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.transformer;
  
  import javax.xml.transform.TransformerException;
  
  import org.apache.xalan.templates.ElemNumber;
  import org.apache.xml.dtm.DTM;
  import org.apache.xpath.NodeSetDTM;
  import org.apache.xpath.XPathContext;
  
  /**
   * A class that does incremental counting for support of xsl:number.
   * This class stores a cache of counted nodes (m_countNodes).
   * It tries to cache the counted nodes in document order...
   * the node count is based on its position in the cache list
   * @xsl.usage internal
   */
  public class Counter
  {
  
    /**
     * Set the maximum ammount the m_countNodes list can
     * grow to.
     */
    static final int MAXCOUNTNODES = 500;
  
    /**
     * The start count from where m_countNodes counts
     * from.  In other words, the count of a given node
     * in the m_countNodes vector is node position +
     * m_countNodesStartCount.
     */
    int m_countNodesStartCount = 0;
  
    /**
     * A vector of all nodes counted so far.
     */
    NodeSetDTM m_countNodes;
  
    /**
     * The node from where the counting starts.  This is needed to
     * find a counter if the node being counted is not immediatly
     * found in the m_countNodes vector.
     */
    int m_fromNode = DTM.NULL;
  
    /**
     * The owning xsl:number element.
     */
    ElemNumber m_numberElem;
  
    /**
     * Value to store result of last getCount call, for benifit
     * of returning val from CountersTable.getCounterByCounted,
     * who calls getCount.
     */
    int m_countResult;
  
    /**
     * Construct a counter object.
     *
     * @param numberElem The owning xsl:number element. 
     * @param countNodes A vector of all nodes counted so far.
     *
     * @throws TransformerException
     */
    Counter(ElemNumber numberElem, NodeSetDTM countNodes) throws TransformerException
    {
      m_countNodes = countNodes;
      m_numberElem = numberElem;
    }
  
    /**
     * Construct a counter object.
     *
     * @param numberElem The owning xsl:number element. 
     *
     * @throws TransformerException
     *
    Counter(ElemNumber numberElem) throws TransformerException
    {
      m_numberElem = numberElem;
    }*/
  
    /**
     * Try and find a node that was previously counted. If found,
     * return a positive integer that corresponds to the count.
     *
     * @param support The XPath context to use
     * @param node The node to be counted.
     * 
     * @return The count of the node, or -1 if not found.
     */
    int getPreviouslyCounted(XPathContext support, int node)
    {
  
      int n = m_countNodes.size();
  
      m_countResult = 0;
  
      for (int i = n - 1; i >= 0; i--)
      {
        int countedNode = m_countNodes.elementAt(i);
  
        if (node == countedNode)
        {
  
          // Since the list is in backwards order, the count is 
          // how many are in the rest of the list.
          m_countResult = i + 1 + m_countNodesStartCount;
  
          break;
        }
        
        DTM dtm = support.getDTM(countedNode);
  
        // Try to see if the given node falls after the counted node...
        // if it does, don't keep searching backwards.
        if (dtm.isNodeAfter(countedNode, node))
          break;
      }
  
      return m_countResult;
    }
  
    /**
     * Get the last node in the list.
     *
     * @return the last node in the list.
     */
    int getLast()
    {
  
      int size = m_countNodes.size();
  
      return (size > 0) ? m_countNodes.elementAt(size - 1) : DTM.NULL;
    }
  }
  