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.Vector;
  
  import org.apache.xalan.templates.ElemTemplateElement;
  import org.apache.xml.utils.PrefixResolver;
  import org.apache.xml.utils.QName;
  import org.apache.xml.utils.XMLString;
  import org.apache.xpath.XPathContext;
  import org.apache.xpath.objects.XNodeSet;
  
  /**
   * This class manages the key tables.
   */
  public class KeyManager
  {
  
    /**
     * Table of tables of element keys.
     * @see org.apache.xalan.transformer.KeyTable
     */
    private transient Vector m_key_tables = null;
  
    /**
     * Given a valid element key, return the corresponding node list.
     *
     * @param xctxt The XPath runtime state
     * @param doc The document node
     * @param name The key element name
     * @param ref The key value we're looking for 
     * @param nscontext The prefix resolver for the execution context
     *
     * @return A nodelist of nodes mathing the given key
     *
     * @throws javax.xml.transform.TransformerException
     */
    public XNodeSet getNodeSetDTMByKey(
            XPathContext xctxt, int doc, QName name, XMLString ref, PrefixResolver nscontext)
              throws javax.xml.transform.TransformerException
    {
  
      XNodeSet nl = null;
      ElemTemplateElement template = (ElemTemplateElement) nscontext;  // yuck -sb
  
      if ((null != template)
              && null != template.getStylesheetRoot().getKeysComposed())
      {
        boolean foundDoc = false;
  
        if (null == m_key_tables)
        {
          m_key_tables = new Vector(4);
        }
        else
        {
          int nKeyTables = m_key_tables.size();
  
          for (int i = 0; i < nKeyTables; i++)
          {
            KeyTable kt = (KeyTable) m_key_tables.elementAt(i);
  
            if (kt.getKeyTableName().equals(name) && doc == kt.getDocKey())
            {
              nl = kt.getNodeSetDTMByKey(name, ref);
  
              if (nl != null)
              {
                foundDoc = true;
  
                break;
              }
            }
          }
        }
  
        if ((null == nl) &&!foundDoc /* && m_needToBuildKeysTable */)
        {
          KeyTable kt =
            new KeyTable(doc, nscontext, name,
                         template.getStylesheetRoot().getKeysComposed(),
                         xctxt);
  
          m_key_tables.addElement(kt);
  
          if (doc == kt.getDocKey())
          {
            foundDoc = true;
            nl = kt.getNodeSetDTMByKey(name, ref);
          }
        }
      }
  
      return nl;
    }
  }
  