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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.60 by jsr166, Mon Dec 5 02:56:59 2005 UTC vs.
Revision 1.108 by jsr166, Sun Oct 11 00:50:06 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 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	<	import java.util.*; // for javadoc (till 6280605 is fixed)
27	>
28	>	import java.util.function.Consumer;
29
30		/**
31	<	* An unbounded priority {@linkplain Queue queue} based on a priority
32	<	* heap.  The elements of the priority queue are ordered according to
33	<	* their {@linkplain Comparable natural ordering}, or by a {@link
34	<	* Comparator} provided at queue construction time, depending on which
35	<	* constructor is used.  A priority queue does not permit
36	<	* <tt>null</tt> elements.  A priority queue relying on natural
37	<	* ordering also does not permit insertion of non-comparable objects
38	<	* (doing so may result in <tt>ClassCastException</tt>).
31	>	* An unbounded priority {@linkplain Queue queue} based on a priority heap.
32	>	* The elements of the priority queue are ordered according to their
33	>	* {@linkplain Comparable natural ordering}, or by a {@link Comparator}
34	>	* provided at queue construction time, depending on which constructor is
35	>	* used.  A priority queue does not permit {@code null} elements.
36	>	* A priority queue relying on natural ordering also does not permit
37	>	* insertion of non-comparable objects (doing so may result in
38	>	* {@code ClassCastException}).
39		*
40		* <p>The <em>head</em> of this queue is the <em>least</em> element
41		* with respect to the specified ordering.  If multiple elements are
42		* tied for least value, the head is one of those elements -- ties are
43	<	* broken arbitrarily.  The queue retrieval operations <tt>poll</tt>,
44	<	* <tt>remove</tt>, <tt>peek</tt>, and <tt>element</tt> access the
43	>	* broken arbitrarily.  The queue retrieval operations {@code poll},
44	>	* {@code remove}, {@code peek}, and {@code element} access the
45		* element at the head of the queue.
46		*
47		* <p>A priority queue is unbounded, but has an internal
#	Line 37 | Line 56 | import java.util.*; // for javadoc (till
56		* Iterator} interfaces.  The Iterator provided in method {@link
57		* #iterator()} is <em>not</em> guaranteed to traverse the elements of
58		* the priority queue in any particular order. If you need ordered
59	<	* traversal, consider using <tt>Arrays.sort(pq.toArray())</tt>.
59	>	* traversal, consider using {@code Arrays.sort(pq.toArray())}.
60		*
61	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
62	<	* Multiple threads should not access a <tt>PriorityQueue</tt>
63	<	* instance concurrently if any of the threads modifies the list
64	<	* structurally. Instead, use the thread-safe {@link
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 O(log(n)) time
68	<	* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
69	<	* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
70	<	* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
71	<	* constant time for the retrieval methods (<tt>peek</tt>,
72	<	* <tt>element</tt>, and <tt>size</tt>).
67	>	* <p>Implementation note: this implementation provides
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
79	<	* @version 1.8, 08/27/05
80	<	* @author Josh Bloch
61	<	* @param <E> the type of elements held in this collection
79	>	* @author Josh Bloch, Doug Lea
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 <tt>PriorityQueue</tt> with the default initial
117	>	* Creates a {@code PriorityQueue} with the default initial
118		* capacity (11) that orders its elements according to their
119		* {@linkplain Comparable natural ordering}.
120		*/
#	Line 104 | Line 123 | public class PriorityQueue<E> extends Ab
123		}
124
125		/**
126	<	* Creates a <tt>PriorityQueue</tt> with the specified initial
126	>	* Creates a {@code PriorityQueue} with the specified initial
127		* capacity that orders its elements according to their
128		* {@linkplain Comparable natural ordering}.
129		*
130		* @param initialCapacity the initial capacity for this priority queue
131	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
132	<	* than 1
131	>	* @throws IllegalArgumentException if {@code initialCapacity} is less
132	>	*         than 1
133		*/
134		public PriorityQueue(int initialCapacity) {
135		this(initialCapacity, null);
136		}
137
138		/**
139	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
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		*
155		* @param  initialCapacity the initial capacity for this priority queue
156	<	* @param  comparator the comparator that will be used to order
157	<	*         this priority queue.  If <tt>null</tt>, the <i>natural
158	<	*         ordering</i> of the elements will be used.
159	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is
156	>	* @param  comparator the comparator that will be used to order this
157	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
158	>	*         natural ordering} of the elements will be used.
159	>	* @throws IllegalArgumentException if {@code initialCapacity} is
160		*         less than 1
161		*/
162		public PriorityQueue(int initialCapacity,
#	Line 138 | Line 170 | public class PriorityQueue<E> extends Ab
170		}
171
172		/**
173	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
174	<	* specified collection.   If the specified collection is an
175	<	* instance of a {@link java.util.SortedSet} or is another
176	<	* <tt>PriorityQueue</tt>, the priority queue will be ordered
177	<	* according to the same ordering.  Otherwise, this priority queue
178	<	* will be ordered according to the natural ordering of its elements.
173	>	* Creates a {@code PriorityQueue} containing the elements in the
174	>	* specified collection.  If the specified collection is an instance of
175	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
176	>	* priority queue will be ordered according to the same ordering.
177	>	* Otherwise, this priority queue will be ordered according to the
178	>	* {@linkplain Comparable natural ordering} of its elements.
179		*
180		* @param  c the collection whose elements are to be placed
181		*         into this priority queue
#	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
206		/**
207	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
207	>	* Creates a {@code PriorityQueue} containing the elements in the
208		* specified priority queue.  This priority queue will be
209		* ordered according to the same ordering as the given priority
210		* queue.
211		*
212		* @param  c the priority queue whose elements are to be placed
213		*         into this priority queue
214	<	* @throws ClassCastException if elements of <tt>c</tt> cannot be
215	<	*         compared to one another according to <tt>c</tt>'s
214	>	* @throws ClassCastException if elements of {@code c} cannot be
215	>	*         compared to one another according to {@code c}'s
216		*         ordering
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		/**
227	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
228	<	* specified sorted set.  This priority queue will be ordered
227	>	* Creates a {@code PriorityQueue} containing the elements in the
228	>	* specified sorted set.   This priority queue will be ordered
229		* according to the same ordering as the given sorted set.
230		*
231		* @param  c the sorted set whose elements are to be placed
232	<	*         into this priority queue.
232	>	*         into this priority queue
233		* @throws ClassCastException if elements of the specified sorted
234		*         set cannot be compared to one another according to the
235		*         sorted set's ordering
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	<	/**
246	<	* Initialize queue array with elements from the given Collection.
247	<	* @param c the collection
248	<	*/
249	<	private void initFromCollection(Collection<? extends E> c) {
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	<	queue = a;
260	<	size = a.length;
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		/**
269	+	* Initializes queue array with elements from the given Collection.
270	+	*
271	+	* @param c the collection
272	+	*/
273	+	private void initFromCollection(Collection<? extends E> c) {
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
227	<	throw new OutOfMemoryError();
228	<	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)
236	<	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		*
314	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
314	>	* @return {@code true} (as specified by {@link Collection#add})
315		* @throws ClassCastException if the specified element cannot be
316		*         compared with elements currently in this priority queue
317		*         according to the priority queue's ordering
#	Line 253 | Line 324 | public class PriorityQueue<E> extends Ab
324		/**
325		* Inserts the specified element into this priority queue.
326		*
327	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
327	>	* @return {@code true} (as specified by {@link Queue#offer})
328		* @throws ClassCastException if the specified element cannot be
329		*         compared with elements currently in this priority queue
330		*         according to the priority queue's ordering
#	Line 274 | Line 345 | public class PriorityQueue<E> extends Ab
345		return true;
346		}
347
348	+	@SuppressWarnings("unchecked")
349		public E peek() {
350	<	if (size == 0)
279	<	return null;
280	<	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 291 | Line 361 | public class PriorityQueue<E> extends Ab
361
362		/**
363		* Removes a single instance of the specified element from this queue,
364	<	* if it is present.  More formally, removes an element <tt>e</tt> such
365	<	* that <tt>o.equals(e)</tt>, if this queue contains one or more such
366	<	* elements.  Returns true if this queue contained the specified element
367	<	* (or equivalently, if this queue changed as a result of the call).
364	>	* if it is present.  More formally, removes an element {@code e} such
365	>	* that {@code o.equals(e)}, if this queue contains one or more such
366	>	* elements.  Returns {@code true} if and only if this queue contained
367	>	* the specified element (or equivalently, if this queue changed as a
368	>	* result of the call).
369		*
370		* @param o element to be removed from this queue, if present
371	<	* @return <tt>true</tt> if this queue changed as a result of the call
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 314 | Line 385 | public class PriorityQueue<E> extends Ab
385		* Needed by iterator.remove.
386		*
387		* @param o element to be removed from this queue, if present
388	<	* @return <tt>true</tt> if removed
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 327 | Line 398 | public class PriorityQueue<E> extends Ab
398		}
399
400		/**
401	<	* Returns <tt>true</tt> if this queue contains the specified element.
402	<	* More formally, returns <tt>true</tt> if and only if this queue contains
403	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
401	>	* Returns {@code true} if this queue contains the specified element.
402	>	* More formally, returns {@code true} if and only if this queue contains
403	>	* at least one element {@code e} such that {@code o.equals(e)}.
404		*
405		* @param o object to be checked for containment in this queue
406	<	* @return <tt>true</tt> if this queue contains the specified element
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		/**
413	<	* Returns an array containing all of the elements in this queue,
413	>	* Returns an array containing all of the elements in this queue.
414		* The elements are in no particular order.
415		*
416		* <p>The returned array will be "safe" in that no references to it are
417	<	* maintained by this list.  (In other words, this method must allocate
417	>	* maintained by this queue.  (In other words, this method must allocate
418		* a new array).  The caller is thus free to modify the returned array.
419		*
420	+	* <p>This method acts as bridge between array-based and collection-based
421	+	* APIs.
422	+	*
423		* @return an array containing all of the elements in this queue
424		*/
425		public Object[] toArray() {
#	Line 353 | Line 427 | public class PriorityQueue<E> extends Ab
427		}
428
429		/**
430	<	* Returns an array containing all of the elements in this queue.
431	<	* The elements are in no particular order.  The runtime type of
432	<	* the returned array is that of the specified array.  If the queue
433	<	* fits in the specified array, it is returned therein.
434	<	* Otherwise, a new array is allocated with the runtime type of
435	<	* the specified array and the size of this queue.
430	>	* Returns an array containing all of the elements in this queue; the
431	>	* runtime type of the returned array is that of the specified array.
432	>	* The returned array elements are in no particular order.
433	>	* If the queue fits in the specified array, it is returned therein.
434	>	* Otherwise, a new array is allocated with the runtime type of the
435	>	* specified array and the size of this queue.
436		*
437		* <p>If the queue fits in the specified array with room to spare
438		* (i.e., the array has more elements than the queue), the element in
439		* the array immediately following the end of the collection is set to
440	<	* <tt>null</tt>.  (This is useful in determining the length of the
441	<	* queue <i>only</i> if the caller knows that the queue does not contain
442	<	* any null elements.)
440	>	* {@code null}.
441	>	*
442	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
443	>	* array-based and collection-based APIs.  Further, this method allows
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 {@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 {@code String}:
450	>	*
451	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
452	>	*
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
458		*          same runtime type is allocated for this purpose.
459	<	* @return an array containing the elements of the queue
459	>	* @return an array containing all of the elements in this queue
460		* @throws ArrayStoreException if the runtime type of the specified array
461		*         is not a supertype of the runtime type of every element in
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 401 | 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 419 | Line 507 | public class PriorityQueue<E> extends Ab
507		* after we've completed the "normal" iteration.
508		*
509		* We expect that most iterations, even those involving removals,
510	<	* will not use need to store elements in this field.
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
522	<	* List should have.  If this expectation is violated, the iterator
522	>	* Queue should have.  If this expectation is violated, the iterator
523		* has detected concurrent modification.
524		*/
525		private int expectedModCount = modCount;
#	Line 441 | 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 458 | Line 547 | public class PriorityQueue<E> extends Ab
547		public void remove() {
548		if (expectedModCount != modCount)
549		throw new ConcurrentModificationException();
461	–	if (lastRet == -1 && lastRetElt == null)
462	–	throw new IllegalStateException();
550		if (lastRet != -1) {
551		E moved = PriorityQueue.this.removeAt(lastRet);
552		lastRet = -1;
#	Line 467 | 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 {
560	>	} else if (lastRetElt != null) {
561		PriorityQueue.this.removeEq(lastRetElt);
562		lastRetElt = null;
563	+	} else {
564	+	throw new IllegalStateException();
565		}
566		expectedModCount = modCount;
567		}
479	–
568		}
569
570		public int size() {
#	Line 494 | 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;
589		int s = --size;
590		modCount++;
591	<	E result = (E)queue[0];
592	<	E x = (E)queue[s];
591	>	E result = (E) queue[0];
592	>	E x = (E) queue[s];
593		queue[s] = null;
594		if (s != 0)
595		siftDown(0, x);
#	Line 517 | Line 606 | public class PriorityQueue<E> extends Ab
606		* i.  Under these circumstances, this method returns the element
607		* that was previously at the end of the list and is now at some
608		* position before i. This fact is used by iterator.remove so as to
609	<	* avoid missing traverseing elements.
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 557 | 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) {
654		int parent = (k - 1) >>> 1;
655		Object e = queue[parent];
656	<	if (key.compareTo((E)e) >= 0)
656	>	if (key.compareTo((E) e) >= 0)
657		break;
658		queue[k] = e;
659		k = parent;
#	Line 570 | 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;
668		Object e = queue[parent];
669	<	if (comparator.compare(x, (E)e) >= 0)
669	>	if (comparator.compare(x, (E) e) >= 0)
670		break;
671		queue[k] = e;
672		k = parent;
#	Line 597 | 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 605 | Line 698 | public class PriorityQueue<E> extends Ab
698		Object c = queue[child];
699		int right = child + 1;
700		if (right < size &&
701	<	((Comparable<? super E>)c).compareTo((E)queue[right]) > 0)
701	>	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
702		c = queue[child = right];
703	<	if (key.compareTo((E)c) <= 0)
703	>	if (key.compareTo((E) c) <= 0)
704		break;
705		queue[k] = c;
706		k = child;
#	Line 615 | 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 622 | Line 716 | public class PriorityQueue<E> extends Ab
716		Object c = queue[child];
717		int right = child + 1;
718		if (right < size &&
719	<	comparator.compare((E)c, (E)queue[right]) > 0)
719	>	comparator.compare((E) c, (E) queue[right]) > 0)
720		c = queue[child = right];
721	<	if (comparator.compare(x, (E)c) <= 0)
721	>	if (comparator.compare(x, (E) c) <= 0)
722		break;
723		queue[k] = c;
724		k = child;
#	Line 636 | 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]);
736	>	siftDown(i, (E) queue[i]);
737		}
738
739		/**
740		* Returns the comparator used to order the elements in this
741	<	* queue, or <tt>null</tt> if this queue is sorted according to
741	>	* queue, or {@code null} if this queue is sorted according to
742		* the {@linkplain Comparable natural ordering} of its elements.
743		*
744		* @return the comparator used to order this queue, or
745	<	*         <tt>null</tt> if this queue is sorted according to the
746	<	*         natural ordering of its elements.
745	>	*         {@code null} if this queue is sorted according to the
746	>	*         natural ordering of its elements
747		*/
748		public Comparator<? super E> comparator() {
749		return comparator;
750		}
751
752		/**
753	<	* Save the state of the instance to a stream (that
659	<	* is, serialize 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 (each an
757	<	* <tt>Object</tt>) in the proper order.
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
766	<	// Write out array length
767	<	// For compatibility with 1.5 version, must be at least 2.
673	<	s.writeInt(Math.max(2, queue.length));
766	>	// Write out array length, for compatibility with 1.5 version
767	>	s.writeInt(Math.max(2, size + 1));
768
769	<	// Write out all elements in the proper order.
770	<	for (int i=0; i<size; i++)
769	>	// Write out all elements in the "proper order".
770	>	for (int i = 0; i < size; i++)
771		s.writeObject(queue[i]);
772		}
773
774		/**
775	<	* Reconstitute the <tt>PriorityQueue</tt> instance from a stream
776	<	* (that is, deserialize it).
775	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
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 {
785		// Read in size, and any hidden stuff
786		s.defaultReadObject();
787
788	<	// Read in array length and allocate array
789	<	int arrayLength = s.readInt();
790	<	queue = new Object[arrayLength];
791	<
792	<	// Read in all elements in the proper order.
793	<	for (int i=0; i<size; i++)
794	<	queue[i] = (E) s.readObject();
788	>	// Read in (and discard) array length
789	>	s.readInt();
790	>
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();
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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