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root/jsr166/jsr166/src/main/java/util/ArrayDeque.java

Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.84 by jsr166, Sun Oct 23 16:08:46 2016 UTC vs.
Revision 1.133 by jsr166, Sat Feb 24 22:04:18 2018 UTC

#	Line 9 | Line 9 | import java.io.Serializable;
9		import java.util.function.Consumer;
10		import java.util.function.Predicate;
11		import java.util.function.UnaryOperator;
12	+	import jdk.internal.misc.SharedSecrets;
13
14		/**
15		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 50 | Line 51 | import java.util.function.UnaryOperator;
51		* Iterator} interfaces.
52		*
53		* <p>This class is a member of the
54	<	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
54	>	* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
55		* Java Collections Framework</a>.
56		*
57		* @author  Josh Bloch and Doug Lea
#	Line 60 | Line 61 | import java.util.function.UnaryOperator;
61		public class ArrayDeque<E> extends AbstractCollection<E>
62		implements Deque<E>, Cloneable, Serializable
63		{
64	+	/*
65	+	* VMs excel at optimizing simple array loops where indices are
66	+	* incrementing or decrementing over a valid slice, e.g.
67	+	*
68	+	* for (int i = start; i < end; i++) ... elements[i]
69	+	*
70	+	* Because in a circular array, elements are in general stored in
71	+	* two disjoint such slices, we help the VM by writing unusual
72	+	* nested loops for all traversals over the elements.  Having only
73	+	* one hot inner loop body instead of two or three eases human
74	+	* maintenance and encourages VM loop inlining into the caller.
75	+	*/
76	+
77		/**
78		* The array in which the elements of the deque are stored.
79	<	* We guarantee that all array cells not holding deque elements
80	<	* are always null.
79	>	* All array cells not holding deque elements are always null.
80	>	* The array always has at least one null slot (at tail).
81		*/
82		transient Object[] elements;
83
84		/**
85		* The index of the element at the head of the deque (which is the
86		* element that would be removed by remove() or pop()); or an
87	<	* arbitrary number 0 <= head < elements.length if the deque is empty.
87	>	* arbitrary number 0 <= head < elements.length equal to tail if
88	>	* the deque is empty.
89		*/
90		transient int head;
91
92	<	/** Number of elements in this collection. */
93	<	transient int size;
92	>	/**
93	>	* The index at which the next element would be added to the tail
94	>	* of the deque (via addLast(E), add(E), or push(E));
95	>	* elements[tail] is always null.
96	>	*/
97	>	transient int tail;
98
99		/**
100		* The maximum size of array to allocate.
#	Line 92 | Line 111 | public class ArrayDeque<E> extends Abstr
111		*/
112		private void grow(int needed) {
113		// overflow-conscious code
114	<	// checkInvariants();
96	<	int oldCapacity = elements.length;
114	>	final int oldCapacity = elements.length;
115		int newCapacity;
116	<	// Double size if small; else grow by 50%
116	>	// Double capacity if small; else grow by 50%
117		int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
118		if (jump < needed
119		|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
120		newCapacity = newCapacity(needed, jump);
121	<	elements = Arrays.copyOf(elements, newCapacity);
122	<	if (oldCapacity - head < size) {
121	>	final Object[] es = elements = Arrays.copyOf(elements, newCapacity);
122	>	// Exceptionally, here tail == head needs to be disambiguated
123	>	if (tail < head || (tail == head && es[head] != null)) {
124		// wrap around; slide first leg forward to end of array
125		int newSpace = newCapacity - oldCapacity;
126	<	System.arraycopy(elements, head,
127	<	elements, head + newSpace,
126	>	System.arraycopy(es, head,
127	>	es, head + newSpace,
128		oldCapacity - head);
129	<	Arrays.fill(elements, head, head + newSpace, null);
130	<	head += newSpace;
129	>	for (int i = head, to = (head += newSpace); i < to; i++)
130	>	es[i] = null;
131		}
132		// checkInvariants();
133		}
134
135		/** Capacity calculation for edge conditions, especially overflow. */
136		private int newCapacity(int needed, int jump) {
137	<	int oldCapacity = elements.length;
119	<	int minCapacity;
137	>	final int oldCapacity = elements.length, minCapacity;
138		if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
139		if (minCapacity < 0)
140		throw new IllegalStateException("Sorry, deque too big");
#	Line 137 | Line 155 | public class ArrayDeque<E> extends Abstr
155		* @since TBD
156		*/
157		/* public */ void ensureCapacity(int minCapacity) {
158	<	if (minCapacity > elements.length)
159	<	grow(minCapacity - elements.length);
158	>	int needed;
159	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
160	>	grow(needed);
161		// checkInvariants();
162		}
163
#	Line 148 | Line 167 | public class ArrayDeque<E> extends Abstr
167		* @since TBD
168		*/
169		/* public */ void trimToSize() {
170	<	if (size < elements.length) {
171	<	elements = toArray();
170	>	int size;
171	>	if ((size = size()) + 1 < elements.length) {
172	>	elements = toArray(new Object[size + 1]);
173		head = 0;
174	+	tail = size;
175		}
176		// checkInvariants();
177		}
#	Line 170 | Line 191 | public class ArrayDeque<E> extends Abstr
191		* @param numElements lower bound on initial capacity of the deque
192		*/
193		public ArrayDeque(int numElements) {
194	<	elements = new Object[numElements];
194	>	elements =
195	>	new Object[(numElements < 1) ? 1 :
196	>	(numElements == Integer.MAX_VALUE) ? Integer.MAX_VALUE :
197	>	numElements + 1];
198		}
199
200		/**
#	Line 184 | Line 208 | public class ArrayDeque<E> extends Abstr
208		* @throws NullPointerException if the specified collection is null
209		*/
210		public ArrayDeque(Collection<? extends E> c) {
211	<	Object[] elements = c.toArray();
212	<	// defend against c.toArray (incorrectly) not returning Object[]
189	<	// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652)
190	<	if (elements.getClass() != Object[].class)
191	<	elements = Arrays.copyOf(elements, size, Object[].class);
192	<	for (Object obj : elements)
193	<	Objects.requireNonNull(obj);
194	<	size = elements.length;
195	<	this.elements = elements;
211	>	this(c.size());
212	>	copyElements(c);
213		}
214
215		/**
216	<	* Increments i, mod modulus.
216	>	* Circularly increments i, mod modulus.
217		* Precondition and postcondition: 0 <= i < modulus.
218		*/
219		static final int inc(int i, int modulus) {
220	<	if (++i == modulus) i = 0;
220	>	if (++i >= modulus) i = 0;
221		return i;
222		}
223
224		/**
225	<	* Decrements i, mod modulus.
225	>	* Circularly decrements i, mod modulus.
226		* Precondition and postcondition: 0 <= i < modulus.
227		*/
228		static final int dec(int i, int modulus) {
229	<	if (--i < 0) i += modulus;
229	>	if (--i < 0) i = modulus - 1;
230		return i;
231		}
232
233		/**
234	<	* Adds i and j, mod modulus.
235	<	* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus.
234	>	* Circularly adds the given distance to index i, mod modulus.
235	>	* Precondition: 0 <= i < modulus, 0 <= distance <= modulus.
236	>	* @return index 0 <= i < modulus
237		*/
238	<	static final int add(int i, int j, int modulus) {
239	<	if ((i += j) - modulus >= 0) i -= modulus;
238	>	static final int inc(int i, int distance, int modulus) {
239	>	if ((i += distance) - modulus >= 0) i -= modulus;
240		return i;
241		}
242
243		/**
244	<	* Returns the array index of the last element.
245	<	* May return invalid index -1 if there are no elements.
244	>	* Subtracts j from i, mod modulus.
245	>	* Index i must be logically ahead of index j.
246	>	* Precondition: 0 <= i < modulus, 0 <= j < modulus.
247	>	* @return the "circular distance" from j to i; corner case i == j
248	>	* is disambiguated to "empty", returning 0.
249		*/
250	<	final int tail() {
251	<	return add(head, size - 1, elements.length);
250	>	static final int sub(int i, int j, int modulus) {
251	>	if ((i -= j) < 0) i += modulus;
252	>	return i;
253		}
254
255		/**
256		* Returns element at array index i.
257	+	* This is a slight abuse of generics, accepted by javac.
258		*/
259		@SuppressWarnings("unchecked")
260	<	final E elementAt(int i) {
261	<	return (E) elements[i];
260	>	static final <E> E elementAt(Object[] es, int i) {
261	>	return (E) es[i];
262		}
263
264		/**
#	Line 243 | Line 266 | public class ArrayDeque<E> extends Abstr
266		* This check doesn't catch all possible comodifications,
267		* but does catch ones that corrupt traversal.
268		*/
269	<	E checkedElementAt(Object[] elements, int i) {
270	<	@SuppressWarnings("unchecked") E e = (E) elements[i];
269	>	static final <E> E nonNullElementAt(Object[] es, int i) {
270	>	@SuppressWarnings("unchecked") E e = (E) es[i];
271		if (e == null)
272		throw new ConcurrentModificationException();
273		return e;
#	Line 261 | Line 284 | public class ArrayDeque<E> extends Abstr
284		* @throws NullPointerException if the specified element is null
285		*/
286		public void addFirst(E e) {
287	<	// checkInvariants();
288	<	Objects.requireNonNull(e);
289	<	final Object[] elements;
290	<	final int capacity, s;
291	<	if ((s = size) == (capacity = (elements = this.elements).length))
292	<	addFirstSlowPath(e);
270	<	else
271	<	elements[head = dec(head, capacity)] = e;
272	<	size = s + 1;
287	>	if (e == null)
288	>	throw new NullPointerException();
289	>	final Object[] es = elements;
290	>	es[head = dec(head, es.length)] = e;
291	>	if (head == tail)
292	>	grow(1);
293		// checkInvariants();
294		}
295
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	–
296		/**
297		* Inserts the specified element at the end of this deque.
298		*
#	Line 288 | Line 302 | public class ArrayDeque<E> extends Abstr
302		* @throws NullPointerException if the specified element is null
303		*/
304		public void addLast(E e) {
305	+	if (e == null)
306	+	throw new NullPointerException();
307	+	final Object[] es = elements;
308	+	es[tail] = e;
309	+	if (head == (tail = inc(tail, es.length)))
310	+	grow(1);
311		// 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;
312		}
313
314		/**
315		* Adds all of the elements in the specified collection at the end
316		* of this deque, as if by calling {@link #addLast} on each one,
317	<	* in the order that they are returned by the collection's
313	<	* iterator.
317	>	* in the order that they are returned by the collection's iterator.
318		*
319		* @param c the elements to be inserted into this deque
320		* @return {@code true} if this deque changed as a result of the call
321		* @throws NullPointerException if the specified collection or any
322		*         of its elements are null
323		*/
320	–	@Override
324		public boolean addAll(Collection<? extends E> c) {
325	+	final int s, needed;
326	+	if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0)
327	+	grow(needed);
328	+	copyElements(c);
329		// checkInvariants();
330	<	Object[] a, elements;
331	<	int newcomers, capacity, s = size;
332	<	if ((newcomers = (a = c.toArray()).length) == 0)
333	<	return false;
334	<	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;
330	>	return size() > s;
331	>	}
332	>
333	>	private void copyElements(Collection<? extends E> c) {
334	>	c.forEach(this::addLast);
335		}
336
337		/**
#	Line 364 | Line 362 | public class ArrayDeque<E> extends Abstr
362		* @throws NoSuchElementException {@inheritDoc}
363		*/
364		public E removeFirst() {
367	–	// checkInvariants();
365		E e = pollFirst();
366		if (e == null)
367		throw new NoSuchElementException();
368	+	// checkInvariants();
369		return e;
370		}
371
#	Line 375 | Line 373 | public class ArrayDeque<E> extends Abstr
373		* @throws NoSuchElementException {@inheritDoc}
374		*/
375		public E removeLast() {
378	–	// checkInvariants();
376		E e = pollLast();
377		if (e == null)
378		throw new NoSuchElementException();
379	+	// checkInvariants();
380		return e;
381		}
382
383		public E pollFirst() {
384	+	final Object[] es;
385	+	final int h;
386	+	E e = elementAt(es = elements, h = head);
387	+	if (e != null) {
388	+	es[h] = null;
389	+	head = inc(h, es.length);
390	+	}
391		// 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;
392		return e;
393		}
394
395		public E pollLast() {
396	+	final Object[] es;
397	+	final int t;
398	+	E e = elementAt(es = elements, t = dec(tail, es.length));
399	+	if (e != null)
400	+	es[tail = t] = null;
401		// checkInvariants();
400	–	final int s, tail;
401	–	if ((s = size) == 0)
402	–	return null;
403	–	final Object[] elements = this.elements;
404	–	@SuppressWarnings("unchecked")
405	–	E e = (E) elements[tail = add(head, s - 1, elements.length)];
406	–	elements[tail] = null;
407	–	size = s - 1;
402		return e;
403		}
404
#	Line 412 | Line 406 | public class ArrayDeque<E> extends Abstr
406		* @throws NoSuchElementException {@inheritDoc}
407		*/
408		public E getFirst() {
409	+	E e = elementAt(elements, head);
410	+	if (e == null)
411	+	throw new NoSuchElementException();
412		// checkInvariants();
413	<	if (size == 0) throw new NoSuchElementException();
417	<	return elementAt(head);
413	>	return e;
414		}
415
416		/**
417		* @throws NoSuchElementException {@inheritDoc}
418		*/
419		public E getLast() {
420	+	final Object[] es = elements;
421	+	E e = elementAt(es, dec(tail, es.length));
422	+	if (e == null)
423	+	throw new NoSuchElementException();
424		// checkInvariants();
425	<	if (size == 0) throw new NoSuchElementException();
426	<	return elementAt(tail());
425	>	return e;
426		}
427
428		public E peekFirst() {
429		// checkInvariants();
430	<	return (size == 0) ? null : elementAt(head);
430	>	return elementAt(elements, head);
431		}
432
433		public E peekLast() {
434		// checkInvariants();
435	<	return (size == 0) ? null : elementAt(tail());
435	>	final Object[] es;
436	>	return elementAt(es = elements, dec(tail, es.length));
437		}
438
439		/**
#	Line 449 | 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();
452		if (o != null) {
453	<	final Object[] elements = this.elements;
454	<	final int capacity = elements.length;
455	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) {
456	<	if (o.equals(elements[i])) {
457	<	delete(i);
458	<	return true;
459	<	}
453	>	final Object[] es = elements;
454	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
455	>	; i = 0, to = end) {
456	>	for (; i < to; i++)
457	>	if (o.equals(es[i])) {
458	>	delete(i);
459	>	return true;
460	>	}
461	>	if (to == end) break;
462		}
463		}
464		return false;
#	Line 477 | Line 478 | public class ArrayDeque<E> extends Abstr
478		*/
479		public boolean removeLastOccurrence(Object o) {
480		if (o != null) {
481	<	final Object[] elements = this.elements;
482	<	final int capacity = elements.length;
483	<	for (int k = size, i = add(head, k - 1, capacity);
484	<	--k >= 0; i = dec(i, capacity)) {
485	<	if (o.equals(elements[i])) {
486	<	delete(i);
487	<	return true;
488	<	}
481	>	final Object[] es = elements;
482	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
483	>	; i = es.length, to = end) {
484	>	for (i--; i > to - 1; i--)
485	>	if (o.equals(es[i])) {
486	>	delete(i);
487	>	return true;
488	>	}
489	>	if (to == end) break;
490		}
491		}
492		return false;
#	Line 522 | Line 524 | public class ArrayDeque<E> extends Abstr
524		/**
525		* Retrieves and removes the head of the queue represented by this deque.
526		*
527	<	* This method differs from {@link #poll poll} only in that it throws an
528	<	* exception if this deque is empty.
527	>	* This method differs from {@link #poll() poll()} only in that it
528	>	* throws an exception if this deque is empty.
529		*
530		* <p>This method is equivalent to {@link #removeFirst}.
531		*
#	Line 612 | Line 614 | public class ArrayDeque<E> extends Abstr
614		* <p>This method is called delete rather than remove to emphasize
615		* that its semantics differ from those of {@link List#remove(int)}.
616		*
617	<	* @return true if elements moved backwards
617	>	* @return true if elements near tail moved backwards
618		*/
619		boolean delete(int i) {
620		// checkInvariants();
621	<	final Object[] elements = this.elements;
622	<	final int capacity = elements.length;
623	<	final int h = head;
624	<	int front;              // number of elements before to-be-deleted elt
625	<	if ((front = i - h) < 0) front += capacity;
626	<	final int back = size - front - 1; // number of elements after
621	>	final Object[] es = elements;
622	>	final int capacity = es.length;
623	>	final int h, t;
624	>	// number of elements before to-be-deleted elt
625	>	final int front = sub(i, h = head, capacity);
626	>	// number of elements after to-be-deleted elt
627	>	final int back = sub(t = tail, i, capacity) - 1;
628		if (front < back) {
629		// move front elements forwards
630		if (h <= i) {
631	<	System.arraycopy(elements, h, elements, h + 1, front);
631	>	System.arraycopy(es, h, es, h + 1, front);
632		} else { // Wrap around
633	<	System.arraycopy(elements, 0, elements, 1, i);
634	<	elements[0] = elements[capacity - 1];
635	<	System.arraycopy(elements, h, elements, h + 1, front - (i + 1));
633	>	System.arraycopy(es, 0, es, 1, i);
634	>	es[0] = es[capacity - 1];
635	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
636		}
637	<	elements[h] = null;
637	>	es[h] = null;
638		head = inc(h, capacity);
636	–	size--;
639		// checkInvariants();
640		return false;
641		} else {
642		// move back elements backwards
643	<	int tail = tail();
643	>	tail = dec(t, capacity);
644		if (i <= tail) {
645	<	System.arraycopy(elements, i + 1, elements, i, back);
645	>	System.arraycopy(es, i + 1, es, i, back);
646		} else { // Wrap around
647	<	int firstLeg = capacity - (i + 1);
648	<	System.arraycopy(elements, i + 1, elements, i, firstLeg);
649	<	elements[capacity - 1] = elements[0];
648	<	System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1);
647	>	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
648	>	es[capacity - 1] = es[0];
649	>	System.arraycopy(es, 1, es, 0, t - 1);
650		}
651	<	elements[tail] = null;
651	<	size--;
651	>	es[tail] = null;
652		// checkInvariants();
653		return true;
654		}
#	Line 662 | Line 662 | public class ArrayDeque<E> extends Abstr
662		* @return the number of elements in this deque
663		*/
664		public int size() {
665	<	return size;
665	>	return sub(tail, head, elements.length);
666		}
667
668		/**
#	Line 671 | 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 size == 0;
674	>	return head == tail;
675		}
676
677		/**
#	Line 695 | Line 695 | public class ArrayDeque<E> extends Abstr
695		int cursor;
696
697		/** Number of elements yet to be returned. */
698	<	int remaining = size;
698	>	int remaining = size();
699
700		/**
701		* Index of element returned by most recent call to next.
#	Line 710 | Line 710 | public class ArrayDeque<E> extends Abstr
710		}
711
712		public E next() {
713	<	if (remaining == 0)
713	>	if (remaining <= 0)
714		throw new NoSuchElementException();
715	<	E e = checkedElementAt(elements, cursor);
716	<	lastRet = cursor;
717	<	cursor = inc(cursor, elements.length);
715	>	final Object[] es = elements;
716	>	E e = nonNullElementAt(es, cursor);
717	>	cursor = inc(lastRet = cursor, es.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
724	>	cursor = dec(cursor, elements.length);
725		}
726
727		public final void remove() {
#	Line 733 | Line 733 | public class ArrayDeque<E> extends Abstr
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;
736	>	int r;
737	>	if ((r = remaining) <= 0)
738	>	return;
739		remaining = 0;
740	<	for (int i = cursor; --k >= 0; i = inc(i, capacity))
741	<	action.accept(checkedElementAt(elements, i));
740	>	final Object[] es = elements;
741	>	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
742	>	throw new ConcurrentModificationException();
743	>	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
744	>	; i = 0, to = end) {
745	>	for (; i < to; i++)
746	>	action.accept(elementAt(es, i));
747	>	if (to == end) {
748	>	if (end != tail)
749	>	throw new ConcurrentModificationException();
750	>	lastRet = dec(end, es.length);
751	>	break;
752	>	}
753	>	}
754		}
755		}
756
757		private class DescendingIterator extends DeqIterator {
758	<	DescendingIterator() { cursor = tail(); }
758	>	DescendingIterator() { cursor = dec(tail, elements.length); }
759
760		public final E next() {
761	<	if (remaining == 0)
761	>	if (remaining <= 0)
762		throw new NoSuchElementException();
763	<	E e = checkedElementAt(elements, cursor);
764	<	lastRet = cursor;
765	<	cursor = dec(cursor, elements.length);
763	>	final Object[] es = elements;
764	>	E e = nonNullElementAt(es, cursor);
765	>	cursor = dec(lastRet = cursor, es.length);
766		remaining--;
767		return e;
768		}
769
770		void postDelete(boolean leftShifted) {
771		if (!leftShifted)
772	<	cursor = inc(cursor, elements.length); // undo dec in next
772	>	cursor = inc(cursor, elements.length);
773		}
774
775		public final void forEachRemaining(Consumer<? super E> action) {
776		Objects.requireNonNull(action);
777	<	final Object[] elements = ArrayDeque.this.elements;
778	<	final int capacity = elements.length;
779	<	int k = remaining;
777	>	int r;
778	>	if ((r = remaining) <= 0)
779	>	return;
780		remaining = 0;
781	<	for (int i = cursor; --k >= 0; i = dec(i, capacity))
782	<	action.accept(checkedElementAt(elements, i));
781	>	final Object[] es = elements;
782	>	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
783	>	throw new ConcurrentModificationException();
784	>	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
785	>	; i = es.length - 1, to = end) {
786	>	// hotspot generates faster code than for: i >= to !
787	>	for (; i > to - 1; i--)
788	>	action.accept(elementAt(es, i));
789	>	if (to == end) {
790	>	if (end != head)
791	>	throw new ConcurrentModificationException();
792	>	lastRet = end;
793	>	break;
794	>	}
795	>	}
796		}
797		}
798
#	Line 785 | Line 810 | public class ArrayDeque<E> extends Abstr
810		* @since 1.8
811		*/
812		public Spliterator<E> spliterator() {
813	<	return new ArrayDequeSpliterator();
813	>	return new DeqSpliterator();
814		}
815
816	<	final class ArrayDequeSpliterator implements Spliterator<E> {
817	<	private int cursor;
818	<	private int remaining; // -1 until late-binding first use
816	>	final class DeqSpliterator implements Spliterator<E> {
817	>	private int fence;      // -1 until first use
818	>	private int cursor;     // current index, modified on traverse/split
819
820		/** Constructs late-binding spliterator over all elements. */
821	<	ArrayDequeSpliterator() {
822	<	this.remaining = -1;
798	<	}
799	<
800	<	/** Constructs spliterator over the given slice. */
801	<	ArrayDequeSpliterator(int cursor, int count) {
802	<	this.cursor = cursor;
803	<	this.remaining = count;
821	>	DeqSpliterator() {
822	>	this.fence = -1;
823		}
824
825	<	/** Ensures late-binding initialization; then returns remaining. */
826	<	private int remaining() {
827	<	if (remaining < 0) {
825	>	/** Constructs spliterator over the given range. */
826	>	DeqSpliterator(int origin, int fence) {
827	>	// assert 0 <= origin && origin < elements.length;
828	>	// assert 0 <= fence && fence < elements.length;
829	>	this.cursor = origin;
830	>	this.fence = fence;
831	>	}
832	>
833	>	/** Ensures late-binding initialization; then returns fence. */
834	>	private int getFence() { // force initialization
835	>	int t;
836	>	if ((t = fence) < 0) {
837	>	t = fence = tail;
838		cursor = head;
810	–	remaining = size;
839		}
840	<	return remaining;
840	>	return t;
841		}
842
843	<	public ArrayDequeSpliterator trySplit() {
844	<	final int mid;
845	<	if ((mid = remaining() >> 1) > 0) {
846	<	int oldCursor = cursor;
847	<	cursor = add(cursor, mid, elements.length);
848	<	remaining -= mid;
821	<	return new ArrayDequeSpliterator(oldCursor, mid);
822	<	}
823	<	return null;
843	>	public DeqSpliterator trySplit() {
844	>	final Object[] es = elements;
845	>	final int i, n;
846	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
847	>	? null
848	>	: new DeqSpliterator(i, cursor = inc(i, n, es.length));
849		}
850
851		public void forEachRemaining(Consumer<? super E> action) {
852	<	Objects.requireNonNull(action);
853	<	final Object[] elements = ArrayDeque.this.elements;
854	<	final int capacity = elements.length;
855	<	int k = remaining();
856	<	remaining = 0;
857	<	for (int i = cursor; --k >= 0; i = inc(i, capacity))
858	<	action.accept(checkedElementAt(elements, i));
852	>	if (action == null)
853	>	throw new NullPointerException();
854	>	final int end = getFence(), cursor = this.cursor;
855	>	final Object[] es = elements;
856	>	if (cursor != end) {
857	>	this.cursor = end;
858	>	// null check at both ends of range is sufficient
859	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
860	>	throw new ConcurrentModificationException();
861	>	for (int i = cursor, to = (i <= end) ? end : es.length;
862	>	; i = 0, to = end) {
863	>	for (; i < to; i++)
864	>	action.accept(elementAt(es, i));
865	>	if (to == end) break;
866	>	}
867	>	}
868		}
869
870		public boolean tryAdvance(Consumer<? super E> action) {
871		Objects.requireNonNull(action);
872	<	if (remaining() == 0)
872	>	final Object[] es = elements;
873	>	if (fence < 0) { fence = tail; cursor = head; } // late-binding
874	>	final int i;
875	>	if ((i = cursor) == fence)
876		return false;
877	<	action.accept(checkedElementAt(elements, cursor));
878	<	cursor = inc(cursor, elements.length);
879	<	remaining--;
877	>	E e = nonNullElementAt(es, i);
878	>	cursor = inc(i, es.length);
879	>	action.accept(e);
880		return true;
881		}
882
883		public long estimateSize() {
884	<	return remaining();
884	>	return sub(getFence(), cursor, elements.length);
885		}
886
887		public int characteristics() {
#	Line 855 | Line 892 | public class ArrayDeque<E> extends Abstr
892		}
893		}
894
895	<	@Override
895	>	/**
896	>	* @throws NullPointerException {@inheritDoc}
897	>	*/
898		public void forEach(Consumer<? super E> action) {
860	–	// checkInvariants();
899		Objects.requireNonNull(action);
900	<	final Object[] elements = this.elements;
901	<	final int capacity = elements.length;
902	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
903	<	action.accept(elementAt(i));
900	>	final Object[] es = elements;
901	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
902	>	; i = 0, to = end) {
903	>	for (; i < to; i++)
904	>	action.accept(elementAt(es, i));
905	>	if (to == end) {
906	>	if (end != tail) throw new ConcurrentModificationException();
907	>	break;
908	>	}
909	>	}
910		// checkInvariants();
911		}
912
#	Line 875 | Line 919 | public class ArrayDeque<E> extends Abstr
919		*/
920		/* public */ void replaceAll(UnaryOperator<E> operator) {
921		Objects.requireNonNull(operator);
922	<	final Object[] elements = this.elements;
923	<	final int capacity = elements.length;
924	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
925	<	elements[i] = operator.apply(elementAt(i));
922	>	final Object[] es = elements;
923	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
924	>	; i = 0, to = end) {
925	>	for (; i < to; i++)
926	>	es[i] = operator.apply(elementAt(es, i));
927	>	if (to == end) {
928	>	if (end != tail) throw new ConcurrentModificationException();
929	>	break;
930	>	}
931	>	}
932		// checkInvariants();
933		}
934
935		/**
936		* @throws NullPointerException {@inheritDoc}
937		*/
888	–	@Override
938		public boolean removeIf(Predicate<? super E> filter) {
939		Objects.requireNonNull(filter);
940		return bulkRemove(filter);
#	Line 894 | Line 943 | public class ArrayDeque<E> extends Abstr
943		/**
944		* @throws NullPointerException {@inheritDoc}
945		*/
897	–	@Override
946		public boolean removeAll(Collection<?> c) {
947		Objects.requireNonNull(c);
948		return bulkRemove(e -> c.contains(e));
#	Line 903 | Line 951 | public class ArrayDeque<E> extends Abstr
951		/**
952		* @throws NullPointerException {@inheritDoc}
953		*/
906	–	@Override
954		public boolean retainAll(Collection<?> c) {
955		Objects.requireNonNull(c);
956		return bulkRemove(e -> !c.contains(e));
#	Line 912 | Line 959 | public class ArrayDeque<E> extends Abstr
959		/** Implementation of bulk remove methods. */
960		private boolean bulkRemove(Predicate<? super E> filter) {
961		// checkInvariants();
962	<	final Object[] elements = this.elements;
963	<	final int capacity = elements.length;
964	<	int i = head, j = i, remaining = size, deleted = 0;
965	<	try {
966	<	for (; remaining > 0; remaining--, i = inc(i, capacity)) {
967	<	@SuppressWarnings("unchecked") E e = (E) elements[i];
968	<	if (filter.test(e))
969	<	deleted++;
970	<	else {
971	<	if (j != i)
925	<	elements[j] = e;
926	<	j = inc(j, capacity);
927	<	}
962	>	final Object[] es = elements;
963	>	// Optimize for initial run of survivors
964	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
965	>	; i = 0, to = end) {
966	>	for (; i < to; i++)
967	>	if (filter.test(elementAt(es, i)))
968	>	return bulkRemoveModified(filter, i);
969	>	if (to == end) {
970	>	if (end != tail) throw new ConcurrentModificationException();
971	>	break;
972		}
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();
973		}
974	+	return false;
975	+	}
976	+
977	+	// A tiny bit set implementation
978	+
979	+	private static long[] nBits(int n) {
980	+	return new long[((n - 1) >> 6) + 1];
981	+	}
982	+	private static void setBit(long[] bits, int i) {
983	+	bits[i >> 6] |= 1L << i;
984	+	}
985	+	private static boolean isClear(long[] bits, int i) {
986	+	return (bits[i >> 6] & (1L << i)) == 0;
987	+	}
988	+
989	+	/**
990	+	* Helper for bulkRemove, in case of at least one deletion.
991	+	* Tolerate predicates that reentrantly access the collection for
992	+	* read (but writers still get CME), so traverse once to find
993	+	* elements to delete, a second pass to physically expunge.
994	+	*
995	+	* @param beg valid index of first element to be deleted
996	+	*/
997	+	private boolean bulkRemoveModified(
998	+	Predicate<? super E> filter, final int beg) {
999	+	final Object[] es = elements;
1000	+	final int capacity = es.length;
1001	+	final int end = tail;
1002	+	final long[] deathRow = nBits(sub(end, beg, capacity));
1003	+	deathRow[0] = 1L;   // set bit 0
1004	+	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1005	+	; i = 0, to = end, k -= capacity) {
1006	+	for (; i < to; i++)
1007	+	if (filter.test(elementAt(es, i)))
1008	+	setBit(deathRow, i - k);
1009	+	if (to == end) break;
1010	+	}
1011	+	// a two-finger traversal, with hare i reading, tortoise w writing
1012	+	int w = beg;
1013	+	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1014	+	; w = 0) { // w rejoins i on second leg
1015	+	// In this loop, i and w are on the same leg, with i > w
1016	+	for (; i < to; i++)
1017	+	if (isClear(deathRow, i - k))
1018	+	es[w++] = es[i];
1019	+	if (to == end) break;
1020	+	// In this loop, w is on the first leg, i on the second
1021	+	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1022	+	if (isClear(deathRow, i - k))
1023	+	es[w++] = es[i];
1024	+	if (i >= to) {
1025	+	if (w == capacity) w = 0; // "corner" case
1026	+	break;
1027	+	}
1028	+	}
1029	+	if (end != tail) throw new ConcurrentModificationException();
1030	+	circularClear(es, tail = w, end);
1031	+	// checkInvariants();
1032	+	return true;
1033		}
1034
1035		/**
#	Line 951 | Line 1042 | public class ArrayDeque<E> extends Abstr
1042		*/
1043		public boolean contains(Object o) {
1044		if (o != null) {
1045	<	final Object[] elements = this.elements;
1046	<	final int capacity = elements.length;
1047	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1048	<	if (o.equals(elements[i]))
1049	<	return true;
1045	>	final Object[] es = elements;
1046	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1047	>	; i = 0, to = end) {
1048	>	for (; i < to; i++)
1049	>	if (o.equals(es[i]))
1050	>	return true;
1051	>	if (to == end) break;
1052	>	}
1053		}
1054		return false;
1055		}
#	Line 982 | Line 1076 | public class ArrayDeque<E> extends Abstr
1076		* The deque will be empty after this call returns.
1077		*/
1078		public void clear() {
1079	<	final Object[] elements = this.elements;
1080	<	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;
1079	>	circularClear(elements, head, tail);
1080	>	head = tail = 0;
1081		// checkInvariants();
1082		}
1083
1084		/**
1085	+	* Nulls out slots starting at array index i, upto index end.
1086	+	* Condition i == end means "empty" - nothing to do.
1087	+	*/
1088	+	private static void circularClear(Object[] es, int i, int end) {
1089	+	// assert 0 <= i && i < es.length;
1090	+	// assert 0 <= end && end < es.length;
1091	+	for (int to = (i <= end) ? end : es.length;
1092	+	; i = 0, to = end) {
1093	+	for (; i < to; i++) es[i] = null;
1094	+	if (to == end) break;
1095	+	}
1096	+	}
1097	+
1098	+	/**
1099		* Returns an array containing all of the elements in this deque
1100		* in proper sequence (from first to last element).
1101		*
#	Line 1010 | Line 1109 | public class ArrayDeque<E> extends Abstr
1109		* @return an array containing all of the elements in this deque
1110		*/
1111		public Object[] toArray() {
1112	<	final int head = this.head;
1113	<	final int firstLeg;
1114	<	Object[] a = Arrays.copyOfRange(elements, head, head + size);
1115	<	if ((firstLeg = elements.length - head) < size)
1116	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1112	>	return toArray(Object[].class);
1113	>	}
1114	>
1115	>	private <T> T[] toArray(Class<T[]> klazz) {
1116	>	final Object[] es = elements;
1117	>	final T[] a;
1118	>	final int head = this.head, tail = this.tail, end;
1119	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1120	>	// Uses null extension feature of copyOfRange
1121	>	a = Arrays.copyOfRange(es, head, end, klazz);
1122	>	} else {
1123	>	// integer overflow!
1124	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1125	>	System.arraycopy(es, head, a, 0, es.length - head);
1126	>	}
1127	>	if (end != tail)
1128	>	System.arraycopy(es, 0, a, es.length - head, tail);
1129		return a;
1130		}
1131
#	Line 1056 | Line 1167 | public class ArrayDeque<E> extends Abstr
1167		*/
1168		@SuppressWarnings("unchecked")
1169		public <T> T[] toArray(T[] a) {
1170	<	final Object[] elements = this.elements;
1171	<	final int head = this.head;
1172	<	final int firstLeg;
1173	<	boolean wrap = (firstLeg = elements.length - head) < size;
1174	<	if (size > a.length) {
1175	<	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
1176	<	a.getClass());
1177	<	} else {
1067	<	System.arraycopy(elements, head, a, 0, wrap ? firstLeg : size);
1068	<	if (size < a.length)
1069	<	a[size] = null;
1170	>	final int size;
1171	>	if ((size = size()) > a.length)
1172	>	return toArray((Class<T[]>) a.getClass());
1173	>	final Object[] es = elements;
1174	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1175	>	; i = 0, len = tail) {
1176	>	System.arraycopy(es, i, a, j, len);
1177	>	if ((j += len) == size) break;
1178		}
1179	<	if (wrap)
1180	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1179	>	if (size < a.length)
1180	>	a[size] = null;
1181		return a;
1182		}
1183
#	Line 1107 | Line 1215 | public class ArrayDeque<E> extends Abstr
1215		s.defaultWriteObject();
1216
1217		// Write out size
1218	<	s.writeInt(size);
1218	>	s.writeInt(size());
1219
1220		// Write out elements in order.
1221	<	final Object[] elements = this.elements;
1222	<	final int capacity = elements.length;
1223	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1224	<	s.writeObject(elements[i]);
1221	>	final Object[] es = elements;
1222	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1223	>	; i = 0, to = end) {
1224	>	for (; i < to; i++)
1225	>	s.writeObject(es[i]);
1226	>	if (to == end) break;
1227	>	}
1228		}
1229
1230		/**
#	Line 1128 | Line 1239 | public class ArrayDeque<E> extends Abstr
1239		s.defaultReadObject();
1240
1241		// Read in size and allocate array
1242	<	elements = new Object[size = s.readInt()];
1242	>	int size = s.readInt();
1243	>	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size + 1);
1244	>	elements = new Object[size + 1];
1245	>	this.tail = size;
1246
1247		// Read in all elements in the proper order.
1248		for (int i = 0; i < size; i++)
#	Line 1136 | Line 1250 | public class ArrayDeque<E> extends Abstr
1250		}
1251
1252		/** debugging */
1253	<	private void checkInvariants() {
1253	>	void checkInvariants() {
1254	>	// Use head and tail fields with empty slot at tail strategy.
1255	>	// head == tail disambiguates to "empty".
1256		try {
1257		int capacity = elements.length;
1258	<	assert size >= 0 && size <= capacity;
1259	<	assert head >= 0 && ((capacity == 0 && head == 0 && size == 0)
1260	<	|| head < capacity);
1261	<	assert size == 0
1262	<	|| (elements[head] != null && elements[tail()] != null);
1263	<	assert size == capacity
1264	<	|| (elements[dec(head, capacity)] == null
1149	<	&& elements[inc(tail(), capacity)] == null);
1258	>	// assert 0 <= head && head < capacity;
1259	>	// assert 0 <= tail && tail < capacity;
1260	>	// assert capacity > 0;
1261	>	// assert size() < capacity;
1262	>	// assert head == tail || elements[head] != null;
1263	>	// assert elements[tail] == null;
1264	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1265		} catch (Throwable t) {
1266	<	System.err.printf("head=%d size=%d capacity=%d%n",
1267	<	head, size, elements.length);
1266	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1267	>	head, tail, elements.length);
1268		System.err.printf("elements=%s%n",
1269		Arrays.toString(elements));
1270		throw t;

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