| /* AbstractUndoableEdit.java -- |
| Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath 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, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
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| exception statement from your version. */ |
| |
| |
| package javax.swing.undo; |
| |
| import java.io.Serializable; |
| |
| import javax.swing.UIManager; |
| |
| /** |
| * A default implementation of <code>UndoableEdit</code> that can be |
| * used as a base for implementing editing operations. |
| * |
| * @author Andrew Selkirk (aselkirk@sympatico.ca) |
| * @author Sascha Brawer (brawer@dandelis.ch) |
| */ |
| public class AbstractUndoableEdit |
| implements UndoableEdit, Serializable |
| { |
| /** |
| * The serialization ID. Verified using the <code>serialver</code> |
| * tool of Apple/Sun JDK 1.3.1 on MacOS X 10.1.5, and Sun JDK |
| * 1.4.1_01 on GNU/Linux. |
| */ |
| static final long serialVersionUID = 580150227676302096L; |
| |
| |
| /** |
| * The constant string “Undo”, which was returned by |
| * {@link #getUndoPresentationName()} on early versions of the |
| * platform. However, this field has become obsolete with version |
| * 1.3.1. That method now retrieves a localized string from the |
| * {@link javax.swing.UIManager}, using the key |
| * <code>“AbstractUndoableEdit.undoText”</code>. |
| */ |
| protected static final String UndoName = "Undo"; |
| |
| |
| /** |
| * The constant string “Redo”, which was returned by |
| * {@link #getRedoPresentationName()} on early versions of the |
| * platform. However, this field has become obsolete with version |
| * 1.3.1. That method now retrieves a localized string from the |
| * {@link javax.swing.UIManager}, using the key |
| * <code>“AbstractUndoableEdit.redoText”</code>. |
| */ |
| protected static final String RedoName = "Redo"; |
| |
| |
| /** |
| * Indicates whether this editing action has been executed. A value |
| * of <code>true</code> means that the action was performed, or that |
| * a redo operation was successful. A value of <code>false</code> |
| * means that the action has not yet performed, or that an undo |
| * operation was successful. |
| */ |
| private boolean hasBeenDone; |
| |
| |
| /** |
| * Indicates whether this editing action is still alive. The value |
| * is set to <code>true</code> by the constructor, and to |
| * <code>false</code> by the {@link #die()} method. |
| */ |
| private boolean alive; |
| |
| |
| /** |
| * Constructs a new <code>AbstractUndoableEdit</code>. The initial |
| * state is that the editing action is alive, and |
| * <code>hasBeenDone</code> is <code>true</code>. |
| */ |
| public AbstractUndoableEdit() |
| { |
| // The API specification is not clear, but Mauve test code has |
| // determined that hasBeenDone is initially set to true. |
| alive = hasBeenDone = true; |
| } |
| |
| |
| /** |
| * Undoes this editing action. |
| * |
| * @throws CannotUndoException if {@link #canUndo()} returns |
| * <code>false</code>, for example because this action has already |
| * been undone. |
| * |
| * @see #canUndo() |
| * @see #redo() |
| */ |
| public void undo() |
| throws CannotUndoException |
| { |
| if (!canUndo()) |
| throw new CannotUndoException(); |
| hasBeenDone = false; |
| } |
| |
| |
| /** |
| * Determines whether it would be possible to undo this editing |
| * action. |
| * |
| * @return <code>true</code> to indicate that this action can be |
| * undone, <code>false</code> otherwise. |
| * |
| * @see #undo() |
| * @see #canRedo() |
| */ |
| public boolean canUndo() |
| { |
| return alive && hasBeenDone; |
| } |
| |
| |
| /** |
| * Redoes this editing action. |
| * |
| * @throws CannotRedoException if {@link #canRedo()} returns |
| * <code>false</code>, for example because this action has not |
| * yet been undone. |
| * |
| * @see #canRedo() |
| * @see #undo() |
| */ |
| public void redo() |
| throws CannotRedoException |
| { |
| if (!canRedo()) |
| throw new CannotRedoException(); |
| hasBeenDone = true; |
| } |
| |
| |
| /** |
| * Determines whether it would be possible to redo this editing |
| * action. |
| * |
| * @return <code>true</code> to indicate that this action can be |
| * redone, <code>false</code> otherwise. |
| * |
| * @see #redo() |
| * @see #canUndo() |
| */ |
| public boolean canRedo() |
| { |
| return alive && !hasBeenDone; |
| } |
| |
| |
| /** |
| * Informs this edit action that it will no longer be used. Some |
| * actions might use this information to release resources, for |
| * example open files. Called by {@link UndoManager} before this |
| * action is removed from the edit queue. |
| */ |
| public void die() |
| { |
| alive = false; |
| } |
| |
| |
| /** |
| * Incorporates another editing action into this one, thus forming a |
| * combined action. |
| * |
| * <p>The default implementation always returns <code>false</code>, |
| * indicating that the editing action could not be incorporated. |
| * |
| * @param edit the editing action to be incorporated. |
| */ |
| public boolean addEdit(UndoableEdit edit) |
| { |
| return false; |
| } |
| |
| |
| /** |
| * Incorporates another editing action into this one, thus forming a |
| * combined action that replaces the argument action. |
| * |
| * <p>The default implementation always returns <code>false</code>, |
| * indicating that the argument action should not be replaced. |
| * |
| * @param edit the editing action to be replaced. |
| */ |
| public boolean replaceEdit(UndoableEdit edit) |
| { |
| return false; |
| } |
| |
| |
| /** |
| * Determines whether this editing action is significant enough for |
| * being seperately undoable by the user. A typical significant |
| * action would be the resizing of an object. However, changing the |
| * selection in a text document would usually not be considered |
| * significant. |
| * |
| * <p>The default implementation returns <code>true</code>. |
| * |
| * @return <code>true</code> to indicate that the action is |
| * significant enough for being separately undoable, or |
| * <code>false</code> otherwise. |
| */ |
| public boolean isSignificant() |
| { |
| return true; |
| } |
| |
| |
| /** |
| * Returns a human-readable, localized name that describes this |
| * editing action and can be displayed to the user. |
| * |
| * <p>The default implementation returns an empty string. |
| */ |
| public String getPresentationName() |
| { |
| return ""; |
| } |
| |
| |
| /** |
| * Calculates a localized name for presenting the undo action to the |
| * user. |
| * |
| * <p>The default implementation returns the concatenation of the |
| * string “Undo” and the action name, which is |
| * determined by calling {@link #getPresentationName()}. |
| * |
| * <p>The string “Undo” is retrieved from the {@link |
| * javax.swing.UIManager}, using the key |
| * <code>“AbstractUndoableEdit.undoText”</code>. This |
| * allows the text to be localized. |
| */ |
| public String getUndoPresentationName() |
| { |
| String msg, pres; |
| |
| msg = UIManager.getString("AbstractUndoableEdit.undoText"); |
| if (msg == null) |
| msg = UndoName; |
| |
| pres = getPresentationName(); |
| if ((pres == null) || (pres.length() == 0)) |
| return msg; |
| else |
| return msg + ' ' + pres; |
| } |
| |
| |
| /** |
| * Calculates a localized name for presenting the redo action to the |
| * user. |
| * |
| * <p>The default implementation returns the concatenation of the |
| * string “Redo” and the action name, which is |
| * determined by calling {@link #getPresentationName()}. |
| * |
| * <p>The string “Redo” is retrieved from the {@link |
| * javax.swing.UIManager}, using the key |
| * <code>“AbstractUndoableEdit.redoText”</code>. This |
| * allows the text to be localized. |
| */ |
| public String getRedoPresentationName() |
| { |
| String msg, pres; |
| |
| msg = UIManager.getString("AbstractUndoableEdit.redoText"); |
| if (msg == null) |
| msg = RedoName; |
| |
| pres = getPresentationName(); |
| if ((pres == null) || (pres.length() == 0)) |
| return msg; |
| else |
| return msg + ' ' + pres; |
| } |
| |
| |
| public String toString() |
| { |
| return super.toString() |
| + " hasBeenDone: " + hasBeenDone |
| + " alive: " + alive; |
| } |
| } |