text: // Author: Mario Sieg
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  //    Copyright 2021 Mario Sieg "pinsrq" <mt3000@gmx.de>
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  #pragma once
  
  #include <string_view>
  #include <unordered_set>
  #include <vector>
  
  #include "IDisplay.hpp"
  
  namespace Nominax::Foundation
  {
      /// <summary>
      /// Command line option.
      /// </summary>
      struct CLIOption final
      {
          /// <summary>
          /// Short name. For example: -h.
          /// </summary>
          std::string_view Short { };
  
          /// <summary>
          /// Long name. For example: --help.
          /// </summary>
          std::string_view Long { };
  
          /// <summary>
          /// Help message for the user.
          /// </summary>
          std::string_view Description { };
      };
  
  	/// <summary>
  	/// Helper to parse command line interface arguments.
  	/// </summary>
  	class CLIParser final : public IDisplay
  	{
  		/// <summary>
  		/// Arguments from environment.
  		/// </summary>
  		std::unordered_set<std::string_view> Args_ { };
  
  		/// <summary>
  		/// Registered available options.
  		/// </summary>
  		std::vector<CLIOption> Options_ { };
  
  	public:
  		/// <summary>
  		/// Construct with argc and argv from
  		/// the entry point.
  		/// </summary>
  		/// <param name="argc"></param>
  		/// <param name="argv"></param>
  		/// <returns></returns>
  		CLIParser(int argc, const char* const* argv);
  
  		/// <summary>
  		/// No copy.
  		/// </summary>
  		/// <param name="other"></param>
  		CLIParser(const CLIParser& other) = delete;
  
  		/// <summary>
  		/// Move constructor.
  		/// </summary>
  		/// <param name="other"></param>
  		/// <returns></returns>
  		CLIParser(CLIParser&& other) = default;
  
  		/// <summary>
  		/// No copy.
  		/// </summary>
  		/// <param name="other"></param>
  		/// <returns></returns>
  		auto operator =(const CLIParser& other) -> CLIParser& = delete;
  
  		/// <summary>
  		/// Move assignment operator.
  		/// </summary>
  		/// <param name="other"></param>
  		/// <returns></returns>
  		auto operator =(CLIParser&& other) -> CLIParser& = default;
  
  		/// <summary>
  		/// Destructor.
  		/// </summary>
  		~CLIParser() override = default;
  
  		/// <summary>
  		/// Returns true if the command line flag is set,
  		/// else false.
  		/// </summary>
  		/// <param name="key"></param>
  		/// <returns></returns>
  		[[nodiscard]]
  		auto HasFlag(const CLIOption& option) const -> bool;
  
  		/// <summary>
  		/// Adds a command line option with description.
  		/// </summary>
  		/// <param name="option">The new option.</param>
  		auto AddOption(const CLIOption& option) -> void;
  
          /// <summary>
          /// Prints this object into the file stream.
          /// </summary>
          virtual auto Display(std::FILE& stream) const -> void override;
  
  		/// <summary>
  		/// Returns true if the argument count is less or equal to one,
  		/// because one is the self path, else false.
  		/// </summary>
  		/// <returns></returns>
  		[[nodiscard]]
  		auto IsEmpty() const -> bool;
  
  		/// <summary>
  		/// Returns argument set.
  		/// </summary>
  		/// <returns></returns>
  		[[nodiscard]]
  		auto GetArgs() const -> const std::unordered_set<std::string_view>&;
  
  		/// <summary>
  		/// Returns all added options.
  		/// </summary>
  		/// <returns></returns>
  		[[nodiscard]]
  		auto GetOptions() const -> const std::vector<CLIOption>&;
  	};
  }
  