cmdparser.hpp

/*
  This file is part of the C++ CmdParser utility.
  Copyright (c) 2015 - 2016 Florian Rappl
*/

#pragma once
#include <iostream>
#include <stdexcept>
#include <string>
#include <vector>
#include <sstream>
#include <functional>

namespace cli {
	struct CallbackArgs {
		const std::vector<std::string>& arguments;
		std::ostream& output;
		std::ostream& error;
	};
	class Parser {
	private:
		class CmdBase {
		public:
			explicit CmdBase(const std::string& name, const std::string& alternative, const std::string& description, bool required, bool dominant, bool variadic) :
				name(name),
				command(name.size() > 0 ? "-" + name : ""),
				alternative(alternative.size() > 0 ? "--" + alternative : ""),
				description(description),
				required(required),
				handled(false),
				arguments({}),
				dominant(dominant),
				variadic(variadic) {
			}

			virtual ~CmdBase() {
			}

			std::string name;
			std::string command;
			std::string alternative;
			std::string description;
			bool required;
			bool handled;
			std::vector<std::string> arguments;
			bool const dominant;
			bool const variadic;

			virtual std::string print_value() const = 0;
			virtual bool parse(std::ostream& output, std::ostream& error) = 0;

			bool is(const std::string& given) const {
				return given == command || given == alternative;
			}
		};

		template<typename T>
		struct ArgumentCountChecker
		{
			static constexpr bool Variadic = false;
		};

		template<typename T>
		struct ArgumentCountChecker<std::vector<T>>
		{
			static constexpr bool Variadic = true;
		};

		template<typename T>
		class CmdFunction final : public CmdBase {
		public:
			explicit CmdFunction(const std::string& name, const std::string& alternative, const std::string& description, bool required, bool dominant) :
				CmdBase(name, alternative, description, required, dominant, ArgumentCountChecker<T>::Variadic) {
			}

			virtual bool parse(std::ostream& output, std::ostream& error) {
				try {
					CallbackArgs args { arguments, output, error };
					value = callback(args);
					return true;
				} catch (...) {
					return false;
				}
			}

			virtual std::string print_value() const {
				return "";
			}

			std::function<T(CallbackArgs&)> callback;
			T value;
		};

		template<typename T>
		class CmdArgument final : public CmdBase {
		public:
			explicit CmdArgument(const std::string& name, const std::string& alternative, const std::string& description, bool required, bool dominant) :
				CmdBase(name, alternative, description, required, dominant, ArgumentCountChecker<T>::Variadic) {
			}

			virtual bool parse(std::ostream&, std::ostream&) {
				try {
					value = Parser::parse(arguments, value);
					return true;
				} catch (...) {
					return false;
				}
			}

			virtual std::string print_value() const {
				return stringify(value);
			}

			T value;
		};

		static int parse(const std::vector<std::string>& elements, const int&) {
			if (elements.size() != 1)
				throw std::bad_cast();

			return std::stoi(elements[0]);
		}

		static bool parse(const std::vector<std::string>& elements, const bool& defval) {
			if (elements.size() != 0)
				throw std::runtime_error("A boolean command line parameter cannot have any arguments.");

			return !defval;
		}

		static double parse(const std::vector<std::string>& elements, const double&) {
			if (elements.size() != 1)
				throw std::bad_cast();

			return std::stod(elements[0]);
		}

		static float parse(const std::vector<std::string>& elements, const float&) {
			if (elements.size() != 1)
				throw std::bad_cast();

			return std::stof(elements[0]);
		}

		static long double parse(const std::vector<std::string>& elements, const long double&) {
			if (elements.size() != 1)
				throw std::bad_cast();

			return std::stold(elements[0]);
		}

		static unsigned int parse(const std::vector<std::string>& elements, const unsigned int&) {
			if (elements.size() != 1)
				throw std::bad_cast();

			return static_cast<unsigned int>(std::stoul(elements[0]));
		}

		static unsigned long parse(const std::vector<std::string>& elements, const unsigned long&) {
			if (elements.size() != 1)
				throw std::bad_cast();

			return std::stoul(elements[0]);
		}

		static long parse(const std::vector<std::string>& elements, const long&) {
			if (elements.size() != 1)
				throw std::bad_cast();

			return std::stol(elements[0]);
		}

		static std::string parse(const std::vector<std::string>& elements, const std::string&) {
			if (elements.size() != 1)
				throw std::bad_cast();

			return elements[0];
		}

		template<class T>
		static std::vector<T> parse(const std::vector<std::string>& elements, const std::vector<T>&) {
			const T defval = T();
			std::vector<T> values { };
			std::vector<std::string> buffer(1);

			for (const auto& element : elements) {
				buffer[0] = element;
				values.push_back(parse(buffer, defval));
			}

			return values;
		}

		template<class T>
		static std::string stringify(const T& value) {
			return std::to_string(value);
		}

		template<class T>
		static std::string stringify(const std::vector<T>& values) {
			std::stringstream ss { };
			ss << "[ ";

			for (const auto& value : values) {
				ss << stringify(value) << " ";
			}

			ss << "]";
			return ss.str();
		}

		static std::string stringify(const std::string& str) {
			return str;
		}

	public:
		explicit Parser(int argc, const char** argv) :
			_appname(argv[0]) {
			for (int i = 1; i < argc; ++i) {
				_arguments.push_back(argv[i]);
			}
			enable_help();
		}

		explicit Parser(int argc, char** argv) :
			_appname(argv[0]) {
			for (int i = 1; i < argc; ++i) {
				_arguments.push_back(argv[i]);
			}
			enable_help();
		}

		~Parser() {
			for (int i = 0, n = _commands.size(); i < n; ++i) {
				delete _commands[i];
			}
		}

		bool has_help() const {
			for (const auto command : _commands) {
				if (command->name == "h" && command->alternative == "--help") {
					return true;
				}
			}

			return false;
		}

		void enable_help() {
			set_callback("h", "help", std::function<bool(CallbackArgs&)>([this](CallbackArgs& args){
				args.output << this->usage();
				exit(0);
				return false;
			}), "", true);
		}

		void disable_help() {
			for (auto command = _commands.begin(); command != _commands.end(); ++command) {
				if ((*command)->name == "h" && (*command)->alternative == "--help") {
					_commands.erase(command);
					break;
				}
			}
		}

		template<typename T>
		void set_default(bool is_required, const std::string& description = "") {
			auto command = new CmdArgument<T> { "", "", description, is_required, false };
			_commands.push_back(command);
		}

		template<typename T>
		void set_required(const std::string& name, const std::string& alternative, const std::string& description = "", bool dominant = false) {
			auto command = new CmdArgument<T> { name, alternative, description, true, dominant };
			_commands.push_back(command);
		}

		template<typename T>
		void set_optional(const std::string& name, const std::string& alternative, T defaultValue, const std::string& description = "", bool dominant = false) {
			auto command = new CmdArgument<T> { name, alternative, description, false, dominant };
			command->value = defaultValue;
			_commands.push_back(command);
		}

		template<typename T>
		void set_callback(const std::string& name, const std::string& alternative, std::function<T(CallbackArgs&)> callback, const std::string& description = "", bool dominant = false) {
			auto command = new CmdFunction<T> { name, alternative, description, false, dominant };
			command->callback = callback;
			_commands.push_back(command);
		}

		inline void run_and_exit_if_error() {
			if (run() == false) {
				exit(1);
			}
		}

		inline bool run() {
			return run(std::cout, std::cerr);
		}

		inline bool run(std::ostream& output) {
			return run(output, std::cerr);
		}

		bool run(std::ostream& output, std::ostream& error) {
			if (_arguments.size() > 0) {
				auto current = find_default();

				for (int i = 0, n = _arguments.size(); i < n; ++i) {
					auto isarg = _arguments[i].size() > 0 && _arguments[i][0] == '-';
					auto associated = isarg ? find(_arguments[i]) : nullptr;

					if (associated != nullptr) {
						current = associated;
						associated->handled = true;
					} else if (current == nullptr) {
						error << no_default();
						return false;
					} else {
						current->arguments.push_back(_arguments[i]);
						current->handled = true;
						if (!current->variadic)
						{
							// If the current command is not variadic, then no more arguments
							// should be added to it. In this case, switch back to the default
							// command.
							current = find_default();
						}
					}
				}
			}

			// First, parse dominant arguments since they succeed even if required
			// arguments are missing.
			for (auto command : _commands) {
				if (command->handled && command->dominant && !command->parse(output, error)) {
					error << howto_use(command);
					return false;
				}
			}

			// Next, check for any missing arguments.
			for (auto command : _commands) {
				if (command->required && !command->handled) {
					error << howto_required(command);
					return false;
				}
			}

			// Finally, parse all remaining arguments.
			for (auto command : _commands) {
				if (command->handled && !command->dominant && !command->parse(output, error)) {
					error << howto_use(command);
					return false;
				}
			}

			return true;
		}

		template<typename T>
		T get(const std::string& name) const {
			for (const auto& command : _commands) {
				if (command->name == name) {
					auto cmd = dynamic_cast<CmdArgument<T>*>(command);

					if (cmd == nullptr) {
						throw std::runtime_error("Invalid usage of the parameter " + name + " detected.");
					}

					return cmd->value;
				}
			}

			throw std::runtime_error("The parameter " + name + " could not be found.");
		}

		template<typename T>
		T get_if(const std::string& name, std::function<T(T)> callback) const {
			auto value = get<T>(name);
			return callback(value);
		}

		int requirements() const {
			int count = 0;

			for (const auto& command : _commands) {
				if (command->required) {
					++count;
				}
			}

			return count;
		}

		int commands() const {
			return static_cast<int>(_commands.size());
		}

		inline const std::string& app_name() const {
			return _appname;
		}

	protected:
		CmdBase* find(const std::string& name) {
			for (auto command : _commands) {
				if (command->is(name)) {
					return command;
				}
			}

			return nullptr;
		}

		CmdBase* find_default() {
			for (auto command : _commands) {
				if (command->name == "") {
					return command;
				}
			}

			return nullptr;
		}

		std::string usage() const {
			std::stringstream ss { };
			ss << "Available parameters:\n\n";

			for (const auto& command : _commands) {
				ss << "  " << command->command << "\t" << command->alternative;

				if (command->required == true) {
					ss << "\t(required)";
				}

				ss << "\n   " << command->description;

				if (command->required == false) {
					ss << "\n   " << "This parameter is optional. The default value is '" + command->print_value() << "'.";
				}

				ss << "\n\n";
			}

			return ss.str();
		}

		void print_help(std::stringstream& ss) const {
			if (has_help()) {
				ss << "For more help use --help or -h.\n";
			}
		}

		std::string howto_required(CmdBase* command) const {
			std::stringstream ss { };
			ss << "The parameter " << command->name << " is required.\n";
			ss << command->description << '\n';
			print_help(ss);
			return ss.str();
		}

		std::string howto_use(CmdBase* command) const {
			std::stringstream ss { };
			ss << "The parameter " << command->name << " has invalid arguments.\n";
			ss << command->description << '\n';
			print_help(ss);
			return ss.str();
		}

		std::string no_default() const {
			std::stringstream ss { };
			ss << "No default parameter has been specified.\n";
			ss << "The given argument must be used with a parameter.\n";
			print_help(ss);
			return ss.str();
		}

	private:
		const std::string _appname;
		std::vector<std::string> _arguments;
		std::vector<CmdBase*> _commands;
	};
}