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Command.h
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Command.h
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/**
* Action - A convenient single-file and header only implementation of the Action-pattern with modern c++.
* Copyright (C) 2016 Felix Becker - fb132550@uni-greifswald.de
*
* This software is provided 'as-is', without any express or
* implied warranty. In no event will the authors be held
* liable for any damages arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute
* it freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented;
* you must not claim that you wrote the original software.
* If you use this software in a product, an acknowledgment
* in the product documentation would be appreciated but
* is not required.
*
* 2. Altered source versions must be plainly marked as such,
* and must not be misrepresented as being the original software.
*
* 3. This notice may not be removed or altered from any
* source distribution.
*/
#ifndef Action_H
#define Action_H
#include <deque>
#include <memory>
#include <tuple>
namespace command
{
/** \brief A manager-object for Actions that works as a stack holding a predefined number of
* Actions. The manager offers the possibility to undo the upmost operation on the stack. */
class ActionManager
{
public:
ActionManager() : mStackSize(100), mUndoMaker(mActionStack.end()) {}
/** \brief Executes a new action function with arbitrary parameters and stores it on top of
* the internal stack along with a corresponding redo function, taking exactly the same parameters. */
template<typename FUNC, typename ... PARAM>
inline void execute( FUNC action, FUNC undo, PARAM&& ... param );
/** \brief Undo the last performed Action. (the Action that is on top of the stack) */
inline void undo();
/** \brief Redo an action that was undo()ne before. */
inline void redo();
private:
/** \brief A base for all editor Actions than can be executed and made undone. */
class BaseAction
{
friend class ActionManager;
private:
/** \brief Invokes the action. */
virtual void execute() = 0;
/** \brief Undo the action. */
virtual void undo() = 0;
};
template<typename ... PARAM>
class Action : public BaseAction
{
private:
std::tuple<PARAM...> mParam;
std::function<void(PARAM ...)> mActionCallback;
std::function<void(PARAM ...)> mUndoCallback;
template<std::size_t ...I>
void callAction(std::index_sequence<I...>);
template<std::size_t ...I>
void callUndo(std::index_sequence<I...>);
virtual void execute() override;
virtual void undo() override;
public:
Action(std::function<void(PARAM ...)> cAction, std::function<void(PARAM ...)> cUndo, PARAM&& ... param);
};
unsigned mStackSize; ///<indicates how deep the "memory" of the Action-manager is
std::deque< std::unique_ptr<BaseAction> > mActionStack;
std::deque< std::unique_ptr<BaseAction> >::iterator mUndoMaker;
};
template<typename FUNC, typename ... PARAM>
void ActionManager::execute( FUNC action, FUNC undo, PARAM&& ... param )
{
mActionStack.erase(mUndoMaker, mActionStack.end());
mActionStack.emplace_back(std::unique_ptr<BaseAction>( new Action<PARAM...>( std::function<void(PARAM ...)>(action),
std::function<void(PARAM ...)>(undo),
std::forward<PARAM>(param)...) ));
mUndoMaker = mActionStack.end();
mActionStack.back()->execute();
if (mActionStack.size() > mStackSize)
mActionStack.pop_front();
}
void ActionManager::undo()
{
if (mUndoMaker != mActionStack.begin()) //remember that begin == end when container is empty
{
mUndoMaker = std::prev(mUndoMaker);
mUndoMaker->get()->undo();
}
}
void ActionManager::redo()
{
if (mUndoMaker != mActionStack.end())
{
mUndoMaker->get()->execute();
mUndoMaker = std::next(mUndoMaker);
}
}
template<typename ... PARAM>
ActionManager::Action<PARAM...>::Action(std::function<void(PARAM ...)> cAction,
std::function<void(PARAM ...)> cUndo,
PARAM&& ... param) :
mParam( std::forward_as_tuple(std::forward<PARAM>(param)...) )
{
mActionCallback = cAction;
mUndoCallback = cUndo;
}
template<typename ... PARAM>
template<std::size_t ...I>
void ActionManager::Action<PARAM...>::callAction(std::index_sequence<I...>)
{
mActionCallback(std::get<I>(mParam)...);
}
template<typename ... PARAM>
template<std::size_t ...I>
void ActionManager::Action<PARAM...>::callUndo(std::index_sequence<I...>)
{
mUndoCallback(std::get<I>(mParam)...);
}
template<typename ... PARAM>
void ActionManager::Action<PARAM...>::execute()
{
callAction( std::index_sequence_for<PARAM...>{} );
}
template<typename ... PARAM>
void ActionManager::Action<PARAM...>::undo()
{
callUndo( std::index_sequence_for<PARAM...>{} );
}
}
#endif // Action_H