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 /** Iterator over an empty tree (a directory with no files). */
56 public class EmptyTreeIterator extends AbstractTreeIterator {
57 /** Create a new iterator with no parent. */
58 public EmptyTreeIterator() {
59 // Create a root empty tree.
60 }
61
62 EmptyTreeIterator(final AbstractTreeIterator p) {
63 super(p);
64 pathLen = pathOffset;
65 }
66
67 /**
68 * Create an iterator for a subtree of an existing iterator.
69 * <p>
70 * The caller is responsible for setting up the path of the child iterator.
71 *
72 * @param p
73 * parent tree iterator.
74 * @param childPath
75 * path array to be used by the child iterator. This path must
76 * contain the path from the top of the walk to the first child
77 * and must end with a '/'.
78 * @param childPathOffset
79 * position within <code>childPath</code> where the child can
80 * insert its data. The value at
81 * <code>childPath[childPathOffset-1]</code> must be '/'.
82 */
83 public EmptyTreeIterator(final AbstractTreeIterator p,
84 final byte[] childPath, final int childPathOffset) {
85 super(p, childPath, childPathOffset);
86 pathLen = childPathOffset - 1;
87 }
88
89 @Override
90 public AbstractTreeIterator createSubtreeIterator(final ObjectReader reader)
91 throws IncorrectObjectTypeException, IOException {
92 return new EmptyTreeIterator(this);
93 }
94
95 @Override
96 public boolean hasId() {
97 return false;
98 }
99
100 @Override
101 public ObjectId getEntryObjectId() {
102 return ObjectId.zeroId();
103 }
104
105 @Override
106 public byte[] idBuffer() {
107 return zeroid;
108 }
109
110 @Override
111 public int idOffset() {
112 return 0;
113 }
114
115 @Override
116 public void reset() {
117 // Do nothing.
118 }
119
120 @Override
121 public boolean first() {
122 return true;
123 }
124
125 @Override
126 public boolean eof() {
127 return true;
128 }
129
130 @Override
131 public void next(final int delta) throws CorruptObjectException {
132 // Do nothing.
133 }
134
135 @Override
136 public void back(final int delta) throws CorruptObjectException {
137 // Do nothing.
138 }
139
140 @Override
141 public void stopWalk() {
142 if (parent != null)
143 parent.stopWalk();
144 }
145 }