| /* |
| * 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); |
| } |
| } |
