/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
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* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Xalan" and "Apache Software Foundation" must
* not be used to endorse or promote products derived from this
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* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
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*
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* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation and was
* originally based on software copyright (c) 1999, Lotus
* Development Corporation., http://www.lotus.com. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
package org.apache.xpath.axes;
import java.util.Vector;
import org.apache.xpath.axes.LocPathIterator;
import org.apache.xpath.XPath;
import org.apache.xpath.XPathContext;
import org.apache.xpath.compiler.OpCodes;
import org.apache.xpath.objects.XObject;
import javax.xml.transform.TransformerException;
import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMIterator;
import org.apache.xml.dtm.DTMAxisIterator;
import org.apache.xml.dtm.Axis;
/**
* Walker for a reverse axes.
* @see <a href="http://www.w3.org/TR/xpath#predicates">XPath 2.4 Predicates</a>
*/
public class ReverseAxesWalker extends AxesWalker
{
/**
* Construct an AxesWalker using a LocPathIterator.
*
* @param locPathIterator The location path iterator that 'owns' this walker.
*/
ReverseAxesWalker(LocPathIterator locPathIterator, int axis)
{
super(locPathIterator, axis);
}
/**
* Set the root node of the TreeWalker.
* (Not part of the DOM2 TreeWalker interface).
*
* @param root The context node of this step.
*/
public void setRoot(int root)
{
super.setRoot(root);
m_iterator = getDTM(root).getAxisIterator(m_axis);
m_iterator.setStartNode(root);
}
/**
* Get the next node in document order on the axes.
*
* @return the next node in document order on the axes, or null.
*/
protected int getNextNode()
{
int next = m_iterator.next();
if (m_isFresh)
m_isFresh = false;
if (DTM.NULL == next)
this.m_isDone = true;
return next;
}
/**
* Tells if this is a reverse axes. Overrides AxesWalker#isReverseAxes.
*
* @return true for this class.
*/
public boolean isReverseAxes()
{
return true;
}
// /**
// * Set the root node of the TreeWalker.
// *
// * @param root The context node of this step.
// */
// public void setRoot(int root)
// {
// super.setRoot(root);
// }
/**
* Get the current sub-context position. In order to do the
* reverse axes count, for the moment this re-searches the axes
* up to the predicate. An optimization on this is to cache
* the nodes searched, but, for the moment, this case is probably
* rare enough that the added complexity isn't worth it.
*
* @param predicateIndex The predicate index of the proximity position.
*
* @return The pridicate index, or -1.
*/
protected int getProximityPosition(int predicateIndex)
{
// A negative predicate index seems to occur with
// (preceding-sibling::*|following-sibling::*)/ancestor::*[position()]/*[position()]
// -sb
if(predicateIndex < 0)
return -1;
if (m_proximityPositions[predicateIndex] <= 0)
{
AxesWalker savedWalker = wi().getLastUsedWalker();
try
{
ReverseAxesWalker clone = (ReverseAxesWalker) this.clone();
clone.setRoot(this.getRoot());
clone.setPredicateCount(predicateIndex);
clone.setPrevWalker(null);
clone.setNextWalker(null);
wi().setLastUsedWalker(clone);
// Count 'em all
int count = 1;
int next;
while (DTM.NULL != (next = clone.nextNode()))
{
count++;
}
m_proximityPositions[predicateIndex] += count;
}
catch (CloneNotSupportedException cnse)
{
// can't happen
}
finally
{
wi().setLastUsedWalker(savedWalker);
}
}
return m_proximityPositions[predicateIndex];
}
/**
* Count backwards one proximity position.
*
* @param i The predicate index.
*/
protected void countProximityPosition(int i)
{
if (i < m_proximityPositions.length)
m_proximityPositions[i]--;
}
/**
* Get the number of nodes in this node list. The function is probably ill
* named?
*
*
* @param xctxt The XPath runtime context.
*
* @return the number of nodes in this node list.
*/
public int getLastPos(XPathContext xctxt)
{
int count = 0;
AxesWalker savedWalker = wi().getLastUsedWalker();
try
{
ReverseAxesWalker clone = (ReverseAxesWalker) this.clone();
clone.setRoot(this.getRoot());
clone.setPredicateCount(this.getPredicateCount() - 1);
clone.setPrevWalker(null);
clone.setNextWalker(null);
wi().setLastUsedWalker(clone);
// Count 'em all
// count = 1;
int next;
while (DTM.NULL != (next = clone.nextNode()))
{
count++;
}
}
catch (CloneNotSupportedException cnse)
{
// can't happen
}
finally
{
wi().setLastUsedWalker(savedWalker);
}
return count;
}
/** The DTM inner traversal class, that corresponds to the super axis. */
protected DTMAxisIterator m_iterator;
}