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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.64 by jsr166, Sun Mar 19 01:00:40 2006 UTC vs.
Revision 1.110 by jsr166, Wed Aug 24 21:46:18 2016 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 2006 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
72		* ({@code peek}, {@code element}, and {@code size}).
73		*
74		* <p>This class is a member of the
75	<	* <a href="{@docRoot}/../guide/collections/index.html">
75	>	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
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 267 | 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;
271	–	if (i == 0)
272	–	queue[0] = e;
273	–	else
274	–	siftUp(i, e);
342		return true;
343		}
344
345	+	@SuppressWarnings("unchecked")
346		public E peek() {
347	<	if (size == 0)
280	<	return null;
281	<	return (E) queue[0];
347	>	return (size == 0) ? null : (E) queue[0];
348		}
349
350		private int indexOf(Object o) {
351	<	if (o != null) {
351	>	if (o != null) {
352		for (int i = 0; i < size; i++)
353		if (o.equals(queue[i]))
354		return i;
#	Line 302 | Line 368 | public class PriorityQueue<E> extends Ab
368		* @return {@code true} if this queue changed as a result of the call
369		*/
370		public boolean remove(Object o) {
371	<	int i = indexOf(o);
372	<	if (i == -1)
373	<	return false;
374	<	else {
375	<	removeAt(i);
376	<	return true;
377	<	}
371	>	int i = indexOf(o);
372	>	if (i == -1)
373	>	return false;
374	>	else {
375	>	removeAt(i);
376	>	return true;
377	>	}
378		}
379
380		/**
#	Line 319 | Line 385 | public class PriorityQueue<E> extends Ab
385		* @return {@code true} if removed
386		*/
387		boolean removeEq(Object o) {
388	<	for (int i = 0; i < size; i++) {
389	<	if (o == queue[i]) {
388	>	for (int i = 0; i < size; i++) {
389	>	if (o == queue[i]) {
390		removeAt(i);
391		return true;
392		}
#	Line 337 | 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 375 | 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>
383	<	*     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 394 | 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());
468	<	System.arraycopy(queue, 0, a, 0, size);
468	>	System.arraycopy(queue, 0, a, 0, size);
469		if (a.length > size)
470		a[size] = null;
471		return a;
#	Line 419 | 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 439 | 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 459 | 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 483 | 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 491 | Line 559 | public class PriorityQueue<E> extends Ab
559		lastRetElt = null;
560		} else {
561		throw new IllegalStateException();
562	<	}
562	>	}
563		expectedModCount = modCount;
564		}
565		}
#	Line 511 | 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 536 | 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) {
609	<	assert i >= 0 && i < size;
608	>	@SuppressWarnings("unchecked")
609	>	E removeAt(int i) {
610	>	// assert i >= 0 && i < size;
611		modCount++;
612		int s = --size;
613		if (s == i) // removed last element
#	Line 574 | 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 587 | 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 614 | 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 632 | 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 653 | 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 672 | Line 747 | public class PriorityQueue<E> extends Ab
747		}
748
749		/**
750	<	* Saves the state of the instance to a stream (that
676	<	* is, serializes it).
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.
681	–	* @param s the stream
757		*/
758		private void writeObject(java.io.ObjectOutputStream s)
759	<	throws java.io.IOException{
759	>	throws java.io.IOException {
760		// Write out element count, and any hidden stuff
761		s.defaultWriteObject();
762
#	Line 698 | Line 773 | public class PriorityQueue<E> extends Ab
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 707 | Line 785 | public class PriorityQueue<E> extends Ab
785		// Read in (and discard) array length
786		s.readInt();
787
788	<	queue = new Object[size];
788	>	queue = new Object[size];
789
790		// Read in all elements.
791		for (int i = 0; i < size; i++)
792		queue[i] = s.readObject();
793
794	<	// Elements are guaranteed to be in "proper order", but the
795	<	// spec has never explained what that might be.
796	<	heapify();
794	>	// Elements are guaranteed to be in "proper order", but the
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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