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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 <qptrstack.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();
+
+ QPtrStack<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