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 java.util.StringTokenizer;
  
  import org.apache.xml.dtm.DTM;
  import org.apache.xml.dtm.DTMIterator;
  import org.apache.xml.utils.StringVector;
  import org.apache.xpath.NodeSetDTM;
  import org.apache.xpath.XPathContext;
  import org.apache.xpath.objects.XNodeSet;
  import org.apache.xpath.objects.XObject;
  import org.apache.xpath.res.XPATHErrorResources;
  
  /**
   * Execute the Id() function.
   * @xsl.usage advanced
   */
  public class FuncId extends FunctionOneArg
  {
      static final long serialVersionUID = 8930573966143567310L;
  
    /**
     * Fill in a list with nodes that match a space delimited list if ID 
     * ID references.
     *
     * @param xctxt The runtime XPath context.
     * @param docContext The document where the nodes are being looked for.
     * @param refval A space delimited list of ID references.
     * @param usedrefs List of references for which nodes were found.
     * @param nodeSet Node set where the nodes will be added to.
     * @param mayBeMore true if there is another set of nodes to be looked for.
     *
     * @return The usedrefs value.
     */
    private StringVector getNodesByID(XPathContext xctxt, int docContext,
                                      String refval, StringVector usedrefs,
                                      NodeSetDTM nodeSet, boolean mayBeMore)
    {
  
      if (null != refval)
      {
        String ref = null;
  //      DOMHelper dh = xctxt.getDOMHelper();
        StringTokenizer tokenizer = new StringTokenizer(refval);
        boolean hasMore = tokenizer.hasMoreTokens();
        DTM dtm = xctxt.getDTM(docContext);
  
        while (hasMore)
        {
          ref = tokenizer.nextToken();
          hasMore = tokenizer.hasMoreTokens();
  
          if ((null != usedrefs) && usedrefs.contains(ref))
          {
            ref = null;
  
            continue;
          }
  
          int node = dtm.getElementById(ref);
  
          if (DTM.NULL != node)
            nodeSet.addNodeInDocOrder(node, xctxt);
  
          if ((null != ref) && (hasMore || mayBeMore))
          {
            if (null == usedrefs)
              usedrefs = new StringVector();
  
            usedrefs.addElement(ref);
          }
        }
      }
  
      return usedrefs;
    }
  
    /**
     * 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
    {
  
      int context = xctxt.getCurrentNode();
      DTM dtm = xctxt.getDTM(context);
      int docContext = dtm.getDocument();
  
      if (DTM.NULL == docContext)
        error(xctxt, XPATHErrorResources.ER_CONTEXT_HAS_NO_OWNERDOC, null);
  
      XObject arg = m_arg0.execute(xctxt);
      int argType = arg.getType();
      XNodeSet nodes = new XNodeSet(xctxt.getDTMManager());
      NodeSetDTM nodeSet = nodes.mutableNodeset();
  
      if (XObject.CLASS_NODESET == argType)
      {
        DTMIterator ni = arg.iter();
        StringVector usedrefs = null;
        int pos = ni.nextNode();
  
        while (DTM.NULL != pos)
        {
          DTM ndtm = ni.getDTM(pos);
          String refval = ndtm.getStringValue(pos).toString();
  
          pos = ni.nextNode();
          usedrefs = getNodesByID(xctxt, docContext, refval, usedrefs, nodeSet,
                                  DTM.NULL != pos);
        }
        // ni.detach();
      }
      else if (XObject.CLASS_NULL == argType)
      {
        return nodes;
      }
      else
      {
        String refval = arg.str();
  
        getNodesByID(xctxt, docContext, refval, null, nodeSet, false);
      }
  
      return nodes;
    }
  }
  