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: MatchingIterator.java 468651 2006-10-28 07:04:25Z minchau $
020 */
021
022 package org.apache.xalan.xsltc.dom;
023
024 import org.apache.xalan.xsltc.runtime.BasisLibrary;
025 import org.apache.xml.dtm.DTMAxisIterator;
026 import org.apache.xml.dtm.ref.DTMAxisIteratorBase;
027
028 /**
029 * This is a special kind of iterator that takes a source iterator and a
030 * node N. If initialized with a node M (the parent of N) it computes the
031 * position of N amongst the children of M. This position can be obtained
032 * by calling getPosition().
033 * It is an iterator even though next() will never be called. It is used to
034 * match patterns with a single predicate like:
035 *
036 * BOOK[position() = last()]
037 *
038 * In this example, the source iterator will return elements of type BOOK,
039 * a call to position() will return the position of N. Notice that because
040 * of the way the pattern matching is implemented, N will always be a node
041 * in the source since (i) it is a BOOK or the test sequence would not be
042 * considered and (ii) the source iterator is initialized with M which is
043 * the parent of N. Also, and still in this example, a call to last() will
044 * return the number of elements in the source (i.e. the number of BOOKs).
045 * @author Jacek Ambroziak
046 * @author Santiago Pericas-Geertsen
047 */
048 public final class MatchingIterator extends DTMAxisIteratorBase {
049
050 /**
051 * A reference to a source iterator.
052 */
053 private DTMAxisIterator _source;
054
055 /**
056 * The node to match.
057 */
058 private final int _match;
059
060 public MatchingIterator(int match, DTMAxisIterator source) {
061 _source = source;
062 _match = match;
063 }
064
065
066 public void setRestartable(boolean isRestartable) {
067 _isRestartable = isRestartable;
068 _source.setRestartable(isRestartable);
069 }
070
071 public DTMAxisIterator cloneIterator() {
072
073 try {
074 final MatchingIterator clone = (MatchingIterator) super.clone();
075 clone._source = _source.cloneIterator();
076 clone._isRestartable = false;
077 return clone.reset();
078 }
079 catch (CloneNotSupportedException e) {
080 BasisLibrary.runTimeError(BasisLibrary.ITERATOR_CLONE_ERR,
081 e.toString());
082 return null;
083 }
084 }
085
086 public DTMAxisIterator setStartNode(int node) {
087 if (_isRestartable) {
088 // iterator is not a clone
089 _source.setStartNode(node);
090
091 // Calculate the position of the node in the set
092 _position = 1;
093 while ((node = _source.next()) != END && node != _match) {
094 _position++;
095 }
096 }
097 return this;
098 }
099
100 public DTMAxisIterator reset() {
101 _source.reset();
102 return resetPosition();
103 }
104
105 public int next() {
106 return _source.next();
107 }
108
109 public int getLast() {
110 if (_last == -1) {
111 _last = _source.getLast();
112 }
113 return _last;
114 }
115
116 public int getPosition() {
117 return _position;
118 }
119
120 public void setMark() {
121 _source.setMark();
122 }
123
124 public void gotoMark() {
125 _source.gotoMark();
126 }
127 }