Back to index...

	/*
	* 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
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package java.util.stream;

	import java.util.Objects;
	import java.util.Spliterator;
	import java.util.function.DoublePredicate;
	import java.util.function.IntPredicate;
	import java.util.function.LongPredicate;
	import java.util.function.Predicate;
	import java.util.function.Supplier;

	/**
	* Factory for instances of a short-circuiting {@code TerminalOp} that implement
	* quantified predicate matching on the elements of a stream. Supported variants
	* include match-all, match-any, and match-none.
	*
	* @since 1.8
	*/
	final class MatchOps {

	private MatchOps() { }

	/**
	* Enum describing quantified match options -- all match, any match, none
	* match.
	*/
	enum MatchKind {
	/** Do all elements match the predicate? */
	ANY(true, true),

	/** Do any elements match the predicate? */
	ALL(false, false),

	/** Do no elements match the predicate? */
	NONE(true, false);

	private final boolean stopOnPredicateMatches;
	private final boolean shortCircuitResult;

	private MatchKind(boolean stopOnPredicateMatches,
	boolean shortCircuitResult) {
	this.stopOnPredicateMatches = stopOnPredicateMatches;
	this.shortCircuitResult = shortCircuitResult;
	}
	}

	/**
	* Constructs a quantified predicate matcher for a Stream.
	*
	* @param <T> the type of stream elements
	* @param predicate the {@code Predicate} to apply to stream elements
	* @param matchKind the kind of quantified match (all, any, none)
	* @return a {@code TerminalOp} implementing the desired quantified match
	* criteria
	*/
	public static <T> TerminalOp<T, Boolean> makeRef(Predicate<? super T> predicate,
	MatchKind matchKind) {
	Objects.requireNonNull(predicate);
	Objects.requireNonNull(matchKind);
	class MatchSink extends BooleanTerminalSink<T> {
	MatchSink() {
	super(matchKind);
	}

	@Override
	public void accept(T t) {
	if (!stop && predicate.test(t) == matchKind.stopOnPredicateMatches) {
	stop = true;
	value = matchKind.shortCircuitResult;
	}
	}
	}

	return new MatchOp<>(StreamShape.REFERENCE, matchKind, MatchSink::new);
	}

	/**
	* Constructs a quantified predicate matcher for an {@code IntStream}.
	*
	* @param predicate the {@code Predicate} to apply to stream elements
	* @param matchKind the kind of quantified match (all, any, none)
	* @return a {@code TerminalOp} implementing the desired quantified match
	* criteria
	*/
	public static TerminalOp<Integer, Boolean> makeInt(IntPredicate predicate,
	MatchKind matchKind) {
	Objects.requireNonNull(predicate);
	Objects.requireNonNull(matchKind);
	class MatchSink extends BooleanTerminalSink<Integer> implements Sink.OfInt {
	MatchSink() {
	super(matchKind);
	}

	@Override
	public void accept(int t) {
	if (!stop && predicate.test(t) == matchKind.stopOnPredicateMatches) {
	stop = true;
	value = matchKind.shortCircuitResult;
	}
	}
	}

	return new MatchOp<>(StreamShape.INT_VALUE, matchKind, MatchSink::new);
	}

	/**
	* Constructs a quantified predicate matcher for a {@code LongStream}.
	*
	* @param predicate the {@code Predicate} to apply to stream elements
	* @param matchKind the kind of quantified match (all, any, none)
	* @return a {@code TerminalOp} implementing the desired quantified match
	* criteria
	*/
	public static TerminalOp<Long, Boolean> makeLong(LongPredicate predicate,
	MatchKind matchKind) {
	Objects.requireNonNull(predicate);
	Objects.requireNonNull(matchKind);
	class MatchSink extends BooleanTerminalSink<Long> implements Sink.OfLong {

	MatchSink() {
	super(matchKind);
	}

	@Override
	public void accept(long t) {
	if (!stop && predicate.test(t) == matchKind.stopOnPredicateMatches) {
	stop = true;
	value = matchKind.shortCircuitResult;
	}
	}
	}

	return new MatchOp<>(StreamShape.LONG_VALUE, matchKind, MatchSink::new);
	}

	/**
	* Constructs a quantified predicate matcher for a {@code DoubleStream}.
	*
	* @param predicate the {@code Predicate} to apply to stream elements
	* @param matchKind the kind of quantified match (all, any, none)
	* @return a {@code TerminalOp} implementing the desired quantified match
	* criteria
	*/
	public static TerminalOp<Double, Boolean> makeDouble(DoublePredicate predicate,
	MatchKind matchKind) {
	Objects.requireNonNull(predicate);
	Objects.requireNonNull(matchKind);
	class MatchSink extends BooleanTerminalSink<Double> implements Sink.OfDouble {

	MatchSink() {
	super(matchKind);
	}

	@Override
	public void accept(double t) {
	if (!stop && predicate.test(t) == matchKind.stopOnPredicateMatches) {
	stop = true;
	value = matchKind.shortCircuitResult;
	}
	}
	}

	return new MatchOp<>(StreamShape.DOUBLE_VALUE, matchKind, MatchSink::new);
	}

	/**
	* A short-circuiting {@code TerminalOp} that evaluates a predicate on the
	* elements of a stream and determines whether all, any or none of those
	* elements match the predicate.
	*
	* @param <T> the output type of the stream pipeline
	*/
	private static final class MatchOp<T> implements TerminalOp<T, Boolean> {
	private final StreamShape inputShape;
	final MatchKind matchKind;
	final Supplier<BooleanTerminalSink<T>> sinkSupplier;

	/**
	* Constructs a {@code MatchOp}.
	*
	* @param shape the output shape of the stream pipeline
	* @param matchKind the kind of quantified match (all, any, none)
	* @param sinkSupplier {@code Supplier} for a {@code Sink} of the
	* appropriate shape which implements the matching operation
	*/
	MatchOp(StreamShape shape,
	MatchKind matchKind,
	Supplier<BooleanTerminalSink<T>> sinkSupplier) {
	this.inputShape = shape;
	this.matchKind = matchKind;
	this.sinkSupplier = sinkSupplier;
	}

	@Override
	public int getOpFlags() {
	return StreamOpFlag.IS_SHORT_CIRCUIT \| StreamOpFlag.NOT_ORDERED;
	}

	@Override
	public StreamShape inputShape() {
	return inputShape;
	}

	@Override
	public <S> Boolean evaluateSequential(PipelineHelper<T> helper,
	Spliterator<S> spliterator) {
	return helper.wrapAndCopyInto(sinkSupplier.get(), spliterator).getAndClearState();
	}

	@Override
	public <S> Boolean evaluateParallel(PipelineHelper<T> helper,
	Spliterator<S> spliterator) {
	// Approach for parallel implementation:
	// - Decompose as per usual
	// - run match on leaf chunks, call result "b"
	// - if b == matchKind.shortCircuitOn, complete early and return b
	// - else if we complete normally, return !shortCircuitOn

	return new MatchTask<>(this, helper, spliterator).invoke();
	}
	}

	/**
	* Boolean specific terminal sink to avoid the boxing costs when returning
	* results. Subclasses implement the shape-specific functionality.
	*
	* @param <T> The output type of the stream pipeline
	*/
	private abstract static class BooleanTerminalSink<T> implements Sink<T> {
	boolean stop;
	boolean value;

	BooleanTerminalSink(MatchKind matchKind) {
	value = !matchKind.shortCircuitResult;
	}

	public boolean getAndClearState() {
	return value;
	}

	@Override
	public boolean cancellationRequested() {
	return stop;
	}
	}

	/**
	* ForkJoinTask implementation to implement a parallel short-circuiting
	* quantified match
	*
	* @param <P_IN> the type of source elements for the pipeline
	* @param <P_OUT> the type of output elements for the pipeline
	*/
	@SuppressWarnings("serial")
	private static final class MatchTask<P_IN, P_OUT>
	extends AbstractShortCircuitTask<P_IN, P_OUT, Boolean, MatchTask<P_IN, P_OUT>> {
	private final MatchOp<P_OUT> op;

	/**
	* Constructor for root node
	*/
	MatchTask(MatchOp<P_OUT> op, PipelineHelper<P_OUT> helper,
	Spliterator<P_IN> spliterator) {
	super(helper, spliterator);
	this.op = op;
	}

	/**
	* Constructor for non-root node
	*/
	MatchTask(MatchTask<P_IN, P_OUT> parent, Spliterator<P_IN> spliterator) {
	super(parent, spliterator);
	this.op = parent.op;
	}

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

	@Override
	protected Boolean doLeaf() {
	boolean b = helper.wrapAndCopyInto(op.sinkSupplier.get(), spliterator).getAndClearState();
	if (b == op.matchKind.shortCircuitResult)
	shortCircuit(b);
	return null;
	}

	@Override
	protected Boolean getEmptyResult() {
	return !op.matchKind.shortCircuitResult;
	}
	}
	}

Back to index...