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revision 1.66, Sun Jan 7 07:38:27 2007 UTC revision 1.83, Sat Jan 19 17:33:55 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.stream.Stream;
28    import java.util.Spliterator;
29    import java.util.stream.Streams;
30    import java.util.function.Block;
31    
32  /**  /**
33   * 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 78 
78   * Java Collections Framework</a>.   * Java Collections Framework</a>.
79   *   *
80   * @since 1.5   * @since 1.5
  * @version %I%, %G%  
81   * @author Josh Bloch, Doug Lea   * @author Josh Bloch, Doug Lea
82   * @param <E> the type of elements held in this collection   * @param <E> the type of elements held in this collection
83   */   */
# Line 75  Line 96 
96       * 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
97       * lowest value is in queue[0], assuming the queue is nonempty.       * lowest value is in queue[0], assuming the queue is nonempty.
98       */       */
99      private transient Object[] queue;      transient Object[] queue; // non-private to simplify nested class access
100    
101      /**      /**
102       * The number of elements in the priority queue.       * The number of elements in the priority queue.
# Line 92  Line 113 
113       * The number of times this priority queue has been       * The number of times this priority queue has been
114       * <i>structurally modified</i>.  See AbstractList for gory details.       * <i>structurally modified</i>.  See AbstractList for gory details.
115       */       */
116      private transient int modCount = 0;      transient int modCount = 0; // non-private to simplify nested class access
117    
118      /**      /**
119       * Creates a {@code PriorityQueue} with the default initial       * Creates a {@code PriorityQueue} with the default initial
# Line 153  Line 174 
174       * @throws NullPointerException if the specified collection or any       * @throws NullPointerException if the specified collection or any
175       *         of its elements are null       *         of its elements are null
176       */       */
177        @SuppressWarnings("unchecked")
178      public PriorityQueue(Collection<? extends E> c) {      public PriorityQueue(Collection<? extends E> c) {
179          initFromCollection(c);          if (c instanceof SortedSet<?>) {
180          if (c instanceof SortedSet)              SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
181              comparator = (Comparator<? super E>)              this.comparator = (Comparator<? super E>) ss.comparator();
182                  ((SortedSet<? extends E>)c).comparator();              initElementsFromCollection(ss);
183          else if (c instanceof PriorityQueue)          }
184              comparator = (Comparator<? super E>)          else if (c instanceof PriorityQueue<?>) {
185                  ((PriorityQueue<? extends E>)c).comparator();              PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
186                this.comparator = (Comparator<? super E>) pq.comparator();
187                initFromPriorityQueue(pq);
188            }
189          else {          else {
190              comparator = null;              this.comparator = null;
191              heapify();              initFromCollection(c);
192          }          }
193      }      }
194    
# Line 181  Line 206 
206       * @throws NullPointerException if the specified priority queue or any       * @throws NullPointerException if the specified priority queue or any
207       *         of its elements are null       *         of its elements are null
208       */       */
209        @SuppressWarnings("unchecked")
210      public PriorityQueue(PriorityQueue<? extends E> c) {      public PriorityQueue(PriorityQueue<? extends E> c) {
211          comparator = (Comparator<? super E>)c.comparator();          this.comparator = (Comparator<? super E>) c.comparator();
212          initFromCollection(c);          initFromPriorityQueue(c);
213      }      }
214    
215      /**      /**
# Line 199  Line 225 
225       * @throws NullPointerException if the specified sorted set or any       * @throws NullPointerException if the specified sorted set or any
226       *         of its elements are null       *         of its elements are null
227       */       */
228        @SuppressWarnings("unchecked")
229      public PriorityQueue(SortedSet<? extends E> c) {      public PriorityQueue(SortedSet<? extends E> c) {
230          comparator = (Comparator<? super E>)c.comparator();          this.comparator = (Comparator<? super E>) c.comparator();
231            initElementsFromCollection(c);
232        }
233    
234        private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
235            if (c.getClass() == PriorityQueue.class) {
236                this.queue = c.toArray();
237                this.size = c.size();
238            } else {
239          initFromCollection(c);          initFromCollection(c);
240      }      }
241        }
242    
243        private void initElementsFromCollection(Collection<? extends E> c) {
244            Object[] a = c.toArray();
245            // If c.toArray incorrectly doesn't return Object[], copy it.
246            if (a.getClass() != Object[].class)
247                a = Arrays.copyOf(a, a.length, Object[].class);
248            int len = a.length;
249            if (len == 1 || this.comparator != null)
250                for (int i = 0; i < len; i++)
251                    if (a[i] == null)
252                        throw new NullPointerException();
253            this.queue = a;
254            this.size = a.length;
255        }
256    
257      /**      /**
258       * Initializes queue array with elements from the given Collection.       * Initializes queue array with elements from the given Collection.
# Line 210  Line 260 
260       * @param c the collection       * @param c the collection
261       */       */
262      private void initFromCollection(Collection<? extends E> c) {      private void initFromCollection(Collection<? extends E> c) {
263          Object[] a = c.toArray();          initElementsFromCollection(c);
264          // 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;  
265      }      }
266    
267      /**      /**
268         * The maximum size of array to allocate.
269         * Some VMs reserve some header words in an array.
270         * Attempts to allocate larger arrays may result in
271         * OutOfMemoryError: Requested array size exceeds VM limit
272         */
273        private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
274    
275        /**
276       * Increases the capacity of the array.       * Increases the capacity of the array.
277       *       *
278       * @param minCapacity the desired minimum capacity       * @param minCapacity the desired minimum capacity
279       */       */
280      private void grow(int minCapacity) {      private void grow(int minCapacity) {
         if (minCapacity < 0) // overflow  
             throw new OutOfMemoryError();  
281          int oldCapacity = queue.length;          int oldCapacity = queue.length;
282          // Double size if small; else grow by 50%          // Double size if small; else grow by 50%
283          int newCapacity = ((oldCapacity < 64)?          int newCapacity = oldCapacity + ((oldCapacity < 64) ?
284                             ((oldCapacity + 1) * 2):                                           (oldCapacity + 2) :
285                             ((oldCapacity / 2) * 3));                                           (oldCapacity >> 1));
286          if (newCapacity < 0) // overflow          // overflow-conscious code
287              newCapacity = Integer.MAX_VALUE;          if (newCapacity - MAX_ARRAY_SIZE > 0)
288          if (newCapacity < minCapacity)              newCapacity = hugeCapacity(minCapacity);
             newCapacity = minCapacity;  
289          queue = Arrays.copyOf(queue, newCapacity);          queue = Arrays.copyOf(queue, newCapacity);
290      }      }
291    
292        private static int hugeCapacity(int minCapacity) {
293            if (minCapacity < 0) // overflow
294                throw new OutOfMemoryError();
295            return (minCapacity > MAX_ARRAY_SIZE) ?
296                Integer.MAX_VALUE :
297                MAX_ARRAY_SIZE;
298        }
299    
300      /**      /**
301       * Inserts the specified element into this priority queue.       * Inserts the specified element into this priority queue.
302       *       *
# Line 275  Line 334 
334          return true;          return true;
335      }      }
336    
337        @SuppressWarnings("unchecked")
338      public E peek() {      public E peek() {
339          if (size == 0)          return (size == 0) ? null : (E) queue[0];
             return null;  
         return (E) queue[0];  
340      }      }
341    
342      private int indexOf(Object o) {      private int indexOf(Object o) {
# Line 375  Line 433 
433       * precise control over the runtime type of the output array, and may,       * precise control over the runtime type of the output array, and may,
434       * under certain circumstances, be used to save allocation costs.       * under certain circumstances, be used to save allocation costs.
435       *       *
436       * <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.
437       * 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
438       * allocated array of <tt>String</tt>:       * allocated array of {@code String}:
439       *       *
440       * <pre>       *  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
      *     String[] y = x.toArray(new String[0]);</pre>  
441       *       *
442       * 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
443       * <tt>toArray()</tt>.       * {@code toArray()}.
444       *       *
445       * @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
446       *          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 459  Line 516 
516                  (forgetMeNot != null && !forgetMeNot.isEmpty());                  (forgetMeNot != null && !forgetMeNot.isEmpty());
517          }          }
518    
519            @SuppressWarnings("unchecked")
520          public E next() {          public E next() {
521              if (expectedModCount != modCount)              if (expectedModCount != modCount)
522                  throw new ConcurrentModificationException();                  throw new ConcurrentModificationException();
# Line 511  Line 569 
569          size = 0;          size = 0;
570      }      }
571    
572        @SuppressWarnings("unchecked")
573      public E poll() {      public E poll() {
574          if (size == 0)          if (size == 0)
575              return null;              return null;
# Line 536  Line 595 
595       * 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
596       * avoid missing traversing elements.       * avoid missing traversing elements.
597       */       */
598        @SuppressWarnings("unchecked")
599      private E removeAt(int i) {      private E removeAt(int i) {
600          assert i >= 0 && i < size;          // assert i >= 0 && i < size;
601          modCount++;          modCount++;
602          int s = --size;          int s = --size;
603          if (s == i) // removed last element          if (s == i) // removed last element
# Line 574  Line 634 
634              siftUpComparable(k, x);              siftUpComparable(k, x);
635      }      }
636    
637        @SuppressWarnings("unchecked")
638      private void siftUpComparable(int k, E x) {      private void siftUpComparable(int k, E x) {
639          Comparable<? super E> key = (Comparable<? super E>) x;          Comparable<? super E> key = (Comparable<? super E>) x;
640          while (k > 0) {          while (k > 0) {
# Line 587  Line 648 
648          queue[k] = key;          queue[k] = key;
649      }      }
650    
651        @SuppressWarnings("unchecked")
652      private void siftUpUsingComparator(int k, E x) {      private void siftUpUsingComparator(int k, E x) {
653          while (k > 0) {          while (k > 0) {
654              int parent = (k - 1) >>> 1;              int parent = (k - 1) >>> 1;
# Line 614  Line 676 
676              siftDownComparable(k, x);              siftDownComparable(k, x);
677      }      }
678    
679        @SuppressWarnings("unchecked")
680      private void siftDownComparable(int k, E x) {      private void siftDownComparable(int k, E x) {
681          Comparable<? super E> key = (Comparable<? super E>)x;          Comparable<? super E> key = (Comparable<? super E>)x;
682          int half = size >>> 1;        // loop while a non-leaf          int half = size >>> 1;        // loop while a non-leaf
# Line 632  Line 695 
695          queue[k] = key;          queue[k] = key;
696      }      }
697    
698        @SuppressWarnings("unchecked")
699      private void siftDownUsingComparator(int k, E x) {      private void siftDownUsingComparator(int k, E x) {
700          int half = size >>> 1;          int half = size >>> 1;
701          while (k < half) {          while (k < half) {
# Line 653  Line 717 
717       * Establishes the heap invariant (described above) in the entire tree,       * Establishes the heap invariant (described above) in the entire tree,
718       * assuming nothing about the order of the elements prior to the call.       * assuming nothing about the order of the elements prior to the call.
719       */       */
720        @SuppressWarnings("unchecked")
721      private void heapify() {      private void heapify() {
722          for (int i = (size >>> 1) - 1; i >= 0; i--)          for (int i = (size >>> 1) - 1; i >= 0; i--)
723              siftDown(i, (E) queue[i]);              siftDown(i, (E) queue[i]);
# Line 672  Line 737 
737      }      }
738    
739      /**      /**
740       * Saves the state of the instance to a stream (that       * Saves this queue to a stream (that is, serializes it).
      * is, serializes it).  
741       *       *
742       * @serialData The length of the array backing the instance is       * @serialData The length of the array backing the instance is
743       *             emitted (int), followed by all of its elements       *             emitted (int), followed by all of its elements
# Line 717  Line 781 
781          // spec has never explained what that might be.          // spec has never explained what that might be.
782          heapify();          heapify();
783      }      }
784    
785        // wrapping constructor in method avoids transient javac problems
786        final PriorityQueueSpliterator<E> spliterator(int origin, int fence,
787                                                      int expectedModCount) {
788            return new PriorityQueueSpliterator<E>(this, origin, fence,
789                                                   expectedModCount);
790        }
791    
792        public Stream<E> stream() {
793            int flags = Streams.STREAM_IS_SIZED;
794            return Streams.stream
795                (() -> spliterator(0, size, modCount), flags);
796        }
797        public Stream<E> parallelStream() {
798            int flags = Streams.STREAM_IS_SIZED;
799            return Streams.parallelStream
800                (() -> spliterator(0, size, modCount), flags);
801        }
802    
803        /** Index-based split-by-two Spliterator */
804        static final class PriorityQueueSpliterator<E>
805            implements Spliterator<E>, Iterator<E> {
806            private final PriorityQueue<E> pq;
807            private int index;           // current index, modified on advance/split
808            private final int fence;     // one past last index
809            private final int expectedModCount; // for comodification checks
810    
811            /** Create new spliterator covering the given  range */
812            PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
813                                 int expectedModCount) {
814                this.pq = pq; this.index = origin; this.fence = fence;
815                this.expectedModCount = expectedModCount;
816            }
817    
818            public PriorityQueueSpliterator<E> trySplit() {
819                int lo = index, mid = (lo + fence) >>> 1;
820                return (lo >= mid) ? null :
821                    new PriorityQueueSpliterator<E>(pq, lo, index = mid,
822                                                expectedModCount);
823            }
824    
825            public void forEach(Block<? super E> block) {
826                Object[] a; int i, hi; // hoist accesses and checks from loop
827                if (block == null)
828                    throw new NullPointerException();
829                if ((a = pq.queue).length >= (hi = fence) &&
830                    (i = index) >= 0 && i < hi) {
831                    index = hi;
832                    do {
833                        @SuppressWarnings("unchecked") E e = (E) a[i];
834                        block.accept(e);
835                    } while (++i < hi);
836                    if (pq.modCount != expectedModCount)
837                        throw new ConcurrentModificationException();
838                }
839            }
840    
841            public boolean tryAdvance(Block<? super E> block) {
842                if (index >= 0 && index < fence) {
843                    if (pq.modCount != expectedModCount)
844                        throw new ConcurrentModificationException();
845                    @SuppressWarnings("unchecked") E e =
846                        (E)pq.queue[index++];
847                    block.accept(e);
848                    return true;
849                }
850                return false;
851            }
852    
853            public long estimateSize() { return (long)(fence - index); }
854            public boolean hasExactSize() { return true; }
855            public boolean hasExactSplits() { return true; }
856    
857            // Iterator support
858            public Iterator<E> iterator() { return this; }
859            public void remove() { throw new UnsupportedOperationException(); }
860            public boolean hasNext() { return index >= 0 && index < fence; }
861    
862            public E next() {
863                if (index < 0 || index >= fence)
864                    throw new NoSuchElementException();
865                if (pq.modCount != expectedModCount)
866                    throw new ConcurrentModificationException();
867                @SuppressWarnings("unchecked") E e =
868                    (E) pq.queue[index++];
869                return e;
870            }
871        }
872  }  }

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