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.Axis;
  import org.apache.xml.dtm.DTM;
  import org.apache.xml.dtm.DTMAxisTraverser;
  import org.apache.xml.dtm.DTMIterator;
  import org.apache.xpath.XPathContext;
  import org.apache.xpath.compiler.Compiler;
  import org.apache.xpath.compiler.OpMap;
  import org.apache.xpath.objects.XObject;
  import org.apache.xpath.patterns.NodeTest;
  import org.apache.xpath.patterns.StepPattern;
  
  /**
   * This class treats a 
   * <a href="http://www.w3.org/TR/xpath#location-paths">LocationPath</a> as a 
   * filtered iteration over the tree, evaluating each node in a super axis 
   * traversal against the LocationPath interpreted as a match pattern.  This 
   * class is useful to find nodes in document order that are complex paths 
   * whose steps probably criss-cross each other.
   */
  public class MatchPatternIterator extends LocPathIterator
  {
      static final long serialVersionUID = -5201153767396296474L;
  
    /** This is the select pattern, translated into a match pattern. */
    protected StepPattern m_pattern;
  
    /** The traversal axis from where the nodes will be filtered. */
    protected int m_superAxis = -1;
  
    /** The DTM inner traversal class, that corresponds to the super axis. */
    protected DTMAxisTraverser m_traverser;
    
    /** DEBUG flag for diagnostic dumps. */
    private static final boolean DEBUG = false;
    
  //  protected int m_nsElemBase = DTM.NULL;
  
    /**
     * Create a LocPathIterator object, including creation
     * of step walkers from the opcode list, and call back
     * into the Compiler to create predicate expressions.
     *
     * @param compiler The Compiler which is creating
     * this expression.
     * @param opPos The position of this iterator in the
     * opcode list from the compiler.
     * @param analysis Analysis bits that give general information about the 
     * LocationPath.
     *
     * @throws javax.xml.transform.TransformerException
     */
    MatchPatternIterator(Compiler compiler, int opPos, int analysis)
            throws javax.xml.transform.TransformerException
    {
  
      super(compiler, opPos, analysis, false);
  
      int firstStepPos = OpMap.getFirstChildPos(opPos);
  
      m_pattern = WalkerFactory.loadSteps(this, compiler, firstStepPos, 0); 
  
      boolean fromRoot = false;
      boolean walkBack = false;
      boolean walkDescendants = false;
      boolean walkAttributes = false;
  
      if (0 != (analysis & (WalkerFactory.BIT_ROOT | 
                            WalkerFactory.BIT_ANY_DESCENDANT_FROM_ROOT)))
        fromRoot = true;
        
      if (0 != (analysis
                & (WalkerFactory.BIT_ANCESTOR
                   | WalkerFactory.BIT_ANCESTOR_OR_SELF
                   | WalkerFactory.BIT_PRECEDING
                   | WalkerFactory.BIT_PRECEDING_SIBLING 
                   | WalkerFactory.BIT_FOLLOWING
                   | WalkerFactory.BIT_FOLLOWING_SIBLING
                   | WalkerFactory.BIT_PARENT | WalkerFactory.BIT_FILTER)))
        walkBack = true;
  
      if (0 != (analysis
                & (WalkerFactory.BIT_DESCENDANT_OR_SELF
                   | WalkerFactory.BIT_DESCENDANT
                   | WalkerFactory.BIT_CHILD)))
        walkDescendants = true;
  
      if (0 != (analysis
                & (WalkerFactory.BIT_ATTRIBUTE | WalkerFactory.BIT_NAMESPACE)))
        walkAttributes = true;
        
      if(false || DEBUG)
      {
        System.out.print("analysis: "+Integer.toBinaryString(analysis));
        System.out.println(", "+WalkerFactory.getAnalysisString(analysis));
      }
        
      if(fromRoot || walkBack)
      {
        if(walkAttributes)
        {
          m_superAxis = Axis.ALL;
        }
        else
        {
          m_superAxis = Axis.DESCENDANTSFROMROOT;
        }
      }
      else if(walkDescendants)
      {
        if(walkAttributes)
        {
          m_superAxis = Axis.ALLFROMNODE;
        }
        else
        {
          m_superAxis = Axis.DESCENDANTORSELF;
        }
      }
      else
      {
        m_superAxis = Axis.ALL;
      }
      if(false || DEBUG)
      {
        System.out.println("axis: "+Axis.getNames(m_superAxis));
      }
      
    }
    
    
    /**
     * 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_superAxis);
    }
  
    /**
     *  Detaches the iterator from the set which it iterated over, releasing
     * any computational resources and placing the iterator in the INVALID
     * state. After<code>detach</code> has been invoked, calls to
     * <code>nextNode</code> or<code>previousNode</code> will raise the
     * exception INVALID_STATE_ERR.
     */
    public void detach()
    {    
      if(m_allowDetach)
      {
        m_traverser = null;
        
        // Always call the superclass detach last!
        super.detach();
      }
    }
    
    /**
     * Get the next node via getNextXXX.  Bottlenecked for derived class override.
     * @return The next node on the axis, or DTM.NULL.
     */
    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 next node in the set and advances the position of the
     * iterator in the set. After a NodeIterator is created, the first call
     * to nextNode() returns the first node in the set.
     * @return  The next <code>Node</code> in the set being iterated over, or
     *   <code>null</code> if there are no more members in that set.
     */
    public int nextNode()
    {      
    	if(m_foundLast)
    		return DTM.NULL;
  
      int next;
      
      org.apache.xpath.VariableStack vars;
      int savedStart;
      if (-1 != m_stackFrame)
      {
        vars = m_execContext.getVarStack();
  
        // These three statements need to be combined into one operation.
        savedStart = vars.getStackFrame();
  
        vars.setStackFrame(m_stackFrame);
      }
      else
      {
        // Yuck.  Just to shut up the compiler!
        vars = null;
        savedStart = 0;
      }
      
      try
      {
        if(DEBUG)
          System.out.println("m_pattern"+m_pattern.toString());
  
        do
        {
          next = getNextNode();
    
          if (DTM.NULL != next)
          {
            if(DTMIterator.FILTER_ACCEPT == acceptNode(next, m_execContext))
              break;
            else
              continue;
          }
          else
            break;
        }
        while (next != DTM.NULL);
        
        if (DTM.NULL != next)
        {
          if(DEBUG)
          {
            System.out.println("next: "+next);
            System.out.println("name: "+m_cdtm.getNodeName(next));
          }
          incrementCurrentPos();
    
          return next;
        }
        else
        {
          m_foundLast = true;
    
          return DTM.NULL;
        }
      }
      finally
      {
        if (-1 != m_stackFrame)
        {
          // These two statements need to be combined into one operation.
          vars.setStackFrame(savedStart);
        }
      }
  
    }
    
    /**
     *  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)
    {
  
      try
      {
        xctxt.pushCurrentNode(n);
        xctxt.pushIteratorRoot(m_context);
        if(DEBUG)
        {
          System.out.println("traverser: "+m_traverser);
          System.out.print("node: "+n);
          System.out.println(", "+m_cdtm.getNodeName(n));
          // if(m_cdtm.getNodeName(n).equals("near-east"))
          System.out.println("pattern: "+m_pattern.toString());
          m_pattern.debugWhatToShow(m_pattern.getWhatToShow());
        }
        
        XObject score = m_pattern.execute(xctxt);
        
        if(DEBUG)
        {
          // System.out.println("analysis: "+Integer.toBinaryString(m_analysis));
          System.out.println("score: "+score);
          System.out.println("skip: "+(score == NodeTest.SCORE_NONE));
        }
  
        // System.out.println("\n::acceptNode - score: "+score.num()+"::");
        return (score == NodeTest.SCORE_NONE) ? DTMIterator.FILTER_SKIP 
                      : DTMIterator.FILTER_ACCEPT;
      }
      catch (javax.xml.transform.TransformerException se)
      {
  
        // TODO: Fix this.
        throw new RuntimeException(se.getMessage());
      }
      finally
      {
        xctxt.popCurrentNode();
        xctxt.popIteratorRoot();
      }
  
    }
  
  }
  