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streamsupport is a backport of the Java 8 java.util.function (functional interfaces) and
java.util.stream (streams) API for Java 6 / 7 and Android developers
The newest version!
/*
* Copyright (c) 2012, 2020, 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 java8.util.stream;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java8.util.Objects;
import java8.util.function.BiConsumer;
import java8.util.function.BiFunction;
import java8.util.function.BinaryOperator;
import java8.util.function.BinaryOperators;
import java8.util.function.Consumer;
import java8.util.function.DoubleConsumer;
import java8.util.function.Function;
import java8.util.function.IntConsumer;
import java8.util.function.IntFunction;
import java8.util.function.LongConsumer;
import java8.util.function.Predicate;
import java8.util.function.Supplier;
import java8.util.function.ToDoubleFunction;
import java8.util.function.ToIntFunction;
import java8.util.function.ToLongFunction;
import java8.util.Optional;
import java8.util.Spliterator;
import java8.util.Spliterators;
/**
* Abstract base class for an intermediate pipeline stage or pipeline source
* stage implementing whose elements are of type {@code U}.
*
* @param type of elements in the upstream source
* @param type of elements in produced by this stage
*
* @since 1.8
*/
abstract class ReferencePipeline
extends AbstractPipeline>
implements Stream {
/**
* Constructor for the head of a stream pipeline.
*
* @param source {@code Supplier} 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
*/
ReferencePipeline(Supplier> 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
*/
ReferencePipeline(Spliterator 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.
*/
ReferencePipeline(AbstractPipeline upstream, int opFlags) {
super(upstream, opFlags);
}
// Shape-specific methods
@Override
final StreamShape getOutputShape() {
return StreamShape.REFERENCE;
}
@Override
final Node evaluateToNode(PipelineHelper helper,
Spliterator spliterator,
boolean flattenTree,
IntFunction generator) {
return Nodes.collect(helper, spliterator, flattenTree, generator);
}
@Override
final Spliterator wrap(PipelineHelper ph,
Supplier> supplier,
boolean isParallel) {
return new StreamSpliterators.WrappingSpliterator<>(ph, supplier, isParallel);
}
@Override
final Spliterator lazySpliterator(Supplier> supplier) {
return new StreamSpliterators.DelegatingSpliterator<>(supplier);
}
@Override
final boolean forEachWithCancel(Spliterator spliterator, Sink sink) {
boolean cancelled;
do { } while (!(cancelled = sink.cancellationRequested()) && spliterator.tryAdvance(sink));
return cancelled;
}
@Override
final Node.Builder makeNodeBuilder(long exactSizeIfKnown, IntFunction generator) {
return Nodes.builder(exactSizeIfKnown, generator);
}
// BaseStream
@Override
public final Iterator iterator() {
return Spliterators.iterator(spliterator());
}
// Stream
// Stateless intermediate operations from Stream
@Override
public Stream unordered() {
if (!isOrdered())
return this;
return new StatelessOp(this, StreamShape.REFERENCE, StreamOpFlag.NOT_ORDERED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return sink;
}
};
}
@Override
public final Stream filter(Predicate predicate) {
Objects.requireNonNull(predicate);
return new StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SIZED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void begin(long size) {
downstream.begin(-1);
}
@Override
public void accept(P_OUT u) {
if (predicate.test(u))
downstream.accept(u);
}
};
}
};
}
@Override
public final Stream map(Function mapper) {
Objects.requireNonNull(mapper);
return new StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void accept(P_OUT u) {
downstream.accept(mapper.apply(u));
}
};
}
};
}
@Override
public final IntStream mapToInt(ToIntFunction mapper) {
Objects.requireNonNull(mapper);
return new IntPipeline.StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void accept(P_OUT u) {
downstream.accept(mapper.applyAsInt(u));
}
};
}
};
}
@Override
public final LongStream mapToLong(ToLongFunction mapper) {
Objects.requireNonNull(mapper);
return new LongPipeline.StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void accept(P_OUT u) {
downstream.accept(mapper.applyAsLong(u));
}
};
}
};
}
@Override
public final DoubleStream mapToDouble(ToDoubleFunction mapper) {
Objects.requireNonNull(mapper);
return new DoublePipeline.StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void accept(P_OUT u) {
downstream.accept(mapper.applyAsDouble(u));
}
};
}
};
}
@Override
public final Stream flatMap(Function> mapper) {
Objects.requireNonNull(mapper);
return new StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
// true if cancellationRequested() has been called
boolean cancellationRequested;
@Override
public void begin(long size) {
downstream.begin(-1);
}
@Override
public void accept(P_OUT u) {
Stream result = null;
try {
result = mapper.apply(u);
if (result != null) {
if (!cancellationRequested) {
result.sequential().forEach(downstream);
}
else {
Spliterator s = result.sequential().spliterator();
do { } while (!downstream.cancellationRequested() && s.tryAdvance(downstream));
}
}
} finally {
if (result != null) {
result.close();
}
}
}
@Override
public boolean cancellationRequested() {
// If this method is called then an operation within the stream
// pipeline is short-circuiting (see AbstractPipeline.copyInto).
// Note that we cannot differentiate between an upstream or
// downstream operation
cancellationRequested = true;
return downstream.cancellationRequested();
}
};
}
};
}
@Override
public final IntStream flatMapToInt(Function mapper) {
Objects.requireNonNull(mapper);
return new IntPipeline.StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
// true if cancellationRequested() has been called
boolean cancellationRequested;
// cache the consumer to avoid creation on every accepted element
IntConsumer downstreamAsInt = downstream::accept;
@Override
public void begin(long size) {
downstream.begin(-1);
}
@Override
public void accept(P_OUT u) {
IntStream result = null;
try {
result = mapper.apply(u);
if (result != null) {
if (!cancellationRequested) {
result.sequential().forEach(downstreamAsInt);
}
else {
Spliterator.OfInt s = result.sequential().spliterator();
do { } while (!downstream.cancellationRequested() && s.tryAdvance(downstreamAsInt));
}
}
} finally {
if (result != null) {
result.close();
}
}
}
@Override
public boolean cancellationRequested() {
cancellationRequested = true;
return downstream.cancellationRequested();
}
};
}
};
}
@Override
public final DoubleStream flatMapToDouble(Function mapper) {
Objects.requireNonNull(mapper);
return new DoublePipeline.StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
// true if cancellationRequested() has been called
boolean cancellationRequested;
// cache the consumer to avoid creation on every accepted element
DoubleConsumer downstreamAsDouble = downstream::accept;
@Override
public void begin(long size) {
downstream.begin(-1);
}
@Override
public void accept(P_OUT u) {
DoubleStream result = null;
try {
result = mapper.apply(u);
if (result != null) {
if (!cancellationRequested) {
result.sequential().forEach(downstreamAsDouble);
}
else {
Spliterator.OfDouble s = result.sequential().spliterator();
do { } while (!downstream.cancellationRequested() && s.tryAdvance(downstreamAsDouble));
}
}
} finally {
if (result != null) {
result.close();
}
}
}
@Override
public boolean cancellationRequested() {
cancellationRequested = true;
return downstream.cancellationRequested();
}
};
}
};
}
@Override
public final LongStream flatMapToLong(Function mapper) {
Objects.requireNonNull(mapper);
return new LongPipeline.StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
// true if cancellationRequested() has been called
boolean cancellationRequested;
// cache the consumer to avoid creation on every accepted element
LongConsumer downstreamAsLong = downstream::accept;
@Override
public void begin(long size) {
downstream.begin(-1);
}
@Override
public void accept(P_OUT u) {
LongStream result = null;
try {
result = mapper.apply(u);
if (result != null) {
if (!cancellationRequested) {
result.sequential().forEach(downstreamAsLong);
}
else {
Spliterator.OfLong s = result.sequential().spliterator();
do { } while (!downstream.cancellationRequested() && s.tryAdvance(downstreamAsLong));
}
}
} finally {
if (result != null) {
result.close();
}
}
}
@Override
public boolean cancellationRequested() {
cancellationRequested = true;
return downstream.cancellationRequested();
}
};
}
};
}
@Override
public final Stream mapMulti(BiConsumer> mapper) {
Objects.requireNonNull(mapper);
return new StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void begin(long size) {
downstream.begin(-1);
}
@Override
@SuppressWarnings("unchecked")
public void accept(P_OUT u) {
mapper.accept(u, (Consumer) downstream);
}
};
}
};
}
@Override
public final IntStream mapMultiToInt(BiConsumer mapper) {
Objects.requireNonNull(mapper);
return new IntPipeline.StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void begin(long size) {
downstream.begin(-1);
}
@Override
public void accept(P_OUT u) {
mapper.accept(u, (IntConsumer)downstream);
}
};
}
};
}
@Override
public final LongStream mapMultiToLong(BiConsumer mapper) {
Objects.requireNonNull(mapper);
return new LongPipeline.StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void begin(long size) {
downstream.begin(-1);
}
@Override
public void accept(P_OUT u) {
mapper.accept(u, (LongConsumer) downstream);
}
};
}
};
}
@Override
public final DoubleStream mapMultiToDouble(BiConsumer mapper) {
Objects.requireNonNull(mapper);
return new DoublePipeline.StatelessOp(this, StreamShape.REFERENCE,
StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void begin(long size) {
downstream.begin(-1);
}
@Override
public void accept(P_OUT u) {
mapper.accept(u, (DoubleConsumer) downstream);
}
};
}
};
}
@Override
public final Stream peek(Consumer action) {
Objects.requireNonNull(action);
return new StatelessOp(this, StreamShape.REFERENCE,
0) {
@Override
Sink opWrapSink(int flags, Sink sink) {
return new Sink.ChainedReference(sink) {
@Override
public void accept(P_OUT u) {
action.accept(u);
downstream.accept(u);
}
};
}
};
}
// Stateful intermediate operations from Stream
@Override
public final Stream distinct() {
return DistinctOps.makeRef(this);
}
@Override
public final Stream sorted() {
return SortedOps.makeRef(this);
}
@Override
public final Stream sorted(Comparator comparator) {
return SortedOps.makeRef(this, comparator);
}
@Override
public final Stream limit(long maxSize) {
if (maxSize < 0)
throw new IllegalArgumentException(Long.toString(maxSize));
return SliceOps.makeRef(this, 0, maxSize);
}
@Override
public final Stream skip(long n) {
if (n < 0)
throw new IllegalArgumentException(Long.toString(n));
if (n == 0)
return this;
else
return SliceOps.makeRef(this, n, -1);
}
@Override
public final Stream takeWhile(Predicate predicate) {
return WhileOps.makeTakeWhileRef(this, predicate);
}
@Override
public final Stream dropWhile(Predicate predicate) {
return WhileOps.makeDropWhileRef(this, predicate);
}
// Terminal operations from Stream
@Override
public void forEach(Consumer action) {
evaluate(ForEachOps.makeRef(action, false));
}
@Override
public void forEachOrdered(Consumer action) {
evaluate(ForEachOps.makeRef(action, true));
}
@Override
@SuppressWarnings("unchecked")
public final A[] toArray(IntFunction generator) {
// Since A has no relation to U (not possible to declare that A is an upper bound of U)
// there will be no static type checking.
// Therefore use a raw type and assume A == U rather than propagating the separation of A and U
// throughout the code-base.
// The runtime type of U is never checked for equality with the component type of the runtime type of A[].
// Runtime checking will be performed when an element is stored in A[], thus if A is not a
// super type of U an ArrayStoreException will be thrown.
@SuppressWarnings("rawtypes")
IntFunction rawGenerator = (IntFunction) generator;
return (A[]) Nodes.flatten((Node) evaluateToArrayNode(rawGenerator), generator)
.asArray(rawGenerator);
}
@Override
public final Object[] toArray() {
return toArray(Object[]::new);
}
@Override
public List toList() {
return Collectors.listFromTrustedArrayNullsAllowed(this.toArray());
}
@Override
public final boolean anyMatch(Predicate predicate) {
return evaluate(MatchOps.makeRef(predicate, MatchOps.MatchKind.ANY));
}
@Override
public final boolean allMatch(Predicate predicate) {
return evaluate(MatchOps.makeRef(predicate, MatchOps.MatchKind.ALL));
}
@Override
public final boolean noneMatch(Predicate predicate) {
return evaluate(MatchOps.makeRef(predicate, MatchOps.MatchKind.NONE));
}
@Override
public final Optional findFirst() {
return evaluate(FindOps.makeRef(true));
}
@Override
public final Optional findAny() {
return evaluate(FindOps.makeRef(false));
}
@Override
public final P_OUT reduce(P_OUT identity, BinaryOperator accumulator) {
return evaluate(ReduceOps.makeRef(identity, accumulator, accumulator));
}
@Override
public final Optional reduce(BinaryOperator accumulator) {
return evaluate(ReduceOps.makeRef(accumulator));
}
@Override
public final R reduce(R identity, BiFunction accumulator, BinaryOperator combiner) {
return evaluate(ReduceOps.makeRef(identity, accumulator, combiner));
}
@Override
@SuppressWarnings("unchecked")
public final R collect(Collector collector) {
A container;
if (isParallel()
&& (collector.characteristics().contains(Collector.Characteristics.CONCURRENT))
&& (!isOrdered() || collector.characteristics().contains(Collector.Characteristics.UNORDERED))) {
container = collector.supplier().get();
BiConsumer accumulator = collector.accumulator();
forEach(u -> accumulator.accept(container, u));
}
else {
container = evaluate(ReduceOps.makeRef(collector));
}
return collector.characteristics().contains(Collector.Characteristics.IDENTITY_FINISH)
? (R) container
: collector.finisher().apply(container);
}
@Override
public final R collect(Supplier supplier,
BiConsumer accumulator,
BiConsumer combiner) {
return evaluate(ReduceOps.makeRef(supplier, accumulator, combiner));
}
@Override
public final Optional max(Comparator comparator) {
return reduce(BinaryOperators.maxBy(comparator));
}
@Override
public final Optional min(Comparator comparator) {
return reduce(BinaryOperators.minBy(comparator));
}
@Override
public final long count() {
return evaluate(ReduceOps.makeRefCounting());
}
//
/**
* Source stage of a ReferencePipeline.
*
* @param type of elements in the upstream source
* @param type of elements in produced by this stage
* @since 1.8
*/
static class Head extends ReferencePipeline {
/**
* Constructor for the source stage of a Stream.
*
* @param source {@code Supplier} describing the stream
* source
* @param sourceFlags the source flags for the stream source, described
* in {@link StreamOpFlag}
*/
Head(Supplier> source,
int sourceFlags, boolean parallel) {
super(source, sourceFlags, parallel);
}
/**
* Constructor for the source stage of a Stream.
*
* @param source {@code Spliterator} describing the stream source
* @param sourceFlags the source flags for the stream source, described
* in {@link StreamOpFlag}
*/
Head(Spliterator source,
int sourceFlags, boolean parallel) {
super(source, sourceFlags, parallel);
}
@Override
final boolean opIsStateful() {
throw new UnsupportedOperationException();
}
@Override
final Sink opWrapSink(int flags, Sink sink) {
throw new UnsupportedOperationException();
}
// Optimized sequential terminal operations for the head of the pipeline
@Override
public void forEach(Consumer action) {
if (!isParallel()) {
sourceStageSpliterator().forEachRemaining(action);
}
else {
super.forEach(action);
}
}
@Override
public void forEachOrdered(Consumer action) {
if (!isParallel()) {
sourceStageSpliterator().forEachRemaining(action);
}
else {
super.forEachOrdered(action);
}
}
}
/**
* Base class for a stateless intermediate stage of a Stream.
*
* @param type of elements in the upstream source
* @param type of elements in produced by this stage
* @since 1.8
*/
abstract static class StatelessOp
extends ReferencePipeline {
/**
* Construct a new Stream by appending a stateless intermediate
* operation to an existing stream.
*
* @param upstream The upstream pipeline stage
* @param inputShape The stream shape for the upstream pipeline stage
* @param opFlags Operation flags for the new stage
*/
StatelessOp(AbstractPipeline upstream,
StreamShape inputShape,
int opFlags) {
super(upstream, opFlags);
}
@Override
final boolean opIsStateful() {
return false;
}
}
/**
* Base class for a stateful intermediate stage of a Stream.
*
* @param type of elements in the upstream source
* @param type of elements in produced by this stage
* @since 1.8
*/
abstract static class StatefulOp
extends ReferencePipeline {
/**
* Construct a new Stream by appending a stateful intermediate operation
* to an existing stream.
* @param upstream The upstream pipeline stage
* @param inputShape The stream shape for the upstream pipeline stage
* @param opFlags Operation flags for the new stage
*/
StatefulOp(AbstractPipeline upstream,
StreamShape inputShape,
int opFlags) {
super(upstream, opFlags);
}
@Override
final boolean opIsStateful() {
return true;
}
@Override
abstract Node opEvaluateParallel(PipelineHelper helper,
Spliterator spliterator,
IntFunction generator);
}
}