7 |
|
|
8 |
|
import java.io.Serializable; |
9 |
|
import java.util.function.Consumer; |
10 |
< |
import java.util.stream.Stream; |
10 |
> |
import java.util.function.Predicate; |
11 |
> |
import java.util.function.UnaryOperator; |
12 |
|
|
13 |
|
/** |
14 |
|
* Resizable-array implementation of the {@link Deque} interface. Array |
54 |
|
* Java Collections Framework</a>. |
55 |
|
* |
56 |
|
* @author Josh Bloch and Doug Lea |
56 |
– |
* @since 1.6 |
57 |
|
* @param <E> the type of elements held in this deque |
58 |
+ |
* @since 1.6 |
59 |
|
*/ |
60 |
|
public class ArrayDeque<E> extends AbstractCollection<E> |
61 |
|
implements Deque<E>, Cloneable, Serializable |
62 |
|
{ |
63 |
+ |
/* |
64 |
+ |
* VMs excel at optimizing simple array loops where indices are |
65 |
+ |
* incrementing or decrementing over a valid slice, e.g. |
66 |
+ |
* |
67 |
+ |
* for (int i = start; i < end; i++) ... elements[i] |
68 |
+ |
* |
69 |
+ |
* Because in a circular array, elements are in general stored in |
70 |
+ |
* two disjoint such slices, we help the VM by writing unusual |
71 |
+ |
* nested loops for all traversals over the elements. Having only |
72 |
+ |
* one hot inner loop body instead of two or three eases human |
73 |
+ |
* maintenance and encourages VM loop inlining into the caller. |
74 |
+ |
*/ |
75 |
+ |
|
76 |
|
/** |
77 |
|
* The array in which the elements of the deque are stored. |
78 |
< |
* The capacity of the deque is the length of this array, which is |
79 |
< |
* always a power of two. The array is never allowed to become |
66 |
< |
* full, except transiently within an addX method where it is |
67 |
< |
* resized (see doubleCapacity) immediately upon becoming full, |
68 |
< |
* thus avoiding head and tail wrapping around to equal each |
69 |
< |
* other. We also guarantee that all array cells not holding |
70 |
< |
* deque elements are always null. |
78 |
> |
* All array cells not holding deque elements are always null. |
79 |
> |
* The array always has at least one null slot (at tail). |
80 |
|
*/ |
81 |
< |
transient Object[] elements; // non-private to simplify nested class access |
81 |
> |
transient Object[] elements; |
82 |
|
|
83 |
|
/** |
84 |
|
* The index of the element at the head of the deque (which is the |
85 |
|
* element that would be removed by remove() or pop()); or an |
86 |
< |
* arbitrary number equal to tail if the deque is empty. |
86 |
> |
* arbitrary number 0 <= head < elements.length equal to tail if |
87 |
> |
* the deque is empty. |
88 |
|
*/ |
89 |
|
transient int head; |
90 |
|
|
91 |
|
/** |
92 |
|
* The index at which the next element would be added to the tail |
93 |
< |
* of the deque (via addLast(E), add(E), or push(E)). |
93 |
> |
* of the deque (via addLast(E), add(E), or push(E)); |
94 |
> |
* elements[tail] is always null. |
95 |
|
*/ |
96 |
|
transient int tail; |
97 |
|
|
98 |
|
/** |
99 |
< |
* The minimum capacity that we'll use for a newly created deque. |
100 |
< |
* Must be a power of 2. |
99 |
> |
* The maximum size of array to allocate. |
100 |
> |
* Some VMs reserve some header words in an array. |
101 |
> |
* Attempts to allocate larger arrays may result in |
102 |
> |
* OutOfMemoryError: Requested array size exceeds VM limit |
103 |
|
*/ |
104 |
< |
private static final int MIN_INITIAL_CAPACITY = 8; |
104 |
> |
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
105 |
|
|
106 |
< |
// ****** Array allocation and resizing utilities ****** |
106 |
> |
/** |
107 |
> |
* Increases the capacity of this deque by at least the given amount. |
108 |
> |
* |
109 |
> |
* @param needed the required minimum extra capacity; must be positive |
110 |
> |
*/ |
111 |
> |
private void grow(int needed) { |
112 |
> |
// overflow-conscious code |
113 |
> |
final int oldCapacity = elements.length; |
114 |
> |
int newCapacity; |
115 |
> |
// Double capacity if small; else grow by 50% |
116 |
> |
int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1); |
117 |
> |
if (jump < needed |
118 |
> |
|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0) |
119 |
> |
newCapacity = newCapacity(needed, jump); |
120 |
> |
elements = Arrays.copyOf(elements, newCapacity); |
121 |
> |
// Exceptionally, here tail == head needs to be disambiguated |
122 |
> |
if (tail < head || (tail == head && elements[head] != null)) { |
123 |
> |
// wrap around; slide first leg forward to end of array |
124 |
> |
int newSpace = newCapacity - oldCapacity; |
125 |
> |
System.arraycopy(elements, head, |
126 |
> |
elements, head + newSpace, |
127 |
> |
oldCapacity - head); |
128 |
> |
Arrays.fill(elements, head, head + newSpace, null); |
129 |
> |
head += newSpace; |
130 |
> |
} |
131 |
> |
// checkInvariants(); |
132 |
> |
} |
133 |
> |
|
134 |
> |
/** Capacity calculation for edge conditions, especially overflow. */ |
135 |
> |
private int newCapacity(int needed, int jump) { |
136 |
> |
final int oldCapacity = elements.length, minCapacity; |
137 |
> |
if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) { |
138 |
> |
if (minCapacity < 0) |
139 |
> |
throw new IllegalStateException("Sorry, deque too big"); |
140 |
> |
return Integer.MAX_VALUE; |
141 |
> |
} |
142 |
> |
if (needed > jump) |
143 |
> |
return minCapacity; |
144 |
> |
return (oldCapacity + jump - MAX_ARRAY_SIZE < 0) |
145 |
> |
? oldCapacity + jump |
146 |
> |
: MAX_ARRAY_SIZE; |
147 |
> |
} |
148 |
|
|
149 |
|
/** |
150 |
< |
* Allocates empty array to hold the given number of elements. |
151 |
< |
* |
152 |
< |
* @param numElements the number of elements to hold |
153 |
< |
*/ |
154 |
< |
private void allocateElements(int numElements) { |
155 |
< |
int initialCapacity = MIN_INITIAL_CAPACITY; |
156 |
< |
// Find the best power of two to hold elements. |
157 |
< |
// Tests "<=" because arrays aren't kept full. |
158 |
< |
if (numElements >= initialCapacity) { |
159 |
< |
initialCapacity = numElements; |
160 |
< |
initialCapacity |= (initialCapacity >>> 1); |
107 |
< |
initialCapacity |= (initialCapacity >>> 2); |
108 |
< |
initialCapacity |= (initialCapacity >>> 4); |
109 |
< |
initialCapacity |= (initialCapacity >>> 8); |
110 |
< |
initialCapacity |= (initialCapacity >>> 16); |
111 |
< |
initialCapacity++; |
112 |
< |
|
113 |
< |
if (initialCapacity < 0) // Too many elements, must back off |
114 |
< |
initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements |
115 |
< |
} |
116 |
< |
elements = new Object[initialCapacity]; |
150 |
> |
* Increases the internal storage of this collection, if necessary, |
151 |
> |
* to ensure that it can hold at least the given number of elements. |
152 |
> |
* |
153 |
> |
* @param minCapacity the desired minimum capacity |
154 |
> |
* @since TBD |
155 |
> |
*/ |
156 |
> |
/* public */ void ensureCapacity(int minCapacity) { |
157 |
> |
int needed; |
158 |
> |
if ((needed = (minCapacity + 1 - elements.length)) > 0) |
159 |
> |
grow(needed); |
160 |
> |
// checkInvariants(); |
161 |
|
} |
162 |
|
|
163 |
|
/** |
164 |
< |
* Doubles the capacity of this deque. Call only when full, i.e., |
165 |
< |
* when head and tail have wrapped around to become equal. |
166 |
< |
*/ |
167 |
< |
private void doubleCapacity() { |
168 |
< |
assert head == tail; |
169 |
< |
int p = head; |
170 |
< |
int n = elements.length; |
171 |
< |
int r = n - p; // number of elements to the right of p |
172 |
< |
int newCapacity = n << 1; |
173 |
< |
if (newCapacity < 0) |
174 |
< |
throw new IllegalStateException("Sorry, deque too big"); |
175 |
< |
Object[] a = new Object[newCapacity]; |
132 |
< |
System.arraycopy(elements, p, a, 0, r); |
133 |
< |
System.arraycopy(elements, 0, a, r, p); |
134 |
< |
elements = a; |
135 |
< |
head = 0; |
136 |
< |
tail = n; |
164 |
> |
* Minimizes the internal storage of this collection. |
165 |
> |
* |
166 |
> |
* @since TBD |
167 |
> |
*/ |
168 |
> |
/* public */ void trimToSize() { |
169 |
> |
int size; |
170 |
> |
if ((size = size()) + 1 < elements.length) { |
171 |
> |
elements = toArray(new Object[size + 1]); |
172 |
> |
head = 0; |
173 |
> |
tail = size; |
174 |
> |
} |
175 |
> |
// checkInvariants(); |
176 |
|
} |
177 |
|
|
178 |
|
/** |
187 |
|
* Constructs an empty array deque with an initial capacity |
188 |
|
* sufficient to hold the specified number of elements. |
189 |
|
* |
190 |
< |
* @param numElements lower bound on initial capacity of the deque |
190 |
> |
* @param numElements lower bound on initial capacity of the deque |
191 |
|
*/ |
192 |
|
public ArrayDeque(int numElements) { |
193 |
< |
allocateElements(numElements); |
193 |
> |
elements = |
194 |
> |
new Object[(numElements < 1) ? 1 : |
195 |
> |
(numElements == Integer.MAX_VALUE) ? Integer.MAX_VALUE : |
196 |
> |
numElements + 1]; |
197 |
|
} |
198 |
|
|
199 |
|
/** |
207 |
|
* @throws NullPointerException if the specified collection is null |
208 |
|
*/ |
209 |
|
public ArrayDeque(Collection<? extends E> c) { |
210 |
< |
allocateElements(c.size()); |
210 |
> |
this(c.size()); |
211 |
|
addAll(c); |
212 |
|
} |
213 |
|
|
214 |
+ |
/** |
215 |
+ |
* Increments i, mod modulus. |
216 |
+ |
* Precondition and postcondition: 0 <= i < modulus. |
217 |
+ |
*/ |
218 |
+ |
static final int inc(int i, int modulus) { |
219 |
+ |
if (++i >= modulus) i = 0; |
220 |
+ |
return i; |
221 |
+ |
} |
222 |
+ |
|
223 |
+ |
/** |
224 |
+ |
* Decrements i, mod modulus. |
225 |
+ |
* Precondition and postcondition: 0 <= i < modulus. |
226 |
+ |
*/ |
227 |
+ |
static final int dec(int i, int modulus) { |
228 |
+ |
if (--i < 0) i = modulus - 1; |
229 |
+ |
return i; |
230 |
+ |
} |
231 |
+ |
|
232 |
+ |
/** |
233 |
+ |
* Circularly adds the given distance to index i, mod modulus. |
234 |
+ |
* Precondition: 0 <= i < modulus, 0 <= distance <= modulus. |
235 |
+ |
* @return index 0 <= i < modulus |
236 |
+ |
*/ |
237 |
+ |
static final int add(int i, int distance, int modulus) { |
238 |
+ |
if ((i += distance) - modulus >= 0) distance -= modulus; |
239 |
+ |
return i; |
240 |
+ |
} |
241 |
+ |
|
242 |
+ |
/** |
243 |
+ |
* Subtracts j from i, mod modulus. |
244 |
+ |
* Index i must be logically ahead of index j. |
245 |
+ |
* Precondition: 0 <= i < modulus, 0 <= j < modulus. |
246 |
+ |
* @return the "circular distance" from j to i; corner case i == j |
247 |
+ |
* is diambiguated to "empty", returning 0. |
248 |
+ |
*/ |
249 |
+ |
static final int sub(int i, int j, int modulus) { |
250 |
+ |
if ((i -= j) < 0) i += modulus; |
251 |
+ |
return i; |
252 |
+ |
} |
253 |
+ |
|
254 |
+ |
/** |
255 |
+ |
* Returns element at array index i. |
256 |
+ |
* This is a slight abuse of generics, accepted by javac. |
257 |
+ |
*/ |
258 |
+ |
@SuppressWarnings("unchecked") |
259 |
+ |
static final <E> E elementAt(Object[] es, int i) { |
260 |
+ |
return (E) es[i]; |
261 |
+ |
} |
262 |
+ |
|
263 |
+ |
/** |
264 |
+ |
* A version of elementAt that checks for null elements. |
265 |
+ |
* This check doesn't catch all possible comodifications, |
266 |
+ |
* but does catch ones that corrupt traversal. |
267 |
+ |
*/ |
268 |
+ |
static final <E> E nonNullElementAt(Object[] es, int i) { |
269 |
+ |
@SuppressWarnings("unchecked") E e = (E) es[i]; |
270 |
+ |
if (e == null) |
271 |
+ |
throw new ConcurrentModificationException(); |
272 |
+ |
return e; |
273 |
+ |
} |
274 |
+ |
|
275 |
|
// The main insertion and extraction methods are addFirst, |
276 |
|
// addLast, pollFirst, pollLast. The other methods are defined in |
277 |
|
// terms of these. |
285 |
|
public void addFirst(E e) { |
286 |
|
if (e == null) |
287 |
|
throw new NullPointerException(); |
288 |
< |
elements[head = (head - 1) & (elements.length - 1)] = e; |
288 |
> |
final Object[] es = elements; |
289 |
> |
es[head = dec(head, es.length)] = e; |
290 |
|
if (head == tail) |
291 |
< |
doubleCapacity(); |
291 |
> |
grow(1); |
292 |
> |
// checkInvariants(); |
293 |
|
} |
294 |
|
|
295 |
|
/** |
303 |
|
public void addLast(E e) { |
304 |
|
if (e == null) |
305 |
|
throw new NullPointerException(); |
306 |
< |
elements[tail] = e; |
307 |
< |
if ( (tail = (tail + 1) & (elements.length - 1)) == head) |
308 |
< |
doubleCapacity(); |
306 |
> |
final Object[] es = elements; |
307 |
> |
es[tail] = e; |
308 |
> |
if (head == (tail = inc(tail, es.length))) |
309 |
> |
grow(1); |
310 |
> |
// checkInvariants(); |
311 |
> |
} |
312 |
> |
|
313 |
> |
/** |
314 |
> |
* Adds all of the elements in the specified collection at the end |
315 |
> |
* of this deque, as if by calling {@link #addLast} on each one, |
316 |
> |
* in the order that they are returned by the collection's |
317 |
> |
* iterator. |
318 |
> |
* |
319 |
> |
* @param c the elements to be inserted into this deque |
320 |
> |
* @return {@code true} if this deque changed as a result of the call |
321 |
> |
* @throws NullPointerException if the specified collection or any |
322 |
> |
* of its elements are null |
323 |
> |
*/ |
324 |
> |
public boolean addAll(Collection<? extends E> c) { |
325 |
> |
final int s, needed; |
326 |
> |
if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0) |
327 |
> |
grow(needed); |
328 |
> |
c.forEach(this::addLast); |
329 |
> |
// checkInvariants(); |
330 |
> |
return size() > s; |
331 |
|
} |
332 |
|
|
333 |
|
/** |
358 |
|
* @throws NoSuchElementException {@inheritDoc} |
359 |
|
*/ |
360 |
|
public E removeFirst() { |
361 |
< |
E x = pollFirst(); |
362 |
< |
if (x == null) |
361 |
> |
E e = pollFirst(); |
362 |
> |
if (e == null) |
363 |
|
throw new NoSuchElementException(); |
364 |
< |
return x; |
364 |
> |
// checkInvariants(); |
365 |
> |
return e; |
366 |
|
} |
367 |
|
|
368 |
|
/** |
369 |
|
* @throws NoSuchElementException {@inheritDoc} |
370 |
|
*/ |
371 |
|
public E removeLast() { |
372 |
< |
E x = pollLast(); |
373 |
< |
if (x == null) |
372 |
> |
E e = pollLast(); |
373 |
> |
if (e == null) |
374 |
|
throw new NoSuchElementException(); |
375 |
< |
return x; |
375 |
> |
// checkInvariants(); |
376 |
> |
return e; |
377 |
|
} |
378 |
|
|
379 |
|
public E pollFirst() { |
380 |
< |
int h = head; |
381 |
< |
@SuppressWarnings("unchecked") |
382 |
< |
E result = (E) elements[h]; |
383 |
< |
// Element is null if deque empty |
384 |
< |
if (result == null) |
385 |
< |
return null; |
386 |
< |
elements[h] = null; // Must null out slot |
387 |
< |
head = (h + 1) & (elements.length - 1); |
388 |
< |
return result; |
380 |
> |
final Object[] es; |
381 |
> |
final int h; |
382 |
> |
E e = elementAt(es = elements, h = head); |
383 |
> |
if (e != null) { |
384 |
> |
es[h] = null; |
385 |
> |
head = inc(h, es.length); |
386 |
> |
} |
387 |
> |
// checkInvariants(); |
388 |
> |
return e; |
389 |
|
} |
390 |
|
|
391 |
|
public E pollLast() { |
392 |
< |
int t = (tail - 1) & (elements.length - 1); |
393 |
< |
@SuppressWarnings("unchecked") |
394 |
< |
E result = (E) elements[t]; |
395 |
< |
if (result == null) |
396 |
< |
return null; |
397 |
< |
elements[t] = null; |
398 |
< |
tail = t; |
270 |
< |
return result; |
392 |
> |
final Object[] es; |
393 |
> |
final int t; |
394 |
> |
E e = elementAt(es = elements, t = dec(tail, es.length)); |
395 |
> |
if (e != null) |
396 |
> |
es[tail = t] = null; |
397 |
> |
// checkInvariants(); |
398 |
> |
return e; |
399 |
|
} |
400 |
|
|
401 |
|
/** |
402 |
|
* @throws NoSuchElementException {@inheritDoc} |
403 |
|
*/ |
404 |
|
public E getFirst() { |
405 |
< |
@SuppressWarnings("unchecked") |
406 |
< |
E result = (E) elements[head]; |
279 |
< |
if (result == null) |
405 |
> |
E e = elementAt(elements, head); |
406 |
> |
if (e == null) |
407 |
|
throw new NoSuchElementException(); |
408 |
< |
return result; |
408 |
> |
// checkInvariants(); |
409 |
> |
return e; |
410 |
|
} |
411 |
|
|
412 |
|
/** |
413 |
|
* @throws NoSuchElementException {@inheritDoc} |
414 |
|
*/ |
415 |
|
public E getLast() { |
416 |
< |
@SuppressWarnings("unchecked") |
417 |
< |
E result = (E) elements[(tail - 1) & (elements.length - 1)]; |
418 |
< |
if (result == null) |
416 |
> |
final Object[] es = elements; |
417 |
> |
E e = elementAt(es, dec(tail, es.length)); |
418 |
> |
if (e == null) |
419 |
|
throw new NoSuchElementException(); |
420 |
< |
return result; |
420 |
> |
// checkInvariants(); |
421 |
> |
return e; |
422 |
|
} |
423 |
|
|
295 |
– |
@SuppressWarnings("unchecked") |
424 |
|
public E peekFirst() { |
425 |
< |
// elements[head] is null if deque empty |
426 |
< |
return (E) elements[head]; |
425 |
> |
// checkInvariants(); |
426 |
> |
return elementAt(elements, head); |
427 |
|
} |
428 |
|
|
301 |
– |
@SuppressWarnings("unchecked") |
429 |
|
public E peekLast() { |
430 |
< |
return (E) elements[(tail - 1) & (elements.length - 1)]; |
430 |
> |
// checkInvariants(); |
431 |
> |
final Object[] es; |
432 |
> |
return elementAt(es = elements, dec(tail, es.length)); |
433 |
|
} |
434 |
|
|
435 |
|
/** |
446 |
|
*/ |
447 |
|
public boolean removeFirstOccurrence(Object o) { |
448 |
|
if (o != null) { |
449 |
< |
int mask = elements.length - 1; |
450 |
< |
int i = head; |
451 |
< |
for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) { |
452 |
< |
if (o.equals(x)) { |
453 |
< |
delete(i); |
454 |
< |
return true; |
455 |
< |
} |
449 |
> |
final Object[] es = elements; |
450 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
451 |
> |
; i = 0, to = end) { |
452 |
> |
for (; i < to; i++) |
453 |
> |
if (o.equals(es[i])) { |
454 |
> |
delete(i); |
455 |
> |
return true; |
456 |
> |
} |
457 |
> |
if (to == end) break; |
458 |
|
} |
459 |
|
} |
460 |
|
return false; |
474 |
|
*/ |
475 |
|
public boolean removeLastOccurrence(Object o) { |
476 |
|
if (o != null) { |
477 |
< |
int mask = elements.length - 1; |
478 |
< |
int i = (tail - 1) & mask; |
479 |
< |
for (Object x; (x = elements[i]) != null; i = (i - 1) & mask) { |
480 |
< |
if (o.equals(x)) { |
481 |
< |
delete(i); |
482 |
< |
return true; |
483 |
< |
} |
477 |
> |
final Object[] es = elements; |
478 |
> |
for (int i = tail, end = head, to = (i >= end) ? end : 0; |
479 |
> |
; i = es.length, to = end) { |
480 |
> |
for (i--; i > to - 1; i--) |
481 |
> |
if (o.equals(es[i])) { |
482 |
> |
delete(i); |
483 |
> |
return true; |
484 |
> |
} |
485 |
> |
if (to == end) break; |
486 |
|
} |
487 |
|
} |
488 |
|
return false; |
602 |
|
return removeFirst(); |
603 |
|
} |
604 |
|
|
472 |
– |
private void checkInvariants() { |
473 |
– |
assert elements[tail] == null; |
474 |
– |
assert head == tail ? elements[head] == null : |
475 |
– |
(elements[head] != null && |
476 |
– |
elements[(tail - 1) & (elements.length - 1)] != null); |
477 |
– |
assert elements[(head - 1) & (elements.length - 1)] == null; |
478 |
– |
} |
479 |
– |
|
605 |
|
/** |
606 |
< |
* Removes the element at the specified position in the elements array, |
607 |
< |
* adjusting head and tail as necessary. This can result in motion of |
608 |
< |
* elements backwards or forwards in the array. |
606 |
> |
* Removes the element at the specified position in the elements array. |
607 |
> |
* This can result in forward or backwards motion of array elements. |
608 |
> |
* We optimize for least element motion. |
609 |
|
* |
610 |
|
* <p>This method is called delete rather than remove to emphasize |
611 |
|
* that its semantics differ from those of {@link List#remove(int)}. |
612 |
|
* |
613 |
< |
* @return true if elements moved backwards |
613 |
> |
* @return true if elements near tail moved backwards |
614 |
|
*/ |
615 |
< |
private boolean delete(int i) { |
616 |
< |
checkInvariants(); |
617 |
< |
final Object[] elements = this.elements; |
618 |
< |
final int mask = elements.length - 1; |
619 |
< |
final int h = head; |
620 |
< |
final int t = tail; |
621 |
< |
final int front = (i - h) & mask; |
622 |
< |
final int back = (t - i) & mask; |
623 |
< |
|
499 |
< |
// Invariant: head <= i < tail mod circularity |
500 |
< |
if (front >= ((t - h) & mask)) |
501 |
< |
throw new ConcurrentModificationException(); |
502 |
< |
|
503 |
< |
// Optimize for least element motion |
615 |
> |
boolean delete(int i) { |
616 |
> |
// checkInvariants(); |
617 |
> |
final Object[] es = elements; |
618 |
> |
final int capacity = es.length; |
619 |
> |
final int h, t; |
620 |
> |
// number of elements before to-be-deleted elt |
621 |
> |
final int front = sub(i, h = head, capacity); |
622 |
> |
// number of elements after to-be-deleted elt |
623 |
> |
final int back = sub(t = tail, i, capacity) - 1; |
624 |
|
if (front < back) { |
625 |
+ |
// move front elements forwards |
626 |
|
if (h <= i) { |
627 |
< |
System.arraycopy(elements, h, elements, h + 1, front); |
627 |
> |
System.arraycopy(es, h, es, h + 1, front); |
628 |
|
} else { // Wrap around |
629 |
< |
System.arraycopy(elements, 0, elements, 1, i); |
630 |
< |
elements[0] = elements[mask]; |
631 |
< |
System.arraycopy(elements, h, elements, h + 1, mask - h); |
629 |
> |
System.arraycopy(es, 0, es, 1, i); |
630 |
> |
es[0] = es[capacity - 1]; |
631 |
> |
System.arraycopy(es, h, es, h + 1, front - (i + 1)); |
632 |
|
} |
633 |
< |
elements[h] = null; |
634 |
< |
head = (h + 1) & mask; |
633 |
> |
es[h] = null; |
634 |
> |
head = inc(h, capacity); |
635 |
> |
// checkInvariants(); |
636 |
|
return false; |
637 |
|
} else { |
638 |
< |
if (i < t) { // Copy the null tail as well |
639 |
< |
System.arraycopy(elements, i + 1, elements, i, back); |
640 |
< |
tail = t - 1; |
638 |
> |
// move back elements backwards |
639 |
> |
tail = dec(t, capacity); |
640 |
> |
if (i <= tail) { |
641 |
> |
System.arraycopy(es, i + 1, es, i, back); |
642 |
|
} else { // Wrap around |
643 |
< |
System.arraycopy(elements, i + 1, elements, i, mask - i); |
644 |
< |
elements[mask] = elements[0]; |
645 |
< |
System.arraycopy(elements, 1, elements, 0, t); |
523 |
< |
tail = (t - 1) & mask; |
643 |
> |
System.arraycopy(es, i + 1, es, i, capacity - (i + 1)); |
644 |
> |
es[capacity - 1] = es[0]; |
645 |
> |
System.arraycopy(es, 1, es, 0, t - 1); |
646 |
|
} |
647 |
+ |
es[tail] = null; |
648 |
+ |
// checkInvariants(); |
649 |
|
return true; |
650 |
|
} |
651 |
|
} |
658 |
|
* @return the number of elements in this deque |
659 |
|
*/ |
660 |
|
public int size() { |
661 |
< |
return (tail - head) & (elements.length - 1); |
661 |
> |
return sub(tail, head, elements.length); |
662 |
|
} |
663 |
|
|
664 |
|
/** |
687 |
|
} |
688 |
|
|
689 |
|
private class DeqIterator implements Iterator<E> { |
690 |
< |
/** |
691 |
< |
* Index of element to be returned by subsequent call to next. |
568 |
< |
*/ |
569 |
< |
private int cursor = head; |
690 |
> |
/** Index of element to be returned by subsequent call to next. */ |
691 |
> |
int cursor; |
692 |
|
|
693 |
< |
/** |
694 |
< |
* Tail recorded at construction (also in remove), to stop |
573 |
< |
* iterator and also to check for comodification. |
574 |
< |
*/ |
575 |
< |
private int fence = tail; |
693 |
> |
/** Number of elements yet to be returned. */ |
694 |
> |
int remaining = size(); |
695 |
|
|
696 |
|
/** |
697 |
|
* Index of element returned by most recent call to next. |
698 |
|
* Reset to -1 if element is deleted by a call to remove. |
699 |
|
*/ |
700 |
< |
private int lastRet = -1; |
700 |
> |
int lastRet = -1; |
701 |
> |
|
702 |
> |
DeqIterator() { cursor = head; } |
703 |
|
|
704 |
< |
public boolean hasNext() { |
705 |
< |
return cursor != fence; |
704 |
> |
public final boolean hasNext() { |
705 |
> |
return remaining > 0; |
706 |
|
} |
707 |
|
|
708 |
|
public E next() { |
709 |
< |
if (cursor == fence) |
709 |
> |
if (remaining <= 0) |
710 |
|
throw new NoSuchElementException(); |
711 |
< |
@SuppressWarnings("unchecked") |
712 |
< |
E result = (E) elements[cursor]; |
592 |
< |
// This check doesn't catch all possible comodifications, |
593 |
< |
// but does catch the ones that corrupt traversal |
594 |
< |
if (tail != fence || result == null) |
595 |
< |
throw new ConcurrentModificationException(); |
711 |
> |
final Object[] es = elements; |
712 |
> |
E e = nonNullElementAt(es, cursor); |
713 |
|
lastRet = cursor; |
714 |
< |
cursor = (cursor + 1) & (elements.length - 1); |
715 |
< |
return result; |
714 |
> |
cursor = inc(cursor, es.length); |
715 |
> |
remaining--; |
716 |
> |
return e; |
717 |
> |
} |
718 |
> |
|
719 |
> |
void postDelete(boolean leftShifted) { |
720 |
> |
if (leftShifted) |
721 |
> |
cursor = dec(cursor, elements.length); |
722 |
|
} |
723 |
|
|
724 |
< |
public void remove() { |
724 |
> |
public final void remove() { |
725 |
|
if (lastRet < 0) |
726 |
|
throw new IllegalStateException(); |
727 |
< |
if (delete(lastRet)) { // if left-shifted, undo increment in next() |
605 |
< |
cursor = (cursor - 1) & (elements.length - 1); |
606 |
< |
fence = tail; |
607 |
< |
} |
727 |
> |
postDelete(delete(lastRet)); |
728 |
|
lastRet = -1; |
729 |
|
} |
730 |
+ |
|
731 |
+ |
public void forEachRemaining(Consumer<? super E> action) { |
732 |
+ |
Objects.requireNonNull(action); |
733 |
+ |
int r; |
734 |
+ |
if ((r = remaining) <= 0) |
735 |
+ |
return; |
736 |
+ |
remaining = 0; |
737 |
+ |
final Object[] es = elements; |
738 |
+ |
if (es[cursor] == null || sub(tail, cursor, es.length) != r) |
739 |
+ |
throw new ConcurrentModificationException(); |
740 |
+ |
for (int i = cursor, end = tail, to = (i <= end) ? end : es.length; |
741 |
+ |
; i = 0, to = end) { |
742 |
+ |
for (; i < to; i++) |
743 |
+ |
action.accept(elementAt(es, i)); |
744 |
+ |
if (to == end) { |
745 |
+ |
if (end != tail) |
746 |
+ |
throw new ConcurrentModificationException(); |
747 |
+ |
lastRet = dec(end, es.length); |
748 |
+ |
break; |
749 |
+ |
} |
750 |
+ |
} |
751 |
+ |
} |
752 |
+ |
} |
753 |
+ |
|
754 |
+ |
private class DescendingIterator extends DeqIterator { |
755 |
+ |
DescendingIterator() { cursor = dec(tail, elements.length); } |
756 |
+ |
|
757 |
+ |
public final E next() { |
758 |
+ |
if (remaining <= 0) |
759 |
+ |
throw new NoSuchElementException(); |
760 |
+ |
final Object[] es = elements; |
761 |
+ |
E e = nonNullElementAt(es, cursor); |
762 |
+ |
lastRet = cursor; |
763 |
+ |
cursor = dec(cursor, es.length); |
764 |
+ |
remaining--; |
765 |
+ |
return e; |
766 |
+ |
} |
767 |
+ |
|
768 |
+ |
void postDelete(boolean leftShifted) { |
769 |
+ |
if (!leftShifted) |
770 |
+ |
cursor = inc(cursor, elements.length); |
771 |
+ |
} |
772 |
+ |
|
773 |
+ |
public final void forEachRemaining(Consumer<? super E> action) { |
774 |
+ |
Objects.requireNonNull(action); |
775 |
+ |
int r; |
776 |
+ |
if ((r = remaining) <= 0) |
777 |
+ |
return; |
778 |
+ |
remaining = 0; |
779 |
+ |
final Object[] es = elements; |
780 |
+ |
if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r) |
781 |
+ |
throw new ConcurrentModificationException(); |
782 |
+ |
for (int i = cursor, end = head, to = (i >= end) ? end : 0; |
783 |
+ |
; i = es.length - 1, to = end) { |
784 |
+ |
// hotspot generates faster code than for: i >= to ! |
785 |
+ |
for (; i > to - 1; i--) |
786 |
+ |
action.accept(elementAt(es, i)); |
787 |
+ |
if (to == end) { |
788 |
+ |
if (end != head) |
789 |
+ |
throw new ConcurrentModificationException(); |
790 |
+ |
lastRet = end; |
791 |
+ |
break; |
792 |
+ |
} |
793 |
+ |
} |
794 |
+ |
} |
795 |
|
} |
796 |
|
|
797 |
|
/** |
798 |
< |
* This class is nearly a mirror-image of DeqIterator, using tail |
799 |
< |
* instead of head for initial cursor, and head instead of tail |
800 |
< |
* for fence. |
801 |
< |
*/ |
802 |
< |
private class DescendingIterator implements Iterator<E> { |
803 |
< |
private int cursor = tail; |
804 |
< |
private int fence = head; |
805 |
< |
private int lastRet = -1; |
798 |
> |
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> |
799 |
> |
* and <em>fail-fast</em> {@link Spliterator} over the elements in this |
800 |
> |
* deque. |
801 |
> |
* |
802 |
> |
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, |
803 |
> |
* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and |
804 |
> |
* {@link Spliterator#NONNULL}. Overriding implementations should document |
805 |
> |
* the reporting of additional characteristic values. |
806 |
> |
* |
807 |
> |
* @return a {@code Spliterator} over the elements in this deque |
808 |
> |
* @since 1.8 |
809 |
> |
*/ |
810 |
> |
public Spliterator<E> spliterator() { |
811 |
> |
return new DeqSpliterator(); |
812 |
> |
} |
813 |
> |
|
814 |
> |
final class DeqSpliterator implements Spliterator<E> { |
815 |
> |
private int fence; // -1 until first use |
816 |
> |
private int cursor; // current index, modified on traverse/split |
817 |
|
|
818 |
< |
public boolean hasNext() { |
819 |
< |
return cursor != fence; |
818 |
> |
/** Constructs late-binding spliterator over all elements. */ |
819 |
> |
DeqSpliterator() { |
820 |
> |
this.fence = -1; |
821 |
|
} |
822 |
|
|
823 |
< |
public E next() { |
824 |
< |
if (cursor == fence) |
825 |
< |
throw new NoSuchElementException(); |
826 |
< |
cursor = (cursor - 1) & (elements.length - 1); |
630 |
< |
@SuppressWarnings("unchecked") |
631 |
< |
E result = (E) elements[cursor]; |
632 |
< |
if (head != fence || result == null) |
633 |
< |
throw new ConcurrentModificationException(); |
634 |
< |
lastRet = cursor; |
635 |
< |
return result; |
823 |
> |
/** Constructs spliterator over the given range. */ |
824 |
> |
DeqSpliterator(int origin, int fence) { |
825 |
> |
this.cursor = origin; |
826 |
> |
this.fence = fence; |
827 |
|
} |
828 |
|
|
829 |
< |
public void remove() { |
830 |
< |
if (lastRet < 0) |
831 |
< |
throw new IllegalStateException(); |
832 |
< |
if (!delete(lastRet)) { |
833 |
< |
cursor = (cursor + 1) & (elements.length - 1); |
834 |
< |
fence = head; |
829 |
> |
/** Ensures late-binding initialization; then returns fence. */ |
830 |
> |
private int getFence() { // force initialization |
831 |
> |
int t; |
832 |
> |
if ((t = fence) < 0) { |
833 |
> |
t = fence = tail; |
834 |
> |
cursor = head; |
835 |
|
} |
836 |
< |
lastRet = -1; |
836 |
> |
return t; |
837 |
> |
} |
838 |
> |
|
839 |
> |
public DeqSpliterator trySplit() { |
840 |
> |
final Object[] es = elements; |
841 |
> |
final int i, n; |
842 |
> |
return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0) |
843 |
> |
? null |
844 |
> |
: new DeqSpliterator(i, cursor = add(i, n, es.length)); |
845 |
> |
} |
846 |
> |
|
847 |
> |
public void forEachRemaining(Consumer<? super E> action) { |
848 |
> |
if (action == null) |
849 |
> |
throw new NullPointerException(); |
850 |
> |
final int end = getFence(), cursor = this.cursor; |
851 |
> |
final Object[] es = elements; |
852 |
> |
if (cursor != end) { |
853 |
> |
this.cursor = end; |
854 |
> |
// null check at both ends of range is sufficient |
855 |
> |
if (es[cursor] == null || es[dec(end, es.length)] == null) |
856 |
> |
throw new ConcurrentModificationException(); |
857 |
> |
for (int i = cursor, to = (i <= end) ? end : es.length; |
858 |
> |
; i = 0, to = end) { |
859 |
> |
for (; i < to; i++) |
860 |
> |
action.accept(elementAt(es, i)); |
861 |
> |
if (to == end) break; |
862 |
> |
} |
863 |
> |
} |
864 |
> |
} |
865 |
> |
|
866 |
> |
public boolean tryAdvance(Consumer<? super E> action) { |
867 |
> |
Objects.requireNonNull(action); |
868 |
> |
final Object[] es = elements; |
869 |
> |
if (fence < 0) { fence = tail; cursor = head; } // late-binding |
870 |
> |
final int i; |
871 |
> |
if ((i = cursor) == fence) |
872 |
> |
return false; |
873 |
> |
E e = nonNullElementAt(es, i); |
874 |
> |
cursor = inc(i, es.length); |
875 |
> |
action.accept(e); |
876 |
> |
return true; |
877 |
|
} |
878 |
+ |
|
879 |
+ |
public long estimateSize() { |
880 |
+ |
return sub(getFence(), cursor, elements.length); |
881 |
+ |
} |
882 |
+ |
|
883 |
+ |
public int characteristics() { |
884 |
+ |
return Spliterator.NONNULL |
885 |
+ |
| Spliterator.ORDERED |
886 |
+ |
| Spliterator.SIZED |
887 |
+ |
| Spliterator.SUBSIZED; |
888 |
+ |
} |
889 |
+ |
} |
890 |
+ |
|
891 |
+ |
public void forEach(Consumer<? super E> action) { |
892 |
+ |
Objects.requireNonNull(action); |
893 |
+ |
final Object[] es = elements; |
894 |
+ |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
895 |
+ |
; i = 0, to = end) { |
896 |
+ |
for (; i < to; i++) |
897 |
+ |
action.accept(elementAt(es, i)); |
898 |
+ |
if (to == end) { |
899 |
+ |
if (end != tail) throw new ConcurrentModificationException(); |
900 |
+ |
break; |
901 |
+ |
} |
902 |
+ |
} |
903 |
+ |
// checkInvariants(); |
904 |
+ |
} |
905 |
+ |
|
906 |
+ |
/** |
907 |
+ |
* Replaces each element of this deque with the result of applying the |
908 |
+ |
* operator to that element, as specified by {@link List#replaceAll}. |
909 |
+ |
* |
910 |
+ |
* @param operator the operator to apply to each element |
911 |
+ |
* @since TBD |
912 |
+ |
*/ |
913 |
+ |
/* public */ void replaceAll(UnaryOperator<E> operator) { |
914 |
+ |
Objects.requireNonNull(operator); |
915 |
+ |
final Object[] es = elements; |
916 |
+ |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
917 |
+ |
; i = 0, to = end) { |
918 |
+ |
for (; i < to; i++) |
919 |
+ |
es[i] = operator.apply(elementAt(es, i)); |
920 |
+ |
if (to == end) { |
921 |
+ |
if (end != tail) throw new ConcurrentModificationException(); |
922 |
+ |
break; |
923 |
+ |
} |
924 |
+ |
} |
925 |
+ |
// checkInvariants(); |
926 |
+ |
} |
927 |
+ |
|
928 |
+ |
/** |
929 |
+ |
* @throws NullPointerException {@inheritDoc} |
930 |
+ |
*/ |
931 |
+ |
public boolean removeIf(Predicate<? super E> filter) { |
932 |
+ |
Objects.requireNonNull(filter); |
933 |
+ |
return bulkRemove(filter); |
934 |
+ |
} |
935 |
+ |
|
936 |
+ |
/** |
937 |
+ |
* @throws NullPointerException {@inheritDoc} |
938 |
+ |
*/ |
939 |
+ |
public boolean removeAll(Collection<?> c) { |
940 |
+ |
Objects.requireNonNull(c); |
941 |
+ |
return bulkRemove(e -> c.contains(e)); |
942 |
+ |
} |
943 |
+ |
|
944 |
+ |
/** |
945 |
+ |
* @throws NullPointerException {@inheritDoc} |
946 |
+ |
*/ |
947 |
+ |
public boolean retainAll(Collection<?> c) { |
948 |
+ |
Objects.requireNonNull(c); |
949 |
+ |
return bulkRemove(e -> !c.contains(e)); |
950 |
+ |
} |
951 |
+ |
|
952 |
+ |
/** Implementation of bulk remove methods. */ |
953 |
+ |
private boolean bulkRemove(Predicate<? super E> filter) { |
954 |
+ |
// checkInvariants(); |
955 |
+ |
final Object[] es = elements; |
956 |
+ |
// Optimize for initial run of survivors |
957 |
+ |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
958 |
+ |
; i = 0, to = end) { |
959 |
+ |
for (; i < to; i++) |
960 |
+ |
if (filter.test(elementAt(es, i))) |
961 |
+ |
return bulkRemoveModified(filter, i); |
962 |
+ |
if (to == end) { |
963 |
+ |
if (end != tail) throw new ConcurrentModificationException(); |
964 |
+ |
break; |
965 |
+ |
} |
966 |
+ |
} |
967 |
+ |
return false; |
968 |
+ |
} |
969 |
+ |
|
970 |
+ |
// A tiny bit set implementation |
971 |
+ |
|
972 |
+ |
private static long[] nBits(int n) { |
973 |
+ |
return new long[((n - 1) >> 6) + 1]; |
974 |
+ |
} |
975 |
+ |
private static void setBit(long[] bits, int i) { |
976 |
+ |
bits[i >> 6] |= 1L << i; |
977 |
+ |
} |
978 |
+ |
private static boolean isClear(long[] bits, int i) { |
979 |
+ |
return (bits[i >> 6] & (1L << i)) == 0; |
980 |
+ |
} |
981 |
+ |
|
982 |
+ |
/** |
983 |
+ |
* Helper for bulkRemove, in case of at least one deletion. |
984 |
+ |
* Tolerate predicates that reentrantly access the collection for |
985 |
+ |
* read (but writers still get CME), so traverse once to find |
986 |
+ |
* elements to delete, a second pass to physically expunge. |
987 |
+ |
* |
988 |
+ |
* @param beg valid index of first element to be deleted |
989 |
+ |
*/ |
990 |
+ |
private boolean bulkRemoveModified( |
991 |
+ |
Predicate<? super E> filter, final int beg) { |
992 |
+ |
final Object[] es = elements; |
993 |
+ |
final int capacity = es.length; |
994 |
+ |
final int end = tail; |
995 |
+ |
final long[] deathRow = nBits(sub(end, beg, capacity)); |
996 |
+ |
deathRow[0] = 1L; // set bit 0 |
997 |
+ |
for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg; |
998 |
+ |
; i = 0, to = end, k -= capacity) { |
999 |
+ |
for (; i < to; i++) |
1000 |
+ |
if (filter.test(elementAt(es, i))) |
1001 |
+ |
setBit(deathRow, i - k); |
1002 |
+ |
if (to == end) break; |
1003 |
+ |
} |
1004 |
+ |
// a two-finger traversal, with hare i reading, tortoise w writing |
1005 |
+ |
int w = beg; |
1006 |
+ |
for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg; |
1007 |
+ |
; w = 0) { // w rejoins i on second leg |
1008 |
+ |
// In this loop, i and w are on the same leg, with i > w |
1009 |
+ |
for (; i < to; i++) |
1010 |
+ |
if (isClear(deathRow, i - k)) |
1011 |
+ |
es[w++] = es[i]; |
1012 |
+ |
if (to == end) break; |
1013 |
+ |
// In this loop, w is on the first leg, i on the second |
1014 |
+ |
for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++) |
1015 |
+ |
if (isClear(deathRow, i - k)) |
1016 |
+ |
es[w++] = es[i]; |
1017 |
+ |
if (i >= to) { |
1018 |
+ |
if (w == capacity) w = 0; // "corner" case |
1019 |
+ |
break; |
1020 |
+ |
} |
1021 |
+ |
} |
1022 |
+ |
if (end != tail) throw new ConcurrentModificationException(); |
1023 |
+ |
circularClear(es, tail = w, end); |
1024 |
+ |
// checkInvariants(); |
1025 |
+ |
return true; |
1026 |
|
} |
1027 |
|
|
1028 |
|
/** |
1035 |
|
*/ |
1036 |
|
public boolean contains(Object o) { |
1037 |
|
if (o != null) { |
1038 |
< |
int mask = elements.length - 1; |
1039 |
< |
int i = head; |
1040 |
< |
for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) { |
1041 |
< |
if (o.equals(x)) |
1042 |
< |
return true; |
1038 |
> |
final Object[] es = elements; |
1039 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
1040 |
> |
; i = 0, to = end) { |
1041 |
> |
for (; i < to; i++) |
1042 |
> |
if (o.equals(es[i])) |
1043 |
> |
return true; |
1044 |
> |
if (to == end) break; |
1045 |
|
} |
1046 |
|
} |
1047 |
|
return false; |
1069 |
|
* The deque will be empty after this call returns. |
1070 |
|
*/ |
1071 |
|
public void clear() { |
1072 |
< |
int h = head; |
1073 |
< |
int t = tail; |
1074 |
< |
if (h != t) { // clear all cells |
1075 |
< |
head = tail = 0; |
1076 |
< |
int i = h; |
1077 |
< |
int mask = elements.length - 1; |
1078 |
< |
do { |
1079 |
< |
elements[i] = null; |
1080 |
< |
i = (i + 1) & mask; |
1081 |
< |
} while (i != t); |
1072 |
> |
circularClear(elements, head, tail); |
1073 |
> |
head = tail = 0; |
1074 |
> |
// checkInvariants(); |
1075 |
> |
} |
1076 |
> |
|
1077 |
> |
/** |
1078 |
> |
* Nulls out slots starting at array index i, upto index end. |
1079 |
> |
*/ |
1080 |
> |
private static void circularClear(Object[] es, int i, int end) { |
1081 |
> |
for (int to = (i <= end) ? end : es.length; |
1082 |
> |
; i = 0, to = end) { |
1083 |
> |
Arrays.fill(es, i, to, null); |
1084 |
> |
if (to == end) break; |
1085 |
|
} |
1086 |
|
} |
1087 |
|
|
1099 |
|
* @return an array containing all of the elements in this deque |
1100 |
|
*/ |
1101 |
|
public Object[] toArray() { |
1102 |
< |
final int head = this.head; |
1103 |
< |
final int tail = this.tail; |
1104 |
< |
boolean wrap = (tail < head); |
1105 |
< |
int end = wrap ? tail + elements.length : tail; |
1106 |
< |
Object[] a = Arrays.copyOfRange(elements, head, end); |
1107 |
< |
if (wrap) |
1108 |
< |
System.arraycopy(elements, 0, a, elements.length - head, tail); |
1102 |
> |
return toArray(Object[].class); |
1103 |
> |
} |
1104 |
> |
|
1105 |
> |
private <T> T[] toArray(Class<T[]> klazz) { |
1106 |
> |
final Object[] es = elements; |
1107 |
> |
final T[] a; |
1108 |
> |
final int head = this.head, tail = this.tail, end; |
1109 |
> |
if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) { |
1110 |
> |
// Uses null extension feature of copyOfRange |
1111 |
> |
a = Arrays.copyOfRange(es, head, end, klazz); |
1112 |
> |
} else { |
1113 |
> |
// integer overflow! |
1114 |
> |
a = Arrays.copyOfRange(es, 0, end - head, klazz); |
1115 |
> |
System.arraycopy(es, head, a, 0, es.length - head); |
1116 |
> |
} |
1117 |
> |
if (end != tail) |
1118 |
> |
System.arraycopy(es, 0, a, es.length - head, tail); |
1119 |
|
return a; |
1120 |
|
} |
1121 |
|
|
1141 |
|
* The following code can be used to dump the deque into a newly |
1142 |
|
* allocated array of {@code String}: |
1143 |
|
* |
1144 |
< |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
1144 |
> |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
1145 |
|
* |
1146 |
|
* Note that {@code toArray(new Object[0])} is identical in function to |
1147 |
|
* {@code toArray()}. |
1157 |
|
*/ |
1158 |
|
@SuppressWarnings("unchecked") |
1159 |
|
public <T> T[] toArray(T[] a) { |
1160 |
< |
final int head = this.head; |
1161 |
< |
final int tail = this.tail; |
1162 |
< |
boolean wrap = (tail < head); |
1163 |
< |
int size = (tail - head) + (wrap ? elements.length : 0); |
1164 |
< |
int firstLeg = size - (wrap ? tail : 0); |
1165 |
< |
int len = a.length; |
1166 |
< |
if (size > len) { |
1167 |
< |
a = (T[]) Arrays.copyOfRange(elements, head, head + size, |
774 |
< |
a.getClass()); |
775 |
< |
} else { |
776 |
< |
System.arraycopy(elements, head, a, 0, firstLeg); |
777 |
< |
if (size < len) |
778 |
< |
a[size] = null; |
1160 |
> |
final int size; |
1161 |
> |
if ((size = size()) > a.length) |
1162 |
> |
return toArray((Class<T[]>) a.getClass()); |
1163 |
> |
final Object[] es = elements; |
1164 |
> |
for (int i = head, j = 0, len = Math.min(size, es.length - i); |
1165 |
> |
; i = 0, len = tail) { |
1166 |
> |
System.arraycopy(es, i, a, j, len); |
1167 |
> |
if ((j += len) == size) break; |
1168 |
|
} |
1169 |
< |
if (wrap) |
1170 |
< |
System.arraycopy(elements, 0, a, firstLeg, tail); |
1169 |
> |
if (size < a.length) |
1170 |
> |
a[size] = null; |
1171 |
|
return a; |
1172 |
|
} |
1173 |
|
|
1208 |
|
s.writeInt(size()); |
1209 |
|
|
1210 |
|
// Write out elements in order. |
1211 |
< |
int mask = elements.length - 1; |
1212 |
< |
for (int i = head; i != tail; i = (i + 1) & mask) |
1213 |
< |
s.writeObject(elements[i]); |
1211 |
> |
final Object[] es = elements; |
1212 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
1213 |
> |
; i = 0, to = end) { |
1214 |
> |
for (; i < to; i++) |
1215 |
> |
s.writeObject(es[i]); |
1216 |
> |
if (to == end) break; |
1217 |
> |
} |
1218 |
|
} |
1219 |
|
|
1220 |
|
/** |
1230 |
|
|
1231 |
|
// Read in size and allocate array |
1232 |
|
int size = s.readInt(); |
1233 |
< |
allocateElements(size); |
1234 |
< |
head = 0; |
842 |
< |
tail = size; |
1233 |
> |
elements = new Object[size + 1]; |
1234 |
> |
this.tail = size; |
1235 |
|
|
1236 |
|
// Read in all elements in the proper order. |
1237 |
|
for (int i = 0; i < size; i++) |
1238 |
|
elements[i] = s.readObject(); |
1239 |
|
} |
1240 |
|
|
1241 |
< |
public Spliterator<E> spliterator() { |
1242 |
< |
return new DeqSpliterator<E>(this, -1, -1); |
1243 |
< |
} |
1244 |
< |
|
1245 |
< |
static final class DeqSpliterator<E> implements Spliterator<E> { |
1246 |
< |
private final ArrayDeque<E> deq; |
1247 |
< |
private int fence; // -1 until first use |
1248 |
< |
private int index; // current index, modified on traverse/split |
1249 |
< |
|
1250 |
< |
/** Creates new spliterator covering the given array and range */ |
1251 |
< |
DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) { |
1252 |
< |
this.deq = deq; |
1253 |
< |
this.index = origin; |
1254 |
< |
this.fence = fence; |
1255 |
< |
} |
1256 |
< |
|
1257 |
< |
private int getFence() { // force initialization |
1258 |
< |
int t; |
1259 |
< |
if ((t = fence) < 0) { |
868 |
< |
t = fence = deq.tail; |
869 |
< |
index = deq.head; |
870 |
< |
} |
871 |
< |
return t; |
872 |
< |
} |
873 |
< |
|
874 |
< |
public Spliterator<E> trySplit() { |
875 |
< |
int t = getFence(), h = index, n = deq.elements.length; |
876 |
< |
if (h != t && ((h + 1) & (n - 1)) != t) { |
877 |
< |
if (h > t) |
878 |
< |
t += n; |
879 |
< |
int m = ((h + t) >>> 1) & (n - 1); |
880 |
< |
return new DeqSpliterator<>(deq, h, index = m); |
881 |
< |
} |
882 |
< |
return null; |
883 |
< |
} |
884 |
< |
|
885 |
< |
public void forEachRemaining(Consumer<? super E> consumer) { |
886 |
< |
if (consumer == null) |
887 |
< |
throw new NullPointerException(); |
888 |
< |
Object[] a = deq.elements; |
889 |
< |
int m = a.length - 1, f = getFence(), i = index; |
890 |
< |
index = f; |
891 |
< |
while (i != f) { |
892 |
< |
@SuppressWarnings("unchecked") E e = (E)a[i]; |
893 |
< |
i = (i + 1) & m; |
894 |
< |
if (e == null) |
895 |
< |
throw new ConcurrentModificationException(); |
896 |
< |
consumer.accept(e); |
897 |
< |
} |
898 |
< |
} |
899 |
< |
|
900 |
< |
public boolean tryAdvance(Consumer<? super E> consumer) { |
901 |
< |
if (consumer == null) |
902 |
< |
throw new NullPointerException(); |
903 |
< |
Object[] a = deq.elements; |
904 |
< |
int m = a.length - 1, f = getFence(), i = index; |
905 |
< |
if (i != fence) { |
906 |
< |
@SuppressWarnings("unchecked") E e = (E)a[i]; |
907 |
< |
index = (i + 1) & m; |
908 |
< |
if (e == null) |
909 |
< |
throw new ConcurrentModificationException(); |
910 |
< |
consumer.accept(e); |
911 |
< |
return true; |
912 |
< |
} |
913 |
< |
return false; |
914 |
< |
} |
915 |
< |
|
916 |
< |
public long estimateSize() { |
917 |
< |
int n = getFence() - index; |
918 |
< |
if (n < 0) |
919 |
< |
n += deq.elements.length; |
920 |
< |
return (long) n; |
921 |
< |
} |
922 |
< |
|
923 |
< |
@Override |
924 |
< |
public int characteristics() { |
925 |
< |
return Spliterator.ORDERED | Spliterator.SIZED | |
926 |
< |
Spliterator.NONNULL | Spliterator.SUBSIZED; |
1241 |
> |
/** debugging */ |
1242 |
> |
void checkInvariants() { |
1243 |
> |
// Use head and tail fields with empty slot at tail strategy. |
1244 |
> |
// head == tail disambiguates to "empty". |
1245 |
> |
try { |
1246 |
> |
int capacity = elements.length; |
1247 |
> |
// assert head >= 0 && head < capacity; |
1248 |
> |
// assert tail >= 0 && tail < capacity; |
1249 |
> |
// assert capacity > 0; |
1250 |
> |
// assert size() < capacity; |
1251 |
> |
// assert head == tail || elements[head] != null; |
1252 |
> |
// assert elements[tail] == null; |
1253 |
> |
// assert head == tail || elements[dec(tail, capacity)] != null; |
1254 |
> |
} catch (Throwable t) { |
1255 |
> |
System.err.printf("head=%d tail=%d capacity=%d%n", |
1256 |
> |
head, tail, elements.length); |
1257 |
> |
System.err.printf("elements=%s%n", |
1258 |
> |
Arrays.toString(elements)); |
1259 |
> |
throw t; |
1260 |
|
} |
1261 |
|
} |
1262 |
|
|