1 |
dl |
1.1 |
/* |
2 |
dl |
1.47 |
* Written by Josh Bloch of Google Inc. and released to the public domain, |
3 |
|
|
* as explained at http://creativecommons.org/publicdomain/zero/1.0/. |
4 |
dl |
1.1 |
*/ |
5 |
|
|
|
6 |
|
|
package java.util; |
7 |
dl |
1.47 |
import java.io.Serializable; |
8 |
|
|
import java.util.function.Consumer; |
9 |
dl |
1.41 |
import java.util.stream.Stream; |
10 |
|
|
import java.util.stream.Streams; |
11 |
dl |
1.1 |
|
12 |
|
|
/** |
13 |
|
|
* Resizable-array implementation of the {@link Deque} interface. Array |
14 |
|
|
* deques have no capacity restrictions; they grow as necessary to support |
15 |
|
|
* usage. They are not thread-safe; in the absence of external |
16 |
|
|
* synchronization, they do not support concurrent access by multiple threads. |
17 |
|
|
* Null elements are prohibited. This class is likely to be faster than |
18 |
dl |
1.2 |
* {@link Stack} when used as a stack, and faster than {@link LinkedList} |
19 |
dl |
1.1 |
* when used as a queue. |
20 |
|
|
* |
21 |
jsr166 |
1.43 |
* <p>Most {@code ArrayDeque} operations run in amortized constant time. |
22 |
dl |
1.41 |
* Exceptions include {@link #remove(Object) remove}, {@link |
23 |
|
|
* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence |
24 |
|
|
* removeLastOccurrence}, {@link #contains contains}, {@link #iterator |
25 |
|
|
* iterator.remove()}, and the bulk operations, all of which run in linear |
26 |
|
|
* time. |
27 |
|
|
* |
28 |
jsr166 |
1.43 |
* <p>The iterators returned by this class's {@code iterator} method are |
29 |
dl |
1.41 |
* <i>fail-fast</i>: If the deque is modified at any time after the iterator |
30 |
jsr166 |
1.43 |
* is created, in any way except through the iterator's own {@code remove} |
31 |
dl |
1.41 |
* method, the iterator will generally throw a {@link |
32 |
jsr166 |
1.7 |
* ConcurrentModificationException}. Thus, in the face of concurrent |
33 |
|
|
* modification, the iterator fails quickly and cleanly, rather than risking |
34 |
|
|
* arbitrary, non-deterministic behavior at an undetermined time in the |
35 |
|
|
* future. |
36 |
dl |
1.1 |
* |
37 |
|
|
* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed |
38 |
|
|
* as it is, generally speaking, impossible to make any hard guarantees in the |
39 |
|
|
* presence of unsynchronized concurrent modification. Fail-fast iterators |
40 |
jsr166 |
1.43 |
* throw {@code ConcurrentModificationException} on a best-effort basis. |
41 |
dl |
1.1 |
* Therefore, it would be wrong to write a program that depended on this |
42 |
|
|
* exception for its correctness: <i>the fail-fast behavior of iterators |
43 |
|
|
* should be used only to detect bugs.</i> |
44 |
|
|
* |
45 |
|
|
* <p>This class and its iterator implement all of the |
46 |
jsr166 |
1.9 |
* <em>optional</em> methods of the {@link Collection} and {@link |
47 |
|
|
* Iterator} interfaces. |
48 |
|
|
* |
49 |
|
|
* <p>This class is a member of the |
50 |
jsr166 |
1.29 |
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
51 |
jsr166 |
1.9 |
* Java Collections Framework</a>. |
52 |
dl |
1.1 |
* |
53 |
|
|
* @author Josh Bloch and Doug Lea |
54 |
|
|
* @since 1.6 |
55 |
|
|
* @param <E> the type of elements held in this collection |
56 |
|
|
*/ |
57 |
|
|
public class ArrayDeque<E> extends AbstractCollection<E> |
58 |
dl |
1.47 |
implements Deque<E>, Cloneable, Serializable |
59 |
dl |
1.1 |
{ |
60 |
|
|
/** |
61 |
dl |
1.4 |
* The array in which the elements of the deque are stored. |
62 |
dl |
1.1 |
* The capacity of the deque is the length of this array, which is |
63 |
|
|
* always a power of two. The array is never allowed to become |
64 |
|
|
* full, except transiently within an addX method where it is |
65 |
|
|
* resized (see doubleCapacity) immediately upon becoming full, |
66 |
|
|
* thus avoiding head and tail wrapping around to equal each |
67 |
|
|
* other. We also guarantee that all array cells not holding |
68 |
|
|
* deque elements are always null. |
69 |
|
|
*/ |
70 |
dl |
1.41 |
transient Object[] elements; // non-private to simplify nested class access |
71 |
dl |
1.1 |
|
72 |
|
|
/** |
73 |
|
|
* The index of the element at the head of the deque (which is the |
74 |
|
|
* element that would be removed by remove() or pop()); or an |
75 |
|
|
* arbitrary number equal to tail if the deque is empty. |
76 |
|
|
*/ |
77 |
dl |
1.41 |
transient int head; |
78 |
dl |
1.1 |
|
79 |
|
|
/** |
80 |
|
|
* The index at which the next element would be added to the tail |
81 |
|
|
* of the deque (via addLast(E), add(E), or push(E)). |
82 |
|
|
*/ |
83 |
dl |
1.41 |
transient int tail; |
84 |
dl |
1.1 |
|
85 |
|
|
/** |
86 |
|
|
* The minimum capacity that we'll use for a newly created deque. |
87 |
|
|
* Must be a power of 2. |
88 |
|
|
*/ |
89 |
|
|
private static final int MIN_INITIAL_CAPACITY = 8; |
90 |
|
|
|
91 |
|
|
// ****** Array allocation and resizing utilities ****** |
92 |
|
|
|
93 |
|
|
/** |
94 |
jsr166 |
1.39 |
* Allocates empty array to hold the given number of elements. |
95 |
dl |
1.1 |
* |
96 |
jsr166 |
1.9 |
* @param numElements the number of elements to hold |
97 |
dl |
1.1 |
*/ |
98 |
dl |
1.5 |
private void allocateElements(int numElements) { |
99 |
dl |
1.1 |
int initialCapacity = MIN_INITIAL_CAPACITY; |
100 |
|
|
// Find the best power of two to hold elements. |
101 |
|
|
// Tests "<=" because arrays aren't kept full. |
102 |
|
|
if (numElements >= initialCapacity) { |
103 |
|
|
initialCapacity = numElements; |
104 |
|
|
initialCapacity |= (initialCapacity >>> 1); |
105 |
|
|
initialCapacity |= (initialCapacity >>> 2); |
106 |
|
|
initialCapacity |= (initialCapacity >>> 4); |
107 |
|
|
initialCapacity |= (initialCapacity >>> 8); |
108 |
|
|
initialCapacity |= (initialCapacity >>> 16); |
109 |
|
|
initialCapacity++; |
110 |
|
|
|
111 |
|
|
if (initialCapacity < 0) // Too many elements, must back off |
112 |
|
|
initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements |
113 |
|
|
} |
114 |
jsr166 |
1.34 |
elements = new Object[initialCapacity]; |
115 |
dl |
1.1 |
} |
116 |
|
|
|
117 |
|
|
/** |
118 |
jsr166 |
1.39 |
* Doubles the capacity of this deque. Call only when full, i.e., |
119 |
dl |
1.1 |
* when head and tail have wrapped around to become equal. |
120 |
|
|
*/ |
121 |
|
|
private void doubleCapacity() { |
122 |
dl |
1.5 |
assert head == tail; |
123 |
dl |
1.1 |
int p = head; |
124 |
|
|
int n = elements.length; |
125 |
|
|
int r = n - p; // number of elements to the right of p |
126 |
|
|
int newCapacity = n << 1; |
127 |
|
|
if (newCapacity < 0) |
128 |
|
|
throw new IllegalStateException("Sorry, deque too big"); |
129 |
|
|
Object[] a = new Object[newCapacity]; |
130 |
|
|
System.arraycopy(elements, p, a, 0, r); |
131 |
|
|
System.arraycopy(elements, 0, a, r, p); |
132 |
jsr166 |
1.34 |
elements = a; |
133 |
dl |
1.1 |
head = 0; |
134 |
|
|
tail = n; |
135 |
|
|
} |
136 |
|
|
|
137 |
|
|
/** |
138 |
jsr166 |
1.7 |
* Copies the elements from our element array into the specified array, |
139 |
dl |
1.1 |
* in order (from first to last element in the deque). It is assumed |
140 |
|
|
* that the array is large enough to hold all elements in the deque. |
141 |
|
|
* |
142 |
|
|
* @return its argument |
143 |
|
|
*/ |
144 |
|
|
private <T> T[] copyElements(T[] a) { |
145 |
|
|
if (head < tail) { |
146 |
|
|
System.arraycopy(elements, head, a, 0, size()); |
147 |
|
|
} else if (head > tail) { |
148 |
|
|
int headPortionLen = elements.length - head; |
149 |
|
|
System.arraycopy(elements, head, a, 0, headPortionLen); |
150 |
|
|
System.arraycopy(elements, 0, a, headPortionLen, tail); |
151 |
|
|
} |
152 |
|
|
return a; |
153 |
|
|
} |
154 |
|
|
|
155 |
|
|
/** |
156 |
dl |
1.4 |
* Constructs an empty array deque with an initial capacity |
157 |
dl |
1.1 |
* sufficient to hold 16 elements. |
158 |
|
|
*/ |
159 |
|
|
public ArrayDeque() { |
160 |
jsr166 |
1.34 |
elements = new Object[16]; |
161 |
dl |
1.1 |
} |
162 |
|
|
|
163 |
|
|
/** |
164 |
|
|
* Constructs an empty array deque with an initial capacity |
165 |
|
|
* sufficient to hold the specified number of elements. |
166 |
|
|
* |
167 |
|
|
* @param numElements lower bound on initial capacity of the deque |
168 |
|
|
*/ |
169 |
|
|
public ArrayDeque(int numElements) { |
170 |
|
|
allocateElements(numElements); |
171 |
|
|
} |
172 |
|
|
|
173 |
|
|
/** |
174 |
|
|
* Constructs a deque containing the elements of the specified |
175 |
|
|
* collection, in the order they are returned by the collection's |
176 |
|
|
* iterator. (The first element returned by the collection's |
177 |
|
|
* iterator becomes the first element, or <i>front</i> of the |
178 |
|
|
* deque.) |
179 |
|
|
* |
180 |
|
|
* @param c the collection whose elements are to be placed into the deque |
181 |
|
|
* @throws NullPointerException if the specified collection is null |
182 |
|
|
*/ |
183 |
|
|
public ArrayDeque(Collection<? extends E> c) { |
184 |
|
|
allocateElements(c.size()); |
185 |
|
|
addAll(c); |
186 |
|
|
} |
187 |
|
|
|
188 |
|
|
// The main insertion and extraction methods are addFirst, |
189 |
|
|
// addLast, pollFirst, pollLast. The other methods are defined in |
190 |
|
|
// terms of these. |
191 |
|
|
|
192 |
|
|
/** |
193 |
dl |
1.5 |
* Inserts the specified element at the front of this deque. |
194 |
dl |
1.1 |
* |
195 |
jsr166 |
1.9 |
* @param e the element to add |
196 |
|
|
* @throws NullPointerException if the specified element is null |
197 |
dl |
1.1 |
*/ |
198 |
|
|
public void addFirst(E e) { |
199 |
|
|
if (e == null) |
200 |
|
|
throw new NullPointerException(); |
201 |
|
|
elements[head = (head - 1) & (elements.length - 1)] = e; |
202 |
dl |
1.5 |
if (head == tail) |
203 |
dl |
1.1 |
doubleCapacity(); |
204 |
|
|
} |
205 |
|
|
|
206 |
|
|
/** |
207 |
dl |
1.6 |
* Inserts the specified element at the end of this deque. |
208 |
jsr166 |
1.14 |
* |
209 |
|
|
* <p>This method is equivalent to {@link #add}. |
210 |
dl |
1.1 |
* |
211 |
jsr166 |
1.9 |
* @param e the element to add |
212 |
|
|
* @throws NullPointerException if the specified element is null |
213 |
dl |
1.1 |
*/ |
214 |
|
|
public void addLast(E e) { |
215 |
|
|
if (e == null) |
216 |
|
|
throw new NullPointerException(); |
217 |
|
|
elements[tail] = e; |
218 |
|
|
if ( (tail = (tail + 1) & (elements.length - 1)) == head) |
219 |
|
|
doubleCapacity(); |
220 |
|
|
} |
221 |
|
|
|
222 |
|
|
/** |
223 |
dl |
1.5 |
* Inserts the specified element at the front of this deque. |
224 |
dl |
1.1 |
* |
225 |
jsr166 |
1.9 |
* @param e the element to add |
226 |
jsr166 |
1.40 |
* @return {@code true} (as specified by {@link Deque#offerFirst}) |
227 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
228 |
dl |
1.1 |
*/ |
229 |
|
|
public boolean offerFirst(E e) { |
230 |
|
|
addFirst(e); |
231 |
|
|
return true; |
232 |
|
|
} |
233 |
|
|
|
234 |
|
|
/** |
235 |
dl |
1.6 |
* Inserts the specified element at the end of this deque. |
236 |
dl |
1.1 |
* |
237 |
jsr166 |
1.9 |
* @param e the element to add |
238 |
jsr166 |
1.40 |
* @return {@code true} (as specified by {@link Deque#offerLast}) |
239 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
240 |
dl |
1.1 |
*/ |
241 |
|
|
public boolean offerLast(E e) { |
242 |
|
|
addLast(e); |
243 |
|
|
return true; |
244 |
|
|
} |
245 |
|
|
|
246 |
|
|
/** |
247 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
248 |
dl |
1.1 |
*/ |
249 |
|
|
public E removeFirst() { |
250 |
|
|
E x = pollFirst(); |
251 |
|
|
if (x == null) |
252 |
|
|
throw new NoSuchElementException(); |
253 |
|
|
return x; |
254 |
|
|
} |
255 |
|
|
|
256 |
|
|
/** |
257 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
258 |
dl |
1.1 |
*/ |
259 |
|
|
public E removeLast() { |
260 |
|
|
E x = pollLast(); |
261 |
|
|
if (x == null) |
262 |
|
|
throw new NoSuchElementException(); |
263 |
|
|
return x; |
264 |
|
|
} |
265 |
|
|
|
266 |
jsr166 |
1.9 |
public E pollFirst() { |
267 |
|
|
int h = head; |
268 |
jsr166 |
1.37 |
@SuppressWarnings("unchecked") |
269 |
|
|
E result = (E) elements[h]; |
270 |
jsr166 |
1.34 |
// Element is null if deque empty |
271 |
jsr166 |
1.9 |
if (result == null) |
272 |
|
|
return null; |
273 |
|
|
elements[h] = null; // Must null out slot |
274 |
|
|
head = (h + 1) & (elements.length - 1); |
275 |
|
|
return result; |
276 |
dl |
1.1 |
} |
277 |
|
|
|
278 |
jsr166 |
1.9 |
public E pollLast() { |
279 |
|
|
int t = (tail - 1) & (elements.length - 1); |
280 |
jsr166 |
1.37 |
@SuppressWarnings("unchecked") |
281 |
|
|
E result = (E) elements[t]; |
282 |
jsr166 |
1.9 |
if (result == null) |
283 |
|
|
return null; |
284 |
|
|
elements[t] = null; |
285 |
|
|
tail = t; |
286 |
|
|
return result; |
287 |
dl |
1.1 |
} |
288 |
|
|
|
289 |
|
|
/** |
290 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
291 |
dl |
1.1 |
*/ |
292 |
|
|
public E getFirst() { |
293 |
jsr166 |
1.37 |
@SuppressWarnings("unchecked") |
294 |
|
|
E result = (E) elements[head]; |
295 |
jsr166 |
1.34 |
if (result == null) |
296 |
dl |
1.1 |
throw new NoSuchElementException(); |
297 |
jsr166 |
1.34 |
return result; |
298 |
dl |
1.1 |
} |
299 |
|
|
|
300 |
|
|
/** |
301 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
302 |
dl |
1.1 |
*/ |
303 |
|
|
public E getLast() { |
304 |
jsr166 |
1.34 |
@SuppressWarnings("unchecked") |
305 |
|
|
E result = (E) elements[(tail - 1) & (elements.length - 1)]; |
306 |
|
|
if (result == null) |
307 |
dl |
1.1 |
throw new NoSuchElementException(); |
308 |
jsr166 |
1.34 |
return result; |
309 |
dl |
1.1 |
} |
310 |
|
|
|
311 |
jsr166 |
1.35 |
@SuppressWarnings("unchecked") |
312 |
jsr166 |
1.9 |
public E peekFirst() { |
313 |
jsr166 |
1.34 |
// elements[head] is null if deque empty |
314 |
jsr166 |
1.35 |
return (E) elements[head]; |
315 |
jsr166 |
1.9 |
} |
316 |
|
|
|
317 |
jsr166 |
1.35 |
@SuppressWarnings("unchecked") |
318 |
jsr166 |
1.9 |
public E peekLast() { |
319 |
jsr166 |
1.35 |
return (E) elements[(tail - 1) & (elements.length - 1)]; |
320 |
jsr166 |
1.9 |
} |
321 |
|
|
|
322 |
dl |
1.1 |
/** |
323 |
|
|
* Removes the first occurrence of the specified element in this |
324 |
jsr166 |
1.9 |
* deque (when traversing the deque from head to tail). |
325 |
|
|
* If the deque does not contain the element, it is unchanged. |
326 |
jsr166 |
1.40 |
* More formally, removes the first element {@code e} such that |
327 |
|
|
* {@code o.equals(e)} (if such an element exists). |
328 |
|
|
* Returns {@code true} if this deque contained the specified element |
329 |
jsr166 |
1.12 |
* (or equivalently, if this deque changed as a result of the call). |
330 |
dl |
1.1 |
* |
331 |
dl |
1.5 |
* @param o element to be removed from this deque, if present |
332 |
jsr166 |
1.40 |
* @return {@code true} if the deque contained the specified element |
333 |
dl |
1.1 |
*/ |
334 |
dl |
1.5 |
public boolean removeFirstOccurrence(Object o) { |
335 |
|
|
if (o == null) |
336 |
dl |
1.1 |
return false; |
337 |
|
|
int mask = elements.length - 1; |
338 |
|
|
int i = head; |
339 |
jsr166 |
1.34 |
Object x; |
340 |
dl |
1.1 |
while ( (x = elements[i]) != null) { |
341 |
dl |
1.5 |
if (o.equals(x)) { |
342 |
dl |
1.1 |
delete(i); |
343 |
|
|
return true; |
344 |
|
|
} |
345 |
|
|
i = (i + 1) & mask; |
346 |
|
|
} |
347 |
|
|
return false; |
348 |
|
|
} |
349 |
|
|
|
350 |
|
|
/** |
351 |
|
|
* Removes the last occurrence of the specified element in this |
352 |
jsr166 |
1.9 |
* deque (when traversing the deque from head to tail). |
353 |
|
|
* If the deque does not contain the element, it is unchanged. |
354 |
jsr166 |
1.40 |
* More formally, removes the last element {@code e} such that |
355 |
|
|
* {@code o.equals(e)} (if such an element exists). |
356 |
|
|
* Returns {@code true} if this deque contained the specified element |
357 |
jsr166 |
1.12 |
* (or equivalently, if this deque changed as a result of the call). |
358 |
dl |
1.1 |
* |
359 |
dl |
1.5 |
* @param o element to be removed from this deque, if present |
360 |
jsr166 |
1.40 |
* @return {@code true} if the deque contained the specified element |
361 |
dl |
1.1 |
*/ |
362 |
dl |
1.5 |
public boolean removeLastOccurrence(Object o) { |
363 |
|
|
if (o == null) |
364 |
dl |
1.1 |
return false; |
365 |
|
|
int mask = elements.length - 1; |
366 |
|
|
int i = (tail - 1) & mask; |
367 |
jsr166 |
1.34 |
Object x; |
368 |
dl |
1.1 |
while ( (x = elements[i]) != null) { |
369 |
dl |
1.5 |
if (o.equals(x)) { |
370 |
dl |
1.1 |
delete(i); |
371 |
|
|
return true; |
372 |
|
|
} |
373 |
|
|
i = (i - 1) & mask; |
374 |
|
|
} |
375 |
|
|
return false; |
376 |
|
|
} |
377 |
|
|
|
378 |
|
|
// *** Queue methods *** |
379 |
|
|
|
380 |
|
|
/** |
381 |
dl |
1.6 |
* Inserts the specified element at the end of this deque. |
382 |
dl |
1.1 |
* |
383 |
|
|
* <p>This method is equivalent to {@link #addLast}. |
384 |
|
|
* |
385 |
jsr166 |
1.9 |
* @param e the element to add |
386 |
jsr166 |
1.40 |
* @return {@code true} (as specified by {@link Collection#add}) |
387 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
388 |
dl |
1.1 |
*/ |
389 |
|
|
public boolean add(E e) { |
390 |
|
|
addLast(e); |
391 |
|
|
return true; |
392 |
|
|
} |
393 |
|
|
|
394 |
|
|
/** |
395 |
jsr166 |
1.9 |
* Inserts the specified element at the end of this deque. |
396 |
dl |
1.1 |
* |
397 |
jsr166 |
1.9 |
* <p>This method is equivalent to {@link #offerLast}. |
398 |
dl |
1.1 |
* |
399 |
jsr166 |
1.9 |
* @param e the element to add |
400 |
jsr166 |
1.40 |
* @return {@code true} (as specified by {@link Queue#offer}) |
401 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
402 |
dl |
1.1 |
*/ |
403 |
jsr166 |
1.9 |
public boolean offer(E e) { |
404 |
|
|
return offerLast(e); |
405 |
dl |
1.1 |
} |
406 |
|
|
|
407 |
|
|
/** |
408 |
|
|
* Retrieves and removes the head of the queue represented by this deque. |
409 |
jsr166 |
1.15 |
* |
410 |
|
|
* This method differs from {@link #poll poll} only in that it throws an |
411 |
jsr166 |
1.9 |
* exception if this deque is empty. |
412 |
dl |
1.1 |
* |
413 |
|
|
* <p>This method is equivalent to {@link #removeFirst}. |
414 |
|
|
* |
415 |
|
|
* @return the head of the queue represented by this deque |
416 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
417 |
dl |
1.1 |
*/ |
418 |
|
|
public E remove() { |
419 |
|
|
return removeFirst(); |
420 |
|
|
} |
421 |
|
|
|
422 |
|
|
/** |
423 |
jsr166 |
1.9 |
* Retrieves and removes the head of the queue represented by this deque |
424 |
|
|
* (in other words, the first element of this deque), or returns |
425 |
jsr166 |
1.40 |
* {@code null} if this deque is empty. |
426 |
dl |
1.1 |
* |
427 |
jsr166 |
1.9 |
* <p>This method is equivalent to {@link #pollFirst}. |
428 |
dl |
1.1 |
* |
429 |
|
|
* @return the head of the queue represented by this deque, or |
430 |
jsr166 |
1.40 |
* {@code null} if this deque is empty |
431 |
dl |
1.1 |
*/ |
432 |
jsr166 |
1.9 |
public E poll() { |
433 |
|
|
return pollFirst(); |
434 |
dl |
1.1 |
} |
435 |
|
|
|
436 |
|
|
/** |
437 |
|
|
* Retrieves, but does not remove, the head of the queue represented by |
438 |
jsr166 |
1.15 |
* this deque. This method differs from {@link #peek peek} only in |
439 |
|
|
* that it throws an exception if this deque is empty. |
440 |
dl |
1.1 |
* |
441 |
jsr166 |
1.8 |
* <p>This method is equivalent to {@link #getFirst}. |
442 |
dl |
1.1 |
* |
443 |
|
|
* @return the head of the queue represented by this deque |
444 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
445 |
dl |
1.1 |
*/ |
446 |
|
|
public E element() { |
447 |
|
|
return getFirst(); |
448 |
|
|
} |
449 |
|
|
|
450 |
jsr166 |
1.9 |
/** |
451 |
|
|
* Retrieves, but does not remove, the head of the queue represented by |
452 |
jsr166 |
1.40 |
* this deque, or returns {@code null} if this deque is empty. |
453 |
jsr166 |
1.9 |
* |
454 |
|
|
* <p>This method is equivalent to {@link #peekFirst}. |
455 |
|
|
* |
456 |
|
|
* @return the head of the queue represented by this deque, or |
457 |
jsr166 |
1.40 |
* {@code null} if this deque is empty |
458 |
jsr166 |
1.9 |
*/ |
459 |
|
|
public E peek() { |
460 |
|
|
return peekFirst(); |
461 |
|
|
} |
462 |
|
|
|
463 |
dl |
1.1 |
// *** Stack methods *** |
464 |
|
|
|
465 |
|
|
/** |
466 |
|
|
* Pushes an element onto the stack represented by this deque. In other |
467 |
dl |
1.5 |
* words, inserts the element at the front of this deque. |
468 |
dl |
1.1 |
* |
469 |
|
|
* <p>This method is equivalent to {@link #addFirst}. |
470 |
|
|
* |
471 |
|
|
* @param e the element to push |
472 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
473 |
dl |
1.1 |
*/ |
474 |
|
|
public void push(E e) { |
475 |
|
|
addFirst(e); |
476 |
|
|
} |
477 |
|
|
|
478 |
|
|
/** |
479 |
|
|
* Pops an element from the stack represented by this deque. In other |
480 |
dl |
1.2 |
* words, removes and returns the first element of this deque. |
481 |
dl |
1.1 |
* |
482 |
|
|
* <p>This method is equivalent to {@link #removeFirst()}. |
483 |
|
|
* |
484 |
|
|
* @return the element at the front of this deque (which is the top |
485 |
jsr166 |
1.9 |
* of the stack represented by this deque) |
486 |
|
|
* @throws NoSuchElementException {@inheritDoc} |
487 |
dl |
1.1 |
*/ |
488 |
|
|
public E pop() { |
489 |
|
|
return removeFirst(); |
490 |
|
|
} |
491 |
|
|
|
492 |
jsr166 |
1.25 |
private void checkInvariants() { |
493 |
jsr166 |
1.30 |
assert elements[tail] == null; |
494 |
|
|
assert head == tail ? elements[head] == null : |
495 |
|
|
(elements[head] != null && |
496 |
|
|
elements[(tail - 1) & (elements.length - 1)] != null); |
497 |
|
|
assert elements[(head - 1) & (elements.length - 1)] == null; |
498 |
jsr166 |
1.25 |
} |
499 |
|
|
|
500 |
dl |
1.1 |
/** |
501 |
jsr166 |
1.7 |
* Removes the element at the specified position in the elements array, |
502 |
jsr166 |
1.9 |
* adjusting head and tail as necessary. This can result in motion of |
503 |
|
|
* elements backwards or forwards in the array. |
504 |
dl |
1.1 |
* |
505 |
dl |
1.5 |
* <p>This method is called delete rather than remove to emphasize |
506 |
jsr166 |
1.9 |
* that its semantics differ from those of {@link List#remove(int)}. |
507 |
dl |
1.5 |
* |
508 |
dl |
1.1 |
* @return true if elements moved backwards |
509 |
|
|
*/ |
510 |
|
|
private boolean delete(int i) { |
511 |
jsr166 |
1.30 |
checkInvariants(); |
512 |
jsr166 |
1.34 |
final Object[] elements = this.elements; |
513 |
jsr166 |
1.30 |
final int mask = elements.length - 1; |
514 |
|
|
final int h = head; |
515 |
|
|
final int t = tail; |
516 |
|
|
final int front = (i - h) & mask; |
517 |
|
|
final int back = (t - i) & mask; |
518 |
|
|
|
519 |
|
|
// Invariant: head <= i < tail mod circularity |
520 |
|
|
if (front >= ((t - h) & mask)) |
521 |
|
|
throw new ConcurrentModificationException(); |
522 |
|
|
|
523 |
|
|
// Optimize for least element motion |
524 |
|
|
if (front < back) { |
525 |
|
|
if (h <= i) { |
526 |
|
|
System.arraycopy(elements, h, elements, h + 1, front); |
527 |
|
|
} else { // Wrap around |
528 |
|
|
System.arraycopy(elements, 0, elements, 1, i); |
529 |
|
|
elements[0] = elements[mask]; |
530 |
|
|
System.arraycopy(elements, h, elements, h + 1, mask - h); |
531 |
|
|
} |
532 |
|
|
elements[h] = null; |
533 |
|
|
head = (h + 1) & mask; |
534 |
|
|
return false; |
535 |
|
|
} else { |
536 |
|
|
if (i < t) { // Copy the null tail as well |
537 |
|
|
System.arraycopy(elements, i + 1, elements, i, back); |
538 |
|
|
tail = t - 1; |
539 |
|
|
} else { // Wrap around |
540 |
|
|
System.arraycopy(elements, i + 1, elements, i, mask - i); |
541 |
|
|
elements[mask] = elements[0]; |
542 |
|
|
System.arraycopy(elements, 1, elements, 0, t); |
543 |
|
|
tail = (t - 1) & mask; |
544 |
|
|
} |
545 |
|
|
return true; |
546 |
|
|
} |
547 |
dl |
1.23 |
} |
548 |
|
|
|
549 |
dl |
1.1 |
// *** Collection Methods *** |
550 |
|
|
|
551 |
|
|
/** |
552 |
|
|
* Returns the number of elements in this deque. |
553 |
|
|
* |
554 |
|
|
* @return the number of elements in this deque |
555 |
|
|
*/ |
556 |
|
|
public int size() { |
557 |
|
|
return (tail - head) & (elements.length - 1); |
558 |
|
|
} |
559 |
|
|
|
560 |
|
|
/** |
561 |
jsr166 |
1.40 |
* Returns {@code true} if this deque contains no elements. |
562 |
dl |
1.1 |
* |
563 |
jsr166 |
1.40 |
* @return {@code true} if this deque contains no elements |
564 |
dl |
1.1 |
*/ |
565 |
|
|
public boolean isEmpty() { |
566 |
|
|
return head == tail; |
567 |
|
|
} |
568 |
|
|
|
569 |
|
|
/** |
570 |
|
|
* Returns an iterator over the elements in this deque. The elements |
571 |
|
|
* will be ordered from first (head) to last (tail). This is the same |
572 |
|
|
* order that elements would be dequeued (via successive calls to |
573 |
|
|
* {@link #remove} or popped (via successive calls to {@link #pop}). |
574 |
dl |
1.5 |
* |
575 |
jsr166 |
1.18 |
* @return an iterator over the elements in this deque |
576 |
dl |
1.1 |
*/ |
577 |
|
|
public Iterator<E> iterator() { |
578 |
|
|
return new DeqIterator(); |
579 |
|
|
} |
580 |
|
|
|
581 |
dl |
1.16 |
public Iterator<E> descendingIterator() { |
582 |
|
|
return new DescendingIterator(); |
583 |
|
|
} |
584 |
|
|
|
585 |
dl |
1.1 |
private class DeqIterator implements Iterator<E> { |
586 |
|
|
/** |
587 |
|
|
* Index of element to be returned by subsequent call to next. |
588 |
|
|
*/ |
589 |
|
|
private int cursor = head; |
590 |
|
|
|
591 |
|
|
/** |
592 |
|
|
* Tail recorded at construction (also in remove), to stop |
593 |
|
|
* iterator and also to check for comodification. |
594 |
|
|
*/ |
595 |
|
|
private int fence = tail; |
596 |
|
|
|
597 |
|
|
/** |
598 |
|
|
* Index of element returned by most recent call to next. |
599 |
|
|
* Reset to -1 if element is deleted by a call to remove. |
600 |
|
|
*/ |
601 |
|
|
private int lastRet = -1; |
602 |
|
|
|
603 |
|
|
public boolean hasNext() { |
604 |
|
|
return cursor != fence; |
605 |
|
|
} |
606 |
|
|
|
607 |
|
|
public E next() { |
608 |
|
|
if (cursor == fence) |
609 |
|
|
throw new NoSuchElementException(); |
610 |
jsr166 |
1.37 |
@SuppressWarnings("unchecked") |
611 |
|
|
E result = (E) elements[cursor]; |
612 |
dl |
1.1 |
// This check doesn't catch all possible comodifications, |
613 |
|
|
// but does catch the ones that corrupt traversal |
614 |
jsr166 |
1.26 |
if (tail != fence || result == null) |
615 |
dl |
1.1 |
throw new ConcurrentModificationException(); |
616 |
|
|
lastRet = cursor; |
617 |
|
|
cursor = (cursor + 1) & (elements.length - 1); |
618 |
|
|
return result; |
619 |
|
|
} |
620 |
|
|
|
621 |
|
|
public void remove() { |
622 |
|
|
if (lastRet < 0) |
623 |
|
|
throw new IllegalStateException(); |
624 |
jsr166 |
1.26 |
if (delete(lastRet)) { // if left-shifted, undo increment in next() |
625 |
dl |
1.17 |
cursor = (cursor - 1) & (elements.length - 1); |
626 |
jsr166 |
1.30 |
fence = tail; |
627 |
|
|
} |
628 |
dl |
1.1 |
lastRet = -1; |
629 |
|
|
} |
630 |
|
|
} |
631 |
|
|
|
632 |
dl |
1.16 |
private class DescendingIterator implements Iterator<E> { |
633 |
jsr166 |
1.18 |
/* |
634 |
dl |
1.17 |
* This class is nearly a mirror-image of DeqIterator, using |
635 |
jsr166 |
1.26 |
* tail instead of head for initial cursor, and head instead of |
636 |
|
|
* tail for fence. |
637 |
dl |
1.16 |
*/ |
638 |
jsr166 |
1.26 |
private int cursor = tail; |
639 |
|
|
private int fence = head; |
640 |
|
|
private int lastRet = -1; |
641 |
dl |
1.16 |
|
642 |
|
|
public boolean hasNext() { |
643 |
|
|
return cursor != fence; |
644 |
|
|
} |
645 |
|
|
|
646 |
|
|
public E next() { |
647 |
|
|
if (cursor == fence) |
648 |
|
|
throw new NoSuchElementException(); |
649 |
jsr166 |
1.26 |
cursor = (cursor - 1) & (elements.length - 1); |
650 |
jsr166 |
1.37 |
@SuppressWarnings("unchecked") |
651 |
|
|
E result = (E) elements[cursor]; |
652 |
jsr166 |
1.26 |
if (head != fence || result == null) |
653 |
dl |
1.16 |
throw new ConcurrentModificationException(); |
654 |
|
|
lastRet = cursor; |
655 |
|
|
return result; |
656 |
|
|
} |
657 |
|
|
|
658 |
|
|
public void remove() { |
659 |
jsr166 |
1.26 |
if (lastRet < 0) |
660 |
dl |
1.16 |
throw new IllegalStateException(); |
661 |
jsr166 |
1.26 |
if (!delete(lastRet)) { |
662 |
dl |
1.17 |
cursor = (cursor + 1) & (elements.length - 1); |
663 |
jsr166 |
1.30 |
fence = head; |
664 |
|
|
} |
665 |
jsr166 |
1.26 |
lastRet = -1; |
666 |
dl |
1.16 |
} |
667 |
|
|
} |
668 |
|
|
|
669 |
dl |
1.1 |
/** |
670 |
jsr166 |
1.40 |
* Returns {@code true} if this deque contains the specified element. |
671 |
|
|
* More formally, returns {@code true} if and only if this deque contains |
672 |
|
|
* at least one element {@code e} such that {@code o.equals(e)}. |
673 |
dl |
1.1 |
* |
674 |
|
|
* @param o object to be checked for containment in this deque |
675 |
jsr166 |
1.40 |
* @return {@code true} if this deque contains the specified element |
676 |
dl |
1.1 |
*/ |
677 |
|
|
public boolean contains(Object o) { |
678 |
|
|
if (o == null) |
679 |
|
|
return false; |
680 |
|
|
int mask = elements.length - 1; |
681 |
|
|
int i = head; |
682 |
jsr166 |
1.34 |
Object x; |
683 |
dl |
1.1 |
while ( (x = elements[i]) != null) { |
684 |
|
|
if (o.equals(x)) |
685 |
|
|
return true; |
686 |
|
|
i = (i + 1) & mask; |
687 |
|
|
} |
688 |
|
|
return false; |
689 |
|
|
} |
690 |
|
|
|
691 |
|
|
/** |
692 |
|
|
* Removes a single instance of the specified element from this deque. |
693 |
jsr166 |
1.9 |
* If the deque does not contain the element, it is unchanged. |
694 |
jsr166 |
1.40 |
* More formally, removes the first element {@code e} such that |
695 |
|
|
* {@code o.equals(e)} (if such an element exists). |
696 |
|
|
* Returns {@code true} if this deque contained the specified element |
697 |
jsr166 |
1.12 |
* (or equivalently, if this deque changed as a result of the call). |
698 |
jsr166 |
1.9 |
* |
699 |
jsr166 |
1.46 |
* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}. |
700 |
dl |
1.1 |
* |
701 |
jsr166 |
1.9 |
* @param o element to be removed from this deque, if present |
702 |
jsr166 |
1.40 |
* @return {@code true} if this deque contained the specified element |
703 |
dl |
1.1 |
*/ |
704 |
jsr166 |
1.9 |
public boolean remove(Object o) { |
705 |
|
|
return removeFirstOccurrence(o); |
706 |
dl |
1.1 |
} |
707 |
|
|
|
708 |
|
|
/** |
709 |
|
|
* Removes all of the elements from this deque. |
710 |
jsr166 |
1.7 |
* The deque will be empty after this call returns. |
711 |
dl |
1.1 |
*/ |
712 |
|
|
public void clear() { |
713 |
|
|
int h = head; |
714 |
|
|
int t = tail; |
715 |
|
|
if (h != t) { // clear all cells |
716 |
|
|
head = tail = 0; |
717 |
|
|
int i = h; |
718 |
|
|
int mask = elements.length - 1; |
719 |
|
|
do { |
720 |
|
|
elements[i] = null; |
721 |
|
|
i = (i + 1) & mask; |
722 |
jsr166 |
1.9 |
} while (i != t); |
723 |
dl |
1.1 |
} |
724 |
|
|
} |
725 |
|
|
|
726 |
|
|
/** |
727 |
dl |
1.5 |
* Returns an array containing all of the elements in this deque |
728 |
jsr166 |
1.10 |
* in proper sequence (from first to last element). |
729 |
dl |
1.1 |
* |
730 |
jsr166 |
1.10 |
* <p>The returned array will be "safe" in that no references to it are |
731 |
|
|
* maintained by this deque. (In other words, this method must allocate |
732 |
|
|
* a new array). The caller is thus free to modify the returned array. |
733 |
jsr166 |
1.13 |
* |
734 |
jsr166 |
1.11 |
* <p>This method acts as bridge between array-based and collection-based |
735 |
|
|
* APIs. |
736 |
|
|
* |
737 |
dl |
1.5 |
* @return an array containing all of the elements in this deque |
738 |
dl |
1.1 |
*/ |
739 |
|
|
public Object[] toArray() { |
740 |
jsr166 |
1.30 |
return copyElements(new Object[size()]); |
741 |
dl |
1.1 |
} |
742 |
|
|
|
743 |
|
|
/** |
744 |
jsr166 |
1.10 |
* Returns an array containing all of the elements in this deque in |
745 |
|
|
* proper sequence (from first to last element); the runtime type of the |
746 |
|
|
* returned array is that of the specified array. If the deque fits in |
747 |
|
|
* the specified array, it is returned therein. Otherwise, a new array |
748 |
|
|
* is allocated with the runtime type of the specified array and the |
749 |
|
|
* size of this deque. |
750 |
|
|
* |
751 |
|
|
* <p>If this deque fits in the specified array with room to spare |
752 |
|
|
* (i.e., the array has more elements than this deque), the element in |
753 |
|
|
* the array immediately following the end of the deque is set to |
754 |
jsr166 |
1.40 |
* {@code null}. |
755 |
jsr166 |
1.10 |
* |
756 |
|
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
757 |
|
|
* array-based and collection-based APIs. Further, this method allows |
758 |
|
|
* precise control over the runtime type of the output array, and may, |
759 |
|
|
* under certain circumstances, be used to save allocation costs. |
760 |
|
|
* |
761 |
jsr166 |
1.40 |
* <p>Suppose {@code x} is a deque known to contain only strings. |
762 |
jsr166 |
1.10 |
* The following code can be used to dump the deque into a newly |
763 |
jsr166 |
1.40 |
* allocated array of {@code String}: |
764 |
jsr166 |
1.10 |
* |
765 |
jsr166 |
1.33 |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
766 |
jsr166 |
1.10 |
* |
767 |
jsr166 |
1.40 |
* Note that {@code toArray(new Object[0])} is identical in function to |
768 |
|
|
* {@code toArray()}. |
769 |
dl |
1.1 |
* |
770 |
|
|
* @param a the array into which the elements of the deque are to |
771 |
jsr166 |
1.9 |
* be stored, if it is big enough; otherwise, a new array of the |
772 |
|
|
* same runtime type is allocated for this purpose |
773 |
jsr166 |
1.10 |
* @return an array containing all of the elements in this deque |
774 |
|
|
* @throws ArrayStoreException if the runtime type of the specified array |
775 |
|
|
* is not a supertype of the runtime type of every element in |
776 |
|
|
* this deque |
777 |
|
|
* @throws NullPointerException if the specified array is null |
778 |
dl |
1.1 |
*/ |
779 |
jsr166 |
1.34 |
@SuppressWarnings("unchecked") |
780 |
dl |
1.1 |
public <T> T[] toArray(T[] a) { |
781 |
|
|
int size = size(); |
782 |
|
|
if (a.length < size) |
783 |
|
|
a = (T[])java.lang.reflect.Array.newInstance( |
784 |
|
|
a.getClass().getComponentType(), size); |
785 |
jsr166 |
1.30 |
copyElements(a); |
786 |
dl |
1.1 |
if (a.length > size) |
787 |
|
|
a[size] = null; |
788 |
|
|
return a; |
789 |
|
|
} |
790 |
|
|
|
791 |
|
|
// *** Object methods *** |
792 |
|
|
|
793 |
|
|
/** |
794 |
|
|
* Returns a copy of this deque. |
795 |
|
|
* |
796 |
|
|
* @return a copy of this deque |
797 |
|
|
*/ |
798 |
|
|
public ArrayDeque<E> clone() { |
799 |
dl |
1.5 |
try { |
800 |
jsr166 |
1.34 |
@SuppressWarnings("unchecked") |
801 |
dl |
1.1 |
ArrayDeque<E> result = (ArrayDeque<E>) super.clone(); |
802 |
jsr166 |
1.28 |
result.elements = Arrays.copyOf(elements, elements.length); |
803 |
dl |
1.1 |
return result; |
804 |
dl |
1.5 |
} catch (CloneNotSupportedException e) { |
805 |
dl |
1.1 |
throw new AssertionError(); |
806 |
|
|
} |
807 |
|
|
} |
808 |
|
|
|
809 |
|
|
private static final long serialVersionUID = 2340985798034038923L; |
810 |
|
|
|
811 |
|
|
/** |
812 |
jsr166 |
1.38 |
* Saves this deque to a stream (that is, serializes it). |
813 |
dl |
1.1 |
* |
814 |
jsr166 |
1.40 |
* @serialData The current size ({@code int}) of the deque, |
815 |
dl |
1.1 |
* followed by all of its elements (each an object reference) in |
816 |
|
|
* first-to-last order. |
817 |
|
|
*/ |
818 |
jsr166 |
1.32 |
private void writeObject(java.io.ObjectOutputStream s) |
819 |
|
|
throws java.io.IOException { |
820 |
dl |
1.1 |
s.defaultWriteObject(); |
821 |
|
|
|
822 |
|
|
// Write out size |
823 |
dl |
1.19 |
s.writeInt(size()); |
824 |
dl |
1.1 |
|
825 |
|
|
// Write out elements in order. |
826 |
|
|
int mask = elements.length - 1; |
827 |
dl |
1.19 |
for (int i = head; i != tail; i = (i + 1) & mask) |
828 |
dl |
1.1 |
s.writeObject(elements[i]); |
829 |
|
|
} |
830 |
|
|
|
831 |
|
|
/** |
832 |
jsr166 |
1.38 |
* Reconstitutes this deque from a stream (that is, deserializes it). |
833 |
dl |
1.1 |
*/ |
834 |
jsr166 |
1.32 |
private void readObject(java.io.ObjectInputStream s) |
835 |
|
|
throws java.io.IOException, ClassNotFoundException { |
836 |
dl |
1.1 |
s.defaultReadObject(); |
837 |
|
|
|
838 |
|
|
// Read in size and allocate array |
839 |
|
|
int size = s.readInt(); |
840 |
|
|
allocateElements(size); |
841 |
|
|
head = 0; |
842 |
|
|
tail = size; |
843 |
|
|
|
844 |
|
|
// Read in all elements in the proper order. |
845 |
|
|
for (int i = 0; i < size; i++) |
846 |
jsr166 |
1.34 |
elements[i] = s.readObject(); |
847 |
dl |
1.1 |
} |
848 |
dl |
1.41 |
|
849 |
dl |
1.47 |
Spliterator<E> spliterator() { |
850 |
|
|
return new DeqSpliterator<E>(this, -1, -1); |
851 |
|
|
} |
852 |
|
|
|
853 |
dl |
1.41 |
public Stream<E> stream() { |
854 |
dl |
1.47 |
return Streams.stream(spliterator()); |
855 |
dl |
1.41 |
} |
856 |
dl |
1.47 |
|
857 |
dl |
1.41 |
public Stream<E> parallelStream() { |
858 |
dl |
1.47 |
return Streams.parallelStream(spliterator()); |
859 |
dl |
1.41 |
} |
860 |
|
|
|
861 |
dl |
1.44 |
static final class DeqSpliterator<E> implements Spliterator<E> { |
862 |
dl |
1.41 |
private final ArrayDeque<E> deq; |
863 |
dl |
1.47 |
private int fence; // -1 until first use |
864 |
|
|
private int index; // current index, modified on traverse/split |
865 |
jsr166 |
1.48 |
|
866 |
dl |
1.41 |
/** Create new spliterator covering the given array and range */ |
867 |
|
|
DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) { |
868 |
dl |
1.47 |
this.deq = deq; |
869 |
|
|
this.index = origin; |
870 |
|
|
this.fence = fence; |
871 |
|
|
} |
872 |
|
|
|
873 |
|
|
private int getFence() { // force initialization |
874 |
|
|
int t; |
875 |
|
|
if ((t = fence) < 0) { |
876 |
|
|
t = fence = deq.tail; |
877 |
|
|
index = deq.head; |
878 |
|
|
} |
879 |
|
|
return t; |
880 |
dl |
1.41 |
} |
881 |
|
|
|
882 |
|
|
public DeqSpliterator<E> trySplit() { |
883 |
dl |
1.47 |
int t = getFence(), h = index, n = deq.elements.length; |
884 |
dl |
1.41 |
if (h != t && ((h + 1) & (n - 1)) != t) { |
885 |
|
|
if (h > t) |
886 |
|
|
t += n; |
887 |
|
|
int m = ((h + t) >>> 1) & (n - 1); |
888 |
dl |
1.47 |
return new DeqSpliterator<>(deq, h, index = m); |
889 |
dl |
1.41 |
} |
890 |
|
|
return null; |
891 |
|
|
} |
892 |
|
|
|
893 |
dl |
1.47 |
public void forEach(Consumer<? super E> consumer) { |
894 |
|
|
if (consumer == null) |
895 |
dl |
1.41 |
throw new NullPointerException(); |
896 |
dl |
1.44 |
Object[] a = deq.elements; |
897 |
dl |
1.47 |
int m = a.length - 1, f = getFence(), i = index; |
898 |
dl |
1.41 |
index = f; |
899 |
|
|
while (i != f) { |
900 |
dl |
1.44 |
@SuppressWarnings("unchecked") E e = (E)a[i]; |
901 |
|
|
i = (i + 1) & m; |
902 |
dl |
1.41 |
if (e == null) |
903 |
|
|
throw new ConcurrentModificationException(); |
904 |
dl |
1.47 |
consumer.accept(e); |
905 |
dl |
1.41 |
} |
906 |
|
|
} |
907 |
|
|
|
908 |
dl |
1.47 |
public boolean tryAdvance(Consumer<? super E> consumer) { |
909 |
|
|
if (consumer == null) |
910 |
dl |
1.41 |
throw new NullPointerException(); |
911 |
dl |
1.44 |
Object[] a = deq.elements; |
912 |
dl |
1.47 |
int m = a.length - 1, f = getFence(), i = index; |
913 |
dl |
1.41 |
if (i != fence) { |
914 |
dl |
1.44 |
@SuppressWarnings("unchecked") E e = (E)a[i]; |
915 |
|
|
index = (i + 1) & m; |
916 |
dl |
1.41 |
if (e == null) |
917 |
|
|
throw new ConcurrentModificationException(); |
918 |
dl |
1.47 |
consumer.accept(e); |
919 |
dl |
1.41 |
return true; |
920 |
|
|
} |
921 |
|
|
return false; |
922 |
|
|
} |
923 |
|
|
|
924 |
jsr166 |
1.42 |
public long estimateSize() { |
925 |
dl |
1.47 |
int n = getFence() - index; |
926 |
dl |
1.41 |
if (n < 0) |
927 |
dl |
1.44 |
n += deq.elements.length; |
928 |
dl |
1.47 |
return (long) n; |
929 |
|
|
} |
930 |
|
|
|
931 |
|
|
@Override |
932 |
|
|
public int characteristics() { |
933 |
jsr166 |
1.48 |
return Spliterator.ORDERED | Spliterator.SIZED | |
934 |
dl |
1.47 |
Spliterator.NONNULL | Spliterator.SUBSIZED; |
935 |
dl |
1.41 |
} |
936 |
|
|
} |
937 |
|
|
|
938 |
dl |
1.1 |
} |