| /* |
| * 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.Objects; |
| import java.util.Spliterator; |
| import java.util.function.IntFunction; |
| import java.util.function.Supplier; |
| |
| /** |
| * Abstract base class for "pipeline" classes, which are the core |
| * implementations of the Stream interface and its primitive specializations. |
| * Manages construction and evaluation of stream pipelines. |
| * |
| * <p>An {@code AbstractPipeline} represents an initial portion of a stream |
| * pipeline, encapsulating a stream source and zero or more intermediate |
| * operations. The individual {@code AbstractPipeline} objects are often |
| * referred to as <em>stages</em>, where each stage describes either the stream |
| * source or an intermediate operation. |
| * |
| * <p>A concrete intermediate stage is generally built from an |
| * {@code AbstractPipeline}, a shape-specific pipeline class which extends it |
| * (e.g., {@code IntPipeline}) which is also abstract, and an operation-specific |
| * concrete class which extends that. {@code AbstractPipeline} contains most of |
| * the mechanics of evaluating the pipeline, and implements methods that will be |
| * used by the operation; the shape-specific classes add helper methods for |
| * dealing with collection of results into the appropriate shape-specific |
| * containers. |
| * |
| * <p>After chaining a new intermediate operation, or executing a terminal |
| * operation, the stream is considered to be consumed, and no more intermediate |
| * or terminal operations are permitted on this stream instance. |
| * |
| * @implNote |
| * <p>For sequential streams, and parallel streams without |
| * <a href="package-summary.html#StreamOps">stateful intermediate |
| * operations</a>, parallel streams, pipeline evaluation is done in a single |
| * pass that "jams" all the operations together. For parallel streams with |
| * stateful operations, execution is divided into segments, where each |
| * stateful operations marks the end of a segment, and each segment is |
| * evaluated separately and the result used as the input to the next |
| * segment. In all cases, the source data is not consumed until a terminal |
| * operation begins. |
| * |
| * @param <E_IN> type of input elements |
| * @param <E_OUT> type of output elements |
| * @param <S> type of the subclass implementing {@code BaseStream} |
| * @since 1.8 |
| * @hide Made public for CTS tests only (OpenJDK 8 streams tests). |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public abstract class AbstractPipeline<E_IN, E_OUT, S extends BaseStream<E_OUT, S>> |
| extends PipelineHelper<E_OUT> implements BaseStream<E_OUT, S> { |
| private static final String MSG_STREAM_LINKED = "stream has already been operated upon or closed"; |
| private static final String MSG_CONSUMED = "source already consumed or closed"; |
| |
| /** |
| * Backlink to the head of the pipeline chain (self if this is the source |
| * stage). |
| */ |
| @SuppressWarnings("rawtypes") |
| private final AbstractPipeline sourceStage; |
| |
| /** |
| * The "upstream" pipeline, or null if this is the source stage. |
| */ |
| @SuppressWarnings("rawtypes") |
| private final AbstractPipeline previousStage; |
| |
| /** |
| * The operation flags for the intermediate operation represented by this |
| * pipeline object. |
| */ |
| protected final int sourceOrOpFlags; |
| |
| /** |
| * The next stage in the pipeline, or null if this is the last stage. |
| * Effectively final at the point of linking to the next pipeline. |
| */ |
| @SuppressWarnings("rawtypes") |
| private AbstractPipeline nextStage; |
| |
| /** |
| * The number of intermediate operations between this pipeline object |
| * and the stream source if sequential, or the previous stateful if parallel. |
| * Valid at the point of pipeline preparation for evaluation. |
| */ |
| private int depth; |
| |
| /** |
| * The combined source and operation flags for the source and all operations |
| * up to and including the operation represented by this pipeline object. |
| * Valid at the point of pipeline preparation for evaluation. |
| */ |
| private int combinedFlags; |
| |
| /** |
| * The source spliterator. Only valid for the head pipeline. |
| * Before the pipeline is consumed if non-null then {@code sourceSupplier} |
| * must be null. After the pipeline is consumed if non-null then is set to |
| * null. |
| */ |
| private Spliterator<?> sourceSpliterator; |
| |
| /** |
| * The source supplier. Only valid for the head pipeline. Before the |
| * pipeline is consumed if non-null then {@code sourceSpliterator} must be |
| * null. After the pipeline is consumed if non-null then is set to null. |
| */ |
| private Supplier<? extends Spliterator<?>> sourceSupplier; |
| |
| /** |
| * True if this pipeline has been linked or consumed |
| */ |
| private boolean linkedOrConsumed; |
| |
| /** |
| * True if there are any stateful ops in the pipeline; only valid for the |
| * source stage. |
| */ |
| private boolean sourceAnyStateful; |
| |
| private Runnable sourceCloseAction; |
| |
| /** |
| * True if pipeline is parallel, otherwise the pipeline is sequential; only |
| * valid for the source stage. |
| */ |
| private boolean parallel; |
| |
| /** |
| * Constructor for the head of a stream pipeline. |
| * |
| * @param source {@code Supplier<Spliterator>} describing the stream source |
| * @param sourceFlags The source flags for the stream source, described in |
| * {@link StreamOpFlag} |
| * @param parallel True if the pipeline is parallel |
| */ |
| AbstractPipeline(Supplier<? extends Spliterator<?>> source, |
| int sourceFlags, boolean parallel) { |
| this.previousStage = null; |
| this.sourceSupplier = source; |
| this.sourceStage = this; |
| this.sourceOrOpFlags = sourceFlags & StreamOpFlag.STREAM_MASK; |
| // The following is an optimization of: |
| // StreamOpFlag.combineOpFlags(sourceOrOpFlags, StreamOpFlag.INITIAL_OPS_VALUE); |
| this.combinedFlags = (~(sourceOrOpFlags << 1)) & StreamOpFlag.INITIAL_OPS_VALUE; |
| this.depth = 0; |
| this.parallel = parallel; |
| } |
| |
| /** |
| * Constructor for the head of a stream pipeline. |
| * |
| * @param source {@code Spliterator} describing the stream source |
| * @param sourceFlags the source flags for the stream source, described in |
| * {@link StreamOpFlag} |
| * @param parallel {@code true} if the pipeline is parallel |
| */ |
| AbstractPipeline(Spliterator<?> source, |
| int sourceFlags, boolean parallel) { |
| this.previousStage = null; |
| this.sourceSpliterator = source; |
| this.sourceStage = this; |
| this.sourceOrOpFlags = sourceFlags & StreamOpFlag.STREAM_MASK; |
| // The following is an optimization of: |
| // StreamOpFlag.combineOpFlags(sourceOrOpFlags, StreamOpFlag.INITIAL_OPS_VALUE); |
| this.combinedFlags = (~(sourceOrOpFlags << 1)) & StreamOpFlag.INITIAL_OPS_VALUE; |
| this.depth = 0; |
| this.parallel = parallel; |
| } |
| |
| /** |
| * Constructor for appending an intermediate operation stage onto an |
| * existing pipeline. |
| * |
| * @param previousStage the upstream pipeline stage |
| * @param opFlags the operation flags for the new stage, described in |
| * {@link StreamOpFlag} |
| */ |
| AbstractPipeline(AbstractPipeline<?, E_IN, ?> previousStage, int opFlags) { |
| if (previousStage.linkedOrConsumed) |
| throw new IllegalStateException(MSG_STREAM_LINKED); |
| previousStage.linkedOrConsumed = true; |
| previousStage.nextStage = this; |
| |
| this.previousStage = previousStage; |
| this.sourceOrOpFlags = opFlags & StreamOpFlag.OP_MASK; |
| this.combinedFlags = StreamOpFlag.combineOpFlags(opFlags, previousStage.combinedFlags); |
| this.sourceStage = previousStage.sourceStage; |
| if (opIsStateful()) |
| sourceStage.sourceAnyStateful = true; |
| this.depth = previousStage.depth + 1; |
| } |
| |
| |
| // Terminal evaluation methods |
| |
| /** |
| * Evaluate the pipeline with a terminal operation to produce a result. |
| * |
| * @param <R> the type of result |
| * @param terminalOp the terminal operation to be applied to the pipeline. |
| * @return the result |
| */ |
| final <R> R evaluate(TerminalOp<E_OUT, R> terminalOp) { |
| assert getOutputShape() == terminalOp.inputShape(); |
| if (linkedOrConsumed) |
| throw new IllegalStateException(MSG_STREAM_LINKED); |
| linkedOrConsumed = true; |
| |
| return isParallel() |
| ? terminalOp.evaluateParallel(this, sourceSpliterator(terminalOp.getOpFlags())) |
| : terminalOp.evaluateSequential(this, sourceSpliterator(terminalOp.getOpFlags())); |
| } |
| |
| /** |
| * Collect the elements output from the pipeline stage. |
| * |
| * @param generator the array generator to be used to create array instances |
| * @return a flat array-backed Node that holds the collected output elements |
| */ |
| @SuppressWarnings("unchecked") |
| // Android-changed: Made public for CTS tests only. |
| public final Node<E_OUT> evaluateToArrayNode(IntFunction<E_OUT[]> generator) { |
| if (linkedOrConsumed) |
| throw new IllegalStateException(MSG_STREAM_LINKED); |
| linkedOrConsumed = true; |
| |
| // If the last intermediate operation is stateful then |
| // evaluate directly to avoid an extra collection step |
| if (isParallel() && previousStage != null && opIsStateful()) { |
| // Set the depth of this, last, pipeline stage to zero to slice the |
| // pipeline such that this operation will not be included in the |
| // upstream slice and upstream operations will not be included |
| // in this slice |
| depth = 0; |
| return opEvaluateParallel(previousStage, previousStage.sourceSpliterator(0), generator); |
| } |
| else { |
| return evaluate(sourceSpliterator(0), true, generator); |
| } |
| } |
| |
| /** |
| * Gets the source stage spliterator if this pipeline stage is the source |
| * stage. The pipeline is consumed after this method is called and |
| * returns successfully. |
| * |
| * @return the source stage spliterator |
| * @throws IllegalStateException if this pipeline stage is not the source |
| * stage. |
| */ |
| @SuppressWarnings("unchecked") |
| final Spliterator<E_OUT> sourceStageSpliterator() { |
| if (this != sourceStage) |
| throw new IllegalStateException(); |
| |
| if (linkedOrConsumed) |
| throw new IllegalStateException(MSG_STREAM_LINKED); |
| linkedOrConsumed = true; |
| |
| if (sourceStage.sourceSpliterator != null) { |
| @SuppressWarnings("unchecked") |
| Spliterator<E_OUT> s = sourceStage.sourceSpliterator; |
| sourceStage.sourceSpliterator = null; |
| return s; |
| } |
| else if (sourceStage.sourceSupplier != null) { |
| @SuppressWarnings("unchecked") |
| Spliterator<E_OUT> s = (Spliterator<E_OUT>) sourceStage.sourceSupplier.get(); |
| sourceStage.sourceSupplier = null; |
| return s; |
| } |
| else { |
| throw new IllegalStateException(MSG_CONSUMED); |
| } |
| } |
| |
| // BaseStream |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| public final S sequential() { |
| sourceStage.parallel = false; |
| return (S) this; |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| public final S parallel() { |
| sourceStage.parallel = true; |
| return (S) this; |
| } |
| |
| @Override |
| public void close() { |
| linkedOrConsumed = true; |
| sourceSupplier = null; |
| sourceSpliterator = null; |
| if (sourceStage.sourceCloseAction != null) { |
| Runnable closeAction = sourceStage.sourceCloseAction; |
| sourceStage.sourceCloseAction = null; |
| closeAction.run(); |
| } |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| public S onClose(Runnable closeHandler) { |
| Runnable existingHandler = sourceStage.sourceCloseAction; |
| sourceStage.sourceCloseAction = |
| (existingHandler == null) |
| ? closeHandler |
| : Streams.composeWithExceptions(existingHandler, closeHandler); |
| return (S) this; |
| } |
| |
| // Primitive specialization use co-variant overrides, hence is not final |
| @Override |
| @SuppressWarnings("unchecked") |
| public Spliterator<E_OUT> spliterator() { |
| if (linkedOrConsumed) |
| throw new IllegalStateException(MSG_STREAM_LINKED); |
| linkedOrConsumed = true; |
| |
| if (this == sourceStage) { |
| if (sourceStage.sourceSpliterator != null) { |
| @SuppressWarnings("unchecked") |
| Spliterator<E_OUT> s = (Spliterator<E_OUT>) sourceStage.sourceSpliterator; |
| sourceStage.sourceSpliterator = null; |
| return s; |
| } |
| else if (sourceStage.sourceSupplier != null) { |
| @SuppressWarnings("unchecked") |
| Supplier<Spliterator<E_OUT>> s = (Supplier<Spliterator<E_OUT>>) sourceStage.sourceSupplier; |
| sourceStage.sourceSupplier = null; |
| return lazySpliterator(s); |
| } |
| else { |
| throw new IllegalStateException(MSG_CONSUMED); |
| } |
| } |
| else { |
| return wrap(this, () -> sourceSpliterator(0), isParallel()); |
| } |
| } |
| |
| @Override |
| public final boolean isParallel() { |
| return sourceStage.parallel; |
| } |
| |
| |
| /** |
| * Returns the composition of stream flags of the stream source and all |
| * intermediate operations. |
| * |
| * @return the composition of stream flags of the stream source and all |
| * intermediate operations |
| * @see StreamOpFlag |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public final int getStreamFlags() { |
| return StreamOpFlag.toStreamFlags(combinedFlags); |
| } |
| |
| /** |
| * Get the source spliterator for this pipeline stage. For a sequential or |
| * stateless parallel pipeline, this is the source spliterator. For a |
| * stateful parallel pipeline, this is a spliterator describing the results |
| * of all computations up to and including the most recent stateful |
| * operation. |
| */ |
| @SuppressWarnings("unchecked") |
| private Spliterator<?> sourceSpliterator(int terminalFlags) { |
| // Get the source spliterator of the pipeline |
| Spliterator<?> spliterator = null; |
| if (sourceStage.sourceSpliterator != null) { |
| spliterator = sourceStage.sourceSpliterator; |
| sourceStage.sourceSpliterator = null; |
| } |
| else if (sourceStage.sourceSupplier != null) { |
| spliterator = (Spliterator<?>) sourceStage.sourceSupplier.get(); |
| sourceStage.sourceSupplier = null; |
| } |
| else { |
| throw new IllegalStateException(MSG_CONSUMED); |
| } |
| |
| if (isParallel() && sourceStage.sourceAnyStateful) { |
| // Adapt the source spliterator, evaluating each stateful op |
| // in the pipeline up to and including this pipeline stage. |
| // The depth and flags of each pipeline stage are adjusted accordingly. |
| int depth = 1; |
| for (@SuppressWarnings("rawtypes") AbstractPipeline u = sourceStage, p = sourceStage.nextStage, e = this; |
| u != e; |
| u = p, p = p.nextStage) { |
| |
| int thisOpFlags = p.sourceOrOpFlags; |
| if (p.opIsStateful()) { |
| depth = 0; |
| |
| if (StreamOpFlag.SHORT_CIRCUIT.isKnown(thisOpFlags)) { |
| // Clear the short circuit flag for next pipeline stage |
| // This stage encapsulates short-circuiting, the next |
| // stage may not have any short-circuit operations, and |
| // if so spliterator.forEachRemaining should be used |
| // for traversal |
| thisOpFlags = thisOpFlags & ~StreamOpFlag.IS_SHORT_CIRCUIT; |
| } |
| |
| spliterator = p.opEvaluateParallelLazy(u, spliterator); |
| |
| // Inject or clear SIZED on the source pipeline stage |
| // based on the stage's spliterator |
| thisOpFlags = spliterator.hasCharacteristics(Spliterator.SIZED) |
| ? (thisOpFlags & ~StreamOpFlag.NOT_SIZED) | StreamOpFlag.IS_SIZED |
| : (thisOpFlags & ~StreamOpFlag.IS_SIZED) | StreamOpFlag.NOT_SIZED; |
| } |
| p.depth = depth++; |
| p.combinedFlags = StreamOpFlag.combineOpFlags(thisOpFlags, u.combinedFlags); |
| } |
| } |
| |
| if (terminalFlags != 0) { |
| // Apply flags from the terminal operation to last pipeline stage |
| combinedFlags = StreamOpFlag.combineOpFlags(terminalFlags, combinedFlags); |
| } |
| |
| return spliterator; |
| } |
| |
| // PipelineHelper |
| |
| @Override |
| final StreamShape getSourceShape() { |
| @SuppressWarnings("rawtypes") |
| AbstractPipeline p = AbstractPipeline.this; |
| while (p.depth > 0) { |
| p = p.previousStage; |
| } |
| return p.getOutputShape(); |
| } |
| |
| @Override |
| final <P_IN> long exactOutputSizeIfKnown(Spliterator<P_IN> spliterator) { |
| return StreamOpFlag.SIZED.isKnown(getStreamAndOpFlags()) ? spliterator.getExactSizeIfKnown() : -1; |
| } |
| |
| @Override |
| final <P_IN, S extends Sink<E_OUT>> S wrapAndCopyInto(S sink, Spliterator<P_IN> spliterator) { |
| copyInto(wrapSink(Objects.requireNonNull(sink)), spliterator); |
| return sink; |
| } |
| |
| @Override |
| final <P_IN> void copyInto(Sink<P_IN> wrappedSink, Spliterator<P_IN> spliterator) { |
| Objects.requireNonNull(wrappedSink); |
| |
| if (!StreamOpFlag.SHORT_CIRCUIT.isKnown(getStreamAndOpFlags())) { |
| wrappedSink.begin(spliterator.getExactSizeIfKnown()); |
| spliterator.forEachRemaining(wrappedSink); |
| wrappedSink.end(); |
| } |
| else { |
| copyIntoWithCancel(wrappedSink, spliterator); |
| } |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| final <P_IN> void copyIntoWithCancel(Sink<P_IN> wrappedSink, Spliterator<P_IN> spliterator) { |
| @SuppressWarnings({"rawtypes","unchecked"}) |
| AbstractPipeline p = AbstractPipeline.this; |
| while (p.depth > 0) { |
| p = p.previousStage; |
| } |
| wrappedSink.begin(spliterator.getExactSizeIfKnown()); |
| p.forEachWithCancel(spliterator, wrappedSink); |
| wrappedSink.end(); |
| } |
| |
| @Override |
| // Android-changed: Made public for CTS tests only. |
| public final int getStreamAndOpFlags() { |
| return combinedFlags; |
| } |
| |
| final boolean isOrdered() { |
| return StreamOpFlag.ORDERED.isKnown(combinedFlags); |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| // Android-changed: Made public for CTS tests only. |
| public final <P_IN> Sink<P_IN> wrapSink(Sink<E_OUT> sink) { |
| Objects.requireNonNull(sink); |
| |
| for ( @SuppressWarnings("rawtypes") AbstractPipeline p=AbstractPipeline.this; p.depth > 0; p=p.previousStage) { |
| sink = p.opWrapSink(p.previousStage.combinedFlags, sink); |
| } |
| return (Sink<P_IN>) sink; |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| final <P_IN> Spliterator<E_OUT> wrapSpliterator(Spliterator<P_IN> sourceSpliterator) { |
| if (depth == 0) { |
| return (Spliterator<E_OUT>) sourceSpliterator; |
| } |
| else { |
| return wrap(this, () -> sourceSpliterator, isParallel()); |
| } |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| // Android-changed: Made public for CTS tests only. |
| public final <P_IN> Node<E_OUT> evaluate(Spliterator<P_IN> spliterator, |
| boolean flatten, |
| IntFunction<E_OUT[]> generator) { |
| if (isParallel()) { |
| // @@@ Optimize if op of this pipeline stage is a stateful op |
| return evaluateToNode(this, spliterator, flatten, generator); |
| } |
| else { |
| Node.Builder<E_OUT> nb = makeNodeBuilder( |
| exactOutputSizeIfKnown(spliterator), generator); |
| return wrapAndCopyInto(nb, spliterator).build(); |
| } |
| } |
| |
| |
| // Shape-specific abstract methods, implemented by XxxPipeline classes |
| |
| /** |
| * Get the output shape of the pipeline. If the pipeline is the head, |
| * then it's output shape corresponds to the shape of the source. |
| * Otherwise, it's output shape corresponds to the output shape of the |
| * associated operation. |
| * |
| * @return the output shape |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public abstract StreamShape getOutputShape(); |
| |
| /** |
| * Collect elements output from a pipeline into a Node that holds elements |
| * of this shape. |
| * |
| * @param helper the pipeline helper describing the pipeline stages |
| * @param spliterator the source spliterator |
| * @param flattenTree true if the returned node should be flattened |
| * @param generator the array generator |
| * @return a Node holding the output of the pipeline |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public abstract <P_IN> Node<E_OUT> evaluateToNode(PipelineHelper<E_OUT> helper, |
| Spliterator<P_IN> spliterator, |
| boolean flattenTree, |
| IntFunction<E_OUT[]> generator); |
| |
| /** |
| * Create a spliterator that wraps a source spliterator, compatible with |
| * this stream shape, and operations associated with a {@link |
| * PipelineHelper}. |
| * |
| * @param ph the pipeline helper describing the pipeline stages |
| * @param supplier the supplier of a spliterator |
| * @return a wrapping spliterator compatible with this shape |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public abstract <P_IN> Spliterator<E_OUT> wrap(PipelineHelper<E_OUT> ph, |
| Supplier<Spliterator<P_IN>> supplier, |
| boolean isParallel); |
| |
| /** |
| * Create a lazy spliterator that wraps and obtains the supplied the |
| * spliterator when a method is invoked on the lazy spliterator. |
| * @param supplier the supplier of a spliterator |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public abstract Spliterator<E_OUT> lazySpliterator(Supplier<? extends Spliterator<E_OUT>> supplier); |
| |
| /** |
| * Traverse the elements of a spliterator compatible with this stream shape, |
| * pushing those elements into a sink. If the sink requests cancellation, |
| * no further elements will be pulled or pushed. |
| * |
| * @param spliterator the spliterator to pull elements from |
| * @param sink the sink to push elements to |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public abstract void forEachWithCancel(Spliterator<E_OUT> spliterator, Sink<E_OUT> sink); |
| |
| /** |
| * Make a node builder compatible with this stream shape. |
| * |
| * @param exactSizeIfKnown if {@literal >=0}, then a node builder will be |
| * created that has a fixed capacity of at most sizeIfKnown elements. If |
| * {@literal < 0}, then the node builder has an unfixed capacity. A fixed |
| * capacity node builder will throw exceptions if an element is added after |
| * builder has reached capacity, or is built before the builder has reached |
| * capacity. |
| * |
| * @param generator the array generator to be used to create instances of a |
| * T[] array. For implementations supporting primitive nodes, this parameter |
| * may be ignored. |
| * @return a node builder |
| */ |
| @Override |
| // Android-changed: Made public for CTS tests only. |
| public abstract Node.Builder<E_OUT> makeNodeBuilder(long exactSizeIfKnown, |
| IntFunction<E_OUT[]> generator); |
| |
| |
| // Op-specific abstract methods, implemented by the operation class |
| |
| /** |
| * Returns whether this operation is stateful or not. If it is stateful, |
| * then the method |
| * {@link #opEvaluateParallel(PipelineHelper, java.util.Spliterator, java.util.function.IntFunction)} |
| * must be overridden. |
| * |
| * @return {@code true} if this operation is stateful |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public abstract boolean opIsStateful(); |
| |
| /** |
| * Accepts a {@code Sink} which will receive the results of this operation, |
| * and return a {@code Sink} which accepts elements of the input type of |
| * this operation and which performs the operation, passing the results to |
| * the provided {@code Sink}. |
| * |
| * @apiNote |
| * The implementation may use the {@code flags} parameter to optimize the |
| * sink wrapping. For example, if the input is already {@code DISTINCT}, |
| * the implementation for the {@code Stream#distinct()} method could just |
| * return the sink it was passed. |
| * |
| * @param flags The combined stream and operation flags up to, but not |
| * including, this operation |
| * @param sink sink to which elements should be sent after processing |
| * @return a sink which accepts elements, perform the operation upon |
| * each element, and passes the results (if any) to the provided |
| * {@code Sink}. |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public abstract Sink<E_IN> opWrapSink(int flags, Sink<E_OUT> sink); |
| |
| /** |
| * Performs a parallel evaluation of the operation using the specified |
| * {@code PipelineHelper} which describes the upstream intermediate |
| * operations. Only called on stateful operations. If {@link |
| * #opIsStateful()} returns true then implementations must override the |
| * default implementation. |
| * |
| * @implSpec The default implementation always throw |
| * {@code UnsupportedOperationException}. |
| * |
| * @param helper the pipeline helper describing the pipeline stages |
| * @param spliterator the source {@code Spliterator} |
| * @param generator the array generator |
| * @return a {@code Node} describing the result of the evaluation |
| */ |
| // Android-changed: Made public for CTS tests only. |
| public <P_IN> Node<E_OUT> opEvaluateParallel(PipelineHelper<E_OUT> helper, |
| Spliterator<P_IN> spliterator, |
| IntFunction<E_OUT[]> generator) { |
| throw new UnsupportedOperationException("Parallel evaluation is not supported"); |
| } |
| |
| /** |
| * Returns a {@code Spliterator} describing a parallel evaluation of the |
| * operation, using the specified {@code PipelineHelper} which describes the |
| * upstream intermediate operations. Only called on stateful operations. |
| * It is not necessary (though acceptable) to do a full computation of the |
| * result here; it is preferable, if possible, to describe the result via a |
| * lazily evaluated spliterator. |
| * |
| * @implSpec The default implementation behaves as if: |
| * <pre>{@code |
| * return evaluateParallel(helper, i -> (E_OUT[]) new |
| * Object[i]).spliterator(); |
| * }</pre> |
| * and is suitable for implementations that cannot do better than a full |
| * synchronous evaluation. |
| * |
| * @param helper the pipeline helper |
| * @param spliterator the source {@code Spliterator} |
| * @return a {@code Spliterator} describing the result of the evaluation |
| */ |
| @SuppressWarnings("unchecked") |
| // Android-changed: Made public for CTS tests only. |
| public <P_IN> Spliterator<E_OUT> opEvaluateParallelLazy(PipelineHelper<E_OUT> helper, |
| Spliterator<P_IN> spliterator) { |
| return opEvaluateParallel(helper, spliterator, i -> (E_OUT[]) new Object[i]).spliterator(); |
| } |
| } |
