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: StepIterator.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 * A step iterator is used to evaluate expressions like "BOOK/TITLE".
030 * A better name for this iterator would have been ParentIterator since
031 * both "BOOK" and "TITLE" are steps in XPath lingo. Step iterators are
032 * constructed from two other iterators which we are going to refer to
033 * as "outer" and "inner". Every node from the outer iterator (the one
034 * for BOOK in our example) is used to initialize the inner iterator.
035 * After this initialization, every node from the inner iterator is
036 * returned (in essence, implementing a "nested loop").
037 * @author Jacek Ambroziak
038 * @author Santiago Pericas-Geertsen
039 * @author Erwin Bolwidt <ejb@klomp.org>
040 * @author Morten Jorgensen
041 */
042 public class StepIterator extends DTMAxisIteratorBase {
043
044 /**
045 * A reference to the "outer" iterator.
046 */
047 protected DTMAxisIterator _source;
048
049 /**
050 * A reference to the "inner" iterator.
051 */
052 protected DTMAxisIterator _iterator;
053
054 /**
055 * Temp variable to store a marked position.
056 */
057 private int _pos = -1;
058
059 public StepIterator(DTMAxisIterator source, DTMAxisIterator iterator) {
060 _source = source;
061 _iterator = iterator;
062 // System.out.println("SI source = " + source + " this = " + this);
063 // System.out.println("SI iterator = " + iterator + " this = " + this);
064 }
065
066
067 public void setRestartable(boolean isRestartable) {
068 _isRestartable = isRestartable;
069 _source.setRestartable(isRestartable);
070 _iterator.setRestartable(true); // must be restartable
071 }
072
073 public DTMAxisIterator cloneIterator() {
074 _isRestartable = false;
075 try {
076 final StepIterator clone = (StepIterator) super.clone();
077 clone._source = _source.cloneIterator();
078 clone._iterator = _iterator.cloneIterator();
079 clone._iterator.setRestartable(true); // must be restartable
080 clone._isRestartable = false;
081 return clone.reset();
082 }
083 catch (CloneNotSupportedException e) {
084 BasisLibrary.runTimeError(BasisLibrary.ITERATOR_CLONE_ERR,
085 e.toString());
086 return null;
087 }
088 }
089
090 public DTMAxisIterator setStartNode(int node) {
091 if (_isRestartable) {
092 // Set start node for left-hand iterator...
093 _source.setStartNode(_startNode = node);
094
095 // ... and get start node for right-hand iterator from left-hand,
096 // with special case for //* path - see ParentLocationPath
097 _iterator.setStartNode(_includeSelf ? _startNode : _source.next());
098 return resetPosition();
099 }
100 return this;
101 }
102
103 public DTMAxisIterator reset() {
104 _source.reset();
105 // Special case for //* path - see ParentLocationPath
106 _iterator.setStartNode(_includeSelf ? _startNode : _source.next());
107 return resetPosition();
108 }
109
110 public int next() {
111 for (int node;;) {
112 // Try to get another node from the right-hand iterator
113 if ((node = _iterator.next()) != END) {
114 return returnNode(node);
115 }
116 // If not, get the next starting point from left-hand iterator...
117 else if ((node = _source.next()) == END) {
118 return END;
119 }
120 // ...and pass it on to the right-hand iterator
121 else {
122 _iterator.setStartNode(node);
123 }
124 }
125 }
126
127 public void setMark() {
128 _source.setMark();
129 _iterator.setMark();
130 //_pos = _position;
131 }
132
133 public void gotoMark() {
134 _source.gotoMark();
135 _iterator.gotoMark();
136 //_position = _pos;
137 }
138 }