--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/util/stream/PipelineHelper.java Tue Apr 16 22:50:48 2013 -0400
@@ -0,0 +1,188 @@
+/*
+ * 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.Spliterator;
+import java.util.function.IntFunction;
+
+/**
+ * Helper class for executing <a href="package-summary.html#StreamPipelines">
+ * stream pipelines</a>, capturing all of the information about a stream
+ * pipeline (output shape, intermediate operations, stream flags, parallelism,
+ * etc) in one place.
+ *
+ * <p>
+ * A {@code PipelineHelper} describes the initial segment of a stream pipeline,
+ * including its source, intermediate operations, and may additionally
+ * incorporate information about the terminal (or stateful) operation which
+ * follows the last intermediate operation described by this
+ * {@code PipelineHelper}. The {@code PipelineHelper} is passed to the
+ * {@link TerminalOp#evaluateParallel(PipelineHelper, java.util.Spliterator)},
+ * {@link TerminalOp#evaluateSequential(PipelineHelper, java.util.Spliterator)},
+ * and {@link AbstractPipeline#opEvaluateParallel(PipelineHelper, java.util.Spliterator,
+ * java.util.function.IntFunction)}, methods, which can use the
+ * {@code PipelineHelper} to access information about the pipeline such as
+ * input shape, output shape, stream flags, and size, and use the helper methods
+ * such as {@link #wrapAndCopyInto(Sink, Spliterator)},
+ * {@link #copyInto(Sink, Spliterator)}, and {@link #wrapSink(Sink)} to execute
+ * pipeline operations.
+ *
+ * @param <P_OUT> type of output elements from the pipeline
+ * @since 1.8
+ */
+abstract class PipelineHelper<P_OUT> {
+
+ /**
+ * Gets the combined stream and operation flags for the output of the described
+ * pipeline. This will incorporate stream flags from the stream source, all
+ * the intermediate operations and the terminal operation.
+ *
+ * @return the combined stream and operation flags
+ * @see StreamOpFlag
+ */
+ abstract int getStreamAndOpFlags();
+
+ /**
+ * Returns the exact output size of the portion of the output resulting from
+ * applying the pipeline stages described by this {@code PipelineHelper} to
+ * the the portion of the input described by the provided
+ * {@code Spliterator}, if known. If not known or known infinite, will
+ * return {@code -1}.
+ *
+ * @apiNote
+ * The exact output size is known if the {@code Spliterator} has the
+ * {@code SIZED} characteristic, and the operation flags
+ * {@link StreamOpFlag#SIZED} is known on the combined stream and operation
+ * flags.
+ *
+ * @param spliterator the spliterator describing the relevant portion of the
+ * source data
+ * @return the exact size if known, or -1 if infinite or unknown
+ */
+ abstract<P_IN> long exactOutputSizeIfKnown(Spliterator<P_IN> spliterator);
+
+ /**
+ * Applies the pipeline stages described by this {@code PipelineHelper} to
+ * the provided {@code Spliterator} and send the results to the provided
+ * {@code Sink}.
+ *
+ * @implSpec
+ * The implementation behaves as if:
+ * <pre>{@code
+ * intoWrapped(wrapSink(sink), spliterator);
+ * }</pre>
+ *
+ * @param sink the {@code Sink} to receive the results
+ * @param spliterator the spliterator describing the source input to process
+ */
+ abstract<P_IN, S extends Sink<P_OUT>> S wrapAndCopyInto(S sink, Spliterator<P_IN> spliterator);
+
+ /**
+ * Pushes elements obtained from the {@code Spliterator} into the provided
+ * {@code Sink}. If the stream pipeline is known to have short-circuiting
+ * stages in it (see {@link StreamOpFlag#SHORT_CIRCUIT}), the
+ * {@link Sink#cancellationRequested()} is checked after each
+ * element, stopping if cancellation is requested.
+ *
+ * @implSpec
+ * This method conforms to the {@code Sink} protocol of calling
+ * {@code Sink.begin} before pushing elements, via {@code Sink.accept}, and
+ * calling {@code Sink.end} after all elements have been pushed.
+ *
+ * @param wrappedSink the destination {@code Sink}
+ * @param spliterator the source {@code Spliterator}
+ */
+ abstract<P_IN> void copyInto(Sink<P_IN> wrappedSink, Spliterator<P_IN> spliterator);
+
+ /**
+ * Pushes elements obtained from the {@code Spliterator} into the provided
+ * {@code Sink}, checking {@link Sink#cancellationRequested()} after each
+ * element, and stopping if cancellation is requested.
+ *
+ * @implSpec
+ * This method conforms to the {@code Sink} protocol of calling
+ * {@code Sink.begin} before pushing elements, via {@code Sink.accept}, and
+ * calling {@code Sink.end} after all elements have been pushed or if
+ * cancellation is requested.
+ *
+ * @param wrappedSink the destination {@code Sink}
+ * @param spliterator the source {@code Spliterator}
+ */
+ abstract <P_IN> void copyIntoWithCancel(Sink<P_IN> wrappedSink, Spliterator<P_IN> spliterator);
+
+ /**
+ * Takes a {@code Sink} that accepts elements of the output type of the
+ * {@code PipelineHelper}, and wrap it with a {@code Sink} that accepts
+ * elements of the input type and implements all the intermediate operations
+ * described by this {@code PipelineHelper}, delivering the result into the
+ * provided {@code Sink}.
+ *
+ * @param sink the {@code Sink} to receive the results
+ * @return a {@code Sink} that implements the pipeline stages and sends
+ * results to the provided {@code Sink}
+ */
+ abstract<P_IN> Sink<P_IN> wrapSink(Sink<P_OUT> sink);
+
+ /**
+ * Constructs a @{link Node.Builder} compatible with the output shape of
+ * this {@code PipelineHelper}.
+ *
+ * @param exactSizeIfKnown if >=0 then a builder will be created that has a
+ * fixed capacity of exactly sizeIfKnown elements; if < 0 then the
+ * builder has variable capacity. A fixed capacity builder will fail
+ * if an element is added after the builder has reached capacity.
+ * @param generator a factory function for array instances
+ * @return a {@code Node.Builder} compatible with the output shape of this
+ * {@code PipelineHelper}
+ */
+ abstract Node.Builder<P_OUT> makeNodeBuilder(long exactSizeIfKnown,
+ IntFunction<P_OUT[]> generator);
+
+ /**
+ * Collects all output elements resulting from applying the pipeline stages
+ * to the source {@code Spliterator} into a {@code Node}.
+ *
+ * @implNote
+ * If the pipeline has no intermediate operations and the source is backed
+ * by a {@code Node} then that {@code Node} will be returned (or flattened
+ * and then returned). This reduces copying for a pipeline consisting of a
+ * stateful operation followed by a terminal operation that returns an
+ * array, such as:
+ * <pre>{@code
+ * stream.sorted().toArray();
+ * }</pre>
+ *
+ * @param spliterator the source {@code Spliterator}
+ * @param flatten if true and the pipeline is a parallel pipeline then the
+ * {@code Node} returned will contain no children, otherwise the
+ * {@code Node} may represent the root in a tree that reflects the
+ * shape of the computation tree.
+ * @param generator a factory function for array instances
+ * @return the {@code Node} containing all output elements
+ */
+ abstract<P_IN> Node<P_OUT> evaluate(Spliterator<P_IN> spliterator,
+ boolean flatten,
+ IntFunction<P_OUT[]> generator);
+}