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

Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.77 by jsr166, Mon Dec 12 20:53:11 2011 UTC vs.
Revision 1.110 by jsr166, Wed Aug 24 21:46:18 2016 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
2	>	* Copyright (c) 2003, 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.  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 25 | Line 25
25
26		package java.util;
27
28	+	import java.util.function.Consumer;
29	+
30		/**
31		* An unbounded priority {@linkplain Queue queue} based on a priority heap.
32		* The elements of the priority queue are ordered according to their
#	Line 56 | Line 58 | package java.util;
58		* the priority queue in any particular order. If you need ordered
59		* traversal, consider using {@code Arrays.sort(pq.toArray())}.
60		*
61	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
61	>	* <p><strong>Note that this implementation is not synchronized.</strong>
62		* Multiple threads should not access a {@code PriorityQueue}
63		* instance concurrently if any of the threads modifies the queue.
64		* Instead, use the thread-safe {@link
65		* java.util.concurrent.PriorityBlockingQueue} class.
66		*
67		* <p>Implementation note: this implementation provides
68	<	* O(log(n)) time for the enqueing and dequeing methods
68	>	* O(log(n)) time for the enqueuing and dequeuing methods
69		* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
70		* linear time for the {@code remove(Object)} and {@code contains(Object)}
71		* methods; and constant time for the retrieval methods
#	Line 75 | Line 77 | package java.util;
77		*
78		* @since 1.5
79		* @author Josh Bloch, Doug Lea
80	<	* @param <E> the type of elements held in this collection
80	>	* @param <E> the type of elements held in this queue
81		*/
80	–	@SuppressWarnings("unchecked")
82		public class PriorityQueue<E> extends AbstractQueue<E>
83		implements java.io.Serializable {
84
#	Line 93 | Line 94 | public class PriorityQueue<E> extends Ab
94		* heap and each descendant d of n, n <= d.  The element with the
95		* lowest value is in queue[0], assuming the queue is nonempty.
96		*/
97	<	private transient Object[] queue;
97	>	transient Object[] queue; // non-private to simplify nested class access
98
99		/**
100		* The number of elements in the priority queue.
101		*/
102	<	private int size = 0;
102	>	int size;
103
104		/**
105		* The comparator, or null if priority queue uses elements'
#	Line 110 | Line 111 | public class PriorityQueue<E> extends Ab
111		* The number of times this priority queue has been
112		* <i>structurally modified</i>.  See AbstractList for gory details.
113		*/
114	<	private transient int modCount = 0;
114	>	transient int modCount;     // non-private to simplify nested class access
115
116		/**
117		* Creates a {@code PriorityQueue} with the default initial
#	Line 135 | Line 136 | public class PriorityQueue<E> extends Ab
136		}
137
138		/**
139	+	* Creates a {@code PriorityQueue} with the default initial capacity and
140	+	* whose elements are ordered according to the specified comparator.
141	+	*
142	+	* @param  comparator the comparator that will be used to order this
143	+	*         priority queue.  If {@code null}, the {@linkplain Comparable
144	+	*         natural ordering} of the elements will be used.
145	+	* @since 1.8
146	+	*/
147	+	public PriorityQueue(Comparator<? super E> comparator) {
148	+	this(DEFAULT_INITIAL_CAPACITY, comparator);
149	+	}
150	+
151	+	/**
152		* Creates a {@code PriorityQueue} with the specified initial capacity
153		* that orders its elements according to the specified comparator.
154		*
#	Line 244 | Line 258 | public class PriorityQueue<E> extends Ab
258		a = Arrays.copyOf(a, a.length, Object[].class);
259		int len = a.length;
260		if (len == 1 || this.comparator != null)
261	<	for (int i = 0; i < len; i++)
262	<	if (a[i] == null)
261	>	for (Object e : a)
262	>	if (e == null)
263		throw new NullPointerException();
264		this.queue = a;
265		this.size = a.length;
#	Line 323 | Line 337 | public class PriorityQueue<E> extends Ab
337		int i = size;
338		if (i >= queue.length)
339		grow(i + 1);
340	+	siftUp(i, e);
341		size = i + 1;
327	–	if (i == 0)
328	–	queue[0] = e;
329	–	else
330	–	siftUp(i, e);
342		return true;
343		}
344
345	+	@SuppressWarnings("unchecked")
346		public E peek() {
347		return (size == 0) ? null : (E) queue[0];
348		}
#	Line 391 | Line 403 | public class PriorityQueue<E> extends Ab
403		* @return {@code true} if this queue contains the specified element
404		*/
405		public boolean contains(Object o) {
406	<	return indexOf(o) != -1;
406	>	return indexOf(o) >= 0;
407		}
408
409		/**
#	Line 429 | Line 441 | public class PriorityQueue<E> extends Ab
441		* precise control over the runtime type of the output array, and may,
442		* under certain circumstances, be used to save allocation costs.
443		*
444	<	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
444	>	* <p>Suppose {@code x} is a queue known to contain only strings.
445		* The following code can be used to dump the queue into a newly
446	<	* allocated array of <tt>String</tt>:
446	>	* allocated array of {@code String}:
447		*
448	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
448	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
449		*
450	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
451	<	* <tt>toArray()</tt>.
450	>	* Note that {@code toArray(new Object[0])} is identical in function to
451	>	* {@code toArray()}.
452		*
453		* @param a the array into which the elements of the queue are to
454		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 447 | Line 459 | public class PriorityQueue<E> extends Ab
459		*         this queue
460		* @throws NullPointerException if the specified array is null
461		*/
462	+	@SuppressWarnings("unchecked")
463		public <T> T[] toArray(T[] a) {
464	+	final int size = this.size;
465		if (a.length < size)
466		// Make a new array of a's runtime type, but my contents:
467		return (T[]) Arrays.copyOf(queue, size, a.getClass());
#	Line 472 | Line 486 | public class PriorityQueue<E> extends Ab
486		* Index (into queue array) of element to be returned by
487		* subsequent call to next.
488		*/
489	<	private int cursor = 0;
489	>	private int cursor;
490
491		/**
492		* Index of element returned by most recent call to next,
#	Line 492 | Line 506 | public class PriorityQueue<E> extends Ab
506		* We expect that most iterations, even those involving removals,
507		* will not need to store elements in this field.
508		*/
509	<	private ArrayDeque<E> forgetMeNot = null;
509	>	private ArrayDeque<E> forgetMeNot;
510
511		/**
512		* Element returned by the most recent call to next iff that
513		* element was drawn from the forgetMeNot list.
514		*/
515	<	private E lastRetElt = null;
515	>	private E lastRetElt;
516
517		/**
518		* The modCount value that the iterator believes that the backing
#	Line 512 | Line 526 | public class PriorityQueue<E> extends Ab
526		(forgetMeNot != null && !forgetMeNot.isEmpty());
527		}
528
529	+	@SuppressWarnings("unchecked")
530		public E next() {
531		if (expectedModCount != modCount)
532		throw new ConcurrentModificationException();
#	Line 536 | Line 551 | public class PriorityQueue<E> extends Ab
551		cursor--;
552		else {
553		if (forgetMeNot == null)
554	<	forgetMeNot = new ArrayDeque<E>();
554	>	forgetMeNot = new ArrayDeque<>();
555		forgetMeNot.add(moved);
556		}
557		} else if (lastRetElt != null) {
#	Line 564 | Line 579 | public class PriorityQueue<E> extends Ab
579		size = 0;
580		}
581
582	+	@SuppressWarnings("unchecked")
583		public E poll() {
584		if (size == 0)
585		return null;
#	Line 589 | Line 605 | public class PriorityQueue<E> extends Ab
605		* position before i. This fact is used by iterator.remove so as to
606		* avoid missing traversing elements.
607		*/
608	<	private E removeAt(int i) {
608	>	@SuppressWarnings("unchecked")
609	>	E removeAt(int i) {
610		// assert i >= 0 && i < size;
611		modCount++;
612		int s = --size;
#	Line 627 | Line 644 | public class PriorityQueue<E> extends Ab
644		siftUpComparable(k, x);
645		}
646
647	+	@SuppressWarnings("unchecked")
648		private void siftUpComparable(int k, E x) {
649		Comparable<? super E> key = (Comparable<? super E>) x;
650		while (k > 0) {
#	Line 640 | Line 658 | public class PriorityQueue<E> extends Ab
658		queue[k] = key;
659		}
660
661	+	@SuppressWarnings("unchecked")
662		private void siftUpUsingComparator(int k, E x) {
663		while (k > 0) {
664		int parent = (k - 1) >>> 1;
#	Line 667 | Line 686 | public class PriorityQueue<E> extends Ab
686		siftDownComparable(k, x);
687		}
688
689	+	@SuppressWarnings("unchecked")
690		private void siftDownComparable(int k, E x) {
691		Comparable<? super E> key = (Comparable<? super E>)x;
692		int half = size >>> 1;        // loop while a non-leaf
#	Line 685 | Line 705 | public class PriorityQueue<E> extends Ab
705		queue[k] = key;
706		}
707
708	+	@SuppressWarnings("unchecked")
709		private void siftDownUsingComparator(int k, E x) {
710		int half = size >>> 1;
711		while (k < half) {
#	Line 706 | Line 727 | public class PriorityQueue<E> extends Ab
727		* Establishes the heap invariant (described above) in the entire tree,
728		* assuming nothing about the order of the elements prior to the call.
729		*/
730	+	@SuppressWarnings("unchecked")
731		private void heapify() {
732		for (int i = (size >>> 1) - 1; i >= 0; i--)
733		siftDown(i, (E) queue[i]);
#	Line 727 | Line 749 | public class PriorityQueue<E> extends Ab
749		/**
750		* Saves this queue to a stream (that is, serializes it).
751		*
752	+	* @param s the stream
753	+	* @throws java.io.IOException if an I/O error occurs
754		* @serialData The length of the array backing the instance is
755		*             emitted (int), followed by all of its elements
756		*             (each an {@code Object}) in the proper order.
#	Line 745 | Line 769 | public class PriorityQueue<E> extends Ab
769		}
770
771		/**
772	<	* Reconstitutes this queue from a stream (that is, deserializes it).
772	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
773	>	* (that is, deserializes it).
774	>	*
775	>	* @param s the stream
776	>	* @throws ClassNotFoundException if the class of a serialized object
777	>	*         could not be found
778	>	* @throws java.io.IOException if an I/O error occurs
779		*/
780		private void readObject(java.io.ObjectInputStream s)
781		throws java.io.IOException, ClassNotFoundException {
#	Line 765 | Line 795 | public class PriorityQueue<E> extends Ab
795		// spec has never explained what that might be.
796		heapify();
797		}
798	+
799	+	/**
800	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
801	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
802	+	* queue.
803	+	*
804	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
805	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
806	+	* Overriding implementations should document the reporting of additional
807	+	* characteristic values.
808	+	*
809	+	* @return a {@code Spliterator} over the elements in this queue
810	+	* @since 1.8
811	+	*/
812	+	public final Spliterator<E> spliterator() {
813	+	return new PriorityQueueSpliterator<>(this, 0, -1, 0);
814	+	}
815	+
816	+	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;
822	+	private int index;            // current index, modified on advance/split
823	+	private int fence;            // -1 until first use
824	+	private int expectedModCount; // initialized when fence set
825	+
826	+	/** Creates new spliterator covering the given range. */
827	+	PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
828	+	int expectedModCount) {
829	+	this.pq = pq;
830	+	this.index = origin;
831	+	this.fence = fence;
832	+	this.expectedModCount = expectedModCount;
833	+	}
834	+
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;
840	+	}
841	+	return hi;
842	+	}
843	+
844	+	public PriorityQueueSpliterator<E> 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);
849	+	}
850	+
851	+	@SuppressWarnings("unchecked")
852	+	public void forEachRemaining(Consumer<? super E> action) {
853	+	int i, hi, mc; // hoist accesses and checks from loop
854	+	PriorityQueue<E> q; Object[] a;
855	+	if (action == null)
856	+	throw new NullPointerException();
857	+	if ((q = pq) != null && (a = q.queue) != null) {
858	+	if ((hi = fence) < 0) {
859	+	mc = q.modCount;
860	+	hi = q.size;
861	+	}
862	+	else
863	+	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	+	}
877	+	}
878	+	throw new ConcurrentModificationException();
879	+	}
880	+
881	+	public boolean tryAdvance(Consumer<? super E> action) {
882	+	if (action == null)
883	+	throw new NullPointerException();
884	+	int hi = getFence(), lo = index;
885	+	if (lo >= 0 && lo < hi) {
886	+	index = lo + 1;
887	+	@SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
888	+	if (e == null)
889	+	throw new ConcurrentModificationException();
890	+	action.accept(e);
891	+	if (pq.modCount != expectedModCount)
892	+	throw new ConcurrentModificationException();
893	+	return true;
894	+	}
895	+	return false;
896	+	}
897	+
898	+	public long estimateSize() {
899	+	return (long) (getFence() - index);
900	+	}
901	+
902	+	public int characteristics() {
903	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
904	+	}
905	+	}
906		}

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