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 * Copyright (c) 2012, 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

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package java.util.stream;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Comparator;

import java.util.Objects;

import java.util.Spliterator;

import java.util.function.IntFunction;

/**

 * Factory methods for transforming streams into sorted streams.

 *

 * @since 1.8

 */

final class SortedOps {

    private SortedOps() { }

    /**

     * Appends a "sorted" operation to the provided stream.

     *

     * @param <T> the type of both input and output elements

     * @param upstream a reference stream with element type T

     */

    static <T> Stream<T> makeRef(AbstractPipeline<?, T, ?> upstream) {

        return new OfRef<>(upstream);

    }

    /**

     * Appends a "sorted" operation to the provided stream.

     *

     * @param <T> the type of both input and output elements

     * @param upstream a reference stream with element type T

     * @param comparator the comparator to order elements by

     */

    static <T> Stream<T> makeRef(AbstractPipeline<?, T, ?> upstream,

                                Comparator<? super T> comparator) {

        return new OfRef<>(upstream, comparator);

    }

    /**

     * Appends a "sorted" operation to the provided stream.

     *

     * @param <T> the type of both input and output elements

     * @param upstream a reference stream with element type T

     */

    static <T> IntStream makeInt(AbstractPipeline<?, Integer, ?> upstream) {

        return new OfInt(upstream);

    }

    /**

     * Appends a "sorted" operation to the provided stream.

     *

     * @param <T> the type of both input and output elements

     * @param upstream a reference stream with element type T

     */

    static <T> LongStream makeLong(AbstractPipeline<?, Long, ?> upstream) {

        return new OfLong(upstream);

    }

    /**

     * Appends a "sorted" operation to the provided stream.

     *

     * @param <T> the type of both input and output elements

     * @param upstream a reference stream with element type T

     */

    static <T> DoubleStream makeDouble(AbstractPipeline<?, Double, ?> upstream) {

        return new OfDouble(upstream);

    }

    /**

     * Specialized subtype for sorting reference streams

     */

    private static final class OfRef<T> extends ReferencePipeline.StatefulOp<T, T> {

        /**

         * Comparator used for sorting

         */

        private final boolean isNaturalSort;

        private final Comparator<? super T> comparator;

        /**

         * Sort using natural order of {@literal <T>} which must be

         * {@code Comparable}.

         */

        OfRef(AbstractPipeline<?, T, ?> upstream) {

            super(upstream, StreamShape.REFERENCE,

                  StreamOpFlag.IS_ORDERED | StreamOpFlag.IS_SORTED);

            this.isNaturalSort = true;

            // Will throw CCE when we try to sort if T is not Comparable

            @SuppressWarnings("unchecked")

            Comparator<? super T> comp = (Comparator<? super T>) Comparator.naturalOrder();

            this.comparator = comp;

        }

        /**

         * Sort using the provided comparator.

         *

         * @param comparator The comparator to be used to evaluate ordering.

         */

        OfRef(AbstractPipeline<?, T, ?> upstream, Comparator<? super T> comparator) {

            super(upstream, StreamShape.REFERENCE,

                  StreamOpFlag.IS_ORDERED | StreamOpFlag.NOT_SORTED);

            this.isNaturalSort = false;

            this.comparator = Objects.requireNonNull(comparator);

        }

        @Override

        public Sink<T> opWrapSink(int flags, Sink<T> sink) {

            Objects.requireNonNull(sink);

            // If the input is already naturally sorted and this operation

            // also naturally sorted then this is a no-op

            if (StreamOpFlag.SORTED.isKnown(flags) && isNaturalSort)

                return sink;

            else if (StreamOpFlag.SIZED.isKnown(flags))

                return new SizedRefSortingSink<>(sink, comparator);

            else

                return new RefSortingSink<>(sink, comparator);

        }

        @Override

        public <P_IN> Node<T> opEvaluateParallel(PipelineHelper<T> helper,

                                                 Spliterator<P_IN> spliterator,

                                                 IntFunction<T[]> generator) {

            // If the input is already naturally sorted and this operation

            // naturally sorts then collect the output

            if (StreamOpFlag.SORTED.isKnown(helper.getStreamAndOpFlags()) && isNaturalSort) {

                return helper.evaluate(spliterator, false, generator);

            }

            else {

                // @@@ Weak two-pass parallel implementation; parallel collect, parallel sort

                T[] flattenedData = helper.evaluate(spliterator, true, generator).asArray(generator);

                Arrays.parallelSort(flattenedData, comparator);

                return Nodes.node(flattenedData);

            }

        }

    }

    /**

     * Specialized subtype for sorting int streams.

     */

    private static final class OfInt extends IntPipeline.StatefulOp<Integer> {

        OfInt(AbstractPipeline<?, Integer, ?> upstream) {

            super(upstream, StreamShape.INT_VALUE,

                  StreamOpFlag.IS_ORDERED | StreamOpFlag.IS_SORTED);

        }

        @Override

        public Sink<Integer> opWrapSink(int flags, Sink<Integer> sink) {

            Objects.requireNonNull(sink);

            if (StreamOpFlag.SORTED.isKnown(flags))

                return sink;

            else if (StreamOpFlag.SIZED.isKnown(flags))

                return new SizedIntSortingSink(sink);

            else

                return new IntSortingSink(sink);

        }

        @Override

        public <P_IN> Node<Integer> opEvaluateParallel(PipelineHelper<Integer> helper,

                                                       Spliterator<P_IN> spliterator,

                                                       IntFunction<Integer[]> generator) {

            if (StreamOpFlag.SORTED.isKnown(helper.getStreamAndOpFlags())) {

                return helper.evaluate(spliterator, false, generator);

            }

            else {

                Node.OfInt n = (Node.OfInt) helper.evaluate(spliterator, true, generator);

                int[] content = n.asPrimitiveArray();

                Arrays.parallelSort(content);

                return Nodes.node(content);

            }

        }

    }

    /**

     * Specialized subtype for sorting long streams.

     */

    private static final class OfLong extends LongPipeline.StatefulOp<Long> {

        OfLong(AbstractPipeline<?, Long, ?> upstream) {

            super(upstream, StreamShape.LONG_VALUE,

                  StreamOpFlag.IS_ORDERED | StreamOpFlag.IS_SORTED);

        }

        @Override

        public Sink<Long> opWrapSink(int flags, Sink<Long> sink) {

            Objects.requireNonNull(sink);

            if (StreamOpFlag.SORTED.isKnown(flags))

                return sink;

            else if (StreamOpFlag.SIZED.isKnown(flags))

                return new SizedLongSortingSink(sink);

            else

                return new LongSortingSink(sink);

        }

        @Override

        public <P_IN> Node<Long> opEvaluateParallel(PipelineHelper<Long> helper,

                                                    Spliterator<P_IN> spliterator,

                                                    IntFunction<Long[]> generator) {

            if (StreamOpFlag.SORTED.isKnown(helper.getStreamAndOpFlags())) {

                return helper.evaluate(spliterator, false, generator);

            }

            else {

                Node.OfLong n = (Node.OfLong) helper.evaluate(spliterator, true, generator);

                long[] content = n.asPrimitiveArray();

                Arrays.parallelSort(content);

                return Nodes.node(content);

            }

        }

    }

    /**

     * Specialized subtype for sorting double streams.

     */

    private static final class OfDouble extends DoublePipeline.StatefulOp<Double> {

        OfDouble(AbstractPipeline<?, Double, ?> upstream) {

            super(upstream, StreamShape.DOUBLE_VALUE,

                  StreamOpFlag.IS_ORDERED | StreamOpFlag.IS_SORTED);

        }

        @Override

        public Sink<Double> opWrapSink(int flags, Sink<Double> sink) {

            Objects.requireNonNull(sink);

            if (StreamOpFlag.SORTED.isKnown(flags))

                return sink;

            else if (StreamOpFlag.SIZED.isKnown(flags))

                return new SizedDoubleSortingSink(sink);

            else

                return new DoubleSortingSink(sink);

        }

        @Override

        public <P_IN> Node<Double> opEvaluateParallel(PipelineHelper<Double> helper,

                                                      Spliterator<P_IN> spliterator,

                                                      IntFunction<Double[]> generator) {

            if (StreamOpFlag.SORTED.isKnown(helper.getStreamAndOpFlags())) {

                return helper.evaluate(spliterator, false, generator);

            }

            else {

                Node.OfDouble n = (Node.OfDouble) helper.evaluate(spliterator, true, generator);

                double[] content = n.asPrimitiveArray();

                Arrays.parallelSort(content);

                return Nodes.node(content);

            }

        }

    }

    /**

     * Abstract {@link Sink} for implementing sort on reference streams.

     *

     * <p>

     * Note: documentation below applies to reference and all primitive sinks.

     * <p>

     * Sorting sinks first accept all elements, buffering then into an array

     * or a re-sizable data structure, if the size of the pipeline is known or

     * unknown respectively.  At the end of the sink protocol those elements are

     * sorted and then pushed downstream.

     * This class records if {@link #cancellationRequested} is called.  If so it

     * can be inferred that the source pushing source elements into the pipeline

     * knows that the pipeline is short-circuiting.  In such cases sub-classes

     * pushing elements downstream will preserve the short-circuiting protocol

     * by calling {@code downstream.cancellationRequested()} and checking the

     * result is {@code false} before an element is pushed.

     * <p>

     * Note that the above behaviour is an optimization for sorting with

     * sequential streams.  It is not an error that more elements, than strictly

     * required to produce a result, may flow through the pipeline.  This can

     * occur, in general (not restricted to just sorting), for short-circuiting

     * parallel pipelines.

     */

        protected final Comparator<? super T> comparator;

        // @@@ could be a lazy final value, if/when support is added

        protected boolean cancellationWasRequested;

        AbstractRefSortingSink(Sink<? super T> downstream, Comparator<? super T> comparator) {

            super(downstream);

            this.comparator = comparator;

        }

        /**

         * Records is cancellation is requested so short-circuiting behaviour

         * can be preserved when the sorted elements are pushed downstream.

         *

         * @return false, as this sink never short-circuits.

         */

        @Override

        public final boolean cancellationRequested() {

            cancellationWasRequested = true;

            return false;

        }

    }

    /**

     * {@link Sink} for implementing sort on SIZED reference streams.

     */

    private static final class SizedRefSortingSink<T> extends AbstractRefSortingSink<T> {

        private T[] array;

        private int offset;

        SizedRefSortingSink(Sink<? super T> sink, Comparator<? super T> comparator) {

            super(sink, comparator);

        }

        @Override

        @SuppressWarnings("unchecked")

        public void begin(long size) {

            if (size >= Nodes.MAX_ARRAY_SIZE)

                throw new IllegalArgumentException(Nodes.BAD_SIZE);

            array = (T[]) new Object[(int) size];

        }

        @Override

        public void end() {

            Arrays.sort(array, 0, offset, comparator);

            downstream.begin(offset);

            if (!cancellationWasRequested) {

                for (int i = 0; i < offset; i++)

                    downstream.accept(array[i]);

            }

            else {

                for (int i = 0; i < offset && !downstream.cancellationRequested(); i++)

                    downstream.accept(array[i]);

            }

            downstream.end();

            array = null;

        }

        @Override

        public void accept(T t) {

            array[offset++] = t;

        }

    }

    /**

     * {@link Sink} for implementing sort on reference streams.

     */

    private static final class RefSortingSink<T> extends AbstractRefSortingSink<T> {

        private ArrayList<T> list;

        RefSortingSink(Sink<? super T> sink, Comparator<? super T> comparator) {

            super(sink, comparator);

        }

        @Override

        public void begin(long size) {

            if (size >= Nodes.MAX_ARRAY_SIZE)

                throw new IllegalArgumentException(Nodes.BAD_SIZE);

            list = (size >= 0) ? new ArrayList<>((int) size) : new ArrayList<>();

        }

        @Override

        public void end() {

            list.sort(comparator);

            downstream.begin(list.size());

            if (!cancellationWasRequested) {

                list.forEach(downstream::accept);

            }

            else {

                for (T t : list) {

                    if (downstream.cancellationRequested()) break;

                    downstream.accept(t);

                }

            }

            downstream.end();

            list = null;

        }

        @Override

        public void accept(T t) {

            list.add(t);

        }

    }

    /**

     * Abstract {@link Sink} for implementing sort on int streams.

     */

        protected boolean cancellationWasRequested;

        AbstractIntSortingSink(Sink<? super Integer> downstream) {

            super(downstream);

        }

        @Override

        public final boolean cancellationRequested() {

            cancellationWasRequested = true;

            return false;

        }

    }

    /**

     * {@link Sink} for implementing sort on SIZED int streams.

     */

    private static final class SizedIntSortingSink extends AbstractIntSortingSink {

        private int[] array;

        private int offset;

        SizedIntSortingSink(Sink<? super Integer> downstream) {

            super(downstream);

        }

        @Override

        public void begin(long size) {

            if (size >= Nodes.MAX_ARRAY_SIZE)

                throw new IllegalArgumentException(Nodes.BAD_SIZE);

            array = new int[(int) size];

        }

        @Override

        public void end() {

            Arrays.sort(array, 0, offset);

            downstream.begin(offset);

            if (!cancellationWasRequested) {

                for (int i = 0; i < offset; i++)

                    downstream.accept(array[i]);

            }

            else {

                for (int i = 0; i < offset && !downstream.cancellationRequested(); i++)

                    downstream.accept(array[i]);

            }

            downstream.end();

            array = null;

        }

        @Override

        public void accept(int t) {

            array[offset++] = t;

        }

    }

    /**

     * {@link Sink} for implementing sort on int streams.

     */

    private static final class IntSortingSink extends AbstractIntSortingSink {

        private SpinedBuffer.OfInt b;

        IntSortingSink(Sink<? super Integer> sink) {

            super(sink);

        }

        @Override

        public void begin(long size) {

            if (size >= Nodes.MAX_ARRAY_SIZE)

                throw new IllegalArgumentException(Nodes.BAD_SIZE);

            b = (size > 0) ? new SpinedBuffer.OfInt((int) size) : new SpinedBuffer.OfInt();

        }

        @Override

        public void end() {

            int[] ints = b.asPrimitiveArray();

            Arrays.sort(ints);

            downstream.begin(ints.length);

            if (!cancellationWasRequested) {

                for (int anInt : ints)

                    downstream.accept(anInt);

            }

            else {

                for (int anInt : ints) {

                    if (downstream.cancellationRequested()) break;

                    downstream.accept(anInt);

                }

            }

            downstream.end();

        }

        @Override

        public void accept(int t) {

            b.accept(t);

        }

    }

    /**

     * Abstract {@link Sink} for implementing sort on long streams.

     */

        protected boolean cancellationWasRequested;

        AbstractLongSortingSink(Sink<? super Long> downstream) {

            super(downstream);

        }