1 /*
2 * Copyright (C) 2008-2009, Google Inc.
3 * Copyright (C) 2009, Robin Rosenberg <robin.rosenberg@dewire.com>
4 * and other copyright owners as documented in the project's IP log.
5 *
6 * This program and the accompanying materials are made available
7 * under the terms of the Eclipse Distribution License v1.0 which
8 * accompanies this distribution, is reproduced below, and is
9 * available at http://www.eclipse.org/org/documents/edl-v10.php
10 *
11 * All rights reserved.
12 *
13 * Redistribution and use in source and binary forms, with or
14 * without modification, are permitted provided that the following
15 * conditions are met:
16 *
17 * - Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 *
20 * - Redistributions in binary form must reproduce the above
21 * copyright notice, this list of conditions and the following
22 * disclaimer in the documentation and/or other materials provided
23 * with the distribution.
24 *
25 * - Neither the name of the Eclipse Foundation, Inc. nor the
26 * names of its contributors may be used to endorse or promote
27 * products derived from this software without specific prior
28 * written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
31 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
32 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
33 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
34 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
35 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
36 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
37 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
38 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
39 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
40 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
41 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
42 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
43 */
44
45 package org.eclipse.jgit.merge;
46
47 import java.io.IOException;
48
49 import org.eclipse.jgit.lib.Config;
50 import org.eclipse.jgit.lib.ObjectId;
51 import org.eclipse.jgit.lib.ObjectInserter;
52 import org.eclipse.jgit.lib.Repository;
53
54 /**
55 * Trivial merge strategy to make the resulting tree exactly match an input.
56 * <p>
57 * This strategy can be used to cauterize an entire side branch of history, by
58 * setting the output tree to one of the inputs, and ignoring any of the paths
59 * of the other inputs.
60 */
61 public class StrategyOneSided extends MergeStrategy {
62 private final String strategyName;
63
64 private final int treeIndex;
65
66 /**
67 * Create a new merge strategy to select a specific input tree.
68 *
69 * @param name
70 * name of this strategy.
71 * @param index
72 * the position of the input tree to accept as the result.
73 */
74 protected StrategyOneSided(final String name, final int index) {
75 strategyName = name;
76 treeIndex = index;
77 }
78
79 @Override
80 public String getName() {
81 return strategyName;
82 }
83
84 @Override
85 public Merger newMerger(final Repository db) {
86 return new OneSide(db, treeIndex);
87 }
88
89 @Override
90 public Merger newMerger(final Repository db, boolean inCore) {
91 return new OneSide(db, treeIndex);
92 }
93
94 @Override
95 public Merger newMerger(final ObjectInserter inserter, final Config config) {
96 return new OneSide(inserter, treeIndex);
97 }
98
99 static class OneSide extends Merger {
100 private final int treeIndex;
101
102 protected OneSide(final Repository local, final int index) {
103 super(local);
104 treeIndex = index;
105 }
106
107 protected OneSide(final ObjectInserter inserter, final int index) {
108 super(inserter);
109 treeIndex = index;
110 }
111
112 @Override
113 protected boolean mergeImpl() throws IOException {
114 return treeIndex < sourceTrees.length;
115 }
116
117 @Override
118 public ObjectId getResultTreeId() {
119 return sourceTrees[treeIndex];
120 }
121
122 @Override
123 public ObjectId getBaseCommitId() {
124 return null;
125 }
126 }
127 }