/*
* 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: MatchPatternIterator.java 469314 2006-10-30 23:31:59Z minchau $
*/
package org.apache.xpath.axes;
import org.apache.xml.dtm.Axis;
import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMAxisTraverser;
import org.apache.xml.dtm.DTMIterator;
import org.apache.xpath.XPathContext;
import org.apache.xpath.compiler.Compiler;
import org.apache.xpath.compiler.OpMap;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.patterns.NodeTest;
import org.apache.xpath.patterns.StepPattern;
/**
* This class treats a
* LocationPath as a
* filtered iteration over the tree, evaluating each node in a super axis
* traversal against the LocationPath interpreted as a match pattern. This
* class is useful to find nodes in document order that are complex paths
* whose steps probably criss-cross each other.
*/
public class MatchPatternIterator extends LocPathIterator
{
static final long serialVersionUID = -5201153767396296474L;
/** This is the select pattern, translated into a match pattern. */
protected StepPattern m_pattern;
/** The traversal axis from where the nodes will be filtered. */
protected int m_superAxis = -1;
/** The DTM inner traversal class, that corresponds to the super axis. */
protected DTMAxisTraverser m_traverser;
/** DEBUG flag for diagnostic dumps. */
private static final boolean DEBUG = false;
// protected int m_nsElemBase = DTM.NULL;
/**
* Create a LocPathIterator object, 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 analysis Analysis bits that give general information about the
* LocationPath.
*
* @throws javax.xml.transform.TransformerException
*/
MatchPatternIterator(Compiler compiler, int opPos, int analysis)
throws javax.xml.transform.TransformerException
{
super(compiler, opPos, analysis, false);
int firstStepPos = OpMap.getFirstChildPos(opPos);
m_pattern = WalkerFactory.loadSteps(this, compiler, firstStepPos, 0);
boolean fromRoot = false;
boolean walkBack = false;
boolean walkDescendants = false;
boolean walkAttributes = false;
if (0 != (analysis & (WalkerFactory.BIT_ROOT |
WalkerFactory.BIT_ANY_DESCENDANT_FROM_ROOT)))
fromRoot = true;
if (0 != (analysis
& (WalkerFactory.BIT_ANCESTOR
| WalkerFactory.BIT_ANCESTOR_OR_SELF
| WalkerFactory.BIT_PRECEDING
| WalkerFactory.BIT_PRECEDING_SIBLING
| WalkerFactory.BIT_FOLLOWING
| WalkerFactory.BIT_FOLLOWING_SIBLING
| WalkerFactory.BIT_PARENT | WalkerFactory.BIT_FILTER)))
walkBack = true;
if (0 != (analysis
& (WalkerFactory.BIT_DESCENDANT_OR_SELF
| WalkerFactory.BIT_DESCENDANT
| WalkerFactory.BIT_CHILD)))
walkDescendants = true;
if (0 != (analysis
& (WalkerFactory.BIT_ATTRIBUTE | WalkerFactory.BIT_NAMESPACE)))
walkAttributes = true;
if(false || DEBUG)
{
System.out.print("analysis: "+Integer.toBinaryString(analysis));
System.out.println(", "+WalkerFactory.getAnalysisString(analysis));
}
if(fromRoot || walkBack)
{
if(walkAttributes)
{
m_superAxis = Axis.ALL;
}
else
{
m_superAxis = Axis.DESCENDANTSFROMROOT;
}
}
else if(walkDescendants)
{
if(walkAttributes)
{
m_superAxis = Axis.ALLFROMNODE;
}
else
{
m_superAxis = Axis.DESCENDANTORSELF;
}
}
else
{
m_superAxis = Axis.ALL;
}
if(false || DEBUG)
{
System.out.println("axis: "+Axis.getNames(m_superAxis));
}
}
/**
* 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_traverser = m_cdtm.getAxisTraverser(m_superAxis);
}
/**
* Detaches the iterator from the set which it iterated over, releasing
* any computational resources and placing the iterator in the INVALID
* state. Afterdetach has been invoked, calls to
* nextNode orpreviousNode will raise the
* exception INVALID_STATE_ERR.
*/
public void detach()
{
if(m_allowDetach)
{
m_traverser = null;
// Always call the superclass detach last!
super.detach();
}
}
/**
* Get the next node via getNextXXX. Bottlenecked for derived class override.
* @return The next node on the axis, or DTM.NULL.
*/
protected int getNextNode()
{
m_lastFetched = (DTM.NULL == m_lastFetched)
? m_traverser.first(m_context)
: m_traverser.next(m_context, m_lastFetched);
return m_lastFetched;
}
/**
* Returns the next node in the set and advances the position of the
* iterator in the set. After a NodeIterator is created, the first call
* to nextNode() returns the first node in the set.
* @return The next Node in the set being iterated over, or
* null if there are no more members in that set.
*/
public int nextNode()
{
if(m_foundLast)
return DTM.NULL;
int next;
org.apache.xpath.VariableStack vars;
int savedStart;
if (-1 != m_stackFrame)
{
vars = m_execContext.getVarStack();
// These three statements need to be combined into one operation.
savedStart = vars.getStackFrame();
vars.setStackFrame(m_stackFrame);
}
else
{
// Yuck. Just to shut up the compiler!
vars = null;
savedStart = 0;
}
try
{
if(DEBUG)
System.out.println("m_pattern"+m_pattern.toString());
do
{
next = getNextNode();
if (DTM.NULL != next)
{
if(DTMIterator.FILTER_ACCEPT == acceptNode(next, m_execContext))
break;
else
continue;
}
else
break;
}
while (next != DTM.NULL);
if (DTM.NULL != next)
{
if(DEBUG)
{
System.out.println("next: "+next);
System.out.println("name: "+m_cdtm.getNodeName(next));
}
incrementCurrentPos();
return next;
}
else
{
m_foundLast = true;
return DTM.NULL;
}
}
finally
{
if (-1 != m_stackFrame)
{
// These two statements need to be combined into one operation.
vars.setStackFrame(savedStart);
}
}
}
/**
* Test whether a specified node is visible in the logical view of a
* TreeWalker or NodeIterator. This function will be called by the
* implementation of TreeWalker and NodeIterator; it is not intended to
* be called directly from user code.
* @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, XPathContext xctxt)
{
try
{
xctxt.pushCurrentNode(n);
xctxt.pushIteratorRoot(m_context);
if(DEBUG)
{
System.out.println("traverser: "+m_traverser);
System.out.print("node: "+n);
System.out.println(", "+m_cdtm.getNodeName(n));
// if(m_cdtm.getNodeName(n).equals("near-east"))
System.out.println("pattern: "+m_pattern.toString());
m_pattern.debugWhatToShow(m_pattern.getWhatToShow());
}
XObject score = m_pattern.execute(xctxt);
if(DEBUG)
{
// System.out.println("analysis: "+Integer.toBinaryString(m_analysis));
System.out.println("score: "+score);
System.out.println("skip: "+(score == NodeTest.SCORE_NONE));
}
// System.out.println("\n::acceptNode - score: "+score.num()+"::");
return (score == NodeTest.SCORE_NONE) ? DTMIterator.FILTER_SKIP
: DTMIterator.FILTER_ACCEPT;
}
catch (javax.xml.transform.TransformerException se)
{
// TODO: Fix this.
throw new RuntimeException(se.getMessage());
}
finally
{
xctxt.popCurrentNode();
xctxt.popIteratorRoot();
}
}
}