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	/*
	* Copyright (c) 2017, 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.DTM;
	import com.sun.org.apache.xml.internal.utils.PrefixResolver;
	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.VariableStack;
	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.OpMap;
	import java.util.List;

	/**
	* Location path iterator that uses Walkers.
	*
	* @LastModified: Oct 2017
	*/

	public class WalkingIterator extends LocPathIterator implements ExpressionOwner
	{
	static final long serialVersionUID = 9110225941815665906L;
	/**
	* 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
	*/
	WalkingIterator(
	Compiler compiler, int opPos, int analysis, boolean shouldLoadWalkers)
	throws javax.xml.transform.TransformerException
	{
	super(compiler, opPos, analysis, shouldLoadWalkers);

	int firstStepPos = OpMap.getFirstChildPos(opPos);

	if (shouldLoadWalkers)
	{
	m_firstWalker = WalkerFactory.loadWalkers(this, compiler, firstStepPos, 0);
	m_lastUsedWalker = m_firstWalker;
	}
	}

	/**
	* Create a WalkingIterator object.
	*
	* @param nscontext The namespace context for this iterator,
	* should be OK if null.
	*/
	public WalkingIterator(PrefixResolver nscontext)
	{

	super(nscontext);
	}


	/**
	* 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 (null != m_firstWalker)
	{
	AxesWalker walker = m_firstWalker;

	while (null != walker)
	{
	int bit = walker.getAnalysisBits();
	bits \|= bit;
	walker = walker.getNextWalker();
	}
	}
	return bits;
	}

	/**
	* Get a cloned WalkingIterator 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
	{

	WalkingIterator clone = (WalkingIterator) super.clone();

	// clone.m_varStackPos = this.m_varStackPos;
	// clone.m_varStackContext = this.m_varStackContext;
	if (null != m_firstWalker)
	{
	clone.m_firstWalker = m_firstWalker.cloneDeep(clone, null);
	}

	return clone;
	}

	/**
	* Reset the iterator.
	*/
	public void reset()
	{

	super.reset();

	if (null != m_firstWalker)
	{
	m_lastUsedWalker = m_firstWalker;

	m_firstWalker.setRoot(m_context);
	}

	}

	/**
	* 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);

	if(null != m_firstWalker)
	{
	m_firstWalker.setRoot(context);
	m_lastUsedWalker = m_firstWalker;
	}
	}

	/**
	* 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 <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;

	// If the variable stack position is not -1, we'll have to
	// set our position in the variable stack, so our variable access
	// will be correct. Iterators that are at the top level of the
	// expression need to reset the variable stack, while iterators
	// in predicates do not need to, and should not, since their execution
	// may be much later than top-level iterators.
	// m_varStackPos is set in setRoot, which is called
	// from the execute method.
	if (-1 == m_stackFrame)
	{
	return returnNextNode(m_firstWalker.nextNode());
	}
	else
	{
	VariableStack vars = m_execContext.getVarStack();

	// These three statements need to be combined into one operation.
	int savedStart = vars.getStackFrame();

	vars.setStackFrame(m_stackFrame);

	int n = returnNextNode(m_firstWalker.nextNode());

	// These two statements need to be combined into one operation.
	vars.setStackFrame(savedStart);

	return n;
	}
	}


	/**
	* Get the head of the walker list.
	*
	* @return The head of the walker list, or null
	* if this iterator does not implement walkers.
	* @xsl.usage advanced
	*/
	public final AxesWalker getFirstWalker()
	{
	return m_firstWalker;
	}

	/**
	* Set the head of the walker list.
	*
	* @param walker Should be a valid AxesWalker.
	* @xsl.usage advanced
	*/
	public final void setFirstWalker(AxesWalker walker)
	{
	m_firstWalker = walker;
	}


	/**
	* Set the last used walker.
	*
	* @param walker The last used walker, or null.
	* @xsl.usage advanced
	*/
	public final void setLastUsedWalker(AxesWalker walker)
	{
	m_lastUsedWalker = walker;
	}

	/**
	* Get the last used walker.
	*
	* @return The last used walker, or null.
	* @xsl.usage advanced
	*/
	public final AxesWalker getLastUsedWalker()
	{
	return m_lastUsedWalker;
	}

	/**
	* 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)
	{
	AxesWalker walker = m_firstWalker;
	while (null != walker)
	{
	walker.detach();
	walker = walker.getNextWalker();
	}

	m_lastUsedWalker = null;

	// Always call the superclass detach last!
	super.detach();
	}
	}

	/**
	* 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)
	{
	m_predicateIndex = -1;

	AxesWalker walker = m_firstWalker;

	while (null != walker)
	{
	walker.fixupVariables(vars, globalsSize);
	walker = walker.getNextWalker();
	}
	}

	/**
	* @see com.sun.org.apache.xpath.internal.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
	*/
	public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
	{
	if(visitor.visitLocationPath(owner, this))
	{
	if(null != m_firstWalker)
	{
	m_firstWalker.callVisitors(this, visitor);
	}
	}
	}


	/** The last used step walker in the walker list.
	* @serial */
	protected AxesWalker m_lastUsedWalker;

	/** The head of the step walker list.
	* @serial */
	protected AxesWalker m_firstWalker;

	/**
	* @see ExpressionOwner#getExpression()
	*/
	public Expression getExpression()
	{
	return m_firstWalker;
	}

	/**
	* @see ExpressionOwner#setExpression(Expression)
	*/
	public void setExpression(Expression exp)
	{
	exp.exprSetParent(this);
	m_firstWalker = (AxesWalker)exp;
	}

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

	AxesWalker walker1 = m_firstWalker;
	AxesWalker walker2 = ((WalkingIterator)expr).m_firstWalker;
	while ((null != walker1) && (null != walker2))
	{
	if(!walker1.deepEquals(walker2))
	return false;
	walker1 = walker1.getNextWalker();
	walker2 = walker2.getNextWalker();
	}

	if((null != walker1) \|\| (null != walker2))
	return false;

	return true;
	}

	}

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