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Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.95 by jsr166, Sat Oct 29 19:10:27 2016 UTC vs.
Revision 1.137 by jsr166, Sun Nov 11 17:37:30 2018 UTC

#	Line 8 | Line 8 | package java.util;
8		import java.io.Serializable;
9		import java.util.function.Consumer;
10		import java.util.function.Predicate;
11	<	import java.util.function.UnaryOperator;
11	>	// OPENJDK import jdk.internal.access.SharedSecrets;
12
13		/**
14		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 50 | Line 50 | import java.util.function.UnaryOperator;
50		* Iterator} interfaces.
51		*
52		* <p>This class is a member of the
53	<	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
53	>	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
54		* Java Collections Framework</a>.
55		*
56		* @author  Josh Bloch and Doug Lea
#	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
95	–	// checkInvariants();
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) {
120	>	final Object[] es = elements = Arrays.copyOf(elements, newCapacity);
121	>	// Exceptionally, here tail == head needs to be disambiguated
122	>	if (tail < head || (tail == head && es[head] != null)) {
123		// wrap around; slide first leg forward to end of array
124		int newSpace = newCapacity - oldCapacity;
125	<	System.arraycopy(elements, head,
126	<	elements, head + newSpace,
125	>	System.arraycopy(es, head,
126	>	es, head + newSpace,
127		oldCapacity - head);
128	<	Arrays.fill(elements, head, head + newSpace, null);
129	<	head += newSpace;
128	>	for (int i = head, to = (head += newSpace); i < to; i++)
129	>	es[i] = null;
130		}
131		// checkInvariants();
132		}
#	Line 136 | 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 147 | 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 159 | Line 180 | public class ArrayDeque<E> extends Abstr
180		* sufficient to hold 16 elements.
181		*/
182		public ArrayDeque() {
183	<	elements = new Object[16];
183	>	elements = new Object[16 + 1];
184		}
185
186		/**
#	Line 169 | 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 183 | 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[] es = c.toArray();
211	<	// 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;
210	>	this(c.size());
211	>	copyElements(c);
212		}
213
214		/**
215	<	* Increments i, mod modulus.
215	>	* Circularly increments i, mod modulus.
216		* Precondition and postcondition: 0 <= i < modulus.
217		*/
218		static final int inc(int i, int modulus) {
#	Line 204 | Line 221 | public class ArrayDeque<E> extends Abstr
221		}
222
223		/**
224	<	* Decrements i, mod modulus.
224	>	* Circularly decrements i, mod modulus.
225		* Precondition and postcondition: 0 <= i < modulus.
226		*/
227		static final int dec(int i, int modulus) {
#	Line 213 | Line 230 | public class ArrayDeque<E> extends Abstr
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 inc(int i, int distance, int modulus) {
238	>	if ((i += distance) - modulus >= 0) i -= 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 disambiguated 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	<	private 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		/**
264		* A version of elementAt that checks for null elements.
265		* This check doesn't catch all possible comodifications,
266	<	* but does catch ones that corrupt traversal.  It's a little
244	<	* surprising that javac allows this abuse of generics.
266	>	* but does catch ones that corrupt traversal.
267		*/
268	<	static final <E> E nonNullElementAt(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	<	// checkInvariants();
287	<	Objects.requireNonNull(e);
288	<	Object[] es;
289	<	int capacity, h;
290	<	final int s;
269	<	if ((s = size) == (capacity = (es = elements).length)) {
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);
271	–	capacity = (es = elements).length;
272	–	}
273	–	if ((h = head - 1) < 0) h = capacity - 1;
274	–	es[head = h] = e;
275	–	size = s + 1;
292		// checkInvariants();
293		}
294
#	Line 285 | 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	<	Object[] es;
307	<	int capacity;
308	<	final int s;
293	<	if ((s = size) == (capacity = (es = elements).length)) {
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);
295	–	capacity = (es = elements).length;
296	–	}
297	–	es[add(head, s, capacity)] = e;
298	–	size = s + 1;
310		// checkInvariants();
311		}
312
313		/**
314		* Adds all of the elements in the specified collection at the end
315		* of this deque, as if by calling {@link #addLast} on each one,
316	<	* in the order that they are returned by the collection's
306	<	* iterator.
316	>	* in the order that they are returned by the collection's iterator.
317		*
318		* @param c the elements to be inserted into this deque
319		* @return {@code true} if this deque changed as a result of the call
#	Line 311 | Line 321 | public class ArrayDeque<E> extends Abstr
321		*         of its elements are null
322		*/
323		public boolean addAll(Collection<? extends E> c) {
324	<	final int s = size, needed = c.size() - (elements.length - s);
325	<	if (needed > 0)
324	>	final int s, needed;
325	>	if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0)
326		grow(needed);
327	<	c.forEach((e) -> addLast(e));
327	>	copyElements(c);
328		// checkInvariants();
329	<	return size > s;
329	>	return size() > s;
330	>	}
331	>
332	>	private void copyElements(Collection<? extends E> c) {
333	>	c.forEach(this::addLast);
334		}
335
336		/**
#	Line 347 | Line 361 | public class ArrayDeque<E> extends Abstr
361		* @throws NoSuchElementException {@inheritDoc}
362		*/
363		public E removeFirst() {
350	–	// checkInvariants();
364		E e = pollFirst();
365		if (e == null)
366		throw new NoSuchElementException();
367	+	// checkInvariants();
368		return e;
369		}
370
#	Line 358 | Line 372 | public class ArrayDeque<E> extends Abstr
372		* @throws NoSuchElementException {@inheritDoc}
373		*/
374		public E removeLast() {
361	–	// checkInvariants();
375		E e = pollLast();
376		if (e == null)
377		throw new NoSuchElementException();
378	+	// checkInvariants();
379		return e;
380		}
381
382		public E pollFirst() {
383	+	final Object[] es;
384	+	final int h;
385	+	E e = elementAt(es = elements, h = head);
386	+	if (e != null) {
387	+	es[h] = null;
388	+	head = inc(h, es.length);
389	+	}
390		// checkInvariants();
370	–	int s, h;
371	–	if ((s = size) <= 0)
372	–	return null;
373	–	final Object[] elements = this.elements;
374	–	@SuppressWarnings("unchecked") E e = (E) elements[h = head];
375	–	elements[h] = null;
376	–	if (++h >= elements.length) h = 0;
377	–	head = h;
378	–	size = s - 1;
391		return e;
392		}
393
394		public E pollLast() {
395	+	final Object[] es;
396	+	final int t;
397	+	E e = elementAt(es = elements, t = dec(tail, es.length));
398	+	if (e != null)
399	+	es[tail = t] = null;
400		// checkInvariants();
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;
401		return e;
402		}
403
#	Line 396 | Line 405 | public class ArrayDeque<E> extends Abstr
405		* @throws NoSuchElementException {@inheritDoc}
406		*/
407		public E getFirst() {
408	+	E e = elementAt(elements, head);
409	+	if (e == null)
410	+	throw new NoSuchElementException();
411		// checkInvariants();
412	<	if (size <= 0) throw new NoSuchElementException();
401	<	return elementAt(head);
412	>	return e;
413		}
414
415		/**
416		* @throws NoSuchElementException {@inheritDoc}
417		*/
407	–	@SuppressWarnings("unchecked")
418		public E getLast() {
419	+	final Object[] es = elements;
420	+	E e = elementAt(es, dec(tail, es.length));
421	+	if (e == null)
422	+	throw new NoSuchElementException();
423		// checkInvariants();
424	<	final int s;
411	<	if ((s = size) <= 0) throw new NoSuchElementException();
412	<	final Object[] elements = this.elements;
413	<	return (E) elements[add(head, s - 1, elements.length)];
424	>	return e;
425		}
426
427		public E peekFirst() {
428		// checkInvariants();
429	<	return (size <= 0) ? null : elementAt(head);
429	>	return elementAt(elements, head);
430		}
431
421	–	@SuppressWarnings("unchecked")
432		public E peekLast() {
433		// checkInvariants();
434	<	final int s;
435	<	if ((s = size) <= 0) return null;
426	<	final Object[] elements = this.elements;
427	<	return (E) elements[add(head, s - 1, elements.length)];
434	>	final Object[] es;
435	>	return elementAt(es = elements, dec(tail, es.length));
436		}
437
438		/**
#	Line 441 | Line 449 | public class ArrayDeque<E> extends Abstr
449		*/
450		public boolean removeFirstOccurrence(Object o) {
451		if (o != null) {
452	<	final Object[] elements = this.elements;
453	<	final int capacity = elements.length;
454	<	int i, end, to, todo;
447	<	todo = (end = (i = head) + size)
448	<	- (to = (capacity - end >= 0) ? end : capacity);
449	<	for (;; to = todo, i = 0, todo = 0) {
452	>	final Object[] es = elements;
453	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
454	>	; i = 0, to = end) {
455		for (; i < to; i++)
456	<	if (o.equals(elements[i])) {
456	>	if (o.equals(es[i])) {
457		delete(i);
458		return true;
459		}
460	<	if (todo == 0) break;
460	>	if (to == end) break;
461		}
462		}
463		return false;
#	Line 472 | Line 477 | public class ArrayDeque<E> extends Abstr
477		*/
478		public boolean removeLastOccurrence(Object o) {
479		if (o != null) {
480	<	final Object[] elements = this.elements;
481	<	final int capacity = elements.length;
482	<	int i, to, end, todo;
483	<	todo = (to = ((end = (i = tail()) - size) >= -1) ? end : -1) - end;
484	<	for (;; to = (i = capacity - 1) - todo, todo = 0) {
480	<	for (; i > to; i--)
481	<	if (o.equals(elements[i])) {
480	>	final Object[] es = elements;
481	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
482	>	; i = es.length, to = end) {
483	>	for (i--; i > to - 1; i--)
484	>	if (o.equals(es[i])) {
485		delete(i);
486		return true;
487		}
488	<	if (todo == 0) break;
488	>	if (to == end) break;
489		}
490		}
491		return false;
#	Line 520 | Line 523 | public class ArrayDeque<E> extends Abstr
523		/**
524		* Retrieves and removes the head of the queue represented by this deque.
525		*
526	<	* This method differs from {@link #poll poll} only in that it throws an
527	<	* exception if this deque is empty.
526	>	* This method differs from {@link #poll() poll()} only in that it
527	>	* throws an exception if this deque is empty.
528		*
529		* <p>This method is equivalent to {@link #removeFirst}.
530		*
#	Line 610 | Line 613 | public class ArrayDeque<E> extends Abstr
613		* <p>This method is called delete rather than remove to emphasize
614		* that its semantics differ from those of {@link List#remove(int)}.
615		*
616	<	* @return true if elements moved backwards
616	>	* @return true if elements near tail moved backwards
617		*/
618		boolean delete(int i) {
619		// checkInvariants();
620	<	final Object[] elements = this.elements;
621	<	final int capacity = elements.length;
622	<	final int h = head;
623	<	int front;              // number of elements before to-be-deleted elt
624	<	if ((front = i - h) < 0) front += capacity;
625	<	final int back = size - front - 1; // number of elements after
620	>	final Object[] es = elements;
621	>	final int capacity = es.length;
622	>	final int h, t;
623	>	// number of elements before to-be-deleted elt
624	>	final int front = sub(i, h = head, capacity);
625	>	// number of elements after to-be-deleted elt
626	>	final int back = sub(t = tail, i, capacity) - 1;
627		if (front < back) {
628		// move front elements forwards
629		if (h <= i) {
630	<	System.arraycopy(elements, h, elements, h + 1, front);
630	>	System.arraycopy(es, h, es, h + 1, front);
631		} else { // Wrap around
632	<	System.arraycopy(elements, 0, elements, 1, i);
633	<	elements[0] = elements[capacity - 1];
634	<	System.arraycopy(elements, h, elements, h + 1, front - (i + 1));
632	>	System.arraycopy(es, 0, es, 1, i);
633	>	es[0] = es[capacity - 1];
634	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
635		}
636	<	elements[h] = null;
637	<	if ((head = (h + 1)) >= capacity) head = 0;
634	<	size--;
636	>	es[h] = null;
637	>	head = inc(h, capacity);
638		// checkInvariants();
639		return false;
640		} else {
641		// move back elements backwards
642	<	int tail = tail();
642	>	tail = dec(t, capacity);
643		if (i <= tail) {
644	<	System.arraycopy(elements, i + 1, elements, i, back);
644	>	System.arraycopy(es, i + 1, es, i, back);
645		} else { // Wrap around
646	<	int firstLeg = capacity - (i + 1);
647	<	System.arraycopy(elements, i + 1, elements, i, firstLeg);
648	<	elements[capacity - 1] = elements[0];
646	<	System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1);
646	>	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
647	>	es[capacity - 1] = es[0];
648	>	System.arraycopy(es, 1, es, 0, t - 1);
649		}
650	<	elements[tail] = null;
649	<	size--;
650	>	es[tail] = null;
651		// checkInvariants();
652		return true;
653		}
#	Line 660 | Line 661 | public class ArrayDeque<E> extends Abstr
661		* @return the number of elements in this deque
662		*/
663		public int size() {
664	<	return size;
664	>	return sub(tail, head, elements.length);
665		}
666
667		/**
#	Line 669 | Line 670 | public class ArrayDeque<E> extends Abstr
670		* @return {@code true} if this deque contains no elements
671		*/
672		public boolean isEmpty() {
673	<	return size == 0;
673	>	return head == tail;
674		}
675
676		/**
#	Line 693 | Line 694 | public class ArrayDeque<E> extends Abstr
694		int cursor;
695
696		/** Number of elements yet to be returned. */
697	<	int remaining = size;
697	>	int remaining = size();
698
699		/**
700		* Index of element returned by most recent call to next.
#	Line 710 | Line 711 | public class ArrayDeque<E> extends Abstr
711		public E next() {
712		if (remaining <= 0)
713		throw new NoSuchElementException();
714	<	final Object[] elements = ArrayDeque.this.elements;
715	<	E e = nonNullElementAt(elements, cursor);
716	<	lastRet = cursor;
716	<	if (++cursor >= elements.length) cursor = 0;
714	>	final Object[] es = elements;
715	>	E e = nonNullElementAt(es, cursor);
716	>	cursor = inc(lastRet = cursor, es.length);
717		remaining--;
718		return e;
719		}
720
721		void postDelete(boolean leftShifted) {
722		if (leftShifted)
723	<	if (--cursor < 0) cursor = elements.length - 1;
723	>	cursor = dec(cursor, elements.length);
724		}
725
726		public final void remove() {
#	Line 731 | Line 731 | public class ArrayDeque<E> extends Abstr
731		}
732
733		public void forEachRemaining(Consumer<? super E> action) {
734	<	final int k;
735	<	if ((k = remaining) > 0) {
736	<	remaining = 0;
737	<	ArrayDeque.forEachRemaining(action, elements, cursor, k);
738	<	if ((lastRet = cursor + k - 1) >= elements.length)
739	<	lastRet -= elements.length;
734	>	Objects.requireNonNull(action);
735	>	int r;
736	>	if ((r = remaining) <= 0)
737	>	return;
738	>	remaining = 0;
739	>	final Object[] es = elements;
740	>	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
741	>	throw new ConcurrentModificationException();
742	>	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
743	>	; i = 0, to = end) {
744	>	for (; i < to; i++)
745	>	action.accept(elementAt(es, i));
746	>	if (to == end) {
747	>	if (end != tail)
748	>	throw new ConcurrentModificationException();
749	>	lastRet = dec(end, es.length);
750	>	break;
751	>	}
752		}
753		}
754		}
755
756		private class DescendingIterator extends DeqIterator {
757	<	DescendingIterator() { cursor = tail(); }
757	>	DescendingIterator() { cursor = dec(tail, elements.length); }
758
759		public final E next() {
760		if (remaining <= 0)
761		throw new NoSuchElementException();
762	<	final Object[] elements = ArrayDeque.this.elements;
763	<	E e = nonNullElementAt(elements, cursor);
764	<	lastRet = cursor;
753	<	if (--cursor < 0) cursor = elements.length - 1;
762	>	final Object[] es = elements;
763	>	E e = nonNullElementAt(es, cursor);
764	>	cursor = dec(lastRet = cursor, es.length);
765		remaining--;
766		return e;
767		}
768
769		void postDelete(boolean leftShifted) {
770		if (!leftShifted)
771	<	if (++cursor >= elements.length) cursor = 0;
771	>	cursor = inc(cursor, elements.length);
772		}
773
774		public final void forEachRemaining(Consumer<? super E> action) {
775	<	final int k;
776	<	if ((k = remaining) > 0) {
777	<	remaining = 0;
778	<	forEachRemainingDescending(action, elements, cursor, k);
779	<	if ((lastRet = cursor - (k - 1)) < 0)
780	<	lastRet += elements.length;
775	>	Objects.requireNonNull(action);
776	>	int r;
777	>	if ((r = remaining) <= 0)
778	>	return;
779	>	remaining = 0;
780	>	final Object[] es = elements;
781	>	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
782	>	throw new ConcurrentModificationException();
783	>	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
784	>	; i = es.length - 1, to = end) {
785	>	// hotspot generates faster code than for: i >= to !
786	>	for (; i > to - 1; i--)
787	>	action.accept(elementAt(es, i));
788	>	if (to == end) {
789	>	if (end != head)
790	>	throw new ConcurrentModificationException();
791	>	lastRet = end;
792	>	break;
793	>	}
794		}
795		}
796		}
#	Line 785 | Line 809 | public class ArrayDeque<E> extends Abstr
809		* @since 1.8
810		*/
811		public Spliterator<E> spliterator() {
812	<	return new ArrayDequeSpliterator();
812	>	return new DeqSpliterator();
813		}
814
815	<	final class ArrayDequeSpliterator implements Spliterator<E> {
816	<	private int cursor;
817	<	private int remaining; // -1 until late-binding first use
815	>	final class DeqSpliterator implements Spliterator<E> {
816	>	private int fence;      // -1 until first use
817	>	private int cursor;     // current index, modified on traverse/split
818
819		/** Constructs late-binding spliterator over all elements. */
820	<	ArrayDequeSpliterator() {
821	<	this.remaining = -1;
798	<	}
799	<
800	<	/** Constructs spliterator over the given slice. */
801	<	ArrayDequeSpliterator(int cursor, int count) {
802	<	this.cursor = cursor;
803	<	this.remaining = count;
820	>	DeqSpliterator() {
821	>	this.fence = -1;
822		}
823
824	<	/** Ensures late-binding initialization; then returns remaining. */
825	<	private int remaining() {
826	<	if (remaining < 0) {
824	>	/** Constructs spliterator over the given range. */
825	>	DeqSpliterator(int origin, int fence) {
826	>	// assert 0 <= origin && origin < elements.length;
827	>	// assert 0 <= fence && fence < elements.length;
828	>	this.cursor = origin;
829	>	this.fence = fence;
830	>	}
831	>
832	>	/** Ensures late-binding initialization; then returns fence. */
833	>	private int getFence() { // force initialization
834	>	int t;
835	>	if ((t = fence) < 0) {
836	>	t = fence = tail;
837		cursor = head;
810	–	remaining = size;
838		}
839	<	return remaining;
839	>	return t;
840		}
841
842	<	public ArrayDequeSpliterator trySplit() {
843	<	final int mid;
844	<	if ((mid = remaining() >> 1) > 0) {
845	<	int oldCursor = cursor;
846	<	cursor = add(cursor, mid, elements.length);
847	<	remaining -= mid;
821	<	return new ArrayDequeSpliterator(oldCursor, mid);
822	<	}
823	<	return null;
842	>	public DeqSpliterator trySplit() {
843	>	final Object[] es = elements;
844	>	final int i, n;
845	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
846	>	? null
847	>	: new DeqSpliterator(i, cursor = inc(i, n, es.length));
848		}
849
850		public void forEachRemaining(Consumer<? super E> action) {
851	<	final int k = remaining(); // side effect!
852	<	remaining = 0;
853	<	ArrayDeque.forEachRemaining(action, elements, cursor, k);
851	>	if (action == null)
852	>	throw new NullPointerException();
853	>	final int end = getFence(), cursor = this.cursor;
854	>	final Object[] es = elements;
855	>	if (cursor != end) {
856	>	this.cursor = end;
857	>	// null check at both ends of range is sufficient
858	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
859	>	throw new ConcurrentModificationException();
860	>	for (int i = cursor, to = (i <= end) ? end : es.length;
861	>	; i = 0, to = end) {
862	>	for (; i < to; i++)
863	>	action.accept(elementAt(es, i));
864	>	if (to == end) break;
865	>	}
866	>	}
867		}
868
869		public boolean tryAdvance(Consumer<? super E> action) {
870		Objects.requireNonNull(action);
871	<	final int k;
872	<	if ((k = remaining()) <= 0)
871	>	final Object[] es = elements;
872	>	if (fence < 0) { fence = tail; cursor = head; } // late-binding
873	>	final int i;
874	>	if ((i = cursor) == fence)
875		return false;
876	<	action.accept(nonNullElementAt(elements, cursor));
877	<	if (++cursor >= elements.length) cursor = 0;
878	<	remaining = k - 1;
876	>	E e = nonNullElementAt(es, i);
877	>	cursor = inc(i, es.length);
878	>	action.accept(e);
879		return true;
880		}
881
882		public long estimateSize() {
883	<	return remaining();
883	>	return sub(getFence(), cursor, elements.length);
884		}
885
886		public int characteristics() {
#	Line 852 | Line 891 | public class ArrayDeque<E> extends Abstr
891		}
892		}
893
855	–	@SuppressWarnings("unchecked")
856	–	public void forEach(Consumer<? super E> action) {
857	–	Objects.requireNonNull(action);
858	–	final Object[] elements = this.elements;
859	–	final int capacity = elements.length;
860	–	int i, end, to, todo;
861	–	todo = (end = (i = head) + size)
862	–	- (to = (capacity - end >= 0) ? end : capacity);
863	–	for (;; to = todo, i = 0, todo = 0) {
864	–	for (; i < to; i++)
865	–	action.accept((E) elements[i]);
866	–	if (todo == 0) break;
867	–	}
868	–	// checkInvariants();
869	–	}
870	–
894		/**
895	<	* Calls action on remaining elements, starting at index i and
873	<	* traversing in ascending order.  A variant of forEach that also
874	<	* checks for concurrent modification, for use in iterators.
895	>	* @throws NullPointerException {@inheritDoc}
896		*/
897	<	static <E> void forEachRemaining(
877	<	Consumer<? super E> action, Object[] elements, int i, int remaining) {
897	>	public void forEach(Consumer<? super E> action) {
898		Objects.requireNonNull(action);
899	<	final int capacity = elements.length;
900	<	int end, to, todo;
901	<	todo = (end = i + remaining)
882	<	- (to = (capacity - end >= 0) ? end : capacity);
883	<	for (;; to = todo, i = 0, todo = 0) {
899	>	final Object[] es = elements;
900	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
901	>	; i = 0, to = end) {
902		for (; i < to; i++)
903	<	action.accept(nonNullElementAt(elements, i));
904	<	if (todo == 0) break;
905	<	}
906	<	}
907	<
890	<	static <E> void forEachRemainingDescending(
891	<	Consumer<? super E> action, Object[] elements, int i, int remaining) {
892	<	Objects.requireNonNull(action);
893	<	final int capacity = elements.length;
894	<	int end, to, todo;
895	<	todo = (to = ((end = i - remaining) >= -1) ? end : -1) - end;
896	<	for (;; to = (i = capacity - 1) - todo, todo = 0) {
897	<	for (; i > to; i--)
898	<	action.accept(nonNullElementAt(elements, i));
899	<	if (todo == 0) break;
903	>	action.accept(elementAt(es, i));
904	>	if (to == end) {
905	>	if (end != tail) throw new ConcurrentModificationException();
906	>	break;
907	>	}
908		}
909	+	// checkInvariants();
910		}
911
912		/**
#	Line 907 | Line 916 | public class ArrayDeque<E> extends Abstr
916		* @param operator the operator to apply to each element
917		* @since TBD
918		*/
919	<	/* public */ void replaceAll(UnaryOperator<E> operator) {
919	>	/* public */ void replaceAll(java.util.function.UnaryOperator<E> operator) {
920		Objects.requireNonNull(operator);
921	<	final Object[] elements = this.elements;
922	<	final int capacity = elements.length;
923	<	int i, end, to, todo;
915	<	todo = (end = (i = head) + size)
916	<	- (to = (capacity - end >= 0) ? end : capacity);
917	<	for (;; to = todo, i = 0, todo = 0) {
921	>	final Object[] es = elements;
922	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
923	>	; i = 0, to = end) {
924		for (; i < to; i++)
925	<	elements[i] = operator.apply(elementAt(i));
926	<	if (todo == 0) break;
925	>	es[i] = operator.apply(elementAt(es, i));
926	>	if (to == end) {
927	>	if (end != tail) throw new ConcurrentModificationException();
928	>	break;
929	>	}
930		}
931		// checkInvariants();
932		}
#	Line 949 | Line 958 | public class ArrayDeque<E> extends Abstr
958		/** Implementation of bulk remove methods. */
959		private boolean bulkRemove(Predicate<? super E> filter) {
960		// checkInvariants();
961	<	final Object[] elements = this.elements;
962	<	final int capacity = elements.length;
963	<	int i = head, j = i, remaining = size, deleted = 0;
964	<	try {
965	<	for (; remaining > 0; remaining--) {
966	<	@SuppressWarnings("unchecked") E e = (E) elements[i];
967	<	if (filter.test(e))
968	<	deleted++;
969	<	else {
970	<	if (j != i)
971	<	elements[j] = e;
972	<	if (++j >= capacity) j = 0;
973	<	}
974	<	if (++i >= capacity) i = 0;
961	>	final Object[] es = elements;
962	>	// Optimize for initial run of survivors
963	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
964	>	; i = 0, to = end) {
965	>	for (; i < to; i++)
966	>	if (filter.test(elementAt(es, i)))
967	>	return bulkRemoveModified(filter, i);
968	>	if (to == end) {
969	>	if (end != tail) throw new ConcurrentModificationException();
970	>	break;
971	>	}
972	>	}
973	>	return false;
974	>	}
975	>
976	>	// A tiny bit set implementation
977	>
978	>	private static long[] nBits(int n) {
979	>	return new long[((n - 1) >> 6) + 1];
980	>	}
981	>	private static void setBit(long[] bits, int i) {
982	>	bits[i >> 6] |= 1L << i;
983	>	}
984	>	private static boolean isClear(long[] bits, int i) {
985	>	return (bits[i >> 6] & (1L << i)) == 0;
986	>	}
987	>
988	>	/**
989	>	* Helper for bulkRemove, in case of at least one deletion.
990	>	* Tolerate predicates that reentrantly access the collection for
991	>	* read (but writers still get CME), so traverse once to find
992	>	* elements to delete, a second pass to physically expunge.
993	>	*
994	>	* @param beg valid index of first element to be deleted
995	>	*/
996	>	private boolean bulkRemoveModified(
997	>	Predicate<? super E> filter, final int beg) {
998	>	final Object[] es = elements;
999	>	final int capacity = es.length;
1000	>	final int end = tail;
1001	>	final long[] deathRow = nBits(sub(end, beg, capacity));
1002	>	deathRow[0] = 1L;   // set bit 0
1003	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1004	>	; i = 0, to = end, k -= capacity) {
1005	>	for (; i < to; i++)
1006	>	if (filter.test(elementAt(es, i)))
1007	>	setBit(deathRow, i - k);
1008	>	if (to == end) break;
1009	>	}
1010	>	// a two-finger traversal, with hare i reading, tortoise w writing
1011	>	int w = beg;
1012	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1013	>	; w = 0) { // w rejoins i on second leg
1014	>	// In this loop, i and w are on the same leg, with i > w
1015	>	for (; i < to; i++)
1016	>	if (isClear(deathRow, i - k))
1017	>	es[w++] = es[i];
1018	>	if (to == end) break;
1019	>	// In this loop, w is on the first leg, i on the second
1020	>	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1021	>	if (isClear(deathRow, i - k))
1022	>	es[w++] = es[i];
1023	>	if (i >= to) {
1024	>	if (w == capacity) w = 0; // "corner" case
1025	>	break;
1026		}
967	–	return deleted > 0;
968	–	} catch (Throwable ex) {
969	–	if (deleted > 0)
970	–	for (; remaining > 0; remaining--) {
971	–	elements[j] = elements[i];
972	–	if (++i >= capacity) i = 0;
973	–	if (++j >= capacity) j = 0;
974	–	}
975	–	throw ex;
976	–	} finally {
977	–	size -= deleted;
978	–	clearSlice(elements, j, deleted);
979	–	// checkInvariants();
1027		}
1028	+	if (end != tail) throw new ConcurrentModificationException();
1029	+	circularClear(es, tail = w, end);
1030	+	// checkInvariants();
1031	+	return true;
1032		}
1033
1034		/**
#	Line 990 | Line 1041 | public class ArrayDeque<E> extends Abstr
1041		*/
1042		public boolean contains(Object o) {
1043		if (o != null) {
1044	<	final Object[] elements = this.elements;
1045	<	final int capacity = elements.length;
1046	<	int i, end, to, todo;
996	<	todo = (end = (i = head) + size)
997	<	- (to = (capacity - end >= 0) ? end : capacity);
998	<	for (;; to = todo, i = 0, todo = 0) {
1044	>	final Object[] es = elements;
1045	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1046	>	; i = 0, to = end) {
1047		for (; i < to; i++)
1048	<	if (o.equals(elements[i]))
1048	>	if (o.equals(es[i]))
1049		return true;
1050	<	if (todo == 0) break;
1050	>	if (to == end) break;
1051		}
1052		}
1053		return false;
#	Line 1027 | Line 1075 | public class ArrayDeque<E> extends Abstr
1075		* The deque will be empty after this call returns.
1076		*/
1077		public void clear() {
1078	<	clearSlice(elements, head, size);
1079	<	size = head = 0;
1078	>	circularClear(elements, head, tail);
1079	>	head = tail = 0;
1080		// checkInvariants();
1081		}
1082
1083		/**
1084	<	* Nulls out count elements, starting at array index from.
1084	>	* Nulls out slots starting at array index i, upto index end.
1085	>	* Condition i == end means "empty" - nothing to do.
1086		*/
1087	<	private static void clearSlice(Object[] elements, int from, int count) {
1088	<	final int capacity = elements.length, end = from + count;
1089	<	final int leg = (capacity - end >= 0) ? end : capacity;
1090	<	Arrays.fill(elements, from, leg, null);
1091	<	if (leg != end)
1092	<	Arrays.fill(elements, 0, end - capacity, null);
1087	>	private static void circularClear(Object[] es, int i, int end) {
1088	>	// assert 0 <= i && i < es.length;
1089	>	// assert 0 <= end && end < es.length;
1090	>	for (int to = (i <= end) ? end : es.length;
1091	>	; i = 0, to = end) {
1092	>	for (; i < to; i++) es[i] = null;
1093	>	if (to == end) break;
1094	>	}
1095		}
1096
1097		/**
#	Line 1061 | Line 1112 | public class ArrayDeque<E> extends Abstr
1112		}
1113
1114		private <T> T[] toArray(Class<T[]> klazz) {
1115	<	final Object[] elements = this.elements;
1065	<	final int capacity = elements.length;
1066	<	final int head = this.head, end = head + size;
1115	>	final Object[] es = elements;
1116		final T[] a;
1117	<	if (end >= 0) {
1118	<	a = Arrays.copyOfRange(elements, head, end, klazz);
1117	>	final int head = this.head, tail = this.tail, end;
1118	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1119	>	// Uses null extension feature of copyOfRange
1120	>	a = Arrays.copyOfRange(es, head, end, klazz);
1121		} else {
1122		// integer overflow!
1123	<	a = Arrays.copyOfRange(elements, 0, size, klazz);
1124	<	System.arraycopy(elements, head, a, 0, capacity - head);
1123	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1124	>	System.arraycopy(es, head, a, 0, es.length - head);
1125		}
1126	<	if (end - capacity > 0)
1127	<	System.arraycopy(elements, 0, a, capacity - head, end - capacity);
1126	>	if (end != tail)
1127	>	System.arraycopy(es, 0, a, es.length - head, tail);
1128		return a;
1129		}
1130
#	Line 1115 | Line 1166 | public class ArrayDeque<E> extends Abstr
1166		*/
1167		@SuppressWarnings("unchecked")
1168		public <T> T[] toArray(T[] a) {
1169	<	final int size = this.size;
1170	<	if (size > a.length)
1169	>	final int size;
1170	>	if ((size = size()) > a.length)
1171		return toArray((Class<T[]>) a.getClass());
1172	<	final Object[] elements = this.elements;
1173	<	final int capacity = elements.length;
1174	<	final int head = this.head, end = head + size;
1175	<	final int front = (capacity - end >= 0) ? size : capacity - head;
1176	<	System.arraycopy(elements, head, a, 0, front);
1177	<	if (front != size)
1127	<	System.arraycopy(elements, 0, a, capacity - head, end - capacity);
1172	>	final Object[] es = elements;
1173	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1174	>	; i = 0, len = tail) {
1175	>	System.arraycopy(es, i, a, j, len);
1176	>	if ((j += len) == size) break;
1177	>	}
1178		if (size < a.length)
1179		a[size] = null;
1180		return a;
#	Line 1164 | Line 1214 | public class ArrayDeque<E> extends Abstr
1214		s.defaultWriteObject();
1215
1216		// Write out size
1217	<	s.writeInt(size);
1217	>	s.writeInt(size());
1218
1219		// Write out elements in order.
1220	<	final Object[] elements = this.elements;
1221	<	final int capacity = elements.length;
1222	<	int i, end, to, todo;
1173	<	todo = (end = (i = head) + size)
1174	<	- (to = (capacity - end >= 0) ? end : capacity);
1175	<	for (;; to = todo, i = 0, todo = 0) {
1220	>	final Object[] es = elements;
1221	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1222	>	; i = 0, to = end) {
1223		for (; i < to; i++)
1224	<	s.writeObject(elements[i]);
1225	<	if (todo == 0) break;
1224	>	s.writeObject(es[i]);
1225	>	if (to == end) break;
1226		}
1227		}
1228
#	Line 1191 | Line 1238 | public class ArrayDeque<E> extends Abstr
1238		s.defaultReadObject();
1239
1240		// Read in size and allocate array
1241	<	elements = new Object[size = s.readInt()];
1241	>	int size = s.readInt();
1242	>	jsr166.Platform.checkArray(s, Object[].class, size + 1);
1243	>	elements = new Object[size + 1];
1244	>	this.tail = size;
1245
1246		// Read in all elements in the proper order.
1247		for (int i = 0; i < size; i++)
#	Line 1200 | Line 1250 | public class ArrayDeque<E> extends Abstr
1250
1251		/** debugging */
1252		void checkInvariants() {
1253	+	// Use head and tail fields with empty slot at tail strategy.
1254	+	// head == tail disambiguates to "empty".
1255		try {
1256		int capacity = elements.length;
1257	<	// assert size >= 0 && size <= capacity;
1258	<	// assert head >= 0;
1259	<	// assert capacity == 0 || head < capacity;
1260	<	// assert size == 0 || elements[head] != null;
1261	<	// assert size == 0 || elements[tail()] != null;
1262	<	// assert size == capacity || elements[dec(head, capacity)] == null;
1263	<	// assert size == capacity || elements[inc(tail(), capacity)] == null;
1257	>	// assert 0 <= head && head < capacity;
1258	>	// assert 0 <= tail && tail < capacity;
1259	>	// assert capacity > 0;
1260	>	// assert size() < capacity;
1261	>	// assert head == tail || elements[head] != null;
1262	>	// assert elements[tail] == null;
1263	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1264		} catch (Throwable t) {
1265	<	System.err.printf("head=%d size=%d capacity=%d%n",
1266	<	head, size, elements.length);
1265	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1266	>	head, tail, elements.length);
1267		System.err.printf("elements=%s%n",
1268		Arrays.toString(elements));
1269		throw t;

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