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/**
* @file script.hpp
* Manages all Lua scripts.
*
* Copyright (C) 2019 Belle-Isle, Andrew <drumsetmonkey@gmail.com>
*
* 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 3 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; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef SYSTEM_SCRIPT_HPP_
#define SYSTEM_SCRIPT_HPP_
#include "world.hpp"
#include <entityx/entityx.h>
#include <sol/sol.hpp>
#include <concepts>
/**
* Utility for pairing class instances to their member function calls.
* This is useful for adding functions to the Lua game namespace.
*
* TODO I am certain that this can be done better. -clyne
*
* @param func The member function to call
* @param instance The instance to bind to
* @return A function that calls the member function using the given instance
*/
template<class C, typename R, typename... Args>
auto bindInstance(R (C::* func)(Args...), C *instance)
{
if constexpr (std::same_as<R, void>)
return [instance, func](Args... args) { (instance->*func)(args...); };
else
return [instance, func](Args... args) { return (instance->*func)(args...); };
}
template<class C, typename R, typename... Args>
auto bindInstance(R (C::* func)(Args...) const, const C *instance)
{
if constexpr (std::same_as<R, void>)
return [instance, func](Args... args) { (instance->*func)(args...); };
else
return [instance, func](Args... args) { return (instance->*func)(args...); };
}
struct EntitySpawnEvent
{
sol::object ref;
EntitySpawnEvent(sol::object _ref) :
ref(_ref) {}
};
/**
* @class ScriptSystem
* Handles all the game's scripting requests
*/
class ScriptSystem : public entityx::System<ScriptSystem>,
public entityx::Receiver<ScriptSystem>
{
private:
/**
* The script systems internal lua state that handles all
* interactions between C and Lua
*/
sol::state lua;
sol::table game;
entityx::EntityManager& manager;
// TODO possibly emit events to spawn worlds instead of passing the
// world system around like a toy
WorldSystem &worldSystem;
public:
ScriptSystem(entityx::EntityManager& _mg, WorldSystem& _ws):
manager(_mg), worldSystem(_ws) {}
~ScriptSystem(void) {}
/**
* Prepares the system for running.
*/
void configure(entityx::EntityManager& entities,
entityx::EventManager& events) final;
/**
* Updates the scripting system.
*/
void update(entityx::EntityManager& entites,
entityx::EventManager& events,
entityx::TimeDelta dt) final;
/**
* Receives all entity spawning events and manages the
* script counterpart.
*/
void receive(const EntitySpawnEvent &toSpawn);
/**
* Initializes the lua states and libraries.
* @return Zero on success, non-zero on error
*/
int init(void);
/**
* Run the initialization file.
*/
void doFile(void);
/**
* The function called by lua scripts in order to spawn an entity.
* @param param The table that must be passed in by Lua. This is a
* sol2 object instead of a sol2 table because this allows us to handle
* errors easier instead of letting sol2 do the error handling.
*/
sol::table spawn(sol::object param);
/**
* Contains all calls that export components/functions to lua.
*/
void scriptExport(void);
template<typename F>
void addToGameNamespace(const std::string& name, F func) {
game.set_function(name, func);
}
};
#endif // SYSTEM_SCRIPT_HPP_
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