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. |
72 |
+ |
*/ |
73 |
+ |
|
74 |
|
/** |
75 |
|
* The array in which the elements of the deque are stored. |
76 |
|
* We guarantee that all array cells not holding deque elements |
81 |
|
/** |
82 |
|
* The index of the element at the head of the deque (which is the |
83 |
|
* element that would be removed by remove() or pop()); or an |
84 |
< |
* arbitrary number 0 <= head < elements.length if the deque is empty. |
84 |
> |
* arbitrary number 0 <= head < elements.length equal to tail if |
85 |
> |
* the deque is empty. |
86 |
|
*/ |
87 |
|
transient int head; |
88 |
|
|
89 |
< |
/** Number of elements in this collection. */ |
90 |
< |
transient int size; |
89 |
> |
/** |
90 |
> |
* The index at which the next element would be added to the tail |
91 |
> |
* of the deque (via addLast(E), add(E), or push(E)). |
92 |
> |
*/ |
93 |
> |
transient int tail; |
94 |
|
|
95 |
|
/** |
96 |
|
* The maximum size of array to allocate. |
105 |
|
* |
106 |
|
* @param needed the required minimum extra capacity; must be positive |
107 |
|
*/ |
108 |
< |
private Object[] grow(int needed) { |
108 |
> |
private void grow(int needed) { |
109 |
|
// overflow-conscious code |
95 |
– |
// checkInvariants(); |
110 |
|
final int oldCapacity = elements.length; |
111 |
|
int newCapacity; |
112 |
< |
// Double size if small; else grow by 50% |
112 |
> |
// Double capacity if small; else grow by 50% |
113 |
|
int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1); |
114 |
|
if (jump < needed |
115 |
|
|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0) |
116 |
|
newCapacity = newCapacity(needed, jump); |
117 |
|
elements = Arrays.copyOf(elements, newCapacity); |
118 |
< |
if (oldCapacity - head < size) { |
118 |
> |
// Exceptionally, here tail == head needs to be disambiguated |
119 |
> |
if (tail < head || (tail == head && elements[head] != null)) { |
120 |
|
// wrap around; slide first leg forward to end of array |
121 |
|
int newSpace = newCapacity - oldCapacity; |
122 |
|
System.arraycopy(elements, head, |
125 |
|
Arrays.fill(elements, head, head + newSpace, null); |
126 |
|
head += newSpace; |
127 |
|
} |
113 |
– |
return elements; |
128 |
|
// checkInvariants(); |
129 |
|
} |
130 |
|
|
151 |
|
* @since TBD |
152 |
|
*/ |
153 |
|
/* public */ void ensureCapacity(int minCapacity) { |
154 |
< |
if (minCapacity > elements.length) |
155 |
< |
grow(minCapacity - elements.length); |
154 |
> |
int needed; |
155 |
> |
if ((needed = (minCapacity + 1 - elements.length)) > 0) |
156 |
> |
grow(needed); |
157 |
|
// checkInvariants(); |
158 |
|
} |
159 |
|
|
163 |
|
* @since TBD |
164 |
|
*/ |
165 |
|
/* public */ void trimToSize() { |
166 |
< |
if (size < elements.length) { |
167 |
< |
elements = toArray(); |
166 |
> |
int size; |
167 |
> |
if ((size = size()) + 1 < elements.length) { |
168 |
> |
elements = toArray(new Object[size + 1]); |
169 |
|
head = 0; |
170 |
+ |
tail = size; |
171 |
|
} |
172 |
|
// checkInvariants(); |
173 |
|
} |
187 |
|
* @param numElements lower bound on initial capacity of the deque |
188 |
|
*/ |
189 |
|
public ArrayDeque(int numElements) { |
190 |
< |
elements = new Object[numElements]; |
190 |
> |
elements = new Object[Math.max(1, numElements + 1)]; |
191 |
|
} |
192 |
|
|
193 |
|
/** |
201 |
|
* @throws NullPointerException if the specified collection is null |
202 |
|
*/ |
203 |
|
public ArrayDeque(Collection<? extends E> c) { |
204 |
< |
Object[] es = c.toArray(); |
205 |
< |
// defend against c.toArray (incorrectly) not returning Object[] |
189 |
< |
// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652) |
190 |
< |
if (es.getClass() != Object[].class) |
191 |
< |
es = Arrays.copyOf(es, es.length, Object[].class); |
192 |
< |
for (Object obj : es) |
193 |
< |
Objects.requireNonNull(obj); |
194 |
< |
this.elements = es; |
195 |
< |
this.size = es.length; |
204 |
> |
elements = new Object[c.size() + 1]; |
205 |
> |
addAll(c); |
206 |
|
} |
207 |
|
|
208 |
|
/** |
233 |
|
} |
234 |
|
|
235 |
|
/** |
236 |
< |
* Returns the array index of the last element. |
237 |
< |
* May return invalid index -1 if there are no elements. |
236 |
> |
* Subtracts j from i, mod modulus. |
237 |
> |
* Index i must be logically ahead of j. |
238 |
> |
* Returns the "circular distance" from j to i. |
239 |
> |
* Precondition and postcondition: 0 <= i < modulus, 0 <= j < modulus. |
240 |
|
*/ |
241 |
< |
final int tail() { |
242 |
< |
return add(head, size - 1, elements.length); |
241 |
> |
static final int sub(int i, int j, int modulus) { |
242 |
> |
if ((i -= j) < 0) i += modulus; |
243 |
> |
return i; |
244 |
|
} |
245 |
|
|
246 |
|
/** |
247 |
|
* Returns element at array index i. |
248 |
+ |
* This is a slight abuse of generics, accepted by javac. |
249 |
|
*/ |
250 |
|
@SuppressWarnings("unchecked") |
251 |
< |
private E elementAt(int i) { |
252 |
< |
return (E) elements[i]; |
251 |
> |
static final <E> E elementAt(Object[] es, int i) { |
252 |
> |
return (E) es[i]; |
253 |
|
} |
254 |
|
|
255 |
|
/** |
256 |
|
* A version of elementAt that checks for null elements. |
257 |
|
* This check doesn't catch all possible comodifications, |
258 |
< |
* but does catch ones that corrupt traversal. It's a little |
245 |
< |
* surprising that javac allows this abuse of generics. |
258 |
> |
* but does catch ones that corrupt traversal. |
259 |
|
*/ |
260 |
|
static final <E> E nonNullElementAt(Object[] es, int i) { |
261 |
|
@SuppressWarnings("unchecked") E e = (E) es[i]; |
275 |
|
* @throws NullPointerException if the specified element is null |
276 |
|
*/ |
277 |
|
public void addFirst(E e) { |
278 |
< |
// checkInvariants(); |
279 |
< |
Objects.requireNonNull(e); |
280 |
< |
Object[] es; |
281 |
< |
int capacity, h; |
282 |
< |
final int s; |
283 |
< |
if ((s = size) == (capacity = (es = elements).length)) |
271 |
< |
capacity = (es = grow(1)).length; |
272 |
< |
if ((h = head - 1) < 0) h = capacity - 1; |
273 |
< |
es[head = h] = e; |
274 |
< |
size = s + 1; |
278 |
> |
if (e == null) |
279 |
> |
throw new NullPointerException(); |
280 |
> |
final Object[] es = elements; |
281 |
> |
es[head = dec(head, es.length)] = e; |
282 |
> |
if (head == tail) |
283 |
> |
grow(1); |
284 |
|
// checkInvariants(); |
285 |
|
} |
286 |
|
|
293 |
|
* @throws NullPointerException if the specified element is null |
294 |
|
*/ |
295 |
|
public void addLast(E e) { |
296 |
< |
// checkInvariants(); |
297 |
< |
Objects.requireNonNull(e); |
298 |
< |
Object[] es; |
299 |
< |
int capacity; |
300 |
< |
final int s; |
301 |
< |
if ((s = size) == (capacity = (es = elements).length)) |
293 |
< |
capacity = (es = grow(1)).length; |
294 |
< |
es[add(head, s, capacity)] = e; |
295 |
< |
size = s + 1; |
296 |
> |
if (e == null) |
297 |
> |
throw new NullPointerException(); |
298 |
> |
final Object[] es = elements; |
299 |
> |
es[tail] = e; |
300 |
> |
if (head == (tail = inc(tail, es.length))) |
301 |
> |
grow(1); |
302 |
|
// checkInvariants(); |
303 |
|
} |
304 |
|
|
314 |
|
* of its elements are null |
315 |
|
*/ |
316 |
|
public boolean addAll(Collection<? extends E> c) { |
317 |
< |
final int s = size, needed = c.size() - (elements.length - s); |
318 |
< |
if (needed > 0) |
317 |
> |
final int s = size(), needed; |
318 |
> |
if ((needed = s + c.size() - elements.length + 1) > 0) |
319 |
|
grow(needed); |
320 |
|
c.forEach((e) -> addLast(e)); |
321 |
|
// checkInvariants(); |
322 |
< |
return size > s; |
322 |
> |
return size() > s; |
323 |
|
} |
324 |
|
|
325 |
|
/** |
350 |
|
* @throws NoSuchElementException {@inheritDoc} |
351 |
|
*/ |
352 |
|
public E removeFirst() { |
347 |
– |
// checkInvariants(); |
353 |
|
E e = pollFirst(); |
354 |
|
if (e == null) |
355 |
|
throw new NoSuchElementException(); |
356 |
+ |
// checkInvariants(); |
357 |
|
return e; |
358 |
|
} |
359 |
|
|
361 |
|
* @throws NoSuchElementException {@inheritDoc} |
362 |
|
*/ |
363 |
|
public E removeLast() { |
358 |
– |
// checkInvariants(); |
364 |
|
E e = pollLast(); |
365 |
|
if (e == null) |
366 |
|
throw new NoSuchElementException(); |
367 |
+ |
// checkInvariants(); |
368 |
|
return e; |
369 |
|
} |
370 |
|
|
371 |
|
public E pollFirst() { |
372 |
+ |
final Object[] es; |
373 |
+ |
final int h; |
374 |
+ |
E e = elementAt(es = elements, h = head); |
375 |
+ |
if (e != null) { |
376 |
+ |
es[h] = null; |
377 |
+ |
head = inc(h, es.length); |
378 |
+ |
} |
379 |
|
// checkInvariants(); |
367 |
– |
int s, h; |
368 |
– |
if ((s = size) <= 0) |
369 |
– |
return null; |
370 |
– |
final Object[] es = elements; |
371 |
– |
@SuppressWarnings("unchecked") E e = (E) es[h = head]; |
372 |
– |
es[h] = null; |
373 |
– |
if (++h >= es.length) h = 0; |
374 |
– |
head = h; |
375 |
– |
size = s - 1; |
380 |
|
return e; |
381 |
|
} |
382 |
|
|
383 |
|
public E pollLast() { |
384 |
+ |
final Object[] es; |
385 |
+ |
final int t; |
386 |
+ |
E e = elementAt(es = elements, t = dec(tail, es.length)); |
387 |
+ |
if (e != null) |
388 |
+ |
es[tail = t] = null; |
389 |
|
// checkInvariants(); |
381 |
– |
final int s, tail; |
382 |
– |
if ((s = size) <= 0) |
383 |
– |
return null; |
384 |
– |
final Object[] es = elements; |
385 |
– |
@SuppressWarnings("unchecked") |
386 |
– |
E e = (E) es[tail = add(head, s - 1, es.length)]; |
387 |
– |
es[tail] = null; |
388 |
– |
size = s - 1; |
390 |
|
return e; |
391 |
|
} |
392 |
|
|
394 |
|
* @throws NoSuchElementException {@inheritDoc} |
395 |
|
*/ |
396 |
|
public E getFirst() { |
397 |
+ |
E e = elementAt(elements, head); |
398 |
+ |
if (e == null) |
399 |
+ |
throw new NoSuchElementException(); |
400 |
|
// checkInvariants(); |
401 |
< |
if (size <= 0) throw new NoSuchElementException(); |
398 |
< |
return elementAt(head); |
401 |
> |
return e; |
402 |
|
} |
403 |
|
|
404 |
|
/** |
405 |
|
* @throws NoSuchElementException {@inheritDoc} |
406 |
|
*/ |
404 |
– |
@SuppressWarnings("unchecked") |
407 |
|
public E getLast() { |
406 |
– |
// checkInvariants(); |
407 |
– |
final int s; |
408 |
– |
if ((s = size) <= 0) throw new NoSuchElementException(); |
408 |
|
final Object[] es = elements; |
409 |
< |
return (E) es[add(head, s - 1, es.length)]; |
409 |
> |
E e = elementAt(es, dec(tail, es.length)); |
410 |
> |
if (e == null) |
411 |
> |
throw new NoSuchElementException(); |
412 |
> |
// checkInvariants(); |
413 |
> |
return e; |
414 |
|
} |
415 |
|
|
416 |
|
public E peekFirst() { |
417 |
|
// checkInvariants(); |
418 |
< |
return (size <= 0) ? null : elementAt(head); |
418 |
> |
return elementAt(elements, head); |
419 |
|
} |
420 |
|
|
418 |
– |
@SuppressWarnings("unchecked") |
421 |
|
public E peekLast() { |
422 |
|
// checkInvariants(); |
423 |
< |
final int s; |
424 |
< |
if ((s = size) <= 0) return null; |
423 |
< |
final Object[] es = elements; |
424 |
< |
return (E) es[add(head, s - 1, es.length)]; |
423 |
> |
final Object[] es; |
424 |
> |
return elementAt(es = elements, dec(tail, es.length)); |
425 |
|
} |
426 |
|
|
427 |
|
/** |
439 |
|
public boolean removeFirstOccurrence(Object o) { |
440 |
|
if (o != null) { |
441 |
|
final Object[] es = elements; |
442 |
< |
int i, end, to, todo; |
443 |
< |
todo = (end = (i = head) + size) |
444 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
445 |
< |
for (;; to = todo, todo = 0, i = 0) { |
442 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
443 |
> |
; i = 0, to = end) { |
444 |
|
for (; i < to; i++) |
445 |
|
if (o.equals(es[i])) { |
446 |
|
delete(i); |
447 |
|
return true; |
448 |
|
} |
449 |
< |
if (todo == 0) break; |
449 |
> |
if (to == end) break; |
450 |
|
} |
451 |
|
} |
452 |
|
return false; |
467 |
|
public boolean removeLastOccurrence(Object o) { |
468 |
|
if (o != null) { |
469 |
|
final Object[] es = elements; |
470 |
< |
int i, to, end, todo; |
471 |
< |
todo = (to = ((end = (i = tail()) - size) >= -1) ? end : -1) - end; |
472 |
< |
for (;; to = (i = es.length - 1) - todo, todo = 0) { |
475 |
< |
for (; i > to; i--) |
470 |
> |
for (int i = tail, end = head, to = (i >= end) ? end : 0; |
471 |
> |
; i = es.length, to = end) { |
472 |
> |
for (i--; i > to - 1; i--) |
473 |
|
if (o.equals(es[i])) { |
474 |
|
delete(i); |
475 |
|
return true; |
476 |
|
} |
477 |
< |
if (todo == 0) break; |
477 |
> |
if (to == end) break; |
478 |
|
} |
479 |
|
} |
480 |
|
return false; |
602 |
|
* <p>This method is called delete rather than remove to emphasize |
603 |
|
* that its semantics differ from those of {@link List#remove(int)}. |
604 |
|
* |
605 |
< |
* @return true if elements moved backwards |
605 |
> |
* @return true if elements near tail moved backwards |
606 |
|
*/ |
607 |
|
boolean delete(int i) { |
608 |
|
// checkInvariants(); |
609 |
|
final Object[] es = elements; |
610 |
|
final int capacity = es.length; |
611 |
|
final int h = head; |
612 |
< |
int front; // number of elements before to-be-deleted elt |
613 |
< |
if ((front = i - h) < 0) front += capacity; |
614 |
< |
final int back = size - front - 1; // number of elements after |
612 |
> |
// number of elements before to-be-deleted elt |
613 |
> |
final int front = sub(i, h, capacity); |
614 |
> |
final int back = size() - front - 1; // number of elements after |
615 |
|
if (front < back) { |
616 |
|
// move front elements forwards |
617 |
|
if (h <= i) { |
622 |
|
System.arraycopy(es, h, es, h + 1, front - (i + 1)); |
623 |
|
} |
624 |
|
es[h] = null; |
625 |
< |
if ((head = (h + 1)) >= capacity) head = 0; |
629 |
< |
size--; |
625 |
> |
head = inc(h, capacity); |
626 |
|
// checkInvariants(); |
627 |
|
return false; |
628 |
|
} else { |
629 |
|
// move back elements backwards |
630 |
< |
int tail = tail(); |
630 |
> |
tail = dec(tail, capacity); |
631 |
|
if (i <= tail) { |
632 |
|
System.arraycopy(es, i + 1, es, i, back); |
633 |
|
} else { // Wrap around |
637 |
|
System.arraycopy(es, 1, es, 0, back - firstLeg - 1); |
638 |
|
} |
639 |
|
es[tail] = null; |
644 |
– |
size--; |
640 |
|
// checkInvariants(); |
641 |
|
return true; |
642 |
|
} |
650 |
|
* @return the number of elements in this deque |
651 |
|
*/ |
652 |
|
public int size() { |
653 |
< |
return size; |
653 |
> |
return sub(tail, head, elements.length); |
654 |
|
} |
655 |
|
|
656 |
|
/** |
659 |
|
* @return {@code true} if this deque contains no elements |
660 |
|
*/ |
661 |
|
public boolean isEmpty() { |
662 |
< |
return size == 0; |
662 |
> |
return head == tail; |
663 |
|
} |
664 |
|
|
665 |
|
/** |
683 |
|
int cursor; |
684 |
|
|
685 |
|
/** Number of elements yet to be returned. */ |
686 |
< |
int remaining = size; |
686 |
> |
int remaining = size(); |
687 |
|
|
688 |
|
/** |
689 |
|
* Index of element returned by most recent call to next. |
703 |
|
final Object[] es = elements; |
704 |
|
E e = nonNullElementAt(es, cursor); |
705 |
|
lastRet = cursor; |
706 |
< |
if (++cursor >= es.length) cursor = 0; |
706 |
> |
cursor = inc(cursor, es.length); |
707 |
|
remaining--; |
708 |
|
return e; |
709 |
|
} |
710 |
|
|
711 |
|
void postDelete(boolean leftShifted) { |
712 |
|
if (leftShifted) |
713 |
< |
if (--cursor < 0) cursor = elements.length - 1; |
713 |
> |
cursor = dec(cursor, elements.length); |
714 |
|
} |
715 |
|
|
716 |
|
public final void remove() { |
722 |
|
|
723 |
|
public void forEachRemaining(Consumer<? super E> action) { |
724 |
|
Objects.requireNonNull(action); |
725 |
< |
final int k; |
726 |
< |
if ((k = remaining) > 0) { |
727 |
< |
remaining = 0; |
728 |
< |
ArrayDeque.forEachRemaining(action, elements, cursor, k); |
729 |
< |
if ((lastRet = cursor + k - 1) >= elements.length) |
730 |
< |
lastRet -= elements.length; |
725 |
> |
int r; |
726 |
> |
if ((r = remaining) <= 0) |
727 |
> |
return; |
728 |
> |
remaining = 0; |
729 |
> |
final Object[] es = elements; |
730 |
> |
if (es[cursor] == null || sub(tail, cursor, es.length) != r) |
731 |
> |
throw new ConcurrentModificationException(); |
732 |
> |
for (int i = cursor, end = tail, to = (i <= end) ? end : es.length; |
733 |
> |
; i = 0, to = end) { |
734 |
> |
for (; i < to; i++) |
735 |
> |
action.accept(elementAt(es, i)); |
736 |
> |
if (to == end) { |
737 |
> |
if (end != tail) |
738 |
> |
throw new ConcurrentModificationException(); |
739 |
> |
lastRet = dec(end, es.length); |
740 |
> |
break; |
741 |
> |
} |
742 |
|
} |
743 |
|
} |
744 |
|
} |
745 |
|
|
746 |
|
private class DescendingIterator extends DeqIterator { |
747 |
< |
DescendingIterator() { cursor = tail(); } |
747 |
> |
DescendingIterator() { cursor = dec(tail, elements.length); } |
748 |
|
|
749 |
|
public final E next() { |
750 |
|
if (remaining <= 0) |
752 |
|
final Object[] es = elements; |
753 |
|
E e = nonNullElementAt(es, cursor); |
754 |
|
lastRet = cursor; |
755 |
< |
if (--cursor < 0) cursor = es.length - 1; |
755 |
> |
cursor = dec(cursor, es.length); |
756 |
|
remaining--; |
757 |
|
return e; |
758 |
|
} |
759 |
|
|
760 |
|
void postDelete(boolean leftShifted) { |
761 |
|
if (!leftShifted) |
762 |
< |
if (++cursor >= elements.length) cursor = 0; |
762 |
> |
cursor = inc(cursor, elements.length); |
763 |
|
} |
764 |
|
|
765 |
|
public final void forEachRemaining(Consumer<? super E> action) { |
766 |
|
Objects.requireNonNull(action); |
767 |
< |
final int k; |
768 |
< |
if ((k = remaining) > 0) { |
769 |
< |
remaining = 0; |
770 |
< |
final Object[] es = elements; |
771 |
< |
int i, end, to, todo; |
772 |
< |
todo = (to = ((end = (i = cursor) - k) >= -1) ? end : -1) - end; |
773 |
< |
for (;; to = (i = es.length - 1) - todo, todo = 0) { |
774 |
< |
for (; i > to; i--) |
775 |
< |
action.accept(nonNullElementAt(es, i)); |
776 |
< |
if (todo == 0) break; |
767 |
> |
int r; |
768 |
> |
if ((r = remaining) <= 0) |
769 |
> |
return; |
770 |
> |
remaining = 0; |
771 |
> |
final Object[] es = elements; |
772 |
> |
if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r) |
773 |
> |
throw new ConcurrentModificationException(); |
774 |
> |
for (int i = cursor, end = head, to = (i >= end) ? end : 0; |
775 |
> |
; i = es.length - 1, to = end) { |
776 |
> |
// hotspot generates faster code than for: i >= to ! |
777 |
> |
for (; i > to - 1; i--) |
778 |
> |
action.accept(elementAt(es, i)); |
779 |
> |
if (to == end) { |
780 |
> |
if (end != head) |
781 |
> |
throw new ConcurrentModificationException(); |
782 |
> |
lastRet = head; |
783 |
> |
break; |
784 |
|
} |
772 |
– |
if ((lastRet = cursor - (k - 1)) < 0) |
773 |
– |
lastRet += es.length; |
785 |
|
} |
786 |
|
} |
787 |
|
} |
800 |
|
* @since 1.8 |
801 |
|
*/ |
802 |
|
public Spliterator<E> spliterator() { |
803 |
< |
return new ArrayDequeSpliterator(); |
803 |
> |
return new DeqSpliterator(); |
804 |
|
} |
805 |
|
|
806 |
< |
final class ArrayDequeSpliterator implements Spliterator<E> { |
807 |
< |
private int cursor; |
808 |
< |
private int remaining; // -1 until late-binding first use |
806 |
> |
final class DeqSpliterator implements Spliterator<E> { |
807 |
> |
private int fence; // -1 until first use |
808 |
> |
private int cursor; // current index, modified on traverse/split |
809 |
|
|
810 |
|
/** Constructs late-binding spliterator over all elements. */ |
811 |
< |
ArrayDequeSpliterator() { |
812 |
< |
this.remaining = -1; |
811 |
> |
DeqSpliterator() { |
812 |
> |
this.fence = -1; |
813 |
|
} |
814 |
|
|
815 |
< |
/** Constructs spliterator over the given slice. */ |
816 |
< |
ArrayDequeSpliterator(int cursor, int count) { |
817 |
< |
this.cursor = cursor; |
818 |
< |
this.remaining = count; |
815 |
> |
/** Constructs spliterator over the given range. */ |
816 |
> |
DeqSpliterator(int origin, int fence) { |
817 |
> |
this.cursor = origin; |
818 |
> |
this.fence = fence; |
819 |
|
} |
820 |
|
|
821 |
< |
/** Ensures late-binding initialization; then returns remaining. */ |
822 |
< |
private int remaining() { |
823 |
< |
if (remaining < 0) { |
821 |
> |
/** Ensures late-binding initialization; then returns fence. */ |
822 |
> |
private int getFence() { // force initialization |
823 |
> |
int t; |
824 |
> |
if ((t = fence) < 0) { |
825 |
> |
t = fence = tail; |
826 |
|
cursor = head; |
814 |
– |
remaining = size; |
827 |
|
} |
828 |
< |
return remaining; |
828 |
> |
return t; |
829 |
|
} |
830 |
|
|
831 |
< |
public ArrayDequeSpliterator trySplit() { |
832 |
< |
final int mid; |
833 |
< |
if ((mid = remaining() >> 1) > 0) { |
834 |
< |
int oldCursor = cursor; |
835 |
< |
cursor = add(cursor, mid, elements.length); |
836 |
< |
remaining -= mid; |
825 |
< |
return new ArrayDequeSpliterator(oldCursor, mid); |
826 |
< |
} |
827 |
< |
return null; |
831 |
> |
public DeqSpliterator trySplit() { |
832 |
> |
final Object[] es = elements; |
833 |
> |
final int i, n; |
834 |
> |
return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0) |
835 |
> |
? null |
836 |
> |
: new DeqSpliterator(i, cursor = add(i, n, es.length)); |
837 |
|
} |
838 |
|
|
839 |
|
public void forEachRemaining(Consumer<? super E> action) { |
840 |
< |
Objects.requireNonNull(action); |
841 |
< |
final int k = remaining(); // side effect! |
842 |
< |
remaining = 0; |
843 |
< |
ArrayDeque.forEachRemaining(action, elements, cursor, k); |
840 |
> |
if (action == null) |
841 |
> |
throw new NullPointerException(); |
842 |
> |
final int end = getFence(), cursor = this.cursor; |
843 |
> |
final Object[] es = elements; |
844 |
> |
if (cursor != end) { |
845 |
> |
this.cursor = end; |
846 |
> |
// null check at both ends of range is sufficient |
847 |
> |
if (es[cursor] == null || es[dec(end, es.length)] == null) |
848 |
> |
throw new ConcurrentModificationException(); |
849 |
> |
for (int i = cursor, to = (i <= end) ? end : es.length; |
850 |
> |
; i = 0, to = end) { |
851 |
> |
for (; i < to; i++) |
852 |
> |
action.accept(elementAt(es, i)); |
853 |
> |
if (to == end) break; |
854 |
> |
} |
855 |
> |
} |
856 |
|
} |
857 |
|
|
858 |
|
public boolean tryAdvance(Consumer<? super E> action) { |
859 |
< |
Objects.requireNonNull(action); |
860 |
< |
final int k; |
861 |
< |
if ((k = remaining()) <= 0) |
859 |
> |
if (action == null) |
860 |
> |
throw new NullPointerException(); |
861 |
> |
int t, i; |
862 |
> |
if ((t = fence) < 0) t = getFence(); |
863 |
> |
if (t == (i = cursor)) |
864 |
|
return false; |
865 |
< |
action.accept(nonNullElementAt(elements, cursor)); |
866 |
< |
if (++cursor >= elements.length) cursor = 0; |
867 |
< |
remaining = k - 1; |
865 |
> |
final Object[] es; |
866 |
> |
action.accept(nonNullElementAt(es = elements, i)); |
867 |
> |
cursor = inc(i, es.length); |
868 |
|
return true; |
869 |
|
} |
870 |
|
|
871 |
|
public long estimateSize() { |
872 |
< |
return remaining(); |
872 |
> |
return sub(getFence(), cursor, elements.length); |
873 |
|
} |
874 |
|
|
875 |
|
public int characteristics() { |
880 |
|
} |
881 |
|
} |
882 |
|
|
860 |
– |
@SuppressWarnings("unchecked") |
883 |
|
public void forEach(Consumer<? super E> action) { |
884 |
|
Objects.requireNonNull(action); |
885 |
|
final Object[] es = elements; |
886 |
< |
int i, end, to, todo; |
887 |
< |
todo = (end = (i = head) + size) |
866 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
867 |
< |
for (;; to = todo, todo = 0, i = 0) { |
886 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
887 |
> |
; i = 0, to = end) { |
888 |
|
for (; i < to; i++) |
889 |
< |
action.accept((E) es[i]); |
890 |
< |
if (todo == 0) break; |
889 |
> |
action.accept(elementAt(es, i)); |
890 |
> |
if (to == end) { |
891 |
> |
if (end != tail) throw new ConcurrentModificationException(); |
892 |
> |
break; |
893 |
> |
} |
894 |
|
} |
895 |
|
// checkInvariants(); |
896 |
|
} |
897 |
|
|
898 |
|
/** |
876 |
– |
* Calls action on remaining elements, starting at index i and |
877 |
– |
* traversing in ascending order. A variant of forEach that also |
878 |
– |
* checks for concurrent modification, for use in iterators. |
879 |
– |
*/ |
880 |
– |
static <E> void forEachRemaining( |
881 |
– |
Consumer<? super E> action, Object[] es, int i, int remaining) { |
882 |
– |
int end, to, todo; |
883 |
– |
todo = (end = i + remaining) |
884 |
– |
- (to = (es.length - end >= 0) ? end : es.length); |
885 |
– |
for (;; to = todo, todo = 0, i = 0) { |
886 |
– |
for (; i < to; i++) |
887 |
– |
action.accept(nonNullElementAt(es, i)); |
888 |
– |
if (todo == 0) break; |
889 |
– |
} |
890 |
– |
} |
891 |
– |
|
892 |
– |
/** |
899 |
|
* Replaces each element of this deque with the result of applying the |
900 |
|
* operator to that element, as specified by {@link List#replaceAll}. |
901 |
|
* |
902 |
|
* @param operator the operator to apply to each element |
903 |
|
* @since TBD |
904 |
|
*/ |
899 |
– |
@SuppressWarnings("unchecked") |
905 |
|
/* public */ void replaceAll(UnaryOperator<E> operator) { |
906 |
|
Objects.requireNonNull(operator); |
907 |
|
final Object[] es = elements; |
908 |
< |
int i, end, to, todo; |
909 |
< |
todo = (end = (i = head) + size) |
905 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
906 |
< |
for (;; to = todo, todo = 0, i = 0) { |
908 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
909 |
> |
; i = 0, to = end) { |
910 |
|
for (; i < to; i++) |
911 |
< |
es[i] = operator.apply((E) es[i]); |
912 |
< |
if (todo == 0) break; |
911 |
> |
es[i] = operator.apply(elementAt(es, i)); |
912 |
> |
if (to == end) { |
913 |
> |
if (end != tail) throw new ConcurrentModificationException(); |
914 |
> |
break; |
915 |
> |
} |
916 |
|
} |
917 |
|
// checkInvariants(); |
918 |
|
} |
942 |
|
} |
943 |
|
|
944 |
|
/** Implementation of bulk remove methods. */ |
939 |
– |
@SuppressWarnings("unchecked") |
945 |
|
private boolean bulkRemove(Predicate<? super E> filter) { |
946 |
|
// checkInvariants(); |
947 |
|
final Object[] es = elements; |
948 |
< |
int i, end, to, todo; |
949 |
< |
todo = (end = (i = head) + size) |
950 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
946 |
< |
// Optimize for initial run of non-removed elements |
947 |
< |
findFirstRemoved: |
948 |
< |
for (;; to = todo, todo = 0, i = 0) { |
948 |
> |
// Optimize for initial run of survivors |
949 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
950 |
> |
; i = 0, to = end) { |
951 |
|
for (; i < to; i++) |
952 |
< |
if (filter.test((E) es[i])) |
953 |
< |
break findFirstRemoved; |
954 |
< |
if (todo == 0) return false; |
952 |
> |
if (filter.test(elementAt(es, i))) |
953 |
> |
return bulkRemoveModified(filter, i, to); |
954 |
> |
if (to == end) { |
955 |
> |
if (end != tail) throw new ConcurrentModificationException(); |
956 |
> |
break; |
957 |
> |
} |
958 |
|
} |
959 |
< |
bulkRemoveModified(filter, i, to, todo); |
955 |
< |
return true; |
959 |
> |
return false; |
960 |
|
} |
961 |
|
|
962 |
|
/** |
963 |
|
* Helper for bulkRemove, in case of at least one deletion. |
964 |
|
* @param i valid index of first element to be deleted |
965 |
|
*/ |
966 |
< |
@SuppressWarnings("unchecked") |
967 |
< |
private void bulkRemoveModified( |
964 |
< |
Predicate<? super E> filter, int i, int to, int todo) { |
966 |
> |
private boolean bulkRemoveModified( |
967 |
> |
Predicate<? super E> filter, int i, int to) { |
968 |
|
final Object[] es = elements; |
969 |
|
final int capacity = es.length; |
970 |
< |
// a two-finger algorithm, with hare i and tortoise j |
970 |
> |
// a two-finger algorithm, with hare i reading, tortoise j writing |
971 |
|
int j = i++; |
972 |
+ |
final int end = tail; |
973 |
|
try { |
974 |
< |
for (;;) { |
974 |
> |
for (;; j = 0) { // j rejoins i on second leg |
975 |
|
E e; |
976 |
|
// In this loop, i and j are on the same leg, with i > j |
977 |
|
for (; i < to; i++) |
978 |
< |
if (!filter.test(e = (E) es[i])) |
978 |
> |
if (!filter.test(e = elementAt(es, i))) |
979 |
|
es[j++] = e; |
980 |
< |
if (todo == 0) break; |
980 |
> |
if (to == end) break; |
981 |
|
// In this loop, j is on the first leg, i on the second |
982 |
< |
for (to = todo, todo = 0, i = 0; i < to && j < capacity; i++) |
983 |
< |
if (!filter.test(e = (E) es[i])) |
982 |
> |
for (i = 0, to = end; i < to && j < capacity; i++) |
983 |
> |
if (!filter.test(e = elementAt(es, i))) |
984 |
|
es[j++] = e; |
985 |
< |
if (i >= to) break; |
986 |
< |
j = 0; // j rejoins i on second leg |
985 |
> |
if (i >= to) { |
986 |
> |
if (j == capacity) j = 0; // "corner" case |
987 |
> |
break; |
988 |
> |
} |
989 |
|
} |
990 |
< |
bulkRemoveClear(es, j, i); |
985 |
< |
// checkInvariants(); |
990 |
> |
return true; |
991 |
|
} catch (Throwable ex) { |
992 |
|
// copy remaining elements |
993 |
< |
for (int remaining = (to - i) + todo; --remaining >= 0;) { |
993 |
> |
for (; i != end; i = inc(i, capacity), j = inc(j, capacity)) |
994 |
|
es[j] = es[i]; |
990 |
– |
if (++i >= capacity) i = 0; |
991 |
– |
if (++j >= capacity) j = 0; |
992 |
– |
} |
993 |
– |
bulkRemoveClear(es, j, i); |
994 |
– |
// checkInvariants(); |
995 |
|
throw ex; |
996 |
+ |
} finally { |
997 |
+ |
if (end != tail) throw new ConcurrentModificationException(); |
998 |
+ |
circularClear(es, tail = j, end); |
999 |
+ |
// checkInvariants(); |
1000 |
|
} |
1001 |
|
} |
1002 |
|
|
1003 |
|
/** |
1000 |
– |
* Nulls out all elements from index j upto index i. |
1001 |
– |
*/ |
1002 |
– |
private void bulkRemoveClear(Object[] es, int j, int i) { |
1003 |
– |
int deleted; |
1004 |
– |
if ((deleted = i - j) <= 0) deleted += es.length; |
1005 |
– |
size -= deleted; |
1006 |
– |
circularClear(es, j, deleted); |
1007 |
– |
} |
1008 |
– |
|
1009 |
– |
/** |
1004 |
|
* Returns {@code true} if this deque contains the specified element. |
1005 |
|
* More formally, returns {@code true} if and only if this deque contains |
1006 |
|
* at least one element {@code e} such that {@code o.equals(e)}. |
1011 |
|
public boolean contains(Object o) { |
1012 |
|
if (o != null) { |
1013 |
|
final Object[] es = elements; |
1014 |
< |
int i, end, to, todo; |
1015 |
< |
todo = (end = (i = head) + size) |
1022 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
1023 |
< |
for (;; to = todo, todo = 0, i = 0) { |
1014 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
1015 |
> |
; i = 0, to = end) { |
1016 |
|
for (; i < to; i++) |
1017 |
|
if (o.equals(es[i])) |
1018 |
|
return true; |
1019 |
< |
if (todo == 0) break; |
1019 |
> |
if (to == end) break; |
1020 |
|
} |
1021 |
|
} |
1022 |
|
return false; |
1044 |
|
* The deque will be empty after this call returns. |
1045 |
|
*/ |
1046 |
|
public void clear() { |
1047 |
< |
circularClear(elements, head, size); |
1048 |
< |
size = head = 0; |
1047 |
> |
circularClear(elements, head, tail); |
1048 |
> |
head = tail = 0; |
1049 |
|
// checkInvariants(); |
1050 |
|
} |
1051 |
|
|
1052 |
|
/** |
1053 |
< |
* Nulls out count elements, starting at array index from. |
1062 |
< |
* Special case (from == es.length) is treated the same as (from == 0). |
1053 |
> |
* Nulls out slots starting at array index i, upto index end. |
1054 |
|
*/ |
1055 |
< |
private static void circularClear(Object[] es, int from, int count) { |
1056 |
< |
int end, to, todo; |
1057 |
< |
todo = (end = from + count) |
1058 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
1059 |
< |
for (;; to = todo, todo = 0, from = 0) { |
1069 |
< |
Arrays.fill(es, from, to, null); |
1070 |
< |
if (todo == 0) break; |
1055 |
> |
private static void circularClear(Object[] es, int i, int end) { |
1056 |
> |
for (int to = (i <= end) ? end : es.length; |
1057 |
> |
; i = 0, to = end) { |
1058 |
> |
Arrays.fill(es, i, to, null); |
1059 |
> |
if (to == end) break; |
1060 |
|
} |
1061 |
|
} |
1062 |
|
|
1080 |
|
private <T> T[] toArray(Class<T[]> klazz) { |
1081 |
|
final Object[] es = elements; |
1082 |
|
final T[] a; |
1083 |
< |
final int head, len, end, todo; |
1084 |
< |
todo = size - (len = Math.min(size, es.length - (head = this.head))); |
1083 |
> |
final int size = size(), head = this.head, end; |
1084 |
> |
final int len = Math.min(size, es.length - head); |
1085 |
|
if ((end = head + size) >= 0) { |
1086 |
|
a = Arrays.copyOfRange(es, head, end, klazz); |
1087 |
|
} else { |
1089 |
|
a = Arrays.copyOfRange(es, 0, size, klazz); |
1090 |
|
System.arraycopy(es, head, a, 0, len); |
1091 |
|
} |
1092 |
< |
if (todo > 0) |
1093 |
< |
System.arraycopy(es, 0, a, len, todo); |
1092 |
> |
if (tail < head) |
1093 |
> |
System.arraycopy(es, 0, a, len, tail); |
1094 |
|
return a; |
1095 |
|
} |
1096 |
|
|
1133 |
|
@SuppressWarnings("unchecked") |
1134 |
|
public <T> T[] toArray(T[] a) { |
1135 |
|
final int size; |
1136 |
< |
if ((size = this.size) > a.length) |
1136 |
> |
if ((size = size()) > a.length) |
1137 |
|
return toArray((Class<T[]>) a.getClass()); |
1138 |
|
final Object[] es = elements; |
1139 |
< |
int i, j, len, todo; |
1140 |
< |
todo = size - (len = Math.min(size, es.length - (i = head))); |
1152 |
< |
for (j = 0;; j += len, len = todo, todo = 0, i = 0) { |
1139 |
> |
for (int i = head, j = 0, len = Math.min(size, es.length - i); |
1140 |
> |
; i = 0, len = tail) { |
1141 |
|
System.arraycopy(es, i, a, j, len); |
1142 |
< |
if (todo == 0) break; |
1142 |
> |
if ((j += len) == size) break; |
1143 |
|
} |
1144 |
|
if (size < a.length) |
1145 |
|
a[size] = null; |
1180 |
|
s.defaultWriteObject(); |
1181 |
|
|
1182 |
|
// Write out size |
1183 |
< |
s.writeInt(size); |
1183 |
> |
s.writeInt(size()); |
1184 |
|
|
1185 |
|
// Write out elements in order. |
1186 |
|
final Object[] es = elements; |
1187 |
< |
int i, end, to, todo; |
1188 |
< |
todo = (end = (i = head) + size) |
1201 |
< |
- (to = (es.length - end >= 0) ? end : es.length); |
1202 |
< |
for (;; to = todo, todo = 0, i = 0) { |
1187 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
1188 |
> |
; i = 0, to = end) { |
1189 |
|
for (; i < to; i++) |
1190 |
|
s.writeObject(es[i]); |
1191 |
< |
if (todo == 0) break; |
1191 |
> |
if (to == end) break; |
1192 |
|
} |
1193 |
|
} |
1194 |
|
|
1204 |
|
s.defaultReadObject(); |
1205 |
|
|
1206 |
|
// Read in size and allocate array |
1207 |
< |
elements = new Object[size = s.readInt()]; |
1207 |
> |
int size = s.readInt(); |
1208 |
> |
elements = new Object[size + 1]; |
1209 |
> |
this.tail = size; |
1210 |
|
|
1211 |
|
// Read in all elements in the proper order. |
1212 |
|
for (int i = 0; i < size; i++) |
1217 |
|
void checkInvariants() { |
1218 |
|
try { |
1219 |
|
int capacity = elements.length; |
1220 |
< |
// assert size >= 0 && size <= capacity; |
1221 |
< |
// assert head >= 0; |
1222 |
< |
// assert capacity == 0 || head < capacity; |
1223 |
< |
// assert size == 0 || elements[head] != null; |
1224 |
< |
// assert size == 0 || elements[tail()] != null; |
1225 |
< |
// assert size == capacity || elements[dec(head, capacity)] == null; |
1226 |
< |
// assert size == capacity || elements[inc(tail(), capacity)] == null; |
1220 |
> |
// assert head >= 0 && head < capacity; |
1221 |
> |
// assert tail >= 0 && tail < capacity; |
1222 |
> |
// assert capacity > 0; |
1223 |
> |
// assert size() < capacity; |
1224 |
> |
// assert head == tail || elements[head] != null; |
1225 |
> |
// assert elements[tail] == null; |
1226 |
> |
// assert head == tail || elements[dec(tail, capacity)] != null; |
1227 |
|
} catch (Throwable t) { |
1228 |
< |
System.err.printf("head=%d size=%d capacity=%d%n", |
1229 |
< |
head, size, elements.length); |
1228 |
> |
System.err.printf("head=%d tail=%d capacity=%d%n", |
1229 |
> |
head, tail, elements.length); |
1230 |
|
System.err.printf("elements=%s%n", |
1231 |
|
Arrays.toString(elements)); |
1232 |
|
throw t; |