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revision 1.66, Sun Jan 7 07:38:27 2007 UTC revision 1.93, Tue Feb 26 17:28:00 2013 UTC
# Line 1  Line 1 
1  /*  /*
2   * %W% %E%   * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
3     * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4   *   *
5   * Copyright 2007 Sun Microsystems, Inc. All rights reserved.   * This code is free software; you can redistribute it and/or modify it
6   * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.   * 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    
26  package java.util;  package java.util;
27    import java.util.function.Consumer;
28    import java.util.stream.Stream;
29    import java.util.stream.Streams;
30    
31  /**  /**
32   * An unbounded priority {@linkplain Queue queue} based on a priority heap.   * An unbounded priority {@linkplain Queue queue} based on a priority heap.
# Line 56  Line 77 
77   * Java Collections Framework</a>.   * Java Collections Framework</a>.
78   *   *
79   * @since 1.5   * @since 1.5
  * @version %I%, %G%  
80   * @author Josh Bloch, Doug Lea   * @author Josh Bloch, Doug Lea
81   * @param <E> the type of elements held in this collection   * @param <E> the type of elements held in this collection
82   */   */
# Line 75  Line 95 
95       * heap and each descendant d of n, n <= d.  The element with the       * heap and each descendant d of n, n <= d.  The element with the
96       * lowest value is in queue[0], assuming the queue is nonempty.       * lowest value is in queue[0], assuming the queue is nonempty.
97       */       */
98      private transient Object[] queue;      transient Object[] queue; // non-private to simplify nested class access
99    
100      /**      /**
101       * The number of elements in the priority queue.       * The number of elements in the priority queue.
# Line 92  Line 112 
112       * The number of times this priority queue has been       * The number of times this priority queue has been
113       * <i>structurally modified</i>.  See AbstractList for gory details.       * <i>structurally modified</i>.  See AbstractList for gory details.
114       */       */
115      private transient int modCount = 0;      transient int modCount = 0; // non-private to simplify nested class access
116    
117      /**      /**
118       * Creates a {@code PriorityQueue} with the default initial       * Creates a {@code PriorityQueue} with the default initial
# Line 153  Line 173 
173       * @throws NullPointerException if the specified collection or any       * @throws NullPointerException if the specified collection or any
174       *         of its elements are null       *         of its elements are null
175       */       */
176        @SuppressWarnings("unchecked")
177      public PriorityQueue(Collection<? extends E> c) {      public PriorityQueue(Collection<? extends E> c) {
178          initFromCollection(c);          if (c instanceof SortedSet<?>) {
179          if (c instanceof SortedSet)              SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
180              comparator = (Comparator<? super E>)              this.comparator = (Comparator<? super E>) ss.comparator();
181                  ((SortedSet<? extends E>)c).comparator();              initElementsFromCollection(ss);
182          else if (c instanceof PriorityQueue)          }
183              comparator = (Comparator<? super E>)          else if (c instanceof PriorityQueue<?>) {
184                  ((PriorityQueue<? extends E>)c).comparator();              PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
185                this.comparator = (Comparator<? super E>) pq.comparator();
186                initFromPriorityQueue(pq);
187            }
188          else {          else {
189              comparator = null;              this.comparator = null;
190              heapify();              initFromCollection(c);
191          }          }
192      }      }
193    
# Line 181  Line 205 
205       * @throws NullPointerException if the specified priority queue or any       * @throws NullPointerException if the specified priority queue or any
206       *         of its elements are null       *         of its elements are null
207       */       */
208        @SuppressWarnings("unchecked")
209      public PriorityQueue(PriorityQueue<? extends E> c) {      public PriorityQueue(PriorityQueue<? extends E> c) {
210          comparator = (Comparator<? super E>)c.comparator();          this.comparator = (Comparator<? super E>) c.comparator();
211          initFromCollection(c);          initFromPriorityQueue(c);
212      }      }
213    
214      /**      /**
# Line 199  Line 224 
224       * @throws NullPointerException if the specified sorted set or any       * @throws NullPointerException if the specified sorted set or any
225       *         of its elements are null       *         of its elements are null
226       */       */
227        @SuppressWarnings("unchecked")
228      public PriorityQueue(SortedSet<? extends E> c) {      public PriorityQueue(SortedSet<? extends E> c) {
229          comparator = (Comparator<? super E>)c.comparator();          this.comparator = (Comparator<? super E>) c.comparator();
230            initElementsFromCollection(c);
231        }
232    
233        private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
234            if (c.getClass() == PriorityQueue.class) {
235                this.queue = c.toArray();
236                this.size = c.size();
237            } else {
238          initFromCollection(c);          initFromCollection(c);
239      }      }
240        }
241    
242        private void initElementsFromCollection(Collection<? extends E> c) {
243            Object[] a = c.toArray();
244            // If c.toArray incorrectly doesn't return Object[], copy it.
245            if (a.getClass() != Object[].class)
246                a = Arrays.copyOf(a, a.length, Object[].class);
247            int len = a.length;
248            if (len == 1 || this.comparator != null)
249                for (int i = 0; i < len; i++)
250                    if (a[i] == null)
251                        throw new NullPointerException();
252            this.queue = a;
253            this.size = a.length;
254        }
255    
256      /**      /**
257       * Initializes queue array with elements from the given Collection.       * Initializes queue array with elements from the given Collection.
# Line 210  Line 259 
259       * @param c the collection       * @param c the collection
260       */       */
261      private void initFromCollection(Collection<? extends E> c) {      private void initFromCollection(Collection<? extends E> c) {
262          Object[] a = c.toArray();          initElementsFromCollection(c);
263          // If c.toArray incorrectly doesn't return Object[], copy it.          heapify();
         if (a.getClass() != Object[].class)  
             a = Arrays.copyOf(a, a.length, Object[].class);  
         queue = a;  
         size = a.length;  
264      }      }
265    
266      /**      /**
267         * The maximum size of array to allocate.
268         * Some VMs reserve some header words in an array.
269         * Attempts to allocate larger arrays may result in
270         * OutOfMemoryError: Requested array size exceeds VM limit
271         */
272        private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
273    
274        /**
275       * Increases the capacity of the array.       * Increases the capacity of the array.
276       *       *
277       * @param minCapacity the desired minimum capacity       * @param minCapacity the desired minimum capacity
278       */       */
279      private void grow(int minCapacity) {      private void grow(int minCapacity) {
         if (minCapacity < 0) // overflow  
             throw new OutOfMemoryError();  
280          int oldCapacity = queue.length;          int oldCapacity = queue.length;
281          // Double size if small; else grow by 50%          // Double size if small; else grow by 50%
282          int newCapacity = ((oldCapacity < 64)?          int newCapacity = oldCapacity + ((oldCapacity < 64) ?
283                             ((oldCapacity + 1) * 2):                                           (oldCapacity + 2) :
284                             ((oldCapacity / 2) * 3));                                           (oldCapacity >> 1));
285          if (newCapacity < 0) // overflow          // overflow-conscious code
286              newCapacity = Integer.MAX_VALUE;          if (newCapacity - MAX_ARRAY_SIZE > 0)
287          if (newCapacity < minCapacity)              newCapacity = hugeCapacity(minCapacity);
             newCapacity = minCapacity;  
288          queue = Arrays.copyOf(queue, newCapacity);          queue = Arrays.copyOf(queue, newCapacity);
289      }      }
290    
291        private static int hugeCapacity(int minCapacity) {
292            if (minCapacity < 0) // overflow
293                throw new OutOfMemoryError();
294            return (minCapacity > MAX_ARRAY_SIZE) ?
295                Integer.MAX_VALUE :
296                MAX_ARRAY_SIZE;
297        }
298    
299      /**      /**
300       * Inserts the specified element into this priority queue.       * Inserts the specified element into this priority queue.
301       *       *
# Line 275  Line 333 
333          return true;          return true;
334      }      }
335    
336        @SuppressWarnings("unchecked")
337      public E peek() {      public E peek() {
338          if (size == 0)          return (size == 0) ? null : (E) queue[0];
             return null;  
         return (E) queue[0];  
339      }      }
340    
341      private int indexOf(Object o) {      private int indexOf(Object o) {
# Line 375  Line 432 
432       * precise control over the runtime type of the output array, and may,       * precise control over the runtime type of the output array, and may,
433       * under certain circumstances, be used to save allocation costs.       * under certain circumstances, be used to save allocation costs.
434       *       *
435       * <p>Suppose <tt>x</tt> is a queue known to contain only strings.       * <p>Suppose {@code x} is a queue known to contain only strings.
436       * The following code can be used to dump the queue into a newly       * The following code can be used to dump the queue into a newly
437       * allocated array of <tt>String</tt>:       * allocated array of {@code String}:
438       *       *
439       * <pre>       *  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
      *     String[] y = x.toArray(new String[0]);</pre>  
440       *       *
441       * Note that <tt>toArray(new Object[0])</tt> is identical in function to       * Note that {@code toArray(new Object[0])} is identical in function to
442       * <tt>toArray()</tt>.       * {@code toArray()}.
443       *       *
444       * @param a the array into which the elements of the queue are to       * @param a the array into which the elements of the queue are to
445       *          be stored, if it is big enough; otherwise, a new array of the       *          be stored, if it is big enough; otherwise, a new array of the
# Line 394  Line 450 
450       *         this queue       *         this queue
451       * @throws NullPointerException if the specified array is null       * @throws NullPointerException if the specified array is null
452       */       */
453        @SuppressWarnings("unchecked")
454      public <T> T[] toArray(T[] a) {      public <T> T[] toArray(T[] a) {
455            final int size = this.size;
456          if (a.length < size)          if (a.length < size)
457              // Make a new array of a's runtime type, but my contents:              // Make a new array of a's runtime type, but my contents:
458              return (T[]) Arrays.copyOf(queue, size, a.getClass());              return (T[]) Arrays.copyOf(queue, size, a.getClass());
# Line 459  Line 517 
517                  (forgetMeNot != null && !forgetMeNot.isEmpty());                  (forgetMeNot != null && !forgetMeNot.isEmpty());
518          }          }
519    
520            @SuppressWarnings("unchecked")
521          public E next() {          public E next() {
522              if (expectedModCount != modCount)              if (expectedModCount != modCount)
523                  throw new ConcurrentModificationException();                  throw new ConcurrentModificationException();
# Line 483  Line 542 
542                      cursor--;                      cursor--;
543                  else {                  else {
544                      if (forgetMeNot == null)                      if (forgetMeNot == null)
545                          forgetMeNot = new ArrayDeque<E>();                          forgetMeNot = new ArrayDeque<>();
546                      forgetMeNot.add(moved);                      forgetMeNot.add(moved);
547                  }                  }
548              } else if (lastRetElt != null) {              } else if (lastRetElt != null) {
# Line 511  Line 570 
570          size = 0;          size = 0;
571      }      }
572    
573        @SuppressWarnings("unchecked")
574      public E poll() {      public E poll() {
575          if (size == 0)          if (size == 0)
576              return null;              return null;
# Line 536  Line 596 
596       * position before i. This fact is used by iterator.remove so as to       * position before i. This fact is used by iterator.remove so as to
597       * avoid missing traversing elements.       * avoid missing traversing elements.
598       */       */
599        @SuppressWarnings("unchecked")
600      private E removeAt(int i) {      private E removeAt(int i) {
601          assert i >= 0 && i < size;          // assert i >= 0 && i < size;
602          modCount++;          modCount++;
603          int s = --size;          int s = --size;
604          if (s == i) // removed last element          if (s == i) // removed last element
# Line 574  Line 635 
635              siftUpComparable(k, x);              siftUpComparable(k, x);
636      }      }
637    
638        @SuppressWarnings("unchecked")
639      private void siftUpComparable(int k, E x) {      private void siftUpComparable(int k, E x) {
640          Comparable<? super E> key = (Comparable<? super E>) x;          Comparable<? super E> key = (Comparable<? super E>) x;
641          while (k > 0) {          while (k > 0) {
# Line 587  Line 649 
649          queue[k] = key;          queue[k] = key;
650      }      }
651    
652        @SuppressWarnings("unchecked")
653      private void siftUpUsingComparator(int k, E x) {      private void siftUpUsingComparator(int k, E x) {
654          while (k > 0) {          while (k > 0) {
655              int parent = (k - 1) >>> 1;              int parent = (k - 1) >>> 1;
# Line 614  Line 677 
677              siftDownComparable(k, x);              siftDownComparable(k, x);
678      }      }
679    
680        @SuppressWarnings("unchecked")
681      private void siftDownComparable(int k, E x) {      private void siftDownComparable(int k, E x) {
682          Comparable<? super E> key = (Comparable<? super E>)x;          Comparable<? super E> key = (Comparable<? super E>)x;
683          int half = size >>> 1;        // loop while a non-leaf          int half = size >>> 1;        // loop while a non-leaf
# Line 632  Line 696 
696          queue[k] = key;          queue[k] = key;
697      }      }
698    
699        @SuppressWarnings("unchecked")
700      private void siftDownUsingComparator(int k, E x) {      private void siftDownUsingComparator(int k, E x) {
701          int half = size >>> 1;          int half = size >>> 1;
702          while (k < half) {          while (k < half) {
# Line 653  Line 718 
718       * Establishes the heap invariant (described above) in the entire tree,       * Establishes the heap invariant (described above) in the entire tree,
719       * assuming nothing about the order of the elements prior to the call.       * assuming nothing about the order of the elements prior to the call.
720       */       */
721        @SuppressWarnings("unchecked")
722      private void heapify() {      private void heapify() {
723          for (int i = (size >>> 1) - 1; i >= 0; i--)          for (int i = (size >>> 1) - 1; i >= 0; i--)
724              siftDown(i, (E) queue[i]);              siftDown(i, (E) queue[i]);
# Line 672  Line 738 
738      }      }
739    
740      /**      /**
741       * Saves the state of the instance to a stream (that       * Saves this queue to a stream (that is, serializes it).
      * is, serializes it).  
742       *       *
743       * @serialData The length of the array backing the instance is       * @serialData The length of the array backing the instance is
744       *             emitted (int), followed by all of its elements       *             emitted (int), followed by all of its elements
# Line 717  Line 782 
782          // spec has never explained what that might be.          // spec has never explained what that might be.
783          heapify();          heapify();
784      }      }
785    
786        final Spliterator<E> spliterator() {
787            return new PriorityQueueSpliterator<E>(this, 0, -1, 0);
788        }
789    
790        public Stream<E> stream() {
791            return Streams.stream(spliterator());
792        }
793    
794        public Stream<E> parallelStream() {
795            return Streams.parallelStream(spliterator());
796        }
797    
798        /**
799         * This is very similar to ArrayList Spliterator, except for extra
800         * null checks.
801         */
802        static final class PriorityQueueSpliterator<E> implements Spliterator<E> {
803            private final PriorityQueue<E> pq;
804            private int index;            // current index, modified on advance/split
805            private int fence;            // -1 until first use
806            private int expectedModCount; // initialized when fence set
807    
808            /** Creates new spliterator covering the given range */
809            PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
810                                 int expectedModCount) {
811                this.pq = pq;
812                this.index = origin;
813                this.fence = fence;
814                this.expectedModCount = expectedModCount;
815            }
816    
817            private int getFence() { // initialize fence to size on first use
818                int hi;
819                if ((hi = fence) < 0) {
820                    expectedModCount = pq.modCount;
821                    hi = fence = pq.size;
822                }
823                return hi;
824            }
825    
826            public PriorityQueueSpliterator<E> trySplit() {
827                int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
828                return (lo >= mid) ? null :
829                    new PriorityQueueSpliterator<E>(pq, lo, index = mid,
830                                                    expectedModCount);
831            }
832    
833            @SuppressWarnings("unchecked")
834            public void forEach(Consumer<? super E> action) {
835                int i, hi, mc; // hoist accesses and checks from loop
836                PriorityQueue<E> q; Object[] a;
837                if (action == null)
838                    throw new NullPointerException();
839                if ((q = pq) != null && (a = q.queue) != null) {
840                    if ((hi = fence) < 0) {
841                        mc = q.modCount;
842                        hi = q.size;
843                    }
844                    else
845                        mc = expectedModCount;
846                    if ((i = index) >= 0 && (index = hi) <= a.length) {
847                        for (E e;; ++i) {
848                            if (i < hi) {
849                                if ((e = (E) a[i]) == null) // must be CME
850                                    break;
851                                action.accept(e);
852                            }
853                            else if (q.modCount != mc)
854                                break;
855                            else
856                                return;
857                        }
858                    }
859                }
860                throw new ConcurrentModificationException();
861            }
862    
863            public boolean tryAdvance(Consumer<? super E> action) {
864                int hi = getFence(), lo = index;
865                if (lo >= 0 && lo < hi) {
866                    index = lo + 1;
867                    @SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
868                    if (e == null)
869                        throw new ConcurrentModificationException();
870                    action.accept(e);
871                    if (pq.modCount != expectedModCount)
872                        throw new ConcurrentModificationException();
873                    return true;
874                }
875                return false;
876            }
877    
878            public long estimateSize() {
879                return (long) (getFence() - index);
880            }
881    
882            public int characteristics() {
883                return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
884            }
885        }
886  }  }

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  Added in v.1.93

Doug Lea
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