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Comparing jsr166/src/jdk8/java/util/ArrayDeque.java (file contents):
Revision 1.1 by jsr166, Sat Mar 26 06:22:49 2016 UTC vs.
Revision 1.2 by jsr166, Mon Oct 24 23:54:10 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 - 1;
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	>	private 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	>	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		/**
#	Line 195 | Line 285 | public class ArrayDeque<E> extends Abstr
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		/**
#	Line 230 | Line 347 | public class ArrayDeque<E> extends Abstr
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	+	// checkInvariants();
370	+	int s, h;
371	+	if ((s = size) == 0)
372	+	return null;
373		final Object[] elements = this.elements;
374	<	final int h = head;
375	<	@SuppressWarnings("unchecked")
376	<	E result = (E) elements[h];
377	<	// Element is null if deque empty
378	<	if (result != null) {
379	<	elements[h] = null; // Must null out slot
257	<	head = (h + 1) & (elements.length - 1);
258	<	}
259	<	return result;
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	+	// checkInvariants();
384	+	final int s, tail;
385	+	if ((s = size) == 0)
386	+	return null;
387		final Object[] elements = this.elements;
264	–	final int t = (tail - 1) & (elements.length - 1);
388		@SuppressWarnings("unchecked")
389	<	E result = (E) elements[t];
390	<	if (result != null) {
391	<	elements[t] = null;
392	<	tail = t;
270	<	}
271	<	return result;
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	<	@SuppressWarnings("unchecked")
400	<	E result = (E) elements[head];
401	<	if (result == null)
281	<	throw new NoSuchElementException();
282	<	return result;
399	>	// checkInvariants();
400	>	if (size == 0) throw new NoSuchElementException();
401	>	return elementAt(head);
402		}
403
404		/**
405		* @throws NoSuchElementException {@inheritDoc}
406		*/
407		public E getLast() {
408	<	@SuppressWarnings("unchecked")
409	<	E result = (E) elements[(tail - 1) & (elements.length - 1)];
410	<	if (result == null)
292	<	throw new NoSuchElementException();
293	<	return result;
408	>	// checkInvariants();
409	>	if (size == 0) throw new NoSuchElementException();
410	>	return elementAt(tail());
411		}
412
296	–	@SuppressWarnings("unchecked")
413		public E peekFirst() {
414	<	// elements[head] is null if deque empty
415	<	return (E) elements[head];
414	>	// checkInvariants();
415	>	return (size == 0) ? null : elementAt(head);
416		}
417
302	–	@SuppressWarnings("unchecked")
418		public E peekLast() {
419	<	return (E) elements[(tail - 1) & (elements.length - 1)];
419	>	// checkInvariants();
420	>	return (size == 0) ? null : elementAt(tail());
421		}
422
423		/**
#	Line 318 | Line 434 | public class ArrayDeque<E> extends Abstr
434		*/
435		public boolean removeFirstOccurrence(Object o) {
436		if (o != null) {
437	<	int mask = elements.length - 1;
438	<	int i = head;
439	<	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
440	<	if (o.equals(x)) {
441	<	delete(i);
442	<	return true;
443	<	}
437	>	final Object[] elements = this.elements;
438	>	final int capacity = elements.length;
439	>	int from, end, to, leftover;
440	>	leftover = (end = (from = head) + size)
441	>	- (to = (capacity - end >= 0) ? end : capacity);
442	>	for (;; from = 0, to = leftover, leftover = 0) {
443	>	for (int i = from; i < to; i++)
444	>	if (o.equals(elements[i])) {
445	>	delete(i);
446	>	return true;
447	>	}
448	>	if (leftover == 0) break;
449		}
450		}
451		return false;
#	Line 344 | Line 465 | public class ArrayDeque<E> extends Abstr
465		*/
466		public boolean removeLastOccurrence(Object o) {
467		if (o != null) {
468	<	int mask = elements.length - 1;
469	<	int i = (tail - 1) & mask;
470	<	for (Object x; (x = elements[i]) != null; i = (i - 1) & mask) {
471	<	if (o.equals(x)) {
472	<	delete(i);
473	<	return true;
474	<	}
468	>	final Object[] elements = this.elements;
469	>	final int capacity = elements.length;
470	>	int from, to, end, leftover;
471	>	leftover = (to = ((end = (from = tail()) - size) >= -1) ? end : -1) - end;
472	>	for (;; from = capacity - 1, to = capacity - 1 - leftover, leftover = 0) {
473	>	for (int i = from; i > to; i--)
474	>	if (o.equals(elements[i])) {
475	>	delete(i);
476	>	return true;
477	>	}
478	>	if (leftover == 0) break;
479		}
480		}
481		return false;
#	Line 470 | Line 595 | public class ArrayDeque<E> extends Abstr
595		return removeFirst();
596		}
597
473	–	private void checkInvariants() {
474	–	assert elements[tail] == null;
475	–	assert head == tail ? elements[head] == null :
476	–	(elements[head] != null &&
477	–	elements[(tail - 1) & (elements.length - 1)] != null);
478	–	assert elements[(head - 1) & (elements.length - 1)] == null;
479	–	}
480	–
598		/**
599	<	* Removes the element at the specified position in the elements array,
600	<	* adjusting head and tail as necessary.  This can result in motion of
601	<	* elements backwards or forwards in the array.
599	>	* Removes the element at the specified position in the elements array.
600	>	* This can result in forward or backwards motion of array elements.
601	>	* We optimize for least element motion.
602		*
603		* <p>This method is called delete rather than remove to emphasize
604		* that its semantics differ from those of {@link List#remove(int)}.
#	Line 489 | Line 606 | public class ArrayDeque<E> extends Abstr
606		* @return true if elements moved backwards
607		*/
608		boolean delete(int i) {
609	<	checkInvariants();
609	>	// checkInvariants();
610		final Object[] elements = this.elements;
611	<	final int mask = elements.length - 1;
611	>	final int capacity = elements.length;
612		final int h = head;
613	<	final int t = tail;
614	<	final int front = (i - h) & mask;
615	<	final int back  = (t - i) & mask;
499	<
500	<	// Invariant: head <= i < tail mod circularity
501	<	if (front >= ((t - h) & mask))
502	<	throw new ConcurrentModificationException();
503	<
504	<	// Optimize for least element motion
613	>	int front;              // number of elements before to-be-deleted elt
614	>	if ((front = i - h) < 0) front += capacity;
615	>	final int back = size - front - 1; // number of elements after
616		if (front < back) {
617	+	// move front elements forwards
618		if (h <= i) {
619		System.arraycopy(elements, h, elements, h + 1, front);
620		} else { // Wrap around
621		System.arraycopy(elements, 0, elements, 1, i);
622	<	elements[0] = elements[mask];
623	<	System.arraycopy(elements, h, elements, h + 1, mask - h);
622	>	elements[0] = elements[capacity - 1];
623	>	System.arraycopy(elements, h, elements, h + 1, front - (i + 1));
624		}
625		elements[h] = null;
626	<	head = (h + 1) & mask;
626	>	if ((head = (h + 1)) >= capacity) head = 0;
627	>	size--;
628	>	// checkInvariants();
629		return false;
630		} else {
631	<	if (i < t) { // Copy the null tail as well
631	>	// move back elements backwards
632	>	int tail = tail();
633	>	if (i <= tail) {
634		System.arraycopy(elements, i + 1, elements, i, back);
519	–	tail = t - 1;
635		} else { // Wrap around
636	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
637	<	elements[mask] = elements[0];
638	<	System.arraycopy(elements, 1, elements, 0, t);
639	<	tail = (t - 1) & mask;
636	>	int firstLeg = capacity - (i + 1);
637	>	System.arraycopy(elements, i + 1, elements, i, firstLeg);
638	>	elements[capacity - 1] = elements[0];
639	>	System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1);
640		}
641	+	elements[tail] = null;
642	+	size--;
643	+	// checkInvariants();
644		return true;
645		}
646		}
#	Line 535 | Line 653 | public class ArrayDeque<E> extends Abstr
653		* @return the number of elements in this deque
654		*/
655		public int size() {
656	<	return (tail - head) & (elements.length - 1);
656	>	return size;
657		}
658
659		/**
#	Line 544 | Line 662 | public class ArrayDeque<E> extends Abstr
662		* @return {@code true} if this deque contains no elements
663		*/
664		public boolean isEmpty() {
665	<	return head == tail;
665	>	return size == 0;
666		}
667
668		/**
#	Line 564 | Line 682 | public class ArrayDeque<E> extends Abstr
682		}
683
684		private class DeqIterator implements Iterator<E> {
685	<	/**
686	<	* Index of element to be returned by subsequent call to next.
569	<	*/
570	<	private int cursor = head;
685	>	/** Index of element to be returned by subsequent call to next. */
686	>	int cursor;
687
688	<	/**
689	<	* Tail recorded at construction (also in remove), to stop
574	<	* iterator and also to check for comodification.
575	<	*/
576	<	private int fence = tail;
688	>	/** Number of elements yet to be returned. */
689	>	int remaining = size;
690
691		/**
692		* Index of element returned by most recent call to next.
693		* Reset to -1 if element is deleted by a call to remove.
694		*/
695	<	private int lastRet = -1;
695	>	int lastRet = -1;
696	>
697	>	DeqIterator() { cursor = head; }
698
699	<	public boolean hasNext() {
700	<	return cursor != fence;
699	>	public final boolean hasNext() {
700	>	return remaining > 0;
701		}
702
703		public E next() {
704	<	if (cursor == fence)
704	>	if (remaining == 0)
705		throw new NoSuchElementException();
706	<	@SuppressWarnings("unchecked")
707	<	E result = (E) elements[cursor];
593	<	// This check doesn't catch all possible comodifications,
594	<	// but does catch the ones that corrupt traversal
595	<	if (tail != fence || result == null)
596	<	throw new ConcurrentModificationException();
706	>	final Object[] elements = ArrayDeque.this.elements;
707	>	E e = checkedElementAt(elements, cursor);
708		lastRet = cursor;
709	<	cursor = (cursor + 1) & (elements.length - 1);
710	<	return result;
709	>	if (++cursor >= elements.length) cursor = 0;
710	>	remaining--;
711	>	return e;
712	>	}
713	>
714	>	void postDelete(boolean leftShifted) {
715	>	if (leftShifted)
716	>	if (--cursor < 0) cursor = elements.length - 1;
717		}
718
719	<	public void remove() {
719	>	public final void remove() {
720		if (lastRet < 0)
721		throw new IllegalStateException();
722	<	if (delete(lastRet)) { // if left-shifted, undo increment in next()
606	<	cursor = (cursor - 1) & (elements.length - 1);
607	<	fence = tail;
608	<	}
722	>	postDelete(delete(lastRet));
723		lastRet = -1;
724		}
725
726		public void forEachRemaining(Consumer<? super E> action) {
727	+	int k;
728	+	if ((k = remaining) > 0) {
729	+	remaining = 0;
730	+	ArrayDeque.forEachRemaining(action, elements, cursor, k);
731	+	if ((lastRet = cursor + k - 1) >= elements.length)
732	+	lastRet -= elements.length;
733	+	}
734	+	}
735	+	}
736	+
737	+	private class DescendingIterator extends DeqIterator {
738	+	DescendingIterator() { cursor = tail(); }
739	+
740	+	public final E next() {
741	+	if (remaining == 0)
742	+	throw new NoSuchElementException();
743	+	final Object[] elements = ArrayDeque.this.elements;
744	+	E e = checkedElementAt(elements, cursor);
745	+	lastRet = cursor;
746	+	if (--cursor < 0) cursor = elements.length - 1;
747	+	remaining--;
748	+	return e;
749	+	}
750	+
751	+	void postDelete(boolean leftShifted) {
752	+	if (!leftShifted)
753	+	if (++cursor >= elements.length) cursor = 0;
754	+	}
755	+
756	+	public final void forEachRemaining(Consumer<? super E> action) {
757	+	int k;
758	+	if ((k = remaining) > 0) {
759	+	remaining = 0;
760	+	forEachRemainingDescending(action, elements, cursor, k);
761	+	if ((lastRet = cursor - (k - 1)) < 0)
762	+	lastRet += elements.length;
763	+	}
764	+	}
765	+	}
766	+
767	+	/**
768	+	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
769	+	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
770	+	* deque.
771	+	*
772	+	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
773	+	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
774	+	* {@link Spliterator#NONNULL}.  Overriding implementations should document
775	+	* the reporting of additional characteristic values.
776	+	*
777	+	* @return a {@code Spliterator} over the elements in this deque
778	+	* @since 1.8
779	+	*/
780	+	public Spliterator<E> spliterator() {
781	+	return new ArrayDequeSpliterator();
782	+	}
783	+
784	+	final class ArrayDequeSpliterator implements Spliterator<E> {
785	+	private int cursor;
786	+	private int remaining; // -1 until late-binding first use
787	+
788	+	/** Constructs late-binding spliterator over all elements. */
789	+	ArrayDequeSpliterator() {
790	+	this.remaining = -1;
791	+	}
792	+
793	+	/** Constructs spliterator over the given slice. */
794	+	ArrayDequeSpliterator(int cursor, int count) {
795	+	this.cursor = cursor;
796	+	this.remaining = count;
797	+	}
798	+
799	+	/** Ensures late-binding initialization; then returns remaining. */
800	+	private int remaining() {
801	+	if (remaining < 0) {
802	+	cursor = head;
803	+	remaining = size;
804	+	}
805	+	return remaining;
806	+	}
807	+
808	+	public ArrayDequeSpliterator trySplit() {
809	+	final int mid;
810	+	if ((mid = remaining() >> 1) > 0) {
811	+	int oldCursor = cursor;
812	+	cursor = add(cursor, mid, elements.length);
813	+	remaining -= mid;
814	+	return new ArrayDequeSpliterator(oldCursor, mid);
815	+	}
816	+	return null;
817	+	}
818	+
819	+	public void forEachRemaining(Consumer<? super E> action) {
820	+	int k = remaining(); // side effect!
821	+	remaining = 0;
822	+	ArrayDeque.forEachRemaining(action, elements, cursor, k);
823	+	}
824	+
825	+	public boolean tryAdvance(Consumer<? super E> action) {
826		Objects.requireNonNull(action);
827	<	Object[] a = elements;
828	<	int m = a.length - 1, f = fence, i = cursor;
829	<	cursor = f;
830	<	while (i != f) {
831	<	@SuppressWarnings("unchecked") E e = (E)a[i];
832	<	i = (i + 1) & m;
827	>	if (remaining() == 0)
828	>	return false;
829	>	action.accept(checkedElementAt(elements, cursor));
830	>	if (++cursor >= elements.length) cursor = 0;
831	>	remaining--;
832	>	return true;
833	>	}
834	>
835	>	public long estimateSize() {
836	>	return remaining();
837	>	}
838	>
839	>	public int characteristics() {
840	>	return Spliterator.NONNULL
841	>	| Spliterator.ORDERED
842	>	| Spliterator.SIZED
843	>	| Spliterator.SUBSIZED;
844	>	}
845	>	}
846	>
847	>	@SuppressWarnings("unchecked")
848	>	public void forEach(Consumer<? super E> action) {
849	>	Objects.requireNonNull(action);
850	>	final Object[] elements = this.elements;
851	>	final int capacity = elements.length;
852	>	int from, end, to, leftover;
853	>	leftover = (end = (from = head) + size)
854	>	- (to = (capacity - end >= 0) ? end : capacity);
855	>	for (;; from = 0, to = leftover, leftover = 0) {
856	>	for (int i = from; i < to; i++)
857	>	action.accept((E) elements[i]);
858	>	if (leftover == 0) break;
859	>	}
860	>	// checkInvariants();
861	>	}
862	>
863	>	/**
864	>	* A variant of forEach that also checks for concurrent
865	>	* modification, for use in iterators.
866	>	*/
867	>	static <E> void forEachRemaining(
868	>	Consumer<? super E> action, Object[] elements, int from, int size) {
869	>	Objects.requireNonNull(action);
870	>	final int capacity = elements.length;
871	>	int end, to, leftover;
872	>	leftover = (end = from + size)
873	>	- (to = (capacity - end >= 0) ? end : capacity);
874	>	for (;; from = 0, to = leftover, leftover = 0) {
875	>	for (int i = from; i < to; i++) {
876	>	@SuppressWarnings("unchecked") E e = (E) elements[i];
877		if (e == null)
878		throw new ConcurrentModificationException();
879		action.accept(e);
880		}
881	+	if (leftover == 0) break;
882		}
883		}
884
885	<	/**
886	<	* This class is nearly a mirror-image of DeqIterator, using tail
887	<	* instead of head for initial cursor, and head instead of tail
888	<	* for fence.
889	<	*/
890	<	private class DescendingIterator implements Iterator<E> {
891	<	private int cursor = tail;
892	<	private int fence = head;
893	<	private int lastRet = -1;
894	<
895	<	public boolean hasNext() {
896	<	return cursor != fence;
885	>	static <E> void forEachRemainingDescending(
886	>	Consumer<? super E> action, Object[] elements, int from, int size) {
887	>	Objects.requireNonNull(action);
888	>	final int capacity = elements.length;
889	>	int end, to, leftover;
890	>	leftover = (to = ((end = from - size) >= -1) ? end : -1) - end;
891	>	for (;; from = capacity - 1, to = capacity - 1 - leftover, leftover = 0) {
892	>	for (int i = from; i > to; i--) {
893	>	@SuppressWarnings("unchecked") E e = (E) elements[i];
894	>	if (e == null)
895	>	throw new ConcurrentModificationException();
896	>	action.accept(e);
897	>	}
898	>	if (leftover == 0) break;
899		}
900	+	}
901
902	<	public E next() {
903	<	if (cursor == fence)
904	<	throw new NoSuchElementException();
905	<	cursor = (cursor - 1) & (elements.length - 1);
906	<	@SuppressWarnings("unchecked")
907	<	E result = (E) elements[cursor];
908	<	if (head != fence || result == null)
909	<	throw new ConcurrentModificationException();
910	<	lastRet = cursor;
911	<	return result;
902	>	/**
903	>	* Replaces each element of this deque with the result of applying the
904	>	* operator to that element, as specified by {@link List#replaceAll}.
905	>	*
906	>	* @param operator the operator to apply to each element
907	>	* @since TBD
908	>	*/
909	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
910	>	Objects.requireNonNull(operator);
911	>	final Object[] elements = this.elements;
912	>	final int capacity = elements.length;
913	>	int from, end, to, leftover;
914	>	leftover = (end = (from = head) + size)
915	>	- (to = (capacity - end >= 0) ? end : capacity);
916	>	for (;; from = 0, to = leftover, leftover = 0) {
917	>	for (int i = from; i < to; i++)
918	>	elements[i] = operator.apply(elementAt(i));
919	>	if (leftover == 0) break;
920		}
921	+	// checkInvariants();
922	+	}
923
924	<	public void remove() {
925	<	if (lastRet < 0)
926	<	throw new IllegalStateException();
927	<	if (!delete(lastRet)) {
928	<	cursor = (cursor + 1) & (elements.length - 1);
929	<	fence = head;
924	>	/**
925	>	* @throws NullPointerException {@inheritDoc}
926	>	*/
927	>	public boolean removeIf(Predicate<? super E> filter) {
928	>	Objects.requireNonNull(filter);
929	>	return bulkRemove(filter);
930	>	}
931	>
932	>	/**
933	>	* @throws NullPointerException {@inheritDoc}
934	>	*/
935	>	public boolean removeAll(Collection<?> c) {
936	>	Objects.requireNonNull(c);
937	>	return bulkRemove(e -> c.contains(e));
938	>	}
939	>
940	>	/**
941	>	* @throws NullPointerException {@inheritDoc}
942	>	*/
943	>	public boolean retainAll(Collection<?> c) {
944	>	Objects.requireNonNull(c);
945	>	return bulkRemove(e -> !c.contains(e));
946	>	}
947	>
948	>	/** Implementation of bulk remove methods. */
949	>	private boolean bulkRemove(Predicate<? super E> filter) {
950	>	// checkInvariants();
951	>	final Object[] elements = this.elements;
952	>	final int capacity = elements.length;
953	>	int i = head, j = i, remaining = size, deleted = 0;
954	>	try {
955	>	for (; remaining > 0; remaining--) {
956	>	@SuppressWarnings("unchecked") E e = (E) elements[i];
957	>	if (filter.test(e))
958	>	deleted++;
959	>	else {
960	>	if (j != i)
961	>	elements[j] = e;
962	>	if (++j >= capacity) j = 0;
963	>	}
964	>	if (++i >= capacity) i = 0;
965		}
966	<	lastRet = -1;
966	>	return deleted > 0;
967	>	} catch (Throwable ex) {
968	>	if (deleted > 0)
969	>	for (; remaining > 0; remaining--) {
970	>	elements[j] = elements[i];
971	>	if (++i >= capacity) i = 0;
972	>	if (++j >= capacity) j = 0;
973	>	}
974	>	throw ex;
975	>	} finally {
976	>	size -= deleted;
977	>	clearSlice(elements, j, deleted);
978	>	// checkInvariants();
979		}
980		}
981
#	Line 671 | Line 989 | public class ArrayDeque<E> extends Abstr
989		*/
990		public boolean contains(Object o) {
991		if (o != null) {
992	<	int mask = elements.length - 1;
993	<	int i = head;
994	<	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
995	<	if (o.equals(x))
996	<	return true;
992	>	final Object[] elements = this.elements;
993	>	final int capacity = elements.length;
994	>	int from, end, to, leftover;
995	>	leftover = (end = (from = head) + size)
996	>	- (to = (capacity - end >= 0) ? end : capacity);
997	>	for (;; from = 0, to = leftover, leftover = 0) {
998	>	for (int i = from; i < to; i++)
999	>	if (o.equals(elements[i]))
1000	>	return true;
1001	>	if (leftover == 0) break;
1002		}
1003		}
1004		return false;
#	Line 703 | Line 1026 | public class ArrayDeque<E> extends Abstr
1026		* The deque will be empty after this call returns.
1027		*/
1028		public void clear() {
1029	<	int h = head;
1030	<	int t = tail;
1031	<	if (h != t) { // clear all cells
1032	<	head = tail = 0;
1033	<	int i = h;
1034	<	int mask = elements.length - 1;
1035	<	do {
1036	<	elements[i] = null;
1037	<	i = (i + 1) & mask;
1038	<	} while (i != t);
1039	<	}
1029	>	clearSlice(elements, head, size);
1030	>	size = head = 0;
1031	>	// checkInvariants();
1032	>	}
1033	>
1034	>	/**
1035	>	* Nulls out size elements, starting at head.
1036	>	*/
1037	>	private static void clearSlice(Object[] elements, int head, int size) {
1038	>	final int capacity = elements.length, end = head + size;
1039	>	final int leg = (capacity - end >= 0) ? end : capacity;
1040	>	Arrays.fill(elements, head, leg, null);
1041	>	if (leg != end)
1042	>	Arrays.fill(elements, 0, end - capacity, null);
1043		}
1044
1045		/**
#	Line 730 | Line 1056 | public class ArrayDeque<E> extends Abstr
1056		* @return an array containing all of the elements in this deque
1057		*/
1058		public Object[] toArray() {
1059	<	final int head = this.head;
1060	<	final int tail = this.tail;
1061	<	boolean wrap = (tail < head);
1062	<	int end = wrap ? tail + elements.length : tail;
1063	<	Object[] a = Arrays.copyOfRange(elements, head, end);
1064	<	if (wrap)
1065	<	System.arraycopy(elements, 0, a, elements.length - head, tail);
1059	>	return toArray(Object[].class);
1060	>	}
1061	>
1062	>	private <T> T[] toArray(Class<T[]> klazz) {
1063	>	final Object[] elements = this.elements;
1064	>	final int capacity = elements.length;
1065	>	final int head = this.head, end = head + size;
1066	>	final T[] a;
1067	>	if (end >= 0) {
1068	>	a = Arrays.copyOfRange(elements, head, end, klazz);
1069	>	} else {
1070	>	// integer overflow!
1071	>	a = Arrays.copyOfRange(elements, 0, size, klazz);
1072	>	System.arraycopy(elements, head, a, 0, capacity - head);
1073	>	}
1074	>	if (end - capacity > 0)
1075	>	System.arraycopy(elements, 0, a, capacity - head, end - capacity);
1076		return a;
1077		}
1078
#	Line 778 | Line 1114 | public class ArrayDeque<E> extends Abstr
1114		*/
1115		@SuppressWarnings("unchecked")
1116		public <T> T[] toArray(T[] a) {
1117	<	final int head = this.head;
1118	<	final int tail = this.tail;
1119	<	boolean wrap = (tail < head);
1120	<	int size = (tail - head) + (wrap ? elements.length : 0);
1121	<	int firstLeg = size - (wrap ? tail : 0);
1122	<	int len = a.length;
1123	<	if (size > len) {
1124	<	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
1125	<	a.getClass());
1126	<	} else {
1127	<	System.arraycopy(elements, head, a, 0, firstLeg);
1128	<	if (size < len)
793	<	a[size] = null;
794	<	}
795	<	if (wrap)
796	<	System.arraycopy(elements, 0, a, firstLeg, tail);
1117	>	final int size = this.size;
1118	>	if (size > a.length)
1119	>	return toArray((Class<T[]>) a.getClass());
1120	>	final Object[] elements = this.elements;
1121	>	final int capacity = elements.length;
1122	>	final int head = this.head, end = head + size;
1123	>	final int front = (capacity - end >= 0) ? size : capacity - head;
1124	>	System.arraycopy(elements, head, a, 0, front);
1125	>	if (front != size)
1126	>	System.arraycopy(elements, 0, a, capacity - head, end - capacity);
1127	>	if (size < a.length)
1128	>	a[size] = null;
1129		return a;
1130		}
1131
#	Line 831 | Line 1163 | public class ArrayDeque<E> extends Abstr
1163		s.defaultWriteObject();
1164
1165		// Write out size
1166	<	s.writeInt(size());
1166	>	s.writeInt(size);
1167
1168		// Write out elements in order.
1169	<	int mask = elements.length - 1;
1170	<	for (int i = head; i != tail; i = (i + 1) & mask)
1171	<	s.writeObject(elements[i]);
1169	>	final Object[] elements = this.elements;
1170	>	final int capacity = elements.length;
1171	>	int from, end, to, leftover;
1172	>	leftover = (end = (from = head) + size)
1173	>	- (to = (capacity - end >= 0) ? end : capacity);
1174	>	for (;; from = 0, to = leftover, leftover = 0) {
1175	>	for (int i = from; i < to; i++)
1176	>	s.writeObject(elements[i]);
1177	>	if (leftover == 0) break;
1178	>	}
1179		}
1180
1181		/**
#	Line 851 | Line 1190 | public class ArrayDeque<E> extends Abstr
1190		s.defaultReadObject();
1191
1192		// Read in size and allocate array
1193	<	int size = s.readInt();
855	<	allocateElements(size);
856	<	head = 0;
857	<	tail = size;
1193	>	elements = new Object[size = s.readInt()];
1194
1195		// Read in all elements in the proper order.
1196		for (int i = 0; i < size; i++)
1197		elements[i] = s.readObject();
1198		}
1199
1200	<	/**
1201	<	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
1202	<	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
1203	<	* deque.
1204	<	*
1205	<	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
1206	<	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
1207	<	* {@link Spliterator#NONNULL}.  Overriding implementations should document
1208	<	* the reporting of additional characteristic values.
1209	<	*
1210	<	* @return a {@code Spliterator} over the elements in this deque
1211	<	* @since 1.8
1212	<	*/
1213	<	public Spliterator<E> spliterator() {
1214	<	return new DeqSpliterator<>(this, -1, -1);
1215	<	}
1216	<
881	<	static final class DeqSpliterator<E> implements Spliterator<E> {
882	<	private final ArrayDeque<E> deq;
883	<	private int fence;  // -1 until first use
884	<	private int index;  // current index, modified on traverse/split
885	<
886	<	/** Creates new spliterator covering the given array and range. */
887	<	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
888	<	this.deq = deq;
889	<	this.index = origin;
890	<	this.fence = fence;
891	<	}
892	<
893	<	private int getFence() { // force initialization
894	<	int t;
895	<	if ((t = fence) < 0) {
896	<	t = fence = deq.tail;
897	<	index = deq.head;
898	<	}
899	<	return t;
900	<	}
901	<
902	<	public DeqSpliterator<E> trySplit() {
903	<	int t = getFence(), h = index, n = deq.elements.length;
904	<	if (h != t && ((h + 1) & (n - 1)) != t) {
905	<	if (h > t)
906	<	t += n;
907	<	int m = ((h + t) >>> 1) & (n - 1);
908	<	return new DeqSpliterator<E>(deq, h, index = m);
909	<	}
910	<	return null;
911	<	}
912	<
913	<	public void forEachRemaining(Consumer<? super E> consumer) {
914	<	if (consumer == null)
915	<	throw new NullPointerException();
916	<	Object[] a = deq.elements;
917	<	int m = a.length - 1, f = getFence(), i = index;
918	<	index = f;
919	<	while (i != f) {
920	<	@SuppressWarnings("unchecked") E e = (E)a[i];
921	<	i = (i + 1) & m;
922	<	if (e == null)
923	<	throw new ConcurrentModificationException();
924	<	consumer.accept(e);
925	<	}
926	<	}
927	<
928	<	public boolean tryAdvance(Consumer<? super E> consumer) {
929	<	if (consumer == null)
930	<	throw new NullPointerException();
931	<	Object[] a = deq.elements;
932	<	int m = a.length - 1, f = getFence(), i = index;
933	<	if (i != f) {
934	<	@SuppressWarnings("unchecked") E e = (E)a[i];
935	<	index = (i + 1) & m;
936	<	if (e == null)
937	<	throw new ConcurrentModificationException();
938	<	consumer.accept(e);
939	<	return true;
940	<	}
941	<	return false;
942	<	}
943	<
944	<	public long estimateSize() {
945	<	int n = getFence() - index;
946	<	if (n < 0)
947	<	n += deq.elements.length;
948	<	return (long) n;
949	<	}
950	<
951	<	@Override
952	<	public int characteristics() {
953	<	return Spliterator.ORDERED | Spliterator.SIZED |
954	<	Spliterator.NONNULL | Spliterator.SUBSIZED;
1200	>	/** debugging */
1201	>	void checkInvariants() {
1202	>	try {
1203	>	int capacity = elements.length;
1204	>	// assert size >= 0 && size <= capacity;
1205	>	// assert head >= 0;
1206	>	// assert capacity == 0 || head < capacity;
1207	>	// assert size == 0 || elements[head] != null;
1208	>	// assert size == 0 || elements[tail()] != null;
1209	>	// assert size == capacity || elements[dec(head, capacity)] == null;
1210	>	// assert size == capacity || elements[inc(tail(), capacity)] == null;
1211	>	} catch (Throwable t) {
1212	>	System.err.printf("head=%d size=%d capacity=%d%n",
1213	>	head, size, elements.length);
1214	>	System.err.printf("elements=%s%n",
1215	>	Arrays.toString(elements));
1216	>	throw t;
1217		}
1218		}
1219

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