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: UnionChildIterator.java 468655 2006-10-28 07:12:06Z minchau $
020 */
021 package org.apache.xpath.axes;
022
023 import org.apache.xml.dtm.DTMIterator;
024 import org.apache.xpath.XPathContext;
025 import org.apache.xpath.objects.XObject;
026 import org.apache.xpath.patterns.NodeTest;
027
028 /**
029 * This class defines a simplified type of union iterator that only
030 * tests along the child axes. If the conditions are right, it is
031 * much faster than using a UnionPathIterator.
032 */
033 public class UnionChildIterator extends ChildTestIterator
034 {
035 static final long serialVersionUID = 3500298482193003495L;
036 /**
037 * Even though these may hold full LocPathIterators, this array does
038 * not have to be cloned, since only the node test and predicate
039 * portion are used, and these only need static information. However,
040 * also note that index predicates can not be used!
041 */
042 private PredicatedNodeTest[] m_nodeTests = null;
043
044 /**
045 * Constructor for UnionChildIterator
046 */
047 public UnionChildIterator()
048 {
049 super(null);
050 }
051
052 /**
053 * Add a node test to the union list.
054 *
055 * @param test reference to a NodeTest, which will be added
056 * directly to the list of node tests (in other words, it will
057 * not be cloned). The parent of this test will be set to
058 * this object.
059 */
060 public void addNodeTest(PredicatedNodeTest test)
061 {
062
063 // Increase array size by only 1 at a time. Fix this
064 // if it looks to be a problem.
065 if (null == m_nodeTests)
066 {
067 m_nodeTests = new PredicatedNodeTest[1];
068 m_nodeTests[0] = test;
069 }
070 else
071 {
072 PredicatedNodeTest[] tests = m_nodeTests;
073 int len = m_nodeTests.length;
074
075 m_nodeTests = new PredicatedNodeTest[len + 1];
076
077 System.arraycopy(tests, 0, m_nodeTests, 0, len);
078
079 m_nodeTests[len] = test;
080 }
081 test.exprSetParent(this);
082 }
083
084 /**
085 * This function is used to fixup variables from QNames to stack frame
086 * indexes at stylesheet build time.
087 * @param vars List of QNames that correspond to variables. This list
088 * should be searched backwards for the first qualified name that
089 * corresponds to the variable reference qname. The position of the
090 * QName in the vector from the start of the vector will be its position
091 * in the stack frame (but variables above the globalsTop value will need
092 * to be offset to the current stack frame).
093 */
094 public void fixupVariables(java.util.Vector vars, int globalsSize)
095 {
096 super.fixupVariables(vars, globalsSize);
097 if (m_nodeTests != null) {
098 for (int i = 0; i < m_nodeTests.length; i++) {
099 m_nodeTests[i].fixupVariables(vars, globalsSize);
100 }
101 }
102 }
103
104 /**
105 * Test whether a specified node is visible in the logical view of a
106 * TreeWalker or NodeIterator. This function will be called by the
107 * implementation of TreeWalker and NodeIterator; it is not intended to
108 * be called directly from user code.
109 * @param n The node to check to see if it passes the filter or not.
110 * @return a constant to determine whether the node is accepted,
111 * rejected, or skipped, as defined above .
112 */
113 public short acceptNode(int n)
114 {
115 XPathContext xctxt = getXPathContext();
116 try
117 {
118 xctxt.pushCurrentNode(n);
119 for (int i = 0; i < m_nodeTests.length; i++)
120 {
121 PredicatedNodeTest pnt = m_nodeTests[i];
122 XObject score = pnt.execute(xctxt, n);
123 if (score != NodeTest.SCORE_NONE)
124 {
125 // Note that we are assuming there are no positional predicates!
126 if (pnt.getPredicateCount() > 0)
127 {
128 if (pnt.executePredicates(n, xctxt))
129 return DTMIterator.FILTER_ACCEPT;
130 }
131 else
132 return DTMIterator.FILTER_ACCEPT;
133
134 }
135 }
136 }
137 catch (javax.xml.transform.TransformerException se)
138 {
139
140 // TODO: Fix this.
141 throw new RuntimeException(se.getMessage());
142 }
143 finally
144 {
145 xctxt.popCurrentNode();
146 }
147 return DTMIterator.FILTER_SKIP;
148 }
149
150 }