/*
 * 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: FilterExprIterator.java 468655 2006-10-28 07:12:06Z minchau $
 */
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   /** 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.  /** 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.
/**
   * Create a FilterExprIterator object.
   *
   */
  public FilterExprIterator()
  {
    super(null);
  }
  
  
Create a FilterExprIterator object.
/**
   * Create a FilterExprIterator object.
   *
   */
  public FilterExprIterator(Expression expr)
  {
    super(null);
    m_expr = expr;
  }

  
Initialize the context values for this expression
after it is cloned.
Params:
context – The XPath runtime context for this
transformation./**
   * 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.
Returns:
The next node on the axis, or DTM.NULL./**
   * 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.
/**
   * 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.
Params:
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)./**
   * 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.
/**
   * Get the inner contained expression of this filter.
   */
  public Expression getInnerExpression()
  {
    return m_expr;
  }

  
Set the inner contained expression of this filter.
/**
   * 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.
Returns:
One of WalkerFactory#BIT_DESCENDANT, etc./** 
   * 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!
Returns:
true as a default./**
   * 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 Also:
getExpression.getExpression()/**
    * @see ExpressionOwner#getExpression()
    */
    public Expression getExpression()
    {
      return m_expr;
    }

    
See Also:
setExpression.setExpression(Expression)/**
     * @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.
Params:
visitor – The visitor whose appropriate method will be called./**
   * 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 Also:
deepEquals.deepEquals(Expression)/**
   * @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;
  }

}