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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.66 by jsr166, Sun Jan 7 07:38:27 2007 UTC vs.
Revision 1.107 by jsr166, Sun Sep 20 16:20:21 2015 UTC

#	Line 1 | Line 1
1		/*
2	<	* %W% %E%
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	<	* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
6	<	* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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.  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;
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 38 | 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 56 | Line 76 | package java.util;
76		* Java Collections Framework</a>.
77		*
78		* @since 1.5
59	–	* @version %I%, %G%
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		*/
82		public class PriorityQueue<E> extends AbstractQueue<E>
83		implements java.io.Serializable {
#	Line 75 | 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 92 | 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 117 | 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 153 | Line 185 | public class PriorityQueue<E> extends Ab
185		* @throws NullPointerException if the specified collection or any
186		*         of its elements are null
187		*/
188	+	@SuppressWarnings("unchecked")
189		public PriorityQueue(Collection<? extends E> c) {
190	<	initFromCollection(c);
191	<	if (c instanceof SortedSet)
192	<	comparator = (Comparator<? super E>)
193	<	((SortedSet<? extends E>)c).comparator();
194	<	else if (c instanceof PriorityQueue)
195	<	comparator = (Comparator<? super E>)
196	<	((PriorityQueue<? extends E>)c).comparator();
190	>	if (c instanceof SortedSet<?>) {
191	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
192	>	this.comparator = (Comparator<? super E>) ss.comparator();
193	>	initElementsFromCollection(ss);
194	>	}
195	>	else if (c instanceof PriorityQueue<?>) {
196	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
197	>	this.comparator = (Comparator<? super E>) pq.comparator();
198	>	initFromPriorityQueue(pq);
199	>	}
200		else {
201	<	comparator = null;
202	<	heapify();
201	>	this.comparator = null;
202	>	initFromCollection(c);
203		}
204		}
205
#	Line 181 | Line 217 | public class PriorityQueue<E> extends Ab
217		* @throws NullPointerException if the specified priority queue or any
218		*         of its elements are null
219		*/
220	+	@SuppressWarnings("unchecked")
221		public PriorityQueue(PriorityQueue<? extends E> c) {
222	<	comparator = (Comparator<? super E>)c.comparator();
223	<	initFromCollection(c);
222	>	this.comparator = (Comparator<? super E>) c.comparator();
223	>	initFromPriorityQueue(c);
224		}
225
226		/**
#	Line 199 | Line 236 | public class PriorityQueue<E> extends Ab
236		* @throws NullPointerException if the specified sorted set or any
237		*         of its elements are null
238		*/
239	+	@SuppressWarnings("unchecked")
240		public PriorityQueue(SortedSet<? extends E> c) {
241	<	comparator = (Comparator<? super E>)c.comparator();
242	<	initFromCollection(c);
241	>	this.comparator = (Comparator<? super E>) c.comparator();
242	>	initElementsFromCollection(c);
243	>	}
244	>
245	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
246	>	if (c.getClass() == PriorityQueue.class) {
247	>	this.queue = c.toArray();
248	>	this.size = c.size();
249	>	} else {
250	>	initFromCollection(c);
251	>	}
252	>	}
253	>
254	>	private void initElementsFromCollection(Collection<? extends E> c) {
255	>	Object[] a = c.toArray();
256	>	// If c.toArray incorrectly doesn't return Object[], copy it.
257	>	if (a.getClass() != Object[].class)
258	>	a = Arrays.copyOf(a, a.length, Object[].class);
259	>	int len = a.length;
260	>	if (len == 1 || this.comparator != null)
261	>	for (Object e : a)
262	>	if (e == null)
263	>	throw new NullPointerException();
264	>	this.queue = a;
265	>	this.size = a.length;
266		}
267
268		/**
#	Line 210 | Line 271 | public class PriorityQueue<E> extends Ab
271		* @param c the collection
272		*/
273		private void initFromCollection(Collection<? extends E> c) {
274	<	Object[] a = c.toArray();
275	<	// If c.toArray incorrectly doesn't return Object[], copy it.
215	<	if (a.getClass() != Object[].class)
216	<	a = Arrays.copyOf(a, a.length, Object[].class);
217	<	queue = a;
218	<	size = a.length;
274	>	initElementsFromCollection(c);
275	>	heapify();
276		}
277
278		/**
279	+	* The maximum size of array to allocate.
280	+	* Some VMs reserve some header words in an array.
281	+	* Attempts to allocate larger arrays may result in
282	+	* OutOfMemoryError: Requested array size exceeds VM limit
283	+	*/
284	+	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
285	+
286	+	/**
287		* Increases the capacity of the array.
288		*
289		* @param minCapacity the desired minimum capacity
290		*/
291		private void grow(int minCapacity) {
292	<	if (minCapacity < 0) // overflow
228	<	throw new OutOfMemoryError();
229	<	int oldCapacity = queue.length;
292	>	int oldCapacity = queue.length;
293		// Double size if small; else grow by 50%
294	<	int newCapacity = ((oldCapacity < 64)?
295	<	((oldCapacity + 1) * 2):
296	<	((oldCapacity / 2) * 3));
297	<	if (newCapacity < 0) // overflow
298	<	newCapacity = Integer.MAX_VALUE;
299	<	if (newCapacity < minCapacity)
237	<	newCapacity = minCapacity;
294	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
295	>	(oldCapacity + 2) :
296	>	(oldCapacity >> 1));
297	>	// overflow-conscious code
298	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
299	>	newCapacity = hugeCapacity(minCapacity);
300		queue = Arrays.copyOf(queue, newCapacity);
301		}
302
303	+	private static int hugeCapacity(int minCapacity) {
304	+	if (minCapacity < 0) // overflow
305	+	throw new OutOfMemoryError();
306	+	return (minCapacity > MAX_ARRAY_SIZE) ?
307	+	Integer.MAX_VALUE :
308	+	MAX_ARRAY_SIZE;
309	+	}
310	+
311		/**
312		* Inserts the specified element into this priority queue.
313		*
#	Line 275 | Line 345 | public class PriorityQueue<E> extends Ab
345		return true;
346		}
347
348	+	@SuppressWarnings("unchecked")
349		public E peek() {
350	<	if (size == 0)
280	<	return null;
281	<	return (E) queue[0];
350	>	return (size == 0) ? null : (E) queue[0];
351		}
352
353		private int indexOf(Object o) {
354	<	if (o != null) {
354	>	if (o != null) {
355		for (int i = 0; i < size; i++)
356		if (o.equals(queue[i]))
357		return i;
#	Line 302 | Line 371 | public class PriorityQueue<E> extends Ab
371		* @return {@code true} if this queue changed as a result of the call
372		*/
373		public boolean remove(Object o) {
374	<	int i = indexOf(o);
375	<	if (i == -1)
376	<	return false;
377	<	else {
378	<	removeAt(i);
379	<	return true;
380	<	}
374	>	int i = indexOf(o);
375	>	if (i == -1)
376	>	return false;
377	>	else {
378	>	removeAt(i);
379	>	return true;
380	>	}
381		}
382
383		/**
#	Line 319 | Line 388 | public class PriorityQueue<E> extends Ab
388		* @return {@code true} if removed
389		*/
390		boolean removeEq(Object o) {
391	<	for (int i = 0; i < size; i++) {
392	<	if (o == queue[i]) {
391	>	for (int i = 0; i < size; i++) {
392	>	if (o == queue[i]) {
393		removeAt(i);
394		return true;
395		}
#	Line 337 | Line 406 | public class PriorityQueue<E> extends Ab
406		* @return {@code true} if this queue contains the specified element
407		*/
408		public boolean contains(Object o) {
409	<	return indexOf(o) != -1;
409	>	return indexOf(o) >= 0;
410		}
411
412		/**
#	Line 375 | Line 444 | public class PriorityQueue<E> extends Ab
444		* precise control over the runtime type of the output array, and may,
445		* under certain circumstances, be used to save allocation costs.
446		*
447	<	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
447	>	* <p>Suppose {@code x} is a queue known to contain only strings.
448		* The following code can be used to dump the queue into a newly
449	<	* allocated array of <tt>String</tt>:
449	>	* allocated array of {@code String}:
450		*
451	<	* <pre>
383	<	*     String[] y = x.toArray(new String[0]);</pre>
451	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
452		*
453	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
454	<	* <tt>toArray()</tt>.
453	>	* Note that {@code toArray(new Object[0])} is identical in function to
454	>	* {@code toArray()}.
455		*
456		* @param a the array into which the elements of the queue are to
457		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 394 | Line 462 | public class PriorityQueue<E> extends Ab
462		*         this queue
463		* @throws NullPointerException if the specified array is null
464		*/
465	+	@SuppressWarnings("unchecked")
466		public <T> T[] toArray(T[] a) {
467	+	final int size = this.size;
468		if (a.length < size)
469		// Make a new array of a's runtime type, but my contents:
470		return (T[]) Arrays.copyOf(queue, size, a.getClass());
471	<	System.arraycopy(queue, 0, a, 0, size);
471	>	System.arraycopy(queue, 0, a, 0, size);
472		if (a.length > size)
473		a[size] = null;
474		return a;
#	Line 419 | Line 489 | public class PriorityQueue<E> extends Ab
489		* Index (into queue array) of element to be returned by
490		* subsequent call to next.
491		*/
492	<	private int cursor = 0;
492	>	private int cursor;
493
494		/**
495		* Index of element returned by most recent call to next,
#	Line 439 | Line 509 | public class PriorityQueue<E> extends Ab
509		* We expect that most iterations, even those involving removals,
510		* will not need to store elements in this field.
511		*/
512	<	private ArrayDeque<E> forgetMeNot = null;
512	>	private ArrayDeque<E> forgetMeNot;
513
514		/**
515		* Element returned by the most recent call to next iff that
516		* element was drawn from the forgetMeNot list.
517		*/
518	<	private E lastRetElt = null;
518	>	private E lastRetElt;
519
520		/**
521		* The modCount value that the iterator believes that the backing
#	Line 459 | Line 529 | public class PriorityQueue<E> extends Ab
529		(forgetMeNot != null && !forgetMeNot.isEmpty());
530		}
531
532	+	@SuppressWarnings("unchecked")
533		public E next() {
534		if (expectedModCount != modCount)
535		throw new ConcurrentModificationException();
#	Line 483 | Line 554 | public class PriorityQueue<E> extends Ab
554		cursor--;
555		else {
556		if (forgetMeNot == null)
557	<	forgetMeNot = new ArrayDeque<E>();
557	>	forgetMeNot = new ArrayDeque<>();
558		forgetMeNot.add(moved);
559		}
560		} else if (lastRetElt != null) {
#	Line 491 | Line 562 | public class PriorityQueue<E> extends Ab
562		lastRetElt = null;
563		} else {
564		throw new IllegalStateException();
565	<	}
565	>	}
566		expectedModCount = modCount;
567		}
568		}
#	Line 511 | Line 582 | public class PriorityQueue<E> extends Ab
582		size = 0;
583		}
584
585	+	@SuppressWarnings("unchecked")
586		public E poll() {
587		if (size == 0)
588		return null;
#	Line 536 | Line 608 | public class PriorityQueue<E> extends Ab
608		* position before i. This fact is used by iterator.remove so as to
609		* avoid missing traversing elements.
610		*/
611	<	private E removeAt(int i) {
612	<	assert i >= 0 && i < size;
611	>	@SuppressWarnings("unchecked")
612	>	E removeAt(int i) {
613	>	// assert i >= 0 && i < size;
614		modCount++;
615		int s = --size;
616		if (s == i) // removed last element
#	Line 574 | Line 647 | public class PriorityQueue<E> extends Ab
647		siftUpComparable(k, x);
648		}
649
650	+	@SuppressWarnings("unchecked")
651		private void siftUpComparable(int k, E x) {
652		Comparable<? super E> key = (Comparable<? super E>) x;
653		while (k > 0) {
#	Line 587 | Line 661 | public class PriorityQueue<E> extends Ab
661		queue[k] = key;
662		}
663
664	+	@SuppressWarnings("unchecked")
665		private void siftUpUsingComparator(int k, E x) {
666		while (k > 0) {
667		int parent = (k - 1) >>> 1;
#	Line 614 | Line 689 | public class PriorityQueue<E> extends Ab
689		siftDownComparable(k, x);
690		}
691
692	+	@SuppressWarnings("unchecked")
693		private void siftDownComparable(int k, E x) {
694		Comparable<? super E> key = (Comparable<? super E>)x;
695		int half = size >>> 1;        // loop while a non-leaf
#	Line 632 | Line 708 | public class PriorityQueue<E> extends Ab
708		queue[k] = key;
709		}
710
711	+	@SuppressWarnings("unchecked")
712		private void siftDownUsingComparator(int k, E x) {
713		int half = size >>> 1;
714		while (k < half) {
#	Line 653 | Line 730 | public class PriorityQueue<E> extends Ab
730		* Establishes the heap invariant (described above) in the entire tree,
731		* assuming nothing about the order of the elements prior to the call.
732		*/
733	+	@SuppressWarnings("unchecked")
734		private void heapify() {
735		for (int i = (size >>> 1) - 1; i >= 0; i--)
736		siftDown(i, (E) queue[i]);
#	Line 672 | Line 750 | public class PriorityQueue<E> extends Ab
750		}
751
752		/**
753	<	* Saves the state of the instance to a stream (that
676	<	* is, serializes it).
753	>	* Saves this queue to a stream (that is, serializes it).
754		*
755		* @serialData The length of the array backing the instance is
756		*             emitted (int), followed by all of its elements
757		*             (each an {@code Object}) in the proper order.
758		* @param s the stream
759	+	* @throws java.io.IOException if an I/O error occurs
760		*/
761		private void writeObject(java.io.ObjectOutputStream s)
762	<	throws java.io.IOException{
762	>	throws java.io.IOException {
763		// Write out element count, and any hidden stuff
764		s.defaultWriteObject();
765
#	Line 698 | Line 776 | public class PriorityQueue<E> extends Ab
776		* (that is, deserializes it).
777		*
778		* @param s the stream
779	+	* @throws ClassNotFoundException if the class of a serialized object
780	+	*         could not be found
781	+	* @throws java.io.IOException if an I/O error occurs
782		*/
783		private void readObject(java.io.ObjectInputStream s)
784		throws java.io.IOException, ClassNotFoundException {
#	Line 707 | Line 788 | public class PriorityQueue<E> extends Ab
788		// Read in (and discard) array length
789		s.readInt();
790
791	<	queue = new Object[size];
791	>	queue = new Object[size];
792
793		// Read in all elements.
794		for (int i = 0; i < size; i++)
795		queue[i] = s.readObject();
796
797	<	// Elements are guaranteed to be in "proper order", but the
798	<	// spec has never explained what that might be.
799	<	heapify();
797	>	// Elements are guaranteed to be in "proper order", but the
798	>	// spec has never explained what that might be.
799	>	heapify();
800	>	}
801	>
802	>	/**
803	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
804	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
805	>	* queue.
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<>(this, 0, -1, 0);
817	>	}
818	>
819	>	static final class PriorityQueueSpliterator<E> implements Spliterator<E> {
820	>	/*
821	>	* This is very similar to ArrayList Spliterator, except for
822	>	* extra null checks.
823	>	*/
824	>	private final PriorityQueue<E> pq;
825	>	private int index;            // current index, modified on advance/split
826	>	private int fence;            // -1 until first use
827	>	private int expectedModCount; // initialized when fence set
828	>
829	>	/** Creates new spliterator covering the given range */
830	>	PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
831	>	int expectedModCount) {
832	>	this.pq = pq;
833	>	this.index = origin;
834	>	this.fence = fence;
835	>	this.expectedModCount = expectedModCount;
836	>	}
837	>
838	>	private int getFence() { // initialize fence to size on first use
839	>	int hi;
840	>	if ((hi = fence) < 0) {
841	>	expectedModCount = pq.modCount;
842	>	hi = fence = pq.size;
843	>	}
844	>	return hi;
845	>	}
846	>
847	>	public PriorityQueueSpliterator<E> trySplit() {
848	>	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
849	>	return (lo >= mid) ? null :
850	>	new PriorityQueueSpliterator<>(pq, lo, index = mid,
851	>	expectedModCount);
852	>	}
853	>
854	>	@SuppressWarnings("unchecked")
855	>	public void forEachRemaining(Consumer<? super E> action) {
856	>	int i, hi, mc; // hoist accesses and checks from loop
857	>	PriorityQueue<E> q; Object[] a;
858	>	if (action == null)
859	>	throw new NullPointerException();
860	>	if ((q = pq) != null && (a = q.queue) != null) {
861	>	if ((hi = fence) < 0) {
862	>	mc = q.modCount;
863	>	hi = q.size;
864	>	}
865	>	else
866	>	mc = expectedModCount;
867	>	if ((i = index) >= 0 && (index = hi) <= a.length) {
868	>	for (E e;; ++i) {
869	>	if (i < hi) {
870	>	if ((e = (E) a[i]) == null) // must be CME
871	>	break;
872	>	action.accept(e);
873	>	}
874	>	else if (q.modCount != mc)
875	>	break;
876	>	else
877	>	return;
878	>	}
879	>	}
880	>	}
881	>	throw new ConcurrentModificationException();
882	>	}
883	>
884	>	public boolean tryAdvance(Consumer<? super E> action) {
885	>	if (action == null)
886	>	throw new NullPointerException();
887	>	int hi = getFence(), lo = index;
888	>	if (lo >= 0 && lo < hi) {
889	>	index = lo + 1;
890	>	@SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
891	>	if (e == null)
892	>	throw new ConcurrentModificationException();
893	>	action.accept(e);
894	>	if (pq.modCount != expectedModCount)
895	>	throw new ConcurrentModificationException();
896	>	return true;
897	>	}
898	>	return false;
899	>	}
900	>
901	>	public long estimateSize() {
902	>	return (long) (getFence() - index);
903	>	}
904	>
905	>	public int characteristics() {
906	>	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
907	>	}
908		}
909		}

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