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


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  * An undo context is used to "tag" operations as being applicable to a certain
16  * context. The undo context is used to filter the history of operations
17  * available for undo or redo so that only operations appropriate for a given
18  * undo context are shown when the application is presenting that context.
19  * </p>
20  * <p>
21  * The scope of an undo context is defined by the application that is making
22  * undo and redo of operations available. Undo contexts may be related to
23  * application models, or may be associated with UI objects that are providing
24  * undo and redo support.
25  * </p>
26  * <p>
27  * An undo context may be defined as "matching" another context. This allows
28  * applications to provide specialized implementations of an undo context that
29  * will appear in the operation history for their matching context.
30  *
31  * @since 3.1
32  */
33
34 public interface IUndoContext {
35
36     /**
37      * Get the label that describes the undo context.
38      *
39      * @return the label for the context.
40      */
41     public String JavaDoc getLabel();
42
43     /**
44      * Return whether the specified context is considered a match for the
45      * receiving context. When a context matches another context, operations
46      * that have the context are considered to also have the matching context.
47      *
48      * @param context
49      * the context to be checked against the receiving context.
50      *
51      * @return <code>true</code> if the receiving context can be considered a
52      * match for the specified context, and <code>false</code> if it
53      * cannot.
54      */
55     public boolean matches(IUndoContext context);
56
57 }
58
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