org.spearce.jgit/src/org/spearce/jgit/treewalk/EmptyTreeIterator.java

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