1 |
< |
package java.util; |
1 |
> |
/* |
2 |
> |
* Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved. |
3 |
> |
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 |
> |
* |
5 |
> |
* This code is free software; you can redistribute it and/or modify it |
6 |
> |
* under the terms of the GNU General Public License version 2 only, as |
7 |
> |
* published by the Free Software Foundation. Oracle designates this |
8 |
> |
* particular file as subject to the "Classpath" exception as provided |
9 |
> |
* by Oracle in the LICENSE file that accompanied this code. |
10 |
> |
* |
11 |
> |
* This code is distributed in the hope that it will be useful, but WITHOUT |
12 |
> |
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
13 |
> |
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
14 |
> |
* version 2 for more details (a copy is included in the LICENSE file that |
15 |
> |
* accompanied this code). |
16 |
> |
* |
17 |
> |
* You should have received a copy of the GNU General Public License version |
18 |
> |
* 2 along with this work; if not, write to the Free Software Foundation, |
19 |
> |
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
20 |
> |
* |
21 |
> |
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
22 |
> |
* or visit www.oracle.com if you need additional information or have any |
23 |
> |
* questions. |
24 |
> |
*/ |
25 |
> |
|
26 |
> |
package java.util; |
27 |
> |
|
28 |
> |
import java.util.function.Consumer; |
29 |
> |
import java.util.function.Predicate; |
30 |
> |
// OPENJDK import jdk.internal.access.SharedSecrets; |
31 |
> |
import jdk.internal.util.ArraysSupport; |
32 |
|
|
33 |
|
/** |
34 |
< |
* An unbounded priority queue based on a priority heap. This queue orders |
35 |
< |
* elements according to an order specified at construction time, which is |
36 |
< |
* specified in the same manner as {@link TreeSet} and {@link TreeMap}: |
37 |
< |
* elements are ordered |
38 |
< |
* either according to their <i>natural order</i> (see {@link Comparable}), or |
39 |
< |
* according to a {@link Comparator}, depending on which constructor is used. |
40 |
< |
* The <em>head</em> of this queue is the least element with respect to the |
41 |
< |
* specified ordering. If multiple elements are tied for least value, the |
42 |
< |
* head is one of those elements. A priority queue does not permit |
43 |
< |
* <tt>null</tt> elements. |
44 |
< |
* |
45 |
< |
* <p>The {@link #remove()} and {@link #poll()} methods remove and |
46 |
< |
* return the head of the queue. |
47 |
< |
* |
48 |
< |
* <p>The {@link #element()} and {@link #peek()} methods return, but do |
49 |
< |
* not delete, the head of the queue. |
50 |
< |
* |
51 |
< |
* <p>A priority queue has a <i>capacity</i>. The capacity is the |
52 |
< |
* size of the array used internally to store the elements on the |
53 |
< |
* queue. It is always at least as large as the queue size. As |
54 |
< |
* elements are added to a priority queue, its capacity grows |
55 |
< |
* automatically. The details of the growth policy are not specified. |
56 |
< |
* |
57 |
< |
* <p>Implementation note: this implementation provides O(log(n)) time |
58 |
< |
* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>, |
59 |
< |
* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the |
60 |
< |
* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and |
61 |
< |
* constant time for the retrieval methods (<tt>peek</tt>, |
62 |
< |
* <tt>element</tt>, and <tt>size</tt>). |
34 |
> |
* An unbounded priority {@linkplain Queue queue} based on a priority heap. |
35 |
> |
* The elements of the priority queue are ordered according to their |
36 |
> |
* {@linkplain Comparable natural ordering}, or by a {@link Comparator} |
37 |
> |
* provided at queue construction time, depending on which constructor is |
38 |
> |
* used. A priority queue does not permit {@code null} elements. |
39 |
> |
* A priority queue relying on natural ordering also does not permit |
40 |
> |
* insertion of non-comparable objects (doing so may result in |
41 |
> |
* {@code ClassCastException}). |
42 |
> |
* |
43 |
> |
* <p>The <em>head</em> of this queue is the <em>least</em> element |
44 |
> |
* with respect to the specified ordering. If multiple elements are |
45 |
> |
* tied for least value, the head is one of those elements -- ties are |
46 |
> |
* broken arbitrarily. The queue retrieval operations {@code poll}, |
47 |
> |
* {@code remove}, {@code peek}, and {@code element} access the |
48 |
> |
* element at the head of the queue. |
49 |
> |
* |
50 |
> |
* <p>A priority queue is unbounded, but has an internal |
51 |
> |
* <i>capacity</i> governing the size of an array used to store the |
52 |
> |
* elements on the queue. It is always at least as large as the queue |
53 |
> |
* size. As elements are added to a priority queue, its capacity |
54 |
> |
* grows automatically. The details of the growth policy are not |
55 |
> |
* specified. |
56 |
> |
* |
57 |
> |
* <p>This class and its iterator implement all of the |
58 |
> |
* <em>optional</em> methods of the {@link Collection} and {@link |
59 |
> |
* Iterator} interfaces. The Iterator provided in method {@link |
60 |
> |
* #iterator()} and the Spliterator provided in method {@link #spliterator()} |
61 |
> |
* are <em>not</em> guaranteed to traverse the elements of |
62 |
> |
* the priority queue in any particular order. If you need ordered |
63 |
> |
* traversal, consider using {@code Arrays.sort(pq.toArray())}. |
64 |
> |
* |
65 |
> |
* <p><strong>Note that this implementation is not synchronized.</strong> |
66 |
> |
* Multiple threads should not access a {@code PriorityQueue} |
67 |
> |
* instance concurrently if any of the threads modifies the queue. |
68 |
> |
* Instead, use the thread-safe {@link |
69 |
> |
* java.util.concurrent.PriorityBlockingQueue} class. |
70 |
> |
* |
71 |
> |
* <p>Implementation note: this implementation provides |
72 |
> |
* O(log(n)) time for the enqueuing and dequeuing methods |
73 |
> |
* ({@code offer}, {@code poll}, {@code remove()} and {@code add}); |
74 |
> |
* linear time for the {@code remove(Object)} and {@code contains(Object)} |
75 |
> |
* methods; and constant time for the retrieval methods |
76 |
> |
* ({@code peek}, {@code element}, and {@code size}). |
77 |
|
* |
78 |
|
* <p>This class is a member of the |
79 |
< |
* <a href="{@docRoot}/../guide/collections/index.html"> |
79 |
> |
* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework"> |
80 |
|
* Java Collections Framework</a>. |
81 |
+ |
* |
82 |
|
* @since 1.5 |
83 |
< |
* @author Josh Bloch |
83 |
> |
* @author Josh Bloch, Doug Lea |
84 |
> |
* @param <E> the type of elements held in this queue |
85 |
|
*/ |
86 |
+ |
@SuppressWarnings("unchecked") |
87 |
|
public class PriorityQueue<E> extends AbstractQueue<E> |
88 |
< |
implements Queue<E>, java.io.Serializable { |
88 |
> |
implements java.io.Serializable { |
89 |
> |
|
90 |
> |
private static final long serialVersionUID = -7720805057305804111L; |
91 |
|
|
92 |
|
private static final int DEFAULT_INITIAL_CAPACITY = 11; |
93 |
|
|
94 |
|
/** |
95 |
< |
* Priority queue represented as a balanced binary heap: the two children |
96 |
< |
* of queue[n] are queue[2*n] and queue[2*n + 1]. The priority queue is |
97 |
< |
* ordered by comparator, or by the elements' natural ordering, if |
98 |
< |
* comparator is null: For each node n in the heap and each descendant d |
99 |
< |
* of n, n <= d. |
100 |
< |
* |
52 |
< |
* The element with the lowest value is in queue[1], assuming the queue is |
53 |
< |
* nonempty. (A one-based array is used in preference to the traditional |
54 |
< |
* zero-based array to simplify parent and child calculations.) |
55 |
< |
* |
56 |
< |
* queue.length must be >= 2, even if size == 0. |
95 |
> |
* Priority queue represented as a balanced binary heap: the two |
96 |
> |
* children of queue[n] are queue[2*n+1] and queue[2*(n+1)]. The |
97 |
> |
* priority queue is ordered by comparator, or by the elements' |
98 |
> |
* natural ordering, if comparator is null: For each node n in the |
99 |
> |
* heap and each descendant d of n, n <= d. The element with the |
100 |
> |
* lowest value is in queue[0], assuming the queue is nonempty. |
101 |
|
*/ |
102 |
< |
private transient E[] queue; |
102 |
> |
transient Object[] queue; // non-private to simplify nested class access |
103 |
|
|
104 |
|
/** |
105 |
|
* The number of elements in the priority queue. |
106 |
|
*/ |
107 |
< |
private int size = 0; |
107 |
> |
int size; |
108 |
|
|
109 |
|
/** |
110 |
|
* The comparator, or null if priority queue uses elements' |
111 |
|
* natural ordering. |
112 |
|
*/ |
113 |
< |
private final Comparator<E> comparator; |
113 |
> |
private final Comparator<? super E> comparator; |
114 |
|
|
115 |
|
/** |
116 |
|
* The number of times this priority queue has been |
117 |
|
* <i>structurally modified</i>. See AbstractList for gory details. |
118 |
|
*/ |
119 |
< |
private transient int modCount = 0; |
119 |
> |
transient int modCount; // non-private to simplify nested class access |
120 |
|
|
121 |
|
/** |
122 |
< |
* Create a <tt>PriorityQueue</tt> with the default initial capacity |
123 |
< |
* (11) that orders its elements according to their natural |
124 |
< |
* ordering (using <tt>Comparable</tt>.) |
122 |
> |
* Creates a {@code PriorityQueue} with the default initial |
123 |
> |
* capacity (11) that orders its elements according to their |
124 |
> |
* {@linkplain Comparable natural ordering}. |
125 |
|
*/ |
126 |
|
public PriorityQueue() { |
127 |
|
this(DEFAULT_INITIAL_CAPACITY, null); |
128 |
|
} |
129 |
|
|
130 |
|
/** |
131 |
< |
* Create a <tt>PriorityQueue</tt> with the specified initial capacity |
132 |
< |
* that orders its elements according to their natural ordering |
133 |
< |
* (using <tt>Comparable</tt>.) |
134 |
< |
* |
135 |
< |
* @param initialCapacity the initial capacity for this priority queue. |
131 |
> |
* Creates a {@code PriorityQueue} with the specified initial |
132 |
> |
* capacity that orders its elements according to their |
133 |
> |
* {@linkplain Comparable natural ordering}. |
134 |
> |
* |
135 |
> |
* @param initialCapacity the initial capacity for this priority queue |
136 |
> |
* @throws IllegalArgumentException if {@code initialCapacity} is less |
137 |
> |
* than 1 |
138 |
|
*/ |
139 |
|
public PriorityQueue(int initialCapacity) { |
140 |
|
this(initialCapacity, null); |
141 |
|
} |
142 |
|
|
143 |
|
/** |
144 |
< |
* Create a <tt>PriorityQueue</tt> with the specified initial capacity |
145 |
< |
* that orders its elements according to the specified comparator. |
144 |
> |
* Creates a {@code PriorityQueue} with the default initial capacity and |
145 |
> |
* whose elements are ordered according to the specified comparator. |
146 |
|
* |
147 |
< |
* @param initialCapacity the initial capacity for this priority queue. |
148 |
< |
* @param comparator the comparator used to order this priority queue. |
149 |
< |
* If <tt>null</tt> then the order depends on the elements' natural |
150 |
< |
* ordering. |
105 |
< |
* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less |
106 |
< |
* than 1 |
147 |
> |
* @param comparator the comparator that will be used to order this |
148 |
> |
* priority queue. If {@code null}, the {@linkplain Comparable |
149 |
> |
* natural ordering} of the elements will be used. |
150 |
> |
* @since 1.8 |
151 |
|
*/ |
152 |
< |
public PriorityQueue(int initialCapacity, Comparator<E> comparator) { |
152 |
> |
public PriorityQueue(Comparator<? super E> comparator) { |
153 |
> |
this(DEFAULT_INITIAL_CAPACITY, comparator); |
154 |
> |
} |
155 |
> |
|
156 |
> |
/** |
157 |
> |
* Creates a {@code PriorityQueue} with the specified initial capacity |
158 |
> |
* that orders its elements according to the specified comparator. |
159 |
> |
* |
160 |
> |
* @param initialCapacity the initial capacity for this priority queue |
161 |
> |
* @param comparator the comparator that will be used to order this |
162 |
> |
* priority queue. If {@code null}, the {@linkplain Comparable |
163 |
> |
* natural ordering} of the elements will be used. |
164 |
> |
* @throws IllegalArgumentException if {@code initialCapacity} is |
165 |
> |
* less than 1 |
166 |
> |
*/ |
167 |
> |
public PriorityQueue(int initialCapacity, |
168 |
> |
Comparator<? super E> comparator) { |
169 |
> |
// Note: This restriction of at least one is not actually needed, |
170 |
> |
// but continues for 1.5 compatibility |
171 |
|
if (initialCapacity < 1) |
172 |
|
throw new IllegalArgumentException(); |
173 |
< |
queue = (E[]) new Object[initialCapacity + 1]; |
173 |
> |
this.queue = new Object[initialCapacity]; |
174 |
|
this.comparator = comparator; |
175 |
|
} |
176 |
|
|
177 |
|
/** |
178 |
< |
* Create a <tt>PriorityQueue</tt> containing the elements in the specified |
179 |
< |
* collection. The priority queue has an initial capacity of 110% of the |
180 |
< |
* size of the specified collection; or 1 if the collection is empty. |
181 |
< |
* If the specified collection |
182 |
< |
* implements the {@link Sorted} interface, the priority queue will be |
183 |
< |
* sorted according to the same comparator, or according to its elements' |
122 |
< |
* natural order if the collection is sorted according to its elements' |
123 |
< |
* natural order. If the specified collection does not implement |
124 |
< |
* <tt>Sorted</tt>, the priority queue is ordered according to |
125 |
< |
* its elements' natural order. |
178 |
> |
* Creates a {@code PriorityQueue} containing the elements in the |
179 |
> |
* specified collection. If the specified collection is an instance of |
180 |
> |
* a {@link SortedSet} or is another {@code PriorityQueue}, this |
181 |
> |
* priority queue will be ordered according to the same ordering. |
182 |
> |
* Otherwise, this priority queue will be ordered according to the |
183 |
> |
* {@linkplain Comparable natural ordering} of its elements. |
184 |
|
* |
185 |
< |
* @param c the collection whose elements are to be placed |
186 |
< |
* into this priority queue. |
185 |
> |
* @param c the collection whose elements are to be placed |
186 |
> |
* into this priority queue |
187 |
|
* @throws ClassCastException if elements of the specified collection |
188 |
|
* cannot be compared to one another according to the priority |
189 |
< |
* queue's ordering. |
190 |
< |
* @throws NullPointerException if <tt>c</tt> or any element within it |
191 |
< |
* is <tt>null</tt> |
192 |
< |
*/ |
193 |
< |
public PriorityQueue(Collection<E> c) { |
194 |
< |
int sz = c.size(); |
195 |
< |
int initialCapacity = (int)Math.min((sz * 110L) / 100, |
196 |
< |
Integer.MAX_VALUE - 1); |
197 |
< |
if (initialCapacity < 1) |
198 |
< |
initialCapacity = 1; |
189 |
> |
* queue's ordering |
190 |
> |
* @throws NullPointerException if the specified collection or any |
191 |
> |
* of its elements are null |
192 |
> |
*/ |
193 |
> |
public PriorityQueue(Collection<? extends E> c) { |
194 |
> |
if (c instanceof SortedSet<?>) { |
195 |
> |
SortedSet<? extends E> ss = (SortedSet<? extends E>) c; |
196 |
> |
this.comparator = (Comparator<? super E>) ss.comparator(); |
197 |
> |
initElementsFromCollection(ss); |
198 |
> |
} |
199 |
> |
else if (c instanceof PriorityQueue<?>) { |
200 |
> |
PriorityQueue<? extends E> pq = (PriorityQueue<? extends E>) c; |
201 |
> |
this.comparator = (Comparator<? super E>) pq.comparator(); |
202 |
> |
initFromPriorityQueue(pq); |
203 |
> |
} |
204 |
> |
else { |
205 |
> |
this.comparator = null; |
206 |
> |
initFromCollection(c); |
207 |
> |
} |
208 |
> |
} |
209 |
|
|
210 |
< |
queue = (E[]) new Object[initialCapacity + 1]; |
210 |
> |
/** |
211 |
> |
* Creates a {@code PriorityQueue} containing the elements in the |
212 |
> |
* specified priority queue. This priority queue will be |
213 |
> |
* ordered according to the same ordering as the given priority |
214 |
> |
* queue. |
215 |
> |
* |
216 |
> |
* @param c the priority queue whose elements are to be placed |
217 |
> |
* into this priority queue |
218 |
> |
* @throws ClassCastException if elements of {@code c} cannot be |
219 |
> |
* compared to one another according to {@code c}'s |
220 |
> |
* ordering |
221 |
> |
* @throws NullPointerException if the specified priority queue or any |
222 |
> |
* of its elements are null |
223 |
> |
*/ |
224 |
> |
public PriorityQueue(PriorityQueue<? extends E> c) { |
225 |
> |
this.comparator = (Comparator<? super E>) c.comparator(); |
226 |
> |
initFromPriorityQueue(c); |
227 |
> |
} |
228 |
|
|
229 |
< |
if (c instanceof Sorted) { |
230 |
< |
// FIXME: this code assumes too much |
231 |
< |
comparator = ((Sorted)c).comparator(); |
232 |
< |
for (Iterator<E> i = c.iterator(); i.hasNext(); ) |
233 |
< |
queue[++size] = i.next(); |
229 |
> |
/** |
230 |
> |
* Creates a {@code PriorityQueue} containing the elements in the |
231 |
> |
* specified sorted set. This priority queue will be ordered |
232 |
> |
* according to the same ordering as the given sorted set. |
233 |
> |
* |
234 |
> |
* @param c the sorted set whose elements are to be placed |
235 |
> |
* into this priority queue |
236 |
> |
* @throws ClassCastException if elements of the specified sorted |
237 |
> |
* set cannot be compared to one another according to the |
238 |
> |
* sorted set's ordering |
239 |
> |
* @throws NullPointerException if the specified sorted set or any |
240 |
> |
* of its elements are null |
241 |
> |
*/ |
242 |
> |
public PriorityQueue(SortedSet<? extends E> c) { |
243 |
> |
this.comparator = (Comparator<? super E>) c.comparator(); |
244 |
> |
initElementsFromCollection(c); |
245 |
> |
} |
246 |
> |
|
247 |
> |
/** Ensures that queue[0] exists, helping peek() and poll(). */ |
248 |
> |
private static Object[] ensureNonEmpty(Object[] es) { |
249 |
> |
return (es.length > 0) ? es : new Object[1]; |
250 |
> |
} |
251 |
> |
|
252 |
> |
private void initFromPriorityQueue(PriorityQueue<? extends E> c) { |
253 |
> |
if (c.getClass() == PriorityQueue.class) { |
254 |
> |
this.queue = ensureNonEmpty(c.toArray()); |
255 |
> |
this.size = c.size(); |
256 |
|
} else { |
257 |
< |
comparator = null; |
151 |
< |
for (Iterator<E> i = c.iterator(); i.hasNext(); ) |
152 |
< |
add(i.next()); |
257 |
> |
initFromCollection(c); |
258 |
|
} |
259 |
|
} |
260 |
|
|
261 |
< |
// Queue Methods |
261 |
> |
private void initElementsFromCollection(Collection<? extends E> c) { |
262 |
> |
Object[] es = c.toArray(); |
263 |
> |
int len = es.length; |
264 |
> |
// If c.toArray incorrectly doesn't return Object[], copy it. |
265 |
> |
if (es.getClass() != Object[].class) |
266 |
> |
es = Arrays.copyOf(es, len, Object[].class); |
267 |
> |
if (len == 1 || this.comparator != null) |
268 |
> |
for (Object e : es) |
269 |
> |
if (e == null) |
270 |
> |
throw new NullPointerException(); |
271 |
> |
this.queue = ensureNonEmpty(es); |
272 |
> |
this.size = len; |
273 |
> |
} |
274 |
|
|
275 |
|
/** |
276 |
< |
* Add the specified element to this priority queue. |
276 |
> |
* Initializes queue array with elements from the given Collection. |
277 |
|
* |
278 |
< |
* @param element the element to add. |
162 |
< |
* @return <tt>true</tt> |
163 |
< |
* @throws ClassCastException if the specified element cannot be compared |
164 |
< |
* with elements currently in the priority queue according |
165 |
< |
* to the priority queue's ordering. |
166 |
< |
* @throws NullPointerException if the specified element is null. |
278 |
> |
* @param c the collection |
279 |
|
*/ |
280 |
< |
public boolean offer(E element) { |
281 |
< |
if (element == null) |
282 |
< |
throw new NullPointerException(); |
283 |
< |
modCount++; |
172 |
< |
++size; |
280 |
> |
private void initFromCollection(Collection<? extends E> c) { |
281 |
> |
initElementsFromCollection(c); |
282 |
> |
heapify(); |
283 |
> |
} |
284 |
|
|
285 |
< |
// Grow backing store if necessary |
286 |
< |
while (size >= queue.length) { |
287 |
< |
E[] newQueue = (E[]) new Object[2 * queue.length]; |
288 |
< |
System.arraycopy(queue, 0, newQueue, 0, queue.length); |
289 |
< |
queue = newQueue; |
290 |
< |
} |
285 |
> |
/** |
286 |
> |
* Increases the capacity of the array. |
287 |
> |
* |
288 |
> |
* @param minCapacity the desired minimum capacity |
289 |
> |
*/ |
290 |
> |
private void grow(int minCapacity) { |
291 |
> |
int oldCapacity = queue.length; |
292 |
> |
// Double size if small; else grow by 50% |
293 |
> |
int newCapacity = ArraysSupport.newLength(oldCapacity, |
294 |
> |
minCapacity - oldCapacity, /* minimum growth */ |
295 |
> |
oldCapacity < 64 ? oldCapacity + 2 : oldCapacity >> 1 |
296 |
> |
/* preferred growth */); |
297 |
> |
queue = Arrays.copyOf(queue, newCapacity); |
298 |
> |
} |
299 |
|
|
300 |
< |
queue[size] = element; |
301 |
< |
fixUp(size); |
302 |
< |
return true; |
300 |
> |
/** |
301 |
> |
* Inserts the specified element into this priority queue. |
302 |
> |
* |
303 |
> |
* @return {@code true} (as specified by {@link Collection#add}) |
304 |
> |
* @throws ClassCastException if the specified element cannot be |
305 |
> |
* compared with elements currently in this priority queue |
306 |
> |
* according to the priority queue's ordering |
307 |
> |
* @throws NullPointerException if the specified element is null |
308 |
> |
*/ |
309 |
> |
public boolean add(E e) { |
310 |
> |
return offer(e); |
311 |
|
} |
312 |
|
|
313 |
< |
public E poll() { |
314 |
< |
if (size == 0) |
315 |
< |
return null; |
316 |
< |
return remove(1); |
313 |
> |
/** |
314 |
> |
* Inserts the specified element into this priority queue. |
315 |
> |
* |
316 |
> |
* @return {@code true} (as specified by {@link Queue#offer}) |
317 |
> |
* @throws ClassCastException if the specified element cannot be |
318 |
> |
* compared with elements currently in this priority queue |
319 |
> |
* according to the priority queue's ordering |
320 |
> |
* @throws NullPointerException if the specified element is null |
321 |
> |
*/ |
322 |
> |
public boolean offer(E e) { |
323 |
> |
if (e == null) |
324 |
> |
throw new NullPointerException(); |
325 |
> |
modCount++; |
326 |
> |
int i = size; |
327 |
> |
if (i >= queue.length) |
328 |
> |
grow(i + 1); |
329 |
> |
siftUp(i, e); |
330 |
> |
size = i + 1; |
331 |
> |
return true; |
332 |
|
} |
333 |
|
|
334 |
|
public E peek() { |
335 |
< |
return queue[1]; |
335 |
> |
return (E) queue[0]; |
336 |
|
} |
337 |
|
|
338 |
< |
// Collection Methods |
338 |
> |
private int indexOf(Object o) { |
339 |
> |
if (o != null) { |
340 |
> |
final Object[] es = queue; |
341 |
> |
for (int i = 0, n = size; i < n; i++) |
342 |
> |
if (o.equals(es[i])) |
343 |
> |
return i; |
344 |
> |
} |
345 |
> |
return -1; |
346 |
> |
} |
347 |
|
|
348 |
< |
// these first two override just to get the throws docs |
348 |
> |
/** |
349 |
> |
* Removes a single instance of the specified element from this queue, |
350 |
> |
* if it is present. More formally, removes an element {@code e} such |
351 |
> |
* that {@code o.equals(e)}, if this queue contains one or more such |
352 |
> |
* elements. Returns {@code true} if and only if this queue contained |
353 |
> |
* the specified element (or equivalently, if this queue changed as a |
354 |
> |
* result of the call). |
355 |
> |
* |
356 |
> |
* @param o element to be removed from this queue, if present |
357 |
> |
* @return {@code true} if this queue changed as a result of the call |
358 |
> |
*/ |
359 |
> |
public boolean remove(Object o) { |
360 |
> |
int i = indexOf(o); |
361 |
> |
if (i == -1) |
362 |
> |
return false; |
363 |
> |
else { |
364 |
> |
removeAt(i); |
365 |
> |
return true; |
366 |
> |
} |
367 |
> |
} |
368 |
|
|
369 |
|
/** |
370 |
< |
* @throws NullPointerException if the specified element is <tt>null</tt>. |
371 |
< |
* @throws ClassCastException if the specified element cannot be compared |
372 |
< |
* with elements currently in the priority queue according |
204 |
< |
* to the priority queue's ordering. |
370 |
> |
* Identity-based version for use in Itr.remove. |
371 |
> |
* |
372 |
> |
* @param o element to be removed from this queue, if present |
373 |
|
*/ |
374 |
< |
public boolean add(E element) { |
375 |
< |
return super.add(element); |
374 |
> |
void removeEq(Object o) { |
375 |
> |
final Object[] es = queue; |
376 |
> |
for (int i = 0, n = size; i < n; i++) { |
377 |
> |
if (o == es[i]) { |
378 |
> |
removeAt(i); |
379 |
> |
break; |
380 |
> |
} |
381 |
> |
} |
382 |
|
} |
383 |
|
|
384 |
|
/** |
385 |
< |
* @throws NullPointerException if any element is <tt>null</tt>. |
386 |
< |
* @throws ClassCastException if any element cannot be compared |
387 |
< |
* with elements currently in the priority queue according |
388 |
< |
* to the priority queue's ordering. |
385 |
> |
* Returns {@code true} if this queue contains the specified element. |
386 |
> |
* More formally, returns {@code true} if and only if this queue contains |
387 |
> |
* at least one element {@code e} such that {@code o.equals(e)}. |
388 |
> |
* |
389 |
> |
* @param o object to be checked for containment in this queue |
390 |
> |
* @return {@code true} if this queue contains the specified element |
391 |
|
*/ |
392 |
< |
public boolean addAll(Collection<? extends E> c) { |
393 |
< |
return super.addAll(c); |
392 |
> |
public boolean contains(Object o) { |
393 |
> |
return indexOf(o) >= 0; |
394 |
|
} |
395 |
|
|
396 |
< |
public boolean remove(Object o) { |
397 |
< |
if (o == null) |
398 |
< |
return false; |
396 |
> |
/** |
397 |
> |
* Returns an array containing all of the elements in this queue. |
398 |
> |
* The elements are in no particular order. |
399 |
> |
* |
400 |
> |
* <p>The returned array will be "safe" in that no references to it are |
401 |
> |
* maintained by this queue. (In other words, this method must allocate |
402 |
> |
* a new array). The caller is thus free to modify the returned array. |
403 |
> |
* |
404 |
> |
* <p>This method acts as bridge between array-based and collection-based |
405 |
> |
* APIs. |
406 |
> |
* |
407 |
> |
* @return an array containing all of the elements in this queue |
408 |
> |
*/ |
409 |
> |
public Object[] toArray() { |
410 |
> |
return Arrays.copyOf(queue, size); |
411 |
> |
} |
412 |
|
|
413 |
< |
if (comparator == null) { |
414 |
< |
for (int i = 1; i <= size; i++) { |
415 |
< |
if (((Comparable)queue[i]).compareTo(o) == 0) { |
416 |
< |
remove(i); |
417 |
< |
return true; |
418 |
< |
} |
419 |
< |
} |
420 |
< |
} else { |
421 |
< |
for (int i = 1; i <= size; i++) { |
422 |
< |
if (comparator.compare(queue[i], (E)o) == 0) { |
423 |
< |
remove(i); |
424 |
< |
return true; |
425 |
< |
} |
426 |
< |
} |
427 |
< |
} |
428 |
< |
return false; |
413 |
> |
/** |
414 |
> |
* Returns an array containing all of the elements in this queue; the |
415 |
> |
* runtime type of the returned array is that of the specified array. |
416 |
> |
* The returned array elements are in no particular order. |
417 |
> |
* If the queue fits in the specified array, it is returned therein. |
418 |
> |
* Otherwise, a new array is allocated with the runtime type of the |
419 |
> |
* specified array and the size of this queue. |
420 |
> |
* |
421 |
> |
* <p>If the queue fits in the specified array with room to spare |
422 |
> |
* (i.e., the array has more elements than the queue), the element in |
423 |
> |
* the array immediately following the end of the collection is set to |
424 |
> |
* {@code null}. |
425 |
> |
* |
426 |
> |
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
427 |
> |
* array-based and collection-based APIs. Further, this method allows |
428 |
> |
* precise control over the runtime type of the output array, and may, |
429 |
> |
* under certain circumstances, be used to save allocation costs. |
430 |
> |
* |
431 |
> |
* <p>Suppose {@code x} is a queue known to contain only strings. |
432 |
> |
* The following code can be used to dump the queue into a newly |
433 |
> |
* allocated array of {@code String}: |
434 |
> |
* |
435 |
> |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
436 |
> |
* |
437 |
> |
* Note that {@code toArray(new Object[0])} is identical in function to |
438 |
> |
* {@code toArray()}. |
439 |
> |
* |
440 |
> |
* @param a the array into which the elements of the queue are to |
441 |
> |
* be stored, if it is big enough; otherwise, a new array of the |
442 |
> |
* same runtime type is allocated for this purpose. |
443 |
> |
* @return an array containing all of the elements in this queue |
444 |
> |
* @throws ArrayStoreException if the runtime type of the specified array |
445 |
> |
* is not a supertype of the runtime type of every element in |
446 |
> |
* this queue |
447 |
> |
* @throws NullPointerException if the specified array is null |
448 |
> |
*/ |
449 |
> |
public <T> T[] toArray(T[] a) { |
450 |
> |
final int size = this.size; |
451 |
> |
if (a.length < size) |
452 |
> |
// Make a new array of a's runtime type, but my contents: |
453 |
> |
return (T[]) Arrays.copyOf(queue, size, a.getClass()); |
454 |
> |
System.arraycopy(queue, 0, a, 0, size); |
455 |
> |
if (a.length > size) |
456 |
> |
a[size] = null; |
457 |
> |
return a; |
458 |
|
} |
459 |
|
|
460 |
+ |
/** |
461 |
+ |
* Returns an iterator over the elements in this queue. The iterator |
462 |
+ |
* does not return the elements in any particular order. |
463 |
+ |
* |
464 |
+ |
* @return an iterator over the elements in this queue |
465 |
+ |
*/ |
466 |
|
public Iterator<E> iterator() { |
467 |
|
return new Itr(); |
468 |
|
} |
469 |
|
|
470 |
< |
private class Itr implements Iterator<E> { |
470 |
> |
private final class Itr implements Iterator<E> { |
471 |
|
/** |
472 |
|
* Index (into queue array) of element to be returned by |
473 |
|
* subsequent call to next. |
474 |
|
*/ |
475 |
< |
private int cursor = 1; |
475 |
> |
private int cursor; |
476 |
> |
|
477 |
> |
/** |
478 |
> |
* Index of element returned by most recent call to next, |
479 |
> |
* unless that element came from the forgetMeNot list. |
480 |
> |
* Set to -1 if element is deleted by a call to remove. |
481 |
> |
*/ |
482 |
> |
private int lastRet = -1; |
483 |
|
|
484 |
|
/** |
485 |
< |
* Index of element returned by most recent call to next or |
486 |
< |
* previous. Reset to 0 if this element is deleted by a call |
487 |
< |
* to remove. |
485 |
> |
* A queue of elements that were moved from the unvisited portion of |
486 |
> |
* the heap into the visited portion as a result of "unlucky" element |
487 |
> |
* removals during the iteration. (Unlucky element removals are those |
488 |
> |
* that require a siftup instead of a siftdown.) We must visit all of |
489 |
> |
* the elements in this list to complete the iteration. We do this |
490 |
> |
* after we've completed the "normal" iteration. |
491 |
> |
* |
492 |
> |
* We expect that most iterations, even those involving removals, |
493 |
> |
* will not need to store elements in this field. |
494 |
|
*/ |
495 |
< |
private int lastRet = 0; |
495 |
> |
private ArrayDeque<E> forgetMeNot; |
496 |
> |
|
497 |
> |
/** |
498 |
> |
* Element returned by the most recent call to next iff that |
499 |
> |
* element was drawn from the forgetMeNot list. |
500 |
> |
*/ |
501 |
> |
private E lastRetElt; |
502 |
|
|
503 |
|
/** |
504 |
|
* The modCount value that the iterator believes that the backing |
505 |
< |
* List should have. If this expectation is violated, the iterator |
505 |
> |
* Queue should have. If this expectation is violated, the iterator |
506 |
|
* has detected concurrent modification. |
507 |
|
*/ |
508 |
|
private int expectedModCount = modCount; |
509 |
|
|
510 |
+ |
Itr() {} // prevent access constructor creation |
511 |
+ |
|
512 |
|
public boolean hasNext() { |
513 |
< |
return cursor <= size; |
513 |
> |
return cursor < size || |
514 |
> |
(forgetMeNot != null && !forgetMeNot.isEmpty()); |
515 |
|
} |
516 |
|
|
517 |
|
public E next() { |
518 |
< |
checkForComodification(); |
519 |
< |
if (cursor > size) |
520 |
< |
throw new NoSuchElementException(); |
521 |
< |
E result = queue[cursor]; |
522 |
< |
lastRet = cursor++; |
523 |
< |
return result; |
518 |
> |
if (expectedModCount != modCount) |
519 |
> |
throw new ConcurrentModificationException(); |
520 |
> |
if (cursor < size) |
521 |
> |
return (E) queue[lastRet = cursor++]; |
522 |
> |
if (forgetMeNot != null) { |
523 |
> |
lastRet = -1; |
524 |
> |
lastRetElt = forgetMeNot.poll(); |
525 |
> |
if (lastRetElt != null) |
526 |
> |
return lastRetElt; |
527 |
> |
} |
528 |
> |
throw new NoSuchElementException(); |
529 |
|
} |
530 |
|
|
531 |
|
public void remove() { |
532 |
< |
if (lastRet == 0) |
532 |
> |
if (expectedModCount != modCount) |
533 |
> |
throw new ConcurrentModificationException(); |
534 |
> |
if (lastRet != -1) { |
535 |
> |
E moved = PriorityQueue.this.removeAt(lastRet); |
536 |
> |
lastRet = -1; |
537 |
> |
if (moved == null) |
538 |
> |
cursor--; |
539 |
> |
else { |
540 |
> |
if (forgetMeNot == null) |
541 |
> |
forgetMeNot = new ArrayDeque<>(); |
542 |
> |
forgetMeNot.add(moved); |
543 |
> |
} |
544 |
> |
} else if (lastRetElt != null) { |
545 |
> |
PriorityQueue.this.removeEq(lastRetElt); |
546 |
> |
lastRetElt = null; |
547 |
> |
} else { |
548 |
|
throw new IllegalStateException(); |
549 |
< |
checkForComodification(); |
284 |
< |
|
285 |
< |
PriorityQueue.this.remove(lastRet); |
286 |
< |
if (lastRet < cursor) |
287 |
< |
cursor--; |
288 |
< |
lastRet = 0; |
549 |
> |
} |
550 |
|
expectedModCount = modCount; |
551 |
|
} |
291 |
– |
|
292 |
– |
final void checkForComodification() { |
293 |
– |
if (modCount != expectedModCount) |
294 |
– |
throw new ConcurrentModificationException(); |
295 |
– |
} |
552 |
|
} |
553 |
|
|
298 |
– |
/** |
299 |
– |
* Returns the number of elements in this priority queue. |
300 |
– |
* |
301 |
– |
* @return the number of elements in this priority queue. |
302 |
– |
*/ |
554 |
|
public int size() { |
555 |
|
return size; |
556 |
|
} |
557 |
|
|
558 |
|
/** |
559 |
< |
* Remove all elements from the priority queue. |
559 |
> |
* Removes all of the elements from this priority queue. |
560 |
> |
* The queue will be empty after this call returns. |
561 |
|
*/ |
562 |
|
public void clear() { |
563 |
|
modCount++; |
564 |
+ |
final Object[] es = queue; |
565 |
+ |
for (int i = 0, n = size; i < n; i++) |
566 |
+ |
es[i] = null; |
567 |
+ |
size = 0; |
568 |
+ |
} |
569 |
|
|
570 |
< |
// Null out element references to prevent memory leak |
571 |
< |
for (int i=1; i<=size; i++) |
572 |
< |
queue[i] = null; |
570 |
> |
public E poll() { |
571 |
> |
final Object[] es; |
572 |
> |
final E result; |
573 |
|
|
574 |
< |
size = 0; |
574 |
> |
if ((result = (E) ((es = queue)[0])) != null) { |
575 |
> |
modCount++; |
576 |
> |
final int n; |
577 |
> |
final E x = (E) es[(n = --size)]; |
578 |
> |
es[n] = null; |
579 |
> |
if (n > 0) { |
580 |
> |
final Comparator<? super E> cmp; |
581 |
> |
if ((cmp = comparator) == null) |
582 |
> |
siftDownComparable(0, x, es, n); |
583 |
> |
else |
584 |
> |
siftDownUsingComparator(0, x, es, n, cmp); |
585 |
> |
} |
586 |
> |
} |
587 |
> |
return result; |
588 |
|
} |
589 |
|
|
590 |
|
/** |
591 |
< |
* Removes and returns the ith element from queue. Recall |
322 |
< |
* that queue is one-based, so 1 <= i <= size. |
591 |
> |
* Removes the ith element from queue. |
592 |
|
* |
593 |
< |
* XXX: Could further special-case i==size, but is it worth it? |
594 |
< |
* XXX: Could special-case i==0, but is it worth it? |
595 |
< |
*/ |
596 |
< |
private E remove(int i) { |
597 |
< |
assert i <= size; |
593 |
> |
* Normally this method leaves the elements at up to i-1, |
594 |
> |
* inclusive, untouched. Under these circumstances, it returns |
595 |
> |
* null. Occasionally, in order to maintain the heap invariant, |
596 |
> |
* it must swap a later element of the list with one earlier than |
597 |
> |
* i. Under these circumstances, this method returns the element |
598 |
> |
* that was previously at the end of the list and is now at some |
599 |
> |
* position before i. This fact is used by iterator.remove so as to |
600 |
> |
* avoid missing traversing elements. |
601 |
> |
*/ |
602 |
> |
E removeAt(int i) { |
603 |
> |
// assert i >= 0 && i < size; |
604 |
> |
final Object[] es = queue; |
605 |
|
modCount++; |
606 |
< |
|
607 |
< |
E result = queue[i]; |
608 |
< |
queue[i] = queue[size]; |
609 |
< |
queue[size--] = null; // Drop extra ref to prevent memory leak |
610 |
< |
if (i <= size) |
611 |
< |
fixDown(i); |
612 |
< |
return result; |
606 |
> |
int s = --size; |
607 |
> |
if (s == i) // removed last element |
608 |
> |
es[i] = null; |
609 |
> |
else { |
610 |
> |
E moved = (E) es[s]; |
611 |
> |
es[s] = null; |
612 |
> |
siftDown(i, moved); |
613 |
> |
if (es[i] == moved) { |
614 |
> |
siftUp(i, moved); |
615 |
> |
if (es[i] != moved) |
616 |
> |
return moved; |
617 |
> |
} |
618 |
> |
} |
619 |
> |
return null; |
620 |
|
} |
621 |
|
|
622 |
|
/** |
623 |
< |
* Establishes the heap invariant (described above) assuming the heap |
624 |
< |
* satisfies the invariant except possibly for the leaf-node indexed by k |
625 |
< |
* (which may have a nextExecutionTime less than its parent's). |
626 |
< |
* |
627 |
< |
* This method functions by "promoting" queue[k] up the hierarchy |
628 |
< |
* (by swapping it with its parent) repeatedly until queue[k] |
629 |
< |
* is greater than or equal to its parent. |
630 |
< |
*/ |
631 |
< |
private void fixUp(int k) { |
632 |
< |
if (comparator == null) { |
633 |
< |
while (k > 1) { |
634 |
< |
int j = k >> 1; |
635 |
< |
if (((Comparable)queue[j]).compareTo(queue[k]) <= 0) |
636 |
< |
break; |
637 |
< |
E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
638 |
< |
k = j; |
639 |
< |
} |
640 |
< |
} else { |
641 |
< |
while (k > 1) { |
642 |
< |
int j = k >> 1; |
643 |
< |
if (comparator.compare(queue[j], queue[k]) <= 0) |
644 |
< |
break; |
645 |
< |
E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
646 |
< |
k = j; |
647 |
< |
} |
623 |
> |
* Inserts item x at position k, maintaining heap invariant by |
624 |
> |
* promoting x up the tree until it is greater than or equal to |
625 |
> |
* its parent, or is the root. |
626 |
> |
* |
627 |
> |
* To simplify and speed up coercions and comparisons, the |
628 |
> |
* Comparable and Comparator versions are separated into different |
629 |
> |
* methods that are otherwise identical. (Similarly for siftDown.) |
630 |
> |
* |
631 |
> |
* @param k the position to fill |
632 |
> |
* @param x the item to insert |
633 |
> |
*/ |
634 |
> |
private void siftUp(int k, E x) { |
635 |
> |
if (comparator != null) |
636 |
> |
siftUpUsingComparator(k, x, queue, comparator); |
637 |
> |
else |
638 |
> |
siftUpComparable(k, x, queue); |
639 |
> |
} |
640 |
> |
|
641 |
> |
private static <T> void siftUpComparable(int k, T x, Object[] es) { |
642 |
> |
Comparable<? super T> key = (Comparable<? super T>) x; |
643 |
> |
while (k > 0) { |
644 |
> |
int parent = (k - 1) >>> 1; |
645 |
> |
Object e = es[parent]; |
646 |
> |
if (key.compareTo((T) e) >= 0) |
647 |
> |
break; |
648 |
> |
es[k] = e; |
649 |
> |
k = parent; |
650 |
> |
} |
651 |
> |
es[k] = key; |
652 |
> |
} |
653 |
> |
|
654 |
> |
private static <T> void siftUpUsingComparator( |
655 |
> |
int k, T x, Object[] es, Comparator<? super T> cmp) { |
656 |
> |
while (k > 0) { |
657 |
> |
int parent = (k - 1) >>> 1; |
658 |
> |
Object e = es[parent]; |
659 |
> |
if (cmp.compare(x, (T) e) >= 0) |
660 |
> |
break; |
661 |
> |
es[k] = e; |
662 |
> |
k = parent; |
663 |
|
} |
664 |
+ |
es[k] = x; |
665 |
|
} |
666 |
|
|
667 |
|
/** |
668 |
< |
* Establishes the heap invariant (described above) in the subtree |
669 |
< |
* rooted at k, which is assumed to satisfy the heap invariant except |
670 |
< |
* possibly for node k itself (which may be greater than its children). |
671 |
< |
* |
672 |
< |
* This method functions by "demoting" queue[k] down the hierarchy |
673 |
< |
* (by swapping it with its smaller child) repeatedly until queue[k] |
674 |
< |
* is less than or equal to its children. |
675 |
< |
*/ |
676 |
< |
private void fixDown(int k) { |
677 |
< |
int j; |
678 |
< |
if (comparator == null) { |
679 |
< |
while ((j = k << 1) <= size) { |
680 |
< |
if (j<size && ((Comparable)queue[j]).compareTo(queue[j+1]) > 0) |
681 |
< |
j++; // j indexes smallest kid |
682 |
< |
if (((Comparable)queue[k]).compareTo(queue[j]) <= 0) |
683 |
< |
break; |
684 |
< |
E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
685 |
< |
k = j; |
686 |
< |
} |
687 |
< |
} else { |
688 |
< |
while ((j = k << 1) <= size) { |
689 |
< |
if (j < size && comparator.compare(queue[j], queue[j+1]) > 0) |
690 |
< |
j++; // j indexes smallest kid |
691 |
< |
if (comparator.compare(queue[k], queue[j]) <= 0) |
692 |
< |
break; |
693 |
< |
E tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
694 |
< |
k = j; |
695 |
< |
} |
668 |
> |
* Inserts item x at position k, maintaining heap invariant by |
669 |
> |
* demoting x down the tree repeatedly until it is less than or |
670 |
> |
* equal to its children or is a leaf. |
671 |
> |
* |
672 |
> |
* @param k the position to fill |
673 |
> |
* @param x the item to insert |
674 |
> |
*/ |
675 |
> |
private void siftDown(int k, E x) { |
676 |
> |
if (comparator != null) |
677 |
> |
siftDownUsingComparator(k, x, queue, size, comparator); |
678 |
> |
else |
679 |
> |
siftDownComparable(k, x, queue, size); |
680 |
> |
} |
681 |
> |
|
682 |
> |
private static <T> void siftDownComparable(int k, T x, Object[] es, int n) { |
683 |
> |
// assert n > 0; |
684 |
> |
Comparable<? super T> key = (Comparable<? super T>)x; |
685 |
> |
int half = n >>> 1; // loop while a non-leaf |
686 |
> |
while (k < half) { |
687 |
> |
int child = (k << 1) + 1; // assume left child is least |
688 |
> |
Object c = es[child]; |
689 |
> |
int right = child + 1; |
690 |
> |
if (right < n && |
691 |
> |
((Comparable<? super T>) c).compareTo((T) es[right]) > 0) |
692 |
> |
c = es[child = right]; |
693 |
> |
if (key.compareTo((T) c) <= 0) |
694 |
> |
break; |
695 |
> |
es[k] = c; |
696 |
> |
k = child; |
697 |
|
} |
698 |
+ |
es[k] = key; |
699 |
|
} |
700 |
|
|
701 |
< |
public Comparator comparator() { |
701 |
> |
private static <T> void siftDownUsingComparator( |
702 |
> |
int k, T x, Object[] es, int n, Comparator<? super T> cmp) { |
703 |
> |
// assert n > 0; |
704 |
> |
int half = n >>> 1; |
705 |
> |
while (k < half) { |
706 |
> |
int child = (k << 1) + 1; |
707 |
> |
Object c = es[child]; |
708 |
> |
int right = child + 1; |
709 |
> |
if (right < n && cmp.compare((T) c, (T) es[right]) > 0) |
710 |
> |
c = es[child = right]; |
711 |
> |
if (cmp.compare(x, (T) c) <= 0) |
712 |
> |
break; |
713 |
> |
es[k] = c; |
714 |
> |
k = child; |
715 |
> |
} |
716 |
> |
es[k] = x; |
717 |
> |
} |
718 |
> |
|
719 |
> |
/** |
720 |
> |
* Establishes the heap invariant (described above) in the entire tree, |
721 |
> |
* assuming nothing about the order of the elements prior to the call. |
722 |
> |
* This classic algorithm due to Floyd (1964) is known to be O(size). |
723 |
> |
*/ |
724 |
> |
private void heapify() { |
725 |
> |
final Object[] es = queue; |
726 |
> |
int n = size, i = (n >>> 1) - 1; |
727 |
> |
final Comparator<? super E> cmp; |
728 |
> |
if ((cmp = comparator) == null) |
729 |
> |
for (; i >= 0; i--) |
730 |
> |
siftDownComparable(i, (E) es[i], es, n); |
731 |
> |
else |
732 |
> |
for (; i >= 0; i--) |
733 |
> |
siftDownUsingComparator(i, (E) es[i], es, n, cmp); |
734 |
> |
} |
735 |
> |
|
736 |
> |
/** |
737 |
> |
* Returns the comparator used to order the elements in this |
738 |
> |
* queue, or {@code null} if this queue is sorted according to |
739 |
> |
* the {@linkplain Comparable natural ordering} of its elements. |
740 |
> |
* |
741 |
> |
* @return the comparator used to order this queue, or |
742 |
> |
* {@code null} if this queue is sorted according to the |
743 |
> |
* natural ordering of its elements |
744 |
> |
*/ |
745 |
> |
public Comparator<? super E> comparator() { |
746 |
|
return comparator; |
747 |
|
} |
748 |
|
|
749 |
|
/** |
750 |
< |
* Save the state of the instance to a stream (that |
406 |
< |
* is, serialize it). |
750 |
> |
* Saves this queue to a stream (that is, serializes it). |
751 |
|
* |
408 |
– |
* @serialData The length of the array backing the instance is |
409 |
– |
* emitted (int), followed by all of its elements (each an |
410 |
– |
* <tt>Object</tt>) in the proper order. |
752 |
|
* @param s the stream |
753 |
+ |
* @throws java.io.IOException if an I/O error occurs |
754 |
+ |
* @serialData The length of the array backing the instance is |
755 |
+ |
* emitted (int), followed by all of its elements |
756 |
+ |
* (each an {@code Object}) in the proper order. |
757 |
|
*/ |
758 |
< |
private synchronized void writeObject(java.io.ObjectOutputStream s) |
759 |
< |
throws java.io.IOException{ |
758 |
> |
private void writeObject(java.io.ObjectOutputStream s) |
759 |
> |
throws java.io.IOException { |
760 |
|
// Write out element count, and any hidden stuff |
761 |
|
s.defaultWriteObject(); |
762 |
|
|
763 |
< |
// Write out array length |
764 |
< |
s.writeInt(queue.length); |
763 |
> |
// Write out array length, for compatibility with 1.5 version |
764 |
> |
s.writeInt(Math.max(2, size + 1)); |
765 |
|
|
766 |
< |
// Write out all elements in the proper order. |
767 |
< |
for (int i=0; i<size; i++) |
768 |
< |
s.writeObject(queue[i]); |
766 |
> |
// Write out all elements in the "proper order". |
767 |
> |
final Object[] es = queue; |
768 |
> |
for (int i = 0, n = size; i < n; i++) |
769 |
> |
s.writeObject(es[i]); |
770 |
|
} |
771 |
|
|
772 |
|
/** |
773 |
< |
* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is, |
774 |
< |
* deserialize it). |
773 |
> |
* Reconstitutes the {@code PriorityQueue} instance from a stream |
774 |
> |
* (that is, deserializes it). |
775 |
> |
* |
776 |
|
* @param s the stream |
777 |
+ |
* @throws ClassNotFoundException if the class of a serialized object |
778 |
+ |
* could not be found |
779 |
+ |
* @throws java.io.IOException if an I/O error occurs |
780 |
|
*/ |
781 |
< |
private synchronized void readObject(java.io.ObjectInputStream s) |
781 |
> |
private void readObject(java.io.ObjectInputStream s) |
782 |
|
throws java.io.IOException, ClassNotFoundException { |
783 |
|
// Read in size, and any hidden stuff |
784 |
|
s.defaultReadObject(); |
785 |
|
|
786 |
< |
// Read in array length and allocate array |
787 |
< |
int arrayLength = s.readInt(); |
788 |
< |
queue = (E[]) new Object[arrayLength]; |
789 |
< |
|
790 |
< |
// Read in all elements in the proper order. |
791 |
< |
for (int i=0; i<size; i++) |
792 |
< |
queue[i] = (E)s.readObject(); |
786 |
> |
// Read in (and discard) array length |
787 |
> |
s.readInt(); |
788 |
> |
|
789 |
> |
jsr166.Platform.checkArray(s, Object[].class, size); |
790 |
> |
final Object[] es = queue = new Object[Math.max(size, 1)]; |
791 |
> |
|
792 |
> |
// Read in all elements. |
793 |
> |
for (int i = 0, n = size; i < n; i++) |
794 |
> |
es[i] = s.readObject(); |
795 |
> |
|
796 |
> |
// Elements are guaranteed to be in "proper order", but the |
797 |
> |
// spec has never explained what that might be. |
798 |
> |
heapify(); |
799 |
|
} |
800 |
|
|
801 |
< |
} |
801 |
> |
/** |
802 |
> |
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> |
803 |
> |
* and <em>fail-fast</em> {@link Spliterator} over the elements in this |
804 |
> |
* queue. The spliterator does not traverse elements in any particular order |
805 |
> |
* (the {@link Spliterator#ORDERED ORDERED} characteristic is not reported). |
806 |
> |
* |
807 |
> |
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, |
808 |
> |
* {@link Spliterator#SUBSIZED}, and {@link Spliterator#NONNULL}. |
809 |
> |
* Overriding implementations should document the reporting of additional |
810 |
> |
* characteristic values. |
811 |
> |
* |
812 |
> |
* @return a {@code Spliterator} over the elements in this queue |
813 |
> |
* @since 1.8 |
814 |
> |
*/ |
815 |
> |
public final Spliterator<E> spliterator() { |
816 |
> |
return new PriorityQueueSpliterator(0, -1, 0); |
817 |
> |
} |
818 |
> |
|
819 |
> |
final class PriorityQueueSpliterator implements Spliterator<E> { |
820 |
> |
private int index; // current index, modified on advance/split |
821 |
> |
private int fence; // -1 until first use |
822 |
> |
private int expectedModCount; // initialized when fence set |
823 |
> |
|
824 |
> |
/** Creates new spliterator covering the given range. */ |
825 |
> |
PriorityQueueSpliterator(int origin, int fence, int expectedModCount) { |
826 |
> |
this.index = origin; |
827 |
> |
this.fence = fence; |
828 |
> |
this.expectedModCount = expectedModCount; |
829 |
> |
} |
830 |
> |
|
831 |
> |
private int getFence() { // initialize fence to size on first use |
832 |
> |
int hi; |
833 |
> |
if ((hi = fence) < 0) { |
834 |
> |
expectedModCount = modCount; |
835 |
> |
hi = fence = size; |
836 |
> |
} |
837 |
> |
return hi; |
838 |
> |
} |
839 |
> |
|
840 |
> |
public PriorityQueueSpliterator trySplit() { |
841 |
> |
int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; |
842 |
> |
return (lo >= mid) ? null : |
843 |
> |
new PriorityQueueSpliterator(lo, index = mid, expectedModCount); |
844 |
> |
} |
845 |
> |
|
846 |
> |
public void forEachRemaining(Consumer<? super E> action) { |
847 |
> |
if (action == null) |
848 |
> |
throw new NullPointerException(); |
849 |
> |
if (fence < 0) { fence = size; expectedModCount = modCount; } |
850 |
> |
final Object[] es = queue; |
851 |
> |
int i, hi; E e; |
852 |
> |
for (i = index, index = hi = fence; i < hi; i++) { |
853 |
> |
if ((e = (E) es[i]) == null) |
854 |
> |
break; // must be CME |
855 |
> |
action.accept(e); |
856 |
> |
} |
857 |
> |
if (modCount != expectedModCount) |
858 |
> |
throw new ConcurrentModificationException(); |
859 |
> |
} |
860 |
> |
|
861 |
> |
public boolean tryAdvance(Consumer<? super E> action) { |
862 |
> |
if (action == null) |
863 |
> |
throw new NullPointerException(); |
864 |
> |
if (fence < 0) { fence = size; expectedModCount = modCount; } |
865 |
> |
int i; |
866 |
> |
if ((i = index) < fence) { |
867 |
> |
index = i + 1; |
868 |
> |
E e; |
869 |
> |
if ((e = (E) queue[i]) == null |
870 |
> |
|| modCount != expectedModCount) |
871 |
> |
throw new ConcurrentModificationException(); |
872 |
> |
action.accept(e); |
873 |
> |
return true; |
874 |
> |
} |
875 |
> |
return false; |
876 |
> |
} |
877 |
> |
|
878 |
> |
public long estimateSize() { |
879 |
> |
return getFence() - index; |
880 |
> |
} |
881 |
|
|
882 |
+ |
public int characteristics() { |
883 |
+ |
return Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.NONNULL; |
884 |
+ |
} |
885 |
+ |
} |
886 |
+ |
|
887 |
+ |
/** |
888 |
+ |
* @throws NullPointerException {@inheritDoc} |
889 |
+ |
*/ |
890 |
+ |
public boolean removeIf(Predicate<? super E> filter) { |
891 |
+ |
Objects.requireNonNull(filter); |
892 |
+ |
return bulkRemove(filter); |
893 |
+ |
} |
894 |
+ |
|
895 |
+ |
/** |
896 |
+ |
* @throws NullPointerException {@inheritDoc} |
897 |
+ |
*/ |
898 |
+ |
public boolean removeAll(Collection<?> c) { |
899 |
+ |
Objects.requireNonNull(c); |
900 |
+ |
return bulkRemove(e -> c.contains(e)); |
901 |
+ |
} |
902 |
+ |
|
903 |
+ |
/** |
904 |
+ |
* @throws NullPointerException {@inheritDoc} |
905 |
+ |
*/ |
906 |
+ |
public boolean retainAll(Collection<?> c) { |
907 |
+ |
Objects.requireNonNull(c); |
908 |
+ |
return bulkRemove(e -> !c.contains(e)); |
909 |
+ |
} |
910 |
+ |
|
911 |
+ |
// A tiny bit set implementation |
912 |
+ |
|
913 |
+ |
private static long[] nBits(int n) { |
914 |
+ |
return new long[((n - 1) >> 6) + 1]; |
915 |
+ |
} |
916 |
+ |
private static void setBit(long[] bits, int i) { |
917 |
+ |
bits[i >> 6] |= 1L << i; |
918 |
+ |
} |
919 |
+ |
private static boolean isClear(long[] bits, int i) { |
920 |
+ |
return (bits[i >> 6] & (1L << i)) == 0; |
921 |
+ |
} |
922 |
+ |
|
923 |
+ |
/** Implementation of bulk remove methods. */ |
924 |
+ |
private boolean bulkRemove(Predicate<? super E> filter) { |
925 |
+ |
final int expectedModCount = ++modCount; |
926 |
+ |
final Object[] es = queue; |
927 |
+ |
final int end = size; |
928 |
+ |
int i; |
929 |
+ |
// Optimize for initial run of survivors |
930 |
+ |
for (i = 0; i < end && !filter.test((E) es[i]); i++) |
931 |
+ |
; |
932 |
+ |
if (i >= end) { |
933 |
+ |
if (modCount != expectedModCount) |
934 |
+ |
throw new ConcurrentModificationException(); |
935 |
+ |
return false; |
936 |
+ |
} |
937 |
+ |
// Tolerate predicates that reentrantly access the collection for |
938 |
+ |
// read (but writers still get CME), so traverse once to find |
939 |
+ |
// elements to delete, a second pass to physically expunge. |
940 |
+ |
final int beg = i; |
941 |
+ |
final long[] deathRow = nBits(end - beg); |
942 |
+ |
deathRow[0] = 1L; // set bit 0 |
943 |
+ |
for (i = beg + 1; i < end; i++) |
944 |
+ |
if (filter.test((E) es[i])) |
945 |
+ |
setBit(deathRow, i - beg); |
946 |
+ |
if (modCount != expectedModCount) |
947 |
+ |
throw new ConcurrentModificationException(); |
948 |
+ |
int w = beg; |
949 |
+ |
for (i = beg; i < end; i++) |
950 |
+ |
if (isClear(deathRow, i - beg)) |
951 |
+ |
es[w++] = es[i]; |
952 |
+ |
for (i = size = w; i < end; i++) |
953 |
+ |
es[i] = null; |
954 |
+ |
heapify(); |
955 |
+ |
return true; |
956 |
+ |
} |
957 |
+ |
|
958 |
+ |
/** |
959 |
+ |
* @throws NullPointerException {@inheritDoc} |
960 |
+ |
*/ |
961 |
+ |
public void forEach(Consumer<? super E> action) { |
962 |
+ |
Objects.requireNonNull(action); |
963 |
+ |
final int expectedModCount = modCount; |
964 |
+ |
final Object[] es = queue; |
965 |
+ |
for (int i = 0, n = size; i < n; i++) |
966 |
+ |
action.accept((E) es[i]); |
967 |
+ |
if (expectedModCount != modCount) |
968 |
+ |
throw new ConcurrentModificationException(); |
969 |
+ |
} |
970 |
+ |
} |