1 /*
2 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package javax.swing.undo;
27
28 import java.io.Serializable;
29 import javax.swing.UIManager;
30
31 /**
32 * An abstract implementation of <code>UndoableEdit</code>,
33 * implementing simple responses to all boolean methods in
34 * that interface.
35 *
36 * @author Ray Ryan
37 */
38 public class AbstractUndoableEdit implements UndoableEdit, Serializable {
39
40 /**
41 * String returned by <code>getUndoPresentationName</code>;
42 * as of Java 2 platform v1.3.1 this field is no longer used. This value
43 * is now localized and comes from the defaults table with key
44 * <code>AbstractUndoableEdit.undoText</code>.
45 *
46 * @see javax.swing.UIDefaults
47 */
48 protected static final String UndoName = "Undo";
49
50 /**
51 * String returned by <code>getRedoPresentationName</code>;
52 * as of Java 2 platform v1.3.1 this field is no longer used. This value
53 * is now localized and comes from the defaults table with key
54 * <code>AbstractUndoableEdit.redoText</code>.
55 *
56 * @see javax.swing.UIDefaults
57 */
58 protected static final String RedoName = "Redo";
59
60 /**
61 * Defaults to true; becomes false if this edit is undone, true
62 * again if it is redone.
63 */
64 boolean hasBeenDone;
65
66 /**
67 * True if this edit has not received <code>die</code>; defaults
68 * to <code>true</code>.
69 */
70 boolean alive;
71
72 /**
73 * Creates an <code>AbstractUndoableEdit</code> which defaults
74 * <code>hasBeenDone</code> and <code>alive</code> to <code>true</code>.
75 */
76 public AbstractUndoableEdit() {
77 super();
78
79 hasBeenDone = true;
80 alive = true;
81 }
82
83 /**
84 * Sets <code>alive</code> to false. Note that this
85 * is a one way operation; dead edits cannot be resurrected.
86 * Sending <code>undo</code> or <code>redo</code> to
87 * a dead edit results in an exception being thrown.
88 *
89 * <p>Typically an edit is killed when it is consolidated by
90 * another edit's <code>addEdit</code> or <code>replaceEdit</code>
91 * method, or when it is dequeued from an <code>UndoManager</code>.
92 */
93 public void die() {
94 alive = false;
95 }
96
97 /**
98 * Throws <code>CannotUndoException</code> if <code>canUndo</code>
99 * returns <code>false</code>. Sets <code>hasBeenDone</code>
100 * to <code>false</code>. Subclasses should override to undo the
101 * operation represented by this edit. Override should begin with
102 * a call to super.
103 *
104 * @exception CannotUndoException if <code>canUndo</code>
105 * returns <code>false</code>
106 * @see #canUndo
107 */
108 public void undo() throws CannotUndoException {
109 if (!canUndo()) {
110 throw new CannotUndoException();
111 }
112 hasBeenDone = false;
113 }
114
115 /**
116 * Returns true if this edit is <code>alive</code>
117 * and <code>hasBeenDone</code> is <code>true</code>.
118 *
119 * @return true if this edit is <code>alive</code>
120 * and <code>hasBeenDone</code> is <code>true</code>
121 *
122 * @see #die
123 * @see #undo
124 * @see #redo
125 */
126 public boolean canUndo() {
127 return alive && hasBeenDone;
128 }
129
130 /**
131 * Throws <code>CannotRedoException</code> if <code>canRedo</code>
132 * returns false. Sets <code>hasBeenDone</code> to <code>true</code>.
133 * Subclasses should override to redo the operation represented by
134 * this edit. Override should begin with a call to super.
135 *
136 * @exception CannotRedoException if <code>canRedo</code>
137 * returns <code>false</code>
138 * @see #canRedo
139 */
140 public void redo() throws CannotRedoException {
141 if (!canRedo()) {
142 throw new CannotRedoException();
143 }
144 hasBeenDone = true;
145 }
146
147 /**
148 * Returns <code>true</code> if this edit is <code>alive</code>
149 * and <code>hasBeenDone</code> is <code>false</code>.
150 *
151 * @return <code>true</code> if this edit is <code>alive</code>
152 * and <code>hasBeenDone</code> is <code>false</code>
153 * @see #die
154 * @see #undo
155 * @see #redo
156 */
157 public boolean canRedo() {
158 return alive && !hasBeenDone;
159 }
160
161 /**
162 * This default implementation returns false.
163 *
164 * @param anEdit the edit to be added
165 * @return false
166 *
167 * @see UndoableEdit#addEdit
168 */
169 public boolean addEdit(UndoableEdit anEdit) {
170 return false;
171 }
172
173 /**
174 * This default implementation returns false.
175 *
176 * @param anEdit the edit to replace
177 * @return false
178 *
179 * @see UndoableEdit#replaceEdit
180 */
181 public boolean replaceEdit(UndoableEdit anEdit) {
182 return false;
183 }
184
185 /**
186 * This default implementation returns true.
187 *
188 * @return true
189 * @see UndoableEdit#isSignificant
190 */
191 public boolean isSignificant() {
192 return true;
193 }
194
195 /**
196 * This default implementation returns "". Used by
197 * <code>getUndoPresentationName</code> and
198 * <code>getRedoPresentationName</code> to
199 * construct the strings they return. Subclasses should override to
200 * return an appropriate description of the operation this edit
201 * represents.
202 *
203 * @return the empty string ""
204 *
205 * @see #getUndoPresentationName
206 * @see #getRedoPresentationName
207 */
208 public String getPresentationName() {
209 return "";
210 }
211
212 /**
213 * Retreives the value from the defaults table with key
214 * <code>AbstractUndoableEdit.undoText</code> and returns
215 * that value followed by a space, followed by
216 * <code>getPresentationName</code>.
217 * If <code>getPresentationName</code> returns "",
218 * then the defaults value is returned alone.
219 *
220 * @return the value from the defaults table with key
221 * <code>AbstractUndoableEdit.undoText</code>, followed
222 * by a space, followed by <code>getPresentationName</code>
223 * unless <code>getPresentationName</code> is "" in which
224 * case, the defaults value is returned alone.
225 * @see #getPresentationName
226 */
227 public String getUndoPresentationName() {
228 String name = getPresentationName();
229 if (!"".equals(name)) {
230 name = UIManager.getString("AbstractUndoableEdit.undoText") +
231 " " + name;
232 } else {
233 name = UIManager.getString("AbstractUndoableEdit.undoText");
234 }
235
236 return name;
237 }
238
239 /**
240 * Retreives the value from the defaults table with key
241 * <code>AbstractUndoableEdit.redoText</code> and returns
242 * that value followed by a space, followed by
243 * <code>getPresentationName</code>.
244 * If <code>getPresentationName</code> returns "",
245 * then the defaults value is returned alone.
246 *
247 * @return the value from the defaults table with key
248 * <code>AbstractUndoableEdit.redoText</code>, followed
249 * by a space, followed by <code>getPresentationName</code>
250 * unless <code>getPresentationName</code> is "" in which
251 * case, the defaults value is returned alone.
252 * @see #getPresentationName
253 */
254 public String getRedoPresentationName() {
255 String name = getPresentationName();
256 if (!"".equals(name)) {
257 name = UIManager.getString("AbstractUndoableEdit.redoText") +
258 " " + name;
259 } else {
260 name = UIManager.getString("AbstractUndoableEdit.redoText");
261 }
262
263 return name;
264 }
265
266 /**
267 * Returns a string that displays and identifies this
268 * object's properties.
269 *
270 * @return a String representation of this object
271 */
272 public String toString()
273 {
274 return super.toString()
275 + " hasBeenDone: " + hasBeenDone
276 + " alive: " + alive;
277 }
278 }
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