01: /*******************************************************************************
02: * Copyright (c) 2000, 2005 IBM Corporation and others.
03: * All rights reserved. This program and the accompanying materials
04: * are made available under the terms of the Eclipse Public License v1.0
05: * which accompanies this distribution, and is available at
06: * http://www.eclipse.org/legal/epl-v10.html
07: *
08: * Contributors:
09: * IBM Corporation - initial API and implementation
10: *******************************************************************************/package org.eclipse.ui.internal.texteditor.quickdiff.compare.rangedifferencer;
11:
12: /**
13: * For breaking an object to compare into a sequence of comparable entities.
14: * <p>
15: * It is used by <code>RangeDifferencer</code> to find longest sequences of
16: * matching and non-matching ranges.
17: * <p>
18: * For example, to compare two text documents and find longest common sequences
19: * of matching and non-matching lines, the implementation must break the document
20: * into lines. <code>getRangeCount</code> would return the number of lines in the
21: * document, and <code>rangesEqual</code> would compare a specified line given
22: * with one in another <code>IRangeComparator</code>.
23: * </p>
24: * <p>
25: * Clients should implement this interface; there is no standard implementation.
26: * </p>
27: *
28: * @since 3.0
29: */
30: public interface IRangeComparator {
31:
32: /**
33: * Returns the number of comparable entities.
34: *
35: * @return the number of comparable entities
36: */
37: int getRangeCount();
38:
39: /**
40: * Returns whether the comparable entity given by the first index
41: * matches an entity specified by the other <code>IRangeComparator</code> and index.
42: *
43: * @param thisIndex the index of the comparable entity within this <code>IRangeComparator</code>
44: * @param other the IRangeComparator to compare this with
45: * @param otherIndex the index of the comparable entity within the other <code>IRangeComparator</code>
46: * @return <code>true</code> if the comparable entities are equal
47: */
48: boolean rangesEqual(int this Index, IRangeComparator other,
49: int otherIndex);
50:
51: /**
52: * Returns whether a comparison should be skipped because it would be too costly (or lengthy).
53: *
54: * @param length a number on which to base the decision whether to return
55: * <code>true</code> or <code>false</code>
56: * @param maxLength another number on which to base the decision whether to return
57: * <code>true</code> or <code>false</code>
58: * @param other the other <code>IRangeComparator</code> to compare with
59: * @return <code>true</code> to avoid a too lengthy range comparison
60: */
61: boolean skipRangeComparison(int length, int maxLength,
62: IRangeComparator other);
63: }
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