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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.56 by jsr166, Mon Nov 28 02:35:46 2005 UTC vs.
Revision 1.129 by jsr166, Mon Oct 1 00:10:53 2018 UTC

#	Line 1 | Line 1
1		/*
2	<	* @(#)PriorityQueue.java       1.8 05/08/27
2	>	* Copyright (c) 2003, 2018, 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	>	import java.util.function.Predicate;
30	>	import jdk.internal.misc.SharedSecrets;
31
32		/**
33	<	* An unbounded priority {@linkplain Queue queue} based on a priority
34	<	* heap.  The elements of the priority queue are ordered according to
35	<	* their {@linkplain Comparable natural ordering}, or by a {@link
36	<	* Comparator} provided at queue construction time, depending on which
37	<	* constructor is used.  A priority queue does not permit
38	<	* <tt>null</tt> elements.  A priority queue relying on natural
39	<	* ordering also does not permit insertion of non-comparable objects
40	<	* (doing so may result in <tt>ClassCastException</tt>).
33	>	* An unbounded priority {@linkplain Queue queue} based on a priority heap.
34	>	* The elements of the priority queue are ordered according to their
35	>	* {@linkplain Comparable natural ordering}, or by a {@link Comparator}
36	>	* provided at queue construction time, depending on which constructor is
37	>	* used.  A priority queue does not permit {@code null} elements.
38	>	* A priority queue relying on natural ordering also does not permit
39	>	* insertion of non-comparable objects (doing so may result in
40	>	* {@code ClassCastException}).
41		*
42		* <p>The <em>head</em> of this queue is the <em>least</em> element
43		* with respect to the specified ordering.  If multiple elements are
44		* tied for least value, the head is one of those elements -- ties are
45	<	* broken arbitrarily.  The queue retrieval operations <tt>poll</tt>,
46	<	* <tt>remove</tt>, <tt>peek</tt>, and <tt>element</tt> access the
45	>	* broken arbitrarily.  The queue retrieval operations {@code poll},
46	>	* {@code remove}, {@code peek}, and {@code element} access the
47		* element at the head of the queue.
48		*
49		* <p>A priority queue is unbounded, but has an internal
#	Line 35 | Line 56 | import java.util.*; // for javadoc (till
56		* <p>This class and its iterator implement all of the
57		* <em>optional</em> methods of the {@link Collection} and {@link
58		* Iterator} interfaces.  The Iterator provided in method {@link
59	<	* #iterator()} is <em>not</em> guaranteed to traverse the elements of
59	>	* #iterator()} and the Spliterator provided in method {@link #spliterator()}
60	>	* are <em>not</em> guaranteed to traverse the elements of
61		* the priority queue in any particular order. If you need ordered
62	<	* traversal, consider using <tt>Arrays.sort(pq.toArray())</tt>.
62	>	* traversal, consider using {@code Arrays.sort(pq.toArray())}.
63		*
64	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
65	<	* Multiple threads should not access a <tt>PriorityQueue</tt>
66	<	* instance concurrently if any of the threads modifies the list
67	<	* structurally. Instead, use the thread-safe {@link
64	>	* <p><strong>Note that this implementation is not synchronized.</strong>
65	>	* Multiple threads should not access a {@code PriorityQueue}
66	>	* instance concurrently if any of the threads modifies the queue.
67	>	* Instead, use the thread-safe {@link
68		* java.util.concurrent.PriorityBlockingQueue} class.
69		*
70	<	* <p>Implementation note: this implementation provides O(log(n)) time
71	<	* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
72	<	* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
73	<	* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
74	<	* constant time for the retrieval methods (<tt>peek</tt>,
75	<	* <tt>element</tt>, and <tt>size</tt>).
70	>	* <p>Implementation note: this implementation provides
71	>	* O(log(n)) time for the enqueuing and dequeuing methods
72	>	* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
73	>	* linear time for the {@code remove(Object)} and {@code contains(Object)}
74	>	* methods; and constant time for the retrieval methods
75	>	* ({@code peek}, {@code element}, and {@code size}).
76		*
77		* <p>This class is a member of the
78	<	* <a href="{@docRoot}/../guide/collections/index.html">
78	>	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
79		* Java Collections Framework</a>.
80	+	*
81		* @since 1.5
82	<	* @version 1.8, 08/27/05
83	<	* @author Josh Bloch
61	<	* @param <E> the type of elements held in this collection
82	>	* @author Josh Bloch, Doug Lea
83	>	* @param <E> the type of elements held in this queue
84		*/
85	+	@SuppressWarnings("unchecked")
86		public class PriorityQueue<E> extends AbstractQueue<E>
87		implements java.io.Serializable {
88
#	Line 75 | Line 98 | public class PriorityQueue<E> extends Ab
98		* heap and each descendant d of n, n <= d.  The element with the
99		* lowest value is in queue[0], assuming the queue is nonempty.
100		*/
101	<	private transient Object[] queue;
101	>	transient Object[] queue; // non-private to simplify nested class access
102
103		/**
104		* The number of elements in the priority queue.
105		*/
106	<	private int size = 0;
106	>	int size;
107
108		/**
109		* The comparator, or null if priority queue uses elements'
#	Line 92 | Line 115 | public class PriorityQueue<E> extends Ab
115		* The number of times this priority queue has been
116		* <i>structurally modified</i>.  See AbstractList for gory details.
117		*/
118	<	private transient int modCount = 0;
118	>	transient int modCount;     // non-private to simplify nested class access
119
120		/**
121	<	* Creates a <tt>PriorityQueue</tt> with the default initial
121	>	* Creates a {@code PriorityQueue} with the default initial
122		* capacity (11) that orders its elements according to their
123		* {@linkplain Comparable natural ordering}.
124		*/
#	Line 104 | Line 127 | public class PriorityQueue<E> extends Ab
127		}
128
129		/**
130	<	* Creates a <tt>PriorityQueue</tt> with the specified initial
130	>	* Creates a {@code PriorityQueue} with the specified initial
131		* capacity that orders its elements according to their
132		* {@linkplain Comparable natural ordering}.
133		*
134		* @param initialCapacity the initial capacity for this priority queue
135	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
136	<	* than 1
135	>	* @throws IllegalArgumentException if {@code initialCapacity} is less
136	>	*         than 1
137		*/
138		public PriorityQueue(int initialCapacity) {
139		this(initialCapacity, null);
140		}
141
142		/**
143	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
143	>	* Creates a {@code PriorityQueue} with the default initial capacity and
144	>	* whose elements are ordered according to the specified comparator.
145	>	*
146	>	* @param  comparator the comparator that will be used to order this
147	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
148	>	*         natural ordering} of the elements will be used.
149	>	* @since 1.8
150	>	*/
151	>	public PriorityQueue(Comparator<? super E> comparator) {
152	>	this(DEFAULT_INITIAL_CAPACITY, comparator);
153	>	}
154	>
155	>	/**
156	>	* Creates a {@code PriorityQueue} with the specified initial capacity
157		* that orders its elements according to the specified comparator.
158		*
159		* @param  initialCapacity the initial capacity for this priority queue
160	<	* @param  comparator the comparator that will be used to order
161	<	*         this priority queue.  If <tt>null</tt>, the <i>natural
162	<	*         ordering</i> of the elements will be used.
163	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is
160	>	* @param  comparator the comparator that will be used to order this
161	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
162	>	*         natural ordering} of the elements will be used.
163	>	* @throws IllegalArgumentException if {@code initialCapacity} is
164		*         less than 1
165		*/
166		public PriorityQueue(int initialCapacity,
#	Line 138 | Line 174 | public class PriorityQueue<E> extends Ab
174		}
175
176		/**
177	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
178	<	* specified collection.   If the specified collection is an
179	<	* instance of a {@link java.util.SortedSet} or is another
180	<	* <tt>PriorityQueue</tt>, the priority queue will be ordered
181	<	* according to the same ordering.  Otherwise, this priority queue
182	<	* will be ordered according to the natural ordering of its elements.
177	>	* Creates a {@code PriorityQueue} containing the elements in the
178	>	* specified collection.  If the specified collection is an instance of
179	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
180	>	* priority queue will be ordered according to the same ordering.
181	>	* Otherwise, this priority queue will be ordered according to the
182	>	* {@linkplain Comparable natural ordering} of its elements.
183		*
184		* @param  c the collection whose elements are to be placed
185		*         into this priority queue
#	Line 154 | Line 190 | public class PriorityQueue<E> extends Ab
190		*         of its elements are null
191		*/
192		public PriorityQueue(Collection<? extends E> c) {
193	<	initFromCollection(c);
194	<	if (c instanceof SortedSet)
195	<	comparator = (Comparator<? super E>)
196	<	((SortedSet<? extends E>)c).comparator();
197	<	else if (c instanceof PriorityQueue)
198	<	comparator = (Comparator<? super E>)
199	<	((PriorityQueue<? extends E>)c).comparator();
193	>	if (c instanceof SortedSet<?>) {
194	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
195	>	this.comparator = (Comparator<? super E>) ss.comparator();
196	>	initElementsFromCollection(ss);
197	>	}
198	>	else if (c instanceof PriorityQueue<?>) {
199	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
200	>	this.comparator = (Comparator<? super E>) pq.comparator();
201	>	initFromPriorityQueue(pq);
202	>	}
203		else {
204	<	comparator = null;
205	<	heapify();
204	>	this.comparator = null;
205	>	initFromCollection(c);
206		}
207		}
208
209		/**
210	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
210	>	* Creates a {@code PriorityQueue} containing the elements in the
211		* specified priority queue.  This priority queue will be
212		* ordered according to the same ordering as the given priority
213		* queue.
214		*
215		* @param  c the priority queue whose elements are to be placed
216		*         into this priority queue
217	<	* @throws ClassCastException if elements of <tt>c</tt> cannot be
218	<	*         compared to one another according to <tt>c</tt>'s
217	>	* @throws ClassCastException if elements of {@code c} cannot be
218	>	*         compared to one another according to {@code c}'s
219		*         ordering
220		* @throws NullPointerException if the specified priority queue or any
221		*         of its elements are null
222		*/
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
#	Line 200 | Line 239 | public class PriorityQueue<E> extends Ab
239		*         of its elements are null
240		*/
241		public PriorityQueue(SortedSet<? extends E> c) {
242	<	comparator = (Comparator<? super E>)c.comparator();
243	<	initFromCollection(c);
242	>	this.comparator = (Comparator<? super E>) c.comparator();
243	>	initElementsFromCollection(c);
244	>	}
245	>
246	>	/** Ensures that queue[0] exists, helping peek() and poll(). */
247	>	private static Object[] ensureNonEmpty(Object[] es) {
248	>	return (es.length > 0) ? es : new Object[1];
249	>	}
250	>
251	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
252	>	if (c.getClass() == PriorityQueue.class) {
253	>	this.queue = ensureNonEmpty(c.toArray());
254	>	this.size = c.size();
255	>	} else {
256	>	initFromCollection(c);
257	>	}
258	>	}
259	>
260	>	private void initElementsFromCollection(Collection<? extends E> c) {
261	>	Object[] es = c.toArray();
262	>	int len = es.length;
263	>	// If c.toArray incorrectly doesn't return Object[], copy it.
264	>	if (es.getClass() != Object[].class)
265	>	es = Arrays.copyOf(es, len, Object[].class);
266	>	if (len == 1 || this.comparator != null)
267	>	for (Object e : es)
268	>	if (e == null)
269	>	throw new NullPointerException();
270	>	this.queue = ensureNonEmpty(es);
271	>	this.size = len;
272		}
273
274		/**
275	<	* Initialize queue array with elements from the given Collection.
275	>	* Initializes queue array with elements from the given Collection.
276	>	*
277		* @param c the collection
278		*/
279		private void initFromCollection(Collection<? extends E> c) {
280	<	Object[] a = c.toArray();
281	<	// If c.toArray incorrectly doesn't return Object[], copy it.
214	<	if (a.getClass() != Object[].class)
215	<	a = Arrays.copyOf(a, a.length, Object[].class);
216	<	queue = a;
217	<	size = a.length;
280	>	initElementsFromCollection(c);
281	>	heapify();
282		}
283
284		/**
285	+	* The maximum size of array to allocate.
286	+	* Some VMs reserve some header words in an array.
287	+	* Attempts to allocate larger arrays may result in
288	+	* OutOfMemoryError: Requested array size exceeds VM limit
289	+	*/
290	+	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
291	+
292	+	/**
293		* Increases the capacity of the array.
294		*
295		* @param minCapacity the desired minimum capacity
296		*/
297		private void grow(int minCapacity) {
298	<	if (minCapacity < 0) // overflow
227	<	throw new OutOfMemoryError();
228	<	int oldCapacity = queue.length;
298	>	int oldCapacity = queue.length;
299		// Double size if small; else grow by 50%
300	<	int newCapacity = ((oldCapacity < 64)?
301	<	((oldCapacity + 1) * 2):
302	<	((oldCapacity * 3) / 2));
303	<	if (newCapacity < minCapacity)
304	<	newCapacity = minCapacity;
300	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
301	>	(oldCapacity + 2) :
302	>	(oldCapacity >> 1));
303	>	// overflow-conscious code
304	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
305	>	newCapacity = hugeCapacity(minCapacity);
306		queue = Arrays.copyOf(queue, newCapacity);
307		}
308
309	+	private static int hugeCapacity(int minCapacity) {
310	+	if (minCapacity < 0) // overflow
311	+	throw new OutOfMemoryError();
312	+	return (minCapacity > MAX_ARRAY_SIZE) ?
313	+	Integer.MAX_VALUE :
314	+	MAX_ARRAY_SIZE;
315	+	}
316	+
317		/**
318		* Inserts the specified element into this priority queue.
319		*
320	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
320	>	* @return {@code true} (as specified by {@link Collection#add})
321		* @throws ClassCastException if the specified element cannot be
322		*         compared with elements currently in this priority queue
323		*         according to the priority queue's ordering
#	Line 251 | Line 330 | public class PriorityQueue<E> extends Ab
330		/**
331		* Inserts the specified element into this priority queue.
332		*
333	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
333	>	* @return {@code true} (as specified by {@link Queue#offer})
334		* @throws ClassCastException if the specified element cannot be
335		*         compared with elements currently in this priority queue
336		*         according to the priority queue's ordering
#	Line 264 | Line 343 | public class PriorityQueue<E> extends Ab
343		int i = size;
344		if (i >= queue.length)
345		grow(i + 1);
346	+	siftUp(i, e);
347		size = i + 1;
268	–	if (i == 0)
269	–	queue[0] = e;
270	–	else
271	–	siftUp(i, e);
348		return true;
349		}
350
351		public E peek() {
276	–	if (size == 0)
277	–	return null;
352		return (E) queue[0];
353		}
354
355		private int indexOf(Object o) {
356	<	if (o != null) {
357	<	for (int i = 0; i < size; i++)
358	<	if (o.equals(queue[i]))
356	>	if (o != null) {
357	>	final Object[] es = queue;
358	>	for (int i = 0, n = size; i < n; i++)
359	>	if (o.equals(es[i]))
360		return i;
361		}
362		return -1;
#	Line 289 | Line 364 | public class PriorityQueue<E> extends Ab
364
365		/**
366		* Removes a single instance of the specified element from this queue,
367	<	* if it is present.  More formally, removes an element <tt>e</tt> such
368	<	* that <tt>o.equals(e)</tt>, if this queue contains one or more such
369	<	* elements.  Returns true if this queue contained the specified element
370	<	* (or equivalently, if this queue changed as a result of the call).
367	>	* if it is present.  More formally, removes an element {@code e} such
368	>	* that {@code o.equals(e)}, if this queue contains one or more such
369	>	* elements.  Returns {@code true} if and only if this queue contained
370	>	* the specified element (or equivalently, if this queue changed as a
371	>	* result of the call).
372		*
373		* @param o element to be removed from this queue, if present
374	<	* @return <tt>true</tt> if this queue changed as a result of the call
374	>	* @return {@code true} if this queue changed as a result of the call
375		*/
376		public boolean remove(Object o) {
377	<	int i = indexOf(o);
378	<	if (i == -1)
379	<	return false;
380	<	else {
381	<	removeAt(i);
382	<	return true;
383	<	}
377	>	int i = indexOf(o);
378	>	if (i == -1)
379	>	return false;
380	>	else {
381	>	removeAt(i);
382	>	return true;
383	>	}
384		}
385
386		/**
387	<	* Version of remove using reference equality, not equals.
312	<	* Needed by iterator.remove
387	>	* Identity-based version for use in Itr.remove.
388		*
389		* @param o element to be removed from this queue, if present
315	–	* @return <tt>true</tt> if removed.
390		*/
391	<	boolean removeEq(Object o) {
392	<	for (int i = 0; i < size; i++) {
393	<	if (o == queue[i]) {
391	>	void removeEq(Object o) {
392	>	final Object[] es = queue;
393	>	for (int i = 0, n = size; i < n; i++) {
394	>	if (o == es[i]) {
395		removeAt(i);
396	<	return true;
396	>	break;
397		}
398		}
324	–	return false;
399		}
400
401		/**
402	<	* Returns <tt>true</tt> if this queue contains the specified element.
403	<	* More formally, returns <tt>true</tt> if and only if this queue contains
404	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
402	>	* Returns {@code true} if this queue contains the specified element.
403	>	* More formally, returns {@code true} if and only if this queue contains
404	>	* at least one element {@code e} such that {@code o.equals(e)}.
405		*
406		* @param o object to be checked for containment in this queue
407	<	* @return <tt>true</tt> if this queue contains the specified element
407	>	* @return {@code true} if this queue contains the specified element
408		*/
409		public boolean contains(Object o) {
410	<	return indexOf(o) != -1;
410	>	return indexOf(o) >= 0;
411		}
412
413		/**
414	<	* Returns an array containing all of the elements in this queue,
414	>	* Returns an array containing all of the elements in this queue.
415		* The elements are in no particular order.
416		*
417		* <p>The returned array will be "safe" in that no references to it are
418	<	* maintained by this list.  (In other words, this method must allocate
418	>	* maintained by this queue.  (In other words, this method must allocate
419		* a new array).  The caller is thus free to modify the returned array.
420		*
421	<	* @return an array containing all of the elements in this queue.
421	>	* <p>This method acts as bridge between array-based and collection-based
422	>	* APIs.
423	>	*
424	>	* @return an array containing all of the elements in this queue
425		*/
426		public Object[] toArray() {
427		return Arrays.copyOf(queue, size);
428		}
429
430		/**
431	<	* Returns an array containing all of the elements in this queue.
432	<	* The elements are in no particular order.  The runtime type of
433	<	* the returned array is that of the specified array.  If the queue
434	<	* fits in the specified array, it is returned therein.
435	<	* Otherwise, a new array is allocated with the runtime type of
436	<	* the specified array and the size of this queue.
431	>	* Returns an array containing all of the elements in this queue; the
432	>	* runtime type of the returned array is that of the specified array.
433	>	* The returned array elements are in no particular order.
434	>	* If the queue fits in the specified array, it is returned therein.
435	>	* Otherwise, a new array is allocated with the runtime type of the
436	>	* specified array and the size of this queue.
437		*
438		* <p>If the queue fits in the specified array with room to spare
439		* (i.e., the array has more elements than the queue), the element in
440		* the array immediately following the end of the collection is set to
441	<	* <tt>null</tt>.  (This is useful in determining the length of the
442	<	* queue <i>only</i> if the caller knows that the queue does not contain
443	<	* any null elements.)
441	>	* {@code null}.
442	>	*
443	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
444	>	* array-based and collection-based APIs.  Further, this method allows
445	>	* precise control over the runtime type of the output array, and may,
446	>	* under certain circumstances, be used to save allocation costs.
447	>	*
448	>	* <p>Suppose {@code x} is a queue known to contain only strings.
449	>	* The following code can be used to dump the queue into a newly
450	>	* allocated array of {@code String}:
451	>	*
452	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
453	>	*
454	>	* Note that {@code toArray(new Object[0])} is identical in function to
455	>	* {@code toArray()}.
456		*
457		* @param a the array into which the elements of the queue are to
458		*          be stored, if it is big enough; otherwise, a new array of the
459		*          same runtime type is allocated for this purpose.
460	<	* @return an array containing the elements of the queue
460	>	* @return an array containing all of the elements in this queue
461		* @throws ArrayStoreException if the runtime type of the specified array
462		*         is not a supertype of the runtime type of every element in
463		*         this queue
464		* @throws NullPointerException if the specified array is null
465		*/
466		public <T> T[] toArray(T[] a) {
467	+	final int size = this.size;
468		if (a.length < size)
469		// Make a new array of a's runtime type, but my contents:
470		return (T[]) Arrays.copyOf(queue, size, a.getClass());
471	<	System.arraycopy(queue, 0, a, 0, size);
471	>	System.arraycopy(queue, 0, a, 0, size);
472		if (a.length > size)
473		a[size] = null;
474		return a;
#	Line 399 | Line 489 | public class PriorityQueue<E> extends Ab
489		* Index (into queue array) of element to be returned by
490		* subsequent call to next.
491		*/
492	<	private int cursor = 0;
492	>	private int cursor;
493
494		/**
495		* Index of element returned by most recent call to next,
#	Line 417 | Line 507 | public class PriorityQueue<E> extends Ab
507		* after we've completed the "normal" iteration.
508		*
509		* We expect that most iterations, even those involving removals,
510	<	* will not use need to store elements in this field.
510	>	* will not need to store elements in this field.
511		*/
512	<	private ArrayDeque<E> forgetMeNot = null;
512	>	private ArrayDeque<E> forgetMeNot;
513
514		/**
515		* Element returned by the most recent call to next iff that
516		* element was drawn from the forgetMeNot list.
517		*/
518	<	private E lastRetElt = null;
518	>	private E lastRetElt;
519
520		/**
521		* The modCount value that the iterator believes that the backing
522	<	* List should have.  If this expectation is violated, the iterator
522	>	* Queue should have.  If this expectation is violated, the iterator
523		* has detected concurrent modification.
524		*/
525		private int expectedModCount = modCount;
526
527	+	Itr() {}                        // prevent access constructor creation
528	+
529		public boolean hasNext() {
530		return cursor < size ||
531		(forgetMeNot != null && !forgetMeNot.isEmpty());
#	Line 456 | Line 548 | public class PriorityQueue<E> extends Ab
548		public void remove() {
549		if (expectedModCount != modCount)
550		throw new ConcurrentModificationException();
459	–	if (lastRet == -1 && lastRetElt == null)
460	–	throw new IllegalStateException();
551		if (lastRet != -1) {
552		E moved = PriorityQueue.this.removeAt(lastRet);
553		lastRet = -1;
#	Line 465 | 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		}
477	–
569		}
570
571		public int size() {
#	Line 487 | Line 578 | public class PriorityQueue<E> extends Ab
578		*/
579		public void clear() {
580		modCount++;
581	<	for (int i = 0; i < size; i++)
582	<	queue[i] = null;
581	>	final Object[] es = queue;
582	>	for (int i = 0, n = size; i < n; i++)
583	>	es[i] = null;
584		size = 0;
585		}
586
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];
594	<	queue[s] = null;
595	<	if (s != 0)
596	<	siftDown(0, x);
588	>	final Object[] es;
589	>	final E result;
590	>
591	>	if ((result = (E) ((es = queue)[0])) != null) {
592	>	modCount++;
593	>	final int n;
594	>	final E x = (E) es[(n = --size)];
595	>	es[n] = null;
596	>	if (n > 0) {
597	>	final Comparator<? super E> cmp;
598	>	if ((cmp = comparator) == null)
599	>	siftDownComparable(0, x, es, n);
600	>	else
601	>	siftDownUsingComparator(0, x, es, n, cmp);
602	>	}
603	>	}
604		return result;
605		}
606
#	Line 515 | Line 614 | public class PriorityQueue<E> extends Ab
614		* i.  Under these circumstances, this method returns the element
615		* that was previously at the end of the list and is now at some
616		* position before i. This fact is used by iterator.remove so as to
617	<	* avoid missing traverseing elements.
617	>	* avoid missing traversing elements.
618		*/
619	<	private E removeAt(int i) {
620	<	assert i >= 0 && i < size;
619	>	E removeAt(int i) {
620	>	// assert i >= 0 && i < size;
621	>	final Object[] es = queue;
622		modCount++;
623		int s = --size;
624		if (s == i) // removed last element
625	<	queue[i] = null;
625	>	es[i] = null;
626		else {
627	<	E moved = (E) queue[s];
628	<	queue[s] = null;
627	>	E moved = (E) es[s];
628	>	es[s] = null;
629		siftDown(i, moved);
630	<	if (queue[i] == moved) {
630	>	if (es[i] == moved) {
631		siftUp(i, moved);
632	<	if (queue[i] != moved)
632	>	if (es[i] != moved)
633		return moved;
634		}
635		}
#	Line 541 | Line 641 | public class PriorityQueue<E> extends Ab
641		* promoting x up the tree until it is greater than or equal to
642		* its parent, or is the root.
643		*
644	<	* To simplify and speed up coercions and comparisons. the
644	>	* To simplify and speed up coercions and comparisons, the
645		* Comparable and Comparator versions are separated into different
646		* methods that are otherwise identical. (Similarly for siftDown.)
647		*
#	Line 550 | Line 650 | public class PriorityQueue<E> extends Ab
650		*/
651		private void siftUp(int k, E x) {
652		if (comparator != null)
653	<	siftUpUsingComparator(k, x);
653	>	siftUpUsingComparator(k, x, queue, comparator);
654		else
655	<	siftUpComparable(k, x);
655	>	siftUpComparable(k, x, queue);
656		}
657
658	<	private void siftUpComparable(int k, E x) {
659	<	Comparable<? super E> key = (Comparable<? super E>) x;
658	>	private static <T> void siftUpComparable(int k, T x, Object[] es) {
659	>	Comparable<? super T> key = (Comparable<? super T>) x;
660		while (k > 0) {
661		int parent = (k - 1) >>> 1;
662	<	Object e = queue[parent];
663	<	if (key.compareTo((E)e) >= 0)
662	>	Object e = es[parent];
663	>	if (key.compareTo((T) e) >= 0)
664		break;
665	<	queue[k] = e;
665	>	es[k] = e;
666		k = parent;
667		}
668	<	queue[k] = key;
668	>	es[k] = key;
669		}
670
671	<	private void siftUpUsingComparator(int k, E x) {
671	>	private static <T> void siftUpUsingComparator(
672	>	int k, T x, Object[] es, Comparator<? super T> cmp) {
673		while (k > 0) {
674		int parent = (k - 1) >>> 1;
675	<	Object e = queue[parent];
676	<	if (comparator.compare(x, (E)e) >= 0)
675	>	Object e = es[parent];
676	>	if (cmp.compare(x, (T) e) >= 0)
677		break;
678	<	queue[k] = e;
678	>	es[k] = e;
679		k = parent;
680		}
681	<	queue[k] = x;
681	>	es[k] = x;
682		}
683
684		/**
#	Line 590 | Line 691 | public class PriorityQueue<E> extends Ab
691		*/
692		private void siftDown(int k, E x) {
693		if (comparator != null)
694	<	siftDownUsingComparator(k, x);
694	>	siftDownUsingComparator(k, x, queue, size, comparator);
695		else
696	<	siftDownComparable(k, x);
696	>	siftDownComparable(k, x, queue, size);
697		}
698
699	<	private void siftDownComparable(int k, E x) {
700	<	Comparable<? super E> key = (Comparable<? super E>)x;
701	<	int half = size >>> 1;        // loop while a non-leaf
699	>	private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
700	>	// assert n > 0;
701	>	Comparable<? super T> key = (Comparable<? super T>)x;
702	>	int half = n >>> 1;           // loop while a non-leaf
703		while (k < half) {
704		int child = (k << 1) + 1; // assume left child is least
705	<	Object c = queue[child];
705	>	Object c = es[child];
706		int right = child + 1;
707	<	if (right < size &&
708	<	((Comparable<? super E>)c).compareTo((E)queue[right]) > 0)
709	<	c = queue[child = right];
710	<	if (key.compareTo((E)c) <= 0)
707	>	if (right < n &&
708	>	((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
709	>	c = es[child = right];
710	>	if (key.compareTo((T) c) <= 0)
711		break;
712	<	queue[k] = c;
712	>	es[k] = c;
713		k = child;
714		}
715	<	queue[k] = key;
715	>	es[k] = key;
716		}
717
718	<	private void siftDownUsingComparator(int k, E x) {
719	<	int half = size >>> 1;
718	>	private static <T> void siftDownUsingComparator(
719	>	int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
720	>	// assert n > 0;
721	>	int half = n >>> 1;
722		while (k < half) {
723		int child = (k << 1) + 1;
724	<	Object c = queue[child];
724	>	Object c = es[child];
725		int right = child + 1;
726	<	if (right < size &&
727	<	comparator.compare((E)c, (E)queue[right]) > 0)
728	<	c = queue[child = right];
625	<	if (comparator.compare(x, (E)c) <= 0)
726	>	if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
727	>	c = es[child = right];
728	>	if (cmp.compare(x, (T) c) <= 0)
729		break;
730	<	queue[k] = c;
730	>	es[k] = c;
731		k = child;
732		}
733	<	queue[k] = x;
733	>	es[k] = x;
734		}
735
736		/**
737		* Establishes the heap invariant (described above) in the entire tree,
738		* assuming nothing about the order of the elements prior to the call.
739	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
740		*/
741		private void heapify() {
742	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
743	<	siftDown(i, (E)queue[i]);
742	>	final Object[] es = queue;
743	>	int n = size, i = (n >>> 1) - 1;
744	>	final Comparator<? super E> cmp;
745	>	if ((cmp = comparator) == null)
746	>	for (; i >= 0; i--)
747	>	siftDownComparable(i, (E) es[i], es, n);
748	>	else
749	>	for (; i >= 0; i--)
750	>	siftDownUsingComparator(i, (E) es[i], es, n, cmp);
751		}
752
753		/**
754		* Returns the comparator used to order the elements in this
755	<	* queue, or <tt>null</tt> if this queue is sorted according to
755	>	* queue, or {@code null} if this queue is sorted according to
756		* the {@linkplain Comparable natural ordering} of its elements.
757		*
758		* @return the comparator used to order this queue, or
759	<	*         <tt>null</tt> if this queue is sorted according to the
760	<	*         natural ordering of its elements.
759	>	*         {@code null} if this queue is sorted according to the
760	>	*         natural ordering of its elements
761		*/
762		public Comparator<? super E> comparator() {
763		return comparator;
764		}
765
766		/**
767	<	* Save the state of the instance to a stream (that
657	<	* is, serialize it).
767	>	* Saves this queue to a stream (that is, serializes it).
768		*
659	–	* @serialData The length of the array backing the instance is
660	–	* emitted (int), followed by all of its elements (each an
661	–	* <tt>Object</tt>) in the proper order.
769		* @param s the stream
770	+	* @throws java.io.IOException if an I/O error occurs
771	+	* @serialData The length of the array backing the instance is
772	+	*             emitted (int), followed by all of its elements
773	+	*             (each an {@code Object}) in the proper order.
774		*/
775		private void writeObject(java.io.ObjectOutputStream s)
776	<	throws java.io.IOException{
776	>	throws java.io.IOException {
777		// Write out element count, and any hidden stuff
778		s.defaultWriteObject();
779
780	<	// Write out array length
781	<	// For compatibility with 1.5 version, must be at least 2.
671	<	s.writeInt(Math.max(2, queue.length));
780	>	// Write out array length, for compatibility with 1.5 version
781	>	s.writeInt(Math.max(2, size + 1));
782
783	<	// Write out all elements in the proper order.
784	<	for (int i=0; i<size; i++)
785	<	s.writeObject(queue[i]);
783	>	// Write out all elements in the "proper order".
784	>	final Object[] es = queue;
785	>	for (int i = 0, n = size; i < n; i++)
786	>	s.writeObject(es[i]);
787		}
788
789		/**
790	<	* Reconstitute the <tt>PriorityQueue</tt> instance from a stream
791	<	* (that is, deserialize it).
790	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
791	>	* (that is, deserializes it).
792	>	*
793		* @param s the stream
794	+	* @throws ClassNotFoundException if the class of a serialized object
795	+	*         could not be found
796	+	* @throws java.io.IOException if an I/O error occurs
797		*/
798		private void readObject(java.io.ObjectInputStream s)
799		throws java.io.IOException, ClassNotFoundException {
800		// Read in size, and any hidden stuff
801		s.defaultReadObject();
802
803	<	// Read in array length and allocate array
804	<	int arrayLength = s.readInt();
805	<	queue = new Object[arrayLength];
806	<
807	<	// Read in all elements in the proper order.
808	<	for (int i=0; i<size; i++)
809	<	queue[i] = (E) s.readObject();
803	>	// Read in (and discard) array length
804	>	s.readInt();
805	>
806	>	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
807	>	final Object[] es = queue = new Object[Math.max(size, 1)];
808	>
809	>	// Read in all elements.
810	>	for (int i = 0, n = size; i < n; i++)
811	>	es[i] = s.readObject();
812	>
813	>	// Elements are guaranteed to be in "proper order", but the
814	>	// spec has never explained what that might be.
815	>	heapify();
816	>	}
817	>
818	>	/**
819	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
820	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
821	>	* queue. The spliterator does not traverse elements in any particular order
822	>	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
823	>	*
824	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
825	>	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
826	>	* Overriding implementations should document the reporting of additional
827	>	* characteristic values.
828	>	*
829	>	* @return a {@code Spliterator} over the elements in this queue
830	>	* @since 1.8
831	>	*/
832	>	public final Spliterator<E> spliterator() {
833	>	return new PriorityQueueSpliterator(0, -1, 0);
834		}
835
836	+	final class PriorityQueueSpliterator implements Spliterator<E> {
837	+	private int index;            // current index, modified on advance/split
838	+	private int fence;            // -1 until first use
839	+	private int expectedModCount; // initialized when fence set
840	+
841	+	/** Creates new spliterator covering the given range. */
842	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
843	+	this.index = origin;
844	+	this.fence = fence;
845	+	this.expectedModCount = expectedModCount;
846	+	}
847	+
848	+	private int getFence() { // initialize fence to size on first use
849	+	int hi;
850	+	if ((hi = fence) < 0) {
851	+	expectedModCount = modCount;
852	+	hi = fence = size;
853	+	}
854	+	return hi;
855	+	}
856	+
857	+	public PriorityQueueSpliterator trySplit() {
858	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
859	+	return (lo >= mid) ? null :
860	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
861	+	}
862	+
863	+	public void forEachRemaining(Consumer<? super E> action) {
864	+	if (action == null)
865	+	throw new NullPointerException();
866	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
867	+	final Object[] es = queue;
868	+	int i, hi; E e;
869	+	for (i = index, index = hi = fence; i < hi; i++) {
870	+	if ((e = (E) es[i]) == null)
871	+	break;      // must be CME
872	+	action.accept(e);
873	+	}
874	+	if (modCount != expectedModCount)
875	+	throw new ConcurrentModificationException();
876	+	}
877	+
878	+	public boolean tryAdvance(Consumer<? super E> action) {
879	+	if (action == null)
880	+	throw new NullPointerException();
881	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
882	+	int i;
883	+	if ((i = index) < fence) {
884	+	index = i + 1;
885	+	E e;
886	+	if ((e = (E) queue[i]) == null
887	+	|| modCount != expectedModCount)
888	+	throw new ConcurrentModificationException();
889	+	action.accept(e);
890	+	return true;
891	+	}
892	+	return false;
893	+	}
894	+
895	+	public long estimateSize() {
896	+	return getFence() - index;
897	+	}
898	+
899	+	public int characteristics() {
900	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
901	+	}
902	+	}
903	+
904	+	/**
905	+	* @throws NullPointerException {@inheritDoc}
906	+	*/
907	+	public boolean removeIf(Predicate<? super E> filter) {
908	+	Objects.requireNonNull(filter);
909	+	return bulkRemove(filter);
910	+	}
911	+
912	+	/**
913	+	* @throws NullPointerException {@inheritDoc}
914	+	*/
915	+	public boolean removeAll(Collection<?> c) {
916	+	Objects.requireNonNull(c);
917	+	return bulkRemove(e -> c.contains(e));
918	+	}
919	+
920	+	/**
921	+	* @throws NullPointerException {@inheritDoc}
922	+	*/
923	+	public boolean retainAll(Collection<?> c) {
924	+	Objects.requireNonNull(c);
925	+	return bulkRemove(e -> !c.contains(e));
926	+	}
927	+
928	+	// A tiny bit set implementation
929	+
930	+	private static long[] nBits(int n) {
931	+	return new long[((n - 1) >> 6) + 1];
932	+	}
933	+	private static void setBit(long[] bits, int i) {
934	+	bits[i >> 6] |= 1L << i;
935	+	}
936	+	private static boolean isClear(long[] bits, int i) {
937	+	return (bits[i >> 6] & (1L << i)) == 0;
938	+	}
939	+
940	+	/** Implementation of bulk remove methods. */
941	+	private boolean bulkRemove(Predicate<? super E> filter) {
942	+	final int expectedModCount = ++modCount;
943	+	final Object[] es = queue;
944	+	final int end = size;
945	+	int i;
946	+	// Optimize for initial run of survivors
947	+	for (i = 0; i < end && !filter.test((E) es[i]); i++)
948	+	;
949	+	if (i >= end) {
950	+	if (modCount != expectedModCount)
951	+	throw new ConcurrentModificationException();
952	+	return false;
953	+	}
954	+	// Tolerate predicates that reentrantly access the collection for
955	+	// read (but writers still get CME), so traverse once to find
956	+	// elements to delete, a second pass to physically expunge.
957	+	final int beg = i;
958	+	final long[] deathRow = nBits(end - beg);
959	+	deathRow[0] = 1L;   // set bit 0
960	+	for (i = beg + 1; i < end; i++)
961	+	if (filter.test((E) es[i]))
962	+	setBit(deathRow, i - beg);
963	+	if (modCount != expectedModCount)
964	+	throw new ConcurrentModificationException();
965	+	int w = beg;
966	+	for (i = beg; i < end; i++)
967	+	if (isClear(deathRow, i - beg))
968	+	es[w++] = es[i];
969	+	for (i = size = w; i < end; i++)
970	+	es[i] = null;
971	+	heapify();
972	+	return true;
973	+	}
974	+
975	+	/**
976	+	* @throws NullPointerException {@inheritDoc}
977	+	*/
978	+	public void forEach(Consumer<? super E> action) {
979	+	Objects.requireNonNull(action);
980	+	final int expectedModCount = modCount;
981	+	final Object[] es = queue;
982	+	for (int i = 0, n = size; i < n; i++)
983	+	action.accept((E) es[i]);
984	+	if (expectedModCount != modCount)
985	+	throw new ConcurrentModificationException();
986	+	}
987		}

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