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	/*
	* Copyright (c) 2013, 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;

	import java.util.function.Consumer;
	import java.util.function.DoubleConsumer;
	import java.util.function.IntConsumer;
	import java.util.function.LongConsumer;

	/**
	* Static classes and methods for operating on or creating instances of
	* {@link Spliterator} and its primitive specializations
	* {@link Spliterator.OfInt}, {@link Spliterator.OfLong}, and
	* {@link Spliterator.OfDouble}.
	*
	* @see Spliterator
	* @since 1.8
	*/
	public final class Spliterators {

	// Suppresses default constructor, ensuring non-instantiability.
	private Spliterators() {}

	// Empty spliterators

	/**
	* Creates an empty {@code Spliterator}
	*
	* <p>The empty spliterator reports {@link Spliterator#SIZED} and
	* {@link Spliterator#SUBSIZED}. Calls to
	* {@link java.util.Spliterator#trySplit()} always return {@code null}.
	*
	* @param <T> Type of elements
	* @return An empty spliterator
	*/
	@SuppressWarnings("unchecked")
	public static <T> Spliterator<T> emptySpliterator() {
	return (Spliterator<T>) EMPTY_SPLITERATOR;
	}

	private static final Spliterator<Object> EMPTY_SPLITERATOR =
	new EmptySpliterator.OfRef<>();

	/**
	* Creates an empty {@code Spliterator.OfInt}
	*
	* <p>The empty spliterator reports {@link Spliterator#SIZED} and
	* {@link Spliterator#SUBSIZED}. Calls to
	* {@link java.util.Spliterator#trySplit()} always return {@code null}.
	*
	* @return An empty spliterator
	*/
	public static Spliterator.OfInt emptyIntSpliterator() {
	return EMPTY_INT_SPLITERATOR;
	}

	private static final Spliterator.OfInt EMPTY_INT_SPLITERATOR =
	new EmptySpliterator.OfInt();

	/**
	* Creates an empty {@code Spliterator.OfLong}
	*
	* <p>The empty spliterator reports {@link Spliterator#SIZED} and
	* {@link Spliterator#SUBSIZED}. Calls to
	* {@link java.util.Spliterator#trySplit()} always return {@code null}.
	*
	* @return An empty spliterator
	*/
	public static Spliterator.OfLong emptyLongSpliterator() {
	return EMPTY_LONG_SPLITERATOR;
	}

	private static final Spliterator.OfLong EMPTY_LONG_SPLITERATOR =
	new EmptySpliterator.OfLong();

	/**
	* Creates an empty {@code Spliterator.OfDouble}
	*
	* <p>The empty spliterator reports {@link Spliterator#SIZED} and
	* {@link Spliterator#SUBSIZED}. Calls to
	* {@link java.util.Spliterator#trySplit()} always return {@code null}.
	*
	* @return An empty spliterator
	*/
	public static Spliterator.OfDouble emptyDoubleSpliterator() {
	return EMPTY_DOUBLE_SPLITERATOR;
	}

	private static final Spliterator.OfDouble EMPTY_DOUBLE_SPLITERATOR =
	new EmptySpliterator.OfDouble();

	// Array-based spliterators

	/**
	* Creates a {@code Spliterator} covering the elements of a given array,
	* using a customized set of spliterator characteristics.
	*
	* <p>This method is provided as an implementation convenience for
	* Spliterators which store portions of their elements in arrays, and need
	* fine control over Spliterator characteristics. Most other situations in
	* which a Spliterator for an array is needed should use
	* {@link Arrays#spliterator(Object[])}.
	*
	* <p>The returned spliterator always reports the characteristics
	* {@code SIZED} and {@code SUBSIZED}. The caller may provide additional
	* characteristics for the spliterator to report; it is common to
	* additionally specify {@code IMMUTABLE} and {@code ORDERED}.
	*
	* @param <T> Type of elements
	* @param array The array, assumed to be unmodified during use
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	* @return A spliterator for an array
	* @throws NullPointerException if the given array is {@code null}
	* @see Arrays#spliterator(Object[])
	*/
	public static <T> Spliterator<T> spliterator(Object[] array,
	int additionalCharacteristics) {
	return new ArraySpliterator<>(Objects.requireNonNull(array),
	additionalCharacteristics);
	}

	/**
	* Creates a {@code Spliterator} covering a range of elements of a given
	* array, using a customized set of spliterator characteristics.
	*
	* <p>This method is provided as an implementation convenience for
	* Spliterators which store portions of their elements in arrays, and need
	* fine control over Spliterator characteristics. Most other situations in
	* which a Spliterator for an array is needed should use
	* {@link Arrays#spliterator(Object[])}.
	*
	* <p>The returned spliterator always reports the characteristics
	* {@code SIZED} and {@code SUBSIZED}. The caller may provide additional
	* characteristics for the spliterator to report; it is common to
	* additionally specify {@code IMMUTABLE} and {@code ORDERED}.
	*
	* @param <T> Type of elements
	* @param array The array, assumed to be unmodified during use
	* @param fromIndex The least index (inclusive) to cover
	* @param toIndex One past the greatest index to cover
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	* @return A spliterator for an array
	* @throws NullPointerException if the given array is {@code null}
	* @throws ArrayIndexOutOfBoundsException if {@code fromIndex} is negative,
	* {@code toIndex} is less than {@code fromIndex}, or
	* {@code toIndex} is greater than the array size
	* @see Arrays#spliterator(Object[], int, int)
	*/
	public static <T> Spliterator<T> spliterator(Object[] array, int fromIndex, int toIndex,
	int additionalCharacteristics) {
	checkFromToBounds(Objects.requireNonNull(array).length, fromIndex, toIndex);
	return new ArraySpliterator<>(array, fromIndex, toIndex, additionalCharacteristics);
	}

	/**
	* Creates a {@code Spliterator.OfInt} covering the elements of a given array,
	* using a customized set of spliterator characteristics.
	*
	* <p>This method is provided as an implementation convenience for
	* Spliterators which store portions of their elements in arrays, and need
	* fine control over Spliterator characteristics. Most other situations in
	* which a Spliterator for an array is needed should use
	* {@link Arrays#spliterator(int[])}.
	*
	* <p>The returned spliterator always reports the characteristics
	* {@code SIZED} and {@code SUBSIZED}. The caller may provide additional
	* characteristics for the spliterator to report; it is common to
	* additionally specify {@code IMMUTABLE} and {@code ORDERED}.
	*
	* @param array The array, assumed to be unmodified during use
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	* @return A spliterator for an array
	* @throws NullPointerException if the given array is {@code null}
	* @see Arrays#spliterator(int[])
	*/
	public static Spliterator.OfInt spliterator(int[] array,
	int additionalCharacteristics) {
	return new IntArraySpliterator(Objects.requireNonNull(array), additionalCharacteristics);
	}

	/**
	* Creates a {@code Spliterator.OfInt} covering a range of elements of a
	* given array, using a customized set of spliterator characteristics.
	*
	* <p>This method is provided as an implementation convenience for
	* Spliterators which store portions of their elements in arrays, and need
	* fine control over Spliterator characteristics. Most other situations in
	* which a Spliterator for an array is needed should use
	* {@link Arrays#spliterator(int[], int, int)}.
	*
	* <p>The returned spliterator always reports the characteristics
	* {@code SIZED} and {@code SUBSIZED}. The caller may provide additional
	* characteristics for the spliterator to report; it is common to
	* additionally specify {@code IMMUTABLE} and {@code ORDERED}.
	*
	* @param array The array, assumed to be unmodified during use
	* @param fromIndex The least index (inclusive) to cover
	* @param toIndex One past the greatest index to cover
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	* @return A spliterator for an array
	* @throws NullPointerException if the given array is {@code null}
	* @throws ArrayIndexOutOfBoundsException if {@code fromIndex} is negative,
	* {@code toIndex} is less than {@code fromIndex}, or
	* {@code toIndex} is greater than the array size
	* @see Arrays#spliterator(int[], int, int)
	*/
	public static Spliterator.OfInt spliterator(int[] array, int fromIndex, int toIndex,
	int additionalCharacteristics) {
	checkFromToBounds(Objects.requireNonNull(array).length, fromIndex, toIndex);
	return new IntArraySpliterator(array, fromIndex, toIndex, additionalCharacteristics);
	}

	/**
	* Creates a {@code Spliterator.OfLong} covering the elements of a given array,
	* using a customized set of spliterator characteristics.
	*
	* <p>This method is provided as an implementation convenience for
	* Spliterators which store portions of their elements in arrays, and need
	* fine control over Spliterator characteristics. Most other situations in
	* which a Spliterator for an array is needed should use
	* {@link Arrays#spliterator(long[])}.
	*
	* <p>The returned spliterator always reports the characteristics
	* {@code SIZED} and {@code SUBSIZED}. The caller may provide additional
	* characteristics for the spliterator to report; it is common to
	* additionally specify {@code IMMUTABLE} and {@code ORDERED}.
	*
	* @param array The array, assumed to be unmodified during use
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	* @return A spliterator for an array
	* @throws NullPointerException if the given array is {@code null}
	* @see Arrays#spliterator(long[])
	*/
	public static Spliterator.OfLong spliterator(long[] array,
	int additionalCharacteristics) {
	return new LongArraySpliterator(Objects.requireNonNull(array), additionalCharacteristics);
	}

	/**
	* Creates a {@code Spliterator.OfLong} covering a range of elements of a
	* given array, using a customized set of spliterator characteristics.
	*
	* <p>This method is provided as an implementation convenience for
	* Spliterators which store portions of their elements in arrays, and need
	* fine control over Spliterator characteristics. Most other situations in
	* which a Spliterator for an array is needed should use
	* {@link Arrays#spliterator(long[], int, int)}.
	*
	* <p>The returned spliterator always reports the characteristics
	* {@code SIZED} and {@code SUBSIZED}. The caller may provide additional
	* characteristics for the spliterator to report. (For example, if it is
	* known the array will not be further modified, specify {@code IMMUTABLE};
	* if the array data is considered to have an encounter order, specify
	* {@code ORDERED}). The method {@link Arrays#spliterator(long[], int, int)} can
	* often be used instead, which returns a spliterator that reports
	* {@code SIZED}, {@code SUBSIZED}, {@code IMMUTABLE}, and {@code ORDERED}.
	*
	* @param array The array, assumed to be unmodified during use
	* @param fromIndex The least index (inclusive) to cover
	* @param toIndex One past the greatest index to cover
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	* @return A spliterator for an array
	* @throws NullPointerException if the given array is {@code null}
	* @throws ArrayIndexOutOfBoundsException if {@code fromIndex} is negative,
	* {@code toIndex} is less than {@code fromIndex}, or
	* {@code toIndex} is greater than the array size
	* @see Arrays#spliterator(long[], int, int)
	*/
	public static Spliterator.OfLong spliterator(long[] array, int fromIndex, int toIndex,
	int additionalCharacteristics) {
	checkFromToBounds(Objects.requireNonNull(array).length, fromIndex, toIndex);
	return new LongArraySpliterator(array, fromIndex, toIndex, additionalCharacteristics);
	}

	/**
	* Creates a {@code Spliterator.OfDouble} covering the elements of a given array,
	* using a customized set of spliterator characteristics.
	*
	* <p>This method is provided as an implementation convenience for
	* Spliterators which store portions of their elements in arrays, and need
	* fine control over Spliterator characteristics. Most other situations in
	* which a Spliterator for an array is needed should use
	* {@link Arrays#spliterator(double[])}.
	*
	* <p>The returned spliterator always reports the characteristics
	* {@code SIZED} and {@code SUBSIZED}. The caller may provide additional
	* characteristics for the spliterator to report; it is common to
	* additionally specify {@code IMMUTABLE} and {@code ORDERED}.
	*
	* @param array The array, assumed to be unmodified during use
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	* @return A spliterator for an array
	* @throws NullPointerException if the given array is {@code null}
	* @see Arrays#spliterator(double[])
	*/
	public static Spliterator.OfDouble spliterator(double[] array,
	int additionalCharacteristics) {
	return new DoubleArraySpliterator(Objects.requireNonNull(array), additionalCharacteristics);
	}

	/**
	* Creates a {@code Spliterator.OfDouble} covering a range of elements of a
	* given array, using a customized set of spliterator characteristics.
	*
	* <p>This method is provided as an implementation convenience for
	* Spliterators which store portions of their elements in arrays, and need
	* fine control over Spliterator characteristics. Most other situations in
	* which a Spliterator for an array is needed should use
	* {@link Arrays#spliterator(double[], int, int)}.
	*
	* <p>The returned spliterator always reports the characteristics
	* {@code SIZED} and {@code SUBSIZED}. The caller may provide additional
	* characteristics for the spliterator to report. (For example, if it is
	* known the array will not be further modified, specify {@code IMMUTABLE};
	* if the array data is considered to have an encounter order, specify
	* {@code ORDERED}). The method {@link Arrays#spliterator(long[], int, int)} can
	* often be used instead, which returns a spliterator that reports
	* {@code SIZED}, {@code SUBSIZED}, {@code IMMUTABLE}, and {@code ORDERED}.
	*
	* @param array The array, assumed to be unmodified during use
	* @param fromIndex The least index (inclusive) to cover
	* @param toIndex One past the greatest index to cover
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	* @return A spliterator for an array
	* @throws NullPointerException if the given array is {@code null}
	* @throws ArrayIndexOutOfBoundsException if {@code fromIndex} is negative,
	* {@code toIndex} is less than {@code fromIndex}, or
	* {@code toIndex} is greater than the array size
	* @see Arrays#spliterator(double[], int, int)
	*/
	public static Spliterator.OfDouble spliterator(double[] array, int fromIndex, int toIndex,
	int additionalCharacteristics) {
	checkFromToBounds(Objects.requireNonNull(array).length, fromIndex, toIndex);
	return new DoubleArraySpliterator(array, fromIndex, toIndex, additionalCharacteristics);
	}

	/**
	* Validate inclusive start index and exclusive end index against the length
	* of an array.
	* @param arrayLength The length of the array
	* @param origin The inclusive start index
	* @param fence The exclusive end index
	* @throws ArrayIndexOutOfBoundsException if the start index is greater than
	* the end index, if the start index is negative, or the end index is
	* greater than the array length
	*/
	private static void checkFromToBounds(int arrayLength, int origin, int fence) {
	if (origin > fence) {
	throw new ArrayIndexOutOfBoundsException(
	"origin(" + origin + ") > fence(" + fence + ")");
	}
	if (origin < 0) {
	throw new ArrayIndexOutOfBoundsException(origin);
	}
	if (fence > arrayLength) {
	throw new ArrayIndexOutOfBoundsException(fence);
	}
	}

	// Iterator-based spliterators

	/**
	* Creates a {@code Spliterator} using the given collection's
	* {@link java.util.Collection#iterator()} as the source of elements, and
	* reporting its {@link java.util.Collection#size()} as its initial size.
	*
	* <p>The spliterator is
	* <em><a href="Spliterator.html#binding">late-binding</a></em>, inherits
	* the <em>fail-fast</em> properties of the collection's iterator, and
	* implements {@code trySplit} to permit limited parallelism.
	*
	* @param <T> Type of elements
	* @param c The collection
	* @param characteristics Characteristics of this spliterator's source or
	* elements. The characteristics {@code SIZED} and {@code SUBSIZED}
	* are additionally reported unless {@code CONCURRENT} is supplied.
	* @return A spliterator from an iterator
	* @throws NullPointerException if the given collection is {@code null}
	*/
	public static <T> Spliterator<T> spliterator(Collection<? extends T> c,
	int characteristics) {
	return new IteratorSpliterator<>(Objects.requireNonNull(c),
	characteristics);
	}

	/**
	* Creates a {@code Spliterator} using a given {@code Iterator}
	* as the source of elements, and with a given initially reported size.
	*
	* <p>The spliterator is not
	* <em><a href="Spliterator.html#binding">late-binding</a></em>, inherits
	* the <em>fail-fast</em> properties of the iterator, and implements
	* {@code trySplit} to permit limited parallelism.
	*
	* <p>Traversal of elements should be accomplished through the spliterator.
	* The behaviour of splitting and traversal is undefined if the iterator is
	* operated on after the spliterator is returned, or the initially reported
	* size is not equal to the actual number of elements in the source.
	*
	* @param <T> Type of elements
	* @param iterator The iterator for the source
	* @param size The number of elements in the source, to be reported as
	* initial {@code estimateSize}
	* @param characteristics Characteristics of this spliterator's source or
	* elements. The characteristics {@code SIZED} and {@code SUBSIZED}
	* are additionally reported unless {@code CONCURRENT} is supplied.
	* @return A spliterator from an iterator
	* @throws NullPointerException if the given iterator is {@code null}
	*/
	public static <T> Spliterator<T> spliterator(Iterator<? extends T> iterator,
	long size,
	int characteristics) {
	return new IteratorSpliterator<>(Objects.requireNonNull(iterator), size,
	characteristics);
	}

	/**
	* Creates a {@code Spliterator} using a given {@code Iterator}
	* as the source of elements, with no initial size estimate.
	*
	* <p>The spliterator is not
	* <em><a href="Spliterator.html#binding">late-binding</a></em>, inherits
	* the <em>fail-fast</em> properties of the iterator, and implements
	* {@code trySplit} to permit limited parallelism.
	*
	* <p>Traversal of elements should be accomplished through the spliterator.
	* The behaviour of splitting and traversal is undefined if the iterator is
	* operated on after the spliterator is returned.
	*
	* @param <T> Type of elements
	* @param iterator The iterator for the source
	* @param characteristics Characteristics of this spliterator's source
	* or elements ({@code SIZED} and {@code SUBSIZED}, if supplied, are
	* ignored and are not reported.)
	* @return A spliterator from an iterator
	* @throws NullPointerException if the given iterator is {@code null}
	*/
	public static <T> Spliterator<T> spliteratorUnknownSize(Iterator<? extends T> iterator,
	int characteristics) {
	return new IteratorSpliterator<>(Objects.requireNonNull(iterator), characteristics);
	}

	/**
	* Creates a {@code Spliterator.OfInt} using a given
	* {@code IntStream.IntIterator} as the source of elements, and with a given
	* initially reported size.
	*
	* <p>The spliterator is not
	* <em><a href="Spliterator.html#binding">late-binding</a></em>, inherits
	* the <em>fail-fast</em> properties of the iterator, and implements
	* {@code trySplit} to permit limited parallelism.
	*
	* <p>Traversal of elements should be accomplished through the spliterator.
	* The behaviour of splitting and traversal is undefined if the iterator is
	* operated on after the spliterator is returned, or the initially reported
	* size is not equal to the actual number of elements in the source.
	*
	* @param iterator The iterator for the source
	* @param size The number of elements in the source, to be reported as
	* initial {@code estimateSize}.
	* @param characteristics Characteristics of this spliterator's source or
	* elements. The characteristics {@code SIZED} and {@code SUBSIZED}
	* are additionally reported unless {@code CONCURRENT} is supplied.
	* @return A spliterator from an iterator
	* @throws NullPointerException if the given iterator is {@code null}
	*/
	public static Spliterator.OfInt spliterator(PrimitiveIterator.OfInt iterator,
	long size,
	int characteristics) {
	return new IntIteratorSpliterator(Objects.requireNonNull(iterator),
	size, characteristics);
	}

	/**
	* Creates a {@code Spliterator.OfInt} using a given
	* {@code IntStream.IntIterator} as the source of elements, with no initial
	* size estimate.
	*
	* <p>The spliterator is not
	* <em><a href="Spliterator.html#binding">late-binding</a></em>, inherits
	* the <em>fail-fast</em> properties of the iterator, and implements
	* {@code trySplit} to permit limited parallelism.
	*
	* <p>Traversal of elements should be accomplished through the spliterator.
	* The behaviour of splitting and traversal is undefined if the iterator is
	* operated on after the spliterator is returned.
	*
	* @param iterator The iterator for the source
	* @param characteristics Characteristics of this spliterator's source
	* or elements ({@code SIZED} and {@code SUBSIZED}, if supplied, are
	* ignored and are not reported.)
	* @return A spliterator from an iterator
	* @throws NullPointerException if the given iterator is {@code null}
	*/
	public static Spliterator.OfInt spliteratorUnknownSize(PrimitiveIterator.OfInt iterator,
	int characteristics) {
	return new IntIteratorSpliterator(Objects.requireNonNull(iterator), characteristics);
	}

	/**
	* Creates a {@code Spliterator.OfLong} using a given
	* {@code LongStream.LongIterator} as the source of elements, and with a
	* given initially reported size.
	*
	* <p>The spliterator is not
	* <em><a href="Spliterator.html#binding">late-binding</a></em>, inherits
	* the <em>fail-fast</em> properties of the iterator, and implements
	* {@code trySplit} to permit limited parallelism.
	*
	* <p>Traversal of elements should be accomplished through the spliterator.
	* The behaviour of splitting and traversal is undefined if the iterator is
	* operated on after the spliterator is returned, or the initially reported
	* size is not equal to the actual number of elements in the source.
	*
	* @param iterator The iterator for the source
	* @param size The number of elements in the source, to be reported as
	* initial {@code estimateSize}.
	* @param characteristics Characteristics of this spliterator's source or
	* elements. The characteristics {@code SIZED} and {@code SUBSIZED}
	* are additionally reported unless {@code CONCURRENT} is supplied.
	* @return A spliterator from an iterator
	* @throws NullPointerException if the given iterator is {@code null}
	*/
	public static Spliterator.OfLong spliterator(PrimitiveIterator.OfLong iterator,
	long size,
	int characteristics) {
	return new LongIteratorSpliterator(Objects.requireNonNull(iterator),
	size, characteristics);
	}

	/**
	* Creates a {@code Spliterator.OfLong} using a given
	* {@code LongStream.LongIterator} as the source of elements, with no
	* initial size estimate.
	*
	* <p>The spliterator is not
	* <em><a href="Spliterator.html#binding">late-binding</a></em>, inherits
	* the <em>fail-fast</em> properties of the iterator, and implements
	* {@code trySplit} to permit limited parallelism.
	*
	* <p>Traversal of elements should be accomplished through the spliterator.
	* The behaviour of splitting and traversal is undefined if the iterator is
	* operated on after the spliterator is returned.
	*
	* @param iterator The iterator for the source
	* @param characteristics Characteristics of this spliterator's source
	* or elements ({@code SIZED} and {@code SUBSIZED}, if supplied, are
	* ignored and are not reported.)
	* @return A spliterator from an iterator
	* @throws NullPointerException if the given iterator is {@code null}
	*/
	public static Spliterator.OfLong spliteratorUnknownSize(PrimitiveIterator.OfLong iterator,
	int characteristics) {
	return new LongIteratorSpliterator(Objects.requireNonNull(iterator), characteristics);
	}

	/**
	* Creates a {@code Spliterator.OfDouble} using a given
	* {@code DoubleStream.DoubleIterator} as the source of elements, and with a
	* given initially reported size.
	*
	* <p>The spliterator is not
	* <em><a href="Spliterator.html#binding">late-binding</a></em>, inherits
	* the <em>fail-fast</em> properties of the iterator, and implements
	* {@code trySplit} to permit limited parallelism.
	*
	* <p>Traversal of elements should be accomplished through the spliterator.
	* The behaviour of splitting and traversal is undefined if the iterator is
	* operated on after the spliterator is returned, or the initially reported
	* size is not equal to the actual number of elements in the source.
	*
	* @param iterator The iterator for the source
	* @param size The number of elements in the source, to be reported as
	* initial {@code estimateSize}
	* @param characteristics Characteristics of this spliterator's source or
	* elements. The characteristics {@code SIZED} and {@code SUBSIZED}
	* are additionally reported unless {@code CONCURRENT} is supplied.
	* @return A spliterator from an iterator
	* @throws NullPointerException if the given iterator is {@code null}
	*/
	public static Spliterator.OfDouble spliterator(PrimitiveIterator.OfDouble iterator,
	long size,
	int characteristics) {
	return new DoubleIteratorSpliterator(Objects.requireNonNull(iterator),
	size, characteristics);
	}

	/**
	* Creates a {@code Spliterator.OfDouble} using a given
	* {@code DoubleStream.DoubleIterator} as the source of elements, with no
	* initial size estimate.
	*
	* <p>The spliterator is not
	* <em><a href="Spliterator.html#binding">late-binding</a></em>, inherits
	* the <em>fail-fast</em> properties of the iterator, and implements
	* {@code trySplit} to permit limited parallelism.
	*
	* <p>Traversal of elements should be accomplished through the spliterator.
	* The behaviour of splitting and traversal is undefined if the iterator is
	* operated on after the spliterator is returned.
	*
	* @param iterator The iterator for the source
	* @param characteristics Characteristics of this spliterator's source
	* or elements ({@code SIZED} and {@code SUBSIZED}, if supplied, are
	* ignored and are not reported.)
	* @return A spliterator from an iterator
	* @throws NullPointerException if the given iterator is {@code null}
	*/
	public static Spliterator.OfDouble spliteratorUnknownSize(PrimitiveIterator.OfDouble iterator,
	int characteristics) {
	return new DoubleIteratorSpliterator(Objects.requireNonNull(iterator), characteristics);
	}

	// Iterators from Spliterators

	/**
	* Creates an {@code Iterator} from a {@code Spliterator}.
	*
	* <p>Traversal of elements should be accomplished through the iterator.
	* The behaviour of traversal is undefined if the spliterator is operated
	* after the iterator is returned.
	*
	* @param <T> Type of elements
	* @param spliterator The spliterator
	* @return An iterator
	* @throws NullPointerException if the given spliterator is {@code null}
	*/
	public static<T> Iterator<T> iterator(Spliterator<? extends T> spliterator) {
	Objects.requireNonNull(spliterator);
	class Adapter implements Iterator<T>, Consumer<T> {
	boolean valueReady = false;
	T nextElement;

	@Override
	public void accept(T t) {
	valueReady = true;
	nextElement = t;
	}

	@Override
	public boolean hasNext() {
	if (!valueReady)
	spliterator.tryAdvance(this);
	return valueReady;
	}

	@Override
	public T next() {
	if (!valueReady && !hasNext())
	throw new NoSuchElementException();
	else {
	valueReady = false;
	return nextElement;
	}
	}
	}

	return new Adapter();
	}

	/**
	* Creates an {@code PrimitiveIterator.OfInt} from a
	* {@code Spliterator.OfInt}.
	*
	* <p>Traversal of elements should be accomplished through the iterator.
	* The behaviour of traversal is undefined if the spliterator is operated
	* after the iterator is returned.
	*
	* @param spliterator The spliterator
	* @return An iterator
	* @throws NullPointerException if the given spliterator is {@code null}
	*/
	public static PrimitiveIterator.OfInt iterator(Spliterator.OfInt spliterator) {
	Objects.requireNonNull(spliterator);
	class Adapter implements PrimitiveIterator.OfInt, IntConsumer {
	boolean valueReady = false;
	int nextElement;

	@Override
	public void accept(int t) {
	valueReady = true;
	nextElement = t;
	}

	@Override
	public boolean hasNext() {
	if (!valueReady)
	spliterator.tryAdvance(this);
	return valueReady;
	}

	@Override
	public int nextInt() {
	if (!valueReady && !hasNext())
	throw new NoSuchElementException();
	else {
	valueReady = false;
	return nextElement;
	}
	}
	}

	return new Adapter();
	}

	/**
	* Creates an {@code PrimitiveIterator.OfLong} from a
	* {@code Spliterator.OfLong}.
	*
	* <p>Traversal of elements should be accomplished through the iterator.
	* The behaviour of traversal is undefined if the spliterator is operated
	* after the iterator is returned.
	*
	* @param spliterator The spliterator
	* @return An iterator
	* @throws NullPointerException if the given spliterator is {@code null}
	*/
	public static PrimitiveIterator.OfLong iterator(Spliterator.OfLong spliterator) {
	Objects.requireNonNull(spliterator);
	class Adapter implements PrimitiveIterator.OfLong, LongConsumer {
	boolean valueReady = false;
	long nextElement;

	@Override
	public void accept(long t) {
	valueReady = true;
	nextElement = t;
	}

	@Override
	public boolean hasNext() {
	if (!valueReady)
	spliterator.tryAdvance(this);
	return valueReady;
	}

	@Override
	public long nextLong() {
	if (!valueReady && !hasNext())
	throw new NoSuchElementException();
	else {
	valueReady = false;
	return nextElement;
	}
	}
	}

	return new Adapter();
	}

	/**
	* Creates an {@code PrimitiveIterator.OfDouble} from a
	* {@code Spliterator.OfDouble}.
	*
	* <p>Traversal of elements should be accomplished through the iterator.
	* The behaviour of traversal is undefined if the spliterator is operated
	* after the iterator is returned.
	*
	* @param spliterator The spliterator
	* @return An iterator
	* @throws NullPointerException if the given spliterator is {@code null}
	*/
	public static PrimitiveIterator.OfDouble iterator(Spliterator.OfDouble spliterator) {
	Objects.requireNonNull(spliterator);
	class Adapter implements PrimitiveIterator.OfDouble, DoubleConsumer {
	boolean valueReady = false;
	double nextElement;

	@Override
	public void accept(double t) {
	valueReady = true;
	nextElement = t;
	}

	@Override
	public boolean hasNext() {
	if (!valueReady)
	spliterator.tryAdvance(this);
	return valueReady;
	}

	@Override
	public double nextDouble() {
	if (!valueReady && !hasNext())
	throw new NoSuchElementException();
	else {
	valueReady = false;
	return nextElement;
	}
	}
	}

	return new Adapter();
	}

	// Implementations

	private abstract static class EmptySpliterator<T, S extends Spliterator<T>, C> {

	EmptySpliterator() { }

	public S trySplit() {
	return null;
	}

	public boolean tryAdvance(C consumer) {
	Objects.requireNonNull(consumer);
	return false;
	}

	public void forEachRemaining(C consumer) {
	Objects.requireNonNull(consumer);
	}

	public long estimateSize() {
	return 0;
	}

	public int characteristics() {
	return Spliterator.SIZED \| Spliterator.SUBSIZED;
	}

	private static final class OfRef<T>
	extends EmptySpliterator<T, Spliterator<T>, Consumer<? super T>>
	implements Spliterator<T> {
	OfRef() { }
	}

	private static final class OfInt
	extends EmptySpliterator<Integer, Spliterator.OfInt, IntConsumer>
	implements Spliterator.OfInt {
	OfInt() { }
	}

	private static final class OfLong
	extends EmptySpliterator<Long, Spliterator.OfLong, LongConsumer>
	implements Spliterator.OfLong {
	OfLong() { }
	}

	private static final class OfDouble
	extends EmptySpliterator<Double, Spliterator.OfDouble, DoubleConsumer>
	implements Spliterator.OfDouble {
	OfDouble() { }
	}
	}

	// Array-based spliterators

	/**
	* A Spliterator designed for use by sources that traverse and split
	* elements maintained in an unmodifiable {@code Object[]} array.
	*/
	static final class ArraySpliterator<T> implements Spliterator<T> {
	/**
	* The array, explicitly typed as Object[]. Unlike in some other
	* classes (see for example CR 6260652), we do not need to
	* screen arguments to ensure they are exactly of type Object[]
	* so long as no methods write into the array or serialize it,
	* which we ensure here by defining this class as final.
	*/
	private final Object[] array;
	private int index; // current index, modified on advance/split
	private final int fence; // one past last index
	private final int characteristics;

	/**
	* Creates a spliterator covering all of the given array.
	* @param array the array, assumed to be unmodified during use
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	*/
	public ArraySpliterator(Object[] array, int additionalCharacteristics) {
	this(array, 0, array.length, additionalCharacteristics);
	}

	/**
	* Creates a spliterator covering the given array and range
	* @param array the array, assumed to be unmodified during use
	* @param origin the least index (inclusive) to cover
	* @param fence one past the greatest index to cover
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	*/
	public ArraySpliterator(Object[] array, int origin, int fence, int additionalCharacteristics) {
	this.array = array;
	this.index = origin;
	this.fence = fence;
	this.characteristics = additionalCharacteristics \| Spliterator.SIZED \| Spliterator.SUBSIZED;
	}

	@Override
	public Spliterator<T> trySplit() {
	int lo = index, mid = (lo + fence) >>> 1;
	return (lo >= mid)
	? null
	: new ArraySpliterator<>(array, lo, index = mid, characteristics);
	}

	@SuppressWarnings("unchecked")
	@Override
	public void forEachRemaining(Consumer<? super T> action) {
	Object[] a; int i, hi; // hoist accesses and checks from loop
	if (action == null)
	throw new NullPointerException();
	if ((a = array).length >= (hi = fence) &&
	(i = index) >= 0 && i < (index = hi)) {
	do { action.accept((T)a[i]); } while (++i < hi);
	}
	}

	@Override
	public boolean tryAdvance(Consumer<? super T> action) {
	if (action == null)
	throw new NullPointerException();
	if (index >= 0 && index < fence) {
	@SuppressWarnings("unchecked") T e = (T) array[index++];
	action.accept(e);
	return true;
	}
	return false;
	}

	@Override
	public long estimateSize() { return (long)(fence - index); }

	@Override
	public int characteristics() {
	return characteristics;
	}

	@Override
	public Comparator<? super T> getComparator() {
	if (hasCharacteristics(Spliterator.SORTED))
	return null;
	throw new IllegalStateException();
	}
	}

	/**
	* A Spliterator.OfInt designed for use by sources that traverse and split
	* elements maintained in an unmodifiable {@code int[]} array.
	*/
	static final class IntArraySpliterator implements Spliterator.OfInt {
	private final int[] array;
	private int index; // current index, modified on advance/split
	private final int fence; // one past last index
	private final int characteristics;

	/**
	* Creates a spliterator covering all of the given array.
	* @param array the array, assumed to be unmodified during use
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	*/
	public IntArraySpliterator(int[] array, int additionalCharacteristics) {
	this(array, 0, array.length, additionalCharacteristics);
	}

	/**
	* Creates a spliterator covering the given array and range
	* @param array the array, assumed to be unmodified during use
	* @param origin the least index (inclusive) to cover
	* @param fence one past the greatest index to cover
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	*/
	public IntArraySpliterator(int[] array, int origin, int fence, int additionalCharacteristics) {
	this.array = array;
	this.index = origin;
	this.fence = fence;
	this.characteristics = additionalCharacteristics \| Spliterator.SIZED \| Spliterator.SUBSIZED;
	}

	@Override
	public OfInt trySplit() {
	int lo = index, mid = (lo + fence) >>> 1;
	return (lo >= mid)
	? null
	: new IntArraySpliterator(array, lo, index = mid, characteristics);
	}

	@Override
	public void forEachRemaining(IntConsumer action) {
	int[] a; int i, hi; // hoist accesses and checks from loop
	if (action == null)
	throw new NullPointerException();
	if ((a = array).length >= (hi = fence) &&
	(i = index) >= 0 && i < (index = hi)) {
	do { action.accept(a[i]); } while (++i < hi);
	}
	}

	@Override
	public boolean tryAdvance(IntConsumer action) {
	if (action == null)
	throw new NullPointerException();
	if (index >= 0 && index < fence) {
	action.accept(array[index++]);
	return true;
	}
	return false;
	}

	@Override
	public long estimateSize() { return (long)(fence - index); }

	@Override
	public int characteristics() {
	return characteristics;
	}

	@Override
	public Comparator<? super Integer> getComparator() {
	if (hasCharacteristics(Spliterator.SORTED))
	return null;
	throw new IllegalStateException();
	}
	}

	/**
	* A Spliterator.OfLong designed for use by sources that traverse and split
	* elements maintained in an unmodifiable {@code int[]} array.
	*/
	static final class LongArraySpliterator implements Spliterator.OfLong {
	private final long[] array;
	private int index; // current index, modified on advance/split
	private final int fence; // one past last index
	private final int characteristics;

	/**
	* Creates a spliterator covering all of the given array.
	* @param array the array, assumed to be unmodified during use
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	*/
	public LongArraySpliterator(long[] array, int additionalCharacteristics) {
	this(array, 0, array.length, additionalCharacteristics);
	}

	/**
	* Creates a spliterator covering the given array and range
	* @param array the array, assumed to be unmodified during use
	* @param origin the least index (inclusive) to cover
	* @param fence one past the greatest index to cover
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	*/
	public LongArraySpliterator(long[] array, int origin, int fence, int additionalCharacteristics) {
	this.array = array;
	this.index = origin;
	this.fence = fence;
	this.characteristics = additionalCharacteristics \| Spliterator.SIZED \| Spliterator.SUBSIZED;
	}

	@Override
	public OfLong trySplit() {
	int lo = index, mid = (lo + fence) >>> 1;
	return (lo >= mid)
	? null
	: new LongArraySpliterator(array, lo, index = mid, characteristics);
	}

	@Override
	public void forEachRemaining(LongConsumer action) {
	long[] a; int i, hi; // hoist accesses and checks from loop
	if (action == null)
	throw new NullPointerException();
	if ((a = array).length >= (hi = fence) &&
	(i = index) >= 0 && i < (index = hi)) {
	do { action.accept(a[i]); } while (++i < hi);
	}
	}

	@Override
	public boolean tryAdvance(LongConsumer action) {
	if (action == null)
	throw new NullPointerException();
	if (index >= 0 && index < fence) {
	action.accept(array[index++]);
	return true;
	}
	return false;
	}

	@Override
	public long estimateSize() { return (long)(fence - index); }

	@Override
	public int characteristics() {
	return characteristics;
	}

	@Override
	public Comparator<? super Long> getComparator() {
	if (hasCharacteristics(Spliterator.SORTED))
	return null;
	throw new IllegalStateException();
	}
	}

	/**
	* A Spliterator.OfDouble designed for use by sources that traverse and split
	* elements maintained in an unmodifiable {@code int[]} array.
	*/
	static final class DoubleArraySpliterator implements Spliterator.OfDouble {
	private final double[] array;
	private int index; // current index, modified on advance/split
	private final int fence; // one past last index
	private final int characteristics;

	/**
	* Creates a spliterator covering all of the given array.
	* @param array the array, assumed to be unmodified during use
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	*/
	public DoubleArraySpliterator(double[] array, int additionalCharacteristics) {
	this(array, 0, array.length, additionalCharacteristics);
	}

	/**
	* Creates a spliterator covering the given array and range
	* @param array the array, assumed to be unmodified during use
	* @param origin the least index (inclusive) to cover
	* @param fence one past the greatest index to cover
	* @param additionalCharacteristics Additional spliterator characteristics
	* of this spliterator's source or elements beyond {@code SIZED} and
	* {@code SUBSIZED} which are always reported
	*/
	public DoubleArraySpliterator(double[] array, int origin, int fence, int additionalCharacteristics) {
	this.array = array;
	this.index = origin;
	this.fence = fence;
	this.characteristics = additionalCharacteristics \| Spliterator.SIZED \| Spliterator.SUBSIZED;
	}

	@Override
	public OfDouble trySplit() {
	int lo = index, mid = (lo + fence) >>> 1;
	return (lo >= mid)
	? null
	: new DoubleArraySpliterator(array, lo, index = mid, characteristics);
	}

	@Override
	public void forEachRemaining(DoubleConsumer action) {
	double[] a; int i, hi; // hoist accesses and checks from loop
	if (action == null)
	throw new NullPointerException();
	if ((a = array).length >= (hi = fence) &&
	(i = index) >= 0 && i < (index = hi)) {
	do { action.accept(a[i]); } while (++i < hi);
	}
	}

	@Override
	public boolean tryAdvance(DoubleConsumer action) {
	if (action == null)
	throw new NullPointerException();
	if (index >= 0 && index < fence) {
	action.accept(array[index++]);
	return true;
	}
	return false;
	}

	@Override
	public long estimateSize() { return (long)(fence - index); }

	@Override
	public int characteristics() {
	return characteristics;
	}

	@Override
	public Comparator<? super Double> getComparator() {
	if (hasCharacteristics(Spliterator.SORTED))
	return null;
	throw new IllegalStateException();
	}
	}

	//

	/**
	* An abstract {@code Spliterator} that implements {@code trySplit} to
	* permit limited parallelism.
	*
	* <p>An extending class need only
	* implement {@link #tryAdvance(java.util.function.Consumer) tryAdvance}.
	* The extending class should override
	* {@link #forEachRemaining(java.util.function.Consumer) forEachRemaining}
	* if it can provide a more performant implementation.
	*
	* @apiNote
	* This class is a useful aid for creating a spliterator when it is not
	* possible or difficult to efficiently partition elements in a manner
	* allowing balanced parallel computation.
	*
	* <p>An alternative to using this class, that also permits limited
	* parallelism, is to create a spliterator from an iterator
	* (see {@link #spliterator(Iterator, long, int)}. Depending on the
	* circumstances using an iterator may be easier or more convenient than
	* extending this class, such as when there is already an iterator
	* available to use.
	*
	* @see #spliterator(Iterator, long, int)
	* @since 1.8
	*/
	public abstract static class AbstractSpliterator<T> implements Spliterator<T> {
	static final int BATCH_UNIT = 1 << 10; // batch array size increment
	static final int MAX_BATCH = 1 << 25; // max batch array size;
	private final int characteristics;
	private long est; // size estimate
	private int batch; // batch size for splits

	/**
	* Creates a spliterator reporting the given estimated size and
	* additionalCharacteristics.
	*
	* @param est the estimated size of this spliterator if known, otherwise
	* {@code Long.MAX_VALUE}.
	* @param additionalCharacteristics properties of this spliterator's
	* source or elements. If {@code SIZED} is reported then this
	* spliterator will additionally report {@code SUBSIZED}.
	*/
	protected AbstractSpliterator(long est, int additionalCharacteristics) {
	this.est = est;
	this.characteristics = ((additionalCharacteristics & Spliterator.SIZED) != 0)
	? additionalCharacteristics \| Spliterator.SUBSIZED
	: additionalCharacteristics;
	}

	static final class HoldingConsumer<T> implements Consumer<T> {
	Object value;

	@Override
	public void accept(T value) {
	this.value = value;
	}
	}

	/**
	* {@inheritDoc}
	*
	* This implementation permits limited parallelism.
	*/
	@Override
	public Spliterator<T> trySplit() {
	/*
	* Split into arrays of arithmetically increasing batch
	* sizes. This will only improve parallel performance if
	* per-element Consumer actions are more costly than
	* transferring them into an array. The use of an
	* arithmetic progression in split sizes provides overhead
	* vs parallelism bounds that do not particularly favor or
	* penalize cases of lightweight vs heavyweight element
	* operations, across combinations of #elements vs #cores,
	* whether or not either are known. We generate
	* O(sqrt(#elements)) splits, allowing O(sqrt(#cores))
	* potential speedup.
	*/
	HoldingConsumer<T> holder = new HoldingConsumer<>();
	long s = est;
	if (s > 1 && tryAdvance(holder)) {
	int n = batch + BATCH_UNIT;
	if (n > s)
	n = (int) s;
	if (n > MAX_BATCH)
	n = MAX_BATCH;
	Object[] a = new Object[n];
	int j = 0;
	do { a[j] = holder.value; } while (++j < n && tryAdvance(holder));
	batch = j;
	if (est != Long.MAX_VALUE)
	est -= j;
	return new ArraySpliterator<>(a, 0, j, characteristics());
	}
	return null;
	}

	/**
	* {@inheritDoc}
	*
	* @implSpec
	* This implementation returns the estimated size as reported when
	* created and, if the estimate size is known, decreases in size when
	* split.
	*/
	@Override
	public long estimateSize() {
	return est;
	}

	/**
	* {@inheritDoc}
	*
	* @implSpec
	* This implementation returns the characteristics as reported when
	* created.
	*/
	@Override
	public int characteristics() {
	return characteristics;
	}
	}

	/**
	* An abstract {@code Spliterator.OfInt} that implements {@code trySplit} to
	* permit limited parallelism.
	*
	* <p>To implement a spliterator an extending class need only
	* implement {@link #tryAdvance(java.util.function.IntConsumer)
	* tryAdvance}. The extending class should override
	* {@link #forEachRemaining(java.util.function.IntConsumer) forEachRemaining}
	* if it can provide a more performant implementation.
	*
	* @apiNote
	* This class is a useful aid for creating a spliterator when it is not
	* possible or difficult to efficiently partition elements in a manner
	* allowing balanced parallel computation.
	*
	* <p>An alternative to using this class, that also permits limited
	* parallelism, is to create a spliterator from an iterator
	* (see {@link #spliterator(java.util.PrimitiveIterator.OfInt, long, int)}.
	* Depending on the circumstances using an iterator may be easier or more
	* convenient than extending this class. For example, if there is already an
	* iterator available to use then there is no need to extend this class.
	*
	* @see #spliterator(java.util.PrimitiveIterator.OfInt, long, int)
	* @since 1.8
	*/
	public abstract static class AbstractIntSpliterator implements Spliterator.OfInt {
	static final int MAX_BATCH = AbstractSpliterator.MAX_BATCH;
	static final int BATCH_UNIT = AbstractSpliterator.BATCH_UNIT;
	private final int characteristics;
	private long est; // size estimate
	private int batch; // batch size for splits

	/**
	* Creates a spliterator reporting the given estimated size and
	* characteristics.
	*
	* @param est the estimated size of this spliterator if known, otherwise
	* {@code Long.MAX_VALUE}.
	* @param additionalCharacteristics properties of this spliterator's
	* source or elements. If {@code SIZED} is reported then this
	* spliterator will additionally report {@code SUBSIZED}.
	*/
	protected AbstractIntSpliterator(long est, int additionalCharacteristics) {
	this.est = est;
	this.characteristics = ((additionalCharacteristics & Spliterator.SIZED) != 0)
	? additionalCharacteristics \| Spliterator.SUBSIZED
	: additionalCharacteristics;
	}

	static final class HoldingIntConsumer implements IntConsumer {
	int value;

	@Override
	public void accept(int value) {
	this.value = value;
	}
	}

	/**
	* {@inheritDoc}
	*
	* This implementation permits limited parallelism.
	*/
	@Override
	public Spliterator.OfInt trySplit() {
	HoldingIntConsumer holder = new HoldingIntConsumer();
	long s = est;
	if (s > 1 && tryAdvance(holder)) {
	int n = batch + BATCH_UNIT;
	if (n > s)
	n = (int) s;
	if (n > MAX_BATCH)
	n = MAX_BATCH;
	int[] a = new int[n];
	int j = 0;
	do { a[j] = holder.value; } while (++j < n && tryAdvance(holder));
	batch = j;
	if (est != Long.MAX_VALUE)
	est -= j;
	return new IntArraySpliterator(a, 0, j, characteristics());
	}
	return null;
	}

	/**
	* {@inheritDoc}
	*
	* @implSpec
	* This implementation returns the estimated size as reported when
	* created and, if the estimate size is known, decreases in size when
	* split.
	*/
	@Override
	public long estimateSize() {
	return est;
	}

	/**
	* {@inheritDoc}
	*
	* @implSpec
	* This implementation returns the characteristics as reported when
	* created.
	*/
	@Override
	public int characteristics() {
	return characteristics;
	}
	}

	/**
	* An abstract {@code Spliterator.OfLong} that implements {@code trySplit}
	* to permit limited parallelism.
	*
	* <p>To implement a spliterator an extending class need only
	* implement {@link #tryAdvance(java.util.function.LongConsumer)
	* tryAdvance}. The extending class should override
	* {@link #forEachRemaining(java.util.function.LongConsumer) forEachRemaining}
	* if it can provide a more performant implementation.
	*
	* @apiNote
	* This class is a useful aid for creating a spliterator when it is not
	* possible or difficult to efficiently partition elements in a manner
	* allowing balanced parallel computation.
	*
	* <p>An alternative to using this class, that also permits limited
	* parallelism, is to create a spliterator from an iterator
	* (see {@link #spliterator(java.util.PrimitiveIterator.OfLong, long, int)}.
	* Depending on the circumstances using an iterator may be easier or more
	* convenient than extending this class. For example, if there is already an
	* iterator available to use then there is no need to extend this class.
	*
	* @see #spliterator(java.util.PrimitiveIterator.OfLong, long, int)
	* @since 1.8
	*/
	public abstract static class AbstractLongSpliterator implements Spliterator.OfLong {
	static final int MAX_BATCH = AbstractSpliterator.MAX_BATCH;
	static final int BATCH_UNIT = AbstractSpliterator.BATCH_UNIT;
	private final int characteristics;
	private long est; // size estimate
	private int batch; // batch size for splits

	/**
	* Creates a spliterator reporting the given estimated size and
	* characteristics.
	*
	* @param est the estimated size of this spliterator if known, otherwise
	* {@code Long.MAX_VALUE}.
	* @param additionalCharacteristics properties of this spliterator's
	* source or elements. If {@code SIZED} is reported then this
	* spliterator will additionally report {@code SUBSIZED}.
	*/
	protected AbstractLongSpliterator(long est, int additionalCharacteristics) {
	this.est = est;
	this.characteristics = ((additionalCharacteristics & Spliterator.SIZED) != 0)
	? additionalCharacteristics \| Spliterator.SUBSIZED
	: additionalCharacteristics;
	}

	static final class HoldingLongConsumer implements LongConsumer {
	long value;

	@Override
	public void accept(long value) {
	this.value = value;
	}
	}

	/**
	* {@inheritDoc}
	*
	* This implementation permits limited parallelism.
	*/
	@Override
	public Spliterator.OfLong trySplit() {
	HoldingLongConsumer holder = new HoldingLongConsumer();
	long s = est;
	if (s > 1 && tryAdvance(holder)) {
	int n = batch + BATCH_UNIT;
	if (n > s)
	n = (int) s;
	if (n > MAX_BATCH)
	n = MAX_BATCH;
	long[] a = new long[n];
	int j = 0;
	do { a[j] = holder.value; } while (++j < n && tryAdvance(holder));
	batch = j;
	if (est != Long.MAX_VALUE)
	est -= j;
	return new LongArraySpliterator(a, 0, j, characteristics());
	}
	return null;
	}

	/**
	* {@inheritDoc}
	*
	* @implSpec
	* This implementation returns the estimated size as reported when
	* created and, if the estimate size is known, decreases in size when
	* split.
	*/
	@Override
	public long estimateSize() {
	return est;
	}

	/**
	* {@inheritDoc}
	*
	* @implSpec
	* This implementation returns the characteristics as reported when
	* created.
	*/
	@Override
	public int characteristics() {
	return characteristics;
	}
	}

	/**
	* An abstract {@code Spliterator.OfDouble} that implements
	* {@code trySplit} to permit limited parallelism.
	*
	* <p>To implement a spliterator an extending class need only
	* implement {@link #tryAdvance(java.util.function.DoubleConsumer)
	* tryAdvance}. The extending class should override
	* {@link #forEachRemaining(java.util.function.DoubleConsumer) forEachRemaining}
	* if it can provide a more performant implementation.
	*
	* @apiNote
	* This class is a useful aid for creating a spliterator when it is not
	* possible or difficult to efficiently partition elements in a manner
	* allowing balanced parallel computation.
	*
	* <p>An alternative to using this class, that also permits limited
	* parallelism, is to create a spliterator from an iterator
	* (see {@link #spliterator(java.util.PrimitiveIterator.OfDouble, long, int)}.
	* Depending on the circumstances using an iterator may be easier or more
	* convenient than extending this class. For example, if there is already an
	* iterator available to use then there is no need to extend this class.
	*
	* @see #spliterator(java.util.PrimitiveIterator.OfDouble, long, int)
	* @since 1.8
	*/
	public abstract static class AbstractDoubleSpliterator implements Spliterator.OfDouble {
	static final int MAX_BATCH = AbstractSpliterator.MAX_BATCH;
	static final int BATCH_UNIT = AbstractSpliterator.BATCH_UNIT;
	private final int characteristics;
	private long est; // size estimate
	private int batch; // batch size for splits

	/**
	* Creates a spliterator reporting the given estimated size and
	* characteristics.
	*
	* @param est the estimated size of this spliterator if known, otherwise
	* {@code Long.MAX_VALUE}.
	* @param additionalCharacteristics properties of this spliterator's
	* source or elements. If {@code SIZED} is reported then this
	* spliterator will additionally report {@code SUBSIZED}.
	*/
	protected AbstractDoubleSpliterator(long est, int additionalCharacteristics) {
	this.est = est;
	this.characteristics = ((additionalCharacteristics & Spliterator.SIZED) != 0)
	? additionalCharacteristics \| Spliterator.SUBSIZED
	: additionalCharacteristics;
	}

	static final class HoldingDoubleConsumer implements DoubleConsumer {
	double value;

	@Override
	public void accept(double value) {
	this.value = value;
	}
	}

	/**
	* {@inheritDoc}
	*
	* This implementation permits limited parallelism.
	*/
	@Override
	public Spliterator.OfDouble trySplit() {
	HoldingDoubleConsumer holder = new HoldingDoubleConsumer();
	long s = est;
	if (s > 1 && tryAdvance(holder)) {
	int n = batch + BATCH_UNIT;
	if (n > s)
	n = (int) s;
	if (n > MAX_BATCH)
	n = MAX_BATCH;
	double[] a = new double[n];
	int j = 0;
	do { a[j] = holder.value; } while (++j < n && tryAdvance(holder));
	batch = j;
	if (est != Long.MAX_VALUE)
	est -= j;
	return new DoubleArraySpliterator(a, 0, j, characteristics());
	}
	return null;
	}

	/**
	* {@inheritDoc}
	*
	* @implSpec
	* This implementation returns the estimated size as reported when
	* created and, if the estimate size is known, decreases in size when
	* split.
	*/
	@Override
	public long estimateSize() {
	return est;
	}

	/**
	* {@inheritDoc}
	*
	* @implSpec
	* This implementation returns the characteristics as reported when
	* created.
	*/
	@Override
	public int characteristics() {
	return characteristics;
	}
	}

	// Iterator-based Spliterators

	/**
	* A Spliterator using a given Iterator for element
	* operations. The spliterator implements {@code trySplit} to
	* permit limited parallelism.
	*/
	static class IteratorSpliterator<T> implements Spliterator<T> {
	static final int BATCH_UNIT = 1 << 10; // batch array size increment
	static final int MAX_BATCH = 1 << 25; // max batch array size;
	private final Collection<? extends T> collection; // null OK
	private Iterator<? extends T> it;
	private final int characteristics;
	private long est; // size estimate
	private int batch; // batch size for splits

	/**
	* Creates a spliterator using the given
	* collection's {@link java.util.Collection#iterator()) for traversal,
	* and reporting its {@link java.util.Collection#size()) as its initial
	* size.
	*
	* @param c the collection
	* @param characteristics properties of this spliterator's
	* source or elements.
	*/
	public IteratorSpliterator(Collection<? extends T> collection, int characteristics) {
	this.collection = collection;
	this.it = null;
	this.characteristics = (characteristics & Spliterator.CONCURRENT) == 0
	? characteristics \| Spliterator.SIZED \| Spliterator.SUBSIZED
	: characteristics;
	}

	/**
	* Creates a spliterator using the given iterator
	* for traversal, and reporting the given initial size
	* and characteristics.
	*
	* @param iterator the iterator for the source
	* @param size the number of elements in the source
	* @param characteristics properties of this spliterator's
	* source or elements.
	*/
	public IteratorSpliterator(Iterator<? extends T> iterator, long size, int characteristics) {
	this.collection = null;
	this.it = iterator;
	this.est = size;
	this.characteristics = (characteristics & Spliterator.CONCURRENT) == 0
	? characteristics \| Spliterator.SIZED \| Spliterator.SUBSIZED
	: characteristics;
	}

	/**
	* Creates a spliterator using the given iterator
	* for traversal, and reporting the given initial size
	* and characteristics.
	*
	* @param iterator the iterator for the source
	* @param characteristics properties of this spliterator's
	* source or elements.
	*/
	public IteratorSpliterator(Iterator<? extends T> iterator, int characteristics) {
	this.collection = null;
	this.it = iterator;
	this.est = Long.MAX_VALUE;
	this.characteristics = characteristics & ~(Spliterator.SIZED \| Spliterator.SUBSIZED);
	}

	@Override
	public Spliterator<T> trySplit() {
	/*
	* Split into arrays of arithmetically increasing batch
	* sizes. This will only improve parallel performance if
	* per-element Consumer actions are more costly than
	* transferring them into an array. The use of an
	* arithmetic progression in split sizes provides overhead
	* vs parallelism bounds that do not particularly favor or
	* penalize cases of lightweight vs heavyweight element
	* operations, across combinations of #elements vs #cores,
	* whether or not either are known. We generate
	* O(sqrt(#elements)) splits, allowing O(sqrt(#cores))
	* potential speedup.
	*/
	Iterator<? extends T> i;
	long s;
	if ((i = it) == null) {
	i = it = collection.iterator();
	s = est = (long) collection.size();
	}
	else
	s = est;
	if (s > 1 && i.hasNext()) {
	int n = batch + BATCH_UNIT;
	if (n > s)
	n = (int) s;
	if (n > MAX_BATCH)
	n = MAX_BATCH;
	Object[] a = new Object[n];
	int j = 0;
	do { a[j] = i.next(); } while (++j < n && i.hasNext());
	batch = j;
	if (est != Long.MAX_VALUE)
	est -= j;
	return new ArraySpliterator<>(a, 0, j, characteristics);
	}
	return null;
	}

	@Override
	public void forEachRemaining(Consumer<? super T> action) {
	if (action == null) throw new NullPointerException();
	Iterator<? extends T> i;
	if ((i = it) == null) {
	i = it = collection.iterator();
	est = (long)collection.size();
	}
	i.forEachRemaining(action);
	}

	@Override
	public boolean tryAdvance(Consumer<? super T> action) {
	if (action == null) throw new NullPointerException();
	if (it == null) {
	it = collection.iterator();
	est = (long) collection.size();
	}
	if (it.hasNext()) {
	action.accept(it.next());
	return true;
	}
	return false;
	}

	@Override
	public long estimateSize() {
	if (it == null) {
	it = collection.iterator();
	return est = (long)collection.size();
	}
	return est;
	}

	@Override
	public int characteristics() { return characteristics; }

	@Override
	public Comparator<? super T> getComparator() {
	if (hasCharacteristics(Spliterator.SORTED))
	return null;
	throw new IllegalStateException();
	}
	}

	/**
	* A Spliterator.OfInt using a given IntStream.IntIterator for element
	* operations. The spliterator implements {@code trySplit} to
	* permit limited parallelism.
	*/
	static final class IntIteratorSpliterator implements Spliterator.OfInt {
	static final int BATCH_UNIT = IteratorSpliterator.BATCH_UNIT;
	static final int MAX_BATCH = IteratorSpliterator.MAX_BATCH;
	private PrimitiveIterator.OfInt it;
	private final int characteristics;
	private long est; // size estimate
	private int batch; // batch size for splits

	/**
	* Creates a spliterator using the given iterator
	* for traversal, and reporting the given initial size
	* and characteristics.
	*
	* @param iterator the iterator for the source
	* @param size the number of elements in the source
	* @param characteristics properties of this spliterator's
	* source or elements.
	*/
	public IntIteratorSpliterator(PrimitiveIterator.OfInt iterator, long size, int characteristics) {
	this.it = iterator;
	this.est = size;
	this.characteristics = (characteristics & Spliterator.CONCURRENT) == 0
	? characteristics \| Spliterator.SIZED \| Spliterator.SUBSIZED
	: characteristics;
	}

	/**
	* Creates a spliterator using the given iterator for a
	* source of unknown size, reporting the given
	* characteristics.
	*
	* @param iterator the iterator for the source
	* @param characteristics properties of this spliterator's
	* source or elements.
	*/
	public IntIteratorSpliterator(PrimitiveIterator.OfInt iterator, int characteristics) {
	this.it = iterator;
	this.est = Long.MAX_VALUE;
	this.characteristics = characteristics & ~(Spliterator.SIZED \| Spliterator.SUBSIZED);
	}

	@Override
	public OfInt trySplit() {
	PrimitiveIterator.OfInt i = it;
	long s = est;
	if (s > 1 && i.hasNext()) {
	int n = batch + BATCH_UNIT;
	if (n > s)
	n = (int) s;
	if (n > MAX_BATCH)
	n = MAX_BATCH;
	int[] a = new int[n];
	int j = 0;
	do { a[j] = i.nextInt(); } while (++j < n && i.hasNext());
	batch = j;
	if (est != Long.MAX_VALUE)
	est -= j;
	return new IntArraySpliterator(a, 0, j, characteristics);
	}
	return null;
	}

	@Override
	public void forEachRemaining(IntConsumer action) {
	if (action == null) throw new NullPointerException();
	it.forEachRemaining(action);
	}

	@Override
	public boolean tryAdvance(IntConsumer action) {
	if (action == null) throw new NullPointerException();
	if (it.hasNext()) {
	action.accept(it.nextInt());
	return true;
	}
	return false;
	}

	@Override
	public long estimateSize() {
	return est;
	}

	@Override
	public int characteristics() { return characteristics; }

	@Override
	public Comparator<? super Integer> getComparator() {
	if (hasCharacteristics(Spliterator.SORTED))
	return null;
	throw new IllegalStateException();
	}
	}

	static final class LongIteratorSpliterator implements Spliterator.OfLong {
	static final int BATCH_UNIT = IteratorSpliterator.BATCH_UNIT;
	static final int MAX_BATCH = IteratorSpliterator.MAX_BATCH;
	private PrimitiveIterator.OfLong it;
	private final int characteristics;
	private long est; // size estimate
	private int batch; // batch size for splits

	/**
	* Creates a spliterator using the given iterator
	* for traversal, and reporting the given initial size
	* and characteristics.
	*
	* @param iterator the iterator for the source
	* @param size the number of elements in the source
	* @param characteristics properties of this spliterator's
	* source or elements.
	*/
	public LongIteratorSpliterator(PrimitiveIterator.OfLong iterator, long size, int characteristics) {
	this.it = iterator;
	this.est = size;
	this.characteristics = (characteristics & Spliterator.CONCURRENT) == 0
	? characteristics \| Spliterator.SIZED \| Spliterator.SUBSIZED
	: characteristics;
	}

	/**
	* Creates a spliterator using the given iterator for a
	* source of unknown size, reporting the given
	* characteristics.
	*
	* @param iterator the iterator for the source
	* @param characteristics properties of this spliterator's
	* source or elements.
	*/
	public LongIteratorSpliterator(PrimitiveIterator.OfLong iterator, int characteristics) {
	this.it = iterator;
	this.est = Long.MAX_VALUE;
	this.characteristics = characteristics & ~(Spliterator.SIZED \| Spliterator.SUBSIZED);
	}

	@Override
	public OfLong trySplit() {
	PrimitiveIterator.OfLong i = it;
	long s = est;
	if (s > 1 && i.hasNext()) {
	int n = batch + BATCH_UNIT;
	if (n > s)
	n = (int) s;
	if (n > MAX_BATCH)
	n = MAX_BATCH;
	long[] a = new long[n];
	int j = 0;
	do { a[j] = i.nextLong(); } while (++j < n && i.hasNext());
	batch = j;
	if (est != Long.MAX_VALUE)
	est -= j;
	return new LongArraySpliterator(a, 0, j, characteristics);
	}
	return null;
	}

	@Override
	public void forEachRemaining(LongConsumer action) {
	if (action == null) throw new NullPointerException();
	it.forEachRemaining(action);
	}

	@Override
	public boolean tryAdvance(LongConsumer action) {
	if (action == null) throw new NullPointerException();
	if (it.hasNext()) {
	action.accept(it.nextLong());
	return true;
	}
	return false;
	}

	@Override
	public long estimateSize() {
	return est;
	}

	@Override
	public int characteristics() { return characteristics; }

	@Override
	public Comparator<? super Long> getComparator() {
	if (hasCharacteristics(Spliterator.SORTED))
	return null;
	throw new IllegalStateException();
	}
	}

	static final class DoubleIteratorSpliterator implements Spliterator.OfDouble {
	static final int BATCH_UNIT = IteratorSpliterator.BATCH_UNIT;
	static final int MAX_BATCH = IteratorSpliterator.MAX_BATCH;
	private PrimitiveIterator.OfDouble it;
	private final int characteristics;
	private long est; // size estimate
	private int batch; // batch size for splits

	/**
	* Creates a spliterator using the given iterator
	* for traversal, and reporting the given initial size
	* and characteristics.
	*
	* @param iterator the iterator for the source
	* @param size the number of elements in the source
	* @param characteristics properties of this spliterator's
	* source or elements.
	*/
	public DoubleIteratorSpliterator(PrimitiveIterator.OfDouble iterator, long size, int characteristics) {
	this.it = iterator;
	this.est = size;
	this.characteristics = (characteristics & Spliterator.CONCURRENT) == 0
	? characteristics \| Spliterator.SIZED \| Spliterator.SUBSIZED
	: characteristics;
	}

	/**
	* Creates a spliterator using the given iterator for a
	* source of unknown size, reporting the given
	* characteristics.
	*
	* @param iterator the iterator for the source
	* @param characteristics properties of this spliterator's
	* source or elements.
	*/
	public DoubleIteratorSpliterator(PrimitiveIterator.OfDouble iterator, int characteristics) {
	this.it = iterator;
	this.est = Long.MAX_VALUE;
	this.characteristics = characteristics & ~(Spliterator.SIZED \| Spliterator.SUBSIZED);
	}

	@Override
	public OfDouble trySplit() {
	PrimitiveIterator.OfDouble i = it;
	long s = est;
	if (s > 1 && i.hasNext()) {
	int n = batch + BATCH_UNIT;
	if (n > s)
	n = (int) s;
	if (n > MAX_BATCH)
	n = MAX_BATCH;
	double[] a = new double[n];
	int j = 0;
	do { a[j] = i.nextDouble(); } while (++j < n && i.hasNext());
	batch = j;
	if (est != Long.MAX_VALUE)
	est -= j;
	return new DoubleArraySpliterator(a, 0, j, characteristics);
	}
	return null;
	}

	@Override
	public void forEachRemaining(DoubleConsumer action) {
	if (action == null) throw new NullPointerException();
	it.forEachRemaining(action);
	}

	@Override
	public boolean tryAdvance(DoubleConsumer action) {
	if (action == null) throw new NullPointerException();
	if (it.hasNext()) {
	action.accept(it.nextDouble());
	return true;
	}
	return false;
	}

	@Override
	public long estimateSize() {
	return est;
	}

	@Override
	public int characteristics() { return characteristics; }

	@Override
	public Comparator<? super Double> getComparator() {
	if (hasCharacteristics(Spliterator.SORTED))
	return null;
	throw new IllegalStateException();
	}
	}
	}

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