memento_command.h

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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/libpbd_visibility.h"
#include "pbd/command.h"
#include "pbd/stacktrace.h"
#include "pbd/xml++.h"
#include "pbd/demangle.h"

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

template <class obj_T>
class LIBPBD_TEMPLATE_API MementoCommandBinder : public PBD::Destructible
{
public:
        virtual obj_T* get () const = 0;

        virtual std::string type_name () const {
                return PBD::demangled_name (*get ());
        }

        virtual void add_state (XMLNode *) = 0;
};

template <class obj_T>
class LIBPBD_TEMPLATE_API SimpleMementoCommandBinder : public MementoCommandBinder<obj_T>
{
public:
        SimpleMementoCommandBinder (obj_T& o)
                : _object (o)
        {
                _object.Destroyed.connect_same_thread (_object_death_connection, boost::bind (&SimpleMementoCommandBinder::object_died, this));
        }

        obj_T* get () const {
                return &_object;
        }

        void add_state (XMLNode* node) {
                node->add_property ("obj_id", _object.id().to_s());
        }
        
        void object_died () {
                /* The object we are binding died, so drop references to ourselves */
                this->drop_references ();
        }

private:
        obj_T& _object;
        PBD::ScopedConnection _object_death_connection;
};

template <class obj_T>
class LIBPBD_TEMPLATE_API MementoCommand : public Command
{
public:
        MementoCommand (obj_T& a_object, XMLNode* a_before, XMLNode* a_after) 
                : _binder (new SimpleMementoCommandBinder<obj_T> (a_object)), before (a_before), after (a_after)
        {
                /* The binder's object died, so we must die */
                _binder->DropReferences.connect_same_thread (_binder_death_connection, boost::bind (&MementoCommand::binder_dying, this));
        }

        MementoCommand (MementoCommandBinder<obj_T>* b, XMLNode* a_before, XMLNode* a_after) 
                : _binder (b), before (a_before), after (a_after)
        {
                /* The binder's object died, so we must die */
                _binder->DropReferences.connect_same_thread (_binder_death_connection, boost::bind (&MementoCommand::binder_dying, this));
        }
        
        ~MementoCommand () {
                drop_references ();
                delete before;
                delete after;
                delete _binder;
        }

        void binder_dying () {
                delete this;
        }

        void operator() () {
                if (after) {
                        _binder->get()->set_state(*after, Stateful::current_state_version); 
                }
        }

        void undo() { 
                if (before) {
                        _binder->get()->set_state(*before, Stateful::current_state_version); 
                }
        }

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

                XMLNode* node = new XMLNode(name);
                _binder->add_state (node);
                
                node->add_property ("type_name", _binder->type_name ());

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

                return *node;
        }

protected:
        MementoCommandBinder<obj_T>* _binder;
        XMLNode* before;
        XMLNode* after;
        PBD::ScopedConnection _binder_death_connection;
};

#endif // __lib_pbd_memento_h__