org.apache.xpath.axes.DescendantIterator 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: DescendantIterator.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.DTMFilter;
import org.apache.xml.dtm.DTMIterator;
import org.apache.xpath.Expression;
import org.apache.xpath.XPathContext;
import org.apache.xpath.compiler.Compiler;
import org.apache.xpath.compiler.OpCodes;
import org.apache.xpath.compiler.OpMap;
import org.apache.xpath.patterns.NodeTest;
/**
* This class implements an optimized iterator for
* descendant, descendant-or-self, or "//foo" patterns.
* @see org.apache.xpath.axes.LocPathIterator
* @xsl.usage advanced
*/
public class DescendantIterator extends LocPathIterator
{
static final long serialVersionUID = -1190338607743976938L;
/**
* Create a DescendantIterator object.
*
* @param compiler A reference to the Compiler that contains the op map.
* @param opPos The position within the op map, which contains the
* location path expression for this itterator.
*
* @throws javax.xml.transform.TransformerException
*/
DescendantIterator(Compiler compiler, int opPos, int analysis)
throws javax.xml.transform.TransformerException
{
super(compiler, opPos, analysis, false);
int firstStepPos = OpMap.getFirstChildPos(opPos);
int stepType = compiler.getOp(firstStepPos);
boolean orSelf = (OpCodes.FROM_DESCENDANTS_OR_SELF == stepType);
boolean fromRoot = false;
if (OpCodes.FROM_SELF == stepType)
{
orSelf = true;
// firstStepPos += 8;
}
else if(OpCodes.FROM_ROOT == stepType)
{
fromRoot = true;
// Ugly code... will go away when AST work is done.
int nextStepPos = compiler.getNextStepPos(firstStepPos);
if(compiler.getOp(nextStepPos) == OpCodes.FROM_DESCENDANTS_OR_SELF)
orSelf = true;
// firstStepPos += 8;
}
// Find the position of the last step.
int nextStepPos = firstStepPos;
while(true)
{
nextStepPos = compiler.getNextStepPos(nextStepPos);
if(nextStepPos > 0)
{
int stepOp = compiler.getOp(nextStepPos);
if(OpCodes.ENDOP != stepOp)
firstStepPos = nextStepPos;
else
break;
}
else
break;
}
// Fix for http://nagoya.apache.org/bugzilla/show_bug.cgi?id=1336
if((analysis & WalkerFactory.BIT_CHILD) != 0)
orSelf = false;
if(fromRoot)
{
if(orSelf)
m_axis = Axis.DESCENDANTSORSELFFROMROOT;
else
m_axis = Axis.DESCENDANTSFROMROOT;
}
else if(orSelf)
m_axis = Axis.DESCENDANTORSELF;
else
m_axis = Axis.DESCENDANT;
int whatToShow = compiler.getWhatToShow(firstStepPos);
if ((0 == (whatToShow
& (DTMFilter.SHOW_ATTRIBUTE | DTMFilter.SHOW_ELEMENT
| DTMFilter.SHOW_PROCESSING_INSTRUCTION))) ||
(whatToShow == DTMFilter.SHOW_ALL))
initNodeTest(whatToShow);
else
{
initNodeTest(whatToShow, compiler.getStepNS(firstStepPos),
compiler.getStepLocalName(firstStepPos));
}
initPredicateInfo(compiler, firstStepPos);
}
/**
* Create a DescendantIterator object.
*
*/
public DescendantIterator()
{
super(null);
m_axis = Axis.DESCENDANTSORSELFFROMROOT;
int whatToShow = DTMFilter.SHOW_ALL;
initNodeTest(whatToShow);
}
/**
* Get a cloned Iterator that is reset to the beginning
* of the query.
*
* @return A cloned NodeIterator set of the start of the query.
*
* @throws CloneNotSupportedException
*/
public DTMIterator cloneWithReset() throws CloneNotSupportedException
{
DescendantIterator clone = (DescendantIterator) super.cloneWithReset();
clone.m_traverser = m_traverser;
clone.resetProximityPositions();
return clone;
}
/**
* 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.
*
* @throws DOMException
* INVALID_STATE_ERR: Raised if this method is called after the
* detach method was invoked.
*/
public int nextNode()
{
if(m_foundLast)
return DTM.NULL;
if(DTM.NULL == m_lastFetched)
{
resetProximityPositions();
}
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
{
do
{
if(0 == m_extendedTypeID)
{
next = m_lastFetched = (DTM.NULL == m_lastFetched)
? m_traverser.first(m_context)
: m_traverser.next(m_context, m_lastFetched);
}
else
{
next = m_lastFetched = (DTM.NULL == m_lastFetched)
? m_traverser.first(m_context, m_extendedTypeID)
: m_traverser.next(m_context, m_lastFetched,
m_extendedTypeID);
}
if (DTM.NULL != next)
{
if(DTMIterator.FILTER_ACCEPT == acceptNode(next))
break;
else
continue;
}
else
break;
}
while (next != DTM.NULL);
if (DTM.NULL != next)
{
m_pos++;
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);
}
}
}
/**
* 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_axis);
String localName = getLocalName();
String namespace = getNamespace();
int what = m_whatToShow;
// System.out.println("what: ");
// NodeTest.debugWhatToShow(what);
if(DTMFilter.SHOW_ALL == what
|| NodeTest.WILD.equals(localName)
|| NodeTest.WILD.equals(namespace))
{
m_extendedTypeID = 0;
}
else
{
int type = getNodeTypeTest(what);
m_extendedTypeID = m_cdtm.getExpandedTypeID(namespace, localName, type);
}
}
/**
* Return the first node out of the nodeset, if this expression is
* a nodeset expression. This is the default implementation for
* nodesets.
* WARNING: Do not mutate this class from this function!
* @param xctxt The XPath runtime context.
* @return the first node out of the nodeset, or DTM.NULL.
*/
public int asNode(XPathContext xctxt)
throws javax.xml.transform.TransformerException
{
if(getPredicateCount() > 0)
return super.asNode(xctxt);
int current = xctxt.getCurrentNode();
DTM dtm = xctxt.getDTM(current);
DTMAxisTraverser traverser = dtm.getAxisTraverser(m_axis);
String localName = getLocalName();
String namespace = getNamespace();
int what = m_whatToShow;
// System.out.print(" (DescendantIterator) ");
// System.out.println("what: ");
// NodeTest.debugWhatToShow(what);
if(DTMFilter.SHOW_ALL == what
|| localName == NodeTest.WILD
|| namespace == NodeTest.WILD)
{
return traverser.first(current);
}
else
{
int type = getNodeTypeTest(what);
int extendedType = dtm.getExpandedTypeID(namespace, localName, type);
return traverser.first(current, extendedType);
}
}
/**
* 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;
m_extendedTypeID = 0;
// Always call the superclass detach last!
super.detach();
}
}
/**
* 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_axis;
}
/** The traverser to use to navigate over the descendants. */
transient protected DTMAxisTraverser m_traverser;
/** The axis that we are traversing. */
protected int m_axis;
/** The extended type ID, not set until setRoot. */
protected int m_extendedTypeID;
/**
* @see Expression#deepEquals(Expression)
*/
public boolean deepEquals(Expression expr)
{
if(!super.deepEquals(expr))
return false;
if(m_axis != ((DescendantIterator)expr).m_axis)
return false;
return true;
}
}