--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/util/stream/LongStream.java Wed Apr 17 14:39:04 2013 -0400
@@ -0,0 +1,646 @@
+/*
+ * Copyright (c) 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.LongSummaryStatistics;
+import java.util.OptionalDouble;
+import java.util.OptionalLong;
+import java.util.PrimitiveIterator;
+import java.util.Spliterator;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+import java.util.function.LongBinaryOperator;
+import java.util.function.LongConsumer;
+import java.util.function.LongFunction;
+import java.util.function.LongPredicate;
+import java.util.function.LongToDoubleFunction;
+import java.util.function.LongToIntFunction;
+import java.util.function.LongUnaryOperator;
+import java.util.function.ObjLongConsumer;
+import java.util.function.Supplier;
+
+/**
+ * A sequence of primitive long elements supporting sequential and parallel
+ * bulk operations. Streams support lazy intermediate operations (transforming
+ * a stream to another stream) such as {@code filter} and {@code map}, and terminal
+ * operations (consuming the contents of a stream to produce a result or
+ * side-effect), such as {@code forEach}, {@code findFirst}, and {@code
+ * iterator}. Once an operation has been performed on a stream, it
+ * is considered <em>consumed</em> and no longer usable for other operations.
+ *
+ * <p>For sequential stream pipelines, all operations are performed in the
+ * <a href="package-summary.html#Ordering">encounter order</a> of the pipeline
+ * source, if the pipeline source has a defined encounter order.
+ *
+ * <p>For parallel stream pipelines, unless otherwise specified, intermediate
+ * stream operations preserve the <a href="package-summary.html#Ordering">
+ * encounter order</a> of their source, and terminal operations
+ * respect the encounter order of their source, if the source
+ * has an encounter order. Provided that and parameters to stream operations
+ * satisfy the <a href="package-summary.html#NonInterference">non-interference
+ * requirements</a>, and excepting differences arising from the absence of
+ * a defined encounter order, the result of a stream pipeline should be the
+ * stable across multiple executions of the same operations on the same source.
+ * However, the timing and thread in which side-effects occur (for those
+ * operations which are allowed to produce side-effects, such as
+ * {@link #forEach(LongConsumer)}), are explicitly nondeterministic for parallel
+ * execution of stream pipelines.
+ *
+ * <p>Unless otherwise noted, passing a {@code null} argument to any stream
+ * method may result in a {@link NullPointerException}.
+ *
+ * @apiNote
+ * Streams are not data structures; they do not manage the storage for their
+ * elements, nor do they support access to individual elements. However,
+ * you can use the {@link #iterator()} or {@link #spliterator()} operations to
+ * perform a controlled traversal.
+ *
+ * @since 1.8
+ * @see <a href="package-summary.html">java.util.stream</a>
+ */
+public interface LongStream extends BaseStream<Long, LongStream> {
+
+ /**
+ * Returns a stream consisting of the elements of this stream that match
+ * the given predicate.
+ *
+ * <p>This is an <a href="package-summary.html#StreamOps">intermediate
+ * operation</a>.
+ *
+ * @param predicate a <a href="package-summary.html#NonInterference">
+ * non-interfering, stateless</a> predicate to apply to
+ * each element to determine if it should be included
+ * @return the new stream
+ */
+ LongStream filter(LongPredicate predicate);
+
+ /**
+ * Returns a stream consisting of the results of applying the given
+ * function to the elements of this stream.
+ *
+ * <p>This is an <a href="package-summary.html#StreamOps">intermediate
+ * operation</a>.
+ *
+ * @param mapper a <a href="package-summary.html#NonInterference">
+ * non-interfering, stateless</a> function to apply to each
+ * element
+ * @return the new stream
+ */
+ LongStream map(LongUnaryOperator mapper);
+
+ /**
+ * Returns an object-valued {@code Stream} consisting of the results of
+ * applying the given function to the elements of this stream.
+ *
+ * <p>This is an <a href="package-summary.html#StreamOps">
+ * intermediate operation</a>.
+ *
+ * @param <U> the element type of the new stream
+ * @param mapper a <a href="package-summary.html#NonInterference">
+ * non-interfering, stateless</a> function to apply to each
+ * element
+ * @return the new stream
+ */
+ <U> Stream<U> mapToObj(LongFunction<? extends U> mapper);
+
+ /**
+ * Returns an {@code IntStream} consisting of the results of applying the
+ * given function to the elements of this stream.
+ *
+ * <p>This is an <a href="package-summary.html#StreamOps">intermediate
+ * operation</a>.
+ *
+ * @param mapper a <a href="package-summary.html#NonInterference">
+ * non-interfering, stateless</a> function to apply to each
+ * element
+ * @return the new stream
+ */
+ IntStream mapToInt(LongToIntFunction mapper);
+
+ /**
+ * Returns a {@code DoubleStream} consisting of the results of applying the
+ * given function to the elements of this stream.
+ *
+ * <p>This is an <a href="package-summary.html#StreamOps">intermediate
+ * operation</a>.
+ *
+ * @param mapper a <a href="package-summary.html#NonInterference">
+ * non-interfering, stateless</a> function to apply to each
+ * element
+ * @return the new stream
+ */
+ DoubleStream mapToDouble(LongToDoubleFunction mapper);
+
+ /**
+ * Returns a stream consisting of the results of replacing each element of
+ * this stream with the contents of the stream produced by applying the
+ * provided mapping function to each element.
+ *
+ * <p>This is an <a href="package-summary.html#StreamOps">intermediate
+ * operation</a>.
+ *
+ * @apiNote
+ * The {@code flatMap()} operation has the effect of applying a one-to-many
+ * tranformation to the elements of the stream, and then flattening the
+ * resulting elements into a new stream. For example, if {@code orders}
+ * is a stream of purchase orders, and each purchase order contains a
+ * collection of line items, then the following produces a stream of line
+ * items:
+ * <pre>{@code
+ * orderStream.flatMap(order -> order.getLineItems().stream())...
+ * }</pre>
+ *
+ * @param mapper a <a href="package-summary.html#NonInterference">
+ * non-interfering, stateless</a> function to apply to
+ * each element which produces an {@code LongStream} of new
+ * values
+ * @return the new stream
+ * @see Stream#flatMap(Function)
+ */
+ LongStream flatMap(LongFunction<? extends LongStream> mapper);
+
+ /**
+ * Returns a stream consisting of the distinct elements of this stream.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">stateful
+ * intermediate operation</a>.
+ *
+ * @return the new stream
+ */
+ LongStream distinct();
+
+ /**
+ * Returns a stream consisting of the elements of this stream in sorted
+ * order.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">stateful
+ * intermediate operation</a>.
+ *
+ * @return the new stream
+ */
+ LongStream sorted();
+
+ /**
+ * Returns a stream consisting of the elements of this stream, additionally
+ * performing the provided action on each element as elements are consumed
+ * from the resulting stream.
+ *
+ * <p>This is an <a href="package-summary.html#StreamOps">intermediate
+ * operation</a>.
+ *
+ * <p>For parallel stream pipelines, the action may be called at
+ * whatever time and in whatever thread the element is made available by the
+ * upstream operation. If the action modifies shared state,
+ * it is responsible for providing the required synchronization.
+ *
+ * @apiNote This method exists mainly to support debugging, where you want
+ * to see the elements as they flow past a certain point in a pipeline:
+ * <pre>{@code
+ * list.stream()
+ * .filter(filteringFunction)
+ * .peek(e -> {System.out.println("Filtered value: " + e); });
+ * .map(mappingFunction)
+ * .peek(e -> {System.out.println("Mapped value: " + e); });
+ * .collect(Collectors.toLongSummaryStastistics());
+ * }</pre>
+ *
+ * @param consumer a <a href="package-summary.html#NonInterference">
+ * non-interfering</a> action to perform on the elements as
+ * they are consumed from the stream
+ * @return the new stream
+ */
+ LongStream peek(LongConsumer consumer);
+
+ /**
+ * Returns a stream consisting of the elements of this stream, truncated
+ * to be no longer than {@code maxSize} in length.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
+ * stateful intermediate operation</a>.
+ *
+ * @param maxSize the number of elements the stream should be limited to
+ * @return the new stream
+ * @throws IllegalArgumentException if {@code maxSize} is negative
+ */
+ LongStream limit(long maxSize);
+
+ /**
+ * Returns a stream consisting of the remaining elements of this stream
+ * after indexing {@code startInclusive} elements into the stream. If the
+ * {@code startInclusive} index lies past the end of this stream then an
+ * empty stream will be returned.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">stateful
+ * intermediate operation</a>.
+ *
+ * @param startInclusive the number of leading elements to skip
+ * @return the new stream
+ * @throws IllegalArgumentException if {@code startInclusive} is negative
+ */
+ LongStream substream(long startInclusive);
+
+ /**
+ * Returns a stream consisting of the remaining elements of this stream
+ * after indexing {@code startInclusive} elements into the stream and
+ * truncated to contain no more than {@code endExclusive - startInclusive}
+ * elements. If the {@code startInclusive} index lies past the end
+ * of this stream then an empty stream will be returned.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
+ * stateful intermediate operation</a>.
+ *
+ * @param startInclusive the starting position of the substream, inclusive
+ * @param endExclusive the ending position of the substream, exclusive
+ * @return the new stream
+ * @throws IllegalArgumentException if {@code startInclusive} or
+ * {@code endExclusive} is negative or {@code startInclusive} is greater
+ * than {@code endExclusive}
+ */
+ LongStream substream(long startInclusive, long endExclusive);
+
+ /**
+ * Performs an action for each element of this stream.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">terminal
+ * operation</a>.
+ *
+ * <p>For parallel stream pipelines, this operation does <em>not</em>
+ * guarantee to respect the encounter order of the stream, as doing so
+ * would sacrifice the benefit of parallelism. For any given element, the
+ * action may be performed at whatever time and in whatever thread the
+ * library chooses. If the action accesses shared state, it is
+ * responsible for providing the required synchronization.
+ *
+ * @param action a <a href="package-summary.html#NonInterference">
+ * non-interfering</a> action to perform on the elements
+ */
+ void forEach(LongConsumer action);
+
+ /**
+ * Performs an action for each element of this stream, guaranteeing that
+ * each element is processed in encounter order for streams that have a
+ * defined encounter order.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">terminal
+ * operation</a>.
+ *
+ * @param action a <a href="package-summary.html#NonInterference">
+ * non-interfering</a> action to perform on the elements
+ * @see #forEach(LongConsumer)
+ */
+ void forEachOrdered(LongConsumer action);
+
+ /**
+ * Returns an array containing the elements of this stream.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">terminal
+ * operation</a>.
+ *
+ * @return an array containing the elements of this stream
+ */
+ long[] toArray();
+
+ /**
+ * Performs a <a href="package-summary.html#Reduction">reduction</a> on the
+ * elements of this stream, using the provided identity value and an
+ * <a href="package-summary.html#Associativity">associative</a>
+ * accumulation function, and returns the reduced value. This is equivalent
+ * to:
+ * <pre>{@code
+ * long result = identity;
+ * for (long element : this stream)
+ * result = accumulator.apply(result, element)
+ * return result;
+ * }</pre>
+ *
+ * but is not constrained to execute sequentially.
+ *
+ * <p>The {@code identity} value must be an identity for the accumulator
+ * function. This means that for all {@code x},
+ * {@code accumulator.apply(identity, x)} is equal to {@code x}.
+ * The {@code accumulator} function must be an
+ * <a href="package-summary.html#Associativity">associative</a> function.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">terminal
+ * operation</a>.
+ *
+ * @apiNote Sum, min, max, and average are all special cases of reduction.
+ * Summing a stream of numbers can be expressed as:
+ *
+ * <pre>{@code
+ * long sum = integers.reduce(0, (a, b) -> a+b);
+ * }</pre>
+ *
+ * or more compactly:
+ *
+ * <pre>{@code
+ * long sum = integers.reduce(0, Long::sum);
+ * }</pre>
+ *
+ * <p>While this may seem a more roundabout way to perform an aggregation
+ * compared to simply mutating a running total in a loop, reduction
+ * operations parallelize more gracefully, without needing additional
+ * synchronization and with greatly reduced risk of data races.
+ *
+ * @param identity the identity value for the accumulating function
+ * @param op an <a href="package-summary.html#Associativity">associative</a>
+ * <a href="package-summary.html#NonInterference">non-interfering,
+ * stateless</a> function for combining two values
+ * @return the result of the reduction
+ * @see #sum()
+ * @see #min()
+ * @see #max()
+ * @see #average()
+ */
+ long reduce(long identity, LongBinaryOperator op);
+
+ /**
+ * Performs a <a href="package-summary.html#Reduction">reduction</a> on the
+ * elements of this stream, using an
+ * <a href="package-summary.html#Associativity">associative</a> accumulation
+ * function, and returns an {@code OptionalLong} describing the reduced value,
+ * if any. This is equivalent to:
+ * <pre>{@code
+ * boolean foundAny = false;
+ * long result = null;
+ * for (long element : this stream) {
+ * if (!foundAny) {
+ * foundAny = true;
+ * result = element;
+ * }
+ * else
+ * result = accumulator.apply(result, element);
+ * }
+ * return foundAny ? OptionalLong.of(result) : OptionalLong.empty();
+ * }</pre>
+ *
+ * but is not constrained to execute sequentially.
+ *
+ * <p>The {@code accumulator} function must be an
+ * <a href="package-summary.html#Associativity">associative</a> function.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">terminal
+ * operation</a>.
+ *
+ * @param op an <a href="package-summary.html#Associativity">associative</a>
+ * <a href="package-summary.html#NonInterference">non-interfering,
+ * stateless</a> function for combining two values
+ * @return the result of the reduction
+ * @see #reduce(long, LongBinaryOperator)
+ */
+ OptionalLong reduce(LongBinaryOperator op);
+
+ /**
+ * Performs a <a href="package-summary.html#MutableReduction">mutable
+ * reduction</a> operation on the elements of this stream. A mutable
+ * reduction is one in which the reduced value is a mutable value holder,
+ * such as an {@code ArrayList}, and elements are incorporated by updating
+ * the state of the result, rather than by replacing the result. This
+ * produces a result equivalent to:
+ * <pre>{@code
+ * R result = resultFactory.get();
+ * for (long element : this stream)
+ * accumulator.accept(result, element);
+ * return result;
+ * }</pre>
+ *
+ * <p>Like {@link #reduce(long, LongBinaryOperator)}, {@code collect} operations
+ * can be parallelized without requiring additional synchronization.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">terminal
+ * operation</a>.
+ *
+ * @param <R> type of the result
+ * @param resultFactory a function that creates a new result container.
+ * For a parallel execution, this function may be
+ * called multiple times and must return a fresh value
+ * each time.
+ * @param accumulator an <a href="package-summary.html#Associativity">associative</a>
+ * <a href="package-summary.html#NonInterference">non-interfering,
+ * stateless</a> function for incorporating an additional
+ * element into a result
+ * @param combiner an <a href="package-summary.html#Associativity">associative</a>
+ * <a href="package-summary.html#NonInterference">non-interfering,
+ * stateless</a> function for combining two values, which
+ * must be compatible with the accumulator function
+ * @return the result of the reduction
+ * @see Stream#collect(Supplier, BiConsumer, BiConsumer)
+ */
+ <R> R collect(Supplier<R> resultFactory,
+ ObjLongConsumer<R> accumulator,
+ BiConsumer<R, R> combiner);
+
+ /**
+ * Returns the sum of elements in this stream. This is a special case
+ * of a <a href="package-summary.html#MutableReduction">reduction</a>
+ * and is equivalent to:
+ * <pre>{@code
+ * return reduce(0, Long::sum);
+ * }</pre>
+ *
+ * @return the sum of elements in this stream
+ */
+ long sum();
+
+ /**
+ * Returns an {@code OptionalLong} describing the minimum element of this
+ * stream, or an empty optional if this stream is empty. This is a special
+ * case of a <a href="package-summary.html#MutableReduction">reduction</a>
+ * and is equivalent to:
+ * <pre>{@code
+ * return reduce(Long::min);
+ * }</pre>
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">terminal operation</a>.
+ *
+
+ * @return an {@code OptionalLong} containing the minimum element of this
+ * stream, or an empty {@code OptionalLong} if the stream is empty
+ */
+ OptionalLong min();
+
+ /**
+ * Returns an {@code OptionalLong} describing the maximum element of this
+ * stream, or an empty optional if this stream is empty. This is a special
+ * case of a <a href="package-summary.html#MutableReduction">reduction</a>
+ * and is equivalent to:
+ * <pre>{@code
+ * return reduce(Long::max);
+ * }</pre>
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">terminal
+ * operation</a>.
+ *
+ * @return an {@code OptionalLong} containing the maximum element of this
+ * stream, or an empty {@code OptionalLong} if the stream is empty
+ */
+ OptionalLong max();
+
+ /**
+ * Returns the count of elements in this stream. This is a special case of
+ * a <a href="package-summary.html#MutableReduction">reduction</a> and is
+ * equivalent to:
+ * <pre>{@code
+ * return map(e -> 1L).sum();
+ * }</pre>
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">terminal operation</a>.
+ *
+ * @return the count of elements in this stream
+ */
+ long count();
+
+ /**
+ * Returns an {@code OptionalDouble} describing the average of elements of
+ * this stream, or an empty optional if this stream is empty. This is a
+ * special case of a
+ * <a href="package-summary.html#MutableReduction">reduction</a>.
+ *
+ * @return an {@code OptionalDouble} containing the average element of this
+ * stream, or an empty optional if the stream is empty
+ */
+ OptionalDouble average();
+
+ /**
+ * Returns a {@code LongSummaryStatistics} describing various summary data
+ * about the elements of this stream. This is a special case of a
+ * <a href="package-summary.html#MutableReduction">reduction</a>.
+ *
+ * @return a {@code LongSummaryStatistics} describing various summary data
+ * about the elements of this stream
+ */
+ LongSummaryStatistics summaryStatistics();
+
+ /**
+ * Returns whether any elements of this stream match the provided
+ * predicate. May not evaluate the predicate on all elements if not
+ * necessary for determining the result.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
+ * terminal operation</a>.
+ *
+ * @param predicate a <a href="package-summary.html#NonInterference">non-interfering,
+ * stateless</a> predicate to apply to elements of this
+ * stream
+ * @return {@code true} if any elements of the stream match the provided
+ * predicate otherwise {@code false}
+ */
+ boolean anyMatch(LongPredicate predicate);
+
+ /**
+ * Returns whether all elements of this stream match the provided predicate.
+ * May not evaluate the predicate on all elements if not necessary for
+ * determining the result.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
+ * terminal operation</a>.
+ *
+ * @param predicate a <a href="package-summary.html#NonInterference">non-interfering,
+ * stateless</a> predicate to apply to elements of this
+ * stream
+ * @return {@code true} if all elements of the stream match the provided
+ * predicate otherwise {@code false}
+ */
+ boolean allMatch(LongPredicate predicate);
+
+ /**
+ * Returns whether no elements of this stream match the provided predicate.
+ * May not evaluate the predicate on all elements if not necessary for
+ * determining the result.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
+ * terminal operation</a>.
+ *
+ * @param predicate a <a href="package-summary.html#NonInterference">non-interfering,
+ * stateless</a> predicate to apply to elements of this
+ * stream
+ * @return {@code true} if no elements of the stream match the provided
+ * predicate otherwise {@code false}
+ */
+ boolean noneMatch(LongPredicate predicate);
+
+ /**
+ * Returns an {@link OptionalLong} describing the first element of this
+ * stream (in the encounter order), or an empty {@code OptionalLong} if the
+ * stream is empty. If the stream has no encounter order, than any element
+ * may be returned.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
+ * terminal operation</a>.
+ *
+ * @return an {@code OptionalLong} describing the first element of this
+ * stream, or an empty {@code OptionalLong} if the stream is empty
+ */
+ OptionalLong findFirst();
+
+ /**
+ * Returns an {@link OptionalLong} describing some element of the stream, or
+ * an empty {@code OptionalLong} if the stream is empty.
+ *
+ * <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
+ * terminal operation</a>.
+ *
+ * <p>The behavior of this operation is explicitly nondeterministic; it is
+ * free to select any element in the stream. This is to allow for maximal
+ * performance in parallel operations; the cost is that multiple invocations
+ * on the same source may not return the same result. (If the first element
+ * in the encounter order is desired, use {@link #findFirst()} instead.)
+ *
+ * @return an {@code OptionalLong} describing some element of this stream,
+ * or an empty {@code OptionalLong} if the stream is empty
+ * @see #findFirst()
+ */
+ OptionalLong findAny();
+
+ /**
+ * Returns a {@code DoubleStream} consisting of the elements of this stream,
+ * converted to {@code double}.
+ *
+ * @return a {@code DoubleStream} consisting of the elements of this stream,
+ * converted to {@code double}
+ */
+ DoubleStream doubles();
+
+ /**
+ * Returns a {@code Stream} consisting of the elements of this stream,
+ * each boxed to a {@code Long}.
+ *
+ * @return a {@code Stream} consistent of the elements of this stream,
+ * each boxed to {@code Long}
+ */
+ Stream<Long> boxed();
+
+ @Override
+ LongStream sequential();
+
+ @Override
+ LongStream parallel();
+
+ @Override
+ PrimitiveIterator.OfLong iterator();
+
+ @Override
+ Spliterator.OfLong spliterator();
+}