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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.46 by dl, Mon Dec 29 19:05:19 2003 UTC vs.
Revision 1.116 by jsr166, Sun Dec 18 21:52:10 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 2003 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
32	<	* heap.  This queue orders elements according to an order specified
33	<	* at construction time, which is specified either according to their
34	<	* <i>natural order</i> (see {@link Comparable}), or according to a
35	<	* {@link java.util.Comparator}, depending on which constructor is
36	<	* used. A priority queue does not permit <tt>null</tt> elements.
37	<	* A priority queue relying on natural ordering also does not
38	<	* permit insertion of non-comparable objects (doing so may result
19	<	* 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 32 | Line 51 | package java.util;
51		* grows automatically.  The details of the growth policy are not
52		* specified.
53		*
54	<	* <p>This class implements all of the <em>optional</em> methods of
55	<	* the {@link Collection} and {@link Iterator} interfaces.  The
56	<	* Iterator provided in method {@link #iterator()} is <em>not</em>
57	<	* guaranteed to traverse the elements of the PriorityQueue in any
58	<	* particular order. If you need ordered traversal, consider using
59	<	* <tt>Arrays.sort(pq.toArray())</tt>.
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
54	>	* <p>This class and its iterator implement all of the
55	>	* <em>optional</em> methods of the {@link Collection} and {@link
56	>	* Iterator} interfaces.  The Iterator provided in method {@link
57	>	* #iterator()} and the Spliterator provided in method {@link #spliterator()}
58	>	* are <em>not</em> guaranteed to traverse the elements of
59	>	* the priority queue in any particular order. If you need ordered
60	>	* traversal, consider using {@code Arrays.sort(pq.toArray())}.
61	>	*
62	>	* <p><strong>Note that this implementation is not synchronized.</strong>
63	>	* Multiple threads should not access a {@code PriorityQueue}
64	>	* instance concurrently if any of the threads modifies the queue.
65	>	* Instead, use the thread-safe {@link
66		* java.util.concurrent.PriorityBlockingQueue} class.
67		*
68	<	*
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>,
54	<	* <tt>element</tt>, and <tt>size</tt>).
68	>	* <p>Implementation note: this implementation provides
69	>	* O(log(n)) time for the enqueuing and dequeuing methods
70	>	* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
71	>	* linear time for the {@code remove(Object)} and {@code contains(Object)}
72	>	* methods; and constant time for the retrieval methods
73	>	* ({@code peek}, {@code element}, and {@code size}).
74		*
75		* <p>This class is a member of the
76	<	* <a href="{@docRoot}/../guide/collections/index.html">
76	>	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
77		* Java Collections Framework</a>.
78	+	*
79		* @since 1.5
80	<	* @version %I%, %G%
81	<	* @author Josh Bloch
62	<	* @param <E> the type of elements held in this collection
80	>	* @author Josh Bloch, Doug Lea
81	>	* @param <E> the type of elements held in this queue
82		*/
83		public class PriorityQueue<E> extends AbstractQueue<E>
84	<	implements Queue<E>, java.io.Serializable {
84	>	implements java.io.Serializable {
85
86		private static final long serialVersionUID = -7720805057305804111L;
87
88		private static final int DEFAULT_INITIAL_CAPACITY = 11;
89
90		/**
91	<	* Priority queue represented as a balanced binary heap: the two children
92	<	* of queue[n] are queue[2*n] and queue[2*n + 1].  The priority queue is
93	<	* ordered by comparator, or by the elements' natural ordering, if
94	<	* comparator is null:  For each node n in the heap and each descendant d
95	<	* of n, n <= d.
96	<	*
78	<	* The element with the lowest value is in queue[1], assuming the queue is
79	<	* nonempty.  (A one-based array is used in preference to the traditional
80	<	* zero-based array to simplify parent and child calculations.)
81	<	*
82	<	* queue.length must be >= 2, even if size == 0.
91	>	* Priority queue represented as a balanced binary heap: the two
92	>	* children of queue[n] are queue[2*n+1] and queue[2*(n+1)].  The
93	>	* priority queue is ordered by comparator, or by the elements'
94	>	* natural ordering, if comparator is null: For each node n in the
95	>	* heap and each descendant d of n, n <= d.  The element with the
96	>	* lowest value is in queue[0], assuming the queue is nonempty.
97		*/
98	<	private transient Object[] queue;
98	>	transient Object[] queue; // non-private to simplify nested class access
99
100		/**
101		* The number of elements in the priority queue.
102		*/
103	<	private int size = 0;
103	>	int size;
104
105		/**
106		* The comparator, or null if priority queue uses elements'
#	Line 98 | Line 112 | public class PriorityQueue<E> extends Ab
112		* The number of times this priority queue has been
113		* <i>structurally modified</i>.  See AbstractList for gory details.
114		*/
115	<	private transient int modCount = 0;
115	>	transient int modCount;     // non-private to simplify nested class access
116
117		/**
118	<	* Creates a <tt>PriorityQueue</tt> with the default initial capacity
119	<	* (11) that orders its elements according to their natural
120	<	* ordering (using <tt>Comparable</tt>).
118	>	* Creates a {@code PriorityQueue} with the default initial
119	>	* capacity (11) that orders its elements according to their
120	>	* {@linkplain Comparable natural ordering}.
121		*/
122		public PriorityQueue() {
123		this(DEFAULT_INITIAL_CAPACITY, null);
124		}
125
126		/**
127	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
128	<	* that orders its elements according to their natural ordering
129	<	* (using <tt>Comparable</tt>).
130	<	*
131	<	* @param initialCapacity the initial capacity for this priority queue.
132	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
133	<	* than 1
127	>	* Creates a {@code PriorityQueue} with the specified initial
128	>	* capacity that orders its elements according to their
129	>	* {@linkplain Comparable natural ordering}.
130	>	*
131	>	* @param initialCapacity the initial capacity for this priority queue
132	>	* @throws IllegalArgumentException if {@code initialCapacity} is less
133	>	*         than 1
134		*/
135		public PriorityQueue(int initialCapacity) {
136		this(initialCapacity, null);
137		}
138
139		/**
140	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
140	>	* Creates a {@code PriorityQueue} with the default initial capacity and
141	>	* whose elements are ordered according to the specified comparator.
142	>	*
143	>	* @param  comparator the comparator that will be used to order this
144	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
145	>	*         natural ordering} of the elements will be used.
146	>	* @since 1.8
147	>	*/
148	>	public PriorityQueue(Comparator<? super E> comparator) {
149	>	this(DEFAULT_INITIAL_CAPACITY, comparator);
150	>	}
151	>
152	>	/**
153	>	* Creates a {@code PriorityQueue} with the specified initial capacity
154		* that orders its elements according to the specified comparator.
155		*
156	<	* @param initialCapacity the initial capacity for this priority queue.
157	<	* @param comparator the comparator used to order this priority queue.
158	<	* If <tt>null</tt> then the order depends on the elements' natural
159	<	* ordering.
160	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
161	<	* than 1
156	>	* @param  initialCapacity the initial capacity for this priority queue
157	>	* @param  comparator the comparator that will be used to order this
158	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
159	>	*         natural ordering} of the elements will be used.
160	>	* @throws IllegalArgumentException if {@code initialCapacity} is
161	>	*         less than 1
162		*/
163	<	public PriorityQueue(int initialCapacity,
163	>	public PriorityQueue(int initialCapacity,
164		Comparator<? super E> comparator) {
165	+	// Note: This restriction of at least one is not actually needed,
166	+	// but continues for 1.5 compatibility
167		if (initialCapacity < 1)
168		throw new IllegalArgumentException();
169	<	this.queue = new Object[initialCapacity + 1];
169	>	this.queue = new Object[initialCapacity];
170		this.comparator = comparator;
171		}
172
173		/**
174	<	* Common code to initialize underlying queue array across
175	<	* constructors below.
174	>	* Creates a {@code PriorityQueue} containing the elements in the
175	>	* specified collection.  If the specified collection is an instance of
176	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
177	>	* priority queue will be ordered according to the same ordering.
178	>	* Otherwise, this priority queue will be ordered according to the
179	>	* {@linkplain Comparable natural ordering} of its elements.
180	>	*
181	>	* @param  c the collection whose elements are to be placed
182	>	*         into this priority queue
183	>	* @throws ClassCastException if elements of the specified collection
184	>	*         cannot be compared to one another according to the priority
185	>	*         queue's ordering
186	>	* @throws NullPointerException if the specified collection or any
187	>	*         of its elements are null
188		*/
189	<	private void initializeArray(Collection<? extends E> c) {
190	<	int sz = c.size();
191	<	int initialCapacity = (int)Math.min((sz * 110L) / 100,
192	<	Integer.MAX_VALUE - 1);
193	<	if (initialCapacity < 1)
194	<	initialCapacity = 1;
195	<
196	<	this.queue = new Object[initialCapacity + 1];
189	>	@SuppressWarnings("unchecked")
190	>	public PriorityQueue(Collection<? extends E> c) {
191	>	if (c instanceof SortedSet<?>) {
192	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
193	>	this.comparator = (Comparator<? super E>) ss.comparator();
194	>	initElementsFromCollection(ss);
195	>	}
196	>	else if (c instanceof PriorityQueue<?>) {
197	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
198	>	this.comparator = (Comparator<? super E>) pq.comparator();
199	>	initFromPriorityQueue(pq);
200	>	}
201	>	else {
202	>	this.comparator = null;
203	>	initFromCollection(c);
204	>	}
205		}
206
207		/**
208	<	* Initially fill elements of the queue array under the
209	<	* knowledge that it is sorted or is another PQ, in which
210	<	* case we can just place the elements in the order presented.
208	>	* Creates a {@code PriorityQueue} containing the elements in the
209	>	* specified priority queue.  This priority queue will be
210	>	* ordered according to the same ordering as the given priority
211	>	* queue.
212	>	*
213	>	* @param  c the priority queue whose elements are to be placed
214	>	*         into this priority queue
215	>	* @throws ClassCastException if elements of {@code c} cannot be
216	>	*         compared to one another according to {@code c}'s
217	>	*         ordering
218	>	* @throws NullPointerException if the specified priority queue or any
219	>	*         of its elements are null
220		*/
221	<	private void fillFromSorted(Collection<? extends E> c) {
222	<	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
223	<	queue[++size] = i.next();
221	>	@SuppressWarnings("unchecked")
222	>	public PriorityQueue(PriorityQueue<? extends E> c) {
223	>	this.comparator = (Comparator<? super E>) c.comparator();
224	>	initFromPriorityQueue(c);
225		}
226
227		/**
228	<	* Initially fill elements of the queue array that is not to our knowledge
229	<	* sorted, so we must rearrange the elements to guarantee the heap
230	<	* invariant.
228	>	* Creates a {@code PriorityQueue} containing the elements in the
229	>	* specified sorted set.   This priority queue will be ordered
230	>	* according to the same ordering as the given sorted set.
231	>	*
232	>	* @param  c the sorted set whose elements are to be placed
233	>	*         into this priority queue
234	>	* @throws ClassCastException if elements of the specified sorted
235	>	*         set cannot be compared to one another according to the
236	>	*         sorted set's ordering
237	>	* @throws NullPointerException if the specified sorted set or any
238	>	*         of its elements are null
239		*/
240	<	private void fillFromUnsorted(Collection<? extends E> c) {
241	<	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); )
242	<	queue[++size] = i.next();
243	<	heapify();
240	>	@SuppressWarnings("unchecked")
241	>	public PriorityQueue(SortedSet<? extends E> c) {
242	>	this.comparator = (Comparator<? super E>) c.comparator();
243	>	initElementsFromCollection(c);
244		}
245
246	<	/**
247	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
248	<	* specified collection.  The priority queue has an initial
249	<	* capacity of 110% of the size of the specified collection or 1
183	<	* if the collection is empty.  If the specified collection is an
184	<	* instance of a {@link java.util.SortedSet} or is another
185	<	* <tt>PriorityQueue</tt>, the priority queue will be sorted
186	<	* according to the same comparator, or according to its elements'
187	<	* natural order if the collection is sorted according to its
188	<	* elements' natural order.  Otherwise, the priority queue is
189	<	* ordered according to its elements' natural order.
190	<	*
191	<	* @param c the collection whose elements are to be placed
192	<	*        into this priority queue.
193	<	* @throws ClassCastException if elements of the specified collection
194	<	*         cannot be compared to one another according to the priority
195	<	*         queue's ordering.
196	<	* @throws NullPointerException if <tt>c</tt> or any element within it
197	<	* is <tt>null</tt>
198	<	*/
199	<	public PriorityQueue(Collection<? extends E> c) {
200	<	initializeArray(c);
201	<	if (c instanceof SortedSet) {
202	<	SortedSet<? extends E> s = (SortedSet<? extends E>)c;
203	<	comparator = (Comparator<? super E>)s.comparator();
204	<	fillFromSorted(s);
205	<	} else if (c instanceof PriorityQueue) {
206	<	PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
207	<	comparator = (Comparator<? super E>)s.comparator();
208	<	fillFromSorted(s);
246	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
247	>	if (c.getClass() == PriorityQueue.class) {
248	>	this.queue = c.toArray();
249	>	this.size = c.size();
250		} else {
251	<	comparator = null;
211	<	fillFromUnsorted(c);
251	>	initFromCollection(c);
252		}
253		}
254
255	+	private void initElementsFromCollection(Collection<? extends E> c) {
256	+	Object[] a = c.toArray();
257	+	// If c.toArray incorrectly doesn't return Object[], copy it.
258	+	if (a.getClass() != Object[].class)
259	+	a = Arrays.copyOf(a, a.length, Object[].class);
260	+	int len = a.length;
261	+	if (len == 1 || this.comparator != null)
262	+	for (Object e : a)
263	+	if (e == null)
264	+	throw new NullPointerException();
265	+	this.queue = a;
266	+	this.size = a.length;
267	+	}
268	+
269		/**
270	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
217	<	* specified collection.  The priority queue has an initial
218	<	* capacity of 110% of the size of the specified collection or 1
219	<	* if the collection is empty.  This priority queue will be sorted
220	<	* according to the same comparator as the given collection, or
221	<	* according to its elements' natural order if the collection is
222	<	* sorted according to its elements' natural order.
270	>	* Initializes queue array with elements from the given Collection.
271		*
272	<	* @param c the collection whose elements are to be placed
225	<	*        into this priority queue.
226	<	* @throws ClassCastException if elements of the specified collection
227	<	*         cannot be compared to one another according to the priority
228	<	*         queue's ordering.
229	<	* @throws NullPointerException if <tt>c</tt> or any element within it
230	<	* is <tt>null</tt>
272	>	* @param c the collection
273		*/
274	<	public PriorityQueue(PriorityQueue<? extends E> c) {
275	<	initializeArray(c);
276	<	comparator = (Comparator<? super E>)c.comparator();
235	<	fillFromSorted(c);
274	>	private void initFromCollection(Collection<? extends E> c) {
275	>	initElementsFromCollection(c);
276	>	heapify();
277		}
278
279		/**
280	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
281	<	* specified collection.  The priority queue has an initial
282	<	* capacity of 110% of the size of the specified collection or 1
283	<	* if the collection is empty.  This priority queue will be sorted
284	<	* according to the same comparator as the given collection, or
285	<	* according to its elements' natural order if the collection is
286	<	* sorted according to its elements' natural order.
280	>	* The maximum size of array to allocate.
281	>	* Some VMs reserve some header words in an array.
282	>	* Attempts to allocate larger arrays may result in
283	>	* OutOfMemoryError: Requested array size exceeds VM limit
284	>	*/
285	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
286	>
287	>	/**
288	>	* Increases the capacity of the array.
289		*
290	<	* @param c the collection whose elements are to be placed
248	<	*        into this priority queue.
249	<	* @throws ClassCastException if elements of the specified collection
250	<	*         cannot be compared to one another according to the priority
251	<	*         queue's ordering.
252	<	* @throws NullPointerException if <tt>c</tt> or any element within it
253	<	* is <tt>null</tt>
290	>	* @param minCapacity the desired minimum capacity
291		*/
292	<	public PriorityQueue(SortedSet<? extends E> c) {
293	<	initializeArray(c);
294	<	comparator = (Comparator<? super E>)c.comparator();
295	<	fillFromSorted(c);
292	>	private void grow(int minCapacity) {
293	>	int oldCapacity = queue.length;
294	>	// Double size if small; else grow by 50%
295	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
296	>	(oldCapacity + 2) :
297	>	(oldCapacity >> 1));
298	>	// overflow-conscious code
299	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
300	>	newCapacity = hugeCapacity(minCapacity);
301	>	queue = Arrays.copyOf(queue, newCapacity);
302	>	}
303	>
304	>	private static int hugeCapacity(int minCapacity) {
305	>	if (minCapacity < 0) // overflow
306	>	throw new OutOfMemoryError();
307	>	return (minCapacity > MAX_ARRAY_SIZE) ?
308	>	Integer.MAX_VALUE :
309	>	MAX_ARRAY_SIZE;
310		}
311
312		/**
313	<	* Resize array, if necessary, to be able to hold given index
313	>	* Inserts the specified element into this priority queue.
314	>	*
315	>	* @return {@code true} (as specified by {@link Collection#add})
316	>	* @throws ClassCastException if the specified element cannot be
317	>	*         compared with elements currently in this priority queue
318	>	*         according to the priority queue's ordering
319	>	* @throws NullPointerException if the specified element is null
320		*/
321	<	private void grow(int index) {
322	<	int newlen = queue.length;
266	<	if (index < newlen) // don't need to grow
267	<	return;
268	<	if (index == Integer.MAX_VALUE)
269	<	throw new OutOfMemoryError();
270	<	while (newlen <= index) {
271	<	if (newlen >= Integer.MAX_VALUE / 2)  // avoid overflow
272	<	newlen = Integer.MAX_VALUE;
273	<	else
274	<	newlen <<= 2;
275	<	}
276	<	Object[] newQueue = new Object[newlen];
277	<	System.arraycopy(queue, 0, newQueue, 0, queue.length);
278	<	queue = newQueue;
321	>	public boolean add(E e) {
322	>	return offer(e);
323		}
280	–
324
325		/**
326		* Inserts the specified element into this priority queue.
327		*
328	<	* @return <tt>true</tt>
329	<	* @throws ClassCastException if the specified element cannot be compared
330	<	* with elements currently in the priority queue according
331	<	* to the priority queue's ordering.
332	<	* @throws NullPointerException if the specified element is <tt>null</tt>.
328	>	* @return {@code true} (as specified by {@link Queue#offer})
329	>	* @throws ClassCastException if the specified element cannot be
330	>	*         compared with elements currently in this priority queue
331	>	*         according to the priority queue's ordering
332	>	* @throws NullPointerException if the specified element is null
333		*/
334	<	public boolean offer(E o) {
335	<	if (o == null)
334	>	public boolean offer(E e) {
335	>	if (e == null)
336		throw new NullPointerException();
337		modCount++;
338	<	++size;
339	<
340	<	// Grow backing store if necessary
341	<	if (size >= queue.length)
342	<	grow(size);
300	<
301	<	queue[size] = o;
302	<	fixUp(size);
338	>	int i = size;
339	>	if (i >= queue.length)
340	>	grow(i + 1);
341	>	siftUp(i, e);
342	>	size = i + 1;
343		return true;
344		}
345
346	+	@SuppressWarnings("unchecked")
347		public E peek() {
348	<	if (size == 0)
308	<	return null;
309	<	return (E) queue[1];
348	>	return (size == 0) ? null : (E) queue[0];
349		}
350
351	<	// Collection Methods - the first two override to update docs
351	>	private int indexOf(Object o) {
352	>	if (o != null) {
353	>	for (int i = 0; i < size; i++)
354	>	if (o.equals(queue[i]))
355	>	return i;
356	>	}
357	>	return -1;
358	>	}
359
360		/**
361	<	* Adds the specified element to this queue.
362	<	* @return <tt>true</tt> (as per the general contract of
363	<	* <tt>Collection.add</tt>).
361	>	* Removes a single instance of the specified element from this queue,
362	>	* if it is present.  More formally, removes an element {@code e} such
363	>	* that {@code o.equals(e)}, if this queue contains one or more such
364	>	* elements.  Returns {@code true} if and only if this queue contained
365	>	* the specified element (or equivalently, if this queue changed as a
366	>	* result of the call).
367		*
368	<	* @throws NullPointerException if the specified element is <tt>null</tt>.
369	<	* @throws ClassCastException if the specified element cannot be compared
321	<	* with elements currently in the priority queue according
322	<	* to the priority queue's ordering.
368	>	* @param o element to be removed from this queue, if present
369	>	* @return {@code true} if this queue changed as a result of the call
370		*/
324	–	public boolean add(E o) {
325	–	return offer(o);
326	–	}
327	–
371		public boolean remove(Object o) {
372	<	if (o == null)
372	>	int i = indexOf(o);
373	>	if (i == -1)
374		return false;
375	+	else {
376	+	removeAt(i);
377	+	return true;
378	+	}
379	+	}
380
381	<	if (comparator == null) {
382	<	for (int i = 1; i <= size; i++) {
383	<	if (((Comparable<E>)queue[i]).compareTo((E)o) == 0) {
384	<	removeAt(i);
385	<	return true;
386	<	}
387	<	}
388	<	} else {
389	<	for (int i = 1; i <= size; i++) {
390	<	if (comparator.compare((E)queue[i], (E)o) == 0) {
391	<	removeAt(i);
392	<	return true;
344	<	}
381	>	/**
382	>	* Version of remove using reference equality, not equals.
383	>	* Needed by iterator.remove.
384	>	*
385	>	* @param o element to be removed from this queue, if present
386	>	* @return {@code true} if removed
387	>	*/
388	>	boolean removeEq(Object o) {
389	>	for (int i = 0; i < size; i++) {
390	>	if (o == queue[i]) {
391	>	removeAt(i);
392	>	return true;
393		}
394		}
395		return false;
396		}
397
398		/**
399	+	* Returns {@code true} if this queue contains the specified element.
400	+	* More formally, returns {@code true} if and only if this queue contains
401	+	* at least one element {@code e} such that {@code o.equals(e)}.
402	+	*
403	+	* @param o object to be checked for containment in this queue
404	+	* @return {@code true} if this queue contains the specified element
405	+	*/
406	+	public boolean contains(Object o) {
407	+	return indexOf(o) >= 0;
408	+	}
409	+
410	+	/**
411	+	* Returns an array containing all of the elements in this queue.
412	+	* The elements are in no particular order.
413	+	*
414	+	* <p>The returned array will be "safe" in that no references to it are
415	+	* maintained by this queue.  (In other words, this method must allocate
416	+	* a new array).  The caller is thus free to modify the returned array.
417	+	*
418	+	* <p>This method acts as bridge between array-based and collection-based
419	+	* APIs.
420	+	*
421	+	* @return an array containing all of the elements in this queue
422	+	*/
423	+	public Object[] toArray() {
424	+	return Arrays.copyOf(queue, size);
425	+	}
426	+
427	+	/**
428	+	* Returns an array containing all of the elements in this queue; the
429	+	* runtime type of the returned array is that of the specified array.
430	+	* The returned array elements are in no particular order.
431	+	* If the queue fits in the specified array, it is returned therein.
432	+	* Otherwise, a new array is allocated with the runtime type of the
433	+	* specified array and the size of this queue.
434	+	*
435	+	* <p>If the queue fits in the specified array with room to spare
436	+	* (i.e., the array has more elements than the queue), the element in
437	+	* the array immediately following the end of the collection is set to
438	+	* {@code null}.
439	+	*
440	+	* <p>Like the {@link #toArray()} method, this method acts as bridge between
441	+	* array-based and collection-based APIs.  Further, this method allows
442	+	* precise control over the runtime type of the output array, and may,
443	+	* under certain circumstances, be used to save allocation costs.
444	+	*
445	+	* <p>Suppose {@code x} is a queue known to contain only strings.
446	+	* The following code can be used to dump the queue into a newly
447	+	* allocated array of {@code String}:
448	+	*
449	+	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
450	+	*
451	+	* Note that {@code toArray(new Object[0])} is identical in function to
452	+	* {@code toArray()}.
453	+	*
454	+	* @param a the array into which the elements of the queue are to
455	+	*          be stored, if it is big enough; otherwise, a new array of the
456	+	*          same runtime type is allocated for this purpose.
457	+	* @return an array containing all of the elements in this queue
458	+	* @throws ArrayStoreException if the runtime type of the specified array
459	+	*         is not a supertype of the runtime type of every element in
460	+	*         this queue
461	+	* @throws NullPointerException if the specified array is null
462	+	*/
463	+	@SuppressWarnings("unchecked")
464	+	public <T> T[] toArray(T[] a) {
465	+	final int size = this.size;
466	+	if (a.length < size)
467	+	// Make a new array of a's runtime type, but my contents:
468	+	return (T[]) Arrays.copyOf(queue, size, a.getClass());
469	+	System.arraycopy(queue, 0, a, 0, size);
470	+	if (a.length > size)
471	+	a[size] = null;
472	+	return a;
473	+	}
474	+
475	+	/**
476		* Returns an iterator over the elements in this queue. The iterator
477		* does not return the elements in any particular order.
478		*
479	<	* @return an iterator over the elements in this queue.
479	>	* @return an iterator over the elements in this queue
480		*/
481		public Iterator<E> iterator() {
482		return new Itr();
483		}
484
485	<	private class Itr implements Iterator<E> {
361	<
485	>	private final class Itr implements Iterator<E> {
486		/**
487		* Index (into queue array) of element to be returned by
488		* subsequent call to next.
489		*/
490	<	private int cursor = 1;
490	>	private int cursor;
491
492		/**
493		* Index of element returned by most recent call to next,
494		* unless that element came from the forgetMeNot list.
495	<	* Reset to 0 if element is deleted by a call to remove.
495	>	* Set to -1 if element is deleted by a call to remove.
496		*/
497	<	private int lastRet = 0;
497	>	private int lastRet = -1;
498
499		/**
500	<	* The modCount value that the iterator believes that the backing
377	<	* List should have.  If this expectation is violated, the iterator
378	<	* has detected concurrent modification.
379	<	*/
380	<	private int expectedModCount = modCount;
381	<
382	<	/**
383	<	* A list of elements that were moved from the unvisited portion of
500	>	* A queue of elements that were moved from the unvisited portion of
501		* the heap into the visited portion as a result of "unlucky" element
502		* removals during the iteration.  (Unlucky element removals are those
503	<	* that require a fixup instead of a fixdown.)  We must visit all of
503	>	* that require a siftup instead of a siftdown.)  We must visit all of
504		* the elements in this list to complete the iteration.  We do this
505		* after we've completed the "normal" iteration.
506		*
507		* We expect that most iterations, even those involving removals,
508	<	* will not use need to store elements in this field.
508	>	* will not need to store elements in this field.
509		*/
510	<	private ArrayList<E> forgetMeNot = null;
510	>	private ArrayDeque<E> forgetMeNot;
511
512		/**
513		* Element returned by the most recent call to next iff that
514		* element was drawn from the forgetMeNot list.
515		*/
516	<	private Object lastRetElt = null;
516	>	private E lastRetElt;
517	>
518	>	/**
519	>	* The modCount value that the iterator believes that the backing
520	>	* Queue should have.  If this expectation is violated, the iterator
521	>	* has detected concurrent modification.
522	>	*/
523	>	private int expectedModCount = modCount;
524
525		public boolean hasNext() {
526	<	return cursor <= size || forgetMeNot != null;
526	>	return cursor < size ||
527	>	(forgetMeNot != null && !forgetMeNot.isEmpty());
528		}
529
530	+	@SuppressWarnings("unchecked")
531		public E next() {
532	<	checkForComodification();
533	<	E result;
534	<	if (cursor <= size) {
535	<	result = (E) queue[cursor];
536	<	lastRet = cursor++;
537	<	}
538	<	else if (forgetMeNot == null)
539	<	throw new NoSuchElementException();
540	<	else {
415	<	int remaining = forgetMeNot.size();
416	<	result = forgetMeNot.remove(remaining - 1);
417	<	if (remaining == 1)
418	<	forgetMeNot = null;
419	<	lastRet = 0;
420	<	lastRetElt = result;
532	>	if (expectedModCount != modCount)
533	>	throw new ConcurrentModificationException();
534	>	if (cursor < size)
535	>	return (E) queue[lastRet = cursor++];
536	>	if (forgetMeNot != null) {
537	>	lastRet = -1;
538	>	lastRetElt = forgetMeNot.poll();
539	>	if (lastRetElt != null)
540	>	return lastRetElt;
541		}
542	<	return result;
542	>	throw new NoSuchElementException();
543		}
544
545		public void remove() {
546	<	checkForComodification();
547	<
548	<	if (lastRet != 0) {
546	>	if (expectedModCount != modCount)
547	>	throw new ConcurrentModificationException();
548	>	if (lastRet != -1) {
549		E moved = PriorityQueue.this.removeAt(lastRet);
550	<	lastRet = 0;
551	<	if (moved == null) {
550	>	lastRet = -1;
551	>	if (moved == null)
552		cursor--;
553	<	} else {
553	>	else {
554		if (forgetMeNot == null)
555	<	forgetMeNot = new ArrayList<E>();
555	>	forgetMeNot = new ArrayDeque<>();
556		forgetMeNot.add(moved);
557		}
558		} else if (lastRetElt != null) {
559	<	PriorityQueue.this.remove(lastRetElt);
559	>	PriorityQueue.this.removeEq(lastRetElt);
560		lastRetElt = null;
561		} else {
562		throw new IllegalStateException();
563		}
444	–
564		expectedModCount = modCount;
565		}
447	–
448	–	final void checkForComodification() {
449	–	if (modCount != expectedModCount)
450	–	throw new ConcurrentModificationException();
451	–	}
566		}
567
568		public int size() {
#	Line 456 | Line 570 | public class PriorityQueue<E> extends Ab
570		}
571
572		/**
573	<	* Remove all elements from the priority queue.
573	>	* Removes all of the elements from this priority queue.
574	>	* The queue will be empty after this call returns.
575		*/
576		public void clear() {
577		modCount++;
578	<
464	<	// Null out element references to prevent memory leak
465	<	for (int i=1; i<=size; i++)
578	>	for (int i = 0; i < size; i++)
579		queue[i] = null;
467	–
580		size = 0;
581		}
582
583	+	@SuppressWarnings("unchecked")
584		public E poll() {
585		if (size == 0)
586		return null;
587	+	int s = --size;
588		modCount++;
589	<
590	<	E result = (E) queue[1];
591	<	queue[1] = queue[size];
592	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
593	<	if (size > 1)
480	<	fixDown(1);
481	<
589	>	E result = (E) queue[0];
590	>	E x = (E) queue[s];
591	>	queue[s] = null;
592	>	if (s != 0)
593	>	siftDown(0, x);
594		return result;
595		}
596
597		/**
598	<	* Removes and returns the ith element from queue.  (Recall that queue
487	<	* is one-based, so 1 <= i <= size.)
598	>	* Removes the ith element from queue.
599		*
600	<	* Normally this method leaves the elements at positions from 1 up to i-1,
601	<	* inclusive, untouched.  Under these circumstances, it returns null.
602	<	* Occasionally, in order to maintain the heap invariant, it must move
603	<	* the last element of the list to some index in the range [2, i-1],
604	<	* and move the element previously at position (i/2) to position i.
605	<	* Under these circumstances, this method returns the element that was
606	<	* previously at the end of the list and is now at some position between
607	<	* 2 and i-1 inclusive.
608	<	*/
609	<	private E removeAt(int i) {
610	<	assert i > 0 && i <= size;
600	>	* Normally this method leaves the elements at up to i-1,
601	>	* inclusive, untouched.  Under these circumstances, it returns
602	>	* null.  Occasionally, in order to maintain the heap invariant,
603	>	* it must swap a later element of the list with one earlier than
604	>	* i.  Under these circumstances, this method returns the element
605	>	* that was previously at the end of the list and is now at some
606	>	* position before i. This fact is used by iterator.remove so as to
607	>	* avoid missing traversing elements.
608	>	*/
609	>	@SuppressWarnings("unchecked")
610	>	E removeAt(int i) {
611	>	// assert i >= 0 && i < size;
612		modCount++;
613	<
614	<	E moved = (E) queue[size];
615	<	queue[i] = moved;
616	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
617	<	if (i <= size) {
618	<	fixDown(i);
613	>	int s = --size;
614	>	if (s == i) // removed last element
615	>	queue[i] = null;
616	>	else {
617	>	E moved = (E) queue[s];
618	>	queue[s] = null;
619	>	siftDown(i, moved);
620		if (queue[i] == moved) {
621	<	fixUp(i);
621	>	siftUp(i, moved);
622		if (queue[i] != moved)
623		return moved;
624		}
#	Line 514 | Line 627 | public class PriorityQueue<E> extends Ab
627		}
628
629		/**
630	<	* Establishes the heap invariant (described above) assuming the heap
631	<	* satisfies the invariant except possibly for the leaf-node indexed by k
632	<	* (which may have a nextExecutionTime less than its parent's).
633	<	*
634	<	* This method functions by "promoting" queue[k] up the hierarchy
635	<	* (by swapping it with its parent) repeatedly until queue[k]
636	<	* is greater than or equal to its parent.
637	<	*/
638	<	private void fixUp(int k) {
639	<	if (comparator == null) {
640	<	while (k > 1) {
641	<	int j = k >> 1;
642	<	if (((Comparable<E>)queue[j]).compareTo((E)queue[k]) <= 0)
643	<	break;
644	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
645	<	k = j;
646	<	}
647	<	} else {
648	<	while (k > 1) {
649	<	int j = k >>> 1;
650	<	if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
651	<	break;
652	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
653	<	k = j;
654	<	}
630	>	* Inserts item x at position k, maintaining heap invariant by
631	>	* promoting x up the tree until it is greater than or equal to
632	>	* its parent, or is the root.
633	>	*
634	>	* To simplify and speed up coercions and comparisons, the
635	>	* Comparable and Comparator versions are separated into different
636	>	* methods that are otherwise identical. (Similarly for siftDown.)
637	>	*
638	>	* @param k the position to fill
639	>	* @param x the item to insert
640	>	*/
641	>	private void siftUp(int k, E x) {
642	>	if (comparator != null)
643	>	siftUpUsingComparator(k, x);
644	>	else
645	>	siftUpComparable(k, x);
646	>	}
647	>
648	>	@SuppressWarnings("unchecked")
649	>	private void siftUpComparable(int k, E x) {
650	>	Comparable<? super E> key = (Comparable<? super E>) x;
651	>	while (k > 0) {
652	>	int parent = (k - 1) >>> 1;
653	>	Object e = queue[parent];
654	>	if (key.compareTo((E) e) >= 0)
655	>	break;
656	>	queue[k] = e;
657	>	k = parent;
658		}
659	+	queue[k] = key;
660	+	}
661	+
662	+	@SuppressWarnings("unchecked")
663	+	private void siftUpUsingComparator(int k, E x) {
664	+	while (k > 0) {
665	+	int parent = (k - 1) >>> 1;
666	+	Object e = queue[parent];
667	+	if (comparator.compare(x, (E) e) >= 0)
668	+	break;
669	+	queue[k] = e;
670	+	k = parent;
671	+	}
672	+	queue[k] = x;
673		}
674
675		/**
676	<	* Establishes the heap invariant (described above) in the subtree
677	<	* rooted at k, which is assumed to satisfy the heap invariant except
678	<	* possibly for node k itself (which may be greater than its children).
679	<	*
680	<	* This method functions by "demoting" queue[k] down the hierarchy
681	<	* (by swapping it with its smaller child) repeatedly until queue[k]
682	<	* is less than or equal to its children.
683	<	*/
684	<	private void fixDown(int k) {
685	<	int j;
686	<	if (comparator == null) {
687	<	while ((j = k << 1) <= size && (j > 0)) {
688	<	if (j<size &&
689	<	((Comparable<E>)queue[j]).compareTo((E)queue[j+1]) > 0)
690	<	j++; // j indexes smallest kid
691	<
692	<	if (((Comparable<E>)queue[k]).compareTo((E)queue[j]) <= 0)
693	<	break;
694	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
695	<	k = j;
696	<	}
697	<	} else {
698	<	while ((j = k << 1) <= size && (j > 0)) {
699	<	if (j<size &&
700	<	comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
701	<	j++; // j indexes smallest kid
702	<	if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
703	<	break;
704	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
705	<	k = j;
706	<	}
676	>	* Inserts item x at position k, maintaining heap invariant by
677	>	* demoting x down the tree repeatedly until it is less than or
678	>	* equal to its children or is a leaf.
679	>	*
680	>	* @param k the position to fill
681	>	* @param x the item to insert
682	>	*/
683	>	private void siftDown(int k, E x) {
684	>	if (comparator != null)
685	>	siftDownUsingComparator(k, x);
686	>	else
687	>	siftDownComparable(k, x);
688	>	}
689	>
690	>	@SuppressWarnings("unchecked")
691	>	private void siftDownComparable(int k, E x) {
692	>	Comparable<? super E> key = (Comparable<? super E>)x;
693	>	int half = size >>> 1;        // loop while a non-leaf
694	>	while (k < half) {
695	>	int child = (k << 1) + 1; // assume left child is least
696	>	Object c = queue[child];
697	>	int right = child + 1;
698	>	if (right < size &&
699	>	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
700	>	c = queue[child = right];
701	>	if (key.compareTo((E) c) <= 0)
702	>	break;
703	>	queue[k] = c;
704	>	k = child;
705	>	}
706	>	queue[k] = key;
707	>	}
708	>
709	>	@SuppressWarnings("unchecked")
710	>	private void siftDownUsingComparator(int k, E x) {
711	>	int half = size >>> 1;
712	>	while (k < half) {
713	>	int child = (k << 1) + 1;
714	>	Object c = queue[child];
715	>	int right = child + 1;
716	>	if (right < size &&
717	>	comparator.compare((E) c, (E) queue[right]) > 0)
718	>	c = queue[child = right];
719	>	if (comparator.compare(x, (E) c) <= 0)
720	>	break;
721	>	queue[k] = c;
722	>	k = child;
723		}
724	+	queue[k] = x;
725		}
726
727		/**
728		* Establishes the heap invariant (described above) in the entire tree,
729		* assuming nothing about the order of the elements prior to the call.
730	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
731		*/
732	+	@SuppressWarnings("unchecked")
733		private void heapify() {
734	<	for (int i = size/2; i >= 1; i--)
735	<	fixDown(i);
734	>	final Object[] es = queue;
735	>	final int half = (size >>> 1) - 1;
736	>	if (comparator == null)
737	>	for (int i = half; i >= 0; i--)
738	>	siftDownComparable(i, (E) es[i]);
739	>	else
740	>	for (int i = half; i >= 0; i--)
741	>	siftDownUsingComparator(i, (E) es[i]);
742		}
743
744		/**
745	<	* Returns the comparator used to order this collection, or <tt>null</tt>
746	<	* if this collection is sorted according to its elements natural ordering
747	<	* (using <tt>Comparable</tt>).
748	<	*
749	<	* @return the comparator used to order this collection, or <tt>null</tt>
750	<	* if this collection is sorted according to its elements natural ordering.
745	>	* Returns the comparator used to order the elements in this
746	>	* queue, or {@code null} if this queue is sorted according to
747	>	* the {@linkplain Comparable natural ordering} of its elements.
748	>	*
749	>	* @return the comparator used to order this queue, or
750	>	*         {@code null} if this queue is sorted according to the
751	>	*         natural ordering of its elements
752		*/
753		public Comparator<? super E> comparator() {
754		return comparator;
755		}
756
757		/**
758	<	* Save the state of the instance to a stream (that
603	<	* is, serialize it).
758	>	* Saves this queue to a stream (that is, serializes it).
759		*
605	–	* @serialData The length of the array backing the instance is
606	–	* emitted (int), followed by all of its elements (each an
607	–	* <tt>Object</tt>) in the proper order.
760		* @param s the stream
761	+	* @throws java.io.IOException if an I/O error occurs
762	+	* @serialData The length of the array backing the instance is
763	+	*             emitted (int), followed by all of its elements
764	+	*             (each an {@code Object}) in the proper order.
765		*/
766		private void writeObject(java.io.ObjectOutputStream s)
767	<	throws java.io.IOException{
767	>	throws java.io.IOException {
768		// Write out element count, and any hidden stuff
769		s.defaultWriteObject();
770
771	<	// Write out array length
772	<	s.writeInt(queue.length);
771	>	// Write out array length, for compatibility with 1.5 version
772	>	s.writeInt(Math.max(2, size + 1));
773
774	<	// Write out all elements in the proper order.
775	<	for (int i=1; i<=size; i++)
774	>	// Write out all elements in the "proper order".
775	>	for (int i = 0; i < size; i++)
776		s.writeObject(queue[i]);
777		}
778
779		/**
780	<	* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is,
781	<	* deserialize it).
780	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
781	>	* (that is, deserializes it).
782	>	*
783		* @param s the stream
784	+	* @throws ClassNotFoundException if the class of a serialized object
785	+	*         could not be found
786	+	* @throws java.io.IOException if an I/O error occurs
787		*/
788		private void readObject(java.io.ObjectInputStream s)
789		throws java.io.IOException, ClassNotFoundException {
790		// Read in size, and any hidden stuff
791		s.defaultReadObject();
792
793	<	// Read in array length and allocate array
794	<	int arrayLength = s.readInt();
795	<	queue = new Object[arrayLength];
796	<
797	<	// Read in all elements in the proper order.
798	<	for (int i=1; i<=size; i++)
799	<	queue[i] = (E) s.readObject();
793	>	// Read in (and discard) array length
794	>	s.readInt();
795	>
796	>	queue = new Object[size];
797	>
798	>	// Read in all elements.
799	>	for (int i = 0; i < size; i++)
800	>	queue[i] = s.readObject();
801	>
802	>	// Elements are guaranteed to be in "proper order", but the
803	>	// spec has never explained what that might be.
804	>	heapify();
805		}
806
807	+	/**
808	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
809	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
810	+	* queue. The spliterator does not traverse elements in any particular order
811	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
812	+	*
813	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
814	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
815	+	* Overriding implementations should document the reporting of additional
816	+	* characteristic values.
817	+	*
818	+	* @return a {@code Spliterator} over the elements in this queue
819	+	* @since 1.8
820	+	*/
821	+	public final Spliterator<E> spliterator() {
822	+	return new PriorityQueueSpliterator(0, -1, 0);
823	+	}
824	+
825	+	final class PriorityQueueSpliterator implements Spliterator<E> {
826	+	private int index;            // current index, modified on advance/split
827	+	private int fence;            // -1 until first use
828	+	private int expectedModCount; // initialized when fence set
829	+
830	+	/** Creates new spliterator covering the given range. */
831	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
832	+	this.index = origin;
833	+	this.fence = fence;
834	+	this.expectedModCount = expectedModCount;
835	+	}
836	+
837	+	private int getFence() { // initialize fence to size on first use
838	+	int hi;
839	+	if ((hi = fence) < 0) {
840	+	expectedModCount = modCount;
841	+	hi = fence = size;
842	+	}
843	+	return hi;
844	+	}
845	+
846	+	public PriorityQueueSpliterator trySplit() {
847	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
848	+	return (lo >= mid) ? null :
849	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
850	+	}
851	+
852	+	@SuppressWarnings("unchecked")
853	+	public void forEachRemaining(Consumer<? super E> action) {
854	+	if (action == null)
855	+	throw new NullPointerException();
856	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
857	+	final Object[] a = queue;
858	+	int i, hi; E e;
859	+	for (i = index, index = hi = fence; i < hi; i++) {
860	+	if ((e = (E) a[i]) == null)
861	+	break;      // must be CME
862	+	action.accept(e);
863	+	}
864	+	if (modCount != expectedModCount)
865	+	throw new ConcurrentModificationException();
866	+	}
867	+
868	+	@SuppressWarnings("unchecked")
869	+	public boolean tryAdvance(Consumer<? super E> action) {
870	+	if (action == null)
871	+	throw new NullPointerException();
872	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
873	+	int i;
874	+	if ((i = index) < fence) {
875	+	index = i + 1;
876	+	E e;
877	+	if ((e = (E) queue[i]) == null
878	+	|| modCount != expectedModCount)
879	+	throw new ConcurrentModificationException();
880	+	action.accept(e);
881	+	return true;
882	+	}
883	+	return false;
884	+	}
885	+
886	+	public long estimateSize() {
887	+	return getFence() - index;
888	+	}
889	+
890	+	public int characteristics() {
891	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
892	+	}
893	+	}
894		}

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