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Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.99 by jsr166, Sun Oct 30 16:32:40 2016 UTC vs.
Revision 1.132 by jsr166, Sun Oct 22 17:44:02 2017 UTC

#	Line 9 | Line 9 | import java.io.Serializable;
9		import java.util.function.Consumer;
10		import java.util.function.Predicate;
11		import java.util.function.UnaryOperator;
12	+	import jdk.internal.misc.SharedSecrets;
13
14		/**
15		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 50 | Line 51 | import java.util.function.UnaryOperator;
51		* Iterator} interfaces.
52		*
53		* <p>This class is a member of the
54	<	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
54	>	* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
55		* Java Collections Framework</a>.
56		*
57		* @author  Josh Bloch and Doug Lea
#	Line 60 | Line 61 | import java.util.function.UnaryOperator;
61		public class ArrayDeque<E> extends AbstractCollection<E>
62		implements Deque<E>, Cloneable, Serializable
63		{
64	+	/*
65	+	* VMs excel at optimizing simple array loops where indices are
66	+	* incrementing or decrementing over a valid slice, e.g.
67	+	*
68	+	* for (int i = start; i < end; i++) ... elements[i]
69	+	*
70	+	* Because in a circular array, elements are in general stored in
71	+	* two disjoint such slices, we help the VM by writing unusual
72	+	* nested loops for all traversals over the elements.  Having only
73	+	* one hot inner loop body instead of two or three eases human
74	+	* maintenance and encourages VM loop inlining into the caller.
75	+	*/
76	+
77		/**
78		* The array in which the elements of the deque are stored.
79	<	* We guarantee that all array cells not holding deque elements
80	<	* are always null.
79	>	* All array cells not holding deque elements are always null.
80	>	* The array always has at least one null slot (at tail).
81		*/
82		transient Object[] elements;
83
84		/**
85		* The index of the element at the head of the deque (which is the
86		* element that would be removed by remove() or pop()); or an
87	<	* arbitrary number 0 <= head < elements.length if the deque is empty.
87	>	* arbitrary number 0 <= head < elements.length equal to tail if
88	>	* the deque is empty.
89		*/
90		transient int head;
91
92	<	/** Number of elements in this collection. */
93	<	transient int size;
92	>	/**
93	>	* The index at which the next element would be added to the tail
94	>	* of the deque (via addLast(E), add(E), or push(E));
95	>	* elements[tail] is always null.
96	>	*/
97	>	transient int tail;
98
99		/**
100		* The maximum size of array to allocate.
#	Line 92 | Line 111 | public class ArrayDeque<E> extends Abstr
111		*/
112		private void grow(int needed) {
113		// overflow-conscious code
95	–	// checkInvariants();
114		final int oldCapacity = elements.length;
115		int newCapacity;
116	<	// Double size if small; else grow by 50%
116	>	// Double capacity if small; else grow by 50%
117		int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
118		if (jump < needed
119		|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
120		newCapacity = newCapacity(needed, jump);
121	<	elements = Arrays.copyOf(elements, newCapacity);
122	<	if (oldCapacity - head < size) {
121	>	final Object[] es = elements = Arrays.copyOf(elements, newCapacity);
122	>	// Exceptionally, here tail == head needs to be disambiguated
123	>	if (tail < head || (tail == head && es[head] != null)) {
124		// wrap around; slide first leg forward to end of array
125		int newSpace = newCapacity - oldCapacity;
126	<	System.arraycopy(elements, head,
127	<	elements, head + newSpace,
126	>	System.arraycopy(es, head,
127	>	es, head + newSpace,
128		oldCapacity - head);
129	<	Arrays.fill(elements, head, head + newSpace, null);
130	<	head += newSpace;
129	>	for (int i = head, to = (head += newSpace); i < to; i++)
130	>	es[i] = null;
131		}
132		// checkInvariants();
133		}
#	Line 136 | Line 155 | public class ArrayDeque<E> extends Abstr
155		* @since TBD
156		*/
157		/* public */ void ensureCapacity(int minCapacity) {
158	<	if (minCapacity > elements.length)
159	<	grow(minCapacity - elements.length);
158	>	int needed;
159	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
160	>	grow(needed);
161		// checkInvariants();
162		}
163
#	Line 147 | Line 167 | public class ArrayDeque<E> extends Abstr
167		* @since TBD
168		*/
169		/* public */ void trimToSize() {
170	<	if (size < elements.length) {
171	<	elements = toArray();
170	>	int size;
171	>	if ((size = size()) + 1 < elements.length) {
172	>	elements = toArray(new Object[size + 1]);
173		head = 0;
174	+	tail = size;
175		}
176		// checkInvariants();
177		}
#	Line 169 | Line 191 | public class ArrayDeque<E> extends Abstr
191		* @param numElements lower bound on initial capacity of the deque
192		*/
193		public ArrayDeque(int numElements) {
194	<	elements = new Object[numElements];
194	>	elements =
195	>	new Object[(numElements < 1) ? 1 :
196	>	(numElements == Integer.MAX_VALUE) ? Integer.MAX_VALUE :
197	>	numElements + 1];
198		}
199
200		/**
#	Line 183 | Line 208 | public class ArrayDeque<E> extends Abstr
208		* @throws NullPointerException if the specified collection is null
209		*/
210		public ArrayDeque(Collection<? extends E> c) {
211	<	Object[] es = c.toArray();
212	<	// 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;
211	>	this(c.size());
212	>	addAll(c);
213		}
214
215		/**
216	<	* Increments i, mod modulus.
216	>	* Circularly increments i, mod modulus.
217		* Precondition and postcondition: 0 <= i < modulus.
218		*/
219		static final int inc(int i, int modulus) {
#	Line 204 | Line 222 | public class ArrayDeque<E> extends Abstr
222		}
223
224		/**
225	<	* Decrements i, mod modulus.
225	>	* Circularly decrements i, mod modulus.
226		* Precondition and postcondition: 0 <= i < modulus.
227		*/
228		static final int dec(int i, int modulus) {
#	Line 213 | Line 231 | public class ArrayDeque<E> extends Abstr
231		}
232
233		/**
234	<	* Adds i and j, mod modulus.
235	<	* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus.
234	>	* Circularly adds the given distance to index i, mod modulus.
235	>	* Precondition: 0 <= i < modulus, 0 <= distance <= modulus.
236	>	* @return index 0 <= i < modulus
237		*/
238	<	static final int add(int i, int j, int modulus) {
239	<	if ((i += j) - modulus >= 0) i -= modulus;
238	>	static final int inc(int i, int distance, int modulus) {
239	>	if ((i += distance) - modulus >= 0) i -= modulus;
240		return i;
241		}
242
243		/**
244	<	* Returns the array index of the last element.
245	<	* May return invalid index -1 if there are no elements.
244	>	* Subtracts j from i, mod modulus.
245	>	* Index i must be logically ahead of index j.
246	>	* Precondition: 0 <= i < modulus, 0 <= j < modulus.
247	>	* @return the "circular distance" from j to i; corner case i == j
248	>	* is disambiguated to "empty", returning 0.
249		*/
250	<	final int tail() {
251	<	return add(head, size - 1, elements.length);
250	>	static final int sub(int i, int j, int modulus) {
251	>	if ((i -= j) < 0) i += modulus;
252	>	return i;
253		}
254
255		/**
256		* Returns element at array index i.
257	+	* This is a slight abuse of generics, accepted by javac.
258		*/
259		@SuppressWarnings("unchecked")
260	<	private E elementAt(int i) {
261	<	return (E) elements[i];
260	>	static final <E> E elementAt(Object[] es, int i) {
261	>	return (E) es[i];
262		}
263
264		/**
265		* A version of elementAt that checks for null elements.
266		* This check doesn't catch all possible comodifications,
267	<	* but does catch ones that corrupt traversal.  It's a little
244	<	* surprising that javac allows this abuse of generics.
267	>	* but does catch ones that corrupt traversal.
268		*/
269		static final <E> E nonNullElementAt(Object[] es, int i) {
270		@SuppressWarnings("unchecked") E e = (E) es[i];
#	Line 261 | Line 284 | public class ArrayDeque<E> extends Abstr
284		* @throws NullPointerException if the specified element is null
285		*/
286		public void addFirst(E e) {
287	<	// checkInvariants();
288	<	Objects.requireNonNull(e);
289	<	Object[] es;
290	<	int capacity, h;
291	<	final int s;
269	<	if ((s = size) == (capacity = (es = elements).length)) {
287	>	if (e == null)
288	>	throw new NullPointerException();
289	>	final Object[] es = elements;
290	>	es[head = dec(head, es.length)] = e;
291	>	if (head == tail)
292		grow(1);
271	–	capacity = (es = elements).length;
272	–	}
273	–	if ((h = head - 1) < 0) h = capacity - 1;
274	–	es[head = h] = e;
275	–	size = s + 1;
293		// checkInvariants();
294		}
295
#	Line 285 | Line 302 | public class ArrayDeque<E> extends Abstr
302		* @throws NullPointerException if the specified element is null
303		*/
304		public void addLast(E e) {
305	<	// checkInvariants();
306	<	Objects.requireNonNull(e);
307	<	Object[] es;
308	<	int capacity;
309	<	final int s;
293	<	if ((s = size) == (capacity = (es = elements).length)) {
305	>	if (e == null)
306	>	throw new NullPointerException();
307	>	final Object[] es = elements;
308	>	es[tail] = e;
309	>	if (head == (tail = inc(tail, es.length)))
310		grow(1);
295	–	capacity = (es = elements).length;
296	–	}
297	–	es[add(head, s, capacity)] = e;
298	–	size = s + 1;
311		// checkInvariants();
312		}
313
314		/**
315		* Adds all of the elements in the specified collection at the end
316		* of this deque, as if by calling {@link #addLast} on each one,
317	<	* in the order that they are returned by the collection's
306	<	* iterator.
317	>	* in the order that they are returned by the collection's iterator.
318		*
319		* @param c the elements to be inserted into this deque
320		* @return {@code true} if this deque changed as a result of the call
#	Line 311 | Line 322 | public class ArrayDeque<E> extends Abstr
322		*         of its elements are null
323		*/
324		public boolean addAll(Collection<? extends E> c) {
325	<	final int s = size, needed = c.size() - (elements.length - s);
326	<	if (needed > 0)
325	>	final int s, needed;
326	>	if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0)
327		grow(needed);
328	<	c.forEach((e) -> addLast(e));
328	>	c.forEach(this::addLast);
329		// checkInvariants();
330	<	return size > s;
330	>	return size() > s;
331		}
332
333		/**
#	Line 347 | Line 358 | public class ArrayDeque<E> extends Abstr
358		* @throws NoSuchElementException {@inheritDoc}
359		*/
360		public E removeFirst() {
350	–	// checkInvariants();
361		E e = pollFirst();
362		if (e == null)
363		throw new NoSuchElementException();
364	+	// checkInvariants();
365		return e;
366		}
367
#	Line 358 | Line 369 | public class ArrayDeque<E> extends Abstr
369		* @throws NoSuchElementException {@inheritDoc}
370		*/
371		public E removeLast() {
361	–	// checkInvariants();
372		E e = pollLast();
373		if (e == null)
374		throw new NoSuchElementException();
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();
370	–	int s, h;
371	–	if ((s = size) <= 0)
372	–	return null;
373	–	final Object[] es = elements;
374	–	@SuppressWarnings("unchecked") E e = (E) es[h = head];
375	–	es[h] = null;
376	–	if (++h >= es.length) h = 0;
377	–	head = h;
378	–	size = s - 1;
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();
384	–	final int s, tail;
385	–	if ((s = size) <= 0)
386	–	return null;
387	–	final Object[] es = elements;
388	–	@SuppressWarnings("unchecked")
389	–	E e = (E) es[tail = add(head, s - 1, es.length)];
390	–	es[tail] = null;
391	–	size = s - 1;
398		return e;
399		}
400
#	Line 396 | 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();
401	<	return elementAt(head);
409	>	return e;
410		}
411
412		/**
413		* @throws NoSuchElementException {@inheritDoc}
414		*/
407	–	@SuppressWarnings("unchecked")
415		public E getLast() {
409	–	// checkInvariants();
410	–	final int s;
411	–	if ((s = size) <= 0) throw new NoSuchElementException();
416		final Object[] es = elements;
417	<	return (E) es[add(head, s - 1, es.length)];
417	>	E e = elementAt(es, dec(tail, es.length));
418	>	if (e == null)
419	>	throw new NoSuchElementException();
420	>	// checkInvariants();
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
421	–	@SuppressWarnings("unchecked")
429		public E peekLast() {
430		// checkInvariants();
431	<	final int s;
432	<	if ((s = size) <= 0) return null;
426	<	final Object[] es = elements;
427	<	return (E) es[add(head, s - 1, es.length)];
431	>	final Object[] es;
432	>	return elementAt(es = elements, dec(tail, es.length));
433		}
434
435		/**
#	Line 442 | Line 447 | public class ArrayDeque<E> extends Abstr
447		public boolean removeFirstOccurrence(Object o) {
448		if (o != null) {
449		final Object[] es = elements;
450	<	int i, end, to, todo;
451	<	todo = (end = (i = head) + size)
447	<	- (to = (es.length - end >= 0) ? end : es.length);
448	<	for (;; to = todo, i = 0, todo = 0) {
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 (todo == 0) break;
457	>	if (to == end) break;
458		}
459		}
460		return false;
#	Line 472 | Line 475 | public class ArrayDeque<E> extends Abstr
475		public boolean removeLastOccurrence(Object o) {
476		if (o != null) {
477		final Object[] es = elements;
478	<	int i, to, end, todo;
479	<	todo = (to = ((end = (i = tail()) - size) >= -1) ? end : -1) - end;
480	<	for (;; to = (i = es.length - 1) - todo, todo = 0) {
478	<	for (; i > to; i--)
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 (todo == 0) break;
485	>	if (to == end) break;
486		}
487		}
488		return false;
#	Line 518 | Line 520 | public class ArrayDeque<E> extends Abstr
520		/**
521		* Retrieves and removes the head of the queue represented by this deque.
522		*
523	<	* This method differs from {@link #poll poll} only in that it throws an
524	<	* exception if this deque is empty.
523	>	* This method differs from {@link #poll() poll()} only in that it
524	>	* throws an exception if this deque is empty.
525		*
526		* <p>This method is equivalent to {@link #removeFirst}.
527		*
#	Line 608 | 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[] es = elements;
618		final int capacity = es.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
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) {
#	Line 628 | Line 631 | public class ArrayDeque<E> extends Abstr
631		System.arraycopy(es, h, es, h + 1, front - (i + 1));
632		}
633		es[h] = null;
634	<	if ((head = (h + 1)) >= capacity) head = 0;
632	<	size--;
634	>	head = inc(h, capacity);
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(es, i + 1, es, i, back);
642		} else { // Wrap around
643	<	int firstLeg = capacity - (i + 1);
642	<	System.arraycopy(es, i + 1, es, i, firstLeg);
643	>	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
644		es[capacity - 1] = es[0];
645	<	System.arraycopy(es, 1, es, 0, back - firstLeg - 1);
645	>	System.arraycopy(es, 1, es, 0, t - 1);
646		}
647		es[tail] = null;
647	–	size--;
648		// checkInvariants();
649		return true;
650		}
#	Line 658 | 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 667 | 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 691 | 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 710 | public class ArrayDeque<E> extends Abstr
710		throw new NoSuchElementException();
711		final Object[] es = elements;
712		E e = nonNullElementAt(es, cursor);
713	<	lastRet = cursor;
714	<	if (++cursor >= es.length) cursor = 0;
713	>	cursor = inc(lastRet = cursor, es.length);
714		remaining--;
715		return e;
716		}
717
718		void postDelete(boolean leftShifted) {
719		if (leftShifted)
720	<	if (--cursor < 0) cursor = elements.length - 1;
720	>	cursor = dec(cursor, elements.length);
721		}
722
723		public final void remove() {
#	Line 730 | Line 729 | public class ArrayDeque<E> extends Abstr
729
730		public void forEachRemaining(Consumer<? super E> action) {
731		Objects.requireNonNull(action);
732	<	final int k;
733	<	if ((k = remaining) > 0) {
734	<	remaining = 0;
735	<	ArrayDeque.forEachRemaining(action, elements, cursor, k);
736	<	if ((lastRet = cursor + k - 1) >= elements.length)
737	<	lastRet -= elements.length;
732	>	int r;
733	>	if ((r = remaining) <= 0)
734	>	return;
735	>	remaining = 0;
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)
758		throw new NoSuchElementException();
759		final Object[] es = elements;
760		E e = nonNullElementAt(es, cursor);
761	<	lastRet = cursor;
752	<	if (--cursor < 0) cursor = es.length - 1;
761	>	cursor = dec(lastRet = cursor, es.length);
762		remaining--;
763		return e;
764		}
765
766		void postDelete(boolean leftShifted) {
767		if (!leftShifted)
768	<	if (++cursor >= elements.length) cursor = 0;
768	>	cursor = inc(cursor, elements.length);
769		}
770
771		public final void forEachRemaining(Consumer<? super E> action) {
772		Objects.requireNonNull(action);
773	<	final int k;
774	<	if ((k = remaining) > 0) {
775	<	remaining = 0;
776	<	final Object[] es = elements;
777	<	int i, end, to, todo;
778	<	todo = (to = ((end = (i = cursor) - k) >= -1) ? end : -1) - end;
779	<	for (;; to = (i = es.length - 1) - todo, todo = 0) {
780	<	for (; i > to; i--)
781	<	action.accept(nonNullElementAt(es, i));
782	<	if (todo == 0) break;
773	>	int r;
774	>	if ((r = remaining) <= 0)
775	>	return;
776	>	remaining = 0;
777	>	final Object[] es = elements;
778	>	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
779	>	throw new ConcurrentModificationException();
780	>	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
781	>	; i = es.length - 1, to = end) {
782	>	// hotspot generates faster code than for: i >= to !
783	>	for (; i > to - 1; i--)
784	>	action.accept(elementAt(es, i));
785	>	if (to == end) {
786	>	if (end != head)
787	>	throw new ConcurrentModificationException();
788	>	lastRet = end;
789	>	break;
790		}
775	–	if ((lastRet = cursor - (k - 1)) < 0)
776	–	lastRet += es.length;
791		}
792		}
793		}
#	Line 792 | Line 806 | public class ArrayDeque<E> extends Abstr
806		* @since 1.8
807		*/
808		public Spliterator<E> spliterator() {
809	<	return new ArrayDequeSpliterator();
809	>	return new DeqSpliterator();
810		}
811
812	<	final class ArrayDequeSpliterator implements Spliterator<E> {
813	<	private int cursor;
814	<	private int remaining; // -1 until late-binding first use
812	>	final class DeqSpliterator implements Spliterator<E> {
813	>	private int fence;      // -1 until first use
814	>	private int cursor;     // current index, modified on traverse/split
815
816		/** Constructs late-binding spliterator over all elements. */
817	<	ArrayDequeSpliterator() {
818	<	this.remaining = -1;
805	<	}
806	<
807	<	/** Constructs spliterator over the given slice. */
808	<	ArrayDequeSpliterator(int cursor, int count) {
809	<	this.cursor = cursor;
810	<	this.remaining = count;
817	>	DeqSpliterator() {
818	>	this.fence = -1;
819		}
820
821	<	/** Ensures late-binding initialization; then returns remaining. */
822	<	private int remaining() {
823	<	if (remaining < 0) {
821	>	/** Constructs spliterator over the given range. */
822	>	DeqSpliterator(int origin, int fence) {
823	>	// assert 0 <= origin && origin < elements.length;
824	>	// assert 0 <= fence && fence < elements.length;
825	>	this.cursor = origin;
826	>	this.fence = fence;
827	>	}
828	>
829	>	/** Ensures late-binding initialization; then returns fence. */
830	>	private int getFence() { // force initialization
831	>	int t;
832	>	if ((t = fence) < 0) {
833	>	t = fence = tail;
834		cursor = head;
817	–	remaining = size;
835		}
836	<	return remaining;
836	>	return t;
837		}
838
839	<	public ArrayDequeSpliterator trySplit() {
840	<	final int mid;
841	<	if ((mid = remaining() >> 1) > 0) {
842	<	int oldCursor = cursor;
843	<	cursor = add(cursor, mid, elements.length);
844	<	remaining -= mid;
828	<	return new ArrayDequeSpliterator(oldCursor, mid);
829	<	}
830	<	return null;
839	>	public DeqSpliterator trySplit() {
840	>	final Object[] es = elements;
841	>	final int i, n;
842	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
843	>	? null
844	>	: new DeqSpliterator(i, cursor = inc(i, n, es.length));
845		}
846
847		public void forEachRemaining(Consumer<? super E> action) {
848	<	Objects.requireNonNull(action);
849	<	final int k = remaining(); // side effect!
850	<	remaining = 0;
851	<	ArrayDeque.forEachRemaining(action, elements, cursor, k);
848	>	if (action == null)
849	>	throw new NullPointerException();
850	>	final int end = getFence(), cursor = this.cursor;
851	>	final Object[] es = elements;
852	>	if (cursor != end) {
853	>	this.cursor = end;
854	>	// null check at both ends of range is sufficient
855	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
856	>	throw new ConcurrentModificationException();
857	>	for (int i = cursor, to = (i <= end) ? end : es.length;
858	>	; i = 0, to = end) {
859	>	for (; i < to; i++)
860	>	action.accept(elementAt(es, i));
861	>	if (to == end) break;
862	>	}
863	>	}
864		}
865
866		public boolean tryAdvance(Consumer<? super E> action) {
867		Objects.requireNonNull(action);
868	<	final int k;
869	<	if ((k = remaining()) <= 0)
868	>	final Object[] es = elements;
869	>	if (fence < 0) { fence = tail; cursor = head; } // late-binding
870	>	final int i;
871	>	if ((i = cursor) == fence)
872		return false;
873	<	action.accept(nonNullElementAt(elements, cursor));
874	<	if (++cursor >= elements.length) cursor = 0;
875	<	remaining = k - 1;
873	>	E e = nonNullElementAt(es, i);
874	>	cursor = inc(i, es.length);
875	>	action.accept(e);
876		return true;
877		}
878
879		public long estimateSize() {
880	<	return remaining();
880	>	return sub(getFence(), cursor, elements.length);
881		}
882
883		public int characteristics() {
#	Line 860 | Line 888 | public class ArrayDeque<E> extends Abstr
888		}
889		}
890
891	<	@SuppressWarnings("unchecked")
891	>	/**
892	>	* @throws NullPointerException {@inheritDoc}
893	>	*/
894		public void forEach(Consumer<? super E> action) {
895		Objects.requireNonNull(action);
896		final Object[] es = elements;
897	<	int i, end, to, todo;
898	<	todo = (end = (i = head) + size)
869	<	- (to = (es.length - end >= 0) ? end : es.length);
870	<	for (;; to = todo, i = 0, todo = 0) {
897	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
898	>	; i = 0, to = end) {
899		for (; i < to; i++)
900	<	action.accept((E) es[i]);
901	<	if (todo == 0) break;
900	>	action.accept(elementAt(es, i));
901	>	if (to == end) {
902	>	if (end != tail) throw new ConcurrentModificationException();
903	>	break;
904	>	}
905		}
906		// checkInvariants();
907		}
908
909		/**
879	–	* Calls action on remaining elements, starting at index i and
880	–	* traversing in ascending order.  A variant of forEach that also
881	–	* checks for concurrent modification, for use in iterators.
882	–	*/
883	–	static <E> void forEachRemaining(
884	–	Consumer<? super E> action, Object[] es, int i, int remaining) {
885	–	int end, to, todo;
886	–	todo = (end = i + remaining)
887	–	- (to = (es.length - end >= 0) ? end : es.length);
888	–	for (;; to = todo, i = 0, todo = 0) {
889	–	for (; i < to; i++)
890	–	action.accept(nonNullElementAt(es, i));
891	–	if (todo == 0) break;
892	–	}
893	–	}
894	–
895	–	/**
910		* Replaces each element of this deque with the result of applying the
911		* operator to that element, as specified by {@link List#replaceAll}.
912		*
913		* @param operator the operator to apply to each element
914		* @since TBD
915		*/
902	–	@SuppressWarnings("unchecked")
916		/* public */ void replaceAll(UnaryOperator<E> operator) {
917		Objects.requireNonNull(operator);
918		final Object[] es = elements;
919	<	int i, end, to, todo;
920	<	todo = (end = (i = head) + size)
908	<	- (to = (es.length - end >= 0) ? end : es.length);
909	<	for (;; to = todo, i = 0, todo = 0) {
919	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
920	>	; i = 0, to = end) {
921		for (; i < to; i++)
922	<	es[i] = operator.apply((E) es[i]);
923	<	if (todo == 0) break;
922	>	es[i] = operator.apply(elementAt(es, i));
923	>	if (to == end) {
924	>	if (end != tail) throw new ConcurrentModificationException();
925	>	break;
926	>	}
927		}
928		// checkInvariants();
929		}
#	Line 942 | Line 956 | public class ArrayDeque<E> extends Abstr
956		private boolean bulkRemove(Predicate<? super E> filter) {
957		// checkInvariants();
958		final Object[] es = elements;
959	+	// Optimize for initial run of survivors
960	+	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
961	+	; i = 0, to = end) {
962	+	for (; i < to; i++)
963	+	if (filter.test(elementAt(es, i)))
964	+	return bulkRemoveModified(filter, i);
965	+	if (to == end) {
966	+	if (end != tail) throw new ConcurrentModificationException();
967	+	break;
968	+	}
969	+	}
970	+	return false;
971	+	}
972	+
973	+	// A tiny bit set implementation
974	+
975	+	private static long[] nBits(int n) {
976	+	return new long[((n - 1) >> 6) + 1];
977	+	}
978	+	private static void setBit(long[] bits, int i) {
979	+	bits[i >> 6] |= 1L << i;
980	+	}
981	+	private static boolean isClear(long[] bits, int i) {
982	+	return (bits[i >> 6] & (1L << i)) == 0;
983	+	}
984	+
985	+	/**
986	+	* Helper for bulkRemove, in case of at least one deletion.
987	+	* Tolerate predicates that reentrantly access the collection for
988	+	* read (but writers still get CME), so traverse once to find
989	+	* elements to delete, a second pass to physically expunge.
990	+	*
991	+	* @param beg valid index of first element to be deleted
992	+	*/
993	+	private boolean bulkRemoveModified(
994	+	Predicate<? super E> filter, final int beg) {
995	+	final Object[] es = elements;
996		final int capacity = es.length;
997	<	int i = head, j = i, remaining = size, deleted = 0;
998	<	try {
999	<	for (; remaining > 0; remaining--) {
1000	<	@SuppressWarnings("unchecked") E e = (E) es[i];
1001	<	if (filter.test(e))
1002	<	deleted++;
1003	<	else {
1004	<	if (j != i)
1005	<	es[j] = e;
1006	<	if (++j >= capacity) j = 0;
1007	<	}
1008	<	if (++i >= capacity) i = 0;
997	>	final int end = tail;
998	>	final long[] deathRow = nBits(sub(end, beg, capacity));
999	>	deathRow[0] = 1L;   // set bit 0
1000	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1001	>	; i = 0, to = end, k -= capacity) {
1002	>	for (; i < to; i++)
1003	>	if (filter.test(elementAt(es, i)))
1004	>	setBit(deathRow, i - k);
1005	>	if (to == end) break;
1006	>	}
1007	>	// a two-finger traversal, with hare i reading, tortoise w writing
1008	>	int w = beg;
1009	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1010	>	; w = 0) { // w rejoins i on second leg
1011	>	// In this loop, i and w are on the same leg, with i > w
1012	>	for (; i < to; i++)
1013	>	if (isClear(deathRow, i - k))
1014	>	es[w++] = es[i];
1015	>	if (to == end) break;
1016	>	// In this loop, w is on the first leg, i on the second
1017	>	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1018	>	if (isClear(deathRow, i - k))
1019	>	es[w++] = es[i];
1020	>	if (i >= to) {
1021	>	if (w == capacity) w = 0; // "corner" case
1022	>	break;
1023		}
959	–	return deleted > 0;
960	–	} catch (Throwable ex) {
961	–	if (deleted > 0)
962	–	for (; remaining > 0; remaining--) {
963	–	es[j] = es[i];
964	–	if (++i >= capacity) i = 0;
965	–	if (++j >= capacity) j = 0;
966	–	}
967	–	throw ex;
968	–	} finally {
969	–	size -= deleted;
970	–	clearSlice(es, j, deleted);
971	–	// checkInvariants();
1024		}
1025	+	if (end != tail) throw new ConcurrentModificationException();
1026	+	circularClear(es, tail = w, end);
1027	+	// checkInvariants();
1028	+	return true;
1029		}
1030
1031		/**
#	Line 983 | Line 1039 | public class ArrayDeque<E> extends Abstr
1039		public boolean contains(Object o) {
1040		if (o != null) {
1041		final Object[] es = elements;
1042	<	int i, end, to, todo;
1043	<	todo = (end = (i = head) + size)
988	<	- (to = (es.length - end >= 0) ? end : es.length);
989	<	for (;; to = todo, i = 0, todo = 0) {
1042	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1043	>	; i = 0, to = end) {
1044		for (; i < to; i++)
1045		if (o.equals(es[i]))
1046		return true;
1047	<	if (todo == 0) break;
1047	>	if (to == end) break;
1048		}
1049		}
1050		return false;
#	Line 1018 | Line 1072 | public class ArrayDeque<E> extends Abstr
1072		* The deque will be empty after this call returns.
1073		*/
1074		public void clear() {
1075	<	clearSlice(elements, head, size);
1076	<	size = head = 0;
1075	>	circularClear(elements, head, tail);
1076	>	head = tail = 0;
1077		// checkInvariants();
1078		}
1079
1080		/**
1081	<	* Nulls out count elements, starting at array index i.
1081	>	* Nulls out slots starting at array index i, upto index end.
1082	>	* Condition i == end means "empty" - nothing to do.
1083		*/
1084	<	private static void clearSlice(Object[] es, int i, int count) {
1085	<	int end, to, todo;
1086	<	todo = (end = i + count)
1087	<	- (to = (es.length - end >= 0) ? end : es.length);
1088	<	for (;; to = todo, i = 0, todo = 0) {
1089	<	Arrays.fill(es, i, to, null);
1090	<	if (todo == 0) break;
1084	>	private static void circularClear(Object[] es, int i, int end) {
1085	>	// assert 0 <= i && i < es.length;
1086	>	// assert 0 <= end && end < es.length;
1087	>	for (int to = (i <= end) ? end : es.length;
1088	>	; i = 0, to = end) {
1089	>	for (; i < to; i++) es[i] = null;
1090	>	if (to == end) break;
1091		}
1092		}
1093
#	Line 1055 | Line 1110 | public class ArrayDeque<E> extends Abstr
1110
1111		private <T> T[] toArray(Class<T[]> klazz) {
1112		final Object[] es = elements;
1058	–	final int capacity = es.length;
1059	–	final int head = this.head, end = head + size;
1113		final T[] a;
1114	<	if (end >= 0) {
1114	>	final int head = this.head, tail = this.tail, end;
1115	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1116	>	// Uses null extension feature of copyOfRange
1117		a = Arrays.copyOfRange(es, head, end, klazz);
1118		} else {
1119		// integer overflow!
1120	<	a = Arrays.copyOfRange(es, 0, size, klazz);
1121	<	System.arraycopy(es, head, a, 0, capacity - head);
1120	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1121	>	System.arraycopy(es, head, a, 0, es.length - head);
1122		}
1123	<	if (end - capacity > 0)
1124	<	System.arraycopy(es, 0, a, capacity - head, end - capacity);
1123	>	if (end != tail)
1124	>	System.arraycopy(es, 0, a, es.length - head, tail);
1125		return a;
1126		}
1127
#	Line 1109 | Line 1164 | public class ArrayDeque<E> extends Abstr
1164		@SuppressWarnings("unchecked")
1165		public <T> T[] toArray(T[] a) {
1166		final int size;
1167	<	if ((size = this.size) > a.length)
1167	>	if ((size = size()) > a.length)
1168		return toArray((Class<T[]>) a.getClass());
1169		final Object[] es = elements;
1170	<	final int head = this.head, end = head + size;
1171	<	final int front = (es.length - end >= 0) ? size : es.length - head;
1172	<	System.arraycopy(es, head, a, 0, front);
1173	<	if (front < size)
1174	<	System.arraycopy(es, 0, a, front, size - front);
1170	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1171	>	; i = 0, len = tail) {
1172	>	System.arraycopy(es, i, a, j, len);
1173	>	if ((j += len) == size) break;
1174	>	}
1175		if (size < a.length)
1176		a[size] = null;
1177		return a;
#	Line 1156 | Line 1211 | public class ArrayDeque<E> extends Abstr
1211		s.defaultWriteObject();
1212
1213		// Write out size
1214	<	s.writeInt(size);
1214	>	s.writeInt(size());
1215
1216		// Write out elements in order.
1217		final Object[] es = elements;
1218	<	int i, end, to, todo;
1219	<	todo = (end = (i = head) + size)
1165	<	- (to = (es.length - end >= 0) ? end : es.length);
1166	<	for (;; to = todo, i = 0, todo = 0) {
1218	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1219	>	; i = 0, to = end) {
1220		for (; i < to; i++)
1221		s.writeObject(es[i]);
1222	<	if (todo == 0) break;
1222	>	if (to == end) break;
1223		}
1224		}
1225
#	Line 1182 | Line 1235 | public class ArrayDeque<E> extends Abstr
1235		s.defaultReadObject();
1236
1237		// Read in size and allocate array
1238	<	elements = new Object[size = s.readInt()];
1238	>	int size = s.readInt();
1239	>	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size + 1);
1240	>	elements = new Object[size + 1];
1241	>	this.tail = size;
1242
1243		// Read in all elements in the proper order.
1244		for (int i = 0; i < size; i++)
#	Line 1191 | Line 1247 | public class ArrayDeque<E> extends Abstr
1247
1248		/** debugging */
1249		void checkInvariants() {
1250	+	// Use head and tail fields with empty slot at tail strategy.
1251	+	// head == tail disambiguates to "empty".
1252		try {
1253		int capacity = elements.length;
1254	<	// assert size >= 0 && size <= capacity;
1255	<	// assert head >= 0;
1256	<	// assert capacity == 0 || head < capacity;
1257	<	// assert size == 0 || elements[head] != null;
1258	<	// assert size == 0 || elements[tail()] != null;
1259	<	// assert size == capacity || elements[dec(head, capacity)] == null;
1260	<	// assert size == capacity || elements[inc(tail(), capacity)] == null;
1254	>	// assert 0 <= head && head < capacity;
1255	>	// assert 0 <= tail && tail < capacity;
1256	>	// assert capacity > 0;
1257	>	// assert size() < capacity;
1258	>	// assert head == tail || elements[head] != null;
1259	>	// assert elements[tail] == null;
1260	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1261		} catch (Throwable t) {
1262	<	System.err.printf("head=%d size=%d capacity=%d%n",
1263	<	head, size, elements.length);
1262	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1263	>	head, tail, elements.length);
1264		System.err.printf("elements=%s%n",
1265		Arrays.toString(elements));
1266		throw t;

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