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	/*
	* Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package java.util.stream;

	import java.util.ArrayDeque;
	import java.util.Arrays;
	import java.util.Collection;
	import java.util.Deque;
	import java.util.List;
	import java.util.Objects;
	import java.util.Spliterator;
	import java.util.Spliterators;
	import java.util.concurrent.CountedCompleter;
	import java.util.function.BinaryOperator;
	import java.util.function.Consumer;
	import java.util.function.DoubleConsumer;
	import java.util.function.IntConsumer;
	import java.util.function.IntFunction;
	import java.util.function.LongConsumer;
	import java.util.function.LongFunction;

	/**
	* Factory methods for constructing implementations of {@link Node} and
	* {@link Node.Builder} and their primitive specializations. Fork/Join tasks
	* for collecting output from a {@link PipelineHelper} to a {@link Node} and
	* flattening {@link Node}s.
	*
	* @since 1.8
	*/
	final class Nodes {

	private Nodes() {
	throw new Error("no instances");
	}

	/**
	* The maximum size of an array that can be allocated.
	*/
	static final long MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;

	// IllegalArgumentException messages
	static final String BAD_SIZE = "Stream size exceeds max array size";

	@SuppressWarnings("rawtypes")
	private static final Node EMPTY_NODE = new EmptyNode.OfRef();
	private static final Node.OfInt EMPTY_INT_NODE = new EmptyNode.OfInt();
	private static final Node.OfLong EMPTY_LONG_NODE = new EmptyNode.OfLong();
	private static final Node.OfDouble EMPTY_DOUBLE_NODE = new EmptyNode.OfDouble();

	/**
	* @return an array generator for an array whose elements are of type T.
	*/
	@SuppressWarnings("unchecked")
	static <T> IntFunction<T[]> castingArray() {
	return size -> (T[]) new Object[size];
	}

	// General shape-based node creation methods

	/**
	* Produces an empty node whose count is zero, has no children and no content.
	*
	* @param <T> the type of elements of the created node
	* @param shape the shape of the node to be created
	* @return an empty node.
	*/
	@SuppressWarnings("unchecked")
	static <T> Node<T> emptyNode(StreamShape shape) {
	return (Node<T>) switch (shape) {
	case REFERENCE -> EMPTY_NODE;
	case INT_VALUE -> EMPTY_INT_NODE;
	case LONG_VALUE -> EMPTY_LONG_NODE;
	case DOUBLE_VALUE -> EMPTY_DOUBLE_NODE;
	};
	}

	/**
	* Produces a concatenated {@link Node} that has two or more children.
	* <p>The count of the concatenated node is equal to the sum of the count
	* of each child. Traversal of the concatenated node traverses the content
	* of each child in encounter order of the list of children. Splitting a
	* spliterator obtained from the concatenated node preserves the encounter
	* order of the list of children.
	*
	* <p>The result may be a concatenated node, the input sole node if the size
	* of the list is 1, or an empty node.
	*
	* @param <T> the type of elements of the concatenated node
	* @param shape the shape of the concatenated node to be created
	* @param left the left input node
	* @param right the right input node
	* @return a {@code Node} covering the elements of the input nodes
	* @throws IllegalStateException if all {@link Node} elements of the list
	* are an not instance of type supported by this factory.
	*/
	@SuppressWarnings("unchecked")
	static <T> Node<T> conc(StreamShape shape, Node<T> left, Node<T> right) {
	return (Node<T>) switch (shape) {
	case REFERENCE -> new ConcNode<>(left, right);
	case INT_VALUE -> new ConcNode.OfInt((Node.OfInt) left, (Node.OfInt) right);
	case LONG_VALUE -> new ConcNode.OfLong((Node.OfLong) left, (Node.OfLong) right);
	case DOUBLE_VALUE -> new ConcNode.OfDouble((Node.OfDouble) left, (Node.OfDouble) right);
	};
	}

	// Reference-based node methods

	/**
	* Produces a {@link Node} describing an array.
	*
	* <p>The node will hold a reference to the array and will not make a copy.
	*
	* @param <T> the type of elements held by the node
	* @param array the array
	* @return a node holding an array
	*/
	static <T> Node<T> node(T[] array) {
	return new ArrayNode<>(array);
	}

	/**
	* Produces a {@link Node} describing a {@link Collection}.
	* <p>
	* The node will hold a reference to the collection and will not make a copy.
	*
	* @param <T> the type of elements held by the node
	* @param c the collection
	* @return a node holding a collection
	*/
	static <T> Node<T> node(Collection<T> c) {
	return new CollectionNode<>(c);
	}

	/**
	* Produces a {@link Node.Builder}.
	*
	* @param exactSizeIfKnown -1 if a variable size builder is requested,
	* otherwise the exact capacity desired. A fixed capacity builder will
	* fail if the wrong number of elements are added to the builder.
	* @param generator the array factory
	* @param <T> the type of elements of the node builder
	* @return a {@code Node.Builder}
	*/
	static <T> Node.Builder<T> builder(long exactSizeIfKnown, IntFunction<T[]> generator) {
	return (exactSizeIfKnown >= 0 && exactSizeIfKnown < MAX_ARRAY_SIZE)
	? new FixedNodeBuilder<>(exactSizeIfKnown, generator)
	: builder();
	}

	/**
	* Produces a variable size @{link Node.Builder}.
	*
	* @param <T> the type of elements of the node builder
	* @return a {@code Node.Builder}
	*/
	static <T> Node.Builder<T> builder() {
	return new SpinedNodeBuilder<>();
	}

	// Int nodes

	/**
	* Produces a {@link Node.OfInt} describing an int[] array.
	*
	* <p>The node will hold a reference to the array and will not make a copy.
	*
	* @param array the array
	* @return a node holding an array
	*/
	static Node.OfInt node(int[] array) {
	return new IntArrayNode(array);
	}

	/**
	* Produces a {@link Node.Builder.OfInt}.
	*
	* @param exactSizeIfKnown -1 if a variable size builder is requested,
	* otherwise the exact capacity desired. A fixed capacity builder will
	* fail if the wrong number of elements are added to the builder.
	* @return a {@code Node.Builder.OfInt}
	*/
	static Node.Builder.OfInt intBuilder(long exactSizeIfKnown) {
	return (exactSizeIfKnown >= 0 && exactSizeIfKnown < MAX_ARRAY_SIZE)
	? new IntFixedNodeBuilder(exactSizeIfKnown)
	: intBuilder();
	}

	/**
	* Produces a variable size @{link Node.Builder.OfInt}.
	*
	* @return a {@code Node.Builder.OfInt}
	*/
	static Node.Builder.OfInt intBuilder() {
	return new IntSpinedNodeBuilder();
	}

	// Long nodes

	/**
	* Produces a {@link Node.OfLong} describing a long[] array.
	* <p>
	* The node will hold a reference to the array and will not make a copy.
	*
	* @param array the array
	* @return a node holding an array
	*/
	static Node.OfLong node(final long[] array) {
	return new LongArrayNode(array);
	}

	/**
	* Produces a {@link Node.Builder.OfLong}.
	*
	* @param exactSizeIfKnown -1 if a variable size builder is requested,
	* otherwise the exact capacity desired. A fixed capacity builder will
	* fail if the wrong number of elements are added to the builder.
	* @return a {@code Node.Builder.OfLong}
	*/
	static Node.Builder.OfLong longBuilder(long exactSizeIfKnown) {
	return (exactSizeIfKnown >= 0 && exactSizeIfKnown < MAX_ARRAY_SIZE)
	? new LongFixedNodeBuilder(exactSizeIfKnown)
	: longBuilder();
	}

	/**
	* Produces a variable size @{link Node.Builder.OfLong}.
	*
	* @return a {@code Node.Builder.OfLong}
	*/
	static Node.Builder.OfLong longBuilder() {
	return new LongSpinedNodeBuilder();
	}

	// Double nodes

	/**
	* Produces a {@link Node.OfDouble} describing a double[] array.
	*
	* <p>The node will hold a reference to the array and will not make a copy.
	*
	* @param array the array
	* @return a node holding an array
	*/
	static Node.OfDouble node(final double[] array) {
	return new DoubleArrayNode(array);
	}

	/**
	* Produces a {@link Node.Builder.OfDouble}.
	*
	* @param exactSizeIfKnown -1 if a variable size builder is requested,
	* otherwise the exact capacity desired. A fixed capacity builder will
	* fail if the wrong number of elements are added to the builder.
	* @return a {@code Node.Builder.OfDouble}
	*/
	static Node.Builder.OfDouble doubleBuilder(long exactSizeIfKnown) {
	return (exactSizeIfKnown >= 0 && exactSizeIfKnown < MAX_ARRAY_SIZE)
	? new DoubleFixedNodeBuilder(exactSizeIfKnown)
	: doubleBuilder();
	}

	/**
	* Produces a variable size @{link Node.Builder.OfDouble}.
	*
	* @return a {@code Node.Builder.OfDouble}
	*/
	static Node.Builder.OfDouble doubleBuilder() {
	return new DoubleSpinedNodeBuilder();
	}

	// Parallel evaluation of pipelines to nodes

	/**
	* Collect, in parallel, elements output from a pipeline and describe those
	* elements with a {@link Node}.
	*
	* @implSpec
	* If the exact size of the output from the pipeline is known and the source
	* {@link Spliterator} has the {@link Spliterator#SUBSIZED} characteristic,
	* then a flat {@link Node} will be returned whose content is an array,
	* since the size is known the array can be constructed in advance and
	* output elements can be placed into the array concurrently by leaf
	* tasks at the correct offsets. If the exact size is not known, output
	* elements are collected into a conc-node whose shape mirrors that
	* of the computation. This conc-node can then be flattened in
	* parallel to produce a flat {@code Node} if desired.
	*
	* @param helper the pipeline helper describing the pipeline
	* @param flattenTree whether a conc node should be flattened into a node
	* describing an array before returning
	* @param generator the array generator
	* @return a {@link Node} describing the output elements
	*/
	public static <P_IN, P_OUT> Node<P_OUT> collect(PipelineHelper<P_OUT> helper,
	Spliterator<P_IN> spliterator,
	boolean flattenTree,
	IntFunction<P_OUT[]> generator) {
	long size = helper.exactOutputSizeIfKnown(spliterator);
	if (size >= 0 && spliterator.hasCharacteristics(Spliterator.SUBSIZED)) {
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	P_OUT[] array = generator.apply((int) size);
	new SizedCollectorTask.OfRef<>(spliterator, helper, array).invoke();
	return node(array);
	} else {
	Node<P_OUT> node = new CollectorTask.OfRef<>(helper, generator, spliterator).invoke();
	return flattenTree ? flatten(node, generator) : node;
	}
	}

	/**
	* Collect, in parallel, elements output from an int-valued pipeline and
	* describe those elements with a {@link Node.OfInt}.
	*
	* @implSpec
	* If the exact size of the output from the pipeline is known and the source
	* {@link Spliterator} has the {@link Spliterator#SUBSIZED} characteristic,
	* then a flat {@link Node} will be returned whose content is an array,
	* since the size is known the array can be constructed in advance and
	* output elements can be placed into the array concurrently by leaf
	* tasks at the correct offsets. If the exact size is not known, output
	* elements are collected into a conc-node whose shape mirrors that
	* of the computation. This conc-node can then be flattened in
	* parallel to produce a flat {@code Node.OfInt} if desired.
	*
	* @param <P_IN> the type of elements from the source Spliterator
	* @param helper the pipeline helper describing the pipeline
	* @param flattenTree whether a conc node should be flattened into a node
	* describing an array before returning
	* @return a {@link Node.OfInt} describing the output elements
	*/
	public static <P_IN> Node.OfInt collectInt(PipelineHelper<Integer> helper,
	Spliterator<P_IN> spliterator,
	boolean flattenTree) {
	long size = helper.exactOutputSizeIfKnown(spliterator);
	if (size >= 0 && spliterator.hasCharacteristics(Spliterator.SUBSIZED)) {
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	int[] array = new int[(int) size];
	new SizedCollectorTask.OfInt<>(spliterator, helper, array).invoke();
	return node(array);
	}
	else {
	Node.OfInt node = new CollectorTask.OfInt<>(helper, spliterator).invoke();
	return flattenTree ? flattenInt(node) : node;
	}
	}

	/**
	* Collect, in parallel, elements output from a long-valued pipeline and
	* describe those elements with a {@link Node.OfLong}.
	*
	* @implSpec
	* If the exact size of the output from the pipeline is known and the source
	* {@link Spliterator} has the {@link Spliterator#SUBSIZED} characteristic,
	* then a flat {@link Node} will be returned whose content is an array,
	* since the size is known the array can be constructed in advance and
	* output elements can be placed into the array concurrently by leaf
	* tasks at the correct offsets. If the exact size is not known, output
	* elements are collected into a conc-node whose shape mirrors that
	* of the computation. This conc-node can then be flattened in
	* parallel to produce a flat {@code Node.OfLong} if desired.
	*
	* @param <P_IN> the type of elements from the source Spliterator
	* @param helper the pipeline helper describing the pipeline
	* @param flattenTree whether a conc node should be flattened into a node
	* describing an array before returning
	* @return a {@link Node.OfLong} describing the output elements
	*/
	public static <P_IN> Node.OfLong collectLong(PipelineHelper<Long> helper,
	Spliterator<P_IN> spliterator,
	boolean flattenTree) {
	long size = helper.exactOutputSizeIfKnown(spliterator);
	if (size >= 0 && spliterator.hasCharacteristics(Spliterator.SUBSIZED)) {
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	long[] array = new long[(int) size];
	new SizedCollectorTask.OfLong<>(spliterator, helper, array).invoke();
	return node(array);
	}
	else {
	Node.OfLong node = new CollectorTask.OfLong<>(helper, spliterator).invoke();
	return flattenTree ? flattenLong(node) : node;
	}
	}

	/**
	* Collect, in parallel, elements output from n double-valued pipeline and
	* describe those elements with a {@link Node.OfDouble}.
	*
	* @implSpec
	* If the exact size of the output from the pipeline is known and the source
	* {@link Spliterator} has the {@link Spliterator#SUBSIZED} characteristic,
	* then a flat {@link Node} will be returned whose content is an array,
	* since the size is known the array can be constructed in advance and
	* output elements can be placed into the array concurrently by leaf
	* tasks at the correct offsets. If the exact size is not known, output
	* elements are collected into a conc-node whose shape mirrors that
	* of the computation. This conc-node can then be flattened in
	* parallel to produce a flat {@code Node.OfDouble} if desired.
	*
	* @param <P_IN> the type of elements from the source Spliterator
	* @param helper the pipeline helper describing the pipeline
	* @param flattenTree whether a conc node should be flattened into a node
	* describing an array before returning
	* @return a {@link Node.OfDouble} describing the output elements
	*/
	public static <P_IN> Node.OfDouble collectDouble(PipelineHelper<Double> helper,
	Spliterator<P_IN> spliterator,
	boolean flattenTree) {
	long size = helper.exactOutputSizeIfKnown(spliterator);
	if (size >= 0 && spliterator.hasCharacteristics(Spliterator.SUBSIZED)) {
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	double[] array = new double[(int) size];
	new SizedCollectorTask.OfDouble<>(spliterator, helper, array).invoke();
	return node(array);
	}
	else {
	Node.OfDouble node = new CollectorTask.OfDouble<>(helper, spliterator).invoke();
	return flattenTree ? flattenDouble(node) : node;
	}
	}

	// Parallel flattening of nodes

	/**
	* Flatten, in parallel, a {@link Node}. A flattened node is one that has
	* no children. If the node is already flat, it is simply returned.
	*
	* @implSpec
	* If a new node is to be created, the generator is used to create an array
	* whose length is {@link Node#count()}. Then the node tree is traversed
	* and leaf node elements are placed in the array concurrently by leaf tasks
	* at the correct offsets.
	*
	* @param <T> type of elements contained by the node
	* @param node the node to flatten
	* @param generator the array factory used to create array instances
	* @return a flat {@code Node}
	*/
	public static <T> Node<T> flatten(Node<T> node, IntFunction<T[]> generator) {
	if (node.getChildCount() > 0) {
	long size = node.count();
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	T[] array = generator.apply((int) size);
	new ToArrayTask.OfRef<>(node, array, 0).invoke();
	return node(array);
	} else {
	return node;
	}
	}

	/**
	* Flatten, in parallel, a {@link Node.OfInt}. A flattened node is one that
	* has no children. If the node is already flat, it is simply returned.
	*
	* @implSpec
	* If a new node is to be created, a new int[] array is created whose length
	* is {@link Node#count()}. Then the node tree is traversed and leaf node
	* elements are placed in the array concurrently by leaf tasks at the
	* correct offsets.
	*
	* @param node the node to flatten
	* @return a flat {@code Node.OfInt}
	*/
	public static Node.OfInt flattenInt(Node.OfInt node) {
	if (node.getChildCount() > 0) {
	long size = node.count();
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	int[] array = new int[(int) size];
	new ToArrayTask.OfInt(node, array, 0).invoke();
	return node(array);
	} else {
	return node;
	}
	}

	/**
	* Flatten, in parallel, a {@link Node.OfLong}. A flattened node is one that
	* has no children. If the node is already flat, it is simply returned.
	*
	* @implSpec
	* If a new node is to be created, a new long[] array is created whose length
	* is {@link Node#count()}. Then the node tree is traversed and leaf node
	* elements are placed in the array concurrently by leaf tasks at the
	* correct offsets.
	*
	* @param node the node to flatten
	* @return a flat {@code Node.OfLong}
	*/
	public static Node.OfLong flattenLong(Node.OfLong node) {
	if (node.getChildCount() > 0) {
	long size = node.count();
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	long[] array = new long[(int) size];
	new ToArrayTask.OfLong(node, array, 0).invoke();
	return node(array);
	} else {
	return node;
	}
	}

	/**
	* Flatten, in parallel, a {@link Node.OfDouble}. A flattened node is one that
	* has no children. If the node is already flat, it is simply returned.
	*
	* @implSpec
	* If a new node is to be created, a new double[] array is created whose length
	* is {@link Node#count()}. Then the node tree is traversed and leaf node
	* elements are placed in the array concurrently by leaf tasks at the
	* correct offsets.
	*
	* @param node the node to flatten
	* @return a flat {@code Node.OfDouble}
	*/
	public static Node.OfDouble flattenDouble(Node.OfDouble node) {
	if (node.getChildCount() > 0) {
	long size = node.count();
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	double[] array = new double[(int) size];
	new ToArrayTask.OfDouble(node, array, 0).invoke();
	return node(array);
	} else {
	return node;
	}
	}

	// Implementations

	private abstract static class EmptyNode<T, T_ARR, T_CONS> implements Node<T> {
	EmptyNode() { }

	@Override
	public T[] asArray(IntFunction<T[]> generator) {
	return generator.apply(0);
	}

	public void copyInto(T_ARR array, int offset) { }

	@Override
	public long count() {
	return 0;
	}

	public void forEach(T_CONS consumer) { }

	private static class OfRef<T> extends EmptyNode<T, T[], Consumer<? super T>> {
	private OfRef() {
	super();
	}

	@Override
	public Spliterator<T> spliterator() {
	return Spliterators.emptySpliterator();
	}
	}

	private static final class OfInt
	extends EmptyNode<Integer, int[], IntConsumer>
	implements Node.OfInt {

	OfInt() { } // Avoid creation of special accessor

	@Override
	public Spliterator.OfInt spliterator() {
	return Spliterators.emptyIntSpliterator();
	}

	@Override
	public int[] asPrimitiveArray() {
	return EMPTY_INT_ARRAY;
	}
	}

	private static final class OfLong
	extends EmptyNode<Long, long[], LongConsumer>
	implements Node.OfLong {

	OfLong() { } // Avoid creation of special accessor

	@Override
	public Spliterator.OfLong spliterator() {
	return Spliterators.emptyLongSpliterator();
	}

	@Override
	public long[] asPrimitiveArray() {
	return EMPTY_LONG_ARRAY;
	}
	}

	private static final class OfDouble
	extends EmptyNode<Double, double[], DoubleConsumer>
	implements Node.OfDouble {

	OfDouble() { } // Avoid creation of special accessor

	@Override
	public Spliterator.OfDouble spliterator() {
	return Spliterators.emptyDoubleSpliterator();
	}

	@Override
	public double[] asPrimitiveArray() {
	return EMPTY_DOUBLE_ARRAY;
	}
	}
	}

	/** Node class for a reference array */
	private static class ArrayNode<T> implements Node<T> {
	final T[] array;
	int curSize;

	@SuppressWarnings("unchecked")
	ArrayNode(long size, IntFunction<T[]> generator) {
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	this.array = generator.apply((int) size);
	this.curSize = 0;
	}

	ArrayNode(T[] array) {
	this.array = array;
	this.curSize = array.length;
	}

	// Node

	@Override
	public Spliterator<T> spliterator() {
	return Arrays.spliterator(array, 0, curSize);
	}

	@Override
	public void copyInto(T[] dest, int destOffset) {
	System.arraycopy(array, 0, dest, destOffset, curSize);
	}

	@Override
	public T[] asArray(IntFunction<T[]> generator) {
	if (array.length == curSize) {
	return array;
	} else {
	throw new IllegalStateException();
	}
	}

	@Override
	public long count() {
	return curSize;
	}

	@Override
	public void forEach(Consumer<? super T> consumer) {
	for (int i = 0; i < curSize; i++) {
	consumer.accept(array[i]);
	}
	}

	//

	@Override
	public String toString() {
	return String.format("ArrayNode[%d][%s]",
	array.length - curSize, Arrays.toString(array));
	}
	}

	/** Node class for a Collection */
	private static final class CollectionNode<T> implements Node<T> {
	private final Collection<T> c;

	CollectionNode(Collection<T> c) {
	this.c = c;
	}

	// Node

	@Override
	public Spliterator<T> spliterator() {
	return c.stream().spliterator();
	}

	@Override
	public void copyInto(T[] array, int offset) {
	for (T t : c)
	array[offset++] = t;
	}

	@Override
	@SuppressWarnings("unchecked")
	public T[] asArray(IntFunction<T[]> generator) {
	return c.toArray(generator.apply(c.size()));
	}

	@Override
	public long count() {
	return c.size();
	}

	@Override
	public void forEach(Consumer<? super T> consumer) {
	c.forEach(consumer);
	}

	//

	@Override
	public String toString() {
	return String.format("CollectionNode[%d][%s]", c.size(), c);
	}
	}

	/**
	* Node class for an internal node with two or more children
	*/
	private abstract static class AbstractConcNode<T, T_NODE extends Node<T>> implements Node<T> {
	protected final T_NODE left;
	protected final T_NODE right;
	private final long size;

	AbstractConcNode(T_NODE left, T_NODE right) {
	this.left = left;
	this.right = right;
	// The Node count will be required when the Node spliterator is
	// obtained and it is cheaper to aggressively calculate bottom up
	// as the tree is built rather than later on from the top down
	// traversing the tree
	this.size = left.count() + right.count();
	}

	@Override
	public int getChildCount() {
	return 2;
	}

	@Override
	public T_NODE getChild(int i) {
	if (i == 0) return left;
	if (i == 1) return right;
	throw new IndexOutOfBoundsException();
	}

	@Override
	public long count() {
	return size;
	}
	}

	static final class ConcNode<T>
	extends AbstractConcNode<T, Node<T>>
	implements Node<T> {

	ConcNode(Node<T> left, Node<T> right) {
	super(left, right);
	}

	@Override
	public Spliterator<T> spliterator() {
	return new Nodes.InternalNodeSpliterator.OfRef<>(this);
	}

	@Override
	public void copyInto(T[] array, int offset) {
	Objects.requireNonNull(array);
	left.copyInto(array, offset);
	// Cast to int is safe since it is the callers responsibility to
	// ensure that there is sufficient room in the array
	right.copyInto(array, offset + (int) left.count());
	}

	@Override
	public T[] asArray(IntFunction<T[]> generator) {
	long size = count();
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	T[] array = generator.apply((int) size);
	copyInto(array, 0);
	return array;
	}

	@Override
	public void forEach(Consumer<? super T> consumer) {
	left.forEach(consumer);
	right.forEach(consumer);
	}

	@Override
	public Node<T> truncate(long from, long to, IntFunction<T[]> generator) {
	if (from == 0 && to == count())
	return this;
	long leftCount = left.count();
	if (from >= leftCount)
	return right.truncate(from - leftCount, to - leftCount, generator);
	else if (to <= leftCount)
	return left.truncate(from, to, generator);
	else {
	return Nodes.conc(getShape(), left.truncate(from, leftCount, generator),
	right.truncate(0, to - leftCount, generator));
	}
	}

	@Override
	public String toString() {
	if (count() < 32) {
	return String.format("ConcNode[%s.%s]", left, right);
	} else {
	return String.format("ConcNode[size=%d]", count());
	}
	}

	private abstract static class OfPrimitive<E, T_CONS, T_ARR,
	T_SPLITR extends Spliterator.OfPrimitive<E, T_CONS, T_SPLITR>,
	T_NODE extends Node.OfPrimitive<E, T_CONS, T_ARR, T_SPLITR, T_NODE>>
	extends AbstractConcNode<E, T_NODE>
	implements Node.OfPrimitive<E, T_CONS, T_ARR, T_SPLITR, T_NODE> {

	OfPrimitive(T_NODE left, T_NODE right) {
	super(left, right);
	}

	@Override
	public void forEach(T_CONS consumer) {
	left.forEach(consumer);
	right.forEach(consumer);
	}

	@Override
	public void copyInto(T_ARR array, int offset) {
	left.copyInto(array, offset);
	// Cast to int is safe since it is the callers responsibility to
	// ensure that there is sufficient room in the array
	right.copyInto(array, offset + (int) left.count());
	}

	@Override
	public T_ARR asPrimitiveArray() {
	long size = count();
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	T_ARR array = newArray((int) size);
	copyInto(array, 0);
	return array;
	}

	@Override
	public String toString() {
	if (count() < 32)
	return String.format("%s[%s.%s]", this.getClass().getName(), left, right);
	else
	return String.format("%s[size=%d]", this.getClass().getName(), count());
	}
	}

	static final class OfInt
	extends ConcNode.OfPrimitive<Integer, IntConsumer, int[], Spliterator.OfInt, Node.OfInt>
	implements Node.OfInt {

	OfInt(Node.OfInt left, Node.OfInt right) {
	super(left, right);
	}

	@Override
	public Spliterator.OfInt spliterator() {
	return new InternalNodeSpliterator.OfInt(this);
	}
	}

	static final class OfLong
	extends ConcNode.OfPrimitive<Long, LongConsumer, long[], Spliterator.OfLong, Node.OfLong>
	implements Node.OfLong {

	OfLong(Node.OfLong left, Node.OfLong right) {
	super(left, right);
	}

	@Override
	public Spliterator.OfLong spliterator() {
	return new InternalNodeSpliterator.OfLong(this);
	}
	}

	static final class OfDouble
	extends ConcNode.OfPrimitive<Double, DoubleConsumer, double[], Spliterator.OfDouble, Node.OfDouble>
	implements Node.OfDouble {

	OfDouble(Node.OfDouble left, Node.OfDouble right) {
	super(left, right);
	}

	@Override
	public Spliterator.OfDouble spliterator() {
	return new InternalNodeSpliterator.OfDouble(this);
	}
	}
	}

	/** Abstract class for spliterator for all internal node classes */
	private abstract static class InternalNodeSpliterator<T,
	S extends Spliterator<T>,
	N extends Node<T>>
	implements Spliterator<T> {
	// Node we are pointing to
	// null if full traversal has occurred
	N curNode;

	// next child of curNode to consume
	int curChildIndex;

	// The spliterator of the curNode if that node is last and has no children.
	// This spliterator will be delegated to for splitting and traversing.
	// null if curNode has children
	S lastNodeSpliterator;

	// spliterator used while traversing with tryAdvance
	// null if no partial traversal has occurred
	S tryAdvanceSpliterator;

	// node stack used when traversing to search and find leaf nodes
	// null if no partial traversal has occurred
	Deque<N> tryAdvanceStack;

	InternalNodeSpliterator(N curNode) {
	this.curNode = curNode;
	}

	/**
	* Initiate a stack containing, in left-to-right order, the child nodes
	* covered by this spliterator
	*/
	@SuppressWarnings("unchecked")
	protected final Deque<N> initStack() {
	// Bias size to the case where leaf nodes are close to this node
	// 8 is the minimum initial capacity for the ArrayDeque implementation
	Deque<N> stack = new ArrayDeque<>(8);
	for (int i = curNode.getChildCount() - 1; i >= curChildIndex; i--)
	stack.addFirst((N) curNode.getChild(i));
	return stack;
	}

	/**
	* Depth first search, in left-to-right order, of the node tree, using
	* an explicit stack, to find the next non-empty leaf node.
	*/
	@SuppressWarnings("unchecked")
	protected final N findNextLeafNode(Deque<N> stack) {
	N n = null;
	while ((n = stack.pollFirst()) != null) {
	if (n.getChildCount() == 0) {
	if (n.count() > 0)
	return n;
	} else {
	for (int i = n.getChildCount() - 1; i >= 0; i--)
	stack.addFirst((N) n.getChild(i));
	}
	}

	return null;
	}

	@SuppressWarnings("unchecked")
	protected final boolean initTryAdvance() {
	if (curNode == null)
	return false;

	if (tryAdvanceSpliterator == null) {
	if (lastNodeSpliterator == null) {
	// Initiate the node stack
	tryAdvanceStack = initStack();
	N leaf = findNextLeafNode(tryAdvanceStack);
	if (leaf != null)
	tryAdvanceSpliterator = (S) leaf.spliterator();
	else {
	// A non-empty leaf node was not found
	// No elements to traverse
	curNode = null;
	return false;
	}
	}
	else
	tryAdvanceSpliterator = lastNodeSpliterator;
	}
	return true;
	}

	@Override
	@SuppressWarnings("unchecked")
	public final S trySplit() {
	if (curNode == null \|\| tryAdvanceSpliterator != null)
	return null; // Cannot split if fully or partially traversed
	else if (lastNodeSpliterator != null)
	return (S) lastNodeSpliterator.trySplit();
	else if (curChildIndex < curNode.getChildCount() - 1)
	return (S) curNode.getChild(curChildIndex++).spliterator();
	else {
	curNode = (N) curNode.getChild(curChildIndex);
	if (curNode.getChildCount() == 0) {
	lastNodeSpliterator = (S) curNode.spliterator();
	return (S) lastNodeSpliterator.trySplit();
	}
	else {
	curChildIndex = 0;
	return (S) curNode.getChild(curChildIndex++).spliterator();
	}
	}
	}

	@Override
	public final long estimateSize() {
	if (curNode == null)
	return 0;

	// Will not reflect the effects of partial traversal.
	// This is compliant with the specification
	if (lastNodeSpliterator != null)
	return lastNodeSpliterator.estimateSize();
	else {
	long size = 0;
	for (int i = curChildIndex; i < curNode.getChildCount(); i++)
	size += curNode.getChild(i).count();
	return size;
	}
	}

	@Override
	public final int characteristics() {
	return Spliterator.SIZED;
	}

	private static final class OfRef<T>
	extends InternalNodeSpliterator<T, Spliterator<T>, Node<T>> {

	OfRef(Node<T> curNode) {
	super(curNode);
	}

	@Override
	public boolean tryAdvance(Consumer<? super T> consumer) {
	if (!initTryAdvance())
	return false;

	boolean hasNext = tryAdvanceSpliterator.tryAdvance(consumer);
	if (!hasNext) {
	if (lastNodeSpliterator == null) {
	// Advance to the spliterator of the next non-empty leaf node
	Node<T> leaf = findNextLeafNode(tryAdvanceStack);
	if (leaf != null) {
	tryAdvanceSpliterator = leaf.spliterator();
	// Since the node is not-empty the spliterator can be advanced
	return tryAdvanceSpliterator.tryAdvance(consumer);
	}
	}
	// No more elements to traverse
	curNode = null;
	}
	return hasNext;
	}

	@Override
	public void forEachRemaining(Consumer<? super T> consumer) {
	if (curNode == null)
	return;

	if (tryAdvanceSpliterator == null) {
	if (lastNodeSpliterator == null) {
	Deque<Node<T>> stack = initStack();
	Node<T> leaf;
	while ((leaf = findNextLeafNode(stack)) != null) {
	leaf.forEach(consumer);
	}
	curNode = null;
	}
	else
	lastNodeSpliterator.forEachRemaining(consumer);
	}
	else
	while(tryAdvance(consumer)) { }
	}
	}

	private abstract static class OfPrimitive<T, T_CONS, T_ARR,
	T_SPLITR extends Spliterator.OfPrimitive<T, T_CONS, T_SPLITR>,
	N extends Node.OfPrimitive<T, T_CONS, T_ARR, T_SPLITR, N>>
	extends InternalNodeSpliterator<T, T_SPLITR, N>
	implements Spliterator.OfPrimitive<T, T_CONS, T_SPLITR> {

	OfPrimitive(N cur) {
	super(cur);
	}

	@Override
	public boolean tryAdvance(T_CONS consumer) {
	if (!initTryAdvance())
	return false;

	boolean hasNext = tryAdvanceSpliterator.tryAdvance(consumer);
	if (!hasNext) {
	if (lastNodeSpliterator == null) {
	// Advance to the spliterator of the next non-empty leaf node
	N leaf = findNextLeafNode(tryAdvanceStack);
	if (leaf != null) {
	tryAdvanceSpliterator = leaf.spliterator();
	// Since the node is not-empty the spliterator can be advanced
	return tryAdvanceSpliterator.tryAdvance(consumer);
	}
	}
	// No more elements to traverse
	curNode = null;
	}
	return hasNext;
	}

	@Override
	public void forEachRemaining(T_CONS consumer) {
	if (curNode == null)
	return;

	if (tryAdvanceSpliterator == null) {
	if (lastNodeSpliterator == null) {
	Deque<N> stack = initStack();
	N leaf;
	while ((leaf = findNextLeafNode(stack)) != null) {
	leaf.forEach(consumer);
	}
	curNode = null;
	}
	else
	lastNodeSpliterator.forEachRemaining(consumer);
	}
	else
	while(tryAdvance(consumer)) { }
	}
	}

	private static final class OfInt
	extends OfPrimitive<Integer, IntConsumer, int[], Spliterator.OfInt, Node.OfInt>
	implements Spliterator.OfInt {

	OfInt(Node.OfInt cur) {
	super(cur);
	}
	}

	private static final class OfLong
	extends OfPrimitive<Long, LongConsumer, long[], Spliterator.OfLong, Node.OfLong>
	implements Spliterator.OfLong {

	OfLong(Node.OfLong cur) {
	super(cur);
	}
	}

	private static final class OfDouble
	extends OfPrimitive<Double, DoubleConsumer, double[], Spliterator.OfDouble, Node.OfDouble>
	implements Spliterator.OfDouble {

	OfDouble(Node.OfDouble cur) {
	super(cur);
	}
	}
	}

	/**
	* Fixed-sized builder class for reference nodes
	*/
	private static final class FixedNodeBuilder<T>
	extends ArrayNode<T>
	implements Node.Builder<T> {

	FixedNodeBuilder(long size, IntFunction<T[]> generator) {
	super(size, generator);
	assert size < MAX_ARRAY_SIZE;
	}

	@Override
	public Node<T> build() {
	if (curSize < array.length)
	throw new IllegalStateException(String.format("Current size %d is less than fixed size %d",
	curSize, array.length));
	return this;
	}

	@Override
	public void begin(long size) {
	if (size != array.length)
	throw new IllegalStateException(String.format("Begin size %d is not equal to fixed size %d",
	size, array.length));
	curSize = 0;
	}

	@Override
	public void accept(T t) {
	if (curSize < array.length) {
	array[curSize++] = t;
	} else {
	throw new IllegalStateException(String.format("Accept exceeded fixed size of %d",
	array.length));
	}
	}

	@Override
	public void end() {
	if (curSize < array.length)
	throw new IllegalStateException(String.format("End size %d is less than fixed size %d",
	curSize, array.length));
	}

	@Override
	public String toString() {
	return String.format("FixedNodeBuilder[%d][%s]",
	array.length - curSize, Arrays.toString(array));
	}
	}

	/**
	* Variable-sized builder class for reference nodes
	*/
	private static final class SpinedNodeBuilder<T>
	extends SpinedBuffer<T>
	implements Node<T>, Node.Builder<T> {
	private boolean building = false;

	SpinedNodeBuilder() {} // Avoid creation of special accessor

	@Override
	public Spliterator<T> spliterator() {
	assert !building : "during building";
	return super.spliterator();
	}

	@Override
	public void forEach(Consumer<? super T> consumer) {
	assert !building : "during building";
	super.forEach(consumer);
	}

	//
	@Override
	public void begin(long size) {
	assert !building : "was already building";
	building = true;
	clear();
	ensureCapacity(size);
	}

	@Override
	public void accept(T t) {
	assert building : "not building";
	super.accept(t);
	}

	@Override
	public void end() {
	assert building : "was not building";
	building = false;
	// @@@ check begin(size) and size
	}

	@Override
	public void copyInto(T[] array, int offset) {
	assert !building : "during building";
	super.copyInto(array, offset);
	}

	@Override
	public T[] asArray(IntFunction<T[]> arrayFactory) {
	assert !building : "during building";
	return super.asArray(arrayFactory);
	}

	@Override
	public Node<T> build() {
	assert !building : "during building";
	return this;
	}
	}

	//

	private static final int[] EMPTY_INT_ARRAY = new int[0];
	private static final long[] EMPTY_LONG_ARRAY = new long[0];
	private static final double[] EMPTY_DOUBLE_ARRAY = new double[0];

	private static class IntArrayNode implements Node.OfInt {
	final int[] array;
	int curSize;

	IntArrayNode(long size) {
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	this.array = new int[(int) size];
	this.curSize = 0;
	}

	IntArrayNode(int[] array) {
	this.array = array;
	this.curSize = array.length;
	}

	// Node

	@Override
	public Spliterator.OfInt spliterator() {
	return Arrays.spliterator(array, 0, curSize);
	}

	@Override
	public int[] asPrimitiveArray() {
	if (array.length == curSize) {
	return array;
	} else {
	return Arrays.copyOf(array, curSize);
	}
	}

	@Override
	public void copyInto(int[] dest, int destOffset) {
	System.arraycopy(array, 0, dest, destOffset, curSize);
	}

	@Override
	public long count() {
	return curSize;
	}

	@Override
	public void forEach(IntConsumer consumer) {
	for (int i = 0; i < curSize; i++) {
	consumer.accept(array[i]);
	}
	}

	@Override
	public String toString() {
	return String.format("IntArrayNode[%d][%s]",
	array.length - curSize, Arrays.toString(array));
	}
	}

	private static class LongArrayNode implements Node.OfLong {
	final long[] array;
	int curSize;

	LongArrayNode(long size) {
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	this.array = new long[(int) size];
	this.curSize = 0;
	}

	LongArrayNode(long[] array) {
	this.array = array;
	this.curSize = array.length;
	}

	@Override
	public Spliterator.OfLong spliterator() {
	return Arrays.spliterator(array, 0, curSize);
	}

	@Override
	public long[] asPrimitiveArray() {
	if (array.length == curSize) {
	return array;
	} else {
	return Arrays.copyOf(array, curSize);
	}
	}

	@Override
	public void copyInto(long[] dest, int destOffset) {
	System.arraycopy(array, 0, dest, destOffset, curSize);
	}

	@Override
	public long count() {
	return curSize;
	}

	@Override
	public void forEach(LongConsumer consumer) {
	for (int i = 0; i < curSize; i++) {
	consumer.accept(array[i]);
	}
	}

	@Override
	public String toString() {
	return String.format("LongArrayNode[%d][%s]",
	array.length - curSize, Arrays.toString(array));
	}
	}

	private static class DoubleArrayNode implements Node.OfDouble {
	final double[] array;
	int curSize;

	DoubleArrayNode(long size) {
	if (size >= MAX_ARRAY_SIZE)
	throw new IllegalArgumentException(BAD_SIZE);
	this.array = new double[(int) size];
	this.curSize = 0;
	}

	DoubleArrayNode(double[] array) {
	this.array = array;
	this.curSize = array.length;
	}

	@Override
	public Spliterator.OfDouble spliterator() {
	return Arrays.spliterator(array, 0, curSize);
	}

	@Override
	public double[] asPrimitiveArray() {
	if (array.length == curSize) {
	return array;
	} else {
	return Arrays.copyOf(array, curSize);
	}
	}

	@Override
	public void copyInto(double[] dest, int destOffset) {
	System.arraycopy(array, 0, dest, destOffset, curSize);
	}

	@Override
	public long count() {
	return curSize;
	}

	@Override
	public void forEach(DoubleConsumer consumer) {
	for (int i = 0; i < curSize; i++) {
	consumer.accept(array[i]);
	}
	}

	@Override
	public String toString() {
	return String.format("DoubleArrayNode[%d][%s]",
	array.length - curSize, Arrays.toString(array));
	}
	}

	private static final class IntFixedNodeBuilder
	extends IntArrayNode
	implements Node.Builder.OfInt {

	IntFixedNodeBuilder(long size) {
	super(size);
	assert size < MAX_ARRAY_SIZE;
	}

	@Override
	public Node.OfInt build() {
	if (curSize < array.length) {
	throw new IllegalStateException(String.format("Current size %d is less than fixed size %d",
	curSize, array.length));
	}

	return this;
	}

	@Override
	public void begin(long size) {
	if (size != array.length) {
	throw new IllegalStateException(String.format("Begin size %d is not equal to fixed size %d",
	size, array.length));
	}

	curSize = 0;
	}

	@Override
	public void accept(int i) {
	if (curSize < array.length) {
	array[curSize++] = i;
	} else {
	throw new IllegalStateException(String.format("Accept exceeded fixed size of %d",
	array.length));
	}
	}

	@Override
	public void end() {
	if (curSize < array.length) {
	throw new IllegalStateException(String.format("End size %d is less than fixed size %d",
	curSize, array.length));
	}
	}

	@Override
	public String toString() {
	return String.format("IntFixedNodeBuilder[%d][%s]",
	array.length - curSize, Arrays.toString(array));
	}
	}

	private static final class LongFixedNodeBuilder
	extends LongArrayNode
	implements Node.Builder.OfLong {

	LongFixedNodeBuilder(long size) {
	super(size);
	assert size < MAX_ARRAY_SIZE;
	}

	@Override
	public Node.OfLong build() {
	if (curSize < array.length) {
	throw new IllegalStateException(String.format("Current size %d is less than fixed size %d",
	curSize, array.length));
	}

	return this;
	}

	@Override
	public void begin(long size) {
	if (size != array.length) {
	throw new IllegalStateException(String.format("Begin size %d is not equal to fixed size %d",
	size, array.length));
	}

	curSize = 0;
	}

	@Override
	public void accept(long i) {
	if (curSize < array.length) {
	array[curSize++] = i;
	} else {
	throw new IllegalStateException(String.format("Accept exceeded fixed size of %d",
	array.length));
	}
	}

	@Override
	public void end() {
	if (curSize < array.length) {
	throw new IllegalStateException(String.format("End size %d is less than fixed size %d",
	curSize, array.length));
	}
	}

	@Override
	public String toString() {
	return String.format("LongFixedNodeBuilder[%d][%s]",
	array.length - curSize, Arrays.toString(array));
	}
	}

	private static final class DoubleFixedNodeBuilder
	extends DoubleArrayNode
	implements Node.Builder.OfDouble {

	DoubleFixedNodeBuilder(long size) {
	super(size);
	assert size < MAX_ARRAY_SIZE;
	}

	@Override
	public Node.OfDouble build() {
	if (curSize < array.length) {
	throw new IllegalStateException(String.format("Current size %d is less than fixed size %d",
	curSize, array.length));
	}

	return this;
	}

	@Override
	public void begin(long size) {
	if (size != array.length) {
	throw new IllegalStateException(String.format("Begin size %d is not equal to fixed size %d",
	size, array.length));
	}

	curSize = 0;
	}

	@Override
	public void accept(double i) {
	if (curSize < array.length) {
	array[curSize++] = i;
	} else {
	throw new IllegalStateException(String.format("Accept exceeded fixed size of %d",
	array.length));
	}
	}

	@Override
	public void end() {
	if (curSize < array.length) {
	throw new IllegalStateException(String.format("End size %d is less than fixed size %d",
	curSize, array.length));
	}
	}

	@Override
	public String toString() {
	return String.format("DoubleFixedNodeBuilder[%d][%s]",
	array.length - curSize, Arrays.toString(array));
	}
	}

	private static final class IntSpinedNodeBuilder
	extends SpinedBuffer.OfInt
	implements Node.OfInt, Node.Builder.OfInt {
	private boolean building = false;

	IntSpinedNodeBuilder() {} // Avoid creation of special accessor

	@Override
	public Spliterator.OfInt spliterator() {
	assert !building : "during building";
	return super.spliterator();
	}

	@Override
	public void forEach(IntConsumer consumer) {
	assert !building : "during building";
	super.forEach(consumer);
	}

	//
	@Override
	public void begin(long size) {
	assert !building : "was already building";
	building = true;
	clear();
	ensureCapacity(size);
	}

	@Override
	public void accept(int i) {
	assert building : "not building";
	super.accept(i);
	}

	@Override
	public void end() {
	assert building : "was not building";
	building = false;
	// @@@ check begin(size) and size
	}

	@Override
	public void copyInto(int[] array, int offset) throws IndexOutOfBoundsException {
	assert !building : "during building";
	super.copyInto(array, offset);
	}

	@Override
	public int[] asPrimitiveArray() {
	assert !building : "during building";
	return super.asPrimitiveArray();
	}

	@Override
	public Node.OfInt build() {
	assert !building : "during building";
	return this;
	}
	}

	private static final class LongSpinedNodeBuilder
	extends SpinedBuffer.OfLong
	implements Node.OfLong, Node.Builder.OfLong {
	private boolean building = false;

	LongSpinedNodeBuilder() {} // Avoid creation of special accessor

	@Override
	public Spliterator.OfLong spliterator() {
	assert !building : "during building";
	return super.spliterator();
	}

	@Override
	public void forEach(LongConsumer consumer) {
	assert !building : "during building";
	super.forEach(consumer);
	}

	//
	@Override
	public void begin(long size) {
	assert !building : "was already building";
	building = true;
	clear();
	ensureCapacity(size);
	}

	@Override
	public void accept(long i) {
	assert building : "not building";
	super.accept(i);
	}

	@Override
	public void end() {
	assert building : "was not building";
	building = false;
	// @@@ check begin(size) and size
	}

	@Override
	public void copyInto(long[] array, int offset) {
	assert !building : "during building";
	super.copyInto(array, offset);
	}

	@Override
	public long[] asPrimitiveArray() {
	assert !building : "during building";
	return super.asPrimitiveArray();
	}

	@Override
	public Node.OfLong build() {
	assert !building : "during building";
	return this;
	}
	}

	private static final class DoubleSpinedNodeBuilder
	extends SpinedBuffer.OfDouble
	implements Node.OfDouble, Node.Builder.OfDouble {
	private boolean building = false;

	DoubleSpinedNodeBuilder() {} // Avoid creation of special accessor

	@Override
	public Spliterator.OfDouble spliterator() {
	assert !building : "during building";
	return super.spliterator();
	}

	@Override
	public void forEach(DoubleConsumer consumer) {
	assert !building : "during building";
	super.forEach(consumer);
	}

	//
	@Override
	public void begin(long size) {
	assert !building : "was already building";
	building = true;
	clear();
	ensureCapacity(size);
	}

	@Override
	public void accept(double i) {
	assert building : "not building";
	super.accept(i);
	}

	@Override
	public void end() {
	assert building : "was not building";
	building = false;
	// @@@ check begin(size) and size
	}

	@Override
	public void copyInto(double[] array, int offset) {
	assert !building : "during building";
	super.copyInto(array, offset);
	}

	@Override
	public double[] asPrimitiveArray() {
	assert !building : "during building";
	return super.asPrimitiveArray();
	}

	@Override
	public Node.OfDouble build() {
	assert !building : "during building";
	return this;
	}
	}

	/*
	* This and subclasses are not intended to be serializable
	*/
	@SuppressWarnings("serial")
	private abstract static class SizedCollectorTask<P_IN, P_OUT, T_SINK extends Sink<P_OUT>,
	K extends SizedCollectorTask<P_IN, P_OUT, T_SINK, K>>
	extends CountedCompleter<Void>
	implements Sink<P_OUT> {
	protected final Spliterator<P_IN> spliterator;
	protected final PipelineHelper<P_OUT> helper;
	protected final long targetSize;
	protected long offset;
	protected long length;
	// For Sink implementation
	protected int index, fence;

	SizedCollectorTask(Spliterator<P_IN> spliterator,
	PipelineHelper<P_OUT> helper,
	int arrayLength) {
	assert spliterator.hasCharacteristics(Spliterator.SUBSIZED);
	this.spliterator = spliterator;
	this.helper = helper;
	this.targetSize = AbstractTask.suggestTargetSize(spliterator.estimateSize());
	this.offset = 0;
	this.length = arrayLength;
	}

	SizedCollectorTask(K parent, Spliterator<P_IN> spliterator,
	long offset, long length, int arrayLength) {
	super(parent);
	assert spliterator.hasCharacteristics(Spliterator.SUBSIZED);
	this.spliterator = spliterator;
	this.helper = parent.helper;
	this.targetSize = parent.targetSize;
	this.offset = offset;
	this.length = length;

	if (offset < 0 \|\| length < 0 \|\| (offset + length - 1 >= arrayLength)) {
	throw new IllegalArgumentException(
	String.format("offset and length interval [%d, %d + %d) is not within array size interval [0, %d)",
	offset, offset, length, arrayLength));
	}
	}

	@Override
	public void compute() {
	SizedCollectorTask<P_IN, P_OUT, T_SINK, K> task = this;
	Spliterator<P_IN> rightSplit = spliterator, leftSplit;
	while (rightSplit.estimateSize() > task.targetSize &&
	(leftSplit = rightSplit.trySplit()) != null) {
	task.setPendingCount(1);
	long leftSplitSize = leftSplit.estimateSize();
	task.makeChild(leftSplit, task.offset, leftSplitSize).fork();
	task = task.makeChild(rightSplit, task.offset + leftSplitSize,
	task.length - leftSplitSize);
	}

	assert task.offset + task.length < MAX_ARRAY_SIZE;
	@SuppressWarnings("unchecked")
	T_SINK sink = (T_SINK) task;
	task.helper.wrapAndCopyInto(sink, rightSplit);
	task.propagateCompletion();
	}

	abstract K makeChild(Spliterator<P_IN> spliterator, long offset, long size);

	@Override
	public void begin(long size) {
	if (size > length)
	throw new IllegalStateException("size passed to Sink.begin exceeds array length");
	// Casts to int are safe since absolute size is verified to be within
	// bounds when the root concrete SizedCollectorTask is constructed
	// with the shared array
	index = (int) offset;
	fence = index + (int) length;
	}

	@SuppressWarnings("serial")
	static final class OfRef<P_IN, P_OUT>
	extends SizedCollectorTask<P_IN, P_OUT, Sink<P_OUT>, OfRef<P_IN, P_OUT>>
	implements Sink<P_OUT> {
	private final P_OUT[] array;

	OfRef(Spliterator<P_IN> spliterator, PipelineHelper<P_OUT> helper, P_OUT[] array) {
	super(spliterator, helper, array.length);
	this.array = array;
	}

	OfRef(OfRef<P_IN, P_OUT> parent, Spliterator<P_IN> spliterator,
	long offset, long length) {
	super(parent, spliterator, offset, length, parent.array.length);
	this.array = parent.array;
	}

	@Override
	OfRef<P_IN, P_OUT> makeChild(Spliterator<P_IN> spliterator,
	long offset, long size) {
	return new OfRef<>(this, spliterator, offset, size);
	}

	@Override
	public void accept(P_OUT value) {
	if (index >= fence) {
	throw new IndexOutOfBoundsException(Integer.toString(index));
	}
	array[index++] = value;
	}
	}

	@SuppressWarnings("serial")
	static final class OfInt<P_IN>
	extends SizedCollectorTask<P_IN, Integer, Sink.OfInt, OfInt<P_IN>>
	implements Sink.OfInt {
	private final int[] array;

	OfInt(Spliterator<P_IN> spliterator, PipelineHelper<Integer> helper, int[] array) {
	super(spliterator, helper, array.length);
	this.array = array;
	}

	OfInt(SizedCollectorTask.OfInt<P_IN> parent, Spliterator<P_IN> spliterator,
	long offset, long length) {
	super(parent, spliterator, offset, length, parent.array.length);
	this.array = parent.array;
	}

	@Override
	SizedCollectorTask.OfInt<P_IN> makeChild(Spliterator<P_IN> spliterator,
	long offset, long size) {
	return new SizedCollectorTask.OfInt<>(this, spliterator, offset, size);
	}

	@Override
	public void accept(int value) {
	if (index >= fence) {
	throw new IndexOutOfBoundsException(Integer.toString(index));
	}
	array[index++] = value;
	}
	}

	@SuppressWarnings("serial")
	static final class OfLong<P_IN>
	extends SizedCollectorTask<P_IN, Long, Sink.OfLong, OfLong<P_IN>>
	implements Sink.OfLong {
	private final long[] array;

	OfLong(Spliterator<P_IN> spliterator, PipelineHelper<Long> helper, long[] array) {
	super(spliterator, helper, array.length);
	this.array = array;
	}

	OfLong(SizedCollectorTask.OfLong<P_IN> parent, Spliterator<P_IN> spliterator,
	long offset, long length) {
	super(parent, spliterator, offset, length, parent.array.length);
	this.array = parent.array;
	}

	@Override
	SizedCollectorTask.OfLong<P_IN> makeChild(Spliterator<P_IN> spliterator,
	long offset, long size) {
	return new SizedCollectorTask.OfLong<>(this, spliterator, offset, size);
	}

	@Override
	public void accept(long value) {
	if (index >= fence) {
	throw new IndexOutOfBoundsException(Integer.toString(index));
	}
	array[index++] = value;
	}
	}

	@SuppressWarnings("serial")
	static final class OfDouble<P_IN>
	extends SizedCollectorTask<P_IN, Double, Sink.OfDouble, OfDouble<P_IN>>
	implements Sink.OfDouble {
	private final double[] array;

	OfDouble(Spliterator<P_IN> spliterator, PipelineHelper<Double> helper, double[] array) {
	super(spliterator, helper, array.length);
	this.array = array;
	}

	OfDouble(SizedCollectorTask.OfDouble<P_IN> parent, Spliterator<P_IN> spliterator,
	long offset, long length) {
	super(parent, spliterator, offset, length, parent.array.length);
	this.array = parent.array;
	}

	@Override
	SizedCollectorTask.OfDouble<P_IN> makeChild(Spliterator<P_IN> spliterator,
	long offset, long size) {
	return new SizedCollectorTask.OfDouble<>(this, spliterator, offset, size);
	}

	@Override
	public void accept(double value) {
	if (index >= fence) {
	throw new IndexOutOfBoundsException(Integer.toString(index));
	}
	array[index++] = value;
	}
	}
	}

	@SuppressWarnings("serial")
	private abstract static class ToArrayTask<T, T_NODE extends Node<T>,
	K extends ToArrayTask<T, T_NODE, K>>
	extends CountedCompleter<Void> {
	protected final T_NODE node;
	protected final int offset;

	ToArrayTask(T_NODE node, int offset) {
	this.node = node;
	this.offset = offset;
	}

	ToArrayTask(K parent, T_NODE node, int offset) {
	super(parent);
	this.node = node;
	this.offset = offset;
	}

	abstract void copyNodeToArray();

	abstract K makeChild(int childIndex, int offset);

	@Override
	public void compute() {
	ToArrayTask<T, T_NODE, K> task = this;
	while (true) {
	if (task.node.getChildCount() == 0) {
	task.copyNodeToArray();
	task.propagateCompletion();
	return;
	}
	else {
	task.setPendingCount(task.node.getChildCount() - 1);

	int size = 0;
	int i = 0;
	for (;i < task.node.getChildCount() - 1; i++) {
	K leftTask = task.makeChild(i, task.offset + size);
	size += leftTask.node.count();
	leftTask.fork();
	}
	task = task.makeChild(i, task.offset + size);
	}
	}
	}

	@SuppressWarnings("serial")
	private static final class OfRef<T>
	extends ToArrayTask<T, Node<T>, OfRef<T>> {
	private final T[] array;

	private OfRef(Node<T> node, T[] array, int offset) {
	super(node, offset);
	this.array = array;
	}

	private OfRef(OfRef<T> parent, Node<T> node, int offset) {
	super(parent, node, offset);
	this.array = parent.array;
	}

	@Override
	OfRef<T> makeChild(int childIndex, int offset) {
	return new OfRef<>(this, node.getChild(childIndex), offset);
	}

	@Override
	void copyNodeToArray() {
	node.copyInto(array, offset);
	}
	}

	@SuppressWarnings("serial")
	private static class OfPrimitive<T, T_CONS, T_ARR,
	T_SPLITR extends Spliterator.OfPrimitive<T, T_CONS, T_SPLITR>,
	T_NODE extends Node.OfPrimitive<T, T_CONS, T_ARR, T_SPLITR, T_NODE>>
	extends ToArrayTask<T, T_NODE, OfPrimitive<T, T_CONS, T_ARR, T_SPLITR, T_NODE>> {
	private final T_ARR array;

	private OfPrimitive(T_NODE node, T_ARR array, int offset) {
	super(node, offset);
	this.array = array;
	}

	private OfPrimitive(OfPrimitive<T, T_CONS, T_ARR, T_SPLITR, T_NODE> parent, T_NODE node, int offset) {
	super(parent, node, offset);
	this.array = parent.array;
	}

	@Override
	OfPrimitive<T, T_CONS, T_ARR, T_SPLITR, T_NODE> makeChild(int childIndex, int offset) {
	return new OfPrimitive<>(this, node.getChild(childIndex), offset);
	}

	@Override
	void copyNodeToArray() {
	node.copyInto(array, offset);
	}
	}

	@SuppressWarnings("serial")
	private static final class OfInt
	extends OfPrimitive<Integer, IntConsumer, int[], Spliterator.OfInt, Node.OfInt> {
	private OfInt(Node.OfInt node, int[] array, int offset) {
	super(node, array, offset);
	}
	}

	@SuppressWarnings("serial")
	private static final class OfLong
	extends OfPrimitive<Long, LongConsumer, long[], Spliterator.OfLong, Node.OfLong> {
	private OfLong(Node.OfLong node, long[] array, int offset) {
	super(node, array, offset);
	}
	}

	@SuppressWarnings("serial")
	private static final class OfDouble
	extends OfPrimitive<Double, DoubleConsumer, double[], Spliterator.OfDouble, Node.OfDouble> {
	private OfDouble(Node.OfDouble node, double[] array, int offset) {
	super(node, array, offset);
	}
	}
	}

	@SuppressWarnings("serial")
	private static class CollectorTask<P_IN, P_OUT, T_NODE extends Node<P_OUT>, T_BUILDER extends Node.Builder<P_OUT>>
	extends AbstractTask<P_IN, P_OUT, T_NODE, CollectorTask<P_IN, P_OUT, T_NODE, T_BUILDER>> {
	protected final PipelineHelper<P_OUT> helper;
	protected final LongFunction<T_BUILDER> builderFactory;
	protected final BinaryOperator<T_NODE> concFactory;

	CollectorTask(PipelineHelper<P_OUT> helper,
	Spliterator<P_IN> spliterator,
	LongFunction<T_BUILDER> builderFactory,
	BinaryOperator<T_NODE> concFactory) {
	super(helper, spliterator);
	this.helper = helper;
	this.builderFactory = builderFactory;
	this.concFactory = concFactory;
	}

	CollectorTask(CollectorTask<P_IN, P_OUT, T_NODE, T_BUILDER> parent,
	Spliterator<P_IN> spliterator) {
	super(parent, spliterator);
	helper = parent.helper;
	builderFactory = parent.builderFactory;
	concFactory = parent.concFactory;
	}

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

	@Override
	@SuppressWarnings("unchecked")
	protected T_NODE doLeaf() {
	T_BUILDER builder = builderFactory.apply(helper.exactOutputSizeIfKnown(spliterator));
	return (T_NODE) helper.wrapAndCopyInto(builder, spliterator).build();
	}

	@Override
	public void onCompletion(CountedCompleter<?> caller) {
	if (!isLeaf())
	setLocalResult(concFactory.apply(leftChild.getLocalResult(), rightChild.getLocalResult()));
	super.onCompletion(caller);
	}

	@SuppressWarnings("serial")
	private static final class OfRef<P_IN, P_OUT>
	extends CollectorTask<P_IN, P_OUT, Node<P_OUT>, Node.Builder<P_OUT>> {
	OfRef(PipelineHelper<P_OUT> helper,
	IntFunction<P_OUT[]> generator,
	Spliterator<P_IN> spliterator) {
	super(helper, spliterator, s -> builder(s, generator), ConcNode::new);
	}
	}

	@SuppressWarnings("serial")
	private static final class OfInt<P_IN>
	extends CollectorTask<P_IN, Integer, Node.OfInt, Node.Builder.OfInt> {
	OfInt(PipelineHelper<Integer> helper, Spliterator<P_IN> spliterator) {
	super(helper, spliterator, Nodes::intBuilder, ConcNode.OfInt::new);
	}
	}

	@SuppressWarnings("serial")
	private static final class OfLong<P_IN>
	extends CollectorTask<P_IN, Long, Node.OfLong, Node.Builder.OfLong> {
	OfLong(PipelineHelper<Long> helper, Spliterator<P_IN> spliterator) {
	super(helper, spliterator, Nodes::longBuilder, ConcNode.OfLong::new);
	}
	}

	@SuppressWarnings("serial")
	private static final class OfDouble<P_IN>
	extends CollectorTask<P_IN, Double, Node.OfDouble, Node.Builder.OfDouble> {
	OfDouble(PipelineHelper<Double> helper, Spliterator<P_IN> spliterator) {
	super(helper, spliterator, Nodes::doubleBuilder, ConcNode.OfDouble::new);
	}
	}
	}
	}

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