001/* UndoableEdit.java --
002   Copyright (C) 2002, 2006, Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package javax.swing.undo;
039
040/**
041 * An editing operation that supports undo/redoability.
042 *
043 * @author Andrew Selkirk
044 */
045public interface UndoableEdit
046{
047
048  /**
049   * Incorporates another editing action into this one, thus forming a
050   * combined action.
051   *
052   * @param edit the editing action to be incorporated.
053   *
054   * @return <code>true</code> if the edit was combined successfully, and
055   *         <code>false</code> if it could not be combined.
056   */
057  boolean addEdit(UndoableEdit edit);
058
059  /**
060   * Determines whether it would be possible to redo this editing
061   * action.
062   *
063   * @return <code>true</code> to indicate that this action can be
064   * redone, <code>false</code> otherwise.
065   *
066   * @see #redo()
067   * @see #canUndo()
068   */
069  boolean canRedo();
070
071  /**
072   * Determines whether it would be possible to undo this editing
073   * action.
074   *
075   * @return <code>true</code> to indicate that this action can be
076   * undone, <code>false</code> otherwise.
077   *
078   * @see #undo()
079   * @see #canRedo()
080   */
081  boolean canUndo();
082
083  /**
084   * Informs this edit action that it will no longer be used. Some
085   * actions might use this information to release resources, for
086   * example open files.  Called by {@link UndoManager} before this
087   * action is removed from the edit queue.
088   */
089  void die();
090
091  /**
092   * Returns a human-readable, localized name that describes this
093   * editing action and can be displayed to the user.
094   *
095   * @return The presentation name.
096   */
097  String getPresentationName();
098
099  /**
100   * Returns the redo presentation name.
101   *
102   * @return The redo presentation name.
103   */
104  String getRedoPresentationName();
105
106  /**
107   * Returns the undo presentation name.
108   *
109   * @return The undo presentation name.
110   */
111  String getUndoPresentationName();
112
113  /**
114   * Determines whether this editing action is significant enough for
115   * being seperately undoable by the user. A typical significant
116   * action would be the resizing of an object. However, changing the
117   * selection in a text document would usually not be considered
118   * significant.
119   *
120   * @return <code>true</code> to indicate that the action is
121   * significant enough for being separately undoable, or
122   * <code>false</code> otherwise.
123   */
124  boolean isSignificant();
125
126  /**
127   * Redoes this editing action.
128   *
129   * @throws CannotRedoException if the edit cannot be undone.
130   *
131   * @see #canRedo()
132   * @see #undo()
133   */
134  void redo() throws CannotRedoException;
135
136  /**
137   * Incorporates another editing action into this one, thus forming a
138   * combined action that replaces the argument action.
139   *
140   * @param edit the editing action to be replaced.
141   *
142   * @return <code>true</code> if the edit is successfully replaced, and
143   *         <code>false</code> otherwise.
144   */
145  boolean replaceEdit(UndoableEdit edit);
146
147  /**
148   * Undoes this editing action.
149   *
150   * @throws CannotUndoException if the edit cannot be undone.
151   *
152   * @see #canUndo()
153   * @see #redo()
154   */
155  void undo() throws CannotUndoException;
156
157}