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

Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.77 by jsr166, Tue Oct 18 00:33:05 2016 UTC vs.
Revision 1.129 by jsr166, Wed May 31 19:01:08 2017 UTC

#	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/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
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) {
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		}
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 134 | Line 151 | public class ArrayDeque<E> extends Abstr
151		* to ensure that it can hold at least the given number of elements.
152		*
153		* @param minCapacity the desired minimum capacity
154	<	* @since 9
154	>	* @since TBD
155		*/
156	<	public void ensureCapacity(int minCapacity) {
157	<	if (minCapacity > elements.length)
158	<	grow(minCapacity - elements.length);
156	>	/* public */ void ensureCapacity(int minCapacity) {
157	>	int needed;
158	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
159	>	grow(needed);
160		// checkInvariants();
161		}
162
163		/**
164		* Minimizes the internal storage of this collection.
165		*
166	<	* @since 9
166	>	* @since TBD
167		*/
168	<	public void trimToSize() {
169	<	if (size < elements.length) {
170	<	elements = toArray();
168	>	/* public */ void trimToSize() {
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		/**
215	<	* Returns the array index of the last element.
216	<	* May return invalid index -1 if there are no elements.
215	>	* Increments i, mod modulus.
216	>	* Precondition and postcondition: 0 <= i < modulus.
217		*/
218	<	final int tail() {
219	<	return add(head, size - 1, elements.length);
218	>	static final int inc(int i, int modulus) {
219	>	if (++i >= modulus) i = 0;
220	>	return i;
221		}
222
223		/**
224	<	* Adds i and j, mod modulus.
225	<	* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus.
224	>	* Decrements i, mod modulus.
225	>	* Precondition and postcondition: 0 <= i < modulus.
226		*/
227	<	static final int add(int i, int j, int modulus) {
228	<	if ((i += j) - modulus >= 0) i -= modulus;
227	>	static final int dec(int i, int modulus) {
228	>	if (--i < 0) i = modulus - 1;
229		return i;
230		}
231
232		/**
233	<	* Increments i, mod modulus.
234	<	* Precondition and postcondition: 0 <= i < 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 inc(int i, int modulus) {
238	<	if (++i == modulus) i = 0;
237	>	static final int add(int i, int distance, int modulus) {
238	>	if ((i += distance) - modulus >= 0) i -= modulus;
239		return i;
240		}
241
242		/**
243	<	* Decrements i, mod modulus.
244	<	* Precondition and postcondition: 0 <= i < modulus.
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	<	static final int dec(int i, int modulus) {
250	<	if (--i < 0) i += modulus;
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	<	// checkInvariants();
287	<	Objects.requireNonNull(e);
288	<	Object[] elements;
289	<	int capacity, s = size;
290	<	while (s == (capacity = (elements = this.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);
292	<	elements[head = dec(head, capacity)] = e;
271	<	size = s + 1;
292	>	// checkInvariants();
293		}
294
295		/**
#	Line 280 | 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[] elements;
307	<	int capacity, s = size;
308	<	while (s == (capacity = (elements = this.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);
310	<	elements[add(head, s, capacity)] = e;
290	<	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
297	<	* 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
320		* @throws NullPointerException if the specified collection or any
321		*         of its elements are null
322		*/
304	–	@Override
323		public boolean addAll(Collection<? extends E> c) {
324	+	final int s, needed;
325	+	if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0)
326	+	grow(needed);
327	+	c.forEach(this::addLast);
328		// checkInvariants();
329	<	Object[] a, elements;
308	<	int len, capacity, s = size;
309	<	if ((len = (a = c.toArray()).length) == 0)
310	<	return false;
311	<	while ((capacity = (elements = this.elements).length) - s < len)
312	<	grow(len - (capacity - s));
313	<	int i = add(head, s, capacity);
314	<	for (Object x : a) {
315	<	Objects.requireNonNull(x);
316	<	elements[i] = x;
317	<	i = inc(i, capacity);
318	<	size++;
319	<	}
320	<	return true;
329	>	return size() > s;
330		}
331
332		/**
#	Line 348 | Line 357 | public class ArrayDeque<E> extends Abstr
357		* @throws NoSuchElementException {@inheritDoc}
358		*/
359		public E removeFirst() {
360	<	// checkInvariants();
361	<	E x = pollFirst();
353	<	if (x == null)
360	>	E e = pollFirst();
361	>	if (e == null)
362		throw new NoSuchElementException();
363	<	return x;
363	>	// checkInvariants();
364	>	return e;
365		}
366
367		/**
368		* @throws NoSuchElementException {@inheritDoc}
369		*/
370		public E removeLast() {
371	<	// checkInvariants();
372	<	E x = pollLast();
364	<	if (x == null)
371	>	E e = pollLast();
372	>	if (e == null)
373		throw new NoSuchElementException();
374	<	return x;
374	>	// checkInvariants();
375	>	return e;
376		}
377
378		public E pollFirst() {
379	+	final Object[] es;
380	+	final int h;
381	+	E e = elementAt(es = elements, h = head);
382	+	if (e != null) {
383	+	es[h] = null;
384	+	head = inc(h, es.length);
385	+	}
386		// checkInvariants();
371	–	final int s, h;
372	–	if ((s = size) == 0)
373	–	return null;
374	–	final Object[] elements = this.elements;
375	–	@SuppressWarnings("unchecked") E e = (E) elements[h = head];
376	–	elements[h] = null;
377	–	head = inc(h, elements.length);
378	–	size = s - 1;
387		return e;
388		}
389
390		public E pollLast() {
391	+	final Object[] es;
392	+	final int t;
393	+	E e = elementAt(es = elements, t = dec(tail, es.length));
394	+	if (e != null)
395	+	es[tail = t] = null;
396		// 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;
397		return e;
398		}
399
#	Line 396 | Line 401 | public class ArrayDeque<E> extends Abstr
401		* @throws NoSuchElementException {@inheritDoc}
402		*/
403		public E getFirst() {
404	+	E e = elementAt(elements, head);
405	+	if (e == null)
406	+	throw new NoSuchElementException();
407		// checkInvariants();
408	<	if (size == 0) throw new NoSuchElementException();
401	<	return elementAt(head);
408	>	return e;
409		}
410
411		/**
412		* @throws NoSuchElementException {@inheritDoc}
413		*/
414		public E getLast() {
415	+	final Object[] es = elements;
416	+	E e = elementAt(es, dec(tail, es.length));
417	+	if (e == null)
418	+	throw new NoSuchElementException();
419		// checkInvariants();
420	<	if (size == 0) throw new NoSuchElementException();
410	<	return elementAt(tail());
420	>	return e;
421		}
422
423		public E peekFirst() {
424		// checkInvariants();
425	<	return (size == 0) ? null : elementAt(head);
425	>	return elementAt(elements, head);
426		}
427
428		public E peekLast() {
429		// checkInvariants();
430	<	return (size == 0) ? null : elementAt(tail());
430	>	final Object[] es;
431	>	return elementAt(es = elements, dec(tail, es.length));
432		}
433
434		/**
#	Line 433 | Line 444 | public class ArrayDeque<E> extends Abstr
444		* @return {@code true} if the deque contained the specified element
445		*/
446		public boolean removeFirstOccurrence(Object o) {
436	–	// checkInvariants();
447		if (o != null) {
448	<	final Object[] elements = this.elements;
449	<	final int capacity = elements.length;
450	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) {
451	<	if (o.equals(elements[i])) {
452	<	delete(i);
453	<	return true;
454	<	}
448	>	final Object[] es = elements;
449	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
450	>	; i = 0, to = end) {
451	>	for (; i < to; i++)
452	>	if (o.equals(es[i])) {
453	>	delete(i);
454	>	return true;
455	>	}
456	>	if (to == end) break;
457		}
458		}
459		return false;
#	Line 461 | Line 473 | public class ArrayDeque<E> extends Abstr
473		*/
474		public boolean removeLastOccurrence(Object o) {
475		if (o != null) {
476	<	final Object[] elements = this.elements;
477	<	final int capacity = elements.length;
478	<	for (int k = size, i = add(head, k - 1, capacity);
479	<	--k >= 0; i = dec(i, capacity)) {
480	<	if (o.equals(elements[i])) {
481	<	delete(i);
482	<	return true;
483	<	}
476	>	final Object[] es = elements;
477	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
478	>	; i = es.length, to = end) {
479	>	for (i--; i > to - 1; i--)
480	>	if (o.equals(es[i])) {
481	>	delete(i);
482	>	return true;
483	>	}
484	>	if (to == end) break;
485		}
486		}
487		return false;
#	Line 506 | Line 519 | public class ArrayDeque<E> extends Abstr
519		/**
520		* Retrieves and removes the head of the queue represented by this deque.
521		*
522	<	* This method differs from {@link #poll poll} only in that it throws an
523	<	* exception if this deque is empty.
522	>	* This method differs from {@link #poll() poll()} only in that it
523	>	* throws an exception if this deque is empty.
524		*
525		* <p>This method is equivalent to {@link #removeFirst}.
526		*
#	Line 596 | Line 609 | public class ArrayDeque<E> extends Abstr
609		* <p>This method is called delete rather than remove to emphasize
610		* that its semantics differ from those of {@link List#remove(int)}.
611		*
612	<	* @return true if elements moved backwards
612	>	* @return true if elements near tail moved backwards
613		*/
614		boolean delete(int i) {
615		// checkInvariants();
616	<	final Object[] elements = this.elements;
617	<	final int capacity = elements.length;
618	<	final int h = head;
619	<	int front;              // number of elements before to-be-deleted elt
620	<	if ((front = i - h) < 0) front += capacity;
621	<	final int back = size - front - 1; // number of elements after
616	>	final Object[] es = elements;
617	>	final int capacity = es.length;
618	>	final int h, t;
619	>	// number of elements before to-be-deleted elt
620	>	final int front = sub(i, h = head, capacity);
621	>	// number of elements after to-be-deleted elt
622	>	final int back = sub(t = tail, i, capacity) - 1;
623		if (front < back) {
624		// move front elements forwards
625		if (h <= i) {
626	<	System.arraycopy(elements, h, elements, h + 1, front);
626	>	System.arraycopy(es, h, es, h + 1, front);
627		} else { // Wrap around
628	<	System.arraycopy(elements, 0, elements, 1, i);
629	<	elements[0] = elements[capacity - 1];
630	<	System.arraycopy(elements, h, elements, h + 1, front - (i + 1));
628	>	System.arraycopy(es, 0, es, 1, i);
629	>	es[0] = es[capacity - 1];
630	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
631		}
632	<	elements[h] = null;
632	>	es[h] = null;
633		head = inc(h, capacity);
620	–	size--;
634		// checkInvariants();
635		return false;
636		} else {
637		// move back elements backwards
638	<	int tail = tail();
638	>	tail = dec(t, capacity);
639		if (i <= tail) {
640	<	System.arraycopy(elements, i + 1, elements, i, back);
640	>	System.arraycopy(es, i + 1, es, i, back);
641		} else { // Wrap around
642	<	int firstLeg = capacity - (i + 1);
643	<	System.arraycopy(elements, i + 1, elements, i, firstLeg);
644	<	elements[capacity - 1] = elements[0];
632	<	System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1);
642	>	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
643	>	es[capacity - 1] = es[0];
644	>	System.arraycopy(es, 1, es, 0, t - 1);
645		}
646	<	elements[tail] = null;
635	<	size--;
646	>	es[tail] = null;
647		// checkInvariants();
648		return true;
649		}
#	Line 646 | Line 657 | public class ArrayDeque<E> extends Abstr
657		* @return the number of elements in this deque
658		*/
659		public int size() {
660	<	return size;
660	>	return sub(tail, head, elements.length);
661		}
662
663		/**
#	Line 655 | Line 666 | public class ArrayDeque<E> extends Abstr
666		* @return {@code true} if this deque contains no elements
667		*/
668		public boolean isEmpty() {
669	<	return size == 0;
669	>	return head == tail;
670		}
671
672		/**
#	Line 679 | Line 690 | public class ArrayDeque<E> extends Abstr
690		int cursor;
691
692		/** Number of elements yet to be returned. */
693	<	int remaining = size;
693	>	int remaining = size();
694
695		/**
696		* Index of element returned by most recent call to next.
#	Line 689 | Line 700 | public class ArrayDeque<E> extends Abstr
700
701		DeqIterator() { cursor = head; }
702
692	–	int advance(int i, int modulus) {
693	–	return inc(i, modulus);
694	–	}
695	–
696	–	void doRemove() {
697	–	if (delete(lastRet))
698	–	// if left-shifted, undo advance in next()
699	–	cursor = dec(cursor, elements.length);
700	–	}
701	–
703		public final boolean hasNext() {
704		return remaining > 0;
705		}
706
707	<	public final E next() {
708	<	if (remaining == 0)
707	>	public E next() {
708	>	if (remaining <= 0)
709		throw new NoSuchElementException();
710	<	E e = checkedElementAt(elements, cursor);
711	<	lastRet = cursor;
712	<	cursor = advance(cursor, elements.length);
710	>	final Object[] es = elements;
711	>	E e = nonNullElementAt(es, cursor);
712	>	cursor = inc(lastRet = cursor, es.length);
713		remaining--;
714		return e;
715		}
716
717	+	void postDelete(boolean leftShifted) {
718	+	if (leftShifted)
719	+	cursor = dec(cursor, elements.length);
720	+	}
721	+
722		public final void remove() {
723		if (lastRet < 0)
724		throw new IllegalStateException();
725	<	doRemove();
725	>	postDelete(delete(lastRet));
726		lastRet = -1;
727		}
728
729	<	public final void forEachRemaining(Consumer<? super E> action) {
729	>	public void forEachRemaining(Consumer<? super E> action) {
730		Objects.requireNonNull(action);
731	<	final Object[] elements = ArrayDeque.this.elements;
732	<	final int capacity = elements.length;
733	<	int k = remaining;
731	>	int r;
732	>	if ((r = remaining) <= 0)
733	>	return;
734		remaining = 0;
735	<	for (int i = cursor; --k >= 0; i = advance(i, capacity))
736	<	action.accept(checkedElementAt(elements, i));
735	>	final Object[] es = elements;
736	>	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
737	>	throw new ConcurrentModificationException();
738	>	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
739	>	; i = 0, to = end) {
740	>	for (; i < to; i++)
741	>	action.accept(elementAt(es, i));
742	>	if (to == end) {
743	>	if (end != tail)
744	>	throw new ConcurrentModificationException();
745	>	lastRet = dec(end, es.length);
746	>	break;
747	>	}
748	>	}
749		}
750		}
751
752		private class DescendingIterator extends DeqIterator {
753	<	DescendingIterator() { cursor = tail(); }
753	>	DescendingIterator() { cursor = dec(tail, elements.length); }
754
755	<	@Override int advance(int i, int modulus) {
756	<	return dec(i, modulus);
755	>	public final E next() {
756	>	if (remaining <= 0)
757	>	throw new NoSuchElementException();
758	>	final Object[] es = elements;
759	>	E e = nonNullElementAt(es, cursor);
760	>	cursor = dec(lastRet = cursor, es.length);
761	>	remaining--;
762	>	return e;
763		}
764
765	<	@Override void doRemove() {
766	<	if (!delete(lastRet))
743	<	// if right-shifted, undo advance in next
765	>	void postDelete(boolean leftShifted) {
766	>	if (!leftShifted)
767		cursor = inc(cursor, elements.length);
768		}
769	+
770	+	public final void forEachRemaining(Consumer<? super E> action) {
771	+	Objects.requireNonNull(action);
772	+	int r;
773	+	if ((r = remaining) <= 0)
774	+	return;
775	+	remaining = 0;
776	+	final Object[] es = elements;
777	+	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
778	+	throw new ConcurrentModificationException();
779	+	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
780	+	; i = es.length - 1, to = end) {
781	+	// hotspot generates faster code than for: i >= to !
782	+	for (; i > to - 1; i--)
783	+	action.accept(elementAt(es, i));
784	+	if (to == end) {
785	+	if (end != head)
786	+	throw new ConcurrentModificationException();
787	+	lastRet = end;
788	+	break;
789	+	}
790	+	}
791	+	}
792		}
793
794		/**
#	Line 759 | Line 805 | public class ArrayDeque<E> extends Abstr
805		* @since 1.8
806		*/
807		public Spliterator<E> spliterator() {
808	<	return new ArrayDequeSpliterator();
808	>	return new DeqSpliterator();
809		}
810
811	<	final class ArrayDequeSpliterator implements Spliterator<E> {
812	<	private int cursor;
813	<	private int remaining; // -1 until late-binding first use
811	>	final class DeqSpliterator implements Spliterator<E> {
812	>	private int fence;      // -1 until first use
813	>	private int cursor;     // current index, modified on traverse/split
814
815		/** Constructs late-binding spliterator over all elements. */
816	<	ArrayDequeSpliterator() {
817	<	this.remaining = -1;
816	>	DeqSpliterator() {
817	>	this.fence = -1;
818		}
819
820	<	/** Constructs spliterator over the given slice. */
821	<	ArrayDequeSpliterator(int cursor, int count) {
822	<	this.cursor = cursor;
823	<	this.remaining = count;
824	<	}
825	<
826	<	/** Ensures late-binding initialization; then returns remaining. */
827	<	private int remaining() {
828	<	if (remaining < 0) {
820	>	/** Constructs spliterator over the given range. */
821	>	DeqSpliterator(int origin, int fence) {
822	>	// assert 0 <= origin && origin < elements.length;
823	>	// assert 0 <= fence && fence < elements.length;
824	>	this.cursor = origin;
825	>	this.fence = fence;
826	>	}
827	>
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;
784	–	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;
795	<	return new ArrayDequeSpliterator(oldCursor, mid);
796	<	}
797	<	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 829 | Line 887 | public class ArrayDeque<E> extends Abstr
887		}
888		}
889
890	<	@Override
890	>	/**
891	>	* @throws NullPointerException {@inheritDoc}
892	>	*/
893		public void forEach(Consumer<? super E> action) {
834	–	// checkInvariants();
894		Objects.requireNonNull(action);
895	<	final Object[] elements = this.elements;
896	<	final int capacity = elements.length;
897	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
898	<	action.accept(elementAt(i));
895	>	final Object[] es = elements;
896	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
897	>	; i = 0, to = end) {
898	>	for (; i < to; i++)
899	>	action.accept(elementAt(es, i));
900	>	if (to == end) {
901	>	if (end != tail) throw new ConcurrentModificationException();
902	>	break;
903	>	}
904	>	}
905		// checkInvariants();
906		}
907
#	Line 845 | Line 910 | public class ArrayDeque<E> extends Abstr
910		* operator to that element, as specified by {@link List#replaceAll}.
911		*
912		* @param operator the operator to apply to each element
913	<	* @since 9
913	>	* @since TBD
914		*/
915	<	public void replaceAll(UnaryOperator<E> operator) {
915	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
916		Objects.requireNonNull(operator);
917	<	final Object[] elements = this.elements;
918	<	final int capacity = elements.length;
919	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
920	<	elements[i] = operator.apply(elementAt(i));
917	>	final Object[] es = elements;
918	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
919	>	; i = 0, to = end) {
920	>	for (; i < to; i++)
921	>	es[i] = operator.apply(elementAt(es, i));
922	>	if (to == end) {
923	>	if (end != tail) throw new ConcurrentModificationException();
924	>	break;
925	>	}
926	>	}
927		// checkInvariants();
928		}
929
930		/**
931		* @throws NullPointerException {@inheritDoc}
932		*/
862	–	@Override
933		public boolean removeIf(Predicate<? super E> filter) {
934		Objects.requireNonNull(filter);
935		return bulkRemove(filter);
#	Line 868 | Line 938 | public class ArrayDeque<E> extends Abstr
938		/**
939		* @throws NullPointerException {@inheritDoc}
940		*/
871	–	@Override
941		public boolean removeAll(Collection<?> c) {
942		Objects.requireNonNull(c);
943		return bulkRemove(e -> c.contains(e));
#	Line 877 | Line 946 | public class ArrayDeque<E> extends Abstr
946		/**
947		* @throws NullPointerException {@inheritDoc}
948		*/
880	–	@Override
949		public boolean retainAll(Collection<?> c) {
950		Objects.requireNonNull(c);
951		return bulkRemove(e -> !c.contains(e));
#	Line 886 | Line 954 | public class ArrayDeque<E> extends Abstr
954		/** Implementation of bulk remove methods. */
955		private boolean bulkRemove(Predicate<? super E> filter) {
956		// checkInvariants();
957	<	final Object[] elements = this.elements;
958	<	final int capacity = elements.length;
959	<	int i = head, j = i, remaining = size, deleted = 0;
960	<	try {
961	<	for (; remaining > 0; remaining--, i = inc(i, capacity)) {
962	<	@SuppressWarnings("unchecked") E e = (E) elements[i];
963	<	if (filter.test(e))
964	<	deleted++;
965	<	else {
966	<	if (j != i)
967	<	elements[j] = e;
968	<	j = inc(j, capacity);
969	<	}
957	>	final Object[] es = elements;
958	>	// Optimize for initial run of survivors
959	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
960	>	; i = 0, to = end) {
961	>	for (; i < to; i++)
962	>	if (filter.test(elementAt(es, i)))
963	>	return bulkRemoveModified(filter, i);
964	>	if (to == end) {
965	>	if (end != tail) throw new ConcurrentModificationException();
966	>	break;
967	>	}
968	>	}
969	>	return false;
970	>	}
971	>
972	>	// A tiny bit set implementation
973	>
974	>	private static long[] nBits(int n) {
975	>	return new long[((n - 1) >> 6) + 1];
976	>	}
977	>	private static void setBit(long[] bits, int i) {
978	>	bits[i >> 6] |= 1L << i;
979	>	}
980	>	private static boolean isClear(long[] bits, int i) {
981	>	return (bits[i >> 6] & (1L << i)) == 0;
982	>	}
983	>
984	>	/**
985	>	* Helper for bulkRemove, in case of at least one deletion.
986	>	* Tolerate predicates that reentrantly access the collection for
987	>	* read (but writers still get CME), so traverse once to find
988	>	* elements to delete, a second pass to physically expunge.
989	>	*
990	>	* @param beg valid index of first element to be deleted
991	>	*/
992	>	private boolean bulkRemoveModified(
993	>	Predicate<? super E> filter, final int beg) {
994	>	final Object[] es = elements;
995	>	final int capacity = es.length;
996	>	final int end = tail;
997	>	final long[] deathRow = nBits(sub(end, beg, capacity));
998	>	deathRow[0] = 1L;   // set bit 0
999	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1000	>	; i = 0, to = end, k -= capacity) {
1001	>	for (; i < to; i++)
1002	>	if (filter.test(elementAt(es, i)))
1003	>	setBit(deathRow, i - k);
1004	>	if (to == end) break;
1005	>	}
1006	>	// a two-finger traversal, with hare i reading, tortoise w writing
1007	>	int w = beg;
1008	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1009	>	; w = 0) { // w rejoins i on second leg
1010	>	// In this loop, i and w are on the same leg, with i > w
1011	>	for (; i < to; i++)
1012	>	if (isClear(deathRow, i - k))
1013	>	es[w++] = es[i];
1014	>	if (to == end) break;
1015	>	// In this loop, w is on the first leg, i on the second
1016	>	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1017	>	if (isClear(deathRow, i - k))
1018	>	es[w++] = es[i];
1019	>	if (i >= to) {
1020	>	if (w == capacity) w = 0; // "corner" case
1021	>	break;
1022		}
903	–	return deleted > 0;
904	–	} catch (Throwable ex) {
905	–	for (; remaining > 0;
906	–	remaining--, i = inc(i, capacity), j = inc(j, capacity))
907	–	elements[j] = elements[i];
908	–	throw ex;
909	–	} finally {
910	–	size -= deleted;
911	–	for (; --deleted >= 0; j = inc(j, capacity))
912	–	elements[j] = null;
913	–	// checkInvariants();
1023		}
1024	+	if (end != tail) throw new ConcurrentModificationException();
1025	+	circularClear(es, tail = w, end);
1026	+	// checkInvariants();
1027	+	return true;
1028		}
1029
1030		/**
#	Line 924 | Line 1037 | public class ArrayDeque<E> extends Abstr
1037		*/
1038		public boolean contains(Object o) {
1039		if (o != null) {
1040	<	final Object[] elements = this.elements;
1041	<	final int capacity = elements.length;
1042	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1043	<	if (o.equals(elements[i]))
1044	<	return true;
1040	>	final Object[] es = elements;
1041	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1042	>	; i = 0, to = end) {
1043	>	for (; i < to; i++)
1044	>	if (o.equals(es[i]))
1045	>	return true;
1046	>	if (to == end) break;
1047	>	}
1048		}
1049		return false;
1050		}
#	Line 955 | Line 1071 | public class ArrayDeque<E> extends Abstr
1071		* The deque will be empty after this call returns.
1072		*/
1073		public void clear() {
1074	<	final Object[] elements = this.elements;
1075	<	final int capacity = elements.length;
960	<	final int h = this.head;
961	<	final int s = size;
962	<	if (capacity - h >= s)
963	<	Arrays.fill(elements, h, h + s, null);
964	<	else {
965	<	Arrays.fill(elements, h, capacity, null);
966	<	Arrays.fill(elements, 0, s - capacity + h, null);
967	<	}
968	<	size = head = 0;
1074	>	circularClear(elements, head, tail);
1075	>	head = tail = 0;
1076		// checkInvariants();
1077		}
1078
1079		/**
1080	+	* Nulls out slots starting at array index i, upto index end.
1081	+	* Condition i == end means "empty" - nothing to do.
1082	+	*/
1083	+	private static void circularClear(Object[] es, int i, int end) {
1084	+	// assert 0 <= i && i < es.length;
1085	+	// assert 0 <= end && end < es.length;
1086	+	for (int to = (i <= end) ? end : es.length;
1087	+	; i = 0, to = end) {
1088	+	for (; i < to; i++) es[i] = null;
1089	+	if (to == end) break;
1090	+	}
1091	+	}
1092	+
1093	+	/**
1094		* Returns an array containing all of the elements in this deque
1095		* in proper sequence (from first to last element).
1096		*
#	Line 983 | Line 1104 | public class ArrayDeque<E> extends Abstr
1104		* @return an array containing all of the elements in this deque
1105		*/
1106		public Object[] toArray() {
1107	<	final int head = this.head;
1108	<	final int firstLeg;
1109	<	Object[] a = Arrays.copyOfRange(elements, head, head + size);
1110	<	if ((firstLeg = elements.length - head) < size)
1111	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1107	>	return toArray(Object[].class);
1108	>	}
1109	>
1110	>	private <T> T[] toArray(Class<T[]> klazz) {
1111	>	final Object[] es = elements;
1112	>	final T[] a;
1113	>	final int head = this.head, tail = this.tail, end;
1114	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1115	>	// Uses null extension feature of copyOfRange
1116	>	a = Arrays.copyOfRange(es, head, end, klazz);
1117	>	} else {
1118	>	// integer overflow!
1119	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1120	>	System.arraycopy(es, head, a, 0, es.length - head);
1121	>	}
1122	>	if (end != tail)
1123	>	System.arraycopy(es, 0, a, es.length - head, tail);
1124		return a;
1125		}
1126
#	Line 1029 | Line 1162 | public class ArrayDeque<E> extends Abstr
1162		*/
1163		@SuppressWarnings("unchecked")
1164		public <T> T[] toArray(T[] a) {
1165	<	final Object[] elements = this.elements;
1166	<	final int head = this.head;
1167	<	final int firstLeg;
1168	<	boolean wrap = (firstLeg = elements.length - head) < size;
1169	<	if (size > a.length) {
1170	<	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
1171	<	a.getClass());
1172	<	} else {
1040	<	System.arraycopy(elements, head, a, 0, wrap ? firstLeg : size);
1041	<	if (size < a.length)
1042	<	a[size] = null;
1165	>	final int size;
1166	>	if ((size = size()) > a.length)
1167	>	return toArray((Class<T[]>) a.getClass());
1168	>	final Object[] es = elements;
1169	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1170	>	; i = 0, len = tail) {
1171	>	System.arraycopy(es, i, a, j, len);
1172	>	if ((j += len) == size) break;
1173		}
1174	<	if (wrap)
1175	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1174	>	if (size < a.length)
1175	>	a[size] = null;
1176		return a;
1177		}
1178
#	Line 1080 | Line 1210 | public class ArrayDeque<E> extends Abstr
1210		s.defaultWriteObject();
1211
1212		// Write out size
1213	<	s.writeInt(size);
1213	>	s.writeInt(size());
1214
1215		// Write out elements in order.
1216	<	final Object[] elements = this.elements;
1217	<	final int capacity = elements.length;
1218	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1219	<	s.writeObject(elements[i]);
1216	>	final Object[] es = elements;
1217	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1218	>	; i = 0, to = end) {
1219	>	for (; i < to; i++)
1220	>	s.writeObject(es[i]);
1221	>	if (to == end) break;
1222	>	}
1223		}
1224
1225		/**
#	Line 1101 | Line 1234 | public class ArrayDeque<E> extends Abstr
1234		s.defaultReadObject();
1235
1236		// Read in size and allocate array
1237	<	elements = new Object[size = s.readInt()];
1237	>	int size = s.readInt();
1238	>	elements = new Object[size + 1];
1239	>	this.tail = size;
1240
1241		// Read in all elements in the proper order.
1242		for (int i = 0; i < size; i++)
#	Line 1109 | Line 1244 | public class ArrayDeque<E> extends Abstr
1244		}
1245
1246		/** debugging */
1247	<	private void checkInvariants() {
1247	>	void checkInvariants() {
1248	>	// Use head and tail fields with empty slot at tail strategy.
1249	>	// head == tail disambiguates to "empty".
1250		try {
1251		int capacity = elements.length;
1252	<	assert size >= 0 && size <= capacity;
1253	<	assert head >= 0 && ((capacity == 0 && head == 0 && size == 0)
1254	<	|| head < capacity);
1255	<	assert size == 0
1256	<	|| (elements[head] != null && elements[tail()] != null);
1257	<	assert size == capacity
1258	<	|| (elements[dec(head, capacity)] == null
1122	<	&& elements[inc(tail(), capacity)] == null);
1252	>	// assert 0 <= head && head < capacity;
1253	>	// assert 0 <= tail && tail < capacity;
1254	>	// assert capacity > 0;
1255	>	// assert size() < capacity;
1256	>	// assert head == tail || elements[head] != null;
1257	>	// assert elements[tail] == null;
1258	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1259		} catch (Throwable t) {
1260	<	System.err.printf("head=%d size=%d capacity=%d%n",
1261	<	head, size, elements.length);
1260	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1261	>	head, tail, elements.length);
1262		System.err.printf("elements=%s%n",
1263		Arrays.toString(elements));
1264		throw t;

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