1 /*
2 * Copyright (C) 2008-2009, Google Inc.
3 * Copyright (C) 2007, Robin Rosenberg <robin.rosenberg@dewire.com>
4 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
5 * and other copyright owners as documented in the project's IP log.
6 *
7 * This program and the accompanying materials are made available
8 * under the terms of the Eclipse Distribution License v1.0 which
9 * accompanies this distribution, is reproduced below, and is
10 * available at http://www.eclipse.org/org/documents/edl-v10.php
11 *
12 * All rights reserved.
13 *
14 * Redistribution and use in source and binary forms, with or
15 * without modification, are permitted provided that the following
16 * conditions are met:
17 *
18 * - Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 *
21 * - Redistributions in binary form must reproduce the above
22 * copyright notice, this list of conditions and the following
23 * disclaimer in the documentation and/or other materials provided
24 * with the distribution.
25 *
26 * - Neither the name of the Eclipse Foundation, Inc. nor the
27 * names of its contributors may be used to endorse or promote
28 * products derived from this software without specific prior
29 * written permission.
30 *
31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
32 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
33 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
34 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
36 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
37 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
39 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
40 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
41 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
42 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
43 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
44 */
45
46 package org.eclipse.jgit.treewalk;
47
48 import java.io.IOException;
49
50 import org.eclipse.jgit.errors.CorruptObjectException;
51 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
52 import org.eclipse.jgit.lib.ObjectId;
53 import org.eclipse.jgit.lib.ObjectReader;
54
55 /**
56 * Iterator over an empty tree (a directory with no files).
57 */
58 public class EmptyTreeIterator extends AbstractTreeIterator {
59 /**
60 * Create a new iterator with no parent.
61 */
62 public EmptyTreeIterator() {
63 // Create a root empty tree.
64 }
65
66 EmptyTreeIterator(AbstractTreeIterator p) {
67 super(p);
68 pathLen = pathOffset;
69 }
70
71 /**
72 * Create an iterator for a subtree of an existing iterator.
73 * <p>
74 * The caller is responsible for setting up the path of the child iterator.
75 *
76 * @param p
77 * parent tree iterator.
78 * @param childPath
79 * path array to be used by the child iterator. This path must
80 * contain the path from the top of the walk to the first child
81 * and must end with a '/'.
82 * @param childPathOffset
83 * position within <code>childPath</code> where the child can
84 * insert its data. The value at
85 * <code>childPath[childPathOffset-1]</code> must be '/'.
86 */
87 public EmptyTreeIterator(final AbstractTreeIterator p,
88 final byte[] childPath, final int childPathOffset) {
89 super(p, childPath, childPathOffset);
90 pathLen = childPathOffset - 1;
91 }
92
93 /** {@inheritDoc} */
94 @Override
95 public AbstractTreeIterator createSubtreeIterator(ObjectReader reader)
96 throws IncorrectObjectTypeException, IOException {
97 return new EmptyTreeIterator(this);
98 }
99
100 /** {@inheritDoc} */
101 @Override
102 public boolean hasId() {
103 return false;
104 }
105
106 /** {@inheritDoc} */
107 @Override
108 public ObjectId getEntryObjectId() {
109 return ObjectId.zeroId();
110 }
111
112 /** {@inheritDoc} */
113 @Override
114 public byte[] idBuffer() {
115 return zeroid;
116 }
117
118 /** {@inheritDoc} */
119 @Override
120 public int idOffset() {
121 return 0;
122 }
123
124 /** {@inheritDoc} */
125 @Override
126 public void reset() {
127 // Do nothing.
128 }
129
130 /** {@inheritDoc} */
131 @Override
132 public boolean first() {
133 return true;
134 }
135
136 /** {@inheritDoc} */
137 @Override
138 public boolean eof() {
139 return true;
140 }
141
142 /** {@inheritDoc} */
143 @Override
144 public void next(int delta) throws CorruptObjectException {
145 // Do nothing.
146 }
147
148 /** {@inheritDoc} */
149 @Override
150 public void back(int delta) throws CorruptObjectException {
151 // Do nothing.
152 }
153
154 /** {@inheritDoc} */
155 @Override
156 public void stopWalk() {
157 if (parent != null)
158 parent.stopWalk();
159 }
160
161 /** {@inheritDoc} */
162 @Override
163 protected boolean needsStopWalk() {
164 return parent != null && parent.needsStopWalk();
165 }
166 }