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Java > Open Source Codes > org > objectweb > fractal > gui > undo > model > UndoManager


1 /***
2  * FractalGUI: a graphical tool to edit Fractal component configurations.
3  * Copyright (C) 2003 France Telecom R&D
4  *
5  * This library is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Lesser General Public
7  * License as published by the Free Software Foundation; either
8  * version 2 of the License, or (at your option) any later version.
9  *
10  * This library is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13  * Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public
16  * License along with this library; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18  *
19  * Contact: fractal@objectweb.org
20  *
21  * Authors: Eric Bruneton, Patrice Fauvel
22  */
23
24 package org.objectweb.fractal.gui.undo.model;
25
26 /**
27  * A model for undo and redo.
28  */
29
30 public interface UndoManager {
31
32   /**
33    * Returns <tt>true</tt> if there is something that can be undone.
34    *
35    * @return <tt>true</tt> if there is something that can be undone.
36    */
37
38   boolean canUndo ();
39
40   /**
41    * Undo the last change that was made.
42    */
43
44   void undo ();
45
46   /**
47    * Returns <tt>true</tt> if there is something that can be redone.
48    *
49    * @return <tt>true</tt> if there is something that can be redone.
50    */
51
52   boolean canRedo ();
53
54   /**
55    * Redo the last change that was undone.
56    */
57
58   void redo ();
59
60   /**
61    * Clears the state of this model. After a call to this method, {@link
62    * #canUndo canUndo} and {@link #canRedo canRedo} return <tt>false</tt>.
63    */
64
65   void clear();
66 }
67
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