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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.dtm.DTMFilter;
	import com.sun.org.apache.xml.internal.dtm.DTMIterator;
	import com.sun.org.apache.xml.internal.dtm.DTMManager;
	import com.sun.org.apache.xml.internal.utils.NodeVector;
	import com.sun.org.apache.xml.internal.utils.QName;
	import com.sun.org.apache.xpath.internal.NodeSetDTM;
	import com.sun.org.apache.xpath.internal.XPathContext;
	import com.sun.org.apache.xpath.internal.objects.XObject;
	import java.util.List;

	/**
	* This class is the dynamic wrapper for a Xalan DTMIterator instance, and
	* provides random access capabilities.
	*
	* @LastModified: Oct 2017
	*/
	public class NodeSequence extends XObject
	implements DTMIterator, Cloneable, PathComponent
	{
	static final long serialVersionUID = 3866261934726581044L;
	/** The index of the last node in the iteration. */
	protected int m_last = -1;

	/**
	* The index of the next node to be fetched. Useful if this
	* is a cached iterator, and is being used as random access
	* NodeList.
	*/
	protected int m_next = 0;

	/**
	* A cache of a list of nodes obtained from the iterator so far.
	* This list is appended to until the iterator is exhausted and
	* the cache is complete.
	* <p>
	* Multiple NodeSequence objects may share the same cache.
	*/
	private IteratorCache m_cache;

	/**
	* If this iterator needs to cache nodes that are fetched, they
	* are stored in the Vector in the generic object.
	*/
	protected NodeVector getVector() {
	NodeVector nv = (m_cache != null) ? m_cache.getVector() : null;
	return nv;
	}

	/**
	* Get the cache (if any) of nodes obtained from
	* the iterator so far. Note that the cache keeps
	* growing until the iterator is walked to exhaustion,
	* at which point the cache is "complete".
	*/
	private IteratorCache getCache() {
	return m_cache;
	}

	/**
	* Set the vector where nodes will be cached.
	*/
	protected void SetVector(NodeVector v)
	{
	setObject(v);
	}


	/**
	* If the iterator needs to cache nodes as they are fetched,
	* then this method returns true.
	*/
	public boolean hasCache()
	{
	final NodeVector nv = getVector();
	return (nv != null);
	}

	/**
	* If this NodeSequence has a cache, and that cache is
	* fully populated then this method returns true, otherwise
	* if there is no cache or it is not complete it returns false.
	*/
	private boolean cacheComplete() {
	final boolean complete;
	if (m_cache != null) {
	complete = m_cache.isComplete();
	} else {
	complete = false;
	}
	return complete;
	}

	/**
	* If this NodeSequence has a cache, mark that it is complete.
	* This method should be called after the iterator is exhausted.
	*/
	private void markCacheComplete() {
	NodeVector nv = getVector();
	if (nv != null) {
	m_cache.setCacheComplete(true);
	}
	}


	/**
	* The functional iterator that fetches nodes.
	*/
	protected DTMIterator m_iter;

	/**
	* Set the functional iterator that fetches nodes.
	* @param iter The iterator that is to be contained.
	*/
	public final void setIter(DTMIterator iter)
	{
	m_iter = iter;
	}

	/**
	* Get the functional iterator that fetches nodes.
	* @return The contained iterator.
	*/
	public final DTMIterator getContainedIter()
	{
	return m_iter;
	}

	/**
	* The DTMManager to use if we're using a NodeVector only.
	* We may well want to do away with this, and store it in the NodeVector.
	*/
	protected DTMManager m_dtmMgr;

	// ==== Constructors ====

	/**
	* Create a new NodeSequence from a (already cloned) iterator.
	*
	* @param iter Cloned (not static) DTMIterator.
	* @param context The initial context node.
	* @param xctxt The execution context.
	* @param shouldCacheNodes True if this sequence can random access.
	*/
	private NodeSequence(DTMIterator iter, int context, XPathContext xctxt, boolean shouldCacheNodes)
	{
	setIter(iter);
	setRoot(context, xctxt);
	setShouldCacheNodes(shouldCacheNodes);
	}

	/**
	* Create a new NodeSequence from a (already cloned) iterator.
	*
	* @param nodeVector
	*/
	public NodeSequence(Object nodeVector)
	{
	super(nodeVector);
	if (nodeVector instanceof NodeVector) {
	SetVector((NodeVector) nodeVector);
	}
	if(null != nodeVector)
	{
	assertion(nodeVector instanceof NodeVector,
	"Must have a NodeVector as the object for NodeSequence!");
	if(nodeVector instanceof DTMIterator)
	{
	setIter((DTMIterator)nodeVector);
	m_last = ((DTMIterator)nodeVector).getLength();
	}

	}
	}

	/**
	* Construct an empty XNodeSet object. This is used to create a mutable
	* nodeset to which random nodes may be added.
	*/
	private NodeSequence(DTMManager dtmMgr)
	{
	super(new NodeVector());
	m_last = 0;
	m_dtmMgr = dtmMgr;
	}


	/**
	* Create a new NodeSequence in an invalid (null) state.
	*/
	public NodeSequence()
	{
	return;
	}


	/**
	* @see DTMIterator#getDTM(int)
	*/
	public DTM getDTM(int nodeHandle)
	{
	DTMManager mgr = getDTMManager();
	if(null != mgr)
	return getDTMManager().getDTM(nodeHandle);
	else
	{
	assertion(false, "Can not get a DTM Unless a DTMManager has been set!");
	return null;
	}
	}

	/**
	* @see DTMIterator#getDTMManager()
	*/
	public DTMManager getDTMManager()
	{
	return m_dtmMgr;
	}

	/**
	* @see DTMIterator#getRoot()
	*/
	public int getRoot()
	{
	if(null != m_iter)
	return m_iter.getRoot();
	else
	{
	// NodeSetDTM will call this, and so it's not a good thing to throw
	// an assertion here.
	// assertion(false, "Can not get the root from a non-iterated NodeSequence!");
	return DTM.NULL;
	}
	}

	/**
	* @see DTMIterator#setRoot(int, Object)
	*/
	public void setRoot(int nodeHandle, Object environment)
	{
	// If root is DTM.NULL, then something's wrong with the context
	if (nodeHandle == DTM.NULL)
	{
	throw new RuntimeException("Unable to evaluate expression using " +
	"this context");
	}

	if(null != m_iter)
	{
	XPathContext xctxt = (XPathContext)environment;
	m_dtmMgr = xctxt.getDTMManager();
	m_iter.setRoot(nodeHandle, environment);
	if(!m_iter.isDocOrdered())
	{
	if(!hasCache())
	setShouldCacheNodes(true);
	runTo(-1);
	m_next=0;
	}
	}
	else
	assertion(false, "Can not setRoot on a non-iterated NodeSequence!");
	}

	/**
	* @see DTMIterator#reset()
	*/
	public void reset()
	{
	m_next = 0;
	// not resetting the iterator on purpose!!!
	}

	/**
	* @see DTMIterator#getWhatToShow()
	*/
	public int getWhatToShow()
	{
	return hasCache() ? (DTMFilter.SHOW_ALL & ~DTMFilter.SHOW_ENTITY_REFERENCE)
	: m_iter.getWhatToShow();
	}

	/**
	* @see DTMIterator#getExpandEntityReferences()
	*/
	public boolean getExpandEntityReferences()
	{
	if(null != m_iter)
	return m_iter.getExpandEntityReferences();
	else
	return true;
	}

	/**
	* @see DTMIterator#nextNode()
	*/
	public int nextNode()
	{
	// If the cache is on, and the node has already been found, then
	// just return from the list.
	NodeVector vec = getVector();
	if (null != vec)
	{
	// There is a cache
	if(m_next < vec.size())
	{
	// The node is in the cache, so just return it.
	int next = vec.elementAt(m_next);
	m_next++;
	return next;
	}
	else if(cacheComplete() \|\| (-1 != m_last) \|\| (null == m_iter))
	{
	m_next++;
	return DTM.NULL;
	}
	}

	if (null == m_iter)
	return DTM.NULL;

	int next = m_iter.nextNode();
	if(DTM.NULL != next)
	{
	if(hasCache())
	{
	if(m_iter.isDocOrdered())
	{
	getVector().addElement(next);
	m_next++;
	}
	else
	{
	int insertIndex = addNodeInDocOrder(next);
	if(insertIndex >= 0)
	m_next++;
	}
	}
	else
	m_next++;
	}
	else
	{
	// We have exhausted the iterator, and if there is a cache
	// it must have all nodes in it by now, so let the cache
	// know that it is complete.
	markCacheComplete();

	m_last = m_next;
	m_next++;
	}

	return next;
	}

	/**
	* @see DTMIterator#previousNode()
	*/
	public int previousNode()
	{
	if(hasCache())
	{
	if(m_next <= 0)
	return DTM.NULL;
	else
	{
	m_next--;
	return item(m_next);
	}
	}
	else
	{
	int n = m_iter.previousNode();
	m_next = m_iter.getCurrentPos();
	return m_next;
	}
	}

	/**
	* @see DTMIterator#detach()
	*/
	public void detach()
	{
	if(null != m_iter)
	m_iter.detach();
	super.detach();
	}

	/**
	* Calling this with a value of false will cause the nodeset
	* to be cached.
	* @see DTMIterator#allowDetachToRelease(boolean)
	*/
	public void allowDetachToRelease(boolean allowRelease)
	{
	if((false == allowRelease) && !hasCache())
	{
	setShouldCacheNodes(true);
	}

	if(null != m_iter)
	m_iter.allowDetachToRelease(allowRelease);
	super.allowDetachToRelease(allowRelease);
	}

	/**
	* @see DTMIterator#getCurrentNode()
	*/
	public int getCurrentNode()
	{
	if(hasCache())
	{
	int currentIndex = m_next-1;
	NodeVector vec = getVector();
	if((currentIndex >= 0) && (currentIndex < vec.size()))
	return vec.elementAt(currentIndex);
	else
	return DTM.NULL;
	}

	if(null != m_iter)
	{
	return m_iter.getCurrentNode();
	}
	else
	return DTM.NULL;
	}

	/**
	* @see DTMIterator#isFresh()
	*/
	public boolean isFresh()
	{
	return (0 == m_next);
	}

	/**
	* @see DTMIterator#setShouldCacheNodes(boolean)
	*/
	public void setShouldCacheNodes(boolean b)
	{
	if (b)
	{
	if(!hasCache())
	{
	SetVector(new NodeVector());
	}
	// else
	// getVector().RemoveAllNoClear(); // Is this good?
	}
	else
	SetVector(null);
	}

	/**
	* @see DTMIterator#isMutable()
	*/
	public boolean isMutable()
	{
	return hasCache(); // though may be surprising if it also has an iterator!
	}

	/**
	* @see DTMIterator#getCurrentPos()
	*/
	public int getCurrentPos()
	{
	return m_next;
	}

	/**
	* @see DTMIterator#runTo(int)
	*/
	public void runTo(int index)
	{
	int n;

	if (-1 == index)
	{
	int pos = m_next;
	while (DTM.NULL != (n = nextNode()));
	m_next = pos;
	}
	else if(m_next == index)
	{
	return;
	}
	else if(hasCache() && index < getVector().size())
	{
	m_next = index;
	}
	else if((null == getVector()) && (index < m_next))
	{
	while ((m_next >= index) && DTM.NULL != (n = previousNode()));
	}
	else
	{
	while ((m_next < index) && DTM.NULL != (n = nextNode()));
	}

	}

	/**
	* @see DTMIterator#setCurrentPos(int)
	*/
	public void setCurrentPos(int i)
	{
	runTo(i);
	}

	/**
	* @see DTMIterator#item(int)
	*/
	public int item(int index)
	{
	setCurrentPos(index);
	int n = nextNode();
	m_next = index;
	return n;
	}

	/**
	* @see DTMIterator#setItem(int, int)
	*/
	public void setItem(int node, int index)
	{
	NodeVector vec = getVector();
	if(null != vec)
	{
	int oldNode = vec.elementAt(index);
	if (oldNode != node && m_cache.useCount() > 1) {
	/* If we are going to set the node at the given index
	* to a different value, and the cache is shared
	* (has a use count greater than 1)
	* then make a copy of the cache and use it
	* so we don't overwrite the value for other
	* users of the cache.
	*/
	IteratorCache newCache = new IteratorCache();
	final NodeVector nv;
	try {
	nv = (NodeVector) vec.clone();
	} catch (CloneNotSupportedException e) {
	// This should never happen
	e.printStackTrace();
	RuntimeException rte = new RuntimeException(e.getMessage());
	throw rte;
	}
	newCache.setVector(nv);
	newCache.setCacheComplete(true);
	m_cache = newCache;
	vec = nv;

	// Keep our superclass informed of the current NodeVector
	super.setObject(nv);

	/* When we get to here the new cache has
	* a use count of 1 and when setting a
	* bunch of values on the same NodeSequence,
	* such as when sorting, we will keep setting
	* values in that same copy which has a use count of 1.
	*/
	}
	vec.setElementAt(node, index);
	m_last = vec.size();
	}
	else
	m_iter.setItem(node, index);
	}

	/**
	* @see DTMIterator#getLength()
	*/
	public int getLength()
	{
	IteratorCache cache = getCache();

	if(cache != null)
	{
	// Nodes from the iterator are cached
	if (cache.isComplete()) {
	// All of the nodes from the iterator are cached
	// so just return the number of nodes in the cache
	NodeVector nv = cache.getVector();
	return nv.size();
	}

	// If this NodeSequence wraps a mutable nodeset, then
	// m_last will not reflect the size of the nodeset if
	// it has been mutated...
	if (m_iter instanceof NodeSetDTM)
	{
	return m_iter.getLength();
	}

	if(-1 == m_last)
	{
	int pos = m_next;
	runTo(-1);
	m_next = pos;
	}
	return m_last;
	}
	else
	{
	return (-1 == m_last) ? (m_last = m_iter.getLength()) : m_last;
	}
	}

	/**
	* Note: Not a deep clone.
	* @see DTMIterator#cloneWithReset()
	*/
	public DTMIterator cloneWithReset() throws CloneNotSupportedException
	{
	NodeSequence seq = (NodeSequence)super.clone();
	seq.m_next = 0;
	if (m_cache != null) {
	// In making this clone of an iterator we are making
	// another NodeSequence object it has a reference
	// to the same IteratorCache object as the original
	// so we need to remember that more than one
	// NodeSequence object shares the cache.
	m_cache.increaseUseCount();
	}

	return seq;
	}

	/**
	* Get a clone of this iterator, but don't reset the iteration in the
	* process, so that it may be used from the current position.
	* Note: Not a deep clone.
	*
	* @return A clone of this object.
	*
	* @throws CloneNotSupportedException
	*/
	public Object clone() throws CloneNotSupportedException
	{
	NodeSequence clone = (NodeSequence) super.clone();
	if (null != m_iter) clone.m_iter = (DTMIterator) m_iter.clone();
	if (m_cache != null) {
	// In making this clone of an iterator we are making
	// another NodeSequence object it has a reference
	// to the same IteratorCache object as the original
	// so we need to remember that more than one
	// NodeSequence object shares the cache.
	m_cache.increaseUseCount();
	}

	return clone;
	}


	/**
	* @see DTMIterator#isDocOrdered()
	*/
	public boolean isDocOrdered()
	{
	if(null != m_iter)
	return m_iter.isDocOrdered();
	else
	return true; // can't be sure?
	}

	/**
	* @see DTMIterator#getAxis()
	*/
	public int getAxis()
	{
	if(null != m_iter)
	return m_iter.getAxis();
	else
	{
	assertion(false, "Can not getAxis from a non-iterated node sequence!");
	return 0;
	}
	}

	/**
	* @see PathComponent#getAnalysisBits()
	*/
	public int getAnalysisBits()
	{
	if((null != m_iter) && (m_iter instanceof PathComponent))
	return ((PathComponent)m_iter).getAnalysisBits();
	else
	return 0;
	}

	/**
	* @see org.apache.xpath.Expression#fixupVariables(Vector, int)
	*/
	public void fixupVariables(List<QName> vars, int globalsSize)
	{
	super.fixupVariables(vars, globalsSize);
	}

	/**
	* Add the node into a vector of nodes where it should occur in
	* document order.
	* @param node The node to be added.
	* @return insertIndex.
	* @throws RuntimeException thrown if this NodeSetDTM is not of
	* a mutable type.
	*/
	protected int addNodeInDocOrder(int node)
	{
	assertion(hasCache(), "addNodeInDocOrder must be done on a mutable sequence!");

	int insertIndex = -1;

	NodeVector vec = getVector();

	// This needs to do a binary search, but a binary search
	// is somewhat tough because the sequence test involves
	// two nodes.
	int size = vec.size(), i;

	for (i = size - 1; i >= 0; i--)
	{
	int child = vec.elementAt(i);

	if (child == node)
	{
	i = -2; // Duplicate, suppress insert

	break;
	}

	DTM dtm = m_dtmMgr.getDTM(node);
	if (!dtm.isNodeAfter(node, child))
	{
	break;
	}
	}

	if (i != -2)
	{
	insertIndex = i + 1;

	vec.insertElementAt(node, insertIndex);
	}

	// checkDups();
	return insertIndex;
	} // end addNodeInDocOrder(List<QName> v, Object obj)

	/**
	* It used to be that many locations in the code simply
	* did an assignment to this.m_obj directly, rather than
	* calling the setObject(Object) method. The problem is
	* that our super-class would be updated on what the
	* cache associated with this NodeSequence, but
	* we wouldn't know ourselves.
	* <p>
	* All setting of m_obj is done through setObject() now,
	* and this method over-rides the super-class method.
	* So now we are in the loop have an opportunity
	* to update some caching information.
	*
	*/
	protected void setObject(Object obj) {
	if (obj instanceof NodeVector) {
	// Keep our superclass informed of the current NodeVector
	// ... if we don't the smoketest fails (don't know why).
	super.setObject(obj);

	// A copy of the code of what SetVector() would do.
	NodeVector v = (NodeVector)obj;
	if (m_cache != null) {
	m_cache.setVector(v);
	} else if (v!=null) {
	m_cache = new IteratorCache();
	m_cache.setVector(v);
	}
	} else if (obj instanceof IteratorCache) {
	IteratorCache cache = (IteratorCache) obj;
	m_cache = cache;
	m_cache.increaseUseCount();

	// Keep our superclass informed of the current NodeVector
	super.setObject(cache.getVector());
	} else {
	super.setObject(obj);
	}

	}

	/**
	* Each NodeSequence object has an iterator which is "walked".
	* As an iterator is walked one obtains nodes from it.
	* As those nodes are obtained they may be cached, making
	* the next walking of a copy or clone of the iterator faster.
	* This field (m_cache) is a reference to such a cache,
	* which is populated as the iterator is walked.
	* <p>
	* Note that multiple NodeSequence objects may hold a
	* reference to the same cache, and also
	* (and this is important) the same iterator.
	* The iterator and its cache may be shared among
	* many NodeSequence objects.
	* <p>
	* If one of the NodeSequence objects walks ahead
	* of the others it fills in the cache.
	* As the others NodeSequence objects catch up they
	* get their values from
	* the cache rather than the iterator itself, so
	* the iterator is only ever walked once and everyone
	* benefits from the cache.
	* <p>
	* At some point the cache may be
	* complete due to walking to the end of one of
	* the copies of the iterator, and the cache is
	* then marked as "complete".
	* and the cache will have no more nodes added to it.
	* <p>
	* Its use-count is the number of NodeSequence objects that use it.
	*/
	private final static class IteratorCache {
	/**
	* A list of nodes already obtained from the iterator.
	* As the iterator is walked the nodes obtained from
	* it are appended to this list.
	* <p>
	* Both an iterator and its corresponding cache can
	* be shared by multiple NodeSequence objects.
	* <p>
	* For example, consider three NodeSequence objects
	* ns1, ns2 and ns3 doing such sharing, and the
	* nodes to be obtaind from the iterator being
	* the sequence { 33, 11, 44, 22, 55 }.
	* <p>
	* If ns3.nextNode() is called 3 times the the
	* underlying iterator will have walked through
	* 33, 11, 55 and these three nodes will have been put
	* in the cache.
	* <p>
	* If ns2.nextNode() is called 2 times it will return
	* 33 and 11 from the cache, leaving the iterator alone.
	* <p>
	* If ns1.nextNode() is called 6 times it will return
	* 33 and 11 from the cache, then get 44, 22, 55 from
	* the iterator, and appending 44, 22, 55 to the cache.
	* On the sixth call it is found that the iterator is
	* exhausted and the cache is marked complete.
	* <p>
	* Should ns2 or ns3 have nextNode() called they will
	* know that the cache is complete, and they will
	* obtain all subsequent nodes from the cache.
	* <p>
	* Note that the underlying iterator, though shared
	* is only ever walked once.
	*/
	private NodeVector m_vec2;

	/**
	* true if the associated iterator is exhausted and
	* all nodes obtained from it are in the cache.
	*/
	private boolean m_isComplete2;

	private int m_useCount2;

	IteratorCache() {
	m_vec2 = null;
	m_isComplete2 = false;
	m_useCount2 = 1;
	return;
	}

	/**
	* Returns count of how many NodeSequence objects share this
	* IteratorCache object.
	*/
	private int useCount() {
	return m_useCount2;
	}

	/**
	* This method is called when yet another
	* NodeSequence object uses, or shares
	* this same cache.
	*
	*/
	private void increaseUseCount() {
	if (m_vec2 != null)
	m_useCount2++;

	}

	/**
	* Sets the NodeVector that holds the
	* growing list of nodes as they are appended
	* to the cached list.
	*/
	private void setVector(NodeVector nv) {
	m_vec2 = nv;
	m_useCount2 = 1;
	}

	/**
	* Get the cached list of nodes obtained from
	* the iterator so far.
	*/
	private NodeVector getVector() {
	return m_vec2;
	}

	/**
	* Call this method with 'true' if the
	* iterator is exhausted and the cached list
	* is complete, or no longer growing.
	*/
	private void setCacheComplete(boolean b) {
	m_isComplete2 = b;

	}

	/**
	* Returns true if no cache is complete
	* and immutable.
	*/
	private boolean isComplete() {
	return m_isComplete2;
	}
	}

	/**
	* Get the cached list of nodes appended with
	* values obtained from the iterator as
	* a NodeSequence is walked when its
	* nextNode() method is called.
	*/
	protected IteratorCache getIteratorCache() {
	return m_cache;
	}
	}

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