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.functions;
  
  import org.apache.xml.dtm.DTM;
  import org.apache.xml.dtm.DTMIterator;
  import org.apache.xpath.XPathContext;
  import org.apache.xpath.axes.SubContextList;
  import org.apache.xpath.compiler.Compiler;
  import org.apache.xpath.objects.XNumber;
  import org.apache.xpath.objects.XObject;
  
  /**
   * Execute the Position() function.
   * @xsl.usage advanced
   */
  public class FuncPosition extends Function
  {
      static final long serialVersionUID = -9092846348197271582L;
    private boolean m_isTopLevel;
    
    /**
     * Figure out if we're executing a toplevel expression.
     * If so, we can't be inside of a predicate. 
     */
    public void postCompileStep(Compiler compiler)
    {
      m_isTopLevel = compiler.getLocationPathDepth() == -1;
    }
  
    /**
     * Get the position in the current context node list.
     *
     * @param xctxt Runtime XPath context.
     *
     * @return The current position of the itteration in the context node list, 
     *         or -1 if there is no active context node list.
     */
    public int getPositionInContextNodeList(XPathContext xctxt)
    {
  
      // System.out.println("FuncPosition- entry");
      // If we're in a predicate, then this will return non-null.
      SubContextList iter = m_isTopLevel ? null : xctxt.getSubContextList();
  
      if (null != iter)
      {
        int prox = iter.getProximityPosition(xctxt);
   
        // System.out.println("FuncPosition- prox: "+prox);
        return prox;
      }
  
      DTMIterator cnl = xctxt.getContextNodeList();
  
      if (null != cnl)
      {
        int n = cnl.getCurrentNode();
        if(n == DTM.NULL)
        {
          if(cnl.getCurrentPos() == 0)
            return 0;
            
          // Then I think we're in a sort.  See sort21.xsl. So the iterator has 
          // already been spent, and is not on the node we're processing. 
          // It's highly possible that this is an issue for other context-list 
          // functions.  Shouldn't be a problem for last(), and it shouldn't be 
          // a problem for current().
          try 
          { 
            cnl = cnl.cloneWithReset(); 
          }
          catch(CloneNotSupportedException cnse)
          {
            throw new org.apache.xml.utils.WrappedRuntimeException(cnse);
          }
          int currentNode = xctxt.getContextNode();
          // System.out.println("currentNode: "+currentNode);
          while(DTM.NULL != (n = cnl.nextNode()))
          {
            if(n == currentNode)
              break;
          }
        }
        // System.out.println("n: "+n);
        // System.out.println("FuncPosition- cnl.getCurrentPos(): "+cnl.getCurrentPos());
        return cnl.getCurrentPos();
      }
  
      // System.out.println("FuncPosition - out of guesses: -1");
      return -1;
    }
  
    /**
     * Execute the function.  The function must return
     * a valid object.
     * @param xctxt The current execution context.
     * @return A valid XObject.
     *
     * @throws javax.xml.transform.TransformerException
     */
    public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
    {
      double pos = (double) getPositionInContextNodeList(xctxt);
      
      return new XNumber(pos);
    }
    
    /**
     * No arguments to process, so this does nothing.
     */
    public void fixupVariables(java.util.Vector vars, int globalsSize)
    {
      // no-op
    }
  }
  