1 /*
2 * Copyright (C) 2009, Google Inc.
3 * Copyright (C) 2012, Research In Motion Limited
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.errors.IncorrectObjectTypeException;
50 import org.eclipse.jgit.errors.MissingObjectException;
51 import org.eclipse.jgit.lib.AnyObjectId;
52 import org.eclipse.jgit.lib.ObjectId;
53 import org.eclipse.jgit.lib.Repository;
54 import org.eclipse.jgit.revwalk.RevCommit;
55 import org.eclipse.jgit.revwalk.RevTree;
56 import org.eclipse.jgit.treewalk.AbstractTreeIterator;
57 import org.eclipse.jgit.treewalk.EmptyTreeIterator;
58
59 /** A merge of 2 trees, using a common base ancestor tree. */
60 public abstract class ThreeWayMerger extends Merger {
61 private RevTree baseTree;
62
63 private ObjectId baseCommitId;
64
65 /**
66 * Create a new merge instance for a repository.
67 *
68 * @param local
69 * the repository this merger will read and write data on.
70 */
71 protected ThreeWayMerger(final Repository local) {
72 super(local);
73 }
74
75 /**
76 * Create a new merge instance for a repository.
77 *
78 * @param local
79 * the repository this merger will read and write data on.
80 * @param inCore
81 * perform the merge in core with no working folder involved
82 */
83 protected ThreeWayMerger(final Repository local, boolean inCore) {
84 this(local);
85 }
86
87 /**
88 * Set the common ancestor tree.
89 *
90 * @param id
91 * common base treeish; null to automatically compute the common
92 * base from the input commits during
93 * {@link #merge(AnyObjectId...)}.
94 * @throws IncorrectObjectTypeException
95 * the object is not a treeish.
96 * @throws MissingObjectException
97 * the object does not exist.
98 * @throws IOException
99 * the object could not be read.
100 */
101 public void setBase(final AnyObjectId id) throws MissingObjectException,
102 IncorrectObjectTypeException, IOException {
103 if (id != null) {
104 baseTree = walk.parseTree(id);
105 } else {
106 baseTree = null;
107 }
108 }
109
110 @Override
111 public boolean merge(final AnyObjectId... tips) throws IOException {
112 if (tips.length != 2)
113 return false;
114 return super.merge(tips);
115 }
116
117 @Override
118 public ObjectId getBaseCommitId() {
119 return baseCommitId;
120 }
121
122 /**
123 * Create an iterator to walk the merge base.
124 *
125 * @return an iterator over the caller-specified merge base, or the natural
126 * merge base of the two input commits.
127 * @throws IOException
128 */
129 protected AbstractTreeIterator mergeBase() throws IOException {
130 if (baseTree != null)
131 return openTree(baseTree);
132 RevCommit baseCommit = (baseCommitId != null) ? walk
133 .parseCommit(baseCommitId) : getBaseCommit(sourceCommits[0],
134 sourceCommits[1]);
135 if (baseCommit == null) {
136 baseCommitId = null;
137 return new EmptyTreeIterator();
138 } else {
139 baseCommitId = baseCommit.toObjectId();
140 return openTree(baseCommit.getTree());
141 }
142 }
143 }