code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the  "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * $Id$
   */
  package org.apache.xalan.templates;
  
  import java.util.Vector;
  
  import org.apache.xml.utils.QName;
  import org.apache.xpath.ExpressionOwner;
  import org.apache.xpath.XPathVisitor;
  import org.apache.xpath.operations.Variable;
  
  /**
   * This class visits variable refs in an XPath and collects their QNames.
   */
  public class VarNameCollector extends XPathVisitor
  {
  	Vector m_refs = new Vector();
  	
  	/**
  	 * Reset the list for a fresh visitation and collection.
  	 */
  	public void reset()
  	{
  		m_refs.removeAllElements(); //.clear();
  	}
  	
  	/**
  	 * Get the number of variable references that were collected.
  	 * @return the size of the list.
  	 */
  	public int getVarCount()
  	{
  		return m_refs.size();
  	}
  	
  	/**
  	 * Tell if the given qualified name occurs in 
  	 * the list of qualified names collected.
  	 * 
  	 * @param refName Must be a valid qualified name.
  	 * @return true if the list contains the qualified name.
  	 */
  	boolean doesOccur(QName refName)
  	{
  		return m_refs.contains(refName);
  	}
  
  	/**
  	 * Visit a variable reference.
  	 * @param owner The owner of the expression, to which the expression can 
  	 *              be reset if rewriting takes place.
  	 * @param var The variable reference object.
  	 * @return true if the sub expressions should be traversed.
  	 */
  	public boolean visitVariableRef(ExpressionOwner owner, Variable var)
  	{
  		m_refs.addElement(var.getQName());
  		return true;
  	}
  
  }
  
  