001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the "License");
007 * you may not use this file except in compliance with the License.
008 * You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 /*
019 * $Id: DTMChildIterNodeList.java 468653 2006-10-28 07:07:05Z minchau $
020 */
021 package org.apache.xml.dtm.ref;
022
023 import org.apache.xml.dtm.DTM;
024 import org.w3c.dom.Node;
025
026 /**
027 * <code>DTMNodeList</code> gives us an implementation of the DOM's
028 * NodeList interface wrapped around a DTM Iterator. The author
029 * considers this something of an abominations, since NodeList was not
030 * intended to be a general purpose "list of nodes" API and is
031 * generally considered by the DOM WG to have be a mistake... but I'm
032 * told that some of the XPath/XSLT folks say they must have this
033 * solution.
034 *
035 * Please note that this is not necessarily equivlaent to a DOM
036 * NodeList operating over the same document. In particular:
037 * <ul>
038 *
039 * <li>If there are several Text nodes in logical succession (ie,
040 * across CDATASection and EntityReference boundaries), we will return
041 * only the first; the caller is responsible for stepping through
042 * them.
043 * (%REVIEW% Provide a convenience routine here to assist, pending
044 * proposed DOM Level 3 getAdjacentText() operation?) </li>
045 *
046 * <li>Since the whole XPath/XSLT architecture assumes that the source
047 * document is not altered while we're working with it, we do not
048 * promise to implement the DOM NodeList's "live view" response to
049 * document mutation. </li>
050 *
051 * </ul>
052 *
053 * <p>State: In progress!!</p>
054 * */
055 public class DTMChildIterNodeList extends DTMNodeListBase {
056 private int m_firstChild;
057 private DTM m_parentDTM;
058
059 //================================================================
060 // Methods unique to this class
061 private DTMChildIterNodeList() {
062 }
063
064 /**
065 * Public constructor: Create a NodeList to support
066 * DTMNodeProxy.getChildren().
067 *
068 * Unfortunately AxisIterators and DTMIterators don't share an API,
069 * so I can't use the existing Axis.CHILD iterator. Rather than
070 * create Yet Another Class, let's set up a special case of this
071 * one.
072 *
073 * @param parentDTM The DTM containing this node
074 * @param parentHandle DTM node-handle integer
075 *
076 */
077 public DTMChildIterNodeList(DTM parentDTM,int parentHandle) {
078 m_parentDTM=parentDTM;
079 m_firstChild=parentDTM.getFirstChild(parentHandle);
080 }
081
082
083 //================================================================
084 // org.w3c.dom.NodeList API follows
085
086 /**
087 * Returns the <code>index</code>th item in the collection. If
088 * <code>index</code> is greater than or equal to the number of nodes in
089 * the list, this returns <code>null</code>.
090 * @param index Index into the collection.
091 * @return The node at the <code>index</code>th position in the
092 * <code>NodeList</code>, or <code>null</code> if that is not a valid
093 * index.
094 */
095 public Node item(int index) {
096 int handle=m_firstChild;
097 while(--index>=0 && handle!=DTM.NULL) {
098 handle=m_parentDTM.getNextSibling(handle);
099 }
100 if (handle == DTM.NULL) {
101 return null;
102 }
103 return m_parentDTM.getNode(handle);
104 }
105
106 /**
107 * The number of nodes in the list. The range of valid child node indices
108 * is 0 to <code>length-1</code> inclusive.
109 */
110 public int getLength() {
111 int count=0;
112 for (int handle=m_firstChild;
113 handle!=DTM.NULL;
114 handle=m_parentDTM.getNextSibling(handle)) {
115 ++count;
116 }
117 return count;
118 }
119 }