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	/*
	* Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package java.util.stream;

	import java.util.Comparator;
	import java.util.Objects;
	import java.util.Spliterator;
	import java.util.concurrent.CountedCompleter;
	import java.util.concurrent.atomic.AtomicBoolean;
	import java.util.function.Consumer;
	import java.util.function.DoubleConsumer;
	import java.util.function.DoublePredicate;
	import java.util.function.IntConsumer;
	import java.util.function.IntFunction;
	import java.util.function.IntPredicate;
	import java.util.function.LongConsumer;
	import java.util.function.LongPredicate;
	import java.util.function.Predicate;

	/**
	* Factory for instances of a takeWhile and dropWhile operations
	* that produce subsequences of their input stream.
	*
	* @since 9
	*/
	final class WhileOps {

	static final int TAKE_FLAGS = StreamOpFlag.NOT_SIZED \| StreamOpFlag.IS_SHORT_CIRCUIT;

	static final int DROP_FLAGS = StreamOpFlag.NOT_SIZED;

	/**
	* Appends a "takeWhile" operation to the provided Stream.
	*
	* @param <T> the type of both input and output elements
	* @param upstream a reference stream with element type T
	* @param predicate the predicate that returns false to halt taking.
	*/
	static <T> Stream<T> makeTakeWhileRef(AbstractPipeline<?, T, ?> upstream,
	Predicate<? super T> predicate) {
	Objects.requireNonNull(predicate);
	return new ReferencePipeline.StatefulOp<T, T>(upstream, StreamShape.REFERENCE, TAKE_FLAGS) {
	@Override
	<P_IN> Spliterator<T> opEvaluateParallelLazy(PipelineHelper<T> helper,
	Spliterator<P_IN> spliterator) {
	if (StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags())) {
	return opEvaluateParallel(helper, spliterator, Nodes.castingArray())
	.spliterator();
	}
	else {
	return new UnorderedWhileSpliterator.OfRef.Taking<>(
	helper.wrapSpliterator(spliterator), false, predicate);
	}
	}

	@Override
	<P_IN> Node<T> opEvaluateParallel(PipelineHelper<T> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<T[]> generator) {
	return new TakeWhileTask<>(this, helper, spliterator, generator)
	.invoke();
	}

	@Override
	Sink<T> opWrapSink(int flags, Sink<T> sink) {
	return new Sink.ChainedReference<T, T>(sink) {
	boolean take = true;

	@Override
	public void begin(long size) {
	downstream.begin(-1);
	}

	@Override
	public void accept(T t) {
	if (take && (take = predicate.test(t))) {
	downstream.accept(t);
	}
	}

	@Override
	public boolean cancellationRequested() {
	return !take \|\| downstream.cancellationRequested();
	}
	};
	}
	};
	}

	/**
	* Appends a "takeWhile" operation to the provided IntStream.
	*
	* @param upstream a reference stream with element type T
	* @param predicate the predicate that returns false to halt taking.
	*/
	static IntStream makeTakeWhileInt(AbstractPipeline<?, Integer, ?> upstream,
	IntPredicate predicate) {
	Objects.requireNonNull(predicate);
	return new IntPipeline.StatefulOp<Integer>(upstream, StreamShape.INT_VALUE, TAKE_FLAGS) {
	@Override
	<P_IN> Spliterator<Integer> opEvaluateParallelLazy(PipelineHelper<Integer> helper,
	Spliterator<P_IN> spliterator) {
	if (StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags())) {
	return opEvaluateParallel(helper, spliterator, Integer[]::new)
	.spliterator();
	}
	else {
	return new UnorderedWhileSpliterator.OfInt.Taking(
	(Spliterator.OfInt) helper.wrapSpliterator(spliterator), false, predicate);
	}
	}

	@Override
	<P_IN> Node<Integer> opEvaluateParallel(PipelineHelper<Integer> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<Integer[]> generator) {
	return new TakeWhileTask<>(this, helper, spliterator, generator)
	.invoke();
	}

	@Override
	Sink<Integer> opWrapSink(int flags, Sink<Integer> sink) {
	return new Sink.ChainedInt<Integer>(sink) {
	boolean take = true;

	@Override
	public void begin(long size) {
	downstream.begin(-1);
	}

	@Override
	public void accept(int t) {
	if (take && (take = predicate.test(t))) {
	downstream.accept(t);
	}
	}

	@Override
	public boolean cancellationRequested() {
	return !take \|\| downstream.cancellationRequested();
	}
	};
	}
	};
	}

	/**
	* Appends a "takeWhile" operation to the provided LongStream.
	*
	* @param upstream a reference stream with element type T
	* @param predicate the predicate that returns false to halt taking.
	*/
	static LongStream makeTakeWhileLong(AbstractPipeline<?, Long, ?> upstream,
	LongPredicate predicate) {
	Objects.requireNonNull(predicate);
	return new LongPipeline.StatefulOp<Long>(upstream, StreamShape.LONG_VALUE, TAKE_FLAGS) {
	@Override
	<P_IN> Spliterator<Long> opEvaluateParallelLazy(PipelineHelper<Long> helper,
	Spliterator<P_IN> spliterator) {
	if (StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags())) {
	return opEvaluateParallel(helper, spliterator, Long[]::new)
	.spliterator();
	}
	else {
	return new UnorderedWhileSpliterator.OfLong.Taking(
	(Spliterator.OfLong) helper.wrapSpliterator(spliterator), false, predicate);
	}
	}

	@Override
	<P_IN> Node<Long> opEvaluateParallel(PipelineHelper<Long> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<Long[]> generator) {
	return new TakeWhileTask<>(this, helper, spliterator, generator)
	.invoke();
	}

	@Override
	Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
	return new Sink.ChainedLong<Long>(sink) {
	boolean take = true;

	@Override
	public void begin(long size) {
	downstream.begin(-1);
	}

	@Override
	public void accept(long t) {
	if (take && (take = predicate.test(t))) {
	downstream.accept(t);
	}
	}

	@Override
	public boolean cancellationRequested() {
	return !take \|\| downstream.cancellationRequested();
	}
	};
	}
	};
	}

	/**
	* Appends a "takeWhile" operation to the provided DoubleStream.
	*
	* @param upstream a reference stream with element type T
	* @param predicate the predicate that returns false to halt taking.
	*/
	static DoubleStream makeTakeWhileDouble(AbstractPipeline<?, Double, ?> upstream,
	DoublePredicate predicate) {
	Objects.requireNonNull(predicate);
	return new DoublePipeline.StatefulOp<Double>(upstream, StreamShape.DOUBLE_VALUE, TAKE_FLAGS) {
	@Override
	<P_IN> Spliterator<Double> opEvaluateParallelLazy(PipelineHelper<Double> helper,
	Spliterator<P_IN> spliterator) {
	if (StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags())) {
	return opEvaluateParallel(helper, spliterator, Double[]::new)
	.spliterator();
	}
	else {
	return new UnorderedWhileSpliterator.OfDouble.Taking(
	(Spliterator.OfDouble) helper.wrapSpliterator(spliterator), false, predicate);
	}
	}

	@Override
	<P_IN> Node<Double> opEvaluateParallel(PipelineHelper<Double> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<Double[]> generator) {
	return new TakeWhileTask<>(this, helper, spliterator, generator)
	.invoke();
	}

	@Override
	Sink<Double> opWrapSink(int flags, Sink<Double> sink) {
	return new Sink.ChainedDouble<Double>(sink) {
	boolean take = true;

	@Override
	public void begin(long size) {
	downstream.begin(-1);
	}

	@Override
	public void accept(double t) {
	if (take && (take = predicate.test(t))) {
	downstream.accept(t);
	}
	}

	@Override
	public boolean cancellationRequested() {
	return !take \|\| downstream.cancellationRequested();
	}
	};
	}
	};
	}

	/**
	* A specialization for the dropWhile operation that controls if
	* elements to be dropped are counted and passed downstream.
	* <p>
	* This specialization is utilized by the {@link TakeWhileTask} for
	* pipelines that are ordered. In such cases elements cannot be dropped
	* until all elements have been collected.
	*
	* @param <T> the type of both input and output elements
	*/
	interface DropWhileOp<T> {
	/**
	* Accepts a {@code Sink} which will receive the results of this
	* dropWhile operation, and return a {@code DropWhileSink} which
	* accepts
	* elements and which performs the dropWhile operation passing the
	* results to the provided {@code Sink}.
	*
	* @param sink sink to which elements should be sent after processing
	* @param retainAndCountDroppedElements true if elements to be dropped
	* are counted and passed to the sink, otherwise such elements
	* are actually dropped and not passed to the sink.
	* @return a dropWhile sink
	*/
	DropWhileSink<T> opWrapSink(Sink<T> sink, boolean retainAndCountDroppedElements);
	}

	/**
	* A specialization for a dropWhile sink.
	*
	* @param <T> the type of both input and output elements
	*/
	interface DropWhileSink<T> extends Sink<T> {
	/**
	* @return the could of elements that would have been dropped and
	* instead were passed downstream.
	*/
	long getDropCount();
	}

	/**
	* Appends a "dropWhile" operation to the provided Stream.
	*
	* @param <T> the type of both input and output elements
	* @param upstream a reference stream with element type T
	* @param predicate the predicate that returns false to halt dropping.
	*/
	static <T> Stream<T> makeDropWhileRef(AbstractPipeline<?, T, ?> upstream,
	Predicate<? super T> predicate) {
	Objects.requireNonNull(predicate);

	class Op extends ReferencePipeline.StatefulOp<T, T> implements DropWhileOp<T> {
	public Op(AbstractPipeline<?, T, ?> upstream, StreamShape inputShape, int opFlags) {
	super(upstream, inputShape, opFlags);
	}

	@Override
	<P_IN> Spliterator<T> opEvaluateParallelLazy(PipelineHelper<T> helper,
	Spliterator<P_IN> spliterator) {
	if (StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags())) {
	return opEvaluateParallel(helper, spliterator, Nodes.castingArray())
	.spliterator();
	}
	else {
	return new UnorderedWhileSpliterator.OfRef.Dropping<>(
	helper.wrapSpliterator(spliterator), false, predicate);
	}
	}

	@Override
	<P_IN> Node<T> opEvaluateParallel(PipelineHelper<T> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<T[]> generator) {
	return new DropWhileTask<>(this, helper, spliterator, generator)
	.invoke();
	}

	@Override
	Sink<T> opWrapSink(int flags, Sink<T> sink) {
	return opWrapSink(sink, false);
	}

	public DropWhileSink<T> opWrapSink(Sink<T> sink, boolean retainAndCountDroppedElements) {
	class OpSink extends Sink.ChainedReference<T, T> implements DropWhileSink<T> {
	long dropCount;
	boolean take;

	OpSink() {
	super(sink);
	}

	@Override
	public void accept(T t) {
	boolean takeElement = take \|\| (take = !predicate.test(t));

	// If ordered and element is dropped increment index
	// for possible future truncation
	if (retainAndCountDroppedElements && !takeElement)
	dropCount++;

	// If ordered need to process element, otherwise
	// skip if element is dropped
	if (retainAndCountDroppedElements \|\| takeElement)
	downstream.accept(t);
	}

	@Override
	public long getDropCount() {
	return dropCount;
	}
	}
	return new OpSink();
	}
	}
	return new Op(upstream, StreamShape.REFERENCE, DROP_FLAGS);
	}

	/**
	* Appends a "dropWhile" operation to the provided IntStream.
	*
	* @param upstream a reference stream with element type T
	* @param predicate the predicate that returns false to halt dropping.
	*/
	static IntStream makeDropWhileInt(AbstractPipeline<?, Integer, ?> upstream,
	IntPredicate predicate) {
	Objects.requireNonNull(predicate);
	class Op extends IntPipeline.StatefulOp<Integer> implements DropWhileOp<Integer> {
	public Op(AbstractPipeline<?, Integer, ?> upstream, StreamShape inputShape, int opFlags) {
	super(upstream, inputShape, opFlags);
	}

	@Override
	<P_IN> Spliterator<Integer> opEvaluateParallelLazy(PipelineHelper<Integer> helper,
	Spliterator<P_IN> spliterator) {
	if (StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags())) {
	return opEvaluateParallel(helper, spliterator, Integer[]::new)
	.spliterator();
	}
	else {
	return new UnorderedWhileSpliterator.OfInt.Dropping(
	(Spliterator.OfInt) helper.wrapSpliterator(spliterator), false, predicate);
	}
	}

	@Override
	<P_IN> Node<Integer> opEvaluateParallel(PipelineHelper<Integer> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<Integer[]> generator) {
	return new DropWhileTask<>(this, helper, spliterator, generator)
	.invoke();
	}

	@Override
	Sink<Integer> opWrapSink(int flags, Sink<Integer> sink) {
	return opWrapSink(sink, false);
	}

	public DropWhileSink<Integer> opWrapSink(Sink<Integer> sink, boolean retainAndCountDroppedElements) {
	class OpSink extends Sink.ChainedInt<Integer> implements DropWhileSink<Integer> {
	long dropCount;
	boolean take;

	OpSink() {
	super(sink);
	}

	@Override
	public void accept(int t) {
	boolean takeElement = take \|\| (take = !predicate.test(t));

	// If ordered and element is dropped increment index
	// for possible future truncation
	if (retainAndCountDroppedElements && !takeElement)
	dropCount++;

	// If ordered need to process element, otherwise
	// skip if element is dropped
	if (retainAndCountDroppedElements \|\| takeElement)
	downstream.accept(t);
	}

	@Override
	public long getDropCount() {
	return dropCount;
	}
	}
	return new OpSink();
	}
	}
	return new Op(upstream, StreamShape.INT_VALUE, DROP_FLAGS);
	}

	/**
	* Appends a "dropWhile" operation to the provided LongStream.
	*
	* @param upstream a reference stream with element type T
	* @param predicate the predicate that returns false to halt dropping.
	*/
	static LongStream makeDropWhileLong(AbstractPipeline<?, Long, ?> upstream,
	LongPredicate predicate) {
	Objects.requireNonNull(predicate);
	class Op extends LongPipeline.StatefulOp<Long> implements DropWhileOp<Long> {
	public Op(AbstractPipeline<?, Long, ?> upstream, StreamShape inputShape, int opFlags) {
	super(upstream, inputShape, opFlags);
	}

	@Override
	<P_IN> Spliterator<Long> opEvaluateParallelLazy(PipelineHelper<Long> helper,
	Spliterator<P_IN> spliterator) {
	if (StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags())) {
	return opEvaluateParallel(helper, spliterator, Long[]::new)
	.spliterator();
	}
	else {
	return new UnorderedWhileSpliterator.OfLong.Dropping(
	(Spliterator.OfLong) helper.wrapSpliterator(spliterator), false, predicate);
	}
	}

	@Override
	<P_IN> Node<Long> opEvaluateParallel(PipelineHelper<Long> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<Long[]> generator) {
	return new DropWhileTask<>(this, helper, spliterator, generator)
	.invoke();
	}

	@Override
	Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
	return opWrapSink(sink, false);
	}

	public DropWhileSink<Long> opWrapSink(Sink<Long> sink, boolean retainAndCountDroppedElements) {
	class OpSink extends Sink.ChainedLong<Long> implements DropWhileSink<Long> {
	long dropCount;
	boolean take;

	OpSink() {
	super(sink);
	}

	@Override
	public void accept(long t) {
	boolean takeElement = take \|\| (take = !predicate.test(t));

	// If ordered and element is dropped increment index
	// for possible future truncation
	if (retainAndCountDroppedElements && !takeElement)
	dropCount++;

	// If ordered need to process element, otherwise
	// skip if element is dropped
	if (retainAndCountDroppedElements \|\| takeElement)
	downstream.accept(t);
	}

	@Override
	public long getDropCount() {
	return dropCount;
	}
	}
	return new OpSink();
	}
	}
	return new Op(upstream, StreamShape.LONG_VALUE, DROP_FLAGS);
	}

	/**
	* Appends a "dropWhile" operation to the provided DoubleStream.
	*
	* @param upstream a reference stream with element type T
	* @param predicate the predicate that returns false to halt dropping.
	*/
	static DoubleStream makeDropWhileDouble(AbstractPipeline<?, Double, ?> upstream,
	DoublePredicate predicate) {
	Objects.requireNonNull(predicate);
	class Op extends DoublePipeline.StatefulOp<Double> implements DropWhileOp<Double> {
	public Op(AbstractPipeline<?, Double, ?> upstream, StreamShape inputShape, int opFlags) {
	super(upstream, inputShape, opFlags);
	}

	@Override
	<P_IN> Spliterator<Double> opEvaluateParallelLazy(PipelineHelper<Double> helper,
	Spliterator<P_IN> spliterator) {
	if (StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags())) {
	return opEvaluateParallel(helper, spliterator, Double[]::new)
	.spliterator();
	}
	else {
	return new UnorderedWhileSpliterator.OfDouble.Dropping(
	(Spliterator.OfDouble) helper.wrapSpliterator(spliterator), false, predicate);
	}
	}

	@Override
	<P_IN> Node<Double> opEvaluateParallel(PipelineHelper<Double> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<Double[]> generator) {
	return new DropWhileTask<>(this, helper, spliterator, generator)
	.invoke();
	}

	@Override
	Sink<Double> opWrapSink(int flags, Sink<Double> sink) {
	return opWrapSink(sink, false);
	}

	public DropWhileSink<Double> opWrapSink(Sink<Double> sink, boolean retainAndCountDroppedElements) {
	class OpSink extends Sink.ChainedDouble<Double> implements DropWhileSink<Double> {
	long dropCount;
	boolean take;

	OpSink() {
	super(sink);
	}

	@Override
	public void accept(double t) {
	boolean takeElement = take \|\| (take = !predicate.test(t));

	// If ordered and element is dropped increment index
	// for possible future truncation
	if (retainAndCountDroppedElements && !takeElement)
	dropCount++;

	// If ordered need to process element, otherwise
	// skip if element is dropped
	if (retainAndCountDroppedElements \|\| takeElement)
	downstream.accept(t);
	}

	@Override
	public long getDropCount() {
	return dropCount;
	}
	}
	return new OpSink();
	}
	}
	return new Op(upstream, StreamShape.DOUBLE_VALUE, DROP_FLAGS);
	}

	//

	/**
	* A spliterator supporting takeWhile and dropWhile operations over an
	* underlying spliterator whose covered elements have no encounter order.
	* <p>
	* Concrete subclasses of this spliterator support reference and primitive
	* types for takeWhile and dropWhile.
	* <p>
	* For the takeWhile operation if during traversal taking completes then
	* taking is cancelled globally for the splitting and traversal of all
	* related spliterators.
	* Cancellation is governed by a shared {@link AtomicBoolean} instance. A
	* spliterator in the process of taking when cancellation occurs will also
	* be cancelled but not necessarily immediately. To reduce contention on
	* the {@link AtomicBoolean} instance, cancellation make be acted on after
	* a small number of additional elements have been traversed.
	* <p>
	* For the dropWhile operation if during traversal dropping completes for
	* some, but not all elements, then it is cancelled globally for the
	* traversal of all related spliterators (splitting is not cancelled).
	* Cancellation is governed in the same manner as for the takeWhile
	* operation.
	*
	* @param <T> the type of elements returned by this spliterator
	* @param <T_SPLITR> the type of the spliterator
	*/
	abstract static class UnorderedWhileSpliterator<T, T_SPLITR extends Spliterator<T>> implements Spliterator<T> {
	// Power of two constant minus one used for modulus of count
	static final int CANCEL_CHECK_COUNT = (1 << 6) - 1;

	// The underlying spliterator
	final T_SPLITR s;
	// True if no splitting should be performed, if true then
	// this spliterator may be used for an underlying spliterator whose
	// covered elements have an encounter order
	// See use in stream take/dropWhile default default methods
	final boolean noSplitting;
	// True when operations are cancelled for all related spliterators
	// For taking, spliterators cannot split or traversed
	// For dropping, spliterators cannot be traversed
	final AtomicBoolean cancel;
	// True while taking or dropping should be performed when traversing
	boolean takeOrDrop = true;
	// The count of elements traversed
	int count;

	UnorderedWhileSpliterator(T_SPLITR s, boolean noSplitting) {
	this.s = s;
	this.noSplitting = noSplitting;
	this.cancel = new AtomicBoolean();
	}

	UnorderedWhileSpliterator(T_SPLITR s, UnorderedWhileSpliterator<T, T_SPLITR> parent) {
	this.s = s;
	this.noSplitting = parent.noSplitting;
	this.cancel = parent.cancel;
	}

	@Override
	public long estimateSize() {
	return s.estimateSize();
	}

	@Override
	public int characteristics() {
	// Size is not known
	return s.characteristics() & ~(Spliterator.SIZED \| Spliterator.SUBSIZED);
	}

	@Override
	public long getExactSizeIfKnown() {
	return -1L;
	}

	@Override
	public Comparator<? super T> getComparator() {
	return s.getComparator();
	}

	@Override
	public T_SPLITR trySplit() {
	@SuppressWarnings("unchecked")
	T_SPLITR ls = noSplitting ? null : (T_SPLITR) s.trySplit();
	return ls != null ? makeSpliterator(ls) : null;
	}

	boolean checkCancelOnCount() {
	return count != 0 \|\| !cancel.get();
	}

	abstract T_SPLITR makeSpliterator(T_SPLITR s);

	abstract static class OfRef<T> extends UnorderedWhileSpliterator<T, Spliterator<T>> implements Consumer<T> {
	final Predicate<? super T> p;
	T t;

	OfRef(Spliterator<T> s, boolean noSplitting, Predicate<? super T> p) {
	super(s, noSplitting);
	this.p = p;
	}

	OfRef(Spliterator<T> s, OfRef<T> parent) {
	super(s, parent);
	this.p = parent.p;
	}

	@Override
	public void accept(T t) {
	count = (count + 1) & CANCEL_CHECK_COUNT;
	this.t = t;
	}

	static final class Taking<T> extends OfRef<T> {
	Taking(Spliterator<T> s, boolean noSplitting, Predicate<? super T> p) {
	super(s, noSplitting, p);
	}

	Taking(Spliterator<T> s, Taking<T> parent) {
	super(s, parent);
	}

	@Override
	public boolean tryAdvance(Consumer<? super T> action) {
	boolean test = true;
	if (takeOrDrop && // If can take
	checkCancelOnCount() && // and if not cancelled
	s.tryAdvance(this) && // and if advanced one element
	(test = p.test(t))) { // and test on element passes
	action.accept(t); // then accept element
	return true;
	}
	else {
	// Taking is finished
	takeOrDrop = false;
	// Cancel all further traversal and splitting operations
	// only if test of element failed (short-circuited)
	if (!test)
	cancel.set(true);
	return false;
	}
	}

	@Override
	public Spliterator<T> trySplit() {
	// Do not split if all operations are cancelled
	return cancel.get() ? null : super.trySplit();
	}

	@Override
	Spliterator<T> makeSpliterator(Spliterator<T> s) {
	return new Taking<>(s, this);
	}
	}

	static final class Dropping<T> extends OfRef<T> {
	Dropping(Spliterator<T> s, boolean noSplitting, Predicate<? super T> p) {
	super(s, noSplitting, p);
	}

	Dropping(Spliterator<T> s, Dropping<T> parent) {
	super(s, parent);
	}

	@Override
	public boolean tryAdvance(Consumer<? super T> action) {
	if (takeOrDrop) {
	takeOrDrop = false;
	boolean adv;
	boolean dropped = false;
	while ((adv = s.tryAdvance(this)) && // If advanced one element
	checkCancelOnCount() && // and if not cancelled
	p.test(t)) { // and test on element passes
	dropped = true; // then drop element
	}

	// Report advanced element, if any
	if (adv) {
	// Cancel all further dropping if one or more elements
	// were previously dropped
	if (dropped)
	cancel.set(true);
	action.accept(t);
	}
	return adv;
	}
	else {
	return s.tryAdvance(action);
	}
	}

	@Override
	Spliterator<T> makeSpliterator(Spliterator<T> s) {
	return new Dropping<>(s, this);
	}
	}
	}

	abstract static class OfInt extends UnorderedWhileSpliterator<Integer, Spliterator.OfInt> implements IntConsumer, Spliterator.OfInt {
	final IntPredicate p;
	int t;

	OfInt(Spliterator.OfInt s, boolean noSplitting, IntPredicate p) {
	super(s, noSplitting);
	this.p = p;
	}

	OfInt(Spliterator.OfInt s, UnorderedWhileSpliterator.OfInt parent) {
	super(s, parent);
	this.p = parent.p;
	}

	@Override
	public void accept(int t) {
	count = (count + 1) & CANCEL_CHECK_COUNT;
	this.t = t;
	}

	static final class Taking extends UnorderedWhileSpliterator.OfInt {
	Taking(Spliterator.OfInt s, boolean noSplitting, IntPredicate p) {
	super(s, noSplitting, p);
	}

	Taking(Spliterator.OfInt s, UnorderedWhileSpliterator.OfInt parent) {
	super(s, parent);
	}

	@Override
	public boolean tryAdvance(IntConsumer action) {
	boolean test = true;
	if (takeOrDrop && // If can take
	checkCancelOnCount() && // and if not cancelled
	s.tryAdvance(this) && // and if advanced one element
	(test = p.test(t))) { // and test on element passes
	action.accept(t); // then accept element
	return true;
	}
	else {
	// Taking is finished
	takeOrDrop = false;
	// Cancel all further traversal and splitting operations
	// only if test of element failed (short-circuited)
	if (!test)
	cancel.set(true);
	return false;
	}
	}

	@Override
	public Spliterator.OfInt trySplit() {
	// Do not split if all operations are cancelled
	return cancel.get() ? null : super.trySplit();
	}

	@Override
	Spliterator.OfInt makeSpliterator(Spliterator.OfInt s) {
	return new Taking(s, this);
	}
	}

	static final class Dropping extends UnorderedWhileSpliterator.OfInt {
	Dropping(Spliterator.OfInt s, boolean noSplitting, IntPredicate p) {
	super(s, noSplitting, p);
	}

	Dropping(Spliterator.OfInt s, UnorderedWhileSpliterator.OfInt parent) {
	super(s, parent);
	}

	@Override
	public boolean tryAdvance(IntConsumer action) {
	if (takeOrDrop) {
	takeOrDrop = false;
	boolean adv;
	boolean dropped = false;
	while ((adv = s.tryAdvance(this)) && // If advanced one element
	checkCancelOnCount() && // and if not cancelled
	p.test(t)) { // and test on element passes
	dropped = true; // then drop element
	}

	// Report advanced element, if any
	if (adv) {
	// Cancel all further dropping if one or more elements
	// were previously dropped
	if (dropped)
	cancel.set(true);
	action.accept(t);
	}
	return adv;
	}
	else {
	return s.tryAdvance(action);
	}
	}

	@Override
	Spliterator.OfInt makeSpliterator(Spliterator.OfInt s) {
	return new Dropping(s, this);
	}
	}
	}

	abstract static class OfLong extends UnorderedWhileSpliterator<Long, Spliterator.OfLong> implements LongConsumer, Spliterator.OfLong {
	final LongPredicate p;
	long t;

	OfLong(Spliterator.OfLong s, boolean noSplitting, LongPredicate p) {
	super(s, noSplitting);
	this.p = p;
	}

	OfLong(Spliterator.OfLong s, UnorderedWhileSpliterator.OfLong parent) {
	super(s, parent);
	this.p = parent.p;
	}

	@Override
	public void accept(long t) {
	count = (count + 1) & CANCEL_CHECK_COUNT;
	this.t = t;
	}

	static final class Taking extends UnorderedWhileSpliterator.OfLong {
	Taking(Spliterator.OfLong s, boolean noSplitting, LongPredicate p) {
	super(s, noSplitting, p);
	}

	Taking(Spliterator.OfLong s, UnorderedWhileSpliterator.OfLong parent) {
	super(s, parent);
	}

	@Override
	public boolean tryAdvance(LongConsumer action) {
	boolean test = true;
	if (takeOrDrop && // If can take
	checkCancelOnCount() && // and if not cancelled
	s.tryAdvance(this) && // and if advanced one element
	(test = p.test(t))) { // and test on element passes
	action.accept(t); // then accept element
	return true;
	}
	else {
	// Taking is finished
	takeOrDrop = false;
	// Cancel all further traversal and splitting operations
	// only if test of element failed (short-circuited)
	if (!test)
	cancel.set(true);
	return false;
	}
	}

	@Override
	public Spliterator.OfLong trySplit() {
	// Do not split if all operations are cancelled
	return cancel.get() ? null : super.trySplit();
	}

	@Override
	Spliterator.OfLong makeSpliterator(Spliterator.OfLong s) {
	return new Taking(s, this);
	}
	}

	static final class Dropping extends UnorderedWhileSpliterator.OfLong {
	Dropping(Spliterator.OfLong s, boolean noSplitting, LongPredicate p) {
	super(s, noSplitting, p);
	}

	Dropping(Spliterator.OfLong s, UnorderedWhileSpliterator.OfLong parent) {
	super(s, parent);
	}

	@Override
	public boolean tryAdvance(LongConsumer action) {
	if (takeOrDrop) {
	takeOrDrop = false;
	boolean adv;
	boolean dropped = false;
	while ((adv = s.tryAdvance(this)) && // If advanced one element
	checkCancelOnCount() && // and if not cancelled
	p.test(t)) { // and test on element passes
	dropped = true; // then drop element
	}

	// Report advanced element, if any
	if (adv) {
	// Cancel all further dropping if one or more elements
	// were previously dropped
	if (dropped)
	cancel.set(true);
	action.accept(t);
	}
	return adv;
	}
	else {
	return s.tryAdvance(action);
	}
	}

	@Override
	Spliterator.OfLong makeSpliterator(Spliterator.OfLong s) {
	return new Dropping(s, this);
	}
	}
	}

	abstract static class OfDouble extends UnorderedWhileSpliterator<Double, Spliterator.OfDouble> implements DoubleConsumer, Spliterator.OfDouble {
	final DoublePredicate p;
	double t;

	OfDouble(Spliterator.OfDouble s, boolean noSplitting, DoublePredicate p) {
	super(s, noSplitting);
	this.p = p;
	}

	OfDouble(Spliterator.OfDouble s, UnorderedWhileSpliterator.OfDouble parent) {
	super(s, parent);
	this.p = parent.p;
	}

	@Override
	public void accept(double t) {
	count = (count + 1) & CANCEL_CHECK_COUNT;
	this.t = t;
	}

	static final class Taking extends UnorderedWhileSpliterator.OfDouble {
	Taking(Spliterator.OfDouble s, boolean noSplitting, DoublePredicate p) {
	super(s, noSplitting, p);
	}

	Taking(Spliterator.OfDouble s, UnorderedWhileSpliterator.OfDouble parent) {
	super(s, parent);
	}

	@Override
	public boolean tryAdvance(DoubleConsumer action) {
	boolean test = true;
	if (takeOrDrop && // If can take
	checkCancelOnCount() && // and if not cancelled
	s.tryAdvance(this) && // and if advanced one element
	(test = p.test(t))) { // and test on element passes
	action.accept(t); // then accept element
	return true;
	}
	else {
	// Taking is finished
	takeOrDrop = false;
	// Cancel all further traversal and splitting operations
	// only if test of element failed (short-circuited)
	if (!test)
	cancel.set(true);
	return false;
	}
	}

	@Override
	public Spliterator.OfDouble trySplit() {
	// Do not split if all operations are cancelled
	return cancel.get() ? null : super.trySplit();
	}

	@Override
	Spliterator.OfDouble makeSpliterator(Spliterator.OfDouble s) {
	return new Taking(s, this);
	}
	}

	static final class Dropping extends UnorderedWhileSpliterator.OfDouble {
	Dropping(Spliterator.OfDouble s, boolean noSplitting, DoublePredicate p) {
	super(s, noSplitting, p);
	}

	Dropping(Spliterator.OfDouble s, UnorderedWhileSpliterator.OfDouble parent) {
	super(s, parent);
	}

	@Override
	public boolean tryAdvance(DoubleConsumer action) {
	if (takeOrDrop) {
	takeOrDrop = false;
	boolean adv;
	boolean dropped = false;
	while ((adv = s.tryAdvance(this)) && // If advanced one element
	checkCancelOnCount() && // and if not cancelled
	p.test(t)) { // and test on element passes
	dropped = true; // then drop element
	}

	// Report advanced element, if any
	if (adv) {
	// Cancel all further dropping if one or more elements
	// were previously dropped
	if (dropped)
	cancel.set(true);
	action.accept(t);
	}
	return adv;
	}
	else {
	return s.tryAdvance(action);
	}
	}

	@Override
	Spliterator.OfDouble makeSpliterator(Spliterator.OfDouble s) {
	return new Dropping(s, this);
	}
	}
	}
	}


	//

	/**
	* {@code ForkJoinTask} implementing takeWhile computation.
	* <p>
	* If the pipeline has encounter order then all tasks to the right of
	* a task where traversal was short-circuited are cancelled.
	* The results of completed (and cancelled) tasks are discarded.
	* The result of merging a short-circuited left task and right task (which
	* may or may not be short-circuited) is that left task.
	* <p>
	* If the pipeline has no encounter order then all tasks to the right of
	* a task where traversal was short-circuited are cancelled.
	* The results of completed (and possibly cancelled) tasks are not
	* discarded, as there is no need to throw away computed results.
	* The result of merging does not change if a left task was
	* short-circuited.
	* No attempt is made, once a leaf task stopped taking, for it to cancel
	* all other tasks, and further more, short-circuit the computation with its
	* result.
	*
	* @param <P_IN> Input element type to the stream pipeline
	* @param <P_OUT> Output element type from the stream pipeline
	*/
	@SuppressWarnings("serial")
	private static final class TakeWhileTask<P_IN, P_OUT>
	extends AbstractShortCircuitTask<P_IN, P_OUT, Node<P_OUT>, TakeWhileTask<P_IN, P_OUT>> {
	private final AbstractPipeline<P_OUT, P_OUT, ?> op;
	private final IntFunction<P_OUT[]> generator;
	private final boolean isOrdered;
	private long thisNodeSize;
	// True if a short-circuited
	private boolean shortCircuited;
	// True if completed, must be set after the local result
	private volatile boolean completed;

	TakeWhileTask(AbstractPipeline<P_OUT, P_OUT, ?> op,
	PipelineHelper<P_OUT> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<P_OUT[]> generator) {
	super(helper, spliterator);
	this.op = op;
	this.generator = generator;
	this.isOrdered = StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags());
	}

	TakeWhileTask(TakeWhileTask<P_IN, P_OUT> parent, Spliterator<P_IN> spliterator) {
	super(parent, spliterator);
	this.op = parent.op;
	this.generator = parent.generator;
	this.isOrdered = parent.isOrdered;
	}

	@Override
	protected TakeWhileTask<P_IN, P_OUT> makeChild(Spliterator<P_IN> spliterator) {
	return new TakeWhileTask<>(this, spliterator);
	}

	@Override
	protected final Node<P_OUT> getEmptyResult() {
	return Nodes.emptyNode(op.getOutputShape());
	}

	@Override
	protected final Node<P_OUT> doLeaf() {
	Node.Builder<P_OUT> builder = helper.makeNodeBuilder(-1, generator);
	Sink<P_OUT> s = op.opWrapSink(helper.getStreamAndOpFlags(), builder);

	if (shortCircuited = helper.copyIntoWithCancel(helper.wrapSink(s), spliterator)) {
	// Cancel later nodes if the predicate returned false
	// during traversal
	cancelLaterNodes();
	}

	Node<P_OUT> node = builder.build();
	thisNodeSize = node.count();
	return node;
	}

	@Override
	public final void onCompletion(CountedCompleter<?> caller) {
	if (!isLeaf()) {
	Node<P_OUT> result;
	shortCircuited = leftChild.shortCircuited \| rightChild.shortCircuited;
	if (isOrdered && canceled) {
	thisNodeSize = 0;
	result = getEmptyResult();
	}
	else if (isOrdered && leftChild.shortCircuited) {
	// If taking finished on the left node then
	// use the left node result
	thisNodeSize = leftChild.thisNodeSize;
	result = leftChild.getLocalResult();
	}
	else {
	thisNodeSize = leftChild.thisNodeSize + rightChild.thisNodeSize;
	result = merge();
	}

	setLocalResult(result);
	}

	completed = true;
	super.onCompletion(caller);
	}

	Node<P_OUT> merge() {
	if (leftChild.thisNodeSize == 0) {
	// If the left node size is 0 then
	// use the right node result
	return rightChild.getLocalResult();
	}
	else if (rightChild.thisNodeSize == 0) {
	// If the right node size is 0 then
	// use the left node result
	return leftChild.getLocalResult();
	}
	else {
	// Combine the left and right nodes
	return Nodes.conc(op.getOutputShape(),
	leftChild.getLocalResult(), rightChild.getLocalResult());
	}
	}

	@Override
	protected void cancel() {
	super.cancel();
	if (isOrdered && completed)
	// If the task is completed then clear the result, if any
	// to aid GC
	setLocalResult(getEmptyResult());
	}
	}

	/**
	* {@code ForkJoinTask} implementing dropWhile computation.
	* <p>
	* If the pipeline has encounter order then each leaf task will not
	* drop elements but will obtain a count of the elements that would have
	* been otherwise dropped. That count is used as an index to track
	* elements to be dropped. Merging will update the index so it corresponds
	* to the index that is the end of the global prefix of elements to be
	* dropped. The root is truncated according to that index.
	* <p>
	* If the pipeline has no encounter order then each leaf task will drop
	* elements. Leaf tasks are ordinarily merged. No truncation of the root
	* node is required.
	* No attempt is made, once a leaf task stopped dropping, for it to cancel
	* all other tasks, and further more, short-circuit the computation with
	* its result.
	*
	* @param <P_IN> Input element type to the stream pipeline
	* @param <P_OUT> Output element type from the stream pipeline
	*/
	@SuppressWarnings("serial")
	private static final class DropWhileTask<P_IN, P_OUT>
	extends AbstractTask<P_IN, P_OUT, Node<P_OUT>, DropWhileTask<P_IN, P_OUT>> {
	private final AbstractPipeline<P_OUT, P_OUT, ?> op;
	private final IntFunction<P_OUT[]> generator;
	private final boolean isOrdered;
	private long thisNodeSize;
	// The index from which elements of the node should be taken
	// i.e. the node should be truncated from [takeIndex, thisNodeSize)
	// Equivalent to the count of dropped elements
	private long index;

	DropWhileTask(AbstractPipeline<P_OUT, P_OUT, ?> op,
	PipelineHelper<P_OUT> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<P_OUT[]> generator) {
	super(helper, spliterator);
	assert op instanceof DropWhileOp;
	this.op = op;
	this.generator = generator;
	this.isOrdered = StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags());
	}

	DropWhileTask(DropWhileTask<P_IN, P_OUT> parent, Spliterator<P_IN> spliterator) {
	super(parent, spliterator);
	this.op = parent.op;
	this.generator = parent.generator;
	this.isOrdered = parent.isOrdered;
	}

	@Override
	protected DropWhileTask<P_IN, P_OUT> makeChild(Spliterator<P_IN> spliterator) {
	return new DropWhileTask<>(this, spliterator);
	}

	@Override
	protected final Node<P_OUT> doLeaf() {
	boolean isChild = !isRoot();
	// If this not the root and pipeline is ordered and size is known
	// then pre-size the builder
	long sizeIfKnown = isChild && isOrdered && StreamOpFlag.SIZED.isPreserved(op.sourceOrOpFlags)
	? op.exactOutputSizeIfKnown(spliterator)
	: -1;
	Node.Builder<P_OUT> builder = helper.makeNodeBuilder(sizeIfKnown, generator);
	@SuppressWarnings("unchecked")
	DropWhileOp<P_OUT> dropOp = (DropWhileOp<P_OUT>) op;
	// If this leaf is the root then there is no merging on completion
	// and there is no need to retain dropped elements
	DropWhileSink<P_OUT> s = dropOp.opWrapSink(builder, isOrdered && isChild);
	helper.wrapAndCopyInto(s, spliterator);

	Node<P_OUT> node = builder.build();
	thisNodeSize = node.count();
	index = s.getDropCount();
	return node;
	}

	@Override
	public final void onCompletion(CountedCompleter<?> caller) {
	if (!isLeaf()) {
	if (isOrdered) {
	index = leftChild.index;
	// If a contiguous sequence of dropped elements
	// include those of the right node, if any
	if (index == leftChild.thisNodeSize)
	index += rightChild.index;
	}

	thisNodeSize = leftChild.thisNodeSize + rightChild.thisNodeSize;
	Node<P_OUT> result = merge();
	setLocalResult(isRoot() ? doTruncate(result) : result);
	}

	super.onCompletion(caller);
	}

	private Node<P_OUT> merge() {
	if (leftChild.thisNodeSize == 0) {
	// If the left node size is 0 then
	// use the right node result
	return rightChild.getLocalResult();
	}
	else if (rightChild.thisNodeSize == 0) {
	// If the right node size is 0 then
	// use the left node result
	return leftChild.getLocalResult();
	}
	else {
	// Combine the left and right nodes
	return Nodes.conc(op.getOutputShape(),
	leftChild.getLocalResult(), rightChild.getLocalResult());
	}
	}

	private Node<P_OUT> doTruncate(Node<P_OUT> input) {
	return isOrdered
	? input.truncate(index, input.count(), generator)
	: input;
	}
	}
	}

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