353 lines
14 KiB
Java
353 lines
14 KiB
Java
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/*
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* Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.util.stream;
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import java.util.Optional;
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import java.util.OptionalDouble;
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import java.util.OptionalInt;
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import java.util.OptionalLong;
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import java.util.Spliterator;
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import java.util.concurrent.CountedCompleter;
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import java.util.function.Predicate;
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import java.util.function.Supplier;
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/**
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* Factory for instances of a short-circuiting {@code TerminalOp} that searches
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* for an element in a stream pipeline, and terminates when it finds one.
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* Supported variants include find-first (find the first element in the
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* encounter order) and find-any (find any element, may not be the first in
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* encounter order.)
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*
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* @since 1.8
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*/
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final class FindOps {
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private FindOps() { }
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/**
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* Constructs a {@code TerminalOp} for streams of objects.
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*
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* @param <T> the type of elements of the stream
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* @param mustFindFirst whether the {@code TerminalOp} must produce the
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* first element in the encounter order
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* @return a {@code TerminalOp} implementing the find operation
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*/
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@SuppressWarnings("unchecked")
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public static <T> TerminalOp<T, Optional<T>> makeRef(boolean mustFindFirst) {
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return (TerminalOp<T, Optional<T>>)
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(mustFindFirst ? FindSink.OfRef.OP_FIND_FIRST : FindSink.OfRef.OP_FIND_ANY);
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}
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/**
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* Constructs a {@code TerminalOp} for streams of ints.
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*
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* @param mustFindFirst whether the {@code TerminalOp} must produce the
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* first element in the encounter order
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* @return a {@code TerminalOp} implementing the find operation
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*/
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public static TerminalOp<Integer, OptionalInt> makeInt(boolean mustFindFirst) {
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return mustFindFirst ? FindSink.OfInt.OP_FIND_FIRST : FindSink.OfInt.OP_FIND_ANY;
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}
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/**
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* Constructs a {@code TerminalOp} for streams of longs.
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*
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* @param mustFindFirst whether the {@code TerminalOp} must produce the
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* first element in the encounter order
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* @return a {@code TerminalOp} implementing the find operation
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*/
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public static TerminalOp<Long, OptionalLong> makeLong(boolean mustFindFirst) {
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return mustFindFirst ? FindSink.OfLong.OP_FIND_FIRST : FindSink.OfLong.OP_FIND_ANY;
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}
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/**
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* Constructs a {@code FindOp} for streams of doubles.
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*
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* @param mustFindFirst whether the {@code TerminalOp} must produce the
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* first element in the encounter order
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* @return a {@code TerminalOp} implementing the find operation
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*/
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public static TerminalOp<Double, OptionalDouble> makeDouble(boolean mustFindFirst) {
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return mustFindFirst ? FindSink.OfDouble.OP_FIND_FIRST : FindSink.OfDouble.OP_FIND_ANY;
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}
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/**
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* A short-circuiting {@code TerminalOp} that searches for an element in a
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* stream pipeline, and terminates when it finds one. Implements both
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* find-first (find the first element in the encounter order) and find-any
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* (find any element, may not be the first in encounter order.)
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*
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* @param <T> the output type of the stream pipeline
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* @param <O> the result type of the find operation, typically an optional
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* type
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*/
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private static final class FindOp<T, O> implements TerminalOp<T, O> {
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private final StreamShape shape;
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final int opFlags;
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final O emptyValue;
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final Predicate<O> presentPredicate;
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final Supplier<TerminalSink<T, O>> sinkSupplier;
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/**
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* Constructs a {@code FindOp}.
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*
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* @param mustFindFirst if true, must find the first element in
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* encounter order, otherwise can find any element
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* @param shape stream shape of elements to search
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* @param emptyValue result value corresponding to "found nothing"
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* @param presentPredicate {@code Predicate} on result value
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* corresponding to "found something"
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* @param sinkSupplier supplier for a {@code TerminalSink} implementing
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* the matching functionality
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*/
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FindOp(boolean mustFindFirst,
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StreamShape shape,
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O emptyValue,
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Predicate<O> presentPredicate,
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Supplier<TerminalSink<T, O>> sinkSupplier) {
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this.opFlags = StreamOpFlag.IS_SHORT_CIRCUIT | (mustFindFirst ? 0 : StreamOpFlag.NOT_ORDERED);
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this.shape = shape;
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this.emptyValue = emptyValue;
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this.presentPredicate = presentPredicate;
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this.sinkSupplier = sinkSupplier;
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}
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@Override
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public int getOpFlags() {
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return opFlags;
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}
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@Override
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public StreamShape inputShape() {
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return shape;
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}
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@Override
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public <S> O evaluateSequential(PipelineHelper<T> helper,
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Spliterator<S> spliterator) {
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O result = helper.wrapAndCopyInto(sinkSupplier.get(), spliterator).get();
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return result != null ? result : emptyValue;
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}
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@Override
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public <P_IN> O evaluateParallel(PipelineHelper<T> helper,
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Spliterator<P_IN> spliterator) {
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// This takes into account the upstream ops flags and the terminal
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// op flags and therefore takes into account findFirst or findAny
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boolean mustFindFirst = StreamOpFlag.ORDERED.isKnown(helper.getStreamAndOpFlags());
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return new FindTask<>(this, mustFindFirst, helper, spliterator).invoke();
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}
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}
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/**
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* Implementation of @{code TerminalSink} that implements the find
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* functionality, requesting cancellation when something has been found
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*
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* @param <T> The type of input element
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* @param <O> The result type, typically an optional type
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*/
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private abstract static class FindSink<T, O> implements TerminalSink<T, O> {
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boolean hasValue;
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T value;
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FindSink() {} // Avoid creation of special accessor
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@Override
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public void accept(T value) {
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if (!hasValue) {
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hasValue = true;
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this.value = value;
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}
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}
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@Override
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public boolean cancellationRequested() {
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return hasValue;
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}
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/** Specialization of {@code FindSink} for reference streams */
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static final class OfRef<T> extends FindSink<T, Optional<T>> {
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@Override
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public Optional<T> get() {
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return hasValue ? Optional.of(value) : null;
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}
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static final TerminalOp<?, ?> OP_FIND_FIRST = new FindOp<>(true,
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StreamShape.REFERENCE, Optional.empty(),
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Optional::isPresent, FindSink.OfRef::new);
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static final TerminalOp<?, ?> OP_FIND_ANY = new FindOp<>(false,
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StreamShape.REFERENCE, Optional.empty(),
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Optional::isPresent, FindSink.OfRef::new);
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}
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/** Specialization of {@code FindSink} for int streams */
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static final class OfInt extends FindSink<Integer, OptionalInt>
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implements Sink.OfInt {
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@Override
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public void accept(int value) {
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// Boxing is OK here, since few values will actually flow into the sink
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accept((Integer) value);
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}
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@Override
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public OptionalInt get() {
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return hasValue ? OptionalInt.of(value) : null;
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}
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static final TerminalOp<Integer, OptionalInt> OP_FIND_FIRST = new FindOp<>(true,
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StreamShape.INT_VALUE, OptionalInt.empty(),
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OptionalInt::isPresent, FindSink.OfInt::new);
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static final TerminalOp<Integer, OptionalInt> OP_FIND_ANY = new FindOp<>(false,
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StreamShape.INT_VALUE, OptionalInt.empty(),
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OptionalInt::isPresent, FindSink.OfInt::new);
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}
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/** Specialization of {@code FindSink} for long streams */
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static final class OfLong extends FindSink<Long, OptionalLong>
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implements Sink.OfLong {
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@Override
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public void accept(long value) {
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// Boxing is OK here, since few values will actually flow into the sink
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accept((Long) value);
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}
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@Override
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public OptionalLong get() {
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return hasValue ? OptionalLong.of(value) : null;
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}
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static final TerminalOp<Long, OptionalLong> OP_FIND_FIRST = new FindOp<>(true,
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StreamShape.LONG_VALUE, OptionalLong.empty(),
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OptionalLong::isPresent, FindSink.OfLong::new);
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static final TerminalOp<Long, OptionalLong> OP_FIND_ANY = new FindOp<>(false,
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StreamShape.LONG_VALUE, OptionalLong.empty(),
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OptionalLong::isPresent, FindSink.OfLong::new);
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}
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/** Specialization of {@code FindSink} for double streams */
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static final class OfDouble extends FindSink<Double, OptionalDouble>
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implements Sink.OfDouble {
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@Override
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public void accept(double value) {
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// Boxing is OK here, since few values will actually flow into the sink
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accept((Double) value);
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}
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@Override
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public OptionalDouble get() {
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return hasValue ? OptionalDouble.of(value) : null;
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}
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static final TerminalOp<Double, OptionalDouble> OP_FIND_FIRST = new FindOp<>(true,
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StreamShape.DOUBLE_VALUE, OptionalDouble.empty(),
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OptionalDouble::isPresent, FindSink.OfDouble::new);
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static final TerminalOp<Double, OptionalDouble> OP_FIND_ANY = new FindOp<>(false,
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StreamShape.DOUBLE_VALUE, OptionalDouble.empty(),
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OptionalDouble::isPresent, FindSink.OfDouble::new);
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}
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}
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/**
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* {@code ForkJoinTask} implementing parallel short-circuiting search
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* @param <P_IN> Input element type to the stream pipeline
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* @param <P_OUT> Output element type from the stream pipeline
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* @param <O> Result type from the find operation
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*/
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@SuppressWarnings("serial")
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private static final class FindTask<P_IN, P_OUT, O>
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extends AbstractShortCircuitTask<P_IN, P_OUT, O, FindTask<P_IN, P_OUT, O>> {
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private final FindOp<P_OUT, O> op;
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private final boolean mustFindFirst;
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FindTask(FindOp<P_OUT, O> op,
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boolean mustFindFirst,
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PipelineHelper<P_OUT> helper,
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Spliterator<P_IN> spliterator) {
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super(helper, spliterator);
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this.mustFindFirst = mustFindFirst;
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this.op = op;
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}
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FindTask(FindTask<P_IN, P_OUT, O> parent, Spliterator<P_IN> spliterator) {
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super(parent, spliterator);
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this.mustFindFirst = parent.mustFindFirst;
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this.op = parent.op;
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}
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@Override
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protected FindTask<P_IN, P_OUT, O> makeChild(Spliterator<P_IN> spliterator) {
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return new FindTask<>(this, spliterator);
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}
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@Override
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protected O getEmptyResult() {
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return op.emptyValue;
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}
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private void foundResult(O answer) {
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if (isLeftmostNode())
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shortCircuit(answer);
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else
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cancelLaterNodes();
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}
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@Override
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protected O doLeaf() {
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O result = helper.wrapAndCopyInto(op.sinkSupplier.get(), spliterator).get();
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if (!mustFindFirst) {
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if (result != null)
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shortCircuit(result);
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return null;
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}
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else {
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if (result != null) {
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foundResult(result);
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return result;
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}
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else
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return null;
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}
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}
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@Override
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public void onCompletion(CountedCompleter<?> caller) {
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if (mustFindFirst) {
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for (FindTask<P_IN, P_OUT, O> child = leftChild, p = null; child != p;
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p = child, child = rightChild) {
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O result = child.getLocalResult();
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if (result != null && op.presentPredicate.test(result)) {
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setLocalResult(result);
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foundResult(result);
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break;
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}
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}
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}
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super.onCompletion(caller);
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}
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}
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}
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