50 |
|
* Iterator} interfaces. |
51 |
|
* |
52 |
|
* <p>This class is a member of the |
53 |
< |
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
53 |
> |
* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework"> |
54 |
|
* Java Collections Framework</a>. |
55 |
|
* |
56 |
|
* @author Josh Bloch and Doug Lea |
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 |
113 |
< |
// checkInvariants(); |
96 |
< |
int oldCapacity = elements.length; |
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) { |
120 |
> |
final Object[] es = elements = Arrays.copyOf(elements, newCapacity); |
121 |
> |
// Exceptionally, here tail == head needs to be disambiguated |
122 |
> |
if (tail < head || (tail == head && es[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, |
125 |
> |
System.arraycopy(es, head, |
126 |
> |
es, head + newSpace, |
127 |
|
oldCapacity - head); |
128 |
< |
Arrays.fill(elements, head, head + newSpace, null); |
129 |
< |
head += newSpace; |
128 |
> |
for (int i = head, to = (head += newSpace); i < to; i++) |
129 |
> |
es[i] = null; |
130 |
|
} |
131 |
|
// checkInvariants(); |
132 |
|
} |
133 |
|
|
134 |
|
/** Capacity calculation for edge conditions, especially overflow. */ |
135 |
|
private int newCapacity(int needed, int jump) { |
136 |
< |
int oldCapacity = elements.length; |
119 |
< |
int minCapacity; |
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"); |
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[] elements = c.toArray(); |
211 |
< |
// defend against c.toArray (incorrectly) not returning Object[] |
189 |
< |
// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652) |
190 |
< |
if (elements.getClass() != Object[].class) |
191 |
< |
elements = Arrays.copyOf(elements, size, Object[].class); |
192 |
< |
for (Object obj : elements) |
193 |
< |
Objects.requireNonNull(obj); |
194 |
< |
size = elements.length; |
195 |
< |
this.elements = elements; |
210 |
> |
this(c.size()); |
211 |
> |
addAll(c); |
212 |
|
} |
213 |
|
|
214 |
|
/** |
215 |
< |
* Increments i, mod modulus. |
215 |
> |
* Circularly 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; |
219 |
> |
if (++i >= modulus) i = 0; |
220 |
|
return i; |
221 |
|
} |
222 |
|
|
223 |
|
/** |
224 |
< |
* Decrements i, mod modulus. |
224 |
> |
* Circularly 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; |
228 |
> |
if (--i < 0) i = modulus - 1; |
229 |
|
return i; |
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 inc(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 disambiguated 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 |
< |
final 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 |
|
/** |
265 |
|
* This check doesn't catch all possible comodifications, |
266 |
|
* but does catch ones that corrupt traversal. |
267 |
|
*/ |
268 |
< |
E checkedElementAt(Object[] elements, int i) { |
269 |
< |
@SuppressWarnings("unchecked") E e = (E) elements[i]; |
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; |
283 |
|
* @throws NullPointerException if the specified element is null |
284 |
|
*/ |
285 |
|
public void addFirst(E e) { |
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); |
292 |
|
// checkInvariants(); |
265 |
– |
Objects.requireNonNull(e); |
266 |
– |
final Object[] elements; |
267 |
– |
final int capacity, s; |
268 |
– |
if ((s = size) == (capacity = (elements = this.elements).length)) |
269 |
– |
addFirstSlowPath(e); |
270 |
– |
else |
271 |
– |
elements[head = dec(head, capacity)] = e; |
272 |
– |
size = s + 1; |
273 |
– |
// checkInvariants(); |
274 |
– |
} |
275 |
– |
|
276 |
– |
private void addFirstSlowPath(E e) { |
277 |
– |
grow(1); |
278 |
– |
final Object[] elements = this.elements; |
279 |
– |
elements[head = dec(head, elements.length)] = e; |
293 |
|
} |
294 |
|
|
295 |
|
/** |
301 |
|
* @throws NullPointerException if the specified element is null |
302 |
|
*/ |
303 |
|
public void addLast(E e) { |
304 |
< |
// checkInvariants(); |
305 |
< |
Objects.requireNonNull(e); |
306 |
< |
final Object[] elements; |
307 |
< |
final int capacity, s; |
308 |
< |
if ((s = size) == (capacity = (elements = this.elements).length)) |
309 |
< |
addLastSlowPath(e); |
297 |
< |
else |
298 |
< |
elements[add(head, s, capacity)] = e; |
299 |
< |
size = s + 1; |
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); |
310 |
|
// checkInvariants(); |
311 |
|
} |
312 |
|
|
303 |
– |
private void addLastSlowPath(E e) { |
304 |
– |
grow(1); |
305 |
– |
final Object[] elements = this.elements; |
306 |
– |
elements[add(head, size, elements.length)] = e; |
307 |
– |
} |
308 |
– |
|
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 |
313 |
< |
* iterator. |
316 |
> |
* in the order that they are returned by the collection's iterator. |
317 |
|
* |
318 |
|
* @param c the elements to be inserted into this deque |
319 |
|
* @return {@code true} if this deque changed as a result of the call |
320 |
|
* @throws NullPointerException if the specified collection or any |
321 |
|
* of its elements are null |
322 |
|
*/ |
320 |
– |
@Override |
323 |
|
public boolean addAll(Collection<? extends E> c) { |
324 |
+ |
final int s, needed; |
325 |
+ |
if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0) |
326 |
+ |
grow(needed); |
327 |
+ |
c.forEach(this::addLast); |
328 |
|
// checkInvariants(); |
329 |
< |
Object[] a, elements; |
324 |
< |
int newcomers, capacity, s = size; |
325 |
< |
if ((newcomers = (a = c.toArray()).length) == 0) |
326 |
< |
return false; |
327 |
< |
while ((capacity = (elements = this.elements).length) - s < newcomers) |
328 |
< |
grow(newcomers - (capacity - s)); |
329 |
< |
int i = add(head, s, capacity); |
330 |
< |
for (Object x : a) { |
331 |
< |
Objects.requireNonNull(x); |
332 |
< |
elements[i] = x; |
333 |
< |
i = inc(i, capacity); |
334 |
< |
size++; |
335 |
< |
} |
336 |
< |
return true; |
329 |
> |
return size() > s; |
330 |
|
} |
331 |
|
|
332 |
|
/** |
357 |
|
* @throws NoSuchElementException {@inheritDoc} |
358 |
|
*/ |
359 |
|
public E removeFirst() { |
367 |
– |
// checkInvariants(); |
360 |
|
E e = pollFirst(); |
361 |
|
if (e == null) |
362 |
|
throw new NoSuchElementException(); |
363 |
+ |
// checkInvariants(); |
364 |
|
return e; |
365 |
|
} |
366 |
|
|
368 |
|
* @throws NoSuchElementException {@inheritDoc} |
369 |
|
*/ |
370 |
|
public E removeLast() { |
378 |
– |
// checkInvariants(); |
371 |
|
E e = pollLast(); |
372 |
|
if (e == null) |
373 |
|
throw new NoSuchElementException(); |
374 |
+ |
// checkInvariants(); |
375 |
|
return e; |
376 |
|
} |
377 |
|
|
378 |
|
public E pollFirst() { |
379 |
+ |
final Object[] es; |
380 |
+ |
final int h; |
381 |
+ |
E e = elementAt(es = elements, h = head); |
382 |
+ |
if (e != null) { |
383 |
+ |
es[h] = null; |
384 |
+ |
head = inc(h, es.length); |
385 |
+ |
} |
386 |
|
// checkInvariants(); |
387 |
– |
final int s, h; |
388 |
– |
if ((s = size) == 0) |
389 |
– |
return null; |
390 |
– |
final Object[] elements = this.elements; |
391 |
– |
@SuppressWarnings("unchecked") E e = (E) elements[h = head]; |
392 |
– |
elements[h] = null; |
393 |
– |
head = inc(h, elements.length); |
394 |
– |
size = s - 1; |
387 |
|
return e; |
388 |
|
} |
389 |
|
|
390 |
|
public E pollLast() { |
391 |
+ |
final Object[] es; |
392 |
+ |
final int t; |
393 |
+ |
E e = elementAt(es = elements, t = dec(tail, es.length)); |
394 |
+ |
if (e != null) |
395 |
+ |
es[tail = t] = null; |
396 |
|
// checkInvariants(); |
400 |
– |
final int s, tail; |
401 |
– |
if ((s = size) == 0) |
402 |
– |
return null; |
403 |
– |
final Object[] elements = this.elements; |
404 |
– |
@SuppressWarnings("unchecked") |
405 |
– |
E e = (E) elements[tail = add(head, s - 1, elements.length)]; |
406 |
– |
elements[tail] = null; |
407 |
– |
size = s - 1; |
397 |
|
return e; |
398 |
|
} |
399 |
|
|
401 |
|
* @throws NoSuchElementException {@inheritDoc} |
402 |
|
*/ |
403 |
|
public E getFirst() { |
404 |
+ |
E e = elementAt(elements, head); |
405 |
+ |
if (e == null) |
406 |
+ |
throw new NoSuchElementException(); |
407 |
|
// checkInvariants(); |
408 |
< |
if (size == 0) throw new NoSuchElementException(); |
417 |
< |
return elementAt(head); |
408 |
> |
return e; |
409 |
|
} |
410 |
|
|
411 |
|
/** |
412 |
|
* @throws NoSuchElementException {@inheritDoc} |
413 |
|
*/ |
414 |
|
public E getLast() { |
415 |
+ |
final Object[] es = elements; |
416 |
+ |
E e = elementAt(es, dec(tail, es.length)); |
417 |
+ |
if (e == null) |
418 |
+ |
throw new NoSuchElementException(); |
419 |
|
// checkInvariants(); |
420 |
< |
if (size == 0) throw new NoSuchElementException(); |
426 |
< |
return elementAt(tail()); |
420 |
> |
return e; |
421 |
|
} |
422 |
|
|
423 |
|
public E peekFirst() { |
424 |
|
// checkInvariants(); |
425 |
< |
return (size == 0) ? null : elementAt(head); |
425 |
> |
return elementAt(elements, head); |
426 |
|
} |
427 |
|
|
428 |
|
public E peekLast() { |
429 |
|
// checkInvariants(); |
430 |
< |
return (size == 0) ? null : elementAt(tail()); |
430 |
> |
final Object[] es; |
431 |
> |
return elementAt(es = elements, dec(tail, es.length)); |
432 |
|
} |
433 |
|
|
434 |
|
/** |
444 |
|
* @return {@code true} if the deque contained the specified element |
445 |
|
*/ |
446 |
|
public boolean removeFirstOccurrence(Object o) { |
452 |
– |
// checkInvariants(); |
447 |
|
if (o != null) { |
448 |
< |
final Object[] elements = this.elements; |
449 |
< |
final int capacity = elements.length; |
450 |
< |
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) { |
451 |
< |
if (o.equals(elements[i])) { |
452 |
< |
delete(i); |
453 |
< |
return true; |
454 |
< |
} |
448 |
> |
final Object[] es = elements; |
449 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
450 |
> |
; i = 0, to = end) { |
451 |
> |
for (; i < to; i++) |
452 |
> |
if (o.equals(es[i])) { |
453 |
> |
delete(i); |
454 |
> |
return true; |
455 |
> |
} |
456 |
> |
if (to == end) break; |
457 |
|
} |
458 |
|
} |
459 |
|
return false; |
473 |
|
*/ |
474 |
|
public boolean removeLastOccurrence(Object o) { |
475 |
|
if (o != null) { |
476 |
< |
final Object[] elements = this.elements; |
477 |
< |
final int capacity = elements.length; |
478 |
< |
for (int k = size, i = add(head, k - 1, capacity); |
479 |
< |
--k >= 0; i = dec(i, capacity)) { |
480 |
< |
if (o.equals(elements[i])) { |
481 |
< |
delete(i); |
482 |
< |
return true; |
483 |
< |
} |
476 |
> |
final Object[] es = elements; |
477 |
> |
for (int i = tail, end = head, to = (i >= end) ? end : 0; |
478 |
> |
; i = es.length, to = end) { |
479 |
> |
for (i--; i > to - 1; i--) |
480 |
> |
if (o.equals(es[i])) { |
481 |
> |
delete(i); |
482 |
> |
return true; |
483 |
> |
} |
484 |
> |
if (to == end) break; |
485 |
|
} |
486 |
|
} |
487 |
|
return false; |
519 |
|
/** |
520 |
|
* Retrieves and removes the head of the queue represented by this deque. |
521 |
|
* |
522 |
< |
* This method differs from {@link #poll poll} only in that it throws an |
523 |
< |
* exception if this deque is empty. |
522 |
> |
* This method differs from {@link #poll() poll()} only in that it |
523 |
> |
* throws an exception if this deque is empty. |
524 |
|
* |
525 |
|
* <p>This method is equivalent to {@link #removeFirst}. |
526 |
|
* |
609 |
|
* <p>This method is called delete rather than remove to emphasize |
610 |
|
* that its semantics differ from those of {@link List#remove(int)}. |
611 |
|
* |
612 |
< |
* @return true if elements moved backwards |
612 |
> |
* @return true if elements near tail moved backwards |
613 |
|
*/ |
614 |
|
boolean delete(int i) { |
615 |
|
// checkInvariants(); |
616 |
< |
final Object[] elements = this.elements; |
617 |
< |
final int capacity = elements.length; |
618 |
< |
final int h = head; |
619 |
< |
int front; // number of elements before to-be-deleted elt |
620 |
< |
if ((front = i - h) < 0) front += capacity; |
621 |
< |
final int back = size - front - 1; // number of elements after |
616 |
> |
final Object[] es = elements; |
617 |
> |
final int capacity = es.length; |
618 |
> |
final int h, t; |
619 |
> |
// number of elements before to-be-deleted elt |
620 |
> |
final int front = sub(i, h = head, capacity); |
621 |
> |
// number of elements after to-be-deleted elt |
622 |
> |
final int back = sub(t = tail, i, capacity) - 1; |
623 |
|
if (front < back) { |
624 |
|
// move front elements forwards |
625 |
|
if (h <= i) { |
626 |
< |
System.arraycopy(elements, h, elements, h + 1, front); |
626 |
> |
System.arraycopy(es, h, es, h + 1, front); |
627 |
|
} else { // Wrap around |
628 |
< |
System.arraycopy(elements, 0, elements, 1, i); |
629 |
< |
elements[0] = elements[capacity - 1]; |
630 |
< |
System.arraycopy(elements, h, elements, h + 1, front - (i + 1)); |
628 |
> |
System.arraycopy(es, 0, es, 1, i); |
629 |
> |
es[0] = es[capacity - 1]; |
630 |
> |
System.arraycopy(es, h, es, h + 1, front - (i + 1)); |
631 |
|
} |
632 |
< |
elements[h] = null; |
632 |
> |
es[h] = null; |
633 |
|
head = inc(h, capacity); |
636 |
– |
size--; |
634 |
|
// checkInvariants(); |
635 |
|
return false; |
636 |
|
} else { |
637 |
|
// move back elements backwards |
638 |
< |
int tail = tail(); |
638 |
> |
tail = dec(t, capacity); |
639 |
|
if (i <= tail) { |
640 |
< |
System.arraycopy(elements, i + 1, elements, i, back); |
640 |
> |
System.arraycopy(es, i + 1, es, i, back); |
641 |
|
} else { // Wrap around |
642 |
< |
int firstLeg = capacity - (i + 1); |
643 |
< |
System.arraycopy(elements, i + 1, elements, i, firstLeg); |
644 |
< |
elements[capacity - 1] = elements[0]; |
648 |
< |
System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1); |
642 |
> |
System.arraycopy(es, i + 1, es, i, capacity - (i + 1)); |
643 |
> |
es[capacity - 1] = es[0]; |
644 |
> |
System.arraycopy(es, 1, es, 0, t - 1); |
645 |
|
} |
646 |
< |
elements[tail] = null; |
651 |
< |
size--; |
646 |
> |
es[tail] = null; |
647 |
|
// checkInvariants(); |
648 |
|
return true; |
649 |
|
} |
657 |
|
* @return the number of elements in this deque |
658 |
|
*/ |
659 |
|
public int size() { |
660 |
< |
return size; |
660 |
> |
return sub(tail, head, elements.length); |
661 |
|
} |
662 |
|
|
663 |
|
/** |
666 |
|
* @return {@code true} if this deque contains no elements |
667 |
|
*/ |
668 |
|
public boolean isEmpty() { |
669 |
< |
return size == 0; |
669 |
> |
return head == tail; |
670 |
|
} |
671 |
|
|
672 |
|
/** |
690 |
|
int cursor; |
691 |
|
|
692 |
|
/** Number of elements yet to be returned. */ |
693 |
< |
int remaining = size; |
693 |
> |
int remaining = size(); |
694 |
|
|
695 |
|
/** |
696 |
|
* Index of element returned by most recent call to next. |
705 |
|
} |
706 |
|
|
707 |
|
public E next() { |
708 |
< |
if (remaining == 0) |
708 |
> |
if (remaining <= 0) |
709 |
|
throw new NoSuchElementException(); |
710 |
< |
E e = checkedElementAt(elements, cursor); |
711 |
< |
lastRet = cursor; |
712 |
< |
cursor = inc(cursor, elements.length); |
710 |
> |
final Object[] es = elements; |
711 |
> |
E e = nonNullElementAt(es, cursor); |
712 |
> |
cursor = inc(lastRet = cursor, es.length); |
713 |
|
remaining--; |
714 |
|
return e; |
715 |
|
} |
716 |
|
|
717 |
|
void postDelete(boolean leftShifted) { |
718 |
|
if (leftShifted) |
719 |
< |
cursor = dec(cursor, elements.length); // undo inc in next |
719 |
> |
cursor = dec(cursor, elements.length); |
720 |
|
} |
721 |
|
|
722 |
|
public final void remove() { |
728 |
|
|
729 |
|
public void forEachRemaining(Consumer<? super E> action) { |
730 |
|
Objects.requireNonNull(action); |
731 |
< |
final Object[] elements = ArrayDeque.this.elements; |
732 |
< |
final int capacity = elements.length; |
733 |
< |
int k = remaining; |
731 |
> |
int r; |
732 |
> |
if ((r = remaining) <= 0) |
733 |
> |
return; |
734 |
|
remaining = 0; |
735 |
< |
for (int i = cursor; --k >= 0; i = inc(i, capacity)) |
736 |
< |
action.accept(checkedElementAt(elements, i)); |
735 |
> |
final Object[] es = elements; |
736 |
> |
if (es[cursor] == null || sub(tail, cursor, es.length) != r) |
737 |
> |
throw new ConcurrentModificationException(); |
738 |
> |
for (int i = cursor, end = tail, to = (i <= end) ? end : es.length; |
739 |
> |
; i = 0, to = end) { |
740 |
> |
for (; i < to; i++) |
741 |
> |
action.accept(elementAt(es, i)); |
742 |
> |
if (to == end) { |
743 |
> |
if (end != tail) |
744 |
> |
throw new ConcurrentModificationException(); |
745 |
> |
lastRet = dec(end, es.length); |
746 |
> |
break; |
747 |
> |
} |
748 |
> |
} |
749 |
|
} |
750 |
|
} |
751 |
|
|
752 |
|
private class DescendingIterator extends DeqIterator { |
753 |
< |
DescendingIterator() { cursor = tail(); } |
753 |
> |
DescendingIterator() { cursor = dec(tail, elements.length); } |
754 |
|
|
755 |
|
public final E next() { |
756 |
< |
if (remaining == 0) |
756 |
> |
if (remaining <= 0) |
757 |
|
throw new NoSuchElementException(); |
758 |
< |
E e = checkedElementAt(elements, cursor); |
759 |
< |
lastRet = cursor; |
760 |
< |
cursor = dec(cursor, elements.length); |
758 |
> |
final Object[] es = elements; |
759 |
> |
E e = nonNullElementAt(es, cursor); |
760 |
> |
cursor = dec(lastRet = cursor, es.length); |
761 |
|
remaining--; |
762 |
|
return e; |
763 |
|
} |
764 |
|
|
765 |
|
void postDelete(boolean leftShifted) { |
766 |
|
if (!leftShifted) |
767 |
< |
cursor = inc(cursor, elements.length); // undo dec in next |
767 |
> |
cursor = inc(cursor, elements.length); |
768 |
|
} |
769 |
|
|
770 |
|
public final void forEachRemaining(Consumer<? super E> action) { |
771 |
|
Objects.requireNonNull(action); |
772 |
< |
final Object[] elements = ArrayDeque.this.elements; |
773 |
< |
final int capacity = elements.length; |
774 |
< |
int k = remaining; |
772 |
> |
int r; |
773 |
> |
if ((r = remaining) <= 0) |
774 |
> |
return; |
775 |
|
remaining = 0; |
776 |
< |
for (int i = cursor; --k >= 0; i = dec(i, capacity)) |
777 |
< |
action.accept(checkedElementAt(elements, i)); |
776 |
> |
final Object[] es = elements; |
777 |
> |
if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r) |
778 |
> |
throw new ConcurrentModificationException(); |
779 |
> |
for (int i = cursor, end = head, to = (i >= end) ? end : 0; |
780 |
> |
; i = es.length - 1, to = end) { |
781 |
> |
// hotspot generates faster code than for: i >= to ! |
782 |
> |
for (; i > to - 1; i--) |
783 |
> |
action.accept(elementAt(es, i)); |
784 |
> |
if (to == end) { |
785 |
> |
if (end != head) |
786 |
> |
throw new ConcurrentModificationException(); |
787 |
> |
lastRet = end; |
788 |
> |
break; |
789 |
> |
} |
790 |
> |
} |
791 |
|
} |
792 |
|
} |
793 |
|
|
805 |
|
* @since 1.8 |
806 |
|
*/ |
807 |
|
public Spliterator<E> spliterator() { |
808 |
< |
return new ArrayDequeSpliterator(); |
808 |
> |
return new DeqSpliterator(); |
809 |
|
} |
810 |
|
|
811 |
< |
final class ArrayDequeSpliterator implements Spliterator<E> { |
812 |
< |
private int cursor; |
813 |
< |
private int remaining; // -1 until late-binding first use |
811 |
> |
final class DeqSpliterator implements Spliterator<E> { |
812 |
> |
private int fence; // -1 until first use |
813 |
> |
private int cursor; // current index, modified on traverse/split |
814 |
|
|
815 |
|
/** Constructs late-binding spliterator over all elements. */ |
816 |
< |
ArrayDequeSpliterator() { |
817 |
< |
this.remaining = -1; |
816 |
> |
DeqSpliterator() { |
817 |
> |
this.fence = -1; |
818 |
|
} |
819 |
|
|
820 |
< |
/** Constructs spliterator over the given slice. */ |
821 |
< |
ArrayDequeSpliterator(int cursor, int count) { |
822 |
< |
this.cursor = cursor; |
823 |
< |
this.remaining = count; |
824 |
< |
} |
825 |
< |
|
826 |
< |
/** Ensures late-binding initialization; then returns remaining. */ |
827 |
< |
private int remaining() { |
828 |
< |
if (remaining < 0) { |
820 |
> |
/** Constructs spliterator over the given range. */ |
821 |
> |
DeqSpliterator(int origin, int fence) { |
822 |
> |
// assert 0 <= origin && origin < elements.length; |
823 |
> |
// assert 0 <= fence && fence < elements.length; |
824 |
> |
this.cursor = origin; |
825 |
> |
this.fence = fence; |
826 |
> |
} |
827 |
> |
|
828 |
> |
/** Ensures late-binding initialization; then returns fence. */ |
829 |
> |
private int getFence() { // force initialization |
830 |
> |
int t; |
831 |
> |
if ((t = fence) < 0) { |
832 |
> |
t = fence = tail; |
833 |
|
cursor = head; |
810 |
– |
remaining = size; |
834 |
|
} |
835 |
< |
return remaining; |
835 |
> |
return t; |
836 |
|
} |
837 |
|
|
838 |
< |
public ArrayDequeSpliterator trySplit() { |
839 |
< |
final int mid; |
840 |
< |
if ((mid = remaining() >> 1) > 0) { |
841 |
< |
int oldCursor = cursor; |
842 |
< |
cursor = add(cursor, mid, elements.length); |
843 |
< |
remaining -= mid; |
821 |
< |
return new ArrayDequeSpliterator(oldCursor, mid); |
822 |
< |
} |
823 |
< |
return null; |
838 |
> |
public DeqSpliterator trySplit() { |
839 |
> |
final Object[] es = elements; |
840 |
> |
final int i, n; |
841 |
> |
return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0) |
842 |
> |
? null |
843 |
> |
: new DeqSpliterator(i, cursor = inc(i, n, es.length)); |
844 |
|
} |
845 |
|
|
846 |
|
public void forEachRemaining(Consumer<? super E> action) { |
847 |
< |
Objects.requireNonNull(action); |
848 |
< |
final Object[] elements = ArrayDeque.this.elements; |
849 |
< |
final int capacity = elements.length; |
850 |
< |
int k = remaining(); |
851 |
< |
remaining = 0; |
852 |
< |
for (int i = cursor; --k >= 0; i = inc(i, capacity)) |
853 |
< |
action.accept(checkedElementAt(elements, i)); |
847 |
> |
if (action == null) |
848 |
> |
throw new NullPointerException(); |
849 |
> |
final int end = getFence(), cursor = this.cursor; |
850 |
> |
final Object[] es = elements; |
851 |
> |
if (cursor != end) { |
852 |
> |
this.cursor = end; |
853 |
> |
// null check at both ends of range is sufficient |
854 |
> |
if (es[cursor] == null || es[dec(end, es.length)] == null) |
855 |
> |
throw new ConcurrentModificationException(); |
856 |
> |
for (int i = cursor, to = (i <= end) ? end : es.length; |
857 |
> |
; i = 0, to = end) { |
858 |
> |
for (; i < to; i++) |
859 |
> |
action.accept(elementAt(es, i)); |
860 |
> |
if (to == end) break; |
861 |
> |
} |
862 |
> |
} |
863 |
|
} |
864 |
|
|
865 |
|
public boolean tryAdvance(Consumer<? super E> action) { |
866 |
|
Objects.requireNonNull(action); |
867 |
< |
if (remaining() == 0) |
867 |
> |
final Object[] es = elements; |
868 |
> |
if (fence < 0) { fence = tail; cursor = head; } // late-binding |
869 |
> |
final int i; |
870 |
> |
if ((i = cursor) == fence) |
871 |
|
return false; |
872 |
< |
action.accept(checkedElementAt(elements, cursor)); |
873 |
< |
cursor = inc(cursor, elements.length); |
874 |
< |
remaining--; |
872 |
> |
E e = nonNullElementAt(es, i); |
873 |
> |
cursor = inc(i, es.length); |
874 |
> |
action.accept(e); |
875 |
|
return true; |
876 |
|
} |
877 |
|
|
878 |
|
public long estimateSize() { |
879 |
< |
return remaining(); |
879 |
> |
return sub(getFence(), cursor, elements.length); |
880 |
|
} |
881 |
|
|
882 |
|
public int characteristics() { |
887 |
|
} |
888 |
|
} |
889 |
|
|
890 |
< |
@Override |
890 |
> |
/** |
891 |
> |
* @throws NullPointerException {@inheritDoc} |
892 |
> |
*/ |
893 |
|
public void forEach(Consumer<? super E> action) { |
860 |
– |
// checkInvariants(); |
894 |
|
Objects.requireNonNull(action); |
895 |
< |
final Object[] elements = this.elements; |
896 |
< |
final int capacity = elements.length; |
897 |
< |
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) |
898 |
< |
action.accept(elementAt(i)); |
895 |
> |
final Object[] es = elements; |
896 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
897 |
> |
; i = 0, to = end) { |
898 |
> |
for (; i < to; i++) |
899 |
> |
action.accept(elementAt(es, i)); |
900 |
> |
if (to == end) { |
901 |
> |
if (end != tail) throw new ConcurrentModificationException(); |
902 |
> |
break; |
903 |
> |
} |
904 |
> |
} |
905 |
|
// checkInvariants(); |
906 |
|
} |
907 |
|
|
914 |
|
*/ |
915 |
|
/* public */ void replaceAll(UnaryOperator<E> operator) { |
916 |
|
Objects.requireNonNull(operator); |
917 |
< |
final Object[] elements = this.elements; |
918 |
< |
final int capacity = elements.length; |
919 |
< |
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) |
920 |
< |
elements[i] = operator.apply(elementAt(i)); |
917 |
> |
final Object[] es = elements; |
918 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
919 |
> |
; i = 0, to = end) { |
920 |
> |
for (; i < to; i++) |
921 |
> |
es[i] = operator.apply(elementAt(es, i)); |
922 |
> |
if (to == end) { |
923 |
> |
if (end != tail) throw new ConcurrentModificationException(); |
924 |
> |
break; |
925 |
> |
} |
926 |
> |
} |
927 |
|
// checkInvariants(); |
928 |
|
} |
929 |
|
|
930 |
|
/** |
931 |
|
* @throws NullPointerException {@inheritDoc} |
932 |
|
*/ |
888 |
– |
@Override |
933 |
|
public boolean removeIf(Predicate<? super E> filter) { |
934 |
|
Objects.requireNonNull(filter); |
935 |
|
return bulkRemove(filter); |
938 |
|
/** |
939 |
|
* @throws NullPointerException {@inheritDoc} |
940 |
|
*/ |
897 |
– |
@Override |
941 |
|
public boolean removeAll(Collection<?> c) { |
942 |
|
Objects.requireNonNull(c); |
943 |
|
return bulkRemove(e -> c.contains(e)); |
946 |
|
/** |
947 |
|
* @throws NullPointerException {@inheritDoc} |
948 |
|
*/ |
906 |
– |
@Override |
949 |
|
public boolean retainAll(Collection<?> c) { |
950 |
|
Objects.requireNonNull(c); |
951 |
|
return bulkRemove(e -> !c.contains(e)); |
954 |
|
/** Implementation of bulk remove methods. */ |
955 |
|
private boolean bulkRemove(Predicate<? super E> filter) { |
956 |
|
// checkInvariants(); |
957 |
< |
final Object[] elements = this.elements; |
958 |
< |
final int capacity = elements.length; |
959 |
< |
int i = head, j = i, remaining = size, deleted = 0; |
960 |
< |
try { |
961 |
< |
for (; remaining > 0; remaining--, i = inc(i, capacity)) { |
962 |
< |
@SuppressWarnings("unchecked") E e = (E) elements[i]; |
963 |
< |
if (filter.test(e)) |
964 |
< |
deleted++; |
965 |
< |
else { |
966 |
< |
if (j != i) |
967 |
< |
elements[j] = e; |
968 |
< |
j = inc(j, capacity); |
969 |
< |
} |
957 |
> |
final Object[] es = elements; |
958 |
> |
// Optimize for initial run of survivors |
959 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
960 |
> |
; i = 0, to = end) { |
961 |
> |
for (; i < to; i++) |
962 |
> |
if (filter.test(elementAt(es, i))) |
963 |
> |
return bulkRemoveModified(filter, i); |
964 |
> |
if (to == end) { |
965 |
> |
if (end != tail) throw new ConcurrentModificationException(); |
966 |
> |
break; |
967 |
> |
} |
968 |
> |
} |
969 |
> |
return false; |
970 |
> |
} |
971 |
> |
|
972 |
> |
// A tiny bit set implementation |
973 |
> |
|
974 |
> |
private static long[] nBits(int n) { |
975 |
> |
return new long[((n - 1) >> 6) + 1]; |
976 |
> |
} |
977 |
> |
private static void setBit(long[] bits, int i) { |
978 |
> |
bits[i >> 6] |= 1L << i; |
979 |
> |
} |
980 |
> |
private static boolean isClear(long[] bits, int i) { |
981 |
> |
return (bits[i >> 6] & (1L << i)) == 0; |
982 |
> |
} |
983 |
> |
|
984 |
> |
/** |
985 |
> |
* Helper for bulkRemove, in case of at least one deletion. |
986 |
> |
* Tolerate predicates that reentrantly access the collection for |
987 |
> |
* read (but writers still get CME), so traverse once to find |
988 |
> |
* elements to delete, a second pass to physically expunge. |
989 |
> |
* |
990 |
> |
* @param beg valid index of first element to be deleted |
991 |
> |
*/ |
992 |
> |
private boolean bulkRemoveModified( |
993 |
> |
Predicate<? super E> filter, final int beg) { |
994 |
> |
final Object[] es = elements; |
995 |
> |
final int capacity = es.length; |
996 |
> |
final int end = tail; |
997 |
> |
final long[] deathRow = nBits(sub(end, beg, capacity)); |
998 |
> |
deathRow[0] = 1L; // set bit 0 |
999 |
> |
for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg; |
1000 |
> |
; i = 0, to = end, k -= capacity) { |
1001 |
> |
for (; i < to; i++) |
1002 |
> |
if (filter.test(elementAt(es, i))) |
1003 |
> |
setBit(deathRow, i - k); |
1004 |
> |
if (to == end) break; |
1005 |
> |
} |
1006 |
> |
// a two-finger traversal, with hare i reading, tortoise w writing |
1007 |
> |
int w = beg; |
1008 |
> |
for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg; |
1009 |
> |
; w = 0) { // w rejoins i on second leg |
1010 |
> |
// In this loop, i and w are on the same leg, with i > w |
1011 |
> |
for (; i < to; i++) |
1012 |
> |
if (isClear(deathRow, i - k)) |
1013 |
> |
es[w++] = es[i]; |
1014 |
> |
if (to == end) break; |
1015 |
> |
// In this loop, w is on the first leg, i on the second |
1016 |
> |
for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++) |
1017 |
> |
if (isClear(deathRow, i - k)) |
1018 |
> |
es[w++] = es[i]; |
1019 |
> |
if (i >= to) { |
1020 |
> |
if (w == capacity) w = 0; // "corner" case |
1021 |
> |
break; |
1022 |
|
} |
929 |
– |
return deleted > 0; |
930 |
– |
} catch (Throwable ex) { |
931 |
– |
if (deleted > 0) |
932 |
– |
for (; remaining > 0; |
933 |
– |
remaining--, i = inc(i, capacity), j = inc(j, capacity)) |
934 |
– |
elements[j] = elements[i]; |
935 |
– |
throw ex; |
936 |
– |
} finally { |
937 |
– |
size -= deleted; |
938 |
– |
for (; --deleted >= 0; j = inc(j, capacity)) |
939 |
– |
elements[j] = null; |
940 |
– |
// checkInvariants(); |
1023 |
|
} |
1024 |
+ |
if (end != tail) throw new ConcurrentModificationException(); |
1025 |
+ |
circularClear(es, tail = w, end); |
1026 |
+ |
// checkInvariants(); |
1027 |
+ |
return true; |
1028 |
|
} |
1029 |
|
|
1030 |
|
/** |
1037 |
|
*/ |
1038 |
|
public boolean contains(Object o) { |
1039 |
|
if (o != null) { |
1040 |
< |
final Object[] elements = this.elements; |
1041 |
< |
final int capacity = elements.length; |
1042 |
< |
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) |
1043 |
< |
if (o.equals(elements[i])) |
1044 |
< |
return true; |
1040 |
> |
final Object[] es = elements; |
1041 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
1042 |
> |
; i = 0, to = end) { |
1043 |
> |
for (; i < to; i++) |
1044 |
> |
if (o.equals(es[i])) |
1045 |
> |
return true; |
1046 |
> |
if (to == end) break; |
1047 |
> |
} |
1048 |
|
} |
1049 |
|
return false; |
1050 |
|
} |
1071 |
|
* The deque will be empty after this call returns. |
1072 |
|
*/ |
1073 |
|
public void clear() { |
1074 |
< |
final Object[] elements = this.elements; |
1075 |
< |
final int capacity = elements.length; |
987 |
< |
final int h = this.head; |
988 |
< |
final int s = size; |
989 |
< |
if (capacity - h >= s) |
990 |
< |
Arrays.fill(elements, h, h + s, null); |
991 |
< |
else { |
992 |
< |
Arrays.fill(elements, h, capacity, null); |
993 |
< |
Arrays.fill(elements, 0, s - capacity + h, null); |
994 |
< |
} |
995 |
< |
size = head = 0; |
1074 |
> |
circularClear(elements, head, tail); |
1075 |
> |
head = tail = 0; |
1076 |
|
// checkInvariants(); |
1077 |
|
} |
1078 |
|
|
1079 |
|
/** |
1080 |
+ |
* Nulls out slots starting at array index i, upto index end. |
1081 |
+ |
* Condition i == end means "empty" - nothing to do. |
1082 |
+ |
*/ |
1083 |
+ |
private static void circularClear(Object[] es, int i, int end) { |
1084 |
+ |
// assert 0 <= i && i < es.length; |
1085 |
+ |
// assert 0 <= end && end < es.length; |
1086 |
+ |
for (int to = (i <= end) ? end : es.length; |
1087 |
+ |
; i = 0, to = end) { |
1088 |
+ |
for (; i < to; i++) es[i] = null; |
1089 |
+ |
if (to == end) break; |
1090 |
+ |
} |
1091 |
+ |
} |
1092 |
+ |
|
1093 |
+ |
/** |
1094 |
|
* Returns an array containing all of the elements in this deque |
1095 |
|
* in proper sequence (from first to last element). |
1096 |
|
* |
1104 |
|
* @return an array containing all of the elements in this deque |
1105 |
|
*/ |
1106 |
|
public Object[] toArray() { |
1107 |
< |
final int head = this.head; |
1108 |
< |
final int firstLeg; |
1109 |
< |
Object[] a = Arrays.copyOfRange(elements, head, head + size); |
1110 |
< |
if ((firstLeg = elements.length - head) < size) |
1111 |
< |
System.arraycopy(elements, 0, a, firstLeg, size - firstLeg); |
1107 |
> |
return toArray(Object[].class); |
1108 |
> |
} |
1109 |
> |
|
1110 |
> |
private <T> T[] toArray(Class<T[]> klazz) { |
1111 |
> |
final Object[] es = elements; |
1112 |
> |
final T[] a; |
1113 |
> |
final int head = this.head, tail = this.tail, end; |
1114 |
> |
if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) { |
1115 |
> |
// Uses null extension feature of copyOfRange |
1116 |
> |
a = Arrays.copyOfRange(es, head, end, klazz); |
1117 |
> |
} else { |
1118 |
> |
// integer overflow! |
1119 |
> |
a = Arrays.copyOfRange(es, 0, end - head, klazz); |
1120 |
> |
System.arraycopy(es, head, a, 0, es.length - head); |
1121 |
> |
} |
1122 |
> |
if (end != tail) |
1123 |
> |
System.arraycopy(es, 0, a, es.length - head, tail); |
1124 |
|
return a; |
1125 |
|
} |
1126 |
|
|
1162 |
|
*/ |
1163 |
|
@SuppressWarnings("unchecked") |
1164 |
|
public <T> T[] toArray(T[] a) { |
1165 |
< |
final Object[] elements = this.elements; |
1166 |
< |
final int head = this.head; |
1167 |
< |
final int firstLeg; |
1168 |
< |
boolean wrap = (firstLeg = elements.length - head) < size; |
1169 |
< |
if (size > a.length) { |
1170 |
< |
a = (T[]) Arrays.copyOfRange(elements, head, head + size, |
1171 |
< |
a.getClass()); |
1172 |
< |
} else { |
1067 |
< |
System.arraycopy(elements, head, a, 0, wrap ? firstLeg : size); |
1068 |
< |
if (size < a.length) |
1069 |
< |
a[size] = null; |
1165 |
> |
final int size; |
1166 |
> |
if ((size = size()) > a.length) |
1167 |
> |
return toArray((Class<T[]>) a.getClass()); |
1168 |
> |
final Object[] es = elements; |
1169 |
> |
for (int i = head, j = 0, len = Math.min(size, es.length - i); |
1170 |
> |
; i = 0, len = tail) { |
1171 |
> |
System.arraycopy(es, i, a, j, len); |
1172 |
> |
if ((j += len) == size) break; |
1173 |
|
} |
1174 |
< |
if (wrap) |
1175 |
< |
System.arraycopy(elements, 0, a, firstLeg, size - firstLeg); |
1174 |
> |
if (size < a.length) |
1175 |
> |
a[size] = null; |
1176 |
|
return a; |
1177 |
|
} |
1178 |
|
|
1210 |
|
s.defaultWriteObject(); |
1211 |
|
|
1212 |
|
// Write out size |
1213 |
< |
s.writeInt(size); |
1213 |
> |
s.writeInt(size()); |
1214 |
|
|
1215 |
|
// Write out elements in order. |
1216 |
< |
final Object[] elements = this.elements; |
1217 |
< |
final int capacity = elements.length; |
1218 |
< |
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) |
1219 |
< |
s.writeObject(elements[i]); |
1216 |
> |
final Object[] es = elements; |
1217 |
> |
for (int i = head, end = tail, to = (i <= end) ? end : es.length; |
1218 |
> |
; i = 0, to = end) { |
1219 |
> |
for (; i < to; i++) |
1220 |
> |
s.writeObject(es[i]); |
1221 |
> |
if (to == end) break; |
1222 |
> |
} |
1223 |
|
} |
1224 |
|
|
1225 |
|
/** |
1234 |
|
s.defaultReadObject(); |
1235 |
|
|
1236 |
|
// Read in size and allocate array |
1237 |
< |
elements = new Object[size = s.readInt()]; |
1237 |
> |
int size = s.readInt(); |
1238 |
> |
elements = new Object[size + 1]; |
1239 |
> |
this.tail = size; |
1240 |
|
|
1241 |
|
// Read in all elements in the proper order. |
1242 |
|
for (int i = 0; i < size; i++) |
1244 |
|
} |
1245 |
|
|
1246 |
|
/** debugging */ |
1247 |
< |
private void checkInvariants() { |
1247 |
> |
void checkInvariants() { |
1248 |
> |
// Use head and tail fields with empty slot at tail strategy. |
1249 |
> |
// head == tail disambiguates to "empty". |
1250 |
|
try { |
1251 |
|
int capacity = elements.length; |
1252 |
< |
assert size >= 0 && size <= capacity; |
1253 |
< |
assert head >= 0 && ((capacity == 0 && head == 0 && size == 0) |
1254 |
< |
|| head < capacity); |
1255 |
< |
assert size == 0 |
1256 |
< |
|| (elements[head] != null && elements[tail()] != null); |
1257 |
< |
assert size == capacity |
1258 |
< |
|| (elements[dec(head, capacity)] == null |
1149 |
< |
&& elements[inc(tail(), capacity)] == null); |
1252 |
> |
// assert 0 <= head && head < capacity; |
1253 |
> |
// assert 0 <= tail && tail < capacity; |
1254 |
> |
// assert capacity > 0; |
1255 |
> |
// assert size() < capacity; |
1256 |
> |
// assert head == tail || elements[head] != null; |
1257 |
> |
// assert elements[tail] == null; |
1258 |
> |
// assert head == tail || elements[dec(tail, capacity)] != null; |
1259 |
|
} catch (Throwable t) { |
1260 |
< |
System.err.printf("head=%d size=%d capacity=%d%n", |
1261 |
< |
head, size, elements.length); |
1260 |
> |
System.err.printf("head=%d tail=%d capacity=%d%n", |
1261 |
> |
head, tail, elements.length); |
1262 |
|
System.err.printf("elements=%s%n", |
1263 |
|
Arrays.toString(elements)); |
1264 |
|
throw t; |