/*
* reserved comment block
* DO NOT REMOVE OR ALTER!
*/
/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed 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: ReverseAxesWalker.java,v 1.2.4.1 2005/09/14 19:45:21 jeffsuttor Exp $
*/
package com.sun.org.apache.xpath.internal.axes;
import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;
import com.sun.org.apache.xpath.internal.XPathContext;
/**
* 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
{
static final long serialVersionUID = 2847007647832768941L;
/**
* 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);
}
/**
* 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()
{
m_iterator = null;
super.detach();
}
/**
* 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()
{
if (m_foundLast)
return DTM.NULL;
int next = m_iterator.next();
if (m_isFresh)
m_isFresh = false;
if (DTM.NULL == next)
this.m_foundLast = 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;
int count = m_proximityPositions[predicateIndex];
if (count <= 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
count++;
int next;
while (DTM.NULL != (next = clone.nextNode()))
{
count++;
}
m_proximityPositions[predicateIndex] = count;
}
catch (CloneNotSupportedException cnse)
{
// can't happen
}
finally
{
wi().setLastUsedWalker(savedWalker);
}
}
return count;
}
/**
* 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;
}
/**
* 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 false.
*/
public boolean isDocOrdered()
{
return false; // I think.
}
/** The DTM inner traversal class, that corresponds to the super axis. */
protected DTMAxisIterator m_iterator;
}