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Comparing jsr166/src/main/java/util/PriorityQueue.java (file contents):
Revision 1.54 by jsr166, Thu Nov 24 03:44:57 2005 UTC vs.
Revision 1.130 by jsr166, Sun Nov 11 16:27:28 2018 UTC

#	Line 1 | Line 1
1		/*
2	<	* @(#)PriorityQueue.java       1.8 05/08/27
2	>	* Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
3	>	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4		*
5	<	* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
6	<	* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
5	>	* This code is free software; you can redistribute it and/or modify it
6	>	* under the terms of the GNU General Public License version 2 only, as
7	>	* published by the Free Software Foundation.  Oracle designates this
8	>	* particular file as subject to the "Classpath" exception as provided
9	>	* by Oracle in the LICENSE file that accompanied this code.
10	>	*
11	>	* This code is distributed in the hope that it will be useful, but WITHOUT
12	>	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13	>	* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14	>	* version 2 for more details (a copy is included in the LICENSE file that
15	>	* accompanied this code).
16	>	*
17	>	* You should have received a copy of the GNU General Public License version
18	>	* 2 along with this work; if not, write to the Free Software Foundation,
19	>	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20	>	*
21	>	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22	>	* or visit www.oracle.com if you need additional information or have any
23	>	* questions.
24		*/
25
26		package java.util;
27	<	import java.util.*; // for javadoc (till 6280605 is fixed)
27	>
28	>	import java.util.function.Consumer;
29	>	import java.util.function.Predicate;
30	>	// OPENJDK import jdk.internal.access.SharedSecrets;
31
32		/**
33	<	* An unbounded priority {@linkplain Queue queue} based on a priority
34	<	* heap.  The elements of the priority queue are ordered according to
35	<	* their {@linkplain Comparable natural ordering}, or by a {@link
36	<	* Comparator} provided at queue construction time, depending on which
37	<	* constructor is used.  A priority queue does not permit
38	<	* <tt>null</tt> elements.  A priority queue relying on natural
39	<	* ordering also does not permit insertion of non-comparable objects
40	<	* (doing so may result in <tt>ClassCastException</tt>).
33	>	* An unbounded priority {@linkplain Queue queue} based on a priority heap.
34	>	* The elements of the priority queue are ordered according to their
35	>	* {@linkplain Comparable natural ordering}, or by a {@link Comparator}
36	>	* provided at queue construction time, depending on which constructor is
37	>	* used.  A priority queue does not permit {@code null} elements.
38	>	* A priority queue relying on natural ordering also does not permit
39	>	* insertion of non-comparable objects (doing so may result in
40	>	* {@code ClassCastException}).
41		*
42		* <p>The <em>head</em> of this queue is the <em>least</em> element
43		* with respect to the specified ordering.  If multiple elements are
44		* tied for least value, the head is one of those elements -- ties are
45	<	* broken arbitrarily.  The queue retrieval operations <tt>poll</tt>,
46	<	* <tt>remove</tt>, <tt>peek</tt>, and <tt>element</tt> access the
45	>	* broken arbitrarily.  The queue retrieval operations {@code poll},
46	>	* {@code remove}, {@code peek}, and {@code element} access the
47		* element at the head of the queue.
48		*
49		* <p>A priority queue is unbounded, but has an internal
#	Line 35 | Line 56 | import java.util.*; // for javadoc (till
56		* <p>This class and its iterator implement all of the
57		* <em>optional</em> methods of the {@link Collection} and {@link
58		* Iterator} interfaces.  The Iterator provided in method {@link
59	<	* #iterator()} is <em>not</em> guaranteed to traverse the elements of
59	>	* #iterator()} and the Spliterator provided in method {@link #spliterator()}
60	>	* are <em>not</em> guaranteed to traverse the elements of
61		* the priority queue in any particular order. If you need ordered
62	<	* traversal, consider using <tt>Arrays.sort(pq.toArray())</tt>.
62	>	* traversal, consider using {@code Arrays.sort(pq.toArray())}.
63		*
64	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
65	<	* Multiple threads should not access a <tt>PriorityQueue</tt>
66	<	* instance concurrently if any of the threads modifies the list
67	<	* structurally. Instead, use the thread-safe {@link
64	>	* <p><strong>Note that this implementation is not synchronized.</strong>
65	>	* Multiple threads should not access a {@code PriorityQueue}
66	>	* instance concurrently if any of the threads modifies the queue.
67	>	* Instead, use the thread-safe {@link
68		* java.util.concurrent.PriorityBlockingQueue} class.
69		*
70	<	* <p>Implementation note: this implementation provides O(log(n)) time
71	<	* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
72	<	* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
73	<	* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
74	<	* constant time for the retrieval methods (<tt>peek</tt>,
75	<	* <tt>element</tt>, and <tt>size</tt>).
70	>	* <p>Implementation note: this implementation provides
71	>	* O(log(n)) time for the enqueuing and dequeuing methods
72	>	* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
73	>	* linear time for the {@code remove(Object)} and {@code contains(Object)}
74	>	* methods; and constant time for the retrieval methods
75	>	* ({@code peek}, {@code element}, and {@code size}).
76		*
77		* <p>This class is a member of the
78	<	* <a href="{@docRoot}/../guide/collections/index.html">
78	>	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
79		* Java Collections Framework</a>.
80	+	*
81		* @since 1.5
82	<	* @version 1.8, 08/27/05
83	<	* @author Josh Bloch
61	<	* @param <E> the type of elements held in this collection
82	>	* @author Josh Bloch, Doug Lea
83	>	* @param <E> the type of elements held in this queue
84		*/
85	+	@SuppressWarnings("unchecked")
86		public class PriorityQueue<E> extends AbstractQueue<E>
87		implements java.io.Serializable {
88
#	Line 68 | Line 91 | public class PriorityQueue<E> extends Ab
91		private static final int DEFAULT_INITIAL_CAPACITY = 11;
92
93		/**
94	<	* Priority queue represented as a balanced binary heap: the two children
95	<	* of queue[n] are queue[2*n] and queue[2*n + 1].  The priority queue is
96	<	* ordered by comparator, or by the elements' natural ordering, if
97	<	* comparator is null:  For each node n in the heap and each descendant d
98	<	* of n, n <= d.
99	<	*
77	<	* The element with the lowest value is in queue[1], assuming the queue is
78	<	* nonempty.  (A one-based array is used in preference to the traditional
79	<	* zero-based array to simplify parent and child calculations.)
80	<	*
81	<	* queue.length must be >= 2, even if size == 0.
94	>	* Priority queue represented as a balanced binary heap: the two
95	>	* children of queue[n] are queue[2*n+1] and queue[2*(n+1)].  The
96	>	* priority queue is ordered by comparator, or by the elements'
97	>	* natural ordering, if comparator is null: For each node n in the
98	>	* heap and each descendant d of n, n <= d.  The element with the
99	>	* lowest value is in queue[0], assuming the queue is nonempty.
100		*/
101	<	private transient Object[] queue;
101	>	transient Object[] queue; // non-private to simplify nested class access
102
103		/**
104		* The number of elements in the priority queue.
105		*/
106	<	private int size = 0;
106	>	int size;
107
108		/**
109		* The comparator, or null if priority queue uses elements'
#	Line 97 | Line 115 | public class PriorityQueue<E> extends Ab
115		* The number of times this priority queue has been
116		* <i>structurally modified</i>.  See AbstractList for gory details.
117		*/
118	<	private transient int modCount = 0;
118	>	transient int modCount;     // non-private to simplify nested class access
119
120		/**
121	<	* Creates a <tt>PriorityQueue</tt> with the default initial
121	>	* Creates a {@code PriorityQueue} with the default initial
122		* capacity (11) that orders its elements according to their
123		* {@linkplain Comparable natural ordering}.
124		*/
#	Line 109 | Line 127 | public class PriorityQueue<E> extends Ab
127		}
128
129		/**
130	<	* Creates a <tt>PriorityQueue</tt> with the specified initial
130	>	* Creates a {@code PriorityQueue} with the specified initial
131		* capacity that orders its elements according to their
132		* {@linkplain Comparable natural ordering}.
133		*
134		* @param initialCapacity the initial capacity for this priority queue
135	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
136	<	* than 1
135	>	* @throws IllegalArgumentException if {@code initialCapacity} is less
136	>	*         than 1
137		*/
138		public PriorityQueue(int initialCapacity) {
139		this(initialCapacity, null);
140		}
141
142		/**
143	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
143	>	* Creates a {@code PriorityQueue} with the default initial capacity and
144	>	* whose elements are ordered according to the specified comparator.
145	>	*
146	>	* @param  comparator the comparator that will be used to order this
147	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
148	>	*         natural ordering} of the elements will be used.
149	>	* @since 1.8
150	>	*/
151	>	public PriorityQueue(Comparator<? super E> comparator) {
152	>	this(DEFAULT_INITIAL_CAPACITY, comparator);
153	>	}
154	>
155	>	/**
156	>	* Creates a {@code PriorityQueue} with the specified initial capacity
157		* that orders its elements according to the specified comparator.
158		*
159		* @param  initialCapacity the initial capacity for this priority queue
160	<	* @param  comparator the comparator that will be used to order
161	<	*         this priority queue.  If <tt>null</tt>, the <i>natural
162	<	*         ordering</i> of the elements will be used.
163	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is
160	>	* @param  comparator the comparator that will be used to order this
161	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
162	>	*         natural ordering} of the elements will be used.
163	>	* @throws IllegalArgumentException if {@code initialCapacity} is
164		*         less than 1
165		*/
166		public PriorityQueue(int initialCapacity,
167		Comparator<? super E> comparator) {
168	+	// Note: This restriction of at least one is not actually needed,
169	+	// but continues for 1.5 compatibility
170		if (initialCapacity < 1)
171		throw new IllegalArgumentException();
172	<	this.queue = new Object[initialCapacity + 1];
172	>	this.queue = new Object[initialCapacity];
173		this.comparator = comparator;
174		}
175
176		/**
177	<	* Common code to initialize underlying queue array across
178	<	* constructors below.
179	<	*/
180	<	private void initializeArray(Collection<? extends E> c) {
181	<	int sz = c.size();
182	<	int initialCapacity = (int)Math.min((sz * 110L) / 100,
150	<	Integer.MAX_VALUE - 1);
151	<	if (initialCapacity < 1)
152	<	initialCapacity = 1;
153	<
154	<	this.queue = new Object[initialCapacity + 1];
155	<	}
156	<
157	<	/**
158	<	* Initially fill elements of the queue array under the
159	<	* knowledge that it is sorted or is another PQ, in which
160	<	* case we can just place the elements in the order presented.
161	<	*/
162	<	private void fillFromSorted(Collection<? extends E> c) {
163	<	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) {
164	<	int k = ++size;
165	<	if (k >= queue.length)
166	<	grow(k);
167	<	queue[k] = i.next();
168	<	}
169	<	}
170	<
171	<	/**
172	<	* Initially fill elements of the queue array that is not to our knowledge
173	<	* sorted, so we must rearrange the elements to guarantee the heap
174	<	* invariant.
175	<	*/
176	<	private void fillFromUnsorted(Collection<? extends E> c) {
177	<	for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) {
178	<	int k = ++size;
179	<	if (k >= queue.length)
180	<	grow(k);
181	<	queue[k] = i.next();
182	<	}
183	<	heapify();
184	<	}
185	<
186	<	/**
187	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
188	<	* specified collection.  The priority queue has an initial
189	<	* capacity of 110% of the size of the specified collection or 1
190	<	* if the collection is empty.  If the specified collection is an
191	<	* instance of a {@link java.util.SortedSet} or is another
192	<	* <tt>PriorityQueue</tt>, the priority queue will be ordered
193	<	* according to the same ordering.  Otherwise, this priority queue
194	<	* will be ordered according to the natural ordering of its elements.
177	>	* Creates a {@code PriorityQueue} containing the elements in the
178	>	* specified collection.  If the specified collection is an instance of
179	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
180	>	* priority queue will be ordered according to the same ordering.
181	>	* Otherwise, this priority queue will be ordered according to the
182	>	* {@linkplain Comparable natural ordering} of its elements.
183		*
184		* @param  c the collection whose elements are to be placed
185		*         into this priority queue
#	Line 202 | Line 190 | public class PriorityQueue<E> extends Ab
190		*         of its elements are null
191		*/
192		public PriorityQueue(Collection<? extends E> c) {
193	<	initializeArray(c);
194	<	if (c instanceof SortedSet) {
195	<	SortedSet<? extends E> s = (SortedSet<? extends E>)c;
196	<	comparator = (Comparator<? super E>)s.comparator();
197	<	fillFromSorted(s);
198	<	} else if (c instanceof PriorityQueue) {
199	<	PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
200	<	comparator = (Comparator<? super E>)s.comparator();
201	<	fillFromSorted(s);
202	<	} else {
203	<	comparator = null;
204	<	fillFromUnsorted(c);
193	>	if (c instanceof SortedSet<?>) {
194	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
195	>	this.comparator = (Comparator<? super E>) ss.comparator();
196	>	initElementsFromCollection(ss);
197	>	}
198	>	else if (c instanceof PriorityQueue<?>) {
199	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
200	>	this.comparator = (Comparator<? super E>) pq.comparator();
201	>	initFromPriorityQueue(pq);
202	>	}
203	>	else {
204	>	this.comparator = null;
205	>	initFromCollection(c);
206		}
207		}
208
209		/**
210	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
211	<	* specified priority queue.  The priority queue has an initial
223	<	* capacity of 110% of the size of the specified priority queue or
224	<	* 1 if the priority queue is empty.  This priority queue will be
210	>	* Creates a {@code PriorityQueue} containing the elements in the
211	>	* specified priority queue.  This priority queue will be
212		* ordered according to the same ordering as the given priority
213		* queue.
214		*
215		* @param  c the priority queue whose elements are to be placed
216		*         into this priority queue
217	<	* @throws ClassCastException if elements of <tt>c</tt> cannot be
218	<	*         compared to one another according to <tt>c</tt>'s
217	>	* @throws ClassCastException if elements of {@code c} cannot be
218	>	*         compared to one another according to {@code c}'s
219		*         ordering
220		* @throws NullPointerException if the specified priority queue or any
221		*         of its elements are null
222		*/
223		public PriorityQueue(PriorityQueue<? extends E> c) {
224	<	initializeArray(c);
225	<	comparator = (Comparator<? super E>)c.comparator();
239	<	fillFromSorted(c);
224	>	this.comparator = (Comparator<? super E>) c.comparator();
225	>	initFromPriorityQueue(c);
226		}
227
228		/**
229	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
230	<	* specified sorted set.  The priority queue has an initial
245	<	* capacity of 110% of the size of the specified sorted set or 1
246	<	* if the sorted set is empty.  This priority queue will be ordered
229	>	* Creates a {@code PriorityQueue} containing the elements in the
230	>	* specified sorted set.   This priority queue will be ordered
231		* according to the same ordering as the given sorted set.
232		*
233		* @param  c the sorted set whose elements are to be placed
234	<	*         into this priority queue.
234	>	*         into this priority queue
235		* @throws ClassCastException if elements of the specified sorted
236		*         set cannot be compared to one another according to the
237		*         sorted set's ordering
#	Line 255 | Line 239 | public class PriorityQueue<E> extends Ab
239		*         of its elements are null
240		*/
241		public PriorityQueue(SortedSet<? extends E> c) {
242	<	initializeArray(c);
243	<	comparator = (Comparator<? super E>)c.comparator();
244	<	fillFromSorted(c);
242	>	this.comparator = (Comparator<? super E>) c.comparator();
243	>	initElementsFromCollection(c);
244	>	}
245	>
246	>	/** Ensures that queue[0] exists, helping peek() and poll(). */
247	>	private static Object[] ensureNonEmpty(Object[] es) {
248	>	return (es.length > 0) ? es : new Object[1];
249	>	}
250	>
251	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
252	>	if (c.getClass() == PriorityQueue.class) {
253	>	this.queue = ensureNonEmpty(c.toArray());
254	>	this.size = c.size();
255	>	} else {
256	>	initFromCollection(c);
257	>	}
258	>	}
259	>
260	>	private void initElementsFromCollection(Collection<? extends E> c) {
261	>	Object[] es = c.toArray();
262	>	int len = es.length;
263	>	// If c.toArray incorrectly doesn't return Object[], copy it.
264	>	if (es.getClass() != Object[].class)
265	>	es = Arrays.copyOf(es, len, Object[].class);
266	>	if (len == 1 || this.comparator != null)
267	>	for (Object e : es)
268	>	if (e == null)
269	>	throw new NullPointerException();
270	>	this.queue = ensureNonEmpty(es);
271	>	this.size = len;
272	>	}
273	>
274	>	/**
275	>	* Initializes queue array with elements from the given Collection.
276	>	*
277	>	* @param c the collection
278	>	*/
279	>	private void initFromCollection(Collection<? extends E> c) {
280	>	initElementsFromCollection(c);
281	>	heapify();
282		}
283
284		/**
285	<	* Resize array, if necessary, to be able to hold given index.
285	>	* The maximum size of array to allocate.
286	>	* Some VMs reserve some header words in an array.
287	>	* Attempts to allocate larger arrays may result in
288	>	* OutOfMemoryError: Requested array size exceeds VM limit
289		*/
290	<	private void grow(int index) {
291	<	int newlen = queue.length;
292	<	if (index < newlen) // don't need to grow
293	<	return;
294	<	if (index == Integer.MAX_VALUE)
290	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
291	>
292	>	/**
293	>	* Increases the capacity of the array.
294	>	*
295	>	* @param minCapacity the desired minimum capacity
296	>	*/
297	>	private void grow(int minCapacity) {
298	>	int oldCapacity = queue.length;
299	>	// Double size if small; else grow by 50%
300	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
301	>	(oldCapacity + 2) :
302	>	(oldCapacity >> 1));
303	>	// overflow-conscious code
304	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
305	>	newCapacity = hugeCapacity(minCapacity);
306	>	queue = Arrays.copyOf(queue, newCapacity);
307	>	}
308	>
309	>	private static int hugeCapacity(int minCapacity) {
310	>	if (minCapacity < 0) // overflow
311		throw new OutOfMemoryError();
312	<	while (newlen <= index) {
313	<	if (newlen >= Integer.MAX_VALUE / 2)  // avoid overflow
314	<	newlen = Integer.MAX_VALUE;
275	<	else
276	<	newlen <<= 1;
277	<	}
278	<	queue = Arrays.copyOf(queue, newlen);
312	>	return (minCapacity > MAX_ARRAY_SIZE) ?
313	>	Integer.MAX_VALUE :
314	>	MAX_ARRAY_SIZE;
315		}
316
317		/**
318		* Inserts the specified element into this priority queue.
319		*
320	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
320	>	* @return {@code true} (as specified by {@link Collection#add})
321		* @throws ClassCastException if the specified element cannot be
322		*         compared with elements currently in this priority queue
323		*         according to the priority queue's ordering
#	Line 294 | Line 330 | public class PriorityQueue<E> extends Ab
330		/**
331		* Inserts the specified element into this priority queue.
332		*
333	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
333	>	* @return {@code true} (as specified by {@link Queue#offer})
334		* @throws ClassCastException if the specified element cannot be
335		*         compared with elements currently in this priority queue
336		*         according to the priority queue's ordering
#	Line 304 | Line 340 | public class PriorityQueue<E> extends Ab
340		if (e == null)
341		throw new NullPointerException();
342		modCount++;
343	<	++size;
344	<
345	<	// Grow backing store if necessary
346	<	if (size >= queue.length)
347	<	grow(size);
312	<
313	<	queue[size] = e;
314	<	fixUp(size);
343	>	int i = size;
344	>	if (i >= queue.length)
345	>	grow(i + 1);
346	>	siftUp(i, e);
347	>	size = i + 1;
348		return true;
349		}
350
351		public E peek() {
352	<	if (size == 0)
320	<	return null;
321	<	return (E) queue[1];
352	>	return (E) queue[0];
353		}
354
355		private int indexOf(Object o) {
356	<	if (o == null)
357	<	return -1;
358	<	for (int i = 1; i <= size; i++)
359	<	if (o.equals(queue[i]))
360	<	return i;
356	>	if (o != null) {
357	>	final Object[] es = queue;
358	>	for (int i = 0, n = size; i < n; i++)
359	>	if (o.equals(es[i]))
360	>	return i;
361	>	}
362		return -1;
363		}
364
365		/**
366		* Removes a single instance of the specified element from this queue,
367	<	* if it is present.  More formally, removes an element <tt>e</tt> such
368	<	* that <tt>o.equals(e)</tt>, if this queue contains one or more such
369	<	* elements.  Returns true if this queue contained the specified element
370	<	* (or equivalently, if this queue changed as a result of the call).
367	>	* if it is present.  More formally, removes an element {@code e} such
368	>	* that {@code o.equals(e)}, if this queue contains one or more such
369	>	* elements.  Returns {@code true} if and only if this queue contained
370	>	* the specified element (or equivalently, if this queue changed as a
371	>	* result of the call).
372		*
373		* @param o element to be removed from this queue, if present
374	<	* @return <tt>true</tt> if this queue changed as a result of the call
374	>	* @return {@code true} if this queue changed as a result of the call
375		*/
376		public boolean remove(Object o) {
377	<	int i = indexOf(o);
378	<	if (i == -1)
379	<	return false;
380	<	else {
381	<	removeAt(i);
382	<	return true;
383	<	}
377	>	int i = indexOf(o);
378	>	if (i == -1)
379	>	return false;
380	>	else {
381	>	removeAt(i);
382	>	return true;
383	>	}
384		}
385
386		/**
387	<	* Returns <tt>true</tt> if this queue contains the specified element.
388	<	* More formally, returns <tt>true</tt> if and only if this queue contains
389	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
387	>	* Identity-based version for use in Itr.remove.
388	>	*
389	>	* @param o element to be removed from this queue, if present
390	>	*/
391	>	void removeEq(Object o) {
392	>	final Object[] es = queue;
393	>	for (int i = 0, n = size; i < n; i++) {
394	>	if (o == es[i]) {
395	>	removeAt(i);
396	>	break;
397	>	}
398	>	}
399	>	}
400	>
401	>	/**
402	>	* Returns {@code true} if this queue contains the specified element.
403	>	* More formally, returns {@code true} if and only if this queue contains
404	>	* at least one element {@code e} such that {@code o.equals(e)}.
405		*
406		* @param o object to be checked for containment in this queue
407	<	* @return <tt>true</tt> if this queue contains the specified element
407	>	* @return {@code true} if this queue contains the specified element
408		*/
409		public boolean contains(Object o) {
410	<	return indexOf(o) != -1;
410	>	return indexOf(o) >= 0;
411		}
412
413		/**
414	<	* Returns an array containing all of the elements in this queue,
414	>	* Returns an array containing all of the elements in this queue.
415		* The elements are in no particular order.
416		*
417		* <p>The returned array will be "safe" in that no references to it are
418	<	* maintained by this list.  (In other words, this method must allocate
418	>	* maintained by this queue.  (In other words, this method must allocate
419		* a new array).  The caller is thus free to modify the returned array.
420		*
421	<	* @return an array containing all of the elements in this queue.
421	>	* <p>This method acts as bridge between array-based and collection-based
422	>	* APIs.
423	>	*
424	>	* @return an array containing all of the elements in this queue
425		*/
426		public Object[] toArray() {
427	<	return Arrays.copyOfRange(queue, 1, size+1);
427	>	return Arrays.copyOf(queue, size);
428		}
429
430		/**
431	<	* Returns an array containing all of the elements in this queue.
432	<	* The elements are in no particular order.  The runtime type of
433	<	* the returned array is that of the specified array.  If the queue
434	<	* fits in the specified array, it is returned therein.
435	<	* Otherwise, a new array is allocated with the runtime type of
436	<	* the specified array and the size of this queue.
431	>	* Returns an array containing all of the elements in this queue; the
432	>	* runtime type of the returned array is that of the specified array.
433	>	* The returned array elements are in no particular order.
434	>	* If the queue fits in the specified array, it is returned therein.
435	>	* Otherwise, a new array is allocated with the runtime type of the
436	>	* specified array and the size of this queue.
437		*
438		* <p>If the queue fits in the specified array with room to spare
439		* (i.e., the array has more elements than the queue), the element in
440		* the array immediately following the end of the collection is set to
441	<	* <tt>null</tt>.  (This is useful in determining the length of the
442	<	* queue <i>only</i> if the caller knows that the queue does not contain
443	<	* any null elements.)
441	>	* {@code null}.
442	>	*
443	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
444	>	* array-based and collection-based APIs.  Further, this method allows
445	>	* precise control over the runtime type of the output array, and may,
446	>	* under certain circumstances, be used to save allocation costs.
447	>	*
448	>	* <p>Suppose {@code x} is a queue known to contain only strings.
449	>	* The following code can be used to dump the queue into a newly
450	>	* allocated array of {@code String}:
451	>	*
452	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
453	>	*
454	>	* Note that {@code toArray(new Object[0])} is identical in function to
455	>	* {@code toArray()}.
456		*
457		* @param a the array into which the elements of the queue are to
458		*          be stored, if it is big enough; otherwise, a new array of the
459		*          same runtime type is allocated for this purpose.
460	<	* @return an array containing the elements of the queue
460	>	* @return an array containing all of the elements in this queue
461		* @throws ArrayStoreException if the runtime type of the specified array
462		*         is not a supertype of the runtime type of every element in
463		*         this queue
464		* @throws NullPointerException if the specified array is null
465		*/
466		public <T> T[] toArray(T[] a) {
467	+	final int size = this.size;
468		if (a.length < size)
469		// Make a new array of a's runtime type, but my contents:
470	<	return (T[]) Arrays.copyOfRange(queue, 1, size+1, a.getClass());
471	<	System.arraycopy(queue, 1, a, 0, size);
470	>	return (T[]) Arrays.copyOf(queue, size, a.getClass());
471	>	System.arraycopy(queue, 0, a, 0, size);
472		if (a.length > size)
473		a[size] = null;
474		return a;
#	Line 420 | Line 484 | public class PriorityQueue<E> extends Ab
484		return new Itr();
485		}
486
487	<	private class Itr implements Iterator<E> {
424	<
487	>	private final class Itr implements Iterator<E> {
488		/**
489		* Index (into queue array) of element to be returned by
490		* subsequent call to next.
491		*/
492	<	private int cursor = 1;
492	>	private int cursor;
493
494		/**
495		* Index of element returned by most recent call to next,
496		* unless that element came from the forgetMeNot list.
497	<	* Reset to 0 if element is deleted by a call to remove.
435	<	*/
436	<	private int lastRet = 0;
437	<
438	<	/**
439	<	* The modCount value that the iterator believes that the backing
440	<	* List should have.  If this expectation is violated, the iterator
441	<	* has detected concurrent modification.
497	>	* Set to -1 if element is deleted by a call to remove.
498		*/
499	<	private int expectedModCount = modCount;
499	>	private int lastRet = -1;
500
501		/**
502	<	* A list of elements that were moved from the unvisited portion of
502	>	* A queue of elements that were moved from the unvisited portion of
503		* the heap into the visited portion as a result of "unlucky" element
504		* removals during the iteration.  (Unlucky element removals are those
505	<	* that require a fixup instead of a fixdown.)  We must visit all of
505	>	* that require a siftup instead of a siftdown.)  We must visit all of
506		* the elements in this list to complete the iteration.  We do this
507		* after we've completed the "normal" iteration.
508		*
509		* We expect that most iterations, even those involving removals,
510	<	* will not use need to store elements in this field.
510	>	* will not need to store elements in this field.
511		*/
512	<	private ArrayList<E> forgetMeNot = null;
512	>	private ArrayDeque<E> forgetMeNot;
513
514		/**
515		* Element returned by the most recent call to next iff that
516		* element was drawn from the forgetMeNot list.
517		*/
518	<	private Object lastRetElt = null;
518	>	private E lastRetElt;
519	>
520	>	/**
521	>	* The modCount value that the iterator believes that the backing
522	>	* Queue should have.  If this expectation is violated, the iterator
523	>	* has detected concurrent modification.
524	>	*/
525	>	private int expectedModCount = modCount;
526	>
527	>	Itr() {}                        // prevent access constructor creation
528
529		public boolean hasNext() {
530	<	return cursor <= size || forgetMeNot != null;
530	>	return cursor < size ||
531	>	(forgetMeNot != null && !forgetMeNot.isEmpty());
532		}
533
534		public E next() {
535	<	checkForComodification();
536	<	E result;
537	<	if (cursor <= size) {
538	<	result = (E) queue[cursor];
539	<	lastRet = cursor++;
540	<	}
541	<	else if (forgetMeNot == null)
542	<	throw new NoSuchElementException();
543	<	else {
478	<	int remaining = forgetMeNot.size();
479	<	result = forgetMeNot.remove(remaining - 1);
480	<	if (remaining == 1)
481	<	forgetMeNot = null;
482	<	lastRet = 0;
483	<	lastRetElt = result;
535	>	if (expectedModCount != modCount)
536	>	throw new ConcurrentModificationException();
537	>	if (cursor < size)
538	>	return (E) queue[lastRet = cursor++];
539	>	if (forgetMeNot != null) {
540	>	lastRet = -1;
541	>	lastRetElt = forgetMeNot.poll();
542	>	if (lastRetElt != null)
543	>	return lastRetElt;
544		}
545	<	return result;
545	>	throw new NoSuchElementException();
546		}
547
548		public void remove() {
549	<	checkForComodification();
550	<
551	<	if (lastRet != 0) {
549	>	if (expectedModCount != modCount)
550	>	throw new ConcurrentModificationException();
551	>	if (lastRet != -1) {
552		E moved = PriorityQueue.this.removeAt(lastRet);
553	<	lastRet = 0;
554	<	if (moved == null) {
553	>	lastRet = -1;
554	>	if (moved == null)
555		cursor--;
556	<	} else {
556	>	else {
557		if (forgetMeNot == null)
558	<	forgetMeNot = new ArrayList<E>();
558	>	forgetMeNot = new ArrayDeque<>();
559		forgetMeNot.add(moved);
560		}
561		} else if (lastRetElt != null) {
562	<	PriorityQueue.this.remove(lastRetElt);
562	>	PriorityQueue.this.removeEq(lastRetElt);
563		lastRetElt = null;
564		} else {
565		throw new IllegalStateException();
566		}
507	–
567		expectedModCount = modCount;
568		}
510	–
511	–	final void checkForComodification() {
512	–	if (modCount != expectedModCount)
513	–	throw new ConcurrentModificationException();
514	–	}
569		}
570
571		public int size() {
#	Line 524 | Line 578 | public class PriorityQueue<E> extends Ab
578		*/
579		public void clear() {
580		modCount++;
581	<
582	<	// Null out element references to prevent memory leak
583	<	for (int i=1; i<=size; i++)
530	<	queue[i] = null;
531	<
581	>	final Object[] es = queue;
582	>	for (int i = 0, n = size; i < n; i++)
583	>	es[i] = null;
584		size = 0;
585		}
586
587		public E poll() {
588	<	if (size == 0)
589	<	return null;
538	<	modCount++;
539	<
540	<	E result = (E) queue[1];
541	<	queue[1] = queue[size];
542	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
543	<	if (size > 1)
544	<	fixDown(1);
588	>	final Object[] es;
589	>	final E result;
590
591	+	if ((result = (E) ((es = queue)[0])) != null) {
592	+	modCount++;
593	+	final int n;
594	+	final E x = (E) es[(n = --size)];
595	+	es[n] = null;
596	+	if (n > 0) {
597	+	final Comparator<? super E> cmp;
598	+	if ((cmp = comparator) == null)
599	+	siftDownComparable(0, x, es, n);
600	+	else
601	+	siftDownUsingComparator(0, x, es, n, cmp);
602	+	}
603	+	}
604		return result;
605		}
606
607		/**
608	<	* Removes and returns the ith element from queue.  (Recall that queue
551	<	* is one-based, so 1 <= i <= size.)
608	>	* Removes the ith element from queue.
609		*
610	<	* Normally this method leaves the elements at positions from 1 up to i-1,
611	<	* inclusive, untouched.  Under these circumstances, it returns null.
612	<	* Occasionally, in order to maintain the heap invariant, it must move
613	<	* the last element of the list to some index in the range [2, i-1],
614	<	* and move the element previously at position (i/2) to position i.
615	<	* Under these circumstances, this method returns the element that was
616	<	* previously at the end of the list and is now at some position between
617	<	* 2 and i-1 inclusive.
618	<	*/
619	<	private E removeAt(int i) {
620	<	assert i > 0 && i <= size;
610	>	* Normally this method leaves the elements at up to i-1,
611	>	* inclusive, untouched.  Under these circumstances, it returns
612	>	* null.  Occasionally, in order to maintain the heap invariant,
613	>	* it must swap a later element of the list with one earlier than
614	>	* i.  Under these circumstances, this method returns the element
615	>	* that was previously at the end of the list and is now at some
616	>	* position before i. This fact is used by iterator.remove so as to
617	>	* avoid missing traversing elements.
618	>	*/
619	>	E removeAt(int i) {
620	>	// assert i >= 0 && i < size;
621	>	final Object[] es = queue;
622		modCount++;
623	<
624	<	E moved = (E) queue[size];
625	<	queue[i] = moved;
626	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
627	<	if (i <= size) {
628	<	fixDown(i);
629	<	if (queue[i] == moved) {
630	<	fixUp(i);
631	<	if (queue[i] != moved)
623	>	int s = --size;
624	>	if (s == i) // removed last element
625	>	es[i] = null;
626	>	else {
627	>	E moved = (E) es[s];
628	>	es[s] = null;
629	>	siftDown(i, moved);
630	>	if (es[i] == moved) {
631	>	siftUp(i, moved);
632	>	if (es[i] != moved)
633		return moved;
634		}
635		}
#	Line 578 | Line 637 | public class PriorityQueue<E> extends Ab
637		}
638
639		/**
640	<	* Establishes the heap invariant (described above) assuming the heap
641	<	* satisfies the invariant except possibly for the leaf-node indexed by k
642	<	* (which may have a nextExecutionTime less than its parent's).
643	<	*
644	<	* This method functions by "promoting" queue[k] up the hierarchy
645	<	* (by swapping it with its parent) repeatedly until queue[k]
646	<	* is greater than or equal to its parent.
647	<	*/
648	<	private void fixUp(int k) {
649	<	if (comparator == null) {
650	<	while (k > 1) {
651	<	int j = k >> 1;
652	<	if (((Comparable<? super E>)queue[j]).compareTo((E)queue[k]) <= 0)
653	<	break;
654	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
655	<	k = j;
656	<	}
657	<	} else {
658	<	while (k > 1) {
659	<	int j = k >>> 1;
660	<	if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
661	<	break;
662	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
663	<	k = j;
664	<	}
665	<	}
666	<	}
667	<
668	<	/**
669	<	* Establishes the heap invariant (described above) in the subtree
670	<	* rooted at k, which is assumed to satisfy the heap invariant except
671	<	* possibly for node k itself (which may be greater than its children).
672	<	*
673	<	* This method functions by "demoting" queue[k] down the hierarchy
674	<	* (by swapping it with its smaller child) repeatedly until queue[k]
675	<	* is less than or equal to its children.
676	<	*/
677	<	private void fixDown(int k) {
678	<	int j;
679	<	if (comparator == null) {
680	<	while ((j = k << 1) <= size && (j > 0)) {
681	<	if (j<size &&
682	<	((Comparable<? super E>)queue[j]).compareTo((E)queue[j+1]) > 0)
683	<	j++; // j indexes smallest kid
684	<
685	<	if (((Comparable<? super E>)queue[k]).compareTo((E)queue[j]) <= 0)
686	<	break;
687	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
688	<	k = j;
689	<	}
690	<	} else {
691	<	while ((j = k << 1) <= size && (j > 0)) {
692	<	if (j<size &&
693	<	comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
694	<	j++; // j indexes smallest kid
695	<	if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
696	<	break;
697	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
698	<	k = j;
699	<	}
640	>	* Inserts item x at position k, maintaining heap invariant by
641	>	* promoting x up the tree until it is greater than or equal to
642	>	* its parent, or is the root.
643	>	*
644	>	* To simplify and speed up coercions and comparisons, the
645	>	* Comparable and Comparator versions are separated into different
646	>	* methods that are otherwise identical. (Similarly for siftDown.)
647	>	*
648	>	* @param k the position to fill
649	>	* @param x the item to insert
650	>	*/
651	>	private void siftUp(int k, E x) {
652	>	if (comparator != null)
653	>	siftUpUsingComparator(k, x, queue, comparator);
654	>	else
655	>	siftUpComparable(k, x, queue);
656	>	}
657	>
658	>	private static <T> void siftUpComparable(int k, T x, Object[] es) {
659	>	Comparable<? super T> key = (Comparable<? super T>) x;
660	>	while (k > 0) {
661	>	int parent = (k - 1) >>> 1;
662	>	Object e = es[parent];
663	>	if (key.compareTo((T) e) >= 0)
664	>	break;
665	>	es[k] = e;
666	>	k = parent;
667	>	}
668	>	es[k] = key;
669	>	}
670	>
671	>	private static <T> void siftUpUsingComparator(
672	>	int k, T x, Object[] es, Comparator<? super T> cmp) {
673	>	while (k > 0) {
674	>	int parent = (k - 1) >>> 1;
675	>	Object e = es[parent];
676	>	if (cmp.compare(x, (T) e) >= 0)
677	>	break;
678	>	es[k] = e;
679	>	k = parent;
680	>	}
681	>	es[k] = x;
682	>	}
683	>
684	>	/**
685	>	* Inserts item x at position k, maintaining heap invariant by
686	>	* demoting x down the tree repeatedly until it is less than or
687	>	* equal to its children or is a leaf.
688	>	*
689	>	* @param k the position to fill
690	>	* @param x the item to insert
691	>	*/
692	>	private void siftDown(int k, E x) {
693	>	if (comparator != null)
694	>	siftDownUsingComparator(k, x, queue, size, comparator);
695	>	else
696	>	siftDownComparable(k, x, queue, size);
697	>	}
698	>
699	>	private static <T> void siftDownComparable(int k, T x, Object[] es, int n) {
700	>	// assert n > 0;
701	>	Comparable<? super T> key = (Comparable<? super T>)x;
702	>	int half = n >>> 1;           // loop while a non-leaf
703	>	while (k < half) {
704	>	int child = (k << 1) + 1; // assume left child is least
705	>	Object c = es[child];
706	>	int right = child + 1;
707	>	if (right < n &&
708	>	((Comparable<? super T>) c).compareTo((T) es[right]) > 0)
709	>	c = es[child = right];
710	>	if (key.compareTo((T) c) <= 0)
711	>	break;
712	>	es[k] = c;
713	>	k = child;
714	>	}
715	>	es[k] = key;
716	>	}
717	>
718	>	private static <T> void siftDownUsingComparator(
719	>	int k, T x, Object[] es, int n, Comparator<? super T> cmp) {
720	>	// assert n > 0;
721	>	int half = n >>> 1;
722	>	while (k < half) {
723	>	int child = (k << 1) + 1;
724	>	Object c = es[child];
725	>	int right = child + 1;
726	>	if (right < n && cmp.compare((T) c, (T) es[right]) > 0)
727	>	c = es[child = right];
728	>	if (cmp.compare(x, (T) c) <= 0)
729	>	break;
730	>	es[k] = c;
731	>	k = child;
732		}
733	+	es[k] = x;
734		}
735
736		/**
737		* Establishes the heap invariant (described above) in the entire tree,
738		* assuming nothing about the order of the elements prior to the call.
739	+	* This classic algorithm due to Floyd (1964) is known to be O(size).
740		*/
741		private void heapify() {
742	<	for (int i = size/2; i >= 1; i--)
743	<	fixDown(i);
742	>	final Object[] es = queue;
743	>	int n = size, i = (n >>> 1) - 1;
744	>	final Comparator<? super E> cmp;
745	>	if ((cmp = comparator) == null)
746	>	for (; i >= 0; i--)
747	>	siftDownComparable(i, (E) es[i], es, n);
748	>	else
749	>	for (; i >= 0; i--)
750	>	siftDownUsingComparator(i, (E) es[i], es, n, cmp);
751		}
752
753		/**
754		* Returns the comparator used to order the elements in this
755	<	* queue, or <tt>null</tt> if this queue is sorted according to
755	>	* queue, or {@code null} if this queue is sorted according to
756		* the {@linkplain Comparable natural ordering} of its elements.
757		*
758		* @return the comparator used to order this queue, or
759	<	*         <tt>null</tt> if this queue is sorted according to the
760	<	*         natural ordering of its elements.
759	>	*         {@code null} if this queue is sorted according to the
760	>	*         natural ordering of its elements
761		*/
762		public Comparator<? super E> comparator() {
763		return comparator;
764		}
765
766		/**
767	<	* Save the state of the instance to a stream (that
668	<	* is, serialize it).
767	>	* Saves this queue to a stream (that is, serializes it).
768		*
670	–	* @serialData The length of the array backing the instance is
671	–	* emitted (int), followed by all of its elements (each an
672	–	* <tt>Object</tt>) in the proper order.
769		* @param s the stream
770	+	* @throws java.io.IOException if an I/O error occurs
771	+	* @serialData The length of the array backing the instance is
772	+	*             emitted (int), followed by all of its elements
773	+	*             (each an {@code Object}) in the proper order.
774		*/
775		private void writeObject(java.io.ObjectOutputStream s)
776	<	throws java.io.IOException{
776	>	throws java.io.IOException {
777		// Write out element count, and any hidden stuff
778		s.defaultWriteObject();
779
780	<	// Write out array length
781	<	s.writeInt(queue.length);
780	>	// Write out array length, for compatibility with 1.5 version
781	>	s.writeInt(Math.max(2, size + 1));
782
783	<	// Write out all elements in the proper order.
784	<	for (int i=1; i<=size; i++)
785	<	s.writeObject(queue[i]);
783	>	// Write out all elements in the "proper order".
784	>	final Object[] es = queue;
785	>	for (int i = 0, n = size; i < n; i++)
786	>	s.writeObject(es[i]);
787		}
788
789		/**
790	<	* Reconstitute the <tt>PriorityQueue</tt> instance from a stream
791	<	* (that is, deserialize it).
790	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
791	>	* (that is, deserializes it).
792	>	*
793		* @param s the stream
794	+	* @throws ClassNotFoundException if the class of a serialized object
795	+	*         could not be found
796	+	* @throws java.io.IOException if an I/O error occurs
797		*/
798		private void readObject(java.io.ObjectInputStream s)
799		throws java.io.IOException, ClassNotFoundException {
800		// Read in size, and any hidden stuff
801		s.defaultReadObject();
802
803	<	// Read in array length and allocate array
804	<	int arrayLength = s.readInt();
805	<	queue = new Object[arrayLength];
806	<
807	<	// Read in all elements in the proper order.
808	<	for (int i=1; i<=size; i++)
809	<	queue[i] = (E) s.readObject();
803	>	// Read in (and discard) array length
804	>	s.readInt();
805	>
806	>	jsr166.Platform.checkArray(s, Object[].class, size);
807	>	final Object[] es = queue = new Object[Math.max(size, 1)];
808	>
809	>	// Read in all elements.
810	>	for (int i = 0, n = size; i < n; i++)
811	>	es[i] = s.readObject();
812	>
813	>	// Elements are guaranteed to be in "proper order", but the
814	>	// spec has never explained what that might be.
815	>	heapify();
816	>	}
817	>
818	>	/**
819	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
820	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
821	>	* queue. The spliterator does not traverse elements in any particular order
822	>	* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported).
823	>	*
824	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
825	>	* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}.
826	>	* Overriding implementations should document the reporting of additional
827	>	* characteristic values.
828	>	*
829	>	* @return a {@code Spliterator} over the elements in this queue
830	>	* @since 1.8
831	>	*/
832	>	public final Spliterator<E> spliterator() {
833	>	return new PriorityQueueSpliterator(0, -1, 0);
834	>	}
835	>
836	>	final class PriorityQueueSpliterator implements Spliterator<E> {
837	>	private int index;            // current index, modified on advance/split
838	>	private int fence;            // -1 until first use
839	>	private int expectedModCount; // initialized when fence set
840	>
841	>	/** Creates new spliterator covering the given range. */
842	>	PriorityQueueSpliterator(int origin, int fence, int expectedModCount) {
843	>	this.index = origin;
844	>	this.fence = fence;
845	>	this.expectedModCount = expectedModCount;
846	>	}
847	>
848	>	private int getFence() { // initialize fence to size on first use
849	>	int hi;
850	>	if ((hi = fence) < 0) {
851	>	expectedModCount = modCount;
852	>	hi = fence = size;
853	>	}
854	>	return hi;
855	>	}
856	>
857	>	public PriorityQueueSpliterator trySplit() {
858	>	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
859	>	return (lo >= mid) ? null :
860	>	new PriorityQueueSpliterator(lo, index = mid, expectedModCount);
861	>	}
862	>
863	>	public void forEachRemaining(Consumer<? super E> action) {
864	>	if (action == null)
865	>	throw new NullPointerException();
866	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
867	>	final Object[] es = queue;
868	>	int i, hi; E e;
869	>	for (i = index, index = hi = fence; i < hi; i++) {
870	>	if ((e = (E) es[i]) == null)
871	>	break;      // must be CME
872	>	action.accept(e);
873	>	}
874	>	if (modCount != expectedModCount)
875	>	throw new ConcurrentModificationException();
876	>	}
877	>
878	>	public boolean tryAdvance(Consumer<? super E> action) {
879	>	if (action == null)
880	>	throw new NullPointerException();
881	>	if (fence < 0) { fence = size; expectedModCount = modCount; }
882	>	int i;
883	>	if ((i = index) < fence) {
884	>	index = i + 1;
885	>	E e;
886	>	if ((e = (E) queue[i]) == null
887	>	|| modCount != expectedModCount)
888	>	throw new ConcurrentModificationException();
889	>	action.accept(e);
890	>	return true;
891	>	}
892	>	return false;
893	>	}
894	>
895	>	public long estimateSize() {
896	>	return getFence() - index;
897	>	}
898	>
899	>	public int characteristics() {
900	>	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
901	>	}
902	>	}
903	>
904	>	/**
905	>	* @throws NullPointerException {@inheritDoc}
906	>	*/
907	>	public boolean removeIf(Predicate<? super E> filter) {
908	>	Objects.requireNonNull(filter);
909	>	return bulkRemove(filter);
910		}
911
912	+	/**
913	+	* @throws NullPointerException {@inheritDoc}
914	+	*/
915	+	public boolean removeAll(Collection<?> c) {
916	+	Objects.requireNonNull(c);
917	+	return bulkRemove(e -> c.contains(e));
918	+	}
919	+
920	+	/**
921	+	* @throws NullPointerException {@inheritDoc}
922	+	*/
923	+	public boolean retainAll(Collection<?> c) {
924	+	Objects.requireNonNull(c);
925	+	return bulkRemove(e -> !c.contains(e));
926	+	}
927	+
928	+	// A tiny bit set implementation
929	+
930	+	private static long[] nBits(int n) {
931	+	return new long[((n - 1) >> 6) + 1];
932	+	}
933	+	private static void setBit(long[] bits, int i) {
934	+	bits[i >> 6] |= 1L << i;
935	+	}
936	+	private static boolean isClear(long[] bits, int i) {
937	+	return (bits[i >> 6] & (1L << i)) == 0;
938	+	}
939	+
940	+	/** Implementation of bulk remove methods. */
941	+	private boolean bulkRemove(Predicate<? super E> filter) {
942	+	final int expectedModCount = ++modCount;
943	+	final Object[] es = queue;
944	+	final int end = size;
945	+	int i;
946	+	// Optimize for initial run of survivors
947	+	for (i = 0; i < end && !filter.test((E) es[i]); i++)
948	+	;
949	+	if (i >= end) {
950	+	if (modCount != expectedModCount)
951	+	throw new ConcurrentModificationException();
952	+	return false;
953	+	}
954	+	// Tolerate predicates that reentrantly access the collection for
955	+	// read (but writers still get CME), so traverse once to find
956	+	// elements to delete, a second pass to physically expunge.
957	+	final int beg = i;
958	+	final long[] deathRow = nBits(end - beg);
959	+	deathRow[0] = 1L;   // set bit 0
960	+	for (i = beg + 1; i < end; i++)
961	+	if (filter.test((E) es[i]))
962	+	setBit(deathRow, i - beg);
963	+	if (modCount != expectedModCount)
964	+	throw new ConcurrentModificationException();
965	+	int w = beg;
966	+	for (i = beg; i < end; i++)
967	+	if (isClear(deathRow, i - beg))
968	+	es[w++] = es[i];
969	+	for (i = size = w; i < end; i++)
970	+	es[i] = null;
971	+	heapify();
972	+	return true;
973	+	}
974	+
975	+	/**
976	+	* @throws NullPointerException {@inheritDoc}
977	+	*/
978	+	public void forEach(Consumer<? super E> action) {
979	+	Objects.requireNonNull(action);
980	+	final int expectedModCount = modCount;
981	+	final Object[] es = queue;
982	+	for (int i = 0, n = size; i < n; i++)
983	+	action.accept((E) es[i]);
984	+	if (expectedModCount != modCount)
985	+	throw new ConcurrentModificationException();
986	+	}
987		}

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