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Java > Open Source Codes > org > eclipse > compare > contentmergeviewer > ITokenComparator


1 /*******************************************************************************
2  * Copyright (c) 2000, 2006 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.compare.contentmergeviewer;
12
13 import org.eclipse.compare.rangedifferencer.IRangeComparator;
14
15
16 /**
17  * For performing a so-called "token compare" on a line of text.
18  * This interface extends the <code>IRangeComparator</code> interface
19  * so that it can be used by the <code>TextMergeViewer</code>.
20  * <p>
21  * <code>TextMergeViewer</code> activates the token compare when navigating into
22  * a range of differing lines. At first the lines are selected as a block.
23  * When navigating into this block the token compare shows for every line
24  * the differing token by selecting them.
25  * <p>
26  * <code>TextMergeViewer</code>'s default token comparator works on characters separated
27  * by whitespace. If a different strategy is needed (for example, to use Java tokens in
28  * a Java-aware merge viewer), clients may create their own token
29  * comparators by implementing this interface (and overriding the
30  * <code>TextMergeViewer.createTokenComparator</code> factory method).
31  * </p>
32  *
33  * @see TextMergeViewer
34  */
35 public interface ITokenComparator extends IRangeComparator {
36
37     /**
38      * Returns the start character position of the token with the given index.
39      * If the index is out of range (but not negative) the character position
40      * behind the last character (the length of the input string) is returned.
41      *
42      * @param index index of the token for which to return the start position
43      * @return the start position of the token with the given index
44      * @throws java.lang.IndexOutOfBoundsException if index is negative
45      */
46     int getTokenStart(int index);
47
48     /**
49      * Returns the character length of the token with the given index.
50      * If the index is out of range (but not negative) the value 0 is returned.
51      *
52      * @param index index of the token for which to return the start position
53      * @return the character length of the token with the given index
54      * @throws java.lang.IndexOutOfBoundsException if index is negative
55      */
56     int getTokenLength(int index);
57 }
58
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