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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 1.100 by jsr166, Fri Aug 29 21:42:37 2014 UTC

#	Line 1 | Line 1
1		/*
2	<	* @(#)PriorityQueue.java       1.8 05/08/27
2	>	* Copyright (c) 2003, 2012, 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	>	import java.util.function.Consumer;
28	>	import java.util.stream.Stream;
29
30		/**
31	<	* An unbounded priority {@linkplain Queue queue} based on a priority
32	<	* heap.  The elements of the priority queue are ordered according to
33	<	* their {@linkplain Comparable natural ordering}, or by a {@link
34	<	* Comparator} provided at queue construction time, depending on which
35	<	* constructor is used.  A priority queue does not permit
36	<	* <tt>null</tt> elements.  A priority queue relying on natural
37	<	* ordering also does not permit insertion of non-comparable objects
38	<	* (doing so may result in <tt>ClassCastException</tt>).
31	>	* An unbounded priority {@linkplain Queue queue} based on a priority heap.
32	>	* The elements of the priority queue are ordered according to their
33	>	* {@linkplain Comparable natural ordering}, or by a {@link Comparator}
34	>	* provided at queue construction time, depending on which constructor is
35	>	* used.  A priority queue does not permit {@code null} elements.
36	>	* A priority queue relying on natural ordering also does not permit
37	>	* insertion of non-comparable objects (doing so may result in
38	>	* {@code ClassCastException}).
39		*
40		* <p>The <em>head</em> of this queue is the <em>least</em> element
41		* with respect to the specified ordering.  If multiple elements are
42		* tied for least value, the head is one of those elements -- ties are
43	<	* broken arbitrarily.  The queue retrieval operations <tt>poll</tt>,
44	<	* <tt>remove</tt>, <tt>peek</tt>, and <tt>element</tt> access the
43	>	* broken arbitrarily.  The queue retrieval operations {@code poll},
44	>	* {@code remove}, {@code peek}, and {@code element} access the
45		* element at the head of the queue.
46		*
47		* <p>A priority queue is unbounded, but has an internal
#	Line 37 | Line 56 | import java.util.*; // for javadoc (till
56		* Iterator} interfaces.  The Iterator provided in method {@link
57		* #iterator()} is <em>not</em> guaranteed to traverse the elements of
58		* the priority queue in any particular order. If you need ordered
59	<	* traversal, consider using <tt>Arrays.sort(pq.toArray())</tt>.
59	>	* traversal, consider using {@code Arrays.sort(pq.toArray())}.
60		*
61	<	* <p> <strong>Note that this implementation is not synchronized.</strong>
62	<	* Multiple threads should not access a <tt>PriorityQueue</tt>
63	<	* instance concurrently if any of the threads modifies the list
64	<	* structurally. Instead, use the thread-safe {@link
61	>	* <p><strong>Note that this implementation is not synchronized.</strong>
62	>	* Multiple threads should not access a {@code PriorityQueue}
63	>	* instance concurrently if any of the threads modifies the queue.
64	>	* Instead, use the thread-safe {@link
65		* java.util.concurrent.PriorityBlockingQueue} class.
66		*
67	<	* <p>Implementation note: this implementation provides O(log(n)) time
68	<	* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>,
69	<	* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the
70	<	* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and
71	<	* constant time for the retrieval methods (<tt>peek</tt>,
72	<	* <tt>element</tt>, and <tt>size</tt>).
67	>	* <p>Implementation note: this implementation provides
68	>	* O(log(n)) time for the enqueuing and dequeuing methods
69	>	* ({@code offer}, {@code poll}, {@code remove()} and {@code add});
70	>	* linear time for the {@code remove(Object)} and {@code contains(Object)}
71	>	* methods; and constant time for the retrieval methods
72	>	* ({@code peek}, {@code element}, and {@code size}).
73		*
74		* <p>This class is a member of the
75	<	* <a href="{@docRoot}/../guide/collections/index.html">
75	>	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
76		* Java Collections Framework</a>.
77	+	*
78		* @since 1.5
79	<	* @version 1.8, 08/27/05
60	<	* @author Josh Bloch
79	>	* @author Josh Bloch, Doug Lea
80		* @param <E> the type of elements held in this collection
81		*/
82		public class PriorityQueue<E> extends AbstractQueue<E>
#	Line 68 | Line 87 | public class PriorityQueue<E> extends Ab
87		private static final int DEFAULT_INITIAL_CAPACITY = 11;
88
89		/**
90	<	* Priority queue represented as a balanced binary heap: the two children
91	<	* of queue[n] are queue[2*n] and queue[2*n + 1].  The priority queue is
92	<	* ordered by comparator, or by the elements' natural ordering, if
93	<	* comparator is null:  For each node n in the heap and each descendant d
94	<	* of n, n <= d.
95	<	*
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.
90	>	* Priority queue represented as a balanced binary heap: the two
91	>	* children of queue[n] are queue[2*n+1] and queue[2*(n+1)].  The
92	>	* priority queue is ordered by comparator, or by the elements'
93	>	* natural ordering, if comparator is null: For each node n in the
94	>	* heap and each descendant d of n, n <= d.  The element with the
95	>	* lowest value is in queue[0], assuming the queue is nonempty.
96		*/
97	<	private transient Object[] queue;
97	>	transient Object[] queue; // non-private to simplify nested class access
98
99		/**
100		* The number of elements in the priority queue.
101		*/
102	<	private int size = 0;
102	>	private int size;
103
104		/**
105		* The comparator, or null if priority queue uses elements'
#	Line 97 | Line 111 | public class PriorityQueue<E> extends Ab
111		* The number of times this priority queue has been
112		* <i>structurally modified</i>.  See AbstractList for gory details.
113		*/
114	<	private transient int modCount = 0;
114	>	transient int modCount = 0; // non-private to simplify nested class access
115
116		/**
117	<	* Creates a <tt>PriorityQueue</tt> with the default initial
117	>	* Creates a {@code PriorityQueue} with the default initial
118		* capacity (11) that orders its elements according to their
119		* {@linkplain Comparable natural ordering}.
120		*/
#	Line 109 | Line 123 | public class PriorityQueue<E> extends Ab
123		}
124
125		/**
126	<	* Creates a <tt>PriorityQueue</tt> with the specified initial
126	>	* Creates a {@code PriorityQueue} with the specified initial
127		* capacity that orders its elements according to their
128		* {@linkplain Comparable natural ordering}.
129		*
130		* @param initialCapacity the initial capacity for this priority queue
131	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less
132	<	* than 1
131	>	* @throws IllegalArgumentException if {@code initialCapacity} is less
132	>	*         than 1
133		*/
134		public PriorityQueue(int initialCapacity) {
135		this(initialCapacity, null);
136		}
137
138		/**
139	<	* Creates a <tt>PriorityQueue</tt> with the specified initial capacity
139	>	* Creates a {@code PriorityQueue} with the specified initial capacity
140		* that orders its elements according to the specified comparator.
141		*
142		* @param  initialCapacity the initial capacity for this priority queue
143	<	* @param  comparator the comparator that will be used to order
144	<	*         this priority queue.  If <tt>null</tt>, the <i>natural
145	<	*         ordering</i> of the elements will be used.
146	<	* @throws IllegalArgumentException if <tt>initialCapacity</tt> is
143	>	* @param  comparator the comparator that will be used to order this
144	>	*         priority queue.  If {@code null}, the {@linkplain Comparable
145	>	*         natural ordering} of the elements will be used.
146	>	* @throws IllegalArgumentException if {@code initialCapacity} is
147		*         less than 1
148		*/
149		public PriorityQueue(int initialCapacity,
150		Comparator<? super E> comparator) {
151	+	// Note: This restriction of at least one is not actually needed,
152	+	// but continues for 1.5 compatibility
153		if (initialCapacity < 1)
154		throw new IllegalArgumentException();
155	<	this.queue = new Object[initialCapacity + 1];
155	>	this.queue = new Object[initialCapacity];
156		this.comparator = comparator;
157		}
158
159		/**
160	<	* Common code to initialize underlying queue array across
161	<	* constructors below.
162	<	*/
163	<	private void initializeArray(Collection<? extends E> c) {
164	<	int sz = c.size();
165	<	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.
160	>	* Creates a {@code PriorityQueue} containing the elements in the
161	>	* specified collection.  If the specified collection is an instance of
162	>	* a {@link SortedSet} or is another {@code PriorityQueue}, this
163	>	* priority queue will be ordered according to the same ordering.
164	>	* Otherwise, this priority queue will be ordered according to the
165	>	* {@linkplain Comparable natural ordering} of its elements.
166		*
167		* @param  c the collection whose elements are to be placed
168		*         into this priority queue
#	Line 201 | Line 172 | public class PriorityQueue<E> extends Ab
172		* @throws NullPointerException if the specified collection or any
173		*         of its elements are null
174		*/
175	+	@SuppressWarnings("unchecked")
176		public PriorityQueue(Collection<? extends E> c) {
177	<	initializeArray(c);
178	<	if (c instanceof SortedSet) {
179	<	SortedSet<? extends E> s = (SortedSet<? extends E>)c;
180	<	comparator = (Comparator<? super E>)s.comparator();
181	<	fillFromSorted(s);
182	<	} else if (c instanceof PriorityQueue) {
183	<	PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c;
184	<	comparator = (Comparator<? super E>)s.comparator();
185	<	fillFromSorted(s);
186	<	} else {
187	<	comparator = null;
188	<	fillFromUnsorted(c);
177	>	if (c instanceof SortedSet<?>) {
178	>	SortedSet<? extends E> ss = (SortedSet<? extends E>) c;
179	>	this.comparator = (Comparator<? super E>) ss.comparator();
180	>	initElementsFromCollection(ss);
181	>	}
182	>	else if (c instanceof PriorityQueue<?>) {
183	>	PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c;
184	>	this.comparator = (Comparator<? super E>) pq.comparator();
185	>	initFromPriorityQueue(pq);
186	>	}
187	>	else {
188	>	this.comparator = null;
189	>	initFromCollection(c);
190		}
191		}
192
193		/**
194	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
195	<	* 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
194	>	* Creates a {@code PriorityQueue} containing the elements in the
195	>	* specified priority queue.  This priority queue will be
196		* ordered according to the same ordering as the given priority
197		* queue.
198		*
199		* @param  c the priority queue whose elements are to be placed
200		*         into this priority queue
201	<	* @throws ClassCastException if elements of <tt>c</tt> cannot be
202	<	*         compared to one another according to <tt>c</tt>'s
201	>	* @throws ClassCastException if elements of {@code c} cannot be
202	>	*         compared to one another according to {@code c}'s
203		*         ordering
204		* @throws NullPointerException if the specified priority queue or any
205		*         of its elements are null
206		*/
207	+	@SuppressWarnings("unchecked")
208		public PriorityQueue(PriorityQueue<? extends E> c) {
209	<	initializeArray(c);
210	<	comparator = (Comparator<? super E>)c.comparator();
239	<	fillFromSorted(c);
209	>	this.comparator = (Comparator<? super E>) c.comparator();
210	>	initFromPriorityQueue(c);
211		}
212
213		/**
214	<	* Creates a <tt>PriorityQueue</tt> containing the elements in the
215	<	* 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
214	>	* Creates a {@code PriorityQueue} containing the elements in the
215	>	* specified sorted set.   This priority queue will be ordered
216		* according to the same ordering as the given sorted set.
217		*
218		* @param  c the sorted set whose elements are to be placed
219	<	*         into this priority queue.
219	>	*         into this priority queue
220		* @throws ClassCastException if elements of the specified sorted
221		*         set cannot be compared to one another according to the
222		*         sorted set's ordering
223		* @throws NullPointerException if the specified sorted set or any
224		*         of its elements are null
225		*/
226	+	@SuppressWarnings("unchecked")
227		public PriorityQueue(SortedSet<? extends E> c) {
228	<	initializeArray(c);
229	<	comparator = (Comparator<? super E>)c.comparator();
230	<	fillFromSorted(c);
228	>	this.comparator = (Comparator<? super E>) c.comparator();
229	>	initElementsFromCollection(c);
230	>	}
231	>
232	>	private void initFromPriorityQueue(PriorityQueue<? extends E> c) {
233	>	if (c.getClass() == PriorityQueue.class) {
234	>	this.queue = c.toArray();
235	>	this.size = c.size();
236	>	} else {
237	>	initFromCollection(c);
238	>	}
239	>	}
240	>
241	>	private void initElementsFromCollection(Collection<? extends E> c) {
242	>	Object[] a = c.toArray();
243	>	// If c.toArray incorrectly doesn't return Object[], copy it.
244	>	if (a.getClass() != Object[].class)
245	>	a = Arrays.copyOf(a, a.length, Object[].class);
246	>	int len = a.length;
247	>	if (len == 1 || this.comparator != null)
248	>	for (int i = 0; i < len; i++)
249	>	if (a[i] == null)
250	>	throw new NullPointerException();
251	>	this.queue = a;
252	>	this.size = a.length;
253		}
254
255		/**
256	<	* Resize array, if necessary, to be able to hold given index.
256	>	* Initializes queue array with elements from the given Collection.
257	>	*
258	>	* @param c the collection
259	>	*/
260	>	private void initFromCollection(Collection<? extends E> c) {
261	>	initElementsFromCollection(c);
262	>	heapify();
263	>	}
264	>
265	>	/**
266	>	* The maximum size of array to allocate.
267	>	* Some VMs reserve some header words in an array.
268	>	* Attempts to allocate larger arrays may result in
269	>	* OutOfMemoryError: Requested array size exceeds VM limit
270	>	*/
271	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
272	>
273	>	/**
274	>	* Increases the capacity of the array.
275	>	*
276	>	* @param minCapacity the desired minimum capacity
277		*/
278	<	private void grow(int index) {
279	<	int newlen = queue.length;
280	<	if (index < newlen) // don't need to grow
281	<	return;
282	<	if (index == Integer.MAX_VALUE)
278	>	private void grow(int minCapacity) {
279	>	int oldCapacity = queue.length;
280	>	// Double size if small; else grow by 50%
281	>	int newCapacity = oldCapacity + ((oldCapacity < 64) ?
282	>	(oldCapacity + 2) :
283	>	(oldCapacity >> 1));
284	>	// overflow-conscious code
285	>	if (newCapacity - MAX_ARRAY_SIZE > 0)
286	>	newCapacity = hugeCapacity(minCapacity);
287	>	queue = Arrays.copyOf(queue, newCapacity);
288	>	}
289	>
290	>	private static int hugeCapacity(int minCapacity) {
291	>	if (minCapacity < 0) // overflow
292		throw new OutOfMemoryError();
293	<	while (newlen <= index) {
294	<	if (newlen >= Integer.MAX_VALUE / 2)  // avoid overflow
295	<	newlen = Integer.MAX_VALUE;
275	<	else
276	<	newlen <<= 1;
277	<	}
278	<	queue = Arrays.copyOf(queue, newlen);
293	>	return (minCapacity > MAX_ARRAY_SIZE) ?
294	>	Integer.MAX_VALUE :
295	>	MAX_ARRAY_SIZE;
296		}
297
298		/**
299		* Inserts the specified element into this priority queue.
300		*
301	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
301	>	* @return {@code true} (as specified by {@link Collection#add})
302		* @throws ClassCastException if the specified element cannot be
303		*         compared with elements currently in this priority queue
304		*         according to the priority queue's ordering
#	Line 294 | Line 311 | public class PriorityQueue<E> extends Ab
311		/**
312		* Inserts the specified element into this priority queue.
313		*
314	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
314	>	* @return {@code true} (as specified by {@link Queue#offer})
315		* @throws ClassCastException if the specified element cannot be
316		*         compared with elements currently in this priority queue
317		*         according to the priority queue's ordering
#	Line 304 | Line 321 | public class PriorityQueue<E> extends Ab
321		if (e == null)
322		throw new NullPointerException();
323		modCount++;
324	<	++size;
325	<
326	<	// Grow backing store if necessary
327	<	if (size >= queue.length)
328	<	grow(size);
329	<
330	<	queue[size] = e;
331	<	fixUp(size);
324	>	int i = size;
325	>	if (i >= queue.length)
326	>	grow(i + 1);
327	>	size = i + 1;
328	>	if (i == 0)
329	>	queue[0] = e;
330	>	else
331	>	siftUp(i, e);
332		return true;
333		}
334
335	+	@SuppressWarnings("unchecked")
336		public E peek() {
337	<	if (size == 0)
320	<	return null;
321	<	return (E) queue[1];
337	>	return (size == 0) ? null : (E) queue[0];
338		}
339
340		private int indexOf(Object o) {
341	<	if (o == null)
342	<	return -1;
343	<	for (int i = 1; i <= size; i++)
344	<	if (o.equals(queue[i]))
345	<	return i;
341	>	if (o != null) {
342	>	for (int i = 0; i < size; i++)
343	>	if (o.equals(queue[i]))
344	>	return i;
345	>	}
346		return -1;
347		}
348
349		/**
350		* Removes a single instance of the specified element from this queue,
351	<	* if it is present.  More formally, removes an element <tt>e</tt> such
352	<	* that <tt>o.equals(e)</tt>, if this queue contains one or more such
353	<	* elements.  Returns true if this queue contained the specified element
354	<	* (or equivalently, if this queue changed as a result of the call).
351	>	* if it is present.  More formally, removes an element {@code e} such
352	>	* that {@code o.equals(e)}, if this queue contains one or more such
353	>	* elements.  Returns {@code true} if and only if this queue contained
354	>	* the specified element (or equivalently, if this queue changed as a
355	>	* result of the call).
356		*
357		* @param o element to be removed from this queue, if present
358	<	* @return <tt>true</tt> if this queue changed as a result of the call
358	>	* @return {@code true} if this queue changed as a result of the call
359		*/
360		public boolean remove(Object o) {
361	<	int i = indexOf(o);
362	<	if (i == -1)
363	<	return false;
364	<	else {
365	<	removeAt(i);
366	<	return true;
367	<	}
361	>	int i = indexOf(o);
362	>	if (i == -1)
363	>	return false;
364	>	else {
365	>	removeAt(i);
366	>	return true;
367	>	}
368	>	}
369	>
370	>	/**
371	>	* Version of remove using reference equality, not equals.
372	>	* Needed by iterator.remove.
373	>	*
374	>	* @param o element to be removed from this queue, if present
375	>	* @return {@code true} if removed
376	>	*/
377	>	boolean removeEq(Object o) {
378	>	for (int i = 0; i < size; i++) {
379	>	if (o == queue[i]) {
380	>	removeAt(i);
381	>	return true;
382	>	}
383	>	}
384	>	return false;
385		}
386
387		/**
388	<	* Returns <tt>true</tt> if this queue contains the specified element.
389	<	* More formally, returns <tt>true</tt> if and only if this queue contains
390	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
388	>	* Returns {@code true} if this queue contains the specified element.
389	>	* More formally, returns {@code true} if and only if this queue contains
390	>	* at least one element {@code e} such that {@code o.equals(e)}.
391		*
392		* @param o object to be checked for containment in this queue
393	<	* @return <tt>true</tt> if this queue contains the specified element
393	>	* @return {@code true} if this queue contains the specified element
394		*/
395		public boolean contains(Object o) {
396	<	return indexOf(o) != -1;
396	>	return indexOf(o) >= 0;
397		}
398
399		/**
400	<	* Returns an array containing all of the elements in this queue,
400	>	* Returns an array containing all of the elements in this queue.
401		* The elements are in no particular order.
402		*
403		* <p>The returned array will be "safe" in that no references to it are
404	<	* maintained by this list.  (In other words, this method must allocate
404	>	* maintained by this queue.  (In other words, this method must allocate
405		* a new array).  The caller is thus free to modify the returned array.
406		*
407	<	* @return an array containing all of the elements in this queue.
407	>	* <p>This method acts as bridge between array-based and collection-based
408	>	* APIs.
409	>	*
410	>	* @return an array containing all of the elements in this queue
411		*/
412		public Object[] toArray() {
413	<	return Arrays.copyOfRange(queue, 1, size+1);
413	>	return Arrays.copyOf(queue, size);
414		}
415
416		/**
417	<	* Returns an array containing all of the elements in this queue.
418	<	* The elements are in no particular order.  The runtime type of
419	<	* the returned array is that of the specified array.  If the queue
420	<	* fits in the specified array, it is returned therein.
421	<	* Otherwise, a new array is allocated with the runtime type of
422	<	* the specified array and the size of this queue.
417	>	* Returns an array containing all of the elements in this queue; the
418	>	* runtime type of the returned array is that of the specified array.
419	>	* The returned array elements are in no particular order.
420	>	* If the queue fits in the specified array, it is returned therein.
421	>	* Otherwise, a new array is allocated with the runtime type of the
422	>	* specified array and the size of this queue.
423		*
424		* <p>If the queue fits in the specified array with room to spare
425		* (i.e., the array has more elements than the queue), the element in
426		* the array immediately following the end of the collection is set to
427	<	* <tt>null</tt>.  (This is useful in determining the length of the
428	<	* queue <i>only</i> if the caller knows that the queue does not contain
429	<	* any null elements.)
427	>	* {@code null}.
428	>	*
429	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
430	>	* array-based and collection-based APIs.  Further, this method allows
431	>	* precise control over the runtime type of the output array, and may,
432	>	* under certain circumstances, be used to save allocation costs.
433	>	*
434	>	* <p>Suppose {@code x} is a queue known to contain only strings.
435	>	* The following code can be used to dump the queue into a newly
436	>	* allocated array of {@code String}:
437	>	*
438	>	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
439	>	*
440	>	* Note that {@code toArray(new Object[0])} is identical in function to
441	>	* {@code toArray()}.
442		*
443		* @param a the array into which the elements of the queue are to
444		*          be stored, if it is big enough; otherwise, a new array of the
445		*          same runtime type is allocated for this purpose.
446	<	* @return an array containing the elements of the queue
446	>	* @return an array containing all of the elements in this queue
447		* @throws ArrayStoreException if the runtime type of the specified array
448		*         is not a supertype of the runtime type of every element in
449		*         this queue
450		* @throws NullPointerException if the specified array is null
451		*/
452	+	@SuppressWarnings("unchecked")
453		public <T> T[] toArray(T[] a) {
454	+	final int size = this.size;
455		if (a.length < size)
456		// Make a new array of a's runtime type, but my contents:
457	<	return (T[]) Arrays.copyOfRange(queue, 1, size+1, a.getClass());
458	<	System.arraycopy(queue, 1, a, 0, size);
457	>	return (T[]) Arrays.copyOf(queue, size, a.getClass());
458	>	System.arraycopy(queue, 0, a, 0, size);
459		if (a.length > size)
460		a[size] = null;
461		return a;
#	Line 420 | Line 471 | public class PriorityQueue<E> extends Ab
471		return new Itr();
472		}
473
474	<	private class Itr implements Iterator<E> {
424	<
474	>	private final class Itr implements Iterator<E> {
475		/**
476		* Index (into queue array) of element to be returned by
477		* subsequent call to next.
478		*/
479	<	private int cursor = 1;
479	>	private int cursor;
480
481		/**
482		* Index of element returned by most recent call to next,
483		* unless that element came from the forgetMeNot list.
484	<	* 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.
484	>	* Set to -1 if element is deleted by a call to remove.
485		*/
486	<	private int expectedModCount = modCount;
486	>	private int lastRet = -1;
487
488		/**
489	<	* A list of elements that were moved from the unvisited portion of
489	>	* A queue of elements that were moved from the unvisited portion of
490		* the heap into the visited portion as a result of "unlucky" element
491		* removals during the iteration.  (Unlucky element removals are those
492	<	* that require a fixup instead of a fixdown.)  We must visit all of
492	>	* that require a siftup instead of a siftdown.)  We must visit all of
493		* the elements in this list to complete the iteration.  We do this
494		* after we've completed the "normal" iteration.
495		*
496		* We expect that most iterations, even those involving removals,
497	<	* will not use need to store elements in this field.
497	>	* will not need to store elements in this field.
498		*/
499	<	private ArrayList<E> forgetMeNot = null;
499	>	private ArrayDeque<E> forgetMeNot;
500
501		/**
502		* Element returned by the most recent call to next iff that
503		* element was drawn from the forgetMeNot list.
504		*/
505	<	private Object lastRetElt = null;
505	>	private E lastRetElt;
506	>
507	>	/**
508	>	* The modCount value that the iterator believes that the backing
509	>	* Queue should have.  If this expectation is violated, the iterator
510	>	* has detected concurrent modification.
511	>	*/
512	>	private int expectedModCount = modCount;
513
514		public boolean hasNext() {
515	<	return cursor <= size || forgetMeNot != null;
515	>	return cursor < size ||
516	>	(forgetMeNot != null && !forgetMeNot.isEmpty());
517		}
518
519	+	@SuppressWarnings("unchecked")
520		public E next() {
521	<	checkForComodification();
522	<	E result;
523	<	if (cursor <= size) {
524	<	result = (E) queue[cursor];
525	<	lastRet = cursor++;
526	<	}
527	<	else if (forgetMeNot == null)
528	<	throw new NoSuchElementException();
529	<	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;
521	>	if (expectedModCount != modCount)
522	>	throw new ConcurrentModificationException();
523	>	if (cursor < size)
524	>	return (E) queue[lastRet = cursor++];
525	>	if (forgetMeNot != null) {
526	>	lastRet = -1;
527	>	lastRetElt = forgetMeNot.poll();
528	>	if (lastRetElt != null)
529	>	return lastRetElt;
530		}
531	<	return result;
531	>	throw new NoSuchElementException();
532		}
533
534		public void remove() {
535	<	checkForComodification();
536	<
537	<	if (lastRet != 0) {
535	>	if (expectedModCount != modCount)
536	>	throw new ConcurrentModificationException();
537	>	if (lastRet != -1) {
538		E moved = PriorityQueue.this.removeAt(lastRet);
539	<	lastRet = 0;
540	<	if (moved == null) {
539	>	lastRet = -1;
540	>	if (moved == null)
541		cursor--;
542	<	} else {
542	>	else {
543		if (forgetMeNot == null)
544	<	forgetMeNot = new ArrayList<E>();
544	>	forgetMeNot = new ArrayDeque<>();
545		forgetMeNot.add(moved);
546		}
547		} else if (lastRetElt != null) {
548	<	PriorityQueue.this.remove(lastRetElt);
548	>	PriorityQueue.this.removeEq(lastRetElt);
549		lastRetElt = null;
550		} else {
551		throw new IllegalStateException();
552		}
507	–
553		expectedModCount = modCount;
554		}
510	–
511	–	final void checkForComodification() {
512	–	if (modCount != expectedModCount)
513	–	throw new ConcurrentModificationException();
514	–	}
555		}
556
557		public int size() {
#	Line 524 | Line 564 | public class PriorityQueue<E> extends Ab
564		*/
565		public void clear() {
566		modCount++;
567	<
528	<	// Null out element references to prevent memory leak
529	<	for (int i=1; i<=size; i++)
567	>	for (int i = 0; i < size; i++)
568		queue[i] = null;
531	–
569		size = 0;
570		}
571
572	+	@SuppressWarnings("unchecked")
573		public E poll() {
574		if (size == 0)
575		return null;
576	+	int s = --size;
577		modCount++;
578	<
579	<	E result = (E) queue[1];
580	<	queue[1] = queue[size];
581	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
582	<	if (size > 1)
544	<	fixDown(1);
545	<
578	>	E result = (E) queue[0];
579	>	E x = (E) queue[s];
580	>	queue[s] = null;
581	>	if (s != 0)
582	>	siftDown(0, x);
583		return result;
584		}
585
586		/**
587	<	* Removes and returns the ith element from queue.  (Recall that queue
551	<	* is one-based, so 1 <= i <= size.)
587	>	* Removes the ith element from queue.
588		*
589	<	* Normally this method leaves the elements at positions from 1 up to i-1,
590	<	* inclusive, untouched.  Under these circumstances, it returns null.
591	<	* Occasionally, in order to maintain the heap invariant, it must move
592	<	* the last element of the list to some index in the range [2, i-1],
593	<	* and move the element previously at position (i/2) to position i.
594	<	* Under these circumstances, this method returns the element that was
595	<	* previously at the end of the list and is now at some position between
596	<	* 2 and i-1 inclusive.
589	>	* Normally this method leaves the elements at up to i-1,
590	>	* inclusive, untouched.  Under these circumstances, it returns
591	>	* null.  Occasionally, in order to maintain the heap invariant,
592	>	* it must swap a later element of the list with one earlier than
593	>	* i.  Under these circumstances, this method returns the element
594	>	* that was previously at the end of the list and is now at some
595	>	* position before i. This fact is used by iterator.remove so as to
596	>	* avoid missing traversing elements.
597		*/
598	+	@SuppressWarnings("unchecked")
599		private E removeAt(int i) {
600	<	assert i > 0 && i <= size;
600	>	// assert i >= 0 && i < size;
601		modCount++;
602	<
603	<	E moved = (E) queue[size];
604	<	queue[i] = moved;
605	<	queue[size--] = null;  // Drop extra ref to prevent memory leak
606	<	if (i <= size) {
607	<	fixDown(i);
602	>	int s = --size;
603	>	if (s == i) // removed last element
604	>	queue[i] = null;
605	>	else {
606	>	E moved = (E) queue[s];
607	>	queue[s] = null;
608	>	siftDown(i, moved);
609		if (queue[i] == moved) {
610	<	fixUp(i);
610	>	siftUp(i, moved);
611		if (queue[i] != moved)
612		return moved;
613		}
#	Line 578 | Line 616 | public class PriorityQueue<E> extends Ab
616		}
617
618		/**
619	<	* Establishes the heap invariant (described above) assuming the heap
620	<	* satisfies the invariant except possibly for the leaf-node indexed by k
621	<	* (which may have a nextExecutionTime less than its parent's).
622	<	*
623	<	* This method functions by "promoting" queue[k] up the hierarchy
624	<	* (by swapping it with its parent) repeatedly until queue[k]
625	<	* is greater than or equal to its parent.
626	<	*/
627	<	private void fixUp(int k) {
628	<	if (comparator == null) {
629	<	while (k > 1) {
630	<	int j = k >> 1;
631	<	if (((Comparable<? super E>)queue[j]).compareTo((E)queue[k]) <= 0)
632	<	break;
633	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
634	<	k = j;
635	<	}
636	<	} else {
637	<	while (k > 1) {
638	<	int j = k >>> 1;
639	<	if (comparator.compare((E)queue[j], (E)queue[k]) <= 0)
640	<	break;
641	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
642	<	k = j;
643	<	}
644	<	}
645	<	}
646	<
647	<	/**
648	<	* Establishes the heap invariant (described above) in the subtree
649	<	* rooted at k, which is assumed to satisfy the heap invariant except
650	<	* possibly for node k itself (which may be greater than its children).
651	<	*
652	<	* This method functions by "demoting" queue[k] down the hierarchy
653	<	* (by swapping it with its smaller child) repeatedly until queue[k]
654	<	* is less than or equal to its children.
655	<	*/
656	<	private void fixDown(int k) {
657	<	int j;
658	<	if (comparator == null) {
659	<	while ((j = k << 1) <= size && (j > 0)) {
660	<	if (j<size &&
661	<	((Comparable<? super E>)queue[j]).compareTo((E)queue[j+1]) > 0)
662	<	j++; // j indexes smallest kid
663	<
664	<	if (((Comparable<? super E>)queue[k]).compareTo((E)queue[j]) <= 0)
665	<	break;
666	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
667	<	k = j;
668	<	}
669	<	} else {
670	<	while ((j = k << 1) <= size && (j > 0)) {
671	<	if (j<size &&
672	<	comparator.compare((E)queue[j], (E)queue[j+1]) > 0)
673	<	j++; // j indexes smallest kid
674	<	if (comparator.compare((E)queue[k], (E)queue[j]) <= 0)
675	<	break;
676	<	Object tmp = queue[j];  queue[j] = queue[k]; queue[k] = tmp;
677	<	k = j;
678	<	}
619	>	* Inserts item x at position k, maintaining heap invariant by
620	>	* promoting x up the tree until it is greater than or equal to
621	>	* its parent, or is the root.
622	>	*
623	>	* To simplify and speed up coercions and comparisons. the
624	>	* Comparable and Comparator versions are separated into different
625	>	* methods that are otherwise identical. (Similarly for siftDown.)
626	>	*
627	>	* @param k the position to fill
628	>	* @param x the item to insert
629	>	*/
630	>	private void siftUp(int k, E x) {
631	>	if (comparator != null)
632	>	siftUpUsingComparator(k, x);
633	>	else
634	>	siftUpComparable(k, x);
635	>	}
636	>
637	>	@SuppressWarnings("unchecked")
638	>	private void siftUpComparable(int k, E x) {
639	>	Comparable<? super E> key = (Comparable<? super E>) x;
640	>	while (k > 0) {
641	>	int parent = (k - 1) >>> 1;
642	>	Object e = queue[parent];
643	>	if (key.compareTo((E) e) >= 0)
644	>	break;
645	>	queue[k] = e;
646	>	k = parent;
647	>	}
648	>	queue[k] = key;
649	>	}
650	>
651	>	@SuppressWarnings("unchecked")
652	>	private void siftUpUsingComparator(int k, E x) {
653	>	while (k > 0) {
654	>	int parent = (k - 1) >>> 1;
655	>	Object e = queue[parent];
656	>	if (comparator.compare(x, (E) e) >= 0)
657	>	break;
658	>	queue[k] = e;
659	>	k = parent;
660	>	}
661	>	queue[k] = x;
662	>	}
663	>
664	>	/**
665	>	* Inserts item x at position k, maintaining heap invariant by
666	>	* demoting x down the tree repeatedly until it is less than or
667	>	* equal to its children or is a leaf.
668	>	*
669	>	* @param k the position to fill
670	>	* @param x the item to insert
671	>	*/
672	>	private void siftDown(int k, E x) {
673	>	if (comparator != null)
674	>	siftDownUsingComparator(k, x);
675	>	else
676	>	siftDownComparable(k, x);
677	>	}
678	>
679	>	@SuppressWarnings("unchecked")
680	>	private void siftDownComparable(int k, E x) {
681	>	Comparable<? super E> key = (Comparable<? super E>)x;
682	>	int half = size >>> 1;        // loop while a non-leaf
683	>	while (k < half) {
684	>	int child = (k << 1) + 1; // assume left child is least
685	>	Object c = queue[child];
686	>	int right = child + 1;
687	>	if (right < size &&
688	>	((Comparable<? super E>) c).compareTo((E) queue[right]) > 0)
689	>	c = queue[child = right];
690	>	if (key.compareTo((E) c) <= 0)
691	>	break;
692	>	queue[k] = c;
693	>	k = child;
694	>	}
695	>	queue[k] = key;
696	>	}
697	>
698	>	@SuppressWarnings("unchecked")
699	>	private void siftDownUsingComparator(int k, E x) {
700	>	int half = size >>> 1;
701	>	while (k < half) {
702	>	int child = (k << 1) + 1;
703	>	Object c = queue[child];
704	>	int right = child + 1;
705	>	if (right < size &&
706	>	comparator.compare((E) c, (E) queue[right]) > 0)
707	>	c = queue[child = right];
708	>	if (comparator.compare(x, (E) c) <= 0)
709	>	break;
710	>	queue[k] = c;
711	>	k = child;
712		}
713	+	queue[k] = x;
714		}
715
716		/**
717		* Establishes the heap invariant (described above) in the entire tree,
718		* assuming nothing about the order of the elements prior to the call.
719		*/
720	+	@SuppressWarnings("unchecked")
721		private void heapify() {
722	<	for (int i = size/2; i >= 1; i--)
723	<	fixDown(i);
722	>	for (int i = (size >>> 1) - 1; i >= 0; i--)
723	>	siftDown(i, (E) queue[i]);
724		}
725
726		/**
727		* Returns the comparator used to order the elements in this
728	<	* queue, or <tt>null</tt> if this queue is sorted according to
728	>	* queue, or {@code null} if this queue is sorted according to
729		* the {@linkplain Comparable natural ordering} of its elements.
730		*
731		* @return the comparator used to order this queue, or
732	<	*         <tt>null</tt> if this queue is sorted according to the
733	<	*         natural ordering of its elements.
732	>	*         {@code null} if this queue is sorted according to the
733	>	*         natural ordering of its elements
734		*/
735		public Comparator<? super E> comparator() {
736		return comparator;
737		}
738
739		/**
740	<	* Save the state of the instance to a stream (that
668	<	* is, serialize it).
740	>	* Saves this queue to a stream (that is, serializes it).
741		*
742		* @serialData The length of the array backing the instance is
743	<	* emitted (int), followed by all of its elements (each an
744	<	* <tt>Object</tt>) in the proper order.
743	>	*             emitted (int), followed by all of its elements
744	>	*             (each an {@code Object}) in the proper order.
745		* @param s the stream
746	+	* @throws java.io.IOException if an I/O error occurs
747		*/
748		private void writeObject(java.io.ObjectOutputStream s)
749	<	throws java.io.IOException{
749	>	throws java.io.IOException {
750		// Write out element count, and any hidden stuff
751		s.defaultWriteObject();
752
753	<	// Write out array length
754	<	s.writeInt(queue.length);
753	>	// Write out array length, for compatibility with 1.5 version
754	>	s.writeInt(Math.max(2, size + 1));
755
756	<	// Write out all elements in the proper order.
757	<	for (int i=1; i<=size; i++)
756	>	// Write out all elements in the "proper order".
757	>	for (int i = 0; i < size; i++)
758		s.writeObject(queue[i]);
759		}
760
761		/**
762	<	* Reconstitute the <tt>PriorityQueue</tt> instance from a stream
763	<	* (that is, deserialize it).
762	>	* Reconstitutes the {@code PriorityQueue} instance from a stream
763	>	* (that is, deserializes it).
764	>	*
765		* @param s the stream
766	+	* @throws ClassNotFoundException if the class of a serialized object
767	+	*         could not be found
768	+	* @throws java.io.IOException if an I/O error occurs
769		*/
770		private void readObject(java.io.ObjectInputStream s)
771		throws java.io.IOException, ClassNotFoundException {
772		// Read in size, and any hidden stuff
773		s.defaultReadObject();
774
775	<	// Read in array length and allocate array
776	<	int arrayLength = s.readInt();
777	<	queue = new Object[arrayLength];
778	<
779	<	// Read in all elements in the proper order.
780	<	for (int i=1; i<=size; i++)
781	<	queue[i] = (E) s.readObject();
775	>	// Read in (and discard) array length
776	>	s.readInt();
777	>
778	>	queue = new Object[size];
779	>
780	>	// Read in all elements.
781	>	for (int i = 0; i < size; i++)
782	>	queue[i] = s.readObject();
783	>
784	>	// Elements are guaranteed to be in "proper order", but the
785	>	// spec has never explained what that might be.
786	>	heapify();
787		}
788
789	+	public Spliterator<E> spliterator() {
790	+	return new PriorityQueueSpliterator<E>(this, 0, -1, 0);
791	+	}
792	+
793	+	/**
794	+	* This is very similar to ArrayList Spliterator, except for extra
795	+	* null checks.
796	+	*/
797	+	static final class PriorityQueueSpliterator<E> implements Spliterator<E> {
798	+	private final PriorityQueue<E> pq;
799	+	private int index;            // current index, modified on advance/split
800	+	private int fence;            // -1 until first use
801	+	private int expectedModCount; // initialized when fence set
802	+
803	+	/** Creates new spliterator covering the given range */
804	+	PriorityQueueSpliterator(PriorityQueue<E> pq, int origin, int fence,
805	+	int expectedModCount) {
806	+	this.pq = pq;
807	+	this.index = origin;
808	+	this.fence = fence;
809	+	this.expectedModCount = expectedModCount;
810	+	}
811	+
812	+	private int getFence() { // initialize fence to size on first use
813	+	int hi;
814	+	if ((hi = fence) < 0) {
815	+	expectedModCount = pq.modCount;
816	+	hi = fence = pq.size;
817	+	}
818	+	return hi;
819	+	}
820	+
821	+	public Spliterator<E> trySplit() {
822	+	int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
823	+	return (lo >= mid) ? null :
824	+	new PriorityQueueSpliterator<E>(pq, lo, index = mid,
825	+	expectedModCount);
826	+	}
827	+
828	+	@SuppressWarnings("unchecked")
829	+	public void forEachRemaining(Consumer<? super E> action) {
830	+	int i, hi, mc; // hoist accesses and checks from loop
831	+	PriorityQueue<E> q; Object[] a;
832	+	if (action == null)
833	+	throw new NullPointerException();
834	+	if ((q = pq) != null && (a = q.queue) != null) {
835	+	if ((hi = fence) < 0) {
836	+	mc = q.modCount;
837	+	hi = q.size;
838	+	}
839	+	else
840	+	mc = expectedModCount;
841	+	if ((i = index) >= 0 && (index = hi) <= a.length) {
842	+	for (E e;; ++i) {
843	+	if (i < hi) {
844	+	if ((e = (E) a[i]) == null) // must be CME
845	+	break;
846	+	action.accept(e);
847	+	}
848	+	else if (q.modCount != mc)
849	+	break;
850	+	else
851	+	return;
852	+	}
853	+	}
854	+	}
855	+	throw new ConcurrentModificationException();
856	+	}
857	+
858	+	public boolean tryAdvance(Consumer<? super E> action) {
859	+	int hi = getFence(), lo = index;
860	+	if (lo >= 0 && lo < hi) {
861	+	index = lo + 1;
862	+	@SuppressWarnings("unchecked") E e = (E)pq.queue[lo];
863	+	if (e == null)
864	+	throw new ConcurrentModificationException();
865	+	action.accept(e);
866	+	if (pq.modCount != expectedModCount)
867	+	throw new ConcurrentModificationException();
868	+	return true;
869	+	}
870	+	return false;
871	+	}
872	+
873	+	public long estimateSize() {
874	+	return (long) (getFence() - index);
875	+	}
876	+
877	+	public int characteristics() {
878	+	return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL;
879	+	}
880	+	}
881		}

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