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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.88 by dl, Fri Feb 1 16:23:04 2013 UTC vs.
Revision 1.133 by jsr166, Thu Oct 10 16:53:08 2019 UTC

#	Line 1 | Line 1
1		/*
2	<	* Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
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		* This code is free software; you can redistribute it and/or modify it
#	Line 24 | Line 24
24		*/
25
26		package java.util;
27	<	import java.util.stream.Stream;
28	<	import java.util.Spliterator;
29	<	import java.util.stream.Streams;
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.
#	Line 56 | Line 57 | import java.util.function.Consumer;
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		*
#	Line 67 | Line 69 | import java.util.function.Consumer;
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
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 101 | Line 105 | public class PriorityQueue<E> extends Ab
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'
112		* natural ordering.
113		*/
114	+	@SuppressWarnings("serial") // Conditionally serializable
115		private final Comparator<? super E> comparator;
116
117		/**
118		* The number of times this priority queue has been
119		* <i>structurally modified</i>.  See AbstractList for gory details.
120		*/
121	<	transient int modCount = 0; // non-private to simplify nested class access
121	>	transient int modCount;     // non-private to simplify nested class access
122
123		/**
124		* Creates a {@code PriorityQueue} with the default initial
#	Line 138 | Line 143 | public class PriorityQueue<E> extends Ab
143		}
144
145		/**
146	+	* Creates a {@code PriorityQueue} with the default initial capacity and
147	+	* whose elements are ordered according to the specified comparator.
148	+	*
149	+	* @param  comparator the comparator that will be used to order this
150	+	*         priority queue.  If {@code null}, the {@linkplain Comparable
151	+	*         natural ordering} of the elements will be used.
152	+	* @since 1.8
153	+	*/
154	+	public PriorityQueue(Comparator<? super E> comparator) {
155	+	this(DEFAULT_INITIAL_CAPACITY, comparator);
156	+	}
157	+
158	+	/**
159		* Creates a {@code PriorityQueue} with the specified initial capacity
160		* that orders its elements according to the specified comparator.
161		*
#	Line 174 | Line 192 | public class PriorityQueue<E> extends Ab
192		* @throws NullPointerException if the specified collection or any
193		*         of its elements are null
194		*/
177	–	@SuppressWarnings("unchecked")
195		public PriorityQueue(Collection<? extends E> c) {
196		if (c instanceof SortedSet<?>) {
197		SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
#	Line 206 | Line 223 | public class PriorityQueue<E> extends Ab
223		* @throws NullPointerException if the specified priority queue or any
224		*         of its elements are null
225		*/
209	–	@SuppressWarnings("unchecked")
226		public PriorityQueue(PriorityQueue<? extends E> c) {
227		this.comparator = (Comparator<? super E>) c.comparator();
228		initFromPriorityQueue(c);
#	Line 225 | Line 241 | public class PriorityQueue<E> extends Ab
241		* @throws NullPointerException if the specified sorted set or any
242		*         of its elements are null
243		*/
228	–	@SuppressWarnings("unchecked")
244		public PriorityQueue(SortedSet<? extends E> c) {
245		this.comparator = (Comparator<? super E>) c.comparator();
246		initElementsFromCollection(c);
247		}
248
249	+	/** Ensures that queue[0] exists, helping peek() and poll(). */
250	+	private static Object[] ensureNonEmpty(Object[] es) {
251	+	return (es.length > 0) ? es : new Object[1];
252	+	}
253	+
254		private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
255		if (c.getClass() == PriorityQueue.class) {
256	<	this.queue = c.toArray();
256	>	this.queue = ensureNonEmpty(c.toArray());
257		this.size = c.size();
258		} else {
259		initFromCollection(c);
#	Line 241 | Line 261 | public class PriorityQueue<E> extends Ab
261		}
262
263		private void initElementsFromCollection(Collection<? extends E> c) {
264	<	Object[] a = c.toArray();
264	>	Object[] es = c.toArray();
265	>	int len = es.length;
266		// If c.toArray incorrectly doesn't return Object[], copy it.
267	<	if (a.getClass() != Object[].class)
268	<	a = Arrays.copyOf(a, a.length, Object[].class);
248	<	int len = a.length;
267	>	if (es.getClass() != Object[].class)
268	>	es = Arrays.copyOf(es, len, Object[].class);
269		if (len == 1 || this.comparator != null)
270	<	for (int i = 0; i < len; i++)
271	<	if (a[i] == null)
270	>	for (Object e : es)
271	>	if (e == null)
272		throw new NullPointerException();
273	<	this.queue = a;
274	<	this.size = a.length;
273	>	this.queue = ensureNonEmpty(es);
274	>	this.size = len;
275		}
276
277		/**
#	Line 265 | Line 285 | public class PriorityQueue<E> extends Ab
285		}
286
287		/**
268	–	* The maximum size of array to allocate.
269	–	* Some VMs reserve some header words in an array.
270	–	* Attempts to allocate larger arrays may result in
271	–	* OutOfMemoryError: Requested array size exceeds VM limit
272	–	*/
273	–	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
274	–
275	–	/**
288		* Increases the capacity of the array.
289		*
290		* @param minCapacity the desired minimum capacity
#	Line 280 | Line 292 | public class PriorityQueue<E> extends Ab
292		private void grow(int minCapacity) {
293		int oldCapacity = queue.length;
294		// Double size if small; else grow by 50%
295	<	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
296	<	(oldCapacity + 2) :
297	<	(oldCapacity >> 1));
298	<	// overflow-conscious code
287	<	if (newCapacity - MAX_ARRAY_SIZE > 0)
288	<	newCapacity = hugeCapacity(minCapacity);
295	>	int newCapacity = ArraysSupport.newLength(oldCapacity,
296	>	minCapacity - oldCapacity, /* minimum growth */
297	>	oldCapacity < 64 ? oldCapacity + 2 : oldCapacity >> 1
298	>	/* preferred growth */);
299		queue = Arrays.copyOf(queue, newCapacity);
300		}
301
292	–	private static int hugeCapacity(int minCapacity) {
293	–	if (minCapacity < 0) // overflow
294	–	throw new OutOfMemoryError();
295	–	return (minCapacity > MAX_ARRAY_SIZE) ?
296	–	Integer.MAX_VALUE :
297	–	MAX_ARRAY_SIZE;
298	–	}
299	–
302		/**
303		* Inserts the specified element into this priority queue.
304		*
#	Line 326 | Line 328 | public class PriorityQueue<E> extends Ab
328		int i = size;
329		if (i >= queue.length)
330		grow(i + 1);
331	+	siftUp(i, e);
332		size = i + 1;
330	–	if (i == 0)
331	–	queue[0] = e;
332	–	else
333	–	siftUp(i, e);
333		return true;
334		}
335
337	–	@SuppressWarnings("unchecked")
336		public E peek() {
337	<	return (size == 0) ? null : (E) queue[0];
337	>	return (E) queue[0];
338		}
339
340		private int indexOf(Object o) {
341		if (o != null) {
342	<	for (int i = 0; i < size; i++)
343	<	if (o.equals(queue[i]))
342	>	final Object[] es = queue;
343	>	for (int i = 0, n = size; i < n; i++)
344	>	if (o.equals(es[i]))
345		return i;
346		}
347		return -1;
#	Line 370 | Line 369 | public class PriorityQueue<E> extends Ab
369		}
370
371		/**
372	<	* Version of remove using reference equality, not equals.
374	<	* Needed by iterator.remove.
372	>	* Identity-based version for use in Itr.remove.
373		*
374		* @param o element to be removed from this queue, if present
377	–	* @return {@code true} if removed
375		*/
376	<	boolean removeEq(Object o) {
377	<	for (int i = 0; i < size; i++) {
378	<	if (o == queue[i]) {
376	>	void removeEq(Object o) {
377	>	final Object[] es = queue;
378	>	for (int i = 0, n = size; i < n; i++) {
379	>	if (o == es[i]) {
380		removeAt(i);
381	<	return true;
381	>	break;
382		}
383		}
386	–	return false;
384		}
385
386		/**
#	Line 395 | Line 392 | public class PriorityQueue<E> extends Ab
392		* @return {@code true} if this queue contains the specified element
393		*/
394		public boolean contains(Object o) {
395	<	return indexOf(o) != -1;
395	>	return indexOf(o) >= 0;
396		}
397
398		/**
#	Line 437 | Line 434 | public class PriorityQueue<E> extends Ab
434		* The following code can be used to dump the queue into a newly
435		* allocated array of {@code String}:
436		*
437	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
437	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
438		*
439		* Note that {@code toArray(new Object[0])} is identical in function to
440		* {@code toArray()}.
#	Line 451 | Line 448 | public class PriorityQueue<E> extends Ab
448		*         this queue
449		* @throws NullPointerException if the specified array is null
450		*/
454	–	@SuppressWarnings("unchecked")
451		public <T> T[] toArray(T[] a) {
452		final int size = this.size;
453		if (a.length < size)
#	Line 478 | Line 474 | public class PriorityQueue<E> extends Ab
474		* Index (into queue array) of element to be returned by
475		* subsequent call to next.
476		*/
477	<	private int cursor = 0;
477	>	private int cursor;
478
479		/**
480		* Index of element returned by most recent call to next,
#	Line 498 | Line 494 | public class PriorityQueue<E> extends Ab
494		* We expect that most iterations, even those involving removals,
495		* will not need to store elements in this field.
496		*/
497	<	private ArrayDeque<E> forgetMeNot = null;
497	>	private ArrayDeque<E> forgetMeNot;
498
499		/**
500		* Element returned by the most recent call to next iff that
501		* element was drawn from the forgetMeNot list.
502		*/
503	<	private E lastRetElt = null;
503	>	private E lastRetElt;
504
505		/**
506		* The modCount value that the iterator believes that the backing
#	Line 513 | Line 509 | public class PriorityQueue<E> extends Ab
509		*/
510		private int expectedModCount = modCount;
511
512	+	Itr() {}                        // prevent access constructor creation
513	+
514		public boolean hasNext() {
515		return cursor < size ||
516		(forgetMeNot != null && !forgetMeNot.isEmpty());
517		}
518
521	–	@SuppressWarnings("unchecked")
519		public E next() {
520		if (expectedModCount != modCount)
521		throw new ConcurrentModificationException();
#	Line 543 | Line 540 | public class PriorityQueue<E> extends Ab
540		cursor--;
541		else {
542		if (forgetMeNot == null)
543	<	forgetMeNot = new ArrayDeque<E>();
543	>	forgetMeNot = new ArrayDeque<>();
544		forgetMeNot.add(moved);
545		}
546		} else if (lastRetElt != null) {
#	Line 566 | Line 563 | public class PriorityQueue<E> extends Ab
563		*/
564		public void clear() {
565		modCount++;
566	<	for (int i = 0; i < size; i++)
567	<	queue[i] = null;
566	>	final Object[] es = queue;
567	>	for (int i = 0, n = size; i < n; i++)
568	>	es[i] = null;
569		size = 0;
570		}
571
574	–	@SuppressWarnings("unchecked")
572		public E poll() {
573	<	if (size == 0)
574	<	return null;
575	<	int s = --size;
576	<	modCount++;
577	<	E result = (E) queue[0];
578	<	E x = (E) queue[s];
579	<	queue[s] = null;
580	<	if (s != 0)
581	<	siftDown(0, x);
573	>	final Object[] es;
574	>	final E result;
575	>
576	>	if ((result = (E) ((es = queue)[0])) != null) {
577	>	modCount++;
578	>	final int n;
579	>	final E x = (E) es[(n = --size)];
580	>	es[n] = null;
581	>	if (n > 0) {
582	>	final Comparator<? super E> cmp;
583	>	if ((cmp = comparator) == null)
584	>	siftDownComparable(0, x, es, n);
585	>	else
586	>	siftDownUsingComparator(0, x, es, n, cmp);
587	>	}
588	>	}
589		return result;
590		}
591
#	Line 597 | Line 601 | public class PriorityQueue<E> extends Ab
601		* position before i. This fact is used by iterator.remove so as to
602		* avoid missing traversing elements.
603		*/
604	<	@SuppressWarnings("unchecked")
601	<	private E removeAt(int i) {
604	>	E removeAt(int i) {
605		// assert i >= 0 && i < size;
606	+	final Object[] es = queue;
607		modCount++;
608		int s = --size;
609		if (s == i) // removed last element
610	<	queue[i] = null;
610	>	es[i] = null;
611		else {
612	<	E moved = (E) queue[s];
613	<	queue[s] = null;
612	>	E moved = (E) es[s];
613	>	es[s] = null;
614		siftDown(i, moved);
615	<	if (queue[i] == moved) {
615	>	if (es[i] == moved) {
616		siftUp(i, moved);
617	<	if (queue[i] != moved)
617	>	if (es[i] != moved)
618		return moved;
619		}
620		}
#	Line 622 | Line 626 | public class PriorityQueue<E> extends Ab
626		* promoting x up the tree until it is greater than or equal to
627		* its parent, or is the root.
628		*
629	<	* To simplify and speed up coercions and comparisons. the
629	>	* To simplify and speed up coercions and comparisons, the
630		* Comparable and Comparator versions are separated into different
631		* methods that are otherwise identical. (Similarly for siftDown.)
632		*
#	Line 631 | Line 635 | public class PriorityQueue<E> extends Ab
635		*/
636		private void siftUp(int k, E x) {
637		if (comparator != null)
638	<	siftUpUsingComparator(k, x);
638	>	siftUpUsingComparator(k, x, queue, comparator);
639		else
640	<	siftUpComparable(k, x);
640	>	siftUpComparable(k, x, queue);
641		}
642
643	<	@SuppressWarnings("unchecked")
644	<	private void siftUpComparable(int k, E x) {
641	<	Comparable<? super E> key = (Comparable<? super E>) x;
643	>	private static <T> void siftUpComparable(int k, T x, Object[] es) {
644	>	Comparable<? super T> key = (Comparable<? super T>) x;
645		while (k > 0) {
646		int parent = (k - 1) >>> 1;
647	<	Object e = queue[parent];
648	<	if (key.compareTo((E) e) >= 0)
647	>	Object e = es[parent];
648	>	if (key.compareTo((T) e) >= 0)
649		break;
650	<	queue[k] = e;
650	>	es[k] = e;
651		k = parent;
652		}
653	<	queue[k] = key;
653	>	es[k] = key;
654		}
655
656	<	@SuppressWarnings("unchecked")
657	<	private void siftUpUsingComparator(int k, E x) {
656	>	private static <T> void siftUpUsingComparator(
657	>	int k, T x, Object[] es, Comparator<? super T> cmp) {
658		while (k > 0) {
659		int parent = (k - 1) >>> 1;
660	<	Object e = queue[parent];
661	<	if (comparator.compare(x, (E) e) >= 0)
660	>	Object e = es[parent];
661	>	if (cmp.compare(x, (T) e) >= 0)
662		break;
663	<	queue[k] = e;
663	>	es[k] = e;
664		k = parent;
665		}
666	<	queue[k] = x;
666	>	es[k] = x;
667		}
668
669		/**
#	Line 673 | Line 676 | public class PriorityQueue<E> extends Ab
676		*/
677		private void siftDown(int k, E x) {
678		if (comparator != null)
679	<	siftDownUsingComparator(k, x);
679	>	siftDownUsingComparator(k, x, queue, size, comparator);
680		else
681	<	siftDownComparable(k, x);
681	>	siftDownComparable(k, x, queue, size);
682		}
683
684	<	@SuppressWarnings("unchecked")
685	<	private void siftDownComparable(int k, E x) {
686	<	Comparable<? super E> key = (Comparable<? super E>)x;
687	<	int half = size >>> 1;        // loop while a non-leaf
684	>	private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
685	>	// assert n > 0;
686	>	Comparable<? super T> key = (Comparable<? super T>)x;
687	>	int half = n >>> 1;           // loop while a non-leaf
688		while (k < half) {
689		int child = (k << 1) + 1; // assume left child is least
690	<	Object c = queue[child];
690	>	Object c = es[child];
691		int right = child + 1;
692	<	if (right < size &&
693	<	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
694	<	c = queue[child = right];
695	<	if (key.compareTo((E) c) <= 0)
692	>	if (right < n &&
693	>	((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
694	>	c = es[child = right];
695	>	if (key.compareTo((T) c) <= 0)
696		break;
697	<	queue[k] = c;
697	>	es[k] = c;
698		k = child;
699		}
700	<	queue[k] = key;
700	>	es[k] = key;
701		}
702
703	<	@SuppressWarnings("unchecked")
704	<	private void siftDownUsingComparator(int k, E x) {
705	<	int half = size >>> 1;
703	>	private static <T> void siftDownUsingComparator(
704	>	int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
705	>	// assert n > 0;
706	>	int half = n >>> 1;
707		while (k < half) {
708		int child = (k << 1) + 1;
709	<	Object c = queue[child];
709	>	Object c = es[child];
710		int right = child + 1;
711	<	if (right < size &&
712	<	comparator.compare((E) c, (E) queue[right]) > 0)
713	<	c = queue[child = right];
710	<	if (comparator.compare(x, (E) c) <= 0)
711	>	if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
712	>	c = es[child = right];
713	>	if (cmp.compare(x, (T) c) <= 0)
714		break;
715	<	queue[k] = c;
715	>	es[k] = c;
716		k = child;
717		}
718	<	queue[k] = x;
718	>	es[k] = x;
719		}
720
721		/**
722		* Establishes the heap invariant (described above) in the entire tree,
723		* assuming nothing about the order of the elements prior to the call.
724	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
725		*/
722	–	@SuppressWarnings("unchecked")
726		private void heapify() {
727	<	for (int i = (size >>> 1) - 1; i >= 0; i--)
728	<	siftDown(i, (E) queue[i]);
727	>	final Object[] es = queue;
728	>	int n = size, i = (n >>> 1) - 1;
729	>	final Comparator<? super E> cmp;
730	>	if ((cmp = comparator) == null)
731	>	for (; i >= 0; i--)
732	>	siftDownComparable(i, (E) es[i], es, n);
733	>	else
734	>	for (; i >= 0; i--)
735	>	siftDownUsingComparator(i, (E) es[i], es, n, cmp);
736		}
737
738		/**
#	Line 741 | Line 751 | public class PriorityQueue<E> extends Ab
751		/**
752		* Saves this queue to a stream (that is, serializes it).
753		*
754	+	* @param s the stream
755	+	* @throws java.io.IOException if an I/O error occurs
756		* @serialData The length of the array backing the instance is
757		*             emitted (int), followed by all of its elements
758		*             (each an {@code Object}) in the proper order.
747	–	* @param s the stream
759		*/
760	+	// OPENJDK @java.io.Serial
761		private void writeObject(java.io.ObjectOutputStream s)
762		throws java.io.IOException {
763		// Write out element count, and any hidden stuff
#	Line 755 | Line 767 | public class PriorityQueue<E> extends Ab
767		s.writeInt(Math.max(2, size + 1));
768
769		// Write out all elements in the "proper order".
770	<	for (int i = 0; i < size; i++)
771	<	s.writeObject(queue[i]);
770	>	final Object[] es = queue;
771	>	for (int i = 0, n = size; i < n; i++)
772	>	s.writeObject(es[i]);
773		}
774
775		/**
#	Line 764 | Line 777 | public class PriorityQueue<E> extends Ab
777		* (that is, deserializes it).
778		*
779		* @param s the stream
780	+	* @throws ClassNotFoundException if the class of a serialized object
781	+	*         could not be found
782	+	* @throws java.io.IOException if an I/O error occurs
783		*/
784	+	// OPENJDK @java.io.Serial
785		private void readObject(java.io.ObjectInputStream s)
786		throws java.io.IOException, ClassNotFoundException {
787		// Read in size, and any hidden stuff
#	Line 773 | Line 790 | public class PriorityQueue<E> extends Ab
790		// Read in (and discard) array length
791		s.readInt();
792
793	<	queue = new Object[size];
793	>	jsr166.Platform.checkArray(s, Object[].class, size);
794	>	final Object[] es = queue = new Object[Math.max(size, 1)];
795
796		// Read in all elements.
797	<	for (int i = 0; i < size; i++)
798	<	queue[i] = s.readObject();
797	>	for (int i = 0, n = size; i < n; i++)
798	>	es[i] = s.readObject();
799
800		// Elements are guaranteed to be in "proper order", but the
801		// spec has never explained what that might be.
802		heapify();
803		}
804
805	<	// wrapping constructor in method avoids transient javac problems
806	<	final PriorityQueueSpliterator<E> spliterator(int origin, int fence,
807	<	int expectedModCount) {
808	<	return new PriorityQueueSpliterator<E>(this, origin, fence,
809	<	expectedModCount);
810	<	}
811	<
812	<	public Stream<E> stream() {
813	<	int flags = Streams.STREAM_IS_SIZED;
814	<	return Streams.stream
815	<	(() -> spliterator(0, size, modCount), flags);
816	<	}
817	<	public Stream<E> parallelStream() {
818	<	int flags = Streams.STREAM_IS_SIZED;
819	<	return Streams.parallelStream
820	<	(() -> spliterator(0, size, modCount), flags);
821	<	}
822	<
823	<	/** Index-based split-by-two Spliterator */
824	<	static final class PriorityQueueSpliterator<E> implements Spliterator<E> {
825	<	private final PriorityQueue<E> pq;
826	<	private int index;           // current index, modified on advance/split
827	<	private final int fence;     // one past last index
828	<	private final int expectedModCount; // for comodification checks
829	<
830	<	/** Create new spliterator covering the given  range */
831	<	PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
814	<	int expectedModCount) {
815	<	this.pq = pq; this.index = origin; this.fence = fence;
805	>	/**
806	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
807	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
808	>	* queue. The spliterator does not traverse elements in any particular order
809	>	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
810	>	*
811	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
812	>	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
813	>	* Overriding implementations should document the reporting of additional
814	>	* characteristic values.
815	>	*
816	>	* @return a {@code Spliterator} over the elements in this queue
817	>	* @since 1.8
818	>	*/
819	>	public final Spliterator<E> spliterator() {
820	>	return new PriorityQueueSpliterator(0, -1, 0);
821	>	}
822	>
823	>	final class PriorityQueueSpliterator implements Spliterator<E> {
824	>	private int index;            // current index, modified on advance/split
825	>	private int fence;            // -1 until first use
826	>	private int expectedModCount; // initialized when fence set
827	>
828	>	/** Creates new spliterator covering the given range. */
829	>	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
830	>	this.index = origin;
831	>	this.fence = fence;
832		this.expectedModCount = expectedModCount;
833		}
834
835	<	public PriorityQueueSpliterator<E> trySplit() {
836	<	int lo = index, mid = (lo + fence) >>> 1;
835	>	private int getFence() { // initialize fence to size on first use
836	>	int hi;
837	>	if ((hi = fence) < 0) {
838	>	expectedModCount = modCount;
839	>	hi = fence = size;
840	>	}
841	>	return hi;
842	>	}
843	>
844	>	public PriorityQueueSpliterator trySplit() {
845	>	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
846		return (lo >= mid) ? null :
847	<	new PriorityQueueSpliterator<E>(pq, lo, index = mid,
823	<	expectedModCount);
847	>	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
848		}
849
850	<	public void forEach(Consumer<? super E> block) {
851	<	Object[] a; int i, hi; // hoist accesses and checks from loop
828	<	if (block == null)
850	>	public void forEachRemaining(Consumer<? super E> action) {
851	>	if (action == null)
852		throw new NullPointerException();
853	<	if ((a = pq.queue).length >= (hi = fence) &&
854	<	(i = index) >= 0 && i < hi) {
855	<	index = hi;
856	<	do {
857	<	@SuppressWarnings("unchecked") E e = (E) a[i];
858	<	block.accept(e);
859	<	} while (++i < hi);
837	<	if (pq.modCount != expectedModCount)
838	<	throw new ConcurrentModificationException();
853	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
854	>	final Object[] es = queue;
855	>	int i, hi; E e;
856	>	for (i = index, index = hi = fence; i < hi; i++) {
857	>	if ((e = (E) es[i]) == null)
858	>	break;      // must be CME
859	>	action.accept(e);
860		}
861	+	if (modCount != expectedModCount)
862	+	throw new ConcurrentModificationException();
863		}
864
865	<	public boolean tryAdvance(Consumer<? super E> block) {
866	<	if (index >= 0 && index < fence) {
867	<	@SuppressWarnings("unchecked") E e =
868	<	(E)pq.queue[index++];
869	<	block.accept(e);
870	<	if (pq.modCount != expectedModCount)
865	>	public boolean tryAdvance(Consumer<? super E> action) {
866	>	if (action == null)
867	>	throw new NullPointerException();
868	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
869	>	int i;
870	>	if ((i = index) < fence) {
871	>	index = i + 1;
872	>	E e;
873	>	if ((e = (E) queue[i]) == null
874	>	|| modCount != expectedModCount)
875		throw new ConcurrentModificationException();
876	+	action.accept(e);
877		return true;
878		}
879		return false;
880		}
881
882	<	public long estimateSize() { return (long)(fence - index); }
883	<	public boolean hasExactSize() { return true; }
884	<	public boolean hasExactSplits() { return true; }
882	>	public long estimateSize() {
883	>	return getFence() - index;
884	>	}
885	>
886	>	public int characteristics() {
887	>	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
888	>	}
889	>	}
890	>
891	>	/**
892	>	* @throws NullPointerException {@inheritDoc}
893	>	*/
894	>	public boolean removeIf(Predicate<? super E> filter) {
895	>	Objects.requireNonNull(filter);
896	>	return bulkRemove(filter);
897	>	}
898	>
899	>	/**
900	>	* @throws NullPointerException {@inheritDoc}
901	>	*/
902	>	public boolean removeAll(Collection<?> c) {
903	>	Objects.requireNonNull(c);
904	>	return bulkRemove(e -> c.contains(e));
905	>	}
906	>
907	>	/**
908	>	* @throws NullPointerException {@inheritDoc}
909	>	*/
910	>	public boolean retainAll(Collection<?> c) {
911	>	Objects.requireNonNull(c);
912	>	return bulkRemove(e -> !c.contains(e));
913	>	}
914	>
915	>	// A tiny bit set implementation
916	>
917	>	private static long[] nBits(int n) {
918	>	return new long[((n - 1) >> 6) + 1];
919	>	}
920	>	private static void setBit(long[] bits, int i) {
921	>	bits[i >> 6] |= 1L << i;
922	>	}
923	>	private static boolean isClear(long[] bits, int i) {
924	>	return (bits[i >> 6] & (1L << i)) == 0;
925	>	}
926	>
927	>	/** Implementation of bulk remove methods. */
928	>	private boolean bulkRemove(Predicate<? super E> filter) {
929	>	final int expectedModCount = ++modCount;
930	>	final Object[] es = queue;
931	>	final int end = size;
932	>	int i;
933	>	// Optimize for initial run of survivors
934	>	for (i = 0; i < end && !filter.test((E) es[i]); i++)
935	>	;
936	>	if (i >= end) {
937	>	if (modCount != expectedModCount)
938	>	throw new ConcurrentModificationException();
939	>	return false;
940	>	}
941	>	// Tolerate predicates that reentrantly access the collection for
942	>	// read (but writers still get CME), so traverse once to find
943	>	// elements to delete, a second pass to physically expunge.
944	>	final int beg = i;
945	>	final long[] deathRow = nBits(end - beg);
946	>	deathRow[0] = 1L;   // set bit 0
947	>	for (i = beg + 1; i < end; i++)
948	>	if (filter.test((E) es[i]))
949	>	setBit(deathRow, i - beg);
950	>	if (modCount != expectedModCount)
951	>	throw new ConcurrentModificationException();
952	>	int w = beg;
953	>	for (i = beg; i < end; i++)
954	>	if (isClear(deathRow, i - beg))
955	>	es[w++] = es[i];
956	>	for (i = size = w; i < end; i++)
957	>	es[i] = null;
958	>	heapify();
959	>	return true;
960	>	}
961	>
962	>	/**
963	>	* @throws NullPointerException {@inheritDoc}
964	>	*/
965	>	public void forEach(Consumer<? super E> action) {
966	>	Objects.requireNonNull(action);
967	>	final int expectedModCount = modCount;
968	>	final Object[] es = queue;
969	>	for (int i = 0, n = size; i < n; i++)
970	>	action.accept((E) es[i]);
971	>	if (expectedModCount != modCount)
972	>	throw new ConcurrentModificationException();
973		}
974		}

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