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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.69 by jsr166, Sun May 18 23:59:57 2008 UTC vs.
Revision 1.113 by jsr166, Wed Nov 30 03:31:47 2016 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright 2003-2006 Sun Microsystems, Inc.  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 18 | Line 18
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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22	<	* CA 95054 USA or visit www.sun.com if you need additional information or
23	<	* have any questions.
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;
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 52 | Line 54 | package java.util;
54		* <p>This class and its iterator implement all of the
55		* <em>optional</em> methods of the {@link Collection} and {@link
56		* Iterator} interfaces.  The Iterator provided in method {@link
57	<	* #iterator()} is <em>not</em> guaranteed to traverse the elements of
57	>	* #iterator()} and the Spliterator provided in method {@link #spliterator()}
58	>	* are <em>not</em> guaranteed to traverse the elements of
59		* the priority queue in any particular order. If you need ordered
60		* traversal, consider using {@code Arrays.sort(pq.toArray())}.
61		*
62	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
62	>	* <p><strong>Note that this implementation is not synchronized.</strong>
63		* Multiple threads should not access a {@code PriorityQueue}
64		* instance concurrently if any of the threads modifies the queue.
65		* Instead, use the thread-safe {@link
66		* java.util.concurrent.PriorityBlockingQueue} class.
67		*
68		* <p>Implementation note: this implementation provides
69	<	* O(log(n)) time for the enqueing and dequeing methods
69	>	* O(log(n)) time for the enqueuing and dequeuing methods
70		* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
71		* linear time for the {@code remove(Object)} and {@code contains(Object)}
72		* methods; and constant time for the retrieval methods
#	Line 75 | Line 78 | package java.util;
78		*
79		* @since 1.5
80		* @author Josh Bloch, Doug Lea
81	<	* @param <E> the type of elements held in this collection
81	>	* @param <E> the type of elements held in this queue
82		*/
83		public class PriorityQueue<E> extends AbstractQueue<E>
84		implements java.io.Serializable {
#	Line 92 | Line 95 | public class PriorityQueue<E> extends Ab
95		* 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.
97		*/
98	<	private transient Object[] queue;
98	>	transient Object[] queue; // non-private to simplify nested class access
99
100		/**
101		* The number of elements in the priority queue.
102		*/
103	<	private int size = 0;
103	>	int size;
104
105		/**
106		* The comparator, or null if priority queue uses elements'
#	Line 109 | Line 112 | public class PriorityQueue<E> extends Ab
112		* The number of times this priority queue has been
113		* <i>structurally modified</i>.  See AbstractList for gory details.
114		*/
115	<	private transient int modCount = 0;
115	>	transient int modCount;     // non-private to simplify nested class access
116
117		/**
118		* Creates a {@code PriorityQueue} with the default initial
#	Line 134 | Line 137 | public class PriorityQueue<E> extends Ab
137		}
138
139		/**
140	+	* Creates a {@code PriorityQueue} with the default initial capacity and
141	+	* whose elements are ordered according to the specified comparator.
142	+	*
143	+	* @param  comparator the comparator that will be used to order this
144	+	*         priority queue.  If {@code null}, the {@linkplain Comparable
145	+	*         natural ordering} of the elements will be used.
146	+	* @since 1.8
147	+	*/
148	+	public PriorityQueue(Comparator<? super E> comparator) {
149	+	this(DEFAULT_INITIAL_CAPACITY, comparator);
150	+	}
151	+
152	+	/**
153		* Creates a {@code PriorityQueue} with the specified initial capacity
154		* that orders its elements according to the specified comparator.
155		*
#	Line 170 | Line 186 | public class PriorityQueue<E> extends Ab
186		* @throws NullPointerException if the specified collection or any
187		*         of its elements are null
188		*/
189	+	@SuppressWarnings("unchecked")
190		public PriorityQueue(Collection<? extends E> c) {
191	<	initFromCollection(c);
192	<	if (c instanceof SortedSet)
193	<	comparator = (Comparator<? super E>)
194	<	((SortedSet<? extends E>)c).comparator();
195	<	else if (c instanceof PriorityQueue)
196	<	comparator = (Comparator<? super E>)
197	<	((PriorityQueue<? extends E>)c).comparator();
191	>	if (c instanceof SortedSet<?>) {
192	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
193	>	this.comparator = (Comparator<? super E>) ss.comparator();
194	>	initElementsFromCollection(ss);
195	>	}
196	>	else if (c instanceof PriorityQueue<?>) {
197	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
198	>	this.comparator = (Comparator<? super E>) pq.comparator();
199	>	initFromPriorityQueue(pq);
200	>	}
201		else {
202	<	comparator = null;
203	<	heapify();
202	>	this.comparator = null;
203	>	initFromCollection(c);
204		}
205		}
206
#	Line 198 | Line 218 | public class PriorityQueue<E> extends Ab
218		* @throws NullPointerException if the specified priority queue or any
219		*         of its elements are null
220		*/
221	+	@SuppressWarnings("unchecked")
222		public PriorityQueue(PriorityQueue<? extends E> c) {
223	<	comparator = (Comparator<? super E>)c.comparator();
224	<	initFromCollection(c);
223	>	this.comparator = (Comparator<? super E>) c.comparator();
224	>	initFromPriorityQueue(c);
225		}
226
227		/**
#	Line 216 | 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		*/
240	+	@SuppressWarnings("unchecked")
241		public PriorityQueue(SortedSet<? extends E> c) {
242	<	comparator = (Comparator<? super E>)c.comparator();
243	<	initFromCollection(c);
242	>	this.comparator = (Comparator<? super E>) c.comparator();
243	>	initElementsFromCollection(c);
244	>	}
245	>
246	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
247	>	if (c.getClass() == PriorityQueue.class) {
248	>	this.queue = c.toArray();
249	>	this.size = c.size();
250	>	} else {
251	>	initFromCollection(c);
252	>	}
253	>	}
254	>
255	>	private void initElementsFromCollection(Collection<? extends E> c) {
256	>	Object[] a = c.toArray();
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);
260	>	int len = a.length;
261	>	if (len == 1 || this.comparator != null)
262	>	for (Object e : a)
263	>	if (e == null)
264	>	throw new NullPointerException();
265	>	this.queue = a;
266	>	this.size = a.length;
267		}
268
269		/**
#	Line 227 | Line 272 | public class PriorityQueue<E> extends Ab
272		* @param c the collection
273		*/
274		private void initFromCollection(Collection<? extends E> c) {
275	<	Object[] a = c.toArray();
276	<	// If c.toArray incorrectly doesn't return Object[], copy it.
232	<	if (a.getClass() != Object[].class)
233	<	a = Arrays.copyOf(a, a.length, Object[].class);
234	<	queue = a;
235	<	size = a.length;
275	>	initElementsFromCollection(c);
276	>	heapify();
277		}
278
279		/**
280	+	* The maximum size of array to allocate.
281	+	* Some VMs reserve some header words in an array.
282	+	* Attempts to allocate larger arrays may result in
283	+	* OutOfMemoryError: Requested array size exceeds VM limit
284	+	*/
285	+	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
286	+
287	+	/**
288		* Increases the capacity of the array.
289		*
290		* @param minCapacity the desired minimum capacity
291		*/
292		private void grow(int minCapacity) {
244	–	if (minCapacity < 0) // overflow
245	–	throw new OutOfMemoryError();
293		int oldCapacity = queue.length;
294		// Double size if small; else grow by 50%
295	<	int newCapacity = ((oldCapacity < 64)?
296	<	((oldCapacity + 1) * 2):
297	<	((oldCapacity / 2) * 3));
298	<	if (newCapacity < 0) // overflow
299	<	newCapacity = Integer.MAX_VALUE;
300	<	if (newCapacity < minCapacity)
254	<	newCapacity = minCapacity;
295	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
296	>	(oldCapacity + 2) :
297	>	(oldCapacity >> 1));
298	>	// overflow-conscious code
299	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
300	>	newCapacity = hugeCapacity(minCapacity);
301		queue = Arrays.copyOf(queue, newCapacity);
302		}
303
304	+	private static int hugeCapacity(int minCapacity) {
305	+	if (minCapacity < 0) // overflow
306	+	throw new OutOfMemoryError();
307	+	return (minCapacity > MAX_ARRAY_SIZE) ?
308	+	Integer.MAX_VALUE :
309	+	MAX_ARRAY_SIZE;
310	+	}
311	+
312		/**
313		* Inserts the specified element into this priority queue.
314		*
#	Line 284 | Line 338 | public class PriorityQueue<E> extends Ab
338		int i = size;
339		if (i >= queue.length)
340		grow(i + 1);
341	+	siftUp(i, e);
342		size = i + 1;
288	–	if (i == 0)
289	–	queue[0] = e;
290	–	else
291	–	siftUp(i, e);
343		return true;
344		}
345
346	+	@SuppressWarnings("unchecked")
347		public E peek() {
348	<	if (size == 0)
297	<	return null;
298	<	return (E) queue[0];
348	>	return (size == 0) ? null : (E) queue[0];
349		}
350
351		private int indexOf(Object o) {
#	Line 354 | Line 404 | public class PriorityQueue<E> extends Ab
404		* @return {@code true} if this queue contains the specified element
405		*/
406		public boolean contains(Object o) {
407	<	return indexOf(o) != -1;
407	>	return indexOf(o) >= 0;
408		}
409
410		/**
#	Line 392 | Line 442 | public class PriorityQueue<E> extends Ab
442		* precise control over the runtime type of the output array, and may,
443		* under certain circumstances, be used to save allocation costs.
444		*
445	<	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
445	>	* <p>Suppose {@code x} is a queue known to contain only strings.
446		* The following code can be used to dump the queue into a newly
447	<	* allocated array of <tt>String</tt>:
447	>	* allocated array of {@code String}:
448		*
449	<	* <pre>
400	<	*     String[] y = x.toArray(new String[0]);</pre>
449	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
450		*
451	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
452	<	* <tt>toArray()</tt>.
451	>	* Note that {@code toArray(new Object[0])} is identical in function to
452	>	* {@code toArray()}.
453		*
454		* @param a the array into which the elements of the queue are to
455		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 411 | Line 460 | public class PriorityQueue<E> extends Ab
460		*         this queue
461		* @throws NullPointerException if the specified array is null
462		*/
463	+	@SuppressWarnings("unchecked")
464		public <T> T[] toArray(T[] a) {
465	+	final int size = this.size;
466		if (a.length < size)
467		// Make a new array of a's runtime type, but my contents:
468		return (T[]) Arrays.copyOf(queue, size, a.getClass());
#	Line 436 | Line 487 | public class PriorityQueue<E> extends Ab
487		* Index (into queue array) of element to be returned by
488		* subsequent call to next.
489		*/
490	<	private int cursor = 0;
490	>	private int cursor;
491
492		/**
493		* Index of element returned by most recent call to next,
#	Line 456 | Line 507 | public class PriorityQueue<E> extends Ab
507		* We expect that most iterations, even those involving removals,
508		* will not need to store elements in this field.
509		*/
510	<	private ArrayDeque<E> forgetMeNot = null;
510	>	private ArrayDeque<E> forgetMeNot;
511
512		/**
513		* Element returned by the most recent call to next iff that
514		* element was drawn from the forgetMeNot list.
515		*/
516	<	private E lastRetElt = null;
516	>	private E lastRetElt;
517
518		/**
519		* The modCount value that the iterator believes that the backing
#	Line 476 | Line 527 | public class PriorityQueue<E> extends Ab
527		(forgetMeNot != null && !forgetMeNot.isEmpty());
528		}
529
530	+	@SuppressWarnings("unchecked")
531		public E next() {
532		if (expectedModCount != modCount)
533		throw new ConcurrentModificationException();
#	Line 500 | Line 552 | public class PriorityQueue<E> extends Ab
552		cursor--;
553		else {
554		if (forgetMeNot == null)
555	<	forgetMeNot = new ArrayDeque<E>();
555	>	forgetMeNot = new ArrayDeque<>();
556		forgetMeNot.add(moved);
557		}
558		} else if (lastRetElt != null) {
#	Line 528 | Line 580 | public class PriorityQueue<E> extends Ab
580		size = 0;
581		}
582
583	+	@SuppressWarnings("unchecked")
584		public E poll() {
585		if (size == 0)
586		return null;
#	Line 553 | Line 606 | public class PriorityQueue<E> extends Ab
606		* position before i. This fact is used by iterator.remove so as to
607		* avoid missing traversing elements.
608		*/
609	<	private E removeAt(int i) {
610	<	assert i >= 0 && i < size;
609	>	@SuppressWarnings("unchecked")
610	>	E removeAt(int i) {
611	>	// assert i >= 0 && i < size;
612		modCount++;
613		int s = --size;
614		if (s == i) // removed last element
#	Line 591 | Line 645 | public class PriorityQueue<E> extends Ab
645		siftUpComparable(k, x);
646		}
647
648	+	@SuppressWarnings("unchecked")
649		private void siftUpComparable(int k, E x) {
650		Comparable<? super E> key = (Comparable<? super E>) x;
651		while (k > 0) {
#	Line 604 | Line 659 | public class PriorityQueue<E> extends Ab
659		queue[k] = key;
660		}
661
662	+	@SuppressWarnings("unchecked")
663		private void siftUpUsingComparator(int k, E x) {
664		while (k > 0) {
665		int parent = (k - 1) >>> 1;
#	Line 631 | Line 687 | public class PriorityQueue<E> extends Ab
687		siftDownComparable(k, x);
688		}
689
690	+	@SuppressWarnings("unchecked")
691		private void siftDownComparable(int k, E x) {
692		Comparable<? super E> key = (Comparable<? super E>)x;
693		int half = size >>> 1;        // loop while a non-leaf
#	Line 649 | Line 706 | public class PriorityQueue<E> extends Ab
706		queue[k] = key;
707		}
708
709	+	@SuppressWarnings("unchecked")
710		private void siftDownUsingComparator(int k, E x) {
711		int half = size >>> 1;
712		while (k < half) {
#	Line 669 | Line 727 | public class PriorityQueue<E> extends Ab
727		/**
728		* Establishes the heap invariant (described above) in the entire tree,
729		* assuming nothing about the order of the elements prior to the call.
730	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
731		*/
732	+	@SuppressWarnings("unchecked")
733		private void heapify() {
734		for (int i = (size >>> 1) - 1; i >= 0; i--)
735		siftDown(i, (E) queue[i]);
#	Line 689 | Line 749 | public class PriorityQueue<E> extends Ab
749		}
750
751		/**
752	<	* Saves the state of the instance to a stream (that
693	<	* is, serializes it).
752	>	* Saves this queue to a stream (that is, serializes it).
753		*
754	+	* @param s the stream
755	+	* @throws java.io.IOException if an I/O error occurs
756		* @serialData The length of the array backing the instance is
757		*             emitted (int), followed by all of its elements
758		*             (each an {@code Object}) in the proper order.
698	–	* @param s the stream
759		*/
760		private void writeObject(java.io.ObjectOutputStream s)
761	<	throws java.io.IOException{
761	>	throws java.io.IOException {
762		// Write out element count, and any hidden stuff
763		s.defaultWriteObject();
764
#	Line 715 | Line 775 | public class PriorityQueue<E> extends Ab
775		* (that is, deserializes it).
776		*
777		* @param s the stream
778	+	* @throws ClassNotFoundException if the class of a serialized object
779	+	*         could not be found
780	+	* @throws java.io.IOException if an I/O error occurs
781		*/
782		private void readObject(java.io.ObjectInputStream s)
783		throws java.io.IOException, ClassNotFoundException {
#	Line 734 | Line 797 | public class PriorityQueue<E> extends Ab
797		// spec has never explained what that might be.
798		heapify();
799		}
800	+
801	+	/**
802	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
803	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
804	+	* queue. The spliterator does not traverse elements in any particular order
805	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
806	+	*
807	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
808	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
809	+	* Overriding implementations should document the reporting of additional
810	+	* characteristic values.
811	+	*
812	+	* @return a {@code Spliterator} over the elements in this queue
813	+	* @since 1.8
814	+	*/
815	+	public final Spliterator<E> spliterator() {
816	+	return new PriorityQueueSpliterator(0, -1, 0);
817	+	}
818	+
819	+	final class PriorityQueueSpliterator implements Spliterator<E> {
820	+	/*
821	+	* This is very similar to ArrayList Spliterator, except for
822	+	* extra null checks.
823	+	*/
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(int origin, int fence, int expectedModCount) {
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 = modCount;
839	+	hi = fence = size;
840	+	}
841	+	return hi;
842	+	}
843	+
844	+	public PriorityQueueSpliterator trySplit() {
845	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
846	+	return (lo >= mid) ? null :
847	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
848	+	}
849	+
850	+	@SuppressWarnings("unchecked")
851	+	public void forEachRemaining(Consumer<? super E> action) {
852	+	int i, hi, mc; // hoist accesses and checks from loop
853	+	final Object[] a;
854	+	if (action == null)
855	+	throw new NullPointerException();
856	+	if ((a = queue) != null) {
857	+	if ((hi = fence) < 0) {
858	+	mc = modCount;
859	+	hi = size;
860	+	}
861	+	else
862	+	mc = expectedModCount;
863	+	if ((i = index) >= 0 && (index = hi) <= a.length) {
864	+	for (E e;; ++i) {
865	+	if (i < hi) {
866	+	if ((e = (E) a[i]) == null) // must be CME
867	+	break;
868	+	action.accept(e);
869	+	}
870	+	else if (modCount != mc)
871	+	break;
872	+	else
873	+	return;
874	+	}
875	+	}
876	+	}
877	+	throw new ConcurrentModificationException();
878	+	}
879	+
880	+	public boolean tryAdvance(Consumer<? super E> action) {
881	+	if (action == null)
882	+	throw new NullPointerException();
883	+	int hi = getFence(), lo = index;
884	+	if (lo >= 0 && lo < hi) {
885	+	index = lo + 1;
886	+	@SuppressWarnings("unchecked") E e = (E)queue[lo];
887	+	if (e == null)
888	+	throw new ConcurrentModificationException();
889	+	action.accept(e);
890	+	if (modCount != expectedModCount)
891	+	throw new ConcurrentModificationException();
892	+	return true;
893	+	}
894	+	return false;
895	+	}
896	+
897	+	public long estimateSize() {
898	+	return getFence() - index;
899	+	}
900	+
901	+	public int characteristics() {
902	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
903	+	}
904	+	}
905		}

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