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

Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.83 by jsr166, Sun Oct 23 00:28:41 2016 UTC vs.
Revision 1.122 by jsr166, Sat Nov 26 14:13:32 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.  Having only
72	+	* one hot inner loop body instead of two or three eases human
73	+	* maintenance and encourages VM loop inlining into the caller.
74	+	*/
75	+
76		/**
77		* The array in which the elements of the deque are stored.
78	<	* We guarantee that all array cells not holding deque elements
79	<	* are always null.
78	>	* All array cells not holding deque elements are always null.
79	>	* The array always has at least one null slot (at tail).
80		*/
81		transient Object[] elements;
82
83		/**
84		* The index of the element at the head of the deque (which is the
85		* element that would be removed by remove() or pop()); or an
86	<	* arbitrary number 0 <= head < elements.length if the deque is empty.
86	>	* arbitrary number 0 <= head < elements.length equal to tail if
87	>	* the deque is empty.
88		*/
89		transient int head;
90
91	<	/** Number of elements in this collection. */
92	<	transient int size;
91	>	/**
92	>	* The index at which the next element would be added to the tail
93	>	* of the deque (via addLast(E), add(E), or push(E));
94	>	* elements[tail] is always null.
95	>	*/
96	>	transient int tail;
97
98		/**
99		* The maximum size of array to allocate.
#	Line 92 | Line 110 | public class ArrayDeque<E> extends Abstr
110		*/
111		private void grow(int needed) {
112		// overflow-conscious code
113	<	// checkInvariants();
96	<	int oldCapacity = elements.length;
113	>	final int oldCapacity = elements.length;
114		int newCapacity;
115	<	// Double size if small; else grow by 50%
115	>	// Double capacity if small; else grow by 50%
116		int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
117		if (jump < needed
118		|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
119		newCapacity = newCapacity(needed, jump);
120		elements = Arrays.copyOf(elements, newCapacity);
121	<	if (oldCapacity - head < size) {
121	>	// Exceptionally, here tail == head needs to be disambiguated
122	>	if (tail < head || (tail == head && elements[head] != null)) {
123		// wrap around; slide first leg forward to end of array
124		int newSpace = newCapacity - oldCapacity;
125		System.arraycopy(elements, head,
#	Line 115 | Line 133 | public class ArrayDeque<E> extends Abstr
133
134		/** Capacity calculation for edge conditions, especially overflow. */
135		private int newCapacity(int needed, int jump) {
136	<	int oldCapacity = elements.length;
119	<	int minCapacity;
136	>	final int oldCapacity = elements.length, minCapacity;
137		if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
138		if (minCapacity < 0)
139		throw new IllegalStateException("Sorry, deque too big");
#	Line 137 | Line 154 | public class ArrayDeque<E> extends Abstr
154		* @since TBD
155		*/
156		/* public */ void ensureCapacity(int minCapacity) {
157	<	if (minCapacity > elements.length)
158	<	grow(minCapacity - elements.length);
157	>	int needed;
158	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
159	>	grow(needed);
160		// checkInvariants();
161		}
162
#	Line 148 | Line 166 | public class ArrayDeque<E> extends Abstr
166		* @since TBD
167		*/
168		/* public */ void trimToSize() {
169	<	if (size < elements.length) {
170	<	elements = toArray();
169	>	int size;
170	>	if ((size = size()) + 1 < elements.length) {
171	>	elements = toArray(new Object[size + 1]);
172		head = 0;
173	+	tail = size;
174		}
175		// checkInvariants();
176		}
#	Line 170 | Line 190 | public class ArrayDeque<E> extends Abstr
190		* @param numElements lower bound on initial capacity of the deque
191		*/
192		public ArrayDeque(int numElements) {
193	<	elements = new Object[numElements];
193	>	elements =
194	>	new Object[(numElements < 1) ? 1 :
195	>	(numElements == Integer.MAX_VALUE) ? Integer.MAX_VALUE :
196	>	numElements + 1];
197		}
198
199		/**
#	Line 184 | Line 207 | public class ArrayDeque<E> extends Abstr
207		* @throws NullPointerException if the specified collection is null
208		*/
209		public ArrayDeque(Collection<? extends E> c) {
210	<	Object[] elements = c.toArray();
211	<	// 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;
210	>	this(c.size());
211	>	addAll(c);
212		}
213
214		/**
#	Line 200 | Line 216 | public class ArrayDeque<E> extends Abstr
216		* Precondition and postcondition: 0 <= i < modulus.
217		*/
218		static final int inc(int i, int modulus) {
219	<	if (++i == modulus) i = 0;
219	>	if (++i >= modulus) i = 0;
220		return i;
221		}
222
#	Line 209 | Line 225 | public class ArrayDeque<E> extends Abstr
225		* Precondition and postcondition: 0 <= i < modulus.
226		*/
227		static final int dec(int i, int modulus) {
228	<	if (--i < 0) i += modulus;
228	>	if (--i < 0) i = modulus - 1;
229		return i;
230		}
231
232		/**
233	<	* Adds i and j, mod modulus.
234	<	* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus.
233	>	* Circularly adds the given distance to index i, mod modulus.
234	>	* Precondition: 0 <= i < modulus, 0 <= distance <= modulus.
235	>	* @return index 0 <= i < modulus
236		*/
237	<	static final int add(int i, int j, int modulus) {
238	<	if ((i += j) - modulus >= 0) i -= modulus;
237	>	static final int add(int i, int distance, int modulus) {
238	>	if ((i += distance) - modulus >= 0) distance -= modulus;
239		return i;
240		}
241
242		/**
243	<	* Returns the array index of the last element.
244	<	* May return invalid index -1 if there are no elements.
243	>	* Subtracts j from i, mod modulus.
244	>	* Index i must be logically ahead of index j.
245	>	* Precondition: 0 <= i < modulus, 0 <= j < modulus.
246	>	* @return the "circular distance" from j to i; corner case i == j
247	>	* is diambiguated to "empty", returning 0.
248		*/
249	<	final int tail() {
250	<	return add(head, size - 1, elements.length);
249	>	static final int sub(int i, int j, int modulus) {
250	>	if ((i -= j) < 0) i += modulus;
251	>	return i;
252		}
253
254		/**
255		* Returns element at array index i.
256	+	* This is a slight abuse of generics, accepted by javac.
257		*/
258		@SuppressWarnings("unchecked")
259	<	final E elementAt(int i) {
260	<	return (E) elements[i];
259	>	static final <E> E elementAt(Object[] es, int i) {
260	>	return (E) es[i];
261		}
262
263		/**
#	Line 243 | Line 265 | public class ArrayDeque<E> extends Abstr
265		* This check doesn't catch all possible comodifications,
266		* but does catch ones that corrupt traversal.
267		*/
268	<	E checkedElementAt(Object[] elements, int i) {
269	<	@SuppressWarnings("unchecked") E e = (E) elements[i];
268	>	static final <E> E nonNullElementAt(Object[] es, int i) {
269	>	@SuppressWarnings("unchecked") E e = (E) es[i];
270		if (e == null)
271		throw new ConcurrentModificationException();
272		return e;
#	Line 261 | Line 283 | public class ArrayDeque<E> extends Abstr
283		* @throws NullPointerException if the specified element is null
284		*/
285		public void addFirst(E e) {
286	+	if (e == null)
287	+	throw new NullPointerException();
288	+	final Object[] es = elements;
289	+	es[head = dec(head, es.length)] = e;
290	+	if (head == tail)
291	+	grow(1);
292		// checkInvariants();
265	–	Objects.requireNonNull(e);
266	–	final Object[] elements;
267	–	final int capacity, s;
268	–	if ((s = size) == (capacity = (elements = this.elements).length))
269	–	addFirstSlowPath(e);
270	–	else
271	–	elements[head = dec(head, capacity)] = e;
272	–	size = s + 1;
273	–	// checkInvariants();
274	–	}
275	–
276	–	private void addFirstSlowPath(E e) {
277	–	grow(1);
278	–	final Object[] elements = this.elements;
279	–	elements[head = dec(head, elements.length)] = e;
293		}
294
295		/**
#	Line 288 | Line 301 | public class ArrayDeque<E> extends Abstr
301		* @throws NullPointerException if the specified element is null
302		*/
303		public void addLast(E e) {
304	<	// checkInvariants();
305	<	Objects.requireNonNull(e);
306	<	final Object[] elements;
307	<	final int capacity, s;
308	<	if ((s = size) == (capacity = (elements = this.elements).length))
309	<	addLastSlowPath(e);
297	<	else
298	<	elements[add(head, s, capacity)] = e;
299	<	size = s + 1;
304	>	if (e == null)
305	>	throw new NullPointerException();
306	>	final Object[] es = elements;
307	>	es[tail] = e;
308	>	if (head == (tail = inc(tail, es.length)))
309	>	grow(1);
310		// checkInvariants();
311		}
312
303	–	private void addLastSlowPath(E e) {
304	–	grow(1);
305	–	final Object[] elements = this.elements;
306	–	elements[add(head, size, elements.length)] = e;
307	–	}
308	–
313		/**
314		* Adds all of the elements in the specified collection at the end
315		* of this deque, as if by calling {@link #addLast} on each one,
#	Line 317 | Line 321 | public class ArrayDeque<E> extends Abstr
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	+	c.forEach(this::addLast);
329		// checkInvariants();
330	<	Object[] a, elements;
324	<	int newcomers, capacity, s = size;
325	<	if ((newcomers = (a = c.toArray()).length) == 0)
326	<	return false;
327	<	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		/**
#	Line 364 | Line 358 | public class ArrayDeque<E> extends Abstr
358		* @throws NoSuchElementException {@inheritDoc}
359		*/
360		public E removeFirst() {
361	<	// checkInvariants();
362	<	E x = pollFirst();
369	<	if (x == null)
361	>	E e = pollFirst();
362	>	if (e == null)
363		throw new NoSuchElementException();
364	<	return x;
364	>	// checkInvariants();
365	>	return e;
366		}
367
368		/**
369		* @throws NoSuchElementException {@inheritDoc}
370		*/
371		public E removeLast() {
372	<	// checkInvariants();
373	<	E x = pollLast();
380	<	if (x == null)
372	>	E e = pollLast();
373	>	if (e == null)
374		throw new NoSuchElementException();
375	<	return x;
375	>	// checkInvariants();
376	>	return e;
377		}
378
379		public E pollFirst() {
380	+	final Object[] es;
381	+	final int h;
382	+	E e = elementAt(es = elements, h = head);
383	+	if (e != null) {
384	+	es[h] = null;
385	+	head = inc(h, es.length);
386	+	}
387		// 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;
388		return e;
389		}
390
391		public E pollLast() {
392	+	final Object[] es;
393	+	final int t;
394	+	E e = elementAt(es = elements, t = dec(tail, es.length));
395	+	if (e != null)
396	+	es[tail = t] = null;
397		// 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;
398		return e;
399		}
400
#	Line 412 | Line 402 | public class ArrayDeque<E> extends Abstr
402		* @throws NoSuchElementException {@inheritDoc}
403		*/
404		public E getFirst() {
405	+	E e = elementAt(elements, head);
406	+	if (e == null)
407	+	throw new NoSuchElementException();
408		// checkInvariants();
409	<	if (size == 0) throw new NoSuchElementException();
417	<	return elementAt(head);
409	>	return e;
410		}
411
412		/**
413		* @throws NoSuchElementException {@inheritDoc}
414		*/
415		public E getLast() {
416	+	final Object[] es = elements;
417	+	E e = elementAt(es, dec(tail, es.length));
418	+	if (e == null)
419	+	throw new NoSuchElementException();
420		// checkInvariants();
421	<	if (size == 0) throw new NoSuchElementException();
426	<	return elementAt(tail());
421	>	return e;
422		}
423
424		public E peekFirst() {
425		// checkInvariants();
426	<	return (size == 0) ? null : elementAt(head);
426	>	return elementAt(elements, head);
427		}
428
429		public E peekLast() {
430		// checkInvariants();
431	<	return (size == 0) ? null : elementAt(tail());
431	>	final Object[] es;
432	>	return elementAt(es = elements, dec(tail, es.length));
433		}
434
435		/**
#	Line 449 | Line 445 | public class ArrayDeque<E> extends Abstr
445		* @return {@code true} if the deque contained the specified element
446		*/
447		public boolean removeFirstOccurrence(Object o) {
452	–	// checkInvariants();
448		if (o != null) {
449	<	final Object[] elements = this.elements;
450	<	final int capacity = elements.length;
451	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) {
452	<	if (o.equals(elements[i])) {
453	<	delete(i);
454	<	return true;
455	<	}
449	>	final Object[] es = elements;
450	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
451	>	; i = 0, to = end) {
452	>	for (; i < to; i++)
453	>	if (o.equals(es[i])) {
454	>	delete(i);
455	>	return true;
456	>	}
457	>	if (to == end) break;
458		}
459		}
460		return false;
#	Line 477 | Line 474 | public class ArrayDeque<E> extends Abstr
474		*/
475		public boolean removeLastOccurrence(Object o) {
476		if (o != null) {
477	<	final Object[] elements = this.elements;
478	<	final int capacity = elements.length;
479	<	for (int k = size, i = add(head, k - 1, capacity);
480	<	--k >= 0; i = dec(i, capacity)) {
481	<	if (o.equals(elements[i])) {
482	<	delete(i);
483	<	return true;
484	<	}
477	>	final Object[] es = elements;
478	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
479	>	; i = es.length, to = end) {
480	>	for (i--; i > to - 1; i--)
481	>	if (o.equals(es[i])) {
482	>	delete(i);
483	>	return true;
484	>	}
485	>	if (to == end) break;
486		}
487		}
488		return false;
#	Line 612 | Line 610 | public class ArrayDeque<E> extends Abstr
610		* <p>This method is called delete rather than remove to emphasize
611		* that its semantics differ from those of {@link List#remove(int)}.
612		*
613	<	* @return true if elements moved backwards
613	>	* @return true if elements near tail moved backwards
614		*/
615		boolean delete(int i) {
616		// checkInvariants();
617	<	final Object[] elements = this.elements;
618	<	final int capacity = elements.length;
619	<	final int h = head;
620	<	int front;              // number of elements before to-be-deleted elt
621	<	if ((front = i - h) < 0) front += capacity;
622	<	final int back = size - front - 1; // number of elements after
617	>	final Object[] es = elements;
618	>	final int capacity = es.length;
619	>	final int h, t;
620	>	// number of elements before to-be-deleted elt
621	>	final int front = sub(i, h = head, capacity);
622	>	// number of elements after to-be-deleted elt
623	>	final int back = sub(t = tail, i, capacity) - 1;
624		if (front < back) {
625		// move front elements forwards
626		if (h <= i) {
627	<	System.arraycopy(elements, h, elements, h + 1, front);
627	>	System.arraycopy(es, h, es, h + 1, front);
628		} else { // Wrap around
629	<	System.arraycopy(elements, 0, elements, 1, i);
630	<	elements[0] = elements[capacity - 1];
631	<	System.arraycopy(elements, h, elements, h + 1, front - (i + 1));
629	>	System.arraycopy(es, 0, es, 1, i);
630	>	es[0] = es[capacity - 1];
631	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
632		}
633	<	elements[h] = null;
633	>	es[h] = null;
634		head = inc(h, capacity);
636	–	size--;
635		// checkInvariants();
636		return false;
637		} else {
638		// move back elements backwards
639	<	int tail = tail();
639	>	tail = dec(t, capacity);
640		if (i <= tail) {
641	<	System.arraycopy(elements, i + 1, elements, i, back);
641	>	System.arraycopy(es, i + 1, es, i, back);
642		} else { // Wrap around
643	<	int firstLeg = capacity - (i + 1);
644	<	System.arraycopy(elements, i + 1, elements, i, firstLeg);
645	<	elements[capacity - 1] = elements[0];
648	<	System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1);
643	>	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
644	>	es[capacity - 1] = es[0];
645	>	System.arraycopy(es, 1, es, 0, t - 1);
646		}
647	<	elements[tail] = null;
651	<	size--;
647	>	es[tail] = null;
648		// checkInvariants();
649		return true;
650		}
#	Line 662 | Line 658 | public class ArrayDeque<E> extends Abstr
658		* @return the number of elements in this deque
659		*/
660		public int size() {
661	<	return size;
661	>	return sub(tail, head, elements.length);
662		}
663
664		/**
#	Line 671 | Line 667 | public class ArrayDeque<E> extends Abstr
667		* @return {@code true} if this deque contains no elements
668		*/
669		public boolean isEmpty() {
670	<	return size == 0;
670	>	return head == tail;
671		}
672
673		/**
#	Line 695 | Line 691 | public class ArrayDeque<E> extends Abstr
691		int cursor;
692
693		/** Number of elements yet to be returned. */
694	<	int remaining = size;
694	>	int remaining = size();
695
696		/**
697		* Index of element returned by most recent call to next.
#	Line 710 | Line 706 | public class ArrayDeque<E> extends Abstr
706		}
707
708		public E next() {
709	<	if (remaining == 0)
709	>	if (remaining <= 0)
710		throw new NoSuchElementException();
711	<	E e = checkedElementAt(elements, cursor);
712	<	lastRet = cursor;
713	<	cursor = inc(cursor, elements.length);
711	>	final Object[] es = elements;
712	>	E e = nonNullElementAt(es, cursor);
713	>	cursor = inc(lastRet = cursor, es.length);
714		remaining--;
715		return e;
716		}
717
718		void postDelete(boolean leftShifted) {
719		if (leftShifted)
720	<	cursor = dec(cursor, elements.length); // undo inc in next
720	>	cursor = dec(cursor, elements.length);
721		}
722
723		public final void remove() {
#	Line 733 | Line 729 | public class ArrayDeque<E> extends Abstr
729
730		public void forEachRemaining(Consumer<? super E> action) {
731		Objects.requireNonNull(action);
732	<	final Object[] elements = ArrayDeque.this.elements;
733	<	final int capacity = elements.length;
734	<	int k = remaining;
732	>	int r;
733	>	if ((r = remaining) <= 0)
734	>	return;
735		remaining = 0;
736	<	for (int i = cursor; --k >= 0; i = inc(i, capacity))
737	<	action.accept(checkedElementAt(elements, i));
736	>	final Object[] es = elements;
737	>	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
738	>	throw new ConcurrentModificationException();
739	>	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
740	>	; i = 0, to = end) {
741	>	for (; i < to; i++)
742	>	action.accept(elementAt(es, i));
743	>	if (to == end) {
744	>	if (end != tail)
745	>	throw new ConcurrentModificationException();
746	>	lastRet = dec(end, es.length);
747	>	break;
748	>	}
749	>	}
750		}
751		}
752
753		private class DescendingIterator extends DeqIterator {
754	<	DescendingIterator() { cursor = tail(); }
754	>	DescendingIterator() { cursor = dec(tail, elements.length); }
755
756		public final E next() {
757	<	if (remaining == 0)
757	>	if (remaining <= 0)
758		throw new NoSuchElementException();
759	<	E e = checkedElementAt(elements, cursor);
759	>	final Object[] es = elements;
760	>	E e = nonNullElementAt(es, cursor);
761		lastRet = cursor;
762	<	cursor = dec(cursor, elements.length);
762	>	cursor = dec(cursor, es.length);
763		remaining--;
764		return e;
765		}
766
767		void postDelete(boolean leftShifted) {
768		if (!leftShifted)
769	<	cursor = inc(cursor, elements.length); // undo dec in next
769	>	cursor = inc(cursor, elements.length);
770		}
771
772		public final void forEachRemaining(Consumer<? super E> action) {
773		Objects.requireNonNull(action);
774	<	final Object[] elements = ArrayDeque.this.elements;
775	<	final int capacity = elements.length;
776	<	int k = remaining;
774	>	int r;
775	>	if ((r = remaining) <= 0)
776	>	return;
777		remaining = 0;
778	<	for (int i = cursor; --k >= 0; i = dec(i, capacity))
779	<	action.accept(checkedElementAt(elements, i));
778	>	final Object[] es = elements;
779	>	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
780	>	throw new ConcurrentModificationException();
781	>	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
782	>	; i = es.length - 1, to = end) {
783	>	// hotspot generates faster code than for: i >= to !
784	>	for (; i > to - 1; i--)
785	>	action.accept(elementAt(es, i));
786	>	if (to == end) {
787	>	if (end != head)
788	>	throw new ConcurrentModificationException();
789	>	lastRet = end;
790	>	break;
791	>	}
792	>	}
793		}
794		}
795
#	Line 785 | Line 807 | public class ArrayDeque<E> extends Abstr
807		* @since 1.8
808		*/
809		public Spliterator<E> spliterator() {
810	<	return new ArrayDequeSpliterator();
810	>	return new DeqSpliterator();
811		}
812
813	<	final class ArrayDequeSpliterator implements Spliterator<E> {
814	<	private int cursor;
815	<	private int remaining; // -1 until late-binding first use
813	>	final class DeqSpliterator implements Spliterator<E> {
814	>	private int fence;      // -1 until first use
815	>	private int cursor;     // current index, modified on traverse/split
816
817		/** Constructs late-binding spliterator over all elements. */
818	<	ArrayDequeSpliterator() {
819	<	this.remaining = -1;
818	>	DeqSpliterator() {
819	>	this.fence = -1;
820		}
821
822	<	/** Constructs spliterator over the given slice. */
823	<	ArrayDequeSpliterator(int cursor, int count) {
824	<	this.cursor = cursor;
825	<	this.remaining = count;
822	>	/** Constructs spliterator over the given range. */
823	>	DeqSpliterator(int origin, int fence) {
824	>	this.cursor = origin;
825	>	this.fence = fence;
826		}
827
828	<	/** Ensures late-binding initialization; then returns remaining. */
829	<	private int remaining() {
830	<	if (remaining < 0) {
828	>	/** Ensures late-binding initialization; then returns fence. */
829	>	private int getFence() { // force initialization
830	>	int t;
831	>	if ((t = fence) < 0) {
832	>	t = fence = tail;
833		cursor = head;
810	–	remaining = size;
834		}
835	<	return remaining;
835	>	return t;
836		}
837
838	<	public ArrayDequeSpliterator trySplit() {
839	<	final int mid;
840	<	if ((mid = remaining() >> 1) > 0) {
841	<	int oldCursor = cursor;
842	<	cursor = add(cursor, mid, elements.length);
843	<	remaining -= mid;
821	<	return new ArrayDequeSpliterator(oldCursor, mid);
822	<	}
823	<	return null;
838	>	public DeqSpliterator trySplit() {
839	>	final Object[] es = elements;
840	>	final int i, n;
841	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
842	>	? null
843	>	: new DeqSpliterator(i, cursor = add(i, n, es.length));
844		}
845
846		public void forEachRemaining(Consumer<? super E> action) {
847	<	Objects.requireNonNull(action);
848	<	final Object[] elements = ArrayDeque.this.elements;
849	<	final int capacity = elements.length;
850	<	int k = remaining();
851	<	remaining = 0;
852	<	for (int i = cursor; --k >= 0; i = inc(i, capacity))
853	<	action.accept(checkedElementAt(elements, i));
847	>	if (action == null)
848	>	throw new NullPointerException();
849	>	final int end = getFence(), cursor = this.cursor;
850	>	final Object[] es = elements;
851	>	if (cursor != end) {
852	>	this.cursor = end;
853	>	// null check at both ends of range is sufficient
854	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
855	>	throw new ConcurrentModificationException();
856	>	for (int i = cursor, to = (i <= end) ? end : es.length;
857	>	; i = 0, to = end) {
858	>	for (; i < to; i++)
859	>	action.accept(elementAt(es, i));
860	>	if (to == end) break;
861	>	}
862	>	}
863		}
864
865		public boolean tryAdvance(Consumer<? super E> action) {
866		Objects.requireNonNull(action);
867	<	if (remaining() == 0)
867	>	final Object[] es = elements;
868	>	if (fence < 0) { fence = tail; cursor = head; } // late-binding
869	>	final int i;
870	>	if ((i = cursor) == fence)
871		return false;
872	<	action.accept(checkedElementAt(elements, cursor));
873	<	cursor = inc(cursor, elements.length);
874	<	remaining--;
872	>	E e = nonNullElementAt(es, i);
873	>	cursor = inc(i, es.length);
874	>	action.accept(e);
875		return true;
876		}
877
878		public long estimateSize() {
879	<	return remaining();
879	>	return sub(getFence(), cursor, elements.length);
880		}
881
882		public int characteristics() {
#	Line 855 | Line 887 | public class ArrayDeque<E> extends Abstr
887		}
888		}
889
858	–	@Override
890		public void forEach(Consumer<? super E> action) {
860	–	// checkInvariants();
891		Objects.requireNonNull(action);
892	<	final Object[] elements = this.elements;
893	<	final int capacity = elements.length;
894	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
895	<	action.accept(elementAt(i));
892	>	final Object[] es = elements;
893	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
894	>	; i = 0, to = end) {
895	>	for (; i < to; i++)
896	>	action.accept(elementAt(es, i));
897	>	if (to == end) {
898	>	if (end != tail) throw new ConcurrentModificationException();
899	>	break;
900	>	}
901	>	}
902		// checkInvariants();
903		}
904
#	Line 875 | Line 911 | public class ArrayDeque<E> extends Abstr
911		*/
912		/* public */ void replaceAll(UnaryOperator<E> operator) {
913		Objects.requireNonNull(operator);
914	<	final Object[] elements = this.elements;
915	<	final int capacity = elements.length;
916	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
917	<	elements[i] = operator.apply(elementAt(i));
914	>	final Object[] es = elements;
915	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
916	>	; i = 0, to = end) {
917	>	for (; i < to; i++)
918	>	es[i] = operator.apply(elementAt(es, i));
919	>	if (to == end) {
920	>	if (end != tail) throw new ConcurrentModificationException();
921	>	break;
922	>	}
923	>	}
924		// checkInvariants();
925		}
926
927		/**
928		* @throws NullPointerException {@inheritDoc}
929		*/
888	–	@Override
930		public boolean removeIf(Predicate<? super E> filter) {
931		Objects.requireNonNull(filter);
932		return bulkRemove(filter);
#	Line 894 | Line 935 | public class ArrayDeque<E> extends Abstr
935		/**
936		* @throws NullPointerException {@inheritDoc}
937		*/
897	–	@Override
938		public boolean removeAll(Collection<?> c) {
939		Objects.requireNonNull(c);
940		return bulkRemove(e -> c.contains(e));
#	Line 903 | Line 943 | public class ArrayDeque<E> extends Abstr
943		/**
944		* @throws NullPointerException {@inheritDoc}
945		*/
906	–	@Override
946		public boolean retainAll(Collection<?> c) {
947		Objects.requireNonNull(c);
948		return bulkRemove(e -> !c.contains(e));
#	Line 912 | Line 951 | public class ArrayDeque<E> extends Abstr
951		/** Implementation of bulk remove methods. */
952		private boolean bulkRemove(Predicate<? super E> filter) {
953		// checkInvariants();
954	<	final Object[] elements = this.elements;
955	<	final int capacity = elements.length;
956	<	int i = head, j = i, remaining = size, deleted = 0;
957	<	try {
958	<	for (; remaining > 0; remaining--, i = inc(i, capacity)) {
959	<	@SuppressWarnings("unchecked") E e = (E) elements[i];
960	<	if (filter.test(e))
961	<	deleted++;
962	<	else {
963	<	if (j != i)
964	<	elements[j] = e;
965	<	j = inc(j, capacity);
966	<	}
954	>	final Object[] es = elements;
955	>	// Optimize for initial run of survivors
956	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
957	>	; i = 0, to = end) {
958	>	for (; i < to; i++)
959	>	if (filter.test(elementAt(es, i)))
960	>	return bulkRemoveModified(filter, i);
961	>	if (to == end) {
962	>	if (end != tail) throw new ConcurrentModificationException();
963	>	break;
964	>	}
965	>	}
966	>	return false;
967	>	}
968	>
969	>	// A tiny bit set implementation
970	>
971	>	private static long[] nBits(int n) {
972	>	return new long[((n - 1) >> 6) + 1];
973	>	}
974	>	private static void setBit(long[] bits, int i) {
975	>	bits[i >> 6] |= 1L << i;
976	>	}
977	>	private static boolean isClear(long[] bits, int i) {
978	>	return (bits[i >> 6] & (1L << i)) == 0;
979	>	}
980	>
981	>	/**
982	>	* Helper for bulkRemove, in case of at least one deletion.
983	>	* Tolerate predicates that reentrantly access the collection for
984	>	* read (but writers still get CME), so traverse once to find
985	>	* elements to delete, a second pass to physically expunge.
986	>	*
987	>	* @param beg valid index of first element to be deleted
988	>	*/
989	>	private boolean bulkRemoveModified(
990	>	Predicate<? super E> filter, final int beg) {
991	>	final Object[] es = elements;
992	>	final int capacity = es.length;
993	>	final int end = tail;
994	>	final long[] deathRow = nBits(sub(end, beg, capacity));
995	>	deathRow[0] = 1L;   // set bit 0
996	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
997	>	; i = 0, to = end, k -= capacity) {
998	>	for (; i < to; i++)
999	>	if (filter.test(elementAt(es, i)))
1000	>	setBit(deathRow, i - k);
1001	>	if (to == end) break;
1002	>	}
1003	>	// a two-finger traversal, with hare i reading, tortoise w writing
1004	>	int w = beg;
1005	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1006	>	; w = 0) { // w rejoins i on second leg
1007	>	// In this loop, i and w are on the same leg, with i > w
1008	>	for (; i < to; i++)
1009	>	if (isClear(deathRow, i - k))
1010	>	es[w++] = es[i];
1011	>	if (to == end) break;
1012	>	// In this loop, w is on the first leg, i on the second
1013	>	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1014	>	if (isClear(deathRow, i - k))
1015	>	es[w++] = es[i];
1016	>	if (i >= to) {
1017	>	if (w == capacity) w = 0; // "corner" case
1018	>	break;
1019		}
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();
1020		}
1021	+	if (end != tail) throw new ConcurrentModificationException();
1022	+	circularClear(es, tail = w, end);
1023	+	// checkInvariants();
1024	+	return true;
1025		}
1026
1027		/**
#	Line 951 | Line 1034 | public class ArrayDeque<E> extends Abstr
1034		*/
1035		public boolean contains(Object o) {
1036		if (o != null) {
1037	<	final Object[] elements = this.elements;
1038	<	final int capacity = elements.length;
1039	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1040	<	if (o.equals(elements[i]))
1041	<	return true;
1037	>	final Object[] es = elements;
1038	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1039	>	; i = 0, to = end) {
1040	>	for (; i < to; i++)
1041	>	if (o.equals(es[i]))
1042	>	return true;
1043	>	if (to == end) break;
1044	>	}
1045		}
1046		return false;
1047		}
#	Line 982 | Line 1068 | public class ArrayDeque<E> extends Abstr
1068		* The deque will be empty after this call returns.
1069		*/
1070		public void clear() {
1071	<	final Object[] elements = this.elements;
1072	<	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;
1071	>	circularClear(elements, head, tail);
1072	>	head = tail = 0;
1073		// checkInvariants();
1074		}
1075
1076		/**
1077	+	* Nulls out slots starting at array index i, upto index end.
1078	+	*/
1079	+	private static void circularClear(Object[] es, int i, int end) {
1080	+	for (int to = (i <= end) ? end : es.length;
1081	+	; i = 0, to = end) {
1082	+	Arrays.fill(es, i, to, null);
1083	+	if (to == end) break;
1084	+	}
1085	+	}
1086	+
1087	+	/**
1088		* Returns an array containing all of the elements in this deque
1089		* in proper sequence (from first to last element).
1090		*
#	Line 1010 | Line 1098 | public class ArrayDeque<E> extends Abstr
1098		* @return an array containing all of the elements in this deque
1099		*/
1100		public Object[] toArray() {
1101	<	final int head = this.head;
1102	<	final int firstLeg;
1103	<	Object[] a = Arrays.copyOfRange(elements, head, head + size);
1104	<	if ((firstLeg = elements.length - head) < size)
1105	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1101	>	return toArray(Object[].class);
1102	>	}
1103	>
1104	>	private <T> T[] toArray(Class<T[]> klazz) {
1105	>	final Object[] es = elements;
1106	>	final T[] a;
1107	>	final int head = this.head, tail = this.tail, end;
1108	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1109	>	// Uses null extension feature of copyOfRange
1110	>	a = Arrays.copyOfRange(es, head, end, klazz);
1111	>	} else {
1112	>	// integer overflow!
1113	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1114	>	System.arraycopy(es, head, a, 0, es.length - head);
1115	>	}
1116	>	if (end != tail)
1117	>	System.arraycopy(es, 0, a, es.length - head, tail);
1118		return a;
1119		}
1120
#	Line 1056 | Line 1156 | public class ArrayDeque<E> extends Abstr
1156		*/
1157		@SuppressWarnings("unchecked")
1158		public <T> T[] toArray(T[] a) {
1159	<	final Object[] elements = this.elements;
1160	<	final int head = this.head;
1161	<	final int firstLeg;
1162	<	boolean wrap = (firstLeg = elements.length - head) < size;
1163	<	if (size > a.length) {
1164	<	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
1165	<	a.getClass());
1166	<	} else {
1067	<	System.arraycopy(elements, head, a, 0, wrap ? firstLeg : size);
1068	<	if (size < a.length)
1069	<	a[size] = null;
1159	>	final int size;
1160	>	if ((size = size()) > a.length)
1161	>	return toArray((Class<T[]>) a.getClass());
1162	>	final Object[] es = elements;
1163	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1164	>	; i = 0, len = tail) {
1165	>	System.arraycopy(es, i, a, j, len);
1166	>	if ((j += len) == size) break;
1167		}
1168	<	if (wrap)
1169	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1168	>	if (size < a.length)
1169	>	a[size] = null;
1170		return a;
1171		}
1172
#	Line 1107 | Line 1204 | public class ArrayDeque<E> extends Abstr
1204		s.defaultWriteObject();
1205
1206		// Write out size
1207	<	s.writeInt(size);
1207	>	s.writeInt(size());
1208
1209		// Write out elements in order.
1210	<	final Object[] elements = this.elements;
1211	<	final int capacity = elements.length;
1212	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1213	<	s.writeObject(elements[i]);
1210	>	final Object[] es = elements;
1211	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1212	>	; i = 0, to = end) {
1213	>	for (; i < to; i++)
1214	>	s.writeObject(es[i]);
1215	>	if (to == end) break;
1216	>	}
1217		}
1218
1219		/**
#	Line 1128 | Line 1228 | public class ArrayDeque<E> extends Abstr
1228		s.defaultReadObject();
1229
1230		// Read in size and allocate array
1231	<	elements = new Object[size = s.readInt()];
1231	>	int size = s.readInt();
1232	>	elements = new Object[size + 1];
1233	>	this.tail = size;
1234
1235		// Read in all elements in the proper order.
1236		for (int i = 0; i < size; i++)
#	Line 1136 | Line 1238 | public class ArrayDeque<E> extends Abstr
1238		}
1239
1240		/** debugging */
1241	<	private void checkInvariants() {
1241	>	void checkInvariants() {
1242	>	// Use head and tail fields with empty slot at tail strategy.
1243	>	// head == tail disambiguates to "empty".
1244		try {
1245		int capacity = elements.length;
1246	<	assert size >= 0 && size <= capacity;
1247	<	assert head >= 0 && ((capacity == 0 && head == 0 && size == 0)
1248	<	|| head < capacity);
1249	<	assert size == 0
1250	<	|| (elements[head] != null && elements[tail()] != null);
1251	<	assert size == capacity
1252	<	|| (elements[dec(head, capacity)] == null
1149	<	&& elements[inc(tail(), capacity)] == null);
1246	>	// assert head >= 0 && head < capacity;
1247	>	// assert tail >= 0 && tail < capacity;
1248	>	// assert capacity > 0;
1249	>	// assert size() < capacity;
1250	>	// assert head == tail || elements[head] != null;
1251	>	// assert elements[tail] == null;
1252	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1253		} catch (Throwable t) {
1254	<	System.err.printf("head=%d size=%d capacity=%d%n",
1255	<	head, size, elements.length);
1254	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1255	>	head, tail, elements.length);
1256		System.err.printf("elements=%s%n",
1257		Arrays.toString(elements));
1258		throw t;

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