ferdios/librealmachine d8ecbb5

Initial commit

Sander committed on 2026-09-04 · d8ecbb5

33 files changed +16301 −0

+ .clang-format
+ .gitignore
+ CMakeLists.txt
+ LICENSE
+ README.md
+ cmake/config-realmachine.h.cmake
+ cmake/realmachineConfig.cmake.in
+ main.cpp
+ src/realmachine/backend.cpp
+ src/realmachine/backend.h
+ src/realmachine/decompressors.cpp
+ src/realmachine/decompressors.h
+ src/realmachine/globals.h
+ src/realmachine/lib/cli11/CLI11.h
+ src/realmachine/lib/cli11/LICENSE
+ src/realmachine/lib/cli11/cli11_wrapper.cpp
+ src/realmachine/lib/cli11/cli11_wrapper.h
+ src/realmachine/lib/utils.cpp
+ src/realmachine/lib/utils.h
+ src/realmachine/machine.cpp
+ src/realmachine/machine.h
+ src/realmachine/models.cpp
+ src/realmachine/models.h
+ src/realmachine/module_cache.cpp
+ src/realmachine/module_cache.h
+ src/realmachine/template.cpp
+ src/realmachine/template.h
+ tests/CMakeLists.txt
+ tests/test
+ tests/test.cpp
+ tests/test.gz
+ tests/test.xz
+ tests/test.zst

commit d8ecbb5048dbe290d7a5c4c9b6d07a70a8f92a04
Author: Sander <sander@sanderf.nl>
Date:   Fri Sep 4 17:28:29 2026 +0300

    Initial commit

diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..a8d8af0
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,55 @@
+# Generated from CLion C/C++ Code Style settings
+---
+Language: Cpp
+BasedOnStyle: LLVM
+AlignConsecutiveAssignments: false
+AlignConsecutiveDeclarations: false
+AlignOperands: true
+AlignTrailingComments: false
+AlwaysBreakTemplateDeclarations: Yes
+BraceWrapping: 
+  AfterCaseLabel: false
+  AfterClass: false
+  AfterControlStatement: false
+  AfterEnum: false
+  AfterFunction: false
+  AfterNamespace: false
+  AfterStruct: false
+  AfterUnion: false
+  AfterExternBlock: false
+  BeforeCatch: false
+  BeforeElse: false
+  BeforeLambdaBody: false
+  BeforeWhile: false
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+BreakBeforeBraces: Custom
+BreakConstructorInitializers: AfterColon
+BreakConstructorInitializersBeforeComma: false
+ColumnLimit: 120
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+IncludeCategories: 
+  - Regex: '^<.*'
+    Priority: 1
+  - Regex: '^".*'
+    Priority: 2
+  - Regex: '.*'
+    Priority: 3
+IncludeIsMainRegex: '([-_](test|unittest))?$'
+IndentCaseLabels: true
+InsertNewlineAtEOF: true
+MacroBlockBegin: ''
+MacroBlockEnd: ''
+MaxEmptyLinesToKeep: 2
+NamespaceIndentation: All
+SpaceAfterCStyleCast: true
+SpaceAfterTemplateKeyword: false
+SpaceBeforeRangeBasedForLoopColon: false
+SpaceInEmptyParentheses: false
+SpacesInAngles: false
+SpacesInConditionalStatement: false
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+TabWidth: 2
+...
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5213fb2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+.idea
+build
+cmake-build-debug
+cmake-build-release
+tests/a.img
+tests/b.img
+tests/test.img
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..b78e7c0
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,161 @@
+cmake_minimum_required(VERSION 3.26)
+project(realmachine VERSION 0.0.17 DESCRIPTION "Boot a transient virtual machine based on the host system")
+
+if(NOT CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    message(FATAL_ERROR "realmachine supports only Linux")
+endif()
+
+include(GNUInstallDirs)
+
+set(REALMACHINE_MAIN_PROJECT OFF)
+if(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
+    set(REALMACHINE_MAIN_PROJECT ON)
+endif()
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+
+option(REALMACHINE_STATIC_LINK "Force -static on the realmachine executable" OFF)
+if(REALMACHINE_STATIC_LINK)
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -static")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -static")
+endif()
+
+option(REALMACHINE_INSTALL "Enable generation of install targets" ${REALMACHINE_MAIN_PROJECT})
+option(REALMACHINE_TESTS "Build tests" OFF)
+
+file(GLOB SOURCE_FILES CONFIGURE_DEPENDS
+        "src/realmachine/*.h"
+        "src/realmachine/*.cpp"
+        "src/realmachine/lib/*.h"
+        "src/realmachine/lib/*.cpp"
+)
+
+find_program(GIT_EXECUTABLE git)
+set(PROJECT_GIT_COMMIT "unknown")
+if(GIT_EXECUTABLE)
+    execute_process(
+            COMMAND ${GIT_EXECUTABLE} rev-parse --short HEAD
+            WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+            OUTPUT_VARIABLE GIT_HEAD
+            OUTPUT_STRIP_TRAILING_WHITESPACE
+            ERROR_QUIET
+    )
+    if(GIT_HEAD)
+        set(PROJECT_GIT_COMMIT "${GIT_HEAD}")
+    endif()
+endif()
+
+configure_file(
+        cmake/config-realmachine.h.cmake
+        ${CMAKE_BINARY_DIR}/src/realmachine/config-realmachine.h
+)
+
+set(ZLIB_USE_STATIC_LIBS ON)
+find_package(ZLIB REQUIRED)
+find_package(PkgConfig REQUIRED)
+find_package(shellescape REQUIRED)
+find_package(cpiocpplame REQUIRED)
+find_package(flogger REQUIRED)
+
+set(ENV{PKG_CONFIG_ALL_STATIC} "1")
+pkg_check_modules(ZSTD REQUIRED libzstd)
+pkg_check_modules(LZMA REQUIRED liblzma)
+
+add_library(realmachine_lib STATIC ${SOURCE_FILES})
+
+target_include_directories(realmachine_lib
+        PUBLIC
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
+        $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
+        ${ZSTD_INCLUDE_DIRS}
+        ${LZMA_INCLUDE_DIRS}
+)
+
+target_link_libraries(realmachine_lib PUBLIC
+        ZLIB::ZLIB
+        ${ZSTD_LIBRARIES}
+        ${LZMA_LIBRARIES}
+        shellescape::shellescape
+        cpiocpplame::cpiocpplame
+        flogger::flogger
+)
+
+set_target_properties(realmachine_lib PROPERTIES
+        OUTPUT_NAME "realmachine"
+        VERSION ${PROJECT_VERSION}
+        SOVERSION ${PROJECT_VERSION_MAJOR}
+)
+
+add_executable(realmachine main.cpp)
+target_sources(realmachine PRIVATE src/realmachine/lib/cli11/cli11_wrapper.cpp)
+target_include_directories(realmachine PRIVATE src/realmachine/lib/cli11)
+
+target_include_directories(realmachine PRIVATE src)
+target_link_libraries(realmachine PRIVATE realmachine_lib)
+
+find_program(STRIP_TOOL strip REQUIRED)
+if(CMAKE_BUILD_TYPE STREQUAL "Release")
+    add_custom_command(TARGET realmachine POST_BUILD
+            COMMAND ${STRIP_TOOL} --strip-unneeded $<TARGET_FILE:realmachine>
+            VERBATIM
+    )
+endif()
+
+if(REALMACHINE_INSTALL)
+    install(FILES ${CMAKE_BINARY_DIR}/src/realmachine/config-realmachine.h
+            DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/
+    )
+
+    file(GLOB realmachine_headers CONFIGURE_DEPENDS
+            src/realmachine/*.h
+            src/realmachine/lib/*.h
+    )
+
+    install(FILES ${realmachine_headers} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/realmachine)
+
+    install(TARGETS realmachine_lib realmachine
+            EXPORT realmachineTargets
+            ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+            RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+            LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+            INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+    )
+
+    install(EXPORT realmachineTargets
+            FILE realmachineTargets.cmake
+            NAMESPACE realmachine::
+            DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/realmachine
+    )
+
+    include(CMakePackageConfigHelpers)
+
+    configure_package_config_file(
+            ${CMAKE_CURRENT_SOURCE_DIR}/cmake/realmachineConfig.cmake.in
+            ${CMAKE_CURRENT_BINARY_DIR}/realmachineConfig.cmake
+            INSTALL_DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/realmachine
+    )
+
+    write_basic_package_version_file(
+            ${CMAKE_CURRENT_BINARY_DIR}/realmachineConfigVersion.cmake
+            VERSION ${PROJECT_VERSION}
+            COMPATIBILITY SameMajorVersion
+    )
+
+    install(FILES
+            ${CMAKE_CURRENT_BINARY_DIR}/realmachineConfig.cmake
+            ${CMAKE_CURRENT_BINARY_DIR}/realmachineConfigVersion.cmake
+            DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/realmachine
+    )
+
+    if(${CMAKE_BUILD_TYPE} STREQUAL Debug)
+        target_compile_definitions(realmachine_lib PRIVATE DEBUG=1)
+        target_compile_definitions(realmachine PRIVATE DEBUG=1)
+    endif()
+endif()
+
+if(BUILD_TESTS)
+    enable_testing()
+    add_subdirectory(tests)
+endif()
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..c98b370
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,201 @@
+                                 Apache License
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diff --git a/README.md b/README.md
new file mode 100644
index 0000000..582d5e6
--- /dev/null
+++ b/README.md
@@ -0,0 +1,116 @@
+# librealmachine - fake a machine
+
+Boot a transient virtual machine based on the host system.
+
+C++ port of the Go project [fakemachine](https://github.com/go-debos/fakemachine/).
+
+Made for [ferdiOS/build-tools](https://codeberg.org/ferdios/build-tools).
+
+### Features
+
+- Mount host volumes into the VM
+- Create and expose disk images
+- Configurable memory, CPU count, and sector size
+- Scratch storage (tmpfs or disk-backed)
+- Environment variable propagation with overrides
+- Command execution inside VM
+- Built-in integration test suite
+- KVM based
+
+## Installation
+
+```bash
+cmake -Bbuild -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr/ .
+sudo make -Cbuild -j4 install
+```
+
+## Dependencies
+
+ferdiOS libraries:
+
+- https://codeberg.org/ferdios/libcpiocpplame
+- https://codeberg.org/ferdios/libflogger
+- https://codeberg.org/ferdios/libshellescape
+
+generic libraries:
+
+`sudo apt install -y pkg-config zlib1g-dev libzstd-dev liblzma-dev libcli11-dev`
+
+### Dependencies: runtime
+
+`sudo apt install -y qemu-system-x86 busybox`
+
+## CMake Integration
+
+After install:
+
+```cmake
+find_package(realmachine REQUIRED)
+target_link_libraries(your_target PRIVATE realmachine::realmachine)
+```
+
+## API usage
+
+See `tests/test.cpp`
+
+`fakemachine::Machine`
+
+Main methods:
+
+- `run(command)`
+- `run_in_machine_with_args(args)`
+- `create_image(path, size)`
+- `add_volume(path)`
+- `add_volume_at(host, guest)`
+- `set_memory(mb)`
+- `set_num_cpus(n)`
+- `set_scratch(size, path)`
+- `set_sector_size(size)`
+- `set_environ(env)`
+
+## CLI Usage
+
+Run a command inside a VM:
+
+```
+realmachine echo hello
+```
+
+Mount a directory:
+
+```
+realmachine -v /host/data:/data ls /data
+```
+
+Create and expose an image:
+
+```
+realmachine -i disk.img:1G bash
+```
+
+Increase memory and CPU count:
+
+```
+realmachine -m 4096 -c 4 bash
+```
+
+Enable verbose boot output:
+
+```
+realmachine --show-boot bash
+```
+
+### Unit tests
+
+```bash
+cmake -Bbuild -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTS=1 .
+sudo make -Cbuild -j4 install
+
+# and run it
+cd tests
+../build/tests/realmachine_tests
+```
+
+## License
+
+Apache 2.0, same as original (fakemachine) project.
\ No newline at end of file
diff --git a/cmake/config-realmachine.h.cmake b/cmake/config-realmachine.h.cmake
new file mode 100644
index 0000000..1e49b5a
--- /dev/null
+++ b/cmake/config-realmachine.h.cmake
@@ -0,0 +1,13 @@
+#pragma once
+#include <string>
+
+namespace realmachine {
+
+inline constexpr std::string_view GENERATED_VERSION = "@CMAKE_PROJECT_VERSION@";
+inline constexpr std::string_view GENERATED_GIT_HEAD = "@GIT_HEAD@";
+
+inline std::string get_generated_version() {
+  return std::string(GENERATED_VERSION) + " (" + std::string(GENERATED_GIT_HEAD) + ")";
+}
+
+}
\ No newline at end of file
diff --git a/cmake/realmachineConfig.cmake.in b/cmake/realmachineConfig.cmake.in
new file mode 100644
index 0000000..d80e8e4
--- /dev/null
+++ b/cmake/realmachineConfig.cmake.in
@@ -0,0 +1,13 @@
+@PACKAGE_INIT@
+
+include(CMakeFindDependencyMacro)
+find_dependency(flogger)
+find_dependency(cpiocpplame)
+find_dependency(shellescape)
+find_dependency(ZLIB)
+find_dependency(PkgConfig)
+pkg_check_modules(ZSTD REQUIRED libzstd)
+pkg_check_modules(LZMA REQUIRED liblzma)
+
+include("${CMAKE_CURRENT_LIST_DIR}/realmachineTargets.cmake")
+check_required_components(realmachine)
\ No newline at end of file
diff --git a/main.cpp b/main.cpp
new file mode 100644
index 0000000..994cb97
--- /dev/null
+++ b/main.cpp
@@ -0,0 +1,249 @@
+#include <iostream>
+#include <string>
+#include <vector>
+#include <unordered_map>
+#include <filesystem>
+#include <cstdlib>
+#include <algorithm>
+
+#include <shellescape/shellescape.h>
+#include <flogger/flogger.h>
+
+#include "src/realmachine/lib/cli11/cli11_wrapper.h"
+#include "src/realmachine/machine.h"
+#include "src/realmachine/backend.h"
+#include "src/realmachine/lib/utils.h"
+
+auto log_main = flogger::bind_log("realmachine/main");
+
+using namespace std;
+
+string version;
+
+// Determine version string similar to Go implementation
+string get_determined_version(const string& v) {
+  if (!v.empty()) return v;
+  return "unknown";
+}
+
+void warn_localhost(const string& variable, const string& value) {
+  if (value.find("localhost") != string::npos ||
+      value.find("127.0.0.1") != string::npos ||
+      value.find("::1") != string::npos) {
+    cerr << "WARNING: Environment variable " << variable << " contains a reference to\n"
+         << "localhost. This may not work when running from realmachine.\n"
+         << "Consider using an address that is valid on your network.\n";
+  }
+}
+
+struct options_t {
+  string backend = "auto";
+  vector<string> volumes;
+  vector<string> images;
+  unordered_map<string,string> environ_vars;
+  int memory = 0;
+  int cpus = 0;
+  int sector_size = 0;
+  string scratch_size;
+  bool show_boot = false;
+  bool quiet = false;
+  bool show_version = false;
+};
+
+void setup_volumes(std::shared_ptr<realmachine::Machine>& m, const options_t& options) {
+  printf_debug(log_main, "setup_volumes start count=%zu", options.volumes.size());
+  for (const auto& v : options.volumes) {
+    printf_debug(log_main, "volume raw=%s", v.c_str());
+    size_t pos = v.find(':');
+    if (pos == string::npos) {
+      printf_debug(log_main, "volume single mount %s", v.c_str());
+      m->add_volume(filesystem::path(v));
+    } else {
+      string a = v.substr(0, pos);
+      string b = v.substr(pos + 1);
+      if (b.find(':') != string::npos) {
+        printf_error(log_main, "Failed to parse volume: %s", v.c_str());
+        exit(1);
+      }
+      printf_debug(log_main, "volume mapping %s -> %s", a.c_str(), b.c_str());
+      m->add_volume_at(filesystem::path(a), filesystem::path(b));
+    }
+  }
+  printf_debug(log_main, "setup_volumes done");
+}
+
+void setup_images(std::shared_ptr<realmachine::Machine>& m, const options_t& options) {
+  printf_debug(log_main, "setup_images start count=%zu", options.images.size());
+
+  for (const auto& i : options.images) {
+    printf_debug(log_main, "image raw=%s", i.c_str());
+
+    const size_t pos = i.find(':');
+    string label;
+
+    try {
+      if (pos == string::npos) {
+        printf_debug(log_main, "image create default size path=%s", i.c_str());
+        label = m->create_image(filesystem::path(i), -1);
+      } else {
+        string name = i.substr(0, pos);
+        string size_str = i.substr(pos + 1);
+
+        printf_debug(log_main, "image create path=%s size_str=%s", name.c_str(), size_str.c_str());
+
+        int64_t size = utils_realmachine::parse_human_size(size_str);
+        printf_debug(log_main, "parsed size=%ld", size);
+
+        label = m->create_image(filesystem::path(name), size);
+      }
+    } catch (const exception& e) {
+      printf_error(log_main, "Failed to create image: %s %s", i.c_str(), e.what());
+      exit(1);
+    }
+
+    if (!options.quiet) {
+      string name = (pos == string::npos) ? i : i.substr(0, pos);
+      printf_debug(log_main, "expose image name=%s label=%s", name.c_str(), label.c_str());
+      cout << "Exposing " << name << " as " << label << "\n";
+    }
+  }
+
+  printf_debug(log_main, "setup_images done");
+}
+
+void setup_environ(std::shared_ptr<realmachine::Machine>& m, const options_t& options) {
+  printf_debug(log_main, "setup_environ start");
+
+  unordered_map<string,string> env;
+
+  vector<string> vars = {
+    "http_proxy","https_proxy","ftp_proxy","rsync_proxy","all_proxy","no_proxy"
+  };
+
+  for (const auto& e : vars) {
+    string lower = e;
+    string upper = e;
+    transform(upper.begin(), upper.end(), upper.begin(), ::toupper);
+
+    printf_debug(log_main, "env probe key=%s", e.c_str());
+
+    const char* lv = getenv(lower.c_str());
+    if (lv && string(lv).size()) {
+      printf_debug(log_main, "env inherit lower=%s", lower.c_str());
+      env[lower] = lv;
+    }
+
+    const char* uv = getenv(upper.c_str());
+    if (uv && string(uv).size()) {
+      printf_debug(log_main, "env inherit upper=%s", upper.c_str());
+      env[upper] = uv;
+    }
+  }
+
+  printf_debug(log_main, "env overrides count=%zu", options.environ_vars.size());
+
+  for (const auto& [k,v] : options.environ_vars) {
+    printf_debug(log_main, "env override key=%s empty=%d", k.c_str(), v.empty());
+    if (v.empty()) env.erase(k);
+    else env[k] = v;
+  }
+
+  vector<string> env_strings;
+  env_strings.reserve(env.size());
+
+  for (const auto& [k,v] : env) {
+    printf_debug(log_main, "env final key=%s", k.c_str());
+    warn_localhost(k, v);
+    env_strings.push_back(k + "=" + v);
+  }
+
+  printf_debug(log_main, "env set count=%zu", env_strings.size());
+  m->set_environ(env_strings);
+  printf_debug(log_main, "setup_environ done");
+}
+
+int main(const int argc, char** argv) {
+  flogger::load_env();
+#ifdef DEBUG
+  flogger::enable_time_measurement(true);
+  flogger::set_log_level(flogger::log_level::trace);
+#endif
+  CLI::App app{"realmachine"};
+
+  options_t options;
+  vector<string> backend_choices = {"auto", "kvm", "qemu"};
+
+  app.add_option("-b,--backend", options.backend)->check(CLI::IsMember(backend_choices));
+  app.add_option("-v,--volume", options.volumes);
+  app.add_option("-i,--image", options.images);
+
+  std::vector<std::string> env_raw;
+  app.add_option("-e,--environ-var", env_raw)->expected(-1);
+
+  CLI11_PARSE(app, argc, argv);
+
+  for (auto& s : env_raw) {
+    auto pos = s.find(':');
+    if (pos == std::string::npos) options.environ_vars[s] = "";
+    else options.environ_vars[s.substr(0,pos)] = s.substr(pos+1);
+  }
+
+  app.add_option("-m,--memory", options.memory);
+  app.add_option("-c,--cpus", options.cpus);
+  app.add_option("-S,--sectorsize", options.sector_size);
+  app.add_option("-s,--scratchsize", options.scratch_size);
+
+  app.add_flag("--show-boot", options.show_boot);
+  app.add_flag("-q,--quiet", options.quiet);
+  app.add_flag("--version", options.show_version);
+
+  vector<string> args;
+  app.add_option("command", args);
+
+  CLI11_PARSE(app, argc, argv);
+
+  if (options.show_version) {
+    cout << "realmachine " << get_determined_version(version) << "\n";
+    return 0;
+  }
+
+  auto m = realmachine::Machine::new_machine_with_backend(options.backend);
+
+  m->set_show_boot(options.show_boot);
+  m->set_quiet(options.quiet);
+
+  setup_volumes(m, options);
+  setup_images(m, options);
+  setup_environ(m, options);
+
+  if (!options.scratch_size.empty()) {
+    try {
+      const int64_t size = utils_realmachine::parse_human_size(options.scratch_size);
+      m->set_scratch(size, "");
+    } catch (const exception& e) {
+      cerr << "realmachine: Couldn't parse scratch size: " << e.what() << "\n";
+      return 1;
+    }
+  }
+
+  if (options.memory > 0)
+    m->set_memory(options.memory);
+  if (options.cpus > 0)
+    m->set_num_cpus(options.cpus);
+  if (options.sector_size > 0)
+    m->set_sector_size(options.sector_size);
+
+  string command = "/bin/bash";
+  if (!args.empty()) {
+    command = shellescape::quote_command(args);
+  }
+
+  int ret = 0;
+  try {
+    ret = m->run(command);
+  } catch (const exception& e) {
+    cerr << "realmachine: " << e.what() << "\n";
+  }
+
+  return ret;
+}
\ No newline at end of file
diff --git a/src/realmachine/backend.cpp b/src/realmachine/backend.cpp
new file mode 100644
index 0000000..a45f988
--- /dev/null
+++ b/src/realmachine/backend.cpp
@@ -0,0 +1,496 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include <cerrno>
+#include <cstring>
+#include <sstream>
+#include <fstream>
+#include <sys/utsname.h>
+#include <sys/wait.h>
+
+#include <flogger/flogger.h>
+#include <shellescape/shellescape.h>
+
+#include "backend.h"
+
+auto log_realmachine_backend = flogger::bind_log("realmachine/backend");
+
+namespace realmachine {
+  std::unique_ptr<Backend> new_qemu_backend(const std::shared_ptr<Machine>& m) {
+    auto b = std::make_unique<QemuBackend>(m);
+    printf_debug(log_realmachine_backend, "new_qemu_backend created");
+    return b;
+  }
+
+  std::unique_ptr<Backend> new_kvm_backend(const std::shared_ptr<Machine>& m) {
+    auto b = std::make_unique<KvmBackend>(m);
+    printf_debug(log_realmachine_backend, "new_kvm_backend created");
+    return b;
+  }
+
+  // List of backends in order of their priority in the "auto" algorithm
+  std::vector<std::unique_ptr<Backend>> implemented_backends(const std::shared_ptr<Machine>& m) {
+    std::vector<std::unique_ptr<Backend>> backends;
+
+    backends.push_back(new_kvm_backend(m));
+    backends.push_back(new_qemu_backend(m));
+    return backends;
+  }
+
+  /* A list of backends which are implemented - sorted in order in which the
+   * "auto" backend chooses them.
+   */
+  std::vector<std::string> backend_names() {
+    std::vector<std::string> names = {"auto"};
+
+    auto backends = implemented_backends(nullptr);
+    for (const auto& backend : backends) {
+      names.push_back(backend->name());
+    }
+
+    return names;
+  }
+
+  /* The "auto" backend loops through each backend, starting with the lowest order.
+   * The backend is created and checked if the creation was successful (i.e. it is
+   * supported on this machine). If so, that backend is used for the realmachine. If
+   * unsuccessful, the next backend is created until no more backends remain then
+   * an error is thrown explaining why each backend was unsuccessful.
+   */
+  std::unique_ptr<Backend> new_backend(const std::string& name, const std::shared_ptr<Machine>& m) {
+    auto backends = implemented_backends(m);
+
+    printf_debug(log_realmachine_backend, "new_backend enter name=%s", name.c_str());
+
+    std::unique_ptr<Backend> b = nullptr;
+
+    if (name == "auto") {
+      std::string combined_errors;
+
+      printf_debug(log_realmachine_backend, "backend_auto start count=%zu", backends.size());
+
+      for (const auto& backend : backends) {
+        std::string backend_name = backend->name();
+
+        printf_debug(log_realmachine_backend, "backend_auto candidate=%s", backend_name.c_str());
+
+        /* The user-mode-linux backend is flaky, don't allow users to auto-select it */
+        if (backend_name == "uml") {
+          printf_debug(log_realmachine_backend, "backend_auto skip_uml");
+          continue;
+        }
+
+        auto candidate = new_backend(backend_name, m);
+        if (!candidate) {
+          if (!combined_errors.empty()) {
+            combined_errors += ", ";
+          }
+          combined_errors += "failed backend: " + backend_name;
+          printf_debug(log_realmachine_backend, "backend_auto failed backend=%s", backend_name.c_str());
+          continue;
+        }
+
+        printf_debug(log_realmachine_backend, "backend_auto selected=%s", backend_name.c_str());
+        return candidate;
+      }
+
+      printf_debug(log_realmachine_backend, "backend_auto exhausted backends errors=%s", combined_errors.c_str());
+      return nullptr;
+    }
+
+    for (auto& backend : backends) {
+      if (backend->name() == name) {
+        printf_debug(log_realmachine_backend, "backend_match name=%s", name.c_str());
+        b = std::move(backend);
+      }
+    }
+
+    if (!b) {
+      printf_debug(log_realmachine_backend, "backend_missing name=%s", name.c_str());
+      throw std::runtime_error(name + " backend does not exist");
+    }
+
+    if (const auto supported = b->supported(); !supported) {
+      printf_debug(log_realmachine_backend, "backend_unsupported name=%s", name.c_str());
+      throw std::runtime_error(name + " backend not supported");
+    }
+
+    printf_debug(log_realmachine_backend, "backend_created name=%s", name.c_str());
+    return b;
+  }
+
+  QemuBackend::QemuBackend(const std::shared_ptr<Machine>& m) : m_machine(m) {}
+
+  std::string QemuBackend::name() const {
+    return "qemu";
+  }
+
+  std::string QemuBackend::qemu_path() const {
+    return "/usr/bin/qemu-system-x86_64";  // @TODO: remove
+    const char* bin = nullptr;
+
+    if (m_machine->arch == Arch::amd64) {
+      bin = qemu_machine_amd64.binary.c_str();
+    } else if (m_machine->arch == Arch::arm64) {
+      bin = qemu_machine_arm64.binary.c_str();
+    } else {
+      printf_debug(log_realmachine_backend, "qemu_path unsupported arch=%d", (int)m_machine->arch);
+      return "";
+    }
+
+    char* resolved = std::getenv("PATH");
+    (void)resolved;
+
+    printf_debug(log_realmachine_backend, "qemu_path bin=%s", bin);
+
+    std::string cmd = std::string("which ") + bin;
+    FILE* pipe = popen(cmd.c_str(), "r");
+    if (!pipe) {
+      printf_debug(log_realmachine_backend, "qemu_path popen_failed cmd=%s", cmd.c_str());
+      return "";
+    }
+
+    char buffer[512];
+    std::string result;
+    if (fgets(buffer, sizeof(buffer), pipe)) {
+      result = buffer;
+    }
+
+    pclose(pipe);
+
+    printf_debug(log_realmachine_backend, "qemu_path raw_result=%s", result.c_str());
+
+    if (result.empty()) {
+      printf_debug(log_realmachine_backend, "qemu_path empty_result");
+      return "";
+    }
+
+    if (!result.empty() && result.back() == '\n') {
+      result.pop_back();
+    }
+
+    printf_debug(log_realmachine_backend, "qemu_path resolved=%s", result.c_str());
+
+    return result;
+  }
+
+  bool QemuBackend::supported() const {
+    const auto path = qemu_path();
+    return !path.empty();
+  }
+
+  std::string QemuBackend::kernel_release() const {
+    /* First try the kernel the current system is running, but if there are no
+     * modules for that try the latest from /lib/modules. The former works best
+     * for systems directly running realmachine, the latter makes sense in docker
+     * environments */
+    struct utsname u {};
+    if (uname(&u) != 0) {
+      return "";
+    }
+
+    std::string release(u.release);
+
+    const std::filesystem::path moddir = "/lib/modules/" + release;
+    if (std::filesystem::exists(moddir))
+      return release;
+
+    const std::filesystem::path base = "/lib/modules";
+    for (auto it = std::filesystem::directory_iterator(base);
+         it != std::filesystem::directory_iterator();
+         ++it) {
+
+      auto name = it->path().filename().string();
+      if (!name.empty() && name[0] >= '0' && name[0] <= '9') {
+        return name;
+      }
+         }
+
+    return "";
+  }
+
+  std::filesystem::path QemuBackend::kernel_path() const {
+    auto moddir = module_path();
+    if (!moddir.empty()) {
+      std::filesystem::path p = moddir / "vmlinuz";
+      if (std::filesystem::exists(p)) {
+        return p;
+      }
+    }
+
+    const auto release = kernel_release();
+    if (release.empty()) {
+      return {};
+    }
+
+    std::filesystem::path p = "/boot/vmlinuz-" + release;
+    if (!std::filesystem::exists(p)) {
+      return {};
+    }
+
+    return p;
+  }
+
+  std::filesystem::path QemuBackend::module_path() const {
+    const auto release = kernel_release();
+    if (release.empty()) {
+      return {};
+    }
+
+    std::filesystem::path base = "/lib/modules";
+    if (merged_usr_system()) {
+      base = "/usr/lib/modules";
+    }
+
+    std::filesystem::path moddir = base / release;
+    if (!std::filesystem::exists(moddir)) {
+      return {};
+    }
+
+    return moddir;
+  }
+
+  std::vector<std::string> QemuBackend::udev_rules() const {
+    std::vector<std::string> rules;
+
+    for (size_t i = 0; i < m_machine->images.size(); i++) {
+      const char drive_letter = 'a' + static_cast<char>(i);
+
+      rules.push_back(
+        "KERNEL==\"vd" + std::string(1, drive_letter) +
+        "\", SYMLINK+=\"disk/by-realmachine-label/" +
+        m_machine->images[i]->label + "\""
+      );
+
+      rules.push_back(
+        "KERNEL==\"vd" + std::string(1, drive_letter) +
+        "[0-9]\", SYMLINK+=\"disk/by-realmachine-label/" +
+        m_machine->images[i]->label + "-part%n\""
+      );
+    }
+
+    return rules;
+  }
+
+  std::string QemuBackend::job_output_tty() const {
+    if (m_machine->show_boot) {
+      return "/dev/console";
+    }
+    return "/dev/hvc0";
+  }
+
+  std::pair<std::string, std::vector<std::string>>
+  QemuBackend::mount_parameters(const std::shared_ptr<MountPoint>& mount) const {
+    return {
+      "9p",
+      {"trans=virtio", "version=9p2000.L", "cache=loose", "msize=262144"}
+    };
+  }
+
+  std::vector<std::string> QemuBackend::init_modules() const {
+    return {"virtio_pci", "virtio_console", "9pnet_virtio", "9p"};
+  }
+
+  std::vector<std::shared_ptr<MountPoint>> QemuBackend::init_static_volumes() const {
+    return {};
+  }
+
+  bool QemuBackend::start() {
+    return start_qemu(false);
+  }
+
+  bool QemuBackend::start_qemu(const bool kvm) {
+    const auto m = m_machine;
+
+    std::string kernel;
+    {
+      auto k = kernel_path();
+      kernel = k.string();
+    }
+
+    std::vector<std::string> args;
+
+    args.emplace_back("qemu-system");
+    args.emplace_back("-smp");
+    args.emplace_back(std::to_string(m->num_cpus));
+    args.emplace_back("-m");
+    args.emplace_back(std::to_string(m->memory));
+    args.emplace_back("-kernel");
+    args.emplace_back(kernel);
+    args.emplace_back("-initrd");
+    args.emplace_back(m->initrd_path.string());
+    args.emplace_back("-display");
+    args.emplace_back("none");
+    args.emplace_back("-nic");
+    args.emplace_back("user,model=virtio-net-pci");
+    args.emplace_back("-no-reboot");
+
+    printf_debug(log_realmachine_backend, "qemu_base cpus=%d mem=%d kernel=%s initrd=%s kvm=%d",
+      m->num_cpus,
+      m->memory,
+      kernel.c_str(),
+      m->initrd_path.string().c_str(),
+      kvm
+    );
+
+    if (kvm) {
+      args.emplace_back("-cpu");
+      args.emplace_back("host");
+      args.emplace_back("-enable-kvm");
+      printf_debug(log_realmachine_backend, "kvm_enabled");
+    }
+
+    std::string console;
+    if (m->arch == Arch::amd64) {
+      console = "ttyS0";
+    } else {
+      console = "ttyAMA0";
+    }
+
+    printf_debug(log_realmachine_backend, "console=%s arch=%d", console.c_str(), (int)m->arch);
+
+    std::vector<std::string> kernelargs = {
+      "console=" + console,
+      "panic=-1",
+      "plymouth.enable=0",
+      "systemd.unit=realmachine.service"
+    };
+
+    if (m->show_boot) {
+      args.emplace_back("-chardev");
+      args.emplace_back("stdio,id=for-ttyS0,signal=off");
+      args.emplace_back("-serial");
+      args.emplace_back("chardev:for-ttyS0");
+      kernelargs.emplace_back("loglevel=7");
+      printf_debug(log_realmachine_backend, "boot_console enabled");
+    } else {
+      args.emplace_back("-device");
+      args.emplace_back("virtio-serial");
+      args.emplace_back("-chardev");
+      args.emplace_back("null,id=for-ttyS0");
+      args.emplace_back("-serial");
+      args.emplace_back("chardev:for-ttyS0");
+      args.emplace_back("-chardev");
+      args.emplace_back("stdio,id=for-hvc0,signal=off");
+      args.emplace_back("-device");
+      args.emplace_back("virtconsole,chardev=for-hvc0");
+      printf_debug(log_realmachine_backend, "boot_console disabled virtio_serial+hvc0");
+    }
+
+    for (const auto& mnt : m->mounts) {
+      args.emplace_back("-virtfs");
+      args.emplace_back(
+        "local,mount_tag=" + mnt->label +
+        ",path=" + mnt->host_directory.string() +
+        ",security_model=none,multidevs=remap"
+      );
+      printf_debug(log_realmachine_backend, "virtfs mount tag=%s path=%s",
+        mnt->label.c_str(),
+        mnt->host_directory.string().c_str()
+      );
+    }
+
+    for (size_t i = 0; i < m->images.size(); i++) {
+      args.emplace_back("-drive");
+      args.emplace_back(
+        "file=" + m->images[i]->path.string() +
+        ",if=none,format=raw,cache=unsafe,id=drive-virtio-disk" + std::to_string(i)
+      );
+
+      args.emplace_back("-device");
+      args.emplace_back(
+        "virtio-blk-pci,drive=drive-virtio-disk" + std::to_string(i) +
+        ",serial=" + m->images[i]->label +
+        ",logical_block_size=" + std::to_string(m->sector_size) +
+        ",physical_block_size=" + std::to_string(m->sector_size)
+      );
+
+      printf_debug(log_realmachine_backend, "drive index=%zu path=%s label=%s",
+        i,
+        m->images[i]->path.string().c_str(),
+        m->images[i]->label.c_str()
+      );
+    }
+
+    std::string append;
+    for (size_t i = 0; i < kernelargs.size(); i++) {
+      if (i) append += " ";
+      append += kernelargs[i];
+    }
+
+    args.emplace_back("-append");
+    args.emplace_back(append);
+
+    printf_debug(log_realmachine_backend, "kernel_append=%s", append.c_str());
+
+    const auto qemu_bin = qemu_path();
+    printf_debug(log_realmachine_backend, "qemu_bin=%s args_count=%zu", qemu_bin.c_str(), args.size());
+
+    const pid_t pid = fork();
+    if (pid == 0) {
+      std::vector<char*> exec_args;
+      for (auto& a : args) {
+        exec_args.emplace_back(const_cast<char*>(a.c_str()));
+      }
+
+      exec_args.emplace_back(nullptr);
+      printf_debug(log_realmachine_backend, "execv qemu_bin=%s args_count=%zu", qemu_bin.c_str(), exec_args.size());
+
+      std::vector<std::string> args;
+      args.reserve(exec_args.size() - 1);
+
+      for (size_t i = 0; i + 1 < exec_args.size(); i++) {
+        args.emplace_back(exec_args[i]);
+      }
+
+      std::string cmd = shellescape::quote_command(args);
+
+      printf_debug(log_realmachine_backend, "execv cmd=%s", cmd.c_str());
+
+      execv(qemu_bin.c_str(), exec_args.data());
+      printf_error(log_realmachine_backend, "execv failed: %s", strerror(errno));
+      _exit(1);
+    }
+
+    printf_debug(log_realmachine_backend, "forked pid=%d", static_cast<int>(pid));
+
+    int status = 0;
+    waitpid(pid, &status, 0);
+
+    printf_debug(log_realmachine_backend, "qemu_exit status=%d exited=%d code=%d",
+      status,
+      WIFEXITED(status),
+      WEXITSTATUS(status)
+    );
+
+    return WIFEXITED(status) && WEXITSTATUS(status) == 0;
+  }
+
+  KvmBackend::KvmBackend(const std::shared_ptr<Machine>& m) : QemuBackend(m) {}
+
+  std::string KvmBackend::name() const {
+    return "kvm";
+  }
+
+  bool KvmBackend::supported() const {
+    int fd = open("/dev/kvm", O_RDWR);
+
+    if (fd < 0) {
+      if (errno == EACCES) {
+        printf_error(log_realmachine_backend, "no permission for /dev/kvm (missing kvm group)");
+        printf_error(log_realmachine_backend, "possible fix (debian/ubuntu): sudo usermod -aG kvm $USER");
+      } else {
+        printf_error(log_realmachine_backend, "failed to open /dev/kvm: %s", strerror(errno));
+      }
+      return false;
+    }
+
+    printf_debug(log_realmachine_backend, "opened /dev/kvm successfully");
+    close(fd);
+
+    return QemuBackend::supported();
+  }
+
+  bool KvmBackend::start() {
+    return start_qemu(true);
+  }
+}
\ No newline at end of file
diff --git a/src/realmachine/backend.h b/src/realmachine/backend.h
new file mode 100644
index 0000000..da07c6c
--- /dev/null
+++ b/src/realmachine/backend.h
@@ -0,0 +1,111 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <filesystem>
+#include <memory>
+#include <utility>
+
+#include "models.h"
+#include "machine.h"
+
+namespace realmachine {
+
+  class Backend {
+  public:
+    virtual ~Backend() = default;
+
+    // The name of the backend
+    [[nodiscard]] virtual std::string name() const = 0;
+
+    // Whether the backend is supported on this machine
+    [[nodiscard]] virtual bool supported() const = 0;
+
+    // Get kernel release version
+    [[nodiscard]] virtual std::string kernel_release() const = 0;
+
+    // The path to the kernel
+    [[nodiscard]] virtual std::filesystem::path kernel_path() const = 0;
+
+    // The path to the modules
+    [[nodiscard]] virtual std::filesystem::path module_path() const = 0;
+
+    // A list of udev rules
+    [[nodiscard]] virtual std::vector<std::string> udev_rules() const = 0;
+
+    // The tty used for the job output
+    [[nodiscard]] virtual std::string job_output_tty() const = 0;
+
+    // The parameters used to mount a specific volume into the machine
+    [[nodiscard]] virtual std::pair<std::string, std::vector<std::string>>
+    mount_parameters(const std::shared_ptr<MountPoint>& mount) const = 0;
+
+    // A list of modules to be added to initrd and probed in the initscript
+    [[nodiscard]] virtual std::vector<std::string> init_modules() const = 0;
+
+    // A list of additional volumes which should be mounted in the initscript
+    [[nodiscard]] virtual std::vector<std::shared_ptr<MountPoint>> init_static_volumes() const = 0;
+
+    // Start an instance of the backend
+    virtual bool start() = 0;
+  };
+
+  // List of backends in order of their priority in the "auto" algorithm
+  std::vector<std::unique_ptr<Backend>> implemented_backends(std::shared_ptr<Machine>& m);
+
+  // A list of backends which are implemented - sorted in order in which the
+  // "auto" backend chooses them.
+  std::vector<std::string> backend_names();
+
+  // The "auto" backend loops through each backend in priority order.
+  // Each backend is instantiated and checked for support on this machine.
+  // The first supported backend is selected.
+  std::unique_ptr<Backend> new_backend(const std::string& name, const std::shared_ptr<Machine>& m);
+
+  class QemuBackend : public Backend {
+  public:
+    explicit QemuBackend(const std::shared_ptr<Machine>& m);
+
+    [[nodiscard]] std::string name() const override;
+
+    [[nodiscard]] bool supported() const override;
+
+    [[nodiscard]] std::string qemu_path() const;
+
+    [[nodiscard]] std::string kernel_release() const override;
+
+    [[nodiscard]] std::filesystem::path kernel_path() const override;
+
+    [[nodiscard]] std::filesystem::path module_path() const override;
+
+    [[nodiscard]] std::vector<std::string> udev_rules() const override;
+
+    [[nodiscard]] std::string job_output_tty() const override;
+
+    [[nodiscard]] std::pair<std::string, std::vector<std::string>>
+    mount_parameters(const std::shared_ptr<MountPoint>& mount) const override;
+
+    [[nodiscard]] std::vector<std::string> init_modules() const override;
+
+    [[nodiscard]] std::vector<std::shared_ptr<MountPoint>> init_static_volumes() const override;
+
+    bool start() override;
+
+    bool start_qemu(bool kvm);
+
+  private:
+    std::shared_ptr<Machine> m_machine;
+  };
+
+  class KvmBackend : public QemuBackend {
+  public:
+    explicit KvmBackend(const std::shared_ptr<Machine>& m);
+
+    [[nodiscard]] std::string name() const override;
+
+    [[nodiscard]] bool supported() const override;
+
+    bool start() override;
+  };
+
+}
\ No newline at end of file
diff --git a/src/realmachine/decompressors.cpp b/src/realmachine/decompressors.cpp
new file mode 100644
index 0000000..4b8c1b2
--- /dev/null
+++ b/src/realmachine/decompressors.cpp
@@ -0,0 +1,135 @@
+#include <istream>
+#include <ostream>
+#include <vector>
+#include <cstring>
+
+#include <zstd.h>
+#include <lzma.h>
+#include <zlib.h>
+
+#include "decompressors.h"
+
+namespace decompressors {
+
+void zstd_decompressor(std::ostream& dst, std::istream& src) {
+  ZSTD_DStream* strm = ZSTD_createDStream();
+  if (!strm) {
+    throw std::runtime_error("zstd: Failed to create ZSTD_DStream");
+  }
+
+  ZSTD_initDStream(strm);
+
+  std::vector<char> in(1 << 16);
+  std::vector<char> out(1 << 16);
+
+  while (src.good()) {
+    src.read(in.data(), in.size());
+    std::streamsize n = src.gcount();
+    if (n <= 0) break;
+
+    ZSTD_inBuffer input{in.data(), static_cast<size_t>(n), 0};
+
+    while (input.pos < input.size) {
+      ZSTD_outBuffer output{out.data(), out.size(), 0};
+
+      size_t ret = ZSTD_decompressStream(strm, &output, &input);
+      if (ZSTD_isError(ret)) {
+        ZSTD_freeDStream(strm);
+        throw std::runtime_error("zstd: ZSTD_isError");
+      }
+
+      dst.write(out.data(), output.pos);
+    }
+  }
+
+  ZSTD_freeDStream(strm);
+}
+
+void xz_decompressor(std::ostream& dst, std::istream& src) {
+  lzma_stream strm = LZMA_STREAM_INIT;
+
+  if (lzma_stream_decoder(&strm, UINT64_MAX, 0) != LZMA_OK) {
+    throw std::runtime_error("xz: lzma_stream_decoder(&strm, UINT64_MAX, 0) != LZMA_OK");
+  }
+
+  std::vector<uint8_t> in_buf(1 << 16);
+  std::vector<uint8_t> out_buf(1 << 16);
+
+  while (true) {
+    if (strm.avail_in == 0 && src.good()) {
+      src.read(reinterpret_cast<char*>(in_buf.data()), in_buf.size());
+      strm.avail_in = static_cast<size_t>(src.gcount());
+      strm.next_in = in_buf.data();
+    }
+
+    strm.avail_out = out_buf.size();
+    strm.next_out = out_buf.data();
+
+    lzma_ret ret = lzma_code(&strm, LZMA_RUN);
+
+    if (ret == LZMA_STREAM_END) {
+      dst.write(reinterpret_cast<char*>(out_buf.data()), out_buf.size() - strm.avail_out);
+      break;
+    }
+
+    if (ret != LZMA_OK && ret != LZMA_BUF_ERROR) {
+      lzma_end(&strm);
+      throw std::runtime_error("xz: ret != LZMA_OK && ret != LZMA_BUF_ERROR");
+    }
+
+    dst.write(reinterpret_cast<char*>(out_buf.data()), out_buf.size() - strm.avail_out);
+  }
+
+  lzma_end(&strm);
+}
+
+void gzip_decompressor(std::ostream& dst, std::istream& src) {
+  z_stream zs{};
+  if (inflateInit2(&zs, 16 + MAX_WBITS) != Z_OK) {
+    throw std::runtime_error("gzip: inflateInit2(&zs, 16 + MAX_WBITS) != Z_OK");
+  }
+
+  std::vector<unsigned char> in(1 << 16);
+  std::vector<unsigned char> out(1 << 16);
+
+  while (true) {
+    if (zs.avail_in == 0 && src.good()) {
+      src.read(reinterpret_cast<char*>(in.data()), in.size());
+      zs.avail_in = static_cast<uInt>(src.gcount());
+      zs.next_in = in.data();
+    }
+
+    zs.avail_out = out.size();
+    zs.next_out = out.data();
+
+    int ret = inflate(&zs, Z_NO_FLUSH);
+
+    if (ret == Z_STREAM_END) {
+      dst.write(reinterpret_cast<char*>(out.data()),
+                out.size() - zs.avail_out);
+      break;
+    }
+
+    if (ret != Z_OK) {
+      inflateEnd(&zs);
+      throw std::runtime_error("gzip: ret != Z_OK");
+    }
+
+    dst.write(reinterpret_cast<char*>(out.data()), out.size() - zs.avail_out);
+  }
+
+  inflateEnd(&zs);
+}
+
+void null_decompressor(std::ostream& dst, std::istream& src) {
+  std::vector<char> buf(1 << 16);
+
+  while (src.good()) {
+    src.read(buf.data(), buf.size());
+    std::streamsize n = src.gcount();
+    if (n <= 0) break;
+    dst.write(buf.data(), n);
+  }
+}
+
+}
\ No newline at end of file
diff --git a/src/realmachine/decompressors.h b/src/realmachine/decompressors.h
new file mode 100644
index 0000000..7eecc09
--- /dev/null
+++ b/src/realmachine/decompressors.h
@@ -0,0 +1,11 @@
+#pragma once
+
+#include <iosfwd>
+#include <system_error>
+
+namespace decompressors {
+  void zstd_decompressor(std::ostream& dst, std::istream& src);
+  void xz_decompressor(std::ostream& dst, std::istream& src);
+  void gzip_decompressor(std::ostream& dst, std::istream& src);
+  void null_decompressor(std::ostream& dst, std::istream& src);
+}
\ No newline at end of file
diff --git a/src/realmachine/globals.h b/src/realmachine/globals.h
new file mode 100644
index 0000000..662d9bf
--- /dev/null
+++ b/src/realmachine/globals.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <optional>
+#include <cstdint>
+#include <variant>
+#include <filesystem>
+
+namespace realmachine_g {
+  enum class log_level {
+    trace = 0,
+    debug,
+    info,
+    error
+  };
+
+  inline bool APP_NO_STATE = false;
+  inline bool APP_THROW_ON_BAD_MOUNTS = true;  // only 'false' during unit-testing
+  inline bool APP_INIT = false;
+  inline std::string APP_ARCH = "x86_64";
+  inline auto current_log_level = log_level::trace;
+}
\ No newline at end of file
diff --git a/src/realmachine/lib/cli11/CLI11.h b/src/realmachine/lib/cli11/CLI11.h
new file mode 100644
index 0000000..4524c54
--- /dev/null
+++ b/src/realmachine/lib/cli11/CLI11.h
@@ -0,0 +1,12216 @@
+// CLI11: Version 2.6.2
+// Originally designed by Henry Schreiner
+// https://github.com/CLIUtils/CLI11
+//
+// This is a standalone header file generated by MakeSingleHeader.py in CLI11/scripts
+// from: v2.6.2
+//
+// CLI11 2.6.2 Copyright (c) 2017-2026 University of Cincinnati, developed by Henry
+// Schreiner under NSF AWARD 1414736. All rights reserved.
+//
+// Redistribution and use in source and binary forms of CLI11, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this
+//    list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+// 3. Neither the name of the copyright holder nor the names of its contributors
+//    may be used to endorse or promote products derived from this software without
+//    specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+// ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once
+
+// Standard combined includes:
+#include <algorithm>
+#include <array>
+#include <cctype>
+#include <clocale>
+#include <cmath>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <cwchar>
+#include <exception>
+#include <fstream>
+#include <functional>
+#include <iomanip>
+#include <iostream>
+#include <iterator>
+#include <limits>
+#include <locale>
+#include <map>
+#include <memory>
+#include <numeric>
+#include <set>
+#include <sstream>
+#include <stdexcept>
+#include <string>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+
+#define CLI11_VERSION_MAJOR 2
+#define CLI11_VERSION_MINOR 6
+#define CLI11_VERSION_PATCH 2
+#define CLI11_VERSION "2.6.2"
+
+
+
+
+// The following version macro is very similar to the one in pybind11
+#if !(defined(_MSC_VER) && __cplusplus == 199711L) && !defined(__INTEL_COMPILER)
+#if __cplusplus >= 201402L
+#define CLI11_CPP14
+#if __cplusplus >= 201703L
+#define CLI11_CPP17
+#if __cplusplus > 201703L
+#define CLI11_CPP20
+#if __cplusplus > 202002L
+#define CLI11_CPP23
+#if __cplusplus > 202302L
+#define CLI11_CPP26
+#endif
+#endif
+#endif
+#endif
+#endif
+#elif defined(_MSC_VER) && __cplusplus == 199711L
+// MSVC sets _MSVC_LANG rather than __cplusplus (supposedly until the standard was fully implemented)
+// Unless you use the /Zc:__cplusplus flag on Visual Studio 2017 15.7 Preview 3 or newer
+#if _MSVC_LANG >= 201402L
+#define CLI11_CPP14
+#if _MSVC_LANG > 201402L && _MSC_VER >= 1910
+#define CLI11_CPP17
+#if _MSVC_LANG > 201703L && _MSC_VER >= 1910
+#define CLI11_CPP20
+#if _MSVC_LANG > 202002L && _MSC_VER >= 1922
+#define CLI11_CPP23
+#endif
+#endif
+#endif
+#endif
+#endif
+
+#if defined(CLI11_CPP14)
+#define CLI11_DEPRECATED(reason) [[deprecated(reason)]]
+#elif defined(_MSC_VER)
+#define CLI11_DEPRECATED(reason) __declspec(deprecated(reason))
+#else
+#define CLI11_DEPRECATED(reason) __attribute__((deprecated(reason)))
+#endif
+
+// GCC < 10 doesn't ignore this in unevaluated contexts
+#if !defined(CLI11_CPP17) ||                                                                                           \
+    (defined(__GNUC__) && !defined(__llvm__) && !defined(__INTEL_COMPILER) && __GNUC__ < 10 && __GNUC__ > 4)
+#define CLI11_NODISCARD
+#else
+#define CLI11_NODISCARD [[nodiscard]]
+#endif
+
+/** detection of rtti */
+#ifndef CLI11_USE_STATIC_RTTI
+#if (defined(_HAS_STATIC_RTTI) && _HAS_STATIC_RTTI)
+#define CLI11_USE_STATIC_RTTI 1
+#elif defined(__cpp_rtti)
+#if (defined(_CPPRTTI) && _CPPRTTI == 0)
+#define CLI11_USE_STATIC_RTTI 1
+#else
+#define CLI11_USE_STATIC_RTTI 0
+#endif
+#elif (defined(__GCC_RTTI) && __GXX_RTTI)
+#define CLI11_USE_STATIC_RTTI 0
+#else
+#define CLI11_USE_STATIC_RTTI 1
+#endif
+#endif
+
+/** <filesystem> availability */
+#if defined CLI11_CPP17 && defined __has_include && !defined CLI11_HAS_FILESYSTEM
+#if __has_include(<filesystem>)
+// Filesystem cannot be used if targeting macOS < 10.15
+#if defined __MAC_OS_X_VERSION_MIN_REQUIRED && __MAC_OS_X_VERSION_MIN_REQUIRED < 101500
+#define CLI11_HAS_FILESYSTEM 0
+#elif defined(__wasi__)
+// As of wasi-sdk-14, filesystem is not implemented
+#define CLI11_HAS_FILESYSTEM 0
+#else
+#include <filesystem>
+#if defined __cpp_lib_filesystem && __cpp_lib_filesystem >= 201703
+#if defined _GLIBCXX_RELEASE && _GLIBCXX_RELEASE >= 9
+#define CLI11_HAS_FILESYSTEM 1
+#elif defined(__GLIBCXX__)
+// if we are using gcc and Version <9 default to no filesystem
+#define CLI11_HAS_FILESYSTEM 0
+#else
+#define CLI11_HAS_FILESYSTEM 1
+#endif
+#else
+#define CLI11_HAS_FILESYSTEM 0
+#endif
+#endif
+#endif
+#endif
+
+/** <codecvt> availability */
+#if !defined(CLI11_CPP26) && !defined(CLI11_HAS_CODECVT)
+#if defined(__GNUC__) && !defined(__llvm__) && !defined(__INTEL_COMPILER) && __GNUC__ < 5
+#define CLI11_HAS_CODECVT 0
+#else
+#define CLI11_HAS_CODECVT 1
+#include <codecvt>
+#endif
+#else
+#if defined(CLI11_HAS_CODECVT)
+#if CLI11_HAS_CODECVT > 0
+#include <codecvt>
+#endif
+#else
+#define CLI11_HAS_CODECVT 0
+#endif
+#endif
+
+/** rtti enabled */
+#ifndef CLI11_HAS_RTTI
+#if defined(__GXX_RTTI) && __GXX_RTTI == 1
+// gcc
+#define CLI11_HAS_RTTI 1
+#elif defined(_CPPRTTI) && _CPPRTTI == 1
+// msvc
+#define CLI11_HAS_RTTI 1
+#elif defined(__NO_RTTI__) && __NO_RTTI__ == 1
+// intel
+#define CLI11_HAS_RTTI 0
+#elif defined(__has_feature)
+// clang and other newer compilers
+#if __has_feature(cxx_rtti)
+#define CLI11_HAS_RTTI 1
+#else
+#define CLI11_HAS_RTTI 0
+#endif
+#elif defined(__RTTI) || defined(__INTEL_RTTI__)
+// more intel and some other compilers
+#define CLI11_HAS_RTTI 1
+#else
+#define CLI11_HAS_RTTI 0
+#endif
+#endif
+
+/** disable deprecations */
+#if defined(__GNUC__)  // GCC or clang
+#define CLI11_DIAGNOSTIC_PUSH _Pragma("GCC diagnostic push")
+#define CLI11_DIAGNOSTIC_POP _Pragma("GCC diagnostic pop")
+
+#define CLI11_DIAGNOSTIC_IGNORE_DEPRECATED _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"")
+
+#elif defined(_MSC_VER)
+#define CLI11_DIAGNOSTIC_PUSH __pragma(warning(push))
+#define CLI11_DIAGNOSTIC_POP __pragma(warning(pop))
+
+#define CLI11_DIAGNOSTIC_IGNORE_DEPRECATED __pragma(warning(disable : 4996))
+
+#else
+#define CLI11_DIAGNOSTIC_PUSH
+#define CLI11_DIAGNOSTIC_POP
+
+#define CLI11_DIAGNOSTIC_IGNORE_DEPRECATED
+
+#endif
+
+/** Inline macro **/
+#ifdef CLI11_COMPILE
+#define CLI11_INLINE
+#else
+#define CLI11_INLINE inline
+#endif
+
+/** Module inline to support module operations**/
+#if defined CLI11_CPP17
+#define CLI11_MODULE_INLINE inline
+#else
+#define CLI11_MODULE_INLINE static
+#endif
+
+
+
+#if defined CLI11_HAS_FILESYSTEM && CLI11_HAS_FILESYSTEM > 0
+#include <filesystem>  // NOLINT(build/include)
+#else
+#include <sys/stat.h>
+#include <sys/types.h>
+#endif
+
+
+
+
+#ifdef CLI11_CPP17
+#include <string_view>
+#endif  // CLI11_CPP17
+
+#if defined CLI11_HAS_FILESYSTEM && CLI11_HAS_FILESYSTEM > 0
+#include <filesystem>
+#include <string_view>  // NOLINT(build/include)
+#endif                  // CLI11_HAS_FILESYSTEM
+
+
+
+#if defined(_WIN32)
+#if !(defined(_AMD64_) || defined(_X86_) || defined(_ARM_))
+#if defined(__amd64__) || defined(__amd64) || defined(__x86_64__) || defined(__x86_64) || defined(_M_X64) ||           \
+    defined(_M_AMD64)
+#define _AMD64_
+#elif defined(i386) || defined(__i386) || defined(__i386__) || defined(__i386__) || defined(_M_IX86)
+#define _X86_
+#elif defined(__arm__) || defined(_M_ARM) || defined(_M_ARMT)
+#define _ARM_
+#elif defined(__aarch64__) || defined(_M_ARM64)
+#define _ARM64_
+#elif defined(_M_ARM64EC)
+#define _ARM64EC_
+#endif
+#endif
+
+// first
+#ifndef NOMINMAX
+// if NOMINMAX is already defined we don't want to mess with that either way
+#define NOMINMAX
+#include <windef.h>
+#undef NOMINMAX
+#else
+#include <windef.h>
+#endif
+
+// second
+#include <winbase.h>
+// third
+#include <processthreadsapi.h>
+#include <shellapi.h>
+#endif
+
+
+namespace CLI {
+
+
+/// Convert a wide string to a narrow string.
+CLI11_INLINE std::string narrow(const std::wstring &str);
+CLI11_INLINE std::string narrow(const wchar_t *str);
+CLI11_INLINE std::string narrow(const wchar_t *str, std::size_t size);
+
+/// Convert a narrow string to a wide string.
+CLI11_INLINE std::wstring widen(const std::string &str);
+CLI11_INLINE std::wstring widen(const char *str);
+CLI11_INLINE std::wstring widen(const char *str, std::size_t size);
+
+#ifdef CLI11_CPP17
+CLI11_INLINE std::string narrow(std::wstring_view str);
+CLI11_INLINE std::wstring widen(std::string_view str);
+#endif  // CLI11_CPP17
+
+#if defined CLI11_HAS_FILESYSTEM && CLI11_HAS_FILESYSTEM > 0
+/// Convert a char-string to a native path correctly.
+CLI11_INLINE std::filesystem::path to_path(std::string_view str);
+#endif  // CLI11_HAS_FILESYSTEM
+
+
+
+
+namespace detail {
+
+#if !CLI11_HAS_CODECVT
+/// Attempt to set one of the acceptable unicode locales for conversion
+CLI11_INLINE void set_unicode_locale() {
+    static const std::array<const char *, 3> unicode_locales{{"C.UTF-8", "en_US.UTF-8", ".UTF-8"}};
+
+    for(const auto &locale_name : unicode_locales) {
+        if(std::setlocale(LC_ALL, locale_name) != nullptr) {
+            return;
+        }
+    }
+    throw std::runtime_error("CLI::narrow: could not set locale to C.UTF-8");
+}
+
+template <typename F> struct scope_guard_t {
+    F closure;
+
+    explicit scope_guard_t(F closure_) : closure(closure_) {}
+    ~scope_guard_t() { closure(); }
+};
+
+template <typename F> CLI11_NODISCARD CLI11_INLINE scope_guard_t<F> scope_guard(F &&closure) {
+    return scope_guard_t<F>{std::forward<F>(closure)};
+}
+
+#endif  // !CLI11_HAS_CODECVT
+
+CLI11_DIAGNOSTIC_PUSH
+CLI11_DIAGNOSTIC_IGNORE_DEPRECATED
+
+CLI11_INLINE std::string narrow_impl(const wchar_t *str, std::size_t str_size) {
+#if CLI11_HAS_CODECVT
+#ifdef _WIN32
+    return std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>>().to_bytes(str, str + str_size);
+
+#else
+    return std::wstring_convert<std::codecvt_utf8<wchar_t>>().to_bytes(str, str + str_size);
+
+#endif  // _WIN32
+#else   // CLI11_HAS_CODECVT
+    (void)str_size;
+    std::mbstate_t state = std::mbstate_t();
+    const wchar_t *it = str;
+
+    std::string old_locale = std::setlocale(LC_ALL, nullptr);
+    auto sg = scope_guard([&] { std::setlocale(LC_ALL, old_locale.c_str()); });
+    set_unicode_locale();
+
+    std::size_t new_size = std::wcsrtombs(nullptr, &it, 0, &state);
+    if(new_size == static_cast<std::size_t>(-1)) {
+        throw std::runtime_error("CLI::narrow: conversion error in std::wcsrtombs at offset " +
+                                 std::to_string(it - str));
+    }
+    std::string result(new_size, '\0');
+    std::wcsrtombs(const_cast<char *>(result.data()), &str, new_size, &state);
+
+    return result;
+
+#endif  // CLI11_HAS_CODECVT
+}
+
+CLI11_INLINE std::wstring widen_impl(const char *str, std::size_t str_size) {
+#if CLI11_HAS_CODECVT
+#ifdef _WIN32
+    return std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>>().from_bytes(str, str + str_size);
+
+#else
+    return std::wstring_convert<std::codecvt_utf8<wchar_t>>().from_bytes(str, str + str_size);
+
+#endif  // _WIN32
+#else   // CLI11_HAS_CODECVT
+    (void)str_size;
+    std::mbstate_t state = std::mbstate_t();
+    const char *it = str;
+
+    std::string old_locale = std::setlocale(LC_ALL, nullptr);
+    auto sg = scope_guard([&] { std::setlocale(LC_ALL, old_locale.c_str()); });
+    set_unicode_locale();
+
+    std::size_t new_size = std::mbsrtowcs(nullptr, &it, 0, &state);
+    if(new_size == static_cast<std::size_t>(-1)) {
+        throw std::runtime_error("CLI::widen: conversion error in std::mbsrtowcs at offset " +
+                                 std::to_string(it - str));
+    }
+    std::wstring result(new_size, L'\0');
+    std::mbsrtowcs(const_cast<wchar_t *>(result.data()), &str, new_size, &state);
+
+    return result;
+
+#endif  // CLI11_HAS_CODECVT
+}
+
+CLI11_DIAGNOSTIC_POP
+
+}  // namespace detail
+
+CLI11_INLINE std::string narrow(const wchar_t *str, std::size_t str_size) { return detail::narrow_impl(str, str_size); }
+CLI11_INLINE std::string narrow(const std::wstring &str) { return detail::narrow_impl(str.data(), str.size()); }
+// Flawfinder: ignore
+CLI11_INLINE std::string narrow(const wchar_t *str) { return detail::narrow_impl(str, std::wcslen(str)); }
+
+CLI11_INLINE std::wstring widen(const char *str, std::size_t str_size) { return detail::widen_impl(str, str_size); }
+CLI11_INLINE std::wstring widen(const std::string &str) { return detail::widen_impl(str.data(), str.size()); }
+// Flawfinder: ignore
+CLI11_INLINE std::wstring widen(const char *str) { return detail::widen_impl(str, std::strlen(str)); }
+
+#ifdef CLI11_CPP17
+CLI11_INLINE std::string narrow(std::wstring_view str) { return detail::narrow_impl(str.data(), str.size()); }
+CLI11_INLINE std::wstring widen(std::string_view str) { return detail::widen_impl(str.data(), str.size()); }
+#endif  // CLI11_CPP17
+
+#if defined CLI11_HAS_FILESYSTEM && CLI11_HAS_FILESYSTEM > 0
+CLI11_INLINE std::filesystem::path to_path(std::string_view str) {
+    return std::filesystem::path{
+#ifdef _WIN32
+        widen(str)
+#else
+        str
+#endif  // _WIN32
+    };
+}
+#endif  // CLI11_HAS_FILESYSTEM
+
+
+
+
+namespace detail {
+#ifdef _WIN32
+/// Decode and return UTF-8 argv from GetCommandLineW.
+CLI11_INLINE std::vector<std::string> compute_win32_argv();
+#endif
+}  // namespace detail
+
+
+
+namespace detail {
+
+#ifdef _WIN32
+CLI11_INLINE std::vector<std::string> compute_win32_argv() {
+    std::vector<std::string> result;
+    int argc = 0;
+
+    auto deleter = [](wchar_t **ptr) { LocalFree(ptr); };
+    // NOLINTBEGIN(*-avoid-c-arrays)
+    auto wargv = std::unique_ptr<wchar_t *[], decltype(deleter)>(CommandLineToArgvW(GetCommandLineW(), &argc), deleter);
+    // NOLINTEND(*-avoid-c-arrays)
+
+    if(wargv == nullptr) {
+        throw std::runtime_error("CommandLineToArgvW failed with code " + std::to_string(GetLastError()));
+    }
+
+    result.reserve(static_cast<size_t>(argc));
+    for(size_t i = 0; i < static_cast<size_t>(argc); ++i) {
+        result.push_back(narrow(wargv[i]));
+    }
+
+    return result;
+}
+#endif
+
+}  // namespace detail
+
+
+
+
+/// Include the items in this namespace to get free conversion of enums to/from streams.
+/// (This is available inside CLI as well, so CLI11 will use this without a using statement).
+namespace enums {
+
+/// output streaming for enumerations
+template <typename T, typename = typename std::enable_if<std::is_enum<T>::value>::type>
+std::ostream &operator<<(std::ostream &in, const T &item) {
+    // make sure this is out of the detail namespace otherwise it won't be found when needed
+    // https://isocpp.org/wiki/faq/input-output#print-char-or-ptr-as-number
+    return in << +static_cast<typename std::underlying_type<T>::type>(item);
+}
+
+}  // namespace enums
+
+/// Export to CLI namespace
+using enums::operator<<;
+
+namespace detail {
+/// a constant defining an expected max vector size defined to be a big number that could be multiplied by 4 and not
+/// produce overflow for some expected uses
+CLI11_MODULE_INLINE constexpr int expected_max_vector_size{1 << 29};
+// Based on http://stackoverflow.com/questions/236129/split-a-string-in-c
+/// Split a string by a delim
+CLI11_INLINE std::vector<std::string> split(const std::string &s, char delim);
+
+/// Simple function to join a string
+template <typename T> std::string join(const T &v, std::string delim = ",") {
+    std::ostringstream s;
+    auto beg = std::begin(v);
+    auto end = std::end(v);
+    if(beg != end)
+        s << *beg++;
+    while(beg != end) {
+        s << delim << *beg++;
+    }
+    auto rval = s.str();
+    if(!rval.empty() && delim.size() == 1 && rval.back() == delim[0]) {
+        // remove trailing delimiter if the last entry was empty
+        rval.pop_back();
+    }
+    return rval;
+}
+
+/// Simple function to join a string from processed elements
+template <typename T,
+          typename Callable,
+          typename = typename std::enable_if<!std::is_constructible<std::string, Callable>::value>::type>
+std::string join(const T &v, Callable func, std::string delim = ",") {
+    std::ostringstream s;
+    auto beg = std::begin(v);
+    auto end = std::end(v);
+    auto loc = s.tellp();
+    while(beg != end) {
+        auto nloc = s.tellp();
+        if(nloc > loc) {
+            s << delim;
+            loc = nloc;
+        }
+        s << func(*beg++);
+    }
+    return s.str();
+}
+
+/// Join a string in reverse order
+template <typename T> std::string rjoin(const T &v, std::string delim = ",") {
+    std::ostringstream s;
+    for(std::size_t start = 0; start < v.size(); start++) {
+        if(start > 0)
+            s << delim;
+        s << v[v.size() - start - 1];
+    }
+    return s.str();
+}
+
+// Based roughly on http://stackoverflow.com/questions/25829143/c-trim-whitespace-from-a-string
+
+/// Trim whitespace from left of string
+CLI11_INLINE std::string &ltrim(std::string &str);
+
+/// Trim anything from left of string
+CLI11_INLINE std::string &ltrim(std::string &str, const std::string &filter);
+
+/// Trim whitespace from right of string
+CLI11_INLINE std::string &rtrim(std::string &str);
+
+/// Trim anything from right of string
+CLI11_INLINE std::string &rtrim(std::string &str, const std::string &filter);
+
+/// Trim whitespace from string
+inline std::string &trim(std::string &str) { return ltrim(rtrim(str)); }
+
+/// Trim anything from string
+inline std::string &trim(std::string &str, const std::string filter) { return ltrim(rtrim(str, filter), filter); }
+
+/// Make a copy of the string and then trim it
+inline std::string trim_copy(const std::string &str) {
+    std::string s = str;
+    return trim(s);
+}
+
+/// remove quotes at the front and back of a string either '"' or '\''
+CLI11_INLINE std::string &remove_quotes(std::string &str);
+
+/// remove quotes from all elements of a string vector and process escaped components
+CLI11_INLINE void remove_quotes(std::vector<std::string> &args);
+
+/// Add a leader to the beginning of all new lines (nothing is added
+/// at the start of the first line). `"; "` would be for ini files
+///
+/// Can't use Regex, or this would be a subs.
+CLI11_INLINE std::string fix_newlines(const std::string &leader, std::string input);
+
+/// Make a copy of the string and then trim it, any filter string can be used (any char in string is filtered)
+inline std::string trim_copy(const std::string &str, const std::string &filter) {
+    std::string s = str;
+    return trim(s, filter);
+}
+
+/// Print subcommand aliases
+CLI11_INLINE std::ostream &format_aliases(std::ostream &out, const std::vector<std::string> &aliases, std::size_t wid);
+
+/// Verify the first character of an option
+/// - is a trigger character, ! has special meaning and new lines would just be annoying to deal with
+template <typename T> bool valid_first_char(T c) {
+    return ((c != '-') && (static_cast<unsigned char>(c) > 33));  // space and '!' not allowed
+}
+
+/// Verify following characters of an option
+template <typename T> bool valid_later_char(T c) {
+    // = and : are value separators, { has special meaning for option defaults,
+    // and control codes other than tab would just be annoying to deal with in many places allowing space here has too
+    // much potential for inadvertent entry errors and bugs
+    return ((c != '=') && (c != ':') && (c != '{') && ((static_cast<unsigned char>(c) > 32) || c == '\t'));
+}
+
+/// Verify an option/subcommand name
+CLI11_INLINE bool valid_name_string(const std::string &str);
+
+/// Verify an app name
+inline bool valid_alias_name_string(const std::string &str) {
+    return ((str.find_first_of('\n') == std::string::npos) && (str.find_first_of('\0') == std::string::npos));
+}
+
+/// check if a string is a container segment separator (empty or "%%")
+inline bool is_separator(const std::string &str) {
+    return (str.empty() || (str.size() == 2 && str[0] == '%' && str[1] == '%'));
+}
+
+/// Verify that str consists of letters only
+inline bool isalpha(const std::string &str) {
+    return std::all_of(str.begin(), str.end(), [](char c) { return std::isalpha(c, std::locale()); });
+}
+
+/// Return a lower case version of a string
+inline std::string to_lower(std::string str) {
+    std::transform(std::begin(str), std::end(str), std::begin(str), [](const std::string::value_type &x) {
+        return std::tolower(x, std::locale());
+    });
+    return str;
+}
+
+/// remove underscores from a string
+inline std::string remove_underscore(std::string str) {
+    str.erase(std::remove(std::begin(str), std::end(str), '_'), std::end(str));
+    return str;
+}
+
+/// @brief  get valid group separators _' + local separator if different
+/// @return a string containing the group separators
+CLI11_INLINE std::string get_group_separators();
+
+/// Find and replace a substring with another substring
+CLI11_INLINE std::string find_and_replace(std::string str, std::string from, std::string to);
+
+/// check if the flag definitions has possible false flags
+inline bool has_default_flag_values(const std::string &flags) {
+    return (flags.find_first_of("{!") != std::string::npos);
+}
+
+CLI11_INLINE void remove_default_flag_values(std::string &flags);
+
+/// Check if a string is a member of a list of strings and optionally ignore case or ignore underscores
+CLI11_INLINE std::ptrdiff_t find_member(std::string name,
+                                        const std::vector<std::string> names,
+                                        bool ignore_case = false,
+                                        bool ignore_underscore = false);
+
+/// Find a trigger string and call a modify callable function that takes the current string and starting position of the
+/// trigger and returns the position in the string to search for the next trigger string
+template <typename Callable> inline std::string find_and_modify(std::string str, std::string trigger, Callable modify) {
+    std::size_t start_pos = 0;
+    while((start_pos = str.find(trigger, start_pos)) != std::string::npos) {
+        start_pos = modify(str, start_pos);
+    }
+    return str;
+}
+
+/// close a sequence of characters indicated by a closure character.  Brackets allows sub sequences
+/// recognized bracket sequences include "'`[(<{  other closure characters are assumed to be literal strings
+CLI11_INLINE std::size_t close_sequence(const std::string &str, std::size_t start, char closure_char);
+
+/// Split a string '"one two" "three"' into 'one two', 'three'
+/// Quote characters can be ` ' or " or bracket characters [{(< with matching to the matching bracket
+CLI11_INLINE std::vector<std::string> split_up(std::string str, char delimiter = '\0');
+
+/// get the value of an environmental variable or empty string if empty
+CLI11_INLINE std::string get_environment_value(const std::string &env_name);
+
+/// This function detects an equal or colon followed by an escaped quote after an argument
+/// then modifies the string to replace the equality with a space.  This is needed
+/// to allow the split up function to work properly and is intended to be used with the find_and_modify function
+/// the return value is the offset+1 which is required by the find_and_modify function.
+CLI11_INLINE std::size_t escape_detect(std::string &str, std::size_t offset);
+
+/// @brief  detect if a string has escapable characters
+/// @param str the string to do the detection on
+/// @return true if the string has escapable characters
+CLI11_INLINE bool has_escapable_character(const std::string &str);
+
+/// @brief escape all escapable characters
+/// @param str the string to escape
+/// @return a string with the escapable characters escaped with '\'
+CLI11_INLINE std::string add_escaped_characters(const std::string &str);
+
+/// @brief replace the escaped characters with their equivalent
+CLI11_INLINE std::string remove_escaped_characters(const std::string &str);
+
+/// generate a string with all non printable characters escaped to hex codes
+CLI11_INLINE std::string binary_escape_string(const std::string &string_to_escape, bool force = false);
+
+CLI11_INLINE bool is_binary_escaped_string(const std::string &escaped_string);
+
+/// extract an escaped binary_string
+CLI11_INLINE std::string extract_binary_string(const std::string &escaped_string);
+
+/// process a quoted string, remove the quotes and if appropriate handle escaped characters
+CLI11_INLINE bool process_quoted_string(std::string &str,
+                                        char string_char = '\"',
+                                        char literal_char = '\'',
+                                        bool disable_secondary_array_processing = false);
+
+/// This function formats the given text as a paragraph with fixed width and applies correct line wrapping
+/// with a custom line prefix. The paragraph will get streamed to the given ostream.
+CLI11_INLINE std::ostream &streamOutAsParagraph(std::ostream &out,
+                                                const std::string &text,
+                                                std::size_t paragraphWidth,
+                                                const std::string &linePrefix = "",
+                                                bool skipPrefixOnFirstLine = false);
+
+}  // namespace detail
+
+
+
+
+namespace detail {
+CLI11_INLINE std::vector<std::string> split(const std::string &s, char delim) {
+    std::vector<std::string> elems;
+    // Check to see if empty string, give consistent result
+    if(s.empty()) {
+        elems.emplace_back();
+    } else {
+        std::stringstream ss;
+        ss.str(s);
+        std::string item;
+        while(std::getline(ss, item, delim)) {
+            elems.push_back(item);
+        }
+    }
+    return elems;
+}
+
+CLI11_INLINE std::string &ltrim(std::string &str) {
+    auto it = std::find_if(str.begin(), str.end(), [](char ch) { return !std::isspace<char>(ch, std::locale()); });
+    str.erase(str.begin(), it);
+    return str;
+}
+
+CLI11_INLINE std::string &ltrim(std::string &str, const std::string &filter) {
+    auto it = std::find_if(str.begin(), str.end(), [&filter](char ch) { return filter.find(ch) == std::string::npos; });
+    str.erase(str.begin(), it);
+    return str;
+}
+
+CLI11_INLINE std::string &rtrim(std::string &str) {
+    auto it = std::find_if(str.rbegin(), str.rend(), [](char ch) { return !std::isspace<char>(ch, std::locale()); });
+    str.erase(it.base(), str.end());
+    return str;
+}
+
+CLI11_INLINE std::string &rtrim(std::string &str, const std::string &filter) {
+    auto it =
+        std::find_if(str.rbegin(), str.rend(), [&filter](char ch) { return filter.find(ch) == std::string::npos; });
+    str.erase(it.base(), str.end());
+    return str;
+}
+
+CLI11_INLINE std::string &remove_quotes(std::string &str) {
+    if(str.length() > 1 && (str.front() == '"' || str.front() == '\'' || str.front() == '`')) {
+        if(str.front() == str.back()) {
+            str.pop_back();
+            str.erase(str.begin(), str.begin() + 1);
+        }
+    }
+    return str;
+}
+
+CLI11_INLINE std::string &remove_outer(std::string &str, char key) {
+    if(str.length() > 1 && (str.front() == key)) {
+        if(str.front() == str.back()) {
+            str.pop_back();
+            str.erase(str.begin(), str.begin() + 1);
+        }
+    }
+    return str;
+}
+
+CLI11_INLINE std::string fix_newlines(const std::string &leader, std::string input) {
+    std::string::size_type n = 0;
+    while(n != std::string::npos && n < input.size()) {
+        n = input.find_first_of("\r\n", n);
+        if(n != std::string::npos) {
+            input = input.substr(0, n + 1) + leader + input.substr(n + 1);
+            n += leader.size();
+        }
+    }
+    return input;
+}
+
+CLI11_INLINE std::ostream &format_aliases(std::ostream &out, const std::vector<std::string> &aliases, std::size_t wid) {
+    if(!aliases.empty()) {
+        out << std::setw(static_cast<int>(wid)) << "     aliases: ";
+        bool front = true;
+        for(const auto &alias : aliases) {
+            if(!front) {
+                out << ", ";
+            } else {
+                front = false;
+            }
+            out << detail::fix_newlines("              ", alias);
+        }
+        out << "\n";
+    }
+    return out;
+}
+
+CLI11_INLINE bool valid_name_string(const std::string &str) {
+    if(str.empty() || !valid_first_char(str[0])) {
+        return false;
+    }
+    auto e = str.end();
+    for(auto c = str.begin() + 1; c != e; ++c)
+        if(!valid_later_char(*c))
+            return false;
+    return true;
+}
+
+CLI11_INLINE std::string get_group_separators() {
+    std::string separators{"_'"};
+#if CLI11_HAS_RTTI != 0
+    char group_separator = std::use_facet<std::numpunct<char>>(std::locale()).thousands_sep();
+    separators.push_back(group_separator);
+#endif
+    return separators;
+}
+
+CLI11_INLINE std::string find_and_replace(std::string str, std::string from, std::string to) {
+
+    std::size_t start_pos = 0;
+
+    while((start_pos = str.find(from, start_pos)) != std::string::npos) {
+        str.replace(start_pos, from.length(), to);
+        start_pos += to.length();
+    }
+
+    return str;
+}
+
+CLI11_INLINE void remove_default_flag_values(std::string &flags) {
+    auto loc = flags.find_first_of('{', 2);
+    while(loc != std::string::npos) {
+        auto finish = flags.find_first_of("},", loc + 1);
+        if((finish != std::string::npos) && (flags[finish] == '}')) {
+            flags.erase(flags.begin() + static_cast<std::ptrdiff_t>(loc),
+                        flags.begin() + static_cast<std::ptrdiff_t>(finish) + 1);
+        }
+        loc = flags.find_first_of('{', loc + 1);
+    }
+    flags.erase(std::remove(flags.begin(), flags.end(), '!'), flags.end());
+}
+
+CLI11_INLINE std::ptrdiff_t
+find_member(std::string name, const std::vector<std::string> names, bool ignore_case, bool ignore_underscore) {
+    auto it = std::end(names);
+    if(ignore_case) {
+        if(ignore_underscore) {
+            name = detail::to_lower(detail::remove_underscore(name));
+            it = std::find_if(std::begin(names), std::end(names), [&name](std::string local_name) {
+                return detail::to_lower(detail::remove_underscore(local_name)) == name;
+            });
+        } else {
+            name = detail::to_lower(name);
+            it = std::find_if(std::begin(names), std::end(names), [&name](std::string local_name) {
+                return detail::to_lower(local_name) == name;
+            });
+        }
+
+    } else if(ignore_underscore) {
+        name = detail::remove_underscore(name);
+        it = std::find_if(std::begin(names), std::end(names), [&name](std::string local_name) {
+            return detail::remove_underscore(local_name) == name;
+        });
+    } else {
+        it = std::find(std::begin(names), std::end(names), name);
+    }
+
+    return (it != std::end(names)) ? (it - std::begin(names)) : (-1);
+}
+
+CLI11_MODULE_INLINE const std::string &escapedChars("\b\t\n\f\r\"\\");
+CLI11_MODULE_INLINE const std::string &escapedCharsCode("btnfr\"\\");
+CLI11_MODULE_INLINE const std::string &bracketChars("\"'`[(<{");
+CLI11_MODULE_INLINE const std::string &matchBracketChars("\"'`])>}");
+
+CLI11_INLINE bool has_escapable_character(const std::string &str) {
+    return (str.find_first_of(escapedChars) != std::string::npos);
+}
+
+CLI11_INLINE std::string add_escaped_characters(const std::string &str) {
+    std::string out;
+    out.reserve(str.size() + 4);
+    for(char s : str) {
+        auto sloc = escapedChars.find_first_of(s);
+        if(sloc != std::string::npos) {
+            out.push_back('\\');
+            out.push_back(escapedCharsCode[sloc]);
+        } else {
+            out.push_back(s);
+        }
+    }
+    return out;
+}
+
+CLI11_INLINE std::uint32_t hexConvert(char hc) {
+    int hcode{0};
+    if(hc >= '0' && hc <= '9') {
+        hcode = (hc - '0');
+    } else if(hc >= 'A' && hc <= 'F') {
+        hcode = (hc - 'A' + 10);
+    } else if(hc >= 'a' && hc <= 'f') {
+        hcode = (hc - 'a' + 10);
+    } else {
+        hcode = -1;
+    }
+    return static_cast<uint32_t>(hcode);
+}
+
+CLI11_INLINE char make_char(std::uint32_t code) { return static_cast<char>(static_cast<unsigned char>(code)); }
+
+CLI11_INLINE void append_codepoint(std::string &str, std::uint32_t code) {
+    if(code < 0x80) {  // ascii code equivalent
+        str.push_back(static_cast<char>(code));
+    } else if(code < 0x800) {  // \u0080 to \u07FF
+        // 110yyyyx 10xxxxxx; 0x3f == 0b0011'1111
+        str.push_back(make_char(0xC0 | code >> 6));
+        str.push_back(make_char(0x80 | (code & 0x3F)));
+    } else if(code < 0x10000) {  // U+0800...U+FFFF
+        if(0xD800 <= code && code <= 0xDFFF) {
+            throw std::invalid_argument("[0xD800, 0xDFFF] are not valid UTF-8.");
+        }
+        // 1110yyyy 10yxxxxx 10xxxxxx
+        str.push_back(make_char(0xE0 | code >> 12));
+        str.push_back(make_char(0x80 | (code >> 6 & 0x3F)));
+        str.push_back(make_char(0x80 | (code & 0x3F)));
+    } else if(code < 0x110000) {  // U+010000 ... U+10FFFF
+        // 11110yyy 10yyxxxx 10xxxxxx 10xxxxxx
+        str.push_back(make_char(0xF0 | code >> 18));
+        str.push_back(make_char(0x80 | (code >> 12 & 0x3F)));
+        str.push_back(make_char(0x80 | (code >> 6 & 0x3F)));
+        str.push_back(make_char(0x80 | (code & 0x3F)));
+    }
+}
+
+CLI11_INLINE std::string remove_escaped_characters(const std::string &str) {
+
+    std::string out;
+    out.reserve(str.size());
+    for(auto loc = str.begin(); loc < str.end(); ++loc) {
+        if(*loc == '\\') {
+            if(str.end() - loc < 2) {
+                throw std::invalid_argument("invalid escape sequence " + str);
+            }
+            auto ecloc = escapedCharsCode.find_first_of(*(loc + 1));
+            if(ecloc != std::string::npos) {
+                out.push_back(escapedChars[ecloc]);
+                ++loc;
+            } else if(*(loc + 1) == 'u') {
+                // must have 4 hex characters
+                if(str.end() - loc < 6) {
+                    throw std::invalid_argument("unicode sequence must have 4 hex codes " + str);
+                }
+                std::uint32_t code{0};
+                std::uint32_t mplier{16 * 16 * 16};
+                for(int ii = 2; ii < 6; ++ii) {
+                    std::uint32_t res = hexConvert(*(loc + ii));
+                    if(res > 0x0F) {
+                        throw std::invalid_argument("unicode sequence must have 4 hex codes " + str);
+                    }
+                    code += res * mplier;
+                    mplier = mplier / 16;
+                }
+                append_codepoint(out, code);
+                loc += 5;
+            } else if(*(loc + 1) == 'U') {
+                // must have 8 hex characters
+                if(str.end() - loc < 10) {
+                    throw std::invalid_argument("unicode sequence must have 8 hex codes " + str);
+                }
+                std::uint32_t code{0};
+                std::uint32_t mplier{16 * 16 * 16 * 16 * 16 * 16 * 16};
+                for(int ii = 2; ii < 10; ++ii) {
+                    std::uint32_t res = hexConvert(*(loc + ii));
+                    if(res > 0x0F) {
+                        throw std::invalid_argument("unicode sequence must have 8 hex codes " + str);
+                    }
+                    code += res * mplier;
+                    mplier = mplier / 16;
+                }
+                append_codepoint(out, code);
+                loc += 9;
+            } else if(*(loc + 1) == '0') {
+                out.push_back('\0');
+                ++loc;
+            } else {
+                throw std::invalid_argument(std::string("unrecognized escape sequence \\") + *(loc + 1) + " in " + str);
+            }
+        } else {
+            out.push_back(*loc);
+        }
+    }
+    return out;
+}
+
+CLI11_INLINE std::size_t close_string_quote(const std::string &str, std::size_t start, char closure_char) {
+    std::size_t loc{0};
+    for(loc = start + 1; loc < str.size(); ++loc) {
+        if(str[loc] == closure_char) {
+            break;
+        }
+        if(str[loc] == '\\') {
+            // skip the next character for escaped sequences
+            ++loc;
+        }
+    }
+    return loc;
+}
+
+CLI11_INLINE std::size_t close_literal_quote(const std::string &str, std::size_t start, char closure_char) {
+    auto loc = str.find_first_of(closure_char, start + 1);
+    return (loc != std::string::npos ? loc : str.size());
+}
+
+CLI11_INLINE std::size_t close_sequence(const std::string &str, std::size_t start, char closure_char) {
+
+    auto bracket_loc = matchBracketChars.find(closure_char);
+    switch(bracket_loc) {
+    case 0:
+        return close_string_quote(str, start, closure_char);
+    case 1:
+    case 2:
+#if defined(_MSC_VER) && _MSC_VER < 1920
+    case(std::size_t)-1:
+#else
+    case std::string::npos:
+#endif
+        return close_literal_quote(str, start, closure_char);
+    default:
+        break;
+    }
+
+    std::string closures(1, closure_char);
+    auto loc = start + 1;
+
+    while(loc < str.size()) {
+        if(str[loc] == closures.back()) {
+            closures.pop_back();
+            if(closures.empty()) {
+                return loc;
+            }
+        }
+        bracket_loc = bracketChars.find(str[loc]);
+        if(bracket_loc != std::string::npos) {
+            switch(bracket_loc) {
+            case 0:
+                loc = close_string_quote(str, loc, str[loc]);
+                break;
+            case 1:
+            case 2:
+                loc = close_literal_quote(str, loc, str[loc]);
+                break;
+            default:
+                closures.push_back(matchBracketChars[bracket_loc]);
+                break;
+            }
+        }
+        ++loc;
+    }
+    if(loc > str.size()) {
+        loc = str.size();
+    }
+    return loc;
+}
+
+CLI11_INLINE std::vector<std::string> split_up(std::string str, char delimiter) {
+
+    auto find_ws = [delimiter](char ch) {
+        return (delimiter == '\0') ? std::isspace<char>(ch, std::locale()) : (ch == delimiter);
+    };
+    trim(str);
+
+    std::vector<std::string> output;
+    while(!str.empty()) {
+        if(bracketChars.find_first_of(str[0]) != std::string::npos) {
+            auto bracketLoc = bracketChars.find_first_of(str[0]);
+            auto end = close_sequence(str, 0, matchBracketChars[bracketLoc]);
+            if(end >= str.size()) {
+                output.push_back(std::move(str));
+                str.clear();
+            } else {
+                output.push_back(str.substr(0, end + 1));
+                if(end + 2 < str.size()) {
+                    str = str.substr(end + 2);
+                } else {
+                    str.clear();
+                }
+            }
+
+        } else {
+            auto it = std::find_if(std::begin(str), std::end(str), find_ws);
+            if(it != std::end(str)) {
+                std::string value = std::string(str.begin(), it);
+                output.push_back(value);
+                str = std::string(it + 1, str.end());
+            } else {
+                output.push_back(str);
+                str.clear();
+            }
+        }
+        trim(str);
+    }
+    return output;
+}
+
+CLI11_INLINE std::size_t escape_detect(std::string &str, std::size_t offset) {
+    auto next = str[offset + 1];
+    if((next == '\"') || (next == '\'') || (next == '`')) {
+        auto astart = str.find_last_of("-/ \"\'`", offset - 1);
+        if(astart != std::string::npos) {
+            if(str[astart] == ((str[offset] == '=') ? '-' : '/'))
+                str[offset] = ' ';  // interpret this as a space so the split_up works properly
+        }
+    }
+    return offset + 1;
+}
+
+CLI11_INLINE std::string binary_escape_string(const std::string &string_to_escape, bool force) {
+    // s is our escaped output string
+    std::string escaped_string{};
+    // loop through all characters
+    for(char c : string_to_escape) {
+        // check if a given character is printable
+        // the cast is necessary to avoid undefined behaviour
+        if(isprint(static_cast<unsigned char>(c)) == 0) {
+            std::stringstream stream;
+            // if the character is not printable
+            // we'll convert it to a hex string using a stringstream
+            // note that since char is signed we have to cast it to unsigned first
+            stream << std::hex << static_cast<unsigned int>(static_cast<unsigned char>(c));
+            std::string code = stream.str();
+            escaped_string += std::string("\\x") + (code.size() < 2 ? "0" : "") + code;
+        } else if(c == 'x' || c == 'X') {
+            // need to check for inadvertent binary sequences
+            if(!escaped_string.empty() && escaped_string.back() == '\\') {
+                escaped_string += std::string("\\x") + (c == 'x' ? "78" : "58");
+            } else {
+                escaped_string.push_back(c);
+            }
+
+        } else {
+            escaped_string.push_back(c);
+        }
+    }
+    if(escaped_string != string_to_escape || force) {
+        auto sqLoc = escaped_string.find('\'');
+        while(sqLoc != std::string::npos) {
+            escaped_string[sqLoc] = '\\';
+            escaped_string.insert(sqLoc + 1, "x27");
+            sqLoc = escaped_string.find('\'');
+        }
+        escaped_string.insert(0, "'B\"(");
+        escaped_string.push_back(')');
+        escaped_string.push_back('"');
+        escaped_string.push_back('\'');
+    }
+    return escaped_string;
+}
+
+CLI11_INLINE bool is_binary_escaped_string(const std::string &escaped_string) {
+    size_t ssize = escaped_string.size();
+    if(escaped_string.compare(0, 3, "B\"(") == 0 && escaped_string.compare(ssize - 2, 2, ")\"") == 0) {
+        return true;
+    }
+    return (escaped_string.compare(0, 4, "'B\"(") == 0 && escaped_string.compare(ssize - 3, 3, ")\"'") == 0);
+}
+
+CLI11_INLINE std::string extract_binary_string(const std::string &escaped_string) {
+    std::size_t start{0};
+    std::size_t tail{0};
+    size_t ssize = escaped_string.size();
+    if(escaped_string.compare(0, 3, "B\"(") == 0 && escaped_string.compare(ssize - 2, 2, ")\"") == 0) {
+        start = 3;
+        tail = 2;
+    } else if(escaped_string.compare(0, 4, "'B\"(") == 0 && escaped_string.compare(ssize - 3, 3, ")\"'") == 0) {
+        start = 4;
+        tail = 3;
+    }
+
+    if(start == 0) {
+        return escaped_string;
+    }
+    std::string outstring;
+
+    outstring.reserve(ssize - start - tail);
+    std::size_t loc = start;
+    while(loc < ssize - tail) {
+        // ssize-2 to skip )" at the end
+        if(escaped_string[loc] == '\\' && (escaped_string[loc + 1] == 'x' || escaped_string[loc + 1] == 'X')) {
+            auto c1 = escaped_string[loc + 2];
+            auto c2 = escaped_string[loc + 3];
+
+            std::uint32_t res1 = hexConvert(c1);
+            std::uint32_t res2 = hexConvert(c2);
+            if(res1 <= 0x0F && res2 <= 0x0F) {
+                loc += 4;
+                outstring.push_back(static_cast<char>(res1 * 16 + res2));
+                continue;
+            }
+        }
+        outstring.push_back(escaped_string[loc]);
+        ++loc;
+    }
+    return outstring;
+}
+
+CLI11_INLINE void remove_quotes(std::vector<std::string> &args) {
+    for(auto &arg : args) {
+        if(arg.front() == '\"' && arg.back() == '\"') {
+            remove_quotes(arg);
+            // only remove escaped for string arguments not literal strings
+            arg = remove_escaped_characters(arg);
+        } else {
+            remove_quotes(arg);
+        }
+    }
+}
+
+CLI11_INLINE void handle_secondary_array(std::string &str) {
+    if(str.size() >= 2 && str.front() == '[' && str.back() == ']') {
+        // handle some special array processing for arguments if it might be interpreted as a secondary array
+        std::string tstr{"[["};
+        for(std::size_t ii = 1; ii < str.size(); ++ii) {
+            tstr.push_back(str[ii]);
+            tstr.push_back(str[ii]);
+        }
+        str = std::move(tstr);
+    }
+}
+
+CLI11_INLINE bool
+process_quoted_string(std::string &str, char string_char, char literal_char, bool disable_secondary_array_processing) {
+    if(str.size() <= 1) {
+        return false;
+    }
+    if(detail::is_binary_escaped_string(str)) {
+        str = detail::extract_binary_string(str);
+        if(!disable_secondary_array_processing)
+            handle_secondary_array(str);
+        return true;
+    }
+    if(str.front() == string_char && str.back() == string_char) {
+        detail::remove_outer(str, string_char);
+        if(str.find_first_of('\\') != std::string::npos) {
+            str = detail::remove_escaped_characters(str);
+        }
+        if(!disable_secondary_array_processing)
+            handle_secondary_array(str);
+        return true;
+    }
+    if((str.front() == literal_char || str.front() == '`') && str.back() == str.front()) {
+        detail::remove_outer(str, str.front());
+        if(!disable_secondary_array_processing)
+            handle_secondary_array(str);
+        return true;
+    }
+    return false;
+}
+
+std::string get_environment_value(const std::string &env_name) {
+    std::string ename_string;
+
+#ifdef _MSC_VER
+    // Windows version
+    char *buffer = nullptr;
+    std::size_t sz = 0;
+    if(_dupenv_s(&buffer, &sz, env_name.c_str()) == 0 && buffer != nullptr) {
+        ename_string = std::string(buffer);
+        free(buffer);
+    }
+#else
+    // This also works on Windows, but gives a warning
+
+    // MISRA static analysis need. MISRACPP2023-25_5_2-a-1
+    const char *buffer = nullptr;
+    buffer = std::getenv(env_name.c_str());
+    if(buffer != nullptr) {
+        ename_string = std::string(buffer);
+    }
+#endif
+    return ename_string;
+}
+
+CLI11_INLINE std::ostream &streamOutAsParagraph(std::ostream &out,
+                                                const std::string &text,
+                                                std::size_t paragraphWidth,
+                                                const std::string &linePrefix,
+                                                bool skipPrefixOnFirstLine) {
+    if(!skipPrefixOnFirstLine)
+        out << linePrefix;  // First line prefix
+
+    std::istringstream lss(text);
+    std::string line = "";
+    while(std::getline(lss, line)) {
+        std::istringstream iss(line);
+        std::string word = "";
+        std::size_t charsWritten = 0;
+
+        while(iss >> word) {
+            if(charsWritten > 0 && (word.length() + 1 + charsWritten > paragraphWidth)) {
+                out << '\n' << linePrefix;
+                charsWritten = 0;
+            }
+            if(charsWritten == 0) {
+                out << word;
+                charsWritten += word.length();
+            } else {
+                out << ' ' << word;
+                charsWritten += word.length() + 1;
+            }
+        }
+
+        if(!lss.eof())
+            out << '\n' << linePrefix;
+    }
+    return out;
+}
+
+}  // namespace detail
+
+
+
+// Use one of these on all error classes.
+// These are temporary and are undef'd at the end of this file.
+#define CLI11_ERROR_DEF(parent, name)                                                                                  \
+  protected:                                                                                                           \
+    name(std::string ename, std::string msg, int exit_code) : parent(std::move(ename), std::move(msg), exit_code) {}   \
+    name(std::string ename, std::string msg, ExitCodes exit_code)                                                      \
+        : parent(std::move(ename), std::move(msg), exit_code) {}                                                       \
+                                                                                                                       \
+  public:                                                                                                              \
+    name(std::string msg, ExitCodes exit_code) : parent(#name, std::move(msg), exit_code) {}                           \
+    name(std::string msg, int exit_code) : parent(#name, std::move(msg), exit_code) {}
+
+// This is added after the one above if a class is used directly and builds its own message
+#define CLI11_ERROR_SIMPLE(name)                                                                                       \
+    explicit name(std::string msg) : name(#name, msg, ExitCodes::name) {}
+
+/// These codes are part of every error in CLI. They can be obtained from e using e.exit_code or as a quick shortcut,
+/// int values from e.get_error_code().
+enum class ExitCodes : int {
+    Success = 0,
+    IncorrectConstruction = 100,
+    BadNameString,
+    OptionAlreadyAdded,
+    FileError,
+    ConversionError,
+    ValidationError,
+    RequiredError,
+    RequiresError,
+    ExcludesError,
+    ExtrasError,
+    ConfigError,
+    InvalidError,
+    HorribleError,
+    OptionNotFound,
+    ArgumentMismatch,
+    BaseClass = 127
+};
+
+// Error definitions
+
+/// @defgroup error_group Errors
+/// @brief Errors thrown by CLI11
+///
+/// These are the errors that can be thrown. Some of them, like CLI::Success, are not really errors.
+/// @{
+
+/// All errors derive from this one
+class Error : public std::runtime_error {
+    int actual_exit_code;
+    std::string error_name{"Error"};
+
+  public:
+    CLI11_NODISCARD int get_exit_code() const { return actual_exit_code; }
+
+    CLI11_NODISCARD std::string get_name() const { return error_name; }
+
+    Error(std::string name, std::string msg, int exit_code = static_cast<int>(ExitCodes::BaseClass))
+        : runtime_error(msg), actual_exit_code(exit_code), error_name(std::move(name)) {}
+
+    Error(std::string name, std::string msg, ExitCodes exit_code) : Error(name, msg, static_cast<int>(exit_code)) {}
+};
+
+// Note: Using Error::Error constructors does not work on GCC 4.7
+
+/// Construction errors (not in parsing)
+class ConstructionError : public Error {
+    CLI11_ERROR_DEF(Error, ConstructionError)
+};
+
+/// Thrown when an option is set to conflicting values (non-vector and multi args, for example)
+class IncorrectConstruction : public ConstructionError {
+    CLI11_ERROR_DEF(ConstructionError, IncorrectConstruction)
+    CLI11_ERROR_SIMPLE(IncorrectConstruction)
+    static IncorrectConstruction PositionalFlag(std::string name) {
+        return IncorrectConstruction(name + ": Flags cannot be positional");
+    }
+    static IncorrectConstruction Set0Opt(std::string name) {
+        return IncorrectConstruction(name + ": Cannot set 0 expected, use a flag instead");
+    }
+    static IncorrectConstruction SetFlag(std::string name) {
+        return IncorrectConstruction(name + ": Cannot set an expected number for flags");
+    }
+    static IncorrectConstruction ChangeNotVector(std::string name) {
+        return IncorrectConstruction(name + ": You can only change the expected arguments for vectors");
+    }
+    static IncorrectConstruction AfterMultiOpt(std::string name) {
+        return IncorrectConstruction(
+            name + ": You can't change expected arguments after you've changed the multi option policy!");
+    }
+    static IncorrectConstruction MissingOption(std::string name) {
+        return IncorrectConstruction("Option " + name + " is not defined");
+    }
+    static IncorrectConstruction MultiOptionPolicy(std::string name) {
+        return IncorrectConstruction(name + ": multi_option_policy only works for flags and exact value options");
+    }
+};
+
+/// Thrown on construction of a bad name
+class BadNameString : public ConstructionError {
+    CLI11_ERROR_DEF(ConstructionError, BadNameString)
+    CLI11_ERROR_SIMPLE(BadNameString)
+    static BadNameString OneCharName(std::string name) { return BadNameString("Invalid one char name: " + name); }
+    static BadNameString MissingDash(std::string name) {
+        return BadNameString("Long names strings require 2 dashes " + name);
+    }
+    static BadNameString BadLongName(std::string name) { return BadNameString("Bad long name: " + name); }
+    static BadNameString BadPositionalName(std::string name) {
+        return BadNameString("Invalid positional Name: " + name);
+    }
+    static BadNameString ReservedName(std::string name) {
+        return BadNameString("Names '-','--','++' are reserved and not allowed as option names " + name);
+    }
+    static BadNameString MultiPositionalNames(std::string name) {
+        return BadNameString("Only one positional name allowed, remove: " + name);
+    }
+};
+
+/// Thrown when an option already exists
+class OptionAlreadyAdded : public ConstructionError {
+    CLI11_ERROR_DEF(ConstructionError, OptionAlreadyAdded)
+    explicit OptionAlreadyAdded(std::string name)
+        : OptionAlreadyAdded(name + " is already added", ExitCodes::OptionAlreadyAdded) {}
+    static OptionAlreadyAdded Requires(std::string name, std::string other) {
+        return {name + " requires " + other, ExitCodes::OptionAlreadyAdded};
+    }
+    static OptionAlreadyAdded Excludes(std::string name, std::string other) {
+        return {name + " excludes " + other, ExitCodes::OptionAlreadyAdded};
+    }
+};
+
+// Parsing errors
+
+/// Anything that can error in Parse
+class ParseError : public Error {
+    CLI11_ERROR_DEF(Error, ParseError)
+};
+
+// Not really "errors"
+
+/// This is a successful completion on parsing, supposed to exit
+class Success : public ParseError {
+    CLI11_ERROR_DEF(ParseError, Success)
+    Success() : Success("Successfully completed, should be caught and quit", ExitCodes::Success) {}
+};
+
+/// -h or --help on command line
+class CallForHelp : public Success {
+    CLI11_ERROR_DEF(Success, CallForHelp)
+    CallForHelp() : CallForHelp("This should be caught in your main function, see examples", ExitCodes::Success) {}
+};
+
+/// Usually something like --help-all on command line
+class CallForAllHelp : public Success {
+    CLI11_ERROR_DEF(Success, CallForAllHelp)
+    CallForAllHelp()
+        : CallForAllHelp("This should be caught in your main function, see examples", ExitCodes::Success) {}
+};
+
+/// -v or --version on command line
+class CallForVersion : public Success {
+    CLI11_ERROR_DEF(Success, CallForVersion)
+    CallForVersion()
+        : CallForVersion("This should be caught in your main function, see examples", ExitCodes::Success) {}
+};
+
+/// Does not output a diagnostic in CLI11_PARSE, but allows main() to return with a specific error code.
+class RuntimeError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, RuntimeError)
+    explicit RuntimeError(int exit_code = 1) : RuntimeError("Runtime error", exit_code) {}
+};
+
+/// Thrown when parsing an INI file and it is missing
+class FileError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, FileError)
+    CLI11_ERROR_SIMPLE(FileError)
+    static FileError Missing(std::string name) { return FileError(name + " was not readable (missing?)"); }
+};
+
+/// Thrown when conversion call back fails, such as when an int fails to coerce to a string
+class ConversionError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, ConversionError)
+    CLI11_ERROR_SIMPLE(ConversionError)
+    ConversionError(std::string member, std::string name)
+        : ConversionError("The value " + member + " is not an allowed value for " + name) {}
+    ConversionError(std::string name, std::vector<std::string> results)
+        : ConversionError("Could not convert: " + name + " = " + detail::join(results)) {}
+    static ConversionError TooManyInputsFlag(std::string name) {
+        return ConversionError(name + ": too many inputs for a flag");
+    }
+    static ConversionError TrueFalse(std::string name) {
+        return ConversionError(name + ": Should be true/false or a number");
+    }
+};
+
+/// Thrown when validation of results fails
+class ValidationError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, ValidationError)
+    CLI11_ERROR_SIMPLE(ValidationError)
+    explicit ValidationError(std::string name, std::string msg) : ValidationError(name + ": " + msg) {}
+};
+
+/// Thrown when a required option is missing
+class RequiredError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, RequiredError)
+    explicit RequiredError(std::string name) : RequiredError(name + " is required", ExitCodes::RequiredError) {}
+    static RequiredError Subcommand(std::size_t min_subcom) {
+        if(min_subcom == 1) {
+            return RequiredError("A subcommand");
+        }
+        return {"Requires at least " + std::to_string(min_subcom) + " subcommands", ExitCodes::RequiredError};
+    }
+    static RequiredError
+    Option(std::size_t min_option, std::size_t max_option, std::size_t used, const std::string &option_list) {
+        if((min_option == 1) && (max_option == 1) && (used == 0))
+            return RequiredError("Exactly 1 option from [" + option_list + "]");
+        if((min_option == 1) && (max_option == 1) && (used > 1)) {
+            return {"Exactly 1 option from [" + option_list + "] is required but " + std::to_string(used) +
+                        " were given",
+                    ExitCodes::RequiredError};
+        }
+        if((min_option == 1) && (used == 0))
+            return RequiredError("At least 1 option from [" + option_list + "]");
+        if(used < min_option) {
+            return {"Requires at least " + std::to_string(min_option) + " options used but only " +
+                        std::to_string(used) + " were given from [" + option_list + "]",
+                    ExitCodes::RequiredError};
+        }
+        if(max_option == 1)
+            return {"Requires at most 1 options be given from [" + option_list + "]", ExitCodes::RequiredError};
+
+        return {"Requires at most " + std::to_string(max_option) + " options be used but " + std::to_string(used) +
+                    " were given from [" + option_list + "]",
+                ExitCodes::RequiredError};
+    }
+};
+
+/// Thrown when the wrong number of arguments has been received
+class ArgumentMismatch : public ParseError {
+    CLI11_ERROR_DEF(ParseError, ArgumentMismatch)
+    CLI11_ERROR_SIMPLE(ArgumentMismatch)
+    ArgumentMismatch(std::string name, int expected, std::size_t received)
+        : ArgumentMismatch(expected > 0 ? ("Expected exactly " + std::to_string(expected) + " arguments to " + name +
+                                           ", got " + std::to_string(received))
+                                        : ("Expected at least " + std::to_string(-expected) + " arguments to " + name +
+                                           ", got " + std::to_string(received)),
+                           ExitCodes::ArgumentMismatch) {}
+
+    static ArgumentMismatch AtLeast(std::string name, int num, std::size_t received) {
+        return ArgumentMismatch(name + ": At least " + std::to_string(num) + " required but received " +
+                                std::to_string(received));
+    }
+    static ArgumentMismatch AtMost(std::string name, int num, std::size_t received) {
+        return ArgumentMismatch(name + ": At most " + std::to_string(num) + " required but received " +
+                                std::to_string(received));
+    }
+    static ArgumentMismatch TypedAtLeast(std::string name, int num, std::string type) {
+        return ArgumentMismatch(name + ": " + std::to_string(num) + " required " + type + " missing");
+    }
+    static ArgumentMismatch FlagOverride(std::string name) {
+        return ArgumentMismatch(name + " was given a disallowed flag override");
+    }
+    static ArgumentMismatch PartialType(std::string name, int num, std::string type) {
+        return ArgumentMismatch(name + ": " + type + " only partially specified: " + std::to_string(num) +
+                                " required for each element");
+    }
+};
+
+/// Thrown when a requires option is missing
+class RequiresError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, RequiresError)
+    RequiresError(std::string curname, std::string subname)
+        : RequiresError(curname + " requires " + subname, ExitCodes::RequiresError) {}
+};
+
+/// Thrown when an excludes option is present
+class ExcludesError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, ExcludesError)
+    ExcludesError(std::string curname, std::string subname)
+        : ExcludesError(curname + " excludes " + subname, ExitCodes::ExcludesError) {}
+};
+
+/// Thrown when too many positionals or options are found
+class ExtrasError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, ExtrasError)
+    explicit ExtrasError(std::vector<std::string> args)
+        : ExtrasError((args.size() > 1 ? "The following arguments were not expected: "
+                                       : "The following argument was not expected: ") +
+                          detail::join(args, " "),
+                      ExitCodes::ExtrasError) {}
+    ExtrasError(const std::string &name, std::vector<std::string> args)
+        : ExtrasError(name,
+                      (args.size() > 1 ? "The following arguments were not expected: "
+                                       : "The following argument was not expected: ") +
+                          detail::join(args, " "),
+                      ExitCodes::ExtrasError) {}
+};
+
+/// Thrown when extra values are found in an INI file
+class ConfigError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, ConfigError)
+    CLI11_ERROR_SIMPLE(ConfigError)
+    static ConfigError Extras(std::string item) { return ConfigError("INI was not able to parse " + item); }
+    static ConfigError NotConfigurable(std::string item) {
+        return ConfigError(item + ": This option is not allowed in a configuration file");
+    }
+};
+
+/// Thrown when validation fails before parsing
+class InvalidError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, InvalidError)
+    explicit InvalidError(std::string name)
+        : InvalidError(name + ": Too many positional arguments with unlimited expected args", ExitCodes::InvalidError) {
+    }
+};
+
+/// This is just a safety check to verify selection and parsing match - you should not ever see it
+/// Strings are directly added to this error, but again, it should never be seen.
+class HorribleError : public ParseError {
+    CLI11_ERROR_DEF(ParseError, HorribleError)
+    CLI11_ERROR_SIMPLE(HorribleError)
+};
+
+// After parsing
+
+/// Thrown when counting a nonexistent option
+class OptionNotFound : public Error {
+    CLI11_ERROR_DEF(Error, OptionNotFound)
+    explicit OptionNotFound(std::string name) : OptionNotFound(name + " not found", ExitCodes::OptionNotFound) {}
+};
+
+#undef CLI11_ERROR_DEF
+#undef CLI11_ERROR_SIMPLE
+
+/// @}
+
+
+
+
+// Type tools
+
+// Utilities for type enabling
+namespace detail {
+// Based generally on https://rmf.io/cxx11/almost-static-if
+/// Simple empty scoped class
+enum class enabler : std::uint8_t {};
+
+/// An instance to use in EnableIf
+CLI11_MODULE_INLINE constexpr enabler dummy = {};
+}  // namespace detail
+
+/// A copy of enable_if_t from C++14, compatible with C++11.
+///
+/// We could check to see if C++14 is being used, but it does not hurt to redefine this
+/// (even Google does this: https://github.com/google/skia/blob/main/include/private/SkTLogic.h)
+/// It is not in the std namespace anyway, so no harm done.
+template <bool B, class T = void> using enable_if_t = typename std::enable_if<B, T>::type;
+
+/// A copy of std::void_t from C++17 (helper for C++11 and C++14)
+template <typename... Ts> struct make_void {
+    using type = void;
+};
+
+/// A copy of std::void_t from C++17 - same reasoning as enable_if_t, it does not hurt to redefine
+template <typename... Ts> using void_t = typename make_void<Ts...>::type;
+
+/// A copy of std::conditional_t from C++14 - same reasoning as enable_if_t, it does not hurt to redefine
+template <bool B, class T, class F> using conditional_t = typename std::conditional<B, T, F>::type;
+
+/// Check to see if something is bool (fail check by default)
+template <typename T> struct is_bool : std::false_type {};
+
+/// Check to see if something is bool (true if actually a bool)
+template <> struct is_bool<bool> : std::true_type {};
+
+/// Check to see if something is a shared pointer
+template <typename T> struct is_shared_ptr : std::false_type {};
+
+/// Check to see if something is a shared pointer (True if really a shared pointer)
+template <typename T> struct is_shared_ptr<std::shared_ptr<T>> : std::true_type {};
+
+/// Check to see if something is a shared pointer (True if really a shared pointer)
+template <typename T> struct is_shared_ptr<const std::shared_ptr<T>> : std::true_type {};
+
+/// Check to see if something is copyable pointer
+template <typename T> struct is_copyable_ptr {
+    static bool const value = is_shared_ptr<T>::value || std::is_pointer<T>::value;
+};
+
+/// This can be specialized to override the type deduction for IsMember.
+template <typename T> struct IsMemberType {
+    using type = T;
+};
+
+/// The main custom type needed here is const char * should be a string.
+template <> struct IsMemberType<const char *> {
+    using type = std::string;
+};
+
+namespace adl_detail {
+/// Check for existence of user-supplied lexical_cast.
+///
+/// This struct has to be in a separate namespace so that it doesn't see our lexical_cast overloads in CLI::detail.
+/// Standard says it shouldn't see them if it's defined before the corresponding lexical_cast declarations, but this
+/// requires a working implementation of two-phase lookup, and not all compilers can boast that (msvc, ahem).
+template <typename T, typename S = std::string> class is_lexical_castable {
+    template <typename TT, typename SS>
+    static auto test(int) -> decltype(lexical_cast(std::declval<const SS &>(), std::declval<TT &>()), std::true_type());
+
+    template <typename, typename> static auto test(...) -> std::false_type;
+
+  public:
+    static constexpr bool value = decltype(test<T, S>(0))::value;
+};
+}  // namespace adl_detail
+
+namespace detail {
+
+// These are utilities for IsMember and other transforming objects
+
+/// Handy helper to access the element_type generically. This is not part of is_copyable_ptr because it requires that
+/// pointer_traits<T> be valid.
+
+/// not a pointer
+template <typename T, typename Enable = void> struct element_type {
+    using type = T;
+};
+
+template <typename T> struct element_type<T, typename std::enable_if<is_copyable_ptr<T>::value>::type> {
+    using type = typename std::pointer_traits<T>::element_type;
+};
+
+/// Combination of the element type and value type - remove pointer (including smart pointers) and get the value_type of
+/// the container
+template <typename T> struct element_value_type {
+    using type = typename element_type<T>::type::value_type;
+};
+
+/// Adaptor for set-like structure: This just wraps a normal container in a few utilities that do almost nothing.
+template <typename T, typename _ = void> struct pair_adaptor : std::false_type {
+    using value_type = typename T::value_type;
+    using first_type = typename std::remove_const<value_type>::type;
+    using second_type = typename std::remove_const<value_type>::type;
+
+    /// Get the first value (really just the underlying value)
+    template <typename Q> static auto first(Q &&pair_value) -> decltype(std::forward<Q>(pair_value)) {
+        return std::forward<Q>(pair_value);
+    }
+    /// Get the second value (really just the underlying value)
+    template <typename Q> static auto second(Q &&pair_value) -> decltype(std::forward<Q>(pair_value)) {
+        return std::forward<Q>(pair_value);
+    }
+};
+
+/// Adaptor for map-like structure (true version, must have key_type and mapped_type).
+/// This wraps a mapped container in a few utilities access it in a general way.
+template <typename T>
+struct pair_adaptor<
+    T,
+    conditional_t<false, void_t<typename T::value_type::first_type, typename T::value_type::second_type>, void>>
+    : std::true_type {
+    using value_type = typename T::value_type;
+    using first_type = typename std::remove_const<typename value_type::first_type>::type;
+    using second_type = typename std::remove_const<typename value_type::second_type>::type;
+
+    /// Get the first value (really just the underlying value)
+    template <typename Q> static auto first(Q &&pair_value) -> decltype(std::get<0>(std::forward<Q>(pair_value))) {
+        return std::get<0>(std::forward<Q>(pair_value));
+    }
+    /// Get the second value (really just the underlying value)
+    template <typename Q> static auto second(Q &&pair_value) -> decltype(std::get<1>(std::forward<Q>(pair_value))) {
+        return std::get<1>(std::forward<Q>(pair_value));
+    }
+};
+
+// Warning is suppressed due to "bug" in gcc<5.0 and gcc 7.0 with c++17 enabled that generates a -Wnarrowing warning
+// in the unevaluated context even if the function that was using this wasn't used.  The standard says narrowing in
+// brace initialization shouldn't be allowed but for backwards compatibility gcc allows it in some contexts.  It is a
+// little fuzzy what happens in template constructs and I think that was something GCC took a little while to work out.
+// But regardless some versions of gcc generate a warning when they shouldn't from the following code so that should be
+// suppressed
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wnarrowing"
+#endif
+// check for constructibility from a specific type and copy assignable used in the parse detection
+template <typename T, typename C> class is_direct_constructible {
+    template <typename TT, typename CC>
+    static auto test(int, std::true_type) -> decltype(
+// NVCC warns about narrowing conversions here
+#ifdef __CUDACC__
+#ifdef __NVCC_DIAG_PRAGMA_SUPPORT__
+#pragma nv_diag_suppress 2361
+#else
+#pragma diag_suppress 2361
+#endif
+#endif
+        TT{std::declval<CC>()}
+#ifdef __CUDACC__
+#ifdef __NVCC_DIAG_PRAGMA_SUPPORT__
+#pragma nv_diag_default 2361
+#else
+#pragma diag_default 2361
+#endif
+#endif
+        ,
+        std::is_move_assignable<TT>());
+
+    template <typename TT, typename CC> static auto test(int, std::false_type) -> std::false_type;
+
+    template <typename, typename> static auto test(...) -> std::false_type;
+
+  public:
+    static constexpr bool value = decltype(test<T, C>(0, typename std::is_constructible<T, C>::type()))::value;
+};
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
+
+// Check for output streamability
+// Based on https://stackoverflow.com/questions/22758291/how-can-i-detect-if-a-type-can-be-streamed-to-an-stdostream
+
+template <typename T, typename S = std::ostringstream> class is_ostreamable {
+    template <typename TT, typename SS>
+    static auto test(int) -> decltype(std::declval<SS &>() << std::declval<TT>(), std::true_type());
+
+    template <typename, typename> static auto test(...) -> std::false_type;
+
+  public:
+    static constexpr bool value = decltype(test<T, S>(0))::value;
+};
+
+/// Check for input streamability
+template <typename T, typename S = std::istringstream> class is_istreamable {
+    template <typename TT, typename SS>
+    static auto test(int) -> decltype(std::declval<SS &>() >> std::declval<TT &>(), std::true_type());
+
+    template <typename, typename> static auto test(...) -> std::false_type;
+
+  public:
+    static constexpr bool value = decltype(test<T, S>(0))::value;
+};
+
+/// Check for complex
+template <typename T> class is_complex {
+    template <typename TT>
+    static auto test(int) -> decltype(std::declval<TT>().real(), std::declval<TT>().imag(), std::true_type());
+
+    template <typename> static auto test(...) -> std::false_type;
+
+  public:
+    static constexpr bool value = decltype(test<T>(0))::value;
+};
+
+/// Templated operation to get a value from a stream
+template <typename T, enable_if_t<is_istreamable<T>::value, detail::enabler> = detail::dummy>
+bool from_stream(const std::string &istring, T &obj) {
+    std::istringstream is;
+    is.str(istring);
+    is >> obj;
+    return !is.fail() && !is.rdbuf()->in_avail();
+}
+
+template <typename T, enable_if_t<!is_istreamable<T>::value, detail::enabler> = detail::dummy>
+bool from_stream(const std::string & /*istring*/, T & /*obj*/) {
+    return false;
+}
+
+// check to see if an object is a mutable container (fail by default)
+template <typename T, typename _ = void> struct is_mutable_container : std::false_type {};
+
+/// type trait to test if a type is a mutable container meaning it has a value_type, it has an iterator, a clear, and
+/// end methods and an insert function.  And for our purposes we exclude std::string and types that can be constructed
+/// from a std::string
+template <typename T>
+struct is_mutable_container<
+    T,
+    conditional_t<false,
+                  void_t<typename T::value_type,
+                         decltype(std::declval<T>().end()),
+                         decltype(std::declval<T>().clear()),
+                         decltype(std::declval<T>().insert(std::declval<decltype(std::declval<T>().end())>(),
+                                                           std::declval<const typename T::value_type &>()))>,
+                  void>> : public conditional_t<std::is_constructible<T, std::string>::value ||
+                                                    std::is_constructible<T, std::wstring>::value,
+                                                std::false_type,
+                                                std::true_type> {};
+
+// check to see if an object is a mutable container (fail by default)
+template <typename T, typename _ = void> struct is_readable_container : std::false_type {};
+
+/// type trait to test if a type is a container meaning it has a value_type, it has an iterator, and an end
+/// method.
+template <typename T>
+struct is_readable_container<
+    T,
+    conditional_t<false, void_t<decltype(std::declval<T>().end()), decltype(std::declval<T>().begin())>, void>>
+    : public std::true_type {};
+
+// check to see if an object is a wrapper (fail by default)
+template <typename T, typename _ = void> struct is_wrapper : std::false_type {};
+
+// check if an object is a wrapper (it has a value_type defined)
+template <typename T>
+struct is_wrapper<T, conditional_t<false, void_t<typename T::value_type>, void>> : public std::true_type {};
+
+// Check for tuple like types, as in classes with a tuple_size type trait
+// Even though in C++26 std::complex gains a std::tuple interface, for our purposes we treat is as NOT a tuple
+template <typename S> class is_tuple_like {
+    template <typename SS, enable_if_t<!is_complex<SS>::value, detail::enabler> = detail::dummy>
+    // static auto test(int)
+    //     -> decltype(std::conditional<(std::tuple_size<SS>::value > 0), std::true_type, std::false_type>::type());
+    static auto test(int) -> decltype(std::tuple_size<typename std::decay<SS>::type>::value, std::true_type{});
+    template <typename> static auto test(...) -> std::false_type;
+
+  public:
+    static constexpr bool value = decltype(test<S>(0))::value;
+};
+
+/// This will only trigger for actual void type
+template <typename T, typename Enable = void> struct type_count_base {
+    static const int value{0};
+};
+
+/// Type size for regular object types that do not look like a tuple
+template <typename T>
+struct type_count_base<T,
+                       typename std::enable_if<!is_tuple_like<T>::value && !is_mutable_container<T>::value &&
+                                               !std::is_void<T>::value>::type> {
+    static constexpr int value{1};
+};
+
+/// the base tuple size
+template <typename T>
+struct type_count_base<T, typename std::enable_if<is_tuple_like<T>::value && !is_mutable_container<T>::value>::type> {
+    static constexpr int value{// cppcheck-suppress unusedStructMember
+                               std::tuple_size<typename std::decay<T>::type>::value};
+};
+
+/// Type count base for containers is the type_count_base of the individual element
+template <typename T> struct type_count_base<T, typename std::enable_if<is_mutable_container<T>::value>::type> {
+    static constexpr int value{type_count_base<typename T::value_type>::value};
+};
+
+/// Convert an object to a string (directly forward if this can become a string)
+template <typename T, enable_if_t<std::is_convertible<T, std::string>::value, detail::enabler> = detail::dummy>
+auto to_string(T &&value) -> decltype(std::forward<T>(value)) {
+    return std::forward<T>(value);
+}
+
+/// Construct a string from the object
+template <typename T,
+          enable_if_t<std::is_constructible<std::string, T>::value && !std::is_convertible<T, std::string>::value,
+                      detail::enabler> = detail::dummy>
+std::string to_string(T &&value) {
+    return std::string(value);  // NOLINT(google-readability-casting)
+}
+
+/// Convert an object to a string (streaming must be supported for that type)
+template <typename T,
+          enable_if_t<!std::is_convertible<T, std::string>::value && !std::is_constructible<std::string, T>::value &&
+                          is_ostreamable<T>::value,
+                      detail::enabler> = detail::dummy>
+std::string to_string(T &&value) {
+    std::stringstream stream;
+    stream << value;
+    return stream.str();
+}
+
+// additional forward declarations
+
+/// Print tuple value string for tuples of size ==1
+template <typename T,
+          enable_if_t<!std::is_convertible<T, std::string>::value && !std::is_constructible<std::string, T>::value &&
+                          !is_ostreamable<T>::value && is_tuple_like<T>::value && type_count_base<T>::value == 1,
+                      detail::enabler> = detail::dummy>
+inline std::string to_string(T &&value);
+
+/// Print tuple value string for tuples of size > 1
+template <typename T,
+          enable_if_t<!std::is_convertible<T, std::string>::value && !std::is_constructible<std::string, T>::value &&
+                          !is_ostreamable<T>::value && is_tuple_like<T>::value && type_count_base<T>::value >= 2,
+                      detail::enabler> = detail::dummy>
+inline std::string to_string(T &&value);
+
+/// If conversion is not supported, return an empty string (streaming is not supported for that type)
+template <
+    typename T,
+    enable_if_t<!std::is_convertible<T, std::string>::value && !std::is_constructible<std::string, T>::value &&
+                    !is_ostreamable<T>::value && !is_readable_container<typename std::remove_const<T>::type>::value &&
+                    !is_tuple_like<T>::value,
+                detail::enabler> = detail::dummy>
+inline std::string to_string(T &&) {
+    return {};
+}
+
+/// convert a readable container to a string
+template <typename T,
+          enable_if_t<!std::is_convertible<T, std::string>::value && !std::is_constructible<std::string, T>::value &&
+                          !is_ostreamable<T>::value && is_readable_container<T>::value && !is_tuple_like<T>::value,
+                      detail::enabler> = detail::dummy>
+inline std::string to_string(T &&variable) {
+    auto cval = variable.begin();
+    auto end = variable.end();
+    if(cval == end) {
+        return {"{}"};
+    }
+    std::vector<std::string> defaults;
+    while(cval != end) {
+        defaults.emplace_back(CLI::detail::to_string(*cval));
+        ++cval;
+    }
+    return {"[" + detail::join(defaults) + "]"};
+}
+
+/// Convert a tuple like object to a string
+
+/// forward declarations for tuple_value_strings
+template <typename T, std::size_t I>
+inline typename std::enable_if<I == type_count_base<T>::value, std::string>::type tuple_value_string(T && /*value*/);
+
+/// Recursively generate the tuple value string
+template <typename T, std::size_t I>
+inline typename std::enable_if<(I < type_count_base<T>::value), std::string>::type tuple_value_string(T &&value);
+
+/// Print tuple value string for tuples of size ==1
+template <typename T,
+          enable_if_t<!std::is_convertible<T, std::string>::value && !std::is_constructible<std::string, T>::value &&
+                          !is_ostreamable<T>::value && is_tuple_like<T>::value && type_count_base<T>::value == 1,
+                      detail::enabler>>
+inline std::string to_string(T &&value) {
+    return to_string(std::get<0>(value));
+}
+
+/// Print tuple value string for tuples of size > 1
+template <typename T,
+          enable_if_t<!std::is_convertible<T, std::string>::value && !std::is_constructible<std::string, T>::value &&
+                          !is_ostreamable<T>::value && is_tuple_like<T>::value && type_count_base<T>::value >= 2,
+                      detail::enabler>>
+inline std::string to_string(T &&value) {
+    auto tname = std::string(1, '[') + tuple_value_string<T, 0>(value);
+    tname.push_back(']');
+    return tname;
+}
+
+/// Empty string if the index > tuple size
+template <typename T, std::size_t I>
+inline typename std::enable_if<I == type_count_base<T>::value, std::string>::type tuple_value_string(T && /*value*/) {
+    return std::string{};
+}
+
+/// Recursively generate the tuple value string
+template <typename T, std::size_t I>
+inline typename std::enable_if<(I < type_count_base<T>::value), std::string>::type tuple_value_string(T &&value) {
+    auto str = std::string{to_string(std::get<I>(value))} + ',' + tuple_value_string<T, I + 1>(value);
+    if(str.back() == ',')
+        str.pop_back();
+    return str;
+}
+
+/// special template overload
+template <typename T1,
+          typename T2,
+          typename T,
+          enable_if_t<std::is_same<T1, T2>::value, detail::enabler> = detail::dummy>
+auto checked_to_string(T &&value) -> decltype(to_string(std::forward<T>(value))) {
+    return to_string(std::forward<T>(value));
+}
+
+/// special template overload
+template <typename T1,
+          typename T2,
+          typename T,
+          enable_if_t<!std::is_same<T1, T2>::value, detail::enabler> = detail::dummy>
+std::string checked_to_string(T &&) {
+    return std::string{};
+}
+/// get a string as a convertible value for arithmetic types
+template <typename T, enable_if_t<std::is_arithmetic<T>::value, detail::enabler> = detail::dummy>
+std::string value_string(const T &value) {
+    return std::to_string(value);
+}
+/// get a string as a convertible value for enumerations
+template <typename T, enable_if_t<std::is_enum<T>::value, detail::enabler> = detail::dummy>
+std::string value_string(const T &value) {
+    return std::to_string(static_cast<typename std::underlying_type<T>::type>(value));
+}
+/// for other types just use the regular to_string function
+template <typename T,
+          enable_if_t<!std::is_enum<T>::value && !std::is_arithmetic<T>::value, detail::enabler> = detail::dummy>
+auto value_string(const T &value) -> decltype(to_string(value)) {
+    return to_string(value);
+}
+
+/// template to get the underlying value type if it exists or use a default
+template <typename T, typename def, typename Enable = void> struct wrapped_type {
+    using type = def;
+};
+
+/// Type size for regular object types that do not look like a tuple
+template <typename T, typename def> struct wrapped_type<T, def, typename std::enable_if<is_wrapper<T>::value>::type> {
+    using type = typename T::value_type;
+};
+
+/// Set of overloads to get the type size of an object
+
+/// forward declare the subtype_count structure
+template <typename T> struct subtype_count;
+
+/// forward declare the subtype_count_min structure
+template <typename T> struct subtype_count_min;
+
+/// This will only trigger for actual void type
+template <typename T, typename Enable = void> struct type_count {
+    static const int value{0};
+};
+
+/// Type size for regular object types that do not look like a tuple
+template <typename T>
+struct type_count<T,
+                  typename std::enable_if<!is_wrapper<T>::value && !is_tuple_like<T>::value && !is_complex<T>::value &&
+                                          !std::is_void<T>::value>::type> {
+    static constexpr int value{1};
+};
+
+/// Type size for complex since it sometimes looks like a wrapper
+template <typename T> struct type_count<T, typename std::enable_if<is_complex<T>::value>::type> {
+    static constexpr int value{2};
+};
+
+/// Type size of types that are wrappers,except complex and tuples(which can also be wrappers sometimes)
+template <typename T> struct type_count<T, typename std::enable_if<is_mutable_container<T>::value>::type> {
+    static constexpr int value{subtype_count<typename T::value_type>::value};
+};
+
+/// Type size of types that are wrappers,except containers complex and tuples(which can also be wrappers sometimes)
+template <typename T>
+struct type_count<T,
+                  typename std::enable_if<is_wrapper<T>::value && !is_complex<T>::value && !is_tuple_like<T>::value &&
+                                          !is_mutable_container<T>::value>::type> {
+    static constexpr int value{type_count<typename T::value_type>::value};
+};
+
+/// 0 if the index > tuple size
+template <typename T, std::size_t I>
+constexpr typename std::enable_if<I == type_count_base<T>::value, int>::type tuple_type_size() {
+    return 0;
+}
+
+/// Recursively generate the tuple type name
+template <typename T, std::size_t I>
+    constexpr typename std::enable_if < I<type_count_base<T>::value, int>::type tuple_type_size() {
+    return subtype_count<typename std::tuple_element<I, T>::type>::value + tuple_type_size<T, I + 1>();
+}
+
+/// Get the type size of the sum of type sizes for all the individual tuple types
+template <typename T>
+struct type_count<T, typename std::enable_if<is_tuple_like<T>::value && !is_complex<T>::value>::type> {
+    static constexpr int value{tuple_type_size<T, 0>()};
+};
+
+/// definition of subtype count
+template <typename T> struct subtype_count {
+    static constexpr int value{is_mutable_container<T>::value ? expected_max_vector_size : type_count<T>::value};
+};
+
+/// This will only trigger for actual void type
+template <typename T, typename Enable = void> struct type_count_min {
+    static const int value{0};
+};
+
+/// Type size for regular object types that do not look like a tuple
+template <typename T>
+struct type_count_min<
+    T,
+    typename std::enable_if<!is_mutable_container<T>::value && !is_tuple_like<T>::value && !is_wrapper<T>::value &&
+                            !is_complex<T>::value && !std::is_void<T>::value>::type> {
+    static constexpr int value{type_count<T>::value};
+};
+
+/// Type size for complex since it sometimes looks like a wrapper
+template <typename T> struct type_count_min<T, typename std::enable_if<is_complex<T>::value>::type> {
+    static constexpr int value{1};
+};
+
+/// Type size min of types that are wrappers,except complex and tuples(which can also be wrappers sometimes)
+template <typename T>
+struct type_count_min<
+    T,
+    typename std::enable_if<is_wrapper<T>::value && !is_complex<T>::value && !is_tuple_like<T>::value>::type> {
+    static constexpr int value{subtype_count_min<typename T::value_type>::value};
+};
+
+/// 0 if the index > tuple size
+template <typename T, std::size_t I>
+constexpr typename std::enable_if<I == type_count_base<T>::value, int>::type tuple_type_size_min() {
+    return 0;
+}
+
+/// Recursively generate the tuple type name
+template <typename T, std::size_t I>
+    constexpr typename std::enable_if < I<type_count_base<T>::value, int>::type tuple_type_size_min() {
+    return subtype_count_min<typename std::tuple_element<I, T>::type>::value + tuple_type_size_min<T, I + 1>();
+}
+
+/// Get the type size of the sum of type sizes for all the individual tuple types
+template <typename T>
+struct type_count_min<T, typename std::enable_if<is_tuple_like<T>::value && !is_complex<T>::value>::type> {
+    static constexpr int value{tuple_type_size_min<T, 0>()};
+};
+
+/// definition of subtype count
+template <typename T> struct subtype_count_min {
+    static constexpr int value{is_mutable_container<T>::value
+                                   ? ((type_count<T>::value < expected_max_vector_size) ? type_count<T>::value : 0)
+                                   : type_count_min<T>::value};
+};
+
+/// This will only trigger for actual void type
+template <typename T, typename Enable = void> struct expected_count {
+    static const int value{0};
+};
+
+/// For most types the number of expected items is 1
+template <typename T>
+struct expected_count<T,
+                      typename std::enable_if<!is_mutable_container<T>::value && !is_wrapper<T>::value &&
+                                              !std::is_void<T>::value>::type> {
+    static constexpr int value{1};
+};
+/// number of expected items in a vector
+template <typename T> struct expected_count<T, typename std::enable_if<is_mutable_container<T>::value>::type> {
+    static constexpr int value{expected_max_vector_size};
+};
+
+/// number of expected items in a vector
+template <typename T>
+struct expected_count<T, typename std::enable_if<!is_mutable_container<T>::value && is_wrapper<T>::value>::type> {
+    static constexpr int value{expected_count<typename T::value_type>::value};
+};
+
+// Enumeration of the different supported categorizations of objects
+enum class object_category : std::uint8_t {
+    char_value = 1,
+    integral_value = 2,
+    unsigned_integral = 4,
+    enumeration = 6,
+    boolean_value = 8,
+    floating_point = 10,
+    number_constructible = 12,
+    double_constructible = 14,
+    integer_constructible = 16,
+    // string like types
+    string_assignable = 23,
+    string_constructible = 24,
+    wstring_assignable = 25,
+    wstring_constructible = 26,
+    other = 45,
+    // special wrapper or container types
+    wrapper_value = 50,
+    complex_number = 60,
+    tuple_value = 70,
+    container_value = 80,
+
+};
+
+/// Set of overloads to classify an object according to type
+
+/// some type that is not otherwise recognized
+template <typename T, typename Enable = void> struct classify_object {
+    static constexpr object_category value{object_category::other};
+};
+
+/// Signed integers
+template <typename T>
+struct classify_object<
+    T,
+    typename std::enable_if<std::is_integral<T>::value && !std::is_same<T, char>::value && std::is_signed<T>::value &&
+                            !is_bool<T>::value && !std::is_enum<T>::value>::type> {
+    static constexpr object_category value{object_category::integral_value};
+};
+
+/// Unsigned integers
+template <typename T>
+struct classify_object<T,
+                       typename std::enable_if<std::is_integral<T>::value && std::is_unsigned<T>::value &&
+                                               !std::is_same<T, char>::value && !is_bool<T>::value>::type> {
+    static constexpr object_category value{object_category::unsigned_integral};
+};
+
+/// single character values
+template <typename T>
+struct classify_object<T, typename std::enable_if<std::is_same<T, char>::value && !std::is_enum<T>::value>::type> {
+    static constexpr object_category value{object_category::char_value};
+};
+
+/// Boolean values
+template <typename T> struct classify_object<T, typename std::enable_if<is_bool<T>::value>::type> {
+    static constexpr object_category value{object_category::boolean_value};
+};
+
+/// Floats
+template <typename T> struct classify_object<T, typename std::enable_if<std::is_floating_point<T>::value>::type> {
+    static constexpr object_category value{object_category::floating_point};
+};
+#if defined _MSC_VER
+// in MSVC wstring should take precedence if available this isn't as useful on other compilers due to the broader use of
+// utf-8 encoding
+#define WIDE_STRING_CHECK                                                                                              \
+    !std::is_assignable<T &, std::wstring>::value && !std::is_constructible<T, std::wstring>::value
+#define STRING_CHECK true
+#else
+#define WIDE_STRING_CHECK true
+#define STRING_CHECK !std::is_assignable<T &, std::string>::value && !std::is_constructible<T, std::string>::value
+#endif
+
+/// String and similar direct assignment
+template <typename T>
+struct classify_object<
+    T,
+    typename std::enable_if<!std::is_floating_point<T>::value && !std::is_integral<T>::value && WIDE_STRING_CHECK &&
+                            std::is_assignable<T &, std::string>::value>::type> {
+    static constexpr object_category value{object_category::string_assignable};
+};
+
+/// String and similar constructible and copy assignment
+template <typename T>
+struct classify_object<
+    T,
+    typename std::enable_if<!std::is_floating_point<T>::value && !std::is_integral<T>::value &&
+                            !std::is_assignable<T &, std::string>::value && (type_count<T>::value == 1) &&
+                            WIDE_STRING_CHECK && std::is_constructible<T, std::string>::value>::type> {
+    static constexpr object_category value{object_category::string_constructible};
+};
+
+/// Wide strings
+template <typename T>
+struct classify_object<T,
+                       typename std::enable_if<!std::is_floating_point<T>::value && !std::is_integral<T>::value &&
+                                               STRING_CHECK && std::is_assignable<T &, std::wstring>::value>::type> {
+    static constexpr object_category value{object_category::wstring_assignable};
+};
+
+template <typename T>
+struct classify_object<
+    T,
+    typename std::enable_if<!std::is_floating_point<T>::value && !std::is_integral<T>::value &&
+                            !std::is_assignable<T &, std::wstring>::value && (type_count<T>::value == 1) &&
+                            STRING_CHECK && std::is_constructible<T, std::wstring>::value>::type> {
+    static constexpr object_category value{object_category::wstring_constructible};
+};
+
+/// Enumerations
+template <typename T> struct classify_object<T, typename std::enable_if<std::is_enum<T>::value>::type> {
+    static constexpr object_category value{object_category::enumeration};
+};
+
+template <typename T> struct classify_object<T, typename std::enable_if<is_complex<T>::value>::type> {
+    static constexpr object_category value{object_category::complex_number};
+};
+
+/// Handy helper to contain a bunch of checks that rule out many common types (integers, string like, floating point,
+/// vectors, and enumerations
+template <typename T> struct uncommon_type {
+    using type = typename std::conditional<
+        !std::is_floating_point<T>::value && !std::is_integral<T>::value &&
+            !std::is_assignable<T &, std::string>::value && !std::is_constructible<T, std::string>::value &&
+            !std::is_assignable<T &, std::wstring>::value && !std::is_constructible<T, std::wstring>::value &&
+            !is_complex<T>::value && !is_mutable_container<T>::value && !std::is_enum<T>::value,
+        std::true_type,
+        std::false_type>::type;
+    static constexpr bool value = type::value;
+};
+
+/// wrapper type
+template <typename T>
+struct classify_object<T,
+                       typename std::enable_if<(!is_mutable_container<T>::value && is_wrapper<T>::value &&
+                                                !is_tuple_like<T>::value && uncommon_type<T>::value)>::type> {
+    static constexpr object_category value{object_category::wrapper_value};
+};
+
+/// Assignable from double or int
+template <typename T>
+struct classify_object<T,
+                       typename std::enable_if<uncommon_type<T>::value && type_count<T>::value == 1 &&
+                                               !is_wrapper<T>::value && is_direct_constructible<T, double>::value &&
+                                               is_direct_constructible<T, int>::value>::type> {
+    static constexpr object_category value{object_category::number_constructible};
+};
+
+/// Assignable from int
+template <typename T>
+struct classify_object<T,
+                       typename std::enable_if<uncommon_type<T>::value && type_count<T>::value == 1 &&
+                                               !is_wrapper<T>::value && !is_direct_constructible<T, double>::value &&
+                                               is_direct_constructible<T, int>::value>::type> {
+    static constexpr object_category value{object_category::integer_constructible};
+};
+
+/// Assignable from double
+template <typename T>
+struct classify_object<T,
+                       typename std::enable_if<uncommon_type<T>::value && type_count<T>::value == 1 &&
+                                               !is_wrapper<T>::value && is_direct_constructible<T, double>::value &&
+                                               !is_direct_constructible<T, int>::value>::type> {
+    static constexpr object_category value{object_category::double_constructible};
+};
+
+/// Tuple type
+template <typename T>
+struct classify_object<
+    T,
+    typename std::enable_if<is_tuple_like<T>::value &&
+                            ((type_count<T>::value >= 2 && !is_wrapper<T>::value) ||
+                             (uncommon_type<T>::value && !is_direct_constructible<T, double>::value &&
+                              !is_direct_constructible<T, int>::value) ||
+                             (uncommon_type<T>::value && type_count<T>::value >= 2))>::type> {
+    static constexpr object_category value{object_category::tuple_value};
+    // the condition on this class requires it be like a tuple, but on some compilers (like Xcode) tuples can be
+    // constructed from just the first element so tuples of <string, int,int> can be constructed from a string, which
+    // could lead to issues so there are two variants of the condition, the first isolates things with a type size >=2
+    // mainly to get tuples on Xcode with the exception of wrappers, the second is the main one and just separating out
+    // those cases that are caught by other object classifications
+};
+
+/// container type
+template <typename T> struct classify_object<T, typename std::enable_if<is_mutable_container<T>::value>::type> {
+    static constexpr object_category value{object_category::container_value};
+};
+
+// Type name print
+
+/// Was going to be based on
+///  http://stackoverflow.com/questions/1055452/c-get-name-of-type-in-template
+/// But this is cleaner and works better in this case
+
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::char_value, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "CHAR";
+}
+
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::integral_value ||
+                          classify_object<T>::value == object_category::integer_constructible,
+                      detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "INT";
+}
+
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::unsigned_integral, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "UINT";
+}
+
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::floating_point ||
+                          classify_object<T>::value == object_category::number_constructible ||
+                          classify_object<T>::value == object_category::double_constructible,
+                      detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "FLOAT";
+}
+
+/// Print name for enumeration types
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::enumeration, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "ENUM";
+}
+
+/// Print name for enumeration types
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::boolean_value, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "BOOLEAN";
+}
+
+/// Print name for enumeration types
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::complex_number, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "COMPLEX";
+}
+
+/// Print for all other types
+template <typename T,
+          enable_if_t<classify_object<T>::value >= object_category::string_assignable &&
+                          classify_object<T>::value <= object_category::other,
+                      detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "TEXT";
+}
+/// typename for tuple value
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::tuple_value && type_count_base<T>::value >= 2,
+                      detail::enabler> = detail::dummy>
+std::string type_name();  // forward declaration
+
+/// Generate type name for a wrapper or container value
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::container_value ||
+                          classify_object<T>::value == object_category::wrapper_value,
+                      detail::enabler> = detail::dummy>
+std::string type_name();  // forward declaration
+
+/// Print name for single element tuple types
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::tuple_value && type_count_base<T>::value == 1,
+                      detail::enabler> = detail::dummy>
+inline std::string type_name() {
+    return type_name<typename std::decay<typename std::tuple_element<0, T>::type>::type>();
+}
+
+/// Empty string if the index > tuple size
+template <typename T, std::size_t I>
+inline typename std::enable_if<I == type_count_base<T>::value, std::string>::type tuple_name() {
+    return std::string{};
+}
+
+/// Recursively generate the tuple type name
+template <typename T, std::size_t I>
+inline typename std::enable_if<(I < type_count_base<T>::value), std::string>::type tuple_name() {
+    auto str = std::string{type_name<typename std::decay<typename std::tuple_element<I, T>::type>::type>()} + ',' +
+               tuple_name<T, I + 1>();
+    if(str.back() == ',')
+        str.pop_back();
+    return str;
+}
+
+/// Print type name for tuples with 2 or more elements
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::tuple_value && type_count_base<T>::value >= 2,
+                      detail::enabler>>
+inline std::string type_name() {
+    auto tname = std::string(1, '[') + tuple_name<T, 0>();
+    tname.push_back(']');
+    return tname;
+}
+
+/// get the type name for a type that has a value_type member
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::container_value ||
+                          classify_object<T>::value == object_category::wrapper_value,
+                      detail::enabler>>
+inline std::string type_name() {
+    return type_name<typename T::value_type>();
+}
+
+// Lexical cast
+
+/// Convert to an unsigned integral
+template <typename T, enable_if_t<std::is_unsigned<T>::value, detail::enabler> = detail::dummy>
+bool integral_conversion(const std::string &input, T &output) noexcept {
+    if(input.empty() || input.front() == '-') {
+        return false;
+    }
+    char *val{nullptr};
+    errno = 0;
+    std::uint64_t output_ll = std::strtoull(input.c_str(), &val, 0);
+    if(errno == ERANGE) {
+        return false;
+    }
+    output = static_cast<T>(output_ll);
+    if(val == (input.c_str() + input.size()) && static_cast<std::uint64_t>(output) == output_ll) {
+        return true;
+    }
+    val = nullptr;
+    std::int64_t output_sll = std::strtoll(input.c_str(), &val, 0);
+    if(val == (input.c_str() + input.size())) {
+        output = (output_sll < 0) ? static_cast<T>(0) : static_cast<T>(output_sll);
+        return (static_cast<std::int64_t>(output) == output_sll);
+    }
+    // remove separators if present
+    auto group_separators = get_group_separators();
+    if(input.find_first_of(group_separators) != std::string::npos) {
+        std::string nstring = input;
+        for(auto &separator : group_separators) {
+            if(input.find_first_of(separator) != std::string::npos) {
+                nstring.erase(std::remove(nstring.begin(), nstring.end(), separator), nstring.end());
+            }
+        }
+        return integral_conversion(nstring, output);
+    }
+
+    if(std::isspace(static_cast<unsigned char>(input.back()))) {
+        return integral_conversion(trim_copy(input), output);
+    }
+    if(input.compare(0, 2, "0o") == 0 || input.compare(0, 2, "0O") == 0) {
+        val = nullptr;
+        errno = 0;
+        output_ll = std::strtoull(input.c_str() + 2, &val, 8);
+        if(errno == ERANGE) {
+            return false;
+        }
+        output = static_cast<T>(output_ll);
+        return (val == (input.c_str() + input.size()) && static_cast<std::uint64_t>(output) == output_ll);
+    }
+    if(input.compare(0, 2, "0b") == 0 || input.compare(0, 2, "0B") == 0) {
+        // LCOV_EXCL_START
+        // In some new compilers including the coverage testing one binary strings are handled properly in strtoull
+        // automatically so this coverage is missing but is well tested in other compilers
+        val = nullptr;
+        errno = 0;
+        output_ll = std::strtoull(input.c_str() + 2, &val, 2);
+        if(errno == ERANGE) {
+            return false;
+        }
+        output = static_cast<T>(output_ll);
+        return (val == (input.c_str() + input.size()) && static_cast<std::uint64_t>(output) == output_ll);
+        // LCOV_EXCL_STOP
+    }
+    return false;
+}
+
+/// Convert to a signed integral
+template <typename T, enable_if_t<std::is_signed<T>::value, detail::enabler> = detail::dummy>
+bool integral_conversion(const std::string &input, T &output) noexcept {
+    if(input.empty()) {
+        return false;
+    }
+    char *val = nullptr;
+    errno = 0;
+    std::int64_t output_ll = std::strtoll(input.c_str(), &val, 0);
+    if(errno == ERANGE) {
+        return false;
+    }
+    output = static_cast<T>(output_ll);
+    if(val == (input.c_str() + input.size()) && static_cast<std::int64_t>(output) == output_ll) {
+        return true;
+    }
+    if(input == "true") {
+        // this is to deal with a few oddities with flags and wrapper int types
+        output = static_cast<T>(1);
+        return true;
+    }
+    // remove separators if present
+    auto group_separators = get_group_separators();
+    if(input.find_first_of(group_separators) != std::string::npos) {
+        for(auto &separator : group_separators) {
+            if(input.find_first_of(separator) != std::string::npos) {
+                std::string nstring = input;
+                nstring.erase(std::remove(nstring.begin(), nstring.end(), separator), nstring.end());
+                return integral_conversion(nstring, output);
+            }
+        }
+    }
+    if(std::isspace(static_cast<unsigned char>(input.back()))) {
+        return integral_conversion(trim_copy(input), output);
+    }
+    if(input.compare(0, 2, "0o") == 0 || input.compare(0, 2, "0O") == 0) {
+        val = nullptr;
+        errno = 0;
+        output_ll = std::strtoll(input.c_str() + 2, &val, 8);
+        if(errno == ERANGE) {
+            return false;
+        }
+        output = static_cast<T>(output_ll);
+        return (val == (input.c_str() + input.size()) && static_cast<std::int64_t>(output) == output_ll);
+    }
+    if(input.compare(0, 2, "0b") == 0 || input.compare(0, 2, "0B") == 0) {
+        // LCOV_EXCL_START
+        // In some new compilers including the coverage testing one binary strings are handled properly in strtoll
+        // automatically so this coverage is missing but is well tested in other compilers
+        val = nullptr;
+        errno = 0;
+        output_ll = std::strtoll(input.c_str() + 2, &val, 2);
+        if(errno == ERANGE) {
+            return false;
+        }
+        output = static_cast<T>(output_ll);
+        return (val == (input.c_str() + input.size()) && static_cast<std::int64_t>(output) == output_ll);
+        // LCOV_EXCL_STOP
+    }
+    return false;
+}
+
+/// Convert a flag into an integer value  typically binary flags sets errno to nonzero if conversion failed
+inline std::int64_t to_flag_value(std::string val) noexcept {
+    static const std::string trueString("true");
+    static const std::string falseString("false");
+    if(val == trueString) {
+        return 1;
+    }
+    if(val == falseString) {
+        return -1;
+    }
+    val = detail::to_lower(val);
+    std::int64_t ret = 0;
+    if(val.size() == 1) {
+        if(val[0] >= '1' && val[0] <= '9') {
+            return (static_cast<std::int64_t>(val[0]) - '0');
+        }
+        switch(val[0]) {
+        case '0':
+        case 'f':
+        case 'n':
+        case '-':
+            ret = -1;
+            break;
+        case 't':
+        case 'y':
+        case '+':
+            ret = 1;
+            break;
+        default:
+            errno = EINVAL;
+            return -1;
+        }
+        return ret;
+    }
+    if(val == trueString || val == "on" || val == "yes" || val == "enable") {
+        ret = 1;
+    } else if(val == falseString || val == "off" || val == "no" || val == "disable") {
+        ret = -1;
+    } else {
+        char *loc_ptr{nullptr};
+        ret = std::strtoll(val.c_str(), &loc_ptr, 0);
+        if(loc_ptr != (val.c_str() + val.size()) && errno == 0) {
+            errno = EINVAL;
+        }
+    }
+    return ret;
+}
+
+/// Integer conversion
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::integral_value ||
+                          classify_object<T>::value == object_category::unsigned_integral,
+                      detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    return integral_conversion(input, output);
+}
+
+/// char values
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::char_value, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    if(input.size() == 1) {
+        output = static_cast<T>(input[0]);
+        return true;
+    }
+    std::int8_t res{0};
+    // we do it this way as some systems have char as signed and not,  this ensures consistency in the way things are
+    // handled
+    bool result = integral_conversion(input, res);
+    if(result) {
+        output = static_cast<T>(res);
+    }
+    return result;
+}
+
+/// Boolean values
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::boolean_value, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    errno = 0;
+    auto out = to_flag_value(input);
+    if(errno == 0) {
+        output = (out > 0);
+    } else if(errno == ERANGE) {
+        output = (input[0] != '-');
+    } else {
+        return false;
+    }
+    return true;
+}
+
+/// Floats
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::floating_point, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    if(input.empty()) {
+        return false;
+    }
+    char *val = nullptr;
+    auto output_ld = std::strtold(input.c_str(), &val);
+    output = static_cast<T>(output_ld);
+    if(val == (input.c_str() + input.size())) {
+        return true;
+    }
+    while(std::isspace(static_cast<unsigned char>(*val))) {
+        ++val;
+        if(val == (input.c_str() + input.size())) {
+            return true;
+        }
+    }
+
+    // remove separators if present
+    auto group_separators = get_group_separators();
+    if(input.find_first_of(group_separators) != std::string::npos) {
+        for(auto &separator : group_separators) {
+            if(input.find_first_of(separator) != std::string::npos) {
+                std::string nstring = input;
+                nstring.erase(std::remove(nstring.begin(), nstring.end(), separator), nstring.end());
+                return lexical_cast(nstring, output);
+            }
+        }
+    }
+    return false;
+}
+
+/// complex
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::complex_number, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    using XC = typename wrapped_type<T, double>::type;
+    XC x{0.0}, y{0.0};
+    auto str1 = input;
+    bool worked = false;
+    auto nloc = str1.find_last_of("+-");
+    if(nloc != std::string::npos && nloc > 0) {
+        worked = lexical_cast(str1.substr(0, nloc), x);
+        str1 = str1.substr(nloc);
+        if(str1.back() == 'i' || str1.back() == 'j')
+            str1.pop_back();
+        worked = worked && lexical_cast(str1, y);
+    } else {
+        if(str1.back() == 'i' || str1.back() == 'j') {
+            str1.pop_back();
+            worked = lexical_cast(str1, y);
+            x = XC{0};
+        } else {
+            worked = lexical_cast(str1, x);
+            y = XC{0};
+        }
+    }
+    if(worked) {
+        output = T{x, y};
+        return worked;
+    }
+    return from_stream(input, output);
+}
+
+/// String and similar direct assignment
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::string_assignable, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    output = input;
+    return true;
+}
+
+/// String and similar constructible and copy assignment
+template <
+    typename T,
+    enable_if_t<classify_object<T>::value == object_category::string_constructible, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    output = T(input);
+    return true;
+}
+
+/// Wide strings
+template <
+    typename T,
+    enable_if_t<classify_object<T>::value == object_category::wstring_assignable, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    output = widen(input);
+    return true;
+}
+
+template <
+    typename T,
+    enable_if_t<classify_object<T>::value == object_category::wstring_constructible, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    output = T{widen(input)};
+    return true;
+}
+
+/// Enumerations
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::enumeration, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    typename std::underlying_type<T>::type val;
+    if(!integral_conversion(input, val)) {
+        return false;
+    }
+    output = static_cast<T>(val);
+    return true;
+}
+
+/// wrapper types
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::wrapper_value &&
+                          std::is_assignable<T &, typename T::value_type>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    typename T::value_type val;
+    if(lexical_cast(input, val)) {
+        output = val;
+        return true;
+    }
+    return from_stream(input, output);
+}
+
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::wrapper_value &&
+                          !std::is_assignable<T &, typename T::value_type>::value && std::is_assignable<T &, T>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    typename T::value_type val;
+    if(lexical_cast(input, val)) {
+        output = T{val};
+        return true;
+    }
+    return from_stream(input, output);
+}
+
+/// Assignable from double or int
+template <
+    typename T,
+    enable_if_t<classify_object<T>::value == object_category::number_constructible, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    int val = 0;
+    if(integral_conversion(input, val)) {
+        output = T(val);
+        return true;
+    }
+
+    double dval = 0.0;
+    if(lexical_cast(input, dval)) {
+        output = T{dval};
+        return true;
+    }
+
+    return from_stream(input, output);
+}
+
+/// Assignable from int
+template <
+    typename T,
+    enable_if_t<classify_object<T>::value == object_category::integer_constructible, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    int val = 0;
+    if(integral_conversion(input, val)) {
+        output = T(val);
+        return true;
+    }
+    return from_stream(input, output);
+}
+
+/// Assignable from double
+template <
+    typename T,
+    enable_if_t<classify_object<T>::value == object_category::double_constructible, detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    double val = 0.0;
+    if(lexical_cast(input, val)) {
+        output = T{val};
+        return true;
+    }
+    return from_stream(input, output);
+}
+
+/// Non-string convertible from an int
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::other && std::is_assignable<T &, int>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    int val = 0;
+    if(integral_conversion(input, val)) {
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable : 4800)
+#endif
+        // with Atomic<XX> this could produce a warning due to the conversion but if atomic gets here it is an old style
+        // so will most likely still work
+        output = val;
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+        return true;
+    }
+    // LCOV_EXCL_START
+    // This version of cast is only used for odd cases in an older compilers the fail over
+    // from_stream is tested elsewhere an not relevant for coverage here
+    return from_stream(input, output);
+    // LCOV_EXCL_STOP
+}
+
+/// Non-string parsable by a stream
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::other && !std::is_assignable<T &, int>::value &&
+                          is_istreamable<T>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string &input, T &output) {
+    return from_stream(input, output);
+}
+
+/// Fallback overload that prints a human-readable error for types that we don't recognize and that don't have a
+/// user-supplied lexical_cast overload.
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::other && !std::is_assignable<T &, int>::value &&
+                          !is_istreamable<T>::value && !adl_detail::is_lexical_castable<T>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_cast(const std::string & /*input*/, T & /*output*/) {
+    static_assert(!std::is_same<T, T>::value,  // Can't just write false here.
+                  "option object type must have a lexical cast overload or streaming input operator(>>) defined, if it "
+                  "is convertible from another type use the add_option<T, XC>(...) with XC being the known type");
+    return false;
+}
+
+/// Assign a value through lexical cast operations
+/// Strings can be empty so we need to do a little different
+template <typename AssignTo,
+          typename ConvertTo,
+          enable_if_t<std::is_same<AssignTo, ConvertTo>::value &&
+                          (classify_object<AssignTo>::value == object_category::string_assignable ||
+                           classify_object<AssignTo>::value == object_category::string_constructible ||
+                           classify_object<AssignTo>::value == object_category::wstring_assignable ||
+                           classify_object<AssignTo>::value == object_category::wstring_constructible),
+                      detail::enabler> = detail::dummy>
+bool lexical_assign(const std::string &input, AssignTo &output) {
+    return lexical_cast(input, output);
+}
+
+/// Assign a value through lexical cast operations
+template <typename AssignTo,
+          typename ConvertTo,
+          enable_if_t<std::is_same<AssignTo, ConvertTo>::value && std::is_assignable<AssignTo &, AssignTo>::value &&
+                          classify_object<AssignTo>::value != object_category::string_assignable &&
+                          classify_object<AssignTo>::value != object_category::string_constructible &&
+                          classify_object<AssignTo>::value != object_category::wstring_assignable &&
+                          classify_object<AssignTo>::value != object_category::wstring_constructible,
+                      detail::enabler> = detail::dummy>
+bool lexical_assign(const std::string &input, AssignTo &output) {
+    if(input.empty()) {
+        output = AssignTo{};
+        return true;
+    }
+
+    return lexical_cast(input, output);
+}  // LCOV_EXCL_LINE
+
+/// Assign a value through lexical cast operations
+template <typename AssignTo,
+          typename ConvertTo,
+          enable_if_t<std::is_same<AssignTo, ConvertTo>::value && !std::is_assignable<AssignTo &, AssignTo>::value &&
+                          classify_object<AssignTo>::value == object_category::wrapper_value,
+                      detail::enabler> = detail::dummy>
+bool lexical_assign(const std::string &input, AssignTo &output) {
+    if(input.empty()) {
+        typename AssignTo::value_type emptyVal{};
+        output = emptyVal;
+        return true;
+    }
+    return lexical_cast(input, output);
+}
+
+/// Assign a value through lexical cast operations for int compatible values
+/// mainly for atomic operations on some compilers
+template <typename AssignTo,
+          typename ConvertTo,
+          enable_if_t<std::is_same<AssignTo, ConvertTo>::value && !std::is_assignable<AssignTo &, AssignTo>::value &&
+                          classify_object<AssignTo>::value != object_category::wrapper_value &&
+                          std::is_assignable<AssignTo &, int>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_assign(const std::string &input, AssignTo &output) {
+    if(input.empty()) {
+        output = 0;
+        return true;
+    }
+    int val{0};
+    if(lexical_cast(input, val)) {
+#if defined(__clang__)
+/* on some older clang compilers */
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wsign-conversion"
+#endif
+        output = val;
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#endif
+        return true;
+    }
+    return false;
+}
+
+/// Assign a value converted from a string in lexical cast to the output value directly
+template <typename AssignTo,
+          typename ConvertTo,
+          enable_if_t<!std::is_same<AssignTo, ConvertTo>::value && std::is_assignable<AssignTo &, ConvertTo &>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_assign(const std::string &input, AssignTo &output) {
+    ConvertTo val{};
+    bool parse_result = (!input.empty()) ? lexical_cast(input, val) : true;
+    if(parse_result) {
+        output = val;
+    }
+    return parse_result;
+}
+
+/// Assign a value from a lexical cast through constructing a value and move assigning it
+template <
+    typename AssignTo,
+    typename ConvertTo,
+    enable_if_t<!std::is_same<AssignTo, ConvertTo>::value && !std::is_assignable<AssignTo &, ConvertTo &>::value &&
+                    std::is_move_assignable<AssignTo>::value,
+                detail::enabler> = detail::dummy>
+bool lexical_assign(const std::string &input, AssignTo &output) {
+    ConvertTo val{};
+    bool parse_result = input.empty() ? true : lexical_cast(input, val);
+    if(parse_result) {
+        output = AssignTo(val);  // use () form of constructor to allow some implicit conversions
+    }
+    return parse_result;
+}
+
+/// primary lexical conversion operation, 1 string to 1 type of some kind
+template <typename AssignTo,
+          typename ConvertTo,
+          enable_if_t<classify_object<ConvertTo>::value <= object_category::other &&
+                          classify_object<AssignTo>::value <= object_category::wrapper_value,
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std ::string> &strings, AssignTo &output) {
+    return lexical_assign<AssignTo, ConvertTo>(strings[0], output);
+}
+
+/// Lexical conversion if there is only one element but the conversion type is for two, then call a two element
+/// constructor
+template <typename AssignTo,
+          typename ConvertTo,
+          enable_if_t<(type_count<AssignTo>::value <= 2) && expected_count<AssignTo>::value == 1 &&
+                          is_tuple_like<ConvertTo>::value && type_count_base<ConvertTo>::value == 2,
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std ::string> &strings, AssignTo &output) {
+    // the remove const is to handle pair types coming from a container
+    using FirstType = typename std::remove_const<typename std::tuple_element<0, ConvertTo>::type>::type;
+    using SecondType = typename std::tuple_element<1, ConvertTo>::type;
+    FirstType v1;
+    SecondType v2{};
+    bool retval = lexical_assign<FirstType, FirstType>(strings[0], v1);
+    retval = retval && lexical_assign<SecondType, SecondType>((strings.size() > 1) ? strings[1] : std::string{}, v2);
+    if(retval) {
+        output = AssignTo{v1, v2};
+    }
+    return retval;
+}
+
+/// Lexical conversion of a container types of single elements
+template <class AssignTo,
+          class ConvertTo,
+          enable_if_t<is_mutable_container<AssignTo>::value && is_mutable_container<ConvertTo>::value &&
+                          type_count<ConvertTo>::value == 1,
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std ::string> &strings, AssignTo &output) {
+    output.erase(output.begin(), output.end());
+    if(strings.empty()) {
+        return true;
+    }
+    if(strings.size() == 1 && strings[0] == "{}") {
+        return true;
+    }
+    bool skip_remaining = false;
+    if(strings.size() == 2 && strings[0] == "{}" && is_separator(strings[1])) {
+        skip_remaining = true;
+    }
+    for(const auto &elem : strings) {
+        typename AssignTo::value_type out;
+        bool retval = lexical_assign<typename AssignTo::value_type, typename ConvertTo::value_type>(elem, out);
+        if(!retval) {
+            return false;
+        }
+        output.insert(output.end(), std::move(out));
+        if(skip_remaining) {
+            break;
+        }
+    }
+    return (!output.empty());
+}
+
+/// Lexical conversion for complex types
+template <class AssignTo, class ConvertTo, enable_if_t<is_complex<ConvertTo>::value, detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std::string> &strings, AssignTo &output) {
+
+    if(strings.size() >= 2 && !strings[1].empty()) {
+        using XC2 = typename wrapped_type<ConvertTo, double>::type;
+        XC2 x{0.0}, y{0.0};
+        auto str1 = strings[1];
+        if(str1.back() == 'i' || str1.back() == 'j') {
+            str1.pop_back();
+        }
+        auto worked = lexical_cast(strings[0], x) && lexical_cast(str1, y);
+        if(worked) {
+            output = ConvertTo{x, y};
+        }
+        return worked;
+    }
+    return lexical_assign<AssignTo, ConvertTo>(strings[0], output);
+}
+
+/// Conversion to a vector type using a particular single type as the conversion type
+template <class AssignTo,
+          class ConvertTo,
+          enable_if_t<is_mutable_container<AssignTo>::value && (expected_count<ConvertTo>::value == 1) &&
+                          (type_count<ConvertTo>::value == 1),
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std ::string> &strings, AssignTo &output) {
+    bool retval = true;
+    output.clear();
+    output.reserve(strings.size());
+    for(const auto &elem : strings) {
+
+        output.emplace_back();
+        retval = retval && lexical_assign<typename AssignTo::value_type, ConvertTo>(elem, output.back());
+    }
+    return (!output.empty()) && retval;
+}
+
+// forward declaration
+
+/// Lexical conversion of a container types with conversion type of two elements
+template <class AssignTo,
+          class ConvertTo,
+          enable_if_t<is_mutable_container<AssignTo>::value && is_mutable_container<ConvertTo>::value &&
+                          type_count_base<ConvertTo>::value == 2,
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(std::vector<std::string> strings, AssignTo &output);
+
+/// Lexical conversion of a vector types with type_size >2 forward declaration
+template <class AssignTo,
+          class ConvertTo,
+          enable_if_t<is_mutable_container<AssignTo>::value && is_mutable_container<ConvertTo>::value &&
+                          type_count_base<ConvertTo>::value != 2 &&
+                          ((type_count<ConvertTo>::value > 2) ||
+                           (type_count<ConvertTo>::value > type_count_base<ConvertTo>::value)),
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std::string> &strings, AssignTo &output);
+
+/// Conversion for tuples
+template <class AssignTo,
+          class ConvertTo,
+          enable_if_t<is_tuple_like<AssignTo>::value && is_tuple_like<ConvertTo>::value &&
+                          (type_count_base<ConvertTo>::value != type_count<ConvertTo>::value ||
+                           type_count<ConvertTo>::value > 2),
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std::string> &strings, AssignTo &output);  // forward declaration
+
+/// Conversion for operations where the assigned type is some class but the conversion is a mutable container or large
+/// tuple
+template <typename AssignTo,
+          typename ConvertTo,
+          enable_if_t<!is_tuple_like<AssignTo>::value && !is_mutable_container<AssignTo>::value &&
+                          classify_object<ConvertTo>::value != object_category::wrapper_value &&
+                          (is_mutable_container<ConvertTo>::value || type_count<ConvertTo>::value > 2),
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std ::string> &strings, AssignTo &output) {
+
+    if(strings.size() > 1 || (!strings.empty() && !(strings.front().empty()))) {
+        ConvertTo val;
+        auto retval = lexical_conversion<ConvertTo, ConvertTo>(strings, val);
+        output = AssignTo{val};
+        return retval;
+    }
+    output = AssignTo{};
+    return true;
+}
+
+/// function template for converting tuples if the static Index is greater than the tuple size
+template <class AssignTo, class ConvertTo, std::size_t I>
+inline typename std::enable_if<(I >= type_count_base<AssignTo>::value), bool>::type
+tuple_conversion(const std::vector<std::string> &, AssignTo &) {
+    return true;
+}
+
+/// Conversion of a tuple element where the type size ==1 and not a mutable container
+template <class AssignTo, class ConvertTo>
+inline typename std::enable_if<!is_mutable_container<ConvertTo>::value && type_count<ConvertTo>::value == 1, bool>::type
+tuple_type_conversion(std::vector<std::string> &strings, AssignTo &output) {
+    auto retval = lexical_assign<AssignTo, ConvertTo>(strings[0], output);
+    strings.erase(strings.begin());
+    return retval;
+}
+
+/// Conversion of a tuple element where the type size !=1 but the size is fixed and not a mutable container
+template <class AssignTo, class ConvertTo>
+inline typename std::enable_if<!is_mutable_container<ConvertTo>::value && (type_count<ConvertTo>::value > 1) &&
+                                   type_count<ConvertTo>::value == type_count_min<ConvertTo>::value,
+                               bool>::type
+tuple_type_conversion(std::vector<std::string> &strings, AssignTo &output) {
+    auto retval = lexical_conversion<AssignTo, ConvertTo>(strings, output);
+    strings.erase(strings.begin(), strings.begin() + type_count<ConvertTo>::value);
+    return retval;
+}
+
+/// Conversion of a tuple element where the type is a mutable container or a type with different min and max type sizes
+template <class AssignTo, class ConvertTo>
+inline typename std::enable_if<is_mutable_container<ConvertTo>::value ||
+                                   type_count<ConvertTo>::value != type_count_min<ConvertTo>::value,
+                               bool>::type
+tuple_type_conversion(std::vector<std::string> &strings, AssignTo &output) {
+
+    std::size_t index{subtype_count_min<ConvertTo>::value};
+    const std::size_t mx_count{subtype_count<ConvertTo>::value};
+    const std::size_t mx{(std::min)(mx_count, strings.size() - 1)};
+
+    while(index < mx) {
+        if(is_separator(strings[index])) {
+            break;
+        }
+        ++index;
+    }
+    bool retval = lexical_conversion<AssignTo, ConvertTo>(
+        std::vector<std::string>(strings.begin(), strings.begin() + static_cast<std::ptrdiff_t>(index)), output);
+    if(strings.size() > index) {
+        strings.erase(strings.begin(), strings.begin() + static_cast<std::ptrdiff_t>(index) + 1);
+    } else {
+        strings.clear();
+    }
+    return retval;
+}
+
+/// Tuple conversion operation
+template <class AssignTo, class ConvertTo, std::size_t I>
+inline typename std::enable_if<(I < type_count_base<AssignTo>::value), bool>::type
+tuple_conversion(std::vector<std::string> strings, AssignTo &output) {
+    bool retval = true;
+    using ConvertToElement = typename std::
+        conditional<is_tuple_like<ConvertTo>::value, typename std::tuple_element<I, ConvertTo>::type, ConvertTo>::type;
+    if(!strings.empty()) {
+        retval = retval && tuple_type_conversion<typename std::tuple_element<I, AssignTo>::type, ConvertToElement>(
+                               strings, std::get<I>(output));
+    }
+    retval = retval && tuple_conversion<AssignTo, ConvertTo, I + 1>(std::move(strings), output);
+    return retval;
+}
+
+/// Lexical conversion of a container types with tuple elements of size 2
+template <class AssignTo,
+          class ConvertTo,
+          enable_if_t<is_mutable_container<AssignTo>::value && is_mutable_container<ConvertTo>::value &&
+                          type_count_base<ConvertTo>::value == 2,
+                      detail::enabler>>
+bool lexical_conversion(std::vector<std::string> strings, AssignTo &output) {
+    output.clear();
+    while(!strings.empty()) {
+
+        typename std::remove_const<typename std::tuple_element<0, typename ConvertTo::value_type>::type>::type v1;
+        typename std::tuple_element<1, typename ConvertTo::value_type>::type v2;
+        bool retval = tuple_type_conversion<decltype(v1), decltype(v1)>(strings, v1);
+        if(!strings.empty()) {
+            retval = retval && tuple_type_conversion<decltype(v2), decltype(v2)>(strings, v2);
+        }
+        if(retval) {
+            output.insert(output.end(), typename AssignTo::value_type{v1, v2});
+        } else {
+            return false;
+        }
+    }
+    return (!output.empty());
+}
+
+/// lexical conversion of tuples with type count>2 or tuples of types of some element with a type size>=2
+template <class AssignTo,
+          class ConvertTo,
+          enable_if_t<is_tuple_like<AssignTo>::value && is_tuple_like<ConvertTo>::value &&
+                          (type_count_base<ConvertTo>::value != type_count<ConvertTo>::value ||
+                           type_count<ConvertTo>::value > 2),
+                      detail::enabler>>
+bool lexical_conversion(const std::vector<std ::string> &strings, AssignTo &output) {
+    static_assert(
+        !is_tuple_like<ConvertTo>::value || type_count_base<AssignTo>::value == type_count_base<ConvertTo>::value,
+        "if the conversion type is defined as a tuple it must be the same size as the type you are converting to");
+    return tuple_conversion<AssignTo, ConvertTo, 0>(strings, output);
+}
+
+/// Lexical conversion of a vector types for everything but tuples of two elements and types of size 1
+template <class AssignTo,
+          class ConvertTo,
+          enable_if_t<is_mutable_container<AssignTo>::value && is_mutable_container<ConvertTo>::value &&
+                          type_count_base<ConvertTo>::value != 2 &&
+                          ((type_count<ConvertTo>::value > 2) ||
+                           (type_count<ConvertTo>::value > type_count_base<ConvertTo>::value)),
+                      detail::enabler>>
+bool lexical_conversion(const std::vector<std ::string> &strings, AssignTo &output) {
+    bool retval = true;
+    output.clear();
+    std::vector<std::string> temp;
+    std::size_t ii{0};
+    std::size_t icount{0};
+    std::size_t xcm{type_count<ConvertTo>::value};
+    auto ii_max = strings.size();
+    while(ii < ii_max) {
+        temp.push_back(strings[ii]);
+        ++ii;
+        ++icount;
+        if(icount == xcm || is_separator(temp.back()) || ii == ii_max) {
+            if(static_cast<int>(xcm) > type_count_min<ConvertTo>::value && is_separator(temp.back())) {
+                temp.pop_back();
+            }
+            typename AssignTo::value_type temp_out;
+            retval = retval &&
+                     lexical_conversion<typename AssignTo::value_type, typename ConvertTo::value_type>(temp, temp_out);
+            temp.clear();
+            if(!retval) {
+                return false;
+            }
+            output.insert(output.end(), std::move(temp_out));
+            icount = 0;
+        }
+    }
+    return retval;
+}
+
+/// conversion for wrapper types
+template <typename AssignTo,
+          class ConvertTo,
+          enable_if_t<classify_object<ConvertTo>::value == object_category::wrapper_value &&
+                          std::is_assignable<ConvertTo &, ConvertTo>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std::string> &strings, AssignTo &output) {
+    if(strings.empty() || strings.front().empty()) {
+        output = ConvertTo{};
+        return true;
+    }
+    typename ConvertTo::value_type val;
+    if(lexical_conversion<typename ConvertTo::value_type, typename ConvertTo::value_type>(strings, val)) {
+        output = ConvertTo{val};
+        return true;
+    }
+    return false;
+}
+
+/// conversion for wrapper types
+template <typename AssignTo,
+          class ConvertTo,
+          enable_if_t<classify_object<ConvertTo>::value == object_category::wrapper_value &&
+                          !std::is_assignable<AssignTo &, ConvertTo>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_conversion(const std::vector<std::string> &strings, AssignTo &output) {
+    using ConvertType = typename ConvertTo::value_type;
+    if(strings.empty() || strings.front().empty()) {
+        output = ConvertType{};
+        return true;
+    }
+    ConvertType val;
+    if(lexical_conversion<typename ConvertTo::value_type, typename ConvertTo::value_type>(strings, val)) {
+        output = val;
+        return true;
+    }
+    return false;
+}
+
+/// Sum a vector of strings
+inline std::string sum_string_vector(const std::vector<std::string> &values) {
+    double val{0.0};
+    bool fail{false};
+    std::string output;
+    for(const auto &arg : values) {
+        double tv{0.0};
+        auto comp = lexical_cast(arg, tv);
+        if(!comp) {
+            errno = 0;
+            auto fv = detail::to_flag_value(arg);
+            fail = (errno != 0);
+            if(fail) {
+                break;
+            }
+            tv = static_cast<double>(fv);
+        }
+        val += tv;
+    }
+    if(fail) {
+        for(const auto &arg : values) {
+            output.append(arg);
+        }
+    } else {
+        std::ostringstream out;
+        out.precision(16);
+        out << val;
+        output = out.str();
+    }
+    return output;
+}
+
+}  // namespace detail
+
+
+
+namespace detail {
+
+// Returns false if not a short option. Otherwise, sets opt name and rest and returns true
+CLI11_INLINE bool split_short(const std::string &current, std::string &name, std::string &rest);
+
+// Returns false if not a long option. Otherwise, sets opt name and other side of = and returns true
+CLI11_INLINE bool split_long(const std::string &current, std::string &name, std::string &value);
+
+// Returns false if not a windows style option. Otherwise, sets opt name and value and returns true
+CLI11_INLINE bool split_windows_style(const std::string &current, std::string &name, std::string &value);
+
+// Splits a string into multiple long and short names
+CLI11_INLINE std::vector<std::string> split_names(std::string current);
+
+/// extract default flag values either {def} or starting with a !
+CLI11_INLINE std::vector<std::pair<std::string, std::string>> get_default_flag_values(const std::string &str);
+
+/// Get a vector of short names, one of long names, and a single name
+CLI11_INLINE std::tuple<std::vector<std::string>, std::vector<std::string>, std::string>
+get_names(const std::vector<std::string> &input, bool allow_non_standard = false);
+
+}  // namespace detail
+
+
+
+namespace detail {
+
+CLI11_INLINE bool split_short(const std::string &current, std::string &name, std::string &rest) {
+    if(current.size() > 1 && current[0] == '-' && valid_first_char(current[1])) {
+        name = current.substr(1, 1);
+        rest = current.substr(2);
+        return true;
+    }
+    return false;
+}
+
+CLI11_INLINE bool split_long(const std::string &current, std::string &name, std::string &value) {
+    if(current.size() > 2 && current.compare(0, 2, "--") == 0 && valid_first_char(current[2])) {
+        auto loc = current.find_first_of('=');
+        if(loc != std::string::npos) {
+            name = current.substr(2, loc - 2);
+            value = current.substr(loc + 1);
+        } else {
+            name = current.substr(2);
+            value = "";
+        }
+        return true;
+    }
+    return false;
+}
+
+CLI11_INLINE bool split_windows_style(const std::string &current, std::string &name, std::string &value) {
+    if(current.size() > 1 && current[0] == '/' && valid_first_char(current[1])) {
+        auto loc = current.find_first_of(':');
+        if(loc != std::string::npos) {
+            name = current.substr(1, loc - 1);
+            value = current.substr(loc + 1);
+        } else {
+            name = current.substr(1);
+            value = "";
+        }
+        return true;
+    }
+    return false;
+}
+
+CLI11_INLINE std::vector<std::string> split_names(std::string current) {
+    std::vector<std::string> output;
+    std::size_t val = 0;
+    while((val = current.find(',')) != std::string::npos) {
+        output.push_back(trim_copy(current.substr(0, val)));
+        current = current.substr(val + 1);
+    }
+    output.push_back(trim_copy(current));
+    return output;
+}
+
+CLI11_INLINE std::vector<std::pair<std::string, std::string>> get_default_flag_values(const std::string &str) {
+    std::vector<std::string> flags = split_names(str);
+    flags.erase(std::remove_if(flags.begin(),
+                               flags.end(),
+                               [](const std::string &name) {
+                                   return ((name.empty()) || (!(((name.find_first_of('{') != std::string::npos) &&
+                                                                 (name.back() == '}')) ||
+                                                                (name[0] == '!'))));
+                               }),
+                flags.end());
+    std::vector<std::pair<std::string, std::string>> output;
+    output.reserve(flags.size());
+    for(auto &flag : flags) {
+        auto def_start = flag.find_first_of('{');
+        std::string defval = "false";
+        if((def_start != std::string::npos) && (flag.back() == '}')) {
+            defval = flag.substr(def_start + 1);
+            defval.pop_back();
+            flag.erase(def_start, std::string::npos);  // NOLINT(readability-suspicious-call-argument)
+        }
+        flag.erase(0, flag.find_first_not_of("-!"));
+        output.emplace_back(flag, defval);
+    }
+    return output;
+}
+
+CLI11_INLINE std::tuple<std::vector<std::string>, std::vector<std::string>, std::string>
+get_names(const std::vector<std::string> &input, bool allow_non_standard) {
+
+    std::vector<std::string> short_names;
+    std::vector<std::string> long_names;
+    std::string pos_name;
+    for(std::string name : input) {
+        if(name.empty()) {
+            continue;
+        }
+        if(name.length() > 1 && name[0] == '-' && name[1] != '-') {
+            if(name.length() == 2 && valid_first_char(name[1])) {
+                short_names.emplace_back(1, name[1]);
+            } else if(name.length() > 2) {
+                if(allow_non_standard) {
+                    name = name.substr(1);
+                    if(valid_name_string(name)) {
+                        short_names.push_back(name);
+                    } else {
+                        throw BadNameString::BadLongName(name);
+                    }
+                } else {
+                    throw BadNameString::MissingDash(name);
+                }
+            } else {
+                throw BadNameString::OneCharName(name);
+            }
+        } else if(name.length() > 2 && name.substr(0, 2) == "--") {
+            name = name.substr(2);
+            if(valid_name_string(name)) {
+                long_names.push_back(name);
+            } else {
+                throw BadNameString::BadLongName(name);
+            }
+        } else if(name == "-" || name == "--" || name == "++") {
+            throw BadNameString::ReservedName(name);
+        } else {
+            if(!pos_name.empty()) {
+                throw BadNameString::MultiPositionalNames(name);
+            }
+            if(valid_name_string(name)) {
+                pos_name = name;
+            } else {
+                throw BadNameString::BadPositionalName(name);
+            }
+        }
+    }
+    return std::make_tuple(short_names, long_names, pos_name);
+}
+
+}  // namespace detail
+
+
+
+class App;
+
+/// Holds values to load into Options
+struct ConfigItem {
+    /// This is the list of parents
+    std::vector<std::string> parents{};
+
+    /// This is the name
+    std::string name{};
+    /// Listing of inputs
+    std::vector<std::string> inputs{};
+    /// @brief indicator if a multiline vector separator was inserted
+    bool multiline{false};
+    /// The list of parents and name joined by "."
+    CLI11_NODISCARD std::string fullname() const {
+        std::vector<std::string> tmp = parents;
+        tmp.emplace_back(name);
+        return detail::join(tmp, ".");
+        (void)multiline;  // suppression for cppcheck false positive
+    }
+};
+
+/// This class provides a converter for configuration files.
+class Config {
+  protected:
+    std::vector<ConfigItem> items{};
+
+  public:
+    /// Convert an app into a configuration
+    virtual std::string to_config(const App *, bool, bool, std::string) const = 0;
+
+    /// Convert a configuration into an app
+    virtual std::vector<ConfigItem> from_config(std::istream &) const = 0;
+
+    /// Get a flag value
+    CLI11_NODISCARD virtual std::string to_flag(const ConfigItem &item) const {
+        if(item.inputs.size() == 1) {
+            return item.inputs.at(0);
+        }
+        if(item.inputs.empty()) {
+            return "{}";
+        }
+        throw ConversionError::TooManyInputsFlag(item.fullname());  // LCOV_EXCL_LINE
+    }
+
+    /// Parse a config file, throw an error (ParseError:ConfigParseError or FileError) on failure
+    CLI11_NODISCARD std::vector<ConfigItem> from_file(const std::string &name) const {
+#if defined CLI11_HAS_FILESYSTEM && CLI11_HAS_FILESYSTEM > 0
+        std::ifstream input{to_path(name)};
+#else
+        std::ifstream input{name};
+#endif
+
+        if(!input.good())
+            throw FileError::Missing(name);
+
+        return from_config(input);
+    }
+
+    /// Virtual destructor
+    virtual ~Config() = default;
+};
+
+/// This converter works with INI/TOML files; to write INI files use ConfigINI
+class ConfigBase : public Config {
+  protected:
+    /// the character used for comments
+    char commentChar = '#';
+    /// the character used to start an array '\0' is a default to not use
+    char arrayStart = '[';
+    /// the character used to end an array '\0' is a default to not use
+    char arrayEnd = ']';
+    /// the character used to separate elements in an array
+    char arraySeparator = ',';
+    /// the character used separate the name from the value
+    char valueDelimiter = '=';
+    /// the character to use around strings
+    char stringQuote = '"';
+    /// the character to use around single characters and literal strings
+    char literalQuote = '\'';
+    /// the maximum number of layers to allow
+    uint8_t maximumLayers{255};
+    /// the separator used to separator parent layers
+    char parentSeparatorChar{'.'};
+    /// comment default values
+    bool commentDefaultsBool = false;
+    /// specify the config reader should collapse repeated field names to a single vector
+    bool allowMultipleDuplicateFields{false};
+    /// Specify the configuration index to use for arrayed sections
+    int16_t configIndex{-1};
+    /// Specify the configuration section that should be used
+    std::string configSection{};
+
+  public:
+    std::string
+    to_config(const App * /*app*/, bool default_also, bool write_description, std::string prefix) const override;
+
+    std::vector<ConfigItem> from_config(std::istream &input) const override;
+    /// Specify the configuration for comment characters
+    ConfigBase *comment(char cchar) {
+        commentChar = cchar;
+        return this;
+    }
+    /// Specify the start and end characters for an array
+    ConfigBase *arrayBounds(char aStart, char aEnd) {
+        arrayStart = aStart;
+        arrayEnd = aEnd;
+        return this;
+    }
+    /// Specify the delimiter character for an array
+    ConfigBase *arrayDelimiter(char aSep) {
+        arraySeparator = aSep;
+        return this;
+    }
+    /// Specify the delimiter between a name and value
+    ConfigBase *valueSeparator(char vSep) {
+        valueDelimiter = vSep;
+        return this;
+    }
+    /// Specify the quote characters used around strings and literal strings
+    ConfigBase *quoteCharacter(char qString, char literalChar) {
+        stringQuote = qString;
+        literalQuote = literalChar;
+        return this;
+    }
+    /// Specify the maximum number of parents
+    ConfigBase *maxLayers(uint8_t layers) {
+        maximumLayers = layers;
+        return this;
+    }
+    /// Specify the separator to use for parent layers
+    ConfigBase *parentSeparator(char sep) {
+        parentSeparatorChar = sep;
+        return this;
+    }
+    /// comment default value options
+    ConfigBase *commentDefaults(bool comDef = true) {
+        commentDefaultsBool = comDef;
+        return this;
+    }
+    /// get a reference to the configuration section
+    std::string &sectionRef() { return configSection; }
+    /// get the section
+    CLI11_NODISCARD const std::string &section() const { return configSection; }
+    /// specify a particular section of the configuration file to use
+    ConfigBase *section(const std::string &sectionName) {
+        configSection = sectionName;
+        return this;
+    }
+
+    /// get a reference to the configuration index
+    int16_t &indexRef() { return configIndex; }
+    /// get the section index
+    CLI11_NODISCARD int16_t index() const { return configIndex; }
+    /// specify a particular index in the section to use (-1) for all sections to use
+    ConfigBase *index(int16_t sectionIndex) {
+        configIndex = sectionIndex;
+        return this;
+    }
+    /// specify that multiple duplicate arguments should be merged even if not sequential
+    ConfigBase *allowDuplicateFields(bool value = true) {
+        allowMultipleDuplicateFields = value;
+        return this;
+    }
+};
+
+/// the default Config is the TOML file format
+using ConfigTOML = ConfigBase;
+
+/// ConfigINI generates a "standard" INI compliant output
+class ConfigINI : public ConfigTOML {
+
+  public:
+    ConfigINI() {
+        commentChar = ';';
+        arrayStart = '\0';
+        arrayEnd = '\0';
+        arraySeparator = ' ';
+        valueDelimiter = '=';
+    }
+};
+
+
+
+class Option;
+
+/// @defgroup validator_group Validators
+
+/// @brief Some validators that are provided
+///
+/// These are simple `std::string(const std::string&)` validators that are useful. They return
+/// a string if the validation fails. A custom struct is provided, as well, with the same user
+/// semantics, but with the ability to provide a new type name.
+/// @{
+
+///
+class Validator {
+  protected:
+    /// This is the description function, if empty the description_ will be used
+    std::function<std::string()> desc_function_{[]() { return std::string{}; }};
+
+    /// This is the base function that is to be called.
+    /// Returns a string error message if validation fails.
+    std::function<std::string(std::string &)> func_{[](std::string &) { return std::string{}; }};
+    /// The name for search purposes of the Validator
+    std::string name_{};
+    /// A Validator will only apply to an indexed value (-1 is all elements)
+    int application_index_ = -1;
+    /// Enable for Validator to allow it to be disabled if need be
+    bool active_{true};
+    /// specify that a validator should not modify the input
+    bool non_modifying_{false};
+
+    Validator(std::string validator_desc, std::function<std::string(std::string &)> func)
+        : desc_function_([validator_desc]() { return validator_desc; }), func_(std::move(func)) {}
+
+  public:
+    Validator() = default;
+    /// Construct a Validator with just the description string
+    explicit Validator(std::string validator_desc) : desc_function_([validator_desc]() { return validator_desc; }) {}
+    /// Construct Validator from basic information
+    Validator(std::function<std::string(std::string &)> op, std::string validator_desc, std::string validator_name = "")
+        : desc_function_([validator_desc]() { return validator_desc; }), func_(std::move(op)),
+          name_(std::move(validator_name)) {}
+    /// Set the Validator operation function
+    Validator &operation(std::function<std::string(std::string &)> op) {
+        func_ = std::move(op);
+        return *this;
+    }
+    /// This is the required operator for a Validator - provided to help
+    /// users (CLI11 uses the member `func` directly)
+    std::string operator()(std::string &str) const;
+
+    /// This is the required operator for a Validator - provided to help
+    /// users (CLI11 uses the member `func` directly)
+    std::string operator()(const std::string &str) const {
+        std::string value = str;
+        return (active_) ? func_(value) : std::string{};
+    }
+
+    /// Specify the type string
+    Validator &description(std::string validator_desc) {
+        desc_function_ = [validator_desc]() { return validator_desc; };
+        return *this;
+    }
+    /// Specify the type string
+    CLI11_NODISCARD Validator description(std::string validator_desc) const;
+
+    /// Generate type description information for the Validator
+    CLI11_NODISCARD std::string get_description() const {
+        if(active_) {
+            return desc_function_();
+        }
+        return std::string{};
+    }
+    /// Specify the type string
+    Validator &name(std::string validator_name) {
+        name_ = std::move(validator_name);
+        return *this;
+    }
+    /// Specify the type string
+    CLI11_NODISCARD Validator name(std::string validator_name) const {
+        Validator newval(*this);
+        newval.name_ = std::move(validator_name);
+        return newval;
+    }
+    /// Get the name of the Validator
+    CLI11_NODISCARD const std::string &get_name() const { return name_; }
+    /// Specify whether the Validator is active or not
+    Validator &active(bool active_val = true) {
+        active_ = active_val;
+        return *this;
+    }
+    /// Specify whether the Validator is active or not
+    CLI11_NODISCARD Validator active(bool active_val = true) const {
+        Validator newval(*this);
+        newval.active_ = active_val;
+        return newval;
+    }
+
+    /// Specify whether the Validator can be modifying or not
+    Validator &non_modifying(bool no_modify = true) {
+        non_modifying_ = no_modify;
+        return *this;
+    }
+    /// Specify the application index of a validator
+    Validator &application_index(int app_index) {
+        application_index_ = app_index;
+        return *this;
+    }
+    /// Specify the application index of a validator
+    CLI11_NODISCARD Validator application_index(int app_index) const {
+        Validator newval(*this);
+        newval.application_index_ = app_index;
+        return newval;
+    }
+    /// Get the current value of the application index
+    CLI11_NODISCARD int get_application_index() const { return application_index_; }
+    /// Get a boolean if the validator is active
+    CLI11_NODISCARD bool get_active() const { return active_; }
+
+    /// Get a boolean if the validator is allowed to modify the input returns true if it can modify the input
+    CLI11_NODISCARD bool get_modifying() const { return !non_modifying_; }
+
+    /// Combining validators is a new validator. Type comes from left validator if function, otherwise only set if the
+    /// same.
+    Validator operator&(const Validator &other) const;
+
+    /// Combining validators is a new validator. Type comes from left validator if function, otherwise only set if the
+    /// same.
+    Validator operator|(const Validator &other) const;
+
+    /// Create a validator that fails when a given validator succeeds
+    Validator operator!() const;
+
+  private:
+    void _merge_description(const Validator &val1, const Validator &val2, const std::string &merger);
+};
+
+/// Alias for Validator for custom Validator for clarity
+using CustomValidator = Validator;
+
+// The implementation of the built in validators is using the Validator class;
+// the user is only expected to use the const (static) versions (since there's no setup).
+// Therefore, this is in detail.
+namespace detail {
+
+/// CLI enumeration of different file types
+enum class path_type : std::uint8_t { nonexistent, file, directory };
+
+/// get the type of the path from a file name
+CLI11_INLINE path_type check_path(const char *file) noexcept;
+
+// Static is not needed here, because global const implies static.
+
+/// Check for an existing file (returns error message if check fails)
+class ExistingFileValidator : public Validator {
+  public:
+    ExistingFileValidator();
+};
+
+/// Check for an existing directory (returns error message if check fails)
+class ExistingDirectoryValidator : public Validator {
+  public:
+    ExistingDirectoryValidator();
+};
+
+/// Check for an existing path
+class ExistingPathValidator : public Validator {
+  public:
+    ExistingPathValidator();
+};
+
+/// Check for an non-existing path
+class NonexistentPathValidator : public Validator {
+  public:
+    NonexistentPathValidator();
+};
+
+class EscapedStringTransformer : public Validator {
+  public:
+    EscapedStringTransformer();
+};
+
+}  // namespace detail
+
+/// Check for existing file (returns error message if check fails)
+CLI11_MODULE_INLINE const detail::ExistingFileValidator ExistingFile;
+
+/// Check for an existing directory (returns error message if check fails)
+CLI11_MODULE_INLINE const detail::ExistingDirectoryValidator ExistingDirectory;
+
+/// Check for an existing path
+CLI11_MODULE_INLINE const detail::ExistingPathValidator ExistingPath;
+
+/// Check for an non-existing path
+CLI11_MODULE_INLINE const detail::NonexistentPathValidator NonexistentPath;
+
+/// convert escaped characters into their associated values
+CLI11_MODULE_INLINE const detail::EscapedStringTransformer EscapedString;
+
+/// Modify a path if the file is a particular default location, can be used as Check or transform
+/// with the error return optionally disabled
+class FileOnDefaultPath : public Validator {
+  public:
+    explicit FileOnDefaultPath(std::string default_path, bool enableErrorReturn = true);
+};
+
+/// Produce a range (factory). Min and max are inclusive.
+class Range : public Validator {
+  public:
+    /// This produces a range with min and max inclusive.
+    ///
+    /// Note that the constructor is templated, but the struct is not, so C++17 is not
+    /// needed to provide nice syntax for Range(a,b).
+    template <typename T>
+    Range(T min_val, T max_val, const std::string &validator_name = std::string{}) : Validator(validator_name) {
+        if(validator_name.empty()) {
+            std::stringstream out;
+            out << detail::type_name<T>() << " in [" << min_val << " - " << max_val << "]";
+            description(out.str());
+        }
+
+        func_ = [min_val, max_val](std::string &input) {
+            using CLI::detail::lexical_cast;
+            T val;
+            bool converted = lexical_cast(input, val);
+            if((!converted) || (val < min_val || val > max_val)) {
+                std::stringstream out;
+                out << "Value " << input << " not in range [";
+                out << min_val << " - " << max_val << "]";
+                return out.str();
+            }
+            return std::string{};
+        };
+    }
+
+    /// Range of one value is 0 to value
+    template <typename T>
+    explicit Range(T max_val, const std::string &validator_name = std::string{})
+        : Range(static_cast<T>(0), max_val, validator_name) {}
+};
+
+/// Check for a non negative number
+CLI11_MODULE_INLINE const Range NonNegativeNumber((std::numeric_limits<double>::max)(), "NONNEGATIVE");
+
+/// Check for a positive valued number (val>0.0), <double>::min  here is the smallest positive number
+CLI11_MODULE_INLINE const
+    Range PositiveNumber((std::numeric_limits<double>::min)(), (std::numeric_limits<double>::max)(), "POSITIVE");
+
+namespace detail {
+// the following suggestion was made by Nikita Ofitserov(@himikof)
+// done in templates to prevent compiler warnings on negation of unsigned numbers
+
+/// Do a check for overflow on signed numbers
+template <typename T>
+inline typename std::enable_if<std::is_signed<T>::value, T>::type overflowCheck(const T &a, const T &b) {
+    if((a > 0) == (b > 0)) {
+        return ((std::numeric_limits<T>::max)() / (std::abs)(a) < (std::abs)(b));
+    }
+    return ((std::numeric_limits<T>::min)() / (std::abs)(a) > -(std::abs)(b));
+}
+/// Do a check for overflow on unsigned numbers
+template <typename T>
+inline typename std::enable_if<!std::is_signed<T>::value, T>::type overflowCheck(const T &a, const T &b) {
+    return ((std::numeric_limits<T>::max)() / a < b);
+}
+
+/// Performs a *= b; if it doesn't cause integer overflow. Returns false otherwise.
+template <typename T> typename std::enable_if<std::is_integral<T>::value, bool>::type checked_multiply(T &a, T b) {
+    if(a == 0 || b == 0 || a == 1 || b == 1) {
+        a *= b;
+        return true;
+    }
+    if(a == (std::numeric_limits<T>::min)() || b == (std::numeric_limits<T>::min)()) {
+        return false;
+    }
+    if(overflowCheck(a, b)) {
+        return false;
+    }
+    a *= b;
+    return true;
+}
+
+/// Performs a *= b; if it doesn't equal infinity. Returns false otherwise.
+template <typename T>
+typename std::enable_if<std::is_floating_point<T>::value, bool>::type checked_multiply(T &a, T b) {
+    T c = a * b;
+    if(std::isinf(c) && !std::isinf(a) && !std::isinf(b)) {
+        return false;
+    }
+    a = c;
+    return true;
+}
+/// Split a string into a program name and command line arguments
+/// the string is assumed to contain a file name followed by other arguments
+/// the return value contains is a pair with the first argument containing the program name and the second
+/// everything else.
+CLI11_INLINE std::pair<std::string, std::string> split_program_name(std::string commandline);
+
+}  // namespace detail
+/// @}
+
+
+
+
+CLI11_INLINE std::string Validator::operator()(std::string &str) const {
+    std::string retstring;
+    if(active_) {
+        if(non_modifying_) {
+            std::string value = str;
+            retstring = func_(value);
+        } else {
+            retstring = func_(str);
+        }
+    }
+    return retstring;
+}
+
+CLI11_NODISCARD CLI11_INLINE Validator Validator::description(std::string validator_desc) const {
+    Validator newval(*this);
+    newval.desc_function_ = [validator_desc]() { return validator_desc; };
+    return newval;
+}
+
+CLI11_INLINE Validator Validator::operator&(const Validator &other) const {
+    Validator newval;
+
+    newval._merge_description(*this, other, " AND ");
+
+    // Give references (will make a copy in lambda function)
+    const std::function<std::string(std::string & filename)> &f1 = func_;
+    const std::function<std::string(std::string & filename)> &f2 = other.func_;
+
+    newval.func_ = [f1, f2](std::string &input) {
+        std::string s1 = f1(input);
+        std::string s2 = f2(input);
+        if(!s1.empty() && !s2.empty())
+            return std::string("(") + s1 + ") AND (" + s2 + ")";
+        return s1 + s2;
+    };
+
+    newval.active_ = active_ && other.active_;
+    newval.application_index_ = application_index_;
+    return newval;
+}
+
+CLI11_INLINE Validator Validator::operator|(const Validator &other) const {
+    Validator newval;
+
+    newval._merge_description(*this, other, " OR ");
+
+    // Give references (will make a copy in lambda function)
+    const std::function<std::string(std::string &)> &f1 = func_;
+    const std::function<std::string(std::string &)> &f2 = other.func_;
+
+    newval.func_ = [f1, f2](std::string &input) {
+        std::string s1 = f1(input);
+        std::string s2 = f2(input);
+        if(s1.empty() || s2.empty())
+            return std::string();
+
+        return std::string("(") + s1 + ") OR (" + s2 + ")";
+    };
+    newval.active_ = active_ && other.active_;
+    newval.application_index_ = application_index_;
+    return newval;
+}
+
+CLI11_INLINE Validator Validator::operator!() const {
+    Validator newval;
+    const std::function<std::string()> &dfunc1 = desc_function_;
+    newval.desc_function_ = [dfunc1]() {
+        auto str = dfunc1();
+        return (!str.empty()) ? std::string("NOT ") + str : std::string{};
+    };
+    // Give references (will make a copy in lambda function)
+    const std::function<std::string(std::string & res)> &f1 = func_;
+
+    newval.func_ = [f1, dfunc1](std::string &test) -> std::string {
+        std::string s1 = f1(test);
+        if(s1.empty()) {
+            return std::string("check ") + dfunc1() + " succeeded improperly";
+        }
+        return std::string{};
+    };
+    newval.active_ = active_;
+    newval.application_index_ = application_index_;
+    return newval;
+}
+
+CLI11_INLINE void
+Validator::_merge_description(const Validator &val1, const Validator &val2, const std::string &merger) {
+
+    const std::function<std::string()> &dfunc1 = val1.desc_function_;
+    const std::function<std::string()> &dfunc2 = val2.desc_function_;
+
+    desc_function_ = [=]() {
+        std::string f1 = dfunc1();
+        std::string f2 = dfunc2();
+        if((f1.empty()) || (f2.empty())) {
+            return f1 + f2;
+        }
+        return std::string(1, '(') + f1 + ')' + merger + '(' + f2 + ')';
+    };
+}
+
+namespace detail {
+
+#if defined CLI11_HAS_FILESYSTEM && CLI11_HAS_FILESYSTEM > 0
+CLI11_INLINE path_type check_path(const char *file) noexcept {
+    std::error_code ec;
+    auto stat = std::filesystem::status(to_path(file), ec);
+    if(ec) {
+        return path_type::nonexistent;
+    }
+    switch(stat.type()) {
+    case std::filesystem::file_type::none:  // LCOV_EXCL_LINE
+    case std::filesystem::file_type::not_found:
+        return path_type::nonexistent;  // LCOV_EXCL_LINE
+    case std::filesystem::file_type::directory:
+        return path_type::directory;
+    case std::filesystem::file_type::symlink:
+    case std::filesystem::file_type::block:
+    case std::filesystem::file_type::character:
+    case std::filesystem::file_type::fifo:
+    case std::filesystem::file_type::socket:
+    case std::filesystem::file_type::regular:
+    case std::filesystem::file_type::unknown:
+    default:
+        return path_type::file;
+    }
+}
+#else
+CLI11_INLINE path_type check_path(const char *file) noexcept {
+#if defined(_MSC_VER)
+    struct __stat64 buffer;
+    if(_stat64(file, &buffer) == 0) {
+        return ((buffer.st_mode & S_IFDIR) != 0) ? path_type::directory : path_type::file;
+    }
+#else
+    struct stat buffer;
+    if(stat(file, &buffer) == 0) {
+        return ((buffer.st_mode & S_IFDIR) != 0) ? path_type::directory : path_type::file;
+    }
+#endif
+    return path_type::nonexistent;
+}
+#endif
+
+CLI11_INLINE ExistingFileValidator::ExistingFileValidator() : Validator("FILE") {
+    func_ = [](std::string &filename) {
+        auto path_result = check_path(filename.c_str());
+        if(path_result == path_type::nonexistent) {
+            return "File does not exist: " + filename;
+        }
+        if(path_result == path_type::directory) {
+            return "File is actually a directory: " + filename;
+        }
+        return std::string();
+    };
+}
+
+CLI11_INLINE ExistingDirectoryValidator::ExistingDirectoryValidator() : Validator("DIR") {
+    func_ = [](std::string &filename) {
+        auto path_result = check_path(filename.c_str());
+        if(path_result == path_type::nonexistent) {
+            return "Directory does not exist: " + filename;
+        }
+        if(path_result == path_type::file) {
+            return "Directory is actually a file: " + filename;
+        }
+        return std::string();
+    };
+}
+
+CLI11_INLINE ExistingPathValidator::ExistingPathValidator() : Validator("PATH(existing)") {
+    func_ = [](std::string &filename) {
+        auto path_result = check_path(filename.c_str());
+        if(path_result == path_type::nonexistent) {
+            return "Path does not exist: " + filename;
+        }
+        return std::string();
+    };
+}
+
+CLI11_INLINE NonexistentPathValidator::NonexistentPathValidator() : Validator("PATH(non-existing)") {
+    func_ = [](std::string &filename) {
+        auto path_result = check_path(filename.c_str());
+        if(path_result != path_type::nonexistent) {
+            return "Path already exists: " + filename;
+        }
+        return std::string();
+    };
+}
+
+CLI11_INLINE EscapedStringTransformer::EscapedStringTransformer() {
+    func_ = [](std::string &str) {
+        try {
+            if(str.size() > 1 && (str.front() == '\"' || str.front() == '\'' || str.front() == '`') &&
+               str.front() == str.back()) {
+                process_quoted_string(str);
+            } else if(str.find_first_of('\\') != std::string::npos) {
+                if(detail::is_binary_escaped_string(str)) {
+                    str = detail::extract_binary_string(str);
+                } else {
+                    str = remove_escaped_characters(str);
+                }
+            }
+            return std::string{};
+        } catch(const std::invalid_argument &ia) {
+            return std::string(ia.what());
+        }
+    };
+}
+}  // namespace detail
+
+CLI11_INLINE FileOnDefaultPath::FileOnDefaultPath(std::string default_path, bool enableErrorReturn)
+    : Validator("FILE") {
+    func_ = [default_path, enableErrorReturn](std::string &filename) {
+        auto path_result = detail::check_path(filename.c_str());
+        if(path_result == detail::path_type::nonexistent) {
+            std::string test_file_path = default_path;
+            if(default_path.back() != '/' && default_path.back() != '\\') {
+                // Add folder separator
+                test_file_path += '/';
+            }
+            test_file_path.append(filename);
+            path_result = detail::check_path(test_file_path.c_str());
+            if(path_result == detail::path_type::file) {
+                filename = test_file_path;
+            } else {
+                if(enableErrorReturn) {
+                    return "File does not exist: " + filename;
+                }
+            }
+        }
+        return std::string{};
+    };
+}
+
+namespace detail {
+
+CLI11_INLINE std::pair<std::string, std::string> split_program_name(std::string commandline) {
+    // try to determine the programName
+    std::pair<std::string, std::string> vals;
+    trim(commandline);
+    auto esp = commandline.find_first_of(' ', 1);
+    while(detail::check_path(commandline.substr(0, esp).c_str()) != path_type::file) {
+        esp = commandline.find_first_of(' ', esp + 1);
+        if(esp == std::string::npos) {
+            // if we have reached the end and haven't found a valid file just assume the first argument is the
+            // program name
+            if(commandline[0] == '"' || commandline[0] == '\'' || commandline[0] == '`') {
+                bool embeddedQuote = false;
+                auto keyChar = commandline[0];
+                auto end = commandline.find_first_of(keyChar, 1);
+                while((end != std::string::npos) && (commandline[end - 1] == '\\')) {  // deal with escaped quotes
+                    end = commandline.find_first_of(keyChar, end + 1);
+                    embeddedQuote = true;
+                }
+                if(end != std::string::npos) {
+                    vals.first = commandline.substr(1, end - 1);
+                    esp = end + 1;
+                    if(embeddedQuote) {
+                        vals.first = find_and_replace(vals.first, std::string("\\") + keyChar, std::string(1, keyChar));
+                    }
+                } else {
+                    esp = commandline.find_first_of(' ', 1);
+                }
+            } else {
+                esp = commandline.find_first_of(' ', 1);
+            }
+
+            break;
+        }
+    }
+    if(vals.first.empty()) {
+        vals.first = commandline.substr(0, esp);
+        rtrim(vals.first);
+    }
+
+    // strip the program name
+    vals.second = (esp < commandline.length() - 1) ? commandline.substr(esp + 1) : std::string{};
+    ltrim(vals.second);
+    return vals;
+}
+
+}  // namespace detail
+/// @}
+
+
+
+
+// The implementation of the extra validators is using the Validator class;
+// the user is only expected to use the const (static) versions (since there's no setup).
+// Therefore, this is in detail.
+namespace detail {
+
+/// Validate the given string is a legal ipv4 address
+class IPV4Validator : public Validator {
+  public:
+    IPV4Validator();
+};
+
+}  // namespace detail
+
+/// Validate the input as a particular type
+template <typename DesiredType> class TypeValidator : public Validator {
+  public:
+    explicit TypeValidator(const std::string &validator_name)
+        : Validator(validator_name, [](std::string &input_string) {
+              using CLI::detail::lexical_cast;
+              auto val = DesiredType();
+              if(!lexical_cast(input_string, val)) {
+                  return std::string("Failed parsing ") + input_string + " as a " + detail::type_name<DesiredType>();
+              }
+              return std::string{};
+          }) {}
+    TypeValidator() : TypeValidator(detail::type_name<DesiredType>()) {}
+};
+
+/// Check for a number
+const TypeValidator<double> Number("NUMBER");
+
+/// Produce a bounded range (factory). Min and max are inclusive.
+class Bound : public Validator {
+  public:
+    /// This bounds a value with min and max inclusive.
+    ///
+    /// Note that the constructor is templated, but the struct is not, so C++17 is not
+    /// needed to provide nice syntax for Range(a,b).
+    template <typename T> Bound(T min_val, T max_val) {
+        std::stringstream out;
+        out << detail::type_name<T>() << " bounded to [" << min_val << " - " << max_val << "]";
+        description(out.str());
+
+        func_ = [min_val, max_val](std::string &input) {
+            using CLI::detail::lexical_cast;
+            T val;
+            bool converted = lexical_cast(input, val);
+            if(!converted) {
+                return std::string("Value ") + input + " could not be converted";
+            }
+            if(val < min_val)
+                input = detail::to_string(min_val);
+            else if(val > max_val)
+                input = detail::to_string(max_val);
+
+            return std::string{};
+        };
+    }
+
+    /// Range of one value is 0 to value
+    template <typename T> explicit Bound(T max_val) : Bound(static_cast<T>(0), max_val) {}
+};
+
+// Static is not needed here, because global const implies static.
+
+/// Check for an IP4 address
+CLI11_MODULE_INLINE const detail::IPV4Validator ValidIPV4;
+
+namespace detail {
+template <typename T,
+          enable_if_t<is_copyable_ptr<typename std::remove_reference<T>::type>::value, detail::enabler> = detail::dummy>
+auto smart_deref(T value) -> decltype(*value) {
+    return *value;
+}
+
+template <
+    typename T,
+    enable_if_t<!is_copyable_ptr<typename std::remove_reference<T>::type>::value, detail::enabler> = detail::dummy>
+typename std::remove_reference<T>::type &smart_deref(T &value) {
+    // NOLINTNEXTLINE
+    return value;
+}
+/// Generate a string representation of a set
+template <typename T> std::string generate_set(const T &set) {
+    using element_t = typename detail::element_type<T>::type;
+    using iteration_type_t = typename detail::pair_adaptor<element_t>::value_type;  // the type of the object pair
+    std::string out(1, '{');
+    out.append(detail::join(
+        detail::smart_deref(set),
+        [](const iteration_type_t &v) { return detail::pair_adaptor<element_t>::first(v); },
+        ","));
+    out.push_back('}');
+    return out;
+}
+
+/// Generate a string representation of a map
+template <typename T> std::string generate_map(const T &map, bool key_only = false) {
+    using element_t = typename detail::element_type<T>::type;
+    using iteration_type_t = typename detail::pair_adaptor<element_t>::value_type;  // the type of the object pair
+    std::string out(1, '{');
+    out.append(detail::join(
+        detail::smart_deref(map),
+        [key_only](const iteration_type_t &v) {
+            std::string res{detail::to_string(detail::pair_adaptor<element_t>::first(v))};
+
+            if(!key_only) {
+                res.append("->");
+                res += detail::to_string(detail::pair_adaptor<element_t>::second(v));
+            }
+            return res;
+        },
+        ","));
+    out.push_back('}');
+    return out;
+}
+
+template <typename C, typename V> struct has_find {
+    template <typename CC, typename VV>
+    static auto test(int) -> decltype(std::declval<CC>().find(std::declval<VV>()), std::true_type());
+    template <typename, typename> static auto test(...) -> decltype(std::false_type());
+
+    static const auto value = decltype(test<C, V>(0))::value;
+    using type = std::integral_constant<bool, value>;
+};
+
+/// A search function
+template <typename T, typename V, enable_if_t<!has_find<T, V>::value, detail::enabler> = detail::dummy>
+auto search(const T &set, const V &val) -> std::pair<bool, decltype(std::begin(detail::smart_deref(set)))> {
+    using element_t = typename detail::element_type<T>::type;
+    auto &setref = detail::smart_deref(set);
+    auto it = std::find_if(std::begin(setref), std::end(setref), [&val](decltype(*std::begin(setref)) v) {
+        return (detail::pair_adaptor<element_t>::first(v) == val);
+    });
+    return {(it != std::end(setref)), it};
+}
+
+/// A search function that uses the built in find function
+template <typename T, typename V, enable_if_t<has_find<T, V>::value, detail::enabler> = detail::dummy>
+auto search(const T &set, const V &val) -> std::pair<bool, decltype(std::begin(detail::smart_deref(set)))> {
+    auto &setref = detail::smart_deref(set);
+    auto it = setref.find(val);
+    return {(it != std::end(setref)), it};
+}
+
+/// A search function with a filter function
+template <typename T, typename V>
+auto search(const T &set, const V &val, const std::function<V(V)> &filter_function)
+    -> std::pair<bool, decltype(std::begin(detail::smart_deref(set)))> {
+    using element_t = typename detail::element_type<T>::type;
+    // do the potentially faster first search
+    auto res = search(set, val);
+    if((res.first) || (!(filter_function))) {
+        return res;
+    }
+    // if we haven't found it do the longer linear search with all the element translations
+    auto &setref = detail::smart_deref(set);
+    auto it = std::find_if(std::begin(setref), std::end(setref), [&](decltype(*std::begin(setref)) v) {
+        V a{detail::pair_adaptor<element_t>::first(v)};
+        a = filter_function(a);
+        return (a == val);
+    });
+    return {(it != std::end(setref)), it};
+}
+
+}  // namespace detail
+   /// Verify items are in a set
+class IsMember : public Validator {
+  public:
+    using filter_fn_t = std::function<std::string(std::string)>;
+
+    /// This allows in-place construction using an initializer list
+    template <typename T, typename... Args>
+    IsMember(std::initializer_list<T> values, Args &&...args)
+        : IsMember(std::vector<T>(values), std::forward<Args>(args)...) {}
+
+    /// This checks to see if an item is in a set (empty function)
+    template <typename T> explicit IsMember(T &&set) : IsMember(std::forward<T>(set), nullptr) {}
+
+    /// This checks to see if an item is in a set: pointer or copy version. You can pass in a function that will filter
+    /// both sides of the comparison before computing the comparison.
+    template <typename T, typename F> explicit IsMember(T set, F filter_function) {
+
+        // Get the type of the contained item - requires a container have ::value_type
+        // if the type does not have first_type and second_type, these are both value_type
+        using element_t = typename detail::element_type<T>::type;             // Removes (smart) pointers if needed
+        using item_t = typename detail::pair_adaptor<element_t>::first_type;  // Is value_type if not a map
+
+        using local_item_t = typename IsMemberType<item_t>::type;  // This will convert bad types to good ones
+        // (const char * to std::string)
+
+        // Make a local copy of the filter function, using a std::function if not one already
+        std::function<local_item_t(local_item_t)> filter_fn = filter_function;
+
+        // This is the type name for help, it will take the current version of the set contents
+        desc_function_ = [set]() { return detail::generate_set(detail::smart_deref(set)); };
+
+        // This is the function that validates
+        // It stores a copy of the set pointer-like, so shared_ptr will stay alive
+        func_ = [set, filter_fn](std::string &input) {
+            using CLI::detail::lexical_cast;
+            local_item_t b;
+            if(!lexical_cast(input, b)) {
+                throw ValidationError(input);  // name is added later
+            }
+            if(filter_fn) {
+                b = filter_fn(b);
+            }
+            auto res = detail::search(set, b, filter_fn);
+            if(res.first) {
+                // Make sure the version in the input string is identical to the one in the set
+                if(filter_fn) {
+                    input = detail::value_string(detail::pair_adaptor<element_t>::first(*(res.second)));
+                }
+
+                // Return empty error string (success)
+                return std::string{};
+            }
+
+            // If you reach this point, the result was not found
+            return input + " not in " + detail::generate_set(detail::smart_deref(set));
+        };
+    }
+
+    /// You can pass in as many filter functions as you like, they nest (string only currently)
+    template <typename T, typename... Args>
+    IsMember(T &&set, filter_fn_t filter_fn_1, filter_fn_t filter_fn_2, Args &&...other)
+        : IsMember(
+              std::forward<T>(set),
+              [filter_fn_1, filter_fn_2](std::string a) { return filter_fn_2(filter_fn_1(a)); },
+              other...) {}
+};
+
+/// definition of the default transformation object
+template <typename T> using TransformPairs = std::vector<std::pair<std::string, T>>;
+
+/// Translate named items to other or a value set
+class Transformer : public Validator {
+  public:
+    using filter_fn_t = std::function<std::string(std::string)>;
+
+    /// This allows in-place construction
+    template <typename... Args>
+    Transformer(std::initializer_list<std::pair<std::string, std::string>> values, Args &&...args)
+        : Transformer(TransformPairs<std::string>(values), std::forward<Args>(args)...) {}
+
+    /// direct map of std::string to std::string
+    template <typename T> explicit Transformer(T &&mapping) : Transformer(std::forward<T>(mapping), nullptr) {}
+
+    /// This checks to see if an item is in a set: pointer or copy version. You can pass in a function that will filter
+    /// both sides of the comparison before computing the comparison.
+    template <typename T, typename F> explicit Transformer(T mapping, F filter_function) {
+
+        static_assert(detail::pair_adaptor<typename detail::element_type<T>::type>::value,
+                      "mapping must produce value pairs");
+        // Get the type of the contained item - requires a container have ::value_type
+        // if the type does not have first_type and second_type, these are both value_type
+        using element_t = typename detail::element_type<T>::type;             // Removes (smart) pointers if needed
+        using item_t = typename detail::pair_adaptor<element_t>::first_type;  // Is value_type if not a map
+        using local_item_t = typename IsMemberType<item_t>::type;             // Will convert bad types to good ones
+        // (const char * to std::string)
+
+        // Make a local copy of the filter function, using a std::function if not one already
+        std::function<local_item_t(local_item_t)> filter_fn = filter_function;
+
+        // This is the type name for help, it will take the current version of the set contents
+        desc_function_ = [mapping]() { return detail::generate_map(detail::smart_deref(mapping)); };
+
+        func_ = [mapping, filter_fn](std::string &input) {
+            using CLI::detail::lexical_cast;
+            local_item_t b;
+            if(!lexical_cast(input, b)) {
+                return std::string();
+                // there is no possible way we can match anything in the mapping if we can't convert so just return
+            }
+            if(filter_fn) {
+                b = filter_fn(b);
+            }
+            auto res = detail::search(mapping, b, filter_fn);
+            if(res.first) {
+                input = detail::value_string(detail::pair_adaptor<element_t>::second(*res.second));
+            }
+            return std::string{};
+        };
+    }
+
+    /// You can pass in as many filter functions as you like, they nest
+    template <typename T, typename... Args>
+    Transformer(T &&mapping, filter_fn_t filter_fn_1, filter_fn_t filter_fn_2, Args &&...other)
+        : Transformer(
+              std::forward<T>(mapping),
+              [filter_fn_1, filter_fn_2](std::string a) { return filter_fn_2(filter_fn_1(a)); },
+              other...) {}
+};
+
+/// translate named items to other or a value set
+class CheckedTransformer : public Validator {
+  public:
+    using filter_fn_t = std::function<std::string(std::string)>;
+
+    /// This allows in-place construction
+    template <typename... Args>
+    CheckedTransformer(std::initializer_list<std::pair<std::string, std::string>> values, Args &&...args)
+        : CheckedTransformer(TransformPairs<std::string>(values), std::forward<Args>(args)...) {}
+
+    /// direct map of std::string to std::string
+    template <typename T> explicit CheckedTransformer(T mapping) : CheckedTransformer(std::move(mapping), nullptr) {}
+
+    /// This checks to see if an item is in a set: pointer or copy version. You can pass in a function that will filter
+    /// both sides of the comparison before computing the comparison.
+    template <typename T, typename F> explicit CheckedTransformer(T mapping, F filter_function) {
+
+        static_assert(detail::pair_adaptor<typename detail::element_type<T>::type>::value,
+                      "mapping must produce value pairs");
+        // Get the type of the contained item - requires a container have ::value_type
+        // if the type does not have first_type and second_type, these are both value_type
+        using element_t = typename detail::element_type<T>::type;             // Removes (smart) pointers if needed
+        using item_t = typename detail::pair_adaptor<element_t>::first_type;  // Is value_type if not a map
+        using local_item_t = typename IsMemberType<item_t>::type;             // Will convert bad types to good ones
+        // (const char * to std::string)
+        using iteration_type_t = typename detail::pair_adaptor<element_t>::value_type;  // the type of the object pair
+
+        // Make a local copy of the filter function, using a std::function if not one already
+        std::function<local_item_t(local_item_t)> filter_fn = filter_function;
+
+        auto tfunc = [mapping]() {
+            std::string out("value in ");
+            out += detail::generate_map(detail::smart_deref(mapping)) + " OR {";
+            out += detail::join(
+                detail::smart_deref(mapping),
+                [](const iteration_type_t &v) {
+                    return detail::value_string(detail::pair_adaptor<element_t>::second(v));
+                },
+                ",");
+            out.push_back('}');
+            return out;
+        };
+
+        desc_function_ = tfunc;
+
+        func_ = [mapping, tfunc, filter_fn](std::string &input) {
+            using CLI::detail::lexical_cast;
+            local_item_t b;
+            bool converted = lexical_cast(input, b);
+            if(converted) {
+                if(filter_fn) {
+                    b = filter_fn(b);
+                }
+                auto res = detail::search(mapping, b, filter_fn);
+                if(res.first) {
+                    input = detail::value_string(detail::pair_adaptor<element_t>::second(*res.second));
+                    return std::string{};
+                }
+            }
+            for(const auto &v : detail::smart_deref(mapping)) {
+                auto output_string = detail::value_string(detail::pair_adaptor<element_t>::second(v));
+                if(output_string == input) {
+                    return std::string();
+                }
+            }
+
+            return "Check " + input + " " + tfunc() + " FAILED";
+        };
+    }
+
+    /// You can pass in as many filter functions as you like, they nest
+    template <typename T, typename... Args>
+    CheckedTransformer(T &&mapping, filter_fn_t filter_fn_1, filter_fn_t filter_fn_2, Args &&...other)
+        : CheckedTransformer(
+              std::forward<T>(mapping),
+              [filter_fn_1, filter_fn_2](std::string a) { return filter_fn_2(filter_fn_1(a)); },
+              other...) {}
+};
+
+/// Helper function to allow ignore_case to be passed to IsMember or Transform
+inline std::string ignore_case(std::string item) { return detail::to_lower(item); }
+
+/// Helper function to allow ignore_underscore to be passed to IsMember or Transform
+inline std::string ignore_underscore(std::string item) { return detail::remove_underscore(item); }
+
+/// Helper function to allow checks to ignore spaces to be passed to IsMember or Transform
+inline std::string ignore_space(std::string item) {
+    item.erase(std::remove(std::begin(item), std::end(item), ' '), std::end(item));
+    item.erase(std::remove(std::begin(item), std::end(item), '\t'), std::end(item));
+    return item;
+}
+
+/// Multiply a number by a factor using given mapping.
+/// Can be used to write transforms for SIZE or DURATION inputs.
+///
+/// Example:
+///   With mapping = `{"b"->1, "kb"->1024, "mb"->1024*1024}`
+///   one can recognize inputs like "100", "12kb", "100 MB",
+///   that will be automatically transformed to 100, 14448, 104857600.
+///
+/// Output number type matches the type in the provided mapping.
+/// Therefore, if it is required to interpret real inputs like "0.42 s",
+/// the mapping should be of a type <string, float> or <string, double>.
+class AsNumberWithUnit : public Validator {
+  public:
+    /// Adjust AsNumberWithUnit behavior.
+    /// CASE_SENSITIVE/CASE_INSENSITIVE controls how units are matched.
+    /// UNIT_OPTIONAL/UNIT_REQUIRED throws ValidationError
+    ///   if UNIT_REQUIRED is set and unit literal is not found.
+    enum Options : std::uint8_t {
+        CASE_SENSITIVE = 0,
+        CASE_INSENSITIVE = 1,
+        UNIT_OPTIONAL = 0,
+        UNIT_REQUIRED = 2,
+        DEFAULT = CASE_INSENSITIVE | UNIT_OPTIONAL
+    };
+
+    template <typename Number>
+    explicit AsNumberWithUnit(std::map<std::string, Number> mapping,
+                              Options opts = DEFAULT,
+                              const std::string &unit_name = "UNIT") {
+        description(generate_description<Number>(unit_name, opts));
+        validate_mapping(mapping, opts);
+
+        // transform function
+        func_ = [mapping, opts](std::string &input) -> std::string {
+            Number num{};
+
+            detail::rtrim(input);
+            if(input.empty()) {
+                throw ValidationError("Input is empty");
+            }
+
+            // Find split position between number and prefix
+            auto unit_begin = input.end();
+            while(unit_begin > input.begin() && std::isalpha(*(unit_begin - 1), std::locale())) {
+                --unit_begin;
+            }
+
+            std::string unit{unit_begin, input.end()};
+            input.resize(static_cast<std::size_t>(std::distance(input.begin(), unit_begin)));
+            detail::trim(input);
+
+            if(opts & UNIT_REQUIRED && unit.empty()) {
+                throw ValidationError("Missing mandatory unit");
+            }
+            if(opts & CASE_INSENSITIVE) {
+                unit = detail::to_lower(unit);
+            }
+            if(unit.empty()) {
+                using CLI::detail::lexical_cast;
+                if(!lexical_cast(input, num)) {
+                    throw ValidationError(std::string("Value ") + input + " could not be converted to " +
+                                          detail::type_name<Number>());
+                }
+                // No need to modify input if no unit passed
+                return {};
+            }
+
+            // find corresponding factor
+            auto it = mapping.find(unit);
+            if(it == mapping.end()) {
+                throw ValidationError(unit +
+                                      " unit not recognized. "
+                                      "Allowed values: " +
+                                      detail::generate_map(mapping, true));
+            }
+
+            if(!input.empty()) {
+                using CLI::detail::lexical_cast;
+                bool converted = lexical_cast(input, num);
+                if(!converted) {
+                    throw ValidationError(std::string("Value ") + input + " could not be converted to " +
+                                          detail::type_name<Number>());
+                }
+                // perform safe multiplication
+                bool ok = detail::checked_multiply(num, it->second);
+                if(!ok) {
+                    throw ValidationError(detail::to_string(num) + " multiplied by " + unit +
+                                          " factor would cause number overflow. Use smaller value.");
+                }
+            } else {
+                num = static_cast<Number>(it->second);
+            }
+
+            input = detail::to_string(num);
+
+            return {};
+        };
+    }
+
+  private:
+    /// Check that mapping contains valid units.
+    /// Update mapping for CASE_INSENSITIVE mode.
+    template <typename Number> static void validate_mapping(std::map<std::string, Number> &mapping, Options opts) {
+        for(auto &kv : mapping) {
+            if(kv.first.empty()) {
+                throw ValidationError("Unit must not be empty.");
+            }
+            if(!detail::isalpha(kv.first)) {
+                throw ValidationError("Unit must contain only letters.");
+            }
+        }
+
+        // make all units lowercase if CASE_INSENSITIVE
+        if(opts & CASE_INSENSITIVE) {
+            std::map<std::string, Number> lower_mapping;
+            for(auto &kv : mapping) {
+                auto s = detail::to_lower(kv.first);
+                if(lower_mapping.count(s)) {
+                    throw ValidationError(std::string("Several matching lowercase unit representations are found: ") +
+                                          s);
+                }
+                lower_mapping[detail::to_lower(kv.first)] = kv.second;
+            }
+            mapping = std::move(lower_mapping);
+        }
+    }
+
+    /// Generate description like this: NUMBER [UNIT]
+    template <typename Number> static std::string generate_description(const std::string &name, Options opts) {
+        std::stringstream out;
+        out << detail::type_name<Number>() << ' ';
+        if(opts & UNIT_REQUIRED) {
+            out << name;
+        } else {
+            out << '[' << name << ']';
+        }
+        return out.str();
+    }
+};
+
+inline AsNumberWithUnit::Options operator|(const AsNumberWithUnit::Options &a, const AsNumberWithUnit::Options &b) {
+    return static_cast<AsNumberWithUnit::Options>(static_cast<int>(a) | static_cast<int>(b));
+}
+
+/// Converts a human-readable size string (with unit literal) to uin64_t size.
+/// Example:
+///   "100" => 100
+///   "1 b" => 100
+///   "10Kb" => 10240 // you can configure this to be interpreted as kilobyte (*1000) or kibibyte (*1024)
+///   "10 KB" => 10240
+///   "10 kb" => 10240
+///   "10 kib" => 10240 // *i, *ib are always interpreted as *bibyte (*1024)
+///   "10kb" => 10240
+///   "2 MB" => 2097152
+///   "2 EiB" => 2^61 // Units up to exibyte are supported
+class AsSizeValue : public AsNumberWithUnit {
+  public:
+    using result_t = std::uint64_t;
+
+    /// If kb_is_1000 is true,
+    /// interpret 'kb', 'k' as 1000 and 'kib', 'ki' as 1024
+    /// (same applies to higher order units as well).
+    /// Otherwise, interpret all literals as factors of 1024.
+    /// The first option is formally correct, but
+    /// the second interpretation is more wide-spread
+    /// (see https://en.wikipedia.org/wiki/Binary_prefix).
+    explicit AsSizeValue(bool kb_is_1000);
+
+  private:
+    /// Get <size unit, factor> mapping
+    static std::map<std::string, result_t> init_mapping(bool kb_is_1000);
+
+    /// Cache calculated mapping
+    static std::map<std::string, result_t> get_mapping(bool kb_is_1000);
+};
+
+#if defined(CLI11_ENABLE_EXTRA_VALIDATORS) && CLI11_ENABLE_EXTRA_VALIDATORS != 0
+// new extra validators
+#if CLI11_HAS_FILESYSTEM
+namespace detail {
+enum class Permission : std::uint8_t { none = 0, read = 1, write = 2, exec = 4 };
+class PermissionValidator : public Validator {
+  public:
+    explicit PermissionValidator(Permission permission);
+};
+}  // namespace detail
+
+/// Check that the file exist and available for read
+const detail::PermissionValidator ReadPermissions(detail::Permission::read);
+
+/// Check that the file exist and available for write
+const detail::PermissionValidator WritePermissions(detail::Permission::write);
+
+/// Check that the file exist and available for write
+const detail::PermissionValidator ExecPermissions(detail::Permission::exec);
+#endif
+
+#endif
+
+
+
+namespace detail {
+
+CLI11_INLINE IPV4Validator::IPV4Validator() : Validator("IPV4") {
+    func_ = [](std::string &ip_addr) {
+        auto cdot = std::count(ip_addr.begin(), ip_addr.end(), '.');
+        if(cdot != 3u) {
+            return std::string("Invalid IPV4 address: must have 3 separators");
+        }
+        auto result = CLI::detail::split(ip_addr, '.');
+        if(result.size() != 4) {
+            return std::string("Invalid IPV4 address: must have four parts (") + ip_addr + ')';
+        }
+        int num = 0;
+        for(const auto &var : result) {
+            using CLI::detail::lexical_cast;
+            bool retval = lexical_cast(var, num);
+            if(!retval) {
+                return std::string("Failed parsing number (") + var + ')';
+            }
+            if(num < 0 || num > 255) {
+                return std::string("Each IP number must be between 0 and 255 ") + var;
+            }
+        }
+        return std::string{};
+    };
+}
+
+}  // namespace detail
+
+CLI11_INLINE AsSizeValue::AsSizeValue(bool kb_is_1000) : AsNumberWithUnit(get_mapping(kb_is_1000)) {
+    if(kb_is_1000) {
+        description("SIZE [b, kb(=1000b), kib(=1024b), ...]");
+    } else {
+        description("SIZE [b, kb(=1024b), ...]");
+    }
+}
+
+CLI11_INLINE std::map<std::string, AsSizeValue::result_t> AsSizeValue::init_mapping(bool kb_is_1000) {
+    std::map<std::string, result_t> m;
+    result_t k_factor = kb_is_1000 ? 1000 : 1024;
+    result_t ki_factor = 1024;
+    result_t k = 1;
+    result_t ki = 1;
+    m["b"] = 1;
+    for(std::string p : {"k", "m", "g", "t", "p", "e"}) {
+        k *= k_factor;
+        ki *= ki_factor;
+        m[p] = k;
+        m[p + "b"] = k;
+        m[p + "i"] = ki;
+        m[p + "ib"] = ki;
+    }
+    return m;
+}
+
+CLI11_INLINE std::map<std::string, AsSizeValue::result_t> AsSizeValue::get_mapping(bool kb_is_1000) {
+    if(kb_is_1000) {
+        static auto m = init_mapping(true);
+        return m;
+    }
+    static auto m = init_mapping(false);
+    return m;
+}
+
+namespace detail {}  // namespace detail
+/// @}
+
+#if defined(CLI11_ENABLE_EXTRA_VALIDATORS) && CLI11_ENABLE_EXTRA_VALIDATORS != 0
+// new extra validators
+namespace detail {
+
+#if defined CLI11_HAS_FILESYSTEM && CLI11_HAS_FILESYSTEM > 0
+CLI11_INLINE PermissionValidator::PermissionValidator(Permission permission) {
+    std::filesystem::perms permission_code = std::filesystem::perms::none;
+    std::string permission_name;
+    switch(permission) {
+    case Permission::read:
+        permission_code = std::filesystem::perms::owner_read | std::filesystem::perms::group_read |
+                          std::filesystem::perms::others_read;
+        permission_name = "read";
+        break;
+    case Permission::write:
+        permission_code = std::filesystem::perms::owner_write | std::filesystem::perms::group_write |
+                          std::filesystem::perms::others_write;
+        permission_name = "write";
+        break;
+    case Permission::exec:
+        permission_code = std::filesystem::perms::owner_exec | std::filesystem::perms::group_exec |
+                          std::filesystem::perms::others_exec;
+        permission_name = "exec";
+        break;
+    case Permission::none:
+    default:
+        permission_code = std::filesystem::perms::none;
+        break;
+    }
+    func_ = [permission_code](std::string &path) {
+        std::error_code ec;
+        auto p = std::filesystem::path(path);
+        if(!std::filesystem::exists(p, ec)) {
+            return std::string("Path does not exist: ") + path;
+        }
+        if(ec) {
+            return std::string("Error checking path: ") + ec.message();  // LCOV_EXCL_LINE
+        }
+        if(permission_code == std::filesystem::perms::none) {
+            return std::string{};
+        }
+        auto perms = std::filesystem::status(p, ec).permissions();
+        if(ec) {
+            return std::string("Error checking path status: ") + ec.message();  // LCOV_EXCL_LINE
+        }
+        if((perms & permission_code) == std::filesystem::perms::none) {
+            return std::string("Path does not have required permissions: ") + path;
+        }
+        return std::string{};
+    };
+    description("Path with " + permission_name + " permission");
+}
+#endif
+
+}  // namespace detail
+#endif
+
+
+
+class Option;
+class App;
+
+/// This enum signifies the type of help requested
+///
+/// This is passed in by App; all user classes must accept this as
+/// the second argument.
+
+enum class AppFormatMode : std::uint8_t {
+    Normal,  ///< The normal, detailed help
+    All,     ///< A fully expanded help
+    Sub,     ///< Used when printed as part of expanded subcommand
+};
+
+/// This is the minimum requirements to run a formatter.
+///
+/// A user can subclass this is if they do not care at all
+/// about the structure in CLI::Formatter.
+class FormatterBase {
+  protected:
+    /// @name Options
+    ///@{
+
+    /// The width of the left column (options/flags/subcommands)
+    std::size_t column_width_{30};
+
+    /// The alignment ratio for long options within the left column
+    float long_option_alignment_ratio_{1 / 3.f};
+
+    /// The width of the right column (description of options/flags/subcommands)
+    std::size_t right_column_width_{65};
+
+    /// The width of the description paragraph at the top of help
+    std::size_t description_paragraph_width_{80};
+
+    /// The width of the footer paragraph
+    std::size_t footer_paragraph_width_{80};
+
+    /// options controlling formatting for footer and descriptions
+    bool enable_description_formatting_{true};
+    bool enable_footer_formatting_{true};
+
+    /// options controlling formatting of options
+    bool enable_option_defaults_{true};
+    bool enable_option_type_names_{true};
+    bool enable_default_flag_values_{true};
+    /// @brief The required help printout labels (user changeable)
+    /// Values are Needs, Excludes, etc.
+    std::map<std::string, std::string> labels_{};
+
+    ///@}
+    /// @name Basic
+    ///@{
+
+  public:
+    FormatterBase() = default;
+    FormatterBase(const FormatterBase &) = default;
+    FormatterBase(FormatterBase &&) = default;
+    FormatterBase &operator=(const FormatterBase &) = default;
+    FormatterBase &operator=(FormatterBase &&) = default;
+
+    /// Adding a destructor in this form to work around bug in GCC 4.7
+    virtual ~FormatterBase() noexcept {}  // NOLINT(modernize-use-equals-default)
+
+    /// This is the key method that puts together help
+    virtual std::string make_help(const App *, std::string, AppFormatMode) const = 0;
+
+    ///@}
+    /// @name Setters
+    ///@{
+
+    /// Set the "REQUIRED" or other labels
+    void label(std::string key, std::string val) { labels_[key] = val; }
+
+    /// Set the left column width (options/flags/subcommands)
+    void column_width(std::size_t val) { column_width_ = val; }
+
+    /// Set the alignment ratio for long options within the left column
+    /// The ratio is in [0;1] range (e.g. 0.2 = 20% of column width, 6.f/column_width = 6th character)
+    void long_option_alignment_ratio(float ratio) {
+        long_option_alignment_ratio_ =
+            (ratio >= 0.0f) ? ((ratio <= 1.0f) ? ratio : 1.0f / ratio) : ((ratio < -1.0f) ? 1.0f / (-ratio) : -ratio);
+    }
+
+    /// Set the right column width (description of options/flags/subcommands)
+    void right_column_width(std::size_t val) { right_column_width_ = val; }
+
+    /// Set the description paragraph width at the top of help
+    void description_paragraph_width(std::size_t val) { description_paragraph_width_ = val; }
+
+    /// Set the footer paragraph width
+    void footer_paragraph_width(std::size_t val) { footer_paragraph_width_ = val; }
+    /// enable formatting for description paragraph
+    void enable_description_formatting(bool value = true) { enable_description_formatting_ = value; }
+    /// disable formatting for footer paragraph
+    void enable_footer_formatting(bool value = true) { enable_footer_formatting_ = value; }
+
+    /// enable option defaults to be printed
+    void enable_option_defaults(bool value = true) { enable_option_defaults_ = value; }
+    /// enable option type names to be printed
+    void enable_option_type_names(bool value = true) { enable_option_type_names_ = value; }
+    /// enable default flag values to be printed
+    void enable_default_flag_values(bool value = true) { enable_default_flag_values_ = value; }
+    ///@}
+    /// @name Getters
+    ///@{
+
+    /// Get the current value of a name (REQUIRED, etc.)
+    CLI11_NODISCARD std::string get_label(std::string key) const {
+        if(labels_.find(key) == labels_.end())
+            return key;
+        return labels_.at(key);
+    }
+
+    /// Get the current left column width (options/flags/subcommands)
+    CLI11_NODISCARD std::size_t get_column_width() const { return column_width_; }
+
+    /// Get the current right column width (description of options/flags/subcommands)
+    CLI11_NODISCARD std::size_t get_right_column_width() const { return right_column_width_; }
+
+    /// Get the current description paragraph width at the top of help
+    CLI11_NODISCARD std::size_t get_description_paragraph_width() const { return description_paragraph_width_; }
+
+    /// Get the current footer paragraph width
+    CLI11_NODISCARD std::size_t get_footer_paragraph_width() const { return footer_paragraph_width_; }
+
+    /// @brief Get the current alignment ratio for long options within the left column
+    /// @return
+    CLI11_NODISCARD float get_long_option_alignment_ratio() const { return long_option_alignment_ratio_; }
+
+    /// Get the current status of description paragraph formatting
+    CLI11_NODISCARD bool is_description_paragraph_formatting_enabled() const { return enable_description_formatting_; }
+
+    /// Get the current status of whether footer paragraph formatting is enabled
+    CLI11_NODISCARD bool is_footer_paragraph_formatting_enabled() const { return enable_footer_formatting_; }
+
+    /// Get the current status of whether option defaults are printed
+    CLI11_NODISCARD bool is_option_defaults_enabled() const { return enable_option_defaults_; }
+
+    /// Get the current status of whether option type names are printed
+    CLI11_NODISCARD bool is_option_type_names_enabled() const { return enable_option_type_names_; }
+
+    /// Get the current status of whether default flag values are printed
+    CLI11_NODISCARD bool is_default_flag_values_enabled() const { return enable_default_flag_values_; }
+
+    ///@}
+};
+
+/// This is a specialty override for lambda functions
+class FormatterLambda final : public FormatterBase {
+    using funct_t = std::function<std::string(const App *, std::string, AppFormatMode)>;
+
+    /// The lambda to hold and run
+    funct_t lambda_;
+
+  public:
+    /// Create a FormatterLambda with a lambda function
+    explicit FormatterLambda(funct_t funct) : lambda_(std::move(funct)) {}
+
+    /// Adding a destructor (mostly to make GCC 4.7 happy)
+    ~FormatterLambda() noexcept override {}  // NOLINT(modernize-use-equals-default)
+
+    /// This will simply call the lambda function
+    std::string make_help(const App *app, std::string name, AppFormatMode mode) const override {
+        return lambda_(app, name, mode);
+    }
+};
+
+/// This is the default Formatter for CLI11. It pretty prints help output, and is broken into quite a few
+/// overridable methods, to be highly customizable with minimal effort.
+class Formatter : public FormatterBase {
+  public:
+    Formatter() = default;
+    Formatter(const Formatter &) = default;
+    Formatter(Formatter &&) = default;
+    Formatter &operator=(const Formatter &) = default;
+    Formatter &operator=(Formatter &&) = default;
+
+    /// @name Overridables
+    ///@{
+
+    /// This prints out a group of options with title
+    ///
+    CLI11_NODISCARD virtual std::string
+    make_group(std::string group, bool is_positional, std::vector<const Option *> opts) const;
+
+    /// This prints out just the positionals "group"
+    virtual std::string make_positionals(const App *app) const;
+
+    /// This prints out all the groups of options
+    std::string make_groups(const App *app, AppFormatMode mode) const;
+
+    /// This prints out all the subcommands
+    virtual std::string make_subcommands(const App *app, AppFormatMode mode) const;
+
+    /// This prints out a subcommand
+    virtual std::string make_subcommand(const App *sub) const;
+
+    /// This prints out a subcommand in help-all
+    virtual std::string make_expanded(const App *sub, AppFormatMode mode) const;
+
+    /// This prints out all the groups of options
+    virtual std::string make_footer(const App *app) const;
+
+    /// This displays the description line
+    virtual std::string make_description(const App *app) const;
+
+    /// This displays the usage line
+    virtual std::string make_usage(const App *app, std::string name) const;
+
+    /// This puts everything together
+    std::string make_help(const App *app, std::string, AppFormatMode mode) const override;
+
+    ///@}
+    /// @name Options
+    ///@{
+
+    /// This prints out an option help line, either positional or optional form
+    virtual std::string make_option(const Option *, bool) const;
+
+    /// @brief This is the name part of an option, Default: left column
+    virtual std::string make_option_name(const Option *, bool) const;
+
+    /// @brief This is the options part of the name, Default: combined into left column
+    virtual std::string make_option_opts(const Option *) const;
+
+    /// @brief This is the description. Default: Right column, on new line if left column too large
+    virtual std::string make_option_desc(const Option *) const;
+
+    /// @brief This is used to print the name on the USAGE line
+    virtual std::string make_option_usage(const Option *opt) const;
+
+    ///@}
+};
+
+
+
+
+using results_t = std::vector<std::string>;
+/// callback function definition
+using callback_t = std::function<bool(const results_t &)>;
+
+class Option;
+class App;
+class ConfigBase;
+
+using Option_p = std::unique_ptr<Option>;
+using Validator_p = std::shared_ptr<Validator>;
+
+/// Enumeration of the multiOption Policy selection
+enum class MultiOptionPolicy : char {
+    Throw,      //!< Throw an error if any extra arguments were given
+    TakeLast,   //!< take only the last Expected number of arguments
+    TakeFirst,  //!< take only the first Expected number of arguments
+    Join,       //!< merge all the arguments together into a single string via the delimiter character default('\n')
+    TakeAll,    //!< just get all the passed argument regardless
+    Sum,        //!< sum all the arguments together if numerical or concatenate directly without delimiter
+    Reverse,    //!< take only the last Expected number of arguments in reverse order
+};
+
+/// @brief  enumeration for the callback priority
+enum class CallbackPriority : std::uint8_t {
+    FirstPreHelp = 0,
+    First = 1,
+    PreRequirementsCheckPreHelp = 2,
+    PreRequirementsCheck = 3,
+    NormalPreHelp = 4,
+    Normal = 5,
+    LastPreHelp = 6,
+    Last = 7
+};  // namespace CLI
+
+/// This is the CRTP base class for Option and OptionDefaults. It was designed this way
+/// to share parts of the class; an OptionDefaults can copy to an Option.
+template <typename CRTP> class OptionBase {
+    friend App;
+    friend ConfigBase;
+
+  protected:
+    /// The group membership
+    std::string group_ = std::string("OPTIONS");
+
+    /// True if this is a required option
+    bool required_{false};
+
+    /// Ignore the case when matching (option, not value)
+    bool ignore_case_{false};
+
+    /// Ignore underscores when matching (option, not value)
+    bool ignore_underscore_{false};
+
+    /// Allow this option to be given in a configuration file
+    bool configurable_{true};
+
+    /// Disable overriding flag values with '=value'
+    bool disable_flag_override_{false};
+
+    /// Specify a delimiter character for vector arguments
+    char delimiter_{'\0'};
+
+    /// Automatically capture default value
+    bool always_capture_default_{false};
+
+    /// Policy for handling multiple arguments beyond the expected Max
+    MultiOptionPolicy multi_option_policy_{MultiOptionPolicy::Throw};
+
+    /// Priority of callback
+    CallbackPriority callback_priority_{CallbackPriority::Normal};
+
+    /// Copy the contents to another similar class (one based on OptionBase)
+    template <typename T> void copy_to(T *other) const;
+
+  public:
+    // setters
+
+    /// Changes the group membership
+    CRTP *group(const std::string &name) {
+        if(!detail::valid_alias_name_string(name)) {
+            throw IncorrectConstruction("Group names may not contain newlines or null characters");
+        }
+        group_ = name;
+        return static_cast<CRTP *>(this);
+    }
+
+    /// Set the option as required
+    CRTP *required(bool value = true) {
+        required_ = value;
+        return static_cast<CRTP *>(this);
+    }
+
+    /// Support Plumbum term
+    CRTP *mandatory(bool value = true) { return required(value); }
+
+    CRTP *always_capture_default(bool value = true) {
+        always_capture_default_ = value;
+        return static_cast<CRTP *>(this);
+    }
+
+    // Getters
+
+    /// Get the group of this option
+    CLI11_NODISCARD const std::string &get_group() const { return group_; }
+
+    /// True if this is a required option
+    CLI11_NODISCARD bool get_required() const { return required_; }
+
+    /// The status of ignore case
+    CLI11_NODISCARD bool get_ignore_case() const { return ignore_case_; }
+
+    /// The status of ignore_underscore
+    CLI11_NODISCARD bool get_ignore_underscore() const { return ignore_underscore_; }
+
+    /// The status of configurable
+    CLI11_NODISCARD bool get_configurable() const { return configurable_; }
+
+    /// The status of configurable
+    CLI11_NODISCARD bool get_disable_flag_override() const { return disable_flag_override_; }
+
+    /// Get the current delimiter char
+    CLI11_NODISCARD char get_delimiter() const { return delimiter_; }
+
+    /// Return true if this will automatically capture the default value for help printing
+    CLI11_NODISCARD bool get_always_capture_default() const { return always_capture_default_; }
+
+    /// The status of the multi option policy
+    CLI11_NODISCARD MultiOptionPolicy get_multi_option_policy() const { return multi_option_policy_; }
+
+    /// The priority of callback
+    CLI11_NODISCARD CallbackPriority get_callback_priority() const { return callback_priority_; }
+
+    // Shortcuts for multi option policy
+
+    /// Set the multi option policy to take last
+    CRTP *take_last() {
+        auto *self = static_cast<CRTP *>(this);
+        self->multi_option_policy(MultiOptionPolicy::TakeLast);
+        return self;
+    }
+
+    /// Set the multi option policy to take last
+    CRTP *take_first() {
+        auto *self = static_cast<CRTP *>(this);
+        self->multi_option_policy(MultiOptionPolicy::TakeFirst);
+        return self;
+    }
+
+    /// Set the multi option policy to take all arguments
+    CRTP *take_all() {
+        auto self = static_cast<CRTP *>(this);
+        self->multi_option_policy(MultiOptionPolicy::TakeAll);
+        return self;
+    }
+
+    /// Set the multi option policy to join
+    CRTP *join() {
+        auto *self = static_cast<CRTP *>(this);
+        self->multi_option_policy(MultiOptionPolicy::Join);
+        return self;
+    }
+
+    /// Set the multi option policy to join with a specific delimiter
+    CRTP *join(char delim) {
+        auto self = static_cast<CRTP *>(this);
+        self->delimiter_ = delim;
+        self->multi_option_policy(MultiOptionPolicy::Join);
+        return self;
+    }
+
+    /// Allow in a configuration file
+    CRTP *configurable(bool value = true) {
+        configurable_ = value;
+        return static_cast<CRTP *>(this);
+    }
+
+    /// Allow in a configuration file
+    CRTP *delimiter(char value = '\0') {
+        delimiter_ = value;
+        return static_cast<CRTP *>(this);
+    }
+};
+
+/// This is a version of OptionBase that only supports setting values,
+/// for defaults. It is stored as the default option in an App.
+class OptionDefaults : public OptionBase<OptionDefaults> {
+  public:
+    OptionDefaults() = default;
+
+    // Methods here need a different implementation if they are Option vs. OptionDefault
+
+    /// Set the callback priority
+    OptionDefaults *callback_priority(CallbackPriority value = CallbackPriority::Normal) {
+        callback_priority_ = value;
+        return this;
+    }
+
+    /// Take the last argument if given multiple times
+    OptionDefaults *multi_option_policy(MultiOptionPolicy value = MultiOptionPolicy::Throw) {
+        multi_option_policy_ = value;
+        return this;
+    }
+
+    /// Ignore the case of the option name
+    OptionDefaults *ignore_case(bool value = true) {
+        ignore_case_ = value;
+        return this;
+    }
+
+    /// Ignore underscores in the option name
+    OptionDefaults *ignore_underscore(bool value = true) {
+        ignore_underscore_ = value;
+        return this;
+    }
+
+    /// Disable overriding flag values with an '=<value>' segment
+    OptionDefaults *disable_flag_override(bool value = true) {
+        disable_flag_override_ = value;
+        return this;
+    }
+
+    /// set a delimiter character to split up single arguments to treat as multiple inputs
+    OptionDefaults *delimiter(char value = '\0') {
+        delimiter_ = value;
+        return this;
+    }
+};
+
+class Option : public OptionBase<Option> {
+    friend App;
+    friend ConfigBase;
+
+  protected:
+    /// @name Names
+    ///@{
+
+    /// A list of the short names (`-a`) without the leading dashes
+    std::vector<std::string> snames_{};
+
+    /// A list of the long names (`--long`) without the leading dashes
+    std::vector<std::string> lnames_{};
+
+    /// A list of the flag names with the appropriate default value, the first part of the pair should be duplicates of
+    /// what is in snames or lnames but will trigger a particular response on a flag
+    std::vector<std::pair<std::string, std::string>> default_flag_values_{};
+
+    /// a list of flag names with specified default values;
+    std::vector<std::string> fnames_{};
+
+    /// A positional name
+    std::string pname_{};
+
+    /// If given, check the environment for this option
+    std::string envname_{};
+
+    ///@}
+    /// @name Help
+    ///@{
+
+    /// The description for help strings
+    std::string description_{};
+
+    /// A human readable default value, either manually set, captured, or captured by default
+    std::string default_str_{};
+
+    /// If given, replace the text that describes the option type and usage in the help text
+    std::string option_text_{};
+
+    /// A human readable type value, set when App creates this
+    ///
+    /// This is a lambda function so "types" can be dynamic, such as when a set prints its contents.
+    std::function<std::string()> type_name_{[]() { return std::string(); }};
+
+    /// Run this function to capture a default (ignore if empty)
+    std::function<std::string()> default_function_{};
+
+    ///@}
+    /// @name Configuration
+    ///@{
+
+    /// The number of arguments that make up one option. max is the nominal type size, min is the minimum number of
+    /// strings
+    int type_size_max_{1};
+    /// The minimum number of arguments an option should be expecting
+    int type_size_min_{1};
+
+    /// The minimum number of expected values
+    int expected_min_{1};
+    /// The maximum number of expected values
+    int expected_max_{1};
+
+    /// A list of Validators to run on each value parsed
+    std::vector<Validator_p> validators_{};
+
+    /// A list of options that are required with this option
+    std::set<Option *> needs_{};
+
+    /// A list of options that are excluded with this option
+    std::set<Option *> excludes_{};
+
+    ///@}
+    /// @name Other
+    ///@{
+
+    /// link back up to the parent App for fallthrough
+    App *parent_{nullptr};
+
+    /// Options store a callback to do all the work
+    callback_t callback_{};
+
+    ///@}
+    /// @name Parsing results
+    ///@{
+
+    /// complete Results of parsing
+    results_t results_{};
+    /// results after reduction
+    mutable results_t proc_results_{};
+    /// enumeration for the option state machine
+    enum class option_state : char {
+        parsing = 0,       //!< The option is currently collecting parsed results
+        validated = 2,     //!< the results have been validated
+        reduced = 4,       //!< a subset of results has been generated
+        callback_run = 6,  //!< the callback has been executed
+    };
+    /// Whether the callback has run (needed for INI parsing)
+    option_state current_option_state_{option_state::parsing};
+    /// Specify that extra args beyond type_size_max should be allowed
+    bool allow_extra_args_{false};
+    /// Specify that the option should act like a flag vs regular option
+    bool flag_like_{false};
+    /// Control option to run the callback to set the default
+    bool run_callback_for_default_{false};
+    /// flag indicating a separator needs to be injected after each argument call
+    bool inject_separator_{false};
+    /// flag indicating that the option should trigger the validation and callback chain on each result when loaded
+    bool trigger_on_result_{false};
+    /// flag indicating that the option should force the callback regardless if any results present
+    bool force_callback_{false};
+
+    /// Making an option by hand is not defined, it must be made by the App class
+    Option(std::string option_name,
+           std::string option_description,
+           callback_t callback,
+           App *parent,
+           bool allow_non_standard = false)
+        : description_(std::move(option_description)), parent_(parent), callback_(std::move(callback)) {
+        std::tie(snames_, lnames_, pname_) = detail::get_names(detail::split_names(option_name), allow_non_standard);
+    }
+
+  public:
+    /// @name Basic
+    ///@{
+
+    Option(const Option &) = delete;
+    Option &operator=(const Option &) = delete;
+
+    /// Count the total number of times an option was passed
+    CLI11_NODISCARD std::size_t count() const { return results_.size(); }
+
+    /// True if the option was not passed
+    CLI11_NODISCARD bool empty() const { return results_.empty(); }
+
+    /// This bool operator returns true if any arguments were passed or the option callback is forced
+    explicit operator bool() const { return !empty() || force_callback_; }
+
+    /// Clear the parsed results (mostly for testing)
+    void clear() {
+        results_.clear();
+        current_option_state_ = option_state::parsing;
+    }
+
+    ///@}
+    /// @name Setting options
+    ///@{
+
+    /// Set the number of expected arguments
+    Option *expected(int value);
+
+    /// Set the range of expected arguments
+    Option *expected(int value_min, int value_max);
+
+    /// Set the value of allow_extra_args which allows extra value arguments on the flag or option to be included
+    /// with each instance
+    Option *allow_extra_args(bool value = true) {
+        allow_extra_args_ = value;
+        return this;
+    }
+    /// Get the current value of allow extra args
+    CLI11_NODISCARD bool get_allow_extra_args() const { return allow_extra_args_; }
+    /// Set the value of trigger_on_parse which specifies that the option callback should be triggered on every parse
+    Option *trigger_on_parse(bool value = true) {
+        trigger_on_result_ = value;
+        return this;
+    }
+    /// The status of trigger on parse
+    CLI11_NODISCARD bool get_trigger_on_parse() const { return trigger_on_result_; }
+
+    /// Set the value of force_callback
+    Option *force_callback(bool value = true) {
+        force_callback_ = value;
+        return this;
+    }
+    /// The status of force_callback
+    CLI11_NODISCARD bool get_force_callback() const { return force_callback_; }
+
+    /// Set the value of run_callback_for_default which controls whether the callback function should be called to set
+    /// the default This is controlled automatically but could be manipulated by the user.
+    Option *run_callback_for_default(bool value = true) {
+        run_callback_for_default_ = value;
+        return this;
+    }
+    /// Get the current value of run_callback_for_default
+    CLI11_NODISCARD bool get_run_callback_for_default() const { return run_callback_for_default_; }
+
+    /// Set the value of callback priority which controls when the callback function should be called relative to other
+    /// parsing operations the default This is controlled automatically but could be manipulated by the user.
+    Option *callback_priority(CallbackPriority value = CallbackPriority::Normal) {
+        callback_priority_ = value;
+        return this;
+    }
+
+    /// Adds a shared validator
+    Option *check(Validator_p validator);
+
+    /// Adds a Validator with a built in type name
+    Option *check(Validator validator, const std::string &validator_name = "");
+
+    /// Adds a Validator. Takes a const string& and returns an error message (empty if conversion/check is okay).
+    Option *check(std::function<std::string(const std::string &)> validator_func,
+                  std::string validator_description = "",
+                  std::string validator_name = "");
+
+    /// Adds a shared Validator
+    Option *transform(Validator_p validator);
+
+    /// Adds a transforming Validator with a built in type name
+    Option *transform(Validator validator, const std::string &transform_name = "");
+
+    /// Adds a Validator-like function that can change result
+    Option *transform(const std::function<std::string(std::string)> &transform_func,
+                      std::string transform_description = "",
+                      std::string transform_name = "");
+
+    /// Adds a user supplied function to run on each item passed in (communicate though lambda capture)
+    Option *each(const std::function<void(std::string)> &func);
+
+    /// Get a named Validator
+    Validator *get_validator(const std::string &validator_name = "");
+
+    /// Get a Validator by index NOTE: this may not be the order of definition
+    Validator *get_validator(int index);
+
+    /// Sets required options
+    Option *needs(Option *opt) {
+        if(opt != this) {
+            needs_.insert(opt);
+        }
+        return this;
+    }
+
+    /// Can find a string if needed
+    template <typename T = App> Option *needs(std::string opt_name) {
+        auto opt = static_cast<T *>(parent_)->get_option_no_throw(opt_name);
+        if(opt == nullptr) {
+            throw IncorrectConstruction::MissingOption(opt_name);
+        }
+        return needs(opt);
+    }
+
+    /// Any number supported, any mix of string and Opt
+    template <typename A, typename B, typename... ARG> Option *needs(A opt, B opt1, ARG... args) {
+        needs(opt);
+        return needs(opt1, args...);  // NOLINT(readability-suspicious-call-argument)
+    }
+
+    /// Remove needs link from an option. Returns true if the option really was in the needs list.
+    bool remove_needs(Option *opt);
+
+    /// Sets excluded options
+    Option *excludes(Option *opt);
+
+    /// Can find a string if needed
+    template <typename T = App> Option *excludes(std::string opt_name) {
+        auto opt = static_cast<T *>(parent_)->get_option_no_throw(opt_name);
+        if(opt == nullptr) {
+            throw IncorrectConstruction::MissingOption(opt_name);
+        }
+        return excludes(opt);
+    }
+
+    /// Any number supported, any mix of string and Opt
+    template <typename A, typename B, typename... ARG> Option *excludes(A opt, B opt1, ARG... args) {
+        excludes(opt);
+        return excludes(opt1, args...);
+    }
+
+    /// Remove needs link from an option. Returns true if the option really was in the needs list.
+    bool remove_excludes(Option *opt);
+
+    /// Sets environment variable to read if no option given
+    Option *envname(std::string name) {
+        envname_ = std::move(name);
+        return this;
+    }
+
+    /// Ignore case
+    ///
+    /// The template hides the fact that we don't have the definition of App yet.
+    /// You are never expected to add an argument to the template here.
+    template <typename T = App> Option *ignore_case(bool value = true);
+
+    /// Ignore underscores in the option names
+    ///
+    /// The template hides the fact that we don't have the definition of App yet.
+    /// You are never expected to add an argument to the template here.
+    template <typename T = App> Option *ignore_underscore(bool value = true);
+
+    /// Take the last argument if given multiple times (or another policy)
+    Option *multi_option_policy(MultiOptionPolicy value = MultiOptionPolicy::Throw);
+
+    /// Disable flag overrides values, e.g. --flag=<value> is not allowed
+    Option *disable_flag_override(bool value = true) {
+        disable_flag_override_ = value;
+        return this;
+    }
+    ///@}
+    /// @name Accessors
+    ///@{
+
+    /// The number of arguments the option expects
+    CLI11_NODISCARD int get_type_size() const { return type_size_min_; }
+
+    /// The minimum number of arguments the option expects
+    CLI11_NODISCARD int get_type_size_min() const { return type_size_min_; }
+    /// The maximum number of arguments the option expects
+    CLI11_NODISCARD int get_type_size_max() const { return type_size_max_; }
+
+    /// Return the inject_separator flag
+    CLI11_NODISCARD bool get_inject_separator() const { return inject_separator_; }
+
+    /// The environment variable associated to this value
+    CLI11_NODISCARD std::string get_envname() const { return envname_; }
+
+    /// The set of options needed
+    CLI11_NODISCARD std::set<Option *> get_needs() const { return needs_; }
+
+    /// The set of options excluded
+    CLI11_NODISCARD std::set<Option *> get_excludes() const { return excludes_; }
+
+    /// The default value (for help printing)
+    CLI11_NODISCARD std::string get_default_str() const { return default_str_; }
+
+    /// Get the callback function
+    CLI11_NODISCARD callback_t get_callback() const { return callback_; }
+
+    /// Get the long names
+    CLI11_NODISCARD const std::vector<std::string> &get_lnames() const { return lnames_; }
+
+    /// Get the short names
+    CLI11_NODISCARD const std::vector<std::string> &get_snames() const { return snames_; }
+
+    /// Get the flag names with specified default values
+    CLI11_NODISCARD const std::vector<std::string> &get_fnames() const { return fnames_; }
+    /// Get a single name for the option, first of lname, sname, pname, envname
+    CLI11_NODISCARD const std::string &get_single_name() const {
+        if(!lnames_.empty()) {
+            return lnames_[0];
+        }
+        if(!snames_.empty()) {
+            return snames_[0];
+        }
+        if(!pname_.empty()) {
+            return pname_;
+        }
+        return envname_;
+    }
+    /// The number of times the option expects to be included
+    CLI11_NODISCARD int get_expected() const { return expected_min_; }
+
+    /// The number of times the option expects to be included
+    CLI11_NODISCARD int get_expected_min() const { return expected_min_; }
+    /// The max number of times the option expects to be included
+    CLI11_NODISCARD int get_expected_max() const { return expected_max_; }
+
+    /// The total min number of expected  string values to be used
+    CLI11_NODISCARD int get_items_expected_min() const { return type_size_min_ * expected_min_; }
+
+    /// Get the maximum number of items expected to be returned and used for the callback
+    CLI11_NODISCARD int get_items_expected_max() const {
+        int t = type_size_max_;
+        return detail::checked_multiply(t, expected_max_) ? t : detail::expected_max_vector_size;
+    }
+    /// The total min number of expected  string values to be used
+    CLI11_NODISCARD int get_items_expected() const { return get_items_expected_min(); }
+
+    /// True if the argument can be given directly
+    CLI11_NODISCARD bool get_positional() const { return !pname_.empty(); }
+
+    /// True if option has at least one non-positional name
+    CLI11_NODISCARD bool nonpositional() const { return (!lnames_.empty() || !snames_.empty()); }
+
+    /// True if option has description
+    CLI11_NODISCARD bool has_description() const { return !description_.empty(); }
+
+    /// Get the description
+    CLI11_NODISCARD const std::string &get_description() const { return description_; }
+
+    /// Set the description
+    Option *description(std::string option_description) {
+        description_ = std::move(option_description);
+        return this;
+    }
+
+    Option *option_text(std::string text) {
+        option_text_ = std::move(text);
+        return this;
+    }
+
+    CLI11_NODISCARD const std::string &get_option_text() const { return option_text_; }
+
+    ///@}
+    /// @name Help tools
+    ///@{
+
+    /// \brief Gets a comma separated list of names.
+    /// Will include / prefer the positional name if positional is true.
+    /// If all_options is false, pick just the most descriptive name to show.
+    /// Use `get_name(true)` to get the positional name (replaces `get_pname`)
+    /// if disable_default_flag_values is true, do not include the default values for flags such as `--no-flag{false}`
+    CLI11_NODISCARD std::string get_name(bool positional = false,                  ///< Show the positional name
+                                         bool all_options = false,                 ///< Show every option
+                                         bool disable_default_flag_values = false  ///< Disable default values in name
+    ) const;
+
+    ///@}
+    /// @name Parser tools
+    ///@{
+
+    /// Process the callback
+    void run_callback();
+
+    /// If options share any of the same names, find it
+    CLI11_NODISCARD const std::string &matching_name(const Option &other) const;
+
+    /// If options share any of the same names, they are equal (not counting positional)
+    bool operator==(const Option &other) const { return !matching_name(other).empty(); }
+
+    /// Check a name. Requires "-" or "--" for short / long, supports positional name
+    CLI11_NODISCARD bool check_name(const std::string &name) const;
+
+    /// Requires "-" to be removed from string
+    CLI11_NODISCARD bool check_sname(std::string name) const {
+        return (detail::find_member(std::move(name), snames_, ignore_case_) >= 0);
+    }
+
+    /// Requires "--" to be removed from string
+    CLI11_NODISCARD bool check_lname(std::string name) const {
+        return (detail::find_member(std::move(name), lnames_, ignore_case_, ignore_underscore_) >= 0);
+    }
+
+    /// Requires "--" to be removed from string
+    CLI11_NODISCARD bool check_fname(std::string name) const {
+        if(fnames_.empty()) {
+            return false;
+        }
+        return (detail::find_member(std::move(name), fnames_, ignore_case_, ignore_underscore_) >= 0);
+    }
+
+    /// Get the value that goes for a flag, nominally gets the default value but allows for overrides if not
+    /// disabled
+    CLI11_NODISCARD std::string get_flag_value(const std::string &name, std::string input_value) const;
+
+    /// Puts a result at the end
+    Option *add_result(std::string s);
+
+    /// Puts a result at the end and get a count of the number of arguments actually added
+    Option *add_result(std::string s, int &results_added);
+
+    /// Puts a result at the end
+    Option *add_result(std::vector<std::string> s);
+
+    /// Get the current complete results set
+    CLI11_NODISCARD const results_t &results() const { return results_; }
+
+    /// Get a copy of the results
+    CLI11_NODISCARD results_t reduced_results() const;
+
+    /// Get the results as a specified type
+    template <typename T> void results(T &output) const {
+        bool retval = false;
+        if(current_option_state_ >= option_state::reduced || (results_.size() == 1 && validators_.empty())) {
+            const results_t &res = (proc_results_.empty()) ? results_ : proc_results_;
+            if(!res.empty()) {
+                retval = detail::lexical_conversion<T, T>(res, output);
+            } else {
+                results_t res2;
+                res2.emplace_back();
+                proc_results_ = std::move(res2);
+                retval = detail::lexical_conversion<T, T>(proc_results_, output);
+            }
+
+        } else {
+            results_t res;
+            if(results_.empty()) {
+                if(!default_str_.empty()) {
+                    // _add_results takes an rvalue only
+                    _add_result(std::string(default_str_), res);
+                    _validate_results(res);
+                    results_t extra;
+                    _reduce_results(extra, res);
+                    if(!extra.empty()) {
+                        res = std::move(extra);
+                    }
+                } else {
+                    res.emplace_back();
+                }
+            } else {
+                res = reduced_results();
+            }
+            // store the results in a stable location if the output is a view
+            proc_results_ = std::move(res);
+            retval = detail::lexical_conversion<T, T>(proc_results_, output);
+        }
+        if(!retval) {
+            throw ConversionError(get_name(), results_);
+        }
+    }
+
+    /// Return the results as the specified type
+    template <typename T> CLI11_NODISCARD T as() const {
+        T output;
+        results(output);
+        return output;
+    }
+
+    /// See if the callback has been run already
+    CLI11_NODISCARD bool get_callback_run() const { return (current_option_state_ == option_state::callback_run); }
+
+    ///@}
+    /// @name Custom options
+    ///@{
+
+    /// Set the type function to run when displayed on this option
+    Option *type_name_fn(std::function<std::string()> typefun) {
+        type_name_ = std::move(typefun);
+        return this;
+    }
+
+    /// Set a custom option typestring
+    Option *type_name(std::string typeval) {
+        type_name_fn([typeval]() { return typeval; });
+        return this;
+    }
+
+    /// Set a custom option size
+    Option *type_size(int option_type_size);
+
+    /// Set a custom option type size range
+    Option *type_size(int option_type_size_min, int option_type_size_max);
+
+    /// Set the value of the separator injection flag
+    void inject_separator(bool value = true) { inject_separator_ = value; }
+
+    /// Set a capture function for the default. Mostly used by App.
+    Option *default_function(const std::function<std::string()> &func) {
+        default_function_ = func;
+        return this;
+    }
+
+    /// Capture the default value from the original value (if it can be captured)
+    Option *capture_default_str() {
+        if(default_function_) {
+            default_str_ = default_function_();
+        }
+        return this;
+    }
+
+    /// Set the default value string representation (does not change the contained value)
+    Option *default_str(std::string val) {
+        default_str_ = std::move(val);
+        return this;
+    }
+
+    /// Set the default value and validate the results and run the callback if appropriate to set the value into the
+    /// bound value only available for types that can be converted to a string
+    template <typename X> Option *default_val(const X &val) {
+        std::string val_str = detail::value_string(val);
+        auto old_option_state = current_option_state_;
+        results_t old_results{std::move(results_)};
+        results_.clear();
+        try {
+            add_result(val_str);
+            // if trigger_on_result_ is set the callback already ran
+            if(run_callback_for_default_ && !trigger_on_result_) {
+                run_callback();  // run callback sets the state, we need to reset it again
+                current_option_state_ = option_state::parsing;
+            } else {
+                _validate_results(results_);
+                current_option_state_ = old_option_state;
+            }
+        } catch(const ConversionError &err) {
+            // this should be done
+            results_ = std::move(old_results);
+            current_option_state_ = old_option_state;
+
+            throw ConversionError(
+                get_name(), std::string("given default value(\"") + val_str + "\") produces an error : " + err.what());
+        } catch(const CLI::Error &) {
+            results_ = std::move(old_results);
+            current_option_state_ = old_option_state;
+            throw;
+        }
+        results_ = std::move(old_results);
+        default_str_ = std::move(val_str);
+        return this;
+    }
+
+    /// Get the full typename for this option
+    CLI11_NODISCARD std::string get_type_name() const;
+
+  private:
+    /// Run the results through the Validators
+    void _validate_results(results_t &res) const;
+
+    /** reduce the results in accordance with the MultiOptionPolicy
+    @param[out] out results are assigned to res if there if they are different
+    */
+    void _reduce_results(results_t &out, const results_t &original) const;
+
+    // Run a result through the Validators
+    std::string _validate(std::string &result, int index) const;
+
+    /// Add a single result to the result set, taking into account delimiters
+    int _add_result(std::string &&result, std::vector<std::string> &res) const;
+};
+
+
+
+
+template <typename CRTP> template <typename T> void OptionBase<CRTP>::copy_to(T *other) const {
+    other->group(group_);
+    other->required(required_);
+    other->ignore_case(ignore_case_);
+    other->ignore_underscore(ignore_underscore_);
+    other->configurable(configurable_);
+    other->disable_flag_override(disable_flag_override_);
+    other->delimiter(delimiter_);
+    other->always_capture_default(always_capture_default_);
+    other->multi_option_policy(multi_option_policy_);
+    other->callback_priority(callback_priority_);
+}
+
+CLI11_INLINE Option *Option::expected(int value) {
+    if(value < 0) {
+        expected_min_ = -value;
+        if(expected_max_ < expected_min_) {
+            expected_max_ = expected_min_;
+        }
+        allow_extra_args_ = true;
+        flag_like_ = false;
+    } else if(value == detail::expected_max_vector_size) {
+        expected_min_ = 1;
+        expected_max_ = detail::expected_max_vector_size;
+        allow_extra_args_ = true;
+        flag_like_ = false;
+    } else {
+        expected_min_ = value;
+        expected_max_ = value;
+        flag_like_ = (expected_min_ == 0);
+    }
+    return this;
+}
+
+CLI11_INLINE Option *Option::expected(int value_min, int value_max) {
+    if(value_min < 0) {
+        value_min = -value_min;
+    }
+
+    if(value_max < 0) {
+        value_max = detail::expected_max_vector_size;
+    }
+    if(value_max < value_min) {
+        expected_min_ = value_max;
+        expected_max_ = value_min;
+    } else {
+        expected_max_ = value_max;
+        expected_min_ = value_min;
+    }
+
+    return this;
+}
+
+CLI11_INLINE Option *Option::check(Validator_p validator) {
+    validator->non_modifying();
+    validators_.push_back(std::move(validator));
+
+    return this;
+}
+
+CLI11_INLINE Option *Option::check(Validator validator, const std::string &validator_name) {
+    validator.non_modifying();
+    auto vp = std::make_shared<Validator>(std::move(validator));
+    if(!validator_name.empty()) {
+        vp->name(validator_name);
+    }
+    validators_.push_back(std::move(vp));
+
+    return this;
+}
+
+CLI11_INLINE Option *Option::check(std::function<std::string(const std::string &)> validator_func,
+                                   std::string validator_description,
+                                   std::string validator_name) {
+
+    auto vp = std::make_shared<Validator>(
+        std::move(validator_func), std::move(validator_description), std::move(validator_name));
+    vp->non_modifying();
+    validators_.push_back(std::move(vp));
+    return this;
+}
+
+CLI11_INLINE Option *Option::transform(Validator_p validator) {
+    validators_.insert(validators_.begin(), std::move(validator));
+
+    return this;
+}
+
+CLI11_INLINE Option *Option::transform(Validator validator, const std::string &transform_name) {
+    auto vp = std::make_shared<Validator>(std::move(validator));
+    if(!transform_name.empty()) {
+        vp->name(transform_name);
+    }
+    validators_.insert(validators_.begin(), std::move(vp));
+    return this;
+}
+
+CLI11_INLINE Option *Option::transform(const std::function<std::string(std::string)> &transform_func,
+                                       std::string transform_description,
+                                       std::string transform_name) {
+    auto vp = std::make_shared<Validator>(
+        [transform_func](std::string &val) {
+            val = transform_func(val);
+            return std::string{};
+        },
+        std::move(transform_description),
+        std::move(transform_name));
+    validators_.insert(validators_.begin(), std::move(vp));
+
+    return this;
+}
+
+CLI11_INLINE Option *Option::each(const std::function<void(std::string)> &func) {
+    auto vp = std::make_shared<Validator>(
+        [func](std::string &inout) {
+            func(inout);
+            return std::string{};
+        },
+        std::string{});
+    validators_.push_back(std::move(vp));
+    return this;
+}
+
+CLI11_INLINE Validator *Option::get_validator(const std::string &validator_name) {
+    for(auto &validator : validators_) {
+        if(validator_name == validator->get_name()) {
+            return validator.get();
+        }
+    }
+    if((validator_name.empty()) && (!validators_.empty())) {
+        return validators_.front().get();
+    }
+    throw OptionNotFound(std::string{"Validator "} + validator_name + " Not Found");
+}
+
+CLI11_INLINE Validator *Option::get_validator(int index) {
+    // This is a signed int so that it is not equivalent to a pointer.
+    if(index >= 0 && index < static_cast<int>(validators_.size())) {
+        return validators_[static_cast<decltype(validators_)::size_type>(index)].get();
+    }
+    throw OptionNotFound("Validator index is not valid");
+}
+
+CLI11_INLINE bool Option::remove_needs(Option *opt) {
+    auto iterator = std::find(std::begin(needs_), std::end(needs_), opt);
+
+    if(iterator == std::end(needs_)) {
+        return false;
+    }
+    needs_.erase(iterator);
+    return true;
+}
+
+CLI11_INLINE Option *Option::excludes(Option *opt) {
+    if(opt == this) {
+        throw(IncorrectConstruction("and option cannot exclude itself"));
+    }
+    excludes_.insert(opt);
+
+    // Help text should be symmetric - excluding a should exclude b
+    opt->excludes_.insert(this);
+
+    // Ignoring the insert return value, excluding twice is now allowed.
+    // (Mostly to allow both directions to be excluded by user, even though the library does it for you.)
+
+    return this;
+}
+
+CLI11_INLINE bool Option::remove_excludes(Option *opt) {
+    auto iterator = std::find(std::begin(excludes_), std::end(excludes_), opt);
+
+    if(iterator == std::end(excludes_)) {
+        return false;
+    }
+    excludes_.erase(iterator);
+    return true;
+}
+
+template <typename T> Option *Option::ignore_case(bool value) {
+    if(!ignore_case_ && value) {
+        ignore_case_ = value;
+        auto *parent = static_cast<T *>(parent_);
+        for(const Option_p &opt : parent->options_) {
+            if(opt.get() == this) {
+                continue;
+            }
+            const auto &omatch = opt->matching_name(*this);
+            if(!omatch.empty()) {
+                ignore_case_ = false;
+                throw OptionAlreadyAdded("adding ignore case caused a name conflict with " + omatch);
+            }
+        }
+    } else {
+        ignore_case_ = value;
+    }
+    return this;
+}
+
+template <typename T> Option *Option::ignore_underscore(bool value) {
+
+    if(!ignore_underscore_ && value) {
+        ignore_underscore_ = value;
+        auto *parent = static_cast<T *>(parent_);
+        for(const Option_p &opt : parent->options_) {
+            if(opt.get() == this) {
+                continue;
+            }
+            const auto &omatch = opt->matching_name(*this);
+            if(!omatch.empty()) {
+                ignore_underscore_ = false;
+                throw OptionAlreadyAdded("adding ignore underscore caused a name conflict with " + omatch);
+            }
+        }
+    } else {
+        ignore_underscore_ = value;
+    }
+    return this;
+}
+
+CLI11_INLINE Option *Option::multi_option_policy(MultiOptionPolicy value) {
+    if(value != multi_option_policy_) {
+        if(multi_option_policy_ == MultiOptionPolicy::Throw && expected_max_ == detail::expected_max_vector_size &&
+           expected_min_ > 1) {  // this bizarre condition is to maintain backwards compatibility
+                                 // with the previous behavior of expected_ with vectors
+            expected_max_ = expected_min_;
+        }
+        multi_option_policy_ = value;
+        current_option_state_ = option_state::parsing;
+    }
+    return this;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::string
+Option::get_name(bool positional, bool all_options, bool disable_default_flag_values) const {
+    if(get_group().empty())
+        return {};  // Hidden
+
+    if(all_options) {
+
+        std::vector<std::string> name_list;
+
+        /// The all list will never include a positional unless asked or that's the only name.
+        if((positional && (!pname_.empty())) || (snames_.empty() && lnames_.empty())) {
+            name_list.push_back(pname_);
+        }
+        if((get_items_expected() == 0) && (!fnames_.empty())) {
+            for(const std::string &sname : snames_) {
+                name_list.push_back("-" + sname);
+                if(!disable_default_flag_values && check_fname(sname)) {
+                    name_list.back() += "{" + get_flag_value(sname, "") + "}";
+                }
+            }
+
+            for(const std::string &lname : lnames_) {
+                name_list.push_back("--" + lname);
+                if(!disable_default_flag_values && check_fname(lname)) {
+                    name_list.back() += "{" + get_flag_value(lname, "") + "}";
+                }
+            }
+        } else {
+            for(const std::string &sname : snames_)
+                name_list.push_back("-" + sname);
+
+            for(const std::string &lname : lnames_)
+                name_list.push_back("--" + lname);
+        }
+
+        return detail::join(name_list);
+    }
+
+    // This returns the positional name no matter what
+    if(positional)
+        return pname_;
+
+    // Prefer long name
+    if(!lnames_.empty())
+        return std::string(2, '-') + lnames_[0];
+
+    // Or short name if no long name
+    if(!snames_.empty())
+        return std::string(1, '-') + snames_[0];
+
+    // If positional is the only name, it's okay to use that
+    return pname_;
+}
+
+CLI11_INLINE void Option::run_callback() {
+    bool used_default_str = false;
+    if(force_callback_ && results_.empty()) {
+        used_default_str = true;
+        add_result(default_str_);
+    }
+    if(current_option_state_ == option_state::parsing) {
+        _validate_results(results_);
+        current_option_state_ = option_state::validated;
+    }
+
+    if(current_option_state_ < option_state::reduced) {
+        _reduce_results(proc_results_, results_);
+    }
+
+    current_option_state_ = option_state::callback_run;
+    if(callback_) {
+        const results_t &send_results = proc_results_.empty() ? results_ : proc_results_;
+        if(send_results.empty()) {
+            return;
+        }
+        bool local_result = callback_(send_results);
+        if(used_default_str) {
+            // we only clear the results if the callback was actually used
+            // otherwise the callback is the storage of the default
+            results_.clear();
+            proc_results_.clear();
+        }
+        if(!local_result)
+            throw ConversionError(get_name(), results_);
+    }
+}
+
+CLI11_NODISCARD CLI11_INLINE const std::string &Option::matching_name(const Option &other) const {
+    static const std::string estring;
+    bool bothConfigurable = configurable_ && other.configurable_;
+    for(const std::string &sname : snames_) {
+        if(other.check_sname(sname))
+            return sname;
+        if(bothConfigurable && other.check_lname(sname))
+            return sname;
+    }
+    for(const std::string &lname : lnames_) {
+        if(other.check_lname(lname))
+            return lname;
+        if(lname.size() == 1 && bothConfigurable) {
+            if(other.check_sname(lname)) {
+                return lname;
+            }
+        }
+    }
+    if(bothConfigurable && snames_.empty() && lnames_.empty() && !pname_.empty()) {
+        if(other.check_sname(pname_) || other.check_lname(pname_) || pname_ == other.pname_)
+            return pname_;
+    }
+    if(bothConfigurable && other.snames_.empty() && other.fnames_.empty() && !other.pname_.empty()) {
+        if(check_sname(other.pname_) || check_lname(other.pname_) || (pname_ == other.pname_))
+            return other.pname_;
+    }
+    if(ignore_case_ ||
+       ignore_underscore_) {  // We need to do the inverse, in case we are ignore_case or ignore underscore
+        for(const std::string &sname : other.snames_)
+            if(check_sname(sname))
+                return sname;
+        for(const std::string &lname : other.lnames_)
+            if(check_lname(lname))
+                return lname;
+    }
+    return estring;
+}
+
+CLI11_NODISCARD CLI11_INLINE bool Option::check_name(const std::string &name) const {
+
+    if(name.length() > 2 && name[0] == '-' && name[1] == '-')
+        return check_lname(name.substr(2));
+    if(name.length() > 1 && name.front() == '-')
+        return check_sname(name.substr(1));
+    if(!pname_.empty()) {
+        std::string local_pname = pname_;
+        std::string local_name = name;
+        if(ignore_underscore_) {
+            local_pname = detail::remove_underscore(local_pname);
+            local_name = detail::remove_underscore(local_name);
+        }
+        if(ignore_case_) {
+            local_pname = detail::to_lower(local_pname);
+            local_name = detail::to_lower(local_name);
+        }
+        if(local_name == local_pname) {
+            return true;
+        }
+    }
+
+    if(!envname_.empty()) {
+        // this needs to be the original since envname_ shouldn't match on case insensitivity
+        return (name == envname_);
+    }
+    return false;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::string Option::get_flag_value(const std::string &name,
+                                                                std::string input_value) const {
+    static const std::string trueString{"true"};
+    static const std::string falseString{"false"};
+    static const std::string emptyString{"{}"};
+    // check for disable flag override_
+    if(disable_flag_override_) {
+        if(!((input_value.empty()) || (input_value == emptyString))) {
+            auto default_ind = detail::find_member(name, fnames_, ignore_case_, ignore_underscore_);
+            if(default_ind >= 0) {
+                // We can static cast this to std::size_t because it is more than 0 in this block
+                if(default_flag_values_[static_cast<std::size_t>(default_ind)].second != input_value) {
+                    if(input_value == default_str_ && force_callback_) {
+                        return input_value;
+                    }
+                    throw(ArgumentMismatch::FlagOverride(name));
+                }
+            } else {
+                if(input_value != trueString) {
+                    throw(ArgumentMismatch::FlagOverride(name));
+                }
+            }
+        }
+    }
+    auto ind = detail::find_member(name, fnames_, ignore_case_, ignore_underscore_);
+    if((input_value.empty()) || (input_value == emptyString)) {
+        if(flag_like_) {
+            return (ind < 0) ? trueString : default_flag_values_[static_cast<std::size_t>(ind)].second;
+        }
+        return (ind < 0) ? default_str_ : default_flag_values_[static_cast<std::size_t>(ind)].second;
+    }
+    if(ind < 0) {
+        return input_value;
+    }
+    if(default_flag_values_[static_cast<std::size_t>(ind)].second == falseString) {
+        errno = 0;
+        auto val = detail::to_flag_value(input_value);
+        if(errno != 0) {
+            errno = 0;
+            return input_value;
+        }
+        return (val == 1) ? falseString : (val == (-1) ? trueString : std::to_string(-val));
+    }
+    return input_value;
+}
+
+CLI11_INLINE Option *Option::add_result(std::string s) {
+    _add_result(std::move(s), results_);
+    current_option_state_ = option_state::parsing;
+    return this;
+}
+
+CLI11_INLINE Option *Option::add_result(std::string s, int &results_added) {
+    results_added = _add_result(std::move(s), results_);
+    current_option_state_ = option_state::parsing;
+    return this;
+}
+
+CLI11_INLINE Option *Option::add_result(std::vector<std::string> s) {
+    current_option_state_ = option_state::parsing;
+    for(auto &str : s) {
+        _add_result(std::move(str), results_);
+    }
+    return this;
+}
+
+CLI11_NODISCARD CLI11_INLINE results_t Option::reduced_results() const {
+    results_t res = proc_results_.empty() ? results_ : proc_results_;
+    if(current_option_state_ < option_state::reduced) {
+        if(current_option_state_ == option_state::parsing) {
+            res = results_;
+            _validate_results(res);
+        }
+        if(!res.empty()) {
+            results_t extra;
+            _reduce_results(extra, res);
+            if(!extra.empty()) {
+                res = std::move(extra);
+            }
+        }
+    }
+    return res;
+}
+
+CLI11_INLINE Option *Option::type_size(int option_type_size) {
+    if(option_type_size < 0) {
+        // this section is included for backwards compatibility
+        type_size_max_ = -option_type_size;
+        type_size_min_ = -option_type_size;
+        expected_max_ = detail::expected_max_vector_size;
+    } else {
+        type_size_max_ = option_type_size;
+        if(type_size_max_ < detail::expected_max_vector_size) {
+            type_size_min_ = option_type_size;
+        } else {
+            inject_separator_ = true;
+        }
+        if(type_size_max_ == 0)
+            required_ = false;
+    }
+    return this;
+}
+
+CLI11_INLINE Option *Option::type_size(int option_type_size_min, int option_type_size_max) {
+    if(option_type_size_min < 0 || option_type_size_max < 0) {
+        // this section is included for backwards compatibility
+        expected_max_ = detail::expected_max_vector_size;
+        option_type_size_min = (std::abs)(option_type_size_min);
+        option_type_size_max = (std::abs)(option_type_size_max);
+    }
+
+    if(option_type_size_min > option_type_size_max) {
+        type_size_max_ = option_type_size_min;
+        type_size_min_ = option_type_size_max;
+    } else {
+        type_size_min_ = option_type_size_min;
+        type_size_max_ = option_type_size_max;
+    }
+    if(type_size_max_ == 0) {
+        required_ = false;
+    }
+    if(type_size_max_ >= detail::expected_max_vector_size) {
+        inject_separator_ = true;
+    }
+    return this;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::string Option::get_type_name() const {
+    std::string full_type_name = type_name_();
+    if(!validators_.empty()) {
+        for(const auto &validator : validators_) {
+            std::string vtype = validator->get_description();
+            if(!vtype.empty()) {
+                full_type_name += ":" + vtype;
+            }
+        }
+    }
+    return full_type_name;
+}
+
+CLI11_INLINE void Option::_validate_results(results_t &res) const {
+    // Run the Validators (can change the string)
+    if(!validators_.empty()) {
+        if(type_size_max_ > 1) {  // in this context index refers to the index in the type
+            int index = 0;
+            if(get_items_expected_max() < static_cast<int>(res.size()) &&
+               (multi_option_policy_ == CLI::MultiOptionPolicy::TakeLast ||
+                multi_option_policy_ == CLI::MultiOptionPolicy::Reverse)) {
+                // create a negative index for the earliest ones
+                index = get_items_expected_max() - static_cast<int>(res.size());
+            }
+
+            for(std::string &result : res) {
+                if(detail::is_separator(result) && type_size_max_ != type_size_min_ && index >= 0) {
+                    index = 0;  // reset index for variable size chunks
+                    continue;
+                }
+                auto err_msg = _validate(result, (index >= 0) ? (index % type_size_max_) : index);
+                if(!err_msg.empty())
+                    throw ValidationError(get_name(), err_msg);
+                ++index;
+            }
+        } else {
+            int index = 0;
+            if(expected_max_ < static_cast<int>(res.size()) &&
+               (multi_option_policy_ == CLI::MultiOptionPolicy::TakeLast ||
+                multi_option_policy_ == CLI::MultiOptionPolicy::Reverse)) {
+                // create a negative index for the earliest ones
+                index = expected_max_ - static_cast<int>(res.size());
+            }
+            for(std::string &result : res) {
+                auto err_msg = _validate(result, index);
+                ++index;
+                if(!err_msg.empty())
+                    throw ValidationError(get_name(), err_msg);
+            }
+        }
+    }
+}
+
+CLI11_INLINE void Option::_reduce_results(results_t &out, const results_t &original) const {
+
+    // max num items expected or length of vector, always at least 1
+    // Only valid for a trimming policy
+
+    out.clear();
+    // Operation depends on the policy setting
+    switch(multi_option_policy_) {
+    case MultiOptionPolicy::TakeAll:
+        break;
+    case MultiOptionPolicy::TakeLast: {
+        // Allow multi-option sizes (including 0)
+        std::size_t trim_size = std::min<std::size_t>(
+            static_cast<std::size_t>(std::max<int>(get_items_expected_max(), 1)), original.size());
+        if(original.size() != trim_size) {
+            out.assign(original.end() - static_cast<results_t::difference_type>(trim_size), original.end());
+        }
+    } break;
+    case MultiOptionPolicy::Reverse: {
+        // Allow multi-option sizes (including 0)
+        std::size_t trim_size = std::min<std::size_t>(
+            static_cast<std::size_t>(std::max<int>(get_items_expected_max(), 1)), original.size());
+        if(original.size() != trim_size || trim_size > 1) {
+            out.assign(original.end() - static_cast<results_t::difference_type>(trim_size), original.end());
+        }
+        std::reverse(out.begin(), out.end());
+    } break;
+    case MultiOptionPolicy::TakeFirst: {
+        std::size_t trim_size = std::min<std::size_t>(
+            static_cast<std::size_t>(std::max<int>(get_items_expected_max(), 1)), original.size());
+        if(original.size() != trim_size) {
+            out.assign(original.begin(), original.begin() + static_cast<results_t::difference_type>(trim_size));
+        }
+    } break;
+    case MultiOptionPolicy::Join:
+        if(results_.size() > 1) {
+            out.push_back(detail::join(original, std::string(1, (delimiter_ == '\0') ? '\n' : delimiter_)));
+        }
+        break;
+    case MultiOptionPolicy::Sum:
+        out.push_back(detail::sum_string_vector(original));
+        break;
+    case MultiOptionPolicy::Throw:
+    default: {
+        auto num_min = static_cast<std::size_t>(get_items_expected_min());
+        auto num_max = static_cast<std::size_t>(get_items_expected_max());
+        if(num_min == 0) {
+            num_min = 1;
+        }
+        if(num_max == 0) {
+            num_max = 1;
+        }
+        if(original.size() < num_min) {
+            throw ArgumentMismatch::AtLeast(get_name(), static_cast<int>(num_min), original.size());
+        }
+        if(original.size() > num_max) {
+            if(original.size() == 2 && num_max == 1 && original[1] == "%%" && original[0] == "{}") {
+                // this condition is a trap for the following empty indicator check on config files, it may not be used
+                // anymore
+                out = original;  // LCOV_EXCL_LINE
+            } else {
+                throw ArgumentMismatch::AtMost(get_name(), static_cast<int>(num_max), original.size());
+            }
+        }
+        break;
+    }
+    }
+    // this check is to allow an empty vector in certain circumstances but not if expected is not zero.
+    // {} is the indicator for an empty container
+    if(out.empty()) {
+        if(original.size() == 1 && original[0] == "{}" && get_items_expected_min() > 0) {
+            out.emplace_back("{}");
+            out.emplace_back("%%");
+        }
+    } else if(out.size() == 1 && out[0] == "{}" && get_items_expected_min() > 0) {
+        out.emplace_back("%%");
+    }
+}
+
+CLI11_INLINE std::string Option::_validate(std::string &result, int index) const {
+    std::string err_msg;
+    if(result.empty() && expected_min_ == 0) {
+        // an empty with nothing expected is allowed
+        return err_msg;
+    }
+    for(const auto &vali : validators_) {
+        auto v = vali->get_application_index();
+        if(v == -1 || v == index) {
+            try {
+                err_msg = (*vali)(result);
+            } catch(const ValidationError &err) {
+                err_msg = err.what();
+            }
+            if(!err_msg.empty())
+                break;
+        }
+    }
+
+    return err_msg;
+}
+
+CLI11_INLINE int Option::_add_result(std::string &&result, std::vector<std::string> &res) const {
+    int result_count = 0;
+
+    // Handle the vector escape possibility all characters duplicated and starting with [[ ending with ]]
+    // this is always a single result
+    if(result.size() >= 4 && result[0] == '[' && result[1] == '[' && result.back() == ']' &&
+       (*(result.end() - 2) == ']')) {
+        // this is an escape clause for odd strings
+        std::string nstrs{'['};
+        bool duplicated{true};
+        for(std::size_t ii = 2; ii < result.size() - 2; ii += 2) {
+            if(result[ii] == result[ii + 1]) {
+                nstrs.push_back(result[ii]);
+            } else {
+                duplicated = false;
+                break;
+            }
+        }
+        if(duplicated) {
+            nstrs.push_back(']');
+            res.push_back(std::move(nstrs));
+            ++result_count;
+            return result_count;
+        }
+    }
+
+    if((allow_extra_args_ || get_expected_max() > 1 || get_type_size() > 1) && !result.empty() &&
+       result.front() == '[' &&
+       result.back() == ']') {  // this is now a vector string likely from the default or user entry
+
+        result.pop_back();
+        result.erase(result.begin());
+        bool skipSection{false};
+        for(auto &var : CLI::detail::split_up(result, ',')) {
+            if(!var.empty()) {
+                result_count += _add_result(std::move(var), res);
+            }
+        }
+        if(!skipSection) {
+            return result_count;
+        }
+    }
+    if(delimiter_ == '\0') {
+        res.push_back(std::move(result));
+        ++result_count;
+    } else {
+        if((result.find_first_of(delimiter_) != std::string::npos)) {
+            for(const auto &var : CLI::detail::split(result, delimiter_)) {
+                if(!var.empty()) {
+                    res.push_back(var);
+                    ++result_count;
+                }
+            }
+        } else {
+            res.push_back(std::move(result));
+            ++result_count;
+        }
+    }
+    return result_count;
+}
+
+
+
+#ifndef CLI11_PARSE
+#define CLI11_PARSE(app, ...)                                                                                          \
+    try {                                                                                                              \
+        (app).parse(__VA_ARGS__);                                                                                      \
+    } catch(const CLI::ParseError &e) {                                                                                \
+        return (app).exit(e);                                                                                          \
+    }
+#endif
+
+namespace detail {
+enum class Classifier : std::uint8_t {
+    NONE,
+    POSITIONAL_MARK,
+    SHORT,
+    LONG,
+    WINDOWS_STYLE,
+    SUBCOMMAND,
+    SUBCOMMAND_TERMINATOR
+};
+struct AppFriend;
+}  // namespace detail
+
+namespace FailureMessage {
+/// Printout a clean, simple message on error (the default in CLI11 1.5+)
+CLI11_INLINE std::string simple(const App *app, const Error &e);
+
+/// Printout the full help string on error (if this fn is set, the old default for CLI11)
+CLI11_INLINE std::string help(const App *app, const Error &e);
+}  // namespace FailureMessage
+
+/// enumeration of modes of how to deal with command line extras
+enum class ExtrasMode : std::uint8_t {
+    Error = 0,
+    ErrorImmediately,
+    Ignore,
+    AssumeSingleArgument,
+    AssumeMultipleArguments,
+    Capture
+};
+
+/// enumeration of modes of how to deal with extras in config files
+enum class ConfigExtrasMode : std::uint8_t { Error = 0, Ignore, IgnoreAll, Capture };
+
+/// @brief  enumeration of modes of how to deal with extras in config files
+enum class config_extras_mode : std::uint8_t { error = 0, ignore, ignore_all, capture };
+
+/// @brief  enumeration of prefix command modes, separator requires that the first extra argument be a "--", other
+/// unrecognized arguments will cause an error. on allows the first extra to trigger prefix mode regardless of other
+/// recognized options
+enum class PrefixCommandMode : std::uint8_t { Off = 0, SeparatorOnly = 1, On = 2 };
+
+class App;
+
+using App_p = std::shared_ptr<App>;
+
+namespace detail {
+/// helper functions for adding in appropriate flag modifiers for add_flag
+
+template <typename T, enable_if_t<!std::is_integral<T>::value || (sizeof(T) <= 1U), detail::enabler> = detail::dummy>
+Option *default_flag_modifiers(Option *opt) {
+    return opt->always_capture_default();
+}
+
+/// summing modifiers
+template <typename T, enable_if_t<std::is_integral<T>::value && (sizeof(T) > 1U), detail::enabler> = detail::dummy>
+Option *default_flag_modifiers(Option *opt) {
+    return opt->multi_option_policy(MultiOptionPolicy::Sum)->default_str("0")->force_callback();
+}
+
+}  // namespace detail
+
+class Option_group;
+/// Creates a command line program, with very few defaults.
+/** To use, create a new `Program()` instance with `argc`, `argv`, and a help description. The templated
+ *  add_option methods make it easy to prepare options. Remember to call `.start` before starting your
+ * program, so that the options can be evaluated and the help option doesn't accidentally run your program. */
+class App {
+    friend Option;
+    friend detail::AppFriend;
+
+  protected:
+    // This library follows the Google style guide for member names ending in underscores
+
+    /// @name Basics
+    ///@{
+
+    /// Subcommand name or program name (from parser if name is empty)
+    std::string name_{};
+
+    /// Description of the current program/subcommand
+    std::string description_{};
+
+    /// If true, allow extra arguments (ie, don't throw an error). INHERITABLE
+    ExtrasMode allow_extras_{ExtrasMode::Error};
+
+    /// If ignore, allow extra arguments in the ini file (ie, don't throw an error). INHERITABLE
+    /// if error, error on an extra argument, and if capture feed it to the app
+    ConfigExtrasMode allow_config_extras_{ConfigExtrasMode::Ignore};
+
+    ///  If true, cease processing on an unrecognized option (implies allow_extras) INHERITABLE
+    PrefixCommandMode prefix_command_{PrefixCommandMode::Off};
+
+    /// If set to true the name was automatically generated from the command line vs a user set name
+    bool has_automatic_name_{false};
+
+    /// If set to true the subcommand is required to be processed and used, ignored for main app
+    bool required_{false};
+
+    /// If set to true the subcommand is disabled and cannot be used, ignored for main app
+    bool disabled_{false};
+
+    /// Flag indicating that the pre_parse_callback has been triggered
+    bool pre_parse_called_{false};
+
+    /// Flag indicating that the callback for the subcommand should be executed immediately on parse completion which is
+    /// before help or ini files are processed. INHERITABLE
+    bool immediate_callback_{false};
+
+    /// This is a function that runs prior to the start of parsing
+    std::function<void(std::size_t)> pre_parse_callback_{};
+
+    /// This is a function that runs when parsing has finished.
+    std::function<void()> parse_complete_callback_{};
+
+    /// This is a function that runs when all processing has completed
+    std::function<void()> final_callback_{};
+
+    ///@}
+    /// @name Options
+    ///@{
+
+    /// The default values for options, customizable and changeable INHERITABLE
+    OptionDefaults option_defaults_{};
+
+    /// The list of options, stored locally
+    std::vector<Option_p> options_{};
+
+    ///@}
+    /// @name Help
+    ///@{
+
+    /// Usage to put after program/subcommand description in the help output INHERITABLE
+    std::string usage_{};
+
+    /// This is a function that generates a usage to put after program/subcommand description in help output
+    std::function<std::string()> usage_callback_{};
+
+    /// Footer to put after all options in the help output INHERITABLE
+    std::string footer_{};
+
+    /// This is a function that generates a footer to put after all other options in help output
+    std::function<std::string()> footer_callback_{};
+
+    /// A pointer to the help flag if there is one INHERITABLE
+    Option *help_ptr_{nullptr};
+
+    /// A pointer to the help all flag if there is one INHERITABLE
+    Option *help_all_ptr_{nullptr};
+
+    /// A pointer to a version flag if there is one
+    Option *version_ptr_{nullptr};
+
+    /// This is the formatter for help printing. Default provided. INHERITABLE (same pointer)
+    std::shared_ptr<FormatterBase> formatter_{new Formatter()};
+
+    /// The error message printing function INHERITABLE
+    std::function<std::string(const App *, const Error &e)> failure_message_{FailureMessage::simple};
+
+    ///@}
+    /// @name Parsing
+    ///@{
+
+    using missing_t = std::vector<std::pair<detail::Classifier, std::string>>;
+
+    /// Pair of classifier, string for missing options. (extra detail is removed on returning from parse)
+    ///
+    /// This is faster and cleaner than storing just a list of strings and reparsing. This may contain the -- separator.
+    missing_t missing_{};
+
+    /// This is a list of pointers to options with the original parse order
+    std::vector<Option *> parse_order_{};
+
+    /// This is a list of the subcommands collected, in order
+    std::vector<App *> parsed_subcommands_{};
+
+    /// this is a list of subcommands that are exclusionary to this one
+    std::set<App *> exclude_subcommands_{};
+
+    /// This is a list of options which are exclusionary to this App, if the options were used this subcommand should
+    /// not be
+    std::set<Option *> exclude_options_{};
+
+    /// this is a list of subcommands or option groups that are required by this one, the list is not mutual,  the
+    /// listed subcommands do not require this one
+    std::set<App *> need_subcommands_{};
+
+    /// This is a list of options which are required by this app, the list is not mutual, listed options do not need the
+    /// subcommand not be
+    std::set<Option *> need_options_{};
+
+    ///@}
+    /// @name Subcommands
+    ///@{
+
+    /// Storage for subcommand list
+    std::vector<App_p> subcommands_{};
+
+    /// If true, the program name is not case-sensitive INHERITABLE
+    bool ignore_case_{false};
+
+    /// If true, the program should ignore underscores INHERITABLE
+    bool ignore_underscore_{false};
+
+    /// Allow options or other arguments to fallthrough, so that parent commands can collect options after subcommand.
+    /// INHERITABLE
+    bool fallthrough_{false};
+
+    /// Allow subcommands to fallthrough, so that parent commands can trigger other subcommands after subcommand.
+    bool subcommand_fallthrough_{true};
+
+    /// Allow '/' for options for Windows like options. Defaults to true on Windows, false otherwise. INHERITABLE
+    bool allow_windows_style_options_{
+#ifdef _WIN32
+        true
+#else
+        false
+#endif
+    };
+    /// specify that positional arguments come at the end of the argument sequence not inheritable
+    bool positionals_at_end_{false};
+
+    enum class startup_mode : std::uint8_t { stable, enabled, disabled };
+    /// specify the startup mode for the app
+    /// stable=no change, enabled= startup enabled, disabled=startup disabled
+    startup_mode default_startup{startup_mode::stable};
+
+    /// if set to true the subcommand can be triggered via configuration files INHERITABLE
+    bool configurable_{false};
+
+    /// If set to true positional options are validated before assigning INHERITABLE
+    bool validate_positionals_{false};
+
+    /// If set to true optional vector arguments are validated before assigning INHERITABLE
+    bool validate_optional_arguments_{false};
+
+    /// indicator that the subcommand is silent and won't show up in subcommands list
+    /// This is potentially useful as a modifier subcommand
+    bool silent_{false};
+
+    /// indicator that the subcommand should allow non-standard option arguments, such as -single_dash_flag
+    bool allow_non_standard_options_{false};
+
+    /// indicator to allow subcommands to match with prefix matching
+    bool allow_prefix_matching_{false};
+
+    /// Counts the number of times this command/subcommand was parsed
+    std::uint32_t parsed_{0U};
+
+    /// Minimum required subcommands (not inheritable!)
+    std::size_t require_subcommand_min_{0};
+
+    /// Max number of subcommands allowed (parsing stops after this number). 0 is unlimited INHERITABLE
+    std::size_t require_subcommand_max_{0};
+
+    /// Minimum required options (not inheritable!)
+    std::size_t require_option_min_{0};
+
+    /// Max number of options allowed. 0 is unlimited (not inheritable)
+    std::size_t require_option_max_{0};
+
+    /// A pointer to the parent if this is a subcommand
+    App *parent_{nullptr};
+
+    /// The group membership INHERITABLE
+    std::string group_{"SUBCOMMANDS"};
+
+    /// Alias names for the subcommand
+    std::vector<std::string> aliases_{};
+
+    ///@}
+    /// @name Config
+    ///@{
+
+    /// Pointer to the config option
+    Option *config_ptr_{nullptr};
+
+    /// This is the formatter for help printing. Default provided. INHERITABLE (same pointer)
+    std::shared_ptr<Config> config_formatter_{new ConfigTOML()};
+
+    ///@}
+
+#ifdef _WIN32
+    /// When normalizing argv to UTF-8 on Windows, this is the storage for normalized args.
+    std::vector<std::string> normalized_argv_{};
+
+    /// When normalizing argv to UTF-8 on Windows, this is the `char**` value returned to the user.
+    std::vector<char *> normalized_argv_view_{};
+#endif
+
+    /// Special private constructor for subcommand
+    App(std::string app_description, std::string app_name, App *parent);
+
+  public:
+    /// @name Basic
+    ///@{
+
+    /// Create a new program. Pass in the same arguments as main(), along with a help string.
+    explicit App(std::string app_description = "", std::string app_name = "")
+        : App(app_description, app_name, nullptr) {
+        set_help_flag("-h,--help", "Print this help message and exit");
+    }
+
+    App(const App &) = delete;
+    App &operator=(const App &) = delete;
+
+    /// virtual destructor
+    virtual ~App() = default;
+
+    /// Convert the contents of argv to UTF-8. Only does something on Windows, does nothing elsewhere.
+    CLI11_NODISCARD char **ensure_utf8(char **argv);
+
+    /// Set a callback for execution when all parsing and processing has completed
+    ///
+    /// Due to a bug in c++11,
+    /// it is not possible to overload on std::function (fixed in c++14
+    /// and backported to c++11 on newer compilers). Use capture by reference
+    /// to get a pointer to App if needed.
+    App *callback(std::function<void()> app_callback) {
+        if(immediate_callback_) {
+            parse_complete_callback_ = std::move(app_callback);
+        } else {
+            final_callback_ = std::move(app_callback);
+        }
+        return this;
+    }
+
+    /// Set a callback for execution when all parsing and processing has completed
+    /// aliased as callback
+    App *final_callback(std::function<void()> app_callback) {
+        final_callback_ = std::move(app_callback);
+        return this;
+    }
+
+    /// Set a callback to execute when parsing has completed for the app
+    ///
+    App *parse_complete_callback(std::function<void()> pc_callback) {
+        parse_complete_callback_ = std::move(pc_callback);
+        return this;
+    }
+
+    /// Set a callback to execute prior to parsing.
+    ///
+    App *preparse_callback(std::function<void(std::size_t)> pp_callback) {
+        pre_parse_callback_ = std::move(pp_callback);
+        return this;
+    }
+
+    /// Set a name for the app (empty will use parser to set the name)
+    App *name(std::string app_name = "");
+
+    /// Set an alias for the app
+    App *alias(std::string app_name);
+
+    /// Remove the error when extras are left over on the command line.
+    App *allow_extras(bool allow = true) {
+        allow_extras_ = allow ? ExtrasMode::Capture : ExtrasMode::Error;
+        return this;
+    }
+
+    /// Remove the error when extras are left over on the command line.
+    App *allow_extras(ExtrasMode allow) {
+        allow_extras_ = allow;
+        return this;
+    }
+
+    /// Remove the error when extras are left over on the command line.
+    App *required(bool require = true) {
+        required_ = require;
+        return this;
+    }
+
+    /// Disable the subcommand or option group
+    App *disabled(bool disable = true) {
+        disabled_ = disable;
+        return this;
+    }
+
+    /// silence the subcommand from showing up in the processed list
+    App *silent(bool silence = true) {
+        silent_ = silence;
+        return this;
+    }
+
+    /// allow non standard option names
+    App *allow_non_standard_option_names(bool allowed = true) {
+        allow_non_standard_options_ = allowed;
+        return this;
+    }
+
+    /// allow prefix matching for subcommands
+    App *allow_subcommand_prefix_matching(bool allowed = true) {
+        allow_prefix_matching_ = allowed;
+        return this;
+    }
+    /// Set the subcommand to be disabled by default, so on clear(), at the start of each parse it is disabled
+    App *disabled_by_default(bool disable = true) {
+        if(disable) {
+            default_startup = startup_mode::disabled;
+        } else {
+            default_startup = (default_startup == startup_mode::enabled) ? startup_mode::enabled : startup_mode::stable;
+        }
+        return this;
+    }
+
+    /// Set the subcommand to be enabled by default, so on clear(), at the start of each parse it is enabled (not
+    /// disabled)
+    App *enabled_by_default(bool enable = true) {
+        if(enable) {
+            default_startup = startup_mode::enabled;
+        } else {
+            default_startup =
+                (default_startup == startup_mode::disabled) ? startup_mode::disabled : startup_mode::stable;
+        }
+        return this;
+    }
+
+    /// Set the subcommand callback to be executed immediately on subcommand completion
+    App *immediate_callback(bool immediate = true);
+
+    /// Set the subcommand to validate positional arguments before assigning
+    App *validate_positionals(bool validate = true) {
+        validate_positionals_ = validate;
+        return this;
+    }
+
+    /// Set the subcommand to validate optional vector arguments before assigning
+    App *validate_optional_arguments(bool validate = true) {
+        validate_optional_arguments_ = validate;
+        return this;
+    }
+
+    /// ignore extras in config files
+    App *allow_config_extras(bool allow = true) {
+        if(allow) {
+            allow_config_extras_ = ConfigExtrasMode::Capture;
+            allow_extras_ = ExtrasMode::Capture;
+        } else {
+            allow_config_extras_ = ConfigExtrasMode::Error;
+        }
+        return this;
+    }
+
+    /// ignore extras in config files
+    App *allow_config_extras(config_extras_mode mode) {
+        allow_config_extras_ = static_cast<ConfigExtrasMode>(mode);
+        return this;
+    }
+
+    /// ignore extras in config files
+    App *allow_config_extras(ConfigExtrasMode mode) {
+        allow_config_extras_ = mode;
+        return this;
+    }
+
+    /// Do not parse anything after the first unrecognized option (if true) all remaining arguments are stored in
+    /// remaining args
+    App *prefix_command(bool is_prefix = true) {
+        prefix_command_ = is_prefix ? PrefixCommandMode::On : PrefixCommandMode::Off;
+        return this;
+    }
+
+    /// Do not parse anything after the first unrecognized option (if true) all remaining arguments are stored in
+    /// remaining args
+    App *prefix_command(PrefixCommandMode mode) {
+        prefix_command_ = mode;
+        return this;
+    }
+
+    /// Ignore case. Subcommands inherit value.
+    App *ignore_case(bool value = true);
+
+    /// Allow windows style options, such as `/opt`. First matching short or long name used. Subcommands inherit
+    /// value.
+    App *allow_windows_style_options(bool value = true) {
+        allow_windows_style_options_ = value;
+        return this;
+    }
+
+    /// Specify that the positional arguments are only at the end of the sequence
+    App *positionals_at_end(bool value = true) {
+        positionals_at_end_ = value;
+        return this;
+    }
+
+    /// Specify that the subcommand can be triggered by a config file
+    App *configurable(bool value = true) {
+        configurable_ = value;
+        return this;
+    }
+
+    /// Ignore underscore. Subcommands inherit value.
+    App *ignore_underscore(bool value = true);
+
+    /// Set the help formatter
+    App *formatter(std::shared_ptr<FormatterBase> fmt) {
+        formatter_ = fmt;
+        return this;
+    }
+
+    /// Set the help formatter
+    App *formatter_fn(std::function<std::string(const App *, std::string, AppFormatMode)> fmt) {
+        formatter_ = std::make_shared<FormatterLambda>(fmt);
+        return this;
+    }
+
+    /// Set the config formatter
+    App *config_formatter(std::shared_ptr<Config> fmt) {
+        config_formatter_ = fmt;
+        return this;
+    }
+
+    /// Check to see if this subcommand was parsed, true only if received on command line.
+    CLI11_NODISCARD bool parsed() const { return parsed_ > 0; }
+
+    /// Get the OptionDefault object, to set option defaults
+    OptionDefaults *option_defaults() { return &option_defaults_; }
+
+    ///@}
+    /// @name Adding options
+    ///@{
+
+    /// Add an option, will automatically understand the type for common types.
+    ///
+    /// To use, create a variable with the expected type, and pass it in after the name.
+    /// After start is called, you can use count to see if the value was passed, and
+    /// the value will be initialized properly. Numbers, vectors, and strings are supported.
+    ///
+    /// ->required(), ->default, and the validators are options,
+    /// The positional options take an optional number of arguments.
+    ///
+    /// For example,
+    ///
+    ///     std::string filename;
+    ///     program.add_option("filename", filename, "description of filename");
+    ///
+    Option *add_option(std::string option_name,
+                       callback_t option_callback,
+                       std::string option_description = "",
+                       bool defaulted = false,
+                       std::function<std::string()> func = {});
+
+    /// Add option for assigning to a variable
+    template <typename AssignTo,
+              typename ConvertTo = AssignTo,
+              enable_if_t<!std::is_const<ConvertTo>::value, detail::enabler> = detail::dummy>
+    Option *add_option(std::string option_name,
+                       AssignTo &variable,  ///< The variable to set
+                       std::string option_description = "") {
+
+        auto fun = [&variable](const CLI::results_t &res) {  // comment for spacing
+            return detail::lexical_conversion<AssignTo, ConvertTo>(res, variable);
+        };
+
+        Option *opt = add_option(option_name, fun, option_description, false, [&variable]() {
+            return CLI::detail::checked_to_string<AssignTo, ConvertTo>(variable);
+        });
+        opt->type_name(detail::type_name<ConvertTo>());
+        // these must be actual lvalues since (std::max) sometimes is defined in terms of references and references
+        // to structs used in the evaluation can be temporary so that would cause issues.
+        auto Tcount = detail::type_count<AssignTo>::value;
+        auto XCcount = detail::type_count<ConvertTo>::value;
+        opt->type_size(detail::type_count_min<ConvertTo>::value, (std::max)(Tcount, XCcount));
+        opt->expected(detail::expected_count<ConvertTo>::value);
+        opt->run_callback_for_default();
+        return opt;
+    }
+
+    /// Add option for assigning to a variable
+    template <typename AssignTo, enable_if_t<!std::is_const<AssignTo>::value, detail::enabler> = detail::dummy>
+    Option *add_option_no_stream(std::string option_name,
+                                 AssignTo &variable,  ///< The variable to set
+                                 std::string option_description = "") {
+
+        auto fun = [&variable](const CLI::results_t &res) {  // comment for spacing
+            return detail::lexical_conversion<AssignTo, AssignTo>(res, variable);
+        };
+
+        Option *opt = add_option(option_name, fun, option_description, false, []() { return std::string{}; });
+        opt->type_name(detail::type_name<AssignTo>());
+        opt->type_size(detail::type_count_min<AssignTo>::value, detail::type_count<AssignTo>::value);
+        opt->expected(detail::expected_count<AssignTo>::value);
+        opt->run_callback_for_default();
+        return opt;
+    }
+
+    /// Add option for a callback of a specific type
+    template <typename ArgType>
+    Option *add_option_function(std::string option_name,
+                                const std::function<void(const ArgType &)> &func,  ///< the callback to execute
+                                std::string option_description = "") {
+
+        auto fun = [func](const CLI::results_t &res) {
+            ArgType variable;
+            bool result = detail::lexical_conversion<ArgType, ArgType>(res, variable);
+            if(result) {
+                func(variable);
+            }
+            return result;
+        };
+
+        Option *opt = add_option(option_name, std::move(fun), option_description, false);
+        opt->type_name(detail::type_name<ArgType>());
+        opt->type_size(detail::type_count_min<ArgType>::value, detail::type_count<ArgType>::value);
+        opt->expected(detail::expected_count<ArgType>::value);
+        return opt;
+    }
+
+    /// Add option with no description or variable assignment
+    Option *add_option(std::string option_name) {
+        return add_option(option_name, CLI::callback_t{}, std::string{}, false);
+    }
+
+    /// Add option with description but with no variable assignment or callback
+    template <typename T,
+              enable_if_t<std::is_const<T>::value && std::is_constructible<std::string, T>::value, detail::enabler> =
+                  detail::dummy>
+    Option *add_option(std::string option_name, T &option_description) {
+        return add_option(option_name, CLI::callback_t(), option_description, false);
+    }
+
+    /// Set a help flag, replace the existing one if present
+    Option *set_help_flag(std::string flag_name = "", const std::string &help_description = "");
+
+    /// Set a help all flag, replaced the existing one if present
+    Option *set_help_all_flag(std::string help_name = "", const std::string &help_description = "");
+
+    /// Set a version flag and version display string, replace the existing one if present
+    Option *set_version_flag(std::string flag_name = "",
+                             const std::string &versionString = "",
+                             const std::string &version_help = "Display program version information and exit");
+
+    /// Generate the version string through a callback function
+    Option *set_version_flag(std::string flag_name,
+                             std::function<std::string()> vfunc,
+                             const std::string &version_help = "Display program version information and exit");
+
+  private:
+    /// Internal function for adding a flag
+    Option *_add_flag_internal(std::string flag_name, CLI::callback_t fun, std::string flag_description);
+
+  public:
+    /// Add a flag with no description or variable assignment
+    Option *add_flag(std::string flag_name) { return _add_flag_internal(flag_name, CLI::callback_t(), std::string{}); }
+
+    /// Add flag with description but with no variable assignment or callback
+    /// takes a constant string or a rvalue reference to a string,  if a variable string is passed that variable will be
+    /// assigned the results from the flag
+    template <typename T,
+              enable_if_t<(std::is_const<typename std::remove_reference<T>::type>::value ||
+                           std::is_rvalue_reference<T &&>::value) &&
+                              std::is_constructible<std::string, typename std::remove_reference<T>::type>::value,
+                          detail::enabler> = detail::dummy>
+    Option *add_flag(std::string flag_name, T &&flag_description) {
+        return _add_flag_internal(flag_name, CLI::callback_t(), std::forward<T>(flag_description));
+    }
+
+    /// Other type version accepts all other types that are not vectors such as bool, enum, string or other classes
+    /// that can be converted from a string
+    template <typename T,
+              enable_if_t<!detail::is_mutable_container<T>::value && !std::is_const<T>::value &&
+                              !std::is_constructible<std::function<void(int)>, T>::value,
+                          detail::enabler> = detail::dummy>
+    Option *add_flag(std::string flag_name,
+                     T &flag_result,  ///< A variable holding the flag result
+                     std::string flag_description = "") {
+
+        CLI::callback_t fun = [&flag_result](const CLI::results_t &res) {
+            using CLI::detail::lexical_cast;
+            return lexical_cast(res[0], flag_result);
+        };
+        auto *opt = _add_flag_internal(flag_name, std::move(fun), std::move(flag_description));
+        return detail::default_flag_modifiers<T>(opt);
+    }
+
+    /// Vector version to capture multiple flags.
+    template <typename T,
+              enable_if_t<!std::is_assignable<std::function<void(std::int64_t)> &, T>::value, detail::enabler> =
+                  detail::dummy>
+    Option *add_flag(std::string flag_name,
+                     std::vector<T> &flag_results,  ///< A vector of values with the flag results
+                     std::string flag_description = "") {
+        CLI::callback_t fun = [&flag_results](const CLI::results_t &res) {
+            bool retval = true;
+            for(const auto &elem : res) {
+                using CLI::detail::lexical_cast;
+                flag_results.emplace_back();
+                retval &= lexical_cast(elem, flag_results.back());
+            }
+            return retval;
+        };
+        return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description))
+            ->multi_option_policy(MultiOptionPolicy::TakeAll)
+            ->run_callback_for_default();
+    }
+
+    /// Add option for callback that is triggered with a true flag and takes no arguments
+    Option *add_flag_callback(std::string flag_name,
+                              std::function<void(void)> function,  ///< A function to call, void(void)
+                              std::string flag_description = "");
+
+    /// Add option for callback with an integer value
+    Option *add_flag_function(std::string flag_name,
+                              std::function<void(std::int64_t)> function,  ///< A function to call, void(int)
+                              std::string flag_description = "");
+
+#ifdef CLI11_CPP14
+    /// Add option for callback (C++14 or better only)
+    Option *add_flag(std::string flag_name,
+                     std::function<void(std::int64_t)> function,  ///< A function to call, void(std::int64_t)
+                     std::string flag_description = "") {
+        return add_flag_function(std::move(flag_name), std::move(function), std::move(flag_description));
+    }
+#endif
+
+    /// Set a configuration ini file option, or clear it if no name passed
+    Option *set_config(std::string option_name = "",
+                       std::string default_filename = "",
+                       const std::string &help_message = "Read an ini file",
+                       bool config_required = false);
+
+    /// Removes an option from the App. Takes an option pointer. Returns true if found and removed.
+    bool remove_option(Option *opt);
+
+    /// creates an option group as part of the given app
+    template <typename T = Option_group>
+    T *add_option_group(std::string group_name, std::string group_description = "") {
+        if(!detail::valid_alias_name_string(group_name)) {
+            throw IncorrectConstruction("option group names may not contain newlines or null characters");
+        }
+        auto option_group = std::make_shared<T>(std::move(group_description), group_name, this);
+        auto *ptr = option_group.get();
+        // move to App_p for overload resolution on older gcc versions
+        App_p app_ptr = std::static_pointer_cast<App>(option_group);
+        // don't inherit the footer in option groups and clear the help flag by default
+        app_ptr->footer_ = "";
+        app_ptr->set_help_flag();
+        add_subcommand(std::move(app_ptr));
+        return ptr;
+    }
+
+    ///@}
+    /// @name Subcommands
+    ///@{
+
+    /// Add a subcommand. Inherits INHERITABLE and OptionDefaults, and help flag
+    App *add_subcommand(std::string subcommand_name = "", std::string subcommand_description = "");
+
+    /// Add a previously created app as a subcommand
+    App *add_subcommand(CLI::App_p subcom);
+
+    /// Removes a subcommand from the App. Takes a subcommand pointer. Returns true if found and removed.
+    bool remove_subcommand(App *subcom);
+
+    /// Check to see if a subcommand is part of this command (doesn't have to be in command line)
+    /// returns the first subcommand if passed a nullptr
+    App *get_subcommand(const App *subcom) const;
+
+    /// Check to see if a subcommand is part of this command (text version)
+    CLI11_NODISCARD App *get_subcommand(std::string subcom) const;
+
+    /// Get a subcommand by name (noexcept non-const version)
+    /// returns null if subcommand doesn't exist
+    CLI11_NODISCARD App *get_subcommand_no_throw(std::string subcom) const noexcept;
+
+    /// Get a pointer to subcommand by index
+    CLI11_NODISCARD App *get_subcommand(int index = 0) const;
+
+    /// Check to see if a subcommand is part of this command and get a shared_ptr to it
+    CLI::App_p get_subcommand_ptr(App *subcom) const;
+
+    /// Check to see if a subcommand is part of this command (text version)
+    CLI11_NODISCARD CLI::App_p get_subcommand_ptr(std::string subcom) const;
+
+    /// Get an owning pointer to subcommand by index
+    CLI11_NODISCARD CLI::App_p get_subcommand_ptr(int index = 0) const;
+
+    /// Check to see if an option group is part of this App
+    CLI11_NODISCARD App *get_option_group(std::string group_name) const;
+
+    /// No argument version of count counts the number of times this subcommand was
+    /// passed in. The main app will return 1. Unnamed subcommands will also return 1 unless
+    /// otherwise modified in a callback
+    CLI11_NODISCARD std::size_t count() const { return parsed_; }
+
+    /// Get a count of all the arguments processed in options and subcommands, this excludes arguments which were
+    /// treated as extras.
+    CLI11_NODISCARD std::size_t count_all() const;
+
+    /// Changes the group membership
+    App *group(std::string group_name) {
+        group_ = group_name;
+        return this;
+    }
+
+    /// The argumentless form of require subcommand requires 1 or more subcommands
+    App *require_subcommand() {
+        require_subcommand_min_ = 1;
+        require_subcommand_max_ = 0;
+        return this;
+    }
+
+    /// Require a subcommand to be given (does not affect help call)
+    /// The number required can be given. Negative values indicate maximum
+    /// number allowed (0 for any number). Max number inheritable.
+    App *require_subcommand(int value) {
+        if(value < 0) {
+            require_subcommand_min_ = 0;
+            require_subcommand_max_ = static_cast<std::size_t>(-value);
+        } else {
+            require_subcommand_min_ = static_cast<std::size_t>(value);
+            require_subcommand_max_ = static_cast<std::size_t>(value);
+        }
+        return this;
+    }
+
+    /// Explicitly control the number of subcommands required. Setting 0
+    /// for the max means unlimited number allowed. Max number inheritable.
+    App *require_subcommand(std::size_t min, std::size_t max) {
+        require_subcommand_min_ = min;
+        require_subcommand_max_ = max;
+        return this;
+    }
+
+    /// The argumentless form of require option requires 1 or more options be used
+    App *require_option() {
+        require_option_min_ = 1;
+        require_option_max_ = 0;
+        return this;
+    }
+
+    /// Require an option to be given (does not affect help call)
+    /// The number required can be given. Negative values indicate maximum
+    /// number allowed (0 for any number).
+    App *require_option(int value) {
+        if(value < 0) {
+            require_option_min_ = 0;
+            require_option_max_ = static_cast<std::size_t>(-value);
+        } else {
+            require_option_min_ = static_cast<std::size_t>(value);
+            require_option_max_ = static_cast<std::size_t>(value);
+        }
+        return this;
+    }
+
+    /// Explicitly control the number of options required. Setting 0
+    /// for the max means unlimited number allowed. Max number inheritable.
+    App *require_option(std::size_t min, std::size_t max) {
+        require_option_min_ = min;
+        require_option_max_ = max;
+        return this;
+    }
+
+    /// Set fallthrough, set to true so that options will fallthrough to parent if not recognized in a subcommand
+    /// Default from parent, usually set on parent.
+    App *fallthrough(bool value = true) {
+        fallthrough_ = value;
+        return this;
+    }
+
+    /// Set subcommand fallthrough, set to true so that subcommands on parents are recognized
+    App *subcommand_fallthrough(bool value = true) {
+        subcommand_fallthrough_ = value;
+        return this;
+    }
+
+    /// Check to see if this subcommand was parsed, true only if received on command line.
+    /// This allows the subcommand to be directly checked.
+    explicit operator bool() const { return parsed_ > 0; }
+
+    ///@}
+    /// @name Extras for subclassing
+    ///@{
+
+    /// This allows subclasses to inject code before callbacks but after parse.
+    ///
+    /// This does not run if any errors or help is thrown.
+    virtual void pre_callback() {}
+
+    ///@}
+    /// @name Parsing
+    ///@{
+    //
+    /// Reset the parsed data
+    void clear();
+
+    /// Parses the command line - throws errors.
+    /// This must be called after the options are in but before the rest of the program.
+    void parse(int argc, const char *const *argv);
+    void parse(int argc, const wchar_t *const *argv);
+
+  private:
+    template <class CharT> void parse_char_t(int argc, const CharT *const *argv);
+
+  public:
+    /// Parse a single string as if it contained command line arguments.
+    /// This function splits the string into arguments then calls parse(std::vector<std::string> &)
+    /// the function takes an optional boolean argument specifying if the programName is included in the string to
+    /// process
+    void parse(std::string commandline, bool program_name_included = false);
+    void parse(std::wstring commandline, bool program_name_included = false);
+
+    /// The real work is done here. Expects a reversed vector.
+    /// Changes the vector to the remaining options.
+    void parse(std::vector<std::string> &args);
+
+    /// The real work is done here. Expects a reversed vector.
+    void parse(std::vector<std::string> &&args);
+
+    void parse_from_stream(std::istream &input);
+
+    /// Provide a function to print a help message. The function gets access to the App pointer and error.
+    void failure_message(std::function<std::string(const App *, const Error &e)> function) {
+        failure_message_ = function;
+    }
+
+    /// Print a nice error message and return the exit code
+    int exit(const Error &e, std::ostream &out = std::cout, std::ostream &err = std::cerr) const;
+
+    ///@}
+    /// @name Post parsing
+    ///@{
+
+    /// Counts the number of times the given option was passed.
+    CLI11_NODISCARD std::size_t count(std::string option_name) const { return get_option(option_name)->count(); }
+
+    /// Get a subcommand pointer list to the currently selected subcommands (after parsing by default, in command
+    /// line order; use parsed = false to get the original definition list.)
+    CLI11_NODISCARD std::vector<App *> get_subcommands() const { return parsed_subcommands_; }
+
+    /// Get a filtered subcommand pointer list from the original definition list. An empty function will provide all
+    /// subcommands (const)
+    std::vector<const App *> get_subcommands(const std::function<bool(const App *)> &filter) const;
+
+    /// Get a filtered subcommand pointer list from the original definition list. An empty function will provide all
+    /// subcommands
+    std::vector<App *> get_subcommands(const std::function<bool(App *)> &filter);
+
+    /// Check to see if given subcommand was selected
+    bool got_subcommand(const App *subcom) const {
+        // get subcom needed to verify that this was a real subcommand
+        return get_subcommand(subcom)->parsed_ > 0;
+    }
+
+    /// Check with name instead of pointer to see if subcommand was selected
+    CLI11_NODISCARD bool got_subcommand(std::string subcommand_name) const noexcept {
+        App *sub = get_subcommand_no_throw(subcommand_name);
+        return (sub != nullptr) ? (sub->parsed_ > 0) : false;
+    }
+
+    /// Sets excluded options for the subcommand
+    App *excludes(Option *opt) {
+        if(opt == nullptr) {
+            throw OptionNotFound("nullptr passed");
+        }
+        exclude_options_.insert(opt);
+        return this;
+    }
+
+    /// Sets excluded subcommands for the subcommand
+    App *excludes(App *app) {
+        if(app == nullptr) {
+            throw OptionNotFound("nullptr passed");
+        }
+        if(app == this) {
+            throw OptionNotFound("cannot self reference in needs");
+        }
+        auto res = exclude_subcommands_.insert(app);
+        // subcommand exclusion should be symmetric
+        if(res.second) {
+            app->exclude_subcommands_.insert(this);
+        }
+        return this;
+    }
+
+    App *needs(Option *opt) {
+        if(opt == nullptr) {
+            throw OptionNotFound("nullptr passed");
+        }
+        need_options_.insert(opt);
+        return this;
+    }
+
+    App *needs(App *app) {
+        if(app == nullptr) {
+            throw OptionNotFound("nullptr passed");
+        }
+        if(app == this) {
+            throw OptionNotFound("cannot self reference in needs");
+        }
+        need_subcommands_.insert(app);
+        return this;
+    }
+
+    /// Removes an option from the excludes list of this subcommand
+    bool remove_excludes(Option *opt);
+
+    /// Removes a subcommand from the excludes list of this subcommand
+    bool remove_excludes(App *app);
+
+    /// Removes an option from the needs list of this subcommand
+    bool remove_needs(Option *opt);
+
+    /// Removes a subcommand from the needs list of this subcommand
+    bool remove_needs(App *app);
+    ///@}
+    /// @name Help
+    ///@{
+
+    /// Set usage.
+    App *usage(std::string usage_string) {
+        usage_ = std::move(usage_string);
+        return this;
+    }
+    /// Set usage.
+    App *usage(std::function<std::string()> usage_function) {
+        usage_callback_ = std::move(usage_function);
+        return this;
+    }
+    /// Set footer.
+    App *footer(std::string footer_string) {
+        footer_ = std::move(footer_string);
+        return this;
+    }
+    /// Set footer.
+    App *footer(std::function<std::string()> footer_function) {
+        footer_callback_ = std::move(footer_function);
+        return this;
+    }
+    /// Produce a string that could be read in as a config of the current values of the App. Set default_also to
+    /// include default arguments. write_descriptions will print a description for the App and for each option.
+    CLI11_NODISCARD std::string config_to_str(bool default_also = false, bool write_description = false) const {
+        return config_formatter_->to_config(this, default_also, write_description, "");
+    }
+
+    /// Makes a help message, using the currently configured formatter
+    /// Will only do one subcommand at a time
+    CLI11_NODISCARD std::string help(std::string prev = "", AppFormatMode mode = AppFormatMode::Normal) const;
+
+    /// Displays a version string
+    CLI11_NODISCARD std::string version() const;
+    ///@}
+    /// @name Getters
+    ///@{
+
+    /// Access the formatter
+    CLI11_NODISCARD std::shared_ptr<FormatterBase> get_formatter() const { return formatter_; }
+
+    /// Access the config formatter
+    CLI11_NODISCARD std::shared_ptr<Config> get_config_formatter() const { return config_formatter_; }
+
+    /// Access the config formatter as a configBase pointer
+    CLI11_NODISCARD std::shared_ptr<ConfigBase> get_config_formatter_base() const {
+        // This is safer as a dynamic_cast if we have RTTI, as Config -> ConfigBase
+#if CLI11_USE_STATIC_RTTI == 0
+        return std::dynamic_pointer_cast<ConfigBase>(config_formatter_);
+#else
+        return std::static_pointer_cast<ConfigBase>(config_formatter_);
+#endif
+    }
+
+    /// Get the app or subcommand description
+    CLI11_NODISCARD std::string get_description() const { return description_; }
+
+    /// Set the description of the app
+    App *description(std::string app_description) {
+        description_ = std::move(app_description);
+        return this;
+    }
+
+    /// Get the list of options (user facing function, so returns raw pointers), has optional filter function
+    std::vector<const Option *> get_options(const std::function<bool(const Option *)> filter = {}) const;
+
+    /// Non-const version of the above
+    std::vector<Option *> get_options(const std::function<bool(Option *)> filter = {});
+
+    /// Get an option by name (noexcept non-const version)
+    CLI11_NODISCARD Option *get_option_no_throw(std::string option_name) noexcept;
+
+    /// Get an option by name (noexcept const version)
+    CLI11_NODISCARD const Option *get_option_no_throw(std::string option_name) const noexcept;
+
+    /// Get an option by name
+    CLI11_NODISCARD const Option *get_option(std::string option_name) const {
+        const auto *opt = get_option_no_throw(option_name);
+        if(opt == nullptr) {
+            throw OptionNotFound(option_name);
+        }
+        return opt;
+    }
+
+    /// Get an option by name (non-const version)
+    CLI11_NODISCARD Option *get_option(std::string option_name) {
+        auto *opt = get_option_no_throw(option_name);
+        if(opt == nullptr) {
+            throw OptionNotFound(option_name);
+        }
+        return opt;
+    }
+
+    /// Shortcut bracket operator for getting a pointer to an option
+    const Option *operator[](const std::string &option_name) const { return get_option(option_name); }
+
+    /// Shortcut bracket operator for getting a pointer to an option
+    const Option *operator[](const char *option_name) const { return get_option(option_name); }
+
+    /// Check the status of ignore_case
+    CLI11_NODISCARD bool get_ignore_case() const { return ignore_case_; }
+
+    /// Check the status of ignore_underscore
+    CLI11_NODISCARD bool get_ignore_underscore() const { return ignore_underscore_; }
+
+    /// Check the status of fallthrough
+    CLI11_NODISCARD bool get_fallthrough() const { return fallthrough_; }
+
+    /// Check the status of subcommand fallthrough
+    CLI11_NODISCARD bool get_subcommand_fallthrough() const { return subcommand_fallthrough_; }
+
+    /// Check the status of the allow windows style options
+    CLI11_NODISCARD bool get_allow_windows_style_options() const { return allow_windows_style_options_; }
+
+    /// Check the status of the allow windows style options
+    CLI11_NODISCARD bool get_positionals_at_end() const { return positionals_at_end_; }
+
+    /// Check the status of the allow windows style options
+    CLI11_NODISCARD bool get_configurable() const { return configurable_; }
+
+    /// Get the group of this subcommand
+    CLI11_NODISCARD const std::string &get_group() const { return group_; }
+
+    /// Generate and return the usage.
+    CLI11_NODISCARD std::string get_usage() const {
+        return (usage_callback_) ? usage_callback_() + '\n' + usage_ : usage_;
+    }
+
+    /// Generate and return the footer.
+    CLI11_NODISCARD std::string get_footer() const {
+        return (footer_callback_) ? footer_callback_() + '\n' + footer_ : footer_;
+    }
+
+    /// Get the required min subcommand value
+    CLI11_NODISCARD std::size_t get_require_subcommand_min() const { return require_subcommand_min_; }
+
+    /// Get the required max subcommand value
+    CLI11_NODISCARD std::size_t get_require_subcommand_max() const { return require_subcommand_max_; }
+
+    /// Get the required min option value
+    CLI11_NODISCARD std::size_t get_require_option_min() const { return require_option_min_; }
+
+    /// Get the required max option value
+    CLI11_NODISCARD std::size_t get_require_option_max() const { return require_option_max_; }
+
+    /// Get the prefix command status
+    CLI11_NODISCARD bool get_prefix_command() const { return static_cast<bool>(prefix_command_); }
+
+    /// Get the prefix command status
+    CLI11_NODISCARD PrefixCommandMode get_prefix_command_mode() const { return prefix_command_; }
+
+    /// Get the status of allow extras
+    CLI11_NODISCARD bool get_allow_extras() const { return allow_extras_ > ExtrasMode::Ignore; }
+
+    /// Get the mode of allow_extras
+    CLI11_NODISCARD ExtrasMode get_allow_extras_mode() const { return allow_extras_; }
+
+    /// Get the status of required
+    CLI11_NODISCARD bool get_required() const { return required_; }
+
+    /// Get the status of disabled
+    CLI11_NODISCARD bool get_disabled() const { return disabled_; }
+
+    /// Get the status of silence
+    CLI11_NODISCARD bool get_silent() const { return silent_; }
+
+    /// Get the status of allowing non standard option names
+    CLI11_NODISCARD bool get_allow_non_standard_option_names() const { return allow_non_standard_options_; }
+
+    /// Get the status of allowing prefix matching for subcommands
+    CLI11_NODISCARD bool get_allow_subcommand_prefix_matching() const { return allow_prefix_matching_; }
+
+    /// Get the status of disabled
+    CLI11_NODISCARD bool get_immediate_callback() const { return immediate_callback_; }
+
+    /// Get the status of disabled by default
+    CLI11_NODISCARD bool get_disabled_by_default() const { return (default_startup == startup_mode::disabled); }
+
+    /// Get the status of disabled by default
+    CLI11_NODISCARD bool get_enabled_by_default() const { return (default_startup == startup_mode::enabled); }
+    /// Get the status of validating positionals
+    CLI11_NODISCARD bool get_validate_positionals() const { return validate_positionals_; }
+    /// Get the status of validating optional vector arguments
+    CLI11_NODISCARD bool get_validate_optional_arguments() const { return validate_optional_arguments_; }
+
+    /// Get the status of allow extras
+    CLI11_NODISCARD config_extras_mode get_allow_config_extras() const {
+        return static_cast<config_extras_mode>(allow_config_extras_);
+    }
+
+    /// Get a pointer to the help flag.
+    Option *get_help_ptr() { return help_ptr_; }
+
+    /// Get a pointer to the help flag. (const)
+    CLI11_NODISCARD const Option *get_help_ptr() const { return help_ptr_; }
+
+    /// Get a pointer to the help all flag. (const)
+    CLI11_NODISCARD const Option *get_help_all_ptr() const { return help_all_ptr_; }
+
+    /// Get a pointer to the config option.
+    Option *get_config_ptr() { return config_ptr_; }
+
+    /// Get a pointer to the config option. (const)
+    CLI11_NODISCARD const Option *get_config_ptr() const { return config_ptr_; }
+
+    /// Get a pointer to the version option.
+    Option *get_version_ptr() { return version_ptr_; }
+
+    /// Get a pointer to the version option. (const)
+    CLI11_NODISCARD const Option *get_version_ptr() const { return version_ptr_; }
+
+    /// Get the parent of this subcommand (or nullptr if main app)
+    App *get_parent() { return parent_; }
+
+    /// Get the parent of this subcommand (or nullptr if main app) (const version)
+    CLI11_NODISCARD const App *get_parent() const { return parent_; }
+
+    /// Get the name of the current app
+    CLI11_NODISCARD const std::string &get_name() const { return name_; }
+
+    /// Get the aliases of the current app
+    CLI11_NODISCARD const std::vector<std::string> &get_aliases() const { return aliases_; }
+
+    /// clear all the aliases of the current App
+    App *clear_aliases() {
+        aliases_.clear();
+        return this;
+    }
+
+    /// Get a display name for an app
+    CLI11_NODISCARD std::string get_display_name(bool with_aliases = false) const;
+
+    /// Check the name, case-insensitive and underscore insensitive, and prefix matching if set
+    /// @return true if matched
+    CLI11_NODISCARD bool check_name(std::string name_to_check) const;
+
+    /// @brief  enumeration of matching possibilities
+    enum class NameMatch : std::uint8_t { none = 0, exact = 1, prefix = 2 };
+
+    /// Check the name, case-insensitive and underscore insensitive if set
+    /// @return NameMatch::none if no match, NameMatch::exact if the match is exact NameMatch::prefix if prefix is
+    /// enabled and a prefix matches
+    CLI11_NODISCARD NameMatch check_name_detail(std::string name_to_check) const;
+
+    /// Get the groups available directly from this option (in order)
+    CLI11_NODISCARD std::vector<std::string> get_groups() const;
+
+    /// This gets a vector of pointers with the original parse order
+    CLI11_NODISCARD const std::vector<Option *> &parse_order() const { return parse_order_; }
+
+    /// This returns the missing options from the current subcommand
+    CLI11_NODISCARD std::vector<std::string> remaining(bool recurse = false) const;
+
+    /// This returns the missing options in a form ready for processing by another command line program
+    CLI11_NODISCARD std::vector<std::string> remaining_for_passthrough(bool recurse = false) const;
+
+    /// This returns the number of remaining options, minus the -- separator
+    CLI11_NODISCARD std::size_t remaining_size(bool recurse = false) const;
+
+    ///@}
+
+  protected:
+    /// Check the options to make sure there are no conflicts.
+    ///
+    /// Currently checks to see if multiple positionals exist with unlimited args and checks if the min and max options
+    /// are feasible
+    void _validate() const;
+
+    /// configure subcommands to enable parsing through the current object
+    /// set the correct fallthrough and prefix for nameless subcommands and manage the automatic enable or disable
+    /// makes sure parent is set correctly
+    void _configure();
+
+    /// Internal function to run (App) callback, bottom up
+    void run_callback(bool final_mode = false, bool suppress_final_callback = false);
+
+    /// Check to see if a subcommand is valid. Give up immediately if subcommand max has been reached.
+    CLI11_NODISCARD bool _valid_subcommand(const std::string &current, bool ignore_used = true) const;
+
+    /// Selects a Classifier enum based on the type of the current argument
+    CLI11_NODISCARD detail::Classifier _recognize(const std::string &current,
+                                                  bool ignore_used_subcommands = true) const;
+
+    // The parse function is now broken into several parts, and part of process
+
+    /// Read and process a configuration file (main app only)
+    void _process_config_file();
+
+    /// Read and process a particular configuration file
+    bool _process_config_file(const std::string &config_file, bool throw_error);
+
+    /// Get envname options if not yet passed. Runs on *all* subcommands.
+    void _process_env();
+
+    /// Process callbacks. Runs on *all* subcommands.
+    void _process_callbacks(CallbackPriority priority);
+
+    /// Run help flag processing if any are found.
+    ///
+    /// The flags allow recursive calls to remember if there was a help flag on a parent.
+    void _process_help_flags(CallbackPriority priority, bool trigger_help = false, bool trigger_all_help = false) const;
+
+    /// Verify required options and cross requirements. Subcommands too (only if selected).
+    void _process_requirements();
+
+    /// Process callbacks and such.
+    void _process();
+
+    /// Throw an error if anything is left over and should not be.
+    void _process_extras();
+
+    /// Internal function to recursively increment the parsed counter on the current app as well unnamed subcommands
+    void increment_parsed();
+
+    /// Internal parse function
+    void _parse(std::vector<std::string> &args);
+
+    /// Internal parse function
+    void _parse(std::vector<std::string> &&args);
+
+    /// Internal function to parse a stream
+    void _parse_stream(std::istream &input);
+
+    /// Parse one config param, return false if not found in any subcommand, remove if it is
+    ///
+    /// If this has more than one dot.separated.name, go into the subcommand matching it
+    /// Returns true if it managed to find the option, if false you'll need to remove the arg manually.
+    void _parse_config(const std::vector<ConfigItem> &args);
+
+    /// Fill in a single config option
+    bool _parse_single_config(const ConfigItem &item, std::size_t level = 0);
+
+    /// @brief store the results for a flag like option
+    bool _add_flag_like_result(Option *op, const ConfigItem &item, const std::vector<std::string> &inputs);
+
+    /// Parse "one" argument (some may eat more than one), delegate to parent if fails, add to missing if missing
+    /// from main return false if the parse has failed and needs to return to parent
+    bool _parse_single(std::vector<std::string> &args, bool &positional_only);
+
+    /// Count the required remaining positional arguments
+    CLI11_NODISCARD std::size_t _count_remaining_positionals(bool required_only = false) const;
+
+    /// Count the required remaining positional arguments
+    CLI11_NODISCARD bool _has_remaining_positionals() const;
+
+    /// Parse a positional, go up the tree to check
+    /// @param haltOnSubcommand if set to true the operation will not process subcommands merely return false
+    /// Return true if the positional was used false otherwise
+    bool _parse_positional(std::vector<std::string> &args, bool haltOnSubcommand);
+
+    /// Locate a subcommand by name with two conditions, should disabled subcommands be ignored, and should used
+    /// subcommands be ignored
+    CLI11_NODISCARD App *
+    _find_subcommand(const std::string &subc_name, bool ignore_disabled, bool ignore_used) const noexcept;
+
+    /// Parse a subcommand, modify args and continue
+    ///
+    /// Unlike the others, this one will always allow fallthrough
+    /// return true if the subcommand was processed false otherwise
+    bool _parse_subcommand(std::vector<std::string> &args);
+
+    /// Parse a short (false) or long (true) argument, must be at the top of the list
+    /// if local_processing_only is set to true then fallthrough is disabled will return false if not found
+    /// return true if the argument was processed or false if nothing was done
+    bool _parse_arg(std::vector<std::string> &args, detail::Classifier current_type, bool local_processing_only);
+
+    /// Trigger the pre_parse callback if needed
+    void _trigger_pre_parse(std::size_t remaining_args);
+
+    /// Get the appropriate parent to fallthrough to which is the first one that has a name or the main app
+    CLI11_NODISCARD App *_get_fallthrough_parent() noexcept;
+
+    /// Get the appropriate parent to fallthrough to which is the first one that has a name or the main app
+    CLI11_NODISCARD const App *_get_fallthrough_parent() const noexcept;
+
+    /// Helper function to run through all possible comparisons of subcommand names to check there is no overlap
+    CLI11_NODISCARD const std::string &_compare_subcommand_names(const App &subcom, const App &base) const;
+
+    /// Helper function to place extra values in the most appropriate position
+    void _move_to_missing(detail::Classifier val_type, const std::string &val);
+
+  public:
+    /// function that could be used by subclasses of App to shift options around into subcommands
+    void _move_option(Option *opt, App *app);
+};  // namespace CLI
+
+/// Extension of App to better manage groups of options
+class Option_group : public App {
+  public:
+    Option_group(std::string group_description, std::string group_name, App *parent)
+        : App(std::move(group_description), "", parent) {
+        group(group_name);
+        // option groups should have automatic fallthrough
+        if(group_name.empty() || group_name.front() == '+') {
+            // help will not be used by default in these contexts
+            set_help_flag("");
+            set_help_all_flag("");
+        }
+    }
+    using App::add_option;
+    /// Add an existing option to the Option_group
+    Option *add_option(Option *opt) {
+        if(get_parent() == nullptr) {
+            throw OptionNotFound("Unable to locate the specified option");
+        }
+        get_parent()->_move_option(opt, this);
+        return opt;
+    }
+    /// Add an existing option to the Option_group
+    void add_options(Option *opt) { add_option(opt); }
+    /// Add a bunch of options to the group
+    template <typename... Args> void add_options(Option *opt, Args... args) {
+        add_option(opt);
+        add_options(args...);
+    }
+    using App::add_subcommand;
+    /// Add an existing subcommand to be a member of an option_group
+    App *add_subcommand(App *subcom) {
+        App_p subc = subcom->get_parent()->get_subcommand_ptr(subcom);
+        subc->get_parent()->remove_subcommand(subcom);
+        add_subcommand(std::move(subc));
+        return subcom;
+    }
+};
+
+/// Helper function to enable one option group/subcommand when another is used
+CLI11_INLINE void TriggerOn(App *trigger_app, App *app_to_enable);
+
+/// Helper function to enable one option group/subcommand when another is used
+CLI11_INLINE void TriggerOn(App *trigger_app, std::vector<App *> apps_to_enable);
+
+/// Helper function to disable one option group/subcommand when another is used
+CLI11_INLINE void TriggerOff(App *trigger_app, App *app_to_enable);
+
+/// Helper function to disable one option group/subcommand when another is used
+CLI11_INLINE void TriggerOff(App *trigger_app, std::vector<App *> apps_to_enable);
+
+/// Helper function to mark an option as deprecated
+CLI11_INLINE void deprecate_option(Option *opt, const std::string &replacement = "");
+
+/// Helper function to mark an option as deprecated
+inline void deprecate_option(App *app, const std::string &option_name, const std::string &replacement = "") {
+    auto *opt = app->get_option(option_name);
+    deprecate_option(opt, replacement);
+}
+
+/// Helper function to mark an option as deprecated
+inline void deprecate_option(App &app, const std::string &option_name, const std::string &replacement = "") {
+    auto *opt = app.get_option(option_name);
+    deprecate_option(opt, replacement);
+}
+
+/// Helper function to mark an option as retired
+CLI11_INLINE void retire_option(App *app, Option *opt);
+
+/// Helper function to mark an option as retired
+CLI11_INLINE void retire_option(App &app, Option *opt);
+
+/// Helper function to mark an option as retired
+CLI11_INLINE void retire_option(App *app, const std::string &option_name);
+
+/// Helper function to mark an option as retired
+CLI11_INLINE void retire_option(App &app, const std::string &option_name);
+
+namespace detail {
+/// This class is simply to allow tests access to App's protected functions
+struct AppFriend {
+#ifdef CLI11_CPP14
+
+    /// Wrap _parse_short, perfectly forward arguments and return
+    template <typename... Args> static decltype(auto) parse_arg(App *app, Args &&...args) {
+        return app->_parse_arg(std::forward<Args>(args)...);
+    }
+
+    /// Wrap _parse_subcommand, perfectly forward arguments and return
+    template <typename... Args> static decltype(auto) parse_subcommand(App *app, Args &&...args) {
+        return app->_parse_subcommand(std::forward<Args>(args)...);
+    }
+#else
+    /// Wrap _parse_short, perfectly forward arguments and return
+    template <typename... Args>
+    static auto parse_arg(App *app, Args &&...args) ->
+        typename std::result_of<decltype (&App::_parse_arg)(App, Args...)>::type {
+        return app->_parse_arg(std::forward<Args>(args)...);
+    }
+
+    /// Wrap _parse_subcommand, perfectly forward arguments and return
+    template <typename... Args>
+    static auto parse_subcommand(App *app, Args &&...args) ->
+        typename std::result_of<decltype (&App::_parse_subcommand)(App, Args...)>::type {
+        return app->_parse_subcommand(std::forward<Args>(args)...);
+    }
+#endif
+    /// Wrap the fallthrough parent function to make sure that is working correctly
+    static App *get_fallthrough_parent(App *app) { return app->_get_fallthrough_parent(); }
+
+    /// Wrap the const fallthrough parent function to make sure that is working correctly
+    static const App *get_fallthrough_parent(const App *app) { return app->_get_fallthrough_parent(); }
+};
+}  // namespace detail
+
+
+
+
+CLI11_INLINE App::App(std::string app_description, std::string app_name, App *parent)
+    : name_(std::move(app_name)), description_(std::move(app_description)), parent_(parent) {
+    // Inherit if not from a nullptr
+    if(parent_ != nullptr) {
+        if(parent_->help_ptr_ != nullptr)
+            set_help_flag(parent_->help_ptr_->get_name(false, true), parent_->help_ptr_->get_description());
+        if(parent_->help_all_ptr_ != nullptr)
+            set_help_all_flag(parent_->help_all_ptr_->get_name(false, true), parent_->help_all_ptr_->get_description());
+
+        /// OptionDefaults
+        option_defaults_ = parent_->option_defaults_;
+
+        // INHERITABLE
+        failure_message_ = parent_->failure_message_;
+        allow_extras_ = parent_->allow_extras_;
+        allow_config_extras_ = parent_->allow_config_extras_;
+        prefix_command_ = parent_->prefix_command_;
+        immediate_callback_ = parent_->immediate_callback_;
+        ignore_case_ = parent_->ignore_case_;
+        ignore_underscore_ = parent_->ignore_underscore_;
+        fallthrough_ = parent_->fallthrough_;
+        validate_positionals_ = parent_->validate_positionals_;
+        validate_optional_arguments_ = parent_->validate_optional_arguments_;
+        configurable_ = parent_->configurable_;
+        allow_windows_style_options_ = parent_->allow_windows_style_options_;
+        group_ = parent_->group_;
+        usage_ = parent_->usage_;
+        footer_ = parent_->footer_;
+        formatter_ = parent_->formatter_;
+        config_formatter_ = parent_->config_formatter_;
+        require_subcommand_max_ = parent_->require_subcommand_max_;
+        allow_prefix_matching_ = parent_->allow_prefix_matching_;
+    }
+}
+
+CLI11_NODISCARD CLI11_INLINE char **App::ensure_utf8(char **argv) {
+#ifdef _WIN32
+    (void)argv;
+
+    normalized_argv_ = detail::compute_win32_argv();
+
+    if(!normalized_argv_view_.empty()) {
+        normalized_argv_view_.clear();
+    }
+
+    normalized_argv_view_.reserve(normalized_argv_.size());
+    for(auto &arg : normalized_argv_) {
+        // using const_cast is well-defined, string is known to not be const.
+        normalized_argv_view_.push_back(const_cast<char *>(arg.data()));
+    }
+
+    return normalized_argv_view_.data();
+#else
+    return argv;
+#endif
+}
+
+CLI11_INLINE App *App::name(std::string app_name) {
+
+    if(parent_ != nullptr) {
+        std::string oname = name_;
+        name_ = app_name;
+        const auto &res = _compare_subcommand_names(*this, *_get_fallthrough_parent());
+        if(!res.empty()) {
+            name_ = oname;
+            throw(OptionAlreadyAdded(app_name + " conflicts with existing subcommand names"));
+        }
+    } else {
+        name_ = app_name;
+    }
+    has_automatic_name_ = false;
+    return this;
+}
+
+CLI11_INLINE App *App::alias(std::string app_name) {
+    if(app_name.empty() || !detail::valid_alias_name_string(app_name)) {
+        throw IncorrectConstruction("Aliases may not be empty or contain newlines or null characters");
+    }
+    if(parent_ != nullptr) {
+        aliases_.push_back(app_name);
+        const auto &res = _compare_subcommand_names(*this, *_get_fallthrough_parent());
+        if(!res.empty()) {
+            aliases_.pop_back();
+            throw(OptionAlreadyAdded("alias already matches an existing subcommand: " + app_name));
+        }
+    } else {
+        aliases_.push_back(app_name);
+    }
+
+    return this;
+}
+
+CLI11_INLINE App *App::immediate_callback(bool immediate) {
+    immediate_callback_ = immediate;
+    if(immediate_callback_) {
+        if(final_callback_ && !(parse_complete_callback_)) {
+            std::swap(final_callback_, parse_complete_callback_);
+        }
+    } else if(!(final_callback_) && parse_complete_callback_) {
+        std::swap(final_callback_, parse_complete_callback_);
+    }
+    return this;
+}
+
+CLI11_INLINE App *App::ignore_case(bool value) {
+    if(value && !ignore_case_) {
+        ignore_case_ = true;
+        auto *p = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
+        const auto &match = _compare_subcommand_names(*this, *p);
+        if(!match.empty()) {
+            ignore_case_ = false;  // we are throwing so need to be exception invariant
+            throw OptionAlreadyAdded("ignore case would cause subcommand name conflicts: " + match);
+        }
+    }
+    ignore_case_ = value;
+    return this;
+}
+
+CLI11_INLINE App *App::ignore_underscore(bool value) {
+    if(value && !ignore_underscore_) {
+        ignore_underscore_ = true;
+        auto *p = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
+        const auto &match = _compare_subcommand_names(*this, *p);
+        if(!match.empty()) {
+            ignore_underscore_ = false;
+            throw OptionAlreadyAdded("ignore underscore would cause subcommand name conflicts: " + match);
+        }
+    }
+    ignore_underscore_ = value;
+    return this;
+}
+
+CLI11_INLINE Option *App::add_option(std::string option_name,
+                                     callback_t option_callback,
+                                     std::string option_description,
+                                     bool defaulted,
+                                     std::function<std::string()> func) {
+    Option myopt{option_name, option_description, option_callback, this, allow_non_standard_options_};
+
+    // do a quick search in current subcommand for options
+    auto res =
+        std::find_if(std::begin(options_), std::end(options_), [&myopt](const Option_p &v) { return *v == myopt; });
+    if(res != options_.end()) {
+        const auto &matchname = (*res)->matching_name(myopt);
+        throw(OptionAlreadyAdded("added option matched existing option name: " + matchname));
+    }
+    /** get a top level parent*/
+    const App *top_level_parent = this;
+    while(top_level_parent->name_.empty() && top_level_parent->parent_ != nullptr) {
+        top_level_parent = top_level_parent->parent_;
+    }
+
+    if(myopt.lnames_.empty() && myopt.snames_.empty()) {
+        // if the option is positional only there is additional potential for ambiguities in config files and needs
+        // to be checked
+        std::string test_name = "--" + myopt.get_single_name();
+        if(test_name.size() == 3) {
+            test_name.erase(0, 1);
+        }
+        // if we are in option group
+        const auto *op = top_level_parent->get_option_no_throw(test_name);
+        if(op != nullptr && op->get_configurable()) {
+            throw(OptionAlreadyAdded("added option positional name matches existing option: " + test_name));
+        }
+        // need to check if there is another positional with the same name that also doesn't have any long or
+        // short names
+        op = top_level_parent->get_option_no_throw(myopt.get_single_name());
+        if(op != nullptr && op->lnames_.empty() && op->snames_.empty()) {
+            throw(OptionAlreadyAdded("unable to disambiguate with existing option: " + test_name));
+        }
+    } else if(top_level_parent != this) {
+        for(auto &ln : myopt.lnames_) {
+            const auto *op = top_level_parent->get_option_no_throw(ln);
+            if(op != nullptr && op->get_configurable()) {
+                throw(OptionAlreadyAdded("added option matches existing positional option: " + ln));
+            }
+            op = top_level_parent->get_option_no_throw("--" + ln);
+            if(op != nullptr && op->get_configurable()) {
+                throw(OptionAlreadyAdded("added option matches existing option: --" + ln));
+            }
+            if(ln.size() == 1 || top_level_parent->get_allow_non_standard_option_names()) {
+                op = top_level_parent->get_option_no_throw("-" + ln);
+                if(op != nullptr && op->get_configurable()) {
+                    throw(OptionAlreadyAdded("added option matches existing option: -" + ln));
+                }
+            }
+        }
+        for(auto &sn : myopt.snames_) {
+            const auto *op = top_level_parent->get_option_no_throw(sn);
+            if(op != nullptr && op->get_configurable()) {
+                throw(OptionAlreadyAdded("added option matches existing positional option: " + sn));
+            }
+            op = top_level_parent->get_option_no_throw("-" + sn);
+            if(op != nullptr && op->get_configurable()) {
+                throw(OptionAlreadyAdded("added option matches existing option: -" + sn));
+            }
+            op = top_level_parent->get_option_no_throw("--" + sn);
+            if(op != nullptr && op->get_configurable()) {
+                throw(OptionAlreadyAdded("added option matches existing option: --" + sn));
+            }
+        }
+    }
+    if(allow_non_standard_options_ && !myopt.snames_.empty()) {
+
+        for(auto &sname : myopt.snames_) {
+            if(sname.length() > 1) {
+                std::string test_name;
+                test_name.push_back('-');
+                test_name.push_back(sname.front());
+                const auto *op = top_level_parent->get_option_no_throw(test_name);
+                if(op != nullptr) {
+                    throw(OptionAlreadyAdded("added option interferes with existing short option: " + sname));
+                }
+            }
+        }
+        for(auto &opt : top_level_parent->get_options()) {
+            for(const auto &osn : opt->snames_) {
+                if(osn.size() > 1) {
+                    std::string test_name;
+                    test_name.push_back(osn.front());
+                    if(myopt.check_sname(test_name)) {
+                        throw(OptionAlreadyAdded("added option interferes with existing non standard option: " + osn));
+                    }
+                }
+            }
+        }
+    }
+    options_.emplace_back();
+    Option_p &option = options_.back();
+    option.reset(new Option(option_name, option_description, option_callback, this, allow_non_standard_options_));
+
+    // Set the default string capture function
+    option->default_function(func);
+
+    // For compatibility with CLI11 1.7 and before, capture the default string here
+    if(defaulted)
+        option->capture_default_str();
+
+    // Transfer defaults to the new option
+    option_defaults_.copy_to(option.get());
+
+    // Don't bother to capture if we already did
+    if(!defaulted && option->get_always_capture_default())
+        option->capture_default_str();
+
+    return option.get();
+}
+
+CLI11_INLINE Option *App::set_help_flag(std::string flag_name, const std::string &help_description) {
+    // take flag_description by const reference otherwise add_flag tries to assign to help_description
+    if(help_ptr_ != nullptr) {
+        remove_option(help_ptr_);
+        help_ptr_ = nullptr;
+    }
+
+    // Empty name will simply remove the help flag
+    if(!flag_name.empty()) {
+        help_ptr_ = add_flag(flag_name, help_description);
+        help_ptr_->configurable(false)->callback_priority(CallbackPriority::First);
+    }
+
+    return help_ptr_;
+}
+
+CLI11_INLINE Option *App::set_help_all_flag(std::string help_name, const std::string &help_description) {
+    // take flag_description by const reference otherwise add_flag tries to assign to flag_description
+    if(help_all_ptr_ != nullptr) {
+        remove_option(help_all_ptr_);
+        help_all_ptr_ = nullptr;
+    }
+
+    // Empty name will simply remove the help all flag
+    if(!help_name.empty()) {
+        help_all_ptr_ = add_flag(help_name, help_description);
+        help_all_ptr_->configurable(false)->callback_priority(CallbackPriority::First);
+    }
+
+    return help_all_ptr_;
+}
+
+CLI11_INLINE Option *
+App::set_version_flag(std::string flag_name, const std::string &versionString, const std::string &version_help) {
+    // take flag_description by const reference otherwise add_flag tries to assign to version_description
+    if(version_ptr_ != nullptr) {
+        remove_option(version_ptr_);
+        version_ptr_ = nullptr;
+    }
+
+    // Empty name will simply remove the version flag
+    if(!flag_name.empty()) {
+        version_ptr_ = add_flag_callback(
+            flag_name, [versionString]() { throw(CLI::CallForVersion(versionString, 0)); }, version_help);
+        version_ptr_->configurable(false)->callback_priority(CallbackPriority::First);
+    }
+
+    return version_ptr_;
+}
+
+CLI11_INLINE Option *
+App::set_version_flag(std::string flag_name, std::function<std::string()> vfunc, const std::string &version_help) {
+    if(version_ptr_ != nullptr) {
+        remove_option(version_ptr_);
+        version_ptr_ = nullptr;
+    }
+
+    // Empty name will simply remove the version flag
+    if(!flag_name.empty()) {
+        version_ptr_ =
+            add_flag_callback(flag_name, [vfunc]() { throw(CLI::CallForVersion(vfunc(), 0)); }, version_help);
+        version_ptr_->configurable(false)->callback_priority(CallbackPriority::First);
+    }
+
+    return version_ptr_;
+}
+
+CLI11_INLINE Option *App::_add_flag_internal(std::string flag_name, CLI::callback_t fun, std::string flag_description) {
+    Option *opt = nullptr;
+    if(detail::has_default_flag_values(flag_name)) {
+        // check for default values and if it has them
+        auto flag_defaults = detail::get_default_flag_values(flag_name);
+        detail::remove_default_flag_values(flag_name);
+        opt = add_option(std::move(flag_name), std::move(fun), std::move(flag_description), false);
+        for(const auto &fname : flag_defaults)
+            opt->fnames_.push_back(fname.first);
+        opt->default_flag_values_ = std::move(flag_defaults);
+    } else {
+        opt = add_option(std::move(flag_name), std::move(fun), std::move(flag_description), false);
+    }
+    // flags cannot have positional values
+    if(opt->get_positional()) {
+        auto pos_name = opt->get_name(true);
+        remove_option(opt);
+        throw IncorrectConstruction::PositionalFlag(pos_name);
+    }
+    opt->multi_option_policy(MultiOptionPolicy::TakeLast);
+    opt->expected(0);
+    opt->required(false);
+    return opt;
+}
+
+CLI11_INLINE Option *App::add_flag_callback(std::string flag_name,
+                                            std::function<void(void)> function,  ///< A function to call, void(void)
+                                            std::string flag_description) {
+
+    CLI::callback_t fun = [function](const CLI::results_t &res) {
+        using CLI::detail::lexical_cast;
+        bool trigger{false};
+        auto result = lexical_cast(res[0], trigger);
+        if(result && trigger) {
+            function();
+        }
+        return result;
+    };
+    return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description));
+}
+
+CLI11_INLINE Option *
+App::add_flag_function(std::string flag_name,
+                       std::function<void(std::int64_t)> function,  ///< A function to call, void(int)
+                       std::string flag_description) {
+
+    CLI::callback_t fun = [function](const CLI::results_t &res) {
+        using CLI::detail::lexical_cast;
+        std::int64_t flag_count{0};
+        lexical_cast(res[0], flag_count);
+        function(flag_count);
+        return true;
+    };
+    return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description))
+        ->multi_option_policy(MultiOptionPolicy::Sum);
+}
+
+CLI11_INLINE Option *App::set_config(std::string option_name,
+                                     std::string default_filename,
+                                     const std::string &help_message,
+                                     bool config_required) {
+
+    // Remove existing config if present
+    if(config_ptr_ != nullptr) {
+        remove_option(config_ptr_);
+        config_ptr_ = nullptr;  // need to remove the config_ptr completely
+    }
+
+    // Only add config if option passed
+    if(!option_name.empty()) {
+        config_ptr_ = add_option(option_name, help_message);
+        if(config_required) {
+            config_ptr_->required();
+        }
+        if(!default_filename.empty()) {
+            config_ptr_->default_str(std::move(default_filename));
+            config_ptr_->force_callback_ = true;
+        }
+        config_ptr_->configurable(false);
+        // set the option to take the last value and reverse given by default
+        config_ptr_->multi_option_policy(MultiOptionPolicy::Reverse);
+    }
+
+    return config_ptr_;
+}
+
+CLI11_INLINE bool App::remove_option(Option *opt) {
+    // Make sure no links exist
+    for(Option_p &op : options_) {
+        op->remove_needs(opt);
+        op->remove_excludes(opt);
+    }
+
+    if(help_ptr_ == opt)
+        help_ptr_ = nullptr;
+    if(help_all_ptr_ == opt)
+        help_all_ptr_ = nullptr;
+    if(config_ptr_ == opt)
+        config_ptr_ = nullptr;
+
+    auto iterator =
+        std::find_if(std::begin(options_), std::end(options_), [opt](const Option_p &v) { return v.get() == opt; });
+    if(iterator != std::end(options_)) {
+        options_.erase(iterator);
+        return true;
+    }
+    return false;
+}
+
+CLI11_INLINE App *App::add_subcommand(std::string subcommand_name, std::string subcommand_description) {
+    if(!subcommand_name.empty() && !detail::valid_name_string(subcommand_name)) {
+        if(!detail::valid_first_char(subcommand_name[0])) {
+            throw IncorrectConstruction(
+                "Subcommand name starts with invalid character, '!' and '-' and control characters");
+        }
+        for(auto c : subcommand_name) {
+            if(!detail::valid_later_char(c)) {
+                throw IncorrectConstruction(std::string("Subcommand name contains invalid character ('") + c +
+                                            "'), all characters are allowed except"
+                                            "'=',':','{','}', ' ', and control characters");
+            }
+        }
+    }
+    CLI::App_p subcom = std::shared_ptr<App>(new App(std::move(subcommand_description), subcommand_name, this));
+    return add_subcommand(std::move(subcom));
+}
+
+CLI11_INLINE App *App::add_subcommand(CLI::App_p subcom) {
+    if(!subcom)
+        throw IncorrectConstruction("passed App is not valid");
+    auto *ckapp = (name_.empty() && parent_ != nullptr) ? _get_fallthrough_parent() : this;
+    const auto &mstrg = _compare_subcommand_names(*subcom, *ckapp);
+    if(!mstrg.empty()) {
+        throw(OptionAlreadyAdded("subcommand name or alias matches existing subcommand: " + mstrg));
+    }
+    subcom->parent_ = this;
+    subcommands_.push_back(std::move(subcom));
+    return subcommands_.back().get();
+}
+
+CLI11_INLINE bool App::remove_subcommand(App *subcom) {
+    // Make sure no links exist
+    for(App_p &sub : subcommands_) {
+        sub->remove_excludes(subcom);
+        sub->remove_needs(subcom);
+    }
+
+    auto iterator = std::find_if(
+        std::begin(subcommands_), std::end(subcommands_), [subcom](const App_p &v) { return v.get() == subcom; });
+    if(iterator != std::end(subcommands_)) {
+        subcommands_.erase(iterator);
+        return true;
+    }
+    return false;
+}
+
+CLI11_INLINE App *App::get_subcommand(const App *subcom) const {
+    if(subcom == nullptr)
+        throw OptionNotFound("nullptr passed");
+    for(const App_p &subcomptr : subcommands_)
+        if(subcomptr.get() == subcom)
+            return subcomptr.get();
+    throw OptionNotFound(subcom->get_name());
+}
+
+CLI11_NODISCARD CLI11_INLINE App *App::get_subcommand(std::string subcom) const {
+    auto *subc = _find_subcommand(subcom, false, false);
+    if(subc == nullptr)
+        throw OptionNotFound(subcom);
+    return subc;
+}
+
+CLI11_NODISCARD CLI11_INLINE App *App::get_subcommand_no_throw(std::string subcom) const noexcept {
+    return _find_subcommand(subcom, false, false);
+}
+
+CLI11_NODISCARD CLI11_INLINE App *App::get_subcommand(int index) const {
+    if(index >= 0) {
+        auto uindex = static_cast<unsigned>(index);
+        if(uindex < subcommands_.size())
+            return subcommands_[uindex].get();
+    }
+    throw OptionNotFound(std::to_string(index));
+}
+
+CLI11_INLINE CLI::App_p App::get_subcommand_ptr(App *subcom) const {
+    if(subcom == nullptr)
+        throw OptionNotFound("nullptr passed");
+    for(const App_p &subcomptr : subcommands_)
+        if(subcomptr.get() == subcom)
+            return subcomptr;
+    throw OptionNotFound(subcom->get_name());
+}
+
+CLI11_NODISCARD CLI11_INLINE CLI::App_p App::get_subcommand_ptr(std::string subcom) const {
+    for(const App_p &subcomptr : subcommands_)
+        if(subcomptr->check_name(subcom))
+            return subcomptr;
+    throw OptionNotFound(subcom);
+}
+
+CLI11_NODISCARD CLI11_INLINE CLI::App_p App::get_subcommand_ptr(int index) const {
+    if(index >= 0) {
+        auto uindex = static_cast<unsigned>(index);
+        if(uindex < subcommands_.size())
+            return subcommands_[uindex];
+    }
+    throw OptionNotFound(std::to_string(index));
+}
+
+CLI11_NODISCARD CLI11_INLINE CLI::App *App::get_option_group(std::string group_name) const {
+    for(const App_p &app : subcommands_) {
+        if(app->name_.empty() && app->group_ == group_name) {
+            return app.get();
+        }
+    }
+    throw OptionNotFound(group_name);
+}
+
+CLI11_NODISCARD CLI11_INLINE std::size_t App::count_all() const {
+    std::size_t cnt{0};
+    for(const auto &opt : options_) {
+        cnt += opt->count();
+    }
+    for(const auto &sub : subcommands_) {
+        cnt += sub->count_all();
+    }
+    if(!get_name().empty()) {  // for named subcommands add the number of times the subcommand was called
+        cnt += parsed_;
+    }
+    return cnt;
+}
+
+CLI11_INLINE void App::clear() {
+
+    parsed_ = 0;
+    pre_parse_called_ = false;
+
+    missing_.clear();
+    parsed_subcommands_.clear();
+    parse_order_.clear();
+    for(const Option_p &opt : options_) {
+        opt->clear();
+    }
+    for(const App_p &subc : subcommands_) {
+        subc->clear();
+    }
+}
+
+CLI11_INLINE void App::parse(int argc, const char *const *argv) { parse_char_t(argc, argv); }
+CLI11_INLINE void App::parse(int argc, const wchar_t *const *argv) { parse_char_t(argc, argv); }
+
+namespace detail {
+
+// Do nothing or perform narrowing
+CLI11_INLINE const char *maybe_narrow(const char *str) { return str; }
+CLI11_INLINE std::string maybe_narrow(const wchar_t *str) { return narrow(str); }
+
+}  // namespace detail
+
+template <class CharT> CLI11_INLINE void App::parse_char_t(int argc, const CharT *const *argv) {
+    // If the name is not set, read from command line
+    if(name_.empty() || has_automatic_name_) {
+        has_automatic_name_ = true;
+        name_ = detail::maybe_narrow(argv[0]);
+    }
+
+    std::vector<std::string> args;
+    args.reserve(static_cast<std::size_t>(argc) - 1U);
+    for(auto i = static_cast<std::size_t>(argc) - 1U; i > 0U; --i)
+        args.emplace_back(detail::maybe_narrow(argv[i]));
+
+    parse(std::move(args));
+}
+
+CLI11_INLINE void App::parse(std::string commandline, bool program_name_included) {
+
+    if(program_name_included) {
+        auto nstr = detail::split_program_name(commandline);
+        if((name_.empty()) || (has_automatic_name_)) {
+            has_automatic_name_ = true;
+            name_ = nstr.first;
+        }
+        commandline = std::move(nstr.second);
+    } else {
+        detail::trim(commandline);
+    }
+    // the next section of code is to deal with quoted arguments after an '=' or ':' for windows like operations
+    if(!commandline.empty()) {
+        commandline = detail::find_and_modify(commandline, "=", detail::escape_detect);
+        if(allow_windows_style_options_)
+            commandline = detail::find_and_modify(commandline, ":", detail::escape_detect);
+    }
+
+    auto args = detail::split_up(std::move(commandline));
+    // remove all empty strings
+    args.erase(std::remove(args.begin(), args.end(), std::string{}), args.end());
+    try {
+        detail::remove_quotes(args);
+    } catch(const std::invalid_argument &arg) {
+        throw CLI::ParseError(arg.what(), CLI::ExitCodes::InvalidError);
+    }
+    std::reverse(args.begin(), args.end());
+    parse(std::move(args));
+}
+
+CLI11_INLINE void App::parse(std::wstring commandline, bool program_name_included) {
+    parse(narrow(commandline), program_name_included);
+}
+
+CLI11_INLINE void App::parse(std::vector<std::string> &args) {
+    // Clear if parsed
+    if(parsed_ > 0)
+        clear();
+
+    // parsed_ is incremented in commands/subcommands,
+    // but placed here to make sure this is cleared when
+    // running parse after an error is thrown, even by _validate or _configure.
+    parsed_ = 1;
+    _validate();
+    _configure();
+    // set the parent as nullptr as this object should be the top now
+    parent_ = nullptr;
+    parsed_ = 0;
+
+    _parse(args);
+    run_callback();
+}
+
+CLI11_INLINE void App::parse(std::vector<std::string> &&args) {
+    // Clear if parsed
+    if(parsed_ > 0)
+        clear();
+
+    // parsed_ is incremented in commands/subcommands,
+    // but placed here to make sure this is cleared when
+    // running parse after an error is thrown, even by _validate or _configure.
+    parsed_ = 1;
+    _validate();
+    _configure();
+    // set the parent as nullptr as this object should be the top now
+    parent_ = nullptr;
+    parsed_ = 0;
+
+    _parse(std::move(args));
+    run_callback();
+}
+
+CLI11_INLINE void App::parse_from_stream(std::istream &input) {
+    if(parsed_ == 0) {
+        _validate();
+        _configure();
+        // set the parent as nullptr as this object should be the top now
+    }
+
+    _parse_stream(input);
+    run_callback();
+}
+
+CLI11_INLINE int App::exit(const Error &e, std::ostream &out, std::ostream &err) const {
+
+    /// Avoid printing anything if this is a CLI::RuntimeError
+    if(e.get_name() == "RuntimeError")
+        return e.get_exit_code();
+
+    if(e.get_name() == "CallForHelp") {
+        out << help();
+        return e.get_exit_code();
+    }
+
+    if(e.get_name() == "CallForAllHelp") {
+        out << help("", AppFormatMode::All);
+        return e.get_exit_code();
+    }
+
+    if(e.get_name() == "CallForVersion") {
+        out << e.what() << '\n';
+        return e.get_exit_code();
+    }
+
+    if(e.get_exit_code() != static_cast<int>(ExitCodes::Success)) {
+        if(failure_message_)
+            err << failure_message_(this, e) << std::flush;
+    }
+
+    return e.get_exit_code();
+}
+
+CLI11_INLINE std::vector<const App *> App::get_subcommands(const std::function<bool(const App *)> &filter) const {
+    std::vector<const App *> subcomms(subcommands_.size());
+    std::transform(
+        std::begin(subcommands_), std::end(subcommands_), std::begin(subcomms), [](const App_p &v) { return v.get(); });
+
+    if(filter) {
+        subcomms.erase(std::remove_if(std::begin(subcomms),
+                                      std::end(subcomms),
+                                      [&filter](const App *app) { return !filter(app); }),
+                       std::end(subcomms));
+    }
+
+    return subcomms;
+}
+
+CLI11_INLINE std::vector<App *> App::get_subcommands(const std::function<bool(App *)> &filter) {
+    std::vector<App *> subcomms(subcommands_.size());
+    std::transform(
+        std::begin(subcommands_), std::end(subcommands_), std::begin(subcomms), [](const App_p &v) { return v.get(); });
+
+    if(filter) {
+        subcomms.erase(
+            std::remove_if(std::begin(subcomms), std::end(subcomms), [&filter](App *app) { return !filter(app); }),
+            std::end(subcomms));
+    }
+
+    return subcomms;
+}
+
+CLI11_INLINE bool App::remove_excludes(Option *opt) {
+    auto iterator = std::find(std::begin(exclude_options_), std::end(exclude_options_), opt);
+    if(iterator == std::end(exclude_options_)) {
+        return false;
+    }
+    exclude_options_.erase(iterator);
+    return true;
+}
+
+CLI11_INLINE bool App::remove_excludes(App *app) {
+    auto iterator = std::find(std::begin(exclude_subcommands_), std::end(exclude_subcommands_), app);
+    if(iterator == std::end(exclude_subcommands_)) {
+        return false;
+    }
+    auto *other_app = *iterator;
+    exclude_subcommands_.erase(iterator);
+    other_app->remove_excludes(this);
+    return true;
+}
+
+CLI11_INLINE bool App::remove_needs(Option *opt) {
+    auto iterator = std::find(std::begin(need_options_), std::end(need_options_), opt);
+    if(iterator == std::end(need_options_)) {
+        return false;
+    }
+    need_options_.erase(iterator);
+    return true;
+}
+
+CLI11_INLINE bool App::remove_needs(App *app) {
+    auto iterator = std::find(std::begin(need_subcommands_), std::end(need_subcommands_), app);
+    if(iterator == std::end(need_subcommands_)) {
+        return false;
+    }
+    need_subcommands_.erase(iterator);
+    return true;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::string App::help(std::string prev, AppFormatMode mode) const {
+    if(prev.empty())
+        prev = get_name();
+    else
+        prev += " " + get_name();
+
+    // Delegate to subcommand if needed
+    auto selected_subcommands = get_subcommands();
+    if(!selected_subcommands.empty()) {
+        return selected_subcommands.back()->help(prev, mode);
+    }
+    return formatter_->make_help(this, prev, mode);
+}
+
+CLI11_NODISCARD CLI11_INLINE std::string App::version() const {
+    std::string val;
+    if(version_ptr_ != nullptr) {
+        // copy the results for reuse later
+        results_t rv = version_ptr_->results();
+        version_ptr_->clear();
+        version_ptr_->add_result("true");
+        try {
+            version_ptr_->run_callback();
+        } catch(const CLI::CallForVersion &cfv) {
+            val = cfv.what();
+        }
+        version_ptr_->clear();
+        version_ptr_->add_result(rv);
+    }
+    return val;
+}
+
+CLI11_INLINE std::vector<const Option *> App::get_options(const std::function<bool(const Option *)> filter) const {
+    std::vector<const Option *> options(options_.size());
+    std::transform(
+        std::begin(options_), std::end(options_), std::begin(options), [](const Option_p &val) { return val.get(); });
+
+    if(filter) {
+        options.erase(std::remove_if(std::begin(options),
+                                     std::end(options),
+                                     [&filter](const Option *opt) { return !filter(opt); }),
+                      std::end(options));
+    }
+    for(const auto &subcp : subcommands_) {
+        // also check down into nameless subcommands
+        const App *subc = subcp.get();
+        if(subc->get_name().empty() && !subc->get_group().empty() && subc->get_group().front() == '+') {
+            std::vector<const Option *> subcopts = subc->get_options(filter);
+            options.insert(options.end(), subcopts.begin(), subcopts.end());
+        }
+    }
+    if(fallthrough_ && parent_ != nullptr) {
+        const auto *fallthrough_parent = _get_fallthrough_parent();
+        std::vector<const Option *> subcopts = fallthrough_parent->get_options(filter);
+        for(const auto *opt : subcopts) {
+            if(std::find_if(options.begin(), options.end(), [opt](const Option *opt2) {
+                   return opt->check_name(opt2->get_name());
+               }) == options.end()) {
+                options.push_back(opt);
+            }
+        }
+    }
+    return options;
+}
+
+CLI11_INLINE std::vector<Option *> App::get_options(const std::function<bool(Option *)> filter) {
+    std::vector<Option *> options(options_.size());
+    std::transform(
+        std::begin(options_), std::end(options_), std::begin(options), [](const Option_p &val) { return val.get(); });
+
+    if(filter) {
+        options.erase(
+            std::remove_if(std::begin(options), std::end(options), [&filter](Option *opt) { return !filter(opt); }),
+            std::end(options));
+    }
+    for(auto &subc : subcommands_) {
+        // also check down into nameless subcommands and specific groups
+        if(subc->get_name().empty() || (!subc->get_group().empty() && subc->get_group().front() == '+')) {
+            auto subcopts = subc->get_options(filter);
+            options.insert(options.end(), subcopts.begin(), subcopts.end());
+        }
+    }
+    if(fallthrough_ && parent_ != nullptr) {
+        auto *fallthrough_parent = _get_fallthrough_parent();
+        std::vector<Option *> subcopts = fallthrough_parent->get_options(filter);
+        for(auto *opt : subcopts) {
+            if(std::find_if(options.begin(), options.end(), [opt](Option *opt2) {
+                   return opt->check_name(opt2->get_name());
+               }) == options.end()) {
+                options.push_back(opt);
+            }
+        }
+    }
+    return options;
+}
+
+CLI11_NODISCARD CLI11_INLINE Option *App::get_option_no_throw(std::string option_name) noexcept {
+    for(Option_p &opt : options_) {
+        if(opt->check_name(option_name)) {
+            return opt.get();
+        }
+    }
+    for(auto &subc : subcommands_) {
+        // also check down into nameless subcommands
+        if(subc->get_name().empty()) {
+            auto *opt = subc->get_option_no_throw(option_name);
+            if(opt != nullptr) {
+                return opt;
+            }
+        }
+    }
+    if(fallthrough_ && parent_ != nullptr) {
+        return _get_fallthrough_parent()->get_option_no_throw(option_name);
+    }
+    return nullptr;
+}
+
+CLI11_NODISCARD CLI11_INLINE const Option *App::get_option_no_throw(std::string option_name) const noexcept {
+    for(const Option_p &opt : options_) {
+        if(opt->check_name(option_name)) {
+            return opt.get();
+        }
+    }
+    for(const auto &subc : subcommands_) {
+        // also check down into nameless subcommands
+        if(subc->get_name().empty()) {
+            auto *opt = subc->get_option_no_throw(option_name);
+            if(opt != nullptr) {
+                return opt;
+            }
+        }
+    }
+    if(fallthrough_ && parent_ != nullptr) {
+        return _get_fallthrough_parent()->get_option_no_throw(option_name);
+    }
+    return nullptr;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::string App::get_display_name(bool with_aliases) const {
+    if(name_.empty()) {
+        return std::string("[Option Group: ") + get_group() + "]";
+    }
+    if(aliases_.empty() || !with_aliases) {
+        return name_;
+    }
+    std::string dispname = name_;
+    for(const auto &lalias : aliases_) {
+        dispname.push_back(',');
+        dispname.push_back(' ');
+        dispname.append(lalias);
+    }
+    return dispname;
+}
+
+CLI11_NODISCARD CLI11_INLINE bool App::check_name(std::string name_to_check) const {
+    auto result = check_name_detail(std::move(name_to_check));
+    return (result != NameMatch::none);
+}
+
+CLI11_NODISCARD CLI11_INLINE App::NameMatch App::check_name_detail(std::string name_to_check) const {
+    std::string local_name = name_;
+    if(ignore_underscore_) {
+        local_name = detail::remove_underscore(name_);
+        name_to_check = detail::remove_underscore(name_to_check);
+    }
+    if(ignore_case_) {
+        local_name = detail::to_lower(name_);
+        name_to_check = detail::to_lower(name_to_check);
+    }
+
+    if(local_name == name_to_check) {
+        return App::NameMatch::exact;
+    }
+    if(allow_prefix_matching_ && name_to_check.size() < local_name.size()) {
+        if(local_name.compare(0, name_to_check.size(), name_to_check) == 0) {
+            return App::NameMatch::prefix;
+        }
+    }
+    for(std::string les : aliases_) {  // NOLINT(performance-for-range-copy)
+        if(ignore_underscore_) {
+            les = detail::remove_underscore(les);
+        }
+        if(ignore_case_) {
+            les = detail::to_lower(les);
+        }
+        if(les == name_to_check) {
+            return App::NameMatch::exact;
+        }
+        if(allow_prefix_matching_ && name_to_check.size() < les.size()) {
+            if(les.compare(0, name_to_check.size(), name_to_check) == 0) {
+                return App::NameMatch::prefix;
+            }
+        }
+    }
+    return App::NameMatch::none;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::vector<std::string> App::get_groups() const {
+    std::vector<std::string> groups;
+
+    for(const Option_p &opt : options_) {
+        // Add group if it is not already in there
+        if(std::find(groups.begin(), groups.end(), opt->get_group()) == groups.end()) {
+            groups.push_back(opt->get_group());
+        }
+    }
+
+    return groups;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::vector<std::string> App::remaining(bool recurse) const {
+    std::vector<std::string> miss_list;
+    for(const std::pair<detail::Classifier, std::string> &miss : missing_) {
+        miss_list.push_back(std::get<1>(miss));
+    }
+    // Get from a subcommand that may allow extras
+    if(recurse) {
+        if(allow_extras_ == ExtrasMode::Error || allow_extras_ == ExtrasMode::Ignore) {
+            for(const auto &sub : subcommands_) {
+                if(sub->name_.empty() && !sub->missing_.empty()) {
+                    for(const std::pair<detail::Classifier, std::string> &miss : sub->missing_) {
+                        miss_list.push_back(std::get<1>(miss));
+                    }
+                }
+            }
+        }
+        // Recurse into subcommands
+
+        for(const App *sub : parsed_subcommands_) {
+            std::vector<std::string> output = sub->remaining(recurse);
+            std::copy(std::begin(output), std::end(output), std::back_inserter(miss_list));
+        }
+    }
+    return miss_list;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::vector<std::string> App::remaining_for_passthrough(bool recurse) const {
+    std::vector<std::string> miss_list = remaining(recurse);
+    std::reverse(std::begin(miss_list), std::end(miss_list));
+    return miss_list;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::size_t App::remaining_size(bool recurse) const {
+    auto remaining_options = static_cast<std::size_t>(std::count_if(
+        std::begin(missing_), std::end(missing_), [](const std::pair<detail::Classifier, std::string> &val) {
+            return val.first != detail::Classifier::POSITIONAL_MARK;
+        }));
+
+    if(recurse) {
+        for(const App_p &sub : subcommands_) {
+            remaining_options += sub->remaining_size(recurse);
+        }
+    }
+    return remaining_options;
+}
+
+CLI11_INLINE void App::_validate() const {
+    // count the number of positional only args
+    auto pcount = std::count_if(std::begin(options_), std::end(options_), [](const Option_p &opt) {
+        return opt->get_items_expected_max() >= detail::expected_max_vector_size && !opt->nonpositional();
+    });
+    if(pcount > 1) {
+        auto pcount_req = std::count_if(std::begin(options_), std::end(options_), [](const Option_p &opt) {
+            return opt->get_items_expected_max() >= detail::expected_max_vector_size && !opt->nonpositional() &&
+                   opt->get_required();
+        });
+        if(pcount - pcount_req > 1) {
+            throw InvalidError(name_);
+        }
+    }
+
+    std::size_t nameless_subs{0};
+    for(const App_p &app : subcommands_) {
+        app->_validate();
+        if(app->get_name().empty())
+            ++nameless_subs;
+    }
+
+    if(require_option_min_ > 0) {
+        if(require_option_max_ > 0) {
+            if(require_option_max_ < require_option_min_) {
+                throw(InvalidError("Required min options greater than required max options", ExitCodes::InvalidError));
+            }
+        }
+        if(require_option_min_ > (options_.size() + nameless_subs)) {
+            throw(
+                InvalidError("Required min options greater than number of available options", ExitCodes::InvalidError));
+        }
+    }
+}
+
+CLI11_INLINE void App::_configure() {
+    if(default_startup == startup_mode::enabled) {
+        disabled_ = false;
+    } else if(default_startup == startup_mode::disabled) {
+        disabled_ = true;
+    }
+    for(const App_p &app : subcommands_) {
+        if(app->has_automatic_name_) {
+            app->name_.clear();
+        }
+        if(app->name_.empty()) {
+            app->fallthrough_ = false;  // make sure fallthrough_ is false to prevent infinite loop
+            app->prefix_command_ = PrefixCommandMode::Off;
+        }
+        // make sure the parent is set to be this object in preparation for parse
+        app->parent_ = this;
+        app->_configure();
+    }
+}
+
+CLI11_INLINE void App::run_callback(bool final_mode, bool suppress_final_callback) {
+    pre_callback();
+    // in the main app if immediate_callback_ is set it runs the main callback before the used subcommands
+    if(!final_mode && parse_complete_callback_) {
+        parse_complete_callback_();
+    }
+    // run the callbacks for the received subcommands
+    for(App *subc : get_subcommands()) {
+        if(subc->parent_ == this) {
+            subc->run_callback(true, suppress_final_callback);
+        }
+    }
+    // now run callbacks for option_groups
+    for(auto &subc : subcommands_) {
+        if(subc->name_.empty() && subc->count_all() > 0) {
+            subc->run_callback(true, suppress_final_callback);
+        }
+    }
+
+    // finally run the main callback
+    if(final_callback_ && (parsed_ > 0) && (!suppress_final_callback)) {
+        if(!name_.empty() || count_all() > 0 || parent_ == nullptr) {
+            final_callback_();
+        }
+    }
+}
+
+CLI11_NODISCARD CLI11_INLINE bool App::_valid_subcommand(const std::string &current, bool ignore_used) const {
+    // Don't match if max has been reached - but still check parents
+    if(require_subcommand_max_ != 0 && parsed_subcommands_.size() >= require_subcommand_max_ &&
+       subcommand_fallthrough_) {
+        return parent_ != nullptr && parent_->_valid_subcommand(current, ignore_used);
+    }
+    auto *com = _find_subcommand(current, true, ignore_used);
+    if(com != nullptr) {
+        return true;
+    }
+    // Check parent if exists, else return false
+    if(subcommand_fallthrough_) {
+        return parent_ != nullptr && parent_->_valid_subcommand(current, ignore_used);
+    }
+    return false;
+}
+
+CLI11_NODISCARD CLI11_INLINE detail::Classifier App::_recognize(const std::string &current,
+                                                                bool ignore_used_subcommands) const {
+    std::string dummy1, dummy2;
+
+    if(current == "--")
+        return detail::Classifier::POSITIONAL_MARK;
+    if(_valid_subcommand(current, ignore_used_subcommands))
+        return detail::Classifier::SUBCOMMAND;
+    if(detail::split_long(current, dummy1, dummy2))
+        return detail::Classifier::LONG;
+    if(detail::split_short(current, dummy1, dummy2)) {
+        if((dummy1[0] >= '0' && dummy1[0] <= '9') ||
+           (dummy1[0] == '.' && !dummy2.empty() && (dummy2[0] >= '0' && dummy2[0] <= '9'))) {
+            // it looks like a number but check if it could be an option
+            if(get_option_no_throw(std::string{'-', dummy1[0]}) == nullptr) {
+                return detail::Classifier::NONE;
+            }
+        }
+        return detail::Classifier::SHORT;
+    }
+    if((allow_windows_style_options_) && (detail::split_windows_style(current, dummy1, dummy2)))
+        return detail::Classifier::WINDOWS_STYLE;
+    if((current == "++") && !name_.empty() && parent_ != nullptr)
+        return detail::Classifier::SUBCOMMAND_TERMINATOR;
+    auto dotloc = current.find_first_of('.');
+    if(dotloc != std::string::npos) {
+        auto *cm = _find_subcommand(current.substr(0, dotloc), true, ignore_used_subcommands);
+        if(cm != nullptr) {
+            auto res = cm->_recognize(current.substr(dotloc + 1), ignore_used_subcommands);
+            if(res == detail::Classifier::SUBCOMMAND) {
+                return res;
+            }
+        }
+    }
+    return detail::Classifier::NONE;
+}
+
+CLI11_INLINE bool App::_process_config_file(const std::string &config_file, bool throw_error) {
+    auto path_result = detail::check_path(config_file.c_str());
+    if(path_result == detail::path_type::file) {
+        try {
+            std::vector<ConfigItem> values = config_formatter_->from_file(config_file);
+            _parse_config(values);
+            return true;
+        } catch(const FileError &) {
+            if(throw_error) {
+                throw;
+            }
+            return false;
+        }
+    } else if(throw_error) {
+        throw FileError::Missing(config_file);
+    } else {
+        return false;
+    }
+}
+
+CLI11_INLINE void App::_process_config_file() {
+    if(config_ptr_ != nullptr) {
+        bool config_required = config_ptr_->get_required();
+        auto file_given = config_ptr_->count() > 0;
+        if(!(file_given || config_ptr_->envname_.empty())) {
+            std::string ename_string = detail::get_environment_value(config_ptr_->envname_);
+            if(!ename_string.empty()) {
+                config_ptr_->add_result(ename_string);
+            }
+        }
+        config_ptr_->run_callback();
+
+        auto config_files = config_ptr_->as<std::vector<std::string>>();
+        bool files_used{file_given};
+        if(config_files.empty() || config_files.front().empty()) {
+            if(config_required) {
+                throw FileError("config file is required but none was given");
+            }
+            return;
+        }
+        for(const auto &config_file : config_files) {
+            if(_process_config_file(config_file, config_required || file_given)) {
+                files_used = true;
+            }
+        }
+        if(!files_used) {
+            // this is done so the count shows as 0 if no callbacks were processed
+            config_ptr_->clear();
+            bool force = config_ptr_->force_callback_;
+            config_ptr_->force_callback_ = false;
+            config_ptr_->run_callback();
+            config_ptr_->force_callback_ = force;
+        }
+    }
+}
+
+CLI11_INLINE void App::_process_env() {
+    for(const Option_p &opt : options_) {
+        if(opt->count() == 0 && !opt->envname_.empty()) {
+            std::string ename_string = detail::get_environment_value(opt->envname_);
+            if(!ename_string.empty()) {
+                std::string result = ename_string;
+                result = opt->_validate(result, 0);
+                if(result.empty()) {
+                    opt->add_result(ename_string);
+                }
+            }
+        }
+    }
+
+    for(App_p &sub : subcommands_) {
+        if(sub->get_name().empty() || (sub->count_all() > 0 && !sub->parse_complete_callback_)) {
+            // only process environment variables if the callback has actually been triggered already
+            sub->_process_env();
+        }
+    }
+}
+
+CLI11_INLINE void App::_process_callbacks(CallbackPriority priority) {
+
+    for(App_p &sub : subcommands_) {
+        // process the priority option_groups first
+        if(sub->get_name().empty() && sub->parse_complete_callback_) {
+            if(sub->count_all() > 0) {
+                sub->_process_callbacks(priority);
+                if(priority == CallbackPriority::Normal) {
+                    // only run the subcommand callback at normal priority
+                    sub->run_callback();
+                }
+            }
+        }
+    }
+
+    for(const Option_p &opt : options_) {
+        if(opt->get_callback_priority() == priority) {
+            if((*opt) && !opt->get_callback_run()) {
+                opt->run_callback();
+            }
+        }
+    }
+    for(App_p &sub : subcommands_) {
+        if(!sub->parse_complete_callback_) {
+            sub->_process_callbacks(priority);
+        }
+    }
+}
+
+CLI11_INLINE void App::_process_help_flags(CallbackPriority priority, bool trigger_help, bool trigger_all_help) const {
+    const Option *help_ptr = get_help_ptr();
+    const Option *help_all_ptr = get_help_all_ptr();
+
+    if(help_ptr != nullptr && help_ptr->count() > 0 && help_ptr->get_callback_priority() == priority) {
+        trigger_help = true;
+    }
+    if(help_all_ptr != nullptr && help_all_ptr->count() > 0 && help_all_ptr->get_callback_priority() == priority) {
+        trigger_all_help = true;
+    }
+
+    // If there were parsed subcommands, call those. First subcommand wins if there are multiple ones.
+    if(!parsed_subcommands_.empty()) {
+        for(const App *sub : parsed_subcommands_) {
+            sub->_process_help_flags(priority, trigger_help, trigger_all_help);
+        }
+
+        // Only the final subcommand should call for help. All help wins over help.
+    } else if(trigger_all_help) {
+        throw CallForAllHelp();
+    } else if(trigger_help) {
+        throw CallForHelp();
+    }
+}
+
+CLI11_INLINE void App::_process_requirements() {
+    // check excludes
+    bool excluded{false};
+    std::string excluder;
+    for(const auto &opt : exclude_options_) {
+        if(opt->count() > 0) {
+            excluded = true;
+            excluder = opt->get_name();
+        }
+    }
+    for(const auto &subc : exclude_subcommands_) {
+        if(subc->count_all() > 0) {
+            excluded = true;
+            excluder = subc->get_display_name();
+        }
+    }
+    if(excluded) {
+        if(count_all() > 0) {
+            throw ExcludesError(get_display_name(), excluder);
+        }
+        // if we are excluded but didn't receive anything, just return
+        return;
+    }
+
+    // check excludes
+    bool missing_needed{false};
+    std::string missing_need;
+    for(const auto &opt : need_options_) {
+        if(opt->count() == 0) {
+            missing_needed = true;
+            missing_need = opt->get_name();
+        }
+    }
+    for(const auto &subc : need_subcommands_) {
+        if(subc->count_all() == 0) {
+            missing_needed = true;
+            missing_need = subc->get_display_name();
+        }
+    }
+    if(missing_needed) {
+        if(count_all() > 0) {
+            throw RequiresError(get_display_name(), missing_need);
+        }
+        // if we missing something but didn't have any options, just return
+        return;
+    }
+
+    std::size_t used_options = 0;
+    for(const Option_p &opt : options_) {
+
+        if(opt->count() != 0) {
+            ++used_options;
+        }
+        // Required but empty
+        if(opt->get_required() && opt->count() == 0) {
+            throw RequiredError(opt->get_name());
+        }
+        // Requires
+        for(const Option *opt_req : opt->needs_)
+            if(opt->count() > 0 && opt_req->count() == 0)
+                throw RequiresError(opt->get_name(), opt_req->get_name());
+        // Excludes
+        for(const Option *opt_ex : opt->excludes_)
+            if(opt->count() > 0 && opt_ex->count() != 0)
+                throw ExcludesError(opt->get_name(), opt_ex->get_name());
+    }
+    // check for the required number of subcommands
+    if(require_subcommand_min_ > 0) {
+        auto selected_subcommands = get_subcommands();
+        if(require_subcommand_min_ > selected_subcommands.size())
+            throw RequiredError::Subcommand(require_subcommand_min_);
+    }
+
+    // Max error cannot occur, the extra subcommand will parse as an ExtrasError or a remaining item.
+
+    // run this loop to check how many unnamed subcommands were actually used since they are considered options
+    // from the perspective of an App
+    for(App_p &sub : subcommands_) {
+        if(sub->disabled_)
+            continue;
+        if(sub->name_.empty() && sub->count_all() > 0) {
+            ++used_options;
+        }
+    }
+
+    if(require_option_min_ > used_options || (require_option_max_ > 0 && require_option_max_ < used_options)) {
+        auto option_list = detail::join(options_, [this](const Option_p &ptr) {
+            if(ptr.get() == help_ptr_ || ptr.get() == help_all_ptr_) {
+                return std::string{};
+            }
+            return ptr->get_name(false, true);
+        });
+
+        auto subc_list = get_subcommands([](App *app) { return ((app->get_name().empty()) && (!app->disabled_)); });
+        if(!subc_list.empty()) {
+            option_list += "," + detail::join(subc_list, [](const App *app) { return app->get_display_name(); });
+        }
+        throw RequiredError::Option(require_option_min_, require_option_max_, used_options, option_list);
+    }
+
+    // now process the requirements for subcommands if needed
+    for(App_p &sub : subcommands_) {
+        if(sub->disabled_)
+            continue;
+        if(sub->name_.empty() && sub->required_ == false) {
+            if(sub->count_all() == 0) {
+                if(require_option_min_ > 0 && require_option_min_ <= used_options) {
+                    continue;
+                    // if we have met the requirement and there is nothing in this option group skip checking
+                    // requirements
+                }
+                if(require_option_max_ > 0 && used_options >= require_option_min_) {
+                    continue;
+                    // if we have met the requirement and there is nothing in this option group skip checking
+                    // requirements
+                }
+            }
+        }
+        if(sub->count() > 0 || sub->name_.empty()) {
+            sub->_process_requirements();
+        }
+
+        if(sub->required_ && sub->count_all() == 0) {
+            throw(CLI::RequiredError(sub->get_display_name()));
+        }
+    }
+}
+
+CLI11_INLINE void App::_process() {
+    // help takes precedence over other potential errors and config and environment shouldn't be processed if help
+    // throws
+    _process_callbacks(CallbackPriority::FirstPreHelp);
+    _process_help_flags(CallbackPriority::First);
+    _process_callbacks(CallbackPriority::First);
+
+    std::exception_ptr config_exception;
+    try {
+        // the config file might generate a FileError but that should not be processed until later in the process
+        // to allow for help, version and other errors to generate first.
+        _process_config_file();
+
+        // process env shouldn't throw but no reason to process it if config generated an error
+        _process_env();
+    } catch(const CLI::FileError &) {
+        config_exception = std::current_exception();
+    }
+    // callbacks and requirements processing can generate exceptions which should take priority
+    // over the config file error if one exists.
+    _process_callbacks(CallbackPriority::PreRequirementsCheckPreHelp);
+    _process_help_flags(CallbackPriority::PreRequirementsCheck);
+    _process_callbacks(CallbackPriority::PreRequirementsCheck);
+
+    _process_requirements();
+
+    _process_callbacks(CallbackPriority::NormalPreHelp);
+    _process_help_flags(CallbackPriority::Normal);
+    _process_callbacks(CallbackPriority::Normal);
+
+    if(config_exception) {
+        std::rethrow_exception(config_exception);
+    }
+
+    _process_callbacks(CallbackPriority::LastPreHelp);
+    _process_help_flags(CallbackPriority::Last);
+    _process_callbacks(CallbackPriority::Last);
+}
+
+CLI11_INLINE void App::_process_extras() {
+    if(allow_extras_ == ExtrasMode::Error && prefix_command_ == PrefixCommandMode::Off) {
+        std::size_t num_left_over = remaining_size();
+        if(num_left_over > 0) {
+            throw ExtrasError(name_, remaining(false));
+        }
+    }
+    if(allow_extras_ == ExtrasMode::Error && prefix_command_ == PrefixCommandMode::SeparatorOnly) {
+        std::size_t num_left_over = remaining_size();
+        if(num_left_over > 0) {
+            if(remaining(false).front() != "--") {
+                throw ExtrasError(name_, remaining(false));
+            }
+        }
+    }
+    for(App_p &sub : subcommands_) {
+        if(sub->count() > 0)
+            sub->_process_extras();
+    }
+}
+
+CLI11_INLINE void App::increment_parsed() {
+    ++parsed_;
+    for(App_p &sub : subcommands_) {
+        if(sub->get_name().empty())
+            sub->increment_parsed();
+    }
+}
+
+CLI11_INLINE void App::_parse(std::vector<std::string> &args) {
+    increment_parsed();
+    _trigger_pre_parse(args.size());
+    bool positional_only = false;
+
+    while(!args.empty()) {
+        if(!_parse_single(args, positional_only)) {
+            break;
+        }
+    }
+
+    if(parent_ == nullptr) {
+        _process();
+
+        // Throw error if any items are left over (depending on settings)
+        _process_extras();
+        // Convert missing (pairs) to extras (string only) ready for processing in another app
+        args = remaining_for_passthrough(false);
+    } else if(parse_complete_callback_) {
+        _process_callbacks(CallbackPriority::FirstPreHelp);
+        _process_help_flags(CallbackPriority::First);
+        _process_callbacks(CallbackPriority::First);
+        _process_env();
+        _process_callbacks(CallbackPriority::PreRequirementsCheckPreHelp);
+        _process_help_flags(CallbackPriority::PreRequirementsCheck);
+        _process_callbacks(CallbackPriority::PreRequirementsCheck);
+        _process_requirements();
+        _process_callbacks(CallbackPriority::NormalPreHelp);
+        _process_help_flags(CallbackPriority::Normal);
+        _process_callbacks(CallbackPriority::Normal);
+        _process_callbacks(CallbackPriority::LastPreHelp);
+        _process_help_flags(CallbackPriority::Last);
+        _process_callbacks(CallbackPriority::Last);
+        run_callback(false, true);
+    }
+}
+
+CLI11_INLINE void App::_parse(std::vector<std::string> &&args) {
+    // this can only be called by the top level in which case parent == nullptr by definition
+    // operation is simplified
+    increment_parsed();
+    _trigger_pre_parse(args.size());
+    bool positional_only = false;
+
+    while(!args.empty()) {
+        _parse_single(args, positional_only);
+    }
+    _process();
+
+    // Throw error if any items are left over (depending on settings)
+    _process_extras();
+}
+
+CLI11_INLINE void App::_parse_stream(std::istream &input) {
+    auto values = config_formatter_->from_config(input);
+    _parse_config(values);
+    increment_parsed();
+    _trigger_pre_parse(values.size());
+    _process();
+
+    // Throw error if any items are left over (depending on settings)
+    _process_extras();
+}
+
+CLI11_INLINE void App::_parse_config(const std::vector<ConfigItem> &args) {
+    for(const ConfigItem &item : args) {
+        if(!_parse_single_config(item) && allow_config_extras_ == ConfigExtrasMode::Error)
+            throw ConfigError::Extras(item.fullname());
+    }
+}
+
+CLI11_INLINE bool
+App::_add_flag_like_result(Option *op, const ConfigItem &item, const std::vector<std::string> &inputs) {
+    if(item.inputs.size() <= 1) {
+        // Flag parsing
+        auto res = config_formatter_->to_flag(item);
+        bool converted{false};
+        if(op->get_disable_flag_override()) {
+            auto val = detail::to_flag_value(res);
+            if(val == 1) {
+                res = op->get_flag_value(item.name, "{}");
+                converted = true;
+            }
+        }
+
+        if(!converted) {
+            errno = 0;
+            if(res != "{}" || op->get_expected_max() <= 1) {
+                res = op->get_flag_value(item.name, res);
+            }
+        }
+
+        op->add_result(res);
+        return true;
+    }
+    if(static_cast<int>(inputs.size()) > op->get_items_expected_max() &&
+       op->get_multi_option_policy() != MultiOptionPolicy::TakeAll &&
+       op->get_multi_option_policy() != MultiOptionPolicy::Join) {
+        if(op->get_items_expected_max() > 1) {
+            throw ArgumentMismatch::AtMost(item.fullname(), op->get_items_expected_max(), inputs.size());
+        }
+
+        if(!op->get_disable_flag_override()) {
+            throw ConversionError::TooManyInputsFlag(item.fullname());
+        }
+        // if the disable flag override is set then we must have the flag values match a known flag value
+        // this is true regardless of the output value, so an array input is possible and must be accounted for
+        for(const auto &res : inputs) {
+            bool valid_value{false};
+            if(op->default_flag_values_.empty()) {
+                if(res == "true" || res == "false" || res == "1" || res == "0") {
+                    valid_value = true;
+                }
+            } else {
+                for(const auto &valid_res : op->default_flag_values_) {
+                    if(valid_res.second == res) {
+                        valid_value = true;
+                        break;
+                    }
+                }
+            }
+
+            if(valid_value) {
+                op->add_result(res);
+            } else {
+                throw InvalidError("invalid flag argument given");
+            }
+        }
+        return true;
+    }
+    return false;
+}
+
+CLI11_INLINE bool App::_parse_single_config(const ConfigItem &item, std::size_t level) {
+
+    if(level < item.parents.size()) {
+        auto *subcom = get_subcommand_no_throw(item.parents.at(level));
+        return (subcom != nullptr) ? subcom->_parse_single_config(item, level + 1) : false;
+    }
+    // check for section open
+    if(item.name == "++") {
+        if(configurable_) {
+            increment_parsed();
+            _trigger_pre_parse(2);
+            if(parent_ != nullptr) {
+                parent_->parsed_subcommands_.push_back(this);
+            }
+        }
+        return true;
+    }
+    // check for section close
+    if(item.name == "--") {
+        if(configurable_ && parse_complete_callback_) {
+            _process_callbacks(CallbackPriority::FirstPreHelp);
+            _process_callbacks(CallbackPriority::First);
+            _process_callbacks(CallbackPriority::PreRequirementsCheckPreHelp);
+            _process_callbacks(CallbackPriority::PreRequirementsCheck);
+            _process_requirements();
+            _process_callbacks(CallbackPriority::NormalPreHelp);
+            _process_callbacks(CallbackPriority::Normal);
+            _process_callbacks(CallbackPriority::LastPreHelp);
+            _process_callbacks(CallbackPriority::Last);
+            run_callback();
+        }
+        return true;
+    }
+    Option *op = get_option_no_throw("--" + item.name);
+    if(op == nullptr) {
+        if(item.name.size() == 1) {
+            op = get_option_no_throw("-" + item.name);
+        }
+        if(op == nullptr) {
+            op = get_option_no_throw(item.name);
+        }
+    } else if(!op->get_configurable()) {
+        if(item.name.size() == 1) {
+            auto *testop = get_option_no_throw("-" + item.name);
+            if(testop != nullptr && testop->get_configurable()) {
+                op = testop;
+            }
+        }
+    }
+    if(op == nullptr || !op->get_configurable()) {
+        std::string iname = item.name;
+        auto options = get_options([iname](const CLI::Option *opt) {
+            return (opt->get_configurable() &&
+                    (opt->check_name(iname) || opt->check_lname(iname) || opt->check_sname(iname)));
+        });
+        if(!options.empty()) {
+            op = options[0];
+        }
+    }
+    if(op == nullptr) {
+        // If the option was not present
+        if(get_allow_config_extras() == config_extras_mode::capture) {
+            // Should we worry about classifying the extras properly?
+            missing_.emplace_back(detail::Classifier::NONE, item.fullname());
+            for(const auto &input : item.inputs) {
+                missing_.emplace_back(detail::Classifier::NONE, input);
+            }
+        }
+        return false;
+    }
+
+    if(!op->get_configurable()) {
+        if(get_allow_config_extras() == config_extras_mode::ignore_all) {
+            return false;
+        }
+        throw ConfigError::NotConfigurable(item.fullname());
+    }
+    if(op->empty()) {
+        std::vector<std::string> buffer;  // a buffer to use for copying and modifying inputs in a few cases
+        bool useBuffer{false};
+        if(item.multiline) {
+            if(!op->get_inject_separator()) {
+                buffer = item.inputs;
+                buffer.erase(std::remove(buffer.begin(), buffer.end(), "%%"), buffer.end());
+                useBuffer = true;
+            }
+        }
+        const std::vector<std::string> &inputs = (useBuffer) ? buffer : item.inputs;
+        if(op->get_expected_min() == 0) {
+            if(_add_flag_like_result(op, item, inputs)) {
+                return true;
+            }
+        }
+        op->add_result(inputs);
+        op->run_callback();
+    }
+
+    return true;
+}
+
+CLI11_INLINE bool App::_parse_single(std::vector<std::string> &args, bool &positional_only) {
+    bool retval = true;
+    detail::Classifier classifier = positional_only ? detail::Classifier::NONE : _recognize(args.back());
+    switch(classifier) {
+    case detail::Classifier::POSITIONAL_MARK:
+        args.pop_back();
+        positional_only = true;
+        if(get_prefix_command()) {
+            // don't care about extras mode here
+            missing_.emplace_back(classifier, "--");
+            while(!args.empty()) {
+                missing_.emplace_back(detail::Classifier::NONE, args.back());
+                args.pop_back();
+            }
+        } else if((!_has_remaining_positionals()) && (parent_ != nullptr)) {
+            retval = false;
+        } else {
+            _move_to_missing(classifier, "--");
+        }
+        break;
+    case detail::Classifier::SUBCOMMAND_TERMINATOR:
+        // treat this like a positional mark if in the parent app
+        args.pop_back();
+        retval = false;
+        break;
+    case detail::Classifier::SUBCOMMAND:
+        retval = _parse_subcommand(args);
+        break;
+    case detail::Classifier::LONG:
+    case detail::Classifier::SHORT:
+    case detail::Classifier::WINDOWS_STYLE:
+        // If already parsed a subcommand, don't accept options_
+        retval = _parse_arg(args, classifier, false);
+        break;
+    case detail::Classifier::NONE:
+        // Probably a positional or something for a parent (sub)command
+        retval = _parse_positional(args, false);
+        if(retval && positionals_at_end_) {
+            positional_only = true;
+        }
+        break;
+        // LCOV_EXCL_START
+    default:
+        throw HorribleError("unrecognized classifier (you should not see this!)");
+        // LCOV_EXCL_STOP
+    }
+    return retval;
+}
+
+CLI11_NODISCARD CLI11_INLINE std::size_t App::_count_remaining_positionals(bool required_only) const {
+    std::size_t retval = 0;
+    for(const Option_p &opt : options_) {
+        if(opt->get_positional() && (!required_only || opt->get_required())) {
+            if(opt->get_items_expected_min() > 0 && static_cast<int>(opt->count()) < opt->get_items_expected_min()) {
+                retval += static_cast<std::size_t>(opt->get_items_expected_min()) - opt->count();
+            }
+        }
+    }
+    return retval;
+}
+
+CLI11_NODISCARD CLI11_INLINE bool App::_has_remaining_positionals() const {
+    for(const Option_p &opt : options_) {
+        if(opt->get_positional() && ((static_cast<int>(opt->count()) < opt->get_items_expected_min()))) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+CLI11_INLINE bool App::_parse_positional(std::vector<std::string> &args, bool haltOnSubcommand) {
+
+    const std::string &positional = args.back();
+    Option *posOpt{nullptr};
+
+    if(positionals_at_end_) {
+        // deal with the case of required arguments at the end which should take precedence over other arguments
+        auto arg_rem = args.size();
+        auto remreq = _count_remaining_positionals(true);
+        if(arg_rem <= remreq) {
+            for(const Option_p &opt : options_) {
+                if(opt->get_positional() && opt->required_) {
+                    if(static_cast<int>(opt->count()) < opt->get_items_expected_min()) {
+                        if(validate_positionals_) {
+                            std::string pos = positional;
+                            pos = opt->_validate(pos, 0);
+                            if(!pos.empty()) {
+                                continue;
+                            }
+                        }
+                        posOpt = opt.get();
+                        break;
+                    }
+                }
+            }
+        }
+    }
+    if(posOpt == nullptr) {
+        for(const Option_p &opt : options_) {
+            // Eat options, one by one, until done
+            if(opt->get_positional() &&
+               (static_cast<int>(opt->count()) < opt->get_items_expected_max() || opt->get_allow_extra_args())) {
+                if(validate_positionals_) {
+                    std::string pos = positional;
+                    pos = opt->_validate(pos, 0);
+                    if(!pos.empty()) {
+                        continue;
+                    }
+                }
+                posOpt = opt.get();
+                break;
+            }
+        }
+    }
+    if(posOpt != nullptr) {
+        parse_order_.push_back(posOpt);
+        if(posOpt->get_inject_separator()) {
+            if(!posOpt->results().empty() && !posOpt->results().back().empty()) {
+                posOpt->add_result(std::string{});
+            }
+        }
+        results_t prev;
+        if(posOpt->get_trigger_on_parse() && posOpt->current_option_state_ == Option::option_state::callback_run) {
+            prev = posOpt->results();
+            posOpt->clear();
+        }
+        if(posOpt->get_expected_min() == 0) {
+            ConfigItem item;
+            item.name = posOpt->pname_;
+            item.inputs.push_back(positional);
+            // input is singular guaranteed to return true in that case
+            _add_flag_like_result(posOpt, item, item.inputs);
+        } else {
+            posOpt->add_result(positional);
+        }
+
+        if(posOpt->get_trigger_on_parse()) {
+            if(!posOpt->empty()) {
+                posOpt->run_callback();
+            } else {
+                if(!prev.empty()) {
+                    posOpt->add_result(prev);
+                }
+            }
+        }
+
+        args.pop_back();
+        return true;
+    }
+
+    for(auto &subc : subcommands_) {
+        if((subc->name_.empty()) && (!subc->disabled_)) {
+            if(subc->_parse_positional(args, false)) {
+                if(!subc->pre_parse_called_) {
+                    subc->_trigger_pre_parse(args.size());
+                }
+                return true;
+            }
+        }
+    }
+    // let the parent deal with it if possible
+    if(parent_ != nullptr && fallthrough_) {
+        return _get_fallthrough_parent()->_parse_positional(args, static_cast<bool>(parse_complete_callback_));
+    }
+    /// Try to find a local subcommand that is repeated
+    auto *com = _find_subcommand(args.back(), true, false);
+    if(com != nullptr && (require_subcommand_max_ == 0 || require_subcommand_max_ > parsed_subcommands_.size())) {
+        if(haltOnSubcommand) {
+            return false;
+        }
+        args.pop_back();
+        com->_parse(args);
+        return true;
+    }
+    if(subcommand_fallthrough_) {
+        /// now try one last gasp at subcommands that have been executed before, go to root app and try to find a
+        /// subcommand in a broader way, if one exists let the parent deal with it
+        auto *parent_app = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
+        com = parent_app->_find_subcommand(args.back(), true, false);
+        if(com != nullptr && (com->parent_->require_subcommand_max_ == 0 ||
+                              com->parent_->require_subcommand_max_ > com->parent_->parsed_subcommands_.size())) {
+            return false;
+        }
+    }
+    if(positionals_at_end_) {
+        std::vector<std::string> rargs;
+        rargs.resize(args.size());
+        std::reverse_copy(args.begin(), args.end(), rargs.begin());
+        throw CLI::ExtrasError(name_, rargs);
+    }
+    /// If this is an option group don't deal with it
+    if(parent_ != nullptr && name_.empty()) {
+        return false;
+    }
+    /// We are out of other options this goes to missing
+    _move_to_missing(detail::Classifier::NONE, positional);
+    args.pop_back();
+    if(get_prefix_command()) {
+        while(!args.empty()) {
+            missing_.emplace_back(detail::Classifier::NONE, args.back());
+            args.pop_back();
+        }
+    }
+
+    return true;
+}
+
+CLI11_NODISCARD CLI11_INLINE App *
+App::_find_subcommand(const std::string &subc_name, bool ignore_disabled, bool ignore_used) const noexcept {
+    App *bcom{nullptr};
+    for(const App_p &com : subcommands_) {
+        if(com->disabled_ && ignore_disabled)
+            continue;
+        if(com->get_name().empty()) {
+            auto *subc = com->_find_subcommand(subc_name, ignore_disabled, ignore_used);
+            if(subc != nullptr) {
+                if(bcom != nullptr) {
+                    return nullptr;
+                }
+                bcom = subc;
+                if(!allow_prefix_matching_) {
+                    return bcom;
+                }
+            }
+        }
+        auto res = com->check_name_detail(subc_name);
+        if(res != NameMatch::none) {
+            if((!*com) || !ignore_used) {
+                if(res == NameMatch::exact) {
+                    return com.get();
+                }
+                if(bcom != nullptr) {
+                    return nullptr;
+                }
+                bcom = com.get();
+                if(!allow_prefix_matching_) {
+                    return bcom;
+                }
+            }
+        }
+    }
+    return bcom;
+}
+
+CLI11_INLINE bool App::_parse_subcommand(std::vector<std::string> &args) {
+    if(_count_remaining_positionals(/* required */ true) > 0) {
+        _parse_positional(args, false);
+        return true;
+    }
+    auto *com = _find_subcommand(args.back(), true, true);
+    if(com == nullptr) {
+        // the main way to get here is using .notation
+        auto dotloc = args.back().find_first_of('.');
+        if(dotloc != std::string::npos) {
+            com = _find_subcommand(args.back().substr(0, dotloc), true, true);
+            if(com != nullptr) {
+                args.back() = args.back().substr(dotloc + 1);
+                args.push_back(com->get_display_name());
+            }
+        }
+    }
+    if(com != nullptr) {
+        args.pop_back();
+        if(!com->silent_) {
+            parsed_subcommands_.push_back(com);
+        }
+        com->_parse(args);
+        auto *parent_app = com->parent_;
+        while(parent_app != this) {
+            parent_app->_trigger_pre_parse(args.size());
+            if(!com->silent_) {
+                parent_app->parsed_subcommands_.push_back(com);
+            }
+            parent_app = parent_app->parent_;
+        }
+        return true;
+    }
+
+    if(parent_ == nullptr)
+        throw HorribleError("Subcommand " + args.back() + " missing");
+    return false;
+}
+
+CLI11_INLINE bool
+App::_parse_arg(std::vector<std::string> &args, detail::Classifier current_type, bool local_processing_only) {
+
+    std::string current = args.back();
+
+    std::string arg_name;
+    std::string value;
+    std::string rest;
+
+    switch(current_type) {
+    case detail::Classifier::LONG:
+        if(!detail::split_long(current, arg_name, value))
+            throw HorribleError("Long parsed but missing (you should not see this):" + args.back());
+        break;
+    case detail::Classifier::SHORT:
+        if(!detail::split_short(current, arg_name, rest))
+            throw HorribleError("Short parsed but missing! You should not see this");
+        break;
+    case detail::Classifier::WINDOWS_STYLE:
+        if(!detail::split_windows_style(current, arg_name, value))
+            throw HorribleError("windows option parsed but missing! You should not see this");
+        break;
+    case detail::Classifier::SUBCOMMAND:
+    case detail::Classifier::SUBCOMMAND_TERMINATOR:
+    case detail::Classifier::POSITIONAL_MARK:
+    case detail::Classifier::NONE:
+    default:
+        throw HorribleError("parsing got called with invalid option! You should not see this");
+    }
+
+    auto op_ptr = std::find_if(std::begin(options_), std::end(options_), [arg_name, current_type](const Option_p &opt) {
+        if(current_type == detail::Classifier::LONG)
+            return opt->check_lname(arg_name);
+        if(current_type == detail::Classifier::SHORT)
+            return opt->check_sname(arg_name);
+        // this will only get called for detail::Classifier::WINDOWS_STYLE
+        return opt->check_lname(arg_name) || opt->check_sname(arg_name);
+    });
+
+    // Option not found
+    while(op_ptr == std::end(options_)) {
+        // using while so we can break
+        for(auto &subc : subcommands_) {
+            if(subc->name_.empty() && !subc->disabled_) {
+                if(subc->_parse_arg(args, current_type, local_processing_only)) {
+                    if(!subc->pre_parse_called_) {
+                        subc->_trigger_pre_parse(args.size());
+                    }
+                    return true;
+                }
+            }
+        }
+        if(allow_non_standard_options_ && current_type == detail::Classifier::SHORT && current.size() > 2) {
+            std::string narg_name;
+            std::string nvalue;
+            detail::split_long(std::string{'-'} + current, narg_name, nvalue);
+            op_ptr = std::find_if(std::begin(options_), std::end(options_), [narg_name](const Option_p &opt) {
+                return opt->check_sname(narg_name);
+            });
+            if(op_ptr != std::end(options_)) {
+                arg_name = narg_name;
+                value = nvalue;
+                rest.clear();
+                break;
+            }
+        }
+
+        // don't capture missing if this is a nameless subcommand and nameless subcommands can't fallthrough
+        if(parent_ != nullptr && name_.empty()) {
+            return false;
+        }
+
+        // now check for '.' notation of subcommands
+        auto dotloc = arg_name.find_first_of('.', 1);
+        if(dotloc != std::string::npos && dotloc < arg_name.size() - 1) {
+            // using dot notation is equivalent to single argument subcommand
+            auto *sub = _find_subcommand(arg_name.substr(0, dotloc), true, false);
+            if(sub != nullptr) {
+                std::string v = args.back();
+                args.pop_back();
+                arg_name = arg_name.substr(dotloc + 1);
+                if(arg_name.size() > 1) {
+                    args.push_back(std::string("--") + v.substr(dotloc + 3));
+                    current_type = detail::Classifier::LONG;
+                } else {
+                    auto nval = v.substr(dotloc + 2);
+                    nval.front() = '-';
+                    if(nval.size() > 2) {
+                        // '=' not allowed in short form arguments
+                        args.push_back(nval.substr(3));
+                        nval.resize(2);
+                    }
+                    args.push_back(nval);
+                    current_type = detail::Classifier::SHORT;
+                }
+                std::string dummy1, dummy2;
+                bool val = false;
+                if((current_type == detail::Classifier::SHORT && detail::valid_first_char(args.back()[1])) ||
+                   detail::split_long(args.back(), dummy1, dummy2)) {
+                    val = sub->_parse_arg(args, current_type, true);
+                }
+
+                if(val) {
+                    if(!sub->silent_) {
+                        parsed_subcommands_.push_back(sub);
+                    }
+                    // deal with preparsing
+                    increment_parsed();
+                    _trigger_pre_parse(args.size());
+                    // run the parse complete callback since the subcommand processing is now complete
+                    if(sub->parse_complete_callback_) {
+                        sub->_process_callbacks(CallbackPriority::FirstPreHelp);
+                        sub->_process_help_flags(CallbackPriority::First);
+                        sub->_process_callbacks(CallbackPriority::First);
+                        sub->_process_env();
+                        sub->_process_callbacks(CallbackPriority::PreRequirementsCheckPreHelp);
+                        sub->_process_help_flags(CallbackPriority::PreRequirementsCheck);
+                        sub->_process_callbacks(CallbackPriority::PreRequirementsCheck);
+                        sub->_process_requirements();
+                        sub->_process_callbacks(CallbackPriority::NormalPreHelp);
+                        sub->_process_help_flags(CallbackPriority::Normal);
+                        sub->_process_callbacks(CallbackPriority::Normal);
+                        sub->_process_callbacks(CallbackPriority::LastPreHelp);
+                        sub->_process_help_flags(CallbackPriority::Last);
+                        sub->_process_callbacks(CallbackPriority::Last);
+                        sub->run_callback(false, true);
+                    }
+                    return true;
+                }
+                args.pop_back();
+                args.push_back(v);
+            }
+        }
+        if(local_processing_only) {
+            return false;
+        }
+        // If a subcommand, try the main command
+        if(parent_ != nullptr && fallthrough_)
+            return _get_fallthrough_parent()->_parse_arg(args, current_type, false);
+
+        // Otherwise, add to missing
+        args.pop_back();
+        _move_to_missing(current_type, current);
+        if(get_prefix_command_mode() == PrefixCommandMode::On) {
+            while(!args.empty()) {
+                missing_.emplace_back(detail::Classifier::NONE, args.back());
+                args.pop_back();
+            }
+        } else if(allow_extras_ == ExtrasMode::AssumeSingleArgument) {
+            if(!args.empty() && _recognize(args.back(), false) == detail::Classifier::NONE) {
+                _move_to_missing(detail::Classifier::NONE, args.back());
+                args.pop_back();
+            }
+        } else if(allow_extras_ == ExtrasMode::AssumeMultipleArguments) {
+            while(!args.empty() && _recognize(args.back(), false) == detail::Classifier::NONE) {
+                _move_to_missing(detail::Classifier::NONE, args.back());
+                args.pop_back();
+            }
+        }
+        return true;
+    }
+
+    args.pop_back();
+
+    // Get a reference to the pointer to make syntax bearable
+    Option_p &op = *op_ptr;
+    /// if we require a separator add it here
+    if(op->get_inject_separator()) {
+        if(!op->results().empty() && !op->results().back().empty()) {
+            op->add_result(std::string{});
+        }
+    }
+    if(op->get_trigger_on_parse() && op->current_option_state_ == Option::option_state::callback_run) {
+        op->clear();
+    }
+    int min_num = (std::min)(op->get_type_size_min(), op->get_items_expected_min());
+    int max_num = op->get_items_expected_max();
+    // check container like options to limit the argument size to a single type if the allow_extra_flags argument is
+    // set. 16 is somewhat arbitrary (needs to be at least 4)
+    if(max_num >= detail::expected_max_vector_size / 16 && !op->get_allow_extra_args()) {
+        auto tmax = op->get_type_size_max();
+        max_num = detail::checked_multiply(tmax, op->get_expected_min()) ? tmax : detail::expected_max_vector_size;
+    }
+    // Make sure we always eat the minimum for unlimited vectors
+    int collected = 0;     // total number of arguments collected
+    int result_count = 0;  // local variable for number of results in a single arg string
+    // deal with purely flag like things
+    if(max_num == 0) {
+        auto res = op->get_flag_value(arg_name, value);
+        op->add_result(res);
+        parse_order_.push_back(op.get());
+    } else if(!value.empty()) {  // --this=value
+        op->add_result(value, result_count);
+        parse_order_.push_back(op.get());
+        collected += result_count;
+        // -Trest
+    } else if(!rest.empty()) {
+        op->add_result(rest, result_count);
+        parse_order_.push_back(op.get());
+        rest = "";
+        collected += result_count;
+    }
+
+    // gather the minimum number of arguments
+    while(min_num > collected && !args.empty()) {
+        std::string current_ = args.back();
+        args.pop_back();
+        op->add_result(current_, result_count);
+        parse_order_.push_back(op.get());
+        collected += result_count;
+    }
+
+    if(min_num > collected) {  // if we have run out of arguments and the minimum was not met
+        throw ArgumentMismatch::TypedAtLeast(op->get_name(), min_num, op->get_type_name());
+    }
+
+    // now check for optional arguments
+    if(max_num > collected || op->get_allow_extra_args()) {  // we allow optional arguments
+        auto remreqpos = _count_remaining_positionals(true);
+        // we have met the minimum now optionally check up to the maximum
+        while((collected < max_num || op->get_allow_extra_args()) && !args.empty() &&
+              _recognize(args.back(), false) == detail::Classifier::NONE) {
+            // If any required positionals remain, don't keep eating
+            if(remreqpos >= args.size()) {
+                break;
+            }
+            if(validate_optional_arguments_) {
+                std::string arg = args.back();
+                arg = op->_validate(arg, 0);
+                if(!arg.empty()) {
+                    break;
+                }
+            }
+            op->add_result(args.back(), result_count);
+            parse_order_.push_back(op.get());
+            args.pop_back();
+            collected += result_count;
+        }
+
+        // Allow -- to end an unlimited list and "eat" it
+        if(!args.empty() && _recognize(args.back()) == detail::Classifier::POSITIONAL_MARK)
+            args.pop_back();
+        // optional flag that didn't receive anything now get the default value
+        if(min_num == 0 && max_num > 0 && collected == 0) {
+            auto res = op->get_flag_value(arg_name, std::string{});
+            op->add_result(res);
+            parse_order_.push_back(op.get());
+        }
+    }
+    // if we only partially completed a type then add an empty string if allowed for later processing
+    if(min_num > 0 && (collected % op->get_type_size_max()) != 0) {
+        if(op->get_type_size_max() != op->get_type_size_min()) {
+            op->add_result(std::string{});
+        } else {
+            throw ArgumentMismatch::PartialType(op->get_name(), op->get_type_size_min(), op->get_type_name());
+        }
+    }
+    if(op->get_trigger_on_parse()) {
+        op->run_callback();
+    }
+    if(!rest.empty()) {
+        rest = "-" + rest;
+        args.push_back(rest);
+    }
+    return true;
+}
+
+CLI11_INLINE void App::_trigger_pre_parse(std::size_t remaining_args) {
+    if(!pre_parse_called_) {
+        pre_parse_called_ = true;
+        if(pre_parse_callback_) {
+            pre_parse_callback_(remaining_args);
+        }
+    } else if(immediate_callback_) {
+        if(!name_.empty()) {
+            auto pcnt = parsed_;
+            missing_t extras = std::move(missing_);
+            clear();
+            parsed_ = pcnt;
+            pre_parse_called_ = true;
+            missing_ = std::move(extras);
+        }
+    }
+}
+
+CLI11_INLINE App *App::_get_fallthrough_parent() noexcept {
+    if(parent_ == nullptr) {
+        return nullptr;
+    }
+    auto *fallthrough_parent = parent_;
+    while((fallthrough_parent->parent_ != nullptr) && (fallthrough_parent->get_name().empty())) {
+        fallthrough_parent = fallthrough_parent->parent_;
+    }
+    return fallthrough_parent;
+}
+
+CLI11_INLINE const App *App::_get_fallthrough_parent() const noexcept {
+    if(parent_ == nullptr) {
+        return nullptr;
+    }
+    const auto *fallthrough_parent = parent_;
+    while((fallthrough_parent->parent_ != nullptr) && (fallthrough_parent->get_name().empty())) {
+        fallthrough_parent = fallthrough_parent->parent_;
+    }
+    return fallthrough_parent;
+}
+
+CLI11_NODISCARD CLI11_INLINE const std::string &App::_compare_subcommand_names(const App &subcom,
+                                                                               const App &base) const {
+    static const std::string estring;
+    if(subcom.disabled_) {
+        return estring;
+    }
+    for(const auto &subc : base.subcommands_) {
+        if(subc.get() != &subcom) {
+            if(subc->disabled_) {
+                continue;
+            }
+            if(!subcom.get_name().empty()) {
+                if(subc->check_name(subcom.get_name())) {
+                    return subcom.get_name();
+                }
+            }
+            if(!subc->get_name().empty()) {
+                if(subcom.check_name(subc->get_name())) {
+                    return subc->get_name();
+                }
+            }
+            for(const auto &les : subcom.aliases_) {
+                if(subc->check_name(les)) {
+                    return les;
+                }
+            }
+            // this loop is needed in case of ignore_underscore or ignore_case on one but not the other
+            for(const auto &les : subc->aliases_) {
+                if(subcom.check_name(les)) {
+                    return les;
+                }
+            }
+            // if the subcommand is an option group we need to check deeper
+            if(subc->get_name().empty()) {
+                const auto &cmpres = _compare_subcommand_names(subcom, *subc);
+                if(!cmpres.empty()) {
+                    return cmpres;
+                }
+            }
+            // if the test subcommand is an option group we need to check deeper
+            if(subcom.get_name().empty()) {
+                const auto &cmpres = _compare_subcommand_names(*subc, subcom);
+                if(!cmpres.empty()) {
+                    return cmpres;
+                }
+            }
+        }
+    }
+    return estring;
+}
+
+inline bool capture_extras(ExtrasMode mode) {
+    return mode == ExtrasMode::Capture || mode == ExtrasMode::AssumeSingleArgument ||
+           mode == ExtrasMode::AssumeMultipleArguments;
+}
+CLI11_INLINE void App::_move_to_missing(detail::Classifier val_type, const std::string &val) {
+    if(allow_extras_ == ExtrasMode::ErrorImmediately) {
+        throw ExtrasError(name_, std::vector<std::string>{val});
+    }
+    if(capture_extras(allow_extras_) || subcommands_.empty() || get_prefix_command()) {
+        if(allow_extras_ != ExtrasMode::Ignore) {
+            missing_.emplace_back(val_type, val);
+        }
+        return;
+    }
+    // allow extra arguments to be placed in an option group if it is allowed there
+    for(auto &subc : subcommands_) {
+        if(subc->name_.empty() && capture_extras(subc->allow_extras_)) {
+            subc->missing_.emplace_back(val_type, val);
+            return;
+        }
+    }
+    if(allow_extras_ != ExtrasMode::Ignore) {
+        // if we haven't found any place to put them yet put them in missing
+        missing_.emplace_back(val_type, val);
+    }
+}
+
+CLI11_INLINE void App::_move_option(Option *opt, App *app) {
+    if(opt == nullptr) {
+        throw OptionNotFound("the option is NULL");
+    }
+    // verify that the give app is actually a subcommand
+    bool found = false;
+    for(auto &subc : subcommands_) {
+        if(app == subc.get()) {
+            found = true;
+        }
+    }
+    if(!found) {
+        throw OptionNotFound("The Given app is not a subcommand");
+    }
+
+    if((help_ptr_ == opt) || (help_all_ptr_ == opt))
+        throw OptionAlreadyAdded("cannot move help options");
+
+    if(config_ptr_ == opt)
+        throw OptionAlreadyAdded("cannot move config file options");
+
+    auto iterator =
+        std::find_if(std::begin(options_), std::end(options_), [opt](const Option_p &v) { return v.get() == opt; });
+    if(iterator != std::end(options_)) {
+        const auto &opt_p = *iterator;
+        if(std::find_if(std::begin(app->options_), std::end(app->options_), [&opt_p](const Option_p &v) {
+               return (*v == *opt_p);
+           }) == std::end(app->options_)) {
+            // only erase after the insertion was successful
+            app->options_.push_back(std::move(*iterator));
+            options_.erase(iterator);
+        } else {
+            throw OptionAlreadyAdded("option was not located: " + opt->get_name());
+        }
+    } else {
+        throw OptionNotFound("could not locate the given Option");
+    }
+}
+
+CLI11_INLINE void TriggerOn(App *trigger_app, App *app_to_enable) {
+    app_to_enable->enabled_by_default(false);
+    app_to_enable->disabled_by_default();
+    trigger_app->preparse_callback([app_to_enable](std::size_t) { app_to_enable->disabled(false); });
+}
+
+CLI11_INLINE void TriggerOn(App *trigger_app, std::vector<App *> apps_to_enable) {
+    for(auto &app : apps_to_enable) {
+        app->enabled_by_default(false);
+        app->disabled_by_default();
+    }
+
+    trigger_app->preparse_callback([apps_to_enable](std::size_t) {
+        for(const auto &app : apps_to_enable) {
+            app->disabled(false);
+        }
+    });
+}
+
+CLI11_INLINE void TriggerOff(App *trigger_app, App *app_to_enable) {
+    app_to_enable->disabled_by_default(false);
+    app_to_enable->enabled_by_default();
+    trigger_app->preparse_callback([app_to_enable](std::size_t) { app_to_enable->disabled(); });
+}
+
+CLI11_INLINE void TriggerOff(App *trigger_app, std::vector<App *> apps_to_enable) {
+    for(auto &app : apps_to_enable) {
+        app->disabled_by_default(false);
+        app->enabled_by_default();
+    }
+
+    trigger_app->preparse_callback([apps_to_enable](std::size_t) {
+        for(const auto &app : apps_to_enable) {
+            app->disabled();
+        }
+    });
+}
+
+CLI11_INLINE void deprecate_option(Option *opt, const std::string &replacement) {
+    Validator deprecate_warning{[opt, replacement](std::string &) {
+                                    std::cout << opt->get_name() << " is deprecated please use '" << replacement
+                                              << "' instead\n";
+                                    return std::string();
+                                },
+                                "DEPRECATED"};
+    deprecate_warning.application_index(0);
+    opt->check(deprecate_warning);
+    if(!replacement.empty()) {
+        opt->description(opt->get_description() + " DEPRECATED: please use '" + replacement + "' instead");
+    }
+}
+
+CLI11_INLINE void retire_option(App *app, Option *opt) {
+    App temp;
+    auto *option_copy = temp.add_option(opt->get_name(false, true))
+                            ->type_size(opt->get_type_size_min(), opt->get_type_size_max())
+                            ->expected(opt->get_expected_min(), opt->get_expected_max())
+                            ->allow_extra_args(opt->get_allow_extra_args());
+
+    app->remove_option(opt);
+    auto *opt2 = app->add_option(option_copy->get_name(false, true), "option has been retired and has no effect");
+    opt2->type_name("RETIRED")
+        ->default_str("RETIRED")
+        ->type_size(option_copy->get_type_size_min(), option_copy->get_type_size_max())
+        ->expected(option_copy->get_expected_min(), option_copy->get_expected_max())
+        ->allow_extra_args(option_copy->get_allow_extra_args());
+
+    // LCOV_EXCL_START
+    // something odd with coverage on new compilers
+    Validator retired_warning{[opt2](std::string &) {
+                                  std::cout << "WARNING " << opt2->get_name() << " is retired and has no effect\n";
+                                  return std::string();
+                              },
+                              ""};
+    // LCOV_EXCL_STOP
+    retired_warning.application_index(0);
+    opt2->check(retired_warning);
+}
+
+CLI11_INLINE void retire_option(App &app, Option *opt) { retire_option(&app, opt); }
+
+CLI11_INLINE void retire_option(App *app, const std::string &option_name) {
+
+    auto *opt = app->get_option_no_throw(option_name);
+    if(opt != nullptr) {
+        retire_option(app, opt);
+        return;
+    }
+    auto *opt2 = app->add_option(option_name, "option has been retired and has no effect")
+                     ->type_name("RETIRED")
+                     ->expected(0, 1)
+                     ->default_str("RETIRED");
+    // LCOV_EXCL_START
+    // something odd with coverage on new compilers
+    Validator retired_warning{[opt2](std::string &) {
+                                  std::cout << "WARNING " << opt2->get_name() << " is retired and has no effect\n";
+                                  return std::string();
+                              },
+                              ""};
+    // LCOV_EXCL_STOP
+    retired_warning.application_index(0);
+    opt2->check(retired_warning);
+}
+
+CLI11_INLINE void retire_option(App &app, const std::string &option_name) { retire_option(&app, option_name); }
+
+namespace FailureMessage {
+
+CLI11_INLINE std::string simple(const App *app, const Error &e) {
+    std::string header = std::string(e.what()) + "\n";
+    std::vector<std::string> names;
+
+    // Collect names
+    if(app->get_help_ptr() != nullptr)
+        names.push_back(app->get_help_ptr()->get_name());
+
+    if(app->get_help_all_ptr() != nullptr)
+        names.push_back(app->get_help_all_ptr()->get_name());
+
+    // If any names found, suggest those
+    if(!names.empty())
+        header += "Run with " + detail::join(names, " or ") + " for more information.\n";
+
+    return header;
+}
+
+CLI11_INLINE std::string help(const App *app, const Error &e) {
+    std::string header = std::string("ERROR: ") + e.get_name() + ": " + e.what() + "\n";
+    header += app->help();
+    return header;
+}
+
+}  // namespace FailureMessage
+
+
+
+
+namespace detail {
+
+std::string convert_arg_for_ini(const std::string &arg,
+                                char stringQuote = '"',
+                                char literalQuote = '\'',
+                                bool disable_multi_line = false);
+
+/// Comma separated join, adds quotes if needed
+std::string ini_join(const std::vector<std::string> &args,
+                     char sepChar = ',',
+                     char arrayStart = '[',
+                     char arrayEnd = ']',
+                     char stringQuote = '"',
+                     char literalQuote = '\'');
+
+void clean_name_string(std::string &name, const std::string &keyChars);
+
+std::vector<std::string> generate_parents(const std::string &section, std::string &name, char parentSeparator);
+
+/// assuming non default segments do a check on the close and open of the segments in a configItem structure
+void checkParentSegments(std::vector<ConfigItem> &output, const std::string &currentSection, char parentSeparator);
+}  // namespace detail
+
+
+
+
+static constexpr auto multiline_literal_quote = R"(''')";
+static constexpr auto multiline_string_quote = R"(""")";
+
+namespace detail {
+
+CLI11_INLINE bool is_printable(const std::string &test_string) {
+    return std::all_of(test_string.begin(), test_string.end(), [](char x) {
+        return (isprint(static_cast<unsigned char>(x)) != 0 || x == '\n' || x == '\t');
+    });
+}
+
+CLI11_INLINE std::string
+convert_arg_for_ini(const std::string &arg, char stringQuote, char literalQuote, bool disable_multi_line) {
+    if(arg.empty()) {
+        return std::string(2, stringQuote);
+    }
+    // some specifically supported strings
+    if(arg == "true" || arg == "false" || arg == "nan" || arg == "inf") {
+        return arg;
+    }
+    // floating point conversion can convert some hex codes, but don't try that here
+    if(arg.compare(0, 2, "0x") != 0 && arg.compare(0, 2, "0X") != 0) {
+        using CLI::detail::lexical_cast;
+        double val = 0.0;
+        if(lexical_cast(arg, val)) {
+            if(arg.find_first_not_of("0123456789.-+eE") == std::string::npos) {
+                return arg;
+            }
+        }
+    }
+    // just quote a single non numeric character
+    if(arg.size() == 1) {
+        if(isprint(static_cast<unsigned char>(arg.front())) == 0) {
+            return binary_escape_string(arg);
+        }
+        if(arg == "'") {
+            return std::string(1, stringQuote) + "'" + stringQuote;
+        }
+        return std::string(1, literalQuote) + arg + literalQuote;
+    }
+    // handle hex, binary or octal arguments
+    if(arg.front() == '0') {
+        if(arg[1] == 'x') {
+            if(std::all_of(arg.begin() + 2, arg.end(), [](char x) {
+                   return (x >= '0' && x <= '9') || (x >= 'A' && x <= 'F') || (x >= 'a' && x <= 'f');
+               })) {
+                return arg;
+            }
+        } else if(arg[1] == 'o') {
+            if(std::all_of(arg.begin() + 2, arg.end(), [](char x) { return (x >= '0' && x <= '7'); })) {
+                return arg;
+            }
+        } else if(arg[1] == 'b') {
+            if(std::all_of(arg.begin() + 2, arg.end(), [](char x) { return (x == '0' || x == '1'); })) {
+                return arg;
+            }
+        }
+    }
+    if(!is_printable(arg)) {
+        return binary_escape_string(arg);
+    }
+    if(detail::has_escapable_character(arg)) {
+        if(arg.size() > 100 && !disable_multi_line) {
+            if(arg.find(multiline_literal_quote) != std::string::npos) {
+                return binary_escape_string(arg, true);
+            }
+            std::string return_string{multiline_literal_quote};
+            return_string.reserve(7 + arg.size());
+            if(arg.front() == '\n' || arg.front() == '\r') {
+                return_string.push_back('\n');
+            }
+            return_string.append(arg);
+            if(arg.back() == '\n' || arg.back() == '\r') {
+                return_string.push_back('\n');
+            }
+            return_string.append(multiline_literal_quote, 3);
+            return return_string;
+        }
+        return std::string(1, stringQuote) + detail::add_escaped_characters(arg) + stringQuote;
+    }
+    return std::string(1, stringQuote) + arg + stringQuote;
+}
+
+CLI11_INLINE std::string ini_join(const std::vector<std::string> &args,
+                                  char sepChar,
+                                  char arrayStart,
+                                  char arrayEnd,
+                                  char stringQuote,
+                                  char literalQuote) {
+    bool disable_multi_line{false};
+    std::string joined;
+    if(args.size() > 1 && arrayStart != '\0') {
+        joined.push_back(arrayStart);
+        disable_multi_line = true;
+    }
+    std::size_t start = 0;
+    for(const auto &arg : args) {
+        if(start++ > 0) {
+            joined.push_back(sepChar);
+            if(!std::isspace<char>(sepChar, std::locale())) {
+                joined.push_back(' ');
+            }
+        }
+        joined.append(convert_arg_for_ini(arg, stringQuote, literalQuote, disable_multi_line));
+    }
+    if(args.size() > 1 && arrayEnd != '\0') {
+        joined.push_back(arrayEnd);
+    }
+    return joined;
+}
+
+CLI11_INLINE std::vector<std::string>
+generate_parents(const std::string &section, std::string &name, char parentSeparator) {
+    std::vector<std::string> parents;
+    if(detail::to_lower(section) != "default") {
+        if(section.find(parentSeparator) != std::string::npos) {
+            parents = detail::split_up(section, parentSeparator);
+        } else {
+            parents = {section};
+        }
+    }
+    if(name.find(parentSeparator) != std::string::npos) {
+        std::vector<std::string> plist = detail::split_up(name, parentSeparator);
+        name = plist.back();
+        plist.pop_back();
+        parents.insert(parents.end(), plist.begin(), plist.end());
+    }
+    // clean up quotes on the parents
+    try {
+        detail::remove_quotes(parents);
+    } catch(const std::invalid_argument &iarg) {
+        throw CLI::ParseError(iarg.what(), CLI::ExitCodes::InvalidError);
+    }
+    return parents;
+}
+
+CLI11_INLINE void
+checkParentSegments(std::vector<ConfigItem> &output, const std::string &currentSection, char parentSeparator) {
+
+    std::string estring;
+    auto parents = detail::generate_parents(currentSection, estring, parentSeparator);
+    if(!output.empty() && output.back().name == "--") {
+        std::size_t msize = (parents.size() > 1U) ? parents.size() : 2;
+        while(output.back().parents.size() >= msize) {
+            output.push_back(output.back());
+            output.back().parents.pop_back();
+        }
+
+        if(parents.size() > 1) {
+            std::size_t common = 0;
+            std::size_t mpair = (std::min)(output.back().parents.size(), parents.size() - 1);
+            for(std::size_t ii = 0; ii < mpair; ++ii) {
+                if(output.back().parents[ii] != parents[ii]) {
+                    break;
+                }
+                ++common;
+            }
+            if(common == mpair) {
+                output.pop_back();
+            } else {
+                while(output.back().parents.size() > common + 1) {
+                    output.push_back(output.back());
+                    output.back().parents.pop_back();
+                }
+            }
+            for(std::size_t ii = common; ii < parents.size() - 1; ++ii) {
+                output.emplace_back();
+                output.back().parents.assign(parents.begin(), parents.begin() + static_cast<std::ptrdiff_t>(ii) + 1);
+                output.back().name = "++";
+            }
+        }
+    } else if(parents.size() > 1) {
+        for(std::size_t ii = 0; ii < parents.size() - 1; ++ii) {
+            output.emplace_back();
+            output.back().parents.assign(parents.begin(), parents.begin() + static_cast<std::ptrdiff_t>(ii) + 1);
+            output.back().name = "++";
+        }
+    }
+
+    // insert a section end which is just an empty items_buffer
+    output.emplace_back();
+    output.back().parents = std::move(parents);
+    output.back().name = "++";
+}
+
+/// @brief  checks if a string represents a multiline comment
+CLI11_INLINE bool hasMLString(std::string const &fullString, char check) {
+    if(fullString.length() < 3) {
+        return false;
+    }
+    auto it = fullString.rbegin();
+    return (*it == check) && (*(it + 1) == check) && (*(it + 2) == check);
+}
+
+/// @brief  find a matching configItem in a list
+inline auto find_matching_config(std::vector<ConfigItem> &items,
+                                 const std::vector<std::string> &parents,
+                                 const std::string &name,
+                                 bool fullSearch) -> decltype(items.begin()) {
+    if(items.empty()) {
+        return items.end();
+    }
+    auto search = items.end() - 1;
+    do {
+        if(search->parents == parents && search->name == name) {
+            return search;
+        }
+        if(search == items.begin()) {
+            break;
+        }
+        --search;
+    } while(fullSearch);
+    return items.end();
+}
+}  // namespace detail
+
+inline std::vector<ConfigItem> ConfigBase::from_config(std::istream &input) const {
+    std::string line;
+    std::string buffer;
+    std::string currentSection = "default";
+    std::string previousSection = "default";
+    std::vector<ConfigItem> output;
+    bool isDefaultArray = (arrayStart == '[' && arrayEnd == ']' && arraySeparator == ',');
+    bool isINIArray = (arrayStart == '\0' || arrayStart == ' ') && arrayStart == arrayEnd;
+    bool inSection{false};
+    bool inMLineComment{false};
+    bool inMLineValue{false};
+
+    char aStart = (isINIArray) ? '[' : arrayStart;
+    char aEnd = (isINIArray) ? ']' : arrayEnd;
+    char aSep = (isINIArray && arraySeparator == ' ') ? ',' : arraySeparator;
+    int currentSectionIndex{0};
+
+    std::string line_sep_chars{parentSeparatorChar, commentChar, valueDelimiter};
+    while(getline(input, buffer)) {
+        std::vector<std::string> items_buffer;
+        std::string name;
+        line = detail::trim_copy(buffer);
+        std::size_t len = line.length();
+        // lines have to be at least 3 characters to have any meaning to CLI just skip the rest
+        if(len < 3) {
+            continue;
+        }
+        if(line.compare(0, 3, multiline_string_quote) == 0 || line.compare(0, 3, multiline_literal_quote) == 0) {
+            inMLineComment = true;
+            auto cchar = line.front();
+            while(inMLineComment) {
+                if(getline(input, line)) {
+                    detail::trim(line);
+                } else {
+                    break;
+                }
+                if(detail::hasMLString(line, cchar)) {
+                    inMLineComment = false;
+                }
+            }
+            continue;
+        }
+        if(line.front() == '[' && line.back() == ']') {
+            if(currentSection != "default") {
+                // insert a section end which is just an empty items_buffer
+                output.emplace_back();
+                output.back().parents = detail::generate_parents(currentSection, name, parentSeparatorChar);
+                output.back().name = "--";
+            }
+            currentSection = line.substr(1, len - 2);
+            // deal with double brackets for TOML
+            if(currentSection.size() > 1 && currentSection.front() == '[' && currentSection.back() == ']') {
+                currentSection = currentSection.substr(1, currentSection.size() - 2);
+            }
+            if(detail::to_lower(currentSection) == "default") {
+                currentSection = "default";
+            } else {
+                detail::checkParentSegments(output, currentSection, parentSeparatorChar);
+            }
+            inSection = false;
+            if(currentSection == previousSection) {
+                ++currentSectionIndex;
+            } else {
+                currentSectionIndex = 0;
+                previousSection = currentSection;
+            }
+            continue;
+        }
+
+        // comment lines
+        if(line.front() == ';' || line.front() == '#' || line.front() == commentChar) {
+            continue;
+        }
+        std::size_t search_start = 0;
+        if(line.find_first_of("\"'`") != std::string::npos) {
+            while(search_start < line.size()) {
+                auto test_char = line[search_start];
+                if(test_char == '\"' || test_char == '\'' || test_char == '`') {
+                    search_start = detail::close_sequence(line, search_start, line[search_start]);
+                    ++search_start;
+                } else if(test_char == valueDelimiter || test_char == commentChar) {
+                    --search_start;
+                    break;
+                } else if(test_char == ' ' || test_char == '\t' || test_char == parentSeparatorChar) {
+                    ++search_start;
+                } else {
+                    search_start = line.find_first_of(line_sep_chars, search_start);
+                }
+            }
+        }
+        // Find = in string, split and recombine
+        auto delimiter_pos = line.find_first_of(valueDelimiter, search_start + 1);
+        auto comment_pos = line.find_first_of(commentChar, search_start);
+        if(comment_pos < delimiter_pos) {
+            delimiter_pos = std::string::npos;
+        }
+        if(delimiter_pos != std::string::npos) {
+
+            name = detail::trim_copy(line.substr(0, delimiter_pos));
+            std::string item = detail::trim_copy(line.substr(delimiter_pos + 1, std::string::npos));
+            bool mlquote =
+                (item.compare(0, 3, multiline_literal_quote) == 0 || item.compare(0, 3, multiline_string_quote) == 0);
+            if(!mlquote && comment_pos != std::string::npos) {
+                auto citems = detail::split_up(item, commentChar);
+                item = detail::trim_copy(citems.front());
+            }
+            if(mlquote) {
+                // multiline string
+                auto keyChar = item.front();
+                item = buffer.substr(delimiter_pos + 1, std::string::npos);
+                detail::ltrim(item);
+                item.erase(0, 3);
+                inMLineValue = true;
+                bool lineExtension{false};
+                bool firstLine = true;
+                if(!item.empty() && item.back() == '\\' && keyChar == '\"') {
+                    item.pop_back();
+                    lineExtension = true;
+                } else if(detail::hasMLString(item, keyChar)) {
+                    // deal with the first line closing the multiline literal
+                    item.pop_back();
+                    item.pop_back();
+                    item.pop_back();
+                    if(keyChar == '\"') {
+                        try {
+                            item = detail::remove_escaped_characters(item);
+                        } catch(const std::invalid_argument &iarg) {
+                            throw CLI::ParseError(iarg.what(), CLI::ExitCodes::InvalidError);
+                        }
+                    }
+                    inMLineValue = false;
+                }
+                while(inMLineValue) {
+                    std::string l2;
+                    if(!std::getline(input, l2)) {
+                        break;
+                    }
+                    line = l2;
+                    detail::rtrim(line);
+                    if(detail::hasMLString(line, keyChar)) {
+                        line.pop_back();
+                        line.pop_back();
+                        line.pop_back();
+                        if(lineExtension) {
+                            detail::ltrim(line);
+                        } else if(!(firstLine && item.empty())) {
+                            item.push_back('\n');
+                        }
+                        firstLine = false;
+                        item += line;
+                        inMLineValue = false;
+                        if(!item.empty() && item.back() == '\n') {
+                            item.pop_back();
+                        }
+                        if(keyChar == '\"') {
+                            try {
+                                item = detail::remove_escaped_characters(item);
+                            } catch(const std::invalid_argument &iarg) {
+                                throw CLI::ParseError(iarg.what(), CLI::ExitCodes::InvalidError);
+                            }
+                        }
+                    } else {
+                        if(lineExtension) {
+                            detail::trim(l2);
+                        } else if(!(firstLine && item.empty())) {
+                            item.push_back('\n');
+                        }
+                        lineExtension = false;
+                        firstLine = false;
+                        if(!l2.empty() && l2.back() == '\\' && keyChar == '\"') {
+                            lineExtension = true;
+                            l2.pop_back();
+                        }
+                        item += l2;
+                    }
+                }
+                items_buffer = {item};
+            } else if(!item.empty() && item.front() == aStart) {
+                for(std::string multiline; item.back() != aEnd && std::getline(input, multiline);) {
+                    detail::trim(multiline);
+                    item += multiline;
+                }
+                if(item.back() == aEnd) {
+                    items_buffer = detail::split_up(item.substr(1, item.length() - 2), aSep);
+                } else {
+                    items_buffer = detail::split_up(item.substr(1, std::string::npos), aSep);
+                }
+            } else if((isDefaultArray || isINIArray) && item.find_first_of(aSep) != std::string::npos) {
+                items_buffer = detail::split_up(item, aSep);
+            } else if((isDefaultArray || isINIArray) && item.find_first_of(' ') != std::string::npos) {
+                items_buffer = detail::split_up(item, '\0');
+            } else {
+                items_buffer = {item};
+            }
+        } else {
+            name = detail::trim_copy(line.substr(0, comment_pos));
+            items_buffer = {"true"};
+        }
+        std::vector<std::string> parents;
+        try {
+            parents = detail::generate_parents(currentSection, name, parentSeparatorChar);
+            detail::process_quoted_string(name, '"', '\'', true);
+            // clean up quotes on the items and check for escaped strings
+            for(auto &it : items_buffer) {
+                detail::process_quoted_string(it, stringQuote, literalQuote);
+            }
+        } catch(const std::invalid_argument &ia) {
+            throw CLI::ParseError(ia.what(), CLI::ExitCodes::InvalidError);
+        }
+
+        if(parents.size() > maximumLayers) {
+            continue;
+        }
+        if(!configSection.empty() && !inSection) {
+            if(parents.empty() || parents.front() != configSection) {
+                continue;
+            }
+            if(configIndex >= 0 && currentSectionIndex != configIndex) {
+                continue;
+            }
+            parents.erase(parents.begin());
+            inSection = true;
+        }
+        auto match = detail::find_matching_config(output, parents, name, allowMultipleDuplicateFields);
+        if(match != output.end()) {
+            if((match->inputs.size() > 1 && items_buffer.size() > 1) || allowMultipleDuplicateFields) {
+                // insert a separator if one is not already present
+                if(!(match->inputs.back().empty() || items_buffer.front().empty() || match->inputs.back() == "%%" ||
+                     items_buffer.front() == "%%")) {
+                    match->inputs.emplace_back("%%");
+                    match->multiline = true;
+                }
+            }
+            match->inputs.insert(match->inputs.end(), items_buffer.begin(), items_buffer.end());
+        } else {
+            output.emplace_back();
+            output.back().parents = std::move(parents);
+            output.back().name = std::move(name);
+            output.back().inputs = std::move(items_buffer);
+        }
+    }
+    if(currentSection != "default") {
+        // insert a section end which is just an empty items_buffer
+        std::string ename;
+        output.emplace_back();
+        output.back().parents = detail::generate_parents(currentSection, ename, parentSeparatorChar);
+        output.back().name = "--";
+        while(output.back().parents.size() > 1) {
+            output.push_back(output.back());
+            output.back().parents.pop_back();
+        }
+    }
+    return output;
+}
+
+CLI11_INLINE std::string &clean_name_string(std::string &name, const std::string &keyChars) {
+    if(name.find_first_of(keyChars) != std::string::npos || (name.front() == '[' && name.back() == ']') ||
+       (name.find_first_of("'`\"\\") != std::string::npos)) {
+        if(name.find_first_of('\'') == std::string::npos) {
+            name.insert(0, 1, '\'');
+            name.push_back('\'');
+        } else {
+            if(detail::has_escapable_character(name)) {
+                name = detail::add_escaped_characters(name);
+            }
+            name.insert(0, 1, '\"');
+            name.push_back('\"');
+        }
+    }
+    return name;
+}
+
+CLI11_INLINE std::string
+ConfigBase::to_config(const App *app, bool default_also, bool write_description, std::string prefix) const {
+    std::stringstream out;
+    std::string commentLead;
+    commentLead.push_back(commentChar);
+    commentLead.push_back(' ');
+
+    std::string commentTest = "#;";
+    commentTest.push_back(commentChar);
+    commentTest.push_back(parentSeparatorChar);
+
+    std::string keyChars = commentTest;
+    keyChars.push_back(literalQuote);
+    keyChars.push_back(stringQuote);
+    keyChars.push_back(arrayStart);
+    keyChars.push_back(arrayEnd);
+    keyChars.push_back(valueDelimiter);
+    keyChars.push_back(arraySeparator);
+
+    std::vector<std::string> groups = app->get_groups();
+    bool defaultUsed = false;
+    groups.insert(groups.begin(), std::string("OPTIONS"));
+
+    for(auto &group : groups) {
+        if(group == "OPTIONS" || group.empty()) {
+            if(defaultUsed) {
+                continue;
+            }
+            defaultUsed = true;
+        }
+        if(write_description && group != "OPTIONS" && !group.empty()) {
+            out << '\n' << commentChar << commentLead << group << " Options\n";
+        }
+        for(const Option *opt : app->get_options({})) {
+            // Only process options that are configurable
+            if(opt->get_configurable()) {
+                if(opt->get_group() != group) {
+                    if(!(group == "OPTIONS" && opt->get_group().empty())) {
+                        continue;
+                    }
+                }
+                std::string single_name = opt->get_single_name();
+                if(single_name.empty()) {
+                    continue;
+                }
+
+                auto results = opt->reduced_results();
+                if(results.size() > 1 && opt->get_multi_option_policy() == CLI::MultiOptionPolicy::Reverse) {
+                    std::reverse(results.begin(), results.end());
+                }
+                if(opt->get_multi_option_policy() == CLI::MultiOptionPolicy::Sum && opt->count() >= 1 &&
+                   results.size() == 1) {
+                    // if the multi option policy is sum then there is a possibility of incorrect fields being produced
+                    // best to just use the original data for config files
+                    auto pos = opt->_validate(results[0], 0);
+                    if(!pos.empty()) {
+                        results = opt->results();
+                    }
+                }
+                if(opt->get_multi_option_policy() == CLI::MultiOptionPolicy::Join && opt->count() > 1) {
+                    char delim = opt->get_delimiter();
+                    if(delim == '\0') {
+                        // this branch deals with a situation where the output would not be readable by a config file
+                        results = opt->results();
+                    } else {
+                        // this branch deals with the case of the strings containing the delimiter itself or empty
+                        // strings which would be interpreted incorrectly
+                        auto delim_count = std::count(results[0].begin(), results[0].end(), delim);
+                        if(results[0].back() == delim ||
+                           static_cast<decltype(delim_count)>(opt->count()) < delim_count - 1 ||
+                           results[0].find(std::string(2, delim)) != std::string::npos) {
+                            results = opt->results();
+                        }
+                    }
+                }
+                std::string value;
+
+                if(opt->count() == 1 && results.size() == 2 && results.front() == "{}" && results.back() == "%%") {
+                    // there is a catch to allow for {} to used as as string in the output
+                    //  it will append a sequence terminator to the output so the lexical conversion handles it
+                    //  correctly but that is meant for config files so when outputting for a config file we need to
+                    //  makes sure to get the correct output
+                    value = "\"{}\"";
+                } else {
+                    value = detail::ini_join(results, arraySeparator, arrayStart, arrayEnd, stringQuote, literalQuote);
+                }
+
+                bool isDefault = false;
+                if(value.empty() && default_also) {
+                    if(!opt->get_default_str().empty()) {
+                        results_t res;
+                        opt->results(res);
+                        value = detail::ini_join(res, arraySeparator, arrayStart, arrayEnd, stringQuote, literalQuote);
+                    } else if(opt->get_expected_min() == 0) {
+                        value = "false";
+                    } else if(opt->get_run_callback_for_default() || !opt->get_required()) {
+                        value = "\"\"";  // empty string default value
+                    } else {
+                        value = "\"<REQUIRED>\"";
+                    }
+                    isDefault = true;
+                }
+
+                if(!value.empty()) {
+                    if(!opt->get_fnames().empty()) {
+                        try {
+                            value = opt->get_flag_value(single_name, value);
+                        } catch(const CLI::ArgumentMismatch &) {
+                            bool valid{false};
+                            for(const auto &test_name : opt->get_fnames()) {
+                                try {
+                                    value = opt->get_flag_value(test_name, value);
+                                    single_name = test_name;
+                                    valid = true;
+                                } catch(const CLI::ArgumentMismatch &) {
+                                    continue;
+                                }
+                            }
+                            if(!valid) {
+                                value = detail::ini_join(
+                                    opt->results(), arraySeparator, arrayStart, arrayEnd, stringQuote, literalQuote);
+                            }
+                        }
+                    }
+                    if(write_description && opt->has_description()) {
+                        if(out.tellp() != std::streampos(0)) {
+                            out << '\n';
+                        }
+                        out << commentLead << detail::fix_newlines(commentLead, opt->get_description()) << '\n';
+                    }
+                    clean_name_string(single_name, keyChars);
+
+                    std::string name = prefix + single_name;
+                    if(commentDefaultsBool && isDefault) {
+                        name = commentChar + name;
+                    }
+                    out << name << valueDelimiter << value << '\n';
+                }
+            }
+        }
+    }
+
+    auto subcommands = app->get_subcommands({});
+    for(const App *subcom : subcommands) {
+        if(subcom->get_name().empty()) {
+            if(!default_also && (subcom->count_all() == 0)) {
+                continue;
+            }
+            if(write_description && !subcom->get_group().empty()) {
+                out << '\n' << commentLead << subcom->get_group() << " Options\n";
+            }
+            /*if (!prefix.empty() || app->get_parent() == nullptr) {
+                out << '[' << prefix << "___"<< subcom->get_group() << "]\n";
+            } else {
+                std::string subname = app->get_name() + parentSeparatorChar + "___"+subcom->get_group();
+                const auto *p = app->get_parent();
+                while(p->get_parent() != nullptr) {
+                    subname = p->get_name() + parentSeparatorChar +subname;
+                    p = p->get_parent();
+                }
+                out << '[' << subname << "]\n";
+            }
+            */
+            out << to_config(subcom, default_also, write_description, prefix);
+        }
+    }
+
+    for(const App *subcom : subcommands) {
+        if(!subcom->get_name().empty()) {
+            if(!default_also && (subcom->count_all() == 0)) {
+                continue;
+            }
+            std::string subname = subcom->get_name();
+            clean_name_string(subname, keyChars);
+
+            if(subcom->get_configurable() && (default_also || app->got_subcommand(subcom))) {
+                if(!prefix.empty() || app->get_parent() == nullptr) {
+
+                    out << '[' << prefix << subname << "]\n";
+                } else {
+                    std::string appname = app->get_name();
+                    clean_name_string(appname, keyChars);
+                    subname = appname + parentSeparatorChar + subname;
+                    const auto *p = app->get_parent();
+                    while(p->get_parent() != nullptr) {
+                        std::string pname = p->get_name();
+                        clean_name_string(pname, keyChars);
+                        subname = pname + parentSeparatorChar + subname;
+                        p = p->get_parent();
+                    }
+                    out << '[' << subname << "]\n";
+                }
+                out << to_config(subcom, default_also, write_description, "");
+            } else {
+                out << to_config(subcom, default_also, write_description, prefix + subname + parentSeparatorChar);
+            }
+        }
+    }
+
+    if(write_description && !out.str().empty()) {
+        std::string outString =
+            commentChar + commentLead + detail::fix_newlines(commentChar + commentLead, app->get_description()) + '\n';
+        return outString + out.str();
+    }
+    return out.str();
+}
+
+
+
+
+
+
+CLI11_INLINE std::string
+Formatter::make_group(std::string group, bool is_positional, std::vector<const Option *> opts) const {
+    std::stringstream out;
+
+    out << "\n" << group << ":\n";
+    for(const Option *opt : opts) {
+        out << make_option(opt, is_positional);
+    }
+
+    return out.str();
+}
+
+CLI11_INLINE std::string Formatter::make_positionals(const App *app) const {
+    std::vector<const Option *> opts =
+        app->get_options([](const Option *opt) { return !opt->get_group().empty() && opt->get_positional(); });
+
+    if(opts.empty())
+        return {};
+
+    return make_group(get_label("POSITIONALS"), true, opts);
+}
+
+CLI11_INLINE std::string Formatter::make_groups(const App *app, AppFormatMode mode) const {
+    std::stringstream out;
+    std::vector<std::string> groups = app->get_groups();
+
+    // Options
+    for(const std::string &group : groups) {
+        std::vector<const Option *> opts = app->get_options([app, mode, &group](const Option *opt) {
+            return opt->get_group() == group                     // Must be in the right group
+                   && opt->nonpositional()                       // Must not be a positional
+                   && (mode != AppFormatMode::Sub                // If mode is Sub, then
+                       || (app->get_help_ptr() != opt            // Ignore help pointer
+                           && app->get_help_all_ptr() != opt));  // Ignore help all pointer
+        });
+        if(!group.empty() && !opts.empty()) {
+            out << make_group(group, false, opts);
+
+            // Removed double newline between groups for consistency of help text
+            // if(group != groups.back())
+            //    out << "\n";
+        }
+    }
+
+    return out.str();
+}
+
+CLI11_INLINE std::string Formatter::make_description(const App *app) const {
+    std::string desc = app->get_description();
+    auto min_options = app->get_require_option_min();
+    auto max_options = app->get_require_option_max();
+
+    if(app->get_required()) {
+        desc += " " + get_label("REQUIRED") + " ";
+    }
+
+    if(min_options > 0) {
+        if(max_options == min_options) {
+            desc += " \n[Exactly " + std::to_string(min_options) + " of the following options are required]";
+        } else if(max_options > 0) {
+            desc += " \n[Between " + std::to_string(min_options) + " and " + std::to_string(max_options) +
+                    " of the following options are required]";
+        } else {
+            desc += " \n[At least " + std::to_string(min_options) + " of the following options are required]";
+        }
+    } else if(max_options > 0) {
+        desc += " \n[At most " + std::to_string(max_options) + " of the following options are allowed]";
+    }
+
+    return (!desc.empty()) ? desc + "\n\n" : std::string{};
+}
+
+CLI11_INLINE std::string Formatter::make_usage(const App *app, std::string name) const {
+    std::string usage = app->get_usage();
+    if(!usage.empty()) {
+        return usage + "\n\n";
+    }
+
+    std::stringstream out;
+    out << '\n';
+
+    if(name.empty())
+        out << get_label("Usage") << ':';
+    else
+        out << name;
+
+    std::vector<std::string> groups = app->get_groups();
+
+    // Print an Options badge if any options exist
+    std::vector<const Option *> non_pos_options =
+        app->get_options([](const Option *opt) { return opt->nonpositional(); });
+    if(!non_pos_options.empty())
+        out << " [" << get_label("OPTIONS") << "]";
+
+    // Positionals need to be listed here
+    std::vector<const Option *> positionals = app->get_options([](const Option *opt) { return opt->get_positional(); });
+
+    // Print out positionals if any are left
+    if(!positionals.empty()) {
+        // Convert to help names
+        std::vector<std::string> positional_names(positionals.size());
+        std::transform(positionals.begin(), positionals.end(), positional_names.begin(), [this](const Option *opt) {
+            return make_option_usage(opt);
+        });
+
+        out << " " << detail::join(positional_names, " ");
+    }
+
+    // Add a marker if subcommands are expected or optional
+    if(!app->get_subcommands(
+               [](const CLI::App *subc) { return ((!subc->get_disabled()) && (!subc->get_name().empty())); })
+            .empty()) {
+        out << ' ' << (app->get_require_subcommand_min() == 0 ? "[" : "")
+            << get_label(app->get_require_subcommand_max() == 1 ? "SUBCOMMAND" : "SUBCOMMANDS")
+            << (app->get_require_subcommand_min() == 0 ? "]" : "");
+    }
+
+    out << "\n\n";
+
+    return out.str();
+}
+
+CLI11_INLINE std::string Formatter::make_footer(const App *app) const {
+    std::string footer = app->get_footer();
+    if(footer.empty()) {
+        return std::string{};
+    }
+    return '\n' + footer + '\n';
+}
+
+CLI11_INLINE std::string Formatter::make_help(const App *app, std::string name, AppFormatMode mode) const {
+    // This immediately forwards to the make_expanded method. This is done this way so that subcommands can
+    // have overridden formatters
+    if(mode == AppFormatMode::Sub)
+        return make_expanded(app, mode);
+
+    std::stringstream out;
+    if((app->get_name().empty()) && (app->get_parent() != nullptr)) {
+        if(app->get_group() != "SUBCOMMANDS") {
+            out << app->get_group() << ':';
+        }
+    }
+    if(is_description_paragraph_formatting_enabled()) {
+        detail::streamOutAsParagraph(
+            out, make_description(app), description_paragraph_width_, "");  // Format description as paragraph
+    } else {
+        out << make_description(app) << '\n';
+    }
+    out << make_usage(app, name);
+    out << make_positionals(app);
+    out << make_groups(app, mode);
+    out << make_subcommands(app, mode);
+    std::string footer_string = make_footer(app);
+
+    if(is_footer_paragraph_formatting_enabled()) {
+        detail::streamOutAsParagraph(out, footer_string, footer_paragraph_width_);  // Format footer as paragraph
+    } else {
+        out << footer_string;
+    }
+
+    return out.str();
+}
+
+CLI11_INLINE std::string Formatter::make_subcommands(const App *app, AppFormatMode mode) const {
+    std::stringstream out;
+
+    std::vector<const App *> subcommands = app->get_subcommands({});
+
+    // Make a list in definition order of the groups seen
+    std::vector<std::string> subcmd_groups_seen;
+    for(const App *com : subcommands) {
+        if(com->get_name().empty()) {
+            if(!com->get_group().empty() && com->get_group().front() != '+') {
+                out << make_expanded(com, mode);
+            }
+            continue;
+        }
+        std::string group_key = com->get_group();
+        if(!group_key.empty() &&
+           std::find_if(subcmd_groups_seen.begin(), subcmd_groups_seen.end(), [&group_key](std::string a) {
+               return detail::to_lower(a) == detail::to_lower(group_key);
+           }) == subcmd_groups_seen.end())
+            subcmd_groups_seen.push_back(group_key);
+    }
+
+    // For each group, filter out and print subcommands
+    for(const std::string &group : subcmd_groups_seen) {
+        out << '\n' << group << ":\n";
+        std::vector<const App *> subcommands_group = app->get_subcommands(
+            [&group](const App *sub_app) { return detail::to_lower(sub_app->get_group()) == detail::to_lower(group); });
+        for(const App *new_com : subcommands_group) {
+            if(new_com->get_name().empty())
+                continue;
+            if(mode != AppFormatMode::All) {
+                out << make_subcommand(new_com);
+            } else {
+                out << new_com->help(new_com->get_name(), AppFormatMode::Sub);
+                out << '\n';
+            }
+        }
+    }
+
+    return out.str();
+}
+
+CLI11_INLINE std::string Formatter::make_subcommand(const App *sub) const {
+    std::stringstream out;
+    std::string name = "  " + sub->get_display_name(true) + (sub->get_required() ? " " + get_label("REQUIRED") : "");
+
+    out << std::setw(static_cast<int>(column_width_)) << std::left << name;
+    detail::streamOutAsParagraph(
+        out, sub->get_description(), right_column_width_, std::string(column_width_, ' '), true);
+    out << '\n';
+    return out.str();
+}
+
+CLI11_INLINE std::string Formatter::make_expanded(const App *sub, AppFormatMode mode) const {
+    std::stringstream out;
+    out << sub->get_display_name(true) << '\n';
+
+    if(is_description_paragraph_formatting_enabled()) {
+        detail::streamOutAsParagraph(
+            out, make_description(sub), description_paragraph_width_, "  ");  // Format description as paragraph
+    } else {
+        out << make_description(sub) << '\n';
+    }
+
+    if(sub->get_name().empty() && !sub->get_aliases().empty()) {
+        detail::format_aliases(out, sub->get_aliases(), column_width_ + 2);
+    }
+
+    out << make_positionals(sub);
+    out << make_groups(sub, mode);
+    out << make_subcommands(sub, mode);
+    std::string footer_string = make_footer(sub);
+
+    if(mode == AppFormatMode::Sub && !footer_string.empty()) {
+        const auto *parent = sub->get_parent();
+        std::string parent_footer = (parent != nullptr) ? make_footer(sub->get_parent()) : std::string{};
+        if(footer_string == parent_footer) {
+            footer_string = "";
+        }
+    }
+    if(!footer_string.empty()) {
+        if(is_footer_paragraph_formatting_enabled()) {
+            detail::streamOutAsParagraph(out, footer_string, footer_paragraph_width_);  // Format footer as paragraph
+        } else {
+            out << footer_string;
+        }
+    }
+    return out.str();
+}
+
+CLI11_INLINE std::string Formatter::make_option(const Option *opt, bool is_positional) const {
+    std::stringstream out;
+    if(is_positional) {
+        const std::string left = "  " + make_option_name(opt, true) + make_option_opts(opt);
+        const std::string desc = make_option_desc(opt);
+        out << std::setw(static_cast<int>(column_width_)) << std::left << left;
+
+        if(!desc.empty()) {
+            bool skipFirstLinePrefix = true;
+            if(left.length() >= column_width_) {
+                out << '\n';
+                skipFirstLinePrefix = false;
+            }
+            detail::streamOutAsParagraph(
+                out, desc, right_column_width_, std::string(column_width_, ' '), skipFirstLinePrefix);
+        }
+    } else {
+        const std::string namesCombined = make_option_name(opt, false);
+        const std::string opts = make_option_opts(opt);
+        const std::string desc = make_option_desc(opt);
+
+        // Split all names at comma and sort them into short names and long names
+        const auto names = detail::split(namesCombined, ',');
+        std::vector<std::string> vshortNames;
+        std::vector<std::string> vlongNames;
+        std::for_each(names.begin(), names.end(), [&vshortNames, &vlongNames](const std::string &name) {
+            if(name.find("--", 0) != std::string::npos)
+                vlongNames.push_back(name);
+            else
+                vshortNames.push_back(name);
+        });
+
+        // Assemble short and long names
+        std::string shortNames = detail::join(vshortNames, ", ");
+        std::string longNames = detail::join(vlongNames, ", ");
+
+        // Calculate setw sizes
+        // Short names take enough width to align long names at the desired ratio
+        const auto shortNamesColumnWidth =
+            static_cast<int>(static_cast<float>(column_width_) * long_option_alignment_ratio_);
+        const auto longNamesColumnWidth = static_cast<int>(column_width_) - shortNamesColumnWidth;
+        int shortNamesOverSize = 0;
+
+        // Print short names
+        if(!shortNames.empty()) {
+            shortNames = "  " + shortNames;  // Indent
+            if(longNames.empty() && !opts.empty())
+                shortNames += opts;  // Add opts if only short names and no long names
+            if(!longNames.empty())
+                shortNames += ",";
+            if(static_cast<int>(shortNames.length()) >= shortNamesColumnWidth) {
+                shortNames += " ";
+                shortNamesOverSize = static_cast<int>(shortNames.length()) - shortNamesColumnWidth;
+            }
+            out << std::setw(shortNamesColumnWidth) << std::left << shortNames;
+        } else {
+            out << std::setw(shortNamesColumnWidth) << std::left << "";
+        }
+
+        // Adjust long name column width in case of short names column reaching into long names column
+        shortNamesOverSize =
+            (std::min)(shortNamesOverSize, longNamesColumnWidth);  // Prevent negative result with unsigned integers
+        const auto adjustedLongNamesColumnWidth = longNamesColumnWidth - shortNamesOverSize;
+
+        // Print long names
+        if(!longNames.empty()) {
+            if(!opts.empty())
+                longNames += opts;
+            if(static_cast<int>(longNames.length()) >= adjustedLongNamesColumnWidth)
+                longNames += " ";
+
+            out << std::setw(adjustedLongNamesColumnWidth) << std::left << longNames;
+        } else {
+            out << std::setw(adjustedLongNamesColumnWidth) << std::left << "";
+        }
+
+        if(!desc.empty()) {
+            bool skipFirstLinePrefix = true;
+            if(out.str().length() > column_width_) {
+                out << '\n';
+                skipFirstLinePrefix = false;
+            }
+            detail::streamOutAsParagraph(
+                out, desc, right_column_width_, std::string(column_width_, ' '), skipFirstLinePrefix);
+        }
+    }
+
+    out << '\n';
+    return out.str();
+}
+
+CLI11_INLINE std::string Formatter::make_option_name(const Option *opt, bool is_positional) const {
+    if(is_positional)
+        return opt->get_name(true, false);
+
+    return opt->get_name(false, true, !enable_default_flag_values_);
+}
+
+CLI11_INLINE std::string Formatter::make_option_opts(const Option *opt) const {
+    std::stringstream out;
+
+    if(!opt->get_option_text().empty()) {
+        out << " " << opt->get_option_text();
+    } else {
+        if(opt->get_type_size() != 0) {
+            if(enable_option_type_names_) {
+                if(!opt->get_type_name().empty())
+                    out << " " << get_label(opt->get_type_name());
+            }
+            if(enable_option_defaults_) {
+                if(!opt->get_default_str().empty())
+                    out << " [" << opt->get_default_str() << "] ";
+            }
+            if(opt->get_expected_max() == detail::expected_max_vector_size)
+                out << " ...";
+            else if(opt->get_expected_min() > 1)
+                out << " x " << opt->get_expected();
+
+            if(opt->get_required())
+                out << " " << get_label("REQUIRED");
+        }
+        if(!opt->get_envname().empty())
+            out << " (" << get_label("Env") << ":" << opt->get_envname() << ")";
+        if(!opt->get_needs().empty()) {
+            out << " " << get_label("Needs") << ":";
+            for(const Option *op : opt->get_needs())
+                out << " " << op->get_name();
+        }
+        if(!opt->get_excludes().empty()) {
+            out << " " << get_label("Excludes") << ":";
+            for(const Option *op : opt->get_excludes())
+                out << " " << op->get_name();
+        }
+    }
+    return out.str();
+}
+
+CLI11_INLINE std::string Formatter::make_option_desc(const Option *opt) const { return opt->get_description(); }
+
+CLI11_INLINE std::string Formatter::make_option_usage(const Option *opt) const {
+    // Note that these are positionals usages
+    std::stringstream out;
+    out << make_option_name(opt, true);
+    if(opt->get_expected_max() >= detail::expected_max_vector_size)
+        out << "...";
+    else if(opt->get_expected_max() > 1)
+        out << "(" << opt->get_expected() << "x)";
+
+    return opt->get_required() ? out.str() : "[" + out.str() + "]";
+}
+
+
+} // namespace CLI
diff --git a/src/realmachine/lib/cli11/LICENSE b/src/realmachine/lib/cli11/LICENSE
new file mode 100644
index 0000000..dc6d29f
--- /dev/null
+++ b/src/realmachine/lib/cli11/LICENSE
@@ -0,0 +1,25 @@
+CLI11 2.6.2 Copyright (c) 2017-2026 University of Cincinnati, developed by Henry
+Schreiner under NSF AWARD 1414736. All rights reserved.
+
+Redistribution and use in source and binary forms of CLI11, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+3. Neither the name of the copyright holder nor the names of its contributors
+   may be used to endorse or promote products derived from this software without
+   specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/src/realmachine/lib/cli11/cli11_wrapper.cpp b/src/realmachine/lib/cli11/cli11_wrapper.cpp
new file mode 100644
index 0000000..1f64d6a
--- /dev/null
+++ b/src/realmachine/lib/cli11/cli11_wrapper.cpp
@@ -0,0 +1 @@
+#include "CLI11.h"
\ No newline at end of file
diff --git a/src/realmachine/lib/cli11/cli11_wrapper.h b/src/realmachine/lib/cli11/cli11_wrapper.h
new file mode 100644
index 0000000..49e6804
--- /dev/null
+++ b/src/realmachine/lib/cli11/cli11_wrapper.h
@@ -0,0 +1,2 @@
+#pragma once
+#include "CLI11.h"
\ No newline at end of file
diff --git a/src/realmachine/lib/utils.cpp b/src/realmachine/lib/utils.cpp
new file mode 100644
index 0000000..a1cd931
--- /dev/null
+++ b/src/realmachine/lib/utils.cpp
@@ -0,0 +1,318 @@
+#include <sys/utsname.h>
+#include <cmath>
+#include <cstdio>
+#include <cctype>
+#include <cstring>
+#include <stdexcept>
+
+#include <flogger/flogger.h>
+#include <shellescape/shellescape.h>
+
+#include "utils.h"
+
+auto log_realmachine_utils = flogger::bind_log("realmachine/utils");
+
+namespace utils_realmachine {
+
+  std::string human_size_str(const int64_t num) {
+    static const char *units[] = {"", "K", "M", "G", "T", "P"};
+    auto n = static_cast<double>(num);
+
+    for (const char *unit: units) {
+      if (std::abs(n) < 1024.0) {
+        char buf[32];
+        std::snprintf(buf, sizeof(buf), "%.1f%s", n, unit);
+        return {buf};
+      }
+      n /= 1024.0;
+    }
+
+    char buf[32];
+    std::snprintf(buf, sizeof(buf), "%.1fE", n);
+    return {buf};
+  }
+
+  std::string human_time_str(const std::chrono::microseconds &us) {
+    auto t = static_cast<double>(us.count());
+
+    struct Unit {
+      const char *name;
+      double scale;
+    };
+    Unit units[] = {
+        {"µs", 1.0},
+        {"ms", 1000.0},
+        {"s", 1000.0},
+        {"min", 60.0},
+        {"h", 60.0}
+    };
+
+    for (auto &u: units) {
+      if (t < u.scale) {
+        char buf[32];
+        std::snprintf(buf, sizeof(buf), "%.3g%s", t, u.name);
+        return {buf};
+      }
+      t /= u.scale;
+    }
+
+    char buf[32];
+    std::snprintf(buf, sizeof(buf), "%.3gh", t);
+    return {buf};
+  }
+
+  int64_t parse_human_size(const std::string &s) {
+    double value = 0.0;
+    char unit = 0;
+
+    if (std::sscanf(s.c_str(), "%lf%c", &value, &unit) < 1)
+      throw std::invalid_argument("invalid size");
+
+    int exp = 0;
+    switch (unit) {
+      case 'K':
+        exp = 1;
+        break;
+      case 'M':
+        exp = 2;
+        break;
+      case 'G':
+        exp = 3;
+        break;
+      case 'T':
+        exp = 4;
+        break;
+      case 'P':
+        exp = 5;
+        break;
+      case '\0':
+        exp = 0;
+        break;
+      default:
+        throw std::invalid_argument("unknown size unit");
+    }
+
+    double n = value;
+    while (exp-- > 0)
+      n *= 1024.0;
+    return static_cast<int64_t>(n);
+  }
+
+  std::chrono::microseconds parse_human_time(const std::string &s) {
+    double value = 0.0;
+    char unit[8] = {0};
+
+    if (std::sscanf(s.c_str(), "%lf%7s", &value, unit) < 1)
+      throw std::invalid_argument("invalid time");
+
+    double scale = 1.0;
+
+    if (std::strcmp(unit, "µs") == 0 || std::strcmp(unit, "us") == 0)
+      scale = 1.0;
+    else if (std::strcmp(unit, "ms") == 0)
+      scale = 1000.0;
+    else if (std::strcmp(unit, "s") == 0)
+      scale = 1000.0 * 1000.0;
+    else if (std::strcmp(unit, "min") == 0)
+      scale = 60.0 * 1000.0 * 1000.0;
+    else if (std::strcmp(unit, "h") == 0)
+      scale = 60.0 * 60.0 * 1000.0 * 1000.0;
+    else if (unit[0] == '\0')
+      scale = 1.0;
+    else
+      throw std::invalid_argument("unknown time unit");
+
+    return std::chrono::microseconds(static_cast<int64_t>(value * scale));
+  }
+
+  void create_standard_dirs() {
+    if (geteuid() != 0) {
+      throw std::runtime_error("Root privileges are required to create system directories");
+    }
+
+    constexpr std::array<const char *, 3> dirs{
+        "/etc/app",
+        "/var/cache/app",
+        "/var/lib/app"
+    };
+
+    constexpr std::array<const char *, 4> files{
+        "/etc/app/world",
+        "/etc/app/repositories",
+        "/etc/app/keys",
+        "/etc/app/arch"
+    };
+
+    for (auto &&d: dirs) {
+      std::filesystem::create_directories(d);
+    }
+
+    for (auto &&f: files) {
+      if (!std::filesystem::exists(f)) {
+        std::ofstream ofs(f); // create empty file
+      }
+    }
+  }
+
+  void parse_package_version(const std::string& v, uint32_t& major, uint32_t& minor, uint32_t& patch, uint32_t& release) {
+    major = minor = patch = release = 0;
+
+    if (v.empty())
+      throw std::invalid_argument("empty version string");
+
+    std::string ver = v;
+    size_t dash = ver.find('-');
+
+    if (dash != std::string::npos) {
+      std::string r = ver.substr(dash + 1);
+      ver = ver.substr(0, dash);
+
+      if (!r.empty()) {
+        if (r[0] == 'r' || r[0] == 'R')
+          release = std::stoul(r.substr(1));
+        else
+          release = std::stoul(r);
+      }
+    }
+
+    const size_t p1 = ver.find('.');
+    if (p1 == std::string::npos) {
+      major = std::stoul(ver);
+      return;
+    }
+
+    const size_t p2 = ver.find('.', p1 + 1);
+
+    major = std::stoul(ver.substr(0, p1));
+
+    if (p2 == std::string::npos) {
+      minor = std::stoul(ver.substr(p1 + 1));
+      patch = 0;
+      return;
+    }
+
+    minor = std::stoul(ver.substr(p1 + 1, p2 - p1 - 1));
+    patch = std::stoul(ver.substr(p2 + 1));
+  }
+
+  void move_recursive(const std::filesystem::path &src, const std::filesystem::path &dst) {
+    printf_debug(log_realmachine_utils, "src: %s, dst: %s", src.string().c_str(), dst.string().c_str());
+
+    std::error_code ec;
+    std::filesystem::create_directories(dst, ec);
+    if (ec) throw std::runtime_error("Failed to create directory: " + dst.string());
+
+    for (auto &entry : std::filesystem::directory_iterator(src, std::filesystem::directory_options::skip_permission_denied, ec)) {
+      if (ec)
+        throw std::runtime_error("Failed to iterate directory: " + src.string());
+
+      auto target_path = dst / entry.path().filename();
+      const auto st = std::filesystem::symlink_status(entry.path(), ec);
+      if (ec)
+        throw std::runtime_error("Failed to get status for: " + entry.path().string());
+
+      if (std::filesystem::is_directory(st)) {
+        move_recursive(entry.path(), target_path);
+        std::filesystem::remove(entry.path(), ec);
+        if (ec)
+          throw std::runtime_error("Failed to remove directory: " + entry.path().string());
+      } else { // regular file or symlink
+        if (std::filesystem::exists(target_path, ec)) {
+          std::filesystem::remove_all(target_path, ec);
+          if (ec)
+            throw std::runtime_error("Failed to remove existing target: " + target_path.string());
+        }
+        std::filesystem::rename(entry.path(), target_path, ec);
+        if (ec)
+          throw std::runtime_error("Failed to move " + entry.path().string() + " -> " + target_path.string());
+      }
+    }
+  }
+
+  bool has_program(const std::string& name) {
+    const char* path = std::getenv("PATH");
+    if (!path)
+      return false;
+
+    std::string p(path);
+    size_t start = 0;
+
+    while (true) {
+      const size_t end = p.find(':', start);
+      std::string dir = p.substr(start, end == std::string::npos ? std::string::npos : end - start);
+
+      if (!dir.empty()) {
+        std::string full = dir + "/" + name;
+        struct stat st{};
+        if (stat(full.c_str(), &st) == 0 && access(full.c_str(), X_OK) == 0)
+          return true;
+      }
+
+      if (end == std::string::npos)
+        break;
+
+      start = end + 1;
+    }
+
+    return false;
+  }
+
+  std::filesystem::path find_program(const std::string& name) {
+    if (name.find('/') != std::string::npos) {
+      std::filesystem::path p = name;
+      if (std::filesystem::exists(p) && std::filesystem::is_regular_file(p)) {
+        return std::filesystem::absolute(p);
+      }
+      return {};
+    }
+
+    const char* path_env = std::getenv("PATH");
+    if (!path_env) {
+      return {};
+    }
+
+    std::string_view path_sv(path_env);
+    size_t start = 0;
+
+    while (start <= path_sv.size()) {
+      size_t end = path_sv.find(':', start);
+      if (end == std::string_view::npos) {
+        end = path_sv.size();
+      }
+
+      std::filesystem::path dir = std::string(path_sv.substr(start, end - start));
+      std::filesystem::path candidate = dir / name;
+
+      if (std::filesystem::exists(candidate) &&
+          std::filesystem::is_regular_file(candidate)) {
+        return std::filesystem::absolute(candidate);
+          }
+
+      start = end + 1;
+    }
+
+    return {};
+  }
+
+  std::string runtime_arch() {
+    utsname u {};
+    if (uname(&u) != 0) {
+      return "unknown";
+    }
+
+    const std::string machine = u.machine;
+    std::string rtn;
+
+    if (machine == "x86_64") rtn = "amd64";
+    if (machine == "aarch64") rtn = "arm64";
+    if (machine == "armv7l" || machine == "armv6l") rtn = "arm";
+    if (machine == "i386" || machine == "i686") rtn = "386";
+
+    if (!rtn.empty()) {
+      printf_debug(log_realmachine_utils, "arch=%s", rtn.c_str());
+      return rtn;
+    }
+
+    throw std::runtime_error("unsupported architecture");
+  }
+}
diff --git a/src/realmachine/lib/utils.h b/src/realmachine/lib/utils.h
new file mode 100644
index 0000000..f7c7a63
--- /dev/null
+++ b/src/realmachine/lib/utils.h
@@ -0,0 +1,60 @@
+#pragma once
+
+#include <vector>
+#include <string>
+#include <array>
+#include <fstream>
+#include <unistd.h>
+#include <stdexcept>
+#include <cstdlib>
+#include <sys/stat.h>
+#include <filesystem>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/ptrace.h>
+#include <cerrno>
+
+#include <flogger/flogger.h>
+
+namespace utils_realmachine {
+  void create_standard_dirs();
+
+  inline bool endswith(const std::string &str, const std::string &suffix) {
+    return str.size() >= suffix.size() && str.compare(str.size() - suffix.size(), suffix.size(), suffix) == 0;
+  }
+
+  inline bool ensure_directory(const std::string &path) {
+    struct stat st{};
+    if (stat(path.c_str(), &st) != 0)
+      return false;
+    return S_ISDIR(st.st_mode);
+  }
+
+  std::string human_size_str(int64_t num);
+  std::string human_time_str(const std::chrono::microseconds& us);
+  int64_t parse_human_size(const std::string& s);
+  std::chrono::microseconds parse_human_time(const std::string& s);
+
+  inline std::vector<std::string> split_bytes(const std::vector<uint8_t>& bytes, const uint8_t delimiter = ',') {
+    std::vector<std::string> result;
+    size_t start = 0;
+    for (size_t i = 0; i < bytes.size(); ++i) {
+      if (bytes[i] == delimiter) {
+        result.emplace_back(bytes.begin() + start, bytes.begin() + i);
+        start = i + 1;
+      }
+    }
+    if (start < bytes.size())
+      result.emplace_back(bytes.begin() + start, bytes.end());
+    return result;
+  }
+
+  void parse_package_version(const std::string& v, uint32_t& major, uint32_t& minor, uint32_t& patch, uint32_t& release);
+
+  void move_recursive(const std::filesystem::path &src, const std::filesystem::path &dst);
+
+  bool has_program(const std::string& name);
+  std::filesystem::path find_program(const std::string& name);
+
+  std::string runtime_arch();
+}
diff --git a/src/realmachine/machine.cpp b/src/realmachine/machine.cpp
new file mode 100644
index 0000000..f9b5c32
--- /dev/null
+++ b/src/realmachine/machine.cpp
@@ -0,0 +1,1182 @@
+#include <sys/stat.h>
+#include <unistd.h>
+#include <cstdlib>
+#include <cstdio>
+#include <sstream>
+#include <fstream>
+#include <array>
+#include <chrono>
+#include <regex>
+#include <thread>
+
+#include <shellescape/shellescape.h>
+
+#include "template.h"
+#include "machine.h"
+#include "backend.h"
+#include "globals.h"
+#include "lib/utils.h"
+
+auto log_realmachine_machine = flogger::bind_log("realmachine/machine");
+
+using namespace std;
+
+namespace realmachine {
+
+  bool merged_usr_system() {
+    struct stat sb{};
+    if (lstat("/bin", &sb) != 0)
+      return false;
+    return S_ISLNK(sb.st_mode);
+  }
+
+  static const string& modinfo_output(const string &modname, const string &kernel_release) {
+    static unordered_map<string, string> cache;
+
+    const string cache_key = kernel_release + "\n" + modname;
+    if (const auto it = cache.find(cache_key); it != cache.end())
+      return it->second;
+
+    array<char, 4096> buffer{};
+    string out;
+
+    string cmd = "modinfo -k " + kernel_release + " " + modname;
+    FILE *pipe = popen(cmd.c_str(), "r");
+    if (!pipe)
+      throw runtime_error("modinfo failed");
+
+    while (fgets(buffer.data(), buffer.size(), pipe)) {
+      out += buffer.data();
+    }
+    pclose(pipe);
+
+    return cache.emplace(cache_key, std::move(out)).first->second;
+  }
+
+  vector<string> get_mod_data(const string &modname, const string &fieldname, const string &kernel_release) {
+    const string& out = modinfo_output(modname, kernel_release);
+
+    vector<string> field_value;
+    istringstream ss(out);
+    string line;
+
+    while (getline(ss, line)) {
+      line = regex_replace(line, regex("^\\s+|\\s+$"), "");
+
+      vector<string> parts;
+      string tmp;
+      stringstream ls(line);
+
+      while (getline(ls, tmp, ':')) {
+        tmp = regex_replace(tmp, regex("^\\s+|\\s+$"), "");
+        parts.emplace_back(tmp);
+      }
+
+      if (!parts.empty() && parts[0] == fieldname) {
+        if (parts.size() > 1) {
+          field_value.emplace_back(parts[1]);
+        } else {
+          field_value.emplace_back("");
+        }
+      }
+    }
+
+    return field_value;
+  }
+
+  string get_mod_path(const string &modname, const string &kernel_release) {
+    auto paths = get_mod_data(modname, "filename", kernel_release);
+    if (!paths.empty())
+      return paths[0];
+    return "";
+  }
+
+  vector<string> get_mod_depends(const string &modname, const string &kernel_release) {
+    printf_debug(log_realmachine_machine, "enter modname=%s kernel_release=%s", modname.c_str(), kernel_release.c_str());
+
+    static unordered_map<string, vector<string>> resolved;
+    const string cache_key = kernel_release + "\n" + modname;
+    if (const auto it = resolved.find(cache_key); it != resolved.end())
+      return it->second;
+
+    auto deps = get_mod_data(modname, "depends", kernel_release);
+    printf_debug(log_realmachine_machine, "deps_count=%zu modname=%s", deps.size(), modname.c_str());
+
+    vector<string> modlist;
+
+    for (auto &v: deps) {
+      if (!v.empty()) {
+        size_t start = 0;
+        while (true) {
+          size_t pos = v.find(',', start);
+          if (pos == string::npos) {
+            auto token = v.substr(start);
+            if (!token.empty()) modlist.emplace_back(token);
+            printf_trace(log_realmachine_machine, "dep_token mod=%s token=%s", modname.c_str(), token.c_str());
+            break;
+          }
+          auto token = v.substr(start, pos - start);
+          if (!token.empty()) modlist.emplace_back(token);
+          printf_trace(log_realmachine_machine, "dep_token mod=%s token=%s", modname.c_str(), token.c_str());
+          start = pos + 1;
+        }
+      }
+    }
+
+    printf_debug(log_realmachine_machine, "direct_deps_count=%zu modname=%s", modlist.size(), modname.c_str());
+
+    // Busybox expects a full dependency list for each module rather than just
+    // direct dependencies, so recurse the module dependency tree:
+    // https://github.com/mirror/busybox/blob/1dd2685dcc735496d7adde87ac60b9434ed4a04c/modutils/modprobe.c#L46-L49
+
+    vector<string> sublist;
+    for (auto &mod: modlist) {
+      printf_trace(log_realmachine_machine, "recurse mod=%s parent=%s", mod.c_str(), modname.c_str());
+      auto sub = get_mod_depends(mod, kernel_release);
+      printf_trace(log_realmachine_machine, "recurse_done mod=%s sub_count=%zu", mod.c_str(), sub.size());
+      sublist.insert(sublist.end(), sub.begin(), sub.end());
+    }
+
+    modlist.insert(modlist.end(), sublist.begin(), sublist.end());
+
+    printf_debug(log_realmachine_machine, "exit modname=%s total=%zu", modname.c_str(), modlist.size());
+    return resolved.emplace(cache_key, std::move(modlist)).first->second;
+  }
+
+  void Machine::resolve_modules(
+    std::vector<ResolvedModule>& resolved,
+    const std::string& modname,
+    std::unordered_map<std::string, bool>& copied_modules
+  ) {
+    printf_trace(log_realmachine_machine, "enter resolve_modules modname=%s", modname.c_str());
+
+    const auto release = backend->kernel_release();
+    printf_debug(log_realmachine_machine, "kernel release=%s", release.c_str());
+
+    std::string modpath = get_mod_path(modname, release);
+    printf_debug(log_realmachine_machine, "modpath=%s", modpath.c_str());
+
+    if (modpath.empty()) {
+      printf_error(log_realmachine_machine, "modpath empty -> invalid module path");
+      throw std::invalid_argument("invalid module path");
+    }
+
+    if (modpath == "(builtin)" || copied_modules[modname]) {
+      printf_trace(log_realmachine_machine, "skip module modname=%s builtin=%d already_copied=%d",
+                  modname.c_str(),
+                  modpath == "(builtin)",
+                  copied_modules[modname]);
+      return;
+    }
+
+    bool found = false;
+
+    for (auto it = KO_SUFFIXES.begin(); it != KO_SUFFIXES.end(); ++it) {
+      const auto& suffix = it->first;
+      const auto& fn = it->second;
+
+      printf_trace(log_realmachine_machine, "checking suffix=%s", suffix.c_str());
+
+      if (modpath.ends_with(suffix)) {
+        printf_trace(log_realmachine_machine, "suffix match modpath=%s suffix=%s", modpath.c_str(), suffix.c_str());
+
+        if (!std::filesystem::exists(modpath)) {
+          printf_trace(log_realmachine_machine, "module not found at path=%s", modpath.c_str());
+          throw std::filesystem::filesystem_error(
+            "module not found",
+            modpath,
+            std::make_error_code(std::errc::no_such_file_or_directory)
+          );
+        }
+
+        std::string dest =
+          modpath.substr(0, modpath.size() - suffix.size()) + ".ko";
+
+        printf_debug(log_realmachine_machine, "raw dest=%s", dest.c_str());
+
+        if (merged_usr_system() && !dest.starts_with("/usr")) {
+          printf_debug(log_realmachine_machine, "prefixing /usr to dest");
+          dest = "/usr" + dest;
+        }
+
+        printf_debug(log_realmachine_machine, "final dest=%s", dest.c_str());
+
+        if (fn) {
+          printf_trace(log_realmachine_machine, "resolved modpath=%s dest=%s", modpath.c_str(), dest.c_str());
+          resolved.emplace_back(ResolvedModule{modpath, dest, fn});
+        } else {
+          printf_error(log_realmachine_machine, "no transform function for suffix=%s", suffix.c_str());
+        }
+
+        found = true;
+        break;
+      }
+    }
+
+    if (!found) {
+      printf_error(log_realmachine_machine, "no matching suffix for modpath=%s", modpath.c_str());
+      throw std::invalid_argument("invalid module suffix");
+    }
+
+    copied_modules[modname] = true;
+    printf_trace(log_realmachine_machine, "marked copied modname=%s", modname.c_str());
+
+    auto deps = get_mod_depends(modname, release);
+    printf_trace(log_realmachine_machine, "deps count=%zu for modname=%s", deps.size(), modname.c_str());
+
+    for (auto& mod : deps) {
+      printf_trace(log_realmachine_machine, "recursing dependency=%s", mod.c_str());
+      resolve_modules(resolved, mod, copied_modules);
+    }
+
+    printf_debug(log_realmachine_machine, "exit resolve_modules modname=%s", modname.c_str());
+  }
+
+  // Evaluate any symbolic link, then return the path's directory. Returns an
+  // absolute path. Think of it as realpath(1) + dirname(1) in bash.
+  filesystem::path real_dir(const filesystem::path &path) {
+    const auto abs = filesystem::absolute(path);
+
+    std::error_code ec;
+    const auto resolved = filesystem::weakly_canonical(abs, ec);
+    if (ec) {
+      return abs.parent_path();
+    }
+
+    return resolved.parent_path();
+  }
+
+  Machine::Machine() = default;
+
+  shared_ptr<Machine> Machine::new_machine() {
+    if (!realmachine_g::APP_INIT) populate_ko_suffix_map();
+    return new_machine_with_backend("auto");
+  }
+
+  shared_ptr<Machine> Machine::new_machine_with_backend(const string &backend_name) {
+    if (!realmachine_g::APP_INIT) populate_ko_suffix_map();
+    auto m = make_shared<Machine>();
+
+    m->memory = 2048;
+    m->num_cpus = thread::hardware_concurrency();
+    m->sector_size = 512;
+
+    string goarch = utils_realmachine::runtime_arch();
+
+    if (!arch_map.contains(goarch)) {
+      throw runtime_error("unsupported arch " + goarch);
+    }
+
+    m->arch = arch_map[goarch];
+
+    m->backend = new_backend(backend_name, m);
+
+    // usr is mounted by specific label via /init
+    m->add_static_volume("/usr", "usr");
+
+    if (!merged_usr_system()) {
+      m->add_static_volume("/sbin", "sbin");
+      m->add_static_volume("/bin", "bin");
+      m->add_static_volume("/lib", "lib");
+    }
+
+    // Mounts for ssl certificates
+    if (filesystem::exists("/etc/ca-certificates")) {
+      m->add_volume("/etc/ca-certificates");
+    }
+    if (filesystem::exists("/etc/ssl")) {
+      m->add_volume("/etc/ssl");
+    }
+
+    // Mounts for java VM configuration, especially security policies
+    for (auto &p : filesystem::directory_iterator("/etc")) {
+      if (p.is_directory() &&
+          p.path().filename().string().rfind("java", 0) == 0) {
+        m->add_volume(p.path());
+          }
+    }
+
+    // Dbus configuration
+    if (filesystem::exists("/etc/dbus-1")) {
+      m->add_volume("/etc/dbus-1");
+    }
+
+    // Debian alternative symlinks
+    if (filesystem::exists("/etc/alternatives")) {
+      m->add_volume("/etc/alternatives");
+    }
+
+    // Debians binfmt registry
+    if (filesystem::exists("/var/lib/binfmts")) {
+      m->add_volume("/var/lib/binfmts");
+    }
+
+    return m;
+  }
+
+  bool Machine::in_machine() {
+    const bool v = std::getenv("IN_FAKE_MACHINE") != nullptr;
+    // for(char **env = ::environ; env && *env; ++env) {
+    //   printf_debug(log_realmachine_machine, "%s", *env);
+    // }
+    printf_debug(log_realmachine_machine, "IN_FAKE_MACHINE=%d", v);
+    return v;
+  }
+
+  bool supported() {
+    return new_backend("auto", nullptr) != nullptr;
+  }
+
+  std::string join_strings(const std::vector<std::string>& v, const std::string& sep) {
+    std::string out;
+    for (size_t i = 0; i < v.size(); i++) {
+      if (i) out += sep;
+      out += v[i];
+    }
+    return out;
+  }
+
+  std::string tmpl_mount_volume(const std::unique_ptr<Backend>& b, const std::shared_ptr<MountPoint>& m) {
+    auto [fs_type, options] = b->mount_parameters(m);
+
+    std::vector<std::string> cmd;
+    cmd.emplace_back("busybox");
+    cmd.emplace_back("mount");
+    cmd.emplace_back("-v");
+
+    cmd.emplace_back("-t");
+    cmd.emplace_back(fs_type);
+
+    if (!options.empty()) {
+      cmd.emplace_back("-o");
+      cmd.emplace_back(join_strings(options, ","));
+    }
+
+    cmd.emplace_back(m->label);
+    cmd.emplace_back(m->machine_directory.string());
+
+    return join_strings(cmd, " ");
+  }
+
+  std::vector<std::shared_ptr<MountPoint>> tmpl_static_volumes(
+    const Machine& m,
+    const std::unique_ptr<Backend>& b
+  ) {
+    std::vector<std::shared_ptr<MountPoint>> mounts;
+
+    auto combined = m.mounts;
+    auto backend_vols = b->init_static_volumes();
+
+    combined.insert(combined.end(), backend_vols.begin(), backend_vols.end());
+
+    for (const auto& mount : combined) {
+      if (mount->is_static) {
+        mounts.emplace_back(mount);
+      }
+    }
+
+    return mounts;
+  }
+
+  std::string build_service_env(const Machine& m) {
+    return join_strings(m.environ, " ");
+  }
+
+  std::string build_init_script(const Machine* m, const std::unique_ptr<Backend>& b) {
+    std::vector<std::string> modprobe_lines;
+
+    for (const auto& mod : b->init_modules()) {
+      modprobe_lines.emplace_back("busybox modprobe " + mod);
+    }
+
+    std::vector<std::string> mount_lines;
+
+    auto vols = tmpl_static_volumes(*m, b);
+    for (const auto& v : vols) {
+      mount_lines.emplace_back(tmpl_mount_volume(b, v));
+    }
+
+    return templating::get_init_script(
+      join_strings(modprobe_lines, "\n"),
+      join_strings(mount_lines, "\n")
+    );
+  }
+
+  std::string build_command_wrapper(const std::string& command) {
+    return templating::get_command_wrapper(command);
+  }
+
+  std::string render_service(const Machine& m, const std::string& tty) {
+    return templating::get_service(
+      build_service_env(m),
+      tty
+    );
+  }
+
+  void Machine::add_static_volume(const std::filesystem::path& directory, const std::string& label) {
+    printf_debug(log_realmachine_machine, "host=%s machine=%s label=%s static=%d",
+      directory.string().c_str(),
+      directory.c_str(),
+      label.c_str(),
+      true
+    );
+
+    // usr is mounted by specific label via /init
+    auto m = std::make_shared<MountPoint>();
+    m->host_directory = directory;
+    m->machine_directory = directory;
+    m->label = label;
+    m->is_static = true;
+
+    mounts.emplace_back(m);
+  }
+
+  void Machine::add_volume_at(const std::string& host_directory, const std::string& machine_directory) {
+    std::string label = "virtfs-" + std::to_string(count_);
+
+    for (const auto& mount : mounts) {
+      if (mount->host_directory == host_directory &&
+          mount->machine_directory == machine_directory) {
+        // Do not need to add already existing mount
+        return;
+      }
+    }
+
+    printf_trace(log_realmachine_machine, "mount_add host=%s machine=%s label=%s readonly=%d",
+      host_directory.c_str(),
+      machine_directory.c_str(),
+      label.c_str(),
+      false
+    );
+
+    mounts.emplace_back(std::make_shared<MountPoint>(
+      host_directory,
+      machine_directory,
+      label,
+      false
+    ));
+
+    count_ += 1;
+  }
+
+  void Machine::add_volume(const std::filesystem::path& directory) {
+    if (directory.empty())
+      throw std::invalid_argument("add_volume: directory is empty");
+    add_volume_at(directory, directory);
+  }
+
+  // CreateImageWithLabel creates an image file at path a given size and exposes
+  // it in the fake machine using the given label as the serial id. If size is -1
+  // then the image should already exist and the size isn't modified.
+  //
+  // label needs to be less than 20 characters due to limitations from qemu
+  //
+  // The returned string is the device path of the new image as seen inside
+  // realmachine.
+  std::string Machine::create_image_with_label(const std::string& path, int64_t size, const std::string& label) {
+    printf_debug(log_realmachine_machine, "enter path=%s size=%ld label=%s", path.c_str(), size, label.c_str());
+
+    if (size < 0) {
+      std::filesystem::file_status st = std::filesystem::status(path);
+    }
+
+    if (label.size() >= 20) {
+      printf_trace(log_realmachine_machine, "label_too_long len=%zu label=%s", label.size(), label.c_str());
+      throw std::invalid_argument("label too long");
+    }
+
+    for (const auto& image : images) {
+      if (image->label == label) {
+        printf_trace(log_realmachine_machine, "duplicate_label label=%s", label.c_str());
+        throw std::invalid_argument("duplicate label");
+      }
+    }
+
+    std::filesystem::path p(path);
+
+    std::ofstream i(p, std::ios::binary | std::ios::out | std::ios::trunc);
+    if (!i.is_open()) {
+      printf_trace(log_realmachine_machine, "file_open_failed path=%s", path.c_str());
+      throw std::runtime_error("file open failed");
+    }
+
+    if (size >= 0) {
+      std::filesystem::resize_file(p, static_cast<std::uintmax_t>(size));
+    }
+
+    i.close();
+
+    images.emplace_back(make_unique<Image>(path, label));
+    printf_debug(log_realmachine_machine, "image_created path=%s label=%s rtn=%s", path.c_str(), label.c_str(), std::string("/dev/disk/by-realmachine-label/" + label).c_str());
+
+    return "/dev/disk/by-realmachine-label/" + label;
+  }
+
+  // CreateImage does the same as CreateImageWithLabel but lets the library pick the label.
+  std::string Machine::create_image(const std::string& imagepath,const int64_t size) {
+    const std::string label = "fakedisk-" + std::to_string(images.size());
+    printf_debug(log_realmachine_machine, "%s", label.c_str());
+    return create_image_with_label(imagepath, size, label);
+  }
+
+  // SetMemory sets the realmachines amount of memory (in megabytes). Defaults to 2048 MB
+  void Machine::set_memory(int new_memory) {
+    printf_debug(log_realmachine_machine, "set_memory %d", new_memory);
+    memory = new_memory;
+  }
+
+  // SetNumCPUs sets the number of CPUs exposed to the realmachine. Defaults to
+  // the number of available cores in the system.
+  void Machine::set_num_cpus(int new_num_cpus) {
+    printf_debug(log_realmachine_machine, "set_num_cpus %d", new_num_cpus);
+    num_cpus = new_num_cpus;
+  }
+
+  // SetSectorSize overrides the default sector size(512 bytes) for the image exposed to the realmachine
+  void Machine::set_sector_size(int new_sector_size) {
+    printf_debug(log_realmachine_machine, "set_sector_size %d", new_sector_size);
+    sector_size = new_sector_size;
+  }
+
+  // SetShowBoot sets whether to show boot/console messages from the realmachine.
+  void Machine::set_show_boot(bool show_boot_status) {
+    printf_debug(log_realmachine_machine, "set_show_boot %d", show_boot_status);
+    show_boot = show_boot_status;
+  }
+
+  // SetQuiet sets whether realmachine should print additional information (e.g. the command
+  // to be ran) or just print the stdout/stderr of the command to be ran.
+  void Machine::set_quiet(bool quiet_status) {
+    printf_debug(log_realmachine_machine, "set_quiet %d", quiet_status);
+    quiet = quiet_status;
+  }
+
+  void Machine::set_module_cache(const bool enabled, const std::string& path) {
+    module_cache = enabled;
+    module_cache_path = path;
+  }
+
+  // SetScratch sets the size and location of on-disk scratch space to allocate
+  // (sparsely) for /scratch. If not set /scratch will be backed by memory. If
+  // Path is "" then the working directory is used as a default storage location
+  void Machine::set_scratch(int64_t new_scratch_size, const std::string& path) {
+    scratch_size = new_scratch_size;
+
+    if (path.empty()) {
+      scratch_path = std::filesystem::current_path().string();
+    } else {
+      scratch_path = path;
+    }
+  }
+
+  void Machine::generate_fstab(cpio::WriterHelper* w, const std::unique_ptr<Backend>& backend) const {
+    std::vector<std::string> fstab;
+    fstab.emplace_back("# Generated fstab file by realmachine");
+
+    if (scratch_file.empty()) {
+      fstab.emplace_back("none /scratch tmpfs size=95% 0 0");
+    } else {
+      fstab.emplace_back(
+        scratch_dev + std::string(" /scratch ext4 defaults,relatime 0 0")
+      );
+    }
+
+    for (const auto& point : mounts) {
+      auto [fstype, options] = backend->mount_parameters(point);
+
+      std::string opt_joined;
+      for (size_t i = 0; i < options.size(); ++i) {
+        if (i) opt_joined += ",";
+        opt_joined += options[i];
+      }
+
+      fstab.emplace_back(
+        point->label + " " +
+        point->machine_directory.string() + " " +
+        fstype + " " +
+        opt_joined +
+        " 0 0"
+      );
+    }
+
+    fstab.emplace_back("");
+
+    w->write_file(
+      "/etc/fstab",
+      [&]() {
+        std::string out;
+        for (size_t i = 0; i < fstab.size(); ++i) {
+          if (i) out += "\n";
+          out += fstab[i];
+        }
+        return out;
+      }(),
+      0755
+    );
+  }
+
+  std::string strip_compression_suffix(const std::string& module) {
+    printf_debug(log_realmachine_machine, "enter strip_compression_suffix module=%s", module.c_str());
+
+    for (const auto& [suffix, _] : KO_SUFFIXES) {
+      if (module.size() >= suffix.size() &&
+          module.compare(module.size() - suffix.size(),
+                         suffix.size(),
+                         suffix) == 0) {
+
+        return module.substr(0, module.size() - suffix.size()) + ".ko";
+      }
+    }
+
+    printf_debug(log_realmachine_machine, "no suffix match module=%s", module.c_str());
+    return "";
+  }
+
+  std::string Machine::generate_modules_dep(
+    const std::unordered_map<std::string, bool>& modules
+  ) const {
+    printf_debug(log_realmachine_machine, "generate_modules_dep: start modules=%zu", modules.size());
+
+    std::vector<std::string> output;
+    output.resize(modules.size());
+
+    const std::string release = backend->kernel_release();
+    printf_trace(log_realmachine_machine, "generate_modules_dep: kernel_release=%s", release.c_str());
+
+    size_t i = 0;
+    for (const auto& mod : modules) {
+      printf_trace(log_realmachine_machine, "generate_modules_dep: mod=%s", mod.first.c_str());
+
+      std::string modpath =
+        strip_compression_suffix(get_mod_path(mod.first, release));
+
+      auto deplist = get_mod_depends(mod.first, release);
+
+      std::vector<std::string> deps;
+      deps.resize(deplist.size());
+
+      for (size_t j = 0; j < deplist.size(); ++j) {
+        const std::string dep_path =
+          strip_compression_suffix(get_mod_path(deplist[j], release));
+        deps[j] = dep_path;
+      }
+
+      std::string joined;
+      for (size_t k = 0; k < deps.size(); ++k) {
+        if (k) joined += " ";
+        joined += deps[k];
+      }
+
+      if (modpath == "(builtin)") {
+        modpath.clear();
+      }
+
+      output[i] = modpath + ": " + joined;
+      i++;
+    }
+
+    std::string out;
+    for (size_t k = 0; k < output.size(); ++k) {
+      if (k) out += "\n";
+      out += output[k];
+    }
+
+    printf_debug(log_realmachine_machine, "generate_modules_dep: done");
+    return out;
+  }
+
+  void Machine::set_environ(const std::vector<std::string>& new_environ) {
+    environ = new_environ;
+  }
+
+  void Machine::writer_kernel_modules(
+    cpio::WriterHelper* w,
+    const std::string& moddir,
+    const std::vector<std::string>& modules
+  ) {
+    printf_debug(log_realmachine_machine, "start moddir=%s modules=%zu",
+                moddir.c_str(), modules.size());
+
+    if (modules.empty()) {
+      printf_trace(log_realmachine_machine, "skipped (no modules)");
+      return;
+    }
+
+    std::vector<std::string> modfiles = {
+      "modules.builtin",
+      "modules.alias",
+      "modules.symbols"
+    };
+
+    for (const auto& v : modfiles) {
+      std::string path = moddir + "/" + v;
+      printf_trace(log_realmachine_machine, "copy_file=%s", path.c_str());
+      w->copy_file(path);
+    }
+
+    const auto cache_base = module_cache_path.empty()
+      ? default_module_cache_directory()
+      : module_cache_path;
+
+    const auto cache_dir = cache_base /
+      module_cache_key(backend->kernel_release(), moddir, modules, merged_usr_system());
+
+    ModuleSet set;
+    std::filesystem::path staging;
+
+    if (!module_cache || !module_cache_load(cache_dir, set)) {
+      printf_debug(log_realmachine_machine, "writer_kernel_modules: decompressing modules (cache=%d)", module_cache);
+
+      staging = module_cache
+        ? cache_base / (cache_dir.filename().string() + ".tmp." + std::to_string(getpid()))
+        : std::filesystem::temp_directory_path() / ("realmachine-modules." + std::to_string(getpid()));
+
+      std::error_code ec;
+      std::filesystem::remove_all(staging, ec);
+      std::filesystem::create_directories(staging, ec);
+      if (ec) {
+        throw std::runtime_error("cannot create module staging directory " + staging.string() + ": " + ec.message());
+      }
+
+      set = build_module_set(moddir, modules, staging);
+
+      if (module_cache) {
+        module_cache_store(staging, cache_dir, set);
+      }
+    }
+
+    for (const auto& file : set.files) {
+      printf_trace(log_realmachine_machine, "writer_kernel_modules: copy %s -> %s", file[0].c_str(), file[1].c_str());
+      w->copy_file_to(file[0], file[1]);
+    }
+
+    w->write_file(
+      (std::filesystem::path(moddir) / "modules.dep").string(),
+      set.modules_dep,
+      0644
+    );
+
+    if (!staging.empty()) {
+      std::error_code ec;
+      std::filesystem::remove_all(staging, ec);
+    }
+
+    printf_trace(log_realmachine_machine, "writer_kernel_modules: done");
+  }
+
+  ModuleSet Machine::build_module_set(
+    const std::string& moddir,
+    const std::vector<std::string>& modules,
+    const std::filesystem::path& staging
+  ) {
+    std::vector<ResolvedModule> resolved;
+    std::unordered_map<std::string, bool> copied_modules;
+
+    for (const auto& modname : modules) {
+      printf_trace(log_realmachine_machine, "build_module_set: resolve=%s", modname.c_str());
+      resolve_modules(resolved, modname, copied_modules);
+    }
+
+    ModuleSet set;
+    set.modules_dep = generate_modules_dep(copied_modules);
+
+    for (size_t i = 0; i < resolved.size(); ++i) {
+      const auto blob = staging / (std::to_string(i) + ".ko");
+
+      std::ifstream src(resolved[i].source, std::ios::binary);
+      if (!src.is_open()) {
+        throw std::runtime_error("cannot read kernel module " + resolved[i].source);
+      }
+
+      std::ofstream dst(blob, std::ios::binary | std::ios::trunc);
+      if (!dst.is_open()) {
+        throw std::runtime_error("cannot write module cache blob " + blob.string());
+      }
+
+      resolved[i].transformer(dst, src);
+      dst.close();
+
+      set.files.push_back({blob.string(), resolved[i].destination});
+    }
+
+    return set;
+  }
+
+  void Machine::setup_scratch() {
+    printf_debug(log_realmachine_machine, "setup_scratch: start");
+
+    if (scratch_size == 0) {
+      printf_debug(log_realmachine_machine, "setup_scratch: skipped (scratch_size=0)");
+      return;
+    }
+
+    std::filesystem::path tmpfile =
+      std::filesystem::temp_directory_path();
+
+    tmpfile /= "fake-scratch.img.";
+    printf_trace(log_realmachine_machine, "setup_scratch: tmpfile=%s", tmpfile.string().c_str());
+
+    std::ofstream f(tmpfile, std::ios::binary);
+    if (!f.is_open()) {
+      printf_trace(log_realmachine_machine, "setup_scratch: failed to open file");
+      throw std::system_error(std::make_error_code(std::errc::io_error));
+    }
+
+    scratch_file = tmpfile.string();
+    printf_debug(log_realmachine_machine, "setup_scratch: scratch_file=%s", scratch_file.c_str());
+
+    auto res = create_image_with_label(
+      tmpfile.string(),
+      scratch_size,
+      "fake-scratch"
+    );
+
+    if (res.empty()) {
+      printf_error(log_realmachine_machine, "create_image_with_label failed");
+      throw std::runtime_error("create_image_with_label failed");
+    }
+
+    scratch_dev = res;
+    printf_trace(log_realmachine_machine, "setup_scratch: scratch_dev=%s", scratch_dev.c_str());
+
+    std::string cmd = "mkfs.ext4 -q " + tmpfile.string();
+    printf_trace(log_realmachine_machine, "setup_scratch: cmd=%s", cmd.c_str());
+
+    int rc = std::system(cmd.c_str());
+    if (rc != 0) {
+      printf_error(log_realmachine_machine, "setup_scratch: mkfs failed rc=%d", rc);
+      throw std::system_error(std::make_error_code(std::errc::io_error));
+    }
+
+    printf_trace(log_realmachine_machine, "setup_scratch: done");
+  }
+
+  void Machine::cleanup() {
+    if (!scratch_file.empty()) {
+      std::filesystem::remove(scratch_file);
+    }
+
+    scratch_file.clear();
+  }
+
+  // Start the machine running the given command and adding the extra content to
+  // the cpio. Extracontent is a list of {source, dest} tuples
+  int Machine::startup(const std::string& command, const std::vector<std::array<std::string, 2>>& extracontent) {
+    flogger::load_env();
+#ifdef DEBUG
+    flogger::enable_time_measurement(true);
+    flogger::set_log_level(flogger::log_level::trace);
+#endif
+
+    cleanup();
+    std::filesystem::path tmpdir_path;
+    std::string content;
+
+    setenv("PATH", (std::string(getenv("PATH")) + ":/sbin:/usr/sbin").c_str(), 1);
+
+    /* Sanity check mountpoints */
+    for(const auto& v : mounts) {
+      const auto stat = std::filesystem::status(v->host_directory);
+      if(!std::filesystem::is_directory(stat)) {
+        if (realmachine_g::APP_THROW_ON_BAD_MOUNTS) {
+          printf_error(log_realmachine_machine, "invalid mountpoint host_directory=%s label=%s reason=not_a_directory", v->host_directory.c_str(), v->label.c_str());
+          throw std::invalid_argument("invalid mountpoint");
+        } else {
+          return -1;
+        }
+      }
+
+      if(std::regex_search(v->machine_directory.string(), std::regex("\\s"))) {
+        if (realmachine_g::APP_THROW_ON_BAD_MOUNTS) {
+          printf_error(log_realmachine_machine, "invalid mountpoint machine_directory=%s label=%s reason=whitespace", v->machine_directory.string().c_str(), v->label.c_str());
+          throw std::invalid_argument("invalid mountpoint");
+        } else {
+          return -1;
+        }
+      }
+
+      if(std::regex_search(v->label, std::regex("\\s"))) {
+        if (realmachine_g::APP_THROW_ON_BAD_MOUNTS) {
+          printf_error(log_realmachine_machine, "invalid mountpoint label=%s reason=whitespace", v->label.c_str());
+          throw std::invalid_argument("invalid mountpoint");
+        } else {
+          return -1;
+        }
+      }
+    }
+
+    tmpdir_path = std::filesystem::temp_directory_path();
+    auto epoch = std::chrono::duration_cast<std::chrono::seconds>(std::chrono::system_clock::now().time_since_epoch()).count();
+    tmpdir_path /= "realmachine-" + std::to_string(epoch);
+    printf_debug(log_realmachine_machine, "tmpdir_path=%s", tmpdir_path.string().c_str());
+
+    std::string tmpdir = tmpdir_path.string();
+    std::filesystem::create_directories(tmpdir_path);
+
+    add_volume_at(tmpdir, "/run/realmachine");
+    std::filesystem::remove_all(tmpdir_path);
+
+    setup_scratch();
+
+    std::filesystem::create_directory(tmpdir_path);
+    initrd_path = std::filesystem::path(tmpdir) / "initramfs.cpio";
+
+    const auto cpio_start = std::chrono::steady_clock::now();
+
+    std::ofstream f(initrd_path, std::ios::binary | std::ios::out | std::ios::trunc);
+    if (!f.is_open()) {
+      throw std::runtime_error("io error");
+    }
+
+    std::string kernel_module_dir = backend->module_path();
+    if (kernel_module_dir.empty()) {
+      throw std::runtime_error("not supported");
+    }
+
+    auto *w = new cpio::WriterHelper(f);
+
+    w->write_directories({
+      {"/scratch", 01777},
+      {"/var/tmp", 01777},
+      {"/var/lib/dbus", 0755},
+      {"/tmp", 01777},
+      {"/sys", 0755},
+      {"/proc", 0755},
+      {"/run", 0755},
+      {"/usr", 0755},
+      {"/usr/bin", 0755},
+      {"/lib64", 0755}
+    });
+
+    w->write_symlink("/run", "/var/run", 0755);
+
+    if (merged_usr_system()) {
+      w->write_symlinks({
+        {"/usr/sbin", "/sbin", 0755},
+        {"/usr/bin", "/bin", 0755},
+        {"/usr/lib", "/lib", 0755},
+        {"/usr/lib64", "/lib64", 0755}
+      });
+    } else {
+      w->write_directories({
+        {"/sbin", 0744},
+        {"/bin", 0755},
+        {"/lib", 0755}
+      });
+    }
+
+    std::string prefix;
+    if (merged_usr_system()) {
+      prefix = "/usr";
+    }
+
+    // search for busybox. note: in some distros it's located under /sbin
+    auto busybox = std::filesystem::path(utils_realmachine::find_program("busybox"));
+    if (busybox.empty()) {
+      throw std::runtime_error("busybox not found");
+    }
+
+    w->copy_file_to(busybox.string(), prefix + "/bin/busybox");
+
+    /* Ensure systemd-resolved is available */
+    if (!std::filesystem::exists("/lib/systemd/systemd-resolved")) {
+      throw std::runtime_error("systemd-resolved missing");
+    }
+
+    std::string dynamic_linker = arch_dynamic_linker[arch];
+    w->copy_file(prefix + dynamic_linker);
+
+    /* C libraries */
+    std::string library_dir = real_dir(dynamic_linker);
+    if (library_dir.empty()) {
+      throw std::runtime_error("missing library dir");
+    }
+
+    w->copy_file(library_dir + "/libc.so.6");
+    w->copy_file(library_dir + "/libresolv.so.2");
+
+    w->write_char_device("/dev/console", 5, 1, 0700);
+
+    // Linker configuration
+    w->copy_file("/etc/ld.so.conf");
+    w->copy_tree("/etc/ld.so.conf.d");
+
+    // Core system configuration
+    w->write_file("/etc/machine-id", "", 0444);
+    w->write_file("/etc/hostname", "realmachine", 0444);
+
+    w->copy_file("/etc/passwd");
+    w->copy_file("/etc/group");
+    w->copy_file("/etc/nsswitch.conf");
+
+    // udev rules
+    std::string udev_joined;
+    for (const auto& r : backend->udev_rules()) {
+      udev_joined += r;
+      udev_joined += "\n";
+    }
+
+    w->write_file(
+      "/etc/udev/rules.d/61-realmachine.rules",
+      udev_joined,
+      0444
+    );
+
+    w->write_file(
+      "/etc/systemd/network/ethernet.network",
+      templating::networkdTemplate,
+      0444
+    );
+
+    w->write_file(
+      "/etc/systemd/network/10-ethernet.link",
+      templating::networkdLinkTemplate,
+      0444
+    );
+
+    w->write_symlink(
+      "/lib/systemd/resolv.conf",
+      "/etc/resolv.conf",
+      0755
+    );
+
+    const auto modules_start = std::chrono::steady_clock::now();
+    writer_kernel_modules(w, kernel_module_dir, backend->init_modules());
+    printf_trace(log_realmachine_machine, "TIMING pre_modules=%ldms kernel_modules=%ldms",
+      std::chrono::duration_cast<std::chrono::milliseconds>(modules_start - cpio_start).count(),
+      std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::steady_clock::now() - modules_start).count());
+
+    // realmachine.service
+    std::string env_joined;
+    for (size_t i = 0; i < environ.size(); ++i) {
+      if (i) env_joined += " ";
+      env_joined += environ[i];
+    }
+
+    content = templating::get_service(env_joined, backend->job_output_tty());
+
+    printf_info(log_realmachine_machine, "etc/systemd/system/realmachine.service: %s", content.c_str());
+
+    w->write_file(
+      "etc/systemd/system/realmachine.service",
+      content,
+      0644
+    );
+
+    w->write_symlink(
+      "/lib/systemd/system/serial-getty@ttyS0.service",
+      "/dev/null",
+      0755
+    );
+
+    // /wrapper
+    std::string wrapper_content = templating::get_command_wrapper(command);
+    printf_info(log_realmachine_machine, "/wrapper: %s", wrapper_content.c_str());
+
+    w->write_file(
+      "/wrapper",
+      wrapper_content,
+      0755
+    );
+
+    auto init_script = build_init_script(this, backend);
+
+    if (init_script.empty()) {
+      throw std::invalid_argument("invalid init script");
+    }
+
+    w->write_file_raw(
+      "/init",
+      std::vector<char>(init_script.begin(), init_script.end()),
+      0755
+    );
+
+    generate_fstab(w, backend);
+
+    for (const auto& v : extracontent) {
+      w->copy_file_to(v[0], v[1]);
+    }
+
+    w->writer->close();
+    f.close();
+
+    printf_trace(log_realmachine_machine, "TIMING total_cpio=%ldms",
+      std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::steady_clock::now() - cpio_start).count());
+
+    if (!quiet) {
+      printf_info(log_realmachine_machine, "Running %s using %s backend", command.c_str(), backend->name().c_str());
+    }
+
+    const bool success = backend->start();
+    if (!success) {
+      throw std::runtime_error("backend start failed");
+    }
+
+    std::filesystem::path result_path = std::filesystem::path(tmpdir) / "result";
+    std::ifstream result(result_path);
+    printf_debug(log_realmachine_machine, "checking result file: %s", result_path.string().c_str());
+    if (!result.is_open()) {
+      throw std::runtime_error("missing result file");
+    }
+
+    std::string exit_str;
+    std::getline(result, exit_str);
+
+    if (tmpdir_path.filename().string().rfind("realmachine", 0) == 0) {
+      printf_debug(log_realmachine_machine, "removing %s", tmpdir_path.filename().string().c_str());
+      std::filesystem::remove_all(tmpdir_path);
+    }
+
+    return std::stoi(exit_str);
+  }
+
+  int Machine::run_in_machine_with_args(const std::vector<std::string>& args) {
+    const std::string host_exe = executable_name;
+    printf_debug(log_realmachine_machine, "host_exe=%s", host_exe.c_str());
+    if (host_exe.empty()) {
+      throw std::runtime_error("executable_name not set");
+    }
+
+    const std::filesystem::path exe_path(host_exe);
+    const std::filesystem::path name =
+      std::filesystem::path("/") / exe_path.filename();
+
+    printf_trace(log_realmachine_machine, "resolved target name: %s", name.string().c_str());
+
+    const std::string quoted_args = shellescape::quote_command(args);
+    const std::string command = name.string() + " " + quoted_args;
+
+    printf_debug(log_realmachine_machine, "final command: %s", command.c_str());
+
+    const std::filesystem::path executable = utils_realmachine::find_program(host_exe);
+
+    printf_trace(log_realmachine_machine, "resolved executable: %s", executable.string().c_str());
+
+    if (executable.empty()) {
+      throw std::runtime_error("failed to find executable");
+    }
+
+    std::vector<std::array<std::string, 2>> extracontent = {
+      {executable.string(), name.string()}
+    };
+
+    printf_trace(log_realmachine_machine, "prepared extracontent mapping: host=%s guest=%s",
+                executable.string().c_str(),
+                name.string().c_str());
+
+    return startup(command, extracontent);
+  }
+
+  // Run creates the machine running the given command
+  int Machine::run(const std::string& command) {
+    return startup(command, {});
+  }
+
+  // RunInMachine runs the caller binary inside the realmachine with the same
+  // commandline arguments as the parent
+  int Machine::run_in_machine() {
+    return run_in_machine_with_args(
+      std::vector(argv.begin() + 1, argv.end())
+    );
+  }
+}
diff --git a/src/realmachine/machine.h b/src/realmachine/machine.h
new file mode 100644
index 0000000..3c6a8ec
--- /dev/null
+++ b/src/realmachine/machine.h
@@ -0,0 +1,94 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <map>
+#include <filesystem>
+#include <functional>
+#include <memory>
+
+#include <cpiocpplame/writerhelper.h>
+
+#include "models.h"
+#include "module_cache.h"
+
+namespace realmachine {
+  class Backend;
+
+  struct ResolvedModule {
+    std::string source;
+    std::string destination;
+    cpio::Transformer transformer;
+  };
+
+  class Machine {
+  public:
+    Machine();
+    Arch arch = Arch::amd64;
+    std::unique_ptr<Backend> backend;
+    std::vector<std::shared_ptr<MountPoint>> mounts;
+    std::vector<std::unique_ptr<Image>> images;
+    std::string executable_name;
+    uint32_t memory = 2048;
+    uint8_t num_cpus = 0;
+    uint32_t sector_size = 512;
+    bool show_boot = false;
+    bool quiet = false;
+
+    bool module_cache = true;
+    std::filesystem::path module_cache_path;
+
+    int64_t scratch_size = 0;
+    std::filesystem::path scratch_path;
+    std::filesystem::path scratch_file;
+    std::string scratch_dev;
+
+    std::filesystem::path initrd_path;
+    std::vector<std::string> argv;
+    std::vector<std::string> environ;
+
+    static std::shared_ptr<Machine> new_machine();
+    static std::shared_ptr<Machine> new_machine_with_backend(const std::string &backend_name);
+    int startup(const std::string& command, const std::vector<std::array<std::string, 2>>& extracontent);
+
+    int run(const std::string& command);
+    int run_in_machine_with_args(const std::vector<std::string>& args);
+    int run_in_machine();
+
+    void add_volume(const std::filesystem::path &directory);
+    std::string create_image_with_label(const std::string &path, int64_t size, const std::string &label);
+    std::string create_image(const std::string &imagepath, int64_t size);
+    void set_memory(int new_memory);
+    void set_num_cpus(int new_num_cpus);
+    void set_sector_size(int new_sector_size);
+    void set_show_boot(bool show_boot_status);
+    void set_quiet(bool quiet_status);
+    void set_scratch(int64_t new_scratch_size, const std::string &path);
+    void set_module_cache(bool enabled, const std::string &path = "");
+    std::string generate_modules_dep(const std::unordered_map<std::string, bool> &modules) const;
+    void set_environ(const std::vector<std::string> &new_environ);
+    void writer_kernel_modules(cpio::WriterHelper *w, const std::string &moddir, const std::vector<std::string> &modules);
+    void setup_scratch();
+    void cleanup();
+    void add_static_volume(const std::filesystem::path &host, const std::string &label);
+    void add_volume_at(const std::string &host_directory, const std::string &machine_directory);
+
+    static bool in_machine();
+
+  private:
+    void resolve_modules(std::vector<ResolvedModule> &resolved, const std::string &modname, std::unordered_map<std::string, bool> &copied_modules);
+    ModuleSet build_module_set(const std::string &moddir, const std::vector<std::string> &modules, const std::filesystem::path &staging);
+    void generate_fstab(cpio::WriterHelper* w, const std::unique_ptr<Backend>& backend) const;
+
+    int count_ = 0;
+  };
+
+  bool merged_usr_system();
+  std::vector<std::string> get_mod_data(const std::string &modname, const std::string &fieldname, const std::string &kernel_release);
+  std::string get_mod_path(const std::string &modname, const std::string &kernel_release);
+  std::vector<std::string> get_mod_depends(const std::string &modname, const std::string &kernel_release);
+  std::filesystem::path real_dir(const std::filesystem::path &path);
+  std::string tmpl_mount_volume(std::unique_ptr<Backend>& b, const std::shared_ptr<MountPoint> &m);
+  std::vector<std::shared_ptr<MountPoint>> tmpl_static_volumes(const Machine& m, const std::unique_ptr<Backend>& b);
+  std::vector<uint8_t> execute_init_script_template(const Machine* m, const std::unique_ptr<Backend>& b);
+}
diff --git a/src/realmachine/models.cpp b/src/realmachine/models.cpp
new file mode 100644
index 0000000..37562bb
--- /dev/null
+++ b/src/realmachine/models.cpp
@@ -0,0 +1,22 @@
+#include "models.h"
+#include "decompressors.h"
+
+namespace realmachine {
+
+  std::map<std::string, cpio::Transformer> KO_SUFFIXES = {
+     {".ko", nullptr},
+     {".ko.gz", nullptr},
+     {".ko.xz", nullptr},
+     {".ko.zst", nullptr}
+  };
+
+  void populate_ko_suffix_map() {
+    KO_SUFFIXES = {
+      {".ko", decompressors::null_decompressor},
+      {".ko.gz", decompressors::gzip_decompressor},
+      {".ko.xz", decompressors::xz_decompressor},
+      {".ko.zst", decompressors::zstd_decompressor}
+    };
+  }
+
+}
\ No newline at end of file
diff --git a/src/realmachine/models.h b/src/realmachine/models.h
new file mode 100644
index 0000000..e522dca
--- /dev/null
+++ b/src/realmachine/models.h
@@ -0,0 +1,44 @@
+#pragma once
+#include <map>
+#include <string>
+#include <filesystem>
+
+#include <cpiocpplame/writerhelper.h>
+
+namespace realmachine {
+  extern std::map<std::string, cpio::Transformer> KO_SUFFIXES;
+  void populate_ko_suffix_map();
+
+  struct QemuMachine {
+    std::string binary;
+    std::string console;
+    std::string machine;
+    std::string qemu_cpu;
+  };
+
+  enum class Arch {
+    amd64,
+    arm64
+  };
+
+  static QemuMachine qemu_machine_amd64 = {"qemu-system-x86_64", "ttyS0", "pc", ""};
+  static QemuMachine qemu_machine_arm64 = {"qemu-system-aarch64", "ttyAMA0", "virt", "cortex-a53"};
+  static std::map<std::string, Arch> arch_map = {{"amd64", Arch::amd64}, {"arm64", Arch::arm64}, {"aarch64", Arch::arm64}};
+
+  static std::map<Arch, std::string> arch_dynamic_linker = {
+    {Arch::amd64, "/lib64/ld-linux-x86-64.so.2"},
+    {Arch::arm64, "/lib/ld-linux-aarch64.so.1"}
+  };
+
+  struct MountPoint {
+    std::filesystem::path host_directory;
+    std::filesystem::path machine_directory;
+    std::string label;
+    bool is_static;
+  };
+
+  struct Image {
+    std::filesystem::path path;
+    std::string label;
+  };
+}
\ No newline at end of file
diff --git a/src/realmachine/module_cache.cpp b/src/realmachine/module_cache.cpp
new file mode 100644
index 0000000..481f504
--- /dev/null
+++ b/src/realmachine/module_cache.cpp
@@ -0,0 +1,163 @@
+#include <cstdlib>
+#include <fstream>
+#include <sstream>
+
+#include <flogger/flogger.h>
+
+#include "module_cache.h"
+
+auto log_realmachine_module_cache = flogger::bind_log("realmachine/module_cache");
+
+namespace realmachine {
+
+  namespace {
+    constexpr const char* CACHE_FORMAT_VERSION = "1";
+
+    std::string fnv1a(const std::string& s) {
+      uint64_t h = 1469598103934665603ULL;
+      for (unsigned char c : s) {
+        h ^= c;
+        h *= 1099511628211ULL;
+      }
+
+      std::ostringstream o;
+      o << std::hex << h;
+      return o.str();
+    }
+
+    std::string stat_signature(const std::filesystem::path& p) {
+      std::error_code ec;
+      const auto size = std::filesystem::file_size(p, ec);
+      if (ec) return "-";
+
+      const auto mtime = std::filesystem::last_write_time(p, ec);
+      if (ec) return "-";
+
+      return std::to_string(static_cast<unsigned long long>(size)) + ":" +
+        std::to_string(static_cast<long long>(mtime.time_since_epoch().count()));
+    }
+  }
+
+  std::filesystem::path default_module_cache_directory() {
+    if (const char* xdg = std::getenv("XDG_CACHE_HOME"); xdg && *xdg)
+      return std::filesystem::path(xdg) / "realmachine" / "kernel-modules";
+
+    if (const char* home = std::getenv("HOME"); home && *home)
+      return std::filesystem::path(home) / ".cache" / "realmachine" / "kernel-modules";
+
+    return std::filesystem::temp_directory_path() / "realmachine-kernel-modules";
+  }
+
+  std::string module_cache_key(
+    const std::string& kernel_release,
+    const std::string& moddir,
+    const std::vector<std::string>& modules,
+    const bool merged_usr
+  ) {
+    std::string key = CACHE_FORMAT_VERSION;
+    key += "|" + kernel_release;
+    key += "|" + moddir;
+    key += "|" + std::to_string(merged_usr);
+
+    for (const auto& m : modules) {
+      key += "|" + m;
+    }
+
+    for (const auto* f : {"modules.dep", "modules.alias", "modules.symbols", "modules.builtin", "modules.order"}) {
+      key += "|" + std::string(f) + "=" + stat_signature(std::filesystem::path(moddir) / f);
+    }
+
+    const std::string hashed = kernel_release + "-" + fnv1a(key);
+    printf_debug(log_realmachine_module_cache, "key=%s hashed=%s", key.c_str(), hashed.c_str());
+    return hashed;
+  }
+
+  bool module_cache_load(const std::filesystem::path& dir, ModuleSet& out) {
+    std::error_code ec;
+    if (!std::filesystem::is_directory(dir, ec) || ec) {
+      return false;
+    }
+
+    std::ifstream manifest(dir / "manifest");
+    if (!manifest.is_open()) {
+      return false;
+    }
+
+    ModuleSet set;
+    std::string line;
+
+    while (std::getline(manifest, line)) {
+      if (line.empty()) continue;
+
+      const auto tab = line.find('\t');
+      if (tab == std::string::npos) {
+        printf_debug(log_realmachine_module_cache, "malformed manifest line=%s", line.c_str());
+        return false;
+      }
+
+      const auto blob = dir / line.substr(0, tab);
+      if (!std::filesystem::exists(blob, ec) || ec) {
+        printf_debug(log_realmachine_module_cache, "missing blob=%s", blob.string().c_str());
+        return false;
+      }
+
+      set.files.push_back({blob.string(), line.substr(tab + 1)});
+    }
+
+    std::ifstream dep(dir / "modules.dep", std::ios::binary);
+    if (!dep.is_open()) {
+      return false;
+    }
+
+    std::ostringstream buf;
+    buf << dep.rdbuf();
+    set.modules_dep = buf.str();
+
+    out = std::move(set);
+    printf_debug(log_realmachine_module_cache, "cache hit dir=%s modules=%zu", dir.string().c_str(), out.files.size());
+    return true;
+  }
+
+  void module_cache_store(
+    const std::filesystem::path& tmpdir,
+    const std::filesystem::path& dir,
+    ModuleSet& set
+  ) {
+    {
+      std::ofstream manifest(tmpdir / "manifest", std::ios::binary | std::ios::trunc);
+      if (!manifest.is_open()) {
+        printf_error(log_realmachine_module_cache, "cannot write manifest in %s", tmpdir.string().c_str());
+        return;
+      }
+
+      for (const auto& f : set.files) {
+        manifest << std::filesystem::path(f[0]).filename().string() << "\t" << f[1] << "\n";
+      }
+    }
+
+    {
+      std::ofstream dep(tmpdir / "modules.dep", std::ios::binary | std::ios::trunc);
+      if (!dep.is_open()) {
+        printf_error(log_realmachine_module_cache, "cannot write modules.dep in %s", tmpdir.string().c_str());
+        return;
+      }
+      dep << set.modules_dep;
+    }
+
+    std::error_code ec;
+    std::filesystem::create_directories(dir.parent_path(), ec);
+    std::filesystem::rename(tmpdir, dir, ec);
+
+    if (ec) {
+      printf_debug(log_realmachine_module_cache, "rename failed (%s), keeping temporary blobs", ec.message().c_str());
+      return;
+    }
+
+    for (auto& f : set.files) {
+      f[0] = (dir / std::filesystem::path(f[0]).filename()).string();
+    }
+
+    printf_debug(log_realmachine_module_cache, "cache stored dir=%s modules=%zu", dir.string().c_str(), set.files.size());
+  }
+
+}
diff --git a/src/realmachine/module_cache.h b/src/realmachine/module_cache.h
new file mode 100644
index 0000000..2d0f867
--- /dev/null
+++ b/src/realmachine/module_cache.h
@@ -0,0 +1,32 @@
+#pragma once
+
+#include <array>
+#include <filesystem>
+#include <string>
+#include <vector>
+
+namespace realmachine {
+
+  struct ModuleSet {
+    std::vector<std::array<std::string, 2>> files;
+    std::string modules_dep;
+  };
+
+  std::filesystem::path default_module_cache_directory();
+
+  std::string module_cache_key(
+    const std::string& kernel_release,
+    const std::string& moddir,
+    const std::vector<std::string>& modules,
+    bool merged_usr
+  );
+
+  bool module_cache_load(const std::filesystem::path& dir, ModuleSet& out);
+
+  void module_cache_store(
+    const std::filesystem::path& tmpdir,
+    const std::filesystem::path& dir,
+    ModuleSet& set
+  );
+
+}
diff --git a/src/realmachine/template.cpp b/src/realmachine/template.cpp
new file mode 100644
index 0000000..b0a4bfa
--- /dev/null
+++ b/src/realmachine/template.cpp
@@ -0,0 +1,132 @@
+#include <string>
+
+#include <flogger/flogger.h>
+#include <shellescape/shellescape.h>
+
+#include "template.h"
+
+auto log_realmachine_templating = flogger::bind_log("realmachine/templating");
+
+namespace templating {
+
+  const std::string initScript =
+  R"(#!/bin/busybox sh
+busybox mount -t proc proc /proc
+busybox mount -t sysfs none /sys
+
+# probe additional modules
+{modules}
+
+# mount static volumes
+{mounts}
+
+exec /lib/systemd/systemd
+)";
+
+  const std::string networkdTemplate =
+  R"([Match]
+Type=ether
+
+[Network]
+DHCP=ipv4
+# Disable link-local address to speedup boot
+LinkLocalAddressing=no
+IPv6AcceptRA=no
+)";
+
+  const std::string networkdLinkTemplate =
+  R"([Match]
+Type=ether
+
+[Link]
+# Give the interface a static name
+Name=ethernet0
+)";
+
+  const std::string commandWrapper =
+  R"(#!/bin/sh
+/lib/systemd/systemd-networkd-wait-online -q --interface=ethernet0
+if [ $? != 0 ]; then
+  echo "WARNING: Network setup failed"
+  echo "== Journal =="
+  journalctl -a --no-pager
+  echo "== networkd =="
+  networkctl status
+  networkctl list
+  echo 1 > /run/realmachine/result
+  exit
+fi
+
+{command}
+
+echo $? > /run/realmachine/result
+)";
+
+  const std::string serviceTemplate =
+  R"([Unit]
+Description=realmachine runner
+Conflicts=shutdown.target
+Before=shutdown.target
+Requires=basic.target
+Wants=systemd-resolved.service binfmt-support.service systemd-networkd.service
+After=basic.target systemd-resolved.service binfmt-support.service systemd-networkd.service
+OnFailure=poweroff.target
+
+[Service]
+Environment=HOME=/root IN_FAKE_MACHINE=yes {env}
+WorkingDirectory=-/scratch
+ExecStart=/wrapper
+ExecStopPost=/bin/sync
+ExecStopPost=/bin/systemctl poweroff -q -ff
+Type=idle
+TTYPath={tty}
+StandardInput=tty-force
+StandardOutput=inherit
+StandardError=inherit
+KillMode=process
+IgnoreSIGPIPE=no
+SendSIGHUP=yes
+LimitNOFILE=4096
+)";
+
+  static std::string replace_all(std::string s, const std::string& key, const std::string& val) {
+    size_t pos = 0;
+    while ((pos = s.find(key, pos)) != std::string::npos) {
+      s.replace(pos, key.size(), val);
+      pos += val.size();
+    }
+    return s;
+  }
+
+  std::string get_init_script(const std::string& modules, const std::string& mounts) {
+    std::string out = initScript;
+    out = replace_all(out, "{modules}", modules);
+    out = replace_all(out, "{mounts}", mounts);
+    printf_debug(log_realmachine_templating, "init_script: %s", out.c_str());
+    return out;
+  }
+
+  std::string get_networkd_config() {
+    return networkdTemplate;
+  }
+
+  std::string get_networkd_link_config() {
+    return networkdLinkTemplate;
+  }
+
+  std::string get_command_wrapper(const std::string& command) {
+    std::string out = commandWrapper;
+    out = replace_all(out, "{command}", command);
+    printf_debug(log_realmachine_templating, "command_wrapper: %s", command.c_str());
+    return out;
+  }
+
+  std::string get_service(const std::string& env, const std::string& tty) {
+    std::string out = serviceTemplate;
+    out = replace_all(out, "{env}", env);
+    out = replace_all(out, "{tty}", tty);
+    printf_debug(log_realmachine_templating, "command_wrapper: %s", out.c_str());
+    return out;
+  }
+
+}
\ No newline at end of file
diff --git a/src/realmachine/template.h b/src/realmachine/template.h
new file mode 100644
index 0000000..99da227
--- /dev/null
+++ b/src/realmachine/template.h
@@ -0,0 +1,16 @@
+#pragma once
+#include <string>
+
+namespace templating {
+  extern const std::string initScript;
+  extern const std::string networkdTemplate;
+  extern const std::string networkdLinkTemplate;
+  extern const std::string commandWrapper;
+  extern const std::string serviceTemplate;
+
+  std::string get_init_script(const std::string& modules, const std::string& mounts);
+  std::string get_networkd_config();
+  std::string get_networkd_link_config();
+  std::string get_command_wrapper(const std::string& command);
+  std::string get_service(const std::string& env, const std::string& tty);
+}
\ No newline at end of file
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
new file mode 100644
index 0000000..fb6ae77
--- /dev/null
+++ b/tests/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_executable(realmachine_tests
+        test.cpp
+)
+
+target_include_directories(realmachine_tests PRIVATE
+        ${CMAKE_SOURCE_DIR}/src
+)
+
+target_link_libraries(realmachine_tests PRIVATE realmachine_lib)
+
+add_test(NAME realmachine_tests COMMAND realmachine_tests)
\ No newline at end of file
diff --git a/tests/test b/tests/test
new file mode 100644
index 0000000..dd33a6b
Binary files /dev/null and b/tests/test differ
diff --git a/tests/test.cpp b/tests/test.cpp
new file mode 100644
index 0000000..2a088d7
--- /dev/null
+++ b/tests/test.cpp
@@ -0,0 +1,392 @@
+// should print 'okidoki' at the end of the tests
+// included:
+// - command execution success/failure
+// - filesystem mounts (tmpfs, ext4 scratch)
+// - disk image creation
+// - memory sizing
+// - sector size correctness
+// - volume mapping behavior
+// - environment variable propagation
+// - command escaping correctness
+
+#include <iostream>
+#include <string>
+#include <vector>
+#include <array>
+#include <fstream>
+#include <sstream>
+
+#include <flogger/flogger.h>
+
+#include "realmachine/globals.h"
+#include "realmachine/machine.h"
+#include "realmachine/decompressors.h"
+
+auto log_test = flogger::bind_log("realmachine/test");
+
+using namespace realmachine;
+
+static std::string backendName = "kvm";
+static std::string testArg;
+
+static std::shared_ptr<Machine> create_machine() {
+  auto m = Machine::new_machine_with_backend(backendName);
+  m->set_show_boot(true);
+  m->set_num_cpus(2);
+
+  m->executable_name =
+    std::filesystem::canonical("/proc/self/exe").string();
+
+  return m;
+}
+
+static void assert_dev_sector_size(const std::string& device, int sectorsize) {
+  const std::vector<std::string> types = {"physical", "logical"};
+
+  for (auto& t : types) {
+    std::ifstream f("/sys/block/" + device + "/queue/" + t + "_block_size");
+    std::string line;
+    std::getline(f, line);
+    int v = std::stoi(line);
+    if (v != sectorsize) {
+      printf_error(log_test, "assert_dev_sector_size(): sector size mismatch");
+      std::exit(1);
+    }
+  }
+}
+
+static void assert_sector_size(int sectorsize) {
+  if (!Machine::in_machine()) {
+    const auto m = create_machine();
+    m->set_sector_size(sectorsize);
+    m->create_image("test.img", 1024 * 1024);
+
+    std::string test =
+      (sectorsize == 512)
+        ? "TestImage512SectorSize"
+        : "TestImage4kSectorSize";
+
+    if (m->run_in_machine_with_args({
+      "-test.run",
+      test,
+      backendName
+    }) != 0) {
+      printf_error(log_test, "assert_sector_size(): run_in_machine_with_args() failed");
+      std::exit(1);
+    }
+
+  } else {
+    assert_dev_sector_size("vda", sectorsize);
+  }
+}
+
+static void assert_mount(const std::string& mp, const std::string& fs) {
+  std::ifstream f("/proc/self/mounts");
+  std::string line;
+
+  while (std::getline(f, line)) {
+    std::istringstream iss(line);
+    std::string d, m, t;
+    iss >> d >> m >> t;
+    if (m == mp) {
+      if (t != fs) std::exit(1);
+      return;
+    }
+  }
+
+  printf_error(log_test, "assert_mount(): mount() failed");
+  std::exit(1);
+}
+
+static void test_success() {
+  const auto m = create_machine();
+  if (m->run("ls /") != 0) {
+    printf_error(log_test, "test_success() failed");
+    std::exit(1);
+  }
+}
+
+static void test_notfound() {
+  const auto m = create_machine();
+  if (m->run("/a/b/c /") != 127) {
+    printf_error(log_test, "test_notfound() failed");
+    std::exit(1);
+  }
+}
+
+static void test_image() {
+  const auto m = create_machine();
+  m->create_image("test.img", 1024 * 1024);
+  if (m->run("test -b /dev/disk/by-realmachine-label/fakedisk-0") != 0) {
+    printf_error(log_test, "test_image() failed");
+    std::exit(1);
+  }
+}
+
+static void test_512() { assert_sector_size(512); }
+
+static void test_4k() { assert_sector_size(4096); }
+
+static void test_tmpfs() {
+  if (Machine::in_machine()) {
+    assert_mount("/scratch", "tmpfs");
+    return;
+  }
+
+  auto m = create_machine();
+  if (m->run_in_machine_with_args({"-test.run", "TestScratchTmp"}) != 0) {
+    printf_error(log_test, "test_tmpfs() failed");
+    std::exit(1);
+  }
+}
+
+static void test_disk() {
+  if (Machine::in_machine()) {
+    assert_mount("/scratch", "ext4");
+    return;
+  }
+
+  auto m = create_machine();
+  m->set_scratch(1024 * 1024 * 1024, "");
+  if (m->run_in_machine_with_args({"-test.run", "TestScratchDisk"}) != 0) {
+    printf_error(log_test, "test_disk() failed");
+    std::exit(1);
+  }
+}
+
+static void test_memory() {
+  auto m = create_machine();
+  m->set_show_boot(true);
+  m->set_memory(1024);
+
+  const std::string cmd = R"(MEM=$(grep MemTotal /proc/meminfo | awk '{print $2}')
+if [ "$MEM" -lt 900000 ] || [ "$MEM" -gt 1024000 ]; then
+  echo "ERROR: unexpected MemTotal=$MEM"
+  echo 1 > /run/realmachine/result
+  exit 1
+else
+  echo "MemTotal OK=$MEM"
+  echo 0 > /run/realmachine/result
+  exit 0
+fi
+)";
+
+  if (m->run(cmd) != 0) {
+    printf_error(log_test, "memory size test failed");
+    std::exit(1);
+  }
+}
+
+static void test_spawn() {
+  if (Machine::in_machine()) return;
+
+  auto m = create_machine();
+  if (m->run_in_machine_with_args({"-test.run", "TestSpawnMachine"}) != 0)
+    std::exit(1);
+}
+
+static void test_label() {
+  if (Machine::in_machine()) return;
+
+  const auto m = create_machine();
+  const auto a = m->create_image("a.img", 1024 * 1024);
+  const auto b = m->create_image_with_label("b.img", 1024 * 1024, "label");
+
+  if (m->run_in_machine_with_args({"-test.run", "TestImageLabel", a, b}) != 0) {
+    printf_error(log_test, "test_label() failed");
+    std::exit(1);
+  }
+}
+
+static void test_volumes() {
+  realmachine_g::APP_THROW_ON_BAD_MOUNTS = false;
+  if (Machine::in_machine())
+    return;
+
+  {
+    auto m = create_machine();
+    m->add_volume("missing_dir");
+    if (m->run_in_machine_with_args({"-test.run", "TestVolumes"}) != -1) {
+      printf_error(log_test, "test_volumes() failed #1");
+      std::exit(1);
+    }
+  }
+
+  {
+    auto m = create_machine();
+    m->add_volume("/dev/zero");
+    if (m->run_in_machine_with_args({"-test.run", "TestVolumes"}) != -1) {
+      printf_error(log_test, "test_volumes() failed #2");
+      std::exit(1);
+    }
+  }
+
+  {
+    auto m = create_machine();
+    m->add_volume_at("/dev", "/dev ices");
+    if (m->run_in_machine_with_args({"-test.run", "TestVolumes"}) != -1) {
+      printf_error(log_test, "test_volumes() failed #3");
+      std::exit(1);
+    }
+  }
+  realmachine_g::APP_THROW_ON_BAD_MOUNTS = true;
+}
+
+static void test_escape() {
+  if (Machine::in_machine()) {
+    if (testArg != "$s'n\\akes") {
+      printf_error(log_test, "test_escape() failed #1");
+      std::exit(1);
+    }
+    return;
+  }
+
+  const auto m = create_machine();
+  if (m->run_in_machine_with_args({
+    "-test.run", "TestCommandEscaping",
+    "-testarg", "$s'n\\akes"
+  }) != 0) {
+    printf_error(log_test, "test_escape() failed #2");
+    std::exit(1);
+  }
+}
+
+static void test_decompressors() {
+  printf_info(log_test, "testing decompression");
+
+  auto compare_streams = [](std::istream& a, std::istream& b) {
+    int i = 0;
+    while (true) {
+      char ca, cb;
+      bool ae = !a.get(ca);
+      bool be = !b.get(cb);
+
+      if (ae || be) {
+        if (ae && be) return;
+        printf_error(log_test, "decompressor mismatch EOF at byte %d", i);
+        std::exit(1);
+      }
+
+      if (ca != cb) {
+        printf_error(log_test, "decompressor mismatch at byte %d (%d vs %d)", i, (unsigned char)ca, (unsigned char)cb);
+        std::exit(1);
+      }
+
+      i++;
+    }
+  };
+
+  struct Case {
+    const char* suffix;
+    void (*fn)(std::ostream&, std::istream&);
+  };
+
+  Case cases[] = {
+    {"", decompressors::null_decompressor},
+    {".gz", decompressors::gzip_decompressor},
+    {".xz", decompressors::xz_decompressor},
+    {".zst", decompressors::zstd_decompressor}
+  };
+
+  int ok = 0;
+  int total = sizeof(cases) / sizeof(cases[0]);
+
+  for (auto& c : cases) {
+    std::string in_path = std::string("test") + c.suffix;
+    std::ifstream src(in_path, std::ios::binary);
+
+    if (!src) {
+      printf_error(log_test, "failed to open input file: '%s' (expected working dir: tests/)", in_path.c_str());
+      std::exit(1);
+    }
+
+    std::ostringstream out(std::ios::binary);
+    c.fn(out, src);
+
+    std::string ref_path = "test";
+    std::ifstream ref(ref_path, std::ios::binary);
+
+    if (!ref) {
+      printf_error(log_test, "failed to open reference file: '%s'", ref_path.c_str());
+      std::exit(1);
+    }
+
+    std::istringstream result(out.str(), std::ios::binary);
+
+    compare_streams(result, ref);
+
+    ok++;
+    printf_info(log_test, "decompressor OK: %s", in_path.c_str());
+  }
+
+  printf_info(log_test, "decompression tests finished: %d/%d passed", ok, total);
+}
+
+int main(const int argc, char** argv) {
+  if (!Machine::in_machine()) {
+    test_decompressors();
+  }
+
+  std::string runFilter;
+  printf_info(log_test, "booting test runner");
+  realmachine_g::current_log_level = realmachine_g::log_level::trace;
+
+  for (int i = 1; i < argc; i++) {
+    std::string a = argv[i];
+    printf_debug(log_test, "arg: %s", a.c_str());
+
+    if (a == "-backend" && i + 1 < argc) {
+      backendName = argv[++i];
+      printf_info(log_test, "backend=%s", backendName.c_str());
+    } else if (a == "-testarg" && i + 1 < argc) {
+      testArg = argv[++i];
+      printf_info(log_test, "testarg set");
+    } else if (a == "-test.run" && i + 1 < argc) {
+      runFilter = argv[++i];
+      printf_info(log_test, "run filter=%s", runFilter.c_str());
+    }
+  }
+
+  struct T { const char* n; void (*f)(); };
+  T tests[] = {
+    {"TestSuccessfulCommand", test_success},
+    {"TestCommandNotFound", test_notfound},
+    {"TestImage", test_image},
+    {"TestImage512SectorSize", test_512},
+    {"TestImage4kSectorSize", test_4k},
+    {"TestScratchTmp", test_tmpfs},
+    {"TestScratchDisk", test_disk},
+    {"TestMemory", test_memory},
+    {"TestSpawnMachine", test_spawn},
+    {"TestImageLabel", test_label},
+    {"TestVolumes", test_volumes},
+    {"TestCommandEscaping", test_escape}
+  };
+
+  auto match = [&](const char* n) {
+    if (runFilter.empty()) return true;
+    return std::string(n) == runFilter;
+  };
+
+  int ran = 0;
+  printf_info(log_test, "starting tests");
+
+  for (auto&[n, f] : tests) {
+    if (match(n)) {
+      printf_debug(log_test, "running %s", n);
+      f();
+      ran++;
+      printf_debug(log_test, "finished %s", n);
+    }
+  }
+
+  if (!runFilter.empty() && ran == 0) {
+    printf_error(log_test, "no tests matched filter: %s", runFilter.c_str());
+    std::exit(1);
+  }
+
+  printf_info(log_test, "done, ran=%d", ran);
+  if (!Machine::in_machine()) printf_info(log_test, "okidoki");
+
+  return 0;
+}
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src / ferdios / librealmachine

Initial commit