You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
319 lines
15 KiB
319 lines
15 KiB
/*
|
|
* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
|
|
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*/
|
|
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);
|
|
}
|
|
}
|