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	/*
	* Copyright (c) 2017, 2020, Oracle and/or its affiliates. All rights reserved.
	*/
	/*
	* 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.
	*/

	package com.sun.org.apache.xpath.internal.axes;

	import com.sun.org.apache.xml.internal.dtm.Axis;
	import com.sun.org.apache.xml.internal.dtm.DTM;
	import com.sun.org.apache.xml.internal.dtm.DTMIterator;
	import com.sun.org.apache.xml.internal.utils.QName;
	import com.sun.org.apache.xpath.internal.Expression;
	import com.sun.org.apache.xpath.internal.ExpressionOwner;
	import com.sun.org.apache.xpath.internal.XPathVisitor;
	import com.sun.org.apache.xpath.internal.compiler.Compiler;
	import com.sun.org.apache.xpath.internal.compiler.OpCodes;
	import com.sun.org.apache.xpath.internal.compiler.OpMap;
	import java.util.List;

	/**
	* This class extends NodeSetDTM, which implements DTMIterator,
	* and fetches nodes one at a time in document order based on a XPath
	* <a href="http://www.w3.org/TR/xpath#NT-UnionExpr">UnionExpr</a>.
	* As each node is iterated via nextNode(), the node is also stored
	* in the NodeVector, so that previousNode() can easily be done.
	* @xsl.usage advanced
	* @LastModified: May 2020
	*/
	public class UnionPathIterator extends LocPathIterator
	implements Cloneable, DTMIterator, java.io.Serializable, PathComponent
	{
	static final long serialVersionUID = -3910351546843826781L;

	/**
	* Constructor to create an instance which you can add location paths to.
	*/
	public UnionPathIterator()
	{

	super();

	// m_mutable = false;
	// m_cacheNodes = false;
	m_iterators = null;
	m_exprs = null;
	}

	/**
	* 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);

	try
	{
	if (null != m_exprs)
	{
	int n = m_exprs.length;
	DTMIterator newIters[] = new DTMIterator[n];

	for (int i = 0; i < n; i++)
	{
	DTMIterator iter = m_exprs[i].asIterator(m_execContext, context);
	newIters[i] = iter;
	iter.nextNode();
	}
	m_iterators = newIters;
	}
	}
	catch(Exception e)
	{
	throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(e);
	}
	}

	/**
	* Add an iterator to the union list.
	*
	* @param expr non-null reference to a location path iterator.
	*/
	public void addIterator(DTMIterator expr)
	{

	// Increase array size by only 1 at a time. Fix this
	// if it looks to be a problem.
	if (null == m_iterators)
	{
	m_iterators = new DTMIterator[1];
	m_iterators[0] = expr;
	}
	else
	{
	DTMIterator[] exprs = m_iterators;
	int len = m_iterators.length;

	m_iterators = new DTMIterator[len + 1];

	System.arraycopy(exprs, 0, m_iterators, 0, len);

	m_iterators[len] = expr;
	}
	expr.nextNode();
	if(expr instanceof Expression)
	((Expression)expr).exprSetParent(this);
	}

	/**
	* Detaches the iterator from the set which it iterated over, releasing
	* any computational resources and placing the iterator in the INVALID
	* state. After<code>detach</code> has been invoked, calls to
	* <code>nextNode</code> or<code>previousNode</code> will raise the
	* exception INVALID_STATE_ERR.
	*/
	public void detach()
	{
	if(m_allowDetach && null != m_iterators){
	int n = m_iterators.length;
	for(int i = 0; i < n; i++)
	{
	m_iterators[i].detach();
	}
	m_iterators = null;
	}
	}


	/**
	* Create a UnionPathIterator object, including creation
	* of location path iterators 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.
	*
	* @throws javax.xml.transform.TransformerException
	*/
	public UnionPathIterator(Compiler compiler, int opPos)
	throws javax.xml.transform.TransformerException
	{

	super();

	opPos = OpMap.getFirstChildPos(opPos);

	loadLocationPaths(compiler, opPos, 0);
	}

	/**
	* This will return an iterator capable of handling the union of paths given.
	*
	* @param compiler The Compiler which is creating
	* this expression.
	* @param opPos The position of this iterator in the
	* opcode list from the compiler.
	*
	* @return Object that is derived from LocPathIterator.
	*
	* @throws javax.xml.transform.TransformerException
	*/
	public static LocPathIterator createUnionIterator(Compiler compiler, int opPos)
	throws javax.xml.transform.TransformerException
	{
	// For the moment, I'm going to first create a full UnionPathIterator, and
	// then see if I can reduce it to a UnionChildIterator. It would obviously
	// be more effecient to just test for the conditions for a UnionChildIterator,
	// and then create that directly.
	UnionPathIterator upi = new UnionPathIterator(compiler, opPos);
	int nPaths = upi.m_exprs.length;
	boolean isAllChildIterators = true;
	for(int i = 0; i < nPaths; i++)
	{
	LocPathIterator lpi = upi.m_exprs[i];

	if(lpi.getAxis() != Axis.CHILD)
	{
	isAllChildIterators = false;
	break;
	}
	else
	{
	// check for positional predicates or position function, which won't work.
	if(HasPositionalPredChecker.check(lpi))
	{
	isAllChildIterators = false;
	break;
	}
	}
	}
	if(isAllChildIterators)
	{
	UnionChildIterator uci = new UnionChildIterator();

	for(int i = 0; i < nPaths; i++)
	{
	PredicatedNodeTest lpi = upi.m_exprs[i];
	// I could strip the lpi down to a pure PredicatedNodeTest, but
	// I don't think it's worth it. Note that the test can be used
	// as a static object... so it doesn't have to be cloned.
	uci.addNodeTest(lpi);
	}
	return uci;

	}
	else
	return upi;
	}

	/**
	* Get the analysis bits for this walker, as defined in the WalkerFactory.
	* @return One of WalkerFactory#BIT_DESCENDANT, etc.
	*/
	public int getAnalysisBits()
	{
	int bits = 0;

	if (m_exprs != null)
	{
	int n = m_exprs.length;

	for (int i = 0; i < n; i++)
	{
	int bit = m_exprs[i].getAnalysisBits();
	bits \|= bit;
	}
	}

	return bits;
	}

	/**
	* Read the object from a serialization stream.
	*
	* @param stream Input stream to read from
	*
	* @throws java.io.IOException in case of any IO related exceptions
	* @throws ClassNotFoundException if Class of the serialized object cannot be found
	*/
	private void readObject(java.io.ObjectInputStream stream)
	throws java.io.IOException, ClassNotFoundException
	{
	stream.defaultReadObject();
	m_clones = new IteratorPool(this);
	}

	/**
	* Get a cloned LocPathIterator that holds the same
	* position as this iterator.
	*
	* @return A clone of this iterator that holds the same node position.
	*
	* @throws CloneNotSupportedException
	*/
	public Object clone() throws CloneNotSupportedException
	{

	UnionPathIterator clone = (UnionPathIterator) super.clone();
	if (m_iterators != null)
	{
	int n = m_iterators.length;

	clone.m_iterators = new DTMIterator[n];

	for (int i = 0; i < n; i++)
	{
	clone.m_iterators[i] = (DTMIterator)m_iterators[i].clone();
	}
	}

	return clone;
	}


	/**
	* Create a new location path iterator.
	*
	* @param compiler The Compiler which is creating
	* this expression.
	* @param opPos The position of this iterator in the
	*
	* @return New location path iterator.
	*
	* @throws javax.xml.transform.TransformerException
	*/
	protected LocPathIterator createDTMIterator(
	Compiler compiler, int opPos) throws javax.xml.transform.TransformerException
	{
	LocPathIterator lpi = (LocPathIterator)WalkerFactory.newDTMIterator(compiler, opPos,
	(compiler.getLocationPathDepth() <= 0));
	return lpi;
	}

	/**
	* Initialize the location path iterators. Recursive.
	*
	* @param compiler The Compiler which is creating
	* this expression.
	* @param opPos The position of this iterator in the
	* opcode list from the compiler.
	* @param count The insert position of the iterator.
	*
	* @throws javax.xml.transform.TransformerException
	*/
	protected void loadLocationPaths(Compiler compiler, int opPos, int count)
	throws javax.xml.transform.TransformerException
	{

	// TODO: Handle unwrapped FilterExpr
	int steptype = compiler.getOp(opPos);

	if (steptype == OpCodes.OP_LOCATIONPATH)
	{
	loadLocationPaths(compiler, compiler.getNextOpPos(opPos), count + 1);

	m_exprs[count] = createDTMIterator(compiler, opPos);
	m_exprs[count].exprSetParent(this);
	}
	else
	{

	// Have to check for unwrapped functions, which the LocPathIterator
	// doesn't handle.
	switch (steptype)
	{
	case OpCodes.OP_VARIABLE :
	case OpCodes.OP_EXTFUNCTION :
	case OpCodes.OP_FUNCTION :
	case OpCodes.OP_GROUP :
	loadLocationPaths(compiler, compiler.getNextOpPos(opPos), count + 1);

	WalkingIterator iter =
	new WalkingIterator(compiler.getNamespaceContext());
	iter.exprSetParent(this);

	if(compiler.getLocationPathDepth() <= 0)
	iter.setIsTopLevel(true);

	iter.m_firstWalker = new com.sun.org.apache.xpath.internal.axes.FilterExprWalker(iter);

	iter.m_firstWalker.init(compiler, opPos, steptype);

	m_exprs[count] = iter;
	break;
	default :
	m_exprs = new LocPathIterator[count];
	}
	}
	}

	/**
	* Returns the next node in the set and advances the position of the
	* iterator in the set. After a DTMIterator is created, the first call
	* to nextNode() returns the first node in the set.
	* @return The next <code>Node</code> in the set being iterated over, or
	* <code>null</code> if there are no more members in that set.
	*/
	public int nextNode()
	{
	if(m_foundLast)
	return DTM.NULL;

	// Loop through the iterators getting the current fetched
	// node, and get the earliest occuring in document order
	int earliestNode = DTM.NULL;

	if (null != m_iterators)
	{
	int n = m_iterators.length;
	int iteratorUsed = -1;

	for (int i = 0; i < n; i++)
	{
	int node = m_iterators[i].getCurrentNode();

	if (DTM.NULL == node)
	continue;
	else if (DTM.NULL == earliestNode)
	{
	iteratorUsed = i;
	earliestNode = node;
	}
	else
	{
	if (node == earliestNode)
	{

	// Found a duplicate, so skip past it.
	m_iterators[i].nextNode();
	}
	else
	{
	DTM dtm = getDTM(node);

	if (dtm.isNodeAfter(node, earliestNode))
	{
	iteratorUsed = i;
	earliestNode = node;
	}
	}
	}
	}

	if (DTM.NULL != earliestNode)
	{
	m_iterators[iteratorUsed].nextNode();

	incrementCurrentPos();
	}
	else
	m_foundLast = true;
	}

	m_lastFetched = earliestNode;

	return earliestNode;
	}

	/**
	* This function is used to fixup variables from QNames to stack frame
	* indexes at stylesheet build time.
	* @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(List<QName> vars, int globalsSize)
	{
	for (int i = 0; i < m_exprs.length; i++)
	{
	m_exprs[i].fixupVariables(vars, globalsSize);
	}

	}

	/**
	* The location path iterators, one for each
	* <a href="http://www.w3.org/TR/xpath#NT-LocationPath">location
	* path</a> contained in the union expression.
	* @serial
	*/
	protected LocPathIterator[] m_exprs;


	/**
	* The location path iterators, one for each
	* <a href="http://www.w3.org/TR/xpath#NT-LocationPath">location
	* path</a> contained in the union expression.
	* @serial
	*/
	protected DTMIterator[] m_iterators;

	/**
	* 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()
	{
	// Could be smarter.
	return -1;
	}

	class iterOwner implements ExpressionOwner
	{
	int m_index;

	iterOwner(int index)
	{
	m_index = index;
	}

	/**
	* @see ExpressionOwner#getExpression()
	*/
	public Expression getExpression()
	{
	return m_exprs[m_index];
	}

	/**
	* @see ExpressionOwner#setExpression(Expression)
	*/
	public void setExpression(Expression exp)
	{

	if(!(exp instanceof LocPathIterator))
	{
	// Yuck. Need FilterExprIter. Or make it so m_exprs can be just
	// plain expressions?
	WalkingIterator wi = new WalkingIterator(getPrefixResolver());
	FilterExprWalker few = new FilterExprWalker(wi);
	wi.setFirstWalker(few);
	few.setInnerExpression(exp);
	wi.exprSetParent(UnionPathIterator.this);
	few.exprSetParent(wi);
	exp.exprSetParent(few);
	exp = wi;
	}
	else
	exp.exprSetParent(UnionPathIterator.this);
	m_exprs[m_index] = (LocPathIterator)exp;
	}

	}

	/**
	* @see com.sun.org.apache.xpath.internal.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
	*/
	public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
	{
	if(visitor.visitUnionPath(owner, this))
	{
	if(null != m_exprs)
	{
	int n = m_exprs.length;
	for(int i = 0; i < n; i++)
	{
	m_exprs[i].callVisitors(new iterOwner(i), visitor);
	}
	}
	}
	}

	/**
	* @see Expression#deepEquals(Expression)
	*/
	public boolean deepEquals(Expression expr)
	{
	if (!super.deepEquals(expr))
	return false;

	UnionPathIterator upi = (UnionPathIterator) expr;

	if (null != m_exprs)
	{
	int n = m_exprs.length;

	if((null == upi.m_exprs) \|\| (upi.m_exprs.length != n))
	return false;

	for (int i = 0; i < n; i++)
	{
	if(!m_exprs[i].deepEquals(upi.m_exprs[i]))
	return false;
	}
	}
	else if (null != upi.m_exprs)
	{
	return false;
	}

	return true;
	}


	}

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