text: /*
  
  Copyright (c) 2014, 2015, 2016, 2017 Jarryd Beck
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  
  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
  
  */
  
  #ifndef CXXOPTS_HPP_INCLUDED
  #define CXXOPTS_HPP_INCLUDED
  
  #include <cctype>
  #include <cstring>
  #include <exception>
  #include <iostream>
  #include <limits>
  #include <list>
  #include <map>
  #include <memory>
  #include <sstream>
  #include <string>
  #include <unordered_map>
  #include <unordered_set>
  #include <utility>
  #include <vector>
  #include <algorithm>
  
  #if defined(__GNUC__) && !defined(__clang__)
  #  if (__GNUC__ * 10 + __GNUC_MINOR__) < 49
  #    define CXXOPTS_NO_REGEX true
  #  endif
  #endif
  
  #ifndef CXXOPTS_NO_REGEX
  #  include <regex>
  #endif  // CXXOPTS_NO_REGEX
  
  // Nonstandard before C++17, which is coincidentally what we also need for <optional>
  #ifdef __has_include
  #  if __has_include(<optional>)
  #    include <optional>
  #    ifdef __cpp_lib_optional
  #      define CXXOPTS_HAS_OPTIONAL
  #    endif
  #  endif
  #endif
  
  #if __cplusplus >= 201603L
  #define CXXOPTS_NODISCARD [[nodiscard]]
  #else
  #define CXXOPTS_NODISCARD
  #endif
  
  #ifndef CXXOPTS_VECTOR_DELIMITER
  #define CXXOPTS_VECTOR_DELIMITER ','
  #endif
  
  #define CXXOPTS__VERSION_MAJOR 3
  #define CXXOPTS__VERSION_MINOR 0
  #define CXXOPTS__VERSION_PATCH 0
  
  #if (__GNUC__ < 10 || (__GNUC__ == 10 && __GNUC_MINOR__ < 1)) && __GNUC__ >= 6
    #define CXXOPTS_NULL_DEREF_IGNORE
  #endif
  
  namespace cxxopts
  {
    static constexpr struct {
      uint8_t major, minor, patch;
    } version = {
      CXXOPTS__VERSION_MAJOR,
      CXXOPTS__VERSION_MINOR,
      CXXOPTS__VERSION_PATCH
    };
  } // namespace cxxopts
  
  //when we ask cxxopts to use Unicode, help strings are processed using ICU,
  //which results in the correct lengths being computed for strings when they
  //are formatted for the help output
  //it is necessary to make sure that <unicode/unistr.h> can be found by the
  //compiler, and that icu-uc is linked in to the binary.
  
  #ifdef CXXOPTS_USE_UNICODE
  #include <unicode/unistr.h>
  
  namespace cxxopts
  {
    using String = icu::UnicodeString;
  
    inline
    String
    toLocalString(std::string s)
    {
      return icu::UnicodeString::fromUTF8(std::move(s));
    }
  
  #if defined(__GNUC__)
  // GNU GCC with -Weffc++ will issue a warning regarding the upcoming class, we want to silence it:
  // warning: base class 'class std::enable_shared_from_this<cxxopts::Value>' has accessible non-virtual destructor
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
  #pragma GCC diagnostic ignored "-Weffc++"
  // This will be ignored under other compilers like LLVM clang.
  #endif
    class UnicodeStringIterator : public
      std::iterator<std::forward_iterator_tag, int32_t>
    {
      public:
  
      UnicodeStringIterator(const icu::UnicodeString* string, int32_t pos)
      : s(string)
      , i(pos)
      {
      }
  
      value_type
      operator*() const
      {
        return s->char32At(i);
      }
  
      bool
      operator==(const UnicodeStringIterator& rhs) const
      {
        return s == rhs.s && i == rhs.i;
      }
  
      bool
      operator!=(const UnicodeStringIterator& rhs) const
      {
        return !(*this == rhs);
      }
  
      UnicodeStringIterator&
      operator++()
      {
        ++i;
        return *this;
      }
  
      UnicodeStringIterator
      operator+(int32_t v)
      {
        return UnicodeStringIterator(s, i + v);
      }
  
      private:
      const icu::UnicodeString* s;
      int32_t i;
    };
  #if defined(__GNUC__)
  #pragma GCC diagnostic pop
  #endif
  
    inline
    String&
    stringAppend(String&s, String a)
    {
      return s.append(std::move(a));
    }
  
    inline
    String&
    stringAppend(String& s, size_t n, UChar32 c)
    {
      for (size_t i = 0; i != n; ++i)
      {
        s.append(c);
      }
  
      return s;
    }
  
    template <typename Iterator>
    String&
    stringAppend(String& s, Iterator begin, Iterator end)
    {
      while (begin != end)
      {
        s.append(*begin);
        ++begin;
      }
  
      return s;
    }
  
    inline
    size_t
    stringLength(const String& s)
    {
      return s.length();
    }
  
    inline
    std::string
    toUTF8String(const String& s)
    {
      std::string result;
      s.toUTF8String(result);
  
      return result;
    }
  
    inline
    bool
    empty(const String& s)
    {
      return s.isEmpty();
    }
  }
  
  namespace std
  {
    inline
    cxxopts::UnicodeStringIterator
    begin(const icu::UnicodeString& s)
    {
      return cxxopts::UnicodeStringIterator(&s, 0);
    }
  
    inline
    cxxopts::UnicodeStringIterator
    end(const icu::UnicodeString& s)
    {
      return cxxopts::UnicodeStringIterator(&s, s.length());
    }
  }
  
  //ifdef CXXOPTS_USE_UNICODE
  #else
  
  namespace cxxopts
  {
    using String = std::string;
  
    template <typename T>
    T
    toLocalString(T&& t)
    {
      return std::forward<T>(t);
    }
  
    inline
    size_t
    stringLength(const String& s)
    {
      return s.length();
    }
  
    inline
    String&
    stringAppend(String&s, const String& a)
    {
      return s.append(a);
    }
  
    inline
    String&
    stringAppend(String& s, size_t n, char c)
    {
      return s.append(n, c);
    }
  
    template <typename Iterator>
    String&
    stringAppend(String& s, Iterator begin, Iterator end)
    {
      return s.append(begin, end);
    }
  
    template <typename T>
    std::string
    toUTF8String(T&& t)
    {
      return std::forward<T>(t);
    }
  
    inline
    bool
    empty(const std::string& s)
    {
      return s.empty();
    }
  } // namespace cxxopts
  
  //ifdef CXXOPTS_USE_UNICODE
  #endif
  
  namespace cxxopts
  {
    namespace
    {
  #ifdef _WIN32
      const std::string LQUOTE("\'");
      const std::string RQUOTE("\'");
  #else
      const std::string LQUOTE("‘");
      const std::string RQUOTE("’");
  #endif
    } // namespace
  
  #if defined(__GNUC__)
  // GNU GCC with -Weffc++ will issue a warning regarding the upcoming class, we want to silence it:
  // warning: base class 'class std::enable_shared_from_this<cxxopts::Value>' has accessible non-virtual destructor
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
  #pragma GCC diagnostic ignored "-Weffc++"
  // This will be ignored under other compilers like LLVM clang.
  #endif
    class Value : public std::enable_shared_from_this<Value>
    {
      public:
  
      virtual ~Value() = default;
  
      virtual
      std::shared_ptr<Value>
      clone() const = 0;
  
      virtual void
      parse(const std::string& text) const = 0;
  
      virtual void
      parse() const = 0;
  
      virtual bool
      has_default() const = 0;
  
      virtual bool
      is_container() const = 0;
  
      virtual bool
      has_implicit() const = 0;
  
      virtual std::string
      get_default_value() const = 0;
  
      virtual std::string
      get_implicit_value() const = 0;
  
      virtual std::shared_ptr<Value>
      default_value(const std::string& value) = 0;
  
      virtual std::shared_ptr<Value>
      implicit_value(const std::string& value) = 0;
  
      virtual std::shared_ptr<Value>
      no_implicit_value() = 0;
  
      virtual bool
      is_boolean() const = 0;
    };
  #if defined(__GNUC__)
  #pragma GCC diagnostic pop
  #endif
    class OptionException : public std::exception
    {
      public:
      explicit OptionException(std::string  message)
      : m_message(std::move(message))
      {
      }
  
      CXXOPTS_NODISCARD
      const char*
      what() const noexcept override
      {
        return m_message.c_str();
      }
  
      private:
      std::string m_message;
    };
  
    class OptionSpecException : public OptionException
    {
      public:
  
      explicit OptionSpecException(const std::string& message)
      : OptionException(message)
      {
      }
    };
  
    class OptionParseException : public OptionException
    {
      public:
      explicit OptionParseException(const std::string& message)
      : OptionException(message)
      {
      }
    };
  
    class option_exists_error : public OptionSpecException
    {
      public:
      explicit option_exists_error(const std::string& option)
      : OptionSpecException("Option " + LQUOTE + option + RQUOTE + " already exists")
      {
      }
    };
  
    class invalid_option_format_error : public OptionSpecException
    {
      public:
      explicit invalid_option_format_error(const std::string& format)
      : OptionSpecException("Invalid option format " + LQUOTE + format + RQUOTE)
      {
      }
    };
  
    class option_syntax_exception : public OptionParseException {
      public:
      explicit option_syntax_exception(const std::string& text)
      : OptionParseException("Argument " + LQUOTE + text + RQUOTE +
          " starts with a - but has incorrect syntax")
      {
      }
    };
  
    class option_not_exists_exception : public OptionParseException
    {
      public:
      explicit option_not_exists_exception(const std::string& option)
      : OptionParseException("Option " + LQUOTE + option + RQUOTE + " does not exist")
      {
      }
    };
  
    class missing_argument_exception : public OptionParseException
    {
      public:
      explicit missing_argument_exception(const std::string& option)
      : OptionParseException(
          "Option " + LQUOTE + option + RQUOTE + " is missing an argument"
        )
      {
      }
    };
  
    class option_requires_argument_exception : public OptionParseException
    {
      public:
      explicit option_requires_argument_exception(const std::string& option)
      : OptionParseException(
          "Option " + LQUOTE + option + RQUOTE + " requires an argument"
        )
      {
      }
    };
  
    class option_not_has_argument_exception : public OptionParseException
    {
      public:
      option_not_has_argument_exception
      (
        const std::string& option,
        const std::string& arg
      )
      : OptionParseException(
          "Option " + LQUOTE + option + RQUOTE +
          " does not take an argument, but argument " +
          LQUOTE + arg + RQUOTE + " given"
        )
      {
      }
    };
  
    class option_not_present_exception : public OptionParseException
    {
      public:
      explicit option_not_present_exception(const std::string& option)
      : OptionParseException("Option " + LQUOTE + option + RQUOTE + " not present")
      {
      }
    };
  
    class option_has_no_value_exception : public OptionException
    {
      public:
      explicit option_has_no_value_exception(const std::string& option)
      : OptionException(
          !option.empty() ?
          ("Option " + LQUOTE + option + RQUOTE + " has no value") :
          "Option has no value")
      {
      }
    };
  
    class argument_incorrect_type : public OptionParseException
    {
      public:
      explicit argument_incorrect_type
      (
        const std::string& arg
      )
      : OptionParseException(
          "Argument " + LQUOTE + arg + RQUOTE + " failed to parse"
        )
      {
      }
    };
  
    class option_required_exception : public OptionParseException
    {
      public:
      explicit option_required_exception(const std::string& option)
      : OptionParseException(
          "Option " + LQUOTE + option + RQUOTE + " is required but not present"
        )
      {
      }
    };
  
    template <typename T>
    void throw_or_mimic(const std::string& text)
    {
      static_assert(std::is_base_of<std::exception, T>::value,
                    "throw_or_mimic only works on std::exception and "
                    "deriving classes");
  
  #ifndef CXXOPTS_NO_EXCEPTIONS
      // If CXXOPTS_NO_EXCEPTIONS is not defined, just throw
      throw T{text};
  #else
      // Otherwise manually instantiate the exception, print what() to stderr,
      // and exit
      T exception{text};
      std::cerr << exception.what() << std::endl;
      std::exit(EXIT_FAILURE);
  #endif
    }
  
    namespace values
    {
      namespace parser_tool
      {
        struct IntegerDesc
        {
          std::string negative = "";
          std::string base     = "";
          std::string value    = "";
        };
        struct ArguDesc {
          std::string arg_name  = "";
          bool        grouping  = false;
          bool        set_value = false;
          std::string value     = "";
        };
  #ifdef CXXOPTS_NO_REGEX
        inline IntegerDesc SplitInteger(const std::string &text)
        {
          if (text.empty())
          {
            throw_or_mimic<argument_incorrect_type>(text);
          }
          IntegerDesc desc;
          const char *pdata = text.c_str();
          if (*pdata == '-')
          {
            pdata += 1;
            desc.negative = "-";
          }
          if (strncmp(pdata, "0x", 2) == 0)
          {
            pdata += 2;
            desc.base = "0x";
          }
          if (*pdata != '\0')
          {
            desc.value = std::string(pdata);
          }
          else
          {
            throw_or_mimic<argument_incorrect_type>(text);
          }
          return desc;
        }
  
        inline bool IsTrueText(const std::string &text)
        {
          const char *pdata = text.c_str();
          if (*pdata == 't' || *pdata == 'T')
          {
            pdata += 1;
            if (strncmp(pdata, "rue\0", 4) == 0)
            {
              return true;
            }
          }
          else if (strncmp(pdata, "1\0", 2) == 0)
          {
            return true;
          }
          return false;
        }
  
        inline bool IsFalseText(const std::string &text)
        {
          const char *pdata = text.c_str();
          if (*pdata == 'f' || *pdata == 'F')
          {
            pdata += 1;
            if (strncmp(pdata, "alse\0", 5) == 0)
            {
              return true;
            }
          }
          else if (strncmp(pdata, "0\0", 2) == 0)
          {
            return true;
          }
          return false;
        }
  
        inline std::pair<std::string, std::string> SplitSwitchDef(const std::string &text)
        {
          std::string short_sw, long_sw;
          const char *pdata = text.c_str();
          if (isalnum(*pdata) && *(pdata + 1) == ',') {
            short_sw = std::string(1, *pdata);
            pdata += 2;
          }
          while (*pdata == ' ') { pdata += 1; }
          if (isalnum(*pdata)) {
            const char *store = pdata;
            pdata += 1;
            while (isalnum(*pdata) || *pdata == '-' || *pdata == '_') {
              pdata += 1;
            }
            if (*pdata == '\0') {
              long_sw = std::string(store, pdata - store);
            } else {
              throw_or_mimic<invalid_option_format_error>(text);
            }
          }
          return std::pair<std::string, std::string>(short_sw, long_sw);
        }
  
        inline ArguDesc ParseArgument(const char *arg, bool &matched)
        {
          ArguDesc argu_desc;
          const char *pdata = arg;
          matched = false;
          if (strncmp(pdata, "--", 2) == 0)
          {
            pdata += 2;
            if (isalnum(*pdata))
            {
              argu_desc.arg_name.push_back(*pdata);
              pdata += 1;
              while (isalnum(*pdata) || *pdata == '-' || *pdata == '_')
              {
                argu_desc.arg_name.push_back(*pdata);
                pdata += 1;
              }
              if (argu_desc.arg_name.length() > 1)
              {
                if (*pdata == '=')
                {
                  argu_desc.set_value = true;
                  pdata += 1;
                  if (*pdata != '\0')
                  {
                    argu_desc.value = std::string(pdata);
                  }
                  matched = true;
                }
                else if (*pdata == '\0')
                {
                  matched = true;
                }
              }
            }
          }
          else if (strncmp(pdata, "-", 1) == 0)
          {
            pdata += 1;
            argu_desc.grouping = true;
            while (isalnum(*pdata))
            {
              argu_desc.arg_name.push_back(*pdata);
              pdata += 1;
            }
            matched = !argu_desc.arg_name.empty() && *pdata == '\0';
          }
          return argu_desc;
        }
  
  #else  // CXXOPTS_NO_REGEX
  
        namespace
        {
  
          std::basic_regex<char> integer_pattern
            ("(-)?(0x)?([0-9a-zA-Z]+)|((0x)?0)");
          std::basic_regex<char> truthy_pattern
            ("(t|T)(rue)?|1");
          std::basic_regex<char> falsy_pattern
            ("(f|F)(alse)?|0");
  
          std::basic_regex<char> option_matcher
            ("--([[:alnum:]][-_[:alnum:]]+)(=(.*))?|-([[:alnum:]]+)");
          std::basic_regex<char> option_specifier
            ("(([[:alnum:]]),)?[ ]*([[:alnum:]][-_[:alnum:]]*)?");
  
        } // namespace
  
        inline IntegerDesc SplitInteger(const std::string &text)
        {
          std::smatch match;
          std::regex_match(text, match, integer_pattern);
  
          if (match.length() == 0)
          {
            throw_or_mimic<argument_incorrect_type>(text);
          }
  
          IntegerDesc desc;
          desc.negative = match[1];
          desc.base = match[2];
          desc.value = match[3];
  
          if (match.length(4) > 0)
          {
            desc.base = match[5];
            desc.value = "0";
            return desc;
          }
  
          return desc;
        }
  
        inline bool IsTrueText(const std::string &text)
        {
          std::smatch result;
          std::regex_match(text, result, truthy_pattern);
          return !result.empty();
        }
  
        inline bool IsFalseText(const std::string &text)
        {
          std::smatch result;
          std::regex_match(text, result, falsy_pattern);
          return !result.empty();
        }
  
        inline std::pair<std::string, std::string> SplitSwitchDef(const std::string &text)
        {
          std::match_results<const char*> result;
          std::regex_match(text.c_str(), result, option_specifier);
          if (result.empty())
          {
            throw_or_mimic<invalid_option_format_error>(text);
          }
  
          const std::string& short_sw = result[2];
          const std::string& long_sw = result[3];
  
          return std::pair<std::string, std::string>(short_sw, long_sw);
        }
  
        inline ArguDesc ParseArgument(const char *arg, bool &matched)
        {
          std::match_results<const char*> result;
          std::regex_match(arg, result, option_matcher);
          matched = !result.empty();
  
          ArguDesc argu_desc;
          if (matched) {
            argu_desc.arg_name = result[1].str();
            argu_desc.set_value = result[2].length() > 0;
            argu_desc.value = result[3].str();
            if (result[4].length() > 0)
            {
              argu_desc.grouping = true;
              argu_desc.arg_name = result[4].str();
            }
          }
  
          return argu_desc;
        }
  
  #endif  // CXXOPTS_NO_REGEX
  #undef CXXOPTS_NO_REGEX
    }
  
      namespace detail
      {
        template <typename T, bool B>
        struct SignedCheck;
  
        template <typename T>
        struct SignedCheck<T, true>
        {
          template <typename U>
          void
          operator()(bool negative, U u, const std::string& text)
          {
            if (negative)
            {
              if (u > static_cast<U>((std::numeric_limits<T>::min)()))
              {
                throw_or_mimic<argument_incorrect_type>(text);
              }
            }
            else
            {
              if (u > static_cast<U>((std::numeric_limits<T>::max)()))
              {
                throw_or_mimic<argument_incorrect_type>(text);
              }
            }
          }
        };
  
        template <typename T>
        struct SignedCheck<T, false>
        {
          template <typename U>
          void
          operator()(bool, U, const std::string&) const {}
        };
  
        template <typename T, typename U>
        void
        check_signed_range(bool negative, U value, const std::string& text)
        {
          SignedCheck<T, std::numeric_limits<T>::is_signed>()(negative, value, text);
        }
      } // namespace detail
  
      template <typename R, typename T>
      void
      checked_negate(R& r, T&& t, const std::string&, std::true_type)
      {
        // if we got to here, then `t` is a positive number that fits into
        // `R`. So to avoid MSVC C4146, we first cast it to `R`.
        // See https://github.com/jarro2783/cxxopts/issues/62 for more details.
        r = static_cast<R>(-static_cast<R>(t-1)-1);
      }
  
      template <typename R, typename T>
      void
      checked_negate(R&, T&&, const std::string& text, std::false_type)
      {
        throw_or_mimic<argument_incorrect_type>(text);
      }
  
      template <typename T>
      void
      integer_parser(const std::string& text, T& value)
      {
        parser_tool::IntegerDesc int_desc = parser_tool::SplitInteger(text);
  
        using US = typename std::make_unsigned<T>::type;
        constexpr bool is_signed = std::numeric_limits<T>::is_signed;
  
        const bool          negative    = int_desc.negative.length() > 0;
        const uint8_t       base        = int_desc.base.length() > 0 ? 16 : 10;
        const std::string & value_match = int_desc.value;
  
        US result = 0;
  
        for (char ch : value_match)
        {
          US digit = 0;
  
          if (ch >= '0' && ch <= '9')
          {
            digit = static_cast<US>(ch - '0');
          }
          else if (base == 16 && ch >= 'a' && ch <= 'f')
          {
            digit = static_cast<US>(ch - 'a' + 10);
          }
          else if (base == 16 && ch >= 'A' && ch <= 'F')
          {
            digit = static_cast<US>(ch - 'A' + 10);
          }
          else
          {
            throw_or_mimic<argument_incorrect_type>(text);
          }
  
          const US next = static_cast<US>(result * base + digit);
          if (result > next)
          {
            throw_or_mimic<argument_incorrect_type>(text);
          }
  
          result = next;
        }
  
        detail::check_signed_range<T>(negative, result, text);
  
        if (negative)
        {
          checked_negate<T>(value, result, text, std::integral_constant<bool, is_signed>());
        }
        else
        {
          value = static_cast<T>(result);
        }
      }
  
      template <typename T>
      void stringstream_parser(const std::string& text, T& value)
      {
        std::stringstream in(text);
        in >> value;
        if (!in) {
          throw_or_mimic<argument_incorrect_type>(text);
        }
      }
  
      template <typename T,
               typename std::enable_if<std::is_integral<T>::value>::type* = nullptr
               >
      void parse_value(const std::string& text, T& value)
      {
          integer_parser(text, value);
      }
  
      inline
      void
      parse_value(const std::string& text, bool& value)
      {
        if (parser_tool::IsTrueText(text))
        {
          value = true;
          return;
        }
  
        if (parser_tool::IsFalseText(text))
        {
          value = false;
          return;
        }
  
        throw_or_mimic<argument_incorrect_type>(text);
      }
  
      inline
      void
      parse_value(const std::string& text, std::string& value)
      {
        value = text;
      }
  
      // The fallback parser. It uses the stringstream parser to parse all types
      // that have not been overloaded explicitly.  It has to be placed in the
      // source code before all other more specialized templates.
      template <typename T,
               typename std::enable_if<!std::is_integral<T>::value>::type* = nullptr
               >
      void
      parse_value(const std::string& text, T& value) {
        stringstream_parser(text, value);
      }
  
      template <typename T>
      void
      parse_value(const std::string& text, std::vector<T>& value)
      {
        if (text.empty()) {
          T v;
          parse_value(text, v);
          value.emplace_back(std::move(v));
          return;
        }
        std::stringstream in(text);
        std::string token;
        while(!in.eof() && std::getline(in, token, CXXOPTS_VECTOR_DELIMITER)) {
          T v;
          parse_value(token, v);
          value.emplace_back(std::move(v));
        }
      }
  
  #ifdef CXXOPTS_HAS_OPTIONAL
      template <typename T>
      void
      parse_value(const std::string& text, std::optional<T>& value)
      {
        T result;
        parse_value(text, result);
        value = std::move(result);
      }
  #endif
  
      inline
      void parse_value(const std::string& text, char& c)
      {
        if (text.length() != 1)
        {
          throw_or_mimic<argument_incorrect_type>(text);
        }
  
        c = text[0];
      }
  
      template <typename T>
      struct type_is_container
      {
        static constexpr bool value = false;
      };
  
      template <typename T>
      struct type_is_container<std::vector<T>>
      {
        static constexpr bool value = true;
      };
  
      template <typename T>
      class abstract_value : public Value
      {
        using Self = abstract_value<T>;
  
        public:
        abstract_value()
        : m_result(std::make_shared<T>())
        , m_store(m_result.get())
        {
        }
  
        explicit abstract_value(T* t)
        : m_store(t)
        {
        }
  
        ~abstract_value() override = default;
  
        abstract_value& operator=(const abstract_value&) = default;
  
        abstract_value(const abstract_value& rhs)
        {
          if (rhs.m_result)
          {
            m_result = std::make_shared<T>();
            m_store = m_result.get();
          }
          else
          {
            m_store = rhs.m_store;
          }
  
          m_default = rhs.m_default;
          m_implicit = rhs.m_implicit;
          m_default_value = rhs.m_default_value;
          m_implicit_value = rhs.m_implicit_value;
        }
  
        void
        parse(const std::string& text) const override
        {
          parse_value(text, *m_store);
        }
  
        bool
        is_container() const override
        {
          return type_is_container<T>::value;
        }
  
        void
        parse() const override
        {
          parse_value(m_default_value, *m_store);
        }
  
        bool
        has_default() const override
        {
          return m_default;
        }
  
        bool
        has_implicit() const override
        {
          return m_implicit;
        }
  
        std::shared_ptr<Value>
        default_value(const std::string& value) override
        {
          m_default = true;
          m_default_value = value;
          return shared_from_this();
        }
  
        std::shared_ptr<Value>
        implicit_value(const std::string& value) override
        {
          m_implicit = true;
          m_implicit_value = value;
          return shared_from_this();
        }
  
        std::shared_ptr<Value>
        no_implicit_value() override
        {
          m_implicit = false;
          return shared_from_this();
        }
  
        std::string
        get_default_value() const override
        {
          return m_default_value;
        }
  
        std::string
        get_implicit_value() const override
        {
          return m_implicit_value;
        }
  
        bool
        is_boolean() const override
        {
          return std::is_same<T, bool>::value;
        }
  
        const T&
        get() const
        {
          if (m_store == nullptr)
          {
            return *m_result;
          }
          return *m_store;
        }
  
        protected:
        std::shared_ptr<T> m_result{};
        T* m_store{};
  
        bool m_default = false;
        bool m_implicit = false;
  
        std::string m_default_value{};
        std::string m_implicit_value{};
      };
  
      template <typename T>
      class standard_value : public abstract_value<T>
      {
        public:
        using abstract_value<T>::abstract_value;
  
        CXXOPTS_NODISCARD
        std::shared_ptr<Value>
        clone() const override
        {
          return std::make_shared<standard_value<T>>(*this);
        }
      };
  
      template <>
      class standard_value<bool> : public abstract_value<bool>
      {
        public:
        ~standard_value() override = default;
  
        standard_value()
        {
          set_default_and_implicit();
        }
  
        explicit standard_value(bool* b)
        : abstract_value(b)
        {
          set_default_and_implicit();
        }
  
        std::shared_ptr<Value>
        clone() const override
        {
          return std::make_shared<standard_value<bool>>(*this);
        }
  
        private:
  
        void
        set_default_and_implicit()
        {
          m_default = true;
          m_default_value = "false";
          m_implicit = true;
          m_implicit_value = "true";
        }
      };
    } // namespace values
  
    template <typename T>
    std::shared_ptr<Value>
    value()
    {
      return std::make_shared<values::standard_value<T>>();
    }
  
    template <typename T>
    std::shared_ptr<Value>
    value(T& t)
    {
      return std::make_shared<values::standard_value<T>>(&t);
    }
  
    class OptionAdder;
  
    class OptionDetails
    {
      public:
      OptionDetails
      (
        std::string short_,
        std::string long_,
        String desc,
        std::shared_ptr<const Value> val
      )
      : m_short(std::move(short_))
      , m_long(std::move(long_))
      , m_desc(std::move(desc))
      , m_value(std::move(val))
      , m_count(0)
      {
        m_hash = std::hash<std::string>{}(m_long + m_short);
      }
  
      OptionDetails(const OptionDetails& rhs)
      : m_desc(rhs.m_desc)
      , m_value(rhs.m_value->clone())
      , m_count(rhs.m_count)
      {
      }
  
      OptionDetails(OptionDetails&& rhs) = default;
  
      CXXOPTS_NODISCARD
      const String&
      description() const
      {
        return m_desc;
      }
  
      CXXOPTS_NODISCARD
      const Value&
      value() const {
          return *m_value;
      }
  
      CXXOPTS_NODISCARD
      std::shared_ptr<Value>
      make_storage() const
      {
        return m_value->clone();
      }
  
      CXXOPTS_NODISCARD
      const std::string&
      short_name() const
      {
        return m_short;
      }
  
      CXXOPTS_NODISCARD
      const std::string&
      long_name() const
      {
        return m_long;
      }
  
      size_t
      hash() const
      {
        return m_hash;
      }
  
      private:
      std::string m_short{};
      std::string m_long{};
      String m_desc{};
      std::shared_ptr<const Value> m_value{};
      int m_count;
  
      size_t m_hash{};
    };
  
    struct HelpOptionDetails
    {
      std::string s;
      std::string l;
      String desc;
      bool has_default;
      std::string default_value;
      bool has_implicit;
      std::string implicit_value;
      std::string arg_help;
      bool is_container;
      bool is_boolean;
    };
  
    struct HelpGroupDetails
    {
      std::string name{};
      std::string description{};
      std::vector<HelpOptionDetails> options{};
    };
  
    class OptionValue
    {
      public:
      void
      parse
      (
        const std::shared_ptr<const OptionDetails>& details,
        const std::string& text
      )
      {
        ensure_value(details);
        ++m_count;
        m_value->parse(text);
        m_long_name = &details->long_name();
      }
  
      void
      parse_default(const std::shared_ptr<const OptionDetails>& details)
      {
        ensure_value(details);
        m_default = true;
        m_long_name = &details->long_name();
        m_value->parse();
      }
  
      void
      parse_no_value(const std::shared_ptr<const OptionDetails>& details)
      {
        m_long_name = &details->long_name();
      }
  
  #if defined(CXXOPTS_NULL_DEREF_IGNORE)
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wnull-dereference"
  #endif
  
      CXXOPTS_NODISCARD
      size_t
      count() const noexcept
      {
        return m_count;
      }
  
  #if defined(CXXOPTS_NULL_DEREF_IGNORE)
  #pragma GCC diagnostic pop
  #endif
  
      // TODO: maybe default options should count towards the number of arguments
      CXXOPTS_NODISCARD
      bool
      has_default() const noexcept
      {
        return m_default;
      }
  
      template <typename T>
      const T&
      as() const
      {
        if (m_value == nullptr) {
            throw_or_mimic<option_has_no_value_exception>(
                m_long_name == nullptr ? "" : *m_long_name);
        }
  
  #ifdef CXXOPTS_NO_RTTI
        return static_cast<const values::standard_value<T>&>(*m_value).get();
  #else
        return dynamic_cast<const values::standard_value<T>&>(*m_value).get();
  #endif
      }
  
      private:
      void
      ensure_value(const std::shared_ptr<const OptionDetails>& details)
      {
        if (m_value == nullptr)
        {
          m_value = details->make_storage();
        }
      }
  
  
      const std::string* m_long_name = nullptr;
      // Holding this pointer is safe, since OptionValue's only exist in key-value pairs,
      // where the key has the string we point to.
      std::shared_ptr<Value> m_value{};
      size_t m_count = 0;
      bool m_default = false;
    };
  
    class KeyValue
    {
      public:
      KeyValue(std::string key_, std::string value_)
      : m_key(std::move(key_))
      , m_value(std::move(value_))
      {
      }
  
      CXXOPTS_NODISCARD
      const std::string&
      key() const
      {
        return m_key;
      }
  
      CXXOPTS_NODISCARD
      const std::string&
      value() const
      {
        return m_value;
      }
  
      template <typename T>
      T
      as() const
      {
        T result;
        values::parse_value(m_value, result);
        return result;
      }
  
      private:
      std::string m_key;
      std::string m_value;
    };
  
    using ParsedHashMap = std::unordered_map<size_t, OptionValue>;
    using NameHashMap = std::unordered_map<std::string, size_t>;
  
    class ParseResult
    {
      public:
      class Iterator
      {
        public:
        using iterator_category = std::forward_iterator_tag;
        using value_type = KeyValue;
        using difference_type = void;
        using pointer = const KeyValue*;
        using reference = const KeyValue&;
  
        Iterator() = default;
        Iterator(const Iterator&) = default;
  
        Iterator(const ParseResult *pr, bool end=false)
        : m_pr(pr)
        , m_iter(end? pr->m_defaults.end(): pr->m_sequential.begin())
        {
        }
  
        Iterator& operator++()
        {
          ++m_iter;
          if(m_iter == m_pr->m_sequential.end())
          {
            m_iter = m_pr->m_defaults.begin();
            return *this;
          }
          return *this;
        }
  
        Iterator operator++(int)
        {
          Iterator retval = *this;
          ++(*this);
          return retval;
        }
  
        bool operator==(const Iterator& other) const
        {
          return m_iter == other.m_iter;
        }
  
        bool operator!=(const Iterator& other) const
        {
          return !(*this == other);
        }
  
        const KeyValue& operator*()
        {
          return *m_iter;
        }
  
        const KeyValue* operator->()
        {
          return m_iter.operator->();
        }
  
        private:
        const ParseResult* m_pr;
        std::vector<KeyValue>::const_iterator m_iter;
      };
  
      ParseResult() = default;
      ParseResult(const ParseResult&) = default;
  
      ParseResult(NameHashMap&& keys, ParsedHashMap&& values, std::vector<KeyValue> sequential, 
              std::vector<KeyValue> default_opts, std::vector<std::string>&& unmatched_args)
      : m_keys(std::move(keys))
      , m_values(std::move(values))
      , m_sequential(std::move(sequential))
      , m_defaults(std::move(default_opts))
      , m_unmatched(std::move(unmatched_args))
      {
      }
  
      ParseResult& operator=(ParseResult&&) = default;
      ParseResult& operator=(const ParseResult&) = default;
  
      Iterator
      begin() const
      {
        return Iterator(this);
      }
  
      Iterator
      end() const
      {
        return Iterator(this, true);
      }
  
      size_t
      count(const std::string& o) const
      {
        auto iter = m_keys.find(o);
        if (iter == m_keys.end())
        {
          return 0;
        }
  
        auto viter = m_values.find(iter->second);
  
        if (viter == m_values.end())
        {
          return 0;
        }
  
        return viter->second.count();
      }
  
      const OptionValue&
      operator[](const std::string& option) const
      {
        auto iter = m_keys.find(option);
  
        if (iter == m_keys.end())
        {
          throw_or_mimic<option_not_present_exception>(option);
        }
  
        auto viter = m_values.find(iter->second);
  
        if (viter == m_values.end())
        {
          throw_or_mimic<option_not_present_exception>(option);
        }
  
        return viter->second;
      }
  
      const std::vector<KeyValue>&
      arguments() const
      {
        return m_sequential;
      }
  
      const std::vector<std::string>&
      unmatched() const
      {
        return m_unmatched;
      }
  
      const std::vector<KeyValue>&
      defaults() const
      {
        return m_defaults;
      }
  
      const std::string
      arguments_string() const
      {
        std::string result;
        for(const auto& kv: m_sequential)
        {
          result += kv.key() + " = " + kv.value() + "\n";
        }
        for(const auto& kv: m_defaults)
        {
          result += kv.key() + " = " + kv.value() + " " + "(default)" + "\n";
        }
        return result;
      }
  
      private:
      NameHashMap m_keys{};
      ParsedHashMap m_values{};
      std::vector<KeyValue> m_sequential{};
      std::vector<KeyValue> m_defaults{};
      std::vector<std::string> m_unmatched{};
    };
  
    struct Option
    {
      Option
      (
        std::string opts,
        std::string desc,
        std::shared_ptr<const Value>  value = ::cxxopts::value<bool>(),
        std::string arg_help = ""
      )
      : opts_(std::move(opts))
      , desc_(std::move(desc))
      , value_(std::move(value))
      , arg_help_(std::move(arg_help))
      {
      }
  
      std::string opts_;
      std::string desc_;
      std::shared_ptr<const Value> value_;
      std::string arg_help_;
    };
  
    using OptionMap = std::unordered_map<std::string, std::shared_ptr<OptionDetails>>;
    using PositionalList = std::vector<std::string>;
    using PositionalListIterator = PositionalList::const_iterator;
  
    class OptionParser
    {
      public:
      OptionParser(const OptionMap& options, const PositionalList& positional, bool allow_unrecognised)
      : m_options(options)
      , m_positional(positional)
      , m_allow_unrecognised(allow_unrecognised)
      {
      }
  
      ParseResult
      parse(int argc, const char* const* argv);
  
      bool
      consume_positional(const std::string& a, PositionalListIterator& next);
  
      void
      checked_parse_arg
      (
        int argc,
        const char* const* argv,
        int& current,
        const std::shared_ptr<OptionDetails>& value,
        const std::string& name
      );
  
      void
      add_to_option(OptionMap::const_iterator iter, const std::string& option, const std::string& arg);
  
      void
      parse_option
      (
        const std::shared_ptr<OptionDetails>& value,
        const std::string& name,
        const std::string& arg = ""
      );
  
      void
      parse_default(const std::shared_ptr<OptionDetails>& details);
  
      void
      parse_no_value(const std::shared_ptr<OptionDetails>& details);
  
      private:
  
      void finalise_aliases();
  
      const OptionMap& m_options;
      const PositionalList& m_positional;
  
      std::vector<KeyValue> m_sequential{};
      std::vector<KeyValue> m_defaults{};
      bool m_allow_unrecognised;
  
      ParsedHashMap m_parsed{};
      NameHashMap m_keys{};
    };
  
    class Options
    {
      public:
  
      explicit Options(std::string program, std::string help_string = "")
      : m_program(std::move(program))
      , m_help_string(toLocalString(std::move(help_string)))
      , m_custom_help("[OPTION...]")
      , m_positional_help("positional parameters")
      , m_show_positional(false)
      , m_allow_unrecognised(false)
      , m_width(76)
      , m_tab_expansion(false)
      , m_options(std::make_shared<OptionMap>())
      {
      }
  
      Options&
      positional_help(std::string help_text)
      {
        m_positional_help = std::move(help_text);
        return *this;
      }
  
      Options&
      custom_help(std::string help_text)
      {
        m_custom_help = std::move(help_text);
        return *this;
      }
  
      Options&
      show_positional_help()
      {
        m_show_positional = true;
        return *this;
      }
  
      Options&
      allow_unrecognised_options()
      {
        m_allow_unrecognised = true;
        return *this;
      }
  
      Options&
      set_width(size_t width)
      {
        m_width = width;
        return *this;
      }
  
      Options&
      set_tab_expansion(bool expansion=true)
      {
        m_tab_expansion = expansion;
        return *this;
      }
  
      ParseResult
      parse(int argc, const char* const* argv);
  
      OptionAdder
      add_options(std::string group = "");
  
      void
      add_options
      (
        const std::string& group,
        std::initializer_list<Option> options
      );
  
      void
      add_option
      (
        const std::string& group,
        const Option& option
      );
  
      void
      add_option
      (
        const std::string& group,
        const std::string& s,
        const std::string& l,
        std::string desc,
        const std::shared_ptr<const Value>& value,
        std::string arg_help
      );
  
      //parse positional arguments into the given option
      void
      parse_positional(std::string option);
  
      void
      parse_positional(std::vector<std::string> options);
  
      void
      parse_positional(std::initializer_list<std::string> options);
  
      template <typename Iterator>
      void
      parse_positional(Iterator begin, Iterator end) {
        parse_positional(std::vector<std::string>{begin, end});
      }
  
      std::string
      help(const std::vector<std::string>& groups = {}) const;
  
      std::vector<std::string>
      groups() const;
  
      const HelpGroupDetails&
      group_help(const std::string& group) const;
  
      private:
  
      void
      add_one_option
      (
        const std::string& option,
        const std::shared_ptr<OptionDetails>& details
      );
  
      String
      help_one_group(const std::string& group) const;
  
      void
      generate_group_help
      (
        String& result,
        const std::vector<std::string>& groups
      ) const;
  
      void
      generate_all_groups_help(String& result) const;
  
      std::string m_program{};
      String m_help_string{};
      std::string m_custom_help{};
      std::string m_positional_help{};
      bool m_show_positional;
      bool m_allow_unrecognised;
      size_t m_width;
      bool m_tab_expansion;
  
      std::shared_ptr<OptionMap> m_options;
      std::vector<std::string> m_positional{};
      std::unordered_set<std::string> m_positional_set{};
  
      //mapping from groups to help options
      std::map<std::string, HelpGroupDetails> m_help{};
  
      std::list<OptionDetails> m_option_list{};
      std::unordered_map<std::string, decltype(m_option_list)::iterator> m_option_map{};
    };
  
    class OptionAdder
    {
      public:
  
      OptionAdder(Options& options, std::string group)
      : m_options(options), m_group(std::move(group))
      {
      }
  
      OptionAdder&
      operator()
      (
        const std::string& opts,
        const std::string& desc,
        const std::shared_ptr<const Value>& value
          = ::cxxopts::value<bool>(),
        std::string arg_help = ""
      );
  
      private:
      Options& m_options;
      std::string m_group;
    };
  
    namespace
    {
      constexpr size_t OPTION_LONGEST = 30;
      constexpr size_t OPTION_DESC_GAP = 2;
  
      String
      format_option
      (
        const HelpOptionDetails& o
      )
      {
        const auto& s = o.s;
        const auto& l = o.l;
  
        String result = "  ";
  
        if (!s.empty())
        {
          result += "-" + toLocalString(s);
          if (!l.empty())
          {
            result += ",";
          }
        }
        else
        {
          result += "   ";
        }
  
        if (!l.empty())
        {
          result += " --" + toLocalString(l);
        }
  
        auto arg = !o.arg_help.empty() ? toLocalString(o.arg_help) : "arg";
  
        if (!o.is_boolean)
        {
          if (o.has_implicit)
          {
            result += " [=" + arg + "(=" + toLocalString(o.implicit_value) + ")]";
          }
          else
          {
            result += " " + arg;
          }
        }
  
        return result;
      }
  
      String
      format_description
      (
        const HelpOptionDetails& o,
        size_t start,
        size_t allowed,
        bool tab_expansion
      )
      {
        auto desc = o.desc;
  
        if (o.has_default && (!o.is_boolean || o.default_value != "false"))
        {
          if(!o.default_value.empty())
          {
            desc += toLocalString(" (default: " + o.default_value + ")");
          }
          else
          {
            desc += toLocalString(" (default: \"\")");
          }
        }
  
        String result;
  
        if (tab_expansion)
        {
          String desc2;
          auto size = size_t{ 0 };
          for (auto c = std::begin(desc); c != std::end(desc); ++c)
          {
            if (*c == '\n')
            {
              desc2 += *c;
              size = 0;
            }
            else if (*c == '\t')
            {
              auto skip = 8 - size % 8;
              stringAppend(desc2, skip, ' ');
              size += skip;
            }
            else
            {
              desc2 += *c;
              ++size;
            }
          }
          desc = desc2;
        }
  
        desc += " ";
  
        auto current = std::begin(desc);
        auto previous = current;
        auto startLine = current;
        auto lastSpace = current;
  
        auto size = size_t{};
  
        bool appendNewLine;
        bool onlyWhiteSpace = true;
  
        while (current != std::end(desc))
        {
          appendNewLine = false;
  
          if (std::isblank(*previous))
          {
            lastSpace = current;
          }
  
          if (!std::isblank(*current))
          {
            onlyWhiteSpace = false;
          }
  
          while (*current == '\n')
          {
            previous = current;
            ++current;
            appendNewLine = true;
          }
  
          if (!appendNewLine && size >= allowed)
          {
            if (lastSpace != startLine)
            {
              current = lastSpace;
              previous = current;
            }
            appendNewLine = true;
          }
  
          if (appendNewLine)
          {
            stringAppend(result, startLine, current);
            startLine = current;
            lastSpace = current;
  
            if (*previous != '\n')
            {
              stringAppend(result, "\n");
            }
  
            stringAppend(result, start, ' ');
  
            if (*previous != '\n')
            {
              stringAppend(result, lastSpace, current);
            }
  
            onlyWhiteSpace = true;
            size = 0;
          }
  
          previous = current;
          ++current;
          ++size;
        }
  
        //append whatever is left but ignore whitespace
        if (!onlyWhiteSpace)
        {
          stringAppend(result, startLine, previous);
        }
  
        return result;
      }
    } // namespace
  
  inline
  void
  Options::add_options
  (
    const std::string &group,
    std::initializer_list<Option> options
  )
  {
   OptionAdder option_adder(*this, group);
   for (const auto &option: options)
   {
     option_adder(option.opts_, option.desc_, option.value_, option.arg_help_);
   }
  }
  
  inline
  OptionAdder
  Options::add_options(std::string group)
  {
    return OptionAdder(*this, std::move(group));
  }
  
  inline
  OptionAdder&
  OptionAdder::operator()
  (
    const std::string& opts,
    const std::string& desc,
    const std::shared_ptr<const Value>& value,
    std::string arg_help
  )
  {
    std::string short_sw, long_sw;
    std::tie(short_sw, long_sw) = values::parser_tool::SplitSwitchDef(opts);
  
    if (!short_sw.length() && !long_sw.length())
    {
      throw_or_mimic<invalid_option_format_error>(opts);
    }
    else if (long_sw.length() == 1 && short_sw.length())
    {
      throw_or_mimic<invalid_option_format_error>(opts);
    }
  
    auto option_names = []
    (
      const std::string &short_,
      const std::string &long_
    )
    {
      if (long_.length() == 1)
      {
        return std::make_tuple(long_, short_);
      }
      return std::make_tuple(short_, long_);
    }(short_sw, long_sw);
  
    m_options.add_option
    (
      m_group,
      std::get<0>(option_names),
      std::get<1>(option_names),
      desc,
      value,
      std::move(arg_help)
    );
  
    return *this;
  }
  
  inline
  void
  OptionParser::parse_default(const std::shared_ptr<OptionDetails>& details)
  {
    // TODO: remove the duplicate code here
    auto& store = m_parsed[details->hash()];
    store.parse_default(details);
    m_defaults.emplace_back(details->long_name(), details->value().get_default_value());
  }
  
  inline
  void
  OptionParser::parse_no_value(const std::shared_ptr<OptionDetails>& details)
  {
    auto& store = m_parsed[details->hash()];
    store.parse_no_value(details);
  }
  
  inline
  void
  OptionParser::parse_option
  (
    const std::shared_ptr<OptionDetails>& value,
    const std::string& /*name*/,
    const std::string& arg
  )
  {
    auto hash = value->hash();
    auto& result = m_parsed[hash];
    result.parse(value, arg);
  
    m_sequential.emplace_back(value->long_name(), arg);
  }
  
  inline
  void
  OptionParser::checked_parse_arg
  (
    int argc,
    const char* const* argv,
    int& current,
    const std::shared_ptr<OptionDetails>& value,
    const std::string& name
  )
  {
    if (current + 1 >= argc)
    {
      if (value->value().has_implicit())
      {
        parse_option(value, name, value->value().get_implicit_value());
      }
      else
      {
        throw_or_mimic<missing_argument_exception>(name);
      }
    }
    else
    {
      if (value->value().has_implicit())
      {
        parse_option(value, name, value->value().get_implicit_value());
      }
      else
      {
        parse_option(value, name, argv[current + 1]);
        ++current;
      }
    }
  }
  
  inline
  void
  OptionParser::add_to_option(OptionMap::const_iterator iter, const std::string& option, const std::string& arg)
  {
    parse_option(iter->second, option, arg);
  }
  
  inline
  bool
  OptionParser::consume_positional(const std::string& a, PositionalListIterator& next)
  {
    while (next != m_positional.end())
    {
      auto iter = m_options.find(*next);
      if (iter != m_options.end())
      {
        if (!iter->second->value().is_container())
        {
          auto& result = m_parsed[iter->second->hash()];
          if (result.count() == 0)
          {
            add_to_option(iter, *next, a);
            ++next;
            return true;
          }
          ++next;
          continue;
        }
        add_to_option(iter, *next, a);
        return true;
      }
      throw_or_mimic<option_not_exists_exception>(*next);
    }
  
    return false;
  }
  
  inline
  void
  Options::parse_positional(std::string option)
  {
    parse_positional(std::vector<std::string>{std::move(option)});
  }
  
  inline
  void
  Options::parse_positional(std::vector<std::string> options)
  {
    m_positional = std::move(options);
  
    m_positional_set.insert(m_positional.begin(), m_positional.end());
  }
  
  inline
  void
  Options::parse_positional(std::initializer_list<std::string> options)
  {
    parse_positional(std::vector<std::string>(options));
  }
  
  inline
  ParseResult
  Options::parse(int argc, const char* const* argv)
  {
    OptionParser parser(*m_options, m_positional, m_allow_unrecognised);
  
    return parser.parse(argc, argv);
  }
  
  inline ParseResult
  OptionParser::parse(int argc, const char* const* argv)
  {
    int current = 1;
    bool consume_remaining = false;
    auto next_positional = m_positional.begin();
  
    std::vector<std::string> unmatched;
  
    while (current != argc)
    {
      if (strcmp(argv[current], "--") == 0)
      {
        consume_remaining = true;
        ++current;
        break;
      }
      bool matched = false;
      values::parser_tool::ArguDesc argu_desc =
          values::parser_tool::ParseArgument(argv[current], matched);
  
      if (!matched)
      {
        //not a flag
  
        // but if it starts with a `-`, then it's an error
        if (argv[current][0] == '-' && argv[current][1] != '\0') {
          if (!m_allow_unrecognised) {
            throw_or_mimic<option_syntax_exception>(argv[current]);
          }
        }
  
        //if true is returned here then it was consumed, otherwise it is
        //ignored
        if (consume_positional(argv[current], next_positional))
        {
        }
        else
        {
          unmatched.emplace_back(argv[current]);
        }
        //if we return from here then it was parsed successfully, so continue
      }
      else
      {
        //short or long option?
        if (argu_desc.grouping)
        {
          const std::string& s = argu_desc.arg_name;
  
          for (std::size_t i = 0; i != s.size(); ++i)
          {
            std::string name(1, s[i]);
            auto iter = m_options.find(name);
  
            if (iter == m_options.end())
            {
              if (m_allow_unrecognised)
              {
                unmatched.push_back(std::string("-") + s[i]);
                continue;
              }
              //error
              throw_or_mimic<option_not_exists_exception>(name);
            }
  
            auto value = iter->second;
  
            if (i + 1 == s.size())
            {
              //it must be the last argument
              checked_parse_arg(argc, argv, current, value, name);
            }
            else if (value->value().has_implicit())
            {
              parse_option(value, name, value->value().get_implicit_value());
            }
            else if (i + 1 < s.size())
            {
              std::string arg_value = s.substr(i + 1);
              parse_option(value, name, arg_value);
              break;
            }
            else
            {
              //error
              throw_or_mimic<option_requires_argument_exception>(name);
            }
          }
        }
        else if (argu_desc.arg_name.length() != 0)
        {
          const std::string& name = argu_desc.arg_name;
  
          auto iter = m_options.find(name);
  
          if (iter == m_options.end())
          {
            if (m_allow_unrecognised)
            {
              // keep unrecognised options in argument list, skip to next argument
              unmatched.emplace_back(argv[current]);
              ++current;
              continue;
            }
            //error
            throw_or_mimic<option_not_exists_exception>(name);
          }
  
          auto opt = iter->second;
  
          //equals provided for long option?
          if (argu_desc.set_value)
          {
            //parse the option given
  
            parse_option(opt, name, argu_desc.value);
          }
          else
          {
            //parse the next argument
            checked_parse_arg(argc, argv, current, opt, name);
          }
        }
  
      }
  
      ++current;
    }
  
    for (auto& opt : m_options)
    {
      auto& detail = opt.second;
      const auto& value = detail->value();
  
      auto& store = m_parsed[detail->hash()];
  
      if (value.has_default()) {
        if (!store.count() && !store.has_default()) {
          parse_default(detail);
        }
      }
      else {
        parse_no_value(detail);
      }
    }
  
    if (consume_remaining)
    {
      while (current < argc)
      {
        if (!consume_positional(argv[current], next_positional)) {
          break;
        }
        ++current;
      }
  
      //adjust argv for any that couldn't be swallowed
      while (current != argc) {
        unmatched.emplace_back(argv[current]);
        ++current;
      }
    }
  
    finalise_aliases();
  
    ParseResult parsed(std::move(m_keys), std::move(m_parsed), std::move(m_sequential), std::move(m_defaults), std::move(unmatched));
    return parsed;
  }
  
  inline
  void
  OptionParser::finalise_aliases()
  {
    for (auto& option: m_options)
    {
      auto& detail = *option.second;
      auto hash = detail.hash();
      m_keys[detail.short_name()] = hash;
      m_keys[detail.long_name()] = hash;
  
      m_parsed.emplace(hash, OptionValue());
    }
  }
  
  inline
  void
  Options::add_option
  (
    const std::string& group,
    const Option& option
  )
  {
      add_options(group, {option});
  }
  
  inline
  void
  Options::add_option
  (
    const std::string& group,
    const std::string& s,
    const std::string& l,
    std::string desc,
    const std::shared_ptr<const Value>& value,
    std::string arg_help
  )
  {
    auto stringDesc = toLocalString(std::move(desc));
    auto option = std::make_shared<OptionDetails>(s, l, stringDesc, value);
  
    if (!s.empty())
    {
      add_one_option(s, option);
    }
  
    if (!l.empty())
    {
      add_one_option(l, option);
    }
  
    m_option_list.push_front(*option.get());
    auto iter = m_option_list.begin();
    m_option_map[s] = iter;
    m_option_map[l] = iter;
  
    //add the help details
    auto& options = m_help[group];
  
    options.options.emplace_back(HelpOptionDetails{s, l, stringDesc,
        value->has_default(), value->get_default_value(),
        value->has_implicit(), value->get_implicit_value(),
        std::move(arg_help),
        value->is_container(),
        value->is_boolean()});
  }
  
  inline
  void
  Options::add_one_option
  (
    const std::string& option,
    const std::shared_ptr<OptionDetails>& details
  )
  {
    auto in = m_options->emplace(option, details);
  
    if (!in.second)
    {
      throw_or_mimic<option_exists_error>(option);
    }
  }
  
  inline
  String
  Options::help_one_group(const std::string& g) const
  {
    using OptionHelp = std::vector<std::pair<String, String>>;
  
    auto group = m_help.find(g);
    if (group == m_help.end())
    {
      return "";
    }
  
    OptionHelp format;
  
    size_t longest = 0;
  
    String result;
  
    if (!g.empty())
    {
      result += toLocalString(" " + g + " options:\n");
    }
  
    for (const auto& o : group->second.options)
    {
      if (m_positional_set.find(o.l) != m_positional_set.end() &&
          !m_show_positional)
      {
        continue;
      }
  
      auto s = format_option(o);
      longest = (std::max)(longest, stringLength(s));
      format.push_back(std::make_pair(s, String()));
    }
    longest = (std::min)(longest, OPTION_LONGEST);
  
    //widest allowed description -- min 10 chars for helptext/line
    size_t allowed = 10;
    if (m_width > allowed + longest + OPTION_DESC_GAP)
    {
      allowed = m_width - longest - OPTION_DESC_GAP;
    }
  
    auto fiter = format.begin();
    for (const auto& o : group->second.options)
    {
      if (m_positional_set.find(o.l) != m_positional_set.end() &&
          !m_show_positional)
      {
        continue;
      }
  
      auto d = format_description(o, longest + OPTION_DESC_GAP, allowed, m_tab_expansion);
  
      result += fiter->first;
      if (stringLength(fiter->first) > longest)
      {
        result += '\n';
        result += toLocalString(std::string(longest + OPTION_DESC_GAP, ' '));
      }
      else
      {
        result += toLocalString(std::string(longest + OPTION_DESC_GAP -
          stringLength(fiter->first),
          ' '));
      }
      result += d;
      result += '\n';
  
      ++fiter;
    }
  
    return result;
  }
  
  inline
  void
  Options::generate_group_help
  (
    String& result,
    const std::vector<std::string>& print_groups
  ) const
  {
    for (size_t i = 0; i != print_groups.size(); ++i)
    {
      const String& group_help_text = help_one_group(print_groups[i]);
      if (empty(group_help_text))
      {
        continue;
      }
      result += group_help_text;
      if (i < print_groups.size() - 1)
      {
        result += '\n';
      }
    }
  }
  
  inline
  void
  Options::generate_all_groups_help(String& result) const
  {
    std::vector<std::string> all_groups;
  
    std::transform(
      m_help.begin(),
      m_help.end(),
      std::back_inserter(all_groups),
      [] (const std::map<std::string, HelpGroupDetails>::value_type& group)
      {
        return group.first;
      }
    );
  
    generate_group_help(result, all_groups);
  }
  
  inline
  std::string
  Options::help(const std::vector<std::string>& help_groups) const
  {
    String result = m_help_string + "\nUsage:\n  " +
      toLocalString(m_program) + " " + toLocalString(m_custom_help);
  
    if (!m_positional.empty() && !m_positional_help.empty()) {
      result += " " + toLocalString(m_positional_help);
    }
  
    result += "\n\n";
  
    if (help_groups.empty())
    {
      generate_all_groups_help(result);
    }
    else
    {
      generate_group_help(result, help_groups);
    }
  
    return toUTF8String(result);
  }
  
  inline
  std::vector<std::string>
  Options::groups() const
  {
    std::vector<std::string> g;
  
    std::transform(
      m_help.begin(),
      m_help.end(),
      std::back_inserter(g),
      [] (const std::map<std::string, HelpGroupDetails>::value_type& pair)
      {
        return pair.first;
      }
    );
  
    return g;
  }
  
  inline
  const HelpGroupDetails&
  Options::group_help(const std::string& group) const
  {
    return m_help.at(group);
  }
  
  } // namespace cxxopts
  
  #endif //CXXOPTS_HPP_INCLUDED
  