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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.109 by jsr166, Wed Jun 1 16:08:04 2016 UTC vs.
Revision 1.124 by jsr166, Sun May 6 19:35:51 2018 UTC

# Line 1 | Line 1
1   /*
2 < * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
2 > * Copyright (c) 2003, 2018, 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
# Line 26 | Line 26
26   package java.util;
27  
28   import java.util.function.Consumer;
29 + import jdk.internal.misc.SharedSecrets;
30  
31   /**
32   * An unbounded priority {@linkplain Queue queue} based on a priority heap.
# Line 54 | Line 55 | import java.util.function.Consumer;
55   * <p>This class and its iterator implement all of the
56   * <em>optional</em> methods of the {@link Collection} and {@link
57   * Iterator} interfaces.  The Iterator provided in method {@link
58 < * #iterator()} is <em>not</em> guaranteed to traverse the elements of
58 > * #iterator()} and the Spliterator provided in method {@link #spliterator()}
59 > * are <em>not</em> guaranteed to traverse the elements of
60   * the priority queue in any particular order. If you need ordered
61   * traversal, consider using {@code Arrays.sort(pq.toArray())}.
62   *
# Line 72 | Line 74 | import java.util.function.Consumer;
74   * ({@code peek}, {@code element}, and {@code size}).
75   *
76   * <p>This class is a member of the
77 < * <a href="{@docRoot}/../technotes/guides/collections/index.html">
77 > * <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
78   * Java Collections Framework</a>.
79   *
80   * @since 1.5
81   * @author Josh Bloch, Doug Lea
82   * @param <E> the type of elements held in this queue
83   */
84 + @SuppressWarnings("unchecked")
85   public class PriorityQueue<E> extends AbstractQueue<E>
86      implements java.io.Serializable {
87  
# Line 185 | Line 188 | public class PriorityQueue<E> extends Ab
188       * @throws NullPointerException if the specified collection or any
189       *         of its elements are null
190       */
188    @SuppressWarnings("unchecked")
191      public PriorityQueue(Collection<? extends E> c) {
192          if (c instanceof SortedSet<?>) {
193              SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
# Line 217 | Line 219 | public class PriorityQueue<E> extends Ab
219       * @throws NullPointerException if the specified priority queue or any
220       *         of its elements are null
221       */
220    @SuppressWarnings("unchecked")
222      public PriorityQueue(PriorityQueue<? extends E> c) {
223          this.comparator = (Comparator<? super E>) c.comparator();
224          initFromPriorityQueue(c);
# Line 236 | Line 237 | public class PriorityQueue<E> extends Ab
237       * @throws NullPointerException if the specified sorted set or any
238       *         of its elements are null
239       */
239    @SuppressWarnings("unchecked")
240      public PriorityQueue(SortedSet<? extends E> c) {
241          this.comparator = (Comparator<? super E>) c.comparator();
242          initElementsFromCollection(c);
# Line 252 | Line 252 | public class PriorityQueue<E> extends Ab
252      }
253  
254      private void initElementsFromCollection(Collection<? extends E> c) {
255 <        Object[] a = c.toArray();
255 >        Object[] es = c.toArray();
256 >        int len = es.length;
257          // If c.toArray incorrectly doesn't return Object[], copy it.
258 <        if (a.getClass() != Object[].class)
259 <            a = Arrays.copyOf(a, a.length, Object[].class);
259 <        int len = a.length;
258 >        if (es.getClass() != Object[].class)
259 >            es = Arrays.copyOf(es, len, Object[].class);
260          if (len == 1 || this.comparator != null)
261 <            for (Object e : a)
261 >            for (Object e : es)
262                  if (e == null)
263                      throw new NullPointerException();
264 <        this.queue = a;
265 <        this.size = a.length;
264 >        this.queue = es;
265 >        this.size = len;
266      }
267  
268      /**
# Line 342 | Line 342 | public class PriorityQueue<E> extends Ab
342          return true;
343      }
344  
345    @SuppressWarnings("unchecked")
345      public E peek() {
346          return (size == 0) ? null : (E) queue[0];
347      }
348  
349      private int indexOf(Object o) {
350          if (o != null) {
351 <            for (int i = 0; i < size; i++)
352 <                if (o.equals(queue[i]))
351 >            final Object[] es = queue;
352 >            for (int i = 0, n = size; i < n; i++)
353 >                if (o.equals(es[i]))
354                      return i;
355          }
356          return -1;
# Line 378 | Line 378 | public class PriorityQueue<E> extends Ab
378      }
379  
380      /**
381 <     * Version of remove using reference equality, not equals.
382 <     * Needed by iterator.remove.
381 >     * Identity-based version for use in Itr.remove.
382       *
383       * @param o element to be removed from this queue, if present
385     * @return {@code true} if removed
384       */
385 <    boolean removeEq(Object o) {
386 <        for (int i = 0; i < size; i++) {
387 <            if (o == queue[i]) {
385 >    void removeEq(Object o) {
386 >        final Object[] es = queue;
387 >        for (int i = 0, n = size; i < n; i++) {
388 >            if (o == es[i]) {
389                  removeAt(i);
390 <                return true;
390 >                break;
391              }
392          }
394        return false;
393      }
394  
395      /**
# Line 459 | Line 457 | public class PriorityQueue<E> extends Ab
457       *         this queue
458       * @throws NullPointerException if the specified array is null
459       */
462    @SuppressWarnings("unchecked")
460      public <T> T[] toArray(T[] a) {
461          final int size = this.size;
462          if (a.length < size)
# Line 521 | Line 518 | public class PriorityQueue<E> extends Ab
518           */
519          private int expectedModCount = modCount;
520  
521 +        Itr() {}                        // prevent access constructor creation
522 +
523          public boolean hasNext() {
524              return cursor < size ||
525                  (forgetMeNot != null && !forgetMeNot.isEmpty());
526          }
527  
529        @SuppressWarnings("unchecked")
528          public E next() {
529              if (expectedModCount != modCount)
530                  throw new ConcurrentModificationException();
# Line 574 | Line 572 | public class PriorityQueue<E> extends Ab
572       */
573      public void clear() {
574          modCount++;
575 <        for (int i = 0; i < size; i++)
576 <            queue[i] = null;
575 >        final Object[] es = queue;
576 >        for (int i = 0, n = size; i < n; i++)
577 >            es[i] = null;
578          size = 0;
579      }
580  
582    @SuppressWarnings("unchecked")
581      public E poll() {
582          if (size == 0)
583              return null;
# Line 605 | Line 603 | public class PriorityQueue<E> extends Ab
603       * position before i. This fact is used by iterator.remove so as to
604       * avoid missing traversing elements.
605       */
608    @SuppressWarnings("unchecked")
606      E removeAt(int i) {
607          // assert i >= 0 && i < size;
608          modCount++;
# Line 630 | Line 627 | public class PriorityQueue<E> extends Ab
627       * promoting x up the tree until it is greater than or equal to
628       * its parent, or is the root.
629       *
630 <     * To simplify and speed up coercions and comparisons. the
630 >     * To simplify and speed up coercions and comparisons, the
631       * Comparable and Comparator versions are separated into different
632       * methods that are otherwise identical. (Similarly for siftDown.)
633       *
# Line 639 | Line 636 | public class PriorityQueue<E> extends Ab
636       */
637      private void siftUp(int k, E x) {
638          if (comparator != null)
639 <            siftUpUsingComparator(k, x);
639 >            siftUpUsingComparator(k, x, queue, comparator);
640          else
641 <            siftUpComparable(k, x);
641 >            siftUpComparable(k, x, queue);
642      }
643  
644 <    @SuppressWarnings("unchecked")
645 <    private void siftUpComparable(int k, E x) {
649 <        Comparable<? super E> key = (Comparable<? super E>) x;
644 >    private static <T> void siftUpComparable(int k, T x, Object[] es) {
645 >        Comparable<? super T> key = (Comparable<? super T>) x;
646          while (k > 0) {
647              int parent = (k - 1) >>> 1;
648 <            Object e = queue[parent];
649 <            if (key.compareTo((E) e) >= 0)
648 >            Object e = es[parent];
649 >            if (key.compareTo((T) e) >= 0)
650                  break;
651 <            queue[k] = e;
651 >            es[k] = e;
652              k = parent;
653          }
654 <        queue[k] = key;
654 >        es[k] = key;
655      }
656  
657 <    @SuppressWarnings("unchecked")
658 <    private void siftUpUsingComparator(int k, E x) {
657 >    private static <T> void siftUpUsingComparator(
658 >        int k, T x, Object[] es, Comparator<? super T> cmp) {
659          while (k > 0) {
660              int parent = (k - 1) >>> 1;
661 <            Object e = queue[parent];
662 <            if (comparator.compare(x, (E) e) >= 0)
661 >            Object e = es[parent];
662 >            if (cmp.compare(x, (T) e) >= 0)
663                  break;
664 <            queue[k] = e;
664 >            es[k] = e;
665              k = parent;
666          }
667 <        queue[k] = x;
667 >        es[k] = x;
668      }
669  
670      /**
# Line 681 | Line 677 | public class PriorityQueue<E> extends Ab
677       */
678      private void siftDown(int k, E x) {
679          if (comparator != null)
680 <            siftDownUsingComparator(k, x);
680 >            siftDownUsingComparator(k, x, queue, size, comparator);
681          else
682 <            siftDownComparable(k, x);
682 >            siftDownComparable(k, x, queue, size);
683      }
684  
685 <    @SuppressWarnings("unchecked")
686 <    private void siftDownComparable(int k, E x) {
687 <        Comparable<? super E> key = (Comparable<? super E>)x;
688 <        int half = size >>> 1;        // loop while a non-leaf
685 >    private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
686 >        // assert n > 0;
687 >        Comparable<? super T> key = (Comparable<? super T>)x;
688 >        int half = n >>> 1;           // loop while a non-leaf
689          while (k < half) {
690              int child = (k << 1) + 1; // assume left child is least
691 <            Object c = queue[child];
691 >            Object c = es[child];
692              int right = child + 1;
693 <            if (right < size &&
694 <                ((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
695 <                c = queue[child = right];
696 <            if (key.compareTo((E) c) <= 0)
693 >            if (right < n &&
694 >                ((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
695 >                c = es[child = right];
696 >            if (key.compareTo((T) c) <= 0)
697                  break;
698 <            queue[k] = c;
698 >            es[k] = c;
699              k = child;
700          }
701 <        queue[k] = key;
701 >        es[k] = key;
702      }
703  
704 <    @SuppressWarnings("unchecked")
705 <    private void siftDownUsingComparator(int k, E x) {
706 <        int half = size >>> 1;
704 >    private static <T> void siftDownUsingComparator(
705 >        int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
706 >        // assert n > 0;
707 >        int half = n >>> 1;
708          while (k < half) {
709              int child = (k << 1) + 1;
710 <            Object c = queue[child];
710 >            Object c = es[child];
711              int right = child + 1;
712 <            if (right < size &&
713 <                comparator.compare((E) c, (E) queue[right]) > 0)
714 <                c = queue[child = right];
718 <            if (comparator.compare(x, (E) c) <= 0)
712 >            if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
713 >                c = es[child = right];
714 >            if (cmp.compare(x, (T) c) <= 0)
715                  break;
716 <            queue[k] = c;
716 >            es[k] = c;
717              k = child;
718          }
719 <        queue[k] = x;
719 >        es[k] = x;
720      }
721  
722      /**
723       * Establishes the heap invariant (described above) in the entire tree,
724       * assuming nothing about the order of the elements prior to the call.
725 +     * This classic algorithm due to Floyd (1964) is known to be O(size).
726       */
730    @SuppressWarnings("unchecked")
727      private void heapify() {
728 <        for (int i = (size >>> 1) - 1; i >= 0; i--)
729 <            siftDown(i, (E) queue[i]);
728 >        final Object[] es = queue;
729 >        int n = size, i = (n >>> 1) - 1;
730 >        Comparator<? super E> cmp = comparator;
731 >        if (cmp == null)
732 >            for (; i >= 0; i--)
733 >                siftDownComparable(i, (E) es[i], es, n);
734 >        else
735 >            for (; i >= 0; i--)
736 >                siftDownUsingComparator(i, (E) es[i], es, n, cmp);
737      }
738  
739      /**
# Line 749 | Line 752 | public class PriorityQueue<E> extends Ab
752      /**
753       * Saves this queue to a stream (that is, serializes it).
754       *
755 +     * @param s the stream
756 +     * @throws java.io.IOException if an I/O error occurs
757       * @serialData The length of the array backing the instance is
758       *             emitted (int), followed by all of its elements
759       *             (each an {@code Object}) in the proper order.
755     * @param s the stream
756     * @throws java.io.IOException if an I/O error occurs
760       */
761      private void writeObject(java.io.ObjectOutputStream s)
762          throws java.io.IOException {
# Line 764 | Line 767 | public class PriorityQueue<E> extends Ab
767          s.writeInt(Math.max(2, size + 1));
768  
769          // Write out all elements in the "proper order".
770 <        for (int i = 0; i < size; i++)
771 <            s.writeObject(queue[i]);
770 >        final Object[] es = queue;
771 >        for (int i = 0, n = size; i < n; i++)
772 >            s.writeObject(es[i]);
773      }
774  
775      /**
# Line 785 | Line 789 | public class PriorityQueue<E> extends Ab
789          // Read in (and discard) array length
790          s.readInt();
791  
792 +        SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
793          queue = new Object[size];
794  
795          // Read in all elements.
796 <        for (int i = 0; i < size; i++)
797 <            queue[i] = s.readObject();
796 >        final Object[] es = queue;
797 >        for (int i = 0, n = size; i < n; i++)
798 >            es[i] = s.readObject();
799  
800          // Elements are guaranteed to be in "proper order", but the
801          // spec has never explained what that might be.
# Line 799 | Line 805 | public class PriorityQueue<E> extends Ab
805      /**
806       * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
807       * and <em>fail-fast</em> {@link Spliterator} over the elements in this
808 <     * queue.
808 >     * queue. The spliterator does not traverse elements in any particular order
809 >     * (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
810       *
811       * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
812       * {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
# Line 810 | Line 817 | public class PriorityQueue<E> extends Ab
817       * @since 1.8
818       */
819      public final Spliterator<E> spliterator() {
820 <        return new PriorityQueueSpliterator<>(this, 0, -1, 0);
820 >        return new PriorityQueueSpliterator(0, -1, 0);
821      }
822  
823 <    static final class PriorityQueueSpliterator<E> implements Spliterator<E> {
817 <        /*
818 <         * This is very similar to ArrayList Spliterator, except for
819 <         * extra null checks.
820 <         */
821 <        private final PriorityQueue<E> pq;
823 >    final class PriorityQueueSpliterator implements Spliterator<E> {
824          private int index;            // current index, modified on advance/split
825          private int fence;            // -1 until first use
826          private int expectedModCount; // initialized when fence set
827  
828          /** Creates new spliterator covering the given range. */
829 <        PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
828 <                                 int expectedModCount) {
829 <            this.pq = pq;
829 >        PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
830              this.index = origin;
831              this.fence = fence;
832              this.expectedModCount = expectedModCount;
# Line 835 | Line 835 | public class PriorityQueue<E> extends Ab
835          private int getFence() { // initialize fence to size on first use
836              int hi;
837              if ((hi = fence) < 0) {
838 <                expectedModCount = pq.modCount;
839 <                hi = fence = pq.size;
838 >                expectedModCount = modCount;
839 >                hi = fence = size;
840              }
841              return hi;
842          }
843  
844 <        public PriorityQueueSpliterator<E> trySplit() {
844 >        public PriorityQueueSpliterator trySplit() {
845              int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
846              return (lo >= mid) ? null :
847 <                new PriorityQueueSpliterator<>(pq, lo, index = mid,
848 <                                               expectedModCount);
847 >                new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
848          }
849  
851        @SuppressWarnings("unchecked")
850          public void forEachRemaining(Consumer<? super E> action) {
853            int i, hi, mc; // hoist accesses and checks from loop
854            PriorityQueue<E> q; Object[] a;
851              if (action == null)
852                  throw new NullPointerException();
853 <            if ((q = pq) != null && (a = q.queue) != null) {
854 <                if ((hi = fence) < 0) {
855 <                    mc = q.modCount;
856 <                    hi = q.size;
857 <                }
858 <                else
859 <                    mc = expectedModCount;
864 <                if ((i = index) >= 0 && (index = hi) <= a.length) {
865 <                    for (E e;; ++i) {
866 <                        if (i < hi) {
867 <                            if ((e = (E) a[i]) == null) // must be CME
868 <                                break;
869 <                            action.accept(e);
870 <                        }
871 <                        else if (q.modCount != mc)
872 <                            break;
873 <                        else
874 <                            return;
875 <                    }
876 <                }
853 >            if (fence < 0) { fence = size; expectedModCount = modCount; }
854 >            final Object[] es = queue;
855 >            int i, hi; E e;
856 >            for (i = index, index = hi = fence; i < hi; i++) {
857 >                if ((e = (E) es[i]) == null)
858 >                    break;      // must be CME
859 >                action.accept(e);
860              }
861 <            throw new ConcurrentModificationException();
861 >            if (modCount != expectedModCount)
862 >                throw new ConcurrentModificationException();
863          }
864  
865          public boolean tryAdvance(Consumer<? super E> action) {
866              if (action == null)
867                  throw new NullPointerException();
868 <            int hi = getFence(), lo = index;
869 <            if (lo >= 0 && lo < hi) {
870 <                index = lo + 1;
871 <                @SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
872 <                if (e == null)
868 >            if (fence < 0) { fence = size; expectedModCount = modCount; }
869 >            int i;
870 >            if ((i = index) < fence) {
871 >                index = i + 1;
872 >                E e;
873 >                if ((e = (E) queue[i]) == null
874 >                    || modCount != expectedModCount)
875                      throw new ConcurrentModificationException();
876                  action.accept(e);
891                if (pq.modCount != expectedModCount)
892                    throw new ConcurrentModificationException();
877                  return true;
878              }
879              return false;
880          }
881  
882          public long estimateSize() {
883 <            return (long) (getFence() - index);
883 >            return getFence() - index;
884          }
885  
886          public int characteristics() {
887              return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
888          }
889      }
890 +
891 +    /**
892 +     * @throws NullPointerException {@inheritDoc}
893 +     */
894 +    public void forEach(Consumer<? super E> action) {
895 +        Objects.requireNonNull(action);
896 +        final int expectedModCount = modCount;
897 +        final Object[] es = queue;
898 +        for (int i = 0, n = size; i < n; i++)
899 +            action.accept((E) es[i]);
900 +        if (expectedModCount != modCount)
901 +            throw new ConcurrentModificationException();
902 +    }
903   }

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