169 lines
6.3 KiB
Java
169 lines
6.3 KiB
Java
/*
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* Copyright (c) 2012, 2013, 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.nio.charset.Charset;
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import java.nio.file.Files;
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import java.nio.file.Path;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.Spliterator;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.function.IntConsumer;
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import java.util.function.Predicate;
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/**
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* Base interface for streams, which are sequences of elements supporting
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* sequential and parallel aggregate operations. The following example
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* illustrates an aggregate operation using the stream types {@link Stream}
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* and {@link IntStream}, computing the sum of the weights of the red widgets:
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*
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* <pre>{@code
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* int sum = widgets.stream()
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* .filter(w -> w.getColor() == RED)
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* .mapToInt(w -> w.getWeight())
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* .sum();
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* }</pre>
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*
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* See the class documentation for {@link Stream} and the package documentation
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* for <a href="package-summary.html">java.util.stream</a> for additional
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* specification of streams, stream operations, stream pipelines, and
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* parallelism, which governs the behavior of all stream types.
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*
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* @param <T> the type of the stream elements
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* @param <S> the type of the stream implementing {@code BaseStream}
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* @since 1.8
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* @see Stream
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* @see IntStream
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* @see LongStream
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* @see DoubleStream
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* @see <a href="package-summary.html">java.util.stream</a>
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*/
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public interface BaseStream<T, S extends BaseStream<T, S>>
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extends AutoCloseable {
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/**
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* Returns an iterator for the elements of this stream.
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*
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* <p>This is a <a href="package-summary.html#StreamOps">terminal
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* operation</a>.
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*
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* @return the element iterator for this stream
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*/
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Iterator<T> iterator();
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/**
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* Returns a spliterator for the elements of this stream.
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*
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* <p>This is a <a href="package-summary.html#StreamOps">terminal
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* operation</a>.
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*
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* <p>
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* The returned spliterator should report the set of characteristics derived
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* from the stream pipeline (namely the characteristics derived from the
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* stream source spliterator and the intermediate operations).
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* Implementations may report a sub-set of those characteristics. For
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* example, it may be too expensive to compute the entire set for some or
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* all possible stream pipelines.
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*
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* @return the element spliterator for this stream
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*/
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Spliterator<T> spliterator();
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/**
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* Returns whether this stream, if a terminal operation were to be executed,
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* would execute in parallel. Calling this method after invoking an
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* terminal stream operation method may yield unpredictable results.
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*
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* @return {@code true} if this stream would execute in parallel if executed
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*/
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boolean isParallel();
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/**
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* Returns an equivalent stream that is sequential. May return
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* itself, either because the stream was already sequential, or because
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* the underlying stream state was modified to be sequential.
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*
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* <p>This is an <a href="package-summary.html#StreamOps">intermediate
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* operation</a>.
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*
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* @return a sequential stream
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*/
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S sequential();
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/**
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* Returns an equivalent stream that is parallel. May return
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* itself, either because the stream was already parallel, or because
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* the underlying stream state was modified to be parallel.
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*
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* <p>This is an <a href="package-summary.html#StreamOps">intermediate
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* operation</a>.
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*
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* @return a parallel stream
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*/
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S parallel();
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/**
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* Returns an equivalent stream that is
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* <a href="package-summary.html#Ordering">unordered</a>. May return
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* itself, either because the stream was already unordered, or because
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* the underlying stream state was modified to be unordered.
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*
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* <p>This is an <a href="package-summary.html#StreamOps">intermediate
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* operation</a>.
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*
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* @return an unordered stream
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*/
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S unordered();
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/**
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* Returns an equivalent stream with an additional close handler. Close
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* handlers are run when the {@link #close()} method
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* is called on the stream, and are executed in the order they were
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* added. All close handlers are run, even if earlier close handlers throw
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* exceptions. If any close handler throws an exception, the first
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* exception thrown will be relayed to the caller of {@code close()}, with
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* any remaining exceptions added to that exception as suppressed exceptions
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* (unless one of the remaining exceptions is the same exception as the
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* first exception, since an exception cannot suppress itself.) May
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* return itself.
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*
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* <p>This is an <a href="package-summary.html#StreamOps">intermediate
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* operation</a>.
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*
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* @param closeHandler A task to execute when the stream is closed
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* @return a stream with a handler that is run if the stream is closed
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*/
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S onClose(Runnable closeHandler);
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/**
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* Closes this stream, causing all close handlers for this stream pipeline
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* to be called.
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*
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* @see AutoCloseable#close()
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*/
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@Override
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void close();
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}
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