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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.65 by jsr166, Sun May 28 23:36:29 2006 UTC vs.
Revision 1.132 by jsr166, Fri Aug 30 18:05:39 2019 UTC

#	Line 1 | Line 1
1		/*
2	<	* %W% %E%
2	>	* Copyright (c) 2003, 2019, 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	+	import java.util.function.Predicate;
30	+	// OPENJDK import jdk.internal.access.SharedSecrets;
31	+	import jdk.internal.util.ArraysSupport;
32	+
33		/**
34		* An unbounded priority {@linkplain Queue queue} based on a priority heap.
35		* The elements of the priority queue are ordered according to their
#	Line 34 | Line 57 | package java.util;
57		* <p>This class and its iterator implement all of the
58		* <em>optional</em> methods of the {@link Collection} and {@link
59		* Iterator} interfaces.  The Iterator provided in method {@link
60	<	* #iterator()} is <em>not</em> guaranteed to traverse the elements of
60	>	* #iterator()} and the Spliterator provided in method {@link #spliterator()}
61	>	* are <em>not</em> guaranteed to traverse the elements of
62		* the priority queue in any particular order. If you need ordered
63		* traversal, consider using {@code Arrays.sort(pq.toArray())}.
64		*
65	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
65	>	* <p><strong>Note that this implementation is not synchronized.</strong>
66		* Multiple threads should not access a {@code PriorityQueue}
67		* instance concurrently if any of the threads modifies the queue.
68		* Instead, use the thread-safe {@link
69		* java.util.concurrent.PriorityBlockingQueue} class.
70		*
71		* <p>Implementation note: this implementation provides
72	<	* O(log(n)) time for the enqueing and dequeing methods
72	>	* O(log(n)) time for the enqueuing and dequeuing methods
73		* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
74		* linear time for the {@code remove(Object)} and {@code contains(Object)}
75		* methods; and constant time for the retrieval methods
76		* ({@code peek}, {@code element}, and {@code size}).
77		*
78		* <p>This class is a member of the
79	<	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
79	>	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
80		* Java Collections Framework</a>.
81		*
82		* @since 1.5
59	–	* @version %I%, %G%
83		* @author Josh Bloch, Doug Lea
84	<	* @param <E> the type of elements held in this collection
84	>	* @param <E> the type of elements held in this queue
85		*/
86	+	@SuppressWarnings("unchecked")
87		public class PriorityQueue<E> extends AbstractQueue<E>
88		implements java.io.Serializable {
89
90	+	// OPENJDK @java.io.Serial
91		private static final long serialVersionUID = -7720805057305804111L;
92
93		private static final int DEFAULT_INITIAL_CAPACITY = 11;
#	Line 75 | Line 100 | public class PriorityQueue<E> extends Ab
100		* heap and each descendant d of n, n <= d.  The element with the
101		* lowest value is in queue[0], assuming the queue is nonempty.
102		*/
103	<	private transient Object[] queue;
103	>	transient Object[] queue; // non-private to simplify nested class access
104
105		/**
106		* The number of elements in the priority queue.
107		*/
108	<	private int size = 0;
108	>	int size;
109
110		/**
111		* The comparator, or null if priority queue uses elements'
#	Line 92 | Line 117 | public class PriorityQueue<E> extends Ab
117		* The number of times this priority queue has been
118		* <i>structurally modified</i>.  See AbstractList for gory details.
119		*/
120	<	private transient int modCount = 0;
120	>	transient int modCount;     // non-private to simplify nested class access
121
122		/**
123		* Creates a {@code PriorityQueue} with the default initial
#	Line 117 | Line 142 | public class PriorityQueue<E> extends Ab
142		}
143
144		/**
145	+	* Creates a {@code PriorityQueue} with the default initial capacity and
146	+	* whose elements are ordered according to the specified comparator.
147	+	*
148	+	* @param  comparator the comparator that will be used to order this
149	+	*         priority queue.  If {@code null}, the {@linkplain Comparable
150	+	*         natural ordering} of the elements will be used.
151	+	* @since 1.8
152	+	*/
153	+	public PriorityQueue(Comparator<? super E> comparator) {
154	+	this(DEFAULT_INITIAL_CAPACITY, comparator);
155	+	}
156	+
157	+	/**
158		* Creates a {@code PriorityQueue} with the specified initial capacity
159		* that orders its elements according to the specified comparator.
160		*
#	Line 154 | Line 192 | public class PriorityQueue<E> extends Ab
192		*         of its elements are null
193		*/
194		public PriorityQueue(Collection<? extends E> c) {
195	<	initFromCollection(c);
196	<	if (c instanceof SortedSet)
197	<	comparator = (Comparator<? super E>)
198	<	((SortedSet<? extends E>)c).comparator();
199	<	else if (c instanceof PriorityQueue)
200	<	comparator = (Comparator<? super E>)
201	<	((PriorityQueue<? extends E>)c).comparator();
195	>	if (c instanceof SortedSet<?>) {
196	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
197	>	this.comparator = (Comparator<? super E>) ss.comparator();
198	>	initElementsFromCollection(ss);
199	>	}
200	>	else if (c instanceof PriorityQueue<?>) {
201	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
202	>	this.comparator = (Comparator<? super E>) pq.comparator();
203	>	initFromPriorityQueue(pq);
204	>	}
205		else {
206	<	comparator = null;
207	<	heapify();
206	>	this.comparator = null;
207	>	initFromCollection(c);
208		}
209		}
210
#	Line 182 | Line 223 | public class PriorityQueue<E> extends Ab
223		*         of its elements are null
224		*/
225		public PriorityQueue(PriorityQueue<? extends E> c) {
226	<	comparator = (Comparator<? super E>)c.comparator();
227	<	initFromCollection(c);
226	>	this.comparator = (Comparator<? super E>) c.comparator();
227	>	initFromPriorityQueue(c);
228		}
229
230		/**
#	Line 200 | Line 241 | public class PriorityQueue<E> extends Ab
241		*         of its elements are null
242		*/
243		public PriorityQueue(SortedSet<? extends E> c) {
244	<	comparator = (Comparator<? super E>)c.comparator();
245	<	initFromCollection(c);
244	>	this.comparator = (Comparator<? super E>) c.comparator();
245	>	initElementsFromCollection(c);
246	>	}
247	>
248	>	/** Ensures that queue[0] exists, helping peek() and poll(). */
249	>	private static Object[] ensureNonEmpty(Object[] es) {
250	>	return (es.length > 0) ? es : new Object[1];
251	>	}
252	>
253	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
254	>	if (c.getClass() == PriorityQueue.class) {
255	>	this.queue = ensureNonEmpty(c.toArray());
256	>	this.size = c.size();
257	>	} else {
258	>	initFromCollection(c);
259	>	}
260	>	}
261	>
262	>	private void initElementsFromCollection(Collection<? extends E> c) {
263	>	Object[] es = c.toArray();
264	>	int len = es.length;
265	>	// If c.toArray incorrectly doesn't return Object[], copy it.
266	>	if (es.getClass() != Object[].class)
267	>	es = Arrays.copyOf(es, len, Object[].class);
268	>	if (len == 1 || this.comparator != null)
269	>	for (Object e : es)
270	>	if (e == null)
271	>	throw new NullPointerException();
272	>	this.queue = ensureNonEmpty(es);
273	>	this.size = len;
274		}
275
276		/**
#	Line 210 | Line 279 | public class PriorityQueue<E> extends Ab
279		* @param c the collection
280		*/
281		private void initFromCollection(Collection<? extends E> c) {
282	<	Object[] a = c.toArray();
283	<	// If c.toArray incorrectly doesn't return Object[], copy it.
215	<	if (a.getClass() != Object[].class)
216	<	a = Arrays.copyOf(a, a.length, Object[].class);
217	<	queue = a;
218	<	size = a.length;
282	>	initElementsFromCollection(c);
283	>	heapify();
284		}
285
286		/**
#	Line 224 | Line 289 | public class PriorityQueue<E> extends Ab
289		* @param minCapacity the desired minimum capacity
290		*/
291		private void grow(int minCapacity) {
292	<	if (minCapacity < 0) // overflow
228	<	throw new OutOfMemoryError();
229	<	int oldCapacity = queue.length;
292	>	int oldCapacity = queue.length;
293		// Double size if small; else grow by 50%
294	<	int newCapacity = ((oldCapacity < 64)?
295	<	((oldCapacity + 1) * 2):
296	<	((oldCapacity / 2) * 3));
297	<	if (newCapacity < 0) // overflow
235	<	newCapacity = Integer.MAX_VALUE;
236	<	if (newCapacity < minCapacity)
237	<	newCapacity = minCapacity;
294	>	int newCapacity = ArraysSupport.newLength(oldCapacity,
295	>	minCapacity - oldCapacity, /* minimum growth */
296	>	oldCapacity < 64 ? oldCapacity + 2 : oldCapacity >> 1
297	>	/* preferred growth */);
298		queue = Arrays.copyOf(queue, newCapacity);
299		}
300
#	Line 267 | Line 327 | public class PriorityQueue<E> extends Ab
327		int i = size;
328		if (i >= queue.length)
329		grow(i + 1);
330	+	siftUp(i, e);
331		size = i + 1;
271	–	if (i == 0)
272	–	queue[0] = e;
273	–	else
274	–	siftUp(i, e);
332		return true;
333		}
334
335		public E peek() {
279	–	if (size == 0)
280	–	return null;
336		return (E) queue[0];
337		}
338
339		private int indexOf(Object o) {
340	<	if (o != null) {
341	<	for (int i = 0; i < size; i++)
342	<	if (o.equals(queue[i]))
340	>	if (o != null) {
341	>	final Object[] es = queue;
342	>	for (int i = 0, n = size; i < n; i++)
343	>	if (o.equals(es[i]))
344		return i;
345		}
346		return -1;
#	Line 302 | Line 358 | public class PriorityQueue<E> extends Ab
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.
316	<	* Needed by iterator.remove.
371	>	* Identity-based version for use in Itr.remove.
372		*
373		* @param o element to be removed from this queue, if present
319	–	* @return {@code true} if removed
374		*/
375	<	boolean removeEq(Object o) {
376	<	for (int i = 0; i < size; i++) {
377	<	if (o == queue[i]) {
375	>	void removeEq(Object o) {
376	>	final Object[] es = queue;
377	>	for (int i = 0, n = size; i < n; i++) {
378	>	if (o == es[i]) {
379		removeAt(i);
380	<	return true;
380	>	break;
381		}
382		}
328	–	return false;
383		}
384
385		/**
#	Line 337 | Line 391 | public class PriorityQueue<E> extends Ab
391		* @return {@code true} if this queue contains the specified element
392		*/
393		public boolean contains(Object o) {
394	<	return indexOf(o) != -1;
394	>	return indexOf(o) >= 0;
395		}
396
397		/**
#	Line 375 | Line 429 | public class PriorityQueue<E> extends Ab
429		* precise control over the runtime type of the output array, and may,
430		* under certain circumstances, be used to save allocation costs.
431		*
432	<	* <p>Suppose <tt>x</tt> is a queue known to contain only strings.
432	>	* <p>Suppose {@code x} is a queue known to contain only strings.
433		* The following code can be used to dump the queue into a newly
434	<	* allocated array of <tt>String</tt>:
434	>	* allocated array of {@code String}:
435		*
436	<	* <pre>
383	<	*     String[] y = x.toArray(new String[0]);</pre>
436	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
437		*
438	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
439	<	* <tt>toArray()</tt>.
438	>	* Note that {@code toArray(new Object[0])} is identical in function to
439	>	* {@code toArray()}.
440		*
441		* @param a the array into which the elements of the queue are to
442		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 395 | Line 448 | public class PriorityQueue<E> extends Ab
448		* @throws NullPointerException if the specified array is null
449		*/
450		public <T> T[] toArray(T[] a) {
451	+	final int size = this.size;
452		if (a.length < size)
453		// Make a new array of a's runtime type, but my contents:
454		return (T[]) Arrays.copyOf(queue, size, a.getClass());
455	<	System.arraycopy(queue, 0, a, 0, size);
455	>	System.arraycopy(queue, 0, a, 0, size);
456		if (a.length > size)
457		a[size] = null;
458		return a;
#	Line 419 | Line 473 | public class PriorityQueue<E> extends Ab
473		* Index (into queue array) of element to be returned by
474		* subsequent call to next.
475		*/
476	<	private int cursor = 0;
476	>	private int cursor;
477
478		/**
479		* Index of element returned by most recent call to next,
#	Line 439 | Line 493 | public class PriorityQueue<E> extends Ab
493		* We expect that most iterations, even those involving removals,
494		* will not need to store elements in this field.
495		*/
496	<	private ArrayDeque<E> forgetMeNot = null;
496	>	private ArrayDeque<E> forgetMeNot;
497
498		/**
499		* Element returned by the most recent call to next iff that
500		* element was drawn from the forgetMeNot list.
501		*/
502	<	private E lastRetElt = null;
502	>	private E lastRetElt;
503
504		/**
505		* The modCount value that the iterator believes that the backing
#	Line 454 | Line 508 | public class PriorityQueue<E> extends Ab
508		*/
509		private int expectedModCount = modCount;
510
511	+	Itr() {}                        // prevent access constructor creation
512	+
513		public boolean hasNext() {
514		return cursor < size ||
515		(forgetMeNot != null && !forgetMeNot.isEmpty());
#	Line 483 | Line 539 | public class PriorityQueue<E> extends Ab
539		cursor--;
540		else {
541		if (forgetMeNot == null)
542	<	forgetMeNot = new ArrayDeque<E>();
542	>	forgetMeNot = new ArrayDeque<>();
543		forgetMeNot.add(moved);
544		}
545		} else if (lastRetElt != null) {
#	Line 491 | Line 547 | public class PriorityQueue<E> extends Ab
547		lastRetElt = null;
548		} else {
549		throw new IllegalStateException();
550	<	}
550	>	}
551		expectedModCount = modCount;
552		}
553		}
#	Line 506 | Line 562 | public class PriorityQueue<E> extends Ab
562		*/
563		public void clear() {
564		modCount++;
565	<	for (int i = 0; i < size; i++)
566	<	queue[i] = null;
565	>	final Object[] es = queue;
566	>	for (int i = 0, n = size; i < n; i++)
567	>	es[i] = null;
568		size = 0;
569		}
570
571		public E poll() {
572	<	if (size == 0)
573	<	return null;
574	<	int s = --size;
575	<	modCount++;
576	<	E result = (E) queue[0];
577	<	E x = (E) queue[s];
578	<	queue[s] = null;
579	<	if (s != 0)
580	<	siftDown(0, x);
572	>	final Object[] es;
573	>	final E result;
574	>
575	>	if ((result = (E) ((es = queue)[0])) != null) {
576	>	modCount++;
577	>	final int n;
578	>	final E x = (E) es[(n = --size)];
579	>	es[n] = null;
580	>	if (n > 0) {
581	>	final Comparator<? super E> cmp;
582	>	if ((cmp = comparator) == null)
583	>	siftDownComparable(0, x, es, n);
584	>	else
585	>	siftDownUsingComparator(0, x, es, n, cmp);
586	>	}
587	>	}
588		return result;
589		}
590
#	Line 536 | Line 600 | public class PriorityQueue<E> extends Ab
600		* position before i. This fact is used by iterator.remove so as to
601		* avoid missing traversing elements.
602		*/
603	<	private E removeAt(int i) {
604	<	assert i >= 0 && i < size;
603	>	E removeAt(int i) {
604	>	// assert i >= 0 && i < size;
605	>	final Object[] es = queue;
606		modCount++;
607		int s = --size;
608		if (s == i) // removed last element
609	<	queue[i] = null;
609	>	es[i] = null;
610		else {
611	<	E moved = (E) queue[s];
612	<	queue[s] = null;
611	>	E moved = (E) es[s];
612	>	es[s] = null;
613		siftDown(i, moved);
614	<	if (queue[i] == moved) {
614	>	if (es[i] == moved) {
615		siftUp(i, moved);
616	<	if (queue[i] != moved)
616	>	if (es[i] != moved)
617		return moved;
618		}
619		}
#	Line 560 | Line 625 | public class PriorityQueue<E> extends Ab
625		* promoting x up the tree until it is greater than or equal to
626		* its parent, or is the root.
627		*
628	<	* To simplify and speed up coercions and comparisons. the
628	>	* To simplify and speed up coercions and comparisons, the
629		* Comparable and Comparator versions are separated into different
630		* methods that are otherwise identical. (Similarly for siftDown.)
631		*
#	Line 569 | Line 634 | public class PriorityQueue<E> extends Ab
634		*/
635		private void siftUp(int k, E x) {
636		if (comparator != null)
637	<	siftUpUsingComparator(k, x);
637	>	siftUpUsingComparator(k, x, queue, comparator);
638		else
639	<	siftUpComparable(k, x);
639	>	siftUpComparable(k, x, queue);
640		}
641
642	<	private void siftUpComparable(int k, E x) {
643	<	Comparable<? super E> key = (Comparable<? super E>) x;
642	>	private static <T> void siftUpComparable(int k, T x, Object[] es) {
643	>	Comparable<? super T> key = (Comparable<? super T>) x;
644		while (k > 0) {
645		int parent = (k - 1) >>> 1;
646	<	Object e = queue[parent];
647	<	if (key.compareTo((E) e) >= 0)
646	>	Object e = es[parent];
647	>	if (key.compareTo((T) e) >= 0)
648		break;
649	<	queue[k] = e;
649	>	es[k] = e;
650		k = parent;
651		}
652	<	queue[k] = key;
652	>	es[k] = key;
653		}
654
655	<	private void siftUpUsingComparator(int k, E x) {
655	>	private static <T> void siftUpUsingComparator(
656	>	int k, T x, Object[] es, Comparator<? super T> cmp) {
657		while (k > 0) {
658		int parent = (k - 1) >>> 1;
659	<	Object e = queue[parent];
660	<	if (comparator.compare(x, (E) e) >= 0)
659	>	Object e = es[parent];
660	>	if (cmp.compare(x, (T) e) >= 0)
661		break;
662	<	queue[k] = e;
662	>	es[k] = e;
663		k = parent;
664		}
665	<	queue[k] = x;
665	>	es[k] = x;
666		}
667
668		/**
#	Line 609 | Line 675 | public class PriorityQueue<E> extends Ab
675		*/
676		private void siftDown(int k, E x) {
677		if (comparator != null)
678	<	siftDownUsingComparator(k, x);
678	>	siftDownUsingComparator(k, x, queue, size, comparator);
679		else
680	<	siftDownComparable(k, x);
680	>	siftDownComparable(k, x, queue, size);
681		}
682
683	<	private void siftDownComparable(int k, E x) {
684	<	Comparable<? super E> key = (Comparable<? super E>)x;
685	<	int half = size >>> 1;        // loop while a non-leaf
683	>	private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
684	>	// assert n > 0;
685	>	Comparable<? super T> key = (Comparable<? super T>)x;
686	>	int half = n >>> 1;           // loop while a non-leaf
687		while (k < half) {
688		int child = (k << 1) + 1; // assume left child is least
689	<	Object c = queue[child];
689	>	Object c = es[child];
690		int right = child + 1;
691	<	if (right < size &&
692	<	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
693	<	c = queue[child = right];
694	<	if (key.compareTo((E) c) <= 0)
691	>	if (right < n &&
692	>	((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
693	>	c = es[child = right];
694	>	if (key.compareTo((T) c) <= 0)
695		break;
696	<	queue[k] = c;
696	>	es[k] = c;
697		k = child;
698		}
699	<	queue[k] = key;
699	>	es[k] = key;
700		}
701
702	<	private void siftDownUsingComparator(int k, E x) {
703	<	int half = size >>> 1;
702	>	private static <T> void siftDownUsingComparator(
703	>	int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
704	>	// assert n > 0;
705	>	int half = n >>> 1;
706		while (k < half) {
707		int child = (k << 1) + 1;
708	<	Object c = queue[child];
708	>	Object c = es[child];
709		int right = child + 1;
710	<	if (right < size &&
711	<	comparator.compare((E) c, (E) queue[right]) > 0)
712	<	c = queue[child = right];
644	<	if (comparator.compare(x, (E) c) <= 0)
710	>	if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
711	>	c = es[child = right];
712	>	if (cmp.compare(x, (T) c) <= 0)
713		break;
714	<	queue[k] = c;
714	>	es[k] = c;
715		k = child;
716		}
717	<	queue[k] = x;
717	>	es[k] = x;
718		}
719
720		/**
721		* Establishes the heap invariant (described above) in the entire tree,
722		* assuming nothing about the order of the elements prior to the call.
723	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
724		*/
725		private void heapify() {
726	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
727	<	siftDown(i, (E) queue[i]);
726	>	final Object[] es = queue;
727	>	int n = size, i = (n >>> 1) - 1;
728	>	final Comparator<? super E> cmp;
729	>	if ((cmp = comparator) == null)
730	>	for (; i >= 0; i--)
731	>	siftDownComparable(i, (E) es[i], es, n);
732	>	else
733	>	for (; i >= 0; i--)
734	>	siftDownUsingComparator(i, (E) es[i], es, n, cmp);
735		}
736
737		/**
#	Line 672 | Line 748 | public class PriorityQueue<E> extends Ab
748		}
749
750		/**
751	<	* Saves the state of the instance to a stream (that
676	<	* is, serializes it).
751	>	* Saves this queue to a stream (that is, serializes it).
752		*
753	+	* @param s the stream
754	+	* @throws java.io.IOException if an I/O error occurs
755		* @serialData The length of the array backing the instance is
756		*             emitted (int), followed by all of its elements
757		*             (each an {@code Object}) in the proper order.
681	–	* @param s the stream
758		*/
759	+	// OPENJDK @java.io.Serial
760		private void writeObject(java.io.ObjectOutputStream s)
761	<	throws java.io.IOException{
761	>	throws java.io.IOException {
762		// Write out element count, and any hidden stuff
763		s.defaultWriteObject();
764
#	Line 689 | Line 766 | public class PriorityQueue<E> extends Ab
766		s.writeInt(Math.max(2, size + 1));
767
768		// Write out all elements in the "proper order".
769	<	for (int i = 0; i < size; i++)
770	<	s.writeObject(queue[i]);
769	>	final Object[] es = queue;
770	>	for (int i = 0, n = size; i < n; i++)
771	>	s.writeObject(es[i]);
772		}
773
774		/**
#	Line 698 | Line 776 | public class PriorityQueue<E> extends Ab
776		* (that is, deserializes it).
777		*
778		* @param s the stream
779	+	* @throws ClassNotFoundException if the class of a serialized object
780	+	*         could not be found
781	+	* @throws java.io.IOException if an I/O error occurs
782		*/
783	+	// OPENJDK @java.io.Serial
784		private void readObject(java.io.ObjectInputStream s)
785		throws java.io.IOException, ClassNotFoundException {
786		// Read in size, and any hidden stuff
#	Line 707 | Line 789 | public class PriorityQueue<E> extends Ab
789		// Read in (and discard) array length
790		s.readInt();
791
792	<	queue = new Object[size];
792	>	jsr166.Platform.checkArray(s, Object[].class, size);
793	>	final Object[] es = queue = new Object[Math.max(size, 1)];
794
795		// Read in all elements.
796	<	for (int i = 0; i < size; i++)
797	<	queue[i] = s.readObject();
796	>	for (int i = 0, n = size; i < n; i++)
797	>	es[i] = s.readObject();
798	>
799	>	// Elements are guaranteed to be in "proper order", but the
800	>	// spec has never explained what that might be.
801	>	heapify();
802	>	}
803	>
804	>	/**
805	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
806	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
807	>	* queue. The spliterator does not traverse elements in any particular order
808	>	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
809	>	*
810	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
811	>	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
812	>	* Overriding implementations should document the reporting of additional
813	>	* characteristic values.
814	>	*
815	>	* @return a {@code Spliterator} over the elements in this queue
816	>	* @since 1.8
817	>	*/
818	>	public final Spliterator<E> spliterator() {
819	>	return new PriorityQueueSpliterator(0, -1, 0);
820	>	}
821	>
822	>	final class PriorityQueueSpliterator implements Spliterator<E> {
823	>	private int index;            // current index, modified on advance/split
824	>	private int fence;            // -1 until first use
825	>	private int expectedModCount; // initialized when fence set
826	>
827	>	/** Creates new spliterator covering the given range. */
828	>	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
829	>	this.index = origin;
830	>	this.fence = fence;
831	>	this.expectedModCount = expectedModCount;
832	>	}
833	>
834	>	private int getFence() { // initialize fence to size on first use
835	>	int hi;
836	>	if ((hi = fence) < 0) {
837	>	expectedModCount = modCount;
838	>	hi = fence = size;
839	>	}
840	>	return hi;
841	>	}
842	>
843	>	public PriorityQueueSpliterator trySplit() {
844	>	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
845	>	return (lo >= mid) ? null :
846	>	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
847	>	}
848	>
849	>	public void forEachRemaining(Consumer<? super E> action) {
850	>	if (action == null)
851	>	throw new NullPointerException();
852	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
853	>	final Object[] es = queue;
854	>	int i, hi; E e;
855	>	for (i = index, index = hi = fence; i < hi; i++) {
856	>	if ((e = (E) es[i]) == null)
857	>	break;      // must be CME
858	>	action.accept(e);
859	>	}
860	>	if (modCount != expectedModCount)
861	>	throw new ConcurrentModificationException();
862	>	}
863	>
864	>	public boolean tryAdvance(Consumer<? super E> action) {
865	>	if (action == null)
866	>	throw new NullPointerException();
867	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
868	>	int i;
869	>	if ((i = index) < fence) {
870	>	index = i + 1;
871	>	E e;
872	>	if ((e = (E) queue[i]) == null
873	>	|| modCount != expectedModCount)
874	>	throw new ConcurrentModificationException();
875	>	action.accept(e);
876	>	return true;
877	>	}
878	>	return false;
879	>	}
880	>
881	>	public long estimateSize() {
882	>	return getFence() - index;
883	>	}
884	>
885	>	public int characteristics() {
886	>	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
887	>	}
888	>	}
889	>
890	>	/**
891	>	* @throws NullPointerException {@inheritDoc}
892	>	*/
893	>	public boolean removeIf(Predicate<? super E> filter) {
894	>	Objects.requireNonNull(filter);
895	>	return bulkRemove(filter);
896	>	}
897	>
898	>	/**
899	>	* @throws NullPointerException {@inheritDoc}
900	>	*/
901	>	public boolean removeAll(Collection<?> c) {
902	>	Objects.requireNonNull(c);
903	>	return bulkRemove(e -> c.contains(e));
904	>	}
905	>
906	>	/**
907	>	* @throws NullPointerException {@inheritDoc}
908	>	*/
909	>	public boolean retainAll(Collection<?> c) {
910	>	Objects.requireNonNull(c);
911	>	return bulkRemove(e -> !c.contains(e));
912	>	}
913	>
914	>	// A tiny bit set implementation
915
916	<	// Elements are guaranteed to be in "proper order", but the
917	<	// spec has never explained what that might be.
918	<	heapify();
916	>	private static long[] nBits(int n) {
917	>	return new long[((n - 1) >> 6) + 1];
918	>	}
919	>	private static void setBit(long[] bits, int i) {
920	>	bits[i >> 6] |= 1L << i;
921	>	}
922	>	private static boolean isClear(long[] bits, int i) {
923	>	return (bits[i >> 6] & (1L << i)) == 0;
924	>	}
925	>
926	>	/** Implementation of bulk remove methods. */
927	>	private boolean bulkRemove(Predicate<? super E> filter) {
928	>	final int expectedModCount = ++modCount;
929	>	final Object[] es = queue;
930	>	final int end = size;
931	>	int i;
932	>	// Optimize for initial run of survivors
933	>	for (i = 0; i < end && !filter.test((E) es[i]); i++)
934	>	;
935	>	if (i >= end) {
936	>	if (modCount != expectedModCount)
937	>	throw new ConcurrentModificationException();
938	>	return false;
939	>	}
940	>	// Tolerate predicates that reentrantly access the collection for
941	>	// read (but writers still get CME), so traverse once to find
942	>	// elements to delete, a second pass to physically expunge.
943	>	final int beg = i;
944	>	final long[] deathRow = nBits(end - beg);
945	>	deathRow[0] = 1L;   // set bit 0
946	>	for (i = beg + 1; i < end; i++)
947	>	if (filter.test((E) es[i]))
948	>	setBit(deathRow, i - beg);
949	>	if (modCount != expectedModCount)
950	>	throw new ConcurrentModificationException();
951	>	int w = beg;
952	>	for (i = beg; i < end; i++)
953	>	if (isClear(deathRow, i - beg))
954	>	es[w++] = es[i];
955	>	for (i = size = w; i < end; i++)
956	>	es[i] = null;
957	>	heapify();
958	>	return true;
959	>	}
960	>
961	>	/**
962	>	* @throws NullPointerException {@inheritDoc}
963	>	*/
964	>	public void forEach(Consumer<? super E> action) {
965	>	Objects.requireNonNull(action);
966	>	final int expectedModCount = modCount;
967	>	final Object[] es = queue;
968	>	for (int i = 0, n = size; i < n; i++)
969	>	action.accept((E) es[i]);
970	>	if (expectedModCount != modCount)
971	>	throw new ConcurrentModificationException();
972		}
973		}

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