/* |
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* Copyright (c) 2012, 2017, 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.util.EnumMap; |
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import java.util.Map; |
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import java.util.Spliterator; |
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/** |
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* Flags corresponding to characteristics of streams and operations. Flags are |
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* utilized by the stream framework to control, specialize or optimize |
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* computation. |
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* |
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* <p> |
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* Stream flags may be used to describe characteristics of several different |
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* entities associated with streams: stream sources, intermediate operations, |
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* and terminal operations. Not all stream flags are meaningful for all |
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* entities; the following table summarizes which flags are meaningful in what |
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* contexts: |
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* |
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* <div> |
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* <table class="borderless"> |
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* <caption>Type Characteristics</caption> |
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* <thead class="tableSubHeadingColor"> |
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* <tr> |
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* <th colspan="2"> </th> |
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* <th>{@code DISTINCT}</th> |
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* <th>{@code SORTED}</th> |
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* <th>{@code ORDERED}</th> |
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* <th>{@code SIZED}</th> |
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* <th>{@code SHORT_CIRCUIT}</th> |
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* </tr> |
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* </thead> |
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* <tbody> |
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* <tr> |
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* <th colspan="2" class="tableSubHeadingColor">Stream source</th> |
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* <td>Y</td> |
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* <td>Y</td> |
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* <td>Y</td> |
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* <td>Y</td> |
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* <td>N</td> |
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* </tr> |
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* <tr> |
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* <th colspan="2" class="tableSubHeadingColor">Intermediate operation</th> |
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* <td>PCI</td> |
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* <td>PCI</td> |
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* <td>PCI</td> |
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* <td>PC</td> |
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* <td>PI</td> |
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* </tr> |
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* <tr> |
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* <th colspan="2" class="tableSubHeadingColor">Terminal operation</th> |
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* <td>N</td> |
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* <td>N</td> |
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* <td>PC</td> |
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* <td>N</td> |
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* <td>PI</td> |
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* </tr> |
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* </tbody> |
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* <tfoot> |
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* <tr> |
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* <th class="tableSubHeadingColor" colspan="2">Legend</th> |
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* <th colspan="6" rowspan="7"> </th> |
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* </tr> |
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* <tr> |
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* <th class="tableSubHeadingColor">Flag</th> |
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* <th class="tableSubHeadingColor">Meaning</th> |
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* <th colspan="6"></th> |
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* </tr> |
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* <tr><td>Y</td><td>Allowed</td></tr> |
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* <tr><td>N</td><td>Invalid</td></tr> |
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* <tr><td>P</td><td>Preserves</td></tr> |
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* <tr><td>C</td><td>Clears</td></tr> |
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* <tr><td>I</td><td>Injects</td></tr> |
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* </tfoot> |
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* </table> |
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* </div> |
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* |
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* <p>In the above table, "PCI" means "may preserve, clear, or inject"; "PC" |
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* means "may preserve or clear", "PI" means "may preserve or inject", and "N" |
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* means "not valid". |
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* |
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* <p>Stream flags are represented by unioned bit sets, so that a single word |
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* may describe all the characteristics of a given stream entity, and that, for |
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* example, the flags for a stream source can be efficiently combined with the |
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* flags for later operations on that stream. |
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* |
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* <p>The bit masks {@link #STREAM_MASK}, {@link #OP_MASK}, and |
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* {@link #TERMINAL_OP_MASK} can be ANDed with a bit set of stream flags to |
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* produce a mask containing only the valid flags for that entity type. |
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* |
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* <p>When describing a stream source, one only need describe what |
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* characteristics that stream has; when describing a stream operation, one need |
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* describe whether the operation preserves, injects, or clears that |
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* characteristic. Accordingly, two bits are used for each flag, so as to allow |
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* representing not only the presence of a characteristic, but how an |
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* operation modifies that characteristic. There are two common forms in which |
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* flag bits are combined into an {@code int} bit set. <em>Stream flags</em> |
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* are a unioned bit set constructed by ORing the enum characteristic values of |
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* {@link #set()} (or, more commonly, ORing the corresponding static named |
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* constants prefixed with {@code IS_}). <em>Operation flags</em> are a unioned |
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* bit set constructed by ORing the enum characteristic values of {@link #set()} |
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* or {@link #clear()} (to inject, or clear, respectively, the corresponding |
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* flag), or more commonly ORing the corresponding named constants prefixed with |
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* {@code IS_} or {@code NOT_}. Flags that are not marked with {@code IS_} or |
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* {@code NOT_} are implicitly treated as preserved. Care must be taken when |
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* combining bitsets that the correct combining operations are applied in the |
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* correct order. |
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* |
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* <p> |
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* With the exception of {@link #SHORT_CIRCUIT}, stream characteristics can be |
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* derived from the equivalent {@link java.util.Spliterator} characteristics: |
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* {@link java.util.Spliterator#DISTINCT}, {@link java.util.Spliterator#SORTED}, |
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* {@link java.util.Spliterator#ORDERED}, and |
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* {@link java.util.Spliterator#SIZED}. A spliterator characteristics bit set |
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* can be converted to stream flags using the method |
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* {@link #fromCharacteristics(java.util.Spliterator)} and converted back using |
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* {@link #toCharacteristics(int)}. (The bit set |
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* {@link #SPLITERATOR_CHARACTERISTICS_MASK} is used to AND with a bit set to |
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* produce a valid spliterator characteristics bit set that can be converted to |
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* stream flags.) |
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* |
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* <p> |
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* The source of a stream encapsulates a spliterator. The characteristics of |
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* that source spliterator when transformed to stream flags will be a proper |
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* subset of stream flags of that stream. |
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* For example: |
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* <pre> {@code |
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* Spliterator s = ...; |
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* Stream stream = Streams.stream(s); |
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* flagsFromSplitr = fromCharacteristics(s.characteristics()); |
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* assert(flagsFromSplitr & stream.getStreamFlags() == flagsFromSplitr); |
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* }</pre> |
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* |
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* <p> |
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* An intermediate operation, performed on an input stream to create a new |
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* output stream, may preserve, clear or inject stream or operation |
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* characteristics. Similarly, a terminal operation, performed on an input |
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* stream to produce an output result may preserve, clear or inject stream or |
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* operation characteristics. Preservation means that if that characteristic |
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* is present on the input, then it is also present on the output. Clearing |
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* means that the characteristic is not present on the output regardless of the |
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* input. Injection means that the characteristic is present on the output |
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* regardless of the input. If a characteristic is not cleared or injected then |
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* it is implicitly preserved. |
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* |
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* <p> |
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* A pipeline consists of a stream source encapsulating a spliterator, one or |
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* more intermediate operations, and finally a terminal operation that produces |
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* a result. At each stage of the pipeline, a combined stream and operation |
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* flags can be calculated, using {@link #combineOpFlags(int, int)}. Such flags |
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* ensure that preservation, clearing and injecting information is retained at |
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* each stage. |
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* |
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* The combined stream and operation flags for the source stage of the pipeline |
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* is calculated as follows: |
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* <pre> {@code |
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* int flagsForSourceStage = combineOpFlags(sourceFlags, INITIAL_OPS_VALUE); |
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* }</pre> |
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* |
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* The combined stream and operation flags of each subsequent intermediate |
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* operation stage in the pipeline is calculated as follows: |
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* <pre> {@code |
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* int flagsForThisStage = combineOpFlags(flagsForPreviousStage, thisOpFlags); |
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* }</pre> |
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* |
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* Finally the flags output from the last intermediate operation of the pipeline |
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* are combined with the operation flags of the terminal operation to produce |
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* the flags output from the pipeline. |
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* |
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* <p>Those flags can then be used to apply optimizations. For example, if |
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* {@code SIZED.isKnown(flags)} returns true then the stream size remains |
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* constant throughout the pipeline, this information can be utilized to |
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* pre-allocate data structures and combined with |
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* {@link java.util.Spliterator#SUBSIZED} that information can be utilized to |
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* perform concurrent in-place updates into a shared array. |
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* |
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* For specific details see the {@link AbstractPipeline} constructors. |
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* |
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* @since 1.8 |
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*/ |
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enum StreamOpFlag { |
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/* |
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* Each characteristic takes up 2 bits in a bit set to accommodate |
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* preserving, clearing and setting/injecting information. |
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* |
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* This applies to stream flags, intermediate/terminal operation flags, and |
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* combined stream and operation flags. Even though the former only requires |
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* 1 bit of information per characteristic, is it more efficient when |
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* combining flags to align set and inject bits. |
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* |
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* Characteristics belong to certain types, see the Type enum. Bit masks for |
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* the types are constructed as per the following table: |
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* |
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* DISTINCT SORTED ORDERED SIZED SHORT_CIRCUIT |
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* SPLITERATOR 01 01 01 01 00 |
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* STREAM 01 01 01 01 00 |
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* OP 11 11 11 10 01 |
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* TERMINAL_OP 00 00 10 00 01 |
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* UPSTREAM_TERMINAL_OP 00 00 10 00 00 |
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* |
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* 01 = set/inject |
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* 10 = clear |
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* 11 = preserve |
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* |
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* Construction of the columns is performed using a simple builder for |
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* non-zero values. |
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*/ |
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// The following flags correspond to characteristics on Spliterator |
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// and the values MUST be equal. |
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// |
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/** |
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* Characteristic value signifying that, for each pair of |
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* encountered elements in a stream {@code x, y}, {@code !x.equals(y)}. |
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* <p> |
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* A stream may have this value or an intermediate operation can preserve, |
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* clear or inject this value. |
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*/ |
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// 0, 0x00000001 |
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// Matches Spliterator.DISTINCT |
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DISTINCT(0, |
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set(Type.SPLITERATOR).set(Type.STREAM).setAndClear(Type.OP)), |
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/** |
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* Characteristic value signifying that encounter order follows a natural |
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* sort order of comparable elements. |
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* <p> |
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* A stream can have this value or an intermediate operation can preserve, |
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* clear or inject this value. |
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* <p> |
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* Note: The {@link java.util.Spliterator#SORTED} characteristic can define |
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* a sort order with an associated non-null comparator. Augmenting flag |
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* state with addition properties such that those properties can be passed |
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* to operations requires some disruptive changes for a singular use-case. |
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* Furthermore, comparing comparators for equality beyond that of identity |
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* is likely to be unreliable. Therefore the {@code SORTED} characteristic |
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* for a defined non-natural sort order is not mapped internally to the |
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* {@code SORTED} flag. |
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*/ |
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// 1, 0x00000004 |
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// Matches Spliterator.SORTED |
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SORTED(1, |
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set(Type.SPLITERATOR).set(Type.STREAM).setAndClear(Type.OP)), |
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/** |
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* Characteristic value signifying that an encounter order is |
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* defined for stream elements. |
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* <p> |
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* A stream can have this value, an intermediate operation can preserve, |
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* clear or inject this value, or a terminal operation can preserve or clear |
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* this value. |
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*/ |
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// 2, 0x00000010 |
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// Matches Spliterator.ORDERED |
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ORDERED(2, |
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set(Type.SPLITERATOR).set(Type.STREAM).setAndClear(Type.OP).clear(Type.TERMINAL_OP) |
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.clear(Type.UPSTREAM_TERMINAL_OP)), |
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/** |
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* Characteristic value signifying that size of the stream |
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* is of a known finite size that is equal to the known finite |
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* size of the source spliterator input to the first stream |
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* in the pipeline. |
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* <p> |
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* A stream can have this value or an intermediate operation can preserve or |
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* clear this value. |
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*/ |
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// 3, 0x00000040 |
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// Matches Spliterator.SIZED |
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SIZED(3, |
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set(Type.SPLITERATOR).set(Type.STREAM).clear(Type.OP)), |
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// The following Spliterator characteristics are not currently used but a |
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// gap in the bit set is deliberately retained to enable corresponding |
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// stream flags if//when required without modification to other flag values. |
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// |
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// 4, 0x00000100 NONNULL(4, ... |
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// 5, 0x00000400 IMMUTABLE(5, ... |
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// 6, 0x00001000 CONCURRENT(6, ... |
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// 7, 0x00004000 SUBSIZED(7, ... |
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// The following 4 flags are currently undefined and a free for any further |
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// spliterator characteristics. |
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// |
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// 8, 0x00010000 |
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// 9, 0x00040000 |
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// 10, 0x00100000 |
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// 11, 0x00400000 |
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// The following flags are specific to streams and operations |
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// |
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/** |
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* Characteristic value signifying that an operation may short-circuit the |
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* stream. |
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* <p> |
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* An intermediate operation can preserve or inject this value, |
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* or a terminal operation can preserve or inject this value. |
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*/ |
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// 12, 0x01000000 |
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SHORT_CIRCUIT(12, |
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set(Type.OP).set(Type.TERMINAL_OP)), |
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/** |
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* Characteristic value signifying that an operation may adjust the |
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* total size of the stream. |
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* <p> |
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* The flag, if present, is only valid when SIZED is present; |
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* and is only valid for sequential streams. |
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* <p> |
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* An intermediate operation can preserve or inject this value. |
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*/ |
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// 13, 0x04000000 |
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SIZE_ADJUSTING(13, |
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set(Type.OP)); |
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// The following 2 flags are currently undefined and a free for any further |
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// stream flags if/when required |
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// |
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// 14, 0x10000000 |
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// 15, 0x40000000 |
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/** |
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* Type of a flag |
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*/ |
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enum Type { |
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/** |
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* The flag is associated with spliterator characteristics. |
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*/ |
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SPLITERATOR, |
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/** |
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* The flag is associated with stream flags. |
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*/ |
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STREAM, |
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/** |
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* The flag is associated with intermediate operation flags. |
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*/ |
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OP, |
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/** |
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* The flag is associated with terminal operation flags. |
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*/ |
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TERMINAL_OP, |
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/** |
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* The flag is associated with terminal operation flags that are |
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* propagated upstream across the last stateful operation boundary |
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*/ |
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UPSTREAM_TERMINAL_OP |
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} |
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/** |
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* The bit pattern for setting/injecting a flag. |
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*/ |
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private static final int SET_BITS = 0b01; |
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/** |
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* The bit pattern for clearing a flag. |
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*/ |
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private static final int CLEAR_BITS = 0b10; |
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/** |
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* The bit pattern for preserving a flag. |
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*/ |
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private static final int PRESERVE_BITS = 0b11; |
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private static MaskBuilder set(Type t) { |
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return new MaskBuilder(new EnumMap<>(Type.class)).set(t); |
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} |
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private static class MaskBuilder { |
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final Map<Type, Integer> map; |
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MaskBuilder(Map<Type, Integer> map) { |
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this.map = map; |
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} |
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MaskBuilder mask(Type t, Integer i) { |
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map.put(t, i); |
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return this; |
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} |
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MaskBuilder set(Type t) { |
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return mask(t, SET_BITS); |
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} |
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MaskBuilder clear(Type t) { |
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return mask(t, CLEAR_BITS); |
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} |
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MaskBuilder setAndClear(Type t) { |
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return mask(t, PRESERVE_BITS); |
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} |
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Map<Type, Integer> build() { |
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for (Type t : Type.values()) { |
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map.putIfAbsent(t, 0b00); |
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} |
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return map; |
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} |
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} |
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/** |
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* The mask table for a flag, this is used to determine if a flag |
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* corresponds to a certain flag type and for creating mask constants. |
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*/ |
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private final Map<Type, Integer> maskTable; |
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/** |
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* The bit position in the bit mask. |
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*/ |
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private final int bitPosition; |
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/** |
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* The set 2 bit set offset at the bit position. |
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*/ |
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private final int set; |
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/** |
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* The clear 2 bit set offset at the bit position. |
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*/ |
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private final int clear; |
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/** |
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* The preserve 2 bit set offset at the bit position. |
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*/ |
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private final int preserve; |
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private StreamOpFlag(int position, MaskBuilder maskBuilder) { |
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this.maskTable = maskBuilder.build(); |
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// Two bits per flag |
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position *= 2; |
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this.bitPosition = position; |
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this.set = SET_BITS << position; |
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this.clear = CLEAR_BITS << position; |
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this.preserve = PRESERVE_BITS << position; |
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} |
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/** |
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* Gets the bitmap associated with setting this characteristic. |
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* |
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* @return the bitmap for setting this characteristic |
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*/ |
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int set() { |
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return set; |
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} |
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/** |
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* Gets the bitmap associated with clearing this characteristic. |
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* |
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* @return the bitmap for clearing this characteristic |
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*/ |
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int clear() { |
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return clear; |
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} |
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/** |
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* Determines if this flag is a stream-based flag. |
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* |
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* @return true if a stream-based flag, otherwise false. |
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*/ |
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boolean isStreamFlag() { |
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return maskTable.get(Type.STREAM) > 0; |
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} |
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/** |
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* Checks if this flag is set on stream flags, injected on operation flags, |
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* and injected on combined stream and operation flags. |
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* |
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* @param flags the stream flags, operation flags, or combined stream and |
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* operation flags |
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* @return true if this flag is known, otherwise false. |
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*/ |
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boolean isKnown(int flags) { |
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return (flags & preserve) == set; |
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} |
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/** |
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* Checks if this flag is cleared on operation flags or combined stream and |
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* operation flags. |
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* |
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* @param flags the operation flags or combined stream and operations flags. |
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* @return true if this flag is preserved, otherwise false. |
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*/ |
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boolean isCleared(int flags) { |
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return (flags & preserve) == clear; |
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} |
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/** |
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* Checks if this flag is preserved on combined stream and operation flags. |
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* |
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* @param flags the combined stream and operations flags. |
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* @return true if this flag is preserved, otherwise false. |
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*/ |
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boolean isPreserved(int flags) { |
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return (flags & preserve) == preserve; |
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} |
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/** |
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* Determines if this flag can be set for a flag type. |
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* |
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* @param t the flag type. |
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* @return true if this flag can be set for the flag type, otherwise false. |
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*/ |
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boolean canSet(Type t) { |
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return (maskTable.get(t) & SET_BITS) > 0; |
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} |
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/** |
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* The bit mask for spliterator characteristics |
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*/ |
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static final int SPLITERATOR_CHARACTERISTICS_MASK = createMask(Type.SPLITERATOR); |
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/** |
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* The bit mask for source stream flags. |
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*/ |
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static final int STREAM_MASK = createMask(Type.STREAM); |
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/** |
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* The bit mask for intermediate operation flags. |
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*/ |
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static final int OP_MASK = createMask(Type.OP); |
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/** |
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* The bit mask for terminal operation flags. |
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*/ |
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static final int TERMINAL_OP_MASK = createMask(Type.TERMINAL_OP); |
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/** |
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* The bit mask for upstream terminal operation flags. |
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*/ |
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static final int UPSTREAM_TERMINAL_OP_MASK = createMask(Type.UPSTREAM_TERMINAL_OP); |
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private static int createMask(Type t) { |
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int mask = 0; |
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for (StreamOpFlag flag : StreamOpFlag.values()) { |
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mask |= flag.maskTable.get(t) << flag.bitPosition; |
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} |
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return mask; |
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} |
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/** |
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* Complete flag mask. |
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*/ |
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private static final int FLAG_MASK = createFlagMask(); |
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private static int createFlagMask() { |
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int mask = 0; |
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for (StreamOpFlag flag : StreamOpFlag.values()) { |
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mask |= flag.preserve; |
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} |
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return mask; |
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} |
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/** |
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* Flag mask for stream flags that are set. |
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*/ |
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private static final int FLAG_MASK_IS = STREAM_MASK; |
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/** |
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* Flag mask for stream flags that are cleared. |
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*/ |
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private static final int FLAG_MASK_NOT = STREAM_MASK << 1; |
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/** |
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* The initial value to be combined with the stream flags of the first |
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* stream in the pipeline. |
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*/ |
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static final int INITIAL_OPS_VALUE = FLAG_MASK_IS | FLAG_MASK_NOT; |
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/** |
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* The bit value to set or inject {@link #DISTINCT}. |
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*/ |
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static final int IS_DISTINCT = DISTINCT.set; |
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/** |
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* The bit value to clear {@link #DISTINCT}. |
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*/ |
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static final int NOT_DISTINCT = DISTINCT.clear; |
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/** |
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* The bit value to set or inject {@link #SORTED}. |
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*/ |
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static final int IS_SORTED = SORTED.set; |
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/** |
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* The bit value to clear {@link #SORTED}. |
|
*/ |
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static final int NOT_SORTED = SORTED.clear; |
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/** |
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* The bit value to set or inject {@link #ORDERED}. |
|
*/ |
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static final int IS_ORDERED = ORDERED.set; |
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/** |
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* The bit value to clear {@link #ORDERED}. |
|
*/ |
|
static final int NOT_ORDERED = ORDERED.clear; |
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/** |
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* The bit value to set {@link #SIZED}. |
|
*/ |
|
static final int IS_SIZED = SIZED.set; |
|
/** |
|
* The bit value to clear {@link #SIZED}. |
|
*/ |
|
static final int NOT_SIZED = SIZED.clear; |
|
/** |
|
* The bit value to inject {@link #SHORT_CIRCUIT}. |
|
*/ |
|
static final int IS_SHORT_CIRCUIT = SHORT_CIRCUIT.set; |
|
/** |
|
* The bit value to inject {@link #SIZE_ADJUSTING}. |
|
*/ |
|
static final int IS_SIZE_ADJUSTING = SIZE_ADJUSTING.set; |
|
private static int getMask(int flags) { |
|
return (flags == 0) |
|
? FLAG_MASK |
|
: ~(flags | ((FLAG_MASK_IS & flags) << 1) | ((FLAG_MASK_NOT & flags) >> 1)); |
|
} |
|
/** |
|
* Combines stream or operation flags with previously combined stream and |
|
* operation flags to produce updated combined stream and operation flags. |
|
* <p> |
|
* A flag set on stream flags or injected on operation flags, |
|
* and injected combined stream and operation flags, |
|
* will be injected on the updated combined stream and operation flags. |
|
* |
|
* <p> |
|
* A flag set on stream flags or injected on operation flags, |
|
* and cleared on the combined stream and operation flags, |
|
* will be cleared on the updated combined stream and operation flags. |
|
* |
|
* <p> |
|
* A flag set on the stream flags or injected on operation flags, |
|
* and preserved on the combined stream and operation flags, |
|
* will be injected on the updated combined stream and operation flags. |
|
* |
|
* <p> |
|
* A flag not set on the stream flags or cleared/preserved on operation |
|
* flags, and injected on the combined stream and operation flags, |
|
* will be injected on the updated combined stream and operation flags. |
|
* |
|
* <p> |
|
* A flag not set on the stream flags or cleared/preserved on operation |
|
* flags, and cleared on the combined stream and operation flags, |
|
* will be cleared on the updated combined stream and operation flags. |
|
* |
|
* <p> |
|
* A flag not set on the stream flags, |
|
* and preserved on the combined stream and operation flags |
|
* will be preserved on the updated combined stream and operation flags. |
|
* |
|
* <p> |
|
* A flag cleared on operation flags, |
|
* and preserved on the combined stream and operation flags |
|
* will be cleared on the updated combined stream and operation flags. |
|
* |
|
* <p> |
|
* A flag preserved on operation flags, |
|
* and preserved on the combined stream and operation flags |
|
* will be preserved on the updated combined stream and operation flags. |
|
* |
|
* @param newStreamOrOpFlags the stream or operation flags. |
|
* @param prevCombOpFlags previously combined stream and operation flags. |
|
* The value {#link INITIAL_OPS_VALUE} must be used as the seed value. |
|
* @return the updated combined stream and operation flags. |
|
*/ |
|
static int combineOpFlags(int newStreamOrOpFlags, int prevCombOpFlags) { |
|
// 0x01 or 0x10 nibbles are transformed to 0x11 |
|
// 0x00 nibbles remain unchanged |
|
// Then all the bits are flipped |
|
// Then the result is logically or'ed with the operation flags. |
|
return (prevCombOpFlags & StreamOpFlag.getMask(newStreamOrOpFlags)) | newStreamOrOpFlags; |
|
} |
|
/** |
|
* Converts combined stream and operation flags to stream flags. |
|
* |
|
* <p>Each flag injected on the combined stream and operation flags will be |
|
* set on the stream flags. |
|
* |
|
* @param combOpFlags the combined stream and operation flags. |
|
* @return the stream flags. |
|
*/ |
|
static int toStreamFlags(int combOpFlags) { |
|
// By flipping the nibbles 0x11 become 0x00 and 0x01 become 0x10 |
|
// Shift left 1 to restore set flags and mask off anything other than the set flags |
|
return ((~combOpFlags) >> 1) & FLAG_MASK_IS & combOpFlags; |
|
} |
|
/** |
|
* Converts stream flags to a spliterator characteristic bit set. |
|
* |
|
* @param streamFlags the stream flags. |
|
* @return the spliterator characteristic bit set. |
|
*/ |
|
static int toCharacteristics(int streamFlags) { |
|
return streamFlags & SPLITERATOR_CHARACTERISTICS_MASK; |
|
} |
|
/** |
|
* Converts a spliterator characteristic bit set to stream flags. |
|
* |
|
* @implSpec |
|
* If the spliterator is naturally {@code SORTED} (the associated |
|
* {@code Comparator} is {@code null}) then the characteristic is converted |
|
* to the {@link #SORTED} flag, otherwise the characteristic is not |
|
* converted. |
|
* |
|
* @param spliterator the spliterator from which to obtain characteristic |
|
* bit set. |
|
* @return the stream flags. |
|
*/ |
|
static int fromCharacteristics(Spliterator<?> spliterator) { |
|
int characteristics = spliterator.characteristics(); |
|
if ((characteristics & Spliterator.SORTED) != 0 && spliterator.getComparator() != null) { |
|
// Do not propagate the SORTED characteristic if it does not correspond |
|
// to a natural sort order |
|
return characteristics & SPLITERATOR_CHARACTERISTICS_MASK & ~Spliterator.SORTED; |
|
} |
|
else { |
|
return characteristics & SPLITERATOR_CHARACTERISTICS_MASK; |
|
} |
|
} |
|
/** |
|
* Converts a spliterator characteristic bit set to stream flags. |
|
* |
|
* @param characteristics the spliterator characteristic bit set. |
|
* @return the stream flags. |
|
*/ |
|
static int fromCharacteristics(int characteristics) { |
|
return characteristics & SPLITERATOR_CHARACTERISTICS_MASK; |
|
} |
|
} |