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.DTM;
  import org.apache.xml.dtm.DTMFilter;
  import org.apache.xpath.Expression;
  import org.apache.xpath.compiler.Compiler;
  import org.apache.xpath.compiler.OpMap;
  
  /**
   * This class implements a general iterator for
   * those LocationSteps with only one step, and perhaps a predicate, 
   * that only go forward (i.e. it can not be used with ancestors, 
   * preceding, etc.)
   * @see org.apache.xpath.axes#ChildTestIterator
   * @xsl.usage advanced
   */
  public class OneStepIteratorForward extends ChildTestIterator
  {
      static final long serialVersionUID = -1576936606178190566L;
    /** The traversal axis from where the nodes will be filtered. */
    protected int m_axis = -1;
  
    /**
     * Create a OneStepIterator object.
     *
     * @param compiler A reference to the Compiler that contains the op map.
     * @param opPos The position within the op map, which contains the
     * location path expression for this itterator.
     *
     * @throws javax.xml.transform.TransformerException
     */
    OneStepIteratorForward(Compiler compiler, int opPos, int analysis)
            throws javax.xml.transform.TransformerException
    {
      super(compiler, opPos, analysis);
      int firstStepPos = OpMap.getFirstChildPos(opPos);
      
      m_axis = WalkerFactory.getAxisFromStep(compiler, firstStepPos);
      
    }
      
    /**
     * Create a OneStepIterator object that will just traverse the self axes.
     * 
     * @param axis One of the org.apache.xml.dtm.Axis integers.
     *
     * @throws javax.xml.transform.TransformerException
     */
    public OneStepIteratorForward(int axis)
    {
      super(null);
      
      m_axis = axis;
      int whatToShow = DTMFilter.SHOW_ALL;
      initNodeTest(whatToShow);
    }
  
    
  
    
    /**
     * Initialize the context values for this expression
     * after it is cloned.
     *
     * @param context The XPath runtime context for this
     * transformation.
     */
    public void setRoot(int context, Object environment)
    {
      super.setRoot(context, environment);
      m_traverser = m_cdtm.getAxisTraverser(m_axis);
      
    }
    
  //  /**
  //   * Return the first node out of the nodeset, if this expression is 
  //   * a nodeset expression.  This is the default implementation for 
  //   * nodesets.
  //   * <p>WARNING: Do not mutate this class from this function!</p>
  //   * @param xctxt The XPath runtime context.
  //   * @return the first node out of the nodeset, or DTM.NULL.
  //   */
  //  public int asNode(XPathContext xctxt)
  //    throws javax.xml.transform.TransformerException
  //  {
  //    if(getPredicateCount() > 0)
  //      return super.asNode(xctxt);
  //      
  //    int current = xctxt.getCurrentNode();
  //    
  //    DTM dtm = xctxt.getDTM(current);
  //    DTMAxisTraverser traverser = dtm.getAxisTraverser(m_axis);
  //    
  //    String localName = getLocalName();
  //    String namespace = getNamespace();
  //    int what = m_whatToShow;
  //    
  //    // System.out.println("what: ");
  //    // NodeTest.debugWhatToShow(what);
  //    if(DTMFilter.SHOW_ALL == what
  //       || ((DTMFilter.SHOW_ELEMENT & what) == 0)
  //       || localName == NodeTest.WILD
  //       || namespace == NodeTest.WILD)
  //    {
  //      return traverser.first(current);
  //    }
  //    else
  //    {
  //      int type = getNodeTypeTest(what);
  //      int extendedType = dtm.getExpandedTypeID(namespace, localName, type);
  //      return traverser.first(current, extendedType);
  //    }
  //  }
    
    /**
     * Get the next node via getFirstAttribute && getNextAttribute.
     */
    protected int getNextNode()
    {
      m_lastFetched = (DTM.NULL == m_lastFetched)
                       ? m_traverser.first(m_context)
                       : m_traverser.next(m_context, m_lastFetched);
      return m_lastFetched;
    }
    
    /**
     * Returns the axis being iterated, if it is known.
     * 
     * @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple 
     * types.
     */
    public int getAxis()
    {
      return m_axis;
    }
  
    /**
     * @see Expression#deepEquals(Expression)
     */
    public boolean deepEquals(Expression expr)
    {
    	if(!super.deepEquals(expr))
    		return false;
    		
    	if(m_axis != ((OneStepIteratorForward)expr).m_axis)
    		return false;
    		
    	return true;
    }
  
    
  }
  