133 |
|
} |
134 |
|
|
135 |
|
/** |
136 |
– |
* Copies the elements from our element array into the specified array, |
137 |
– |
* in order (from first to last element in the deque). It is assumed |
138 |
– |
* that the array is large enough to hold all elements in the deque. |
139 |
– |
* |
140 |
– |
* @return its argument |
141 |
– |
*/ |
142 |
– |
private <T> T[] copyElements(T[] a) { |
143 |
– |
if (head < tail) { |
144 |
– |
System.arraycopy(elements, head, a, 0, size()); |
145 |
– |
} else if (head > tail) { |
146 |
– |
int headPortionLen = elements.length - head; |
147 |
– |
System.arraycopy(elements, head, a, 0, headPortionLen); |
148 |
– |
System.arraycopy(elements, 0, a, headPortionLen, tail); |
149 |
– |
} |
150 |
– |
return a; |
151 |
– |
} |
152 |
– |
|
153 |
– |
/** |
136 |
|
* Constructs an empty array deque with an initial capacity |
137 |
|
* sufficient to hold 16 elements. |
138 |
|
*/ |
488 |
|
* @return true if elements moved backwards |
489 |
|
*/ |
490 |
|
private boolean delete(int i) { |
491 |
< |
checkInvariants(); |
491 |
> |
// checkInvariants(); |
492 |
|
final Object[] elements = this.elements; |
493 |
|
final int mask = elements.length - 1; |
494 |
|
final int h = head; |
609 |
|
} |
610 |
|
} |
611 |
|
|
612 |
+ |
/** |
613 |
+ |
* This class is nearly a mirror-image of DeqIterator, using tail |
614 |
+ |
* instead of head for initial cursor, and head instead of tail |
615 |
+ |
* for fence. |
616 |
+ |
*/ |
617 |
|
private class DescendingIterator implements Iterator<E> { |
631 |
– |
/* |
632 |
– |
* This class is nearly a mirror-image of DeqIterator, using |
633 |
– |
* tail instead of head for initial cursor, and head instead of |
634 |
– |
* tail for fence. |
635 |
– |
*/ |
618 |
|
private int cursor = tail; |
619 |
|
private int fence = head; |
620 |
|
private int lastRet = -1; |
717 |
|
* @return an array containing all of the elements in this deque |
718 |
|
*/ |
719 |
|
public Object[] toArray() { |
720 |
< |
return copyElements(new Object[size()]); |
720 |
> |
final int head = this.head; |
721 |
> |
final int tail = this.tail; |
722 |
> |
boolean wrap = (tail < head); |
723 |
> |
int end = wrap ? tail + elements.length : tail; |
724 |
> |
Object[] a = Arrays.copyOfRange(elements, head, end); |
725 |
> |
if (wrap) |
726 |
> |
System.arraycopy(elements, 0, a, elements.length - head, tail); |
727 |
> |
return a; |
728 |
|
} |
729 |
|
|
730 |
|
/** |
765 |
|
*/ |
766 |
|
@SuppressWarnings("unchecked") |
767 |
|
public <T> T[] toArray(T[] a) { |
768 |
< |
int size = size(); |
769 |
< |
if (a.length < size) |
770 |
< |
a = (T[])java.lang.reflect.Array.newInstance( |
771 |
< |
a.getClass().getComponentType(), size); |
772 |
< |
copyElements(a); |
773 |
< |
if (a.length > size) |
774 |
< |
a[size] = null; |
768 |
> |
final int head = this.head; |
769 |
> |
final int tail = this.tail; |
770 |
> |
boolean wrap = (tail < head); |
771 |
> |
int size = (tail - head) + (wrap ? elements.length : 0); |
772 |
> |
int firstLeg = size - (wrap ? tail : 0); |
773 |
> |
int len = a.length; |
774 |
> |
if (size > len) { |
775 |
> |
a = (T[]) Arrays.copyOfRange(elements, head, head + size, |
776 |
> |
a.getClass()); |
777 |
> |
} else { |
778 |
> |
System.arraycopy(elements, head, a, 0, firstLeg); |
779 |
> |
if (size < len) |
780 |
> |
a[size] = null; |
781 |
> |
} |
782 |
> |
if (wrap) |
783 |
> |
System.arraycopy(elements, 0, a, firstLeg, tail); |
784 |
|
return a; |
785 |
|
} |
786 |
|
|