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	/*
	* Copyright (c) 2013, 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.LongSummaryStatistics;
	import java.util.Objects;
	import java.util.OptionalDouble;
	import java.util.OptionalLong;
	import java.util.PrimitiveIterator;
	import java.util.Spliterator;
	import java.util.Spliterators;
	import java.util.function.BiConsumer;
	import java.util.function.BinaryOperator;
	import java.util.function.IntFunction;
	import java.util.function.LongBinaryOperator;
	import java.util.function.LongConsumer;
	import java.util.function.LongFunction;
	import java.util.function.LongPredicate;
	import java.util.function.LongToDoubleFunction;
	import java.util.function.LongToIntFunction;
	import java.util.function.LongUnaryOperator;
	import java.util.function.ObjLongConsumer;
	import java.util.function.Supplier;

	/**
	* Abstract base class for an intermediate pipeline stage or pipeline source
	* stage implementing whose elements are of type {@code long}.
	*
	* @param <E_IN> type of elements in the upstream source
	* @since 1.8
	*/
	abstract class LongPipeline<E_IN>
	extends AbstractPipeline<E_IN, Long, LongStream>
	implements LongStream {

	/**
	* Constructor for the head of a stream pipeline.
	*
	* @param source {@code Supplier<Spliterator>} describing the stream source
	* @param sourceFlags the source flags for the stream source, described in
	* {@link StreamOpFlag}
	* @param parallel {@code true} if the pipeline is parallel
	*/
	LongPipeline(Supplier<? extends Spliterator<Long>> source,
	int sourceFlags, boolean parallel) {
	super(source, sourceFlags, parallel);
	}

	/**
	* Constructor for the head of a stream pipeline.
	*
	* @param source {@code Spliterator} describing the stream source
	* @param sourceFlags the source flags for the stream source, described in
	* {@link StreamOpFlag}
	* @param parallel {@code true} if the pipeline is parallel
	*/
	LongPipeline(Spliterator<Long> source,
	int sourceFlags, boolean parallel) {
	super(source, sourceFlags, parallel);
	}

	/**
	* Constructor for appending an intermediate operation onto an existing pipeline.
	*
	* @param upstream the upstream element source.
	* @param opFlags the operation flags
	*/
	LongPipeline(AbstractPipeline<?, E_IN, ?> upstream, int opFlags) {
	super(upstream, opFlags);
	}

	/**
	* Adapt a {@code Sink<Long> to an {@code LongConsumer}, ideally simply
	* by casting.
	*/
	private static LongConsumer adapt(Sink<Long> sink) {
	if (sink instanceof LongConsumer) {
	return (LongConsumer) sink;
	} else {
	if (Tripwire.ENABLED)
	Tripwire.trip(AbstractPipeline.class,
	"using LongStream.adapt(Sink<Long> s)");
	return sink::accept;
	}
	}

	/**
	* Adapt a {@code Spliterator<Long>} to a {@code Spliterator.OfLong}.
	*
	* @implNote
	* The implementation attempts to cast to a Spliterator.OfLong, and throws
	* an exception if this cast is not possible.
	*/
	private static Spliterator.OfLong adapt(Spliterator<Long> s) {
	if (s instanceof Spliterator.OfLong) {
	return (Spliterator.OfLong) s;
	} else {
	if (Tripwire.ENABLED)
	Tripwire.trip(AbstractPipeline.class,
	"using LongStream.adapt(Spliterator<Long> s)");
	throw new UnsupportedOperationException("LongStream.adapt(Spliterator<Long> s)");
	}
	}


	// Shape-specific methods

	@Override
	final StreamShape getOutputShape() {
	return StreamShape.LONG_VALUE;
	}

	@Override
	final <P_IN> Node<Long> evaluateToNode(PipelineHelper<Long> helper,
	Spliterator<P_IN> spliterator,
	boolean flattenTree,
	IntFunction<Long[]> generator) {
	return Nodes.collectLong(helper, spliterator, flattenTree);
	}

	@Override
	final <P_IN> Spliterator<Long> wrap(PipelineHelper<Long> ph,
	Supplier<Spliterator<P_IN>> supplier,
	boolean isParallel) {
	return new StreamSpliterators.LongWrappingSpliterator<>(ph, supplier, isParallel);
	}

	@Override
	@SuppressWarnings("unchecked")
	final Spliterator.OfLong lazySpliterator(Supplier<? extends Spliterator<Long>> supplier) {
	return new StreamSpliterators.DelegatingSpliterator.OfLong((Supplier<Spliterator.OfLong>) supplier);
	}

	@Override
	final boolean forEachWithCancel(Spliterator<Long> spliterator, Sink<Long> sink) {
	Spliterator.OfLong spl = adapt(spliterator);
	LongConsumer adaptedSink = adapt(sink);
	boolean cancelled;
	do { } while (!(cancelled = sink.cancellationRequested()) && spl.tryAdvance(adaptedSink));
	return cancelled;
	}

	@Override
	final Node.Builder<Long> makeNodeBuilder(long exactSizeIfKnown, IntFunction<Long[]> generator) {
	return Nodes.longBuilder(exactSizeIfKnown);
	}

	private <U> Stream<U> mapToObj(LongFunction<? extends U> mapper, int opFlags) {
	return new ReferencePipeline.StatelessOp<Long, U>(this, StreamShape.LONG_VALUE, opFlags) {
	@Override
	Sink<Long> opWrapSink(int flags, Sink<U> sink) {
	return new Sink.ChainedLong<U>(sink) {
	@Override
	public void accept(long t) {
	downstream.accept(mapper.apply(t));
	}
	};
	}
	};
	}

	// LongStream

	@Override
	public final PrimitiveIterator.OfLong iterator() {
	return Spliterators.iterator(spliterator());
	}

	@Override
	public final Spliterator.OfLong spliterator() {
	return adapt(super.spliterator());
	}

	// Stateless intermediate ops from LongStream

	@Override
	public final DoubleStream asDoubleStream() {
	return new DoublePipeline.StatelessOp<Long>(this, StreamShape.LONG_VALUE, StreamOpFlag.NOT_DISTINCT) {
	@Override
	Sink<Long> opWrapSink(int flags, Sink<Double> sink) {
	return new Sink.ChainedLong<Double>(sink) {
	@Override
	public void accept(long t) {
	downstream.accept((double) t);
	}
	};
	}
	};
	}

	@Override
	public final Stream<Long> boxed() {
	return mapToObj(Long::valueOf, 0);
	}

	@Override
	public final LongStream map(LongUnaryOperator mapper) {
	Objects.requireNonNull(mapper);
	return new StatelessOp<Long>(this, StreamShape.LONG_VALUE,
	StreamOpFlag.NOT_SORTED \| StreamOpFlag.NOT_DISTINCT) {
	@Override
	Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
	return new Sink.ChainedLong<Long>(sink) {
	@Override
	public void accept(long t) {
	downstream.accept(mapper.applyAsLong(t));
	}
	};
	}
	};
	}

	@Override
	public final <U> Stream<U> mapToObj(LongFunction<? extends U> mapper) {
	Objects.requireNonNull(mapper);
	return mapToObj(mapper, StreamOpFlag.NOT_SORTED \| StreamOpFlag.NOT_DISTINCT);
	}

	@Override
	public final IntStream mapToInt(LongToIntFunction mapper) {
	Objects.requireNonNull(mapper);
	return new IntPipeline.StatelessOp<Long>(this, StreamShape.LONG_VALUE,
	StreamOpFlag.NOT_SORTED \| StreamOpFlag.NOT_DISTINCT) {
	@Override
	Sink<Long> opWrapSink(int flags, Sink<Integer> sink) {
	return new Sink.ChainedLong<Integer>(sink) {
	@Override
	public void accept(long t) {
	downstream.accept(mapper.applyAsInt(t));
	}
	};
	}
	};
	}

	@Override
	public final DoubleStream mapToDouble(LongToDoubleFunction mapper) {
	Objects.requireNonNull(mapper);
	return new DoublePipeline.StatelessOp<Long>(this, StreamShape.LONG_VALUE,
	StreamOpFlag.NOT_SORTED \| StreamOpFlag.NOT_DISTINCT) {
	@Override
	Sink<Long> opWrapSink(int flags, Sink<Double> sink) {
	return new Sink.ChainedLong<Double>(sink) {
	@Override
	public void accept(long t) {
	downstream.accept(mapper.applyAsDouble(t));
	}
	};
	}
	};
	}

	@Override
	public final LongStream flatMap(LongFunction<? extends LongStream> mapper) {
	Objects.requireNonNull(mapper);
	return new StatelessOp<Long>(this, StreamShape.LONG_VALUE,
	StreamOpFlag.NOT_SORTED \| StreamOpFlag.NOT_DISTINCT \| StreamOpFlag.NOT_SIZED) {
	@Override
	Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
	return new Sink.ChainedLong<Long>(sink) {
	// true if cancellationRequested() has been called
	boolean cancellationRequestedCalled;

	// cache the consumer to avoid creation on every accepted element
	LongConsumer downstreamAsLong = downstream::accept;

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

	@Override
	public void accept(long t) {
	try (LongStream result = mapper.apply(t)) {
	if (result != null) {
	if (!cancellationRequestedCalled) {
	result.sequential().forEach(downstreamAsLong);
	}
	else {
	var s = result.sequential().spliterator();
	do { } while (!downstream.cancellationRequested() && s.tryAdvance(downstreamAsLong));
	}
	}
	}
	}

	@Override
	public boolean cancellationRequested() {
	// If this method is called then an operation within the stream
	// pipeline is short-circuiting (see AbstractPipeline.copyInto).
	// Note that we cannot differentiate between an upstream or
	// downstream operation
	cancellationRequestedCalled = true;
	return downstream.cancellationRequested();
	}
	};
	}
	};
	}

	@Override
	public LongStream unordered() {
	if (!isOrdered())
	return this;
	return new StatelessOp<Long>(this, StreamShape.LONG_VALUE, StreamOpFlag.NOT_ORDERED) {
	@Override
	Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
	return sink;
	}
	};
	}

	@Override
	public final LongStream filter(LongPredicate predicate) {
	Objects.requireNonNull(predicate);
	return new StatelessOp<Long>(this, StreamShape.LONG_VALUE,
	StreamOpFlag.NOT_SIZED) {
	@Override
	Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
	return new Sink.ChainedLong<Long>(sink) {
	@Override
	public void begin(long size) {
	downstream.begin(-1);
	}

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

	@Override
	public final LongStream peek(LongConsumer action) {
	Objects.requireNonNull(action);
	return new StatelessOp<Long>(this, StreamShape.LONG_VALUE,
	0) {
	@Override
	Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
	return new Sink.ChainedLong<Long>(sink) {
	@Override
	public void accept(long t) {
	action.accept(t);
	downstream.accept(t);
	}
	};
	}
	};
	}

	// Stateful intermediate ops from LongStream

	@Override
	public final LongStream limit(long maxSize) {
	if (maxSize < 0)
	throw new IllegalArgumentException(Long.toString(maxSize));
	return SliceOps.makeLong(this, 0, maxSize);
	}

	@Override
	public final LongStream skip(long n) {
	if (n < 0)
	throw new IllegalArgumentException(Long.toString(n));
	if (n == 0)
	return this;
	else
	return SliceOps.makeLong(this, n, -1);
	}

	@Override
	public final LongStream takeWhile(LongPredicate predicate) {
	return WhileOps.makeTakeWhileLong(this, predicate);
	}

	@Override
	public final LongStream dropWhile(LongPredicate predicate) {
	return WhileOps.makeDropWhileLong(this, predicate);
	}

	@Override
	public final LongStream sorted() {
	return SortedOps.makeLong(this);
	}

	@Override
	public final LongStream distinct() {
	// While functional and quick to implement, this approach is not very efficient.
	// An efficient version requires a long-specific map/set implementation.
	return boxed().distinct().mapToLong(i -> (long) i);
	}

	// Terminal ops from LongStream

	@Override
	public void forEach(LongConsumer action) {
	evaluate(ForEachOps.makeLong(action, false));
	}

	@Override
	public void forEachOrdered(LongConsumer action) {
	evaluate(ForEachOps.makeLong(action, true));
	}

	@Override
	public final long sum() {
	// use better algorithm to compensate for intermediate overflow?
	return reduce(0, Long::sum);
	}

	@Override
	public final OptionalLong min() {
	return reduce(Math::min);
	}

	@Override
	public final OptionalLong max() {
	return reduce(Math::max);
	}

	@Override
	public final OptionalDouble average() {
	long[] avg = collect(() -> new long[2],
	(ll, i) -> {
	ll[0]++;
	ll[1] += i;
	},
	(ll, rr) -> {
	ll[0] += rr[0];
	ll[1] += rr[1];
	});
	return avg[0] > 0
	? OptionalDouble.of((double) avg[1] / avg[0])
	: OptionalDouble.empty();
	}

	@Override
	public final long count() {
	return evaluate(ReduceOps.makeLongCounting());
	}

	@Override
	public final LongSummaryStatistics summaryStatistics() {
	return collect(LongSummaryStatistics::new, LongSummaryStatistics::accept,
	LongSummaryStatistics::combine);
	}

	@Override
	public final long reduce(long identity, LongBinaryOperator op) {
	return evaluate(ReduceOps.makeLong(identity, op));
	}

	@Override
	public final OptionalLong reduce(LongBinaryOperator op) {
	return evaluate(ReduceOps.makeLong(op));
	}

	@Override
	public final <R> R collect(Supplier<R> supplier,
	ObjLongConsumer<R> accumulator,
	BiConsumer<R, R> combiner) {
	Objects.requireNonNull(combiner);
	BinaryOperator<R> operator = (left, right) -> {
	combiner.accept(left, right);
	return left;
	};
	return evaluate(ReduceOps.makeLong(supplier, accumulator, operator));
	}

	@Override
	public final boolean anyMatch(LongPredicate predicate) {
	return evaluate(MatchOps.makeLong(predicate, MatchOps.MatchKind.ANY));
	}

	@Override
	public final boolean allMatch(LongPredicate predicate) {
	return evaluate(MatchOps.makeLong(predicate, MatchOps.MatchKind.ALL));
	}

	@Override
	public final boolean noneMatch(LongPredicate predicate) {
	return evaluate(MatchOps.makeLong(predicate, MatchOps.MatchKind.NONE));
	}

	@Override
	public final OptionalLong findFirst() {
	return evaluate(FindOps.makeLong(true));
	}

	@Override
	public final OptionalLong findAny() {
	return evaluate(FindOps.makeLong(false));
	}

	@Override
	public final long[] toArray() {
	return Nodes.flattenLong((Node.OfLong) evaluateToArrayNode(Long[]::new))
	.asPrimitiveArray();
	}


	//

	/**
	* Source stage of a LongPipeline.
	*
	* @param <E_IN> type of elements in the upstream source
	* @since 1.8
	*/
	static class Head<E_IN> extends LongPipeline<E_IN> {
	/**
	* Constructor for the source stage of a LongStream.
	*
	* @param source {@code Supplier<Spliterator>} describing the stream
	* source
	* @param sourceFlags the source flags for the stream source, described
	* in {@link StreamOpFlag}
	* @param parallel {@code true} if the pipeline is parallel
	*/
	Head(Supplier<? extends Spliterator<Long>> source,
	int sourceFlags, boolean parallel) {
	super(source, sourceFlags, parallel);
	}

	/**
	* Constructor for the source stage of a LongStream.
	*
	* @param source {@code Spliterator} describing the stream source
	* @param sourceFlags the source flags for the stream source, described
	* in {@link StreamOpFlag}
	* @param parallel {@code true} if the pipeline is parallel
	*/
	Head(Spliterator<Long> source,
	int sourceFlags, boolean parallel) {
	super(source, sourceFlags, parallel);
	}

	@Override
	final boolean opIsStateful() {
	throw new UnsupportedOperationException();
	}

	@Override
	final Sink<E_IN> opWrapSink(int flags, Sink<Long> sink) {
	throw new UnsupportedOperationException();
	}

	// Optimized sequential terminal operations for the head of the pipeline

	@Override
	public void forEach(LongConsumer action) {
	if (!isParallel()) {
	adapt(sourceStageSpliterator()).forEachRemaining(action);
	} else {
	super.forEach(action);
	}
	}

	@Override
	public void forEachOrdered(LongConsumer action) {
	if (!isParallel()) {
	adapt(sourceStageSpliterator()).forEachRemaining(action);
	} else {
	super.forEachOrdered(action);
	}
	}
	}

	/** Base class for a stateless intermediate stage of a LongStream.
	*
	* @param <E_IN> type of elements in the upstream source
	* @since 1.8
	*/
	abstract static class StatelessOp<E_IN> extends LongPipeline<E_IN> {
	/**
	* Construct a new LongStream by appending a stateless intermediate
	* operation to an existing stream.
	* @param upstream The upstream pipeline stage
	* @param inputShape The stream shape for the upstream pipeline stage
	* @param opFlags Operation flags for the new stage
	*/
	StatelessOp(AbstractPipeline<?, E_IN, ?> upstream,
	StreamShape inputShape,
	int opFlags) {
	super(upstream, opFlags);
	assert upstream.getOutputShape() == inputShape;
	}

	@Override
	final boolean opIsStateful() {
	return false;
	}
	}

	/**
	* Base class for a stateful intermediate stage of a LongStream.
	*
	* @param <E_IN> type of elements in the upstream source
	* @since 1.8
	*/
	abstract static class StatefulOp<E_IN> extends LongPipeline<E_IN> {
	/**
	* Construct a new LongStream by appending a stateful intermediate
	* operation to an existing stream.
	* @param upstream The upstream pipeline stage
	* @param inputShape The stream shape for the upstream pipeline stage
	* @param opFlags Operation flags for the new stage
	*/
	StatefulOp(AbstractPipeline<?, E_IN, ?> upstream,
	StreamShape inputShape,
	int opFlags) {
	super(upstream, opFlags);
	assert upstream.getOutputShape() == inputShape;
	}

	@Override
	final boolean opIsStateful() {
	return true;
	}

	@Override
	abstract <P_IN> Node<Long> opEvaluateParallel(PipelineHelper<Long> helper,
	Spliterator<P_IN> spliterator,
	IntFunction<Long[]> generator);
	}
	}

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