unionpathiterator.java

java1.6众多例子参考

    return clone;
  }
  
  
  /**
   * Create a new location path iterator.
   *
   * @param compiler The Compiler which is creating 
   * this expression.
   * @param opPos The position of this iterator in the 
   *
   * @return New location path iterator.
   *
   * @throws javax.xml.transform.TransformerException
   */
  protected LocPathIterator createDTMIterator(
          Compiler compiler, int opPos) throws javax.xml.transform.TransformerException
  {
    LocPathIterator lpi = (LocPathIterator)WalkerFactory.newDTMIterator(compiler, opPos, 
                                      (compiler.getLocationPathDepth() <= 0));
    return lpi;
  }

  /**
   * Initialize the location path iterators.  Recursive.
   *
   * @param compiler The Compiler which is creating 
   * this expression.
   * @param opPos The position of this iterator in the 
   * opcode list from the compiler.
   * @param count The insert position of the iterator.
   *
   * @throws javax.xml.transform.TransformerException
   */
  protected void loadLocationPaths(Compiler compiler, int opPos, int count)
          throws javax.xml.transform.TransformerException
  {

    // TODO: Handle unwrapped FilterExpr
    int steptype = compiler.getOp(opPos);

    if (steptype == OpCodes.OP_LOCATIONPATH)
    {
      loadLocationPaths(compiler, compiler.getNextOpPos(opPos), count + 1);

      m_exprs[count] = createDTMIterator(compiler, opPos);
      m_exprs[count].exprSetParent(this);
    }
    else
    {

      // Have to check for unwrapped functions, which the LocPathIterator
      // doesn't handle. 
      switch (steptype)
      {
      case OpCodes.OP_VARIABLE :
      case OpCodes.OP_EXTFUNCTION :
      case OpCodes.OP_FUNCTION :
      case OpCodes.OP_GROUP :
        loadLocationPaths(compiler, compiler.getNextOpPos(opPos), count + 1);

        WalkingIterator iter =
          new WalkingIterator(compiler.getNamespaceContext());
        iter.exprSetParent(this);
          
        if(compiler.getLocationPathDepth() <= 0)
          iter.setIsTopLevel(true);

        iter.m_firstWalker = new com.sun.org.apache.xpath.internal.axes.FilterExprWalker(iter);

        iter.m_firstWalker.init(compiler, opPos, steptype);

        m_exprs[count] = iter;
        break;
      default :
        m_exprs = new LocPathIterator[count];
      }
    }
  }

  /**
   *  Returns the next node in the set and advances the position of the
   * iterator in the set. After a DTMIterator 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;

    // Loop through the iterators getting the current fetched 
    // node, and get the earliest occuring in document order
    int earliestNode = DTM.NULL;

    if (null != m_iterators)
    {
      int n = m_iterators.length;
      int iteratorUsed = -1;

      for (int i = 0; i < n; i++)
      {
        int node = m_iterators[i].getCurrentNode();

        if (DTM.NULL == node)
          continue;
        else if (DTM.NULL == earliestNode)
        {
          iteratorUsed = i;
          earliestNode = node;
        }
        else
        {
          if (node == earliestNode)
          {

            // Found a duplicate, so skip past it.
            m_iterators[i].nextNode();
          }
          else
          {
            DTM dtm = getDTM(node);

            if (dtm.isNodeAfter(node, earliestNode))
            {
              iteratorUsed = i;
              earliestNode = node;
            }
          }
        }
      }

      if (DTM.NULL != earliestNode)
      {
        m_iterators[iteratorUsed].nextNode();

        incrementCurrentPos();
      }
      else
        m_foundLast = true;
    }

    m_lastFetched = earliestNode;

    return earliestNode;
  }
            
  /**
   * 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)
  {
    for (int i = 0; i < m_exprs.length; i++) 
    {
      m_exprs[i].fixupVariables(vars, globalsSize);
    }
    
  }
  
  /**
   * The location path iterators, one for each
   * <a href="http://www.w3.org/TR/xpath#NT-LocationPath">location
   * path</a> contained in the union expression.
   * @serial
   */
  protected LocPathIterator[] m_exprs;

    
  /**
   * The location path iterators, one for each
   * <a href="http://www.w3.org/TR/xpath#NT-LocationPath">location
   * path</a> contained in the union expression.
   * @serial
   */
  protected DTMIterator[] m_iterators;
      
  /**
   * 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()
  {
    // Could be smarter.
    return -1;
  }
  
  class iterOwner implements ExpressionOwner
  {
  	int m_index;
  	
  	iterOwner(int index)
  	{
  		m_index = index;
  	}
  	
    /**
     * @see ExpressionOwner#getExpression()
     */
    public Expression getExpression()
    {
      return m_exprs[m_index];
    }

    /**
     * @see ExpressionOwner#setExpression(Expression)
     */
    public void setExpression(Expression exp)
    {
    	
    	if(!(exp instanceof LocPathIterator))
    	{
    		// Yuck.  Need FilterExprIter.  Or make it so m_exprs can be just 
    		// plain expressions?
    		WalkingIterator wi = new WalkingIterator(getPrefixResolver());
    		FilterExprWalker few = new FilterExprWalker(wi);
    		wi.setFirstWalker(few);
    		few.setInnerExpression(exp);
    		wi.exprSetParent(UnionPathIterator.this);
    		few.exprSetParent(wi);
    		exp.exprSetParent(few);
    		exp = wi;
    	}
    	else
    		exp.exprSetParent(UnionPathIterator.this);
    	m_exprs[m_index] = (LocPathIterator)exp;
    }

  }

  /**
   * @see com.sun.org.apache.xpath.internal.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
   */
  public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
  {
  	 	if(visitor.visitUnionPath(owner, this))
  	 	{
  	 		if(null != m_exprs)
  	 		{
  	 			int n = m_exprs.length;
  	 			for(int i = 0; i < n; i++)
  	 			{
  	 				m_exprs[i].callVisitors(new iterOwner(i), visitor);
  	 			}
  	 		}
  	 	}
  }
  
    /**
     * @see Expression#deepEquals(Expression)
     */
    public boolean deepEquals(Expression expr)
    {
      if (!super.deepEquals(expr))
            return false;

      UnionPathIterator upi = (UnionPathIterator) expr;

      if (null != m_exprs)
      {
        int n = m_exprs.length;
        
        if((null == upi.m_exprs) || (upi.m_exprs.length != n))
        	return false;
        
        for (int i = 0; i < n; i++)
        {
          if(!m_exprs[i].deepEquals(upi.m_exprs[i]))
          	return false;
        }
      }
      else if (null != upi.m_exprs)
      {
          return false;
      }

      return true;
    }


}