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/*
This file is part of KAddressBook.
Copyright (C) 1999 Don Sanders <sanders@kde.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; 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
As a special exception, permission is given to link this program
with any edition of Qt, and distribute the resulting executable,
without including the source code for Qt in the source distribution.
*/
#ifndef UNDO_H
#define UNDO_H
#include <qobject.h>
#include <q3ptrstack.h>
#include <qstring.h>
class Command
{
public:
Command() {}
virtual ~Command() {};
virtual QString name() = 0;
virtual void redo() = 0; // egcs requires these methods to have
virtual void undo() = 0; // implementations (Seems like a bug)
// pure virtual may not work
};
/** The Undo and Redo stacks now no longer inherit directly from a stack.
* They now contain a stack internally and inherit from StackBase, which
* has a signal for when the stack is modified. This is need to keep
* the edit menu and toolbar up to date.
*
* Really this is a simple observable stack.
*/
class StackBase : public QObject
{
Q_OBJECT
public:
StackBase() : QObject() {}
void push(Command *c);
bool isEmpty();
Command *top();
void clear();
signals:
void changed();
protected:
/** Protect the pop method so users must call undo/redo to properly
* use the stack, however the subclasses need it to modify the stack.
*/
Command *pop();
Q3PtrStack<Command> mCommandStack;
};
class UndoStack : public StackBase
{
public:
static UndoStack *instance();
void undo();
protected:
UndoStack();
static UndoStack* instance_;
};
class RedoStack : public StackBase
{
public:
static RedoStack *instance();
void redo();
protected:
RedoStack();
static RedoStack* instance_;
};
#endif
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