ViewVC Help

View File | Revision Log | Show Annotations | Download File | Root Listing

root/jsr166/jsr166/src/main/java/util/PriorityQueue.java

Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.1 by tim, Wed May 14 21:30:45 2003 UTC vs.
Revision 1.133 by jsr166, Thu Oct 10 16:53:08 2019 UTC

#	Line 1 | Line 1
1	+	/*
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
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.*;
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 (resizable) priority queue based on a priority
35	<	* heap.The take operation returns the least element with respect to
36	<	* the given ordering. (If more than one element is tied for least
37	<	* value, one of them is arbitrarily chosen to be returned -- no
38	<	* guarantees are made for ordering across ties.) Ordering follows the
39	<	* java.util.Collection conventions: Either the elements must be
40	<	* Comparable, or a Comparator must be supplied. Comparison failures
41	<	* throw ClassCastExceptions during insertions and extractions.
42	<	**/
43	<	public class PriorityQueue<E> extends AbstractCollection<E> implements Queue<E> {
44	<	public PriorityQueue(int initialCapacity) {}
45	<	public PriorityQueue(int initialCapacity, Comparator comparator) {}
46	<
47	<	public PriorityQueue(int initialCapacity, Collection initialElements) {}
48	<
49	<	public PriorityQueue(int initialCapacity, Comparator comparator, Collection initialElements) {}
50	<
51	<	public boolean add(E x) {
52	<	return false;
34	>	* An unbounded priority {@linkplain Queue queue} based on a priority heap.
35	>	* The elements of the priority queue are ordered according to their
36	>	* {@linkplain Comparable natural ordering}, or by a {@link Comparator}
37	>	* provided at queue construction time, depending on which constructor is
38	>	* used.  A priority queue does not permit {@code null} elements.
39	>	* A priority queue relying on natural ordering also does not permit
40	>	* insertion of non-comparable objects (doing so may result in
41	>	* {@code ClassCastException}).
42	>	*
43	>	* <p>The <em>head</em> of this queue is the <em>least</em> element
44	>	* with respect to the specified ordering.  If multiple elements are
45	>	* tied for least value, the head is one of those elements -- ties are
46	>	* broken arbitrarily.  The queue retrieval operations {@code poll},
47	>	* {@code remove}, {@code peek}, and {@code element} access the
48	>	* element at the head of the queue.
49	>	*
50	>	* <p>A priority queue is unbounded, but has an internal
51	>	* <i>capacity</i> governing the size of an array used to store the
52	>	* elements on the queue.  It is always at least as large as the queue
53	>	* size.  As elements are added to a priority queue, its capacity
54	>	* grows automatically.  The details of the growth policy are not
55	>	* specified.
56	>	*
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()} 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>
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 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}/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 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;
94	>
95	>	/**
96	>	* Priority queue represented as a balanced binary heap: the two
97	>	* children of queue[n] are queue[2*n+1] and queue[2*(n+1)].  The
98	>	* priority queue is ordered by comparator, or by the elements'
99	>	* natural ordering, if comparator is null: For each node n in the
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	>	transient Object[] queue; // non-private to simplify nested class access
104	>
105	>	/**
106	>	* The number of elements in the priority queue.
107	>	*/
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;     // non-private to simplify nested class access
122	>
123	>	/**
124	>	* Creates a {@code PriorityQueue} with the default initial
125	>	* capacity (11) that orders its elements according to their
126	>	* {@linkplain Comparable natural ordering}.
127	>	*/
128	>	public PriorityQueue() {
129	>	this(DEFAULT_INITIAL_CAPACITY, null);
130		}
131	<	public boolean offer(E x) {
132	<	return false;
131	>
132	>	/**
133	>	* Creates a {@code PriorityQueue} with the specified initial
134	>	* capacity that orders its elements according to their
135	>	* {@linkplain Comparable natural ordering}.
136	>	*
137	>	* @param initialCapacity the initial capacity for this priority queue
138	>	* @throws IllegalArgumentException if {@code initialCapacity} is less
139	>	*         than 1
140	>	*/
141	>	public PriorityQueue(int initialCapacity) {
142	>	this(initialCapacity, null);
143		}
144	<	public boolean remove(Object x) {
145	<	return false;
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	<	public E remove() {
159	<	return null;
158	>	/**
159	>	* Creates a {@code PriorityQueue} with the specified initial capacity
160	>	* that orders its elements according to the specified comparator.
161	>	*
162	>	* @param  initialCapacity the initial capacity for this priority queue
163	>	* @param  comparator the comparator that will be used to order this
164	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
165	>	*         natural ordering} of the elements will be used.
166	>	* @throws IllegalArgumentException if {@code initialCapacity} is
167	>	*         less than 1
168	>	*/
169	>	public PriorityQueue(int initialCapacity,
170	>	Comparator<? super E> comparator) {
171	>	// Note: This restriction of at least one is not actually needed,
172	>	// but continues for 1.5 compatibility
173	>	if (initialCapacity < 1)
174	>	throw new IllegalArgumentException();
175	>	this.queue = new Object[initialCapacity];
176	>	this.comparator = comparator;
177		}
178	<	public Iterator<E> iterator() {
179	<	return null;
178	>
179	>	/**
180	>	* Creates a {@code PriorityQueue} containing the elements in the
181	>	* specified collection.  If the specified collection is an instance of
182	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
183	>	* priority queue will be ordered according to the same ordering.
184	>	* Otherwise, this priority queue will be ordered according to the
185	>	* {@linkplain Comparable natural ordering} of its elements.
186	>	*
187	>	* @param  c the collection whose elements are to be placed
188	>	*         into this priority queue
189	>	* @throws ClassCastException if elements of the specified collection
190	>	*         cannot be compared to one another according to the priority
191	>	*         queue's ordering
192	>	* @throws NullPointerException if the specified collection or any
193	>	*         of its elements are null
194	>	*/
195	>	public PriorityQueue(Collection<? extends E> c) {
196	>	if (c instanceof SortedSet<?>) {
197	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
198	>	this.comparator = (Comparator<? super E>) ss.comparator();
199	>	initElementsFromCollection(ss);
200	>	}
201	>	else if (c instanceof PriorityQueue<?>) {
202	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
203	>	this.comparator = (Comparator<? super E>) pq.comparator();
204	>	initFromPriorityQueue(pq);
205	>	}
206	>	else {
207	>	this.comparator = null;
208	>	initFromCollection(c);
209	>	}
210		}
211
212	<	public E element() {
213	<	return null;
212	>	/**
213	>	* Creates a {@code PriorityQueue} containing the elements in the
214	>	* specified priority queue.  This priority queue will be
215	>	* ordered according to the same ordering as the given priority
216	>	* queue.
217	>	*
218	>	* @param  c the priority queue whose elements are to be placed
219	>	*         into this priority queue
220	>	* @throws ClassCastException if elements of {@code c} cannot be
221	>	*         compared to one another according to {@code c}'s
222	>	*         ordering
223	>	* @throws NullPointerException if the specified priority queue or any
224	>	*         of its elements are null
225	>	*/
226	>	public PriorityQueue(PriorityQueue<? extends E> c) {
227	>	this.comparator = (Comparator<? super E>) c.comparator();
228	>	initFromPriorityQueue(c);
229		}
230	<	public E poll() {
231	<	return null;
230	>
231	>	/**
232	>	* Creates a {@code PriorityQueue} containing the elements in the
233	>	* specified sorted set.   This priority queue will be ordered
234	>	* according to the same ordering as the given sorted set.
235	>	*
236	>	* @param  c the sorted set whose elements are to be placed
237	>	*         into this priority queue
238	>	* @throws ClassCastException if elements of the specified sorted
239	>	*         set cannot be compared to one another according to the
240	>	*         sorted set's ordering
241	>	* @throws NullPointerException if the specified sorted set or any
242	>	*         of its elements are null
243	>	*/
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 = ensureNonEmpty(c.toArray());
257	>	this.size = c.size();
258	>	} else {
259	>	initFromCollection(c);
260	>	}
261	>	}
262	>
263	>	private void initElementsFromCollection(Collection<? extends E> c) {
264	>	Object[] es = c.toArray();
265	>	int len = es.length;
266	>	// If c.toArray incorrectly doesn't return Object[], copy it.
267	>	if (es.getClass() != Object[].class)
268	>	es = Arrays.copyOf(es, len, Object[].class);
269	>	if (len == 1 || this.comparator != null)
270	>	for (Object e : es)
271	>	if (e == null)
272	>	throw new NullPointerException();
273	>	this.queue = ensureNonEmpty(es);
274	>	this.size = len;
275	>	}
276	>
277	>	/**
278	>	* Initializes queue array with elements from the given Collection.
279	>	*
280	>	* @param c the collection
281	>	*/
282	>	private void initFromCollection(Collection<? extends E> c) {
283	>	initElementsFromCollection(c);
284	>	heapify();
285	>	}
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	>	int oldCapacity = queue.length;
294	>	// Double size if small; else grow by 50%
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	>
302	>	/**
303	>	* Inserts the specified element into this priority queue.
304	>	*
305	>	* @return {@code true} (as specified by {@link Collection#add})
306	>	* @throws ClassCastException if the specified element cannot be
307	>	*         compared with elements currently in this priority queue
308	>	*         according to the priority queue's ordering
309	>	* @throws NullPointerException if the specified element is null
310	>	*/
311	>	public boolean add(E e) {
312	>	return offer(e);
313		}
314	+
315	+	/**
316	+	* Inserts the specified element into this priority queue.
317	+	*
318	+	* @return {@code true} (as specified by {@link Queue#offer})
319	+	* @throws ClassCastException if the specified element cannot be
320	+	*         compared with elements currently in this priority queue
321	+	*         according to the priority queue's ordering
322	+	* @throws NullPointerException if the specified element is null
323	+	*/
324	+	public boolean offer(E e) {
325	+	if (e == null)
326	+	throw new NullPointerException();
327	+	modCount++;
328	+	int i = size;
329	+	if (i >= queue.length)
330	+	grow(i + 1);
331	+	siftUp(i, e);
332	+	size = i + 1;
333	+	return true;
334	+	}
335	+
336		public E peek() {
337	<	return null;
337	>	return (E) queue[0];
338		}
339
340	<	public boolean isEmpty() {
341	<	return false;
340	>	private int indexOf(Object o) {
341	>	if (o != null) {
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;
348		}
349	<	public int size() {
350	<	return 0;
349	>
350	>	/**
351	>	* Removes a single instance of the specified element from this queue,
352	>	* if it is present.  More formally, removes an element {@code e} such
353	>	* that {@code o.equals(e)}, if this queue contains one or more such
354	>	* elements.  Returns {@code true} if and only if this queue contained
355	>	* the specified element (or equivalently, if this queue changed as a
356	>	* result of the call).
357	>	*
358	>	* @param o element to be removed from this queue, if present
359	>	* @return {@code true} if this queue changed as a result of the call
360	>	*/
361	>	public boolean remove(Object o) {
362	>	int i = indexOf(o);
363	>	if (i == -1)
364	>	return false;
365	>	else {
366	>	removeAt(i);
367	>	return true;
368	>	}
369	>	}
370	>
371	>	/**
372	>	* Identity-based version for use in Itr.remove.
373	>	*
374	>	* @param o element to be removed from this queue, if present
375	>	*/
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	>	break;
382	>	}
383	>	}
384		}
385	+
386	+	/**
387	+	* Returns {@code true} if this queue contains the specified element.
388	+	* More formally, returns {@code true} if and only if this queue contains
389	+	* at least one element {@code e} such that {@code o.equals(e)}.
390	+	*
391	+	* @param o object to be checked for containment in this queue
392	+	* @return {@code true} if this queue contains the specified element
393	+	*/
394	+	public boolean contains(Object o) {
395	+	return indexOf(o) >= 0;
396	+	}
397	+
398	+	/**
399	+	* Returns an array containing all of the elements in this queue.
400	+	* The elements are in no particular order.
401	+	*
402	+	* <p>The returned array will be "safe" in that no references to it are
403	+	* maintained by this queue.  (In other words, this method must allocate
404	+	* a new array).  The caller is thus free to modify the returned array.
405	+	*
406	+	* <p>This method acts as bridge between array-based and collection-based
407	+	* APIs.
408	+	*
409	+	* @return an array containing all of the elements in this queue
410	+	*/
411		public Object[] toArray() {
412	<	return null;
412	>	return Arrays.copyOf(queue, size);
413	>	}
414	>
415	>	/**
416	>	* Returns an array containing all of the elements in this queue; the
417	>	* runtime type of the returned array is that of the specified array.
418	>	* The returned array elements are in no particular order.
419	>	* If the queue fits in the specified array, it is returned therein.
420	>	* Otherwise, a new array is allocated with the runtime type of the
421	>	* specified array and the size of this queue.
422	>	*
423	>	* <p>If the queue fits in the specified array with room to spare
424	>	* (i.e., the array has more elements than the queue), the element in
425	>	* the array immediately following the end of the collection is set to
426	>	* {@code null}.
427	>	*
428	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
429	>	* array-based and collection-based APIs.  Further, this method allows
430	>	* precise control over the runtime type of the output array, and may,
431	>	* under certain circumstances, be used to save allocation costs.
432	>	*
433	>	* <p>Suppose {@code x} is a queue known to contain only strings.
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>
438	>	*
439	>	* Note that {@code toArray(new Object[0])} is identical in function to
440	>	* {@code toArray()}.
441	>	*
442	>	* @param a the array into which the elements of the queue are to
443	>	*          be stored, if it is big enough; otherwise, a new array of the
444	>	*          same runtime type is allocated for this purpose.
445	>	* @return an array containing all of the elements in this queue
446	>	* @throws ArrayStoreException if the runtime type of the specified array
447	>	*         is not a supertype of the runtime type of every element in
448	>	*         this queue
449	>	* @throws NullPointerException if the specified array is null
450	>	*/
451	>	public <T> T[] toArray(T[] a) {
452	>	final int size = this.size;
453	>	if (a.length < size)
454	>	// Make a new array of a's runtime type, but my contents:
455	>	return (T[]) Arrays.copyOf(queue, size, a.getClass());
456	>	System.arraycopy(queue, 0, a, 0, size);
457	>	if (a.length > size)
458	>	a[size] = null;
459	>	return a;
460	>	}
461	>
462	>	/**
463	>	* Returns an iterator over the elements in this queue. The iterator
464	>	* does not return the elements in any particular order.
465	>	*
466	>	* @return an iterator over the elements in this queue
467	>	*/
468	>	public Iterator<E> iterator() {
469	>	return new Itr();
470	>	}
471	>
472	>	private final class Itr implements Iterator<E> {
473	>	/**
474	>	* Index (into queue array) of element to be returned by
475	>	* subsequent call to next.
476	>	*/
477	>	private int cursor;
478	>
479	>	/**
480	>	* Index of element returned by most recent call to next,
481	>	* unless that element came from the forgetMeNot list.
482	>	* Set to -1 if element is deleted by a call to remove.
483	>	*/
484	>	private int lastRet = -1;
485	>
486	>	/**
487	>	* A queue of elements that were moved from the unvisited portion of
488	>	* the heap into the visited portion as a result of "unlucky" element
489	>	* removals during the iteration.  (Unlucky element removals are those
490	>	* that require a siftup instead of a siftdown.)  We must visit all of
491	>	* the elements in this list to complete the iteration.  We do this
492	>	* after we've completed the "normal" iteration.
493	>	*
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;
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;
504	>
505	>	/**
506	>	* The modCount value that the iterator believes that the backing
507	>	* Queue should have.  If this expectation is violated, the iterator
508	>	* has detected concurrent modification.
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	>
519	>	public E next() {
520	>	if (expectedModCount != modCount)
521	>	throw new ConcurrentModificationException();
522	>	if (cursor < size)
523	>	return (E) queue[lastRet = cursor++];
524	>	if (forgetMeNot != null) {
525	>	lastRet = -1;
526	>	lastRetElt = forgetMeNot.poll();
527	>	if (lastRetElt != null)
528	>	return lastRetElt;
529	>	}
530	>	throw new NoSuchElementException();
531	>	}
532	>
533	>	public void remove() {
534	>	if (expectedModCount != modCount)
535	>	throw new ConcurrentModificationException();
536	>	if (lastRet != -1) {
537	>	E moved = PriorityQueue.this.removeAt(lastRet);
538	>	lastRet = -1;
539	>	if (moved == null)
540	>	cursor--;
541	>	else {
542	>	if (forgetMeNot == null)
543	>	forgetMeNot = new ArrayDeque<>();
544	>	forgetMeNot.add(moved);
545	>	}
546	>	} else if (lastRetElt != null) {
547	>	PriorityQueue.this.removeEq(lastRetElt);
548	>	lastRetElt = null;
549	>	} else {
550	>	throw new IllegalStateException();
551	>	}
552	>	expectedModCount = modCount;
553	>	}
554	>	}
555	>
556	>	public int size() {
557	>	return size;
558	>	}
559	>
560	>	/**
561	>	* Removes all of the elements from this priority queue.
562	>	* The queue will be empty after this call returns.
563	>	*/
564	>	public void clear() {
565	>	modCount++;
566	>	final Object[] es = queue;
567	>	for (int i = 0, n = size; i < n; i++)
568	>	es[i] = null;
569	>	size = 0;
570	>	}
571	>
572	>	public E poll() {
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
592	<	public <T> T[] toArray(T[] array) {
592	>	/**
593	>	* Removes the ith element from queue.
594	>	*
595	>	* Normally this method leaves the elements at up to i-1,
596	>	* inclusive, untouched.  Under these circumstances, it returns
597	>	* null.  Occasionally, in order to maintain the heap invariant,
598	>	* it must swap a later element of the list with one earlier than
599	>	* i.  Under these circumstances, this method returns the element
600	>	* that was previously at the end of the list and is now at some
601	>	* position before i. This fact is used by iterator.remove so as to
602	>	* avoid missing traversing elements.
603	>	*/
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	>	es[i] = null;
611	>	else {
612	>	E moved = (E) es[s];
613	>	es[s] = null;
614	>	siftDown(i, moved);
615	>	if (es[i] == moved) {
616	>	siftUp(i, moved);
617	>	if (es[i] != moved)
618	>	return moved;
619	>	}
620	>	}
621		return null;
622		}
623
624	+	/**
625	+	* Inserts item x at position k, maintaining heap invariant by
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
630	+	* Comparable and Comparator versions are separated into different
631	+	* methods that are otherwise identical. (Similarly for siftDown.)
632	+	*
633	+	* @param k the position to fill
634	+	* @param x the item to insert
635	+	*/
636	+	private void siftUp(int k, E x) {
637	+	if (comparator != null)
638	+	siftUpUsingComparator(k, x, queue, comparator);
639	+	else
640	+	siftUpComparable(k, x, queue);
641	+	}
642	+
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 = es[parent];
648	+	if (key.compareTo((T) e) >= 0)
649	+	break;
650	+	es[k] = e;
651	+	k = parent;
652	+	}
653	+	es[k] = key;
654	+	}
655	+
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 = es[parent];
661	+	if (cmp.compare(x, (T) e) >= 0)
662	+	break;
663	+	es[k] = e;
664	+	k = parent;
665	+	}
666	+	es[k] = x;
667	+	}
668	+
669	+	/**
670	+	* Inserts item x at position k, maintaining heap invariant by
671	+	* demoting x down the tree repeatedly until it is less than or
672	+	* equal to its children or is a leaf.
673	+	*
674	+	* @param k the position to fill
675	+	* @param x the item to insert
676	+	*/
677	+	private void siftDown(int k, E x) {
678	+	if (comparator != null)
679	+	siftDownUsingComparator(k, x, queue, size, comparator);
680	+	else
681	+	siftDownComparable(k, x, queue, size);
682	+	}
683	+
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 = es[child];
691	+	int right = child + 1;
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	+	es[k] = c;
698	+	k = child;
699	+	}
700	+	es[k] = key;
701	+	}
702	+
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 = es[child];
710	+	int right = child + 1;
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	+	es[k] = c;
716	+	k = child;
717	+	}
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	+	*/
726	+	private void heapify() {
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	+	/**
739	+	* Returns the comparator used to order the elements in this
740	+	* queue, or {@code null} if this queue is sorted according to
741	+	* the {@linkplain Comparable natural ordering} of its elements.
742	+	*
743	+	* @return the comparator used to order this queue, or
744	+	*         {@code null} if this queue is sorted according to the
745	+	*         natural ordering of its elements
746	+	*/
747	+	public Comparator<? super E> comparator() {
748	+	return comparator;
749	+	}
750	+
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.
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
764	+	s.defaultWriteObject();
765	+
766	+	// Write out array length, for compatibility with 1.5 version
767	+	s.writeInt(Math.max(2, size + 1));
768	+
769	+	// Write out all elements in the "proper order".
770	+	final Object[] es = queue;
771	+	for (int i = 0, n = size; i < n; i++)
772	+	s.writeObject(es[i]);
773	+	}
774	+
775	+	/**
776	+	* Reconstitutes the {@code PriorityQueue} instance from a stream
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
788	+	s.defaultReadObject();
789	+
790	+	// Read in (and discard) array length
791	+	s.readInt();
792	+
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, 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	+	/**
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	+	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(lo, index = mid, expectedModCount);
848	+	}
849	+
850	+	public void forEachRemaining(Consumer<? super E> action) {
851	+	if (action == null)
852	+	throw new NullPointerException();
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> 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() {
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		}

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines