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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 1.137 by jsr166, Sun Nov 11 17:37:30 2018 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	+	// OPENJDK import jdk.internal.access.SharedSecrets;
12
13		/**
14		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 48 | Line 50 | import java.util.function.Consumer;
50		* Iterator} interfaces.
51		*
52		* <p>This class is a member of the
53	<	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
53	>	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
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	+	* VMs excel at optimizing simple array loops where indices are
65	+	* incrementing or decrementing over a valid slice, e.g.
66	+	*
67	+	* for (int i = start; i < end; i++) ... elements[i]
68	+	*
69	+	* Because in a circular array, elements are in general stored in
70	+	* two disjoint such slices, we help the VM by writing unusual
71	+	* nested loops for all traversals over the elements.  Having only
72	+	* one hot inner loop body instead of two or three eases human
73	+	* maintenance and encourages VM loop inlining into the caller.
74	+	*/
75	+
76		/**
77		* The array in which the elements of the deque are stored.
78	<	* The capacity of the deque is the length of this array, which is
79	<	* 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.
78	>	* All array cells not holding deque elements are always null.
79	>	* The array always has at least one null slot (at tail).
80		*/
81	<	transient Object[] elements; // non-private to simplify nested class access
81	>	transient Object[] elements;
82
83		/**
84		* The index of the element at the head of the deque (which is the
85		* element that would be removed by remove() or pop()); or an
86	<	* arbitrary number equal to tail if the deque is empty.
86	>	* arbitrary number 0 <= head < elements.length equal to tail if
87	>	* the deque is empty.
88		*/
89		transient int head;
90
91		/**
92		* The index at which the next element would be added to the tail
93	<	* of the deque (via addLast(E), add(E), or push(E)).
93	>	* of the deque (via addLast(E), add(E), or push(E));
94	>	* elements[tail] is always null.
95		*/
96		transient int tail;
97
98		/**
99	<	* The minimum capacity that we'll use for a newly created deque.
100	<	* Must be a power of 2.
99	>	* The maximum size of array to allocate.
100	>	* Some VMs reserve some header words in an array.
101	>	* Attempts to allocate larger arrays may result in
102	>	* OutOfMemoryError: Requested array size exceeds VM limit
103		*/
104	<	private static final int MIN_INITIAL_CAPACITY = 8;
104	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
105
106	<	// ******  Array allocation and resizing utilities ******
106	>	/**
107	>	* Increases the capacity of this deque by at least the given amount.
108	>	*
109	>	* @param needed the required minimum extra capacity; must be positive
110	>	*/
111	>	private void grow(int needed) {
112	>	// overflow-conscious code
113	>	final int oldCapacity = elements.length;
114	>	int newCapacity;
115	>	// Double capacity if small; else grow by 50%
116	>	int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
117	>	if (jump < needed
118	>	|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
119	>	newCapacity = newCapacity(needed, jump);
120	>	final Object[] es = elements = Arrays.copyOf(elements, newCapacity);
121	>	// Exceptionally, here tail == head needs to be disambiguated
122	>	if (tail < head || (tail == head && es[head] != null)) {
123	>	// wrap around; slide first leg forward to end of array
124	>	int newSpace = newCapacity - oldCapacity;
125	>	System.arraycopy(es, head,
126	>	es, head + newSpace,
127	>	oldCapacity - head);
128	>	for (int i = head, to = (head += newSpace); i < to; i++)
129	>	es[i] = null;
130	>	}
131	>	// checkInvariants();
132	>	}
133	>
134	>	/** Capacity calculation for edge conditions, especially overflow. */
135	>	private int newCapacity(int needed, int jump) {
136	>	final int oldCapacity = elements.length, minCapacity;
137	>	if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
138	>	if (minCapacity < 0)
139	>	throw new IllegalStateException("Sorry, deque too big");
140	>	return Integer.MAX_VALUE;
141	>	}
142	>	if (needed > jump)
143	>	return minCapacity;
144	>	return (oldCapacity + jump - MAX_ARRAY_SIZE < 0)
145	>	? oldCapacity + jump
146	>	: MAX_ARRAY_SIZE;
147	>	}
148
149		/**
150	<	* Allocates empty array to hold the given number of elements.
151	<	*
152	<	* @param numElements  the number of elements to hold
153	<	*/
154	<	private void allocateElements(int numElements) {
155	<	int initialCapacity = MIN_INITIAL_CAPACITY;
156	<	// Find the best power of two to hold elements.
157	<	// Tests "<=" because arrays aren't kept full.
158	<	if (numElements >= initialCapacity) {
159	<	initialCapacity = numElements;
160	<	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];
150	>	* Increases the internal storage of this collection, if necessary,
151	>	* to ensure that it can hold at least the given number of elements.
152	>	*
153	>	* @param minCapacity the desired minimum capacity
154	>	* @since TBD
155	>	*/
156	>	/* public */ void ensureCapacity(int minCapacity) {
157	>	int needed;
158	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
159	>	grow(needed);
160	>	// checkInvariants();
161		}
162
163		/**
164	<	* Doubles the capacity of this deque.  Call only when full, i.e.,
165	<	* when head and tail have wrapped around to become equal.
166	<	*/
167	<	private void doubleCapacity() {
168	<	assert head == tail;
169	<	int p = head;
170	<	int n = elements.length;
171	<	int r = n - p; // number of elements to the right of p
172	<	int newCapacity = n << 1;
173	<	if (newCapacity < 0)
174	<	throw new IllegalStateException("Sorry, deque too big");
175	<	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;
164	>	* Minimizes the internal storage of this collection.
165	>	*
166	>	* @since TBD
167	>	*/
168	>	/* public */ void trimToSize() {
169	>	int size;
170	>	if ((size = size()) + 1 < elements.length) {
171	>	elements = toArray(new Object[size + 1]);
172	>	head = 0;
173	>	tail = size;
174	>	}
175	>	// checkInvariants();
176		}
177
178		/**
#	Line 140 | Line 180 | public class ArrayDeque<E> extends Abstr
180		* sufficient to hold 16 elements.
181		*/
182		public ArrayDeque() {
183	<	elements = new Object[16];
183	>	elements = new Object[16 + 1];
184		}
185
186		/**
187		* Constructs an empty array deque with an initial capacity
188		* sufficient to hold the specified number of elements.
189		*
190	<	* @param numElements  lower bound on initial capacity of the deque
190	>	* @param numElements lower bound on initial capacity of the deque
191		*/
192		public ArrayDeque(int numElements) {
193	<	allocateElements(numElements);
193	>	elements =
194	>	new Object[(numElements < 1) ? 1 :
195	>	(numElements == Integer.MAX_VALUE) ? Integer.MAX_VALUE :
196	>	numElements + 1];
197		}
198
199		/**
#	Line 164 | Line 207 | public class ArrayDeque<E> extends Abstr
207		* @throws NullPointerException if the specified collection is null
208		*/
209		public ArrayDeque(Collection<? extends E> c) {
210	<	allocateElements(c.size());
211	<	addAll(c);
210	>	this(c.size());
211	>	copyElements(c);
212	>	}
213	>
214	>	/**
215	>	* Circularly increments i, mod modulus.
216	>	* Precondition and postcondition: 0 <= i < modulus.
217	>	*/
218	>	static final int inc(int i, int modulus) {
219	>	if (++i >= modulus) i = 0;
220	>	return i;
221	>	}
222	>
223	>	/**
224	>	* Circularly decrements i, mod modulus.
225	>	* Precondition and postcondition: 0 <= i < modulus.
226	>	*/
227	>	static final int dec(int i, int modulus) {
228	>	if (--i < 0) i = modulus - 1;
229	>	return i;
230	>	}
231	>
232	>	/**
233	>	* Circularly adds the given distance to index i, mod modulus.
234	>	* Precondition: 0 <= i < modulus, 0 <= distance <= modulus.
235	>	* @return index 0 <= i < modulus
236	>	*/
237	>	static final int inc(int i, int distance, int modulus) {
238	>	if ((i += distance) - modulus >= 0) i -= modulus;
239	>	return i;
240	>	}
241	>
242	>	/**
243	>	* Subtracts j from i, mod modulus.
244	>	* Index i must be logically ahead of index j.
245	>	* Precondition: 0 <= i < modulus, 0 <= j < modulus.
246	>	* @return the "circular distance" from j to i; corner case i == j
247	>	* is disambiguated to "empty", returning 0.
248	>	*/
249	>	static final int sub(int i, int j, int modulus) {
250	>	if ((i -= j) < 0) i += modulus;
251	>	return i;
252	>	}
253	>
254	>	/**
255	>	* Returns element at array index i.
256	>	* This is a slight abuse of generics, accepted by javac.
257	>	*/
258	>	@SuppressWarnings("unchecked")
259	>	static final <E> E elementAt(Object[] es, int i) {
260	>	return (E) es[i];
261	>	}
262	>
263	>	/**
264	>	* A version of elementAt that checks for null elements.
265	>	* This check doesn't catch all possible comodifications,
266	>	* but does catch ones that corrupt traversal.
267	>	*/
268	>	static final <E> E nonNullElementAt(Object[] es, int i) {
269	>	@SuppressWarnings("unchecked") E e = (E) es[i];
270	>	if (e == null)
271	>	throw new ConcurrentModificationException();
272	>	return e;
273		}
274
275		// The main insertion and extraction methods are addFirst,
#	Line 181 | Line 285 | public class ArrayDeque<E> extends Abstr
285		public void addFirst(E e) {
286		if (e == null)
287		throw new NullPointerException();
288	<	elements[head = (head - 1) & (elements.length - 1)] = e;
288	>	final Object[] es = elements;
289	>	es[head = dec(head, es.length)] = e;
290		if (head == tail)
291	<	doubleCapacity();
291	>	grow(1);
292	>	// checkInvariants();
293		}
294
295		/**
#	Line 197 | Line 303 | public class ArrayDeque<E> extends Abstr
303		public void addLast(E e) {
304		if (e == null)
305		throw new NullPointerException();
306	<	elements[tail] = e;
307	<	if ( (tail = (tail + 1) & (elements.length - 1)) == head)
308	<	doubleCapacity();
306	>	final Object[] es = elements;
307	>	es[tail] = e;
308	>	if (head == (tail = inc(tail, es.length)))
309	>	grow(1);
310	>	// checkInvariants();
311	>	}
312	>
313	>	/**
314	>	* Adds all of the elements in the specified collection at the end
315	>	* of this deque, as if by calling {@link #addLast} on each one,
316	>	* in the order that they are returned by the collection's iterator.
317	>	*
318	>	* @param c the elements to be inserted into this deque
319	>	* @return {@code true} if this deque changed as a result of the call
320	>	* @throws NullPointerException if the specified collection or any
321	>	*         of its elements are null
322	>	*/
323	>	public boolean addAll(Collection<? extends E> c) {
324	>	final int s, needed;
325	>	if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0)
326	>	grow(needed);
327	>	copyElements(c);
328	>	// checkInvariants();
329	>	return size() > s;
330	>	}
331	>
332	>	private void copyElements(Collection<? extends E> c) {
333	>	c.forEach(this::addLast);
334		}
335
336		/**
#	Line 230 | Line 361 | public class ArrayDeque<E> extends Abstr
361		* @throws NoSuchElementException {@inheritDoc}
362		*/
363		public E removeFirst() {
364	<	E x = pollFirst();
365	<	if (x == null)
364	>	E e = pollFirst();
365	>	if (e == null)
366		throw new NoSuchElementException();
367	<	return x;
367	>	// checkInvariants();
368	>	return e;
369		}
370
371		/**
372		* @throws NoSuchElementException {@inheritDoc}
373		*/
374		public E removeLast() {
375	<	E x = pollLast();
376	<	if (x == null)
375	>	E e = pollLast();
376	>	if (e == null)
377		throw new NoSuchElementException();
378	<	return x;
378	>	// checkInvariants();
379	>	return e;
380		}
381
382		public E pollFirst() {
383	<	int h = head;
384	<	@SuppressWarnings("unchecked")
385	<	E result = (E) elements[h];
386	<	// Element is null if deque empty
387	<	if (result != null) {
388	<	elements[h] = null; // Must null out slot
256	<	head = (h + 1) & (elements.length - 1);
383	>	final Object[] es;
384	>	final int h;
385	>	E e = elementAt(es = elements, h = head);
386	>	if (e != null) {
387	>	es[h] = null;
388	>	head = inc(h, es.length);
389		}
390	<	return result;
390	>	// checkInvariants();
391	>	return e;
392		}
393
394		public E pollLast() {
395	<	int t = (tail - 1) & (elements.length - 1);
396	<	@SuppressWarnings("unchecked")
397	<	E result = (E) elements[t];
398	<	if (result != null) {
399	<	elements[t] = null;
400	<	tail = t;
401	<	}
269	<	return result;
395	>	final Object[] es;
396	>	final int t;
397	>	E e = elementAt(es = elements, t = dec(tail, es.length));
398	>	if (e != null)
399	>	es[tail = t] = null;
400	>	// checkInvariants();
401	>	return e;
402		}
403
404		/**
405		* @throws NoSuchElementException {@inheritDoc}
406		*/
407		public E getFirst() {
408	<	@SuppressWarnings("unchecked")
409	<	E result = (E) elements[head];
278	<	if (result == null)
408	>	E e = elementAt(elements, head);
409	>	if (e == null)
410		throw new NoSuchElementException();
411	<	return result;
411	>	// checkInvariants();
412	>	return e;
413		}
414
415		/**
416		* @throws NoSuchElementException {@inheritDoc}
417		*/
418		public E getLast() {
419	<	@SuppressWarnings("unchecked")
420	<	E result = (E) elements[(tail - 1) & (elements.length - 1)];
421	<	if (result == null)
419	>	final Object[] es = elements;
420	>	E e = elementAt(es, dec(tail, es.length));
421	>	if (e == null)
422		throw new NoSuchElementException();
423	<	return result;
423	>	// checkInvariants();
424	>	return e;
425		}
426
294	–	@SuppressWarnings("unchecked")
427		public E peekFirst() {
428	<	// elements[head] is null if deque empty
429	<	return (E) elements[head];
428	>	// checkInvariants();
429	>	return elementAt(elements, head);
430		}
431
300	–	@SuppressWarnings("unchecked")
432		public E peekLast() {
433	<	return (E) elements[(tail - 1) & (elements.length - 1)];
433	>	// checkInvariants();
434	>	final Object[] es;
435	>	return elementAt(es = elements, dec(tail, es.length));
436		}
437
438		/**
#	Line 316 | Line 449 | public class ArrayDeque<E> extends Abstr
449		*/
450		public boolean removeFirstOccurrence(Object o) {
451		if (o != null) {
452	<	int mask = elements.length - 1;
453	<	int i = head;
454	<	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
455	<	if (o.equals(x)) {
456	<	delete(i);
457	<	return true;
458	<	}
452	>	final Object[] es = elements;
453	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
454	>	; i = 0, to = end) {
455	>	for (; i < to; i++)
456	>	if (o.equals(es[i])) {
457	>	delete(i);
458	>	return true;
459	>	}
460	>	if (to == end) break;
461		}
462		}
463		return false;
#	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)) {
484	<	delete(i);
485	<	return true;
486	<	}
480	>	final Object[] es = elements;
481	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
482	>	; i = es.length, to = end) {
483	>	for (i--; i > to - 1; i--)
484	>	if (o.equals(es[i])) {
485	>	delete(i);
486	>	return true;
487	>	}
488	>	if (to == end) break;
489		}
490		}
491		return false;
#	Line 386 | Line 523 | public class ArrayDeque<E> extends Abstr
523		/**
524		* Retrieves and removes the head of the queue represented by this deque.
525		*
526	<	* This method differs from {@link #poll poll} only in that it throws an
527	<	* exception if this deque is empty.
526	>	* This method differs from {@link #poll() poll()} only in that it
527	>	* throws an exception if this deque is empty.
528		*
529		* <p>This method is equivalent to {@link #removeFirst}.
530		*
#	Line 468 | Line 605 | public class ArrayDeque<E> extends Abstr
605		return removeFirst();
606		}
607
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	–
608		/**
609	<	* Removes the element at the specified position in the elements array,
610	<	* adjusting head and tail as necessary.  This can result in motion of
611	<	* elements backwards or forwards in the array.
609	>	* Removes the element at the specified position in the elements array.
610	>	* This can result in forward or backwards motion of array elements.
611	>	* We optimize for least element motion.
612		*
613		* <p>This method is called delete rather than remove to emphasize
614		* that its semantics differ from those of {@link List#remove(int)}.
615		*
616	<	* @return true if elements moved backwards
616	>	* @return true if elements near tail moved backwards
617		*/
618	<	private boolean delete(int i) {
619	<	checkInvariants();
620	<	final Object[] elements = this.elements;
621	<	final int mask = elements.length - 1;
622	<	final int h = head;
623	<	final int t = tail;
624	<	final int front = (i - h) & mask;
625	<	final int back  = (t - i) & mask;
626	<
498	<	// Invariant: head <= i < tail mod circularity
499	<	if (front >= ((t - h) & mask))
500	<	throw new ConcurrentModificationException();
501	<
502	<	// Optimize for least element motion
618	>	boolean delete(int i) {
619	>	// checkInvariants();
620	>	final Object[] es = elements;
621	>	final int capacity = es.length;
622	>	final int h, t;
623	>	// number of elements before to-be-deleted elt
624	>	final int front = sub(i, h = head, capacity);
625	>	// number of elements after to-be-deleted elt
626	>	final int back = sub(t = tail, i, capacity) - 1;
627		if (front < back) {
628	+	// move front elements forwards
629		if (h <= i) {
630	<	System.arraycopy(elements, h, elements, h + 1, front);
630	>	System.arraycopy(es, h, es, h + 1, front);
631		} else { // Wrap around
632	<	System.arraycopy(elements, 0, elements, 1, i);
633	<	elements[0] = elements[mask];
634	<	System.arraycopy(elements, h, elements, h + 1, mask - h);
632	>	System.arraycopy(es, 0, es, 1, i);
633	>	es[0] = es[capacity - 1];
634	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
635		}
636	<	elements[h] = null;
637	<	head = (h + 1) & mask;
636	>	es[h] = null;
637	>	head = inc(h, capacity);
638	>	// checkInvariants();
639		return false;
640		} else {
641	<	if (i < t) { // Copy the null tail as well
642	<	System.arraycopy(elements, i + 1, elements, i, back);
643	<	tail = t - 1;
641	>	// move back elements backwards
642	>	tail = dec(t, capacity);
643	>	if (i <= tail) {
644	>	System.arraycopy(es, i + 1, es, i, back);
645		} else { // Wrap around
646	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
647	<	elements[mask] = elements[0];
648	<	System.arraycopy(elements, 1, elements, 0, t);
522	<	tail = (t - 1) & mask;
646	>	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
647	>	es[capacity - 1] = es[0];
648	>	System.arraycopy(es, 1, es, 0, t - 1);
649		}
650	+	es[tail] = null;
651	+	// checkInvariants();
652		return true;
653		}
654		}
#	Line 533 | Line 661 | public class ArrayDeque<E> extends Abstr
661		* @return the number of elements in this deque
662		*/
663		public int size() {
664	<	return (tail - head) & (elements.length - 1);
664	>	return sub(tail, head, elements.length);
665		}
666
667		/**
#	Line 562 | Line 690 | public class ArrayDeque<E> extends Abstr
690		}
691
692		private class DeqIterator implements Iterator<E> {
693	<	/**
694	<	* Index of element to be returned by subsequent call to next.
567	<	*/
568	<	private int cursor = head;
693	>	/** Index of element to be returned by subsequent call to next. */
694	>	int cursor;
695
696	<	/**
697	<	* Tail recorded at construction (also in remove), to stop
572	<	* iterator and also to check for comodification.
573	<	*/
574	<	private int fence = tail;
696	>	/** Number of elements yet to be returned. */
697	>	int remaining = size();
698
699		/**
700		* Index of element returned by most recent call to next.
701		* Reset to -1 if element is deleted by a call to remove.
702		*/
703	<	private int lastRet = -1;
703	>	int lastRet = -1;
704
705	<	public boolean hasNext() {
706	<	return cursor != fence;
705	>	DeqIterator() { cursor = head; }
706	>
707	>	public final boolean hasNext() {
708	>	return remaining > 0;
709		}
710
711		public E next() {
712	<	if (cursor == fence)
712	>	if (remaining <= 0)
713		throw new NoSuchElementException();
714	<	@SuppressWarnings("unchecked")
715	<	E result = (E) elements[cursor];
716	<	// This check doesn't catch all possible comodifications,
717	<	// but does catch the ones that corrupt traversal
718	<	if (tail != fence || result == null)
719	<	throw new ConcurrentModificationException();
720	<	lastRet = cursor;
721	<	cursor = (cursor + 1) & (elements.length - 1);
722	<	return result;
714	>	final Object[] es = elements;
715	>	E e = nonNullElementAt(es, cursor);
716	>	cursor = inc(lastRet = cursor, es.length);
717	>	remaining--;
718	>	return e;
719	>	}
720	>
721	>	void postDelete(boolean leftShifted) {
722	>	if (leftShifted)
723	>	cursor = dec(cursor, elements.length);
724		}
725
726	<	public void remove() {
726	>	public final void remove() {
727		if (lastRet < 0)
728		throw new IllegalStateException();
729	<	if (delete(lastRet)) { // if left-shifted, undo increment in next()
604	<	cursor = (cursor - 1) & (elements.length - 1);
605	<	fence = tail;
606	<	}
729	>	postDelete(delete(lastRet));
730		lastRet = -1;
731		}
732	+
733	+	public void forEachRemaining(Consumer<? super E> action) {
734	+	Objects.requireNonNull(action);
735	+	int r;
736	+	if ((r = remaining) <= 0)
737	+	return;
738	+	remaining = 0;
739	+	final Object[] es = elements;
740	+	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
741	+	throw new ConcurrentModificationException();
742	+	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
743	+	; i = 0, to = end) {
744	+	for (; i < to; i++)
745	+	action.accept(elementAt(es, i));
746	+	if (to == end) {
747	+	if (end != tail)
748	+	throw new ConcurrentModificationException();
749	+	lastRet = dec(end, es.length);
750	+	break;
751	+	}
752	+	}
753	+	}
754	+	}
755	+
756	+	private class DescendingIterator extends DeqIterator {
757	+	DescendingIterator() { cursor = dec(tail, elements.length); }
758	+
759	+	public final E next() {
760	+	if (remaining <= 0)
761	+	throw new NoSuchElementException();
762	+	final Object[] es = elements;
763	+	E e = nonNullElementAt(es, cursor);
764	+	cursor = dec(lastRet = cursor, es.length);
765	+	remaining--;
766	+	return e;
767	+	}
768	+
769	+	void postDelete(boolean leftShifted) {
770	+	if (!leftShifted)
771	+	cursor = inc(cursor, elements.length);
772	+	}
773	+
774	+	public final void forEachRemaining(Consumer<? super E> action) {
775	+	Objects.requireNonNull(action);
776	+	int r;
777	+	if ((r = remaining) <= 0)
778	+	return;
779	+	remaining = 0;
780	+	final Object[] es = elements;
781	+	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
782	+	throw new ConcurrentModificationException();
783	+	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
784	+	; i = es.length - 1, to = end) {
785	+	// hotspot generates faster code than for: i >= to !
786	+	for (; i > to - 1; i--)
787	+	action.accept(elementAt(es, i));
788	+	if (to == end) {
789	+	if (end != head)
790	+	throw new ConcurrentModificationException();
791	+	lastRet = end;
792	+	break;
793	+	}
794	+	}
795	+	}
796		}
797
798		/**
799	<	* This class is nearly a mirror-image of DeqIterator, using tail
800	<	* instead of head for initial cursor, and head instead of tail
801	<	* for fence.
802	<	*/
803	<	private class DescendingIterator implements Iterator<E> {
804	<	private int cursor = tail;
805	<	private int fence = head;
806	<	private int lastRet = -1;
799	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
800	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
801	>	* deque.
802	>	*
803	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
804	>	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
805	>	* {@link Spliterator#NONNULL}.  Overriding implementations should document
806	>	* the reporting of additional characteristic values.
807	>	*
808	>	* @return a {@code Spliterator} over the elements in this deque
809	>	* @since 1.8
810	>	*/
811	>	public Spliterator<E> spliterator() {
812	>	return new DeqSpliterator();
813	>	}
814	>
815	>	final class DeqSpliterator implements Spliterator<E> {
816	>	private int fence;      // -1 until first use
817	>	private int cursor;     // current index, modified on traverse/split
818
819	<	public boolean hasNext() {
820	<	return cursor != fence;
819	>	/** Constructs late-binding spliterator over all elements. */
820	>	DeqSpliterator() {
821	>	this.fence = -1;
822		}
823
824	<	public E next() {
825	<	if (cursor == fence)
826	<	throw new NoSuchElementException();
827	<	cursor = (cursor - 1) & (elements.length - 1);
828	<	@SuppressWarnings("unchecked")
829	<	E result = (E) elements[cursor];
631	<	if (head != fence || result == null)
632	<	throw new ConcurrentModificationException();
633	<	lastRet = cursor;
634	<	return result;
824	>	/** Constructs spliterator over the given range. */
825	>	DeqSpliterator(int origin, int fence) {
826	>	// assert 0 <= origin && origin < elements.length;
827	>	// assert 0 <= fence && fence < elements.length;
828	>	this.cursor = origin;
829	>	this.fence = fence;
830		}
831
832	<	public void remove() {
833	<	if (lastRet < 0)
834	<	throw new IllegalStateException();
835	<	if (!delete(lastRet)) {
836	<	cursor = (cursor + 1) & (elements.length - 1);
837	<	fence = head;
832	>	/** Ensures late-binding initialization; then returns fence. */
833	>	private int getFence() { // force initialization
834	>	int t;
835	>	if ((t = fence) < 0) {
836	>	t = fence = tail;
837	>	cursor = head;
838	>	}
839	>	return t;
840	>	}
841	>
842	>	public DeqSpliterator trySplit() {
843	>	final Object[] es = elements;
844	>	final int i, n;
845	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
846	>	? null
847	>	: new DeqSpliterator(i, cursor = inc(i, n, es.length));
848	>	}
849	>
850	>	public void forEachRemaining(Consumer<? super E> action) {
851	>	if (action == null)
852	>	throw new NullPointerException();
853	>	final int end = getFence(), cursor = this.cursor;
854	>	final Object[] es = elements;
855	>	if (cursor != end) {
856	>	this.cursor = end;
857	>	// null check at both ends of range is sufficient
858	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
859	>	throw new ConcurrentModificationException();
860	>	for (int i = cursor, to = (i <= end) ? end : es.length;
861	>	; i = 0, to = end) {
862	>	for (; i < to; i++)
863	>	action.accept(elementAt(es, i));
864	>	if (to == end) break;
865	>	}
866	>	}
867	>	}
868	>
869	>	public boolean tryAdvance(Consumer<? super E> action) {
870	>	Objects.requireNonNull(action);
871	>	final Object[] es = elements;
872	>	if (fence < 0) { fence = tail; cursor = head; } // late-binding
873	>	final int i;
874	>	if ((i = cursor) == fence)
875	>	return false;
876	>	E e = nonNullElementAt(es, i);
877	>	cursor = inc(i, es.length);
878	>	action.accept(e);
879	>	return true;
880	>	}
881	>
882	>	public long estimateSize() {
883	>	return sub(getFence(), cursor, elements.length);
884	>	}
885	>
886	>	public int characteristics() {
887	>	return Spliterator.NONNULL
888	>	| Spliterator.ORDERED
889	>	| Spliterator.SIZED
890	>	| Spliterator.SUBSIZED;
891	>	}
892	>	}
893	>
894	>	/**
895	>	* @throws NullPointerException {@inheritDoc}
896	>	*/
897	>	public void forEach(Consumer<? super E> action) {
898	>	Objects.requireNonNull(action);
899	>	final Object[] es = elements;
900	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
901	>	; i = 0, to = end) {
902	>	for (; i < to; i++)
903	>	action.accept(elementAt(es, i));
904	>	if (to == end) {
905	>	if (end != tail) throw new ConcurrentModificationException();
906	>	break;
907		}
644	–	lastRet = -1;
908		}
909	+	// checkInvariants();
910	+	}
911	+
912	+	/**
913	+	* Replaces each element of this deque with the result of applying the
914	+	* operator to that element, as specified by {@link List#replaceAll}.
915	+	*
916	+	* @param operator the operator to apply to each element
917	+	* @since TBD
918	+	*/
919	+	/* public */ void replaceAll(java.util.function.UnaryOperator<E> operator) {
920	+	Objects.requireNonNull(operator);
921	+	final Object[] es = elements;
922	+	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
923	+	; i = 0, to = end) {
924	+	for (; i < to; i++)
925	+	es[i] = operator.apply(elementAt(es, i));
926	+	if (to == end) {
927	+	if (end != tail) throw new ConcurrentModificationException();
928	+	break;
929	+	}
930	+	}
931	+	// checkInvariants();
932	+	}
933	+
934	+	/**
935	+	* @throws NullPointerException {@inheritDoc}
936	+	*/
937	+	public boolean removeIf(Predicate<? super E> filter) {
938	+	Objects.requireNonNull(filter);
939	+	return bulkRemove(filter);
940	+	}
941	+
942	+	/**
943	+	* @throws NullPointerException {@inheritDoc}
944	+	*/
945	+	public boolean removeAll(Collection<?> c) {
946	+	Objects.requireNonNull(c);
947	+	return bulkRemove(e -> c.contains(e));
948	+	}
949	+
950	+	/**
951	+	* @throws NullPointerException {@inheritDoc}
952	+	*/
953	+	public boolean retainAll(Collection<?> c) {
954	+	Objects.requireNonNull(c);
955	+	return bulkRemove(e -> !c.contains(e));
956	+	}
957	+
958	+	/** Implementation of bulk remove methods. */
959	+	private boolean bulkRemove(Predicate<? super E> filter) {
960	+	// checkInvariants();
961	+	final Object[] es = elements;
962	+	// Optimize for initial run of survivors
963	+	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
964	+	; i = 0, to = end) {
965	+	for (; i < to; i++)
966	+	if (filter.test(elementAt(es, i)))
967	+	return bulkRemoveModified(filter, i);
968	+	if (to == end) {
969	+	if (end != tail) throw new ConcurrentModificationException();
970	+	break;
971	+	}
972	+	}
973	+	return false;
974	+	}
975	+
976	+	// A tiny bit set implementation
977	+
978	+	private static long[] nBits(int n) {
979	+	return new long[((n - 1) >> 6) + 1];
980	+	}
981	+	private static void setBit(long[] bits, int i) {
982	+	bits[i >> 6] |= 1L << i;
983	+	}
984	+	private static boolean isClear(long[] bits, int i) {
985	+	return (bits[i >> 6] & (1L << i)) == 0;
986	+	}
987	+
988	+	/**
989	+	* Helper for bulkRemove, in case of at least one deletion.
990	+	* Tolerate predicates that reentrantly access the collection for
991	+	* read (but writers still get CME), so traverse once to find
992	+	* elements to delete, a second pass to physically expunge.
993	+	*
994	+	* @param beg valid index of first element to be deleted
995	+	*/
996	+	private boolean bulkRemoveModified(
997	+	Predicate<? super E> filter, final int beg) {
998	+	final Object[] es = elements;
999	+	final int capacity = es.length;
1000	+	final int end = tail;
1001	+	final long[] deathRow = nBits(sub(end, beg, capacity));
1002	+	deathRow[0] = 1L;   // set bit 0
1003	+	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1004	+	; i = 0, to = end, k -= capacity) {
1005	+	for (; i < to; i++)
1006	+	if (filter.test(elementAt(es, i)))
1007	+	setBit(deathRow, i - k);
1008	+	if (to == end) break;
1009	+	}
1010	+	// a two-finger traversal, with hare i reading, tortoise w writing
1011	+	int w = beg;
1012	+	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1013	+	; w = 0) { // w rejoins i on second leg
1014	+	// In this loop, i and w are on the same leg, with i > w
1015	+	for (; i < to; i++)
1016	+	if (isClear(deathRow, i - k))
1017	+	es[w++] = es[i];
1018	+	if (to == end) break;
1019	+	// In this loop, w is on the first leg, i on the second
1020	+	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1021	+	if (isClear(deathRow, i - k))
1022	+	es[w++] = es[i];
1023	+	if (i >= to) {
1024	+	if (w == capacity) w = 0; // "corner" case
1025	+	break;
1026	+	}
1027	+	}
1028	+	if (end != tail) throw new ConcurrentModificationException();
1029	+	circularClear(es, tail = w, end);
1030	+	// checkInvariants();
1031	+	return true;
1032		}
1033
1034		/**
#	Line 655 | Line 1041 | public class ArrayDeque<E> extends Abstr
1041		*/
1042		public boolean contains(Object o) {
1043		if (o != null) {
1044	<	int mask = elements.length - 1;
1045	<	int i = head;
1046	<	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
1047	<	if (o.equals(x))
1048	<	return true;
1044	>	final Object[] es = elements;
1045	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1046	>	; i = 0, to = end) {
1047	>	for (; i < to; i++)
1048	>	if (o.equals(es[i]))
1049	>	return true;
1050	>	if (to == end) break;
1051		}
1052		}
1053		return false;
#	Line 687 | Line 1075 | public class ArrayDeque<E> extends Abstr
1075		* The deque will be empty after this call returns.
1076		*/
1077		public void clear() {
1078	<	int h = head;
1079	<	int t = tail;
1080	<	if (h != t) { // clear all cells
1081	<	head = tail = 0;
1082	<	int i = h;
1083	<	int mask = elements.length - 1;
1084	<	do {
1085	<	elements[i] = null;
1086	<	i = (i + 1) & mask;
1087	<	} while (i != t);
1078	>	circularClear(elements, head, tail);
1079	>	head = tail = 0;
1080	>	// checkInvariants();
1081	>	}
1082	>
1083	>	/**
1084	>	* Nulls out slots starting at array index i, upto index end.
1085	>	* Condition i == end means "empty" - nothing to do.
1086	>	*/
1087	>	private static void circularClear(Object[] es, int i, int end) {
1088	>	// assert 0 <= i && i < es.length;
1089	>	// assert 0 <= end && end < es.length;
1090	>	for (int to = (i <= end) ? end : es.length;
1091	>	; i = 0, to = end) {
1092	>	for (; i < to; i++) es[i] = null;
1093	>	if (to == end) break;
1094		}
1095		}
1096
#	Line 714 | Line 1108 | public class ArrayDeque<E> extends Abstr
1108		* @return an array containing all of the elements in this deque
1109		*/
1110		public Object[] toArray() {
1111	<	final int head = this.head;
1112	<	final int tail = this.tail;
1113	<	boolean wrap = (tail < head);
1114	<	int end = wrap ? tail + elements.length : tail;
1115	<	Object[] a = Arrays.copyOfRange(elements, head, end);
1116	<	if (wrap)
1117	<	System.arraycopy(elements, 0, a, elements.length - head, tail);
1111	>	return toArray(Object[].class);
1112	>	}
1113	>
1114	>	private <T> T[] toArray(Class<T[]> klazz) {
1115	>	final Object[] es = elements;
1116	>	final T[] a;
1117	>	final int head = this.head, tail = this.tail, end;
1118	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1119	>	// Uses null extension feature of copyOfRange
1120	>	a = Arrays.copyOfRange(es, head, end, klazz);
1121	>	} else {
1122	>	// integer overflow!
1123	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1124	>	System.arraycopy(es, head, a, 0, es.length - head);
1125	>	}
1126	>	if (end != tail)
1127	>	System.arraycopy(es, 0, a, es.length - head, tail);
1128		return a;
1129		}
1130
#	Line 762 | Line 1166 | public class ArrayDeque<E> extends Abstr
1166		*/
1167		@SuppressWarnings("unchecked")
1168		public <T> T[] toArray(T[] a) {
1169	<	final int head = this.head;
1170	<	final int tail = this.tail;
1171	<	boolean wrap = (tail < head);
1172	<	int size = (tail - head) + (wrap ? elements.length : 0);
1173	<	int firstLeg = size - (wrap ? tail : 0);
1174	<	int len = a.length;
1175	<	if (size > len) {
1176	<	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
773	<	a.getClass());
774	<	} else {
775	<	System.arraycopy(elements, head, a, 0, firstLeg);
776	<	if (size < len)
777	<	a[size] = null;
1169	>	final int size;
1170	>	if ((size = size()) > a.length)
1171	>	return toArray((Class<T[]>) a.getClass());
1172	>	final Object[] es = elements;
1173	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1174	>	; i = 0, len = tail) {
1175	>	System.arraycopy(es, i, a, j, len);
1176	>	if ((j += len) == size) break;
1177		}
1178	<	if (wrap)
1179	<	System.arraycopy(elements, 0, a, firstLeg, tail);
1178	>	if (size < a.length)
1179	>	a[size] = null;
1180		return a;
1181		}
1182
#	Line 818 | Line 1217 | public class ArrayDeque<E> extends Abstr
1217		s.writeInt(size());
1218
1219		// Write out elements in order.
1220	<	int mask = elements.length - 1;
1221	<	for (int i = head; i != tail; i = (i + 1) & mask)
1222	<	s.writeObject(elements[i]);
1220	>	final Object[] es = elements;
1221	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1222	>	; i = 0, to = end) {
1223	>	for (; i < to; i++)
1224	>	s.writeObject(es[i]);
1225	>	if (to == end) break;
1226	>	}
1227		}
1228
1229		/**
#	Line 836 | Line 1239 | public class ArrayDeque<E> extends Abstr
1239
1240		// Read in size and allocate array
1241		int size = s.readInt();
1242	<	allocateElements(size);
1243	<	head = 0;
1244	<	tail = size;
1242	>	jsr166.Platform.checkArray(s, Object[].class, size + 1);
1243	>	elements = new Object[size + 1];
1244	>	this.tail = size;
1245
1246		// Read in all elements in the proper order.
1247		for (int i = 0; i < size; i++)
1248		elements[i] = s.readObject();
1249		}
1250
1251	<	public Spliterator<E> spliterator() {
1252	<	return new DeqSpliterator<E>(this, -1, -1);
1253	<	}
1254	<
1255	<	static final class DeqSpliterator<E> implements Spliterator<E> {
1256	<	private final ArrayDeque<E> deq;
1257	<	private int fence;  // -1 until first use
1258	<	private int index;  // current index, modified on traverse/split
1259	<
1260	<	/** Creates new spliterator covering the given array and range */
1261	<	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
1262	<	this.deq = deq;
1263	<	this.index = origin;
1264	<	this.fence = fence;
1265	<	}
1266	<
1267	<	private int getFence() { // force initialization
1268	<	int t;
1269	<	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;
1251	>	/** debugging */
1252	>	void checkInvariants() {
1253	>	// Use head and tail fields with empty slot at tail strategy.
1254	>	// head == tail disambiguates to "empty".
1255	>	try {
1256	>	int capacity = elements.length;
1257	>	// assert 0 <= head && head < capacity;
1258	>	// assert 0 <= tail && tail < capacity;
1259	>	// assert capacity > 0;
1260	>	// assert size() < capacity;
1261	>	// assert head == tail || elements[head] != null;
1262	>	// assert elements[tail] == null;
1263	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1264	>	} catch (Throwable t) {
1265	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1266	>	head, tail, elements.length);
1267	>	System.err.printf("elements=%s%n",
1268	>	Arrays.toString(elements));
1269	>	throw t;
1270		}
1271		}
1272

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