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 |
< |
* We guarantee that all array cells not holding deque elements |
79 |
< |
* 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; |
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 0 <= head < elements.length 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 |
< |
/** Number of elements in this collection. */ |
92 |
< |
transient int size; |
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)); |
94 |
> |
* elements[tail] is always null. |
95 |
> |
*/ |
96 |
> |
transient int tail; |
97 |
|
|
98 |
|
/** |
99 |
|
* The maximum size of array to allocate. |
110 |
|
*/ |
111 |
|
private void grow(int needed) { |
112 |
|
// overflow-conscious code |
95 |
– |
// checkInvariants(); |
113 |
|
final int oldCapacity = elements.length; |
114 |
|
int newCapacity; |
115 |
< |
// Double size if small; else grow by 50% |
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 |
< |
if (oldCapacity - head < size) { |
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, |
154 |
|
* @since TBD |
155 |
|
*/ |
156 |
|
/* public */ void ensureCapacity(int minCapacity) { |
157 |
< |
if (minCapacity > elements.length) |
158 |
< |
grow(minCapacity - elements.length); |
157 |
> |
int needed; |
158 |
> |
if ((needed = (minCapacity + 1 - elements.length)) > 0) |
159 |
> |
grow(needed); |
160 |
|
// checkInvariants(); |
161 |
|
} |
162 |
|
|
166 |
|
* @since TBD |
167 |
|
*/ |
168 |
|
/* public */ void trimToSize() { |
169 |
< |
if (size < elements.length) { |
170 |
< |
elements = toArray(); |
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 |
|
} |
190 |
|
* @param numElements lower bound on initial capacity of the deque |
191 |
|
*/ |
192 |
|
public ArrayDeque(int numElements) { |
193 |
< |
elements = new Object[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 |
< |
Object[] es = c.toArray(); |
211 |
< |
// defend against c.toArray (incorrectly) not returning Object[] |
188 |
< |
// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652) |
189 |
< |
if (es.getClass() != Object[].class) |
190 |
< |
es = Arrays.copyOf(es, es.length, Object[].class); |
191 |
< |
for (Object obj : es) |
192 |
< |
Objects.requireNonNull(obj); |
193 |
< |
this.elements = es; |
194 |
< |
this.size = es.length; |
210 |
> |
this(c.size()); |
211 |
> |
addAll(c); |
212 |
|
} |
213 |
|
|
214 |
|
/** |
230 |
|
} |
231 |
|
|
232 |
|
/** |
233 |
< |
* Adds i and j, mod modulus. |
234 |
< |
* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus. |
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 j, int modulus) { |
238 |
< |
if ((i += j) - modulus >= 0) i -= modulus; |
237 |
> |
static final int add(int i, int distance, int modulus) { |
238 |
> |
if ((i += distance) - modulus >= 0) i -= modulus; |
239 |
|
return i; |
240 |
|
} |
241 |
|
|
242 |
|
/** |
243 |
< |
* Returns the array index of the last element. |
244 |
< |
* May return invalid index -1 if there are no elements. |
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 |
< |
final int tail() { |
250 |
< |
return add(head, size - 1, elements.length); |
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 |
< |
private E elementAt(int i) { |
260 |
< |
return (E) elements[i]; |
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. It's a little |
244 |
< |
* surprising that javac allows this abuse of generics. |
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]; |
283 |
|
* @throws NullPointerException if the specified element is null |
284 |
|
*/ |
285 |
|
public void addFirst(E e) { |
286 |
< |
// checkInvariants(); |
287 |
< |
Objects.requireNonNull(e); |
288 |
< |
Object[] es; |
289 |
< |
int capacity, h; |
290 |
< |
final int s; |
269 |
< |
if ((s = size) == (capacity = (es = elements).length)) { |
286 |
> |
if (e == null) |
287 |
> |
throw new NullPointerException(); |
288 |
> |
final Object[] es = elements; |
289 |
> |
es[head = dec(head, es.length)] = e; |
290 |
> |
if (head == tail) |
291 |
|
grow(1); |
271 |
– |
capacity = (es = elements).length; |
272 |
– |
} |
273 |
– |
if ((h = head - 1) < 0) h = capacity - 1; |
274 |
– |
es[head = h] = e; |
275 |
– |
size = s + 1; |
292 |
|
// checkInvariants(); |
293 |
|
} |
294 |
|
|
301 |
|
* @throws NullPointerException if the specified element is null |
302 |
|
*/ |
303 |
|
public void addLast(E e) { |
304 |
< |
// checkInvariants(); |
305 |
< |
Objects.requireNonNull(e); |
306 |
< |
Object[] es; |
307 |
< |
int capacity; |
308 |
< |
final int s; |
293 |
< |
if ((s = size) == (capacity = (es = elements).length)) { |
304 |
> |
if (e == null) |
305 |
> |
throw new NullPointerException(); |
306 |
> |
final Object[] es = elements; |
307 |
> |
es[tail] = e; |
308 |
> |
if (head == (tail = inc(tail, es.length))) |
309 |
|
grow(1); |
295 |
– |
capacity = (es = elements).length; |
296 |
– |
} |
297 |
– |
es[add(head, s, capacity)] = e; |
298 |
– |
size = s + 1; |
310 |
|
// checkInvariants(); |
311 |
|
} |
312 |
|
|
322 |
|
* of its elements are null |
323 |
|
*/ |
324 |
|
public boolean addAll(Collection<? extends E> c) { |
325 |
< |
final int s = size, needed = c.size() - (elements.length - s); |
326 |
< |
if (needed > 0) |
325 |
> |
final int s, needed; |
326 |
> |
if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0) |
327 |
|
grow(needed); |
328 |
< |
c.forEach((e) -> addLast(e)); |
328 |
> |
c.forEach(this::addLast); |
329 |
|
// checkInvariants(); |
330 |
< |
return size > s; |
330 |
> |
return size() > s; |
331 |
|
} |
332 |
|
|
333 |
|
/** |
358 |
|
* @throws NoSuchElementException {@inheritDoc} |
359 |
|
*/ |
360 |
|
public E removeFirst() { |
350 |
– |
// checkInvariants(); |
361 |
|
E e = pollFirst(); |
362 |
|
if (e == null) |
363 |
|
throw new NoSuchElementException(); |
364 |
+ |
// checkInvariants(); |
365 |
|
return e; |
366 |
|
} |
367 |
|
|
369 |
|
* @throws NoSuchElementException {@inheritDoc} |
370 |
|
*/ |
371 |
|
public E removeLast() { |
361 |
– |
// checkInvariants(); |
372 |
|
E e = pollLast(); |
373 |
|
if (e == null) |
374 |
|
throw new NoSuchElementException(); |
375 |
+ |
// checkInvariants(); |
376 |
|
return e; |
377 |
|
} |
378 |
|
|
379 |
|
public E pollFirst() { |
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(); |
370 |
– |
int s, h; |
371 |
– |
if ((s = size) <= 0) |
372 |
– |
return null; |
373 |
– |
final Object[] es = elements; |
374 |
– |
@SuppressWarnings("unchecked") E e = (E) es[h = head]; |
375 |
– |
es[h] = null; |
376 |
– |
if (++h >= es.length) h = 0; |
377 |
– |
head = h; |
378 |
– |
size = s - 1; |
388 |
|
return e; |
389 |
|
} |
390 |
|
|
391 |
|
public E pollLast() { |
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(); |
384 |
– |
final int s, tail; |
385 |
– |
if ((s = size) <= 0) |
386 |
– |
return null; |
387 |
– |
final Object[] es = elements; |
388 |
– |
@SuppressWarnings("unchecked") |
389 |
– |
E e = (E) es[tail = add(head, s - 1, es.length)]; |
390 |
– |
es[tail] = null; |
391 |
– |
size = s - 1; |
398 |
|
return e; |
399 |
|
} |
400 |
|
|
402 |
|
* @throws NoSuchElementException {@inheritDoc} |
403 |
|
*/ |
404 |
|
public E getFirst() { |
405 |
+ |
E e = elementAt(elements, head); |
406 |
+ |
if (e == null) |
407 |
+ |
throw new NoSuchElementException(); |
408 |
|
// checkInvariants(); |
409 |
< |
if (size <= 0) throw new NoSuchElementException(); |
401 |
< |
return elementAt(head); |
409 |
> |
return e; |
410 |
|
} |
411 |
|
|
412 |
|
/** |
413 |
|
* @throws NoSuchElementException {@inheritDoc} |
414 |
|
*/ |
407 |
– |
@SuppressWarnings("unchecked") |
415 |
|
public E getLast() { |
409 |
– |
// checkInvariants(); |
410 |
– |
final int s; |
411 |
– |
if ((s = size) <= 0) throw new NoSuchElementException(); |
416 |
|
final Object[] es = elements; |
417 |
< |
return (E) es[add(head, s - 1, es.length)]; |
417 |
> |
E e = elementAt(es, dec(tail, es.length)); |
418 |
> |
if (e == null) |
419 |
> |
throw new NoSuchElementException(); |
420 |
> |
// checkInvariants(); |
421 |
> |
return e; |
422 |
|
} |
423 |
|
|
424 |
|
public E peekFirst() { |
425 |
|
// checkInvariants(); |
426 |
< |
return (size <= 0) ? null : elementAt(head); |
426 |
> |
return elementAt(elements, head); |
427 |
|
} |
428 |
|
|
421 |
– |
@SuppressWarnings("unchecked") |
429 |
|
public E peekLast() { |
430 |
|
// checkInvariants(); |
431 |
< |
final int s; |
432 |
< |
if ((s = size) <= 0) return null; |
426 |
< |
final Object[] es = elements; |
427 |
< |
return (E) es[add(head, s - 1, es.length)]; |
431 |
> |
final Object[] es; |
432 |
> |
return elementAt(es = elements, dec(tail, es.length)); |
433 |
|
} |
434 |
|
|
435 |
|
/** |
447 |
|
public boolean removeFirstOccurrence(Object o) { |
448 |
|
if (o != null) { |
449 |
|
final Object[] es = elements; |
450 |
< |
int i, end, to, todo; |
451 |
< |
todo = (end = (i = head) + size) |
447 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
448 |
< |
for (;; to = todo, i = 0, todo = 0) { |
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 (todo == 0) break; |
457 |
> |
if (to == end) break; |
458 |
|
} |
459 |
|
} |
460 |
|
return false; |
475 |
|
public boolean removeLastOccurrence(Object o) { |
476 |
|
if (o != null) { |
477 |
|
final Object[] es = elements; |
478 |
< |
int i, to, end, todo; |
479 |
< |
todo = (to = ((end = (i = tail()) - size) >= -1) ? end : -1) - end; |
480 |
< |
for (;; to = (i = es.length - 1) - todo, todo = 0) { |
478 |
< |
for (; i > to; i--) |
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 (todo == 0) break; |
485 |
> |
if (to == end) break; |
486 |
|
} |
487 |
|
} |
488 |
|
return false; |
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 |
|
boolean delete(int i) { |
616 |
|
// checkInvariants(); |
617 |
|
final Object[] es = elements; |
618 |
|
final int capacity = es.length; |
619 |
< |
final int h = head; |
620 |
< |
int front; // number of elements before to-be-deleted elt |
621 |
< |
if ((front = i - h) < 0) front += capacity; |
622 |
< |
final int back = size - front - 1; // number of elements after |
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) { |
631 |
|
System.arraycopy(es, h, es, h + 1, front - (i + 1)); |
632 |
|
} |
633 |
|
es[h] = null; |
634 |
< |
if ((head = (h + 1)) >= capacity) head = 0; |
632 |
< |
size--; |
634 |
> |
head = inc(h, capacity); |
635 |
|
// checkInvariants(); |
636 |
|
return false; |
637 |
|
} else { |
638 |
|
// move back elements backwards |
639 |
< |
int tail = tail(); |
639 |
> |
tail = dec(t, capacity); |
640 |
|
if (i <= tail) { |
641 |
|
System.arraycopy(es, i + 1, es, i, back); |
642 |
|
} else { // Wrap around |
643 |
< |
int firstLeg = capacity - (i + 1); |
642 |
< |
System.arraycopy(es, i + 1, es, i, firstLeg); |
643 |
> |
System.arraycopy(es, i + 1, es, i, capacity - (i + 1)); |
644 |
|
es[capacity - 1] = es[0]; |
645 |
< |
System.arraycopy(es, 1, es, 0, back - firstLeg - 1); |
645 |
> |
System.arraycopy(es, 1, es, 0, t - 1); |
646 |
|
} |
647 |
|
es[tail] = null; |
647 |
– |
size--; |
648 |
|
// checkInvariants(); |
649 |
|
return true; |
650 |
|
} |
658 |
|
* @return the number of elements in this deque |
659 |
|
*/ |
660 |
|
public int size() { |
661 |
< |
return size; |
661 |
> |
return sub(tail, head, elements.length); |
662 |
|
} |
663 |
|
|
664 |
|
/** |
667 |
|
* @return {@code true} if this deque contains no elements |
668 |
|
*/ |
669 |
|
public boolean isEmpty() { |
670 |
< |
return size == 0; |
670 |
> |
return head == tail; |
671 |
|
} |
672 |
|
|
673 |
|
/** |
691 |
|
int cursor; |
692 |
|
|
693 |
|
/** Number of elements yet to be returned. */ |
694 |
< |
int remaining = size; |
694 |
> |
int remaining = size(); |
695 |
|
|
696 |
|
/** |
697 |
|
* Index of element returned by most recent call to next. |
710 |
|
throw new NoSuchElementException(); |
711 |
|
final Object[] es = elements; |
712 |
|
E e = nonNullElementAt(es, cursor); |
713 |
< |
lastRet = cursor; |
714 |
< |
if (++cursor >= es.length) cursor = 0; |
713 |
> |
cursor = inc(lastRet = cursor, es.length); |
714 |
|
remaining--; |
715 |
|
return e; |
716 |
|
} |
717 |
|
|
718 |
|
void postDelete(boolean leftShifted) { |
719 |
|
if (leftShifted) |
720 |
< |
if (--cursor < 0) cursor = elements.length - 1; |
720 |
> |
cursor = dec(cursor, elements.length); |
721 |
|
} |
722 |
|
|
723 |
|
public final void remove() { |
729 |
|
|
730 |
|
public void forEachRemaining(Consumer<? super E> action) { |
731 |
|
Objects.requireNonNull(action); |
732 |
< |
final int k; |
733 |
< |
if ((k = remaining) > 0) { |
734 |
< |
remaining = 0; |
735 |
< |
ArrayDeque.forEachRemaining(action, elements, cursor, k); |
736 |
< |
if ((lastRet = cursor + k - 1) >= elements.length) |
737 |
< |
lastRet -= elements.length; |
732 |
> |
int r; |
733 |
> |
if ((r = remaining) <= 0) |
734 |
> |
return; |
735 |
> |
remaining = 0; |
736 |
> |
final Object[] es = elements; |
737 |
> |
if (es[cursor] == null || sub(tail, cursor, es.length) != r) |
738 |
> |
throw new ConcurrentModificationException(); |
739 |
> |
for (int i = cursor, end = tail, to = (i <= end) ? end : es.length; |
740 |
> |
; i = 0, to = end) { |
741 |
> |
for (; i < to; i++) |
742 |
> |
action.accept(elementAt(es, i)); |
743 |
> |
if (to == end) { |
744 |
> |
if (end != tail) |
745 |
> |
throw new ConcurrentModificationException(); |
746 |
> |
lastRet = dec(end, es.length); |
747 |
> |
break; |
748 |
> |
} |
749 |
|
} |
750 |
|
} |
751 |
|
} |
752 |
|
|
753 |
|
private class DescendingIterator extends DeqIterator { |
754 |
< |
DescendingIterator() { cursor = tail(); } |
754 |
> |
DescendingIterator() { cursor = dec(tail, elements.length); } |
755 |
|
|
756 |
|
public final E next() { |
757 |
|
if (remaining <= 0) |
758 |
|
throw new NoSuchElementException(); |
759 |
|
final Object[] es = elements; |
760 |
|
E e = nonNullElementAt(es, cursor); |
761 |
< |
lastRet = cursor; |
752 |
< |
if (--cursor < 0) cursor = es.length - 1; |
761 |
> |
cursor = dec(lastRet = cursor, es.length); |
762 |
|
remaining--; |
763 |
|
return e; |
764 |
|
} |
765 |
|
|
766 |
|
void postDelete(boolean leftShifted) { |
767 |
|
if (!leftShifted) |
768 |
< |
if (++cursor >= elements.length) cursor = 0; |
768 |
> |
cursor = inc(cursor, elements.length); |
769 |
|
} |
770 |
|
|
771 |
|
public final void forEachRemaining(Consumer<? super E> action) { |
772 |
|
Objects.requireNonNull(action); |
773 |
< |
final int k; |
774 |
< |
if ((k = remaining) > 0) { |
775 |
< |
remaining = 0; |
776 |
< |
final Object[] es = elements; |
777 |
< |
int i, end, to, todo; |
778 |
< |
todo = (to = ((end = (i = cursor) - k) >= -1) ? end : -1) - end; |
779 |
< |
for (;; to = (i = es.length - 1) - todo, todo = 0) { |
780 |
< |
for (; i > to; i--) |
781 |
< |
action.accept(nonNullElementAt(es, i)); |
782 |
< |
if (todo == 0) break; |
773 |
> |
int r; |
774 |
> |
if ((r = remaining) <= 0) |
775 |
> |
return; |
776 |
> |
remaining = 0; |
777 |
> |
final Object[] es = elements; |
778 |
> |
if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r) |
779 |
> |
throw new ConcurrentModificationException(); |
780 |
> |
for (int i = cursor, end = head, to = (i >= end) ? end : 0; |
781 |
> |
; i = es.length - 1, to = end) { |
782 |
> |
// hotspot generates faster code than for: i >= to ! |
783 |
> |
for (; i > to - 1; i--) |
784 |
> |
action.accept(elementAt(es, i)); |
785 |
> |
if (to == end) { |
786 |
> |
if (end != head) |
787 |
> |
throw new ConcurrentModificationException(); |
788 |
> |
lastRet = end; |
789 |
> |
break; |
790 |
|
} |
775 |
– |
if ((lastRet = cursor - (k - 1)) < 0) |
776 |
– |
lastRet += es.length; |
791 |
|
} |
792 |
|
} |
793 |
|
} |
806 |
|
* @since 1.8 |
807 |
|
*/ |
808 |
|
public Spliterator<E> spliterator() { |
809 |
< |
return new ArrayDequeSpliterator(); |
809 |
> |
return new DeqSpliterator(); |
810 |
|
} |
811 |
|
|
812 |
< |
final class ArrayDequeSpliterator implements Spliterator<E> { |
813 |
< |
private int cursor; |
814 |
< |
private int remaining; // -1 until late-binding first use |
812 |
> |
final class DeqSpliterator implements Spliterator<E> { |
813 |
> |
private int fence; // -1 until first use |
814 |
> |
private int cursor; // current index, modified on traverse/split |
815 |
|
|
816 |
|
/** Constructs late-binding spliterator over all elements. */ |
817 |
< |
ArrayDequeSpliterator() { |
818 |
< |
this.remaining = -1; |
805 |
< |
} |
806 |
< |
|
807 |
< |
/** Constructs spliterator over the given slice. */ |
808 |
< |
ArrayDequeSpliterator(int cursor, int count) { |
809 |
< |
this.cursor = cursor; |
810 |
< |
this.remaining = count; |
817 |
> |
DeqSpliterator() { |
818 |
> |
this.fence = -1; |
819 |
|
} |
820 |
|
|
821 |
< |
/** Ensures late-binding initialization; then returns remaining. */ |
822 |
< |
private int remaining() { |
823 |
< |
if (remaining < 0) { |
821 |
> |
/** Constructs spliterator over the given range. */ |
822 |
> |
DeqSpliterator(int origin, int fence) { |
823 |
> |
// assert 0 <= origin && origin < elements.length; |
824 |
> |
// assert 0 <= fence && fence < elements.length; |
825 |
> |
this.cursor = origin; |
826 |
> |
this.fence = fence; |
827 |
> |
} |
828 |
> |
|
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; |
817 |
– |
remaining = size; |
835 |
|
} |
836 |
< |
return remaining; |
836 |
> |
return t; |
837 |
|
} |
838 |
|
|
839 |
< |
public ArrayDequeSpliterator trySplit() { |
840 |
< |
final int mid; |
841 |
< |
if ((mid = remaining() >> 1) > 0) { |
842 |
< |
int oldCursor = cursor; |
843 |
< |
cursor = add(cursor, mid, elements.length); |
844 |
< |
remaining -= mid; |
828 |
< |
return new ArrayDequeSpliterator(oldCursor, mid); |
829 |
< |
} |
830 |
< |
return null; |
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 |
< |
Objects.requireNonNull(action); |
849 |
< |
final int k = remaining(); // side effect! |
850 |
< |
remaining = 0; |
851 |
< |
ArrayDeque.forEachRemaining(action, elements, cursor, k); |
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 int k; |
869 |
< |
if ((k = remaining()) <= 0) |
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 |
< |
action.accept(nonNullElementAt(elements, cursor)); |
874 |
< |
if (++cursor >= elements.length) cursor = 0; |
875 |
< |
remaining = k - 1; |
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 remaining(); |
880 |
> |
return sub(getFence(), cursor, elements.length); |
881 |
|
} |
882 |
|
|
883 |
|
public int characteristics() { |
888 |
|
} |
889 |
|
} |
890 |
|
|
863 |
– |
@SuppressWarnings("unchecked") |
891 |
|
public void forEach(Consumer<? super E> action) { |
892 |
|
Objects.requireNonNull(action); |
893 |
|
final Object[] es = elements; |
894 |
< |
int i, end, to, todo; |
895 |
< |
todo = (end = (i = head) + size) |
869 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
870 |
< |
for (;; to = todo, i = 0, todo = 0) { |
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((E) es[i]); |
898 |
< |
if (todo == 0) break; |
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 |
|
/** |
879 |
– |
* Calls action on remaining elements, starting at index i and |
880 |
– |
* traversing in ascending order. A variant of forEach that also |
881 |
– |
* checks for concurrent modification, for use in iterators. |
882 |
– |
*/ |
883 |
– |
static <E> void forEachRemaining( |
884 |
– |
Consumer<? super E> action, Object[] es, int i, int remaining) { |
885 |
– |
int end, to, todo; |
886 |
– |
todo = (end = i + remaining) |
887 |
– |
- (to = (es.length - end >= 0) ? end : es.length); |
888 |
– |
for (;; to = todo, i = 0, todo = 0) { |
889 |
– |
for (; i < to; i++) |
890 |
– |
action.accept(nonNullElementAt(es, i)); |
891 |
– |
if (todo == 0) break; |
892 |
– |
} |
893 |
– |
} |
894 |
– |
|
895 |
– |
/** |
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 |
|
*/ |
902 |
– |
@SuppressWarnings("unchecked") |
913 |
|
/* public */ void replaceAll(UnaryOperator<E> operator) { |
914 |
|
Objects.requireNonNull(operator); |
915 |
|
final Object[] es = elements; |
916 |
< |
int i, end, to, todo; |
917 |
< |
todo = (end = (i = head) + size) |
908 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
909 |
< |
for (;; to = todo, i = 0, todo = 0) { |
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((E) es[i]); |
920 |
< |
if (todo == 0) break; |
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 |
|
} |
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 |
< |
int i = head, j = i, remaining = size, deleted = 0; |
995 |
< |
try { |
996 |
< |
for (; remaining > 0; remaining--) { |
997 |
< |
@SuppressWarnings("unchecked") E e = (E) es[i]; |
998 |
< |
if (filter.test(e)) |
999 |
< |
deleted++; |
1000 |
< |
else { |
1001 |
< |
if (j != i) |
1002 |
< |
es[j] = e; |
1003 |
< |
if (++j >= capacity) j = 0; |
1004 |
< |
} |
1005 |
< |
if (++i >= capacity) i = 0; |
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 |
|
} |
959 |
– |
return deleted > 0; |
960 |
– |
} catch (Throwable ex) { |
961 |
– |
if (deleted > 0) |
962 |
– |
for (; remaining > 0; remaining--) { |
963 |
– |
es[j] = es[i]; |
964 |
– |
if (++i >= capacity) i = 0; |
965 |
– |
if (++j >= capacity) j = 0; |
966 |
– |
} |
967 |
– |
throw ex; |
968 |
– |
} finally { |
969 |
– |
size -= deleted; |
970 |
– |
clearSlice(es, j, deleted); |
971 |
– |
// checkInvariants(); |
1021 |
|
} |
1022 |
+ |
if (end != tail) throw new ConcurrentModificationException(); |
1023 |
+ |
circularClear(es, tail = w, end); |
1024 |
+ |
// checkInvariants(); |
1025 |
+ |
return true; |
1026 |
|
} |
1027 |
|
|
1028 |
|
/** |
1036 |
|
public boolean contains(Object o) { |
1037 |
|
if (o != null) { |
1038 |
|
final Object[] es = elements; |
1039 |
< |
int i, end, to, todo; |
1040 |
< |
todo = (end = (i = head) + size) |
988 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
989 |
< |
for (;; to = todo, i = 0, todo = 0) { |
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 (todo == 0) break; |
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 |
< |
clearSlice(elements, head, size); |
1073 |
< |
size = head = 0; |
1072 |
> |
circularClear(elements, head, tail); |
1073 |
> |
head = tail = 0; |
1074 |
|
// checkInvariants(); |
1075 |
|
} |
1076 |
|
|
1077 |
|
/** |
1078 |
< |
* Nulls out count elements, starting at array index i. |
1078 |
> |
* Nulls out slots starting at array index i, upto index end. |
1079 |
|
*/ |
1080 |
< |
private static void clearSlice(Object[] es, int i, int count) { |
1081 |
< |
int end, to, todo; |
1082 |
< |
todo = (end = i + count) |
1032 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
1033 |
< |
for (;; to = todo, i = 0, todo = 0) { |
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 (todo == 0) break; |
1084 |
> |
if (to == end) break; |
1085 |
|
} |
1086 |
|
} |
1087 |
|
|
1104 |
|
|
1105 |
|
private <T> T[] toArray(Class<T[]> klazz) { |
1106 |
|
final Object[] es = elements; |
1058 |
– |
final int capacity = es.length; |
1059 |
– |
final int head = this.head, end = head + size; |
1107 |
|
final T[] a; |
1108 |
< |
if (end >= 0) { |
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, size, klazz); |
1115 |
< |
System.arraycopy(es, head, a, 0, capacity - head); |
1114 |
> |
a = Arrays.copyOfRange(es, 0, end - head, klazz); |
1115 |
> |
System.arraycopy(es, head, a, 0, es.length - head); |
1116 |
|
} |
1117 |
< |
if (end - capacity > 0) |
1118 |
< |
System.arraycopy(es, 0, a, capacity - head, end - capacity); |
1117 |
> |
if (end != tail) |
1118 |
> |
System.arraycopy(es, 0, a, es.length - head, tail); |
1119 |
|
return a; |
1120 |
|
} |
1121 |
|
|
1158 |
|
@SuppressWarnings("unchecked") |
1159 |
|
public <T> T[] toArray(T[] a) { |
1160 |
|
final int size; |
1161 |
< |
if ((size = this.size) > a.length) |
1161 |
> |
if ((size = size()) > a.length) |
1162 |
|
return toArray((Class<T[]>) a.getClass()); |
1163 |
|
final Object[] es = elements; |
1164 |
< |
final int head = this.head, end = head + size; |
1165 |
< |
final int front = (es.length - end >= 0) ? size : es.length - head; |
1166 |
< |
System.arraycopy(es, head, a, 0, front); |
1167 |
< |
if (front < size) |
1168 |
< |
System.arraycopy(es, 0, a, front, size - front); |
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 (size < a.length) |
1170 |
|
a[size] = null; |
1171 |
|
return a; |
1205 |
|
s.defaultWriteObject(); |
1206 |
|
|
1207 |
|
// Write out size |
1208 |
< |
s.writeInt(size); |
1208 |
> |
s.writeInt(size()); |
1209 |
|
|
1210 |
|
// Write out elements in order. |
1211 |
|
final Object[] es = elements; |
1212 |
< |
int i, end, to, todo; |
1213 |
< |
todo = (end = (i = head) + size) |
1165 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
1166 |
< |
for (;; to = todo, i = 0, todo = 0) { |
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 (todo == 0) break; |
1216 |
> |
if (to == end) break; |
1217 |
|
} |
1218 |
|
} |
1219 |
|
|
1229 |
|
s.defaultReadObject(); |
1230 |
|
|
1231 |
|
// Read in size and allocate array |
1232 |
< |
elements = new Object[size = s.readInt()]; |
1232 |
> |
int size = s.readInt(); |
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++) |
1240 |
|
|
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 size >= 0 && size <= capacity; |
1248 |
< |
// assert head >= 0; |
1249 |
< |
// assert capacity == 0 || head < capacity; |
1250 |
< |
// assert size == 0 || elements[head] != null; |
1251 |
< |
// assert size == 0 || elements[tail()] != null; |
1252 |
< |
// assert size == capacity || elements[dec(head, capacity)] == null; |
1253 |
< |
// assert size == capacity || elements[inc(tail(), capacity)] == null; |
1247 |
> |
// assert 0 <= head && head < capacity; |
1248 |
> |
// assert 0 <= tail && 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 size=%d capacity=%d%n", |
1256 |
< |
head, size, elements.length); |
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; |