synced_commands.hpp

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/*
    Copyright (C) 2014 - 2024
    by David White <dave@whitevine.net>
    Part of the Battle for Wesnoth Project https://www.wesnoth.org/
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY.
 
    See the COPYING file for more details.
*/
 
#pragma once
 
#include <map>
#include <string>
 
#include <functional>
 
class config;
 
class action_spectator
{
public:
    typedef std::function<void(const std::string&)> error_handler_function;
    action_spectator() = default;
    action_spectator(error_handler_function eh)
        : eh_(eh)
    {
    }
    virtual ~action_spectator() = default;
    /**
     * Called when synced_context::run received nonsensial data based on the current gamestate.
     */
    virtual void error(const std::string& message)
    {
        eh_(message);
    }
    error_handler_function eh_;
};
 
// TODO: it would be nice if we would use some consistent terminology along the codebase
//       The things that the user invokes are sometimes called "commands" (in particular
//       in the replay), and sometimes called "actions" (in particular inn the actions/ folder)
 
class synced_command {
    public:
        /*
            the parameters or error handlers are
            1) the message of the error
        */
        typedef std::function<void(const std::string&)> error_handler_function;
        /*
            returns: true if the action succeeded correctly,
        */
        typedef bool (*handler)(const config&, action_spectator& spectator);
        typedef std::map<std::string, handler> map;
 
 
        synced_command(const std::string & tag, handler function);
 
        /** using static function variable instead of static member variable to prevent static initialization fiasco when used in other files. */
        static map& registry();
    };
 
/*
    this is currently only used in "synced_commands.cpp" and there is no reason to use it anywhere else.
    but if you have a good reason feel free to do so.
*/
 
#define SYNCED_COMMAND_HANDLER_FUNCTION(pname, pcfg, spectator) \
    static bool synced_command_func_##pname(const config& pcfg, action_spectator& spectator); \
    static synced_command synced_command_action_##pname(#pname, &synced_command_func_##pname);  \
    static bool synced_command_func_##pname(const config& pcfg, action_spectator& spectator)