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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.62 by jsr166, Thu Feb 16 08:17:21 2006 UTC vs.
Revision 1.117 by jsr166, Tue Dec 20 22:37:31 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 2006 Sun Microsystems, Inc. All rights reserved.
6	<	* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
5	>	* This code is free software; you can redistribute it and/or modify it
6	>	* under the terms of the GNU General Public License version 2 only, as
7	>	* published by the Free Software Foundation.  Oracle designates this
8	>	* particular file as subject to the "Classpath" exception as provided
9	>	* by Oracle in the LICENSE file that accompanied this code.
10	>	*
11	>	* This code is distributed in the hope that it will be useful, but WITHOUT
12	>	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13	>	* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14	>	* version 2 for more details (a copy is included in the LICENSE file that
15	>	* accompanied this code).
16	>	*
17	>	* You should have received a copy of the GNU General Public License version
18	>	* 2 along with this work; if not, write to the Free Software Foundation,
19	>	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20	>	*
21	>	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22	>	* or visit www.oracle.com if you need additional information or have any
23	>	* questions.
24		*/
25
26		package java.util;
27
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 34 | Line 54 | package java.util;
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()} is <em>not</em> guaranteed to traverse the elements of
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 <tt>Arrays.sort(pq.toArray())</tt>.
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 <tt>PriorityQueue</tt>
64	<	* instance concurrently if any of the threads modifies the list
65	<	* structurally. Instead, use the thread-safe {@link
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	<	* <p>Implementation note: this implementation provides O(log(n)) time
69	<	* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
70	<	* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
71	<	* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
72	<	* constant time for the retrieval methods (<tt>peek</tt>,
73	<	* <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
60	<	* @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 java.io.Serializable {
#	Line 74 | Line 95 | public class PriorityQueue<E> extends Ab
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 91 | 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
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		*/
#	Line 103 | Line 124 | public class PriorityQueue<E> extends Ab
124		}
125
126		/**
127	<	* Creates a <tt>PriorityQueue</tt> with the specified initial
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 <tt>initialCapacity</tt> is less
133	<	* than 1
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 that will be used to order
158	<	*         this priority queue.  If <tt>null</tt>, the <i>natural
159	<	*         ordering</i> of the elements will be used.
160	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is
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,
#	Line 137 | Line 171 | public class PriorityQueue<E> extends Ab
171		}
172
173		/**
174	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
175	<	* specified collection.   If the specified collection is an
176	<	* instance of a {@link java.util.SortedSet} or is another
177	<	* <tt>PriorityQueue</tt>, the priority queue will be ordered
178	<	* according to the same ordering.  Otherwise, this priority queue
179	<	* will be ordered according to the natural ordering of its elements.
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
#	Line 152 | Line 186 | public class PriorityQueue<E> extends Ab
186		* @throws NullPointerException if the specified collection or any
187		*         of its elements are null
188		*/
189	+	@SuppressWarnings("unchecked")
190		public PriorityQueue(Collection<? extends E> c) {
191	<	initFromCollection(c);
192	<	if (c instanceof SortedSet)
193	<	comparator = (Comparator<? super E>)
194	<	((SortedSet<? extends E>)c).comparator();
195	<	else if (c instanceof PriorityQueue)
196	<	comparator = (Comparator<? super E>)
197	<	((PriorityQueue<? extends E>)c).comparator();
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	<	comparator = null;
203	<	heapify();
202	>	this.comparator = null;
203	>	initFromCollection(c);
204		}
205		}
206
207		/**
208	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
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 <tt>c</tt> cannot be
216	<	*         compared to one another according to <tt>c</tt>'s
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	+	@SuppressWarnings("unchecked")
222		public PriorityQueue(PriorityQueue<? extends E> c) {
223	<	comparator = (Comparator<? super E>)c.comparator();
224	<	initFromCollection(c);
223	>	this.comparator = (Comparator<? super E>) c.comparator();
224	>	initFromPriorityQueue(c);
225		}
226
227		/**
228	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
229	<	* specified sorted set.  This priority queue will be ordered
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.
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	+	@SuppressWarnings("unchecked")
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	<	/**
247	<	* Initialize queue array with elements from the given Collection.
248	<	* @param c the collection
249	<	*/
250	<	private void initFromCollection(Collection<? extends E> c) {
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	>	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	<	queue = a;
261	<	size = a.length;
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	>	* Initializes queue array with elements from the given Collection.
271	>	*
272	>	* @param c the collection
273	>	*/
274	>	private void initFromCollection(Collection<? extends E> c) {
275	>	initElementsFromCollection(c);
276	>	heapify();
277		}
278
279		/**
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 minCapacity the desired minimum capacity
291		*/
292		private void grow(int minCapacity) {
293	<	if (minCapacity < 0) // overflow
226	<	throw new OutOfMemoryError();
227	<	int oldCapacity = queue.length;
293	>	int oldCapacity = queue.length;
294		// Double size if small; else grow by 50%
295	<	int newCapacity = ((oldCapacity < 64)?
296	<	((oldCapacity + 1) * 2):
297	<	((oldCapacity / 2) * 3));
298	<	if (newCapacity < 0) // overflow
299	<	newCapacity = Integer.MAX_VALUE;
300	<	if (newCapacity < minCapacity)
235	<	newCapacity = minCapacity;
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		* Inserts the specified element into this priority queue.
314		*
315	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
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
#	Line 252 | Line 325 | public class PriorityQueue<E> extends Ab
325		/**
326		* Inserts the specified element into this priority queue.
327		*
328	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
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
#	Line 265 | Line 338 | public class PriorityQueue<E> extends Ab
338		int i = size;
339		if (i >= queue.length)
340		grow(i + 1);
341	+	siftUp(i, e);
342		size = i + 1;
269	–	if (i == 0)
270	–	queue[0] = e;
271	–	else
272	–	siftUp(i, e);
343		return true;
344		}
345
346	+	@SuppressWarnings("unchecked")
347		public E peek() {
348	<	if (size == 0)
278	<	return null;
279	<	return (E) queue[0];
348	>	return (size == 0) ? null : (E) queue[0];
349		}
350
351		private int indexOf(Object o) {
352	<	if (o != null) {
352	>	if (o != null) {
353		for (int i = 0; i < size; i++)
354		if (o.equals(queue[i]))
355		return i;
#	Line 290 | Line 359 | public class PriorityQueue<E> extends Ab
359
360		/**
361		* Removes a single instance of the specified element from this queue,
362	<	* if it is present.  More formally, removes an element <tt>e</tt> such
363	<	* that <tt>o.equals(e)</tt>, if this queue contains one or more such
364	<	* elements.  Returns true if this queue contained the specified element
365	<	* (or equivalently, if this queue changed as a result of the call).
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		* @param o element to be removed from this queue, if present
369	<	* @return <tt>true</tt> if this queue changed as a result of the call
369	>	* @return {@code true} if this queue changed as a result of the call
370		*/
371		public boolean remove(Object o) {
372	<	int i = indexOf(o);
373	<	if (i == -1)
374	<	return false;
375	<	else {
376	<	removeAt(i);
377	<	return true;
378	<	}
372	>	int i = indexOf(o);
373	>	if (i == -1)
374	>	return false;
375	>	else {
376	>	removeAt(i);
377	>	return true;
378	>	}
379		}
380
381		/**
#	Line 313 | Line 383 | public class PriorityQueue<E> extends Ab
383		* Needed by iterator.remove.
384		*
385		* @param o element to be removed from this queue, if present
386	<	* @return <tt>true</tt> if removed
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]) {
389	>	for (int i = 0; i < size; i++) {
390	>	if (o == queue[i]) {
391		removeAt(i);
392		return true;
393		}
#	Line 326 | Line 396 | public class PriorityQueue<E> extends Ab
396		}
397
398		/**
399	<	* Returns <tt>true</tt> if this queue contains the specified element.
400	<	* More formally, returns <tt>true</tt> if and only if this queue contains
401	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
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 <tt>true</tt> if this queue contains the specified element
404	>	* @return {@code true} if this queue contains the specified element
405		*/
406		public boolean contains(Object o) {
407	<	return indexOf(o) != -1;
407	>	return indexOf(o) >= 0;
408		}
409
410		/**
411	<	* Returns an array containing all of the elements in this queue,
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 list.  (In other words, this method must allocate
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() {
#	Line 352 | Line 425 | public class PriorityQueue<E> extends Ab
425		}
426
427		/**
428	<	* Returns an array containing all of the elements in this queue.
429	<	* The elements are in no particular order.  The runtime type of
430	<	* the returned array is that of the specified array.  If the queue
431	<	* fits in the specified array, it is returned therein.
432	<	* Otherwise, a new array is allocated with the runtime type of
433	<	* the specified array and the size of this queue.
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	<	* <tt>null</tt>.  (This is useful in determining the length of the
439	<	* queue <i>only</i> if the caller knows that the queue does not contain
440	<	* any null elements.)
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 the elements of the queue
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);
469	>	System.arraycopy(queue, 0, a, 0, size);
470		if (a.length > size)
471		a[size] = null;
472		return a;
#	Line 400 | Line 487 | public class PriorityQueue<E> extends Ab
487		* Index (into queue array) of element to be returned by
488		* subsequent call to next.
489		*/
490	<	private int cursor = 0;
490	>	private int cursor;
491
492		/**
493		* Index of element returned by most recent call to next,
#	Line 418 | Line 505 | public class PriorityQueue<E> extends Ab
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 ArrayDeque<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 E lastRetElt = null;
516	>	private E lastRetElt;
517
518		/**
519		* The modCount value that the iterator believes that the backing
520	<	* List should have.  If this expectation is violated, the iterator
520	>	* Queue should have.  If this expectation is violated, the iterator
521		* has detected concurrent modification.
522		*/
523		private int expectedModCount = modCount;
524
525	+	Itr() {}                        // prevent access constructor creation
526	+
527		public boolean hasNext() {
528		return cursor < size ||
529		(forgetMeNot != null && !forgetMeNot.isEmpty());
530		}
531
532	+	@SuppressWarnings("unchecked")
533		public E next() {
534		if (expectedModCount != modCount)
535		throw new ConcurrentModificationException();
#	Line 457 | Line 547 | public class PriorityQueue<E> extends Ab
547		public void remove() {
548		if (expectedModCount != modCount)
549		throw new ConcurrentModificationException();
460	–	if (lastRet == -1 && lastRetElt == null)
461	–	throw new IllegalStateException();
550		if (lastRet != -1) {
551		E moved = PriorityQueue.this.removeAt(lastRet);
552		lastRet = -1;
#	Line 466 | Line 554 | public class PriorityQueue<E> extends Ab
554		cursor--;
555		else {
556		if (forgetMeNot == null)
557	<	forgetMeNot = new ArrayDeque<E>();
557	>	forgetMeNot = new ArrayDeque<>();
558		forgetMeNot.add(moved);
559		}
560	<	} else {
560	>	} else if (lastRetElt != null) {
561		PriorityQueue.this.removeEq(lastRetElt);
562		lastRetElt = null;
563	+	} else {
564	+	throw new IllegalStateException();
565		}
566		expectedModCount = modCount;
567		}
478	–
568		}
569
570		public int size() {
#	Line 493 | Line 582 | public class PriorityQueue<E> extends Ab
582		size = 0;
583		}
584
585	+	@SuppressWarnings("unchecked")
586		public E poll() {
587		if (size == 0)
588		return null;
589		int s = --size;
590		modCount++;
591	<	E result = (E)queue[0];
592	<	E x = (E)queue[s];
591	>	E result = (E) queue[0];
592	>	E x = (E) queue[s];
593		queue[s] = null;
594		if (s != 0)
595		siftDown(0, x);
#	Line 516 | Line 606 | public class PriorityQueue<E> extends Ab
606		* i.  Under these circumstances, this method returns the element
607		* that was previously at the end of the list and is now at some
608		* position before i. This fact is used by iterator.remove so as to
609	<	* avoid missing traverseing elements.
609	>	* avoid missing traversing elements.
610		*/
611	<	private E removeAt(int i) {
612	<	assert i >= 0 && i < size;
611	>	@SuppressWarnings("unchecked")
612	>	E removeAt(int i) {
613	>	// assert i >= 0 && i < size;
614		modCount++;
615		int s = --size;
616		if (s == i) // removed last element
#	Line 542 | Line 633 | public class PriorityQueue<E> extends Ab
633		* promoting x up the tree until it is greater than or equal to
634		* its parent, or is the root.
635		*
636	<	* To simplify and speed up coercions and comparisons. the
636	>	* To simplify and speed up coercions and comparisons, the
637		* Comparable and Comparator versions are separated into different
638		* methods that are otherwise identical. (Similarly for siftDown.)
639		*
#	Line 556 | Line 647 | public class PriorityQueue<E> extends Ab
647		siftUpComparable(k, x);
648		}
649
650	+	@SuppressWarnings("unchecked")
651		private void siftUpComparable(int k, E x) {
652		Comparable<? super E> key = (Comparable<? super E>) x;
653		while (k > 0) {
654		int parent = (k - 1) >>> 1;
655		Object e = queue[parent];
656	<	if (key.compareTo((E)e) >= 0)
656	>	if (key.compareTo((E) e) >= 0)
657		break;
658		queue[k] = e;
659		k = parent;
#	Line 569 | Line 661 | public class PriorityQueue<E> extends Ab
661		queue[k] = key;
662		}
663
664	+	@SuppressWarnings("unchecked")
665		private void siftUpUsingComparator(int k, E x) {
666		while (k > 0) {
667		int parent = (k - 1) >>> 1;
668		Object e = queue[parent];
669	<	if (comparator.compare(x, (E)e) >= 0)
669	>	if (comparator.compare(x, (E) e) >= 0)
670		break;
671		queue[k] = e;
672		k = parent;
#	Line 596 | Line 689 | public class PriorityQueue<E> extends Ab
689		siftDownComparable(k, x);
690		}
691
692	+	@SuppressWarnings("unchecked")
693		private void siftDownComparable(int k, E x) {
694		Comparable<? super E> key = (Comparable<? super E>)x;
695		int half = size >>> 1;        // loop while a non-leaf
#	Line 604 | Line 698 | public class PriorityQueue<E> extends Ab
698		Object c = queue[child];
699		int right = child + 1;
700		if (right < size &&
701	<	((Comparable<? super E>)c).compareTo((E)queue[right]) > 0)
701	>	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
702		c = queue[child = right];
703	<	if (key.compareTo((E)c) <= 0)
703	>	if (key.compareTo((E) c) <= 0)
704		break;
705		queue[k] = c;
706		k = child;
#	Line 614 | Line 708 | public class PriorityQueue<E> extends Ab
708		queue[k] = key;
709		}
710
711	+	@SuppressWarnings("unchecked")
712		private void siftDownUsingComparator(int k, E x) {
713		int half = size >>> 1;
714		while (k < half) {
#	Line 621 | Line 716 | public class PriorityQueue<E> extends Ab
716		Object c = queue[child];
717		int right = child + 1;
718		if (right < size &&
719	<	comparator.compare((E)c, (E)queue[right]) > 0)
719	>	comparator.compare((E) c, (E) queue[right]) > 0)
720		c = queue[child = right];
721	<	if (comparator.compare(x, (E)c) <= 0)
721	>	if (comparator.compare(x, (E) c) <= 0)
722		break;
723		queue[k] = c;
724		k = child;
#	Line 634 | Line 729 | public class PriorityQueue<E> extends Ab
729		/**
730		* Establishes the heap invariant (described above) in the entire tree,
731		* assuming nothing about the order of the elements prior to the call.
732	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
733		*/
734	+	@SuppressWarnings("unchecked")
735		private void heapify() {
736	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
737	<	siftDown(i, (E)queue[i]);
736	>	final Object[] es = queue;
737	>	final int half = (size >>> 1) - 1;
738	>	if (comparator == null)
739	>	for (int i = half; i >= 0; i--)
740	>	siftDownComparable(i, (E) es[i]);
741	>	else
742	>	for (int i = half; i >= 0; i--)
743	>	siftDownUsingComparator(i, (E) es[i]);
744		}
745
746		/**
747		* Returns the comparator used to order the elements in this
748	<	* queue, or <tt>null</tt> if this queue is sorted according to
748	>	* queue, or {@code null} if this queue is sorted according to
749		* the {@linkplain Comparable natural ordering} of its elements.
750		*
751		* @return the comparator used to order this queue, or
752	<	*         <tt>null</tt> if this queue is sorted according to the
753	<	*         natural ordering of its elements.
752	>	*         {@code null} if this queue is sorted according to the
753	>	*         natural ordering of its elements
754		*/
755		public Comparator<? super E> comparator() {
756		return comparator;
757		}
758
759		/**
760	<	* Save the state of the instance to a stream (that
658	<	* is, serialize it).
760	>	* Saves this queue to a stream (that is, serializes it).
761		*
660	–	* @serialData The length of the array backing the instance is
661	–	* emitted (int), followed by all of its elements (each an
662	–	* <tt>Object</tt>) in the proper order.
762		* @param s the stream
763	+	* @throws java.io.IOException if an I/O error occurs
764	+	* @serialData The length of the array backing the instance is
765	+	*             emitted (int), followed by all of its elements
766	+	*             (each an {@code Object}) in the proper order.
767		*/
768		private void writeObject(java.io.ObjectOutputStream s)
769	<	throws java.io.IOException{
769	>	throws java.io.IOException {
770		// Write out element count, and any hidden stuff
771		s.defaultWriteObject();
772
773	<	// Write out array length
774	<	// For compatibility with 1.5 version, must be at least 2.
672	<	s.writeInt(Math.max(2, queue.length));
773	>	// Write out array length, for compatibility with 1.5 version
774	>	s.writeInt(Math.max(2, size + 1));
775
776	<	// Write out all elements in the proper order.
777	<	for (int i=0; i<size; i++)
776	>	// Write out all elements in the "proper order".
777	>	for (int i = 0; i < size; i++)
778		s.writeObject(queue[i]);
779		}
780
781		/**
782	<	* Reconstitute the <tt>PriorityQueue</tt> instance from a stream
783	<	* (that is, deserialize it).
782	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
783	>	* (that is, deserializes it).
784	>	*
785		* @param s the stream
786	+	* @throws ClassNotFoundException if the class of a serialized object
787	+	*         could not be found
788	+	* @throws java.io.IOException if an I/O error occurs
789		*/
790		private void readObject(java.io.ObjectInputStream s)
791		throws java.io.IOException, ClassNotFoundException {
792		// Read in size, and any hidden stuff
793		s.defaultReadObject();
794
795	<	// Read in array length and allocate array
796	<	int arrayLength = s.readInt();
797	<	queue = new Object[arrayLength];
798	<
799	<	// Read in all elements in the proper order.
800	<	for (int i=0; i<size; i++)
801	<	queue[i] = (E) s.readObject();
795	>	// Read in (and discard) array length
796	>	s.readInt();
797	>
798	>	queue = new Object[size];
799	>
800	>	// Read in all elements.
801	>	for (int i = 0; i < size; i++)
802	>	queue[i] = s.readObject();
803	>
804	>	// Elements are guaranteed to be in "proper order", but the
805	>	// spec has never explained what that might be.
806	>	heapify();
807		}
808
809	+	/**
810	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
811	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
812	+	* queue. The spliterator does not traverse elements in any particular order
813	+	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
814	+	*
815	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
816	+	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
817	+	* Overriding implementations should document the reporting of additional
818	+	* characteristic values.
819	+	*
820	+	* @return a {@code Spliterator} over the elements in this queue
821	+	* @since 1.8
822	+	*/
823	+	public final Spliterator<E> spliterator() {
824	+	return new PriorityQueueSpliterator(0, -1, 0);
825	+	}
826	+
827	+	final class PriorityQueueSpliterator implements Spliterator<E> {
828	+	private int index;            // current index, modified on advance/split
829	+	private int fence;            // -1 until first use
830	+	private int expectedModCount; // initialized when fence set
831	+
832	+	/** Creates new spliterator covering the given range. */
833	+	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
834	+	this.index = origin;
835	+	this.fence = fence;
836	+	this.expectedModCount = expectedModCount;
837	+	}
838	+
839	+	private int getFence() { // initialize fence to size on first use
840	+	int hi;
841	+	if ((hi = fence) < 0) {
842	+	expectedModCount = modCount;
843	+	hi = fence = size;
844	+	}
845	+	return hi;
846	+	}
847	+
848	+	public PriorityQueueSpliterator trySplit() {
849	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
850	+	return (lo >= mid) ? null :
851	+	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
852	+	}
853	+
854	+	@SuppressWarnings("unchecked")
855	+	public void forEachRemaining(Consumer<? super E> action) {
856	+	if (action == null)
857	+	throw new NullPointerException();
858	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
859	+	final Object[] a = queue;
860	+	int i, hi; E e;
861	+	for (i = index, index = hi = fence; i < hi; i++) {
862	+	if ((e = (E) a[i]) == null)
863	+	break;      // must be CME
864	+	action.accept(e);
865	+	}
866	+	if (modCount != expectedModCount)
867	+	throw new ConcurrentModificationException();
868	+	}
869	+
870	+	@SuppressWarnings("unchecked")
871	+	public boolean tryAdvance(Consumer<? super E> action) {
872	+	if (action == null)
873	+	throw new NullPointerException();
874	+	if (fence < 0) { fence = size; expectedModCount = modCount; }
875	+	int i;
876	+	if ((i = index) < fence) {
877	+	index = i + 1;
878	+	E e;
879	+	if ((e = (E) queue[i]) == null
880	+	|| modCount != expectedModCount)
881	+	throw new ConcurrentModificationException();
882	+	action.accept(e);
883	+	return true;
884	+	}
885	+	return false;
886	+	}
887	+
888	+	public long estimateSize() {
889	+	return getFence() - index;
890	+	}
891	+
892	+	public int characteristics() {
893	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
894	+	}
895	+	}
896		}

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