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