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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 1.120 by jsr166, Sun Oct 22 17:44:03 2017 UTC

#	Line 1 | Line 1
1		/*
2	<	* %W% %E%
2	>	* Copyright (c) 2003, 2017, 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	>	import jdk.internal.misc.SharedSecrets;
30
31		/**
32	<	* An unbounded priority {@linkplain Queue queue} based on a priority
33	<	* heap.  The elements of the priority queue are ordered according to
34	<	* their {@linkplain Comparable natural ordering}, or by a {@link
35	<	* Comparator} provided at queue construction time, depending on which
36	<	* constructor is used.  A priority queue does not permit
37	<	* <tt>null</tt> elements.  A priority queue relying on natural
38	<	* ordering also does not permit insertion of non-comparable objects
39	<	* (doing so may result in <tt>ClassCastException</tt>).
32	>	* An unbounded priority {@linkplain Queue queue} based on a priority heap.
33	>	* The elements of the priority queue are ordered according to their
34	>	* {@linkplain Comparable natural ordering}, or by a {@link Comparator}
35	>	* provided at queue construction time, depending on which constructor is
36	>	* used.  A priority queue does not permit {@code null} elements.
37	>	* A priority queue relying on natural ordering also does not permit
38	>	* insertion of non-comparable objects (doing so may result in
39	>	* {@code ClassCastException}).
40		*
41		* <p>The <em>head</em> of this queue is the <em>least</em> element
42		* with respect to the specified ordering.  If multiple elements are
43		* tied for least value, the head is one of those elements -- ties are
44	<	* broken arbitrarily.  The queue retrieval operations <tt>poll</tt>,
45	<	* <tt>remove</tt>, <tt>peek</tt>, and <tt>element</tt> access the
44	>	* broken arbitrarily.  The queue retrieval operations {@code poll},
45	>	* {@code remove}, {@code peek}, and {@code element} access the
46		* element at the head of the queue.
47		*
48		* <p>A priority queue is unbounded, but has an internal
#	Line 35 | Line 55 | import java.util.*; // for javadoc (till
55		* <p>This class and its iterator implement all of the
56		* <em>optional</em> methods of the {@link Collection} and {@link
57		* Iterator} interfaces.  The Iterator provided in method {@link
58	<	* #iterator()} is <em>not</em> guaranteed to traverse the elements of
58	>	* #iterator()} and the Spliterator provided in method {@link #spliterator()}
59	>	* are <em>not</em> guaranteed to traverse the elements of
60		* the priority queue in any particular order. If you need ordered
61	<	* traversal, consider using <tt>Arrays.sort(pq.toArray())</tt>.
61	>	* traversal, consider using {@code Arrays.sort(pq.toArray())}.
62		*
63	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
64	<	* Multiple threads should not access a <tt>PriorityQueue</tt>
65	<	* instance concurrently if any of the threads modifies the list
66	<	* structurally. Instead, use the thread-safe {@link
63	>	* <p><strong>Note that this implementation is not synchronized.</strong>
64	>	* Multiple threads should not access a {@code PriorityQueue}
65	>	* instance concurrently if any of the threads modifies the queue.
66	>	* Instead, use the thread-safe {@link
67		* java.util.concurrent.PriorityBlockingQueue} class.
68		*
69	<	* <p>Implementation note: this implementation provides O(log(n)) time
70	<	* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
71	<	* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
72	<	* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
73	<	* constant time for the retrieval methods (<tt>peek</tt>,
74	<	* <tt>element</tt>, and <tt>size</tt>).
69	>	* <p>Implementation note: this implementation provides
70	>	* O(log(n)) time for the enqueuing and dequeuing methods
71	>	* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
72	>	* linear time for the {@code remove(Object)} and {@code contains(Object)}
73	>	* methods; and constant time for the retrieval methods
74	>	* ({@code peek}, {@code element}, and {@code size}).
75		*
76		* <p>This class is a member of the
77	<	* <a href="{@docRoot}/../guide/collections/index.html">
77	>	* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
78		* Java Collections Framework</a>.
79	+	*
80		* @since 1.5
81	<	* @version 1.8, 08/27/05
82	<	* @author Josh Bloch
61	<	* @param <E> the type of elements held in this collection
81	>	* @author Josh Bloch, Doug Lea
82	>	* @param <E> the type of elements held in this queue
83		*/
84		public class PriorityQueue<E> extends AbstractQueue<E>
85		implements java.io.Serializable {
#	Line 75 | Line 96 | public class PriorityQueue<E> extends Ab
96		* heap and each descendant d of n, n <= d.  The element with the
97		* lowest value is in queue[0], assuming the queue is nonempty.
98		*/
99	<	private transient Object[] queue;
99	>	transient Object[] queue; // non-private to simplify nested class access
100
101		/**
102		* The number of elements in the priority queue.
103		*/
104	<	private int size = 0;
104	>	int size;
105
106		/**
107		* The comparator, or null if priority queue uses elements'
#	Line 92 | Line 113 | public class PriorityQueue<E> extends Ab
113		* The number of times this priority queue has been
114		* <i>structurally modified</i>.  See AbstractList for gory details.
115		*/
116	<	private transient int modCount = 0;
116	>	transient int modCount;     // non-private to simplify nested class access
117
118		/**
119	<	* Creates a <tt>PriorityQueue</tt> with the default initial
119	>	* Creates a {@code PriorityQueue} with the default initial
120		* capacity (11) that orders its elements according to their
121		* {@linkplain Comparable natural ordering}.
122		*/
#	Line 104 | Line 125 | public class PriorityQueue<E> extends Ab
125		}
126
127		/**
128	<	* Creates a <tt>PriorityQueue</tt> with the specified initial
128	>	* Creates a {@code PriorityQueue} with the specified initial
129		* capacity that orders its elements according to their
130		* {@linkplain Comparable natural ordering}.
131		*
132		* @param initialCapacity the initial capacity for this priority queue
133	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
134	<	* than 1
133	>	* @throws IllegalArgumentException if {@code initialCapacity} is less
134	>	*         than 1
135		*/
136		public PriorityQueue(int initialCapacity) {
137		this(initialCapacity, null);
138		}
139
140		/**
141	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
141	>	* Creates a {@code PriorityQueue} with the default initial capacity and
142	>	* whose elements are ordered according to the specified comparator.
143	>	*
144	>	* @param  comparator the comparator that will be used to order this
145	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
146	>	*         natural ordering} of the elements will be used.
147	>	* @since 1.8
148	>	*/
149	>	public PriorityQueue(Comparator<? super E> comparator) {
150	>	this(DEFAULT_INITIAL_CAPACITY, comparator);
151	>	}
152	>
153	>	/**
154	>	* Creates a {@code PriorityQueue} with the specified initial capacity
155		* that orders its elements according to the specified comparator.
156		*
157		* @param  initialCapacity the initial capacity for this priority queue
158	<	* @param  comparator the comparator that will be used to order
159	<	*         this priority queue.  If <tt>null</tt>, the <i>natural
160	<	*         ordering</i> of the elements will be used.
161	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is
158	>	* @param  comparator the comparator that will be used to order this
159	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
160	>	*         natural ordering} of the elements will be used.
161	>	* @throws IllegalArgumentException if {@code initialCapacity} is
162		*         less than 1
163		*/
164		public PriorityQueue(int initialCapacity,
#	Line 138 | Line 172 | public class PriorityQueue<E> extends Ab
172		}
173
174		/**
175	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
176	<	* specified collection.   If the specified collection is an
177	<	* instance of a {@link java.util.SortedSet} or is another
178	<	* <tt>PriorityQueue</tt>, the priority queue will be ordered
179	<	* according to the same ordering.  Otherwise, this priority queue
180	<	* will be ordered according to the natural ordering of its elements.
175	>	* Creates a {@code PriorityQueue} containing the elements in the
176	>	* specified collection.  If the specified collection is an instance of
177	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
178	>	* priority queue will be ordered according to the same ordering.
179	>	* Otherwise, this priority queue will be ordered according to the
180	>	* {@linkplain Comparable natural ordering} of its elements.
181		*
182		* @param  c the collection whose elements are to be placed
183		*         into this priority queue
#	Line 153 | Line 187 | public class PriorityQueue<E> extends Ab
187		* @throws NullPointerException if the specified collection or any
188		*         of its elements are null
189		*/
190	+	@SuppressWarnings("unchecked")
191		public PriorityQueue(Collection<? extends E> c) {
192	<	initFromCollection(c);
193	<	if (c instanceof SortedSet)
194	<	comparator = (Comparator<? super E>)
195	<	((SortedSet<? extends E>)c).comparator();
196	<	else if (c instanceof PriorityQueue)
197	<	comparator = (Comparator<? super E>)
198	<	((PriorityQueue<? extends E>)c).comparator();
192	>	if (c instanceof SortedSet<?>) {
193	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
194	>	this.comparator = (Comparator<? super E>) ss.comparator();
195	>	initElementsFromCollection(ss);
196	>	}
197	>	else if (c instanceof PriorityQueue<?>) {
198	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
199	>	this.comparator = (Comparator<? super E>) pq.comparator();
200	>	initFromPriorityQueue(pq);
201	>	}
202		else {
203	<	comparator = null;
204	<	heapify();
203	>	this.comparator = null;
204	>	initFromCollection(c);
205		}
206		}
207
208		/**
209	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
209	>	* Creates a {@code PriorityQueue} containing the elements in the
210		* specified priority queue.  This priority queue will be
211		* ordered according to the same ordering as the given priority
212		* queue.
213		*
214		* @param  c the priority queue whose elements are to be placed
215		*         into this priority queue
216	<	* @throws ClassCastException if elements of <tt>c</tt> cannot be
217	<	*         compared to one another according to <tt>c</tt>'s
216	>	* @throws ClassCastException if elements of {@code c} cannot be
217	>	*         compared to one another according to {@code c}'s
218		*         ordering
219		* @throws NullPointerException if the specified priority queue or any
220		*         of its elements are null
221		*/
222	+	@SuppressWarnings("unchecked")
223		public PriorityQueue(PriorityQueue<? extends E> c) {
224	<	comparator = (Comparator<? super E>)c.comparator();
225	<	initFromCollection(c);
224	>	this.comparator = (Comparator<? super E>) c.comparator();
225	>	initFromPriorityQueue(c);
226		}
227
228		/**
229	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
230	<	* specified sorted set.  This priority queue will be ordered
229	>	* Creates a {@code PriorityQueue} containing the elements in the
230	>	* specified sorted set.   This priority queue will be ordered
231		* according to the same ordering as the given sorted set.
232		*
233		* @param  c the sorted set whose elements are to be placed
234	<	*         into this priority queue.
234	>	*         into this priority queue
235		* @throws ClassCastException if elements of the specified sorted
236		*         set cannot be compared to one another according to the
237		*         sorted set's ordering
238		* @throws NullPointerException if the specified sorted set or any
239		*         of its elements are null
240		*/
241	+	@SuppressWarnings("unchecked")
242		public PriorityQueue(SortedSet<? extends E> c) {
243	<	comparator = (Comparator<? super E>)c.comparator();
244	<	initFromCollection(c);
243	>	this.comparator = (Comparator<? super E>) c.comparator();
244	>	initElementsFromCollection(c);
245		}
246
247	<	/**
248	<	* Initialize queue array with elements from the given Collection.
249	<	* @param c the collection
250	<	*/
251	<	private void initFromCollection(Collection<? extends E> c) {
247	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
248	>	if (c.getClass() == PriorityQueue.class) {
249	>	this.queue = c.toArray();
250	>	this.size = c.size();
251	>	} else {
252	>	initFromCollection(c);
253	>	}
254	>	}
255	>
256	>	private void initElementsFromCollection(Collection<? extends E> c) {
257		Object[] a = c.toArray();
258		// If c.toArray incorrectly doesn't return Object[], copy it.
259		if (a.getClass() != Object[].class)
260		a = Arrays.copyOf(a, a.length, Object[].class);
261	<	queue = a;
262	<	size = a.length;
261	>	int len = a.length;
262	>	if (len == 1 || this.comparator != null)
263	>	for (Object e : a)
264	>	if (e == null)
265	>	throw new NullPointerException();
266	>	this.queue = a;
267	>	this.size = a.length;
268	>	}
269	>
270	>	/**
271	>	* Initializes queue array with elements from the given Collection.
272	>	*
273	>	* @param c the collection
274	>	*/
275	>	private void initFromCollection(Collection<? extends E> c) {
276	>	initElementsFromCollection(c);
277	>	heapify();
278		}
279
280		/**
281	+	* The maximum size of array to allocate.
282	+	* Some VMs reserve some header words in an array.
283	+	* Attempts to allocate larger arrays may result in
284	+	* OutOfMemoryError: Requested array size exceeds VM limit
285	+	*/
286	+	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
287	+
288	+	/**
289		* Increases the capacity of the array.
290		*
291		* @param minCapacity the desired minimum capacity
292		*/
293		private void grow(int minCapacity) {
294	<	if (minCapacity < 0) // overflow
227	<	throw new OutOfMemoryError();
228	<	int oldCapacity = queue.length;
294	>	int oldCapacity = queue.length;
295		// Double size if small; else grow by 50%
296	<	int newCapacity = ((oldCapacity < 64)?
297	<	((oldCapacity + 1) * 2):
298	<	((oldCapacity / 2) * 3));
299	<	if (newCapacity < 0) // overflow
300	<	newCapacity = Integer.MAX_VALUE;
301	<	if (newCapacity < minCapacity)
236	<	newCapacity = minCapacity;
296	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
297	>	(oldCapacity + 2) :
298	>	(oldCapacity >> 1));
299	>	// overflow-conscious code
300	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
301	>	newCapacity = hugeCapacity(minCapacity);
302		queue = Arrays.copyOf(queue, newCapacity);
303		}
304
305	+	private static int hugeCapacity(int minCapacity) {
306	+	if (minCapacity < 0) // overflow
307	+	throw new OutOfMemoryError();
308	+	return (minCapacity > MAX_ARRAY_SIZE) ?
309	+	Integer.MAX_VALUE :
310	+	MAX_ARRAY_SIZE;
311	+	}
312	+
313		/**
314		* Inserts the specified element into this priority queue.
315		*
316	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
316	>	* @return {@code true} (as specified by {@link Collection#add})
317		* @throws ClassCastException if the specified element cannot be
318		*         compared with elements currently in this priority queue
319		*         according to the priority queue's ordering
#	Line 253 | Line 326 | public class PriorityQueue<E> extends Ab
326		/**
327		* Inserts the specified element into this priority queue.
328		*
329	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
329	>	* @return {@code true} (as specified by {@link Queue#offer})
330		* @throws ClassCastException if the specified element cannot be
331		*         compared with elements currently in this priority queue
332		*         according to the priority queue's ordering
#	Line 266 | Line 339 | public class PriorityQueue<E> extends Ab
339		int i = size;
340		if (i >= queue.length)
341		grow(i + 1);
342	+	siftUp(i, e);
343		size = i + 1;
270	–	if (i == 0)
271	–	queue[0] = e;
272	–	else
273	–	siftUp(i, e);
344		return true;
345		}
346
347	+	@SuppressWarnings("unchecked")
348		public E peek() {
349	<	if (size == 0)
279	<	return null;
280	<	return (E) queue[0];
349	>	return (size == 0) ? null : (E) queue[0];
350		}
351
352		private int indexOf(Object o) {
353	<	if (o != null) {
353	>	if (o != null) {
354		for (int i = 0; i < size; i++)
355		if (o.equals(queue[i]))
356		return i;
#	Line 291 | Line 360 | public class PriorityQueue<E> extends Ab
360
361		/**
362		* Removes a single instance of the specified element from this queue,
363	<	* if it is present.  More formally, removes an element <tt>e</tt> such
364	<	* that <tt>o.equals(e)</tt>, if this queue contains one or more such
365	<	* elements.  Returns true if this queue contained the specified element
366	<	* (or equivalently, if this queue changed as a result of the call).
363	>	* if it is present.  More formally, removes an element {@code e} such
364	>	* that {@code o.equals(e)}, if this queue contains one or more such
365	>	* elements.  Returns {@code true} if and only if this queue contained
366	>	* the specified element (or equivalently, if this queue changed as a
367	>	* result of the call).
368		*
369		* @param o element to be removed from this queue, if present
370	<	* @return <tt>true</tt> if this queue changed as a result of the call
370	>	* @return {@code true} if this queue changed as a result of the call
371		*/
372		public boolean remove(Object o) {
373	<	int i = indexOf(o);
374	<	if (i == -1)
375	<	return false;
376	<	else {
377	<	removeAt(i);
378	<	return true;
379	<	}
373	>	int i = indexOf(o);
374	>	if (i == -1)
375	>	return false;
376	>	else {
377	>	removeAt(i);
378	>	return true;
379	>	}
380		}
381
382		/**
#	Line 314 | Line 384 | public class PriorityQueue<E> extends Ab
384		* Needed by iterator.remove.
385		*
386		* @param o element to be removed from this queue, if present
387	<	* @return <tt>true</tt> if removed
387	>	* @return {@code true} if removed
388		*/
389		boolean removeEq(Object o) {
390	<	for (int i = 0; i < size; i++) {
391	<	if (o == queue[i]) {
390	>	for (int i = 0; i < size; i++) {
391	>	if (o == queue[i]) {
392		removeAt(i);
393		return true;
394		}
#	Line 327 | Line 397 | public class PriorityQueue<E> extends Ab
397		}
398
399		/**
400	<	* Returns <tt>true</tt> if this queue contains the specified element.
401	<	* More formally, returns <tt>true</tt> if and only if this queue contains
402	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
400	>	* Returns {@code true} if this queue contains the specified element.
401	>	* More formally, returns {@code true} if and only if this queue contains
402	>	* at least one element {@code e} such that {@code o.equals(e)}.
403		*
404		* @param o object to be checked for containment in this queue
405	<	* @return <tt>true</tt> if this queue contains the specified element
405	>	* @return {@code true} if this queue contains the specified element
406		*/
407		public boolean contains(Object o) {
408	<	return indexOf(o) != -1;
408	>	return indexOf(o) >= 0;
409		}
410
411		/**
412	<	* Returns an array containing all of the elements in this queue,
412	>	* Returns an array containing all of the elements in this queue.
413		* The elements are in no particular order.
414		*
415		* <p>The returned array will be "safe" in that no references to it are
416	<	* maintained by this list.  (In other words, this method must allocate
416	>	* maintained by this queue.  (In other words, this method must allocate
417		* a new array).  The caller is thus free to modify the returned array.
418		*
419	+	* <p>This method acts as bridge between array-based and collection-based
420	+	* APIs.
421	+	*
422		* @return an array containing all of the elements in this queue
423		*/
424		public Object[] toArray() {
#	Line 353 | Line 426 | public class PriorityQueue<E> extends Ab
426		}
427
428		/**
429	<	* Returns an array containing all of the elements in this queue.
430	<	* The elements are in no particular order.  The runtime type of
431	<	* the returned array is that of the specified array.  If the queue
432	<	* fits in the specified array, it is returned therein.
433	<	* Otherwise, a new array is allocated with the runtime type of
434	<	* the specified array and the size of this queue.
429	>	* Returns an array containing all of the elements in this queue; the
430	>	* runtime type of the returned array is that of the specified array.
431	>	* The returned array elements are in no particular order.
432	>	* If the queue fits in the specified array, it is returned therein.
433	>	* Otherwise, a new array is allocated with the runtime type of the
434	>	* specified array and the size of this queue.
435		*
436		* <p>If the queue fits in the specified array with room to spare
437		* (i.e., the array has more elements than the queue), the element in
438		* the array immediately following the end of the collection is set to
439	<	* <tt>null</tt>.  (This is useful in determining the length of the
440	<	* queue <i>only</i> if the caller knows that the queue does not contain
441	<	* any null elements.)
439	>	* {@code null}.
440	>	*
441	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
442	>	* array-based and collection-based APIs.  Further, this method allows
443	>	* precise control over the runtime type of the output array, and may,
444	>	* under certain circumstances, be used to save allocation costs.
445	>	*
446	>	* <p>Suppose {@code x} is a queue known to contain only strings.
447	>	* The following code can be used to dump the queue into a newly
448	>	* allocated array of {@code String}:
449	>	*
450	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
451	>	*
452	>	* Note that {@code toArray(new Object[0])} is identical in function to
453	>	* {@code toArray()}.
454		*
455		* @param a the array into which the elements of the queue are to
456		*          be stored, if it is big enough; otherwise, a new array of the
457		*          same runtime type is allocated for this purpose.
458	<	* @return an array containing the elements of the queue
458	>	* @return an array containing all of the elements in this queue
459		* @throws ArrayStoreException if the runtime type of the specified array
460		*         is not a supertype of the runtime type of every element in
461		*         this queue
462		* @throws NullPointerException if the specified array is null
463		*/
464	+	@SuppressWarnings("unchecked")
465		public <T> T[] toArray(T[] a) {
466	+	final int size = this.size;
467		if (a.length < size)
468		// Make a new array of a's runtime type, but my contents:
469		return (T[]) Arrays.copyOf(queue, size, a.getClass());
470	<	System.arraycopy(queue, 0, a, 0, size);
470	>	System.arraycopy(queue, 0, a, 0, size);
471		if (a.length > size)
472		a[size] = null;
473		return a;
#	Line 401 | Line 488 | public class PriorityQueue<E> extends Ab
488		* Index (into queue array) of element to be returned by
489		* subsequent call to next.
490		*/
491	<	private int cursor = 0;
491	>	private int cursor;
492
493		/**
494		* Index of element returned by most recent call to next,
#	Line 419 | Line 506 | public class PriorityQueue<E> extends Ab
506		* after we've completed the "normal" iteration.
507		*
508		* We expect that most iterations, even those involving removals,
509	<	* will not use need to store elements in this field.
509	>	* will not need to store elements in this field.
510		*/
511	<	private ArrayDeque<E> forgetMeNot = null;
511	>	private ArrayDeque<E> forgetMeNot;
512
513		/**
514		* Element returned by the most recent call to next iff that
515		* element was drawn from the forgetMeNot list.
516		*/
517	<	private E lastRetElt = null;
517	>	private E lastRetElt;
518
519		/**
520		* The modCount value that the iterator believes that the backing
521	<	* List should have.  If this expectation is violated, the iterator
521	>	* Queue should have.  If this expectation is violated, the iterator
522		* has detected concurrent modification.
523		*/
524		private int expectedModCount = modCount;
525
526	+	Itr() {}                        // prevent access constructor creation
527	+
528		public boolean hasNext() {
529		return cursor < size ||
530		(forgetMeNot != null && !forgetMeNot.isEmpty());
531		}
532
533	+	@SuppressWarnings("unchecked")
534		public E next() {
535		if (expectedModCount != modCount)
536		throw new ConcurrentModificationException();
#	Line 458 | Line 548 | public class PriorityQueue<E> extends Ab
548		public void remove() {
549		if (expectedModCount != modCount)
550		throw new ConcurrentModificationException();
461	–	if (lastRet == -1 && lastRetElt == null)
462	–	throw new IllegalStateException();
551		if (lastRet != -1) {
552		E moved = PriorityQueue.this.removeAt(lastRet);
553		lastRet = -1;
#	Line 467 | Line 555 | public class PriorityQueue<E> extends Ab
555		cursor--;
556		else {
557		if (forgetMeNot == null)
558	<	forgetMeNot = new ArrayDeque<E>();
558	>	forgetMeNot = new ArrayDeque<>();
559		forgetMeNot.add(moved);
560		}
561	<	} else {
561	>	} else if (lastRetElt != null) {
562		PriorityQueue.this.removeEq(lastRetElt);
563		lastRetElt = null;
564	+	} else {
565	+	throw new IllegalStateException();
566		}
567		expectedModCount = modCount;
568		}
479	–
569		}
570
571		public int size() {
#	Line 494 | Line 583 | public class PriorityQueue<E> extends Ab
583		size = 0;
584		}
585
586	+	@SuppressWarnings("unchecked")
587		public E poll() {
588		if (size == 0)
589		return null;
590		int s = --size;
591		modCount++;
592	<	E result = (E)queue[0];
593	<	E x = (E)queue[s];
592	>	E result = (E) queue[0];
593	>	E x = (E) queue[s];
594		queue[s] = null;
595		if (s != 0)
596		siftDown(0, x);
#	Line 517 | Line 607 | public class PriorityQueue<E> extends Ab
607		* i.  Under these circumstances, this method returns the element
608		* that was previously at the end of the list and is now at some
609		* position before i. This fact is used by iterator.remove so as to
610	<	* avoid missing traverseing elements.
610	>	* avoid missing traversing elements.
611		*/
612	<	private E removeAt(int i) {
613	<	assert i >= 0 && i < size;
612	>	@SuppressWarnings("unchecked")
613	>	E removeAt(int i) {
614	>	// assert i >= 0 && i < size;
615		modCount++;
616		int s = --size;
617		if (s == i) // removed last element
#	Line 543 | Line 634 | public class PriorityQueue<E> extends Ab
634		* promoting x up the tree until it is greater than or equal to
635		* its parent, or is the root.
636		*
637	<	* To simplify and speed up coercions and comparisons. the
637	>	* To simplify and speed up coercions and comparisons, the
638		* Comparable and Comparator versions are separated into different
639		* methods that are otherwise identical. (Similarly for siftDown.)
640		*
#	Line 557 | Line 648 | public class PriorityQueue<E> extends Ab
648		siftUpComparable(k, x);
649		}
650
651	+	@SuppressWarnings("unchecked")
652		private void siftUpComparable(int k, E x) {
653		Comparable<? super E> key = (Comparable<? super E>) x;
654		while (k > 0) {
655		int parent = (k - 1) >>> 1;
656		Object e = queue[parent];
657	<	if (key.compareTo((E)e) >= 0)
657	>	if (key.compareTo((E) e) >= 0)
658		break;
659		queue[k] = e;
660		k = parent;
#	Line 570 | Line 662 | public class PriorityQueue<E> extends Ab
662		queue[k] = key;
663		}
664
665	+	@SuppressWarnings("unchecked")
666		private void siftUpUsingComparator(int k, E x) {
667		while (k > 0) {
668		int parent = (k - 1) >>> 1;
669		Object e = queue[parent];
670	<	if (comparator.compare(x, (E)e) >= 0)
670	>	if (comparator.compare(x, (E) e) >= 0)
671		break;
672		queue[k] = e;
673		k = parent;
#	Line 597 | Line 690 | public class PriorityQueue<E> extends Ab
690		siftDownComparable(k, x);
691		}
692
693	+	@SuppressWarnings("unchecked")
694		private void siftDownComparable(int k, E x) {
695		Comparable<? super E> key = (Comparable<? super E>)x;
696		int half = size >>> 1;        // loop while a non-leaf
#	Line 605 | Line 699 | public class PriorityQueue<E> extends Ab
699		Object c = queue[child];
700		int right = child + 1;
701		if (right < size &&
702	<	((Comparable<? super E>)c).compareTo((E)queue[right]) > 0)
702	>	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
703		c = queue[child = right];
704	<	if (key.compareTo((E)c) <= 0)
704	>	if (key.compareTo((E) c) <= 0)
705		break;
706		queue[k] = c;
707		k = child;
#	Line 615 | Line 709 | public class PriorityQueue<E> extends Ab
709		queue[k] = key;
710		}
711
712	+	@SuppressWarnings("unchecked")
713		private void siftDownUsingComparator(int k, E x) {
714		int half = size >>> 1;
715		while (k < half) {
#	Line 622 | Line 717 | public class PriorityQueue<E> extends Ab
717		Object c = queue[child];
718		int right = child + 1;
719		if (right < size &&
720	<	comparator.compare((E)c, (E)queue[right]) > 0)
720	>	comparator.compare((E) c, (E) queue[right]) > 0)
721		c = queue[child = right];
722	<	if (comparator.compare(x, (E)c) <= 0)
722	>	if (comparator.compare(x, (E) c) <= 0)
723		break;
724		queue[k] = c;
725		k = child;
#	Line 635 | Line 730 | public class PriorityQueue<E> extends Ab
730		/**
731		* Establishes the heap invariant (described above) in the entire tree,
732		* assuming nothing about the order of the elements prior to the call.
733	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
734		*/
735	+	@SuppressWarnings("unchecked")
736		private void heapify() {
737	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
738	<	siftDown(i, (E)queue[i]);
737	>	final Object[] es = queue;
738	>	int i = (size >>> 1) - 1;
739	>	if (comparator == null)
740	>	for (; i >= 0; i--)
741	>	siftDownComparable(i, (E) es[i]);
742	>	else
743	>	for (; i >= 0; i--)
744	>	siftDownUsingComparator(i, (E) es[i]);
745		}
746
747		/**
748		* Returns the comparator used to order the elements in this
749	<	* queue, or <tt>null</tt> if this queue is sorted according to
749	>	* queue, or {@code null} if this queue is sorted according to
750		* the {@linkplain Comparable natural ordering} of its elements.
751		*
752		* @return the comparator used to order this queue, or
753	<	*         <tt>null</tt> if this queue is sorted according to the
754	<	*         natural ordering of its elements.
753	>	*         {@code null} if this queue is sorted according to the
754	>	*         natural ordering of its elements
755		*/
756		public Comparator<? super E> comparator() {
757		return comparator;
758		}
759
760		/**
761	<	* Save the state of the instance to a stream (that
659	<	* is, serialize it).
761	>	* Saves this queue to a stream (that is, serializes it).
762		*
661	–	* @serialData The length of the array backing the instance is
662	–	* emitted (int), followed by all of its elements (each an
663	–	* <tt>Object</tt>) in the proper order.
763		* @param s the stream
764	+	* @throws java.io.IOException if an I/O error occurs
765	+	* @serialData The length of the array backing the instance is
766	+	*             emitted (int), followed by all of its elements
767	+	*             (each an {@code Object}) in the proper order.
768		*/
769		private void writeObject(java.io.ObjectOutputStream s)
770	<	throws java.io.IOException{
770	>	throws java.io.IOException {
771		// Write out element count, and any hidden stuff
772		s.defaultWriteObject();
773
774	<	// Write out array length
775	<	// For compatibility with 1.5 version, must be at least 2.
673	<	s.writeInt(Math.max(2, queue.length));
774	>	// Write out array length, for compatibility with 1.5 version
775	>	s.writeInt(Math.max(2, size + 1));
776
777	<	// Write out all elements in the proper order.
778	<	for (int i=0; i<size; i++)
777	>	// Write out all elements in the "proper order".
778	>	for (int i = 0; i < size; i++)
779		s.writeObject(queue[i]);
780		}
781
782		/**
783	<	* Reconstitute the <tt>PriorityQueue</tt> instance from a stream
784	<	* (that is, deserialize it).
783	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
784	>	* (that is, deserializes it).
785	>	*
786		* @param s the stream
787	+	* @throws ClassNotFoundException if the class of a serialized object
788	+	*         could not be found
789	+	* @throws java.io.IOException if an I/O error occurs
790		*/
791		private void readObject(java.io.ObjectInputStream s)
792		throws java.io.IOException, ClassNotFoundException {
793		// Read in size, and any hidden stuff
794		s.defaultReadObject();
795
796	<	// Read in array length and allocate array
797	<	int arrayLength = s.readInt();
798	<	queue = new Object[arrayLength];
799	<
800	<	// Read in all elements in the proper order.
801	<	for (int i=0; i<size; i++)
802	<	queue[i] = (E) s.readObject();
796	>	// Read in (and discard) array length
797	>	s.readInt();
798	>
799	>	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
800	>	queue = new Object[size];
801	>
802	>	// Read in all elements.
803	>	for (int i = 0; i < size; i++)
804	>	queue[i] = s.readObject();
805	>
806	>	// Elements are guaranteed to be in "proper order", but the
807	>	// spec has never explained what that might be.
808	>	heapify();
809		}
810
811	+	/**
812	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
813	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
814	+	* queue. The spliterator does not traverse elements in any particular order
815	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
816	+	*
817	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
818	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
819	+	* Overriding implementations should document the reporting of additional
820	+	* characteristic values.
821	+	*
822	+	* @return a {@code Spliterator} over the elements in this queue
823	+	* @since 1.8
824	+	*/
825	+	public final Spliterator<E> spliterator() {
826	+	return new PriorityQueueSpliterator(0, -1, 0);
827	+	}
828	+
829	+	final class PriorityQueueSpliterator implements Spliterator<E> {
830	+	private int index;            // current index, modified on advance/split
831	+	private int fence;            // -1 until first use
832	+	private int expectedModCount; // initialized when fence set
833	+
834	+	/** Creates new spliterator covering the given range. */
835	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
836	+	this.index = origin;
837	+	this.fence = fence;
838	+	this.expectedModCount = expectedModCount;
839	+	}
840	+
841	+	private int getFence() { // initialize fence to size on first use
842	+	int hi;
843	+	if ((hi = fence) < 0) {
844	+	expectedModCount = modCount;
845	+	hi = fence = size;
846	+	}
847	+	return hi;
848	+	}
849	+
850	+	public PriorityQueueSpliterator trySplit() {
851	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
852	+	return (lo >= mid) ? null :
853	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
854	+	}
855	+
856	+	@SuppressWarnings("unchecked")
857	+	public void forEachRemaining(Consumer<? super E> action) {
858	+	if (action == null)
859	+	throw new NullPointerException();
860	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
861	+	final Object[] a = queue;
862	+	int i, hi; E e;
863	+	for (i = index, index = hi = fence; i < hi; i++) {
864	+	if ((e = (E) a[i]) == null)
865	+	break;      // must be CME
866	+	action.accept(e);
867	+	}
868	+	if (modCount != expectedModCount)
869	+	throw new ConcurrentModificationException();
870	+	}
871	+
872	+	@SuppressWarnings("unchecked")
873	+	public boolean tryAdvance(Consumer<? super E> action) {
874	+	if (action == null)
875	+	throw new NullPointerException();
876	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
877	+	int i;
878	+	if ((i = index) < fence) {
879	+	index = i + 1;
880	+	E e;
881	+	if ((e = (E) queue[i]) == null
882	+	|| modCount != expectedModCount)
883	+	throw new ConcurrentModificationException();
884	+	action.accept(e);
885	+	return true;
886	+	}
887	+	return false;
888	+	}
889	+
890	+	public long estimateSize() {
891	+	return getFence() - index;
892	+	}
893	+
894	+	public int characteristics() {
895	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
896	+	}
897	+	}
898		}

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