org.apache.xpath.axes.WalkingIteratorSorted Maven / Gradle / Ivy
/*
* 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: WalkingIteratorSorted.java 468655 2006-10-28 07:12:06Z minchau $
*/
package org.apache.xpath.axes;
import org.apache.xml.dtm.Axis;
import org.apache.xml.utils.PrefixResolver;
import org.apache.xpath.compiler.Compiler;
/**
* This class iterates over set of nodes that needs to be sorted.
* @xsl.usage internal
*/
public class WalkingIteratorSorted extends WalkingIterator
{
static final long serialVersionUID = -4512512007542368213L;
// /** True if the nodes will be found in document order */
// protected boolean m_inNaturalOrder = false;
/** True if the nodes will be found in document order, and this can
* be determined statically. */
protected boolean m_inNaturalOrderStatic = false;
/**
* Create a WalkingIteratorSorted object.
*
* @param nscontext The namespace context for this iterator,
* should be OK if null.
*/
public WalkingIteratorSorted(PrefixResolver nscontext)
{
super(nscontext);
}
/**
* Create a WalkingIterator iterator, including creation
* of step walkers from the opcode list, and call back
* into the Compiler to create predicate expressions.
*
* @param compiler The Compiler which is creating
* this expression.
* @param opPos The position of this iterator in the
* opcode list from the compiler.
* @param shouldLoadWalkers True if walkers should be
* loaded, or false if this is a derived iterator and
* it doesn't wish to load child walkers.
*
* @throws javax.xml.transform.TransformerException
*/
WalkingIteratorSorted(
Compiler compiler, int opPos, int analysis, boolean shouldLoadWalkers)
throws javax.xml.transform.TransformerException
{
super(compiler, opPos, analysis, shouldLoadWalkers);
}
/**
* Returns true if all the nodes in the iteration well be returned in document
* order.
*
* @return true as a default.
*/
public boolean isDocOrdered()
{
return m_inNaturalOrderStatic;
}
/**
* Tell if the nodeset can be walked in doc order, via static analysis.
*
*
* @return true if the nodeset can be walked in doc order, without sorting.
*/
boolean canBeWalkedInNaturalDocOrderStatic()
{
if (null != m_firstWalker)
{
AxesWalker walker = m_firstWalker;
int prevAxis = -1;
boolean prevIsSimpleDownAxis = true;
for(int i = 0; null != walker; i++)
{
int axis = walker.getAxis();
if(walker.isDocOrdered())
{
boolean isSimpleDownAxis = ((axis == Axis.CHILD)
|| (axis == Axis.SELF)
|| (axis == Axis.ROOT));
// Catching the filtered list here is only OK because
// FilterExprWalker#isDocOrdered() did the right thing.
if(isSimpleDownAxis || (axis == -1))
walker = walker.getNextWalker();
else
{
boolean isLastWalker = (null == walker.getNextWalker());
if(isLastWalker)
{
if(walker.isDocOrdered() && (axis == Axis.DESCENDANT ||
axis == Axis.DESCENDANTORSELF || axis == Axis.DESCENDANTSFROMROOT
|| axis == Axis.DESCENDANTSORSELFFROMROOT) || (axis == Axis.ATTRIBUTE))
return true;
}
return false;
}
}
else
return false;
}
return true;
}
return false;
}
// /**
// * NEEDSDOC Method canBeWalkedInNaturalDocOrder
// *
// *
// * NEEDSDOC (canBeWalkedInNaturalDocOrder) @return
// */
// boolean canBeWalkedInNaturalDocOrder()
// {
//
// if (null != m_firstWalker)
// {
// AxesWalker walker = m_firstWalker;
// int prevAxis = -1;
// boolean prevIsSimpleDownAxis = true;
//
// for(int i = 0; null != walker; i++)
// {
// int axis = walker.getAxis();
//
// if(walker.isDocOrdered())
// {
// boolean isSimpleDownAxis = ((axis == Axis.CHILD)
// || (axis == Axis.SELF)
// || (axis == Axis.ROOT));
// // Catching the filtered list here is only OK because
// // FilterExprWalker#isDocOrdered() did the right thing.
// if(isSimpleDownAxis || (axis == -1))
// walker = walker.getNextWalker();
// else
// {
// boolean isLastWalker = (null == walker.getNextWalker());
// if(isLastWalker)
// {
// if(walker.isDocOrdered() && (axis == Axis.DESCENDANT ||
// axis == Axis.DESCENDANTORSELF || axis == Axis.DESCENDANTSFROMROOT
// || axis == Axis.DESCENDANTSORSELFFROMROOT) || (axis == Axis.ATTRIBUTE))
// return true;
// }
// return false;
// }
// }
// else
// return false;
// }
// return true;
// }
// return false;
// }
/**
* This function is used to perform some extra analysis of the iterator.
*
* @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);
int analysis = getAnalysisBits();
if(WalkerFactory.isNaturalDocOrder(analysis))
{
m_inNaturalOrderStatic = true;
}
else
{
m_inNaturalOrderStatic = false;
// System.out.println("Setting natural doc order to false: "+
// WalkerFactory.getAnalysisString(analysis));
}
}
}