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Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.77 by jsr166, Tue Oct 18 00:33:05 2016 UTC vs.
Revision 1.113 by jsr166, Sun Nov 13 02:10:09 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
110	<	// checkInvariants();
96	<	int oldCapacity = elements.length;
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 115 | Line 130 | public class ArrayDeque<E> extends Abstr
130
131		/** Capacity calculation for edge conditions, especially overflow. */
132		private int newCapacity(int needed, int jump) {
133	<	int oldCapacity = elements.length;
119	<	int minCapacity;
133	>	final int oldCapacity = elements.length, minCapacity;
134		if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
135		if (minCapacity < 0)
136		throw new IllegalStateException("Sorry, deque too big");
#	Line 134 | Line 148 | public class ArrayDeque<E> extends Abstr
148		* to ensure that it can hold at least the given number of elements.
149		*
150		* @param minCapacity the desired minimum capacity
151	<	* @since 9
151	>	* @since TBD
152		*/
153	<	public void ensureCapacity(int minCapacity) {
154	<	if (minCapacity > elements.length)
155	<	grow(minCapacity - elements.length);
153	>	/* public */ void ensureCapacity(int minCapacity) {
154	>	int needed;
155	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
156	>	grow(needed);
157		// checkInvariants();
158		}
159
160		/**
161		* Minimizes the internal storage of this collection.
162		*
163	<	* @since 9
163	>	* @since TBD
164		*/
165	<	public void trimToSize() {
166	<	if (size < elements.length) {
167	<	elements = toArray();
165	>	/* public */ void trimToSize() {
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 170 | 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 184 | 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[] elements = c.toArray();
205	<	// 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;
204	>	elements = new Object[c.size() + 1];
205	>	addAll(c);
206		}
207
208		/**
209	<	* Returns the array index of the last element.
210	<	* May return invalid index -1 if there are no elements.
209	>	* Increments i, mod modulus.
210	>	* Precondition and postcondition: 0 <= i < modulus.
211		*/
212	<	final int tail() {
213	<	return add(head, size - 1, elements.length);
212	>	static final int inc(int i, int modulus) {
213	>	if (++i >= modulus) i = 0;
214	>	return i;
215		}
216
217		/**
218	<	* Adds i and j, mod modulus.
219	<	* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus.
218	>	* Decrements i, mod modulus.
219	>	* Precondition and postcondition: 0 <= i < modulus.
220		*/
221	<	static final int add(int i, int j, int modulus) {
222	<	if ((i += j) - modulus >= 0) i -= modulus;
221	>	static final int dec(int i, int modulus) {
222	>	if (--i < 0) i = modulus - 1;
223		return i;
224		}
225
226		/**
227	<	* Increments i, mod modulus.
228	<	* Precondition and postcondition: 0 <= i < modulus.
227	>	* Adds i and j, mod modulus.
228	>	* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus.
229		*/
230	<	static final int inc(int i, int modulus) {
231	<	if (++i == modulus) i = 0;
230	>	static final int add(int i, int j, int modulus) {
231	>	if ((i += j) - modulus >= 0) i -= modulus;
232		return i;
233		}
234
235		/**
236	<	* Decrements i, mod modulus.
237	<	* Precondition and postcondition: 0 <= i < modulus.
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	<	static final int dec(int i, int modulus) {
242	<	if (--i < 0) i += modulus;
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	<	final 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		/**
#	Line 243 | Line 257 | public class ArrayDeque<E> extends Abstr
257		* This check doesn't catch all possible comodifications,
258		* but does catch ones that corrupt traversal.
259		*/
260	<	E checkedElementAt(Object[] elements, int i) {
261	<	@SuppressWarnings("unchecked") E e = (E) elements[i];
260	>	static final <E> E nonNullElementAt(Object[] es, int i) {
261	>	@SuppressWarnings("unchecked") E e = (E) es[i];
262		if (e == null)
263		throw new ConcurrentModificationException();
264		return e;
#	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[] elements;
281	<	int capacity, s = size;
282	<	while (s == (capacity = (elements = this.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);
284	<	elements[head = dec(head, capacity)] = e;
271	<	size = s + 1;
284	>	// checkInvariants();
285		}
286
287		/**
#	Line 280 | 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[] elements;
299	<	int capacity, s = size;
300	<	while (s == (capacity = (elements = this.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);
302	<	elements[add(head, s, capacity)] = e;
290	<	size = s + 1;
302	>	// checkInvariants();
303		}
304
305		/**
#	Line 301 | Line 313 | public class ArrayDeque<E> extends Abstr
313		* @throws NullPointerException if the specified collection or any
314		*         of its elements are null
315		*/
304	–	@Override
316		public boolean addAll(Collection<? extends E> c) {
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	<	Object[] a, elements;
308	<	int len, capacity, s = size;
309	<	if ((len = (a = c.toArray()).length) == 0)
310	<	return false;
311	<	while ((capacity = (elements = this.elements).length) - s < len)
312	<	grow(len - (capacity - s));
313	<	int i = add(head, s, capacity);
314	<	for (Object x : a) {
315	<	Objects.requireNonNull(x);
316	<	elements[i] = x;
317	<	i = inc(i, capacity);
318	<	size++;
319	<	}
320	<	return true;
322	>	return size() > s;
323		}
324
325		/**
#	Line 348 | Line 350 | public class ArrayDeque<E> extends Abstr
350		* @throws NoSuchElementException {@inheritDoc}
351		*/
352		public E removeFirst() {
353	<	// checkInvariants();
354	<	E x = pollFirst();
353	<	if (x == null)
353	>	E e = pollFirst();
354	>	if (e == null)
355		throw new NoSuchElementException();
356	<	return x;
356	>	// checkInvariants();
357	>	return e;
358		}
359
360		/**
361		* @throws NoSuchElementException {@inheritDoc}
362		*/
363		public E removeLast() {
364	<	// checkInvariants();
365	<	E x = pollLast();
364	<	if (x == null)
364	>	E e = pollLast();
365	>	if (e == null)
366		throw new NoSuchElementException();
367	<	return x;
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();
371	–	final int s, h;
372	–	if ((s = size) == 0)
373	–	return null;
374	–	final Object[] elements = this.elements;
375	–	@SuppressWarnings("unchecked") E e = (E) elements[h = head];
376	–	elements[h] = null;
377	–	head = inc(h, elements.length);
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[] elements = this.elements;
388	–	@SuppressWarnings("unchecked")
389	–	E e = (E) elements[tail = add(head, s - 1, elements.length)];
390	–	elements[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		public E getLast() {
408	+	final Object[] es = elements;
409	+	E e = elementAt(es, dec(tail, es.length));
410	+	if (e == null)
411	+	throw new NoSuchElementException();
412		// checkInvariants();
413	<	if (size == 0) throw new NoSuchElementException();
410	<	return elementAt(tail());
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		public E peekLast() {
422		// checkInvariants();
423	<	return (size == 0) ? null : elementAt(tail());
423	>	final Object[] es;
424	>	return elementAt(es = elements, dec(tail, es.length));
425		}
426
427		/**
#	Line 433 | Line 437 | public class ArrayDeque<E> extends Abstr
437		* @return {@code true} if the deque contained the specified element
438		*/
439		public boolean removeFirstOccurrence(Object o) {
436	–	// checkInvariants();
440		if (o != null) {
441	<	final Object[] elements = this.elements;
442	<	final int capacity = elements.length;
443	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) {
444	<	if (o.equals(elements[i])) {
445	<	delete(i);
446	<	return true;
447	<	}
441	>	final Object[] es = elements;
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 (to == end) break;
450		}
451		}
452		return false;
#	Line 461 | Line 466 | public class ArrayDeque<E> extends Abstr
466		*/
467		public boolean removeLastOccurrence(Object o) {
468		if (o != null) {
469	<	final Object[] elements = this.elements;
470	<	final int capacity = elements.length;
471	<	for (int k = size, i = add(head, k - 1, capacity);
472	<	--k >= 0; i = dec(i, capacity)) {
473	<	if (o.equals(elements[i])) {
474	<	delete(i);
475	<	return true;
476	<	}
469	>	final Object[] es = elements;
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 (to == end) break;
478		}
479		}
480		return false;
#	Line 596 | 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[] elements = this.elements;
610	<	final int capacity = elements.length;
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) {
618	<	System.arraycopy(elements, h, elements, h + 1, front);
618	>	System.arraycopy(es, h, es, h + 1, front);
619		} else { // Wrap around
620	<	System.arraycopy(elements, 0, elements, 1, i);
621	<	elements[0] = elements[capacity - 1];
622	<	System.arraycopy(elements, h, elements, h + 1, front - (i + 1));
620	>	System.arraycopy(es, 0, es, 1, i);
621	>	es[0] = es[capacity - 1];
622	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
623		}
624	<	elements[h] = null;
624	>	es[h] = null;
625		head = inc(h, capacity);
620	–	size--;
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(elements, i + 1, elements, i, back);
632	>	System.arraycopy(es, i + 1, es, i, back);
633		} else { // Wrap around
634		int firstLeg = capacity - (i + 1);
635	<	System.arraycopy(elements, i + 1, elements, i, firstLeg);
636	<	elements[capacity - 1] = elements[0];
637	<	System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1);
635	>	System.arraycopy(es, i + 1, es, i, firstLeg);
636	>	es[capacity - 1] = es[0];
637	>	System.arraycopy(es, 1, es, 0, back - firstLeg - 1);
638		}
639	<	elements[tail] = null;
635	<	size--;
639	>	es[tail] = null;
640		// checkInvariants();
641		return true;
642		}
#	Line 646 | 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 655 | 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 679 | 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 689 | Line 693 | public class ArrayDeque<E> extends Abstr
693
694		DeqIterator() { cursor = head; }
695
692	–	int advance(int i, int modulus) {
693	–	return inc(i, modulus);
694	–	}
695	–
696	–	void doRemove() {
697	–	if (delete(lastRet))
698	–	// if left-shifted, undo advance in next()
699	–	cursor = dec(cursor, elements.length);
700	–	}
701	–
696		public final boolean hasNext() {
697		return remaining > 0;
698		}
699
700	<	public final E next() {
701	<	if (remaining == 0)
700	>	public E next() {
701	>	if (remaining <= 0)
702		throw new NoSuchElementException();
703	<	E e = checkedElementAt(elements, cursor);
703	>	final Object[] es = elements;
704	>	E e = nonNullElementAt(es, cursor);
705		lastRet = cursor;
706	<	cursor = advance(cursor, elements.length);
706	>	cursor = inc(cursor, es.length);
707		remaining--;
708		return e;
709		}
710
711	+	void postDelete(boolean leftShifted) {
712	+	if (leftShifted)
713	+	cursor = dec(cursor, elements.length);
714	+	}
715	+
716		public final void remove() {
717		if (lastRet < 0)
718		throw new IllegalStateException();
719	<	doRemove();
719	>	postDelete(delete(lastRet));
720		lastRet = -1;
721		}
722
723	<	public final void forEachRemaining(Consumer<? super E> action) {
723	>	public void forEachRemaining(Consumer<? super E> action) {
724		Objects.requireNonNull(action);
725	<	final Object[] elements = ArrayDeque.this.elements;
726	<	final int capacity = elements.length;
727	<	int k = remaining;
725	>	int r;
726	>	if ((r = remaining) <= 0)
727	>	return;
728		remaining = 0;
729	<	for (int i = cursor; --k >= 0; i = advance(i, capacity))
730	<	action.accept(checkedElementAt(elements, i));
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	<	@Override int advance(int i, int modulus) {
750	<	return dec(i, modulus);
749	>	public final E next() {
750	>	if (remaining <= 0)
751	>	throw new NoSuchElementException();
752	>	final Object[] es = elements;
753	>	E e = nonNullElementAt(es, cursor);
754	>	lastRet = cursor;
755	>	cursor = dec(cursor, es.length);
756	>	remaining--;
757	>	return e;
758		}
759
760	<	@Override void doRemove() {
761	<	if (!delete(lastRet))
743	<	// if right-shifted, undo advance in next
760	>	void postDelete(boolean leftShifted) {
761	>	if (!leftShifted)
762		cursor = inc(cursor, elements.length);
763		}
764	+
765	+	public final void forEachRemaining(Consumer<? super E> action) {
766	+	Objects.requireNonNull(action);
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 = end;
783	+	break;
784	+	}
785	+	}
786	+	}
787		}
788
789		/**
#	Line 759 | 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;
784	–	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;
795	<	return new ArrayDequeSpliterator(oldCursor, mid);
796	<	}
797	<	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 Object[] elements = ArrayDeque.this.elements;
842	<	final int capacity = elements.length;
843	<	int k = remaining();
844	<	remaining = 0;
845	<	for (int i = cursor; --k >= 0; i = inc(i, capacity))
846	<	action.accept(checkedElementAt(elements, i));
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	<	if (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(checkedElementAt(elements, cursor));
866	<	cursor = inc(cursor, elements.length);
867	<	remaining--;
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 829 | Line 880 | public class ArrayDeque<E> extends Abstr
880		}
881		}
882
832	–	@Override
883		public void forEach(Consumer<? super E> action) {
834	–	// checkInvariants();
884		Objects.requireNonNull(action);
885	<	final Object[] elements = this.elements;
886	<	final int capacity = elements.length;
887	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
888	<	action.accept(elementAt(i));
885	>	final Object[] es = elements;
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(elementAt(es, i));
890	>	if (to == end) {
891	>	if (end != tail) throw new ConcurrentModificationException();
892	>	break;
893	>	}
894	>	}
895		// checkInvariants();
896		}
897
#	Line 845 | Line 900 | public class ArrayDeque<E> extends Abstr
900		* operator to that element, as specified by {@link List#replaceAll}.
901		*
902		* @param operator the operator to apply to each element
903	<	* @since 9
903	>	* @since TBD
904		*/
905	<	public void replaceAll(UnaryOperator<E> operator) {
905	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
906		Objects.requireNonNull(operator);
907	<	final Object[] elements = this.elements;
908	<	final int capacity = elements.length;
909	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
910	<	elements[i] = operator.apply(elementAt(i));
907	>	final Object[] es = elements;
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(elementAt(es, i));
912	>	if (to == end) {
913	>	if (end != tail) throw new ConcurrentModificationException();
914	>	break;
915	>	}
916	>	}
917		// checkInvariants();
918		}
919
920		/**
921		* @throws NullPointerException {@inheritDoc}
922		*/
862	–	@Override
923		public boolean removeIf(Predicate<? super E> filter) {
924		Objects.requireNonNull(filter);
925		return bulkRemove(filter);
#	Line 868 | Line 928 | public class ArrayDeque<E> extends Abstr
928		/**
929		* @throws NullPointerException {@inheritDoc}
930		*/
871	–	@Override
931		public boolean removeAll(Collection<?> c) {
932		Objects.requireNonNull(c);
933		return bulkRemove(e -> c.contains(e));
#	Line 877 | Line 936 | public class ArrayDeque<E> extends Abstr
936		/**
937		* @throws NullPointerException {@inheritDoc}
938		*/
880	–	@Override
939		public boolean retainAll(Collection<?> c) {
940		Objects.requireNonNull(c);
941		return bulkRemove(e -> !c.contains(e));
#	Line 886 | Line 944 | public class ArrayDeque<E> extends Abstr
944		/** Implementation of bulk remove methods. */
945		private boolean bulkRemove(Predicate<? super E> filter) {
946		// checkInvariants();
947	<	final Object[] elements = this.elements;
948	<	final int capacity = elements.length;
949	<	int i = head, j = i, remaining = size, deleted = 0;
950	<	try {
951	<	for (; remaining > 0; remaining--, i = inc(i, capacity)) {
952	<	@SuppressWarnings("unchecked") E e = (E) elements[i];
953	<	if (filter.test(e))
954	<	deleted++;
955	<	else {
956	<	if (j != i)
899	<	elements[j] = e;
900	<	j = inc(j, capacity);
901	<	}
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);
954	>	if (to == end) {
955	>	if (end != tail) throw new ConcurrentModificationException();
956	>	break;
957		}
903	–	return deleted > 0;
904	–	} catch (Throwable ex) {
905	–	for (; remaining > 0;
906	–	remaining--, i = inc(i, capacity), j = inc(j, capacity))
907	–	elements[j] = elements[i];
908	–	throw ex;
909	–	} finally {
910	–	size -= deleted;
911	–	for (; --deleted >= 0; j = inc(j, capacity))
912	–	elements[j] = null;
913	–	// checkInvariants();
958		}
959	+	return false;
960	+	}
961	+
962	+	// A tiny bit set implementation
963	+
964	+	private static long[] nBits(int n) {
965	+	return new long[((n - 1) >> 6) + 1];
966	+	}
967	+	private static void setBit(long[] bits, int i) {
968	+	bits[i >> 6] |= 1L << i;
969	+	}
970	+	private static boolean isClear(long[] bits, int i) {
971	+	return (bits[i >> 6] & (1L << i)) == 0;
972	+	}
973	+
974	+	/**
975	+	* Helper for bulkRemove, in case of at least one deletion.
976	+	* Tolerate predicates that reentrantly access the collection for
977	+	* read (but writers still get CME), so traverse once to find
978	+	* elements to delete, a second pass to physically expunge.
979	+	*
980	+	* @param beg valid index of first element to be deleted
981	+	*/
982	+	private boolean bulkRemoveModified(
983	+	Predicate<? super E> filter, final int beg) {
984	+	final Object[] es = elements;
985	+	final int capacity = es.length;
986	+	final int end = tail;
987	+	final long[] deathRow = nBits(sub(end, beg, capacity));
988	+	deathRow[0] = 1L;   // set bit 0
989	+	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
990	+	; i = 0, to = end, k -= capacity) {
991	+	for (; i < to; i++)
992	+	if (filter.test(elementAt(es, i)))
993	+	setBit(deathRow, i - k);
994	+	if (to == end) break;
995	+	}
996	+	// a two-finger traversal, with hare i reading, tortoise w writing
997	+	int w = beg;
998	+	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
999	+	; w = 0) { // w rejoins i on second leg
1000	+	// In this loop, i and w are on the same leg, with i > w
1001	+	for (; i < to; i++)
1002	+	if (isClear(deathRow, i - k))
1003	+	es[w++] = es[i];
1004	+	if (to == end) break;
1005	+	// In this loop, w is on the first leg, i on the second
1006	+	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1007	+	if (isClear(deathRow, i - k))
1008	+	es[w++] = es[i];
1009	+	if (i >= to) {
1010	+	if (w == capacity) w = 0; // "corner" case
1011	+	break;
1012	+	}
1013	+	}
1014	+	if (end != tail) throw new ConcurrentModificationException();
1015	+	circularClear(es, tail = w, end);
1016	+	// checkInvariants();
1017	+	return true;
1018		}
1019
1020		/**
#	Line 924 | Line 1027 | public class ArrayDeque<E> extends Abstr
1027		*/
1028		public boolean contains(Object o) {
1029		if (o != null) {
1030	<	final Object[] elements = this.elements;
1031	<	final int capacity = elements.length;
1032	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1033	<	if (o.equals(elements[i]))
1034	<	return true;
1030	>	final Object[] es = elements;
1031	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1032	>	; i = 0, to = end) {
1033	>	for (; i < to; i++)
1034	>	if (o.equals(es[i]))
1035	>	return true;
1036	>	if (to == end) break;
1037	>	}
1038		}
1039		return false;
1040		}
#	Line 955 | Line 1061 | public class ArrayDeque<E> extends Abstr
1061		* The deque will be empty after this call returns.
1062		*/
1063		public void clear() {
1064	<	final Object[] elements = this.elements;
1065	<	final int capacity = elements.length;
960	<	final int h = this.head;
961	<	final int s = size;
962	<	if (capacity - h >= s)
963	<	Arrays.fill(elements, h, h + s, null);
964	<	else {
965	<	Arrays.fill(elements, h, capacity, null);
966	<	Arrays.fill(elements, 0, s - capacity + h, null);
967	<	}
968	<	size = head = 0;
1064	>	circularClear(elements, head, tail);
1065	>	head = tail = 0;
1066		// checkInvariants();
1067		}
1068
1069		/**
1070	+	* Nulls out slots starting at array index i, upto index end.
1071	+	*/
1072	+	private static void circularClear(Object[] es, int i, int end) {
1073	+	for (int to = (i <= end) ? end : es.length;
1074	+	; i = 0, to = end) {
1075	+	Arrays.fill(es, i, to, null);
1076	+	if (to == end) break;
1077	+	}
1078	+	}
1079	+
1080	+	/**
1081		* Returns an array containing all of the elements in this deque
1082		* in proper sequence (from first to last element).
1083		*
#	Line 983 | Line 1091 | public class ArrayDeque<E> extends Abstr
1091		* @return an array containing all of the elements in this deque
1092		*/
1093		public Object[] toArray() {
1094	<	final int head = this.head;
1095	<	final int firstLeg;
1096	<	Object[] a = Arrays.copyOfRange(elements, head, head + size);
1097	<	if ((firstLeg = elements.length - head) < size)
1098	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1094	>	return toArray(Object[].class);
1095	>	}
1096	>
1097	>	private <T> T[] toArray(Class<T[]> klazz) {
1098	>	final Object[] es = elements;
1099	>	final T[] a;
1100	>	final int size = size(), head = this.head, end;
1101	>	final int len = Math.min(size, es.length - head);
1102	>	if ((end = head + size) >= 0) {
1103	>	a = Arrays.copyOfRange(es, head, end, klazz);
1104	>	} else {
1105	>	// integer overflow!
1106	>	a = Arrays.copyOfRange(es, 0, size, klazz);
1107	>	System.arraycopy(es, head, a, 0, len);
1108	>	}
1109	>	if (tail < head)
1110	>	System.arraycopy(es, 0, a, len, tail);
1111		return a;
1112		}
1113
#	Line 1029 | Line 1149 | public class ArrayDeque<E> extends Abstr
1149		*/
1150		@SuppressWarnings("unchecked")
1151		public <T> T[] toArray(T[] a) {
1152	<	final Object[] elements = this.elements;
1153	<	final int head = this.head;
1154	<	final int firstLeg;
1155	<	boolean wrap = (firstLeg = elements.length - head) < size;
1156	<	if (size > a.length) {
1157	<	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
1158	<	a.getClass());
1159	<	} else {
1040	<	System.arraycopy(elements, head, a, 0, wrap ? firstLeg : size);
1041	<	if (size < a.length)
1042	<	a[size] = null;
1152	>	final int size;
1153	>	if ((size = size()) > a.length)
1154	>	return toArray((Class<T[]>) a.getClass());
1155	>	final Object[] es = elements;
1156	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1157	>	; i = 0, len = tail) {
1158	>	System.arraycopy(es, i, a, j, len);
1159	>	if ((j += len) == size) break;
1160		}
1161	<	if (wrap)
1162	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1161	>	if (size < a.length)
1162	>	a[size] = null;
1163		return a;
1164		}
1165
#	Line 1080 | Line 1197 | public class ArrayDeque<E> extends Abstr
1197		s.defaultWriteObject();
1198
1199		// Write out size
1200	<	s.writeInt(size);
1200	>	s.writeInt(size());
1201
1202		// Write out elements in order.
1203	<	final Object[] elements = this.elements;
1204	<	final int capacity = elements.length;
1205	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1206	<	s.writeObject(elements[i]);
1203	>	final Object[] es = elements;
1204	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1205	>	; i = 0, to = end) {
1206	>	for (; i < to; i++)
1207	>	s.writeObject(es[i]);
1208	>	if (to == end) break;
1209	>	}
1210		}
1211
1212		/**
#	Line 1101 | Line 1221 | public class ArrayDeque<E> extends Abstr
1221		s.defaultReadObject();
1222
1223		// Read in size and allocate array
1224	<	elements = new Object[size = s.readInt()];
1224	>	int size = s.readInt();
1225	>	elements = new Object[size + 1];
1226	>	this.tail = size;
1227
1228		// Read in all elements in the proper order.
1229		for (int i = 0; i < size; i++)
#	Line 1109 | Line 1231 | public class ArrayDeque<E> extends Abstr
1231		}
1232
1233		/** debugging */
1234	<	private void checkInvariants() {
1234	>	void checkInvariants() {
1235		try {
1236		int capacity = elements.length;
1237	<	assert size >= 0 && size <= capacity;
1238	<	assert head >= 0 && ((capacity == 0 && head == 0 && size == 0)
1239	<	|| head < capacity);
1240	<	assert size == 0
1241	<	|| (elements[head] != null && elements[tail()] != null);
1242	<	assert size == capacity
1243	<	|| (elements[dec(head, capacity)] == null
1122	<	&& elements[inc(tail(), capacity)] == null);
1237	>	// assert head >= 0 && head < capacity;
1238	>	// assert tail >= 0 && tail < capacity;
1239	>	// assert capacity > 0;
1240	>	// assert size() < capacity;
1241	>	// assert head == tail || elements[head] != null;
1242	>	// assert elements[tail] == null;
1243	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1244		} catch (Throwable t) {
1245	<	System.err.printf("head=%d size=%d capacity=%d%n",
1246	<	head, size, elements.length);
1245	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1246	>	head, tail, elements.length);
1247		System.err.printf("elements=%s%n",
1248		Arrays.toString(elements));
1249		throw t;

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