/*
 * 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 Spliterator and its primitive specializations OfInt, OfLong, and OfDouble. 
See Also:
Spliterator
Since:
1.8/**
 * 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 Spliterator 
The empty spliterator reports Spliterator.SIZED and Spliterator.SUBSIZED. Calls to Spliterator.trySplit() always return null. 
Type parameters:
<T> – Type of elements
Returns:
An empty spliterator/**
     * 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 Spliterator.OfInt 
The empty spliterator reports Spliterator.SIZED and Spliterator.SUBSIZED. Calls to Spliterator.trySplit() always return null. 
Returns:
An empty spliterator/**
     * 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 Spliterator.OfLong 
The empty spliterator reports Spliterator.SIZED and Spliterator.SUBSIZED. Calls to Spliterator.trySplit() always return null. 
Returns:
An empty spliterator/**
     * 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 Spliterator.OfDouble 
The empty spliterator reports Spliterator.SIZED and Spliterator.SUBSIZED. Calls to Spliterator.trySplit() always return null. 
Returns:
An empty spliterator/**
     * 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 Spliterator covering the elements of a given array, using a customized set of spliterator characteristics. 
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 Arrays.spliterator(Object[]). 
The returned spliterator always reports the characteristics SIZED and SUBSIZED. The caller may provide additional characteristics for the spliterator to report; it is common to additionally specify IMMUTABLE and ORDERED. 
Params:
array – The array, assumed to be unmodified during use
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported
Type parameters:
<T> – Type of elements
Throws:
NullPointerException – if the given array is null
See Also:
Arrays.spliterator(Object[])
Returns:
A spliterator for an array/**
     * 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 Spliterator covering a range of elements of a given array, using a customized set of spliterator characteristics. 
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 Arrays.spliterator(Object[]). 
The returned spliterator always reports the characteristics SIZED and SUBSIZED. The caller may provide additional characteristics for the spliterator to report; it is common to additionally specify IMMUTABLE and ORDERED. 
Params:
array – The array, assumed to be unmodified during use
fromIndex – The least index (inclusive) to cover
toIndex – One past the greatest index to cover
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported
Type parameters:
<T> – Type of elements
Throws:
NullPointerException – if the given array is null
ArrayIndexOutOfBoundsException – if fromIndex is negative, toIndex is less than fromIndex, or toIndex is greater than the array size
See Also:
Arrays.spliterator(Object[], int, int)
Returns:
A spliterator for an array/**
     * 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 Spliterator.OfInt covering the elements of a given array, using a customized set of spliterator characteristics. 
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 Arrays.spliterator(int[]). 
The returned spliterator always reports the characteristics SIZED and SUBSIZED. The caller may provide additional characteristics for the spliterator to report; it is common to additionally specify IMMUTABLE and ORDERED. 
Params:
array – The array, assumed to be unmodified during use
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported
Throws:
NullPointerException – if the given array is null
See Also:
Arrays.spliterator(int[])
Returns:
A spliterator for an array/**
     * 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 Spliterator.OfInt covering a range of elements of a given array, using a customized set of spliterator characteristics. 
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 Arrays.spliterator(int[], int, int). 
The returned spliterator always reports the characteristics SIZED and SUBSIZED. The caller may provide additional characteristics for the spliterator to report; it is common to additionally specify IMMUTABLE and ORDERED. 
Params:
array – The array, assumed to be unmodified during use
fromIndex – The least index (inclusive) to cover
toIndex – One past the greatest index to cover
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported
Throws:
NullPointerException – if the given array is null
ArrayIndexOutOfBoundsException – if fromIndex is negative, toIndex is less than fromIndex, or toIndex is greater than the array size
See Also:
Arrays.spliterator(int[], int, int)
Returns:
A spliterator for an array/**
     * 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 Spliterator.OfLong covering the elements of a given array, using a customized set of spliterator characteristics. 
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 Arrays.spliterator(long[]). 
The returned spliterator always reports the characteristics SIZED and SUBSIZED. The caller may provide additional characteristics for the spliterator to report; it is common to additionally specify IMMUTABLE and ORDERED. 
Params:
array – The array, assumed to be unmodified during use
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported
Throws:
NullPointerException – if the given array is null
See Also:
Arrays.spliterator(long[])
Returns:
A spliterator for an array/**
     * 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 Spliterator.OfLong covering a range of elements of a given array, using a customized set of spliterator characteristics. 
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 Arrays.spliterator(long[], int, int). 
The returned spliterator always reports the characteristics SIZED and 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 IMMUTABLE; if the array data is considered to have an encounter order, specify ORDERED). The method Arrays.spliterator(long[], int, int) can often be used instead, which returns a spliterator that reports SIZED, SUBSIZED, IMMUTABLE, and ORDERED. 
Params:
array – The array, assumed to be unmodified during use
fromIndex – The least index (inclusive) to cover
toIndex – One past the greatest index to cover
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported
Throws:
NullPointerException – if the given array is null
ArrayIndexOutOfBoundsException – if fromIndex is negative, toIndex is less than fromIndex, or toIndex is greater than the array size
See Also:
Arrays.spliterator(long[], int, int)
Returns:
A spliterator for an array/**
     * 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 Spliterator.OfDouble covering the elements of a given array, using a customized set of spliterator characteristics. 
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 Arrays.spliterator(double[]). 
The returned spliterator always reports the characteristics SIZED and SUBSIZED. The caller may provide additional characteristics for the spliterator to report; it is common to additionally specify IMMUTABLE and ORDERED. 
Params:
array – The array, assumed to be unmodified during use
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported
Throws:
NullPointerException – if the given array is null
See Also:
Arrays.spliterator(double[])
Returns:
A spliterator for an array/**
     * 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 Spliterator.OfDouble covering a range of elements of a given array, using a customized set of spliterator characteristics. 
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 Arrays.spliterator(double[], int, int). 
The returned spliterator always reports the characteristics SIZED and 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 IMMUTABLE; if the array data is considered to have an encounter order, specify ORDERED). The method Arrays.spliterator(long[], int, int) can often be used instead, which returns a spliterator that reports SIZED, SUBSIZED, IMMUTABLE, and ORDERED. 
Params:
array – The array, assumed to be unmodified during use
fromIndex – The least index (inclusive) to cover
toIndex – One past the greatest index to cover
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported
Throws:
NullPointerException – if the given array is null
ArrayIndexOutOfBoundsException – if fromIndex is negative, toIndex is less than fromIndex, or toIndex is greater than the array size
See Also:
Arrays.spliterator(double[], int, int)
Returns:
A spliterator for an array/**
     * 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.
Params:
arrayLength – The length of the array
origin – The inclusive start index
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/**
     * 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 Spliterator using the given collection's Collection.iterator() as the source of elements, and reporting its Collection.size() as its initial size. 
The spliterator is
late-binding, inherits
the fail-fast properties of the collection's iterator, and implements trySplit to permit limited parallelism. 
Params:
c – The collection
characteristics – Characteristics of this spliterator's source or elements. The characteristics SIZED and SUBSIZED are additionally reported unless CONCURRENT is supplied.
Type parameters:
<T> – Type of elements
Throws:
NullPointerException – if the given collection is null
Returns:
A spliterator from an iterator/**
     * 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 Spliterator using a given Iterator as the source of elements, and with a given initially reported size. 
The spliterator is not
late-binding, inherits
the fail-fast properties of the iterator, and implements trySplit to permit limited parallelism. 
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.
Params:
iterator – The iterator for the source
size – The number of elements in the source, to be reported as initial estimateSize
characteristics – Characteristics of this spliterator's source or elements. The characteristics SIZED and SUBSIZED are additionally reported unless CONCURRENT is supplied.
Type parameters:
<T> – Type of elements
Throws:
NullPointerException – if the given iterator is null
Returns:
A spliterator from an iterator/**
     * 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 Spliterator using a given Iterator as the source of elements, with no initial size estimate. 
The spliterator is not
late-binding, inherits
the fail-fast properties of the iterator, and implements trySplit to permit limited parallelism. 
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.
Params:
iterator – The iterator for the source
characteristics – Characteristics of this spliterator's source or elements (SIZED and SUBSIZED, if supplied, are ignored and are not reported.)
Type parameters:
<T> – Type of elements
Throws:
NullPointerException – if the given iterator is null
Returns:
A spliterator from an iterator/**
     * 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 Spliterator.OfInt using a given IntStream.IntIterator as the source of elements, and with a given initially reported size. 
The spliterator is not
late-binding, inherits
the fail-fast properties of the iterator, and implements trySplit to permit limited parallelism. 
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.
Params:
iterator – The iterator for the source
size – The number of elements in the source, to be reported as initial estimateSize.
characteristics – Characteristics of this spliterator's source or elements. The characteristics SIZED and SUBSIZED are additionally reported unless CONCURRENT is supplied.
Throws:
NullPointerException – if the given iterator is null
Returns:
A spliterator from an iterator/**
     * 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 Spliterator.OfInt using a given IntStream.IntIterator as the source of elements, with no initial size estimate. 
The spliterator is not
late-binding, inherits
the fail-fast properties of the iterator, and implements trySplit to permit limited parallelism. 
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.
Params:
iterator – The iterator for the source
characteristics – Characteristics of this spliterator's source or elements (SIZED and SUBSIZED, if supplied, are ignored and are not reported.)
Throws:
NullPointerException – if the given iterator is null
Returns:
A spliterator from an iterator/**
     * 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 Spliterator.OfLong using a given LongStream.LongIterator as the source of elements, and with a given initially reported size. 
The spliterator is not
late-binding, inherits
the fail-fast properties of the iterator, and implements trySplit to permit limited parallelism. 
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.
Params:
iterator – The iterator for the source
size – The number of elements in the source, to be reported as initial estimateSize.
characteristics – Characteristics of this spliterator's source or elements. The characteristics SIZED and SUBSIZED are additionally reported unless CONCURRENT is supplied.
Throws:
NullPointerException – if the given iterator is null
Returns:
A spliterator from an iterator/**
     * 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 Spliterator.OfLong using a given LongStream.LongIterator as the source of elements, with no initial size estimate. 
The spliterator is not
late-binding, inherits
the fail-fast properties of the iterator, and implements trySplit to permit limited parallelism. 
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.
Params:
iterator – The iterator for the source
characteristics – Characteristics of this spliterator's source or elements (SIZED and SUBSIZED, if supplied, are ignored and are not reported.)
Throws:
NullPointerException – if the given iterator is null
Returns:
A spliterator from an iterator/**
     * 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 Spliterator.OfDouble using a given DoubleStream.DoubleIterator as the source of elements, and with a given initially reported size. 
The spliterator is not
late-binding, inherits
the fail-fast properties of the iterator, and implements trySplit to permit limited parallelism. 
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.
Params:
iterator – The iterator for the source
size – The number of elements in the source, to be reported as initial estimateSize
characteristics – Characteristics of this spliterator's source or elements. The characteristics SIZED and SUBSIZED are additionally reported unless CONCURRENT is supplied.
Throws:
NullPointerException – if the given iterator is null
Returns:
A spliterator from an iterator/**
     * 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 Spliterator.OfDouble using a given DoubleStream.DoubleIterator as the source of elements, with no initial size estimate. 
The spliterator is not
late-binding, inherits
the fail-fast properties of the iterator, and implements trySplit to permit limited parallelism. 
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.
Params:
iterator – The iterator for the source
characteristics – Characteristics of this spliterator's source or elements (SIZED and SUBSIZED, if supplied, are ignored and are not reported.)
Throws:
NullPointerException – if the given iterator is null
Returns:
A spliterator from an iterator/**
     * 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 Iterator from a Spliterator. 
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.
Params:
spliterator – The spliterator
Type parameters:
<T> – Type of elements
Throws:
NullPointerException – if the given spliterator is null
Returns:
An iterator/**
     * 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 PrimitiveIterator.OfInt from a Spliterator.OfInt. 
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.
Params:
spliterator – The spliterator
Throws:
NullPointerException – if the given spliterator is null
Returns:
An iterator/**
     * 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 PrimitiveIterator.OfLong from a Spliterator.OfLong. 
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.
Params:
spliterator – The spliterator
Throws:
NullPointerException – if the given spliterator is null
Returns:
An iterator/**
     * 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 PrimitiveIterator.OfDouble from a Spliterator.OfDouble. 
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.
Params:
spliterator – The spliterator
Throws:
NullPointerException – if the given spliterator is null
Returns:
An iterator/**
     * 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 Object[] array. /**
     * 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.
/**
         * 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.
Params:
array – the array, assumed to be unmodified during use
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported/**
         * 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
Params:
array – the array, assumed to be unmodified during use
origin – the least index (inclusive) to cover
fence – one past the greatest index to cover
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported/**
         * 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 int[] array. /**
     * 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.
Params:
array – the array, assumed to be unmodified during use
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported/**
         * 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
Params:
array – the array, assumed to be unmodified during use
origin – the least index (inclusive) to cover
fence – one past the greatest index to cover
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported/**
         * 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 int[] array. /**
     * 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.
Params:
array – the array, assumed to be unmodified during use
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported/**
         * 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
Params:
array – the array, assumed to be unmodified during use
origin – the least index (inclusive) to cover
fence – one past the greatest index to cover
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported/**
         * 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 int[] array. /**
     * 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.
Params:
array – the array, assumed to be unmodified during use
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported/**
         * 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
Params:
array – the array, assumed to be unmodified during use
origin – the least index (inclusive) to cover
fence – one past the greatest index to cover
additionalCharacteristics – Additional spliterator characteristics of this spliterator's source or elements beyond SIZED and SUBSIZED which are always reported/**
         * 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 Spliterator that implements trySplit to permit limited parallelism. 
An extending class need only implement tryAdvance. The extending class should override forEachRemaining if it can provide a more performant implementation. 
See Also:
Spliterators.spliterator(Iterator<? extends Object>, long, int)
API Note:

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.
An alternative to using this class, that also permits limited parallelism, is to create a spliterator from an iterator (see Spliterators.spliterator(Iterator<? extends Object>, 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.
Since:
1.8/**
     * 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.
Params:
est – the estimated size of this spliterator if known, otherwise Long.MAX_VALUE.
additionalCharacteristics – properties of this spliterator's source or elements. If SIZED is reported then this spliterator will additionally report SUBSIZED./**
         * 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.
/**
         * {@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}
Implementation Requirements:

This implementation returns the estimated size as reported when
created and, if the estimate size is known, decreases in size when
split./**
         * {@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}
Implementation Requirements:

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

    
An abstract Spliterator.OfInt that implements trySplit to permit limited parallelism. 
To implement a spliterator an extending class need only implement 
tryAdvance. The extending class should override forEachRemaining if it can provide a more performant implementation. 
See Also:
Spliterators.spliterator(OfInt, long, int)
API Note:

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.
An alternative to using this class, that also permits limited parallelism, is to create a spliterator from an iterator (see Spliterators.spliterator(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.
Since:
1.8/**
     * 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.
Params:
est – the estimated size of this spliterator if known, otherwise Long.MAX_VALUE.
additionalCharacteristics – properties of this spliterator's source or elements. If SIZED is reported then this spliterator will additionally report SUBSIZED./**
         * 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.
/**
         * {@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}
Implementation Requirements:

This implementation returns the estimated size as reported when
created and, if the estimate size is known, decreases in size when
split./**
         * {@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}
Implementation Requirements:

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

    
An abstract Spliterator.OfLong that implements trySplit to permit limited parallelism. 
To implement a spliterator an extending class need only implement 
tryAdvance. The extending class should override forEachRemaining if it can provide a more performant implementation. 
See Also:
Spliterators.spliterator(OfLong, long, int)
API Note:

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.
An alternative to using this class, that also permits limited parallelism, is to create a spliterator from an iterator (see Spliterators.spliterator(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.
Since:
1.8/**
     * 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.
Params:
est – the estimated size of this spliterator if known, otherwise Long.MAX_VALUE.
additionalCharacteristics – properties of this spliterator's source or elements. If SIZED is reported then this spliterator will additionally report SUBSIZED./**
         * 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.
/**
         * {@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}
Implementation Requirements:

This implementation returns the estimated size as reported when
created and, if the estimate size is known, decreases in size when
split./**
         * {@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}
Implementation Requirements:

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

    
An abstract Spliterator.OfDouble that implements trySplit to permit limited parallelism. 
To implement a spliterator an extending class need only implement 
tryAdvance. The extending class should override forEachRemaining if it can provide a more performant implementation. 
See Also:
Spliterators.spliterator(OfDouble, long, int)
API Note:

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.
An alternative to using this class, that also permits limited parallelism, is to create a spliterator from an iterator (see Spliterators.spliterator(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.
Since:
1.8/**
     * 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.
Params:
est – the estimated size of this spliterator if known, otherwise Long.MAX_VALUE.
additionalCharacteristics – properties of this spliterator's source or elements. If SIZED is reported then this spliterator will additionally report SUBSIZED./**
         * 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.
/**
         * {@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}
Implementation Requirements:

This implementation returns the estimated size as reported when
created and, if the estimate size is known, decreases in size when
split./**
         * {@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}
Implementation Requirements:

This implementation returns the characteristics as reported when
created./**
         * {@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 trySplit to permit limited parallelism. /**
     * 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 java.util.Collection#iterator()) for traversal,
and reporting its size.
Params:
c – the collection
characteristics – properties of this spliterator's
       source or elements./**
         * 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.
Params:
iterator – the iterator for the source
size – the number of elements in the source
characteristics – properties of this spliterator's
source or elements./**
         * 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.
Params:
iterator – the iterator for the source
characteristics – properties of this spliterator's
source or elements./**
         * 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 trySplit to permit limited parallelism. /**
     * 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.
Params:
iterator – the iterator for the source
size – the number of elements in the source
characteristics – properties of this spliterator's
source or elements./**
         * 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.
Params:
iterator – the iterator for the source
characteristics – properties of this spliterator's
source or elements./**
         * 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.
Params:
iterator – the iterator for the source
size – the number of elements in the source
characteristics – properties of this spliterator's
source or elements./**
         * 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.
Params:
iterator – the iterator for the source
characteristics – properties of this spliterator's
source or elements./**
         * 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.
Params:
iterator – the iterator for the source
size – the number of elements in the source
characteristics – properties of this spliterator's
source or elements./**
         * 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.
Params:
iterator – the iterator for the source
characteristics – properties of this spliterator's
source or elements./**
         * 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();
        }
    }
}