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◆ main openmsx / src / commands / Command.hh
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#ifndef COMMAND_HH
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#define COMMAND_HH
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#include "CommandException.hh"
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#include "Completer.hh"
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#include "strCat.hh"
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#include <cassert>
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#include <span>
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#include <string_view>
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#include <vector>
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namespace openmsx {
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class CommandController;
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class GlobalCommandController;
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class Interpreter;
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class TclObject;
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class CliComm;
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class CommandCompleter : public Completer
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{
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public:
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	CommandCompleter(const CommandCompleter&) = delete;
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	CommandCompleter(CommandCompleter&&) = delete;
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	CommandCompleter& operator=(const CommandCompleter&) = delete;
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	CommandCompleter& operator=(CommandCompleter&&) = delete;
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	[[nodiscard]] CommandController& getCommandController() const { return commandController; }
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	[[nodiscard]] Interpreter& getInterpreter() const final;
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protected:
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	CommandCompleter(CommandController& controller, std::string_view name);
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	~CommandCompleter();
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	[[nodiscard]] GlobalCommandController& getGlobalCommandController() const;
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	[[nodiscard]] CliComm& getCliComm() const;
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private:
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	CommandController& commandController;
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};
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class Command : public CommandCompleter
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{
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	struct UnknownSubCommand {};
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public:
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	/** Execute this command.
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	  * @param tokens Tokenized command line;
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	  *     tokens[0] is the command itself.
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	  * @param result The result of the command must be assigned to this
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	  *               parameter.
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	  * @throws CommandException Thrown when there was an error while
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	  *                          executing this command.
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	  */
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	virtual void execute(std::span<const TclObject> tokens, TclObject& result) = 0;
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	/** Attempt tab completion for this command.
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	  * Default implementation does nothing.
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	  * @param tokens Tokenized command line;
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	  *     tokens[0] is the command itself.
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	  *     The last token is incomplete, this method tries to complete it.
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	  */
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	void tabCompletion(std::vector<std::string>& tokens) const override;
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	// see comments in MSXMotherBoard::loadMachineCommand
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	void setAllowedInEmptyMachine(bool value) { allowInEmptyMachine = value; }
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	[[nodiscard]] bool isAllowedInEmptyMachine() const { return allowInEmptyMachine; }
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	// used by Interpreter::(un)registerCommand()
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	void setToken(void* token_) { assert(!token); token = token_; }
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	[[nodiscard]] void* getToken() const { return token; }
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	// helper to delegate to a subcommand
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	template<typename... Args>
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	void executeSubCommand(std::string_view subCmd, Args&&... args) {
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		try {
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			executeSubCommandImpl(subCmd, std::forward<Args>(args)...);
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		} catch (UnknownSubCommand&) {
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			unknownSubCommand(subCmd, std::forward<Args>(args)...);
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		}
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	}
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protected:
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	Command(CommandController& controller, std::string_view name);
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	~Command();
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private:
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	template<typename Func, typename... Args>
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	void executeSubCommandImpl(std::string_view subCmd, std::string_view candidate, Func func, Args&&... args) const {
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		if (subCmd == candidate) {
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			func();
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		} else {
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			executeSubCommandImpl(subCmd, std::forward<Args>(args)...);
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		}
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	}
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	[[noreturn]] void executeSubCommandImpl(std::string_view /*subCmd*/) const {
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		throw UnknownSubCommand{}; // exhausted all possible candidates
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	}
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	template<typename Func, typename... Args>
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	void unknownSubCommand(std::string_view subCmd, std::string_view firstCandidate, Func /*func*/, Args&&... args) const {
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		unknownSubCommandImpl(strCat("Unknown subcommand '", subCmd, "'. Must be one of '", firstCandidate, '\''),
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		                      std::forward<Args>(args)...);
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	}
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	template<typename Func, typename... Args>
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	void unknownSubCommandImpl(std::string message, std::string_view candidate, Func /*func*/, Args&&... args) const {
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		strAppend(message, ", '", candidate, '\'');
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		unknownSubCommandImpl(message, std::forward<Args>(args)...);
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		throw SyntaxError();
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	}
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	template<typename Func>
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	void unknownSubCommandImpl(std::string message, std::string_view lastCandidate, Func /*func*/) const {
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		strAppend(message, " or '", lastCandidate, "'.");
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		throw CommandException(message);
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	}
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private:
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	bool allowInEmptyMachine = true;
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	void* token = nullptr;
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};
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} // namespace openmsx
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#endif