1/*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the  "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 *     http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18/*
19 * $Id: DTMNodeList.java 468653 2006-10-28 07:07:05Z minchau $
20 */
21package org.apache.xml.dtm.ref;
22
23import org.apache.xml.dtm.DTM;
24import org.apache.xml.dtm.DTMIterator;
25import org.w3c.dom.Node;
26
27/**
28 * <code>DTMNodeList</code> gives us an implementation of the DOM's
29 * NodeList interface wrapped around a DTM Iterator. The author
30 * considers this something of an abominations, since NodeList was not
31 * intended to be a general purpose "list of nodes" API and is
32 * generally considered by the DOM WG to have be a mistake... but I'm
33 * told that some of the XPath/XSLT folks say they must have this
34 * solution.
35 *
36 * Please note that this is not necessarily equivlaent to a DOM
37 * NodeList operating over the same document. In particular:
38 * <ul>
39 *
40 * <li>If there are several Text nodes in logical succession (ie,
41 * across CDATASection and EntityReference boundaries), we will return
42 * only the first; the caller is responsible for stepping through
43 * them.
44 * (%REVIEW% Provide a convenience routine here to assist, pending
45 * proposed DOM Level 3 getAdjacentText() operation?) </li>
46 *
47 * <li>Since the whole XPath/XSLT architecture assumes that the source
48 * document is not altered while we're working with it, we do not
49 * promise to implement the DOM NodeList's "live view" response to
50 * document mutation. </li>
51 *
52 * </ul>
53 *
54 * <p>State: In progress!!</p>
55 * */
56public class DTMNodeList extends DTMNodeListBase {
57    private DTMIterator m_iter;
58
59    //================================================================
60    // Methods unique to this class
61    private DTMNodeList() {
62    }
63
64    /**
65     * Public constructor: Wrap a DTMNodeList around an existing
66     * and preconfigured DTMIterator
67     *
68     * WARNING: THIS HAS THE SIDE EFFECT OF ISSUING setShouldCacheNodes(true)
69     * AGAINST THE DTMIterator.
70     *
71     */
72    public DTMNodeList(DTMIterator dtmIterator) {
73        if (dtmIterator != null) {
74            int pos = dtmIterator.getCurrentPos();
75            try {
76                m_iter=(DTMIterator)dtmIterator.cloneWithReset();
77            } catch(CloneNotSupportedException cnse) {
78                m_iter = dtmIterator;
79            }
80            m_iter.setShouldCacheNodes(true);
81            m_iter.runTo(-1);
82            m_iter.setCurrentPos(pos);
83        }
84    }
85
86    /**
87     * Access the wrapped DTMIterator. I'm not sure whether anyone will
88     * need this or not, but let's write it and think about it.
89     *
90     */
91    public DTMIterator getDTMIterator() {
92        return m_iter;
93    }
94
95    //================================================================
96    // org.w3c.dom.NodeList API follows
97
98    /**
99     * Returns the <code>index</code>th item in the collection. If
100     * <code>index</code> is greater than or equal to the number of nodes in
101     * the list, this returns <code>null</code>.
102     * @param index Index into the collection.
103     * @return The node at the <code>index</code>th position in the
104     *   <code>NodeList</code>, or <code>null</code> if that is not a valid
105     *   index.
106     */
107    public Node item(int index)
108    {
109        if (m_iter != null) {
110            int handle=m_iter.item(index);
111            if (handle == DTM.NULL) {
112                return null;
113            }
114            return m_iter.getDTM(handle).getNode(handle);
115        } else {
116            return null;
117        }
118    }
119
120    /**
121     * The number of nodes in the list. The range of valid child node indices
122     * is 0 to <code>length-1</code> inclusive.
123     */
124    public int getLength() {
125        return (m_iter != null) ? m_iter.getLength() : 0;
126    }
127}
128