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.xpath.Expression;
  import org.apache.xpath.ExpressionOwner;
  import org.apache.xpath.XPathVisitor;
  import org.apache.xpath.objects.XNodeSet;
  
  public class FilterExprIterator extends BasicTestIterator
  {
      static final long serialVersionUID = 2552176105165737614L;
    /** The contained expression. Should be non-null.
     *  @serial   */
    private Expression m_expr;
  
    /** The result of executing m_expr.  Needs to be deep cloned on clone op.  */
    transient private XNodeSet m_exprObj;
  
    private boolean m_mustHardReset = false;
    private boolean m_canDetachNodeset = true;
  
    /**
     * Create a FilterExprIterator object.
     *
     */
    public FilterExprIterator()
    {
      super(null);
    }
    
    /**
     * Create a FilterExprIterator object.
     *
     */
    public FilterExprIterator(Expression expr)
    {
      super(null);
      m_expr = expr;
    }
  
    /**
     * 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_exprObj = FilterExprIteratorSimple.executeFilterExpr(context, 
    	                  m_execContext, getPrefixResolver(), 
    	                  getIsTopLevel(), m_stackFrame, m_expr);
     }
  
  
    /**
     * Get the next node via getNextXXX.  Bottlenecked for derived class override.
     * @return The next node on the axis, or DTM.NULL.
     */
    protected int getNextNode()
    {
      if (null != m_exprObj)
      {
        m_lastFetched = m_exprObj.nextNode();
      }
      else
        m_lastFetched = DTM.NULL;
  
      return m_lastFetched;
    }
    
    /**
     * Detaches the walker from the set which it iterated over, releasing
     * any computational resources and placing the iterator in the INVALID
     * state.
     */
    public void detach()
    {  
    	super.detach();
    	m_exprObj.detach();
    	m_exprObj = null;
    }
  
    /**
     * 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);
      m_expr.fixupVariables(vars, globalsSize);
    }
  
    /**
     * Get the inner contained expression of this filter.
     */
    public Expression getInnerExpression()
    {
      return m_expr;
    }
  
    /**
     * Set the inner contained expression of this filter.
     */
    public void setInnerExpression(Expression expr)
    {
      expr.exprSetParent(this);
      m_expr = expr;
    }
  
    /** 
     * Get the analysis bits for this walker, as defined in the WalkerFactory.
     * @return One of WalkerFactory#BIT_DESCENDANT, etc.
     */
    public int getAnalysisBits()
    {
      if (null != m_expr && m_expr instanceof PathComponent)
      {
        return ((PathComponent) m_expr).getAnalysisBits();
      }
      return WalkerFactory.BIT_FILTER;
    }
  
    /**
     * Returns true if all the nodes in the iteration well be returned in document 
     * order.
     * Warning: This can only be called after setRoot has been called!
     * 
     * @return true as a default.
     */
    public boolean isDocOrdered()
    {
      return m_exprObj.isDocOrdered();
    }
  
    class filterExprOwner implements ExpressionOwner
    {
      /**
      * @see ExpressionOwner#getExpression()
      */
      public Expression getExpression()
      {
        return m_expr;
      }
  
      /**
       * @see ExpressionOwner#setExpression(Expression)
       */
      public void setExpression(Expression exp)
      {
        exp.exprSetParent(FilterExprIterator.this);
        m_expr = exp;
      }
  
    }
  
    /**
     * 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)
    {
      m_expr.callVisitors(new filterExprOwner(), visitor);
  
      super.callPredicateVisitors(visitor);
    }
  
    /**
     * @see Expression#deepEquals(Expression)
     */
    public boolean deepEquals(Expression expr)
    {
      if (!super.deepEquals(expr))
        return false;
  
      FilterExprIterator fet = (FilterExprIterator) expr;
      if (!m_expr.deepEquals(fet.m_expr))
        return false;
  
      return true;
    }
  
  }
  