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.axes;
  
  import org.apache.xml.dtm.DTMIterator;
  import org.apache.xpath.XPathContext;
  import org.apache.xpath.objects.XObject;
  import org.apache.xpath.patterns.NodeTest;
  
  /**
   * This class defines a simplified type of union iterator that only 
   * tests along the child axes.  If the conditions are right, it is 
   * much faster than using a UnionPathIterator.
   */
  public class UnionChildIterator extends ChildTestIterator
  {
      static final long serialVersionUID = 3500298482193003495L;
    /**
     * Even though these may hold full LocPathIterators, this array does 
     * not have to be cloned, since only the node test and predicate 
     * portion are used, and these only need static information.  However, 
     * also note that index predicates can not be used!
     */
    private PredicatedNodeTest[] m_nodeTests = null;
  
    /**
     * Constructor for UnionChildIterator
     */
    public UnionChildIterator()
    {
      super(null);
    }
  
    /**
     * Add a node test to the union list.
     *
     * @param test reference to a NodeTest, which will be added 
     * directly to the list of node tests (in other words, it will 
     * not be cloned).  The parent of this test will be set to 
     * this object.
     */
    public void addNodeTest(PredicatedNodeTest test)
    {
  
      // Increase array size by only 1 at a time.  Fix this
      // if it looks to be a problem.
      if (null == m_nodeTests)
      {
        m_nodeTests = new PredicatedNodeTest[1];
        m_nodeTests[0] = test;
      }
      else
      {
        PredicatedNodeTest[] tests = m_nodeTests;
        int len = m_nodeTests.length;
  
        m_nodeTests = new PredicatedNodeTest[len + 1];
  
        System.arraycopy(tests, 0, m_nodeTests, 0, len);
  
        m_nodeTests[len] = test;
      }
      test.exprSetParent(this);
    }
  
    /**
     * This function is used to fixup variables from QNames to stack frame 
     * indexes at stylesheet build time.
     * @param vars List of QNames that correspond to variables.  This list 
     * should be searched backwards for the first qualified name that 
     * corresponds to the variable reference qname.  The position of the 
     * QName in the vector from the start of the vector will be its position 
     * in the stack frame (but variables above the globalsTop value will need 
     * to be offset to the current stack frame).
     */
    public void fixupVariables(java.util.Vector vars, int globalsSize)
    {
      super.fixupVariables(vars, globalsSize);
      if (m_nodeTests != null) {
        for (int i = 0; i < m_nodeTests.length; i++) {
          m_nodeTests[i].fixupVariables(vars, globalsSize);
        }
      }
    }
  
    /**
     * Test whether a specified node is visible in the logical view of a
     * TreeWalker or NodeIterator. This function will be called by the
     * implementation of TreeWalker and NodeIterator; it is not intended to
     * be called directly from user code.
     * @param n  The node to check to see if it passes the filter or not.
     * @return  a constant to determine whether the node is accepted,
     *   rejected, or skipped, as defined  above .
     */
    public short acceptNode(int n)
    {
      XPathContext xctxt = getXPathContext();
      try
      {
        xctxt.pushCurrentNode(n);
        for (int i = 0; i < m_nodeTests.length; i++)
        {
          PredicatedNodeTest pnt = m_nodeTests[i];
          XObject score = pnt.execute(xctxt, n);
          if (score != NodeTest.SCORE_NONE)
          {
            // Note that we are assuming there are no positional predicates!
            if (pnt.getPredicateCount() > 0)
            {
              if (pnt.executePredicates(n, xctxt))
                return DTMIterator.FILTER_ACCEPT;
            }
            else
              return DTMIterator.FILTER_ACCEPT;
  
          }
        }
      }
      catch (javax.xml.transform.TransformerException se)
      {
  
        // TODO: Fix this.
        throw new RuntimeException(se.getMessage());
      }
      finally
      {
        xctxt.popCurrentNode();
      }
      return DTMIterator.FILTER_SKIP;
    }
  
  }
  