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: VarNameCollector.java 468643 2006-10-28 06:56:03Z minchau $
020     */
021    package org.apache.xalan.templates;
022    
023    import java.util.Vector;
024    
025    import org.apache.xml.utils.QName;
026    import org.apache.xpath.ExpressionOwner;
027    import org.apache.xpath.XPathVisitor;
028    import org.apache.xpath.operations.Variable;
029    
030    /**
031     * This class visits variable refs in an XPath and collects their QNames.
032     */
033    public class VarNameCollector extends XPathVisitor
034    {
035            Vector m_refs = new Vector();
036            
037            /**
038             * Reset the list for a fresh visitation and collection.
039             */
040            public void reset()
041            {
042                    m_refs.removeAllElements(); //.clear();
043            }
044            
045            /**
046             * Get the number of variable references that were collected.
047             * @return the size of the list.
048             */
049            public int getVarCount()
050            {
051                    return m_refs.size();
052            }
053            
054            /**
055             * Tell if the given qualified name occurs in 
056             * the list of qualified names collected.
057             * 
058             * @param refName Must be a valid qualified name.
059             * @return true if the list contains the qualified name.
060             */
061            boolean doesOccur(QName refName)
062            {
063                    return m_refs.contains(refName);
064            }
065    
066            /**
067             * Visit a variable reference.
068             * @param owner The owner of the expression, to which the expression can 
069             *              be reset if rewriting takes place.
070             * @param var The variable reference object.
071             * @return true if the sub expressions should be traversed.
072             */
073            public boolean visitVariableRef(ExpressionOwner owner, Variable var)
074            {
075                    m_refs.addElement(var.getQName());
076                    return true;
077            }
078    
079    }
080