Adding 3rd homework - Brainfuck Interpreter (#44)

* Add 1st hw

* --amend

* moving readme for 1st hw to designated folder

* renamed TokenType enum to TokenClass

* fixed character constant lexing. added sampe output file

* add new line at end-of-file. added gitignore

* a bit of refactoring

* Add BF interpreter

6 files changed, 4300 insertions, 0 deletions

diff --git a/homework/81568/BF_Interpreter/CLI11.hpp b/homework/81568/BF_Interpreter/CLI11.hpp
new file mode 100644
index 0000000..bf3f813
--- /dev/null
+++ b/homework/81568/BF_Interpreter/CLI11.hpp
@@ -0,0 +1,4043 @@
+#pragma once
+
+// CLI11: Version 1.6.1
+// Originally designed by Henry Schreiner
+// https://github.com/CLIUtils/CLI11
+//
+// This is a standalone header file generated by MakeSingleHeader.py in CLI11/scripts
+// from: v1.6.1
+//
+// From LICENSE:
+//
+// CLI11 1.6 Copyright (c) 2017-2018 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.
+
+
+// Standard combined includes:
+
+#include <algorithm>
+#include <deque>
+#include <exception>
+#include <fstream>
+#include <functional>
+#include <iomanip>
+#include <iostream>
+#include <istream>
+#include <iterator>
+#include <locale>
+#include <map>
+#include <memory>
+#include <numeric>
+#include <set>
+#include <sstream>
+#include <stdexcept>
+#include <string>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+
+// Verbatim copy from CLI/Version.hpp:
+
+
+#define CLI11_VERSION_MAJOR 1
+#define CLI11_VERSION_MINOR 6
+#define CLI11_VERSION_PATCH 1
+#define CLI11_VERSION "1.6.1"
+
+
+
+
+// Verbatim copy from CLI/Macros.hpp:
+
+
+// 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
+#endif
+#endif
+#endif
+#elif defined(_MSC_VER) && __cplusplus == 199711L
+// MSVC sets _MSVC_LANG rather than __cplusplus (supposedly until the standard is 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
+#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
+
+
+
+
+// Verbatim copy from CLI/Optional.hpp:
+
+#ifdef __has_include
+
+#if defined(CLI11_CPP17) && __has_include(<optional>) && \
+     !defined(CLI11_STD_OPTIONAL)
+#define CLI11_STD_OPTIONAL 1
+#endif
+
+#if defined(CLI11_CPP14) && __has_include(<experimental/optional>) && \
+    !defined(CLI11_EXPERIMENTAL_OPTIONAL)
+#define CLI11_EXPERIMENTAL_OPTIONAL 1
+#endif
+
+#if __has_include(<boost/optional.hpp>) && !defined(CLI11_BOOST_OPTIONAL)
+#include <boost/version.hpp>
+#if BOOST_VERSION >= 105800
+#define CLI11_BOOST_OPTIONAL 1
+#endif
+#endif
+
+#endif
+
+#if CLI11_STD_OPTIONAL
+#include <optional>
+#endif
+#if CLI11_EXPERIMENTAL_OPTIONAL
+#include <experimental/optional>
+#endif
+#if CLI11_BOOST_OPTIONAL
+#include <boost/optional.hpp>
+#endif
+
+
+// From CLI/Version.hpp:
+
+
+
+// From CLI/Macros.hpp:
+
+
+
+// From CLI/Optional.hpp:
+
+namespace CLI {
+
+#if CLI11_STD_OPTIONAL
+template <typename T> std::istream &operator>>(std::istream &in, std::optional<T> &val) {
+    T v;
+    in >> v;
+    val = v;
+    return in;
+}
+#endif
+
+#if CLI11_EXPERIMENTAL_OPTIONAL
+template <typename T> std::istream &operator>>(std::istream &in, std::experimental::optional<T> &val) {
+    T v;
+    in >> v;
+    val = v;
+    return in;
+}
+#endif
+
+#if CLI11_BOOST_OPTIONAL
+template <typename T> std::istream &operator>>(std::istream &in, boost::optional<T> &val) {
+    T v;
+    in >> v;
+    val = v;
+    return in;
+}
+#endif
+
+// Export the best optional to the CLI namespace
+#if CLI11_STD_OPTIONAL
+using std::optional;
+#elif CLI11_EXPERIMENTAL_OPTIONAL
+using std::experimental::optional;
+#elif CLI11_BOOST_OPTIONAL
+using boost::optional;
+#endif
+
+// This is true if any optional is found
+#if CLI11_STD_OPTIONAL || CLI11_EXPERIMENTAL_OPTIONAL || CLI11_BOOST_OPTIONAL
+#define CLI11_OPTIONAL 1
+#endif
+
+} // namespace CLI
+
+// From CLI/StringTools.hpp:
+
+namespace CLI {
+namespace detail {
+
+// Based on http://stackoverflow.com/questions/236129/split-a-string-in-c
+/// Split a string by a delim
+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;
+}
+
+/// Simple function to join a string
+template <typename T> std::string join(const T &v, std::string delim = ",") {
+    std::ostringstream s;
+    size_t start = 0;
+    for(const auto &i : v) {
+        if(start++ > 0)
+            s << delim;
+        s << i;
+    }
+    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(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
+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;
+}
+
+/// Trim anything from left of string
+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;
+}
+
+/// Trim whitespace from right of string
+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;
+}
+
+/// Trim anything from right of string
+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;
+}
+
+/// 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);
+}
+
+/// 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 a two part "help" string
+inline std::ostream &format_help(std::ostream &out, std::string name, std::string description, size_t wid) {
+    name = "  " + name;
+    out << std::setw(static_cast<int>(wid)) << std::left << name;
+    if(!description.empty()) {
+        if(name.length() >= wid)
+            out << "\n" << std::setw(static_cast<int>(wid)) << "";
+        out << description;
+    }
+    out << "\n";
+    return out;
+}
+
+/// Verify the first character of an option
+template <typename T> bool valid_first_char(T c) { return std::isalpha(c, std::locale()) || c == '_'; }
+
+/// Verify following characters of an option
+template <typename T> bool valid_later_char(T c) {
+    return std::isalnum(c, std::locale()) || c == '_' || c == '.' || c == '-';
+}
+
+/// Verify an option name
+inline bool valid_name_string(const std::string &str) {
+    if(str.empty() || !valid_first_char(str[0]))
+        return false;
+    for(auto c : str.substr(1))
+        if(!valid_later_char(c))
+            return false;
+    return true;
+}
+
+/// 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;
+}
+
+/// Split a string '"one two" "three"' into 'one two', 'three'
+inline std::vector<std::string> split_up(std::string str) {
+
+    std::vector<char> delims = {'\'', '\"'};
+    auto find_ws = [](char ch) { return std::isspace<char>(ch, std::locale()); };
+    trim(str);
+
+    std::vector<std::string> output;
+
+    while(!str.empty()) {
+        if(str[0] == '\'') {
+            auto end = str.find('\'', 1);
+            if(end != std::string::npos) {
+                output.push_back(str.substr(1, end - 1));
+                str = str.substr(end + 1);
+            } else {
+                output.push_back(str.substr(1));
+                str = "";
+            }
+        } else if(str[0] == '\"') {
+            auto end = str.find('\"', 1);
+            if(end != std::string::npos) {
+                output.push_back(str.substr(1, end - 1));
+                str = str.substr(end + 1);
+            } else {
+                output.push_back(str.substr(1));
+                str = "";
+            }
+
+        } 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, str.end());
+            } else {
+                output.push_back(str);
+                str = "";
+            }
+        }
+        trim(str);
+    }
+
+    return output;
+}
+
+/// 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.
+inline std::string fix_newlines(std::string leader, std::string input) {
+    std::string::size_type n = 0;
+    while(n != std::string::npos && n < input.size()) {
+        n = input.find('\n', n);
+        if(n != std::string::npos) {
+            input = input.substr(0, n + 1) + leader + input.substr(n + 1);
+            n += leader.size();
+        }
+    }
+    return input;
+}
+
+} // namespace detail
+} // namespace CLI
+
+// From CLI/Error.hpp:
+
+namespace CLI {
+
+// 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 name, std::string msg, int exit_code) : parent(std::move(name), std::move(msg), exit_code) {}     \
+    name(std::string name, std::string msg, ExitCodes exit_code)                                                       \
+        : parent(std::move(name), 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 {
+    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 exit_code;
+    std::string name{"Error"};
+
+  public:
+    int get_exit_code() const { return exit_code; }
+
+    std::string get_name() const { return name; }
+
+    Error(std::string name, std::string msg, int exit_code = static_cast<int>(ExitCodes::BaseClass))
+        : runtime_error(msg), exit_code(exit_code), 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 BadLongName(std::string name) { return BadNameString("Bad long name: " + name); }
+    static BadNameString DashesOnly(std::string name) {
+        return BadNameString("Must have a name, not just dashes: " + 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 OptionAlreadyAdded(name + " requires " + other, ExitCodes::OptionAlreadyAdded);
+    }
+    static OptionAlreadyAdded Excludes(std::string name, std::string other) {
+        return OptionAlreadyAdded(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 ParseError {
+    CLI11_ERROR_DEF(ParseError, CallForHelp)
+    CallForHelp() : CallForHelp("This should be caught in your main function, see examples", ExitCodes::Success) {}
+};
+
+/// Usually somethign like --help-all on command line
+class CallForAllHelp : public ParseError {
+    CLI11_ERROR_DEF(ParseError, CallForAllHelp)
+    CallForAllHelp()
+        : CallForAllHelp("This should be caught in your main function, see examples", ExitCodes::Success) {}
+};
+
+/// Does not output a diagnostic in CLI11_PARSE, but allows to return from main() 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(size_t min_subcom) {
+        if(min_subcom == 1)
+            return RequiredError("A subcommand");
+        else
+            return RequiredError("Requires at least " + std::to_string(min_subcom) + " subcommands",
+                                 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, size_t recieved)
+        : ArgumentMismatch(expected > 0 ? ("Expected exactly " + std::to_string(expected) + " arguments to " + name +
+                                           ", got " + std::to_string(recieved))
+                                        : ("Expected at least " + std::to_string(-expected) + " arguments to " + name +
+                                           ", got " + std::to_string(recieved)),
+                           ExitCodes::ArgumentMismatch) {}
+
+    static ArgumentMismatch AtLeast(std::string name, int num) {
+        return ArgumentMismatch(name + ": At least " + std::to_string(num) + " required");
+    }
+    static ArgumentMismatch TypedAtLeast(std::string name, int num, std::string type) {
+        return ArgumentMismatch(name + ": " + std::to_string(num) + " required " + type + " missing");
+    }
+};
+
+/// 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::rjoin(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 non-existent 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
+
+/// @}
+
+} // namespace CLI
+
+// From CLI/TypeTools.hpp:
+
+namespace CLI {
+
+// Type tools
+
+/// 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/master/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;
+
+/// Check to see if something is a vector (fail check by default)
+template <typename T> struct is_vector { static const bool value = false; };
+
+/// Check to see if something is a vector (true if actually a vector)
+template <class T, class A> struct is_vector<std::vector<T, A>> { static bool const value = true; };
+
+/// Check to see if something is bool (fail check by default)
+template <typename T> struct is_bool { static const bool value = false; };
+
+/// Check to see if something is bool (true if actually a bool)
+template <> struct is_bool<bool> { static bool const value = true; };
+
+namespace detail {
+// Based generally on https://rmf.io/cxx11/almost-static-if
+/// Simple empty scoped class
+enum class enabler {};
+
+/// An instance to use in EnableIf
+constexpr enabler dummy = {};
+
+// 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<std::is_integral<T>::value && std::is_signed<T>::value, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "INT";
+}
+
+template <typename T,
+          enable_if_t<std::is_integral<T>::value && std::is_unsigned<T>::value, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "UINT";
+}
+
+template <typename T, enable_if_t<std::is_floating_point<T>::value, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "FLOAT";
+}
+
+/// This one should not be used, since vector types print the internal type
+template <typename T, enable_if_t<is_vector<T>::value, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "VECTOR";
+}
+
+template <typename T,
+          enable_if_t<!std::is_floating_point<T>::value && !std::is_integral<T>::value && !is_vector<T>::value,
+                      detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "TEXT";
+}
+
+// Lexical cast
+
+/// Signed integers / enums
+template <typename T,
+          enable_if_t<(std::is_integral<T>::value && std::is_signed<T>::value), detail::enabler> = detail::dummy>
+bool lexical_cast(std::string input, T &output) {
+    try {
+        size_t n = 0;
+        long long output_ll = std::stoll(input, &n, 0);
+        output = static_cast<T>(output_ll);
+        return n == input.size() && static_cast<long long>(output) == output_ll;
+    } catch(const std::invalid_argument &) {
+        return false;
+    } catch(const std::out_of_range &) {
+        return false;
+    }
+}
+
+/// Unsigned integers
+template <typename T,
+          enable_if_t<std::is_integral<T>::value && std::is_unsigned<T>::value, detail::enabler> = detail::dummy>
+bool lexical_cast(std::string input, T &output) {
+    if(!input.empty() && input.front() == '-')
+        return false; // std::stoull happily converts negative values to junk without any errors.
+
+    try {
+        size_t n = 0;
+        unsigned long long output_ll = std::stoull(input, &n, 0);
+        output = static_cast<T>(output_ll);
+        return n == input.size() && static_cast<unsigned long long>(output) == output_ll;
+    } catch(const std::invalid_argument &) {
+        return false;
+    } catch(const std::out_of_range &) {
+        return false;
+    }
+}
+
+/// Floats
+template <typename T, enable_if_t<std::is_floating_point<T>::value, detail::enabler> = detail::dummy>
+bool lexical_cast(std::string input, T &output) {
+    try {
+        size_t n = 0;
+        output = static_cast<T>(std::stold(input, &n));
+        return n == input.size();
+    } catch(const std::invalid_argument &) {
+        return false;
+    } catch(const std::out_of_range &) {
+        return false;
+    }
+}
+
+/// String and similar
+template <typename T,
+          enable_if_t<!std::is_floating_point<T>::value && !std::is_integral<T>::value &&
+                          std::is_assignable<T &, std::string>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_cast(std::string input, T &output) {
+    output = input;
+    return true;
+}
+
+/// Non-string parsable
+template <typename T,
+          enable_if_t<!std::is_floating_point<T>::value && !std::is_integral<T>::value &&
+                          !std::is_assignable<T &, std::string>::value,
+                      detail::enabler> = detail::dummy>
+bool lexical_cast(std::string input, T &output) {
+    std::istringstream is;
+
+    is.str(input);
+    is >> output;
+    return !is.fail() && !is.rdbuf()->in_avail();
+}
+
+} // namespace detail
+} // namespace CLI
+
+// From CLI/Split.hpp:
+
+namespace CLI {
+namespace detail {
+
+// Returns false if not a short option. Otherwise, sets opt name and rest and returns true
+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;
+    } else
+        return false;
+}
+
+// Returns false if not a long option. Otherwise, sets opt name and other side of = and returns true
+inline bool split_long(const std::string &current, std::string &name, std::string &value) {
+    if(current.size() > 2 && current.substr(0, 2) == "--" && valid_first_char(current[2])) {
+        auto loc = current.find("=");
+        if(loc != std::string::npos) {
+            name = current.substr(2, loc - 2);
+            value = current.substr(loc + 1);
+        } else {
+            name = current.substr(2);
+            value = "";
+        }
+        return true;
+    } else
+        return false;
+}
+
+// Splits a string into multiple long and short names
+inline std::vector<std::string> split_names(std::string current) {
+    std::vector<std::string> output;
+    size_t val;
+    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;
+}
+
+/// Get a vector of short names, one of long names, and a single name
+inline std::tuple<std::vector<std::string>, std::vector<std::string>, std::string>
+get_names(const std::vector<std::string> &input) {
+
+    std::vector<std::string> short_names;
+    std::vector<std::string> long_names;
+    std::string pos_name;
+
+    for(std::string name : input) {
+        if(name.length() == 0)
+            continue;
+        else 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
+                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 == "--") {
+            throw BadNameString::DashesOnly(name);
+        } else {
+            if(pos_name.length() > 0)
+                throw BadNameString::MultiPositionalNames(name);
+            pos_name = name;
+        }
+    }
+
+    return std::tuple<std::vector<std::string>, std::vector<std::string>, std::string>(
+        short_names, long_names, pos_name);
+}
+
+} // namespace detail
+} // namespace CLI
+
+// From CLI/ConfigFwd.hpp:
+
+namespace CLI {
+
+class App;
+
+namespace detail {
+
+/// Comma separated join, adds quotes if needed
+inline std::string ini_join(std::vector<std::string> args) {
+    std::ostringstream s;
+    size_t start = 0;
+    for(const auto &arg : args) {
+        if(start++ > 0)
+            s << " ";
+
+        auto it = std::find_if(arg.begin(), arg.end(), [](char ch) { return std::isspace<char>(ch, std::locale()); });
+        if(it == arg.end())
+            s << arg;
+        else if(arg.find(R"(")") == std::string::npos)
+            s << R"(")" << arg << R"(")";
+        else
+            s << R"(')" << arg << R"(')";
+    }
+
+    return s.str();
+}
+
+} // namespace detail
+
+/// 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;
+
+    /// The list of parents and name joined by "."
+    std::string fullname() const {
+        std::vector<std::string> tmp = parents;
+        tmp.emplace_back(name);
+        return detail::join(tmp, ".");
+    }
+};
+
+/// 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;
+
+    /// Convert a flag to a bool
+    virtual std::vector<std::string> to_flag(const ConfigItem &item) const {
+        if(item.inputs.size() == 1) {
+            std::string val = item.inputs.at(0);
+            val = detail::to_lower(val);
+
+            if(val == "true" || val == "on" || val == "yes") {
+                return std::vector<std::string>(1);
+            } else if(val == "false" || val == "off" || val == "no") {
+                return std::vector<std::string>();
+            } else {
+                try {
+                    size_t ui = std::stoul(val);
+                    return std::vector<std::string>(ui);
+                } catch(const std::invalid_argument &) {
+                    throw ConversionError::TrueFalse(item.fullname());
+                }
+            }
+        } else {
+            throw ConversionError::TooManyInputsFlag(item.fullname());
+        }
+    }
+
+    /// Parse a config file, throw an error (ParseError:ConfigParseError or FileError) on failure
+    std::vector<ConfigItem> from_file(const std::string &name) {
+        std::ifstream input{name};
+        if(!input.good())
+            throw FileError::Missing(name);
+
+        return from_config(input);
+    }
+
+    /// virtual destructor
+    virtual ~Config() = default;
+};
+
+/// This converter works with INI files
+class ConfigINI : public Config {
+  public:
+    std::string to_config(const App *, bool default_also, bool write_description, std::string prefix) const override;
+
+    std::vector<ConfigItem> from_config(std::istream &input) const override {
+        std::string line;
+        std::string section = "default";
+
+        std::vector<ConfigItem> output;
+
+        while(getline(input, line)) {
+            std::vector<std::string> items;
+
+            detail::trim(line);
+            size_t len = line.length();
+            if(len > 1 && line[0] == '[' && line[len - 1] == ']') {
+                section = line.substr(1, len - 2);
+            } else if(len > 0 && line[0] != ';') {
+                output.emplace_back();
+                ConfigItem &out = output.back();
+
+                // Find = in string, split and recombine
+                auto pos = line.find('=');
+                if(pos != std::string::npos) {
+                    out.name = detail::trim_copy(line.substr(0, pos));
+                    std::string item = detail::trim_copy(line.substr(pos + 1));
+                    items = detail::split_up(item);
+                } else {
+                    out.name = detail::trim_copy(line);
+                    items = {"ON"};
+                }
+
+                if(detail::to_lower(section) != "default") {
+                    out.parents = {section};
+                }
+
+                if(out.name.find('.') != std::string::npos) {
+                    std::vector<std::string> plist = detail::split(out.name, '.');
+                    out.name = plist.back();
+                    plist.pop_back();
+                    out.parents.insert(out.parents.end(), plist.begin(), plist.end());
+                }
+
+                out.inputs.insert(std::end(out.inputs), std::begin(items), std::end(items));
+            }
+        }
+        return output;
+    }
+};
+
+} // namespace CLI
+
+// From CLI/Validators.hpp:
+
+namespace CLI {
+
+/// @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.
+/// @{
+
+///
+struct Validator {
+    /// This is the type name, if empty the type name will not be changed
+    std::string tname;
+
+    /// This it the base function that is to be called.
+    /// Returns a string error message if validation fails.
+    std::function<std::string(const std::string &)> func;
+
+    /// 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 { return func(str); };
+
+    /// Combining validators is a new validator
+    Validator operator&(const Validator &other) const {
+        Validator newval;
+        newval.tname = (tname == other.tname ? tname : "");
+
+        // Give references (will make a copy in lambda function)
+        const std::function<std::string(const std::string &filename)> &f1 = func;
+        const std::function<std::string(const std::string &filename)> &f2 = other.func;
+
+        newval.func = [f1, f2](const std::string &filename) {
+            std::string s1 = f1(filename);
+            std::string s2 = f2(filename);
+            if(!s1.empty() && !s2.empty())
+                return s1 + " & " + s2;
+            else
+                return s1 + s2;
+        };
+        return newval;
+    }
+
+    /// Combining validators is a new validator
+    Validator operator|(const Validator &other) const {
+        Validator newval;
+        newval.tname = (tname == other.tname ? tname : "");
+
+        // Give references (will make a copy in lambda function)
+        const std::function<std::string(const std::string &filename)> &f1 = func;
+        const std::function<std::string(const std::string &filename)> &f2 = other.func;
+
+        newval.func = [f1, f2](const std::string &filename) {
+            std::string s1 = f1(filename);
+            std::string s2 = f2(filename);
+            if(s1.empty() || s2.empty())
+                return std::string();
+            else
+                return s1 + " & " + s2;
+        };
+        return newval;
+    }
+};
+
+// 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 {
+
+/// Check for an existing file (returns error message if check fails)
+struct ExistingFileValidator : public Validator {
+    ExistingFileValidator() {
+        tname = "FILE";
+        func = [](const std::string &filename) {
+            struct stat buffer;
+            bool exist = stat(filename.c_str(), &buffer) == 0;
+            bool is_dir = (buffer.st_mode & S_IFDIR) != 0;
+            if(!exist) {
+                return "File does not exist: " + filename;
+            } else if(is_dir) {
+                return "File is actually a directory: " + filename;
+            }
+            return std::string();
+        };
+    }
+};
+
+/// Check for an existing directory (returns error message if check fails)
+struct ExistingDirectoryValidator : public Validator {
+    ExistingDirectoryValidator() {
+        tname = "DIR";
+        func = [](const std::string &filename) {
+            struct stat buffer;
+            bool exist = stat(filename.c_str(), &buffer) == 0;
+            bool is_dir = (buffer.st_mode & S_IFDIR) != 0;
+            if(!exist) {
+                return "Directory does not exist: " + filename;
+            } else if(!is_dir) {
+                return "Directory is actually a file: " + filename;
+            }
+            return std::string();
+        };
+    }
+};
+
+/// Check for an existing path
+struct ExistingPathValidator : public Validator {
+    ExistingPathValidator() {
+        tname = "PATH";
+        func = [](const std::string &filename) {
+            struct stat buffer;
+            bool const exist = stat(filename.c_str(), &buffer) == 0;
+            if(!exist) {
+                return "Path does not exist: " + filename;
+            }
+            return std::string();
+        };
+    }
+};
+
+/// Check for an non-existing path
+struct NonexistentPathValidator : public Validator {
+    NonexistentPathValidator() {
+        tname = "PATH";
+        func = [](const std::string &filename) {
+            struct stat buffer;
+            bool exist = stat(filename.c_str(), &buffer) == 0;
+            if(exist) {
+                return "Path already exists: " + filename;
+            }
+            return std::string();
+        };
+    }
+};
+} // namespace detail
+
+// Static is not needed here, because global const implies static.
+
+/// Check for existing file (returns error message if check fails)
+const detail::ExistingFileValidator ExistingFile;
+
+/// Check for an existing directory (returns error message if check fails)
+const detail::ExistingDirectoryValidator ExistingDirectory;
+
+/// Check for an existing path
+const detail::ExistingPathValidator ExistingPath;
+
+/// Check for an non-existing path
+const detail::NonexistentPathValidator NonexistentPath;
+
+///  Produce a range (factory). Min and max are inclusive.
+struct Range : public Validator {
+    /// 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, T max) {
+        std::stringstream out;
+        out << detail::type_name<T>() << " in [" << min << " - " << max << "]";
+
+        tname = out.str();
+        func = [min, max](std::string input) {
+            T val;
+            detail::lexical_cast(input, val);
+            if(val < min || val > max)
+                return "Value " + input + " not in range " + std::to_string(min) + " to " + std::to_string(max);
+
+            return std::string();
+        };
+    }
+
+    /// Range of one value is 0 to value
+    template <typename T> explicit Range(T max) : Range(static_cast<T>(0), max) {}
+};
+
+/// @}
+
+} // namespace CLI
+
+// From CLI/FormatterFwd.hpp:
+
+namespace CLI {
+
+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 {
+    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 first column
+    size_t column_width_{30};
+
+    /// @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;
+    virtual ~FormatterBase() = 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" label
+    void label(std::string key, std::string val) { labels_[key] = val; }
+
+    /// Set the column width
+    void column_width(size_t val) { column_width_ = val; }
+
+    ///@}
+    /// @name Getters
+    ///@{
+
+    /// Get the current value of a name (REQUIRED, etc.)
+    std::string get_label(std::string key) const {
+        if(labels_.find(key) == labels_.end())
+            return key;
+        else
+            return labels_.at(key);
+    }
+
+    /// Get the current column width
+    size_t get_column_width() const { return column_width_; }
+
+    ///@}
+};
+
+/// 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)) {}
+
+    /// 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;
+
+    /// @name Overridables
+    ///@{
+
+    /// This prints out a group of options with title
+    ///
+    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) 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 *, std::string, AppFormatMode) const override;
+
+    ///@}
+    /// @name Options
+    ///@{
+
+    /// This prints out an option help line, either positional or optional form
+    virtual std::string make_option(const Option *opt, bool is_positional) const {
+        std::stringstream out;
+        detail::format_help(
+            out, make_option_name(opt, is_positional) + make_option_opts(opt), make_option_desc(opt), column_width_);
+        return out.str();
+    }
+
+    /// @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;
+
+    ///@}
+};
+
+} // namespace CLI
+
+// From CLI/Option.hpp:
+
+namespace CLI {
+
+using results_t = std::vector<std::string>;
+using callback_t = std::function<bool(results_t)>;
+
+class Option;
+class App;
+
+using Option_p = std::unique_ptr<Option>;
+
+enum class MultiOptionPolicy { Throw, TakeLast, TakeFirst, Join };
+
+/// 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;
+
+  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};
+
+    /// Allow this option to be given in a configuration file
+    bool configurable_{true};
+
+    /// Policy for multiple arguments when `expected_ == 1`  (can be set on bool flags, too)
+    MultiOptionPolicy multi_option_policy_{MultiOptionPolicy::Throw};
+
+    /// Copy the contents to another similar class (one based on OptionBase)
+    template <typename T> void copy_to(T *other) const {
+        other->group(group_);
+        other->required(required_);
+        other->ignore_case(ignore_case_);
+        other->configurable(configurable_);
+        other->multi_option_policy(multi_option_policy_);
+    }
+
+  public:
+    // setters
+
+    /// Changes the group membership
+    CRTP *group(std::string name) {
+        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); }
+
+    // Getters
+
+    /// Get the group of this option
+    const std::string &get_group() const { return group_; }
+
+    /// True if this is a required option
+    bool get_required() const { return required_; }
+
+    /// The status of ignore case
+    bool get_ignore_case() const { return ignore_case_; }
+
+    /// The status of configurable
+    bool get_configurable() const { return configurable_; }
+
+    /// The status of the multi option policy
+    MultiOptionPolicy get_multi_option_policy() const { return multi_option_policy_; }
+
+    // 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 last
+    CRTP *join() {
+        auto self = static_cast<CRTP *>(this);
+        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);
+    }
+};
+
+/// 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
+
+    /// 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;
+    }
+};
+
+class Option : public OptionBase<Option> {
+    friend App;
+
+  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 (`--a`) without the leading dashes
+    std::vector<std::string> lnames_;
+
+    /// 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, usually only set if default is true in creation
+    std::string defaultval_;
+
+    /// 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(); }};
+
+    /// True if this option has a default
+    bool default_{false};
+
+    ///@}
+    /// @name Configuration
+    ///@{
+
+    /// The number of arguments that make up one option. -1=unlimited (vector-like), 0=flag, 1=normal option,
+    /// 2=complex/pair, etc. Set only when the option is created; this is intrinsic to the type. Eventually, -2 may mean
+    /// vector of pairs.
+    int type_size_{1};
+
+    /// The number of expected values, type_size_ must be < 0. Ignored for flag. N < 0 means at least -N values.
+    int expected_{1};
+
+    /// A list of validators to run on each value parsed
+    std::vector<std::function<std::string(std::string &)>> validators_;
+
+    /// A list of options that are required with this option
+    std::set<Option *> requires_;
+
+    /// A list of options that are excluded with this option
+    std::set<Option *> excludes_;
+
+    ///@}
+    /// @name Other
+    ///@{
+
+    /// Remember the parent app
+    App *parent_;
+
+    /// Options store a callback to do all the work
+    callback_t callback_;
+
+    /// Options can short-circuit for help options or similar (called before parsing is validated)
+    bool short_circuit_{false};
+
+    ///@}
+    /// @name Parsing results
+    ///@{
+
+    /// Results of parsing
+    results_t results_;
+
+    /// Whether the callback has run (needed for INI parsing)
+    bool callback_run_{false};
+
+    ///@}
+
+    /// Making an option by hand is not defined, it must be made by the App class
+    Option(
+        std::string name, std::string description, std::function<bool(results_t)> callback, bool defaulted, App *parent)
+        : description_(std::move(description)), default_(defaulted), parent_(parent),
+          callback_(callback ? std::move(callback) : [](results_t) { return true; }) {
+        std::tie(snames_, lnames_, pname_) = detail::get_names(detail::split_names(name));
+    }
+
+  public:
+    /// @name Basic
+    ///@{
+
+    /// Count the total number of times an option was passed
+    size_t count() const { return results_.size(); }
+
+    /// True if the option was not passed
+    size_t empty() const { return results_.empty(); }
+
+    /// This class is true if option is passed.
+    operator bool() const { return !empty(); }
+
+    /// Clear the parsed results (mostly for testing)
+    void clear() { results_.clear(); }
+
+    ///@}
+    /// @name Setting options
+    ///@{
+
+    /// Set the number of expected arguments (Flags don't use this)
+    Option *expected(int value) {
+        // Break if this is a flag
+        if(type_size_ == 0)
+            throw IncorrectConstruction::SetFlag(get_name(true, true));
+
+        // Setting 0 is not allowed
+        else if(value == 0)
+            throw IncorrectConstruction::Set0Opt(get_name());
+
+        // No change is okay, quit now
+        else if(expected_ == value)
+            return this;
+
+        // Type must be a vector
+        else if(type_size_ >= 0)
+            throw IncorrectConstruction::ChangeNotVector(get_name());
+
+        // TODO: Can support multioption for non-1 values (except for join)
+        else if(value != 1 && multi_option_policy_ != MultiOptionPolicy::Throw)
+            throw IncorrectConstruction::AfterMultiOpt(get_name());
+
+        expected_ = value;
+        return this;
+    }
+
+    /// Adds a validator with a built in type name
+    Option *check(const Validator &validator) {
+        validators_.emplace_back(validator.func);
+        if(!validator.tname.empty())
+            type_name(validator.tname);
+        return this;
+    }
+
+    /// 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) {
+        validators_.emplace_back(validator);
+        return this;
+    }
+
+    /// Adds a validator-like function that can change result
+    Option *transform(std::function<std::string(std::string)> func) {
+        validators_.emplace_back([func](std::string &inout) {
+            try {
+                inout = func(inout);
+            } catch(const ValidationError &e) {
+                return std::string(e.what());
+            }
+            return std::string();
+        });
+        return this;
+    }
+
+    /// Adds a user supplied function to run on each item passed in (communicate though lambda capture)
+    Option *each(std::function<void(std::string)> func) {
+        validators_.emplace_back([func](std::string &inout) {
+            func(inout);
+            return std::string();
+        });
+        return this;
+    }
+
+    /// Sets required options
+    Option *needs(Option *opt) {
+        auto tup = requires_.insert(opt);
+        if(!tup.second)
+            throw OptionAlreadyAdded::Requires(get_name(), opt->get_name());
+        return this;
+    }
+
+    /// Can find a string if needed
+    template <typename T = App> Option *needs(std::string opt_name) {
+        for(const Option_p &opt : dynamic_cast<T *>(parent_)->options_)
+            if(opt.get() != this && opt->check_name(opt_name))
+                return needs(opt.get());
+        throw IncorrectConstruction::MissingOption(opt_name);
+    }
+
+    /// 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...);
+    }
+
+    /// Sets excluded options
+    Option *excludes(Option *opt) {
+        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;
+    }
+
+    /// Can find a string if needed
+    template <typename T = App> Option *excludes(std::string opt_name) {
+        for(const Option_p &opt : dynamic_cast<T *>(parent_)->options_)
+            if(opt.get() != this && opt->check_name(opt_name))
+                return excludes(opt.get());
+        throw IncorrectConstruction::MissingOption(opt_name);
+    }
+
+    /// 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...);
+    }
+
+    /// Sets environment variable to read if no option given
+    Option *envname(std::string name) {
+        envname_ = 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_case_ = value;
+        auto *parent = dynamic_cast<T *>(parent_);
+
+        for(const Option_p &opt : parent->options_)
+            if(opt.get() != this && *opt == *this)
+                throw OptionAlreadyAdded(opt->get_name(true, true));
+
+        return this;
+    }
+
+    /// Take the last argument if given multiple times (or another policy)
+    Option *multi_option_policy(MultiOptionPolicy value = MultiOptionPolicy::Throw) {
+
+        if(get_items_expected() < 0)
+            throw IncorrectConstruction::MultiOptionPolicy(get_name());
+        multi_option_policy_ = value;
+        return this;
+    }
+
+    /// Options with a short circuit set will run this function before parsing is finished.
+    ///
+    /// This is set on help functions, for example, to escape the normal validation.
+    Option *short_circuit(bool value = true) {
+        short_circuit_ = value;
+        return this;
+    }
+
+    ///@}
+    /// @name Accessors
+    ///@{
+
+    /// The number of arguments the option expects
+    int get_type_size() const { return type_size_; }
+
+    /// The environment variable associated to this value
+    std::string get_envname() const { return envname_; }
+
+    /// The set of options needed
+    std::set<Option *> get_needs() const { return requires_; }
+
+    /// The set of options excluded
+    std::set<Option *> get_excludes() const { return excludes_; }
+
+    /// The default value (for help printing)
+    std::string get_defaultval() const { return defaultval_; }
+
+    /// See if this is supposed to short circuit (skip validation, INI, etc) (Used for help flags)
+    bool get_short_circuit() const { return short_circuit_; }
+
+    /// Get the callback function
+    callback_t get_callback() const { return callback_; }
+
+    /// Get the long names
+    const std::vector<std::string> get_lnames() const { return lnames_; }
+
+    /// Get the short names
+    const std::vector<std::string> get_snames() const { return snames_; }
+
+    /// The number of times the option expects to be included
+    int get_expected() const { return expected_; }
+
+    /// \brief The total number of expected values (including the type)
+    /// This is positive if exactly this number is expected, and negitive for at least N values
+    ///
+    /// v = fabs(size_type*expected)
+    /// !MultiOptionPolicy::Throw
+    ///           | Expected < 0  | Expected == 0 | Expected > 0
+    /// Size < 0  |      -v       |       0       |     -v
+    /// Size == 0 |       0       |       0       |      0
+    /// Size > 0  |      -v       |       0       |     -v       // Expected must be 1
+    ///
+    /// MultiOptionPolicy::Throw
+    ///           | Expected < 0  | Expected == 0 | Expected > 0
+    /// Size < 0  |      -v       |       0       |      v
+    /// Size == 0 |       0       |       0       |      0
+    /// Size > 0  |       v       |       0       |      v      // Expected must be 1
+    ///
+    int get_items_expected() const {
+        return std::abs(type_size_ * expected_) *
+               ((multi_option_policy_ != MultiOptionPolicy::Throw || (expected_ < 0 && type_size_ < 0) ? -1 : 1));
+    }
+
+    /// True if this has a default value
+    int get_default() const { return default_; }
+
+    /// True if the argument can be given directly
+    bool get_positional() const { return pname_.length() > 0; }
+
+    /// True if option has at least one non-positional name
+    bool nonpositional() const { return (snames_.size() + lnames_.size()) > 0; }
+
+    /// True if option has description
+    bool has_description() const { return description_.length() > 0; }
+
+    /// Get the description
+    const std::string &get_description() const { return description_; }
+
+    ///@}
+    /// @name Help tools
+    ///@{
+
+    /// \brief Gets a comma seperated 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`)
+    std::string get_name(bool positional = false, //<[input] Show the positional name
+                         bool all_options = false //<[input] Show every option
+                         ) const {
+
+        if(all_options) {
+
+            std::vector<std::string> name_list;
+
+            /// The all list wil never include a positional unless asked or that's the only name.
+            if((positional && pname_.length()) || (snames_.empty() && lnames_.empty()))
+                name_list.push_back(pname_);
+
+            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);
+
+        } else {
+
+            // This returns the positional name no matter what
+            if(positional)
+                return pname_;
+
+            // Prefer long name
+            else if(!lnames_.empty())
+                return std::string("--") + lnames_[0];
+
+            // Or short name if no long name
+            else if(!snames_.empty())
+                return std::string("-") + snames_[0];
+
+            // If positional is the only name, it's okay to use that
+            else
+                return pname_;
+        }
+    }
+
+    ///@}
+    /// @name Parser tools
+    ///@{
+
+    /// Process the callback
+    void run_callback() {
+
+        // Run the validators (can change the string)
+        if(!validators_.empty()) {
+            for(std::string &result : results_)
+                for(const std::function<std::string(std::string &)> &vali : validators_) {
+                    std::string err_msg = vali(result);
+                    if(!err_msg.empty())
+                        throw ValidationError(get_name(), err_msg);
+                }
+        }
+
+        bool local_result;
+
+        // Num items expected or length of vector, always at least 1
+        // Only valid for a trimming policy
+        int trim_size =
+            std::min<int>(std::max<int>(std::abs(get_items_expected()), 1), static_cast<int>(results_.size()));
+
+        // Operation depends on the policy setting
+        if(multi_option_policy_ == MultiOptionPolicy::TakeLast) {
+            // Allow multi-option sizes (including 0)
+            results_t partial_result{results_.end() - trim_size, results_.end()};
+            local_result = !callback_(partial_result);
+
+        } else if(multi_option_policy_ == MultiOptionPolicy::TakeFirst) {
+            results_t partial_result{results_.begin(), results_.begin() + trim_size};
+            local_result = !callback_(partial_result);
+
+        } else if(multi_option_policy_ == MultiOptionPolicy::Join) {
+            results_t partial_result = {detail::join(results_, "\n")};
+            local_result = !callback_(partial_result);
+
+        } else {
+            // Exact number required
+            if(get_items_expected() > 0) {
+                if(results_.size() != static_cast<size_t>(get_items_expected()))
+                    throw ArgumentMismatch(get_name(), get_items_expected(), results_.size());
+                // Variable length list
+            } else if(get_items_expected() < 0) {
+                // Require that this be a multiple of expected size and at least as many as expected
+                if(results_.size() < static_cast<size_t>(-get_items_expected()) ||
+                   results_.size() % static_cast<size_t>(std::abs(get_type_size())) != 0)
+                    throw ArgumentMismatch(get_name(), get_items_expected(), results_.size());
+            }
+            local_result = !callback_(results_);
+        }
+
+        if(local_result)
+            throw ConversionError(get_name(), results_);
+    }
+
+    /// If options share any of the same names, they are equal (not counting positional)
+    bool operator==(const Option &other) const {
+        for(const std::string &sname : snames_)
+            if(other.check_sname(sname))
+                return true;
+        for(const std::string &lname : lnames_)
+            if(other.check_lname(lname))
+                return true;
+        // We need to do the inverse, just in case we are ignore_case
+        for(const std::string &sname : other.snames_)
+            if(check_sname(sname))
+                return true;
+        for(const std::string &lname : other.lnames_)
+            if(check_lname(lname))
+                return true;
+        return false;
+    }
+
+    /// Check a name. Requires "-" or "--" for short / long, supports positional name
+    bool check_name(std::string name) const {
+
+        if(name.length() > 2 && name.substr(0, 2) == "--")
+            return check_lname(name.substr(2));
+        else if(name.length() > 1 && name.substr(0, 1) == "-")
+            return check_sname(name.substr(1));
+        else {
+            std::string local_pname = pname_;
+            if(ignore_case_) {
+                local_pname = detail::to_lower(local_pname);
+                name = detail::to_lower(name);
+            }
+            return name == local_pname;
+        }
+    }
+
+    /// Requires "-" to be removed from string
+    bool check_sname(std::string name) const {
+        if(ignore_case_) {
+            name = detail::to_lower(name);
+            return std::find_if(std::begin(snames_), std::end(snames_), [&name](std::string local_sname) {
+                       return detail::to_lower(local_sname) == name;
+                   }) != std::end(snames_);
+        } else
+            return std::find(std::begin(snames_), std::end(snames_), name) != std::end(snames_);
+    }
+
+    /// Requires "--" to be removed from string
+    bool check_lname(std::string name) const {
+        if(ignore_case_) {
+            name = detail::to_lower(name);
+            return std::find_if(std::begin(lnames_), std::end(lnames_), [&name](std::string local_sname) {
+                       return detail::to_lower(local_sname) == name;
+                   }) != std::end(lnames_);
+        } else
+            return std::find(std::begin(lnames_), std::end(lnames_), name) != std::end(lnames_);
+    }
+
+    /// Puts a result at the end
+    Option *add_result(std::string s) {
+        results_.push_back(s);
+        callback_run_ = false;
+        return this;
+    }
+
+    /// Set the results vector all at once
+    Option *set_results(std::vector<std::string> results) {
+        results_ = results;
+        callback_run_ = false;
+        return this;
+    }
+
+    /// Get a copy of the results
+    std::vector<std::string> results() const { return results_; }
+
+    /// See if the callback has been run already
+    bool get_callback_run() const { return 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_ = typefun;
+        return this;
+    }
+
+    /// Set a custom option typestring
+    Option *type_name(std::string typeval) {
+        type_name_fn([typeval]() { return typeval; });
+        return this;
+    }
+
+    /// Provided for backward compatibility \deprecated
+    CLI11_DEPRECATED("Please use type_name instead")
+    Option *set_type_name(std::string typeval) { return type_name(typeval); }
+
+    /// Set a custom option size
+    Option *type_size(int type_size) {
+        type_size_ = type_size;
+        if(type_size_ == 0)
+            required_ = false;
+        if(type_size < 0)
+            expected_ = -1;
+        return this;
+    }
+
+    /// Set the default value string representation
+    Option *default_str(std::string val) {
+        defaultval_ = val;
+        return this;
+    }
+
+    /// Set the default value string representation and evaluate
+    Option *default_val(std::string val) {
+        default_str(val);
+        auto old_results = results_;
+        results_ = {val};
+        run_callback();
+        results_ = std::move(old_results);
+        return this;
+    }
+
+    /// Get the typename for this option
+    std::string get_type_name() const { return type_name_(); }
+};
+
+} // namespace CLI
+
+// From CLI/App.hpp:
+
+namespace CLI {
+
+#ifndef CLI11_PARSE
+#define CLI11_PARSE(app, argc, argv)                                                                                   \
+    try {                                                                                                              \
+        (app).parse((argc), (argv));                                                                                   \
+    } catch(const CLI::ParseError &e) {                                                                                \
+        return (app).exit(e);                                                                                          \
+    }
+#endif
+
+namespace detail {
+enum class Classifer { NONE, POSITIONAL_MARK, SHORT, LONG, SUBCOMMAND };
+struct AppFriend;
+} // namespace detail
+
+namespace FailureMessage {
+std::string simple(const App *app, const Error &e);
+std::string help(const App *app, const Error &e);
+} // namespace FailureMessage
+
+class App;
+
+using App_p = std::unique_ptr<App>;
+
+/// 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
+    bool allow_extras_{false};
+
+    /// If true, allow extra arguments in the ini file (ie, don't throw an error). INHERITABLE
+    bool allow_config_extras_{false};
+
+    ///  If true, return immediately on an unrecognised option (implies allow_extras) INHERITABLE
+    bool prefix_command_{false};
+
+    /// This is a function that runs when complete. Great for subcommands. Can throw.
+    std::function<void()> 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
+    ///@{
+
+    /// Footer to put after all options in the help output INHERITABLE
+    std::string footer_;
+
+    /// 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};
+
+    /// 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::Classifer, 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_;
+
+    ///@}
+    /// @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};
+
+    /// Allow subcommand fallthrough, so that parent commands can collect commands after subcommand.  INHERITABLE
+    bool fallthrough_{false};
+
+    /// A pointer to the parent if this is a subcommand
+    App *parent_{nullptr};
+
+    /// True if this command/subcommand was parsed
+    bool parsed_{false};
+
+    /// Minimum required subcommands (not inheritable!)
+    size_t require_subcommand_min_ = 0;
+
+    /// Max number of subcommands allowed (parsing stops after this number). 0 is unlimited INHERITABLE
+    size_t require_subcommand_max_ = 0;
+
+    /// The group membership INHERITABLE
+    std::string group_{"Subcommands"};
+
+    ///@}
+    /// @name Config
+    ///@{
+
+    /// The name of the connected config file
+    std::string config_name_;
+
+    /// True if ini is required (throws if not present), if false simply keep going.
+    bool config_required_{false};
+
+    /// 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 ConfigINI()};
+
+    ///@}
+
+    /// Special private constructor for subcommand
+    App(std::string description_, std::string name, App *parent)
+        : name_(std::move(name)), description_(std::move(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_;
+            ignore_case_ = parent_->ignore_case_;
+            fallthrough_ = parent_->fallthrough_;
+            group_ = parent_->group_;
+            footer_ = parent_->footer_;
+            formatter_ = parent_->formatter_;
+            config_formatter_ = parent_->config_formatter_;
+            require_subcommand_max_ = parent_->require_subcommand_max_;
+        }
+    }
+
+  public:
+    /// @name Basic
+    ///@{
+
+    /// Create a new program. Pass in the same arguments as main(), along with a help string.
+    explicit App(std::string description_ = "", std::string name = "") : App(description_, name, nullptr) {
+        set_help_flag("-h,--help", "Print this help message and exit");
+    }
+
+    /// virtual destructor
+    virtual ~App() = default;
+
+    /// Set a callback for the end of parsing.
+    ///
+    /// 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()> callback) {
+        callback_ = callback;
+        return this;
+    }
+
+    /// Set a name for the app (empty will use parser to set the name)
+    App *name(std::string name = "") {
+        name_ = name;
+        return this;
+    }
+
+    /// Remove the error when extras are left over on the command line.
+    App *allow_extras(bool allow = true) {
+        allow_extras_ = allow;
+        return this;
+    }
+
+    /// Remove the error when extras are left over on the command line.
+    /// Will also call App::allow_extras().
+    App *allow_config_extras(bool allow = true) {
+        allow_extras(allow);
+        allow_config_extras_ = allow;
+        return this;
+    }
+
+    /// Do not parse anything after the first unrecognised option and return
+    App *prefix_command(bool allow = true) {
+        prefix_command_ = allow;
+        return this;
+    }
+
+    /// Ignore case. Subcommand inherit value.
+    App *ignore_case(bool value = true) {
+        ignore_case_ = value;
+        if(parent_ != nullptr) {
+            for(const auto &subc : parent_->subcommands_) {
+                if(subc.get() != this && (this->check_name(subc->name_) || subc->check_name(this->name_)))
+                    throw OptionAlreadyAdded(subc->name_);
+            }
+        }
+        return this;
+    }
+
+    /// 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.
+    bool parsed() const { return parsed_; }
+
+    /// 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 name, callback_t callback, std::string description = "", bool defaulted = false) {
+        Option myopt{name, description, callback, defaulted, this};
+
+        if(std::find_if(std::begin(options_), std::end(options_), [&myopt](const Option_p &v) {
+               return *v == myopt;
+           }) == std::end(options_)) {
+            options_.emplace_back();
+            Option_p &option = options_.back();
+            option.reset(new Option(name, description, callback, defaulted, this));
+            option_defaults_.copy_to(option.get());
+            return option.get();
+        } else
+            throw OptionAlreadyAdded(myopt.get_name());
+    }
+
+    /// Add option for non-vectors (duplicate copy needed without defaulted to avoid `iostream << value`)
+    template <typename T, enable_if_t<!is_vector<T>::value, detail::enabler> = detail::dummy>
+    Option *add_option(std::string name,
+                       T &variable, ///< The variable to set
+                       std::string description = "") {
+
+        CLI::callback_t fun = [&variable](CLI::results_t res) { return detail::lexical_cast(res[0], variable); };
+
+        Option *opt = add_option(name, fun, description, false);
+        opt->type_name(detail::type_name<T>());
+        return opt;
+    }
+
+    /// Add option for non-vectors with a default print
+    template <typename T, enable_if_t<!is_vector<T>::value, detail::enabler> = detail::dummy>
+    Option *add_option(std::string name,
+                       T &variable, ///< The variable to set
+                       std::string description,
+                       bool defaulted) {
+
+        CLI::callback_t fun = [&variable](CLI::results_t res) { return detail::lexical_cast(res[0], variable); };
+
+        Option *opt = add_option(name, fun, description, defaulted);
+        opt->type_name(detail::type_name<T>());
+        if(defaulted) {
+            std::stringstream out;
+            out << variable;
+            opt->default_str(out.str());
+        }
+        return opt;
+    }
+
+    /// Add option for vectors (no default)
+    template <typename T>
+    Option *add_option(std::string name,
+                       std::vector<T> &variable, ///< The variable vector to set
+                       std::string description = "") {
+
+        CLI::callback_t fun = [&variable](CLI::results_t res) {
+            bool retval = true;
+            variable.clear();
+            for(const auto &a : res) {
+                variable.emplace_back();
+                retval &= detail::lexical_cast(a, variable.back());
+            }
+            return (!variable.empty()) && retval;
+        };
+
+        Option *opt = add_option(name, fun, description, false);
+        opt->type_name(detail::type_name<T>())->type_size(-1);
+        return opt;
+    }
+
+    /// Add option for vectors
+    template <typename T>
+    Option *add_option(std::string name,
+                       std::vector<T> &variable, ///< The variable vector to set
+                       std::string description,
+                       bool defaulted) {
+
+        CLI::callback_t fun = [&variable](CLI::results_t res) {
+            bool retval = true;
+            variable.clear();
+            for(const auto &a : res) {
+                variable.emplace_back();
+                retval &= detail::lexical_cast(a, variable.back());
+            }
+            return (!variable.empty()) && retval;
+        };
+
+        Option *opt = add_option(name, fun, description, defaulted);
+        opt->type_name(detail::type_name<T>())->type_size(-1);
+        if(defaulted)
+            opt->default_str("[" + detail::join(variable) + "]");
+        return opt;
+    }
+
+    /// Set a help flag, replace the existing one if present
+    Option *set_help_flag(std::string name = "", std::string description = "") {
+        if(help_ptr_ != nullptr) {
+            remove_option(help_ptr_);
+            help_ptr_ = nullptr;
+        }
+
+        // Empty name will simply remove the help flag
+        if(!name.empty()) {
+            help_ptr_ = add_flag_function(name, [](size_t) -> void { throw CallForHelp(); }, description);
+            help_ptr_->short_circuit(true);
+            help_ptr_->configurable(false);
+        }
+
+        return help_ptr_;
+    }
+
+    /// Set a help all flag, replaced the existing one if present
+    Option *set_help_all_flag(std::string name = "", std::string 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(!name.empty()) {
+            help_all_ptr_ = add_flag_function(name, [](size_t) -> void { throw CallForAllHelp(); }, description);
+            help_all_ptr_->short_circuit(true);
+            help_all_ptr_->configurable(false);
+        }
+
+        return help_all_ptr_;
+    }
+
+    /// Add option for flag
+    Option *add_flag(std::string name, std::string description = "") {
+        CLI::callback_t fun = [](CLI::results_t) { return true; };
+
+        Option *opt = add_option(name, fun, description, false);
+        if(opt->get_positional())
+            throw IncorrectConstruction::PositionalFlag(name);
+        opt->type_size(0);
+        return opt;
+    }
+
+    /// Add option for flag integer
+    template <typename T,
+              enable_if_t<std::is_integral<T>::value && !is_bool<T>::value, detail::enabler> = detail::dummy>
+    Option *add_flag(std::string name,
+                     T &count, ///< A variable holding the count
+                     std::string description = "") {
+
+        count = 0;
+        CLI::callback_t fun = [&count](CLI::results_t res) {
+            count = static_cast<T>(res.size());
+            return true;
+        };
+
+        Option *opt = add_option(name, fun, description, false);
+        if(opt->get_positional())
+            throw IncorrectConstruction::PositionalFlag(name);
+        opt->type_size(0);
+        return opt;
+    }
+
+    /// Bool version - defaults to allowing multiple passings, but can be forced to one if
+    /// `multi_option_policy(CLI::MultiOptionPolicy::Throw)` is used.
+    template <typename T, enable_if_t<is_bool<T>::value, detail::enabler> = detail::dummy>
+    Option *add_flag(std::string name,
+                     T &count, ///< A variable holding true if passed
+                     std::string description = "") {
+
+        count = false;
+        CLI::callback_t fun = [&count](CLI::results_t res) {
+            count = true;
+            return res.size() == 1;
+        };
+
+        Option *opt = add_option(name, fun, description, false);
+        if(opt->get_positional())
+            throw IncorrectConstruction::PositionalFlag(name);
+        opt->type_size(0);
+        opt->multi_option_policy(CLI::MultiOptionPolicy::TakeLast);
+        return opt;
+    }
+
+    /// Add option for callback
+    Option *add_flag_function(std::string name,
+                              std::function<void(size_t)> function, ///< A function to call, void(size_t)
+                              std::string description = "") {
+
+        CLI::callback_t fun = [function](CLI::results_t res) {
+            auto count = static_cast<size_t>(res.size());
+            function(count);
+            return true;
+        };
+
+        Option *opt = add_option(name, fun, description, false);
+        if(opt->get_positional())
+            throw IncorrectConstruction::PositionalFlag(name);
+        opt->type_size(0);
+        return opt;
+    }
+
+#ifdef CLI11_CPP14
+    /// Add option for callback (C++14 or better only)
+    Option *add_flag(std::string name,
+                     std::function<void(size_t)> function, ///< A function to call, void(size_t)
+                     std::string description = "") {
+        return add_flag_function(name, function, description);
+    }
+#endif
+
+    /// Add set of options (No default, temp refernce, such as an inline set)
+    template <typename T>
+    Option *add_set(std::string name,
+                    T &member,                   ///< The selected member of the set
+                    const std::set<T> &&options, ///< The set of possibilities
+                    std::string description = "") {
+
+        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
+            bool retval = detail::lexical_cast(res[0], member);
+            if(!retval)
+                throw ConversionError(res[0], simple_name);
+            return std::find(std::begin(options), std::end(options), member) != std::end(options);
+        };
+
+        Option *opt = add_option(name, fun, description, false);
+        std::string typeval = detail::type_name<T>();
+        typeval += " in {" + detail::join(options) + "}";
+        opt->type_name(typeval);
+        return opt;
+    }
+
+    /// Add set of options (No default, non-temp refernce, such as an existing set)
+    template <typename T>
+    Option *add_set(std::string name,
+                    T &member,                  ///< The selected member of the set
+                    const std::set<T> &options, ///< The set of possibilities
+                    std::string description = "") {
+
+        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
+            bool retval = detail::lexical_cast(res[0], member);
+            if(!retval)
+                throw ConversionError(res[0], simple_name);
+            return std::find(std::begin(options), std::end(options), member) != std::end(options);
+        };
+
+        Option *opt = add_option(name, fun, description, false);
+        opt->type_name_fn(
+            [&options]() { return std::string(detail::type_name<T>()) + " in {" + detail::join(options) + "}"; });
+
+        return opt;
+    }
+
+    /// Add set of options (with default, R value, such as an inline set)
+    template <typename T>
+    Option *add_set(std::string name,
+                    T &member,                   ///< The selected member of the set
+                    const std::set<T> &&options, ///< The set of posibilities
+                    std::string description,
+                    bool defaulted) {
+
+        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
+            bool retval = detail::lexical_cast(res[0], member);
+            if(!retval)
+                throw ConversionError(res[0], simple_name);
+            return std::find(std::begin(options), std::end(options), member) != std::end(options);
+        };
+
+        Option *opt = add_option(name, fun, description, defaulted);
+        std::string typeval = detail::type_name<T>();
+        typeval += " in {" + detail::join(options) + "}";
+        opt->type_name(typeval);
+        if(defaulted) {
+            std::stringstream out;
+            out << member;
+            opt->default_str(out.str());
+        }
+        return opt;
+    }
+
+    /// Add set of options (with default, L value refernce, such as an existing set)
+    template <typename T>
+    Option *add_set(std::string name,
+                    T &member,                  ///< The selected member of the set
+                    const std::set<T> &options, ///< The set of posibilities
+                    std::string description,
+                    bool defaulted) {
+
+        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
+            bool retval = detail::lexical_cast(res[0], member);
+            if(!retval)
+                throw ConversionError(res[0], simple_name);
+            return std::find(std::begin(options), std::end(options), member) != std::end(options);
+        };
+
+        Option *opt = add_option(name, fun, description, defaulted);
+        opt->type_name_fn(
+            [&options]() { return std::string(detail::type_name<T>()) + " in {" + detail::join(options) + "}"; });
+        if(defaulted) {
+            std::stringstream out;
+            out << member;
+            opt->default_str(out.str());
+        }
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore case (no default, R value)
+    Option *add_set_ignore_case(std::string name,
+                                std::string &member,                   ///< The selected member of the set
+                                const std::set<std::string> &&options, ///< The set of possibilities
+                                std::string description = "") {
+
+        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
+            member = detail::to_lower(res[0]);
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::to_lower(val) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(name, fun, description, false);
+        std::string typeval = detail::type_name<std::string>();
+        typeval += " in {" + detail::join(options) + "}";
+        opt->type_name(typeval);
+
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore case (no default, L value)
+    Option *add_set_ignore_case(std::string name,
+                                std::string &member,                  ///< The selected member of the set
+                                const std::set<std::string> &options, ///< The set of possibilities
+                                std::string description = "") {
+
+        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
+            member = detail::to_lower(res[0]);
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::to_lower(val) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(name, fun, description, false);
+        opt->type_name_fn([&options]() {
+            return std::string(detail::type_name<std::string>()) + " in {" + detail::join(options) + "}";
+        });
+
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore case (default, R value)
+    Option *add_set_ignore_case(std::string name,
+                                std::string &member,                   ///< The selected member of the set
+                                const std::set<std::string> &&options, ///< The set of posibilities
+                                std::string description,
+                                bool defaulted) {
+
+        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        CLI::callback_t fun = [&member, options, simple_name](CLI::results_t res) {
+            member = detail::to_lower(res[0]);
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::to_lower(val) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(name, fun, description, defaulted);
+        std::string typeval = detail::type_name<std::string>();
+        typeval += " in {" + detail::join(options) + "}";
+        opt->type_name(typeval);
+        if(defaulted) {
+            opt->default_str(member);
+        }
+        return opt;
+    }
+
+    /// Add set of options, string only, ignore case (default, L value)
+    Option *add_set_ignore_case(std::string name,
+                                std::string &member,                  ///< The selected member of the set
+                                const std::set<std::string> &options, ///< The set of posibilities
+                                std::string description,
+                                bool defaulted) {
+
+        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        CLI::callback_t fun = [&member, &options, simple_name](CLI::results_t res) {
+            member = detail::to_lower(res[0]);
+            auto iter = std::find_if(std::begin(options), std::end(options), [&member](std::string val) {
+                return detail::to_lower(val) == member;
+            });
+            if(iter == std::end(options))
+                throw ConversionError(member, simple_name);
+            else {
+                member = *iter;
+                return true;
+            }
+        };
+
+        Option *opt = add_option(name, fun, description, defaulted);
+        opt->type_name_fn([&options]() {
+            return std::string(detail::type_name<std::string>()) + " in {" + detail::join(options) + "}";
+        });
+        if(defaulted) {
+            opt->default_str(member);
+        }
+        return opt;
+    }
+
+    /// Add a complex number
+    template <typename T>
+    Option *add_complex(std::string name,
+                        T &variable,
+                        std::string description = "",
+                        bool defaulted = false,
+                        std::string label = "COMPLEX") {
+
+        std::string simple_name = CLI::detail::split(name, ',').at(0);
+        CLI::callback_t fun = [&variable, simple_name, label](results_t res) {
+            if(res[1].back() == 'i')
+                res[1].pop_back();
+            double x, y;
+            bool worked = detail::lexical_cast(res[0], x) && detail::lexical_cast(res[1], y);
+            if(worked)
+                variable = T(x, y);
+            return worked;
+        };
+
+        CLI::Option *opt = add_option(name, fun, description, defaulted);
+        opt->type_name(label)->type_size(2);
+        if(defaulted) {
+            std::stringstream out;
+            out << variable;
+            opt->default_str(out.str());
+        }
+        return opt;
+    }
+
+    /// Set a configuration ini file option, or clear it if no name passed
+    Option *set_config(std::string name = "",
+                       std::string default_filename = "",
+                       std::string help = "Read an ini file",
+                       bool required = false) {
+
+        // Remove existing config if present
+        if(config_ptr_ != nullptr)
+            remove_option(config_ptr_);
+
+        // Only add config if option passed
+        if(!name.empty()) {
+            config_name_ = default_filename;
+            config_required_ = required;
+            config_ptr_ = add_option(name, config_name_, help, !default_filename.empty());
+            config_ptr_->configurable(false);
+        }
+
+        return config_ptr_;
+    }
+
+    /// Removes an option from the App. Takes an option pointer. Returns true if found and removed.
+    bool remove_option(Option *opt) {
+        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;
+    }
+
+    ///@}
+    /// @name Subcommmands
+    ///@{
+
+    /// Add a subcommand. Inherits INHERITABLE and OptionDefaults, and help flag
+    App *add_subcommand(std::string name, std::string description = "") {
+        subcommands_.emplace_back(new App(description, name, this));
+        for(const auto &subc : subcommands_)
+            if(subc.get() != subcommands_.back().get())
+                if(subc->check_name(subcommands_.back()->name_) || subcommands_.back()->check_name(subc->name_))
+                    throw OptionAlreadyAdded(subc->name_);
+        return subcommands_.back().get();
+    }
+
+    /// Check to see if a subcommand is part of this command (doesn't have to be in command line)
+    App *get_subcommand(App *subcom) const {
+        for(const App_p &subcomptr : subcommands_)
+            if(subcomptr.get() == subcom)
+                return subcom;
+        throw OptionNotFound(subcom->get_name());
+    }
+
+    /// Check to see if a subcommand is part of this command (text version)
+    App *get_subcommand(std::string subcom) const {
+        for(const App_p &subcomptr : subcommands_)
+            if(subcomptr->check_name(subcom))
+                return subcomptr.get();
+        throw OptionNotFound(subcom);
+    }
+
+    /// Changes the group membership
+    App *group(std::string name) {
+        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<size_t>(-value);
+        } else {
+            require_subcommand_min_ = static_cast<size_t>(value);
+            require_subcommand_max_ = static_cast<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(size_t min, size_t max) {
+        require_subcommand_min_ = min;
+        require_subcommand_max_ = max;
+        return this;
+    }
+
+    /// Stop subcommand fallthrough, so that parent commands cannot collect commands after subcommand.
+    /// Default from parent, usually set on parent.
+    App *fallthrough(bool value = true) {
+        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.
+    operator bool() const { return parsed_; }
+
+    ///@}
+    /// @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() {
+
+        parsed_ = false;
+        missing_.clear();
+        parsed_subcommands_.clear();
+
+        for(const Option_p &opt : options_) {
+            opt->clear();
+        }
+        for(const App_p &app : subcommands_) {
+            app->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) {
+        // If the name is not set, read from command line
+        if(name_.empty())
+            name_ = argv[0];
+
+        std::vector<std::string> args;
+        for(int i = argc - 1; i > 0; i--)
+            args.emplace_back(argv[i]);
+        parse(args);
+    }
+
+    /// The real work is done here. Expects a reversed vector.
+    /// Changes the vector to the remaining options.
+    void parse(std::vector<std::string> &args) {
+        // Clear if parsed
+        if(parsed_)
+            clear();
+
+        // Redundant (set by _parse on commands/subcommands)
+        // but placed here to make sure this is cleared when
+        // running parse after an error is thrown, even by _validate.
+        parsed_ = true;
+
+        _validate();
+        _parse(args);
+        run_callback();
+    }
+
+    /// 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 {
+
+        /// Avoid printing anything if this is a CLI::RuntimeError
+        if(dynamic_cast<const CLI::RuntimeError *>(&e) != nullptr)
+            return e.get_exit_code();
+
+        if(dynamic_cast<const CLI::CallForHelp *>(&e) != nullptr) {
+            out << help();
+            return e.get_exit_code();
+        }
+
+        if(dynamic_cast<const CLI::CallForAllHelp *>(&e) != nullptr) {
+            out << help("", AppFormatMode::All);
+            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();
+    }
+
+    ///@}
+    /// @name Post parsing
+    ///@{
+
+    /// Counts the number of times the given option was passed.
+    size_t count(std::string name) const {
+        for(const Option_p &opt : options_) {
+            if(opt->check_name(name)) {
+                return opt->count();
+            }
+        }
+        throw OptionNotFound(name);
+    }
+
+    /// Get a subcommand pointer list to the currently selected subcommands (after parsing by by default, in command
+    /// line order; use parsed = false to get the original definition list.)
+    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 {
+        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;
+    }
+
+    /// 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) {
+        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;
+    }
+
+    /// Check to see if given subcommand was selected
+    bool got_subcommand(App *subcom) const {
+        // get subcom needed to verify that this was a real subcommand
+        return get_subcommand(subcom)->parsed_;
+    }
+
+    /// Check with name instead of pointer to see if subcommand was selected
+    bool got_subcommand(std::string name) const { return get_subcommand(name)->parsed_; }
+
+    ///@}
+    /// @name Help
+    ///@{
+
+    /// Set footer.
+    App *footer(std::string footer) {
+        footer_ = footer;
+        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. Prefix will add a string to the beginning of each option.
+    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
+    std::string help(std::string prev = "", AppFormatMode mode = AppFormatMode::Normal) 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.at(0)->help(prev);
+        else
+            return formatter_->make_help(this, prev, mode);
+    }
+
+    /// Provided for backwards compatibility \deprecated
+    CLI11_DEPRECATED("Please use footer instead")
+    App *set_footer(std::string msg) { return footer(msg); }
+
+    /// Provided for backwards compatibility \deprecated
+    CLI11_DEPRECATED("Please use name instead")
+    App *set_name(std::string msg) { return name(msg); }
+
+    /// Provided for backwards compatibility \deprecated
+    CLI11_DEPRECATED("Please use callback instead")
+    App *set_callback(std::function<void()> fn) { return callback(fn); }
+
+    ///@}
+    /// @name Getters
+    ///@{
+
+    /// Access the formatter
+    std::shared_ptr<FormatterBase> get_formatter() const { return formatter_; }
+
+    /// Access the config formatter
+    std::shared_ptr<Config> get_config_formatter() const { return config_formatter_; }
+
+    /// Get the app or subcommand description
+    std::string get_description() const { return description_; }
+
+    /// 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 {
+        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));
+        }
+
+        return options;
+    }
+
+    /// Get an option by name
+    const Option *get_option(std::string name) const {
+        for(const Option_p &opt : options_) {
+            if(opt->check_name(name)) {
+                return opt.get();
+            }
+        }
+        throw OptionNotFound(name);
+    }
+
+    /// Get an option by name (non-const version)
+    Option *get_option(std::string name) {
+        for(Option_p &opt : options_) {
+            if(opt->check_name(name)) {
+                return opt.get();
+            }
+        }
+        throw OptionNotFound(name);
+    }
+
+    /// Check the status of ignore_case
+    bool get_ignore_case() const { return ignore_case_; }
+
+    /// Check the status of fallthrough
+    bool get_fallthrough() const { return fallthrough_; }
+
+    /// Get the group of this subcommand
+    const std::string &get_group() const { return group_; }
+
+    /// Get footer.
+    std::string get_footer() const { return footer_; }
+
+    /// Get the required min subcommand value
+    size_t get_require_subcommand_min() const { return require_subcommand_min_; }
+
+    /// Get the required max subcommand value
+    size_t get_require_subcommand_max() const { return require_subcommand_max_; }
+
+    /// Get the prefix command status
+    bool get_prefix_command() const { return prefix_command_; }
+
+    /// Get the status of allow extras
+    bool get_allow_extras() const { return allow_extras_; }
+
+    /// Get the status of allow extras
+    bool get_allow_config_extras() const { return 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)
+    const Option *get_help_ptr() const { return help_ptr_; }
+
+    /// Get a pointer to the help all flag. (const)
+    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)
+    const Option *get_config_ptr() const { return config_ptr_; }
+
+    /// Get the parent of this subcommand (or nullptr if master app)
+    App *get_parent() { return parent_; }
+
+    /// Get the parent of this subcommand (or nullptr if master app) (const version)
+    const App *get_parent() const { return parent_; }
+
+    /// Get the name of the current app
+    std::string get_name() const { return name_; }
+
+    /// Check the name, case insensitive if set
+    bool check_name(std::string name_to_check) const {
+        std::string local_name = name_;
+        if(ignore_case_) {
+            local_name = detail::to_lower(name_);
+            name_to_check = detail::to_lower(name_to_check);
+        }
+
+        return local_name == name_to_check;
+    }
+
+    /// Get the groups available directly from this option (in order)
+    std::vector<std::string> 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;
+    }
+
+    /// This gets a vector of pointers with the original parse order
+    const std::vector<Option *> &parse_order() const { return parse_order_; }
+
+    /// This returns the missing options from the current subcommand
+    std::vector<std::string> remaining(bool recurse = false) const {
+        std::vector<std::string> miss_list;
+        for(const std::pair<detail::Classifer, std::string> &miss : missing_) {
+            miss_list.push_back(std::get<1>(miss));
+        }
+
+        // Recurse into subcommands
+        if(recurse) {
+            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;
+    }
+
+    /// This returns the number of remaining options, minus the -- seperator
+    size_t remaining_size(bool recurse = false) const {
+        auto count = static_cast<size_t>(std::count_if(
+            std::begin(missing_), std::end(missing_), [](const std::pair<detail::Classifer, std::string> &val) {
+                return val.first != detail::Classifer::POSITIONAL_MARK;
+            }));
+        if(recurse) {
+            for(const App_p &sub : subcommands_) {
+                count += sub->remaining_size(recurse);
+            }
+        }
+        return count;
+    }
+
+    ///@}
+
+  protected:
+    /// Check the options to make sure there are no conflicts.
+    ///
+    /// Currently checks to see if multiple positionals exist with -1 args
+    void _validate() const {
+        auto count = std::count_if(std::begin(options_), std::end(options_), [](const Option_p &opt) {
+            return opt->get_items_expected() < 0 && opt->get_positional();
+        });
+        if(count > 1)
+            throw InvalidError(name_);
+        for(const App_p &app : subcommands_)
+            app->_validate();
+    }
+
+    /// Internal function to run (App) callback, top down
+    void run_callback() {
+        pre_callback();
+        if(callback_)
+            callback_();
+        for(App *subc : get_subcommands()) {
+            subc->run_callback();
+        }
+    }
+
+    /// Check to see if a subcommand is valid. Give up immediately if subcommand max has been reached.
+    bool _valid_subcommand(const std::string &current) const {
+        // Don't match if max has been reached - but still check parents
+        if(require_subcommand_max_ != 0 && parsed_subcommands_.size() >= require_subcommand_max_) {
+            return parent_ != nullptr && parent_->_valid_subcommand(current);
+        }
+
+        for(const App_p &com : subcommands_)
+            if(com->check_name(current) && !*com)
+                return true;
+
+        // Check parent if exists, else return false
+        return parent_ != nullptr && parent_->_valid_subcommand(current);
+    }
+
+    /// Selects a Classifier enum based on the type of the current argument
+    detail::Classifer _recognize(const std::string &current) const {
+        std::string dummy1, dummy2;
+
+        if(current == "--")
+            return detail::Classifer::POSITIONAL_MARK;
+        if(_valid_subcommand(current))
+            return detail::Classifer::SUBCOMMAND;
+        if(detail::split_long(current, dummy1, dummy2))
+            return detail::Classifer::LONG;
+        if(detail::split_short(current, dummy1, dummy2))
+            return detail::Classifer::SHORT;
+        return detail::Classifer::NONE;
+    }
+
+    /// Internal parse function
+    void _parse(std::vector<std::string> &args) {
+        parsed_ = true;
+        bool positional_only = false;
+
+        while(!args.empty()) {
+            _parse_single(args, positional_only);
+        }
+
+        for(const Option_p &opt : options_)
+            if(opt->get_short_circuit() && opt->count() > 0)
+                opt->run_callback();
+
+        // Process an INI file
+        if(config_ptr_ != nullptr) {
+            if(*config_ptr_) {
+                config_ptr_->run_callback();
+                config_required_ = true;
+            }
+            if(!config_name_.empty()) {
+                try {
+                    std::vector<ConfigItem> values = config_formatter_->from_file(config_name_);
+                    _parse_config(values);
+                } catch(const FileError &) {
+                    if(config_required_)
+                        throw;
+                }
+            }
+        }
+
+        // Get envname options if not yet passed
+        for(const Option_p &opt : options_) {
+            if(opt->count() == 0 && !opt->envname_.empty()) {
+                char *buffer = nullptr;
+                std::string ename_string;
+
+#ifdef _MSC_VER
+                // Windows version
+                size_t sz = 0;
+                if(_dupenv_s(&buffer, &sz, opt->envname_.c_str()) == 0 && buffer != nullptr) {
+                    ename_string = std::string(buffer);
+                    free(buffer);
+                }
+#else
+                // This also works on Windows, but gives a warning
+                buffer = std::getenv(opt->envname_.c_str());
+                if(buffer != nullptr)
+                    ename_string = std::string(buffer);
+#endif
+
+                if(!ename_string.empty()) {
+                    opt->add_result(ename_string);
+                }
+            }
+        }
+
+        // Process callbacks
+        for(const Option_p &opt : options_) {
+            if(opt->count() > 0 && !opt->get_callback_run()) {
+                opt->run_callback();
+            }
+        }
+
+        // Verify required options
+        for(const Option_p &opt : options_) {
+            // Required or partially filled
+            if(opt->get_required() || opt->count() != 0) {
+                // Make sure enough -N arguments parsed (+N is already handled in parsing function)
+                if(opt->get_items_expected() < 0 && opt->count() < static_cast<size_t>(-opt->get_items_expected()))
+                    throw ArgumentMismatch::AtLeast(opt->get_name(), -opt->get_items_expected());
+
+                // Required but empty
+                if(opt->get_required() && opt->count() == 0)
+                    throw RequiredError(opt->get_name());
+            }
+            // Requires
+            for(const Option *opt_req : opt->requires_)
+                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());
+        }
+
+        auto selected_subcommands = get_subcommands();
+        if(require_subcommand_min_ > selected_subcommands.size())
+            throw RequiredError::Subcommand(require_subcommand_min_);
+
+        // Convert missing (pairs) to extras (string only)
+        if(!(allow_extras_ || prefix_command_)) {
+            size_t num_left_over = remaining_size();
+            if(num_left_over > 0) {
+                args = remaining(false);
+                throw ExtrasError(args);
+            }
+        }
+
+        if(parent_ == nullptr) {
+            args = remaining(false);
+        }
+    }
+
+    /// 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(std::vector<ConfigItem> &args) {
+        for(ConfigItem item : args) {
+            if(!_parse_single_config(item) && !allow_config_extras_)
+                throw ConfigError::Extras(item.fullname());
+        }
+    }
+
+    /// Fill in a single config option
+    bool _parse_single_config(const ConfigItem &item, size_t level = 0) {
+        if(level < item.parents.size()) {
+            App *subcom;
+            try {
+                std::cout << item.parents.at(level) << std::endl;
+                subcom = get_subcommand(item.parents.at(level));
+            } catch(const OptionNotFound &) {
+                return false;
+            }
+            return subcom->_parse_single_config(item, level + 1);
+        }
+
+        Option *op;
+        try {
+            op = get_option("--" + item.name);
+        } catch(const OptionNotFound &) {
+            // If the option was not present
+            if(get_allow_config_extras())
+                // Should we worry about classifying the extras properly?
+                missing_.emplace_back(detail::Classifer::NONE, item.fullname());
+            return false;
+        }
+
+        if(!op->get_configurable())
+            throw ConfigError::NotConfigurable(item.fullname());
+
+        if(op->empty()) {
+            // Flag parsing
+            if(op->get_type_size() == 0) {
+                op->set_results(config_formatter_->to_flag(item));
+            } else {
+                op->set_results(item.inputs);
+                op->run_callback();
+            }
+        }
+
+        return true;
+    }
+
+    /// Parse "one" argument (some may eat more than one), delegate to parent if fails, add to missing if missing from
+    /// master
+    void _parse_single(std::vector<std::string> &args, bool &positional_only) {
+
+        detail::Classifer classifer = positional_only ? detail::Classifer::NONE : _recognize(args.back());
+        switch(classifer) {
+        case detail::Classifer::POSITIONAL_MARK:
+            missing_.emplace_back(classifer, args.back());
+            args.pop_back();
+            positional_only = true;
+            break;
+        case detail::Classifer::SUBCOMMAND:
+            _parse_subcommand(args);
+            break;
+        case detail::Classifer::LONG:
+            // If already parsed a subcommand, don't accept options_
+            _parse_arg(args, true);
+            break;
+        case detail::Classifer::SHORT:
+            // If already parsed a subcommand, don't accept options_
+            _parse_arg(args, false);
+            break;
+        case detail::Classifer::NONE:
+            // Probably a positional or something for a parent (sub)command
+            _parse_positional(args);
+        }
+    }
+
+    /// Count the required remaining positional arguments
+    size_t _count_remaining_positionals(bool required = false) const {
+        size_t retval = 0;
+        for(const Option_p &opt : options_)
+            if(opt->get_positional() && (!required || opt->get_required()) && opt->get_items_expected() > 0 &&
+               static_cast<int>(opt->count()) < opt->get_items_expected())
+                retval = static_cast<size_t>(opt->get_items_expected()) - opt->count();
+
+        return retval;
+    }
+
+    /// Parse a positional, go up the tree to check
+    void _parse_positional(std::vector<std::string> &args) {
+
+        std::string positional = args.back();
+        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() || opt->get_items_expected() < 0)) {
+
+                opt->add_result(positional);
+                parse_order_.push_back(opt.get());
+                args.pop_back();
+                return;
+            }
+        }
+
+        if(parent_ != nullptr && fallthrough_)
+            return parent_->_parse_positional(args);
+        else {
+            args.pop_back();
+            missing_.emplace_back(detail::Classifer::NONE, positional);
+
+            if(prefix_command_) {
+                while(!args.empty()) {
+                    missing_.emplace_back(detail::Classifer::NONE, args.back());
+                    args.pop_back();
+                }
+            }
+        }
+    }
+
+    /// Parse a subcommand, modify args and continue
+    ///
+    /// Unlike the others, this one will always allow fallthrough
+    void _parse_subcommand(std::vector<std::string> &args) {
+        if(_count_remaining_positionals(/* required */ true) > 0)
+            return _parse_positional(args);
+        for(const App_p &com : subcommands_) {
+            if(com->check_name(args.back())) {
+                args.pop_back();
+                if(std::find(std::begin(parsed_subcommands_), std::end(parsed_subcommands_), com.get()) ==
+                   std::end(parsed_subcommands_))
+                    parsed_subcommands_.push_back(com.get());
+                com->_parse(args);
+                return;
+            }
+        }
+        if(parent_ != nullptr)
+            return parent_->_parse_subcommand(args);
+        else
+            throw HorribleError("Subcommand " + args.back() + " missing");
+    }
+
+    /// Parse a short (false) or long (true) argument, must be at the top of the list
+    void _parse_arg(std::vector<std::string> &args, bool second_dash) {
+
+        detail::Classifer current_type = second_dash ? detail::Classifer::LONG : detail::Classifer::SHORT;
+
+        std::string current = args.back();
+
+        std::string name;
+        std::string value;
+        std::string rest;
+
+        if(second_dash) {
+            if(!detail::split_long(current, name, value))
+                throw HorribleError("Long parsed but missing (you should not see this):" + args.back());
+        } else {
+            if(!detail::split_short(current, name, rest))
+                throw HorribleError("Short parsed but missing! You should not see this");
+        }
+
+        auto op_ptr = std::find_if(std::begin(options_), std::end(options_), [name, second_dash](const Option_p &opt) {
+            return second_dash ? opt->check_lname(name) : opt->check_sname(name);
+        });
+
+        // Option not found
+        if(op_ptr == std::end(options_)) {
+            // If a subcommand, try the master command
+            if(parent_ != nullptr && fallthrough_)
+                return parent_->_parse_arg(args, second_dash);
+            // Otherwise, add to missing
+            else {
+                args.pop_back();
+                missing_.emplace_back(current_type, current);
+                return;
+            }
+        }
+
+        args.pop_back();
+
+        // Get a reference to the pointer to make syntax bearable
+        Option_p &op = *op_ptr;
+
+        int num = op->get_items_expected();
+
+        // Make sure we always eat the minimum for unlimited vectors
+        int collected = 0;
+
+        // --this=value
+        if(!value.empty()) {
+            // If exact number expected
+            if(num > 0)
+                num--;
+            op->add_result(value);
+            parse_order_.push_back(op.get());
+            collected += 1;
+        } else if(num == 0) {
+            op->add_result("");
+            parse_order_.push_back(op.get());
+            // -Trest
+        } else if(!rest.empty()) {
+            if(num > 0)
+                num--;
+            op->add_result(rest);
+            parse_order_.push_back(op.get());
+            rest = "";
+            collected += 1;
+        }
+
+        // Unlimited vector parser
+        if(num < 0) {
+            while(!args.empty() && _recognize(args.back()) == detail::Classifer::NONE) {
+                if(collected >= -num) {
+                    // We could break here for allow extras, but we don't
+
+                    // If any positionals remain, don't keep eating
+                    if(_count_remaining_positionals() > 0)
+                        break;
+                }
+                op->add_result(args.back());
+                parse_order_.push_back(op.get());
+                args.pop_back();
+                collected++;
+            }
+
+            // Allow -- to end an unlimited list and "eat" it
+            if(!args.empty() && _recognize(args.back()) == detail::Classifer::POSITIONAL_MARK)
+                args.pop_back();
+
+        } else {
+            while(num > 0 && !args.empty()) {
+                num--;
+                std::string current_ = args.back();
+                args.pop_back();
+                op->add_result(current_);
+                parse_order_.push_back(op.get());
+            }
+
+            if(num > 0) {
+                throw ArgumentMismatch::TypedAtLeast(op->get_name(), num, op->get_type_name());
+            }
+        }
+
+        if(!rest.empty()) {
+            rest = "-" + rest;
+            args.push_back(rest);
+        }
+    }
+};
+
+namespace FailureMessage {
+
+/// Printout a clean, simple message on error (the default in CLI11 1.5+)
+inline std::string simple(const App *app, const Error &e) {
+    std::string header = std::string(e.what()) + "\n";
+    if(app->get_help_ptr() != nullptr)
+        header += "Run with " + app->get_help_ptr()->get_name() + " for more information.\n";
+    return header;
+}
+
+/// Printout the full help string on error (if this fn is set, the old default for 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 {
+/// This class is simply to allow tests access to App's protected functions
+struct AppFriend {
+
+    /// 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)...);
+    }
+};
+} // namespace detail
+
+} // namespace CLI
+
+// From CLI/Config.hpp:
+
+namespace CLI {
+
+inline std::string
+ConfigINI::to_config(const App *app, bool default_also, bool write_description, std::string prefix) const {
+    std::stringstream out;
+    for(const Option *opt : app->get_options({})) {
+
+        // Only process option with a long-name and configurable
+        if(!opt->get_lnames().empty() && opt->get_configurable()) {
+            std::string name = prefix + opt->get_lnames()[0];
+            std::string value;
+
+            // Non-flags
+            if(opt->get_type_size() != 0) {
+
+                // If the option was found on command line
+                if(opt->count() > 0)
+                    value = detail::ini_join(opt->results());
+
+                // If the option has a default and is requested by optional argument
+                else if(default_also && !opt->get_defaultval().empty())
+                    value = opt->get_defaultval();
+                // Flag, one passed
+            } else if(opt->count() == 1) {
+                value = "true";
+
+                // Flag, multiple passed
+            } else if(opt->count() > 1) {
+                value = std::to_string(opt->count());
+
+                // Flag, not present
+            } else if(opt->count() == 0 && default_also) {
+                value = "false";
+            }
+
+            if(!value.empty()) {
+                if(write_description && opt->has_description()) {
+                    if(static_cast<int>(out.tellp()) != 0) {
+                        out << std::endl;
+                    }
+                    out << "; " << detail::fix_newlines("; ", opt->get_description()) << std::endl;
+                }
+                out << name << "=" << value << std::endl;
+            }
+        }
+    }
+
+    for(const App *subcom : app->get_subcommands({}))
+        out << to_config(subcom, default_also, write_description, prefix + subcom->get_name() + ".");
+
+    return out.str();
+}
+
+} // namespace CLI
+
+// From CLI/Formatter.hpp:
+
+namespace CLI {
+
+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();
+}
+
+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 std::string();
+    else
+        return make_group(get_label("Positionals"), true, opts);
+}
+
+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);
+
+            if(group != groups.back())
+                out << "\n";
+        }
+    }
+
+    return out.str();
+}
+
+inline std::string Formatter::make_description(const App *app) const {
+    std::string desc = app->get_description();
+
+    if(!desc.empty())
+        return desc + "\n";
+    else
+        return "";
+}
+
+inline std::string Formatter::make_usage(const App *app, std::string name) const {
+    std::stringstream out;
+
+    out << get_label("Usage") << ":" << (name.empty() ? "" : " ") << 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({}).empty()) {
+        out << " " << (app->get_require_subcommand_min() == 0 ? "[" : "")
+            << get_label(app->get_require_subcommand_max() < 2 || app->get_require_subcommand_min() > 1 ? "SUBCOMMAND"
+                                                                                                        : "SUBCOMMANDS")
+            << (app->get_require_subcommand_min() == 0 ? "]" : "");
+    }
+
+    out << std::endl;
+
+    return out.str();
+}
+
+inline std::string Formatter::make_footer(const App *app) const {
+    std::string footer = app->get_footer();
+    if(!footer.empty())
+        return footer + "\n";
+    else
+        return "";
+}
+
+inline std::string Formatter::make_help(const App *app, std::string name, AppFormatMode mode) const {
+
+    // This immediatly 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);
+
+    std::stringstream out;
+
+    out << make_description(app);
+    out << make_usage(app, name);
+    out << make_positionals(app);
+    out << make_groups(app, mode);
+    out << make_subcommands(app, mode);
+    out << make_footer(app);
+
+    return out.str();
+}
+
+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) {
+        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 *app) { return detail::to_lower(app->get_group()) == detail::to_lower(group); });
+        for(const App *new_com : subcommands_group) {
+            if(mode != AppFormatMode::All) {
+                out << make_subcommand(new_com);
+            } else {
+                out << new_com->help(new_com->get_name(), AppFormatMode::Sub);
+                if(new_com != subcommands_group.back())
+                    out << "\n";
+            }
+        }
+    }
+
+    return out.str();
+}
+
+inline std::string Formatter::make_subcommand(const App *sub) const {
+    std::stringstream out;
+    detail::format_help(out, sub->get_name(), sub->get_description(), column_width_);
+    return out.str();
+}
+
+inline std::string Formatter::make_expanded(const App *sub) const {
+    std::stringstream out;
+    if(sub->get_description().empty())
+        out << sub->get_name();
+    else
+        out << sub->get_name() << " -> " << sub->get_description();
+    out << make_groups(sub, AppFormatMode::Sub);
+    return out.str();
+}
+
+inline std::string Formatter::make_option_name(const Option *opt, bool is_positional) const {
+    if(is_positional)
+        return opt->get_name(true, false);
+    else
+        return opt->get_name(false, true);
+}
+
+inline std::string Formatter::make_option_opts(const Option *opt) const {
+    std::stringstream out;
+
+    if(opt->get_type_size() != 0) {
+        if(!opt->get_type_name().empty())
+            out << " " << get_label(opt->get_type_name());
+        if(!opt->get_defaultval().empty())
+            out << "=" << opt->get_defaultval();
+        if(opt->get_expected() > 1)
+            out << " x " << opt->get_expected();
+        if(opt->get_expected() == -1)
+            out << " ...";
+        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();
+}
+
+inline std::string Formatter::make_option_desc(const Option *opt) const { return opt->get_description(); }
+
+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() > 1)
+        out << "(" << std::to_string(opt->get_expected()) << "x)";
+    else if(opt->get_expected() < 0)
+        out << "...";
+
+    return opt->get_required() ? out.str() : "[" + out.str() + "]";
+}
+
+} // namespace CLI
+
diff --git a/homework/81568/BF_Interpreter/Makefile b/homework/81568/BF_Interpreter/Makefile
new file mode 100644
index 0000000..b430742
--- /dev/null
+++ b/homework/81568/BF_Interpreter/Makefile
@@ -0,0 +1,2 @@
+bfi: main.cpp bf_interpreter.cpp
+	g++ -o bfi main.cpp bf_interpreter.cpp
diff --git a/homework/81568/BF_Interpreter/README.md b/homework/81568/BF_Interpreter/README.md
new file mode 100644
index 0000000..b8cde8b
--- /dev/null
+++ b/homework/81568/BF_Interpreter/README.md
@@ -0,0 +1,40 @@
+# Brainfuck-Interpreter
+Simple Brainfuck interpreter written for IPL course homework from FMI, SU, 2018.
+
+Uses default memory size of 30000 cells but if you define `#MEMSIZE` with your compiler to something else you can get different size.
+
+When either > or < instructions overflow the cell pointer, the latter just wraps
+around.
+
+# Installation
+BFI uses _make_ for make for simplicity.
+
+To install simply run:
+```
+make
+```
+
+# Usage
+```
+Usage: bfi [OPTIONS]
+
+Options:
+  -h,--help                   Print this help message and exit
+  -f,--file FILE Excludes: --code
+                              Brainfuck source file
+  -c,--code TEXT Excludes: --file
+                              Brainfuck source code
+  -o,--output TEXT            File to write the Brainfuck output to. Optional.
+  -i,--input FILE             File to take the Brainfuck input from. Optional.
+```
+
+# Future
+BFI is planned to be made child-friendly by introducing new instructions like:
+
+* ! - make the current cell value equal to 0.
+* ^ - go to cell No. (current cell No. + current cell value).
+* & - go to cell No. (current cell No. - current cell value).
+* \# - if statement that depends on next value (for comparison) and previous (to use like ^)
+* $ - same as above, but go back, instead of forward.
+
+To be completely child-friendly change the name of the language to Brainmeddler.
diff --git a/homework/81568/BF_Interpreter/bf_interpreter.cpp b/homework/81568/BF_Interpreter/bf_interpreter.cpp
new file mode 100644
index 0000000..28d4c18
--- /dev/null
+++ b/homework/81568/BF_Interpreter/bf_interpreter.cpp
@@ -0,0 +1,114 @@
+#include "bf_interpreter.h"
+
+#include <cmath>
+#include <cstring>
+#include <iostream>
+#include <stack>
+
+#ifndef MEMSIZE
+#define MEMSIZE 30000
+#endif
+
+BFInterpreter::BFInterpreter(const char *program, std::istream &input, std::ostream &output) :
+  memory_blocks(nullptr), p(nullptr),
+  program(nullptr), input(input), output(output),
+  memory_size(MEMSIZE) {
+  
+  this->program = new char[strlen(program) + 1];
+  strncpy(this->program, program, strlen(program) + 1);
+  pp = this->program;
+
+  memory_blocks = new uchar[memory_size];
+  for (int i = 0; i < memory_size; ++i) {
+    memory_blocks[i] = 0;
+  }
+  p = memory_blocks;
+}
+
+BFInterpreter::~BFInterpreter() {
+  delete [] memory_blocks;
+  delete [] program;
+}
+
+void BFInterpreter::addMemory() {
+  uchar *new_memory = new uchar[memory_size + ((size_t) log2(memory_size))];
+  for (int i = 0; i < memory_size; ++i) {
+    new_memory[i] = memory_blocks[i];
+  }
+  delete [] memory_blocks;
+  memory_blocks = new_memory;
+  memory_size += log2(memory_size);
+}
+
+void BFInterpreter::compile() {
+  while (*pp) {
+    switch (*pp) {
+    case '[':
+      ++pp;
+      loop();
+      break;
+    case ']': // that will only happen if code is wrong
+      printf("Syntax error!\n");
+      return;
+    default:
+      proccessNonLoopCmd(*pp);
+    }
+    ++pp;
+  }
+  output.put('\n');
+}
+
+void BFInterpreter::loop() {
+  std::stack<char*> loops;
+  loops.push(pp);
+  
+  char *body = loops.top();
+  while (!loops.empty()) {
+    while (*body != ']' && *body != '[') {
+      proccessNonLoopCmd(*body);
+      ++body;
+    }
+    if (*body == ']') {
+      if (!*p) { /* End of a loop */
+        loops.pop();
+        ++body;
+      } else { /* Loop has not ended. Return to the beginning of the current loop */
+        body = loops.top();
+      }
+    } else { /* Start of a new loop */
+      loops.push(body + 1);
+      ++body;
+    }
+  }
+  pp = --body;
+  return;
+}
+
+void BFInterpreter::proccessNonLoopCmd(char c) {
+  switch (c) {
+  case '+':
+    ++*p;
+    break;
+  case '-':
+    --*p;
+    break;
+  case '.':
+    output.put(*p);
+    break;
+  case ',':
+    *p = input.get();
+    break;
+  case '<':
+    if (p == memory_blocks)
+      p = memory_blocks + (memory_size - 1);
+    else 
+      --p;
+    break;
+  case '>':
+    if (p == memory_blocks + (memory_size - 1))
+      p = memory_blocks;
+    else
+      ++p;
+    break;
+  }
+}
diff --git a/homework/81568/BF_Interpreter/bf_interpreter.h b/homework/81568/BF_Interpreter/bf_interpreter.h
new file mode 100644
index 0000000..9e355ff
--- /dev/null
+++ b/homework/81568/BF_Interpreter/bf_interpreter.h
@@ -0,0 +1,33 @@
+#ifndef BRAINFUCK_INTERPRETER_H
+#define BRAINFUCK_INTERPRETER_H
+
+#include <cstddef>
+#include <iostream>
+
+
+class BFInterpreter {
+public:
+  using uchar = unsigned char;
+  
+  BFInterpreter(const char *program, std::istream &input = std::cin, std::ostream &output = std::cout);
+  ~BFInterpreter();
+
+  void compile();
+
+private:
+  void addMemory();
+  void loop();
+  void proccessNonLoopCmd(char c);
+  
+private:
+  std::istream &input;
+  std::ostream &output;
+  size_t memory_size;
+  
+  uchar *memory_blocks;
+  uchar *p;
+  char *program;
+  char *pp;
+};
+
+#endif /* BRAINFUCK_INTERPRETER_H */
diff --git a/homework/81568/BF_Interpreter/main.cpp b/homework/81568/BF_Interpreter/main.cpp
new file mode 100644
index 0000000..ccde7a5
--- /dev/null
+++ b/homework/81568/BF_Interpreter/main.cpp
@@ -0,0 +1,68 @@
+#include "bf_interpreter.h"
+#include "CLI11.hpp"
+
+#include <fstream>
+#include <iostream>
+#include <iterator>
+#include <sstream>
+#include <string>
+
+#define USAGE_MSG \
+  "Usage %s [-f <code file> | -c <code>] (-i <input file>) (-o <output file>)\n" \
+  "If no input/output file is provided standart input/output is used instead.\n"
+
+
+// TODO: implement proper CLI parsing
+// TODO: https://github.com/CLIUtils/CLI11
+int main(int argc, char **argv) {
+  CLI::App app {"Simple Brainfuck interpreter written for "
+                "IPL course homework from FMI, SU, 2018." };
+
+  std::string srcFile;
+  CLI::Option *srcFileOpt = app.add_option("-f,--file", srcFile, "Brainfuck source file");
+
+  srcFileOpt->check(CLI::ExistingFile);
+  
+  std::string srcCode;
+  CLI::Option *srcCodeOpt = app.add_option("-c,--code", srcCode, "Brainfuck source code");
+
+  srcFileOpt->excludes(srcCodeOpt);
+  srcCodeOpt->excludes(srcFileOpt);
+
+  std::string output;
+  CLI::Option *outputOpt = app.add_option("-o,--output", output, "File to write the Brainfuck output to. Optional.");
+
+  std::string input;
+  CLI::Option *inputOpt = app.add_option("-i,--input", input, "File to take the Brainfuck input from. Optional.");
+
+  inputOpt->check(CLI::ExistingFile);
+
+  CLI11_PARSE(app, argc, argv);
+
+  std::string source;
+  if (*srcFileOpt) {
+    std::ifstream file {srcFile};
+    if (file.is_open()) {
+      source.assign((std::istreambuf_iterator<char>(file)),
+                    std::istreambuf_iterator<char>());
+    }
+  } else {
+    source = srcCode;
+  }
+
+  std::ifstream inputFile;
+  if (*inputOpt)
+    inputFile.open(input);
+  
+  std::ofstream outputFile;
+  if (*outputOpt)
+    outputFile.open(output);  
+  
+  std::istream &is = *inputOpt ? inputFile : std::cin;
+  std::ostream &os = *outputOpt ? outputFile : std::cout;
+  
+  BFInterpreter bfi{source.c_str(), is, os};
+  bfi.compile();
+
+  return 0;
+}