1 /*
2 * Copyright (C) 2010, Google Inc. and others
3 *
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Distribution License v. 1.0 which is available at
6 * https://www.eclipse.org/org/documents/edl-v10.php.
7 *
8 * SPDX-License-Identifier: BSD-3-Clause
9 */
10
11 package org.eclipse.jgit.diff;
12
13 /**
14 * Compares two sequences primarily based upon hash codes.
15 */
16 public abstract class LowLevelDiffAlgorithm extends DiffAlgorithm {
17 /** {@inheritDoc} */
18 @Override
19 public <S extends Sequence> EditList diffNonCommon(
20 SequenceComparator<? super S> cmp, S a, S b) {
21 HashedSequencePair<S> p = new HashedSequencePair<>(cmp, a, b);
22 HashedSequenceComparator<S> hc = p.getComparator();
23 HashedSequence<S> ha = p.getA();
24 HashedSequence<S> hb = p.getB();
25 p = null;
26
27 EditList res = new EditList();
28 Edit region = new Edit(0, a.size(), 0, b.size());
29 diffNonCommon(res, hc, ha, hb, region);
30 return res;
31 }
32
33 /**
34 * Compare two sequences and identify a list of edits between them.
35 *
36 * This method should be invoked only after the two sequences have been
37 * proven to have no common starting or ending elements. The expected
38 * elimination of common starting and ending elements is automatically
39 * performed by the {@link #diff(SequenceComparator, Sequence, Sequence)}
40 * method, which invokes this method using
41 * {@link org.eclipse.jgit.diff.Subsequence}s.
42 *
43 * @param edits
44 * result list to append the region's edits onto.
45 * @param cmp
46 * the comparator supplying the element equivalence function.
47 * @param a
48 * the first (also known as old or pre-image) sequence. Edits
49 * returned by this algorithm will reference indexes using the
50 * 'A' side: {@link org.eclipse.jgit.diff.Edit#getBeginA()},
51 * {@link org.eclipse.jgit.diff.Edit#getEndA()}.
52 * @param b
53 * the second (also known as new or post-image) sequence. Edits
54 * returned by this algorithm will reference indexes using the
55 * 'B' side: {@link org.eclipse.jgit.diff.Edit#getBeginB()},
56 * {@link org.eclipse.jgit.diff.Edit#getEndB()}.
57 * @param region
58 * the region being compared within the two sequences.
59 */
60 public abstract <S extends Sequence> void diffNonCommon(EditList edits,
61 HashedSequenceComparator<S> cmp, HashedSequence<S> a,
62 HashedSequence<S> b, Edit region);
63 }