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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

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package java.util.stream;

import java.util.IntSummaryStatistics;

import java.util.Objects;

import java.util.OptionalDouble;

import java.util.OptionalInt;

import java.util.PrimitiveIterator;

import java.util.Spliterator;

import java.util.Spliterators;

import java.util.function.BiConsumer;

import java.util.function.BinaryOperator;

import java.util.function.IntBinaryOperator;

import java.util.function.IntConsumer;

import java.util.function.IntFunction;

import java.util.function.IntPredicate;

import java.util.function.IntToDoubleFunction;

import java.util.function.IntToLongFunction;

import java.util.function.IntUnaryOperator;

import java.util.function.ObjIntConsumer;

import java.util.function.Supplier;

/**

 * Abstract base class for an intermediate pipeline stage or pipeline source

 * stage implementing whose elements are of type {@code int}.

 *

 * @param <E_IN> type of elements in the upstream source

 * @since 1.8

 */

abstract class IntPipeline<E_IN>

        extends AbstractPipeline<E_IN, Integer, IntStream>

        implements IntStream {

    /**

     * Constructor for the head of a stream pipeline.

     *

     * @param source {@code Supplier<Spliterator>} describing the stream source

     * @param sourceFlags The source flags for the stream source, described in

     *        {@link StreamOpFlag}

     * @param parallel {@code true} if the pipeline is parallel

     */

    IntPipeline(Supplier<? extends Spliterator<Integer>> source,

                int sourceFlags, boolean parallel) {

        super(source, sourceFlags, parallel);

    }

    /**

     * Constructor for the head of a stream pipeline.

     *

     * @param source {@code Spliterator} describing the stream source

     * @param sourceFlags The source flags for the stream source, described in

     *        {@link StreamOpFlag}

     * @param parallel {@code true} if the pipeline is parallel

     */

    IntPipeline(Spliterator<Integer> source,

                int sourceFlags, boolean parallel) {

        super(source, sourceFlags, parallel);

    }

    /**

     * Constructor for appending an intermediate operation onto an existing

     * pipeline.

     *

     * @param upstream the upstream element source

     * @param opFlags the operation flags for the new operation

     */

    IntPipeline(AbstractPipeline<?, E_IN, ?> upstream, int opFlags) {

        super(upstream, opFlags);

    }

    /**

     * Adapt a {@code Sink<Integer> to an {@code IntConsumer}, ideally simply

     * by casting.

     */

    private static IntConsumer adapt(Sink<Integer> sink) {

        if (sink instanceof IntConsumer) {

            return (IntConsumer) sink;

        }

        else {

            if (Tripwire.ENABLED)

                Tripwire.trip(AbstractPipeline.class,

                              "using IntStream.adapt(Sink<Integer> s)");

            return sink::accept;

        }

    }

    /**

     * Adapt a {@code Spliterator<Integer>} to a {@code Spliterator.OfInt}.

     *

     * @implNote

     * The implementation attempts to cast to a Spliterator.OfInt, and throws an

     * exception if this cast is not possible.

     */

    private static Spliterator.OfInt adapt(Spliterator<Integer> s) {

        if (s instanceof Spliterator.OfInt) {

            return (Spliterator.OfInt) s;

        }

        else {

            if (Tripwire.ENABLED)

                Tripwire.trip(AbstractPipeline.class,

                              "using IntStream.adapt(Spliterator<Integer> s)");

            throw new UnsupportedOperationException("IntStream.adapt(Spliterator<Integer> s)");

        }

    }

    // Shape-specific methods

    @Override

    final StreamShape getOutputShape() {

        return StreamShape.INT_VALUE;

    }

    @Override

    final <P_IN> Node<Integer> evaluateToNode(PipelineHelper<Integer> helper,

                                              Spliterator<P_IN> spliterator,

                                              boolean flattenTree,

                                              IntFunction<Integer[]> generator) {

        return Nodes.collectInt(helper, spliterator, flattenTree);

    }

    @Override

    final <P_IN> Spliterator<Integer> wrap(PipelineHelper<Integer> ph,

                                           Supplier<Spliterator<P_IN>> supplier,

                                           boolean isParallel) {

        return new StreamSpliterators.IntWrappingSpliterator<>(ph, supplier, isParallel);

    }

    @Override

    @SuppressWarnings("unchecked")

    final Spliterator.OfInt lazySpliterator(Supplier<? extends Spliterator<Integer>> supplier) {

        return new StreamSpliterators.DelegatingSpliterator.OfInt((Supplier<Spliterator.OfInt>) supplier);

    }

    @Override

    final void forEachWithCancel(Spliterator<Integer> spliterator, Sink<Integer> sink) {

        Spliterator.OfInt spl = adapt(spliterator);

        IntConsumer adaptedSink = adapt(sink);

        do { } while (!sink.cancellationRequested() && spl.tryAdvance(adaptedSink));

    }

    @Override

    final Node.Builder<Integer> makeNodeBuilder(long exactSizeIfKnown,

                                                IntFunction<Integer[]> generator) {

        return Nodes.intBuilder(exactSizeIfKnown);

    }

    // IntStream

    @Override

    public final PrimitiveIterator.OfInt iterator() {

        return Spliterators.iterator(spliterator());

    }

    @Override

    public final Spliterator.OfInt spliterator() {

        return adapt(super.spliterator());

    }

    // Stateless intermediate ops from IntStream

    @Override

    public final LongStream asLongStream() {

        return new LongPipeline.StatelessOp<Integer>(this, StreamShape.INT_VALUE,

                                                     StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

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

                return new Sink.ChainedInt<Long>(sink) {

                    @Override

                    public void accept(int t) {

                        downstream.accept((long) t);

                    }

                };

            }

        };

    }

    @Override

    public final DoubleStream asDoubleStream() {

        return new DoublePipeline.StatelessOp<Integer>(this, StreamShape.INT_VALUE,

                                                       StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

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

                return new Sink.ChainedInt<Double>(sink) {

                    @Override

                    public void accept(int t) {

                        downstream.accept((double) t);

                    }

                };

            }

        };

    }

    @Override

    public final Stream<Integer> boxed() {

        return mapToObj(Integer::valueOf);

    }

    @Override

    public final IntStream map(IntUnaryOperator mapper) {

        Objects.requireNonNull(mapper);

        return new StatelessOp<Integer>(this, StreamShape.INT_VALUE,

                                        StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

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

                return new Sink.ChainedInt<Integer>(sink) {

                    @Override

                    public void accept(int t) {

                        downstream.accept(mapper.applyAsInt(t));

                    }

                };

            }

        };

    }

    @Override

    public final <U> Stream<U> mapToObj(IntFunction<? extends U> mapper) {

        Objects.requireNonNull(mapper);

        return new ReferencePipeline.StatelessOp<Integer, U>(this, StreamShape.INT_VALUE,

                                                             StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

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

                return new Sink.ChainedInt<U>(sink) {

                    @Override

                    public void accept(int t) {

                        downstream.accept(mapper.apply(t));

                    }

                };

            }

        };

    }

    @Override

    public final LongStream mapToLong(IntToLongFunction mapper) {

        Objects.requireNonNull(mapper);

        return new LongPipeline.StatelessOp<Integer>(this, StreamShape.INT_VALUE,

                                                     StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

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

                return new Sink.ChainedInt<Long>(sink) {

                    @Override

                    public void accept(int t) {

                        downstream.accept(mapper.applyAsLong(t));

                    }

                };

            }

        };

    }

    @Override

    public final DoubleStream mapToDouble(IntToDoubleFunction mapper) {

        Objects.requireNonNull(mapper);

        return new DoublePipeline.StatelessOp<Integer>(this, StreamShape.INT_VALUE,

                                                       StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

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

                return new Sink.ChainedInt<Double>(sink) {

                    @Override

                    public void accept(int t) {

                        downstream.accept(mapper.applyAsDouble(t));

                    }

                };

            }

        };

    }

    @Override

    public final IntStream flatMap(IntFunction<? extends IntStream> mapper) {

        Objects.requireNonNull(mapper);

        return new StatelessOp<Integer>(this, StreamShape.INT_VALUE,

                                        StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {

            @Override

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

                return new Sink.ChainedInt<Integer>(sink) {

                    @Override

                    public void begin(long size) {

                        downstream.begin(-1);

                    }

                    @Override

                    public void accept(int t) {

                        try (IntStream result = mapper.apply(t)) {

                            // We can do better that this too; optimize for depth=0 case and just grab spliterator and forEach it

                            if (result != null)

                                result.sequential().forEach(i -> downstream.accept(i));

                        }

                    }

                };

            }

        };

    }

    @Override

    public IntStream unordered() {

        if (!isOrdered())

            return this;

        return new StatelessOp<Integer>(this, StreamShape.INT_VALUE, StreamOpFlag.NOT_ORDERED) {

            @Override

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

                return sink;

            }

        };

    }

    @Override

    public final IntStream filter(IntPredicate predicate) {

        Objects.requireNonNull(predicate);

        return new StatelessOp<Integer>(this, StreamShape.INT_VALUE,

                                        StreamOpFlag.NOT_SIZED) {

            @Override

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

                return new Sink.ChainedInt<Integer>(sink) {

                    @Override

                    public void begin(long size) {

                        downstream.begin(-1);

                    }

                    @Override

                    public void accept(int t) {

                        if (predicate.test(t))

                            downstream.accept(t);

                    }

                };

            }

        };

    }

    @Override

    public final IntStream peek(IntConsumer action) {

        Objects.requireNonNull(action);

        return new StatelessOp<Integer>(this, StreamShape.INT_VALUE,

                                        0) {

            @Override

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

                return new Sink.ChainedInt<Integer>(sink) {

                    @Override

                    public void accept(int t) {

                        action.accept(t);

                        downstream.accept(t);

                    }

                };

            }

        };

    }

    // Stateful intermediate ops from IntStream

    @Override

    public final IntStream limit(long maxSize) {

        if (maxSize < 0)

            throw new IllegalArgumentException(Long.toString(maxSize));

        return SliceOps.makeInt(this, 0, maxSize);

    }

    @Override

    public final IntStream skip(long n) {

        if (n < 0)

            throw new IllegalArgumentException(Long.toString(n));

        if (n == 0)

            return this;

        else

            return SliceOps.makeInt(this, n, -1);

    }

    @Override

    public final IntStream sorted() {

        return SortedOps.makeInt(this);

    }

    @Override

    public final IntStream distinct() {

        // While functional and quick to implement, this approach is not very efficient.

        // An efficient version requires an int-specific map/set implementation.

        return boxed().distinct().mapToInt(i -> i);

    }

    // Terminal ops from IntStream

    @Override

    public void forEach(IntConsumer action) {

        evaluate(ForEachOps.makeInt(action, false));

    }

    @Override

    public void forEachOrdered(IntConsumer action) {

        evaluate(ForEachOps.makeInt(action, true));

    }

    @Override

    public final int sum() {

        return reduce(0, Integer::sum);

    }

    @Override

    public final OptionalInt min() {

        return reduce(Math::min);

    }

    @Override

    public final OptionalInt max() {

        return reduce(Math::max);

    }

    @Override

    public final long count() {

        return evaluate(ReduceOps.makeIntCounting());

    }

    @Override

    public final OptionalDouble average() {

        long[] avg = collect(() -> new long[2],

                             (ll, i) -> {

                                 ll[0]++;

                                 ll[1] += i;

                             },

                             (ll, rr) -> {

                                 ll[0] += rr[0];

                                 ll[1] += rr[1];

                             });

        return avg[0] > 0

               ? OptionalDouble.of((double) avg[1] / avg[0])

               : OptionalDouble.empty();

    }

    @Override

    public final IntSummaryStatistics summaryStatistics() {

        return collect(IntSummaryStatistics::new, IntSummaryStatistics::accept,

                       IntSummaryStatistics::combine);

    }

    @Override

    public final int reduce(int identity, IntBinaryOperator op) {

        return evaluate(ReduceOps.makeInt(identity, op));

    }

    @Override

    public final OptionalInt reduce(IntBinaryOperator op) {

        return evaluate(ReduceOps.makeInt(op));

    }

    @Override

    public final <R> R collect(Supplier<R> supplier,

                               ObjIntConsumer<R> accumulator,

                               BiConsumer<R, R> combiner) {

        Objects.requireNonNull(combiner);

        BinaryOperator<R> operator = (left, right) -> {

            combiner.accept(left, right);

            return left;

        };

        return evaluate(ReduceOps.makeInt(supplier, accumulator, operator));

    }

    @Override

    public final boolean anyMatch(IntPredicate predicate) {

        return evaluate(MatchOps.makeInt(predicate, MatchOps.MatchKind.ANY));

    }

    @Override

    public final boolean allMatch(IntPredicate predicate) {

        return evaluate(MatchOps.makeInt(predicate, MatchOps.MatchKind.ALL));

    }

    @Override

    public final boolean noneMatch(IntPredicate predicate) {

        return evaluate(MatchOps.makeInt(predicate, MatchOps.MatchKind.NONE));

    }

    @Override

    public final OptionalInt findFirst() {

        return evaluate(FindOps.makeInt(true));

    }

    @Override

    public final OptionalInt findAny() {

        return evaluate(FindOps.makeInt(false));

    }

    @Override

    public final int[] toArray() {

        return Nodes.flattenInt((Node.OfInt) evaluateToArrayNode(Integer[]::new))

                        .asPrimitiveArray();

    }

    //

    /**

     * Source stage of an IntStream.

     *

     * @param <E_IN> type of elements in the upstream source

     * @since 1.8

     */

    static class Head<E_IN> extends IntPipeline<E_IN> {

        /**

         * Constructor for the source stage of an IntStream.

         *

         * @param source {@code Supplier<Spliterator>} describing the stream

         *               source

         * @param sourceFlags the source flags for the stream source, described