1 /*
2 * Copyright (C) 2010, Google Inc.
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 package org.eclipse.jgit.diff;
45
46 /**
47 * Wrap another comparator for use with
48 * {@link org.eclipse.jgit.diff.HashedSequence}.
49 * <p>
50 * This comparator acts as a proxy for the real comparator, evaluating the
51 * cached hash code before testing the underlying comparator's equality.
52 * Comparators of this type must be used with a
53 * {@link org.eclipse.jgit.diff.HashedSequence}.
54 * <p>
55 * To construct an instance of this type use
56 * {@link org.eclipse.jgit.diff.HashedSequencePair}.
57 *
58 * @param <S>
59 * the base sequence type.
60 */
61 public final class HashedSequenceComparator<S extends Sequence> extends
62 SequenceComparator<HashedSequence<S>> {
63 private final SequenceComparator<? super S> cmp;
64
65 HashedSequenceComparator(SequenceComparator<? super S> cmp) {
66 this.cmp = cmp;
67 }
68
69 /** {@inheritDoc} */
70 @Override
71 public boolean equals(HashedSequence<S> a, int ai, //
72 HashedSequence<S> b, int bi) {
73 return a.hashes[ai] == b.hashes[bi]
74 && cmp.equals(a.base, ai, b.base, bi);
75 }
76
77 /** {@inheritDoc} */
78 @Override
79 public int hash(HashedSequence<S> seq, int ptr) {
80 return seq.hashes[ptr];
81 }
82 }