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 java.util.Hashtable;
  import java.util.Vector;
  
  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;
  
  /**
   * This is a table of counters, keyed by ElemNumber objects, each
   * of which has a list of Counter objects.  This really isn't a true
   * table, it is more like a list of lists (there must be a technical
   * term for that...).
   * @xsl.usage internal
   */
  public class CountersTable extends Hashtable
  {
      static final long serialVersionUID = 2159100770924179875L;
  
    /**
     * Construct a CountersTable.
     */
    public CountersTable(){}
  
    /**
     * Get the list of counters that corresponds to
     * the given ElemNumber object.
     *
     * @param numberElem the given xsl:number element.
     *
     * @return the list of counters that corresponds to
     * the given ElemNumber object.
     */
    Vector getCounters(ElemNumber numberElem)
    {
  
      Vector counters = (Vector) this.get(numberElem);
  
      return (null == counters) ? putElemNumber(numberElem) : counters;
    }
  
    /**
     * Put a counter into the table and create an empty
     * vector as it's value.
     *
     * @param numberElem the given xsl:number element.
     *
     * @return an empty vector to be used to store counts
     * for this number element.
     */
    Vector putElemNumber(ElemNumber numberElem)
    {
  
      Vector counters = new Vector();
  
      this.put(numberElem, counters);
  
      return counters;
    }
  
    /**
     * Place to collect new counters.
     */
    transient private NodeSetDTM m_newFound;
  
    /**
     * Add a list of counted nodes that were built in backwards document
     * order, or a list of counted nodes that are in forwards document
     * order.
     *
     * @param flist Vector of nodes built in forwards document order
     * @param blist Vector of nodes built in backwards document order
     */
    void appendBtoFList(NodeSetDTM flist, NodeSetDTM blist)
    {
  
      int n = blist.size();
  
      for (int i = (n - 1); i >= 0; i--)
      {
        flist.addElement(blist.item(i));
      }
    }
  
    // For diagnostics
  
    /** Number of counters created so far          */
    transient int m_countersMade = 0;
  
    /**
     * Count forward until the given node is found, or until
     * we have looked to the given amount.
     *
     * @param support The XPath context to use  
     * @param numberElem The given xsl:number element.
     * @param node The node to count.
     * 
     * @return The node count, or 0 if not found.
     *
     * @throws TransformerException
     */
    public int countNode(XPathContext support, ElemNumber numberElem, int node)
            throws TransformerException
    {
  
      int count = 0;
      Vector counters = getCounters(numberElem);
      int nCounters = counters.size();
  
      // XPath countMatchPattern = numberElem.getCountMatchPattern(support, node);
      // XPath fromMatchPattern = numberElem.m_fromMatchPattern;
      int target = numberElem.getTargetNode(support, node);
  
      if (DTM.NULL != target)
      {
        for (int i = 0; i < nCounters; i++)
        {
          Counter counter = (Counter) counters.elementAt(i);
  
          count = counter.getPreviouslyCounted(support, target);
  
          if (count > 0)
            return count;
        }
  
        // In the loop below, we collect the nodes in backwards doc order, so 
        // we don't have to do inserts, but then we store the nodes in forwards 
        // document order, so we don't have to insert nodes into that list, 
        // so that's what the appendBtoFList stuff is all about.  In cases 
        // of forward counting by one, this will mean a single node copy from 
        // the backwards list (m_newFound) to the forwards list (counter.m_countNodes).
        count = 0;
        if (m_newFound == null)
          m_newFound = new NodeSetDTM(support.getDTMManager());
  
        for (; DTM.NULL != target;
                target = numberElem.getPreviousNode(support, target))
        {
  
          // First time in, we should not have to check for previous counts, 
          // since the original target node was already checked in the 
          // block above.
          if (0 != count)
          {
            for (int i = 0; i < nCounters; i++)
            {
              Counter counter = (Counter) counters.elementAt(i);
              int cacheLen = counter.m_countNodes.size();
  
              if ((cacheLen > 0)
                      && (counter.m_countNodes.elementAt(cacheLen
                                                        - 1) == target))
              {
                count += (cacheLen + counter.m_countNodesStartCount);
  
                if (cacheLen > 0)
                  appendBtoFList(counter.m_countNodes, m_newFound);
  
                m_newFound.removeAllElements();
  
                return count;
              }
            }
          }
  
          m_newFound.addElement(target);
  
          count++;
        }
  
        // If we got to this point, then we didn't find a counter, so make 
        // one and add it to the list.
        Counter counter = new Counter(numberElem, new NodeSetDTM(support.getDTMManager()));
  
        m_countersMade++;  // for diagnostics
  
        appendBtoFList(counter.m_countNodes, m_newFound);
        m_newFound.removeAllElements();
        counters.addElement(counter);
      }
  
      return count;
    }
  }
  