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.xpath.axes;
  
  import org.apache.xpath.Expression;
  import org.apache.xpath.ExpressionOwner;
  import org.apache.xpath.XPathVisitor;
  import org.apache.xpath.functions.FuncLast;
  import org.apache.xpath.functions.FuncPosition;
  import org.apache.xpath.functions.Function;
  import org.apache.xpath.objects.XNumber;
  import org.apache.xpath.operations.Div;
  import org.apache.xpath.operations.Minus;
  import org.apache.xpath.operations.Mod;
  import org.apache.xpath.operations.Mult;
  import org.apache.xpath.operations.Plus;
  import org.apache.xpath.operations.Quo;
  import org.apache.xpath.operations.Variable;
  
  public class HasPositionalPredChecker extends XPathVisitor
  {
  	private boolean m_hasPositionalPred = false;
  	private int m_predDepth = 0;
  	
  	/**
  	 * Process the LocPathIterator to see if it contains variables 
  	 * or functions that may make it context dependent.
  	 * @param path LocPathIterator that is assumed to be absolute, but needs checking.
  	 * @return true if the path is confirmed to be absolute, false if it 
  	 * may contain context dependencies.
  	 */
  	public static boolean check(LocPathIterator path)
  	{
  		HasPositionalPredChecker hppc = new HasPositionalPredChecker();
  		path.callVisitors(null, hppc);
  		return hppc.m_hasPositionalPred;
  	}
  	
  	/**
  	 * Visit a function.
  	 * @param owner The owner of the expression, to which the expression can 
  	 *              be reset if rewriting takes place.
  	 * @param func The function reference object.
  	 * @return true if the sub expressions should be traversed.
  	 */
  	public boolean visitFunction(ExpressionOwner owner, Function func)
  	{
  		if((func instanceof FuncPosition) ||
  		   (func instanceof FuncLast))
  			m_hasPositionalPred = true;
  		return true;
  	}
  	
  //	/**
  //	 * 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_hasPositionalPred = true;
  //		return true;
  //	}
  	
    /**
     * Visit a predicate within a location path.  Note that there isn't a 
     * proper unique component for predicates, and that the expression will 
     * be called also for whatever type Expression is.
     * 
     * @param owner The owner of the expression, to which the expression can 
     *              be reset if rewriting takes place.
     * @param pred The predicate object.
     * @return true if the sub expressions should be traversed.
     */
    public boolean visitPredicate(ExpressionOwner owner, Expression pred)
    {
      m_predDepth++;
  
      if(m_predDepth == 1)
      {
        if((pred instanceof Variable) || 
           (pred instanceof XNumber) ||
           (pred instanceof Div) ||
           (pred instanceof Plus) ||
           (pred instanceof Minus) ||
           (pred instanceof Mod) ||
           (pred instanceof Quo) ||
           (pred instanceof Mult) ||
           (pred instanceof org.apache.xpath.operations.Number) ||
           (pred instanceof Function))
            m_hasPositionalPred = true;
        else
        	pred.callVisitors(owner, this);
      }
  
      m_predDepth--;
  
      // Don't go have the caller go any further down the subtree.
      return false;
    }
  
  
  }
  
  