1 /*
   2  * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package java.util.stream;
  26 
  27 import java.util.Comparator;
  28 import java.util.Objects;
  29 import java.util.Spliterator;
  30 import java.util.function.Consumer;
  31 import java.util.function.DoubleConsumer;
  32 import java.util.function.IntConsumer;
  33 import java.util.function.LongConsumer;
  34 
  35 /**
  36  * Utility methods for operating on and creating streams.
  37  *
  38  * <p>Unless otherwise stated, streams are created as sequential streams.  A
  39  * sequential stream can be transformed into a parallel stream by calling the
  40  * {@code parallel()} method on the created stream.
  41  *
  42  * @since 1.8
  43  */
  44 final class Streams {
  45 
  46     private Streams() {
  47         throw new Error("no instances");
  48     }
  49 
  50     /**
  51      * An object instance representing no value, that cannot be an actual
  52      * data element of a stream.  Used when processing streams that can contain
  53      * {@code null} elements to distinguish between a {@code null} value and no
  54      * value.
  55      */
  56     static final Object NONE = new Object();
  57 
  58     /**
  59      * An {@code int} range spliterator.
  60      */
  61     static final class RangeIntSpliterator implements Spliterator.OfInt {
  62         // Can never be greater that upTo, this avoids overflow if upper bound
  63         // is Integer.MAX_VALUE
  64         // All elements are traversed if from == upTo & last == 0
  65         private int from;
  66         private final int upTo;
  67         // 1 if the range is closed and the last element has not been traversed
  68         // Otherwise, 0 if the range is open, or is a closed range and all
  69         // elements have been traversed
  70         private int last;
  71 
  72         RangeIntSpliterator(int from, int upTo, boolean closed) {
  73             this(from, upTo, closed ? 1 : 0);
  74         }
  75 
  76         private RangeIntSpliterator(int from, int upTo, int last) {
  77             this.from = from;
  78             this.upTo = upTo;
  79             this.last = last;
  80         }
  81 
  82         @Override
  83         public boolean tryAdvance(IntConsumer consumer) {
  84             Objects.requireNonNull(consumer);
  85 
  86             final int i = from;
  87             if (i < upTo) {
  88                 from++;
  89                 consumer.accept(i);
  90                 return true;
  91             }
  92             else if (last > 0) {
  93                 last = 0;
  94                 consumer.accept(i);
  95                 return true;
  96             }
  97             return false;
  98         }
  99 
 100         @Override
 101         public void forEachRemaining(IntConsumer consumer) {
 102             Objects.requireNonNull(consumer);
 103 
 104             int i = from;
 105             final int hUpTo = upTo;
 106             int hLast = last;
 107             from = upTo;
 108             last = 0;
 109             while (i < hUpTo) {
 110                 consumer.accept(i++);
 111             }
 112             if (hLast > 0) {
 113                 // Last element of closed range
 114                 consumer.accept(i);
 115             }
 116         }
 117 
 118         @Override
 119         public long estimateSize() {
 120             // Ensure ranges of size > Integer.MAX_VALUE report the correct size
 121             return ((long) upTo) - from + last;
 122         }
 123 
 124         @Override
 125         public int characteristics() {
 126             return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED |
 127                    Spliterator.IMMUTABLE | Spliterator.NONNULL |
 128                    Spliterator.DISTINCT | Spliterator.SORTED;
 129         }
 130 
 131         @Override
 132         public Comparator<? super Integer> getComparator() {
 133             return null;
 134         }
 135 
 136         @Override
 137         public Spliterator.OfInt trySplit() {
 138             long size = estimateSize();
 139             return size <= 1
 140                    ? null
 141                    // Left split always has a half-open range
 142                    : new RangeIntSpliterator(from, from = from + splitPoint(size), 0);
 143         }
 144 
 145         /**
 146          * The spliterator size below which the spliterator will be split
 147          * at the mid-point to produce balanced splits. Above this size the
 148          * spliterator will be split at a ratio of
 149          * 1:(RIGHT_BALANCED_SPLIT_RATIO - 1)
 150          * to produce right-balanced splits.
 151          *
 152          * <p>Such splitting ensures that for very large ranges that the left
 153          * side of the range will more likely be processed at a lower-depth
 154          * than a balanced tree at the expense of a higher-depth for the right
 155          * side of the range.
 156          *
 157          * <p>This is optimized for cases such as IntStream.ints() that is
 158          * implemented as range of 0 to Integer.MAX_VALUE but is likely to be
 159          * augmented with a limit operation that limits the number of elements
 160          * to a count lower than this threshold.
 161          */
 162         private static final int BALANCED_SPLIT_THRESHOLD = 1 << 24;
 163 
 164         /**
 165          * The split ratio of the left and right split when the spliterator
 166          * size is above BALANCED_SPLIT_THRESHOLD.
 167          */
 168         private static final int RIGHT_BALANCED_SPLIT_RATIO = 1 << 3;
 169 
 170         private int splitPoint(long size) {
 171             int d = (size < BALANCED_SPLIT_THRESHOLD) ? 2 : RIGHT_BALANCED_SPLIT_RATIO;
 172             // 2 <= size <= 2^32
 173             return (int) (size / d);
 174         }
 175     }
 176 
 177     /**
 178      * A {@code long} range spliterator.
 179      *
 180      * This implementation cannot be used for ranges whose size is greater
 181      * than Long.MAX_VALUE
 182      */
 183     static final class RangeLongSpliterator implements Spliterator.OfLong {
 184         // Can never be greater that upTo, this avoids overflow if upper bound
 185         // is Long.MAX_VALUE
 186         // All elements are traversed if from == upTo & last == 0
 187         private long from;
 188         private final long upTo;
 189         // 1 if the range is closed and the last element has not been traversed
 190         // Otherwise, 0 if the range is open, or is a closed range and all
 191         // elements have been traversed
 192         private int last;
 193 
 194         RangeLongSpliterator(long from, long upTo, boolean closed) {
 195             this(from, upTo, closed ? 1 : 0);
 196         }
 197 
 198         private RangeLongSpliterator(long from, long upTo, int last) {
 199             assert upTo - from + last > 0;
 200             this.from = from;
 201             this.upTo = upTo;
 202             this.last = last;
 203         }
 204 
 205         @Override
 206         public boolean tryAdvance(LongConsumer consumer) {
 207             Objects.requireNonNull(consumer);
 208 
 209             final long i = from;
 210             if (i < upTo) {
 211                 from++;
 212                 consumer.accept(i);
 213                 return true;
 214             }
 215             else if (last > 0) {
 216                 last = 0;
 217                 consumer.accept(i);
 218                 return true;
 219             }
 220             return false;
 221         }
 222 
 223         @Override
 224         public void forEachRemaining(LongConsumer consumer) {
 225             Objects.requireNonNull(consumer);
 226 
 227             long i = from;
 228             final long hUpTo = upTo;
 229             int hLast = last;
 230             from = upTo;
 231             last = 0;
 232             while (i < hUpTo) {
 233                 consumer.accept(i++);
 234             }
 235             if (hLast > 0) {
 236                 // Last element of closed range
 237                 consumer.accept(i);
 238             }
 239         }
 240 
 241         @Override
 242         public long estimateSize() {
 243             return upTo - from + last;
 244         }
 245 
 246         @Override
 247         public int characteristics() {
 248             return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED |
 249                    Spliterator.IMMUTABLE | Spliterator.NONNULL |
 250                    Spliterator.DISTINCT | Spliterator.SORTED;
 251         }
 252 
 253         @Override
 254         public Comparator<? super Long> getComparator() {
 255             return null;
 256         }
 257 
 258         @Override
 259         public Spliterator.OfLong trySplit() {
 260             long size = estimateSize();
 261             return size <= 1
 262                    ? null
 263                    // Left split always has a half-open range
 264                    : new RangeLongSpliterator(from, from = from + splitPoint(size), 0);
 265         }
 266 
 267         /**
 268          * The spliterator size below which the spliterator will be split
 269          * at the mid-point to produce balanced splits. Above this size the
 270          * spliterator will be split at a ratio of
 271          * 1:(RIGHT_BALANCED_SPLIT_RATIO - 1)
 272          * to produce right-balanced splits.
 273          *
 274          * <p>Such splitting ensures that for very large ranges that the left
 275          * side of the range will more likely be processed at a lower-depth
 276          * than a balanced tree at the expense of a higher-depth for the right
 277          * side of the range.
 278          *
 279          * <p>This is optimized for cases such as LongStream.longs() that is
 280          * implemented as range of 0 to Long.MAX_VALUE but is likely to be
 281          * augmented with a limit operation that limits the number of elements
 282          * to a count lower than this threshold.
 283          */
 284         private static final long BALANCED_SPLIT_THRESHOLD = 1 << 24;
 285 
 286         /**
 287          * The split ratio of the left and right split when the spliterator
 288          * size is above BALANCED_SPLIT_THRESHOLD.
 289          */
 290         private static final long RIGHT_BALANCED_SPLIT_RATIO = 1 << 3;
 291 
 292         private long splitPoint(long size) {
 293             long d = (size < BALANCED_SPLIT_THRESHOLD) ? 2 : RIGHT_BALANCED_SPLIT_RATIO;
 294             // 2 <= size <= Long.MAX_VALUE
 295             return size / d;
 296         }
 297     }
 298 
 299     private static abstract class AbstractStreamBuilderImpl<T, S extends Spliterator<T>> implements Spliterator<T> {
 300         // >= 0 when building, < 0 when built
 301         // -1 == no elements
 302         // -2 == one element, held by first
 303         // -3 == two or more elements, held by buffer
 304         int count;
 305 
 306         // Spliterator implementation for 0 or 1 element
 307         // count == -1 for no elements
 308         // count == -2 for one element held by first
 309 
 310         @Override
 311         public S trySplit() {
 312             return null;
 313         }
 314 
 315         @Override
 316         public long estimateSize() {
 317             return -count - 1;
 318         }
 319 
 320         @Override
 321         public int characteristics() {
 322             return Spliterator.SIZED | Spliterator.SUBSIZED |
 323                    Spliterator.ORDERED | Spliterator.IMMUTABLE;
 324         }
 325     }
 326 
 327     static final class StreamBuilderImpl<T>
 328             extends AbstractStreamBuilderImpl<T, Spliterator<T>>
 329             implements Stream.Builder<T> {
 330         // The first element in the stream
 331         // valid if count == 1
 332         T first;
 333 
 334         // The first and subsequent elements in the stream
 335         // non-null if count == 2
 336         SpinedBuffer<T> buffer;
 337 
 338         /**
 339          * Constructor for building a stream of 0 or more elements.
 340          */
 341         StreamBuilderImpl() { }
 342 
 343         /**
 344          * Constructor for a singleton stream.
 345          *
 346          * @param t the single element
 347          */
 348         StreamBuilderImpl(T t) {
 349             first = t;
 350             count = -2;
 351         }
 352 
 353         // StreamBuilder implementation
 354 
 355         @Override
 356         public void accept(T t) {
 357             if (count == 0) {
 358                 first = t;
 359                 count++;
 360             }
 361             else if (count > 0) {
 362                 if (buffer == null) {
 363                     buffer = new SpinedBuffer<>();
 364                     buffer.accept(first);
 365                     count++;
 366                 }
 367 
 368                 buffer.accept(t);
 369             }
 370             else {
 371                 throw new IllegalStateException();
 372             }
 373         }
 374 
 375         public Stream.Builder<T> add(T t) {
 376             accept(t);
 377             return this;
 378         }
 379 
 380         @Override
 381         public Stream<T> build() {
 382             int c = count;
 383             if (c >= 0) {
 384                 // Switch count to negative value signalling the builder is built
 385                 count = -count - 1;
 386                 // Use this spliterator if 0 or 1 elements, otherwise use
 387                 // the spliterator of the spined buffer
 388                 return (c < 2) ? StreamSupport.stream(this, false) : StreamSupport.stream(buffer.spliterator(), false);
 389             }
 390 
 391             throw new IllegalStateException();
 392         }
 393 
 394         // Spliterator implementation for 0 or 1 element
 395         // count == -1 for no elements
 396         // count == -2 for one element held by first
 397 
 398         @Override
 399         public boolean tryAdvance(Consumer<? super T> action) {
 400             Objects.requireNonNull(action);
 401 
 402             if (count == -2) {
 403                 action.accept(first);
 404                 count = -1;
 405                 return true;
 406             }
 407             else {
 408                 return false;
 409             }
 410         }
 411 
 412         @Override
 413         public void forEachRemaining(Consumer<? super T> action) {
 414             Objects.requireNonNull(action);
 415 
 416             if (count == -2) {
 417                 action.accept(first);
 418                 count = -1;
 419             }
 420         }
 421     }
 422 
 423     static final class IntStreamBuilderImpl
 424             extends AbstractStreamBuilderImpl<Integer, Spliterator.OfInt>
 425             implements IntStream.Builder, Spliterator.OfInt {
 426         // The first element in the stream
 427         // valid if count == 1
 428         int first;
 429 
 430         // The first and subsequent elements in the stream
 431         // non-null if count == 2
 432         SpinedBuffer.OfInt buffer;
 433 
 434         /**
 435          * Constructor for building a stream of 0 or more elements.
 436          */
 437         IntStreamBuilderImpl() { }
 438 
 439         /**
 440          * Constructor for a singleton stream.
 441          *
 442          * @param t the single element
 443          */
 444         IntStreamBuilderImpl(int t) {
 445             first = t;
 446             count = -2;
 447         }
 448 
 449         // StreamBuilder implementation
 450 
 451         @Override
 452         public void accept(int t) {
 453             if (count == 0) {
 454                 first = t;
 455                 count++;
 456             }
 457             else if (count > 0) {
 458                 if (buffer == null) {
 459                     buffer = new SpinedBuffer.OfInt();
 460                     buffer.accept(first);
 461                     count++;
 462                 }
 463 
 464                 buffer.accept(t);
 465             }
 466             else {
 467                 throw new IllegalStateException();
 468             }
 469         }
 470 
 471         @Override
 472         public IntStream build() {
 473             int c = count;
 474             if (c >= 0) {
 475                 // Switch count to negative value signalling the builder is built
 476                 count = -count - 1;
 477                 // Use this spliterator if 0 or 1 elements, otherwise use
 478                 // the spliterator of the spined buffer
 479                 return (c < 2) ? StreamSupport.intStream(this, false) : StreamSupport.intStream(buffer.spliterator(), false);
 480             }
 481 
 482             throw new IllegalStateException();
 483         }
 484 
 485         // Spliterator implementation for 0 or 1 element
 486         // count == -1 for no elements
 487         // count == -2 for one element held by first
 488 
 489         @Override
 490         public boolean tryAdvance(IntConsumer action) {
 491             Objects.requireNonNull(action);
 492 
 493             if (count == -2) {
 494                 action.accept(first);
 495                 count = -1;
 496                 return true;
 497             }
 498             else {
 499                 return false;
 500             }
 501         }
 502 
 503         @Override
 504         public void forEachRemaining(IntConsumer action) {
 505             Objects.requireNonNull(action);
 506 
 507             if (count == -2) {
 508                 action.accept(first);
 509                 count = -1;
 510             }
 511         }
 512     }
 513 
 514     static final class LongStreamBuilderImpl
 515             extends AbstractStreamBuilderImpl<Long, Spliterator.OfLong>
 516             implements LongStream.Builder, Spliterator.OfLong {
 517         // The first element in the stream
 518         // valid if count == 1
 519         long first;
 520 
 521         // The first and subsequent elements in the stream
 522         // non-null if count == 2
 523         SpinedBuffer.OfLong buffer;
 524 
 525         /**
 526          * Constructor for building a stream of 0 or more elements.
 527          */
 528         LongStreamBuilderImpl() { }
 529 
 530         /**
 531          * Constructor for a singleton stream.
 532          *
 533          * @param t the single element
 534          */
 535         LongStreamBuilderImpl(long t) {
 536             first = t;
 537             count = -2;
 538         }
 539 
 540         // StreamBuilder implementation
 541 
 542         @Override
 543         public void accept(long t) {
 544             if (count == 0) {
 545                 first = t;
 546                 count++;
 547             }
 548             else if (count > 0) {
 549                 if (buffer == null) {
 550                     buffer = new SpinedBuffer.OfLong();
 551                     buffer.accept(first);
 552                     count++;
 553                 }
 554 
 555                 buffer.accept(t);
 556             }
 557             else {
 558                 throw new IllegalStateException();
 559             }
 560         }
 561 
 562         @Override
 563         public LongStream build() {
 564             int c = count;
 565             if (c >= 0) {
 566                 // Switch count to negative value signalling the builder is built
 567                 count = -count - 1;
 568                 // Use this spliterator if 0 or 1 elements, otherwise use
 569                 // the spliterator of the spined buffer
 570                 return (c < 2) ? StreamSupport.longStream(this, false) : StreamSupport.longStream(buffer.spliterator(), false);
 571             }
 572 
 573             throw new IllegalStateException();
 574         }
 575 
 576         // Spliterator implementation for 0 or 1 element
 577         // count == -1 for no elements
 578         // count == -2 for one element held by first
 579 
 580         @Override
 581         public boolean tryAdvance(LongConsumer action) {
 582             Objects.requireNonNull(action);
 583 
 584             if (count == -2) {
 585                 action.accept(first);
 586                 count = -1;
 587                 return true;
 588             }
 589             else {
 590                 return false;
 591             }
 592         }
 593 
 594         @Override
 595         public void forEachRemaining(LongConsumer action) {
 596             Objects.requireNonNull(action);
 597 
 598             if (count == -2) {
 599                 action.accept(first);
 600                 count = -1;
 601             }
 602         }
 603     }
 604 
 605     static final class DoubleStreamBuilderImpl
 606             extends AbstractStreamBuilderImpl<Double, Spliterator.OfDouble>
 607             implements DoubleStream.Builder, Spliterator.OfDouble {
 608         // The first element in the stream
 609         // valid if count == 1
 610         double first;
 611 
 612         // The first and subsequent elements in the stream
 613         // non-null if count == 2
 614         SpinedBuffer.OfDouble buffer;
 615 
 616         /**
 617          * Constructor for building a stream of 0 or more elements.
 618          */
 619         DoubleStreamBuilderImpl() { }
 620 
 621         /**
 622          * Constructor for a singleton stream.
 623          *
 624          * @param t the single element
 625          */
 626         DoubleStreamBuilderImpl(double t) {
 627             first = t;
 628             count = -2;
 629         }
 630 
 631         // StreamBuilder implementation
 632 
 633         @Override
 634         public void accept(double t) {
 635             if (count == 0) {
 636                 first = t;
 637                 count++;
 638             }
 639             else if (count > 0) {
 640                 if (buffer == null) {
 641                     buffer = new SpinedBuffer.OfDouble();
 642                     buffer.accept(first);
 643                     count++;
 644                 }
 645 
 646                 buffer.accept(t);
 647             }
 648             else {
 649                 throw new IllegalStateException();
 650             }
 651         }
 652 
 653         @Override
 654         public DoubleStream build() {
 655             int c = count;
 656             if (c >= 0) {
 657                 // Switch count to negative value signalling the builder is built
 658                 count = -count - 1;
 659                 // Use this spliterator if 0 or 1 elements, otherwise use
 660                 // the spliterator of the spined buffer
 661                 return (c < 2) ? StreamSupport.doubleStream(this, false) : StreamSupport.doubleStream(buffer.spliterator(), false);
 662             }
 663 
 664             throw new IllegalStateException();
 665         }
 666 
 667         // Spliterator implementation for 0 or 1 element
 668         // count == -1 for no elements
 669         // count == -2 for one element held by first
 670 
 671         @Override
 672         public boolean tryAdvance(DoubleConsumer action) {
 673             Objects.requireNonNull(action);
 674 
 675             if (count == -2) {
 676                 action.accept(first);
 677                 count = -1;
 678                 return true;
 679             }
 680             else {
 681                 return false;
 682             }
 683         }
 684 
 685         @Override
 686         public void forEachRemaining(DoubleConsumer action) {
 687             Objects.requireNonNull(action);
 688 
 689             if (count == -2) {
 690                 action.accept(first);
 691                 count = -1;
 692             }
 693         }
 694     }
 695 
 696     abstract static class ConcatSpliterator<T, T_SPLITR extends Spliterator<T>>
 697             implements Spliterator<T> {
 698         protected final T_SPLITR aSpliterator;
 699         protected final T_SPLITR bSpliterator;
 700         // True when no split has occurred, otherwise false
 701         boolean beforeSplit;
 702         // Never read after splitting
 703         final boolean unsized;
 704 
 705         public ConcatSpliterator(T_SPLITR aSpliterator, T_SPLITR bSpliterator) {
 706             this.aSpliterator = aSpliterator;
 707             this.bSpliterator = bSpliterator;
 708             beforeSplit = true;
 709             // The spliterator is known to be unsized before splitting if the
 710             // sum of the estimates overflows.
 711             unsized = aSpliterator.estimateSize() + bSpliterator.estimateSize() < 0;
 712         }
 713 
 714         @Override
 715         public T_SPLITR trySplit() {
 716             T_SPLITR ret = beforeSplit ? aSpliterator : (T_SPLITR) bSpliterator.trySplit();
 717             beforeSplit = false;
 718             return ret;
 719         }
 720 
 721         @Override
 722         public boolean tryAdvance(Consumer<? super T> consumer) {
 723             boolean hasNext;
 724             if (beforeSplit) {
 725                 hasNext = aSpliterator.tryAdvance(consumer);
 726                 if (!hasNext) {
 727                     beforeSplit = false;
 728                     hasNext = bSpliterator.tryAdvance(consumer);
 729                 }
 730             }
 731             else
 732                 hasNext = bSpliterator.tryAdvance(consumer);
 733             return hasNext;
 734         }
 735 
 736         @Override
 737         public void forEachRemaining(Consumer<? super T> consumer) {
 738             if (beforeSplit)
 739                 aSpliterator.forEachRemaining(consumer);
 740             bSpliterator.forEachRemaining(consumer);
 741         }
 742 
 743         @Override
 744         public long estimateSize() {
 745             if (beforeSplit) {
 746                 // If one or both estimates are Long.MAX_VALUE then the sum
 747                 // will either be Long.MAX_VALUE or overflow to a negative value
 748                 long size = aSpliterator.estimateSize() + bSpliterator.estimateSize();
 749                 return (size >= 0) ? size : Long.MAX_VALUE;
 750             }
 751             else {
 752                 return bSpliterator.estimateSize();
 753             }
 754         }
 755 
 756         @Override
 757         public int characteristics() {
 758             if (beforeSplit) {
 759                 // Concatenation loses DISTINCT and SORTED characteristics
 760                 return aSpliterator.characteristics() & bSpliterator.characteristics()
 761                        & ~(Spliterator.DISTINCT | Spliterator.SORTED
 762                            | (unsized ? Spliterator.SIZED | Spliterator.SUBSIZED : 0));
 763             }
 764             else {
 765                 return bSpliterator.characteristics();
 766             }
 767         }
 768 
 769         @Override
 770         public Comparator<? super T> getComparator() {
 771             if (beforeSplit)
 772                 throw new IllegalStateException();
 773             return bSpliterator.getComparator();
 774         }
 775 
 776         static class OfRef<T> extends ConcatSpliterator<T, Spliterator<T>> {
 777             OfRef(Spliterator<T> aSpliterator, Spliterator<T> bSpliterator) {
 778                 super(aSpliterator, bSpliterator);
 779             }
 780         }
 781 
 782         private static abstract class OfPrimitive<T, T_CONS, T_SPLITR extends Spliterator.OfPrimitive<T, T_CONS, T_SPLITR>>
 783                 extends ConcatSpliterator<T, T_SPLITR>
 784                 implements Spliterator.OfPrimitive<T, T_CONS, T_SPLITR> {
 785             private OfPrimitive(T_SPLITR aSpliterator, T_SPLITR bSpliterator) {
 786                 super(aSpliterator, bSpliterator);
 787             }
 788 
 789             @Override
 790             public boolean tryAdvance(T_CONS action) {
 791                 boolean hasNext;
 792                 if (beforeSplit) {
 793                     hasNext = aSpliterator.tryAdvance(action);
 794                     if (!hasNext) {
 795                         beforeSplit = false;
 796                         hasNext = bSpliterator.tryAdvance(action);
 797                     }
 798                 }
 799                 else
 800                     hasNext = bSpliterator.tryAdvance(action);
 801                 return hasNext;
 802             }
 803 
 804             @Override
 805             public void forEachRemaining(T_CONS action) {
 806                 if (beforeSplit)
 807                     aSpliterator.forEachRemaining(action);
 808                 bSpliterator.forEachRemaining(action);
 809             }
 810         }
 811 
 812         static class OfInt
 813                 extends ConcatSpliterator.OfPrimitive<Integer, IntConsumer, Spliterator.OfInt>
 814                 implements Spliterator.OfInt {
 815             OfInt(Spliterator.OfInt aSpliterator, Spliterator.OfInt bSpliterator) {
 816                 super(aSpliterator, bSpliterator);
 817             }
 818         }
 819 
 820         static class OfLong
 821                 extends ConcatSpliterator.OfPrimitive<Long, LongConsumer, Spliterator.OfLong>
 822                 implements Spliterator.OfLong {
 823             OfLong(Spliterator.OfLong aSpliterator, Spliterator.OfLong bSpliterator) {
 824                 super(aSpliterator, bSpliterator);
 825             }
 826         }
 827 
 828         static class OfDouble
 829                 extends ConcatSpliterator.OfPrimitive<Double, DoubleConsumer, Spliterator.OfDouble>
 830                 implements Spliterator.OfDouble {
 831             OfDouble(Spliterator.OfDouble aSpliterator, Spliterator.OfDouble bSpliterator) {
 832                 super(aSpliterator, bSpliterator);
 833             }
 834         }
 835     }
 836 }