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Java > Open Source Codes > org > eclipse > core > commands > operations > UndoContext


1 /*******************************************************************************
2  * Copyright (c) 2005 IBM Corporation and others.
3  * All rights reserved. This program and the accompanying materials
4  * are made available under the terms of the Eclipse Public License v1.0
5  * which accompanies this distribution, and is available at
6  * http://www.eclipse.org/legal/epl-v10.html
7  *
8  * Contributors:
9  * IBM Corporation - initial API and implementation
10  *******************************************************************************/
11 package org.eclipse.core.commands.operations;
12
13 /**
14  * <p>
15  * A simple, lightweight undo context that can be used to tag any operation. It
16  * does not provided a specialized label. This class may be instantiated by
17  * clients. This class may also be subclassed.
18  * </p>
19  *
20  * @since 3.1
21  */
22 public class UndoContext implements IUndoContext {
23
24     /**
25      * <p>
26      * Get the label that describes the undo context. The default implementation
27      * returns the empty String. Subclasses may override.
28      * </p>
29      *
30      * @return the label for the context.
31      */
32     public String JavaDoc getLabel() {
33         return ""; //$NON-NLS-1$
34 }
35
36     /**
37      * <p>
38      * Return whether the specified context is considered a match for the
39      * receiving context. When a context matches another context, operations
40      * that have the context are considered to also have the matching context.
41      * The default implementation checks whether the supplied context is
42      * identical to this context. Subclasses may override.
43      * </p>
44      *
45      * @param context
46      * the context to be checked against the receiving context.
47      *
48      * @return <code>true</code> if the receiving context can be considered a
49      * match for the specified context, and <code>false</code> if it
50      * cannot.
51      */
52     public boolean matches(IUndoContext context) {
53         return context == this;
54     }
55 }
56
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