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 /** Compares two sequences primarily based upon hash codes. */
47 public abstract class LowLevelDiffAlgorithm extends DiffAlgorithm {
48 @Override
49 public <S extends Sequence> EditList diffNonCommon(
50 SequenceComparator<? super S> cmp, S a, S b) {
51 HashedSequencePair<S> p = new HashedSequencePair<S>(cmp, a, b);
52 HashedSequenceComparator<S> hc = p.getComparator();
53 HashedSequence<S> ha = p.getA();
54 HashedSequence<S> hb = p.getB();
55 p = null;
56
57 EditList res = new EditList();
58 Edit region = new Edit(0, a.size(), 0, b.size());
59 diffNonCommon(res, hc, ha, hb, region);
60 return res;
61 }
62
63 /**
64 * Compare two sequences and identify a list of edits between them.
65 *
66 * This method should be invoked only after the two sequences have been
67 * proven to have no common starting or ending elements. The expected
68 * elimination of common starting and ending elements is automatically
69 * performed by the {@link #diff(SequenceComparator, Sequence, Sequence)}
70 * method, which invokes this method using {@link Subsequence}s.
71 *
72 * @param <S>
73 * type of sequence being compared.
74 * @param edits
75 * result list to append the region's edits onto.
76 * @param cmp
77 * the comparator supplying the element equivalence function.
78 * @param a
79 * the first (also known as old or pre-image) sequence. Edits
80 * returned by this algorithm will reference indexes using the
81 * 'A' side: {@link Edit#getBeginA()}, {@link Edit#getEndA()}.
82 * @param b
83 * the second (also known as new or post-image) sequence. Edits
84 * returned by this algorithm will reference indexes using the
85 * 'B' side: {@link Edit#getBeginB()}, {@link Edit#getEndB()}.
86 * @param region
87 * the region being compared within the two sequences.
88 */
89 public abstract <S extends Sequence> void diffNonCommon(EditList edits,
90 HashedSequenceComparator<S> cmp, HashedSequence<S> a,
91 HashedSequence<S> b, Edit region);
92 }