1 /*
   2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
   3  * @LastModified: Nov 2017
   4  */
   5 /*
   6  * Licensed to the Apache Software Foundation (ASF) under one or more
   7  * contributor license agreements.  See the NOTICE file distributed with
   8  * this work for additional information regarding copyright ownership.
   9  * The ASF licenses this file to You under the Apache License, Version 2.0
  10  * (the "License"); you may not use this file except in compliance with
  11  * the License.  You may obtain a copy of the License at
  12  *
  13  *      http://www.apache.org/licenses/LICENSE-2.0
  14  *
  15  * Unless required by applicable law or agreed to in writing, software
  16  * distributed under the License is distributed on an "AS IS" BASIS,
  17  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  18  * See the License for the specific language governing permissions and
  19  * limitations under the License.
  20  */
  21 
  22 package com.sun.org.apache.xml.internal.dtm.ref;
  23 
  24 import com.sun.org.apache.xml.internal.dtm.DTM;
  25 import com.sun.org.apache.xml.internal.dtm.DTMIterator;
  26 import org.w3c.dom.Node;
  27 
  28 /**
  29  * <code>DTMNodeList</code> gives us an implementation of the DOM's
  30  * NodeList interface wrapped around a DTM Iterator. The author
  31  * considers this something of an abominations, since NodeList was not
  32  * intended to be a general purpose "list of nodes" API and is
  33  * generally considered by the DOM WG to have be a mistake... but I'm
  34  * told that some of the XPath/XSLT folks say they must have this
  35  * solution.
  36  *
  37  * Please note that this is not necessarily equivlaent to a DOM
  38  * NodeList operating over the same document. In particular:
  39  * <ul>
  40  *
  41  * <li>If there are several Text nodes in logical succession (ie,
  42  * across CDATASection and EntityReference boundaries), we will return
  43  * only the first; the caller is responsible for stepping through
  44  * them.
  45  * (%REVIEW% Provide a convenience routine here to assist, pending
  46  * proposed DOM Level 3 getAdjacentText() operation?) </li>
  47  *
  48  * <li>Since the whole XPath/XSLT architecture assumes that the source
  49  * document is not altered while we're working with it, we do not
  50  * promise to implement the DOM NodeList's "live view" response to
  51  * document mutation. </li>
  52  *
  53  * </ul>
  54  *
  55  * <p>State: In progress!!</p>
  56  * */
  57 public class DTMNodeList extends DTMNodeListBase {
  58     private DTMIterator m_iter;
  59 
  60     //================================================================
  61     // Methods unique to this class
  62     private DTMNodeList() {
  63     }
  64 
  65     /**
  66      * Public constructor: Wrap a DTMNodeList around an existing
  67      * and preconfigured DTMIterator
  68      *
  69      * WARNING: THIS HAS THE SIDE EFFECT OF ISSUING setShouldCacheNodes(true)
  70      * AGAINST THE DTMIterator.
  71      *
  72      */
  73     public DTMNodeList(DTMIterator dtmIterator) {
  74         if (dtmIterator != null) {
  75             int pos = dtmIterator.getCurrentPos();
  76             try {
  77                 m_iter = dtmIterator.cloneWithReset();
  78             } catch(CloneNotSupportedException cnse) {
  79                 m_iter = dtmIterator;
  80             }
  81             m_iter.setShouldCacheNodes(true);
  82             m_iter.runTo(-1);
  83             m_iter.setCurrentPos(pos);
  84         }
  85     }
  86 
  87     /**
  88      * Access the wrapped DTMIterator. I'm not sure whether anyone will
  89      * need this or not, but let's write it and think about it.
  90      *
  91      */
  92     public DTMIterator getDTMIterator() {
  93         return m_iter;
  94     }
  95 
  96     //================================================================
  97     // org.w3c.dom.NodeList API follows
  98 
  99     /**
 100      * Returns the <code>index</code>th item in the collection. If
 101      * <code>index</code> is greater than or equal to the number of nodes in
 102      * the list, this returns <code>null</code>.
 103      * @param index Index into the collection.
 104      * @return The node at the <code>index</code>th position in the
 105      *   <code>NodeList</code>, or <code>null</code> if that is not a valid
 106      *   index.
 107      */
 108     public Node item(int index)
 109     {
 110         if (m_iter != null) {
 111             int handle=m_iter.item(index);
 112             if (handle == DTM.NULL) {
 113                 return null;
 114             }
 115             return m_iter.getDTM(handle).getNode(handle);
 116         } else {
 117             return null;
 118         }
 119     }
 120 
 121     /**
 122      * The number of nodes in the list. The range of valid child node indices
 123      * is 0 to <code>length-1</code> inclusive.
 124      */
 125     public int getLength() {
 126         return (m_iter != null) ? m_iter.getLength() : 0;
 127     }
 128 }