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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.58 by dl, Mon Nov 28 23:53:32 2005 UTC vs.
Revision 1.103 by jsr166, Wed Dec 31 09:37:20 2014 UTC

#	Line 1 | Line 1
1		/*
2	<	* %W% %E%
2	>	* Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
3	>	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4		*
5	<	* Copyright 2005 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	>	private 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 = 0; // 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 specified initial capacity
140		* that orders its elements according to the specified comparator.
141		*
142		* @param  initialCapacity the initial capacity for this priority queue
143	<	* @param  comparator the comparator that will be used to order
144	<	*         this priority queue.  If <tt>null</tt>, the <i>natural
145	<	*         ordering</i> of the elements will be used.
146	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is
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	>	* @throws IllegalArgumentException if {@code initialCapacity} is
147		*         less than 1
148		*/
149		public PriorityQueue(int initialCapacity,
#	Line 138 | Line 157 | public class PriorityQueue<E> extends Ab
157		}
158
159		/**
160	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
161	<	* specified collection.   If the specified collection is an
162	<	* instance of a {@link java.util.SortedSet} or is another
163	<	* <tt>PriorityQueue</tt>, the priority queue will be ordered
164	<	* according to the same ordering.  Otherwise, this priority queue
165	<	* will be ordered according to the natural ordering of its elements.
160	>	* Creates a {@code PriorityQueue} containing the elements in the
161	>	* specified collection.  If the specified collection is an instance of
162	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
163	>	* priority queue will be ordered according to the same ordering.
164	>	* Otherwise, this priority queue will be ordered according to the
165	>	* {@linkplain Comparable natural ordering} of its elements.
166		*
167		* @param  c the collection whose elements are to be placed
168		*         into this priority queue
#	Line 153 | Line 172 | public class PriorityQueue<E> extends Ab
172		* @throws NullPointerException if the specified collection or any
173		*         of its elements are null
174		*/
175	+	@SuppressWarnings("unchecked")
176		public PriorityQueue(Collection<? extends E> c) {
177	<	initFromCollection(c);
178	<	if (c instanceof SortedSet)
179	<	comparator = (Comparator<? super E>)
180	<	((SortedSet<? extends E>)c).comparator();
181	<	else if (c instanceof PriorityQueue)
182	<	comparator = (Comparator<? super E>)
183	<	((PriorityQueue<? extends E>)c).comparator();
177	>	if (c instanceof SortedSet<?>) {
178	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
179	>	this.comparator = (Comparator<? super E>) ss.comparator();
180	>	initElementsFromCollection(ss);
181	>	}
182	>	else if (c instanceof PriorityQueue<?>) {
183	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
184	>	this.comparator = (Comparator<? super E>) pq.comparator();
185	>	initFromPriorityQueue(pq);
186	>	}
187		else {
188	<	comparator = null;
189	<	heapify();
188	>	this.comparator = null;
189	>	initFromCollection(c);
190		}
191		}
192
193		/**
194	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
194	>	* Creates a {@code PriorityQueue} containing the elements in the
195		* specified priority queue.  This priority queue will be
196		* ordered according to the same ordering as the given priority
197		* queue.
198		*
199		* @param  c the priority queue whose elements are to be placed
200		*         into this priority queue
201	<	* @throws ClassCastException if elements of <tt>c</tt> cannot be
202	<	*         compared to one another according to <tt>c</tt>'s
201	>	* @throws ClassCastException if elements of {@code c} cannot be
202	>	*         compared to one another according to {@code c}'s
203		*         ordering
204		* @throws NullPointerException if the specified priority queue or any
205		*         of its elements are null
206		*/
207	+	@SuppressWarnings("unchecked")
208		public PriorityQueue(PriorityQueue<? extends E> c) {
209	<	comparator = (Comparator<? super E>)c.comparator();
210	<	initFromCollection(c);
209	>	this.comparator = (Comparator<? super E>) c.comparator();
210	>	initFromPriorityQueue(c);
211		}
212
213		/**
214	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
215	<	* specified sorted set.  This priority queue will be ordered
214	>	* Creates a {@code PriorityQueue} containing the elements in the
215	>	* specified sorted set.   This priority queue will be ordered
216		* according to the same ordering as the given sorted set.
217		*
218		* @param  c the sorted set whose elements are to be placed
219	<	*         into this priority queue.
219	>	*         into this priority queue
220		* @throws ClassCastException if elements of the specified sorted
221		*         set cannot be compared to one another according to the
222		*         sorted set's ordering
223		* @throws NullPointerException if the specified sorted set or any
224		*         of its elements are null
225		*/
226	+	@SuppressWarnings("unchecked")
227		public PriorityQueue(SortedSet<? extends E> c) {
228	<	comparator = (Comparator<? super E>)c.comparator();
229	<	initFromCollection(c);
228	>	this.comparator = (Comparator<? super E>) c.comparator();
229	>	initElementsFromCollection(c);
230		}
231
232	<	/**
233	<	* Initialize queue array with elements from the given Collection.
234	<	* @param c the collection
235	<	*/
236	<	private void initFromCollection(Collection<? extends E> c) {
232	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
233	>	if (c.getClass() == PriorityQueue.class) {
234	>	this.queue = c.toArray();
235	>	this.size = c.size();
236	>	} else {
237	>	initFromCollection(c);
238	>	}
239	>	}
240	>
241	>	private void initElementsFromCollection(Collection<? extends E> c) {
242		Object[] a = c.toArray();
243		// If c.toArray incorrectly doesn't return Object[], copy it.
244		if (a.getClass() != Object[].class)
245		a = Arrays.copyOf(a, a.length, Object[].class);
246	<	queue = a;
247	<	size = a.length;
246	>	int len = a.length;
247	>	if (len == 1 || this.comparator != null)
248	>	for (int i = 0; i < len; i++)
249	>	if (a[i] == null)
250	>	throw new NullPointerException();
251	>	this.queue = a;
252	>	this.size = a.length;
253	>	}
254	>
255	>	/**
256	>	* Initializes queue array with elements from the given Collection.
257	>	*
258	>	* @param c the collection
259	>	*/
260	>	private void initFromCollection(Collection<? extends E> c) {
261	>	initElementsFromCollection(c);
262	>	heapify();
263		}
264
265		/**
266	+	* The maximum size of array to allocate.
267	+	* Some VMs reserve some header words in an array.
268	+	* Attempts to allocate larger arrays may result in
269	+	* OutOfMemoryError: Requested array size exceeds VM limit
270	+	*/
271	+	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
272	+
273	+	/**
274		* Increases the capacity of the array.
275		*
276		* @param minCapacity the desired minimum capacity
277		*/
278		private void grow(int minCapacity) {
279	<	if (minCapacity < 0) // overflow
227	<	throw new OutOfMemoryError();
228	<	int oldCapacity = queue.length;
279	>	int oldCapacity = queue.length;
280		// Double size if small; else grow by 50%
281	<	int newCapacity = ((oldCapacity < 64)?
282	<	((oldCapacity + 1) * 2):
283	<	((oldCapacity / 2) * 3));
284	<	if (newCapacity < 0) // overflow
285	<	newCapacity = Integer.MAX_VALUE;
286	<	if (newCapacity < minCapacity)
236	<	newCapacity = minCapacity;
281	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
282	>	(oldCapacity + 2) :
283	>	(oldCapacity >> 1));
284	>	// overflow-conscious code
285	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
286	>	newCapacity = hugeCapacity(minCapacity);
287		queue = Arrays.copyOf(queue, newCapacity);
288		}
289
290	+	private static int hugeCapacity(int minCapacity) {
291	+	if (minCapacity < 0) // overflow
292	+	throw new OutOfMemoryError();
293	+	return (minCapacity > MAX_ARRAY_SIZE) ?
294	+	Integer.MAX_VALUE :
295	+	MAX_ARRAY_SIZE;
296	+	}
297	+
298		/**
299		* Inserts the specified element into this priority queue.
300		*
301	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
301	>	* @return {@code true} (as specified by {@link Collection#add})
302		* @throws ClassCastException if the specified element cannot be
303		*         compared with elements currently in this priority queue
304		*         according to the priority queue's ordering
#	Line 253 | Line 311 | public class PriorityQueue<E> extends Ab
311		/**
312		* Inserts the specified element into this priority queue.
313		*
314	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
314	>	* @return {@code true} (as specified by {@link Queue#offer})
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 274 | Line 332 | public class PriorityQueue<E> extends Ab
332		return true;
333		}
334
335	+	@SuppressWarnings("unchecked")
336		public E peek() {
337	<	if (size == 0)
279	<	return null;
280	<	return (E) queue[0];
337	>	return (size == 0) ? null : (E) queue[0];
338		}
339
340		private int indexOf(Object o) {
341	<	if (o != null) {
341	>	if (o != null) {
342		for (int i = 0; i < size; i++)
343		if (o.equals(queue[i]))
344		return i;
#	Line 291 | Line 348 | public class PriorityQueue<E> extends Ab
348
349		/**
350		* Removes a single instance of the specified element from this queue,
351	<	* if it is present.  More formally, removes an element <tt>e</tt> such
352	<	* that <tt>o.equals(e)</tt>, if this queue contains one or more such
353	<	* elements.  Returns true if this queue contained the specified element
354	<	* (or equivalently, if this queue changed as a result of the call).
351	>	* if it is present.  More formally, removes an element {@code e} such
352	>	* that {@code o.equals(e)}, if this queue contains one or more such
353	>	* elements.  Returns {@code true} if and only if this queue contained
354	>	* the specified element (or equivalently, if this queue changed as a
355	>	* result of the call).
356		*
357		* @param o element to be removed from this queue, if present
358	<	* @return <tt>true</tt> if this queue changed as a result of the call
358	>	* @return {@code true} if this queue changed as a result of the call
359		*/
360		public boolean remove(Object o) {
361	<	int i = indexOf(o);
362	<	if (i == -1)
363	<	return false;
364	<	else {
365	<	removeAt(i);
366	<	return true;
367	<	}
361	>	int i = indexOf(o);
362	>	if (i == -1)
363	>	return false;
364	>	else {
365	>	removeAt(i);
366	>	return true;
367	>	}
368		}
369
370		/**
371		* Version of remove using reference equality, not equals.
372	<	* Needed by iterator.remove
372	>	* Needed by iterator.remove.
373		*
374		* @param o element to be removed from this queue, if present
375	<	* @return <tt>true</tt> if removed.
375	>	* @return {@code true} if removed
376		*/
377		boolean removeEq(Object o) {
378	<	for (int i = 0; i < size; i++) {
379	<	if (o == queue[i]) {
378	>	for (int i = 0; i < size; i++) {
379	>	if (o == queue[i]) {
380		removeAt(i);
381		return true;
382		}
#	Line 327 | Line 385 | public class PriorityQueue<E> extends Ab
385		}
386
387		/**
388	<	* Returns <tt>true</tt> if this queue contains the specified element.
389	<	* More formally, returns <tt>true</tt> if and only if this queue contains
390	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
388	>	* Returns {@code true} if this queue contains the specified element.
389	>	* More formally, returns {@code true} if and only if this queue contains
390	>	* at least one element {@code e} such that {@code o.equals(e)}.
391		*
392		* @param o object to be checked for containment in this queue
393	<	* @return <tt>true</tt> if this queue contains the specified element
393	>	* @return {@code true} if this queue contains the specified element
394		*/
395		public boolean contains(Object o) {
396	<	return indexOf(o) != -1;
396	>	return indexOf(o) >= 0;
397		}
398
399		/**
400	<	* Returns an array containing all of the elements in this queue,
400	>	* Returns an array containing all of the elements in this queue.
401		* The elements are in no particular order.
402		*
403		* <p>The returned array will be "safe" in that no references to it are
404	<	* maintained by this list.  (In other words, this method must allocate
404	>	* maintained by this queue.  (In other words, this method must allocate
405		* a new array).  The caller is thus free to modify the returned array.
406		*
407	<	* @return an array containing all of the elements in this queue.
407	>	* <p>This method acts as bridge between array-based and collection-based
408	>	* APIs.
409	>	*
410	>	* @return an array containing all of the elements in this queue
411		*/
412		public Object[] toArray() {
413		return Arrays.copyOf(queue, size);
414		}
415
416		/**
417	<	* Returns an array containing all of the elements in this queue.
418	<	* The elements are in no particular order.  The runtime type of
419	<	* the returned array is that of the specified array.  If the queue
420	<	* fits in the specified array, it is returned therein.
421	<	* Otherwise, a new array is allocated with the runtime type of
422	<	* the specified array and the size of this queue.
417	>	* Returns an array containing all of the elements in this queue; the
418	>	* runtime type of the returned array is that of the specified array.
419	>	* The returned array elements are in no particular order.
420	>	* If the queue fits in the specified array, it is returned therein.
421	>	* Otherwise, a new array is allocated with the runtime type of the
422	>	* specified array and the size of this queue.
423		*
424		* <p>If the queue fits in the specified array with room to spare
425		* (i.e., the array has more elements than the queue), the element in
426		* the array immediately following the end of the collection is set to
427	<	* <tt>null</tt>.  (This is useful in determining the length of the
428	<	* queue <i>only</i> if the caller knows that the queue does not contain
429	<	* any null elements.)
427	>	* {@code null}.
428	>	*
429	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
430	>	* array-based and collection-based APIs.  Further, this method allows
431	>	* precise control over the runtime type of the output array, and may,
432	>	* under certain circumstances, be used to save allocation costs.
433	>	*
434	>	* <p>Suppose {@code x} is a queue known to contain only strings.
435	>	* The following code can be used to dump the queue into a newly
436	>	* allocated array of {@code String}:
437	>	*
438	>	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
439	>	*
440	>	* Note that {@code toArray(new Object[0])} is identical in function to
441	>	* {@code toArray()}.
442		*
443		* @param a the array into which the elements of the queue are to
444		*          be stored, if it is big enough; otherwise, a new array of the
445		*          same runtime type is allocated for this purpose.
446	<	* @return an array containing the elements of the queue
446	>	* @return an array containing all of the elements in this queue
447		* @throws ArrayStoreException if the runtime type of the specified array
448		*         is not a supertype of the runtime type of every element in
449		*         this queue
450		* @throws NullPointerException if the specified array is null
451		*/
452	+	@SuppressWarnings("unchecked")
453		public <T> T[] toArray(T[] a) {
454	+	final int size = this.size;
455		if (a.length < size)
456		// Make a new array of a's runtime type, but my contents:
457		return (T[]) Arrays.copyOf(queue, size, a.getClass());
458	<	System.arraycopy(queue, 0, a, 0, size);
458	>	System.arraycopy(queue, 0, a, 0, size);
459		if (a.length > size)
460		a[size] = null;
461		return a;
#	Line 401 | Line 476 | public class PriorityQueue<E> extends Ab
476		* Index (into queue array) of element to be returned by
477		* subsequent call to next.
478		*/
479	<	private int cursor = 0;
479	>	private int cursor;
480
481		/**
482		* Index of element returned by most recent call to next,
#	Line 419 | Line 494 | public class PriorityQueue<E> extends Ab
494		* after we've completed the "normal" iteration.
495		*
496		* We expect that most iterations, even those involving removals,
497	<	* will not use need to store elements in this field.
497	>	* will not need to store elements in this field.
498		*/
499	<	private ArrayDeque<E> forgetMeNot = null;
499	>	private ArrayDeque<E> forgetMeNot;
500
501		/**
502		* Element returned by the most recent call to next iff that
503		* element was drawn from the forgetMeNot list.
504		*/
505	<	private E lastRetElt = null;
505	>	private E lastRetElt;
506
507		/**
508		* The modCount value that the iterator believes that the backing
509	<	* List should have.  If this expectation is violated, the iterator
509	>	* Queue should have.  If this expectation is violated, the iterator
510		* has detected concurrent modification.
511		*/
512		private int expectedModCount = modCount;
#	Line 441 | Line 516 | public class PriorityQueue<E> extends Ab
516		(forgetMeNot != null && !forgetMeNot.isEmpty());
517		}
518
519	+	@SuppressWarnings("unchecked")
520		public E next() {
521		if (expectedModCount != modCount)
522		throw new ConcurrentModificationException();
#	Line 458 | Line 534 | public class PriorityQueue<E> extends Ab
534		public void remove() {
535		if (expectedModCount != modCount)
536		throw new ConcurrentModificationException();
461	–	if (lastRet == -1 && lastRetElt == null)
462	–	throw new IllegalStateException();
537		if (lastRet != -1) {
538		E moved = PriorityQueue.this.removeAt(lastRet);
539		lastRet = -1;
#	Line 467 | Line 541 | public class PriorityQueue<E> extends Ab
541		cursor--;
542		else {
543		if (forgetMeNot == null)
544	<	forgetMeNot = new ArrayDeque<E>();
544	>	forgetMeNot = new ArrayDeque<>();
545		forgetMeNot.add(moved);
546		}
547	<	} else {
547	>	} else if (lastRetElt != null) {
548		PriorityQueue.this.removeEq(lastRetElt);
549		lastRetElt = null;
550	+	} else {
551	+	throw new IllegalStateException();
552		}
553		expectedModCount = modCount;
554		}
479	–
555		}
556
557		public int size() {
#	Line 494 | Line 569 | public class PriorityQueue<E> extends Ab
569		size = 0;
570		}
571
572	+	@SuppressWarnings("unchecked")
573		public E poll() {
574		if (size == 0)
575		return null;
576		int s = --size;
577		modCount++;
578	<	E result = (E)queue[0];
579	<	E x = (E)queue[s];
578	>	E result = (E) queue[0];
579	>	E x = (E) queue[s];
580		queue[s] = null;
581		if (s != 0)
582		siftDown(0, x);
#	Line 517 | Line 593 | public class PriorityQueue<E> extends Ab
593		* i.  Under these circumstances, this method returns the element
594		* that was previously at the end of the list and is now at some
595		* position before i. This fact is used by iterator.remove so as to
596	<	* avoid missing traverseing elements.
596	>	* avoid missing traversing elements.
597		*/
598	+	@SuppressWarnings("unchecked")
599		private E removeAt(int i) {
600	<	assert i >= 0 && i < size;
600	>	// assert i >= 0 && i < size;
601		modCount++;
602		int s = --size;
603		if (s == i) // removed last element
#	Line 557 | Line 634 | public class PriorityQueue<E> extends Ab
634		siftUpComparable(k, x);
635		}
636
637	+	@SuppressWarnings("unchecked")
638		private void siftUpComparable(int k, E x) {
639		Comparable<? super E> key = (Comparable<? super E>) x;
640		while (k > 0) {
641		int parent = (k - 1) >>> 1;
642		Object e = queue[parent];
643	<	if (key.compareTo((E)e) >= 0)
643	>	if (key.compareTo((E) e) >= 0)
644		break;
645		queue[k] = e;
646		k = parent;
#	Line 570 | Line 648 | public class PriorityQueue<E> extends Ab
648		queue[k] = key;
649		}
650
651	+	@SuppressWarnings("unchecked")
652		private void siftUpUsingComparator(int k, E x) {
653		while (k > 0) {
654		int parent = (k - 1) >>> 1;
655		Object e = queue[parent];
656	<	if (comparator.compare(x, (E)e) >= 0)
656	>	if (comparator.compare(x, (E) e) >= 0)
657		break;
658		queue[k] = e;
659		k = parent;
#	Line 597 | Line 676 | public class PriorityQueue<E> extends Ab
676		siftDownComparable(k, x);
677		}
678
679	+	@SuppressWarnings("unchecked")
680		private void siftDownComparable(int k, E x) {
681		Comparable<? super E> key = (Comparable<? super E>)x;
682		int half = size >>> 1;        // loop while a non-leaf
#	Line 605 | Line 685 | public class PriorityQueue<E> extends Ab
685		Object c = queue[child];
686		int right = child + 1;
687		if (right < size &&
688	<	((Comparable<? super E>)c).compareTo((E)queue[right]) > 0)
688	>	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
689		c = queue[child = right];
690	<	if (key.compareTo((E)c) <= 0)
690	>	if (key.compareTo((E) c) <= 0)
691		break;
692		queue[k] = c;
693		k = child;
#	Line 615 | Line 695 | public class PriorityQueue<E> extends Ab
695		queue[k] = key;
696		}
697
698	+	@SuppressWarnings("unchecked")
699		private void siftDownUsingComparator(int k, E x) {
700		int half = size >>> 1;
701		while (k < half) {
#	Line 622 | Line 703 | public class PriorityQueue<E> extends Ab
703		Object c = queue[child];
704		int right = child + 1;
705		if (right < size &&
706	<	comparator.compare((E)c, (E)queue[right]) > 0)
706	>	comparator.compare((E) c, (E) queue[right]) > 0)
707		c = queue[child = right];
708	<	if (comparator.compare(x, (E)c) <= 0)
708	>	if (comparator.compare(x, (E) c) <= 0)
709		break;
710		queue[k] = c;
711		k = child;
#	Line 636 | Line 717 | public class PriorityQueue<E> extends Ab
717		* Establishes the heap invariant (described above) in the entire tree,
718		* assuming nothing about the order of the elements prior to the call.
719		*/
720	+	@SuppressWarnings("unchecked")
721		private void heapify() {
722		for (int i = (size >>> 1) - 1; i >= 0; i--)
723	<	siftDown(i, (E)queue[i]);
723	>	siftDown(i, (E) queue[i]);
724		}
725
726		/**
727		* Returns the comparator used to order the elements in this
728	<	* queue, or <tt>null</tt> if this queue is sorted according to
728	>	* queue, or {@code null} if this queue is sorted according to
729		* the {@linkplain Comparable natural ordering} of its elements.
730		*
731		* @return the comparator used to order this queue, or
732	<	*         <tt>null</tt> if this queue is sorted according to the
733	<	*         natural ordering of its elements.
732	>	*         {@code null} if this queue is sorted according to the
733	>	*         natural ordering of its elements
734		*/
735		public Comparator<? super E> comparator() {
736		return comparator;
737		}
738
739		/**
740	<	* Save the state of the instance to a stream (that
659	<	* is, serialize it).
740	>	* Saves this queue to a stream (that is, serializes it).
741		*
742		* @serialData The length of the array backing the instance is
743	<	* emitted (int), followed by all of its elements (each an
744	<	* <tt>Object</tt>) in the proper order.
743	>	*             emitted (int), followed by all of its elements
744	>	*             (each an {@code Object}) in the proper order.
745		* @param s the stream
746	+	* @throws java.io.IOException if an I/O error occurs
747		*/
748		private void writeObject(java.io.ObjectOutputStream s)
749	<	throws java.io.IOException{
749	>	throws java.io.IOException {
750		// Write out element count, and any hidden stuff
751		s.defaultWriteObject();
752
753	<	// Write out array length
754	<	// For compatibility with 1.5 version, must be at least 2.
673	<	s.writeInt(Math.max(2, queue.length));
753	>	// Write out array length, for compatibility with 1.5 version
754	>	s.writeInt(Math.max(2, size + 1));
755
756	<	// Write out all elements in the proper order.
757	<	for (int i=0; i<size; i++)
756	>	// Write out all elements in the "proper order".
757	>	for (int i = 0; i < size; i++)
758		s.writeObject(queue[i]);
759		}
760
761		/**
762	<	* Reconstitute the <tt>PriorityQueue</tt> instance from a stream
763	<	* (that is, deserialize it).
762	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
763	>	* (that is, deserializes it).
764	>	*
765		* @param s the stream
766	+	* @throws ClassNotFoundException if the class of a serialized object
767	+	*         could not be found
768	+	* @throws java.io.IOException if an I/O error occurs
769		*/
770		private void readObject(java.io.ObjectInputStream s)
771		throws java.io.IOException, ClassNotFoundException {
772		// Read in size, and any hidden stuff
773		s.defaultReadObject();
774
775	<	// Read in array length and allocate array
776	<	int arrayLength = s.readInt();
777	<	queue = new Object[arrayLength];
778	<
779	<	// Read in all elements in the proper order.
780	<	for (int i=0; i<size; i++)
781	<	queue[i] = (E) s.readObject();
775	>	// Read in (and discard) array length
776	>	s.readInt();
777	>
778	>	queue = new Object[size];
779	>
780	>	// Read in all elements.
781	>	for (int i = 0; i < size; i++)
782	>	queue[i] = s.readObject();
783	>
784	>	// Elements are guaranteed to be in "proper order", but the
785	>	// spec has never explained what that might be.
786	>	heapify();
787		}
788
789	+	public Spliterator<E> spliterator() {
790	+	return new PriorityQueueSpliterator<E>(this, 0, -1, 0);
791	+	}
792	+
793	+	/**
794	+	* This is very similar to ArrayList Spliterator, except for extra
795	+	* null checks.
796	+	*/
797	+	static final class PriorityQueueSpliterator<E> implements Spliterator<E> {
798	+	private final PriorityQueue<E> pq;
799	+	private int index;            // current index, modified on advance/split
800	+	private int fence;            // -1 until first use
801	+	private int expectedModCount; // initialized when fence set
802	+
803	+	/** Creates new spliterator covering the given range */
804	+	PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
805	+	int expectedModCount) {
806	+	this.pq = pq;
807	+	this.index = origin;
808	+	this.fence = fence;
809	+	this.expectedModCount = expectedModCount;
810	+	}
811	+
812	+	private int getFence() { // initialize fence to size on first use
813	+	int hi;
814	+	if ((hi = fence) < 0) {
815	+	expectedModCount = pq.modCount;
816	+	hi = fence = pq.size;
817	+	}
818	+	return hi;
819	+	}
820	+
821	+	public Spliterator<E> trySplit() {
822	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
823	+	return (lo >= mid) ? null :
824	+	new PriorityQueueSpliterator<E>(pq, lo, index = mid,
825	+	expectedModCount);
826	+	}
827	+
828	+	@SuppressWarnings("unchecked")
829	+	public void forEachRemaining(Consumer<? super E> action) {
830	+	int i, hi, mc; // hoist accesses and checks from loop
831	+	PriorityQueue<E> q; Object[] a;
832	+	if (action == null)
833	+	throw new NullPointerException();
834	+	if ((q = pq) != null && (a = q.queue) != null) {
835	+	if ((hi = fence) < 0) {
836	+	mc = q.modCount;
837	+	hi = q.size;
838	+	}
839	+	else
840	+	mc = expectedModCount;
841	+	if ((i = index) >= 0 && (index = hi) <= a.length) {
842	+	for (E e;; ++i) {
843	+	if (i < hi) {
844	+	if ((e = (E) a[i]) == null) // must be CME
845	+	break;
846	+	action.accept(e);
847	+	}
848	+	else if (q.modCount != mc)
849	+	break;
850	+	else
851	+	return;
852	+	}
853	+	}
854	+	}
855	+	throw new ConcurrentModificationException();
856	+	}
857	+
858	+	public boolean tryAdvance(Consumer<? super E> action) {
859	+	int hi = getFence(), lo = index;
860	+	if (lo >= 0 && lo < hi) {
861	+	index = lo + 1;
862	+	@SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
863	+	if (e == null)
864	+	throw new ConcurrentModificationException();
865	+	action.accept(e);
866	+	if (pq.modCount != expectedModCount)
867	+	throw new ConcurrentModificationException();
868	+	return true;
869	+	}
870	+	return false;
871	+	}
872	+
873	+	public long estimateSize() {
874	+	return (long) (getFence() - index);
875	+	}
876	+
877	+	public int characteristics() {
878	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
879	+	}
880	+	}
881		}

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