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root/jsr166/jsr166/src/main/java/util/PriorityQueue.java

Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.80 by jsr166, Wed Jan 16 01:59:47 2013 UTC vs.
Revision 1.81 by dl, Wed Jan 16 15:06:10 2013 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
2	>	* 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		* 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.  Sun designates this
7	>	* published by the Free Software Foundation.  Oracle designates this
8		* particular file as subject to the "Classpath" exception as provided
9	<	* by Sun in the LICENSE file that accompanied this code.
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
#	Line 24 | Line 24
24		*/
25
26		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.
#	Line 56 | Line 60 | package java.util;
60		* the priority queue in any particular order. If you need ordered
61		* traversal, consider using {@code Arrays.sort(pq.toArray())}.
62		*
63	<	* <p><strong>Note that this implementation is not synchronized.</strong>
63	>	* <p> <strong>Note that this implementation is not synchronized.</strong>
64		* Multiple threads should not access a {@code PriorityQueue}
65		* instance concurrently if any of the threads modifies the queue.
66		* Instead, use the thread-safe {@link
67		* java.util.concurrent.PriorityBlockingQueue} class.
68		*
69		* <p>Implementation note: this implementation provides
70	<	* O(log(n)) time for the enqueuing and dequeuing methods
70	>	* O(log(n)) time for the enqueing and dequeing methods
71		* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
72		* linear time for the {@code remove(Object)} and {@code contains(Object)}
73		* methods; and constant time for the retrieval methods
#	Line 77 | Line 81 | package java.util;
81		* @author Josh Bloch, Doug Lea
82		* @param <E> the type of elements held in this collection
83		*/
80	–	@SuppressWarnings("unchecked")
84		public class PriorityQueue<E> extends AbstractQueue<E>
85		implements java.io.Serializable {
86
#	Line 93 | Line 96 | public class PriorityQueue<E> extends Ab
96		* 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.
98		*/
99	<	private transient Object[] queue;
99	>	transient Object[] queue; // non-private to simplify nested class access
100
101		/**
102		* The number of elements in the priority queue.
#	Line 110 | Line 113 | public class PriorityQueue<E> extends Ab
113		* The number of times this priority queue has been
114		* <i>structurally modified</i>.  See AbstractList for gory details.
115		*/
116	<	private transient int modCount = 0;
116	>	transient int modCount = 0; // non-private to simplify nested class access
117
118		/**
119		* Creates a {@code PriorityQueue} with the default initial
#	Line 331 | Line 334 | public class PriorityQueue<E> extends Ab
334		return true;
335		}
336
337	+	@SuppressWarnings("unchecked")
338		public E peek() {
339		return (size == 0) ? null : (E) queue[0];
340		}
#	Line 512 | Line 516 | public class PriorityQueue<E> extends Ab
516		(forgetMeNot != null && !forgetMeNot.isEmpty());
517		}
518
519	+	@SuppressWarnings("unchecked")
520		public E next() {
521		if (expectedModCount != modCount)
522		throw new ConcurrentModificationException();
#	Line 564 | Line 569 | public class PriorityQueue<E> extends Ab
569		size = 0;
570		}
571
572	+	@SuppressWarnings("unchecked")
573		public E poll() {
574		if (size == 0)
575		return null;
#	Line 589 | Line 595 | public class PriorityQueue<E> extends Ab
595		* position before i. This fact is used by iterator.remove so as to
596		* avoid missing traversing elements.
597		*/
598	+	@SuppressWarnings("unchecked")
599		private E removeAt(int i) {
600		// assert i >= 0 && i < size;
601		modCount++;
#	Line 627 | Line 634 | public class PriorityQueue<E> extends Ab
634		siftUpComparable(k, x);
635		}
636
637	+	@SuppressWarnings("unchecked")
638		private void siftUpComparable(int k, E x) {
639		Comparable<? super E> key = (Comparable<? super E>) x;
640		while (k > 0) {
#	Line 640 | Line 648 | public class PriorityQueue<E> extends Ab
648		queue[k] = key;
649		}
650
651	+	@SuppressWarnings("unchecked")
652		private void siftUpUsingComparator(int k, E x) {
653		while (k > 0) {
654		int parent = (k - 1) >>> 1;
#	Line 667 | Line 676 | public class PriorityQueue<E> extends Ab
676		siftDownComparable(k, x);
677		}
678
679	+	@SuppressWarnings("unchecked")
680		private void siftDownComparable(int k, E x) {
681		Comparable<? super E> key = (Comparable<? super E>)x;
682		int half = size >>> 1;        // loop while a non-leaf
#	Line 685 | Line 695 | public class PriorityQueue<E> extends Ab
695		queue[k] = key;
696		}
697
698	+	@SuppressWarnings("unchecked")
699		private void siftDownUsingComparator(int k, E x) {
700		int half = size >>> 1;
701		while (k < half) {
#	Line 706 | Line 717 | public class PriorityQueue<E> extends Ab
717		* Establishes the heap invariant (described above) in the entire tree,
718		* assuming nothing about the order of the elements prior to the call.
719		*/
720	+	@SuppressWarnings("unchecked")
721		private void heapify() {
722		for (int i = (size >>> 1) - 1; i >= 0; i--)
723		siftDown(i, (E) queue[i]);
#	Line 730 | Line 742 | public class PriorityQueue<E> extends Ab
742		* @serialData The length of the array backing the instance is
743		*             emitted (int), followed by all of its elements
744		*             (each an {@code Object}) in the proper order.
745	+	* @param s the stream
746		*/
747		private void writeObject(java.io.ObjectOutputStream s)
748		throws java.io.IOException {
#	Line 745 | Line 758 | public class PriorityQueue<E> extends Ab
758		}
759
760		/**
761	<	* Reconstitutes this queue from a stream (that is, deserializes it).
761	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
762	>	* (that is, deserializes it).
763	>	*
764	>	* @param s the stream
765		*/
766		private void readObject(java.io.ObjectInputStream s)
767		throws java.io.IOException, ClassNotFoundException {
#	Line 765 | Line 781 | public class PriorityQueue<E> extends Ab
781		// spec has never explained what that might be.
782		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(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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