1 |
|
/* |
2 |
|
* Written by Josh Bloch of Google Inc. and released to the public domain, |
3 |
< |
* as explained at http://creativecommons.org/licenses/publicdomain. |
3 |
> |
* as explained at http://creativecommons.org/publicdomain/zero/1.0/. |
4 |
|
*/ |
5 |
|
|
6 |
|
package java.util; |
7 |
< |
import java.io.*; |
7 |
> |
|
8 |
> |
import java.io.Serializable; |
9 |
> |
import java.util.function.Consumer; |
10 |
> |
import java.util.function.Predicate; |
11 |
> |
import java.util.function.UnaryOperator; |
12 |
|
|
13 |
|
/** |
14 |
|
* Resizable-array implementation of the {@link Deque} interface. Array |
19 |
|
* {@link Stack} when used as a stack, and faster than {@link LinkedList} |
20 |
|
* when used as a queue. |
21 |
|
* |
22 |
< |
* <p>Most <tt>ArrayDeque</tt> operations run in amortized constant time. |
23 |
< |
* Exceptions include {@link #remove(Object) remove}, {@link |
24 |
< |
* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence |
25 |
< |
* removeLastOccurrence}, {@link #contains contains}, {@link #iterator |
26 |
< |
* iterator.remove()}, and the bulk operations, all of which run in linear |
27 |
< |
* time. |
22 |
> |
* <p>Most {@code ArrayDeque} operations run in amortized constant time. |
23 |
> |
* Exceptions include |
24 |
> |
* {@link #remove(Object) remove}, |
25 |
> |
* {@link #removeFirstOccurrence removeFirstOccurrence}, |
26 |
> |
* {@link #removeLastOccurrence removeLastOccurrence}, |
27 |
> |
* {@link #contains contains}, |
28 |
> |
* {@link #iterator iterator.remove()}, |
29 |
> |
* and the bulk operations, all of which run in linear time. |
30 |
|
* |
31 |
< |
* <p>The iterators returned by this class's <tt>iterator</tt> method are |
32 |
< |
* <i>fail-fast</i>: If the deque is modified at any time after the iterator |
33 |
< |
* is created, in any way except through the iterator's own <tt>remove</tt> |
34 |
< |
* method, the iterator will generally throw a {@link |
31 |
> |
* <p>The iterators returned by this class's {@link #iterator() iterator} |
32 |
> |
* method are <em>fail-fast</em>: If the deque is modified at any time after |
33 |
> |
* the iterator is created, in any way except through the iterator's own |
34 |
> |
* {@code remove} method, the iterator will generally throw a {@link |
35 |
|
* ConcurrentModificationException}. Thus, in the face of concurrent |
36 |
|
* modification, the iterator fails quickly and cleanly, rather than risking |
37 |
|
* arbitrary, non-deterministic behavior at an undetermined time in the |
40 |
|
* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed |
41 |
|
* as it is, generally speaking, impossible to make any hard guarantees in the |
42 |
|
* presence of unsynchronized concurrent modification. Fail-fast iterators |
43 |
< |
* throw <tt>ConcurrentModificationException</tt> on a best-effort basis. |
43 |
> |
* throw {@code ConcurrentModificationException} on a best-effort basis. |
44 |
|
* Therefore, it would be wrong to write a program that depended on this |
45 |
|
* exception for its correctness: <i>the fail-fast behavior of iterators |
46 |
|
* should be used only to detect bugs.</i> |
50 |
|
* Iterator} interfaces. |
51 |
|
* |
52 |
|
* <p>This class is a member of the |
53 |
< |
* <a href="{@docRoot}/../guide/collections/index.html"> |
53 |
> |
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
54 |
|
* Java Collections Framework</a>. |
55 |
|
* |
56 |
|
* @author Josh Bloch and Doug Lea |
57 |
+ |
* @param <E> the type of elements held in this deque |
58 |
|
* @since 1.6 |
52 |
– |
* @param <E> the type of elements held in this collection |
59 |
|
*/ |
60 |
|
public class ArrayDeque<E> extends AbstractCollection<E> |
61 |
|
implements Deque<E>, Cloneable, Serializable |
62 |
|
{ |
63 |
|
/** |
64 |
|
* The array in which the elements of the deque are stored. |
65 |
< |
* The capacity of the deque is the length of this array, which is |
66 |
< |
* always a power of two. The array is never allowed to become |
61 |
< |
* full, except transiently within an addX method where it is |
62 |
< |
* resized (see doubleCapacity) immediately upon becoming full, |
63 |
< |
* thus avoiding head and tail wrapping around to equal each |
64 |
< |
* other. We also guarantee that all array cells not holding |
65 |
< |
* deque elements are always null. |
65 |
> |
* We guarantee that all array cells not holding deque elements |
66 |
> |
* are always null. |
67 |
|
*/ |
68 |
< |
private transient E[] elements; |
68 |
> |
transient Object[] elements; |
69 |
|
|
70 |
|
/** |
71 |
|
* The index of the element at the head of the deque (which is the |
72 |
|
* element that would be removed by remove() or pop()); or an |
73 |
< |
* arbitrary number equal to tail if the deque is empty. |
73 |
> |
* arbitrary number 0 <= head < elements.length if the deque is empty. |
74 |
|
*/ |
75 |
< |
private transient int head; |
75 |
> |
transient int head; |
76 |
|
|
77 |
< |
/** |
78 |
< |
* The index at which the next element would be added to the tail |
78 |
< |
* of the deque (via addLast(E), add(E), or push(E)). |
79 |
< |
*/ |
80 |
< |
private transient int tail; |
77 |
> |
/** Number of elements in this collection. */ |
78 |
> |
transient int size; |
79 |
|
|
80 |
|
/** |
81 |
< |
* The minimum capacity that we'll use for a newly created deque. |
82 |
< |
* Must be a power of 2. |
83 |
< |
*/ |
84 |
< |
private static final int MIN_INITIAL_CAPACITY = 8; |
85 |
< |
|
86 |
< |
// ****** Array allocation and resizing utilities ****** |
87 |
< |
|
88 |
< |
/** |
89 |
< |
* Allocate empty array to hold the given number of elements. |
90 |
< |
* |
91 |
< |
* @param numElements the number of elements to hold |
92 |
< |
*/ |
93 |
< |
private void allocateElements(int numElements) { |
94 |
< |
int initialCapacity = MIN_INITIAL_CAPACITY; |
95 |
< |
// Find the best power of two to hold elements. |
96 |
< |
// Tests "<=" because arrays aren't kept full. |
97 |
< |
if (numElements >= initialCapacity) { |
98 |
< |
initialCapacity = numElements; |
99 |
< |
initialCapacity |= (initialCapacity >>> 1); |
100 |
< |
initialCapacity |= (initialCapacity >>> 2); |
101 |
< |
initialCapacity |= (initialCapacity >>> 4); |
102 |
< |
initialCapacity |= (initialCapacity >>> 8); |
103 |
< |
initialCapacity |= (initialCapacity >>> 16); |
104 |
< |
initialCapacity++; |
81 |
> |
* The maximum size of array to allocate. |
82 |
> |
* Some VMs reserve some header words in an array. |
83 |
> |
* Attempts to allocate larger arrays may result in |
84 |
> |
* OutOfMemoryError: Requested array size exceeds VM limit |
85 |
> |
*/ |
86 |
> |
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
87 |
> |
|
88 |
> |
/** |
89 |
> |
* Increases the capacity of this deque by at least the given amount. |
90 |
> |
* |
91 |
> |
* @param needed the required minimum extra capacity; must be positive |
92 |
> |
*/ |
93 |
> |
private void grow(int needed) { |
94 |
> |
// overflow-conscious code |
95 |
> |
// checkInvariants(); |
96 |
> |
final int oldCapacity = elements.length; |
97 |
> |
int newCapacity; |
98 |
> |
// Double size if small; else grow by 50% |
99 |
> |
int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1); |
100 |
> |
if (jump < needed |
101 |
> |
|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0) |
102 |
> |
newCapacity = newCapacity(needed, jump); |
103 |
> |
elements = Arrays.copyOf(elements, newCapacity); |
104 |
> |
if (oldCapacity - head < size) { |
105 |
> |
// wrap around; slide first leg forward to end of array |
106 |
> |
int newSpace = newCapacity - oldCapacity; |
107 |
> |
System.arraycopy(elements, head, |
108 |
> |
elements, head + newSpace, |
109 |
> |
oldCapacity - head); |
110 |
> |
Arrays.fill(elements, head, head + newSpace, null); |
111 |
> |
head += newSpace; |
112 |
> |
} |
113 |
> |
// checkInvariants(); |
114 |
> |
} |
115 |
|
|
116 |
< |
if (initialCapacity < 0) // Too many elements, must back off |
117 |
< |
initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements |
116 |
> |
/** Capacity calculation for edge conditions, especially overflow. */ |
117 |
> |
private int newCapacity(int needed, int jump) { |
118 |
> |
final int oldCapacity = elements.length, minCapacity; |
119 |
> |
if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) { |
120 |
> |
if (minCapacity < 0) |
121 |
> |
throw new IllegalStateException("Sorry, deque too big"); |
122 |
> |
return Integer.MAX_VALUE; |
123 |
|
} |
124 |
< |
elements = (E[]) new Object[initialCapacity]; |
124 |
> |
if (needed > jump) |
125 |
> |
return minCapacity; |
126 |
> |
return (oldCapacity + jump - MAX_ARRAY_SIZE < 0) |
127 |
> |
? oldCapacity + jump |
128 |
> |
: MAX_ARRAY_SIZE; |
129 |
|
} |
130 |
|
|
131 |
|
/** |
132 |
< |
* Double the capacity of this deque. Call only when full, i.e., |
133 |
< |
* when head and tail have wrapped around to become equal. |
132 |
> |
* Increases the internal storage of this collection, if necessary, |
133 |
> |
* to ensure that it can hold at least the given number of elements. |
134 |
> |
* |
135 |
> |
* @param minCapacity the desired minimum capacity |
136 |
> |
* @since TBD |
137 |
|
*/ |
138 |
< |
private void doubleCapacity() { |
139 |
< |
assert head == tail; |
140 |
< |
int p = head; |
141 |
< |
int n = elements.length; |
122 |
< |
int r = n - p; // number of elements to the right of p |
123 |
< |
int newCapacity = n << 1; |
124 |
< |
if (newCapacity < 0) |
125 |
< |
throw new IllegalStateException("Sorry, deque too big"); |
126 |
< |
Object[] a = new Object[newCapacity]; |
127 |
< |
System.arraycopy(elements, p, a, 0, r); |
128 |
< |
System.arraycopy(elements, 0, a, r, p); |
129 |
< |
elements = (E[])a; |
130 |
< |
head = 0; |
131 |
< |
tail = n; |
138 |
> |
/* public */ void ensureCapacity(int minCapacity) { |
139 |
> |
if (minCapacity > elements.length) |
140 |
> |
grow(minCapacity - elements.length); |
141 |
> |
// checkInvariants(); |
142 |
|
} |
143 |
|
|
144 |
|
/** |
145 |
< |
* Copies the elements from our element array into the specified array, |
136 |
< |
* in order (from first to last element in the deque). It is assumed |
137 |
< |
* that the array is large enough to hold all elements in the deque. |
145 |
> |
* Minimizes the internal storage of this collection. |
146 |
|
* |
147 |
< |
* @return its argument |
147 |
> |
* @since TBD |
148 |
|
*/ |
149 |
< |
private <T> T[] copyElements(T[] a) { |
150 |
< |
if (head < tail) { |
151 |
< |
System.arraycopy(elements, head, a, 0, size()); |
152 |
< |
} else if (head > tail) { |
145 |
< |
int headPortionLen = elements.length - head; |
146 |
< |
System.arraycopy(elements, head, a, 0, headPortionLen); |
147 |
< |
System.arraycopy(elements, 0, a, headPortionLen, tail); |
149 |
> |
/* public */ void trimToSize() { |
150 |
> |
if (size < elements.length) { |
151 |
> |
elements = toArray(); |
152 |
> |
head = 0; |
153 |
|
} |
154 |
< |
return a; |
154 |
> |
// checkInvariants(); |
155 |
|
} |
156 |
|
|
157 |
|
/** |
159 |
|
* sufficient to hold 16 elements. |
160 |
|
*/ |
161 |
|
public ArrayDeque() { |
162 |
< |
elements = (E[]) new Object[16]; |
162 |
> |
elements = new Object[16]; |
163 |
|
} |
164 |
|
|
165 |
|
/** |
166 |
|
* Constructs an empty array deque with an initial capacity |
167 |
|
* sufficient to hold the specified number of elements. |
168 |
|
* |
169 |
< |
* @param numElements lower bound on initial capacity of the deque |
169 |
> |
* @param numElements lower bound on initial capacity of the deque |
170 |
|
*/ |
171 |
|
public ArrayDeque(int numElements) { |
172 |
< |
allocateElements(numElements); |
172 |
> |
elements = new Object[numElements]; |
173 |
|
} |
174 |
|
|
175 |
|
/** |
183 |
|
* @throws NullPointerException if the specified collection is null |
184 |
|
*/ |
185 |
|
public ArrayDeque(Collection<? extends E> c) { |
186 |
< |
allocateElements(c.size()); |
187 |
< |
addAll(c); |
186 |
> |
Object[] elements = c.toArray(); |
187 |
> |
// defend against c.toArray (incorrectly) not returning Object[] |
188 |
> |
// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652) |
189 |
> |
size = elements.length; |
190 |
> |
if (elements.getClass() != Object[].class) |
191 |
> |
elements = Arrays.copyOf(elements, size, Object[].class); |
192 |
> |
for (Object obj : elements) |
193 |
> |
Objects.requireNonNull(obj); |
194 |
> |
this.elements = elements; |
195 |
> |
} |
196 |
> |
|
197 |
> |
/** |
198 |
> |
* Increments i, mod modulus. |
199 |
> |
* Precondition and postcondition: 0 <= i < modulus. |
200 |
> |
*/ |
201 |
> |
static final int inc(int i, int modulus) { |
202 |
> |
if (++i >= modulus) i = 0; |
203 |
> |
return i; |
204 |
> |
} |
205 |
> |
|
206 |
> |
/** |
207 |
> |
* Decrements i, mod modulus. |
208 |
> |
* Precondition and postcondition: 0 <= i < modulus. |
209 |
> |
*/ |
210 |
> |
static final int dec(int i, int modulus) { |
211 |
> |
if (--i < 0) i = modulus - 1; |
212 |
> |
return i; |
213 |
> |
} |
214 |
> |
|
215 |
> |
/** |
216 |
> |
* Adds i and j, mod modulus. |
217 |
> |
* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus. |
218 |
> |
*/ |
219 |
> |
static final int add(int i, int j, int modulus) { |
220 |
> |
if ((i += j) - modulus >= 0) i -= modulus; |
221 |
> |
return i; |
222 |
> |
} |
223 |
> |
|
224 |
> |
/** |
225 |
> |
* Returns the array index of the last element. |
226 |
> |
* May return invalid index -1 if there are no elements. |
227 |
> |
*/ |
228 |
> |
final int tail() { |
229 |
> |
return add(head, size - 1, elements.length); |
230 |
> |
} |
231 |
> |
|
232 |
> |
/** |
233 |
> |
* Returns element at array index i. |
234 |
> |
*/ |
235 |
> |
@SuppressWarnings("unchecked") |
236 |
> |
private E elementAt(int i) { |
237 |
> |
return (E) elements[i]; |
238 |
> |
} |
239 |
> |
|
240 |
> |
/** |
241 |
> |
* A version of elementAt that checks for null elements. |
242 |
> |
* This check doesn't catch all possible comodifications, |
243 |
> |
* but does catch ones that corrupt traversal. It's a little |
244 |
> |
* surprising that javac allows this abuse of generics. |
245 |
> |
*/ |
246 |
> |
static final <E> E nonNullElementAt(Object[] elements, int i) { |
247 |
> |
@SuppressWarnings("unchecked") E e = (E) elements[i]; |
248 |
> |
if (e == null) |
249 |
> |
throw new ConcurrentModificationException(); |
250 |
> |
return e; |
251 |
|
} |
252 |
|
|
253 |
|
// The main insertion and extraction methods are addFirst, |
261 |
|
* @throws NullPointerException if the specified element is null |
262 |
|
*/ |
263 |
|
public void addFirst(E e) { |
264 |
< |
if (e == null) |
265 |
< |
throw new NullPointerException(); |
266 |
< |
elements[head = (head - 1) & (elements.length - 1)] = e; |
267 |
< |
if (head == tail) |
268 |
< |
doubleCapacity(); |
264 |
> |
// checkInvariants(); |
265 |
> |
Objects.requireNonNull(e); |
266 |
> |
Object[] elements; |
267 |
> |
int capacity, h; |
268 |
> |
final int s; |
269 |
> |
if ((s = size) == (capacity = (elements = this.elements).length)) { |
270 |
> |
grow(1); |
271 |
> |
capacity = (elements = this.elements).length; |
272 |
> |
} |
273 |
> |
if ((h = head - 1) < 0) h = capacity - 1; |
274 |
> |
elements[head = h] = e; |
275 |
> |
size = s + 1; |
276 |
> |
// checkInvariants(); |
277 |
|
} |
278 |
|
|
279 |
|
/** |
280 |
|
* Inserts the specified element at the end of this deque. |
281 |
< |
* This method is equivalent to {@link #add} and {@link #push}. |
281 |
> |
* |
282 |
> |
* <p>This method is equivalent to {@link #add}. |
283 |
|
* |
284 |
|
* @param e the element to add |
285 |
|
* @throws NullPointerException if the specified element is null |
286 |
|
*/ |
287 |
|
public void addLast(E e) { |
288 |
< |
if (e == null) |
289 |
< |
throw new NullPointerException(); |
290 |
< |
elements[tail] = e; |
291 |
< |
if ( (tail = (tail + 1) & (elements.length - 1)) == head) |
292 |
< |
doubleCapacity(); |
288 |
> |
// checkInvariants(); |
289 |
> |
Objects.requireNonNull(e); |
290 |
> |
Object[] elements; |
291 |
> |
int capacity; |
292 |
> |
final int s; |
293 |
> |
if ((s = size) == (capacity = (elements = this.elements).length)) { |
294 |
> |
grow(1); |
295 |
> |
capacity = (elements = this.elements).length; |
296 |
> |
} |
297 |
> |
elements[add(head, s, capacity)] = e; |
298 |
> |
size = s + 1; |
299 |
> |
// checkInvariants(); |
300 |
> |
} |
301 |
> |
|
302 |
> |
/** |
303 |
> |
* Adds all of the elements in the specified collection at the end |
304 |
> |
* of this deque, as if by calling {@link #addLast} on each one, |
305 |
> |
* in the order that they are returned by the collection's |
306 |
> |
* iterator. |
307 |
> |
* |
308 |
> |
* @param c the elements to be inserted into this deque |
309 |
> |
* @return {@code true} if this deque changed as a result of the call |
310 |
> |
* @throws NullPointerException if the specified collection or any |
311 |
> |
* of its elements are null |
312 |
> |
*/ |
313 |
> |
public boolean addAll(Collection<? extends E> c) { |
314 |
> |
final int s = size, needed = c.size() - (elements.length - s); |
315 |
> |
if (needed > 0) |
316 |
> |
grow(needed); |
317 |
> |
c.forEach((e) -> addLast(e)); |
318 |
> |
// checkInvariants(); |
319 |
> |
return size > s; |
320 |
|
} |
321 |
|
|
322 |
|
/** |
323 |
|
* Inserts the specified element at the front of this deque. |
324 |
|
* |
325 |
|
* @param e the element to add |
326 |
< |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerFirst}) |
326 |
> |
* @return {@code true} (as specified by {@link Deque#offerFirst}) |
327 |
|
* @throws NullPointerException if the specified element is null |
328 |
|
*/ |
329 |
|
public boolean offerFirst(E e) { |
335 |
|
* Inserts the specified element at the end of this deque. |
336 |
|
* |
337 |
|
* @param e the element to add |
338 |
< |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerLast}) |
338 |
> |
* @return {@code true} (as specified by {@link Deque#offerLast}) |
339 |
|
* @throws NullPointerException if the specified element is null |
340 |
|
*/ |
341 |
|
public boolean offerLast(E e) { |
347 |
|
* @throws NoSuchElementException {@inheritDoc} |
348 |
|
*/ |
349 |
|
public E removeFirst() { |
350 |
< |
E x = pollFirst(); |
351 |
< |
if (x == null) |
350 |
> |
// checkInvariants(); |
351 |
> |
E e = pollFirst(); |
352 |
> |
if (e == null) |
353 |
|
throw new NoSuchElementException(); |
354 |
< |
return x; |
354 |
> |
return e; |
355 |
|
} |
356 |
|
|
357 |
|
/** |
358 |
|
* @throws NoSuchElementException {@inheritDoc} |
359 |
|
*/ |
360 |
|
public E removeLast() { |
361 |
< |
E x = pollLast(); |
362 |
< |
if (x == null) |
361 |
> |
// checkInvariants(); |
362 |
> |
E e = pollLast(); |
363 |
> |
if (e == null) |
364 |
|
throw new NoSuchElementException(); |
365 |
< |
return x; |
365 |
> |
return e; |
366 |
|
} |
367 |
|
|
368 |
|
public E pollFirst() { |
369 |
< |
int h = head; |
370 |
< |
E result = elements[h]; // Element is null if deque empty |
371 |
< |
if (result == null) |
369 |
> |
// checkInvariants(); |
370 |
> |
int s, h; |
371 |
> |
if ((s = size) <= 0) |
372 |
|
return null; |
373 |
< |
elements[h] = null; // Must null out slot |
374 |
< |
head = (h + 1) & (elements.length - 1); |
375 |
< |
return result; |
373 |
> |
final Object[] elements = this.elements; |
374 |
> |
@SuppressWarnings("unchecked") E e = (E) elements[h = head]; |
375 |
> |
elements[h] = null; |
376 |
> |
if (++h >= elements.length) h = 0; |
377 |
> |
head = h; |
378 |
> |
size = s - 1; |
379 |
> |
return e; |
380 |
|
} |
381 |
|
|
382 |
|
public E pollLast() { |
383 |
< |
int t = (tail - 1) & (elements.length - 1); |
384 |
< |
E result = elements[t]; |
385 |
< |
if (result == null) |
383 |
> |
// checkInvariants(); |
384 |
> |
final int s, tail; |
385 |
> |
if ((s = size) <= 0) |
386 |
|
return null; |
387 |
< |
elements[t] = null; |
388 |
< |
tail = t; |
389 |
< |
return result; |
387 |
> |
final Object[] elements = this.elements; |
388 |
> |
@SuppressWarnings("unchecked") |
389 |
> |
E e = (E) elements[tail = add(head, s - 1, elements.length)]; |
390 |
> |
elements[tail] = null; |
391 |
> |
size = s - 1; |
392 |
> |
return e; |
393 |
|
} |
394 |
|
|
395 |
|
/** |
396 |
|
* @throws NoSuchElementException {@inheritDoc} |
397 |
|
*/ |
398 |
|
public E getFirst() { |
399 |
< |
E x = elements[head]; |
400 |
< |
if (x == null) |
401 |
< |
throw new NoSuchElementException(); |
289 |
< |
return x; |
399 |
> |
// checkInvariants(); |
400 |
> |
if (size <= 0) throw new NoSuchElementException(); |
401 |
> |
return elementAt(head); |
402 |
|
} |
403 |
|
|
404 |
|
/** |
405 |
|
* @throws NoSuchElementException {@inheritDoc} |
406 |
|
*/ |
407 |
+ |
@SuppressWarnings("unchecked") |
408 |
|
public E getLast() { |
409 |
< |
E x = elements[(tail - 1) & (elements.length - 1)]; |
410 |
< |
if (x == null) |
411 |
< |
throw new NoSuchElementException(); |
412 |
< |
return x; |
409 |
> |
// checkInvariants(); |
410 |
> |
final int s; |
411 |
> |
if ((s = size) <= 0) throw new NoSuchElementException(); |
412 |
> |
final Object[] elements = this.elements; |
413 |
> |
return (E) elements[add(head, s - 1, elements.length)]; |
414 |
|
} |
415 |
|
|
416 |
|
public E peekFirst() { |
417 |
< |
return elements[head]; // elements[head] is null if deque empty |
417 |
> |
// checkInvariants(); |
418 |
> |
return (size <= 0) ? null : elementAt(head); |
419 |
|
} |
420 |
|
|
421 |
+ |
@SuppressWarnings("unchecked") |
422 |
|
public E peekLast() { |
423 |
< |
return elements[(tail - 1) & (elements.length - 1)]; |
423 |
> |
// checkInvariants(); |
424 |
> |
final int s; |
425 |
> |
if ((s = size) <= 0) return null; |
426 |
> |
final Object[] elements = this.elements; |
427 |
> |
return (E) elements[add(head, s - 1, elements.length)]; |
428 |
|
} |
429 |
|
|
430 |
|
/** |
431 |
|
* Removes the first occurrence of the specified element in this |
432 |
|
* deque (when traversing the deque from head to tail). |
433 |
|
* If the deque does not contain the element, it is unchanged. |
434 |
< |
* More formally, removes the first element <tt>e</tt> such that |
435 |
< |
* <tt>o.equals(e)</tt> (if such an element exists). |
436 |
< |
* Returns true if this deque contained the specified element (or |
437 |
< |
* equivalently, if this deque changed as a result of the call). |
434 |
> |
* More formally, removes the first element {@code e} such that |
435 |
> |
* {@code o.equals(e)} (if such an element exists). |
436 |
> |
* Returns {@code true} if this deque contained the specified element |
437 |
> |
* (or equivalently, if this deque changed as a result of the call). |
438 |
|
* |
439 |
|
* @param o element to be removed from this deque, if present |
440 |
< |
* @return <tt>true</tt> if the deque contained the specified element |
440 |
> |
* @return {@code true} if the deque contained the specified element |
441 |
|
*/ |
442 |
|
public boolean removeFirstOccurrence(Object o) { |
443 |
< |
if (o == null) |
444 |
< |
return false; |
445 |
< |
int mask = elements.length - 1; |
446 |
< |
int i = head; |
447 |
< |
E x; |
448 |
< |
while ( (x = elements[i]) != null) { |
449 |
< |
if (o.equals(x)) { |
450 |
< |
delete(i); |
451 |
< |
return true; |
443 |
> |
if (o != null) { |
444 |
> |
final Object[] elements = this.elements; |
445 |
> |
final int capacity = elements.length; |
446 |
> |
int i, end, to, todo; |
447 |
> |
todo = (end = (i = head) + size) |
448 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
449 |
> |
for (;; to = todo, i = 0, todo = 0) { |
450 |
> |
for (; i < to; i++) |
451 |
> |
if (o.equals(elements[i])) { |
452 |
> |
delete(i); |
453 |
> |
return true; |
454 |
> |
} |
455 |
> |
if (todo == 0) break; |
456 |
|
} |
333 |
– |
i = (i + 1) & mask; |
457 |
|
} |
458 |
|
return false; |
459 |
|
} |
462 |
|
* Removes the last occurrence of the specified element in this |
463 |
|
* deque (when traversing the deque from head to tail). |
464 |
|
* If the deque does not contain the element, it is unchanged. |
465 |
< |
* More formally, removes the last element <tt>e</tt> such that |
466 |
< |
* <tt>o.equals(e)</tt> (if such an element exists). |
467 |
< |
* Returns true if this deque contained the specified element (or |
468 |
< |
* equivalently, if this deque changed as a result of the call). |
465 |
> |
* More formally, removes the last element {@code e} such that |
466 |
> |
* {@code o.equals(e)} (if such an element exists). |
467 |
> |
* Returns {@code true} if this deque contained the specified element |
468 |
> |
* (or equivalently, if this deque changed as a result of the call). |
469 |
|
* |
470 |
|
* @param o element to be removed from this deque, if present |
471 |
< |
* @return <tt>true</tt> if the deque contained the specified element |
471 |
> |
* @return {@code true} if the deque contained the specified element |
472 |
|
*/ |
473 |
|
public boolean removeLastOccurrence(Object o) { |
474 |
< |
if (o == null) |
475 |
< |
return false; |
476 |
< |
int mask = elements.length - 1; |
477 |
< |
int i = (tail - 1) & mask; |
478 |
< |
E x; |
479 |
< |
while ( (x = elements[i]) != null) { |
480 |
< |
if (o.equals(x)) { |
481 |
< |
delete(i); |
482 |
< |
return true; |
474 |
> |
if (o != null) { |
475 |
> |
final Object[] elements = this.elements; |
476 |
> |
final int capacity = elements.length; |
477 |
> |
int i, to, end, todo; |
478 |
> |
todo = (to = ((end = (i = tail()) - size) >= -1) ? end : -1) - end; |
479 |
> |
for (;; to = (i = capacity - 1) - todo, todo = 0) { |
480 |
> |
for (; i > to; i--) |
481 |
> |
if (o.equals(elements[i])) { |
482 |
> |
delete(i); |
483 |
> |
return true; |
484 |
> |
} |
485 |
> |
if (todo == 0) break; |
486 |
|
} |
361 |
– |
i = (i - 1) & mask; |
487 |
|
} |
488 |
|
return false; |
489 |
|
} |
496 |
|
* <p>This method is equivalent to {@link #addLast}. |
497 |
|
* |
498 |
|
* @param e the element to add |
499 |
< |
* @return <tt>true</tt> (as per the spec for {@link Collection#add}) |
499 |
> |
* @return {@code true} (as specified by {@link Collection#add}) |
500 |
|
* @throws NullPointerException if the specified element is null |
501 |
|
*/ |
502 |
|
public boolean add(E e) { |
510 |
|
* <p>This method is equivalent to {@link #offerLast}. |
511 |
|
* |
512 |
|
* @param e the element to add |
513 |
< |
* @return <tt>true</tt> (as per the spec for {@link Queue#offer}) |
513 |
> |
* @return {@code true} (as specified by {@link Queue#offer}) |
514 |
|
* @throws NullPointerException if the specified element is null |
515 |
|
*/ |
516 |
|
public boolean offer(E e) { |
519 |
|
|
520 |
|
/** |
521 |
|
* Retrieves and removes the head of the queue represented by this deque. |
522 |
< |
* This method differs from {@link #poll} only in that it throws an |
522 |
> |
* |
523 |
> |
* This method differs from {@link #poll poll} only in that it throws an |
524 |
|
* exception if this deque is empty. |
525 |
|
* |
526 |
|
* <p>This method is equivalent to {@link #removeFirst}. |
535 |
|
/** |
536 |
|
* Retrieves and removes the head of the queue represented by this deque |
537 |
|
* (in other words, the first element of this deque), or returns |
538 |
< |
* <tt>null</tt> if this deque is empty. |
538 |
> |
* {@code null} if this deque is empty. |
539 |
|
* |
540 |
|
* <p>This method is equivalent to {@link #pollFirst}. |
541 |
|
* |
542 |
|
* @return the head of the queue represented by this deque, or |
543 |
< |
* <tt>null</tt> if this deque is empty |
543 |
> |
* {@code null} if this deque is empty |
544 |
|
*/ |
545 |
|
public E poll() { |
546 |
|
return pollFirst(); |
548 |
|
|
549 |
|
/** |
550 |
|
* Retrieves, but does not remove, the head of the queue represented by |
551 |
< |
* this deque. This method differs from {@link #peek} only in that it |
552 |
< |
* throws an exception if this deque is empty. |
551 |
> |
* this deque. This method differs from {@link #peek peek} only in |
552 |
> |
* that it throws an exception if this deque is empty. |
553 |
|
* |
554 |
|
* <p>This method is equivalent to {@link #getFirst}. |
555 |
|
* |
562 |
|
|
563 |
|
/** |
564 |
|
* Retrieves, but does not remove, the head of the queue represented by |
565 |
< |
* this deque, or returns <tt>null</tt> if this deque is empty. |
565 |
> |
* this deque, or returns {@code null} if this deque is empty. |
566 |
|
* |
567 |
|
* <p>This method is equivalent to {@link #peekFirst}. |
568 |
|
* |
569 |
|
* @return the head of the queue represented by this deque, or |
570 |
< |
* <tt>null</tt> if this deque is empty |
570 |
> |
* {@code null} if this deque is empty |
571 |
|
*/ |
572 |
|
public E peek() { |
573 |
|
return peekFirst(); |
603 |
|
} |
604 |
|
|
605 |
|
/** |
606 |
< |
* Removes the element at the specified position in the elements array, |
607 |
< |
* adjusting head and tail as necessary. This can result in motion of |
608 |
< |
* elements backwards or forwards in the array. |
606 |
> |
* Removes the element at the specified position in the elements array. |
607 |
> |
* This can result in forward or backwards motion of array elements. |
608 |
> |
* We optimize for least element motion. |
609 |
|
* |
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 |
614 |
|
*/ |
615 |
< |
private boolean delete(int i) { |
616 |
< |
int mask = elements.length - 1; |
617 |
< |
|
618 |
< |
// Invariant: head <= i < tail mod circularity |
619 |
< |
if (((i - head) & mask) >= ((tail - head) & mask)) |
620 |
< |
throw new ConcurrentModificationException(); |
621 |
< |
|
622 |
< |
// Case 1: Deque doesn't wrap |
623 |
< |
// Case 2: Deque does wrap and removed element is in the head portion |
624 |
< |
if (i >= head) { |
625 |
< |
System.arraycopy(elements, head, elements, head + 1, i - head); |
626 |
< |
elements[head] = null; |
627 |
< |
head = (head + 1) & mask; |
615 |
> |
boolean delete(int i) { |
616 |
> |
// checkInvariants(); |
617 |
> |
final Object[] elements = this.elements; |
618 |
> |
final int capacity = elements.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 |
623 |
> |
if (front < back) { |
624 |
> |
// move front elements forwards |
625 |
> |
if (h <= i) { |
626 |
> |
System.arraycopy(elements, h, elements, 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)); |
631 |
> |
} |
632 |
> |
elements[h] = null; |
633 |
> |
if ((head = (h + 1)) >= capacity) head = 0; |
634 |
> |
size--; |
635 |
> |
// checkInvariants(); |
636 |
|
return false; |
637 |
+ |
} else { |
638 |
+ |
// move back elements backwards |
639 |
+ |
int tail = tail(); |
640 |
+ |
if (i <= tail) { |
641 |
+ |
System.arraycopy(elements, i + 1, elements, i, back); |
642 |
+ |
} else { // Wrap around |
643 |
+ |
int firstLeg = capacity - (i + 1); |
644 |
+ |
System.arraycopy(elements, i + 1, elements, i, firstLeg); |
645 |
+ |
elements[capacity - 1] = elements[0]; |
646 |
+ |
System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1); |
647 |
+ |
} |
648 |
+ |
elements[tail] = null; |
649 |
+ |
size--; |
650 |
+ |
// checkInvariants(); |
651 |
+ |
return true; |
652 |
|
} |
504 |
– |
|
505 |
– |
// Case 3: Deque wraps and removed element is in the tail portion |
506 |
– |
tail--; |
507 |
– |
System.arraycopy(elements, i + 1, elements, i, tail - i); |
508 |
– |
elements[tail] = null; |
509 |
– |
return true; |
653 |
|
} |
654 |
|
|
655 |
|
// *** Collection Methods *** |
660 |
|
* @return the number of elements in this deque |
661 |
|
*/ |
662 |
|
public int size() { |
663 |
< |
return (tail - head) & (elements.length - 1); |
663 |
> |
return size; |
664 |
|
} |
665 |
|
|
666 |
|
/** |
667 |
< |
* Returns <tt>true</tt> if this deque contains no elements. |
667 |
> |
* Returns {@code true} if this deque contains no elements. |
668 |
|
* |
669 |
< |
* @return <tt>true</tt> if this deque contains no elements |
669 |
> |
* @return {@code true} if this deque contains no elements |
670 |
|
*/ |
671 |
|
public boolean isEmpty() { |
672 |
< |
return head == tail; |
672 |
> |
return size == 0; |
673 |
|
} |
674 |
|
|
675 |
|
/** |
678 |
|
* order that elements would be dequeued (via successive calls to |
679 |
|
* {@link #remove} or popped (via successive calls to {@link #pop}). |
680 |
|
* |
681 |
< |
* @return an <tt>Iterator</tt> over the elements in this deque |
681 |
> |
* @return an iterator over the elements in this deque |
682 |
|
*/ |
683 |
|
public Iterator<E> iterator() { |
684 |
|
return new DeqIterator(); |
685 |
|
} |
686 |
|
|
687 |
+ |
public Iterator<E> descendingIterator() { |
688 |
+ |
return new DescendingIterator(); |
689 |
+ |
} |
690 |
+ |
|
691 |
|
private class DeqIterator implements Iterator<E> { |
692 |
< |
/** |
693 |
< |
* Index of element to be returned by subsequent call to next. |
547 |
< |
*/ |
548 |
< |
private int cursor = head; |
692 |
> |
/** Index of element to be returned by subsequent call to next. */ |
693 |
> |
int cursor; |
694 |
|
|
695 |
< |
/** |
696 |
< |
* Tail recorded at construction (also in remove), to stop |
552 |
< |
* iterator and also to check for comodification. |
553 |
< |
*/ |
554 |
< |
private int fence = tail; |
695 |
> |
/** Number of elements yet to be returned. */ |
696 |
> |
int remaining = size; |
697 |
|
|
698 |
|
/** |
699 |
|
* Index of element returned by most recent call to next. |
700 |
|
* Reset to -1 if element is deleted by a call to remove. |
701 |
|
*/ |
702 |
< |
private int lastRet = -1; |
702 |
> |
int lastRet = -1; |
703 |
> |
|
704 |
> |
DeqIterator() { cursor = head; } |
705 |
|
|
706 |
< |
public boolean hasNext() { |
707 |
< |
return cursor != fence; |
706 |
> |
public final boolean hasNext() { |
707 |
> |
return remaining > 0; |
708 |
|
} |
709 |
|
|
710 |
|
public E next() { |
711 |
< |
E result; |
568 |
< |
if (cursor == fence) |
711 |
> |
if (remaining <= 0) |
712 |
|
throw new NoSuchElementException(); |
713 |
< |
// This check doesn't catch all possible comodifications, |
714 |
< |
// but does catch the ones that corrupt traversal |
572 |
< |
if (tail != fence || (result = elements[cursor]) == null) |
573 |
< |
throw new ConcurrentModificationException(); |
713 |
> |
final Object[] elements = ArrayDeque.this.elements; |
714 |
> |
E e = nonNullElementAt(elements, cursor); |
715 |
|
lastRet = cursor; |
716 |
< |
cursor = (cursor + 1) & (elements.length - 1); |
717 |
< |
return result; |
716 |
> |
if (++cursor >= elements.length) cursor = 0; |
717 |
> |
remaining--; |
718 |
> |
return e; |
719 |
> |
} |
720 |
> |
|
721 |
> |
void postDelete(boolean leftShifted) { |
722 |
> |
if (leftShifted) |
723 |
> |
if (--cursor < 0) cursor = elements.length - 1; |
724 |
|
} |
725 |
|
|
726 |
< |
public void remove() { |
726 |
> |
public final void remove() { |
727 |
|
if (lastRet < 0) |
728 |
|
throw new IllegalStateException(); |
729 |
< |
if (delete(lastRet)) |
583 |
< |
cursor--; |
729 |
> |
postDelete(delete(lastRet)); |
730 |
|
lastRet = -1; |
731 |
< |
fence = tail; |
731 |
> |
} |
732 |
> |
|
733 |
> |
public void forEachRemaining(Consumer<? super E> action) { |
734 |
> |
final int k; |
735 |
> |
if ((k = remaining) > 0) { |
736 |
> |
remaining = 0; |
737 |
> |
ArrayDeque.forEachRemaining(action, elements, cursor, k); |
738 |
> |
if ((lastRet = cursor + k - 1) >= elements.length) |
739 |
> |
lastRet -= elements.length; |
740 |
> |
} |
741 |
> |
} |
742 |
> |
} |
743 |
> |
|
744 |
> |
private class DescendingIterator extends DeqIterator { |
745 |
> |
DescendingIterator() { cursor = tail(); } |
746 |
> |
|
747 |
> |
public final E next() { |
748 |
> |
if (remaining <= 0) |
749 |
> |
throw new NoSuchElementException(); |
750 |
> |
final Object[] elements = ArrayDeque.this.elements; |
751 |
> |
E e = nonNullElementAt(elements, cursor); |
752 |
> |
lastRet = cursor; |
753 |
> |
if (--cursor < 0) cursor = elements.length - 1; |
754 |
> |
remaining--; |
755 |
> |
return e; |
756 |
> |
} |
757 |
> |
|
758 |
> |
void postDelete(boolean leftShifted) { |
759 |
> |
if (!leftShifted) |
760 |
> |
if (++cursor >= elements.length) cursor = 0; |
761 |
> |
} |
762 |
> |
|
763 |
> |
public final void forEachRemaining(Consumer<? super E> action) { |
764 |
> |
final int k; |
765 |
> |
if ((k = remaining) > 0) { |
766 |
> |
remaining = 0; |
767 |
> |
forEachRemainingDescending(action, elements, cursor, k); |
768 |
> |
if ((lastRet = cursor - (k - 1)) < 0) |
769 |
> |
lastRet += elements.length; |
770 |
> |
} |
771 |
|
} |
772 |
|
} |
773 |
|
|
774 |
|
/** |
775 |
< |
* Returns <tt>true</tt> if this deque contains the specified element. |
776 |
< |
* More formally, returns <tt>true</tt> if and only if this deque contains |
777 |
< |
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. |
775 |
> |
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> |
776 |
> |
* and <em>fail-fast</em> {@link Spliterator} over the elements in this |
777 |
> |
* deque. |
778 |
> |
* |
779 |
> |
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, |
780 |
> |
* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and |
781 |
> |
* {@link Spliterator#NONNULL}. Overriding implementations should document |
782 |
> |
* the reporting of additional characteristic values. |
783 |
> |
* |
784 |
> |
* @return a {@code Spliterator} over the elements in this deque |
785 |
> |
* @since 1.8 |
786 |
> |
*/ |
787 |
> |
public Spliterator<E> spliterator() { |
788 |
> |
return new ArrayDequeSpliterator(); |
789 |
> |
} |
790 |
> |
|
791 |
> |
final class ArrayDequeSpliterator implements Spliterator<E> { |
792 |
> |
private int cursor; |
793 |
> |
private int remaining; // -1 until late-binding first use |
794 |
> |
|
795 |
> |
/** Constructs late-binding spliterator over all elements. */ |
796 |
> |
ArrayDequeSpliterator() { |
797 |
> |
this.remaining = -1; |
798 |
> |
} |
799 |
> |
|
800 |
> |
/** Constructs spliterator over the given slice. */ |
801 |
> |
ArrayDequeSpliterator(int cursor, int count) { |
802 |
> |
this.cursor = cursor; |
803 |
> |
this.remaining = count; |
804 |
> |
} |
805 |
> |
|
806 |
> |
/** Ensures late-binding initialization; then returns remaining. */ |
807 |
> |
private int remaining() { |
808 |
> |
if (remaining < 0) { |
809 |
> |
cursor = head; |
810 |
> |
remaining = size; |
811 |
> |
} |
812 |
> |
return remaining; |
813 |
> |
} |
814 |
> |
|
815 |
> |
public ArrayDequeSpliterator trySplit() { |
816 |
> |
final int mid; |
817 |
> |
if ((mid = remaining() >> 1) > 0) { |
818 |
> |
int oldCursor = cursor; |
819 |
> |
cursor = add(cursor, mid, elements.length); |
820 |
> |
remaining -= mid; |
821 |
> |
return new ArrayDequeSpliterator(oldCursor, mid); |
822 |
> |
} |
823 |
> |
return null; |
824 |
> |
} |
825 |
> |
|
826 |
> |
public void forEachRemaining(Consumer<? super E> action) { |
827 |
> |
final int k = remaining(); // side effect! |
828 |
> |
remaining = 0; |
829 |
> |
ArrayDeque.forEachRemaining(action, elements, cursor, k); |
830 |
> |
} |
831 |
> |
|
832 |
> |
public boolean tryAdvance(Consumer<? super E> action) { |
833 |
> |
Objects.requireNonNull(action); |
834 |
> |
final int k; |
835 |
> |
if ((k = remaining()) <= 0) |
836 |
> |
return false; |
837 |
> |
action.accept(nonNullElementAt(elements, cursor)); |
838 |
> |
if (++cursor >= elements.length) cursor = 0; |
839 |
> |
remaining = k - 1; |
840 |
> |
return true; |
841 |
> |
} |
842 |
> |
|
843 |
> |
public long estimateSize() { |
844 |
> |
return remaining(); |
845 |
> |
} |
846 |
> |
|
847 |
> |
public int characteristics() { |
848 |
> |
return Spliterator.NONNULL |
849 |
> |
| Spliterator.ORDERED |
850 |
> |
| Spliterator.SIZED |
851 |
> |
| Spliterator.SUBSIZED; |
852 |
> |
} |
853 |
> |
} |
854 |
> |
|
855 |
> |
@SuppressWarnings("unchecked") |
856 |
> |
public void forEach(Consumer<? super E> action) { |
857 |
> |
Objects.requireNonNull(action); |
858 |
> |
final Object[] elements = this.elements; |
859 |
> |
final int capacity = elements.length; |
860 |
> |
int i, end, to, todo; |
861 |
> |
todo = (end = (i = head) + size) |
862 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
863 |
> |
for (;; to = todo, i = 0, todo = 0) { |
864 |
> |
for (; i < to; i++) |
865 |
> |
action.accept((E) elements[i]); |
866 |
> |
if (todo == 0) break; |
867 |
> |
} |
868 |
> |
// checkInvariants(); |
869 |
> |
} |
870 |
> |
|
871 |
> |
/** |
872 |
> |
* Calls action on remaining elements, starting at index i and |
873 |
> |
* traversing in ascending order. A variant of forEach that also |
874 |
> |
* checks for concurrent modification, for use in iterators. |
875 |
> |
*/ |
876 |
> |
static <E> void forEachRemaining( |
877 |
> |
Consumer<? super E> action, Object[] elements, int i, int remaining) { |
878 |
> |
Objects.requireNonNull(action); |
879 |
> |
final int capacity = elements.length; |
880 |
> |
int end, to, todo; |
881 |
> |
todo = (end = i + remaining) |
882 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
883 |
> |
for (;; to = todo, i = 0, todo = 0) { |
884 |
> |
for (; i < to; i++) |
885 |
> |
action.accept(nonNullElementAt(elements, i)); |
886 |
> |
if (todo == 0) break; |
887 |
> |
} |
888 |
> |
} |
889 |
> |
|
890 |
> |
static <E> void forEachRemainingDescending( |
891 |
> |
Consumer<? super E> action, Object[] elements, int i, int remaining) { |
892 |
> |
Objects.requireNonNull(action); |
893 |
> |
final int capacity = elements.length; |
894 |
> |
int end, to, todo; |
895 |
> |
todo = (to = ((end = i - remaining) >= -1) ? end : -1) - end; |
896 |
> |
for (;; to = (i = capacity - 1) - todo, todo = 0) { |
897 |
> |
for (; i > to; i--) |
898 |
> |
action.accept(nonNullElementAt(elements, i)); |
899 |
> |
if (todo == 0) break; |
900 |
> |
} |
901 |
> |
} |
902 |
> |
|
903 |
> |
/** |
904 |
> |
* Replaces each element of this deque with the result of applying the |
905 |
> |
* operator to that element, as specified by {@link List#replaceAll}. |
906 |
> |
* |
907 |
> |
* @param operator the operator to apply to each element |
908 |
> |
* @since TBD |
909 |
> |
*/ |
910 |
> |
/* public */ void replaceAll(UnaryOperator<E> operator) { |
911 |
> |
Objects.requireNonNull(operator); |
912 |
> |
final Object[] elements = this.elements; |
913 |
> |
final int capacity = elements.length; |
914 |
> |
int i, end, to, todo; |
915 |
> |
todo = (end = (i = head) + size) |
916 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
917 |
> |
for (;; to = todo, i = 0, todo = 0) { |
918 |
> |
for (; i < to; i++) |
919 |
> |
elements[i] = operator.apply(elementAt(i)); |
920 |
> |
if (todo == 0) break; |
921 |
> |
} |
922 |
> |
// checkInvariants(); |
923 |
> |
} |
924 |
> |
|
925 |
> |
/** |
926 |
> |
* @throws NullPointerException {@inheritDoc} |
927 |
> |
*/ |
928 |
> |
public boolean removeIf(Predicate<? super E> filter) { |
929 |
> |
Objects.requireNonNull(filter); |
930 |
> |
return bulkRemove(filter); |
931 |
> |
} |
932 |
> |
|
933 |
> |
/** |
934 |
> |
* @throws NullPointerException {@inheritDoc} |
935 |
> |
*/ |
936 |
> |
public boolean removeAll(Collection<?> c) { |
937 |
> |
Objects.requireNonNull(c); |
938 |
> |
return bulkRemove(e -> c.contains(e)); |
939 |
> |
} |
940 |
> |
|
941 |
> |
/** |
942 |
> |
* @throws NullPointerException {@inheritDoc} |
943 |
> |
*/ |
944 |
> |
public boolean retainAll(Collection<?> c) { |
945 |
> |
Objects.requireNonNull(c); |
946 |
> |
return bulkRemove(e -> !c.contains(e)); |
947 |
> |
} |
948 |
> |
|
949 |
> |
/** Implementation of bulk remove methods. */ |
950 |
> |
private boolean bulkRemove(Predicate<? super E> filter) { |
951 |
> |
// checkInvariants(); |
952 |
> |
final Object[] elements = this.elements; |
953 |
> |
final int capacity = elements.length; |
954 |
> |
int i = head, j = i, remaining = size, deleted = 0; |
955 |
> |
try { |
956 |
> |
for (; remaining > 0; remaining--) { |
957 |
> |
@SuppressWarnings("unchecked") E e = (E) elements[i]; |
958 |
> |
if (filter.test(e)) |
959 |
> |
deleted++; |
960 |
> |
else { |
961 |
> |
if (j != i) |
962 |
> |
elements[j] = e; |
963 |
> |
if (++j >= capacity) j = 0; |
964 |
> |
} |
965 |
> |
if (++i >= capacity) i = 0; |
966 |
> |
} |
967 |
> |
return deleted > 0; |
968 |
> |
} catch (Throwable ex) { |
969 |
> |
if (deleted > 0) |
970 |
> |
for (; remaining > 0; remaining--) { |
971 |
> |
elements[j] = elements[i]; |
972 |
> |
if (++i >= capacity) i = 0; |
973 |
> |
if (++j >= capacity) j = 0; |
974 |
> |
} |
975 |
> |
throw ex; |
976 |
> |
} finally { |
977 |
> |
size -= deleted; |
978 |
> |
clearSlice(elements, j, deleted); |
979 |
> |
// checkInvariants(); |
980 |
> |
} |
981 |
> |
} |
982 |
> |
|
983 |
> |
/** |
984 |
> |
* Returns {@code true} if this deque contains the specified element. |
985 |
> |
* More formally, returns {@code true} if and only if this deque contains |
986 |
> |
* at least one element {@code e} such that {@code o.equals(e)}. |
987 |
|
* |
988 |
|
* @param o object to be checked for containment in this deque |
989 |
< |
* @return <tt>true</tt> if this deque contains the specified element |
989 |
> |
* @return {@code true} if this deque contains the specified element |
990 |
|
*/ |
991 |
|
public boolean contains(Object o) { |
992 |
< |
if (o == null) |
993 |
< |
return false; |
994 |
< |
int mask = elements.length - 1; |
995 |
< |
int i = head; |
996 |
< |
E x; |
997 |
< |
while ( (x = elements[i]) != null) { |
998 |
< |
if (o.equals(x)) |
999 |
< |
return true; |
1000 |
< |
i = (i + 1) & mask; |
992 |
> |
if (o != null) { |
993 |
> |
final Object[] elements = this.elements; |
994 |
> |
final int capacity = elements.length; |
995 |
> |
int i, end, to, todo; |
996 |
> |
todo = (end = (i = head) + size) |
997 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
998 |
> |
for (;; to = todo, i = 0, todo = 0) { |
999 |
> |
for (; i < to; i++) |
1000 |
> |
if (o.equals(elements[i])) |
1001 |
> |
return true; |
1002 |
> |
if (todo == 0) break; |
1003 |
> |
} |
1004 |
|
} |
1005 |
|
return false; |
1006 |
|
} |
1008 |
|
/** |
1009 |
|
* Removes a single instance of the specified element from this deque. |
1010 |
|
* If the deque does not contain the element, it is unchanged. |
1011 |
< |
* More formally, removes the first element <tt>e</tt> such that |
1012 |
< |
* <tt>o.equals(e)</tt> (if such an element exists). |
1013 |
< |
* Returns true if this deque contained the specified element (or |
1014 |
< |
* equivalently, if this deque changed as a result of the call). |
1011 |
> |
* More formally, removes the first element {@code e} such that |
1012 |
> |
* {@code o.equals(e)} (if such an element exists). |
1013 |
> |
* Returns {@code true} if this deque contained the specified element |
1014 |
> |
* (or equivalently, if this deque changed as a result of the call). |
1015 |
|
* |
1016 |
< |
* <p>This method is equivalent to {@link #removeFirstOccurrence}. |
1016 |
> |
* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}. |
1017 |
|
* |
1018 |
|
* @param o element to be removed from this deque, if present |
1019 |
< |
* @return <tt>true</tt> if this deque contained the specified element |
1019 |
> |
* @return {@code true} if this deque contained the specified element |
1020 |
|
*/ |
1021 |
|
public boolean remove(Object o) { |
1022 |
|
return removeFirstOccurrence(o); |
1027 |
|
* The deque will be empty after this call returns. |
1028 |
|
*/ |
1029 |
|
public void clear() { |
1030 |
< |
int h = head; |
1031 |
< |
int t = tail; |
1032 |
< |
if (h != t) { // clear all cells |
1033 |
< |
head = tail = 0; |
1034 |
< |
int i = h; |
1035 |
< |
int mask = elements.length - 1; |
1036 |
< |
do { |
1037 |
< |
elements[i] = null; |
1038 |
< |
i = (i + 1) & mask; |
1039 |
< |
} while (i != t); |
1040 |
< |
} |
1030 |
> |
clearSlice(elements, head, size); |
1031 |
> |
size = head = 0; |
1032 |
> |
// checkInvariants(); |
1033 |
> |
} |
1034 |
> |
|
1035 |
> |
/** |
1036 |
> |
* Nulls out count elements, starting at array index from. |
1037 |
> |
*/ |
1038 |
> |
private static void clearSlice(Object[] elements, int from, int count) { |
1039 |
> |
final int capacity = elements.length, end = from + count; |
1040 |
> |
final int leg = (capacity - end >= 0) ? end : capacity; |
1041 |
> |
Arrays.fill(elements, from, leg, null); |
1042 |
> |
if (leg != end) |
1043 |
> |
Arrays.fill(elements, 0, end - capacity, null); |
1044 |
|
} |
1045 |
|
|
1046 |
|
/** |
1050 |
|
* <p>The returned array will be "safe" in that no references to it are |
1051 |
|
* maintained by this deque. (In other words, this method must allocate |
1052 |
|
* a new array). The caller is thus free to modify the returned array. |
1053 |
< |
* |
1053 |
> |
* |
1054 |
|
* <p>This method acts as bridge between array-based and collection-based |
1055 |
|
* APIs. |
1056 |
|
* |
1057 |
|
* @return an array containing all of the elements in this deque |
1058 |
|
*/ |
1059 |
|
public Object[] toArray() { |
1060 |
< |
return copyElements(new Object[size()]); |
1060 |
> |
return toArray(Object[].class); |
1061 |
> |
} |
1062 |
> |
|
1063 |
> |
private <T> T[] toArray(Class<T[]> klazz) { |
1064 |
> |
final Object[] elements = this.elements; |
1065 |
> |
final int capacity = elements.length; |
1066 |
> |
final int head = this.head, end = head + size; |
1067 |
> |
final T[] a; |
1068 |
> |
if (end >= 0) { |
1069 |
> |
a = Arrays.copyOfRange(elements, head, end, klazz); |
1070 |
> |
} else { |
1071 |
> |
// integer overflow! |
1072 |
> |
a = Arrays.copyOfRange(elements, 0, size, klazz); |
1073 |
> |
System.arraycopy(elements, head, a, 0, capacity - head); |
1074 |
> |
} |
1075 |
> |
if (end - capacity > 0) |
1076 |
> |
System.arraycopy(elements, 0, a, capacity - head, end - capacity); |
1077 |
> |
return a; |
1078 |
|
} |
1079 |
|
|
1080 |
|
/** |
1088 |
|
* <p>If this deque fits in the specified array with room to spare |
1089 |
|
* (i.e., the array has more elements than this deque), the element in |
1090 |
|
* the array immediately following the end of the deque is set to |
1091 |
< |
* <tt>null</tt>. |
1091 |
> |
* {@code null}. |
1092 |
|
* |
1093 |
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
1094 |
|
* array-based and collection-based APIs. Further, this method allows |
1095 |
|
* precise control over the runtime type of the output array, and may, |
1096 |
|
* under certain circumstances, be used to save allocation costs. |
1097 |
|
* |
1098 |
< |
* <p>Suppose <tt>x</tt> is a deque known to contain only strings. |
1098 |
> |
* <p>Suppose {@code x} is a deque known to contain only strings. |
1099 |
|
* The following code can be used to dump the deque into a newly |
1100 |
< |
* allocated array of <tt>String</tt>: |
1100 |
> |
* allocated array of {@code String}: |
1101 |
|
* |
1102 |
< |
* <pre> |
686 |
< |
* String[] y = x.toArray(new String[0]);</pre> |
1102 |
> |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
1103 |
|
* |
1104 |
< |
* Note that <tt>toArray(new Object[0])</tt> is identical in function to |
1105 |
< |
* <tt>toArray()</tt>. |
1104 |
> |
* Note that {@code toArray(new Object[0])} is identical in function to |
1105 |
> |
* {@code toArray()}. |
1106 |
|
* |
1107 |
|
* @param a the array into which the elements of the deque are to |
1108 |
|
* be stored, if it is big enough; otherwise, a new array of the |
1113 |
|
* this deque |
1114 |
|
* @throws NullPointerException if the specified array is null |
1115 |
|
*/ |
1116 |
+ |
@SuppressWarnings("unchecked") |
1117 |
|
public <T> T[] toArray(T[] a) { |
1118 |
< |
int size = size(); |
1119 |
< |
if (a.length < size) |
1120 |
< |
a = (T[])java.lang.reflect.Array.newInstance( |
1121 |
< |
a.getClass().getComponentType(), size); |
1122 |
< |
copyElements(a); |
1123 |
< |
if (a.length > size) |
1118 |
> |
final int size = this.size; |
1119 |
> |
if (size > a.length) |
1120 |
> |
return toArray((Class<T[]>) a.getClass()); |
1121 |
> |
final Object[] elements = this.elements; |
1122 |
> |
final int capacity = elements.length; |
1123 |
> |
final int head = this.head, end = head + size; |
1124 |
> |
final int front = (capacity - end >= 0) ? size : capacity - head; |
1125 |
> |
System.arraycopy(elements, head, a, 0, front); |
1126 |
> |
if (front != size) |
1127 |
> |
System.arraycopy(elements, 0, a, capacity - head, end - capacity); |
1128 |
> |
if (size < a.length) |
1129 |
|
a[size] = null; |
1130 |
|
return a; |
1131 |
|
} |
1139 |
|
*/ |
1140 |
|
public ArrayDeque<E> clone() { |
1141 |
|
try { |
1142 |
+ |
@SuppressWarnings("unchecked") |
1143 |
|
ArrayDeque<E> result = (ArrayDeque<E>) super.clone(); |
1144 |
< |
// These two lines are currently faster than cloning the array: |
722 |
< |
result.elements = (E[]) new Object[elements.length]; |
723 |
< |
System.arraycopy(elements, 0, result.elements, 0, elements.length); |
1144 |
> |
result.elements = Arrays.copyOf(elements, elements.length); |
1145 |
|
return result; |
725 |
– |
|
1146 |
|
} catch (CloneNotSupportedException e) { |
1147 |
|
throw new AssertionError(); |
1148 |
|
} |
1149 |
|
} |
1150 |
|
|
731 |
– |
/** |
732 |
– |
* Appease the serialization gods. |
733 |
– |
*/ |
1151 |
|
private static final long serialVersionUID = 2340985798034038923L; |
1152 |
|
|
1153 |
|
/** |
1154 |
< |
* Serialize this deque. |
1154 |
> |
* Saves this deque to a stream (that is, serializes it). |
1155 |
|
* |
1156 |
< |
* @serialData The current size (<tt>int</tt>) of the deque, |
1156 |
> |
* @param s the stream |
1157 |
> |
* @throws java.io.IOException if an I/O error occurs |
1158 |
> |
* @serialData The current size ({@code int}) of the deque, |
1159 |
|
* followed by all of its elements (each an object reference) in |
1160 |
|
* first-to-last order. |
1161 |
|
*/ |
1162 |
< |
private void writeObject(ObjectOutputStream s) throws IOException { |
1162 |
> |
private void writeObject(java.io.ObjectOutputStream s) |
1163 |
> |
throws java.io.IOException { |
1164 |
|
s.defaultWriteObject(); |
1165 |
|
|
1166 |
|
// Write out size |
747 |
– |
int size = size(); |
1167 |
|
s.writeInt(size); |
1168 |
|
|
1169 |
|
// Write out elements in order. |
1170 |
< |
int i = head; |
1171 |
< |
int mask = elements.length - 1; |
1172 |
< |
for (int j = 0; j < size; j++) { |
1173 |
< |
s.writeObject(elements[i]); |
1174 |
< |
i = (i + 1) & mask; |
1170 |
> |
final Object[] elements = this.elements; |
1171 |
> |
final int capacity = elements.length; |
1172 |
> |
int i, end, to, todo; |
1173 |
> |
todo = (end = (i = head) + size) |
1174 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
1175 |
> |
for (;; to = todo, i = 0, todo = 0) { |
1176 |
> |
for (; i < to; i++) |
1177 |
> |
s.writeObject(elements[i]); |
1178 |
> |
if (todo == 0) break; |
1179 |
|
} |
1180 |
|
} |
1181 |
|
|
1182 |
|
/** |
1183 |
< |
* Deserialize this deque. |
1183 |
> |
* Reconstitutes this deque from a stream (that is, deserializes it). |
1184 |
> |
* @param s the stream |
1185 |
> |
* @throws ClassNotFoundException if the class of a serialized object |
1186 |
> |
* could not be found |
1187 |
> |
* @throws java.io.IOException if an I/O error occurs |
1188 |
|
*/ |
1189 |
< |
private void readObject(ObjectInputStream s) |
1190 |
< |
throws IOException, ClassNotFoundException { |
1189 |
> |
private void readObject(java.io.ObjectInputStream s) |
1190 |
> |
throws java.io.IOException, ClassNotFoundException { |
1191 |
|
s.defaultReadObject(); |
1192 |
|
|
1193 |
|
// Read in size and allocate array |
1194 |
< |
int size = s.readInt(); |
768 |
< |
allocateElements(size); |
769 |
< |
head = 0; |
770 |
< |
tail = size; |
1194 |
> |
elements = new Object[size = s.readInt()]; |
1195 |
|
|
1196 |
|
// Read in all elements in the proper order. |
1197 |
|
for (int i = 0; i < size; i++) |
1198 |
< |
elements[i] = (E)s.readObject(); |
1198 |
> |
elements[i] = s.readObject(); |
1199 |
> |
} |
1200 |
|
|
1201 |
+ |
/** debugging */ |
1202 |
+ |
void checkInvariants() { |
1203 |
+ |
try { |
1204 |
+ |
int capacity = elements.length; |
1205 |
+ |
// assert size >= 0 && size <= capacity; |
1206 |
+ |
// assert head >= 0; |
1207 |
+ |
// assert capacity == 0 || head < capacity; |
1208 |
+ |
// assert size == 0 || elements[head] != null; |
1209 |
+ |
// assert size == 0 || elements[tail()] != null; |
1210 |
+ |
// assert size == capacity || elements[dec(head, capacity)] == null; |
1211 |
+ |
// assert size == capacity || elements[inc(tail(), capacity)] == null; |
1212 |
+ |
} catch (Throwable t) { |
1213 |
+ |
System.err.printf("head=%d size=%d capacity=%d%n", |
1214 |
+ |
head, size, elements.length); |
1215 |
+ |
System.err.printf("elements=%s%n", |
1216 |
+ |
Arrays.toString(elements)); |
1217 |
+ |
throw t; |
1218 |
+ |
} |
1219 |
|
} |
1220 |
+ |
|
1221 |
|
} |