| /* | |
| * 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.Supplier; | |
| /** | |
| * Low-level utility methods for creating and manipulating streams. | |
| * | |
| * <p>This class is mostly for library writers presenting stream views | |
| * of data structures; most static stream methods intended for end users are in | |
| * the various {@code Stream} classes. | |
| * | |
| * @since 1.8 | |
| */ | |
| public final class StreamSupport { | |
| // Suppresses default constructor, ensuring non-instantiability. | |
| private StreamSupport() {} | |
| /** | |
| * Creates a new sequential or parallel {@code Stream} from a | |
| * {@code Spliterator}. | |
| * | |
| * <p>The spliterator is only traversed, split, or queried for estimated | |
| * size after the terminal operation of the stream pipeline commences. | |
| * | |
| * <p>It is strongly recommended the spliterator report a characteristic of | |
| * {@code IMMUTABLE} or {@code CONCURRENT}, or be | |
| * <a href="../Spliterator.html#binding">late-binding</a>. Otherwise, | |
| * {@link #stream(java.util.function.Supplier, int, boolean)} should be used | |
| * to reduce the scope of potential interference with the source. See | |
| * <a href="package-summary.html#NonInterference">Non-Interference</a> for | |
| * more details. | |
| * | |
| * @param <T> the type of stream elements | |
| * @param spliterator a {@code Spliterator} describing the stream elements | |
| * @param parallel if {@code true} then the returned stream is a parallel | |
| * stream; if {@code false} the returned stream is a sequential | |
| * stream. | |
| * @return a new sequential or parallel {@code Stream} | |
| */ | |
| public static <T> Stream<T> stream(Spliterator<T> spliterator, boolean parallel) { | |
| Objects.requireNonNull(spliterator); | |
| return new ReferencePipeline.Head<>(spliterator, | |
| StreamOpFlag.fromCharacteristics(spliterator), | |
| parallel); | |
| } | |
| /** | |
| * Creates a new sequential or parallel {@code Stream} from a | |
| * {@code Supplier} of {@code Spliterator}. | |
| * | |
| * <p>The {@link Supplier#get()} method will be invoked on the supplier no | |
| * more than once, and only after the terminal operation of the stream pipeline | |
| * commences. | |
| * | |
| * <p>For spliterators that report a characteristic of {@code IMMUTABLE} | |
| * or {@code CONCURRENT}, or that are | |
| * <a href="../Spliterator.html#binding">late-binding</a>, it is likely | |
| * more efficient to use {@link #stream(java.util.Spliterator, boolean)} | |
| * instead. | |
| * <p>The use of a {@code Supplier} in this form provides a level of | |
| * indirection that reduces the scope of potential interference with the | |
| * source. Since the supplier is only invoked after the terminal operation | |
| * commences, any modifications to the source up to the start of the | |
| * terminal operation are reflected in the stream result. See | |
| * <a href="package-summary.html#NonInterference">Non-Interference</a> for | |
| * more details. | |
| * | |
| * @param <T> the type of stream elements | |
| * @param supplier a {@code Supplier} of a {@code Spliterator} | |
| * @param characteristics Spliterator characteristics of the supplied | |
| * {@code Spliterator}. The characteristics must be equal to | |
| * {@code supplier.get().characteristics()}, otherwise undefined | |
| * behavior may occur when terminal operation commences. | |
| * @param parallel if {@code true} then the returned stream is a parallel | |
| * stream; if {@code false} the returned stream is a sequential | |
| * stream. | |
| * @return a new sequential or parallel {@code Stream} | |
| * @see #stream(java.util.Spliterator, boolean) | |
| */ | |
| public static <T> Stream<T> stream(Supplier<? extends Spliterator<T>> supplier, | |
| int characteristics, | |
| boolean parallel) { | |
| Objects.requireNonNull(supplier); | |
| return new ReferencePipeline.Head<>(supplier, | |
| StreamOpFlag.fromCharacteristics(characteristics), | |
| parallel); | |
| } | |
| /** | |
| * Creates a new sequential or parallel {@code IntStream} from a | |
| * {@code Spliterator.OfInt}. | |
| * | |
| * <p>The spliterator is only traversed, split, or queried for estimated size | |
| * after the terminal operation of the stream pipeline commences. | |
| * | |
| * <p>It is strongly recommended the spliterator report a characteristic of | |
| * {@code IMMUTABLE} or {@code CONCURRENT}, or be | |
| * <a href="../Spliterator.html#binding">late-binding</a>. Otherwise, | |
| * {@link #intStream(java.util.function.Supplier, int, boolean)} should be | |
| * used to reduce the scope of potential interference with the source. See | |
| * <a href="package-summary.html#NonInterference">Non-Interference</a> for | |
| * more details. | |
| * | |
| * @param spliterator a {@code Spliterator.OfInt} describing the stream elements | |
| * @param parallel if {@code true} then the returned stream is a parallel | |
| * stream; if {@code false} the returned stream is a sequential | |
| * stream. | |
| * @return a new sequential or parallel {@code IntStream} | |
| */ | |
| public static IntStream intStream(Spliterator.OfInt spliterator, boolean parallel) { | |
| return new IntPipeline.Head<>(spliterator, | |
| StreamOpFlag.fromCharacteristics(spliterator), | |
| parallel); | |
| } | |
| /** | |
| * Creates a new sequential or parallel {@code IntStream} from a | |
| * {@code Supplier} of {@code Spliterator.OfInt}. | |
| * | |
| * <p>The {@link Supplier#get()} method will be invoked on the supplier no | |
| * more than once, and only after the terminal operation of the stream pipeline | |
| * commences. | |
| * | |
| * <p>For spliterators that report a characteristic of {@code IMMUTABLE} | |
| * or {@code CONCURRENT}, or that are | |
| * <a href="../Spliterator.html#binding">late-binding</a>, it is likely | |
| * more efficient to use {@link #intStream(java.util.Spliterator.OfInt, boolean)} | |
| * instead. | |
| * <p>The use of a {@code Supplier} in this form provides a level of | |
| * indirection that reduces the scope of potential interference with the | |
| * source. Since the supplier is only invoked after the terminal operation | |
| * commences, any modifications to the source up to the start of the | |
| * terminal operation are reflected in the stream result. See | |
| * <a href="package-summary.html#NonInterference">Non-Interference</a> for | |
| * more details. | |
| * | |
| * @param supplier a {@code Supplier} of a {@code Spliterator.OfInt} | |
| * @param characteristics Spliterator characteristics of the supplied | |
| * {@code Spliterator.OfInt}. The characteristics must be equal to | |
| * {@code supplier.get().characteristics()}, otherwise undefined | |
| * behavior may occur when terminal operation commences. | |
| * @param parallel if {@code true} then the returned stream is a parallel | |
| * stream; if {@code false} the returned stream is a sequential | |
| * stream. | |
| * @return a new sequential or parallel {@code IntStream} | |
| * @see #intStream(java.util.Spliterator.OfInt, boolean) | |
| */ | |
| public static IntStream intStream(Supplier<? extends Spliterator.OfInt> supplier, | |
| int characteristics, | |
| boolean parallel) { | |
| return new IntPipeline.Head<>(supplier, | |
| StreamOpFlag.fromCharacteristics(characteristics), | |
| parallel); | |
| } | |
| /** | |
| * Creates a new sequential or parallel {@code LongStream} from a | |
| * {@code Spliterator.OfLong}. | |
| * | |
| * <p>The spliterator is only traversed, split, or queried for estimated | |
| * size after the terminal operation of the stream pipeline commences. | |
| * | |
| * <p>It is strongly recommended the spliterator report a characteristic of | |
| * {@code IMMUTABLE} or {@code CONCURRENT}, or be | |
| * <a href="../Spliterator.html#binding">late-binding</a>. Otherwise, | |
| * {@link #longStream(java.util.function.Supplier, int, boolean)} should be | |
| * used to reduce the scope of potential interference with the source. See | |
| * <a href="package-summary.html#NonInterference">Non-Interference</a> for | |
| * more details. | |
| * | |
| * @param spliterator a {@code Spliterator.OfLong} describing the stream elements | |
| * @param parallel if {@code true} then the returned stream is a parallel | |
| * stream; if {@code false} the returned stream is a sequential | |
| * stream. | |
| * @return a new sequential or parallel {@code LongStream} | |
| */ | |
| public static LongStream longStream(Spliterator.OfLong spliterator, | |
| boolean parallel) { | |
| return new LongPipeline.Head<>(spliterator, | |
| StreamOpFlag.fromCharacteristics(spliterator), | |
| parallel); | |
| } | |
| /** | |
| * Creates a new sequential or parallel {@code LongStream} from a | |
| * {@code Supplier} of {@code Spliterator.OfLong}. | |
| * | |
| * <p>The {@link Supplier#get()} method will be invoked on the supplier no | |
| * more than once, and only after the terminal operation of the stream pipeline | |
| * commences. | |
| * | |
| * <p>For spliterators that report a characteristic of {@code IMMUTABLE} | |
| * or {@code CONCURRENT}, or that are | |
| * <a href="../Spliterator.html#binding">late-binding</a>, it is likely | |
| * more efficient to use {@link #longStream(java.util.Spliterator.OfLong, boolean)} | |
| * instead. | |
| * <p>The use of a {@code Supplier} in this form provides a level of | |
| * indirection that reduces the scope of potential interference with the | |
| * source. Since the supplier is only invoked after the terminal operation | |
| * commences, any modifications to the source up to the start of the | |
| * terminal operation are reflected in the stream result. See | |
| * <a href="package-summary.html#NonInterference">Non-Interference</a> for | |
| * more details. | |
| * | |
| * @param supplier a {@code Supplier} of a {@code Spliterator.OfLong} | |
| * @param characteristics Spliterator characteristics of the supplied | |
| * {@code Spliterator.OfLong}. The characteristics must be equal to | |
| * {@code supplier.get().characteristics()}, otherwise undefined | |
| * behavior may occur when terminal operation commences. | |
| * @param parallel if {@code true} then the returned stream is a parallel | |
| * stream; if {@code false} the returned stream is a sequential | |
| * stream. | |
| * @return a new sequential or parallel {@code LongStream} | |
| * @see #longStream(java.util.Spliterator.OfLong, boolean) | |
| */ | |
| public static LongStream longStream(Supplier<? extends Spliterator.OfLong> supplier, | |
| int characteristics, | |
| boolean parallel) { | |
| return new LongPipeline.Head<>(supplier, | |
| StreamOpFlag.fromCharacteristics(characteristics), | |
| parallel); | |
| } | |
| /** | |
| * Creates a new sequential or parallel {@code DoubleStream} from a | |
| * {@code Spliterator.OfDouble}. | |
| * | |
| * <p>The spliterator is only traversed, split, or queried for estimated size | |
| * after the terminal operation of the stream pipeline commences. | |
| * | |
| * <p>It is strongly recommended the spliterator report a characteristic of | |
| * {@code IMMUTABLE} or {@code CONCURRENT}, or be | |
| * <a href="../Spliterator.html#binding">late-binding</a>. Otherwise, | |
| * {@link #doubleStream(java.util.function.Supplier, int, boolean)} should | |
| * be used to reduce the scope of potential interference with the source. See | |
| * <a href="package-summary.html#NonInterference">Non-Interference</a> for | |
| * more details. | |
| * | |
| * @param spliterator A {@code Spliterator.OfDouble} describing the stream elements | |
| * @param parallel if {@code true} then the returned stream is a parallel | |
| * stream; if {@code false} the returned stream is a sequential | |
| * stream. | |
| * @return a new sequential or parallel {@code DoubleStream} | |
| */ | |
| public static DoubleStream doubleStream(Spliterator.OfDouble spliterator, | |
| boolean parallel) { | |
| return new DoublePipeline.Head<>(spliterator, | |
| StreamOpFlag.fromCharacteristics(spliterator), | |
| parallel); | |
| } | |
| /** | |
| * Creates a new sequential or parallel {@code DoubleStream} from a | |
| * {@code Supplier} of {@code Spliterator.OfDouble}. | |
| * | |
| * <p>The {@link Supplier#get()} method will be invoked on the supplier no | |
| * more than once, and only after the terminal operation of the stream pipeline | |
| * commences. | |
| * | |
| * <p>For spliterators that report a characteristic of {@code IMMUTABLE} | |
| * or {@code CONCURRENT}, or that are | |
| * <a href="../Spliterator.html#binding">late-binding</a>, it is likely | |
| * more efficient to use {@link #doubleStream(java.util.Spliterator.OfDouble, boolean)} | |
| * instead. | |
| * <p>The use of a {@code Supplier} in this form provides a level of | |
| * indirection that reduces the scope of potential interference with the | |
| * source. Since the supplier is only invoked after the terminal operation | |
| * commences, any modifications to the source up to the start of the | |
| * terminal operation are reflected in the stream result. See | |
| * <a href="package-summary.html#NonInterference">Non-Interference</a> for | |
| * more details. | |
| * | |
| * @param supplier A {@code Supplier} of a {@code Spliterator.OfDouble} | |
| * @param characteristics Spliterator characteristics of the supplied | |
| * {@code Spliterator.OfDouble}. The characteristics must be equal to | |
| * {@code supplier.get().characteristics()}, otherwise undefined | |
| * behavior may occur when terminal operation commences. | |
| * @param parallel if {@code true} then the returned stream is a parallel | |
| * stream; if {@code false} the returned stream is a sequential | |
| * stream. | |
| * @return a new sequential or parallel {@code DoubleStream} | |
| * @see #doubleStream(java.util.Spliterator.OfDouble, boolean) | |
| */ | |
| public static DoubleStream doubleStream(Supplier<? extends Spliterator.OfDouble> supplier, | |
| int characteristics, | |
| boolean parallel) { | |
| return new DoublePipeline.Head<>(supplier, | |
| StreamOpFlag.fromCharacteristics(characteristics), | |
| parallel); | |
| } | |
| } |