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Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.65 by jsr166, Sat Feb 28 20:35:47 2015 UTC vs.
Revision 1.85 by jsr166, Sun Oct 23 19:30:54 2016 UTC

#	Line 7 | Line 7 | package java.util;
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
#	Line 52 | Line 54 | import java.util.function.Consumer;
54		* Java Collections Framework</a>.
55		*
56		* @author  Josh Bloch and Doug Lea
55	–	* @since   1.6
57		* @param <E> the type of elements held in this deque
58	+	* @since   1.6
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
65	<	* full, except transiently within an addX method where it is
66	<	* resized (see doubleCapacity) immediately upon becoming full,
67	<	* thus avoiding head and tail wrapping around to equal each
68	<	* other.  We also guarantee that all array cells not holding
69	<	* deque elements are always null.
65	>	* We guarantee that all array cells not holding deque elements
66	>	* are always null.
67		*/
68	<	transient Object[] elements; // non-private to simplify nested class access
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		transient int head;
76
77	+	/** Number of elements in this collection. */
78	+	transient int size;
79	+
80		/**
81	<	* The index at which the next element would be added to the tail
82	<	* of the deque (via addLast(E), add(E), or push(E)).
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	<	transient int tail;
86	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
87
88		/**
89	<	* The minimum capacity that we'll use for a newly created deque.
90	<	* Must be a power of 2.
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 static final int MIN_INITIAL_CAPACITY = 8;
93	>	private void grow(int needed) {
94	>	// overflow-conscious code
95	>	// checkInvariants();
96	>	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	<	// ******  Array allocation and resizing utilities ******
116	>	/** Capacity calculation for edge conditions, especially overflow. */
117	>	private int newCapacity(int needed, int jump) {
118	>	int oldCapacity = elements.length;
119	>	int minCapacity;
120	>	if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
121	>	if (minCapacity < 0)
122	>	throw new IllegalStateException("Sorry, deque too big");
123	>	return Integer.MAX_VALUE;
124	>	}
125	>	if (needed > jump)
126	>	return minCapacity;
127	>	return (oldCapacity + jump - MAX_ARRAY_SIZE < 0)
128	>	? oldCapacity + jump
129	>	: MAX_ARRAY_SIZE;
130	>	}
131
132		/**
133	<	* Allocates empty array to hold the given number of elements.
133	>	* Increases the internal storage of this collection, if necessary,
134	>	* to ensure that it can hold at least the given number of elements.
135		*
136	<	* @param numElements  the number of elements to hold
136	>	* @param minCapacity the desired minimum capacity
137	>	* @since TBD
138		*/
139	<	private void allocateElements(int numElements) {
140	<	int initialCapacity = MIN_INITIAL_CAPACITY;
141	<	// Find the best power of two to hold elements.
142	<	// Tests "<=" because arrays aren't kept full.
103	<	if (numElements >= initialCapacity) {
104	<	initialCapacity = numElements;
105	<	initialCapacity |= (initialCapacity >>>  1);
106	<	initialCapacity |= (initialCapacity >>>  2);
107	<	initialCapacity |= (initialCapacity >>>  4);
108	<	initialCapacity |= (initialCapacity >>>  8);
109	<	initialCapacity |= (initialCapacity >>> 16);
110	<	initialCapacity++;
111	<
112	<	if (initialCapacity < 0)   // Too many elements, must back off
113	<	initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements
114	<	}
115	<	elements = new Object[initialCapacity];
139	>	/* public */ void ensureCapacity(int minCapacity) {
140	>	if (minCapacity > elements.length)
141	>	grow(minCapacity - elements.length);
142	>	// checkInvariants();
143		}
144
145		/**
146	<	* Doubles the capacity of this deque.  Call only when full, i.e.,
147	<	* when head and tail have wrapped around to become equal.
146	>	* Minimizes the internal storage of this collection.
147	>	*
148	>	* @since TBD
149		*/
150	<	private void doubleCapacity() {
151	<	assert head == tail;
152	<	int p = head;
153	<	int n = elements.length;
154	<	int r = n - p; // number of elements to the right of p
155	<	int newCapacity = n << 1;
128	<	if (newCapacity < 0)
129	<	throw new IllegalStateException("Sorry, deque too big");
130	<	Object[] a = new Object[newCapacity];
131	<	System.arraycopy(elements, p, a, 0, r);
132	<	System.arraycopy(elements, 0, a, r, p);
133	<	elements = a;
134	<	head = 0;
135	<	tail = n;
150	>	/* public */ void trimToSize() {
151	>	if (size < elements.length) {
152	>	elements = toArray();
153	>	head = 0;
154	>	}
155	>	// checkInvariants();
156		}
157
158		/**
#	Line 147 | Line 167 | public class ArrayDeque<E> extends Abstr
167		* Constructs an empty array deque with an initial capacity
168		* sufficient to hold the specified number of elements.
169		*
170	<	* @param numElements  lower bound on initial capacity of the deque
170	>	* @param numElements lower bound on initial capacity of the deque
171		*/
172		public ArrayDeque(int numElements) {
173	<	allocateElements(numElements);
173	>	elements = new Object[numElements];
174		}
175
176		/**
#	Line 164 | Line 184 | public class ArrayDeque<E> extends Abstr
184		* @throws NullPointerException if the specified collection is null
185		*/
186		public ArrayDeque(Collection<? extends E> c) {
187	<	allocateElements(c.size());
188	<	addAll(c);
187	>	Object[] elements = c.toArray();
188	>	// defend against c.toArray (incorrectly) not returning Object[]
189	>	// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652)
190	>	size = elements.length;
191	>	if (elements.getClass() != Object[].class)
192	>	elements = Arrays.copyOf(elements, size, Object[].class);
193	>	for (Object obj : elements)
194	>	Objects.requireNonNull(obj);
195	>	this.elements = elements;
196	>	}
197	>
198	>	/**
199	>	* Increments i, mod modulus.
200	>	* Precondition and postcondition: 0 <= i < modulus.
201	>	*/
202	>	static final int inc(int i, int modulus) {
203	>	if (++i == modulus) i = 0;
204	>	return i;
205	>	}
206	>
207	>	/**
208	>	* Decrements i, mod modulus.
209	>	* Precondition and postcondition: 0 <= i < modulus.
210	>	*/
211	>	static final int dec(int i, int modulus) {
212	>	if (--i < 0) i += modulus;
213	>	return i;
214	>	}
215	>
216	>	/**
217	>	* Adds i and j, mod modulus.
218	>	* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus.
219	>	*/
220	>	static final int add(int i, int j, int modulus) {
221	>	if ((i += j) - modulus >= 0) i -= modulus;
222	>	return i;
223	>	}
224	>
225	>	/**
226	>	* Returns the array index of the last element.
227	>	* May return invalid index -1 if there are no elements.
228	>	*/
229	>	final int tail() {
230	>	return add(head, size - 1, elements.length);
231	>	}
232	>
233	>	/**
234	>	* Returns element at array index i.
235	>	*/
236	>	@SuppressWarnings("unchecked")
237	>	final E elementAt(int i) {
238	>	return (E) elements[i];
239	>	}
240	>
241	>	/**
242	>	* A version of elementAt that checks for null elements.
243	>	* This check doesn't catch all possible comodifications,
244	>	* but does catch ones that corrupt traversal.
245	>	*/
246	>	E checkedElementAt(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,
#	Line 179 | Line 261 | public class ArrayDeque<E> extends Abstr
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	>	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;
280		}
281
282		/**
#	Line 195 | Line 288 | public class ArrayDeque<E> extends Abstr
288		* @throws NullPointerException if the specified element is null
289		*/
290		public void addLast(E e) {
291	<	if (e == null)
292	<	throw new NullPointerException();
293	<	elements[tail] = e;
294	<	if ( (tail = (tail + 1) & (elements.length - 1)) == head)
295	<	doubleCapacity();
291	>	// checkInvariants();
292	>	Objects.requireNonNull(e);
293	>	final Object[] elements;
294	>	final int capacity, s;
295	>	if ((s = size) == (capacity = (elements = this.elements).length))
296	>	addLastSlowPath(e);
297	>	else
298	>	elements[add(head, s, capacity)] = e;
299	>	size = s + 1;
300	>	// checkInvariants();
301	>	}
302	>
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	>
309	>	/**
310	>	* Adds all of the elements in the specified collection at the end
311	>	* of this deque, as if by calling {@link #addLast} on each one,
312	>	* in the order that they are returned by the collection's
313	>	* iterator.
314	>	*
315	>	* @param c the elements to be inserted into this deque
316	>	* @return {@code true} if this deque changed as a result of the call
317	>	* @throws NullPointerException if the specified collection or any
318	>	*         of its elements are null
319	>	*/
320	>	@Override
321	>	public boolean addAll(Collection<? extends E> c) {
322	>	// checkInvariants();
323	>	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;
337		}
338
339		/**
#	Line 230 | Line 364 | public class ArrayDeque<E> extends Abstr
364		* @throws NoSuchElementException {@inheritDoc}
365		*/
366		public E removeFirst() {
367	<	E x = pollFirst();
368	<	if (x == null)
367	>	// checkInvariants();
368	>	E e = pollFirst();
369	>	if (e == null)
370		throw new NoSuchElementException();
371	<	return x;
371	>	return e;
372		}
373
374		/**
375		* @throws NoSuchElementException {@inheritDoc}
376		*/
377		public E removeLast() {
378	<	E x = pollLast();
379	<	if (x == null)
378	>	// checkInvariants();
379	>	E e = pollLast();
380	>	if (e == null)
381		throw new NoSuchElementException();
382	<	return x;
382	>	return e;
383		}
384
385		public E pollFirst() {
386	<	int h = head;
387	<	@SuppressWarnings("unchecked")
388	<	E result = (E) elements[h];
389	<	// Element is null if deque empty
390	<	if (result != null) {
391	<	elements[h] = null; // Must null out slot
392	<	head = (h + 1) & (elements.length - 1);
393	<	}
394	<	return result;
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;
395	>	return e;
396		}
397
398		public E pollLast() {
399	<	int t = (tail - 1) & (elements.length - 1);
399	>	// 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 result = (E) elements[t];
406	<	if (result != null) {
407	<	elements[t] = null;
408	<	tail = t;
268	<	}
269	<	return result;
405	>	E e = (E) elements[tail = add(head, s - 1, elements.length)];
406	>	elements[tail] = null;
407	>	size = s - 1;
408	>	return e;
409		}
410
411		/**
412		* @throws NoSuchElementException {@inheritDoc}
413		*/
414		public E getFirst() {
415	<	@SuppressWarnings("unchecked")
416	<	E result = (E) elements[head];
417	<	if (result == null)
279	<	throw new NoSuchElementException();
280	<	return result;
415	>	// checkInvariants();
416	>	if (size == 0) throw new NoSuchElementException();
417	>	return elementAt(head);
418		}
419
420		/**
421		* @throws NoSuchElementException {@inheritDoc}
422		*/
423		public E getLast() {
424	<	@SuppressWarnings("unchecked")
425	<	E result = (E) elements[(tail - 1) & (elements.length - 1)];
426	<	if (result == null)
290	<	throw new NoSuchElementException();
291	<	return result;
424	>	// checkInvariants();
425	>	if (size == 0) throw new NoSuchElementException();
426	>	return elementAt(tail());
427		}
428
294	–	@SuppressWarnings("unchecked")
429		public E peekFirst() {
430	<	// elements[head] is null if deque empty
431	<	return (E) elements[head];
430	>	// checkInvariants();
431	>	return (size == 0) ? null : elementAt(head);
432		}
433
300	–	@SuppressWarnings("unchecked")
434		public E peekLast() {
435	<	return (E) elements[(tail - 1) & (elements.length - 1)];
435	>	// checkInvariants();
436	>	return (size == 0) ? null : elementAt(tail());
437		}
438
439		/**
#	Line 315 | Line 449 | public class ArrayDeque<E> extends Abstr
449		* @return {@code true} if the deque contained the specified element
450		*/
451		public boolean removeFirstOccurrence(Object o) {
452	+	// checkInvariants();
453		if (o != null) {
454	<	int mask = elements.length - 1;
455	<	int i = head;
456	<	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
457	<	if (o.equals(x)) {
454	>	final Object[] elements = this.elements;
455	>	final int capacity = elements.length;
456	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) {
457	>	if (o.equals(elements[i])) {
458		delete(i);
459		return true;
460		}
#	Line 342 | Line 477 | public class ArrayDeque<E> extends Abstr
477		*/
478		public boolean removeLastOccurrence(Object o) {
479		if (o != null) {
480	<	int mask = elements.length - 1;
481	<	int i = (tail - 1) & mask;
482	<	for (Object x; (x = elements[i]) != null; i = (i - 1) & mask) {
483	<	if (o.equals(x)) {
480	>	final Object[] elements = this.elements;
481	>	final int capacity = elements.length;
482	>	for (int k = size, i = add(head, k - 1, capacity);
483	>	--k >= 0; i = dec(i, capacity)) {
484	>	if (o.equals(elements[i])) {
485		delete(i);
486		return true;
487		}
#	Line 468 | Line 604 | public class ArrayDeque<E> extends Abstr
604		return removeFirst();
605		}
606
471	–	private void checkInvariants() {
472	–	assert elements[tail] == null;
473	–	assert head == tail ? elements[head] == null :
474	–	(elements[head] != null &&
475	–	elements[(tail - 1) & (elements.length - 1)] != null);
476	–	assert elements[(head - 1) & (elements.length - 1)] == null;
477	–	}
478	–
607		/**
608	<	* Removes the element at the specified position in the elements array,
609	<	* adjusting head and tail as necessary.  This can result in motion of
610	<	* elements backwards or forwards in the array.
608	>	* Removes the element at the specified position in the elements array.
609	>	* This can result in forward or backwards motion of array elements.
610	>	* We optimize for least element motion.
611		*
612		* <p>This method is called delete rather than remove to emphasize
613		* that its semantics differ from those of {@link List#remove(int)}.
614		*
615		* @return true if elements moved backwards
616		*/
617	<	private boolean delete(int i) {
618	<	checkInvariants();
617	>	boolean delete(int i) {
618	>	// checkInvariants();
619		final Object[] elements = this.elements;
620	<	final int mask = elements.length - 1;
620	>	final int capacity = elements.length;
621		final int h = head;
622	<	final int t = tail;
623	<	final int front = (i - h) & mask;
624	<	final int back  = (t - i) & mask;
497	<
498	<	// Invariant: head <= i < tail mod circularity
499	<	if (front >= ((t - h) & mask))
500	<	throw new ConcurrentModificationException();
501	<
502	<	// Optimize for least element motion
622	>	int front;              // number of elements before to-be-deleted elt
623	>	if ((front = i - h) < 0) front += capacity;
624	>	final int back = size - front - 1; // number of elements after
625		if (front < back) {
626	+	// move front elements forwards
627		if (h <= i) {
628		System.arraycopy(elements, h, elements, h + 1, front);
629		} else { // Wrap around
630		System.arraycopy(elements, 0, elements, 1, i);
631	<	elements[0] = elements[mask];
632	<	System.arraycopy(elements, h, elements, h + 1, mask - h);
631	>	elements[0] = elements[capacity - 1];
632	>	System.arraycopy(elements, h, elements, h + 1, front - (i + 1));
633		}
634		elements[h] = null;
635	<	head = (h + 1) & mask;
635	>	head = inc(h, capacity);
636	>	size--;
637	>	// checkInvariants();
638		return false;
639		} else {
640	<	if (i < t) { // Copy the null tail as well
640	>	// move back elements backwards
641	>	int tail = tail();
642	>	if (i <= tail) {
643		System.arraycopy(elements, i + 1, elements, i, back);
517	–	tail = t - 1;
644		} else { // Wrap around
645	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
646	<	elements[mask] = elements[0];
647	<	System.arraycopy(elements, 1, elements, 0, t);
648	<	tail = (t - 1) & mask;
645	>	int firstLeg = capacity - (i + 1);
646	>	System.arraycopy(elements, i + 1, elements, i, firstLeg);
647	>	elements[capacity - 1] = elements[0];
648	>	System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1);
649		}
650	+	elements[tail] = null;
651	+	size--;
652	+	// checkInvariants();
653		return true;
654		}
655		}
#	Line 533 | Line 662 | public class ArrayDeque<E> extends Abstr
662		* @return the number of elements in this deque
663		*/
664		public int size() {
665	<	return (tail - head) & (elements.length - 1);
665	>	return size;
666		}
667
668		/**
#	Line 542 | Line 671 | public class ArrayDeque<E> extends Abstr
671		* @return {@code true} if this deque contains no elements
672		*/
673		public boolean isEmpty() {
674	<	return head == tail;
674	>	return size == 0;
675		}
676
677		/**
#	Line 562 | Line 691 | public class ArrayDeque<E> extends Abstr
691		}
692
693		private class DeqIterator implements Iterator<E> {
694	<	/**
695	<	* Index of element to be returned by subsequent call to next.
567	<	*/
568	<	private int cursor = head;
694	>	/** Index of element to be returned by subsequent call to next. */
695	>	int cursor;
696
697	<	/**
698	<	* Tail recorded at construction (also in remove), to stop
572	<	* iterator and also to check for comodification.
573	<	*/
574	<	private int fence = tail;
697	>	/** Number of elements yet to be returned. */
698	>	int remaining = size;
699
700		/**
701		* Index of element returned by most recent call to next.
702		* Reset to -1 if element is deleted by a call to remove.
703		*/
704	<	private int lastRet = -1;
704	>	int lastRet = -1;
705	>
706	>	DeqIterator() { cursor = head; }
707
708	<	public boolean hasNext() {
709	<	return cursor != fence;
708	>	public final boolean hasNext() {
709	>	return remaining > 0;
710		}
711
712		public E next() {
713	<	if (cursor == fence)
713	>	if (remaining == 0)
714		throw new NoSuchElementException();
715	<	@SuppressWarnings("unchecked")
590	<	E result = (E) elements[cursor];
591	<	// This check doesn't catch all possible comodifications,
592	<	// but does catch the ones that corrupt traversal
593	<	if (tail != fence || result == null)
594	<	throw new ConcurrentModificationException();
715	>	E e = checkedElementAt(elements, cursor);
716		lastRet = cursor;
717	<	cursor = (cursor + 1) & (elements.length - 1);
718	<	return result;
717	>	cursor = inc(cursor, elements.length);
718	>	remaining--;
719	>	return e;
720	>	}
721	>
722	>	void postDelete(boolean leftShifted) {
723	>	if (leftShifted)
724	>	cursor = dec(cursor, elements.length); // undo inc in next
725		}
726
727	<	public void remove() {
727	>	public final void remove() {
728		if (lastRet < 0)
729		throw new IllegalStateException();
730	<	if (delete(lastRet)) { // if left-shifted, undo increment in next()
604	<	cursor = (cursor - 1) & (elements.length - 1);
605	<	fence = tail;
606	<	}
730	>	postDelete(delete(lastRet));
731		lastRet = -1;
732		}
733	+
734	+	public void forEachRemaining(Consumer<? super E> action) {
735	+	Objects.requireNonNull(action);
736	+	final Object[] elements = ArrayDeque.this.elements;
737	+	final int capacity = elements.length;
738	+	int k = remaining;
739	+	remaining = 0;
740	+	for (int i = cursor; --k >= 0; i = inc(i, capacity))
741	+	action.accept(checkedElementAt(elements, i));
742	+	}
743	+	}
744	+
745	+	private class DescendingIterator extends DeqIterator {
746	+	DescendingIterator() { cursor = tail(); }
747	+
748	+	public final E next() {
749	+	if (remaining == 0)
750	+	throw new NoSuchElementException();
751	+	E e = checkedElementAt(elements, cursor);
752	+	lastRet = cursor;
753	+	cursor = dec(cursor, elements.length);
754	+	remaining--;
755	+	return e;
756	+	}
757	+
758	+	void postDelete(boolean leftShifted) {
759	+	if (!leftShifted)
760	+	cursor = inc(cursor, elements.length); // undo dec in next
761	+	}
762	+
763	+	public final void forEachRemaining(Consumer<? super E> action) {
764	+	Objects.requireNonNull(action);
765	+	final Object[] elements = ArrayDeque.this.elements;
766	+	final int capacity = elements.length;
767	+	int k = remaining;
768	+	remaining = 0;
769	+	for (int i = cursor; --k >= 0; i = dec(i, capacity))
770	+	action.accept(checkedElementAt(elements, i));
771	+	}
772		}
773
774		/**
775	<	* This class is nearly a mirror-image of DeqIterator, using tail
776	<	* instead of head for initial cursor, and head instead of tail
777	<	* for fence.
778	<	*/
779	<	private class DescendingIterator implements Iterator<E> {
780	<	private int cursor = tail;
781	<	private int fence = head;
782	<	private int lastRet = -1;
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	<	public boolean hasNext() {
796	<	return cursor != fence;
795	>	/** Constructs late-binding spliterator over all elements. */
796	>	ArrayDequeSpliterator() {
797	>	this.remaining = -1;
798		}
799
800	<	public E next() {
801	<	if (cursor == fence)
802	<	throw new NoSuchElementException();
803	<	cursor = (cursor - 1) & (elements.length - 1);
629	<	@SuppressWarnings("unchecked")
630	<	E result = (E) elements[cursor];
631	<	if (head != fence || result == null)
632	<	throw new ConcurrentModificationException();
633	<	lastRet = cursor;
634	<	return result;
800	>	/** Constructs spliterator over the given slice. */
801	>	ArrayDequeSpliterator(int cursor, int count) {
802	>	this.cursor = cursor;
803	>	this.remaining = count;
804		}
805
806	<	public void remove() {
807	<	if (lastRet < 0)
808	<	throw new IllegalStateException();
809	<	if (!delete(lastRet)) {
810	<	cursor = (cursor + 1) & (elements.length - 1);
642	<	fence = head;
806	>	/** Ensures late-binding initialization; then returns remaining. */
807	>	private int remaining() {
808	>	if (remaining < 0) {
809	>	cursor = head;
810	>	remaining = size;
811		}
812	<	lastRet = -1;
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	>	Objects.requireNonNull(action);
828	>	final Object[] elements = ArrayDeque.this.elements;
829	>	final int capacity = elements.length;
830	>	int k = remaining();
831	>	remaining = 0;
832	>	for (int i = cursor; --k >= 0; i = inc(i, capacity))
833	>	action.accept(checkedElementAt(elements, i));
834	>	}
835	>
836	>	public boolean tryAdvance(Consumer<? super E> action) {
837	>	Objects.requireNonNull(action);
838	>	if (remaining() == 0)
839	>	return false;
840	>	action.accept(checkedElementAt(elements, cursor));
841	>	cursor = inc(cursor, elements.length);
842	>	remaining--;
843	>	return true;
844	>	}
845	>
846	>	public long estimateSize() {
847	>	return remaining();
848	>	}
849	>
850	>	public int characteristics() {
851	>	return Spliterator.NONNULL
852	>	| Spliterator.ORDERED
853	>	| Spliterator.SIZED
854	>	| Spliterator.SUBSIZED;
855	>	}
856	>	}
857	>
858	>	@Override
859	>	public void forEach(Consumer<? super E> action) {
860	>	// checkInvariants();
861	>	Objects.requireNonNull(action);
862	>	final Object[] elements = this.elements;
863	>	final int capacity = elements.length;
864	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
865	>	action.accept(elementAt(i));
866	>	// checkInvariants();
867	>	}
868	>
869	>	/**
870	>	* Replaces each element of this deque with the result of applying the
871	>	* operator to that element, as specified by {@link List#replaceAll}.
872	>	*
873	>	* @param operator the operator to apply to each element
874	>	* @since TBD
875	>	*/
876	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
877	>	Objects.requireNonNull(operator);
878	>	final Object[] elements = this.elements;
879	>	final int capacity = elements.length;
880	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
881	>	elements[i] = operator.apply(elementAt(i));
882	>	// checkInvariants();
883	>	}
884	>
885	>	/**
886	>	* @throws NullPointerException {@inheritDoc}
887	>	*/
888	>	@Override
889	>	public boolean removeIf(Predicate<? super E> filter) {
890	>	Objects.requireNonNull(filter);
891	>	return bulkRemove(filter);
892	>	}
893	>
894	>	/**
895	>	* @throws NullPointerException {@inheritDoc}
896	>	*/
897	>	@Override
898	>	public boolean removeAll(Collection<?> c) {
899	>	Objects.requireNonNull(c);
900	>	return bulkRemove(e -> c.contains(e));
901	>	}
902	>
903	>	/**
904	>	* @throws NullPointerException {@inheritDoc}
905	>	*/
906	>	@Override
907	>	public boolean retainAll(Collection<?> c) {
908	>	Objects.requireNonNull(c);
909	>	return bulkRemove(e -> !c.contains(e));
910	>	}
911	>
912	>	/** Implementation of bulk remove methods. */
913	>	private boolean bulkRemove(Predicate<? super E> filter) {
914	>	// checkInvariants();
915	>	final Object[] elements = this.elements;
916	>	final int capacity = elements.length;
917	>	int i = head, j = i, remaining = size, deleted = 0;
918	>	try {
919	>	for (; remaining > 0; remaining--, i = inc(i, capacity)) {
920	>	@SuppressWarnings("unchecked") E e = (E) elements[i];
921	>	if (filter.test(e))
922	>	deleted++;
923	>	else {
924	>	if (j != i)
925	>	elements[j] = e;
926	>	j = inc(j, capacity);
927	>	}
928	>	}
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();
941		}
942		}
943
#	Line 655 | Line 951 | public class ArrayDeque<E> extends Abstr
951		*/
952		public boolean contains(Object o) {
953		if (o != null) {
954	<	int mask = elements.length - 1;
955	<	int i = head;
956	<	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
957	<	if (o.equals(x))
954	>	final Object[] elements = this.elements;
955	>	final int capacity = elements.length;
956	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
957	>	if (o.equals(elements[i]))
958		return true;
663	–	}
959		}
960		return false;
961		}
#	Line 687 | Line 982 | public class ArrayDeque<E> extends Abstr
982		* The deque will be empty after this call returns.
983		*/
984		public void clear() {
985	<	int h = head;
986	<	int t = tail;
987	<	if (h != t) { // clear all cells
988	<	head = tail = 0;
989	<	int i = h;
990	<	int mask = elements.length - 1;
991	<	do {
992	<	elements[i] = null;
993	<	i = (i + 1) & mask;
699	<	} while (i != t);
985	>	final Object[] elements = this.elements;
986	>	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;
996	+	// checkInvariants();
997		}
998
999		/**
#	Line 715 | Line 1011 | public class ArrayDeque<E> extends Abstr
1011		*/
1012		public Object[] toArray() {
1013		final int head = this.head;
1014	<	final int tail = this.tail;
1015	<	boolean wrap = (tail < head);
1016	<	int end = wrap ? tail + elements.length : tail;
1017	<	Object[] a = Arrays.copyOfRange(elements, head, end);
722	<	if (wrap)
723	<	System.arraycopy(elements, 0, a, elements.length - head, tail);
1014	>	final int firstLeg;
1015	>	Object[] a = Arrays.copyOfRange(elements, head, head + size);
1016	>	if ((firstLeg = elements.length - head) < size)
1017	>	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1018		return a;
1019		}
1020
#	Line 762 | Line 1056 | public class ArrayDeque<E> extends Abstr
1056		*/
1057		@SuppressWarnings("unchecked")
1058		public <T> T[] toArray(T[] a) {
1059	+	final Object[] elements = this.elements;
1060		final int head = this.head;
1061	<	final int tail = this.tail;
1062	<	boolean wrap = (tail < head);
1063	<	int size = (tail - head) + (wrap ? elements.length : 0);
769	<	int firstLeg = size - (wrap ? tail : 0);
770	<	int len = a.length;
771	<	if (size > len) {
1061	>	final int firstLeg;
1062	>	boolean wrap = (firstLeg = elements.length - head) < size;
1063	>	if (size > a.length) {
1064		a = (T[]) Arrays.copyOfRange(elements, head, head + size,
1065		a.getClass());
1066		} else {
1067	<	System.arraycopy(elements, head, a, 0, firstLeg);
1068	<	if (size < len)
1067	>	System.arraycopy(elements, head, a, 0, wrap ? firstLeg : size);
1068	>	if (size < a.length)
1069		a[size] = null;
1070		}
1071		if (wrap)
1072	<	System.arraycopy(elements, 0, a, firstLeg, tail);
1072	>	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1073		return a;
1074		}
1075
#	Line 815 | Line 1107 | public class ArrayDeque<E> extends Abstr
1107		s.defaultWriteObject();
1108
1109		// Write out size
1110	<	s.writeInt(size());
1110	>	s.writeInt(size);
1111
1112		// Write out elements in order.
1113	<	int mask = elements.length - 1;
1114	<	for (int i = head; i != tail; i = (i + 1) & mask)
1113	>	final Object[] elements = this.elements;
1114	>	final int capacity = elements.length;
1115	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1116		s.writeObject(elements[i]);
1117		}
1118
#	Line 835 | Line 1128 | public class ArrayDeque<E> extends Abstr
1128		s.defaultReadObject();
1129
1130		// Read in size and allocate array
1131	<	int size = s.readInt();
839	<	allocateElements(size);
840	<	head = 0;
841	<	tail = size;
1131	>	elements = new Object[size = s.readInt()];
1132
1133		// Read in all elements in the proper order.
1134		for (int i = 0; i < size; i++)
1135		elements[i] = s.readObject();
1136		}
1137
1138	<	public Spliterator<E> spliterator() {
1139	<	return new DeqSpliterator<E>(this, -1, -1);
1140	<	}
1141	<
1142	<	static final class DeqSpliterator<E> implements Spliterator<E> {
1143	<	private final ArrayDeque<E> deq;
1144	<	private int fence;  // -1 until first use
1145	<	private int index;  // current index, modified on traverse/split
1146	<
1147	<	/** Creates new spliterator covering the given array and range */
1148	<	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
1149	<	this.deq = deq;
1150	<	this.index = origin;
1151	<	this.fence = fence;
1152	<	}
1153	<
1154	<	private int getFence() { // force initialization
1155	<	int t;
866	<	if ((t = fence) < 0) {
867	<	t = fence = deq.tail;
868	<	index = deq.head;
869	<	}
870	<	return t;
871	<	}
872	<
873	<	public Spliterator<E> trySplit() {
874	<	int t = getFence(), h = index, n = deq.elements.length;
875	<	if (h != t && ((h + 1) & (n - 1)) != t) {
876	<	if (h > t)
877	<	t += n;
878	<	int m = ((h + t) >>> 1) & (n - 1);
879	<	return new DeqSpliterator<>(deq, h, index = m);
880	<	}
881	<	return null;
882	<	}
883	<
884	<	public void forEachRemaining(Consumer<? super E> consumer) {
885	<	if (consumer == null)
886	<	throw new NullPointerException();
887	<	Object[] a = deq.elements;
888	<	int m = a.length - 1, f = getFence(), i = index;
889	<	index = f;
890	<	while (i != f) {
891	<	@SuppressWarnings("unchecked") E e = (E)a[i];
892	<	i = (i + 1) & m;
893	<	if (e == null)
894	<	throw new ConcurrentModificationException();
895	<	consumer.accept(e);
896	<	}
897	<	}
898	<
899	<	public boolean tryAdvance(Consumer<? super E> consumer) {
900	<	if (consumer == null)
901	<	throw new NullPointerException();
902	<	Object[] a = deq.elements;
903	<	int m = a.length - 1, f = getFence(), i = index;
904	<	if (i != f) {
905	<	@SuppressWarnings("unchecked") E e = (E)a[i];
906	<	index = (i + 1) & m;
907	<	if (e == null)
908	<	throw new ConcurrentModificationException();
909	<	consumer.accept(e);
910	<	return true;
911	<	}
912	<	return false;
913	<	}
914	<
915	<	public long estimateSize() {
916	<	int n = getFence() - index;
917	<	if (n < 0)
918	<	n += deq.elements.length;
919	<	return (long) n;
920	<	}
921	<
922	<	@Override
923	<	public int characteristics() {
924	<	return Spliterator.ORDERED | Spliterator.SIZED |
925	<	Spliterator.NONNULL | Spliterator.SUBSIZED;
1138	>	/** debugging */
1139	>	private void checkInvariants() {
1140	>	try {
1141	>	int capacity = elements.length;
1142	>	assert size >= 0 && size <= capacity;
1143	>	assert head >= 0 && ((capacity == 0 && head == 0 && size == 0)
1144	>	|| head < capacity);
1145	>	assert size == 0
1146	>	|| (elements[head] != null && elements[tail()] != null);
1147	>	assert size == capacity
1148	>	|| (elements[dec(head, capacity)] == null
1149	>	&& elements[inc(tail(), capacity)] == null);
1150	>	} catch (Throwable t) {
1151	>	System.err.printf("head=%d size=%d capacity=%d%n",
1152	>	head, size, elements.length);
1153	>	System.err.printf("elements=%s%n",
1154	>	Arrays.toString(elements));
1155	>	throw t;
1156		}
1157		}
1158

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