http://xml.apache.org/xalan-j/: Serializer to write out XML, HTML etc. as a stream of characters from an input DOM or from input SAX events. (The Apache Software Foundation) 
/*
 * Licensed to the Apache Software Foundation (ASF) under one
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 * 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: FilterExprWalker.java 469367 2006-10-31 04:41:08Z minchau $
 */
package org.apache.xpath.axes;

import org.apache.xml.dtm.Axis;
import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMIterator;
import org.apache.xpath.Expression;
import org.apache.xpath.ExpressionOwner;
import org.apache.xpath.XPathContext;
import org.apache.xpath.XPathVisitor;
import org.apache.xpath.compiler.Compiler;
import org.apache.xpath.compiler.OpCodes;
import org.apache.xpath.objects.XNodeSet;


Walker for the OP_VARIABLE, or OP_EXTFUNCTION, or OP_FUNCTION, or OP_GROUP,
op codes.

See Also:
/**
 * Walker for the OP_VARIABLE, or OP_EXTFUNCTION, or OP_FUNCTION, or OP_GROUP,
 * op codes.
 * @see <a href="http://www.w3.org/TR/xpath#NT-FilterExpr">XPath FilterExpr descriptions</a>
 */
public class FilterExprWalker extends AxesWalker
{
    static final long serialVersionUID = 5457182471424488375L;

  
Construct a FilterExprWalker using a LocPathIterator.

Params:
  • locPathIterator – non-null reference to the parent iterator.
/**
   * Construct a FilterExprWalker using a LocPathIterator.
   *
   * @param locPathIterator non-null reference to the parent iterator.
   */
  public FilterExprWalker(WalkingIterator locPathIterator)
  {
    super(locPathIterator, Axis.FILTEREDLIST);
  }

  
Init a FilterExprWalker.

Params:
  • compiler – non-null reference to the Compiler that is constructing.
  • opPos – positive opcode position for this step.
  • stepType – The type of step.
Throws:
/**
   * Init a FilterExprWalker.
   *
   * @param compiler non-null reference to the Compiler that is constructing.
   * @param opPos positive opcode position for this step.
   * @param stepType The type of step.
   *
   * @throws javax.xml.transform.TransformerException
   */
  public void init(Compiler compiler, int opPos, int stepType)
          throws javax.xml.transform.TransformerException
  {

    super.init(compiler, opPos, stepType);

    // Smooth over an anomily in the opcode map...
    switch (stepType)
    {
    case OpCodes.OP_FUNCTION :
    case OpCodes.OP_EXTFUNCTION :
    	m_mustHardReset = true;
    case OpCodes.OP_GROUP :
    case OpCodes.OP_VARIABLE :
      m_expr = compiler.compile(opPos);
      m_expr.exprSetParent(this);
      //if((OpCodes.OP_FUNCTION == stepType) && (m_expr instanceof org.apache.xalan.templates.FuncKey))
      if(m_expr instanceof org.apache.xpath.operations.Variable)
      {
      	// hack/temp workaround
      	m_canDetachNodeset = false;
      }
      break;
    default :
      m_expr = compiler.compile(opPos + 2);
      m_expr.exprSetParent(this);
    }
//    if(m_expr instanceof WalkingIterator)
//    {
//      WalkingIterator wi = (WalkingIterator)m_expr;
//      if(wi.getFirstWalker() instanceof FilterExprWalker)
//      {
//      	FilterExprWalker fw = (FilterExprWalker)wi.getFirstWalker();
//      	if(null == fw.getNextWalker())
//      	{
//      		m_expr = fw.m_expr;
//      		m_expr.exprSetParent(this);
//      	}
//      }
//      		
//    }
  }
  
  
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();
  	if (m_canDetachNodeset)
  	{
  	  m_exprObj.detach();
  	}
  	m_exprObj = null;
  }

  
 Set the root node of the TreeWalker.

Params:
  • root – non-null reference to the root, or starting point of 
       the query.
/**
   *  Set the root node of the TreeWalker.
   *
   * @param root non-null reference to the root, or starting point of 
   *        the query.
   */
  public void setRoot(int root)
  {

    super.setRoot(root);

  	m_exprObj = FilterExprIteratorSimple.executeFilterExpr(root, 
  	                  m_lpi.getXPathContext(), m_lpi.getPrefixResolver(), 
  	                  m_lpi.getIsTopLevel(), m_lpi.m_stackFrame, m_expr);

  }

  
Get a cloned FilterExprWalker.

Throws:
Returns:A new FilterExprWalker that can be used without mutating this one.
/**
   * Get a cloned FilterExprWalker.
   *
   * @return A new FilterExprWalker that can be used without mutating this one.
   *
   * @throws CloneNotSupportedException
   */
  public Object clone() throws CloneNotSupportedException
  {

    FilterExprWalker clone = (FilterExprWalker) super.clone();

    if (null != m_exprObj)
      clone.m_exprObj = (XNodeSet) m_exprObj.clone();

    return clone;
  }
  
  
This method needs to override AxesWalker.acceptNode because FilterExprWalkers
don't need to, and shouldn't, do a node test.

Params:
  • n –  The node to check to see if it passes the filter or not.
Returns: a constant to determine whether the node is accepted,
  rejected, or skipped, as defined  above .
/**
   * This method needs to override AxesWalker.acceptNode because FilterExprWalkers
   * don't need to, and shouldn't, do a node test.
   * @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)
  {

    try
    {
      if (getPredicateCount() > 0)
      {
        countProximityPosition(0);

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

      return DTMIterator.FILTER_ACCEPT;
    }
    catch (javax.xml.transform.TransformerException se)
    {
      throw new RuntimeException(se.getMessage());
    }
  }

  
 Moves the TreeWalker to the next visible node in document
order relative to the current node, and returns the new node. If the
current node has no next node,  or if the search for nextNode attempts
to step upward from the TreeWalker's root node, returns
null , and retains the current node.

Returns: The new node, or null if the current node has no
  next node  in the TreeWalker's logical view.
/**
   *  Moves the <code>TreeWalker</code> to the next visible node in document
   * order relative to the current node, and returns the new node. If the
   * current node has no next node,  or if the search for nextNode attempts
   * to step upward from the TreeWalker's root node, returns
   * <code>null</code> , and retains the current node.
   * @return  The new node, or <code>null</code> if the current node has no
   *   next node  in the TreeWalker's logical view.
   */
  public int getNextNode()
  {

    if (null != m_exprObj)
    {
       int next = m_exprObj.nextNode();
       return next;
    }
    else
      return DTM.NULL;
  }
  
  
Get the index of the last node that can be itterated to.

Params:
  • xctxt – XPath runtime context.
Returns:the index of the last node that can be itterated to.
/**
   * Get the index of the last node that can be itterated to.
   *
   *
   * @param xctxt XPath runtime context.
   *
   * @return the index of the last node that can be itterated to.
   */
  public int getLastPos(XPathContext xctxt)
  {
    return m_exprObj.getLength();
  }
  
  
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;

  
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();
  }
  
  
Returns the axis being iterated, if it is known.

Returns:Axis.CHILD, etc., or -1 if the axis is not known or is of multiple 
types.
/**
   * 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()
  {
    return m_exprObj.getAxis();
  }
  
  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(FilterExprWalker.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;

      FilterExprWalker walker = (FilterExprWalker)expr;
      if(!m_expr.deepEquals(walker.m_expr))
      	return false;

      return true;
    }

	

}