| 538 |
|
* order that elements would be dequeued (via successive calls to |
| 539 |
|
* {@link #remove} or popped (via successive calls to {@link #pop}). |
| 540 |
|
* |
| 541 |
< |
* @return an <tt>Iterator</tt> over the elements in this deque |
| 541 |
> |
* @return an iterator over the elements in this deque |
| 542 |
|
*/ |
| 543 |
|
public Iterator<E> iterator() { |
| 544 |
|
return new DeqIterator(); |
| 545 |
|
} |
| 546 |
|
|
| 547 |
+ |
public Iterator<E> descendingIterator() { |
| 548 |
+ |
return new DescendingIterator(); |
| 549 |
+ |
} |
| 550 |
+ |
|
| 551 |
|
private class DeqIterator implements Iterator<E> { |
| 552 |
|
/** |
| 553 |
|
* Index of element to be returned by subsequent call to next. |
| 586 |
|
public void remove() { |
| 587 |
|
if (lastRet < 0) |
| 588 |
|
throw new IllegalStateException(); |
| 589 |
< |
if (delete(lastRet)) |
| 590 |
< |
cursor--; |
| 589 |
> |
if (delete(lastRet)) // if left-shifted, undo increment in next() |
| 590 |
> |
cursor = (cursor - 1) & (elements.length - 1); |
| 591 |
|
lastRet = -1; |
| 592 |
|
fence = tail; |
| 593 |
|
} |
| 594 |
|
} |
| 595 |
|
|
| 596 |
+ |
|
| 597 |
+ |
private class DescendingIterator implements Iterator<E> { |
| 598 |
+ |
/* |
| 599 |
+ |
* This class is nearly a mirror-image of DeqIterator, using |
| 600 |
+ |
* (tail-1) instead of head for initial cursor, (head-1) |
| 601 |
+ |
* instead of tail for fence, and elements.length instead of -1 |
| 602 |
+ |
* for sentinel. It shares the same structure, but not many |
| 603 |
+ |
* actual lines of code. |
| 604 |
+ |
*/ |
| 605 |
+ |
private int cursor = (tail - 1) & (elements.length - 1); |
| 606 |
+ |
private int fence = (head - 1) & (elements.length - 1); |
| 607 |
+ |
private int lastRet = elements.length; |
| 608 |
+ |
|
| 609 |
+ |
public boolean hasNext() { |
| 610 |
+ |
return cursor != fence; |
| 611 |
+ |
} |
| 612 |
+ |
|
| 613 |
+ |
public E next() { |
| 614 |
+ |
E result; |
| 615 |
+ |
if (cursor == fence) |
| 616 |
+ |
throw new NoSuchElementException(); |
| 617 |
+ |
if (((head - 1) & (elements.length - 1)) != fence || |
| 618 |
+ |
(result = elements[cursor]) == null) |
| 619 |
+ |
throw new ConcurrentModificationException(); |
| 620 |
+ |
lastRet = cursor; |
| 621 |
+ |
cursor = (cursor - 1) & (elements.length - 1); |
| 622 |
+ |
return result; |
| 623 |
+ |
} |
| 624 |
+ |
|
| 625 |
+ |
public void remove() { |
| 626 |
+ |
if (lastRet >= elements.length) |
| 627 |
+ |
throw new IllegalStateException(); |
| 628 |
+ |
if (!delete(lastRet)) |
| 629 |
+ |
cursor = (cursor + 1) & (elements.length - 1); |
| 630 |
+ |
lastRet = elements.length; |
| 631 |
+ |
fence = (head - 1) & (elements.length - 1); |
| 632 |
+ |
} |
| 633 |
+ |
} |
| 634 |
+ |
|
| 635 |
|
/** |
| 636 |
|
* Returns <tt>true</tt> if this deque contains the specified element. |
| 637 |
|
* More formally, returns <tt>true</tt> if and only if this deque contains |
| 790 |
|
s.defaultWriteObject(); |
| 791 |
|
|
| 792 |
|
// Write out size |
| 793 |
< |
int size = size(); |
| 751 |
< |
s.writeInt(size); |
| 793 |
> |
s.writeInt(size()); |
| 794 |
|
|
| 795 |
|
// Write out elements in order. |
| 754 |
– |
int i = head; |
| 796 |
|
int mask = elements.length - 1; |
| 797 |
< |
for (int j = 0; j < size; j++) { |
| 797 |
> |
for (int i = head; i != tail; i = (i + 1) & mask) |
| 798 |
|
s.writeObject(elements[i]); |
| 758 |
– |
i = (i + 1) & mask; |
| 759 |
– |
} |
| 799 |
|
} |
| 800 |
|
|
| 801 |
|
/** |
