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

Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.99 by jsr166, Sun Oct 30 16:32:40 2016 UTC vs.
Revision 1.110 by jsr166, Sat Nov 5 17:45:44 2016 UTC

#	Line 60 | Line 60 | import java.util.function.UnaryOperator;
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.
72	+	*/
73	+
74		/**
75		* The array in which the elements of the deque are stored.
76		* We guarantee that all array cells not holding deque elements
#	Line 70 | Line 81 | public class ArrayDeque<E> extends Abstr
81		/**
82		* The index of the element at the head of the deque (which is the
83		* element that would be removed by remove() or pop()); or an
84	<	* arbitrary number 0 <= head < elements.length if the deque is empty.
84	>	* arbitrary number 0 <= head < elements.length equal to tail if
85	>	* the deque is empty.
86		*/
87		transient int head;
88
89	<	/** Number of elements in this collection. */
90	<	transient int size;
89	>	/**
90	>	* The index at which the next element would be added to the tail
91	>	* of the deque (via addLast(E), add(E), or push(E)).
92	>	*/
93	>	transient int tail;
94
95		/**
96		* The maximum size of array to allocate.
#	Line 92 | Line 107 | public class ArrayDeque<E> extends Abstr
107		*/
108		private void grow(int needed) {
109		// overflow-conscious code
95	–	// checkInvariants();
110		final int oldCapacity = elements.length;
111		int newCapacity;
112	<	// Double size if small; else grow by 50%
112	>	// Double capacity if small; else grow by 50%
113		int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
114		if (jump < needed
115		|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
116		newCapacity = newCapacity(needed, jump);
117		elements = Arrays.copyOf(elements, newCapacity);
118	<	if (oldCapacity - head < size) {
118	>	// Exceptionally, here tail == head needs to be disambiguated
119	>	if (tail < head || (tail == head && elements[head] != null)) {
120		// wrap around; slide first leg forward to end of array
121		int newSpace = newCapacity - oldCapacity;
122		System.arraycopy(elements, head,
#	Line 136 | Line 151 | public class ArrayDeque<E> extends Abstr
151		* @since TBD
152		*/
153		/* public */ void ensureCapacity(int minCapacity) {
154	<	if (minCapacity > elements.length)
155	<	grow(minCapacity - elements.length);
154	>	int needed;
155	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
156	>	grow(needed);
157		// checkInvariants();
158		}
159
#	Line 147 | Line 163 | public class ArrayDeque<E> extends Abstr
163		* @since TBD
164		*/
165		/* public */ void trimToSize() {
166	<	if (size < elements.length) {
167	<	elements = toArray();
166	>	int size;
167	>	if ((size = size()) + 1 < elements.length) {
168	>	elements = toArray(new Object[size + 1]);
169		head = 0;
170	+	tail = size;
171		}
172		// checkInvariants();
173		}
#	Line 169 | Line 187 | public class ArrayDeque<E> extends Abstr
187		* @param numElements lower bound on initial capacity of the deque
188		*/
189		public ArrayDeque(int numElements) {
190	<	elements = new Object[numElements];
190	>	elements = new Object[Math.max(1, numElements + 1)];
191		}
192
193		/**
#	Line 183 | Line 201 | public class ArrayDeque<E> extends Abstr
201		* @throws NullPointerException if the specified collection is null
202		*/
203		public ArrayDeque(Collection<? extends E> c) {
204	<	Object[] es = c.toArray();
205	<	// defend against c.toArray (incorrectly) not returning Object[]
188	<	// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652)
189	<	if (es.getClass() != Object[].class)
190	<	es = Arrays.copyOf(es, es.length, Object[].class);
191	<	for (Object obj : es)
192	<	Objects.requireNonNull(obj);
193	<	this.elements = es;
194	<	this.size = es.length;
204	>	elements = new Object[c.size() + 1];
205	>	addAll(c);
206		}
207
208		/**
#	Line 222 | Line 233 | public class ArrayDeque<E> extends Abstr
233		}
234
235		/**
236	<	* Returns the array index of the last element.
237	<	* May return invalid index -1 if there are no elements.
236	>	* Subtracts j from i, mod modulus.
237	>	* Index i must be logically ahead of j.
238	>	* Returns the "circular distance" from j to i.
239	>	* Precondition and postcondition: 0 <= i < modulus, 0 <= j < modulus.
240		*/
241	<	final int tail() {
242	<	return add(head, size - 1, elements.length);
241	>	static final int sub(int i, int j, int modulus) {
242	>	if ((i -= j) < 0) i += modulus;
243	>	return i;
244		}
245
246		/**
247		* Returns element at array index i.
248	+	* This is a slight abuse of generics, accepted by javac.
249		*/
250		@SuppressWarnings("unchecked")
251	<	private E elementAt(int i) {
252	<	return (E) elements[i];
251	>	static final <E> E elementAt(Object[] es, int i) {
252	>	return (E) es[i];
253		}
254
255		/**
256		* A version of elementAt that checks for null elements.
257		* This check doesn't catch all possible comodifications,
258	<	* but does catch ones that corrupt traversal.  It's a little
244	<	* surprising that javac allows this abuse of generics.
258	>	* but does catch ones that corrupt traversal.
259		*/
260		static final <E> E nonNullElementAt(Object[] es, int i) {
261		@SuppressWarnings("unchecked") E e = (E) es[i];
#	Line 261 | Line 275 | public class ArrayDeque<E> extends Abstr
275		* @throws NullPointerException if the specified element is null
276		*/
277		public void addFirst(E e) {
278	<	// checkInvariants();
279	<	Objects.requireNonNull(e);
280	<	Object[] es;
281	<	int capacity, h;
282	<	final int s;
269	<	if ((s = size) == (capacity = (es = elements).length)) {
278	>	if (e == null)
279	>	throw new NullPointerException();
280	>	final Object[] es = elements;
281	>	es[head = dec(head, es.length)] = e;
282	>	if (head == tail)
283		grow(1);
271	–	capacity = (es = elements).length;
272	–	}
273	–	if ((h = head - 1) < 0) h = capacity - 1;
274	–	es[head = h] = e;
275	–	size = s + 1;
284		// checkInvariants();
285		}
286
#	Line 285 | Line 293 | public class ArrayDeque<E> extends Abstr
293		* @throws NullPointerException if the specified element is null
294		*/
295		public void addLast(E e) {
296	<	// checkInvariants();
297	<	Objects.requireNonNull(e);
298	<	Object[] es;
299	<	int capacity;
300	<	final int s;
293	<	if ((s = size) == (capacity = (es = elements).length)) {
296	>	if (e == null)
297	>	throw new NullPointerException();
298	>	final Object[] es = elements;
299	>	es[tail] = e;
300	>	if (head == (tail = inc(tail, es.length)))
301		grow(1);
295	–	capacity = (es = elements).length;
296	–	}
297	–	es[add(head, s, capacity)] = e;
298	–	size = s + 1;
302		// checkInvariants();
303		}
304
#	Line 311 | Line 314 | public class ArrayDeque<E> extends Abstr
314		*         of its elements are null
315		*/
316		public boolean addAll(Collection<? extends E> c) {
317	<	final int s = size, needed = c.size() - (elements.length - s);
318	<	if (needed > 0)
317	>	final int s = size(), needed;
318	>	if ((needed = s + c.size() - elements.length + 1) > 0)
319		grow(needed);
320		c.forEach((e) -> addLast(e));
321		// checkInvariants();
322	<	return size > s;
322	>	return size() > s;
323		}
324
325		/**
#	Line 347 | Line 350 | public class ArrayDeque<E> extends Abstr
350		* @throws NoSuchElementException {@inheritDoc}
351		*/
352		public E removeFirst() {
350	–	// checkInvariants();
353		E e = pollFirst();
354		if (e == null)
355		throw new NoSuchElementException();
356	+	// checkInvariants();
357		return e;
358		}
359
#	Line 358 | Line 361 | public class ArrayDeque<E> extends Abstr
361		* @throws NoSuchElementException {@inheritDoc}
362		*/
363		public E removeLast() {
361	–	// checkInvariants();
364		E e = pollLast();
365		if (e == null)
366		throw new NoSuchElementException();
367	+	// checkInvariants();
368		return e;
369		}
370
371		public E pollFirst() {
372	+	final Object[] es;
373	+	final int h;
374	+	E e = elementAt(es = elements, h = head);
375	+	if (e != null) {
376	+	es[h] = null;
377	+	head = inc(h, es.length);
378	+	}
379		// checkInvariants();
370	–	int s, h;
371	–	if ((s = size) <= 0)
372	–	return null;
373	–	final Object[] es = elements;
374	–	@SuppressWarnings("unchecked") E e = (E) es[h = head];
375	–	es[h] = null;
376	–	if (++h >= es.length) h = 0;
377	–	head = h;
378	–	size = s - 1;
380		return e;
381		}
382
383		public E pollLast() {
384	+	final Object[] es;
385	+	final int t;
386	+	E e = elementAt(es = elements, t = dec(tail, es.length));
387	+	if (e != null)
388	+	es[tail = t] = null;
389		// checkInvariants();
384	–	final int s, tail;
385	–	if ((s = size) <= 0)
386	–	return null;
387	–	final Object[] es = elements;
388	–	@SuppressWarnings("unchecked")
389	–	E e = (E) es[tail = add(head, s - 1, es.length)];
390	–	es[tail] = null;
391	–	size = s - 1;
390		return e;
391		}
392
#	Line 396 | Line 394 | public class ArrayDeque<E> extends Abstr
394		* @throws NoSuchElementException {@inheritDoc}
395		*/
396		public E getFirst() {
397	+	E e = elementAt(elements, head);
398	+	if (e == null)
399	+	throw new NoSuchElementException();
400		// checkInvariants();
401	<	if (size <= 0) throw new NoSuchElementException();
401	<	return elementAt(head);
401	>	return e;
402		}
403
404		/**
405		* @throws NoSuchElementException {@inheritDoc}
406		*/
407	–	@SuppressWarnings("unchecked")
407		public E getLast() {
409	–	// checkInvariants();
410	–	final int s;
411	–	if ((s = size) <= 0) throw new NoSuchElementException();
408		final Object[] es = elements;
409	<	return (E) es[add(head, s - 1, es.length)];
409	>	E e = elementAt(es, dec(tail, es.length));
410	>	if (e == null)
411	>	throw new NoSuchElementException();
412	>	// checkInvariants();
413	>	return e;
414		}
415
416		public E peekFirst() {
417		// checkInvariants();
418	<	return (size <= 0) ? null : elementAt(head);
418	>	return elementAt(elements, head);
419		}
420
421	–	@SuppressWarnings("unchecked")
421		public E peekLast() {
422		// checkInvariants();
423	<	final int s;
424	<	if ((s = size) <= 0) return null;
426	<	final Object[] es = elements;
427	<	return (E) es[add(head, s - 1, es.length)];
423	>	final Object[] es;
424	>	return elementAt(es = elements, dec(tail, es.length));
425		}
426
427		/**
#	Line 442 | Line 439 | public class ArrayDeque<E> extends Abstr
439		public boolean removeFirstOccurrence(Object o) {
440		if (o != null) {
441		final Object[] es = elements;
442	<	int i, end, to, todo;
443	<	todo = (end = (i = head) + size)
447	<	- (to = (es.length - end >= 0) ? end : es.length);
448	<	for (;; to = todo, i = 0, todo = 0) {
442	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
443	>	; i = 0, to = end) {
444		for (; i < to; i++)
445		if (o.equals(es[i])) {
446		delete(i);
447		return true;
448		}
449	<	if (todo == 0) break;
449	>	if (to == end) break;
450		}
451		}
452		return false;
#	Line 472 | Line 467 | public class ArrayDeque<E> extends Abstr
467		public boolean removeLastOccurrence(Object o) {
468		if (o != null) {
469		final Object[] es = elements;
470	<	int i, to, end, todo;
471	<	todo = (to = ((end = (i = tail()) - size) >= -1) ? end : -1) - end;
472	<	for (;; to = (i = es.length - 1) - todo, todo = 0) {
478	<	for (; i > to; i--)
470	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
471	>	; i = es.length, to = end) {
472	>	for (i--; i > to - 1; i--)
473		if (o.equals(es[i])) {
474		delete(i);
475		return true;
476		}
477	<	if (todo == 0) break;
477	>	if (to == end) break;
478		}
479		}
480		return false;
#	Line 608 | Line 602 | public class ArrayDeque<E> extends Abstr
602		* <p>This method is called delete rather than remove to emphasize
603		* that its semantics differ from those of {@link List#remove(int)}.
604		*
605	<	* @return true if elements moved backwards
605	>	* @return true if elements near tail moved backwards
606		*/
607		boolean delete(int i) {
608		// checkInvariants();
609		final Object[] es = elements;
610		final int capacity = es.length;
611		final int h = head;
612	<	int front;              // number of elements before to-be-deleted elt
613	<	if ((front = i - h) < 0) front += capacity;
614	<	final int back = size - front - 1; // number of elements after
612	>	// number of elements before to-be-deleted elt
613	>	final int front = sub(i, h, capacity);
614	>	final int back = size() - front - 1; // number of elements after
615		if (front < back) {
616		// move front elements forwards
617		if (h <= i) {
#	Line 628 | Line 622 | public class ArrayDeque<E> extends Abstr
622		System.arraycopy(es, h, es, h + 1, front - (i + 1));
623		}
624		es[h] = null;
625	<	if ((head = (h + 1)) >= capacity) head = 0;
632	<	size--;
625	>	head = inc(h, capacity);
626		// checkInvariants();
627		return false;
628		} else {
629		// move back elements backwards
630	<	int tail = tail();
630	>	tail = dec(tail, capacity);
631		if (i <= tail) {
632		System.arraycopy(es, i + 1, es, i, back);
633		} else { // Wrap around
#	Line 644 | Line 637 | public class ArrayDeque<E> extends Abstr
637		System.arraycopy(es, 1, es, 0, back - firstLeg - 1);
638		}
639		es[tail] = null;
647	–	size--;
640		// checkInvariants();
641		return true;
642		}
#	Line 658 | Line 650 | public class ArrayDeque<E> extends Abstr
650		* @return the number of elements in this deque
651		*/
652		public int size() {
653	<	return size;
653	>	return sub(tail, head, elements.length);
654		}
655
656		/**
#	Line 667 | Line 659 | public class ArrayDeque<E> extends Abstr
659		* @return {@code true} if this deque contains no elements
660		*/
661		public boolean isEmpty() {
662	<	return size == 0;
662	>	return head == tail;
663		}
664
665		/**
#	Line 691 | Line 683 | public class ArrayDeque<E> extends Abstr
683		int cursor;
684
685		/** Number of elements yet to be returned. */
686	<	int remaining = size;
686	>	int remaining = size();
687
688		/**
689		* Index of element returned by most recent call to next.
#	Line 711 | Line 703 | public class ArrayDeque<E> extends Abstr
703		final Object[] es = elements;
704		E e = nonNullElementAt(es, cursor);
705		lastRet = cursor;
706	<	if (++cursor >= es.length) cursor = 0;
706	>	cursor = inc(cursor, es.length);
707		remaining--;
708		return e;
709		}
710
711		void postDelete(boolean leftShifted) {
712		if (leftShifted)
713	<	if (--cursor < 0) cursor = elements.length - 1;
713	>	cursor = dec(cursor, elements.length);
714		}
715
716		public final void remove() {
#	Line 730 | Line 722 | public class ArrayDeque<E> extends Abstr
722
723		public void forEachRemaining(Consumer<? super E> action) {
724		Objects.requireNonNull(action);
725	<	final int k;
726	<	if ((k = remaining) > 0) {
727	<	remaining = 0;
728	<	ArrayDeque.forEachRemaining(action, elements, cursor, k);
729	<	if ((lastRet = cursor + k - 1) >= elements.length)
730	<	lastRet -= elements.length;
725	>	int r;
726	>	if ((r = remaining) <= 0)
727	>	return;
728	>	remaining = 0;
729	>	final Object[] es = elements;
730	>	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
731	>	throw new ConcurrentModificationException();
732	>	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
733	>	; i = 0, to = end) {
734	>	for (; i < to; i++)
735	>	action.accept(elementAt(es, i));
736	>	if (to == end) {
737	>	if (end != tail)
738	>	throw new ConcurrentModificationException();
739	>	lastRet = dec(end, es.length);
740	>	break;
741	>	}
742		}
743		}
744		}
745
746		private class DescendingIterator extends DeqIterator {
747	<	DescendingIterator() { cursor = tail(); }
747	>	DescendingIterator() { cursor = dec(tail, elements.length); }
748
749		public final E next() {
750		if (remaining <= 0)
#	Line 749 | Line 752 | public class ArrayDeque<E> extends Abstr
752		final Object[] es = elements;
753		E e = nonNullElementAt(es, cursor);
754		lastRet = cursor;
755	<	if (--cursor < 0) cursor = es.length - 1;
755	>	cursor = dec(cursor, es.length);
756		remaining--;
757		return e;
758		}
759
760		void postDelete(boolean leftShifted) {
761		if (!leftShifted)
762	<	if (++cursor >= elements.length) cursor = 0;
762	>	cursor = inc(cursor, elements.length);
763		}
764
765		public final void forEachRemaining(Consumer<? super E> action) {
766		Objects.requireNonNull(action);
767	<	final int k;
768	<	if ((k = remaining) > 0) {
769	<	remaining = 0;
770	<	final Object[] es = elements;
771	<	int i, end, to, todo;
772	<	todo = (to = ((end = (i = cursor) - k) >= -1) ? end : -1) - end;
773	<	for (;; to = (i = es.length - 1) - todo, todo = 0) {
774	<	for (; i > to; i--)
775	<	action.accept(nonNullElementAt(es, i));
776	<	if (todo == 0) break;
767	>	int r;
768	>	if ((r = remaining) <= 0)
769	>	return;
770	>	remaining = 0;
771	>	final Object[] es = elements;
772	>	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
773	>	throw new ConcurrentModificationException();
774	>	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
775	>	; i = es.length - 1, to = end) {
776	>	// hotspot generates faster code than for: i >= to !
777	>	for (; i > to - 1; i--)
778	>	action.accept(elementAt(es, i));
779	>	if (to == end) {
780	>	if (end != head)
781	>	throw new ConcurrentModificationException();
782	>	lastRet = head;
783	>	break;
784		}
775	–	if ((lastRet = cursor - (k - 1)) < 0)
776	–	lastRet += es.length;
785		}
786		}
787		}
#	Line 792 | Line 800 | public class ArrayDeque<E> extends Abstr
800		* @since 1.8
801		*/
802		public Spliterator<E> spliterator() {
803	<	return new ArrayDequeSpliterator();
803	>	return new DeqSpliterator();
804		}
805
806	<	final class ArrayDequeSpliterator implements Spliterator<E> {
807	<	private int cursor;
808	<	private int remaining; // -1 until late-binding first use
806	>	final class DeqSpliterator implements Spliterator<E> {
807	>	private int fence;      // -1 until first use
808	>	private int cursor;     // current index, modified on traverse/split
809
810		/** Constructs late-binding spliterator over all elements. */
811	<	ArrayDequeSpliterator() {
812	<	this.remaining = -1;
811	>	DeqSpliterator() {
812	>	this.fence = -1;
813		}
814
815	<	/** Constructs spliterator over the given slice. */
816	<	ArrayDequeSpliterator(int cursor, int count) {
817	<	this.cursor = cursor;
818	<	this.remaining = count;
815	>	/** Constructs spliterator over the given range. */
816	>	DeqSpliterator(int origin, int fence) {
817	>	this.cursor = origin;
818	>	this.fence = fence;
819		}
820
821	<	/** Ensures late-binding initialization; then returns remaining. */
822	<	private int remaining() {
823	<	if (remaining < 0) {
821	>	/** Ensures late-binding initialization; then returns fence. */
822	>	private int getFence() { // force initialization
823	>	int t;
824	>	if ((t = fence) < 0) {
825	>	t = fence = tail;
826		cursor = head;
817	–	remaining = size;
827		}
828	<	return remaining;
828	>	return t;
829		}
830
831	<	public ArrayDequeSpliterator trySplit() {
832	<	final int mid;
833	<	if ((mid = remaining() >> 1) > 0) {
834	<	int oldCursor = cursor;
835	<	cursor = add(cursor, mid, elements.length);
836	<	remaining -= mid;
828	<	return new ArrayDequeSpliterator(oldCursor, mid);
829	<	}
830	<	return null;
831	>	public DeqSpliterator trySplit() {
832	>	final Object[] es = elements;
833	>	final int i, n;
834	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
835	>	? null
836	>	: new DeqSpliterator(i, cursor = add(i, n, es.length));
837		}
838
839		public void forEachRemaining(Consumer<? super E> action) {
840	<	Objects.requireNonNull(action);
841	<	final int k = remaining(); // side effect!
842	<	remaining = 0;
843	<	ArrayDeque.forEachRemaining(action, elements, cursor, k);
840	>	if (action == null)
841	>	throw new NullPointerException();
842	>	final int end = getFence(), cursor = this.cursor;
843	>	final Object[] es = elements;
844	>	if (cursor != end) {
845	>	this.cursor = end;
846	>	// null check at both ends of range is sufficient
847	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
848	>	throw new ConcurrentModificationException();
849	>	for (int i = cursor, to = (i <= end) ? end : es.length;
850	>	; i = 0, to = end) {
851	>	for (; i < to; i++)
852	>	action.accept(elementAt(es, i));
853	>	if (to == end) break;
854	>	}
855	>	}
856		}
857
858		public boolean tryAdvance(Consumer<? super E> action) {
859	<	Objects.requireNonNull(action);
860	<	final int k;
861	<	if ((k = remaining()) <= 0)
859	>	if (action == null)
860	>	throw new NullPointerException();
861	>	int t, i;
862	>	if ((t = fence) < 0) t = getFence();
863	>	if (t == (i = cursor))
864		return false;
865	<	action.accept(nonNullElementAt(elements, cursor));
866	<	if (++cursor >= elements.length) cursor = 0;
867	<	remaining = k - 1;
865	>	final Object[] es;
866	>	action.accept(nonNullElementAt(es = elements, i));
867	>	cursor = inc(i, es.length);
868		return true;
869		}
870
871		public long estimateSize() {
872	<	return remaining();
872	>	return sub(getFence(), cursor, elements.length);
873		}
874
875		public int characteristics() {
#	Line 860 | Line 880 | public class ArrayDeque<E> extends Abstr
880		}
881		}
882
863	–	@SuppressWarnings("unchecked")
883		public void forEach(Consumer<? super E> action) {
884		Objects.requireNonNull(action);
885		final Object[] es = elements;
886	<	int i, end, to, todo;
887	<	todo = (end = (i = head) + size)
869	<	- (to = (es.length - end >= 0) ? end : es.length);
870	<	for (;; to = todo, i = 0, todo = 0) {
886	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
887	>	; i = 0, to = end) {
888		for (; i < to; i++)
889	<	action.accept((E) es[i]);
890	<	if (todo == 0) break;
889	>	action.accept(elementAt(es, i));
890	>	if (to == end) {
891	>	if (end != tail) throw new ConcurrentModificationException();
892	>	break;
893	>	}
894		}
895		// checkInvariants();
896		}
897
898		/**
879	–	* Calls action on remaining elements, starting at index i and
880	–	* traversing in ascending order.  A variant of forEach that also
881	–	* checks for concurrent modification, for use in iterators.
882	–	*/
883	–	static <E> void forEachRemaining(
884	–	Consumer<? super E> action, Object[] es, int i, int remaining) {
885	–	int end, to, todo;
886	–	todo = (end = i + remaining)
887	–	- (to = (es.length - end >= 0) ? end : es.length);
888	–	for (;; to = todo, i = 0, todo = 0) {
889	–	for (; i < to; i++)
890	–	action.accept(nonNullElementAt(es, i));
891	–	if (todo == 0) break;
892	–	}
893	–	}
894	–
895	–	/**
899		* Replaces each element of this deque with the result of applying the
900		* operator to that element, as specified by {@link List#replaceAll}.
901		*
902		* @param operator the operator to apply to each element
903		* @since TBD
904		*/
902	–	@SuppressWarnings("unchecked")
905		/* public */ void replaceAll(UnaryOperator<E> operator) {
906		Objects.requireNonNull(operator);
907		final Object[] es = elements;
908	<	int i, end, to, todo;
909	<	todo = (end = (i = head) + size)
908	<	- (to = (es.length - end >= 0) ? end : es.length);
909	<	for (;; to = todo, i = 0, todo = 0) {
908	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
909	>	; i = 0, to = end) {
910		for (; i < to; i++)
911	<	es[i] = operator.apply((E) es[i]);
912	<	if (todo == 0) break;
911	>	es[i] = operator.apply(elementAt(es, i));
912	>	if (to == end) {
913	>	if (end != tail) throw new ConcurrentModificationException();
914	>	break;
915	>	}
916		}
917		// checkInvariants();
918		}
#	Line 942 | Line 945 | public class ArrayDeque<E> extends Abstr
945		private boolean bulkRemove(Predicate<? super E> filter) {
946		// checkInvariants();
947		final Object[] es = elements;
948	+	// Optimize for initial run of survivors
949	+	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
950	+	; i = 0, to = end) {
951	+	for (; i < to; i++)
952	+	if (filter.test(elementAt(es, i)))
953	+	return bulkRemoveModified(filter, i, to);
954	+	if (to == end) {
955	+	if (end != tail) throw new ConcurrentModificationException();
956	+	break;
957	+	}
958	+	}
959	+	return false;
960	+	}
961	+
962	+	/**
963	+	* Helper for bulkRemove, in case of at least one deletion.
964	+	* @param i valid index of first element to be deleted
965	+	*/
966	+	private boolean bulkRemoveModified(
967	+	Predicate<? super E> filter, int i, int to) {
968	+	final Object[] es = elements;
969		final int capacity = es.length;
970	<	int i = head, j = i, remaining = size, deleted = 0;
970	>	// a two-finger algorithm, with hare i reading, tortoise j writing
971	>	int j = i++;
972	>	final int end = tail;
973		try {
974	<	for (; remaining > 0; remaining--) {
975	<	@SuppressWarnings("unchecked") E e = (E) es[i];
976	<	if (filter.test(e))
977	<	deleted++;
978	<	else {
979	<	if (j != i)
980	<	es[j] = e;
981	<	if (++j >= capacity) j = 0;
974	>	for (;; j = 0) {    // j rejoins i on second leg
975	>	E e;
976	>	// In this loop, i and j are on the same leg, with i > j
977	>	for (; i < to; i++)
978	>	if (!filter.test(e = elementAt(es, i)))
979	>	es[j++] = e;
980	>	if (to == end) break;
981	>	// In this loop, j is on the first leg, i on the second
982	>	for (i = 0, to = end; i < to && j < capacity; i++)
983	>	if (!filter.test(e = elementAt(es, i)))
984	>	es[j++] = e;
985	>	if (i >= to) {
986	>	if (j == capacity) j = 0; // "corner" case
987	>	break;
988		}
957	–	if (++i >= capacity) i = 0;
989		}
990	<	return deleted > 0;
990	>	return true;
991		} catch (Throwable ex) {
992	<	if (deleted > 0)
993	<	for (; remaining > 0; remaining--) {
994	<	es[j] = es[i];
964	<	if (++i >= capacity) i = 0;
965	<	if (++j >= capacity) j = 0;
966	<	}
992	>	// copy remaining elements
993	>	for (; i != end; i = inc(i, capacity), j = inc(j, capacity))
994	>	es[j] = es[i];
995		throw ex;
996		} finally {
997	<	size -= deleted;
998	<	clearSlice(es, j, deleted);
997	>	if (end != tail) throw new ConcurrentModificationException();
998	>	circularClear(es, tail = j, end);
999		// checkInvariants();
1000		}
1001		}
#	Line 983 | Line 1011 | public class ArrayDeque<E> extends Abstr
1011		public boolean contains(Object o) {
1012		if (o != null) {
1013		final Object[] es = elements;
1014	<	int i, end, to, todo;
1015	<	todo = (end = (i = head) + size)
988	<	- (to = (es.length - end >= 0) ? end : es.length);
989	<	for (;; to = todo, i = 0, todo = 0) {
1014	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1015	>	; i = 0, to = end) {
1016		for (; i < to; i++)
1017		if (o.equals(es[i]))
1018		return true;
1019	<	if (todo == 0) break;
1019	>	if (to == end) break;
1020		}
1021		}
1022		return false;
#	Line 1018 | Line 1044 | public class ArrayDeque<E> extends Abstr
1044		* The deque will be empty after this call returns.
1045		*/
1046		public void clear() {
1047	<	clearSlice(elements, head, size);
1048	<	size = head = 0;
1047	>	circularClear(elements, head, tail);
1048	>	head = tail = 0;
1049		// checkInvariants();
1050		}
1051
1052		/**
1053	<	* Nulls out count elements, starting at array index i.
1053	>	* Nulls out slots starting at array index i, upto index end.
1054		*/
1055	<	private static void clearSlice(Object[] es, int i, int count) {
1056	<	int end, to, todo;
1057	<	todo = (end = i + count)
1032	<	- (to = (es.length - end >= 0) ? end : es.length);
1033	<	for (;; to = todo, i = 0, todo = 0) {
1055	>	private static void circularClear(Object[] es, int i, int end) {
1056	>	for (int to = (i <= end) ? end : es.length;
1057	>	; i = 0, to = end) {
1058		Arrays.fill(es, i, to, null);
1059	<	if (todo == 0) break;
1059	>	if (to == end) break;
1060		}
1061		}
1062
#	Line 1055 | Line 1079 | public class ArrayDeque<E> extends Abstr
1079
1080		private <T> T[] toArray(Class<T[]> klazz) {
1081		final Object[] es = elements;
1058	–	final int capacity = es.length;
1059	–	final int head = this.head, end = head + size;
1082		final T[] a;
1083	<	if (end >= 0) {
1083	>	final int size = size(), head = this.head, end;
1084	>	final int len = Math.min(size, es.length - head);
1085	>	if ((end = head + size) >= 0) {
1086		a = Arrays.copyOfRange(es, head, end, klazz);
1087		} else {
1088		// integer overflow!
1089		a = Arrays.copyOfRange(es, 0, size, klazz);
1090	<	System.arraycopy(es, head, a, 0, capacity - head);
1090	>	System.arraycopy(es, head, a, 0, len);
1091		}
1092	<	if (end - capacity > 0)
1093	<	System.arraycopy(es, 0, a, capacity - head, end - capacity);
1092	>	if (tail < head)
1093	>	System.arraycopy(es, 0, a, len, tail);
1094		return a;
1095		}
1096
#	Line 1109 | Line 1133 | public class ArrayDeque<E> extends Abstr
1133		@SuppressWarnings("unchecked")
1134		public <T> T[] toArray(T[] a) {
1135		final int size;
1136	<	if ((size = this.size) > a.length)
1136	>	if ((size = size()) > a.length)
1137		return toArray((Class<T[]>) a.getClass());
1138		final Object[] es = elements;
1139	<	final int head = this.head, end = head + size;
1140	<	final int front = (es.length - end >= 0) ? size : es.length - head;
1141	<	System.arraycopy(es, head, a, 0, front);
1142	<	if (front < size)
1143	<	System.arraycopy(es, 0, a, front, size - front);
1139	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1140	>	; i = 0, len = tail) {
1141	>	System.arraycopy(es, i, a, j, len);
1142	>	if ((j += len) == size) break;
1143	>	}
1144		if (size < a.length)
1145		a[size] = null;
1146		return a;
#	Line 1156 | Line 1180 | public class ArrayDeque<E> extends Abstr
1180		s.defaultWriteObject();
1181
1182		// Write out size
1183	<	s.writeInt(size);
1183	>	s.writeInt(size());
1184
1185		// Write out elements in order.
1186		final Object[] es = elements;
1187	<	int i, end, to, todo;
1188	<	todo = (end = (i = head) + size)
1165	<	- (to = (es.length - end >= 0) ? end : es.length);
1166	<	for (;; to = todo, i = 0, todo = 0) {
1187	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1188	>	; i = 0, to = end) {
1189		for (; i < to; i++)
1190		s.writeObject(es[i]);
1191	<	if (todo == 0) break;
1191	>	if (to == end) break;
1192		}
1193		}
1194
#	Line 1182 | Line 1204 | public class ArrayDeque<E> extends Abstr
1204		s.defaultReadObject();
1205
1206		// Read in size and allocate array
1207	<	elements = new Object[size = s.readInt()];
1207	>	int size = s.readInt();
1208	>	elements = new Object[size + 1];
1209	>	this.tail = size;
1210
1211		// Read in all elements in the proper order.
1212		for (int i = 0; i < size; i++)
#	Line 1193 | Line 1217 | public class ArrayDeque<E> extends Abstr
1217		void checkInvariants() {
1218		try {
1219		int capacity = elements.length;
1220	<	// assert size >= 0 && size <= capacity;
1221	<	// assert head >= 0;
1222	<	// assert capacity == 0 || head < capacity;
1223	<	// assert size == 0 || elements[head] != null;
1224	<	// assert size == 0 || elements[tail()] != null;
1225	<	// assert size == capacity || elements[dec(head, capacity)] == null;
1226	<	// assert size == capacity || elements[inc(tail(), capacity)] == null;
1220	>	// assert head >= 0 && head < capacity;
1221	>	// assert tail >= 0 && tail < capacity;
1222	>	// assert capacity > 0;
1223	>	// assert size() < capacity;
1224	>	// assert head == tail || elements[head] != null;
1225	>	// assert elements[tail] == null;
1226	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1227		} catch (Throwable t) {
1228	<	System.err.printf("head=%d size=%d capacity=%d%n",
1229	<	head, size, elements.length);
1228	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1229	>	head, tail, elements.length);
1230		System.err.printf("elements=%s%n",
1231		Arrays.toString(elements));
1232		throw t;

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