predicatednodetest.java

java1.6众多例子参考

    // System.out.println("nPredicates: "+nPredicates);
    if (nPredicates == 0)
      return true;

    PrefixResolver savedResolver = xctxt.getNamespaceContext();

    try
    {
      m_predicateIndex = 0;
      xctxt.pushSubContextList(this);
      xctxt.pushNamespaceContext(m_lpi.getPrefixResolver());
      xctxt.pushCurrentNode(context);

      for (int i = 0; i < nPredicates; i++)
      {
        // System.out.println("Executing predicate expression - waiting count: "+m_lpi.getWaitingCount());
        XObject pred = m_predicates[i].execute(xctxt);
        // System.out.println("\nBack from executing predicate expression - waiting count: "+m_lpi.getWaitingCount());
        // System.out.println("pred.getType(): "+pred.getType());
        if (XObject.CLASS_NUMBER == pred.getType())
        {
          if (DEBUG_PREDICATECOUNTING)
          {
            System.out.flush();
            System.out.println("\n===== start predicate count ========");
            System.out.println("m_predicateIndex: " + m_predicateIndex);
            // System.out.println("getProximityPosition(m_predicateIndex): "
            //                   + getProximityPosition(m_predicateIndex));
            System.out.println("pred.num(): " + pred.num());
          }

          int proxPos = this.getProximityPosition(m_predicateIndex);
          int predIndex = (int) pred.num();
          if (proxPos != predIndex)
          {
            if (DEBUG_PREDICATECOUNTING)
            {
              System.out.println("\nnode context: "+nodeToString(context));
              System.out.println("index predicate is false: "+proxPos);
              System.out.println("\n===== end predicate count ========");
            }
            return false;
          }
          else if (DEBUG_PREDICATECOUNTING)
          {
            System.out.println("\nnode context: "+nodeToString(context));
            System.out.println("index predicate is true: "+proxPos);
            System.out.println("\n===== end predicate count ========");
          }
          
          // If there is a proximity index that will not change during the 
          // course of itteration, then we know there can be no more true 
          // occurances of this predicate, so flag that we're done after 
          // this.
          //
          // bugzilla 14365
          // We can't set m_foundLast = true unless we're sure that -all-
          // remaining parameters are stable, or else last() fails. Fixed so
          // only sets m_foundLast if on the last predicate
          if(m_predicates[i].isStableNumber() && i == nPredicates - 1)
          {
            m_foundLast = true;
          }
        }
        else if (!pred.bool())
          return false;

        countProximityPosition(++m_predicateIndex);
      }
    }
    finally
    {
      xctxt.popCurrentNode();
      xctxt.popNamespaceContext();
      xctxt.popSubContextList();
      m_predicateIndex = -1;
    }

    return true;
  }
  
  /**
   * 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);

    int nPredicates = getPredicateCount();

    for (int i = 0; i < nPredicates; i++)
    {
      m_predicates[i].fixupVariables(vars, globalsSize);
    }
  }

  
  /**
   * Diagnostics.
   *
   * @param n Node to give diagnostic information about, or null.
   *
   * @return Informative string about the argument.
   */
  protected String nodeToString(int n)
  {
    if(DTM.NULL != n)
    {
      DTM dtm = m_lpi.getXPathContext().getDTM(n);
      return dtm.getNodeName(n) + "{" + (n+1) + "}";
    }
    else
    {
      return "null";
    }
  }
  
  //=============== NodeFilter Implementation ===============

  /**
   *  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 = m_lpi.getXPathContext();

    try
    {
      xctxt.pushCurrentNode(n);

      XObject score = execute(xctxt, n);

      // System.out.println("\n::acceptNode - score: "+score.num()+"::");
      if (score != NodeTest.SCORE_NONE)
      {
        if (getPredicateCount() > 0)
        {
          countProximityPosition(0);

          if (!executePredicates(n, xctxt))
            return DTMIterator.FILTER_SKIP;
        }

        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;
  }

  
  /**
   * Get the owning location path iterator.
   *
   * @return the owning location path iterator, which should not be null.
   */
  public LocPathIterator getLocPathIterator()
  {
    return m_lpi;
  }

  /**
   * Set the location path iterator owner for this walker.  Besides 
   * initialization, this function is called during cloning operations.
   *
   * @param li non-null reference to the owning location path iterator.
   */
  public void setLocPathIterator(LocPathIterator li)
  {
    m_lpi = li;
    if(this != li)
      li.exprSetParent(this);
  }
  
  /**
   * Tell if this expression or it's subexpressions can traverse outside 
   * the current subtree.
   * 
   * @return true if traversal outside the context node's subtree can occur.
   */
   public boolean canTraverseOutsideSubtree()
   {
    int n = getPredicateCount();
    for (int i = 0; i < n; i++) 
    {
      if(getPredicate(i).canTraverseOutsideSubtree())
        return true;
    }
    return false;
   }
   
	/**
	 * This will traverse the heararchy, calling the visitor for 
	 * each member.  If the called visitor method returns 
	 * false, the subtree should not be called.
	 * 
	 * @param visitor The visitor whose appropriate method will be called.
	 */
	public void callPredicateVisitors(XPathVisitor visitor)
	{
	  if (null != m_predicates)
	    {
	    int n = m_predicates.length;
	    for (int i = 0; i < n; i++)
	      {
	      ExpressionOwner predOwner = new PredOwner(i);
	      if (visitor.visitPredicate(predOwner, m_predicates[i]))
	        {
	        m_predicates[i].callVisitors(predOwner, visitor);
	      }
	
	    }
	  }
	} 
	
    /**
     * @see Expression#deepEquals(Expression)
     */
    public boolean deepEquals(Expression expr)
    {
      if (!super.deepEquals(expr))
            return false;

      PredicatedNodeTest pnt = (PredicatedNodeTest) expr;
      if (null != m_predicates)
      {

        int n = m_predicates.length;
        if ((null == pnt.m_predicates) || (pnt.m_predicates.length != n))
              return false;
        for (int i = 0; i < n; i++)
        {
          if (!m_predicates[i].deepEquals(pnt.m_predicates[i]))
          	return false; 
        }
      }
      else if (null != pnt.m_predicates)
              return false; 
              
      return true; 
    }
    
  /** This is true if nextNode returns null. */
  transient protected boolean m_foundLast = false;
    
  /** The owning location path iterator.
   *  @serial */
  protected LocPathIterator m_lpi;
  
  /**
   * Which predicate we are executing.
   */
  transient int m_predicateIndex = -1;
  
  /** The list of predicate expressions. Is static and does not need 
   *  to be deep cloned.
   *  @serial 
   */
  private Expression[] m_predicates;

  /**
   * An array of counts that correspond to the number
   * of predicates the step contains.
   */
  transient protected int[] m_proximityPositions;

  /** If true, diagnostic messages about predicate execution will be posted.  */
  static final boolean DEBUG_PREDICATECOUNTING = false;
  
  class PredOwner implements ExpressionOwner
  {
  	int m_index;
  	
  	PredOwner(int index)
  	{
  		m_index = index;
  	}
  	
    /**
     * @see ExpressionOwner#getExpression()
     */
    public Expression getExpression()
    {
      return m_predicates[m_index];
    }


    /**
     * @see ExpressionOwner#setExpression(Expression)
     */
    public void setExpression(Expression exp)
    {
    	exp.exprSetParent(PredicatedNodeTest.this);
    	m_predicates[m_index] = exp;
    }
  }
    
}