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/* 
    Copyright (C) 2006 Paul Davis
    Author: Hans Fugal

    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; 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, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#ifndef __lib_pbd_memento_command_h__
#define __lib_pbd_memento_command_h__

#include <iostream>

#include <pbd/command.h>
#include <pbd/stacktrace.h>
#include <pbd/xml++.h>
#include <pbd/shiva.h>

#include <sigc++/slot.h>
#include <typeinfo>

/** This command class is initialized with before and after mementos 
 * (from Stateful::get_state()), so undo becomes restoring the before
 * memento, and redo is restoring the after memento.
 */
template <class obj_T>
class MementoCommand : public Command
{
public:
	MementoCommand(obj_T &object, XMLNode *before, XMLNode *after) 
		: obj(object), before(before), after(after)
	{
		/* catch destruction of the object */
		new PBD::Shiva<obj_T,MementoCommand<obj_T> > (object, *this);
	}

	~MementoCommand ()
	{
		GoingAway(); /* EMIT SIGNAL */
		
		if (before)
			delete before;
		
		if (after)
			delete after;
	}

	void operator() () 
	{
		if (after)
			obj.set_state(*after); 
	}

	void undo() 
	{ 
		if (before)
			obj.set_state(*before); 
	}

	virtual XMLNode &get_state() 
	{
		string name;
		if (before && after)
			name = "MementoCommand";
		else if (before)
			name = "MementoUndoCommand";
		else
			name = "MementoRedoCommand";

		XMLNode *node = new XMLNode(name);

		node->add_property("obj_id", obj.id().to_s());
		node->add_property("type_name", typeid(obj).name());

		if (before)
			node->add_child_copy(*before);
		
		if (after)
			node->add_child_copy(*after);

		return *node;
	}

protected:
	obj_T &obj;
	XMLNode *before, *after;
};

#endif // __lib_pbd_memento_h__