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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 1.123 by jsr166, Sat Nov 26 14:16:18 2016 UTC

#	Line 60 | Line 60 | import java.util.function.UnaryOperator;
60		public class ArrayDeque<E> extends AbstractCollection<E>
61		implements Deque<E>, Cloneable, Serializable
62		{
63	+	/*
64	+	* VMs excel at optimizing simple array loops where indices are
65	+	* incrementing or decrementing over a valid slice, e.g.
66	+	*
67	+	* for (int i = start; i < end; i++) ... elements[i]
68	+	*
69	+	* Because in a circular array, elements are in general stored in
70	+	* two disjoint such slices, we help the VM by writing unusual
71	+	* nested loops for all traversals over the elements.  Having only
72	+	* one hot inner loop body instead of two or three eases human
73	+	* maintenance and encourages VM loop inlining into the caller.
74	+	*/
75	+
76		/**
77		* The array in which the elements of the deque are stored.
78	<	* We guarantee that all array cells not holding deque elements
79	<	* are always null.
78	>	* All array cells not holding deque elements are always null.
79	>	* The array always has at least one null slot (at tail).
80		*/
81		transient Object[] elements;
82
83		/**
84		* The index of the element at the head of the deque (which is the
85		* element that would be removed by remove() or pop()); or an
86	<	* arbitrary number 0 <= head < elements.length if the deque is empty.
86	>	* arbitrary number 0 <= head < elements.length equal to tail if
87	>	* the deque is empty.
88		*/
89		transient int head;
90
91	<	/** Number of elements in this collection. */
92	<	transient int size;
91	>	/**
92	>	* The index at which the next element would be added to the tail
93	>	* of the deque (via addLast(E), add(E), or push(E));
94	>	* elements[tail] is always null.
95	>	*/
96	>	transient int tail;
97
98		/**
99		* The maximum size of array to allocate.
#	Line 92 | Line 110 | public class ArrayDeque<E> extends Abstr
110		*/
111		private void grow(int needed) {
112		// overflow-conscious code
113	<	// checkInvariants();
96	<	int oldCapacity = elements.length;
113	>	final int oldCapacity = elements.length;
114		int newCapacity;
115	<	// Double size if small; else grow by 50%
115	>	// Double capacity if small; else grow by 50%
116		int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
117		if (jump < needed
118		|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
119		newCapacity = newCapacity(needed, jump);
120		elements = Arrays.copyOf(elements, newCapacity);
121	<	if (oldCapacity - head < size) {
121	>	// Exceptionally, here tail == head needs to be disambiguated
122	>	if (tail < head || (tail == head && elements[head] != null)) {
123		// wrap around; slide first leg forward to end of array
124		int newSpace = newCapacity - oldCapacity;
125		System.arraycopy(elements, head,
#	Line 115 | Line 133 | public class ArrayDeque<E> extends Abstr
133
134		/** Capacity calculation for edge conditions, especially overflow. */
135		private int newCapacity(int needed, int jump) {
136	<	int oldCapacity = elements.length;
119	<	int minCapacity;
136	>	final int oldCapacity = elements.length, minCapacity;
137		if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
138		if (minCapacity < 0)
139		throw new IllegalStateException("Sorry, deque too big");
#	Line 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) distance -= 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		/**
#	Line 301 | Line 321 | public class ArrayDeque<E> extends Abstr
321		* @throws NullPointerException if the specified collection or any
322		*         of its elements are null
323		*/
304	–	@Override
324		public boolean addAll(Collection<? extends E> c) {
325	+	final int s, needed;
326	+	if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0)
327	+	grow(needed);
328	+	c.forEach(this::addLast);
329		// checkInvariants();
330	<	Object[] a, elements;
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;
330	>	return size() > s;
331		}
332
333		/**
#	Line 348 | Line 358 | public class ArrayDeque<E> extends Abstr
358		* @throws NoSuchElementException {@inheritDoc}
359		*/
360		public E removeFirst() {
361	<	// checkInvariants();
362	<	E x = pollFirst();
353	<	if (x == null)
361	>	E e = pollFirst();
362	>	if (e == null)
363		throw new NoSuchElementException();
364	<	return x;
364	>	// checkInvariants();
365	>	return e;
366		}
367
368		/**
369		* @throws NoSuchElementException {@inheritDoc}
370		*/
371		public E removeLast() {
372	<	// checkInvariants();
373	<	E x = pollLast();
364	<	if (x == null)
372	>	E e = pollLast();
373	>	if (e == null)
374		throw new NoSuchElementException();
375	<	return x;
375	>	// checkInvariants();
376	>	return e;
377		}
378
379		public E pollFirst() {
380	+	final Object[] es;
381	+	final int h;
382	+	E e = elementAt(es = elements, h = head);
383	+	if (e != null) {
384	+	es[h] = null;
385	+	head = inc(h, es.length);
386	+	}
387		// checkInvariants();
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;
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[] 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;
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		*/
415		public E getLast() {
416	+	final Object[] es = elements;
417	+	E e = elementAt(es, dec(tail, es.length));
418	+	if (e == null)
419	+	throw new NoSuchElementException();
420		// checkInvariants();
421	<	if (size == 0) throw new NoSuchElementException();
410	<	return elementAt(tail());
421	>	return e;
422		}
423
424		public E peekFirst() {
425		// checkInvariants();
426	<	return (size == 0) ? null : elementAt(head);
426	>	return elementAt(elements, head);
427		}
428
429		public E peekLast() {
430		// checkInvariants();
431	<	return (size == 0) ? null : elementAt(tail());
431	>	final Object[] es;
432	>	return elementAt(es = elements, dec(tail, es.length));
433		}
434
435		/**
#	Line 433 | Line 445 | public class ArrayDeque<E> extends Abstr
445		* @return {@code true} if the deque contained the specified element
446		*/
447		public boolean removeFirstOccurrence(Object o) {
436	–	// checkInvariants();
448		if (o != null) {
449	<	final Object[] elements = this.elements;
450	<	final int capacity = elements.length;
451	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) {
452	<	if (o.equals(elements[i])) {
453	<	delete(i);
454	<	return true;
455	<	}
449	>	final Object[] es = elements;
450	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
451	>	; i = 0, to = end) {
452	>	for (; i < to; i++)
453	>	if (o.equals(es[i])) {
454	>	delete(i);
455	>	return true;
456	>	}
457	>	if (to == end) break;
458		}
459		}
460		return false;
#	Line 461 | Line 474 | public class ArrayDeque<E> extends Abstr
474		*/
475		public boolean removeLastOccurrence(Object o) {
476		if (o != null) {
477	<	final Object[] elements = this.elements;
478	<	final int capacity = elements.length;
479	<	for (int k = size, i = add(head, k - 1, capacity);
480	<	--k >= 0; i = dec(i, capacity)) {
481	<	if (o.equals(elements[i])) {
482	<	delete(i);
483	<	return true;
484	<	}
477	>	final Object[] es = elements;
478	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
479	>	; i = es.length, to = end) {
480	>	for (i--; i > to - 1; i--)
481	>	if (o.equals(es[i])) {
482	>	delete(i);
483	>	return true;
484	>	}
485	>	if (to == end) break;
486		}
487		}
488		return false;
#	Line 596 | Line 610 | public class ArrayDeque<E> extends Abstr
610		* <p>This method is called delete rather than remove to emphasize
611		* that its semantics differ from those of {@link List#remove(int)}.
612		*
613	<	* @return true if elements moved backwards
613	>	* @return true if elements near tail moved backwards
614		*/
615		boolean delete(int i) {
616		// checkInvariants();
617	<	final Object[] elements = this.elements;
618	<	final int capacity = elements.length;
619	<	final int h = head;
620	<	int front;              // number of elements before to-be-deleted elt
621	<	if ((front = i - h) < 0) front += capacity;
622	<	final int back = size - front - 1; // number of elements after
617	>	final Object[] es = elements;
618	>	final int capacity = es.length;
619	>	final int h, t;
620	>	// number of elements before to-be-deleted elt
621	>	final int front = sub(i, h = head, capacity);
622	>	// number of elements after to-be-deleted elt
623	>	final int back = sub(t = tail, i, capacity) - 1;
624		if (front < back) {
625		// move front elements forwards
626		if (h <= i) {
627	<	System.arraycopy(elements, h, elements, h + 1, front);
627	>	System.arraycopy(es, h, es, h + 1, front);
628		} else { // Wrap around
629	<	System.arraycopy(elements, 0, elements, 1, i);
630	<	elements[0] = elements[capacity - 1];
631	<	System.arraycopy(elements, h, elements, h + 1, front - (i + 1));
629	>	System.arraycopy(es, 0, es, 1, i);
630	>	es[0] = es[capacity - 1];
631	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
632		}
633	<	elements[h] = null;
633	>	es[h] = null;
634		head = inc(h, capacity);
620	–	size--;
635		// checkInvariants();
636		return false;
637		} else {
638		// move back elements backwards
639	<	int tail = tail();
639	>	tail = dec(t, capacity);
640		if (i <= tail) {
641	<	System.arraycopy(elements, i + 1, elements, i, back);
641	>	System.arraycopy(es, i + 1, es, i, back);
642		} else { // Wrap around
643	<	int firstLeg = capacity - (i + 1);
644	<	System.arraycopy(elements, i + 1, elements, i, firstLeg);
645	<	elements[capacity - 1] = elements[0];
632	<	System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1);
643	>	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
644	>	es[capacity - 1] = es[0];
645	>	System.arraycopy(es, 1, es, 0, t - 1);
646		}
647	<	elements[tail] = null;
635	<	size--;
647	>	es[tail] = null;
648		// checkInvariants();
649		return true;
650		}
#	Line 646 | 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 655 | 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 679 | 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 689 | Line 701 | public class ArrayDeque<E> extends Abstr
701
702		DeqIterator() { cursor = head; }
703
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	–
704		public final boolean hasNext() {
705		return remaining > 0;
706		}
707
708	<	public final E next() {
709	<	if (remaining == 0)
708	>	public E next() {
709	>	if (remaining <= 0)
710		throw new NoSuchElementException();
711	<	E e = checkedElementAt(elements, cursor);
712	<	lastRet = cursor;
713	<	cursor = advance(cursor, elements.length);
711	>	final Object[] es = elements;
712	>	E e = nonNullElementAt(es, cursor);
713	>	cursor = inc(lastRet = cursor, es.length);
714		remaining--;
715		return e;
716		}
717
718	+	void postDelete(boolean leftShifted) {
719	+	if (leftShifted)
720	+	cursor = dec(cursor, elements.length);
721	+	}
722	+
723		public final void remove() {
724		if (lastRet < 0)
725		throw new IllegalStateException();
726	<	doRemove();
726	>	postDelete(delete(lastRet));
727		lastRet = -1;
728		}
729
730	<	public final void forEachRemaining(Consumer<? super E> action) {
730	>	public void forEachRemaining(Consumer<? super E> action) {
731		Objects.requireNonNull(action);
732	<	final Object[] elements = ArrayDeque.this.elements;
733	<	final int capacity = elements.length;
734	<	int k = remaining;
732	>	int r;
733	>	if ((r = remaining) <= 0)
734	>	return;
735		remaining = 0;
736	<	for (int i = cursor; --k >= 0; i = advance(i, capacity))
737	<	action.accept(checkedElementAt(elements, i));
736	>	final Object[] es = elements;
737	>	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
738	>	throw new ConcurrentModificationException();
739	>	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
740	>	; i = 0, to = end) {
741	>	for (; i < to; i++)
742	>	action.accept(elementAt(es, i));
743	>	if (to == end) {
744	>	if (end != tail)
745	>	throw new ConcurrentModificationException();
746	>	lastRet = dec(end, es.length);
747	>	break;
748	>	}
749	>	}
750		}
751		}
752
753		private class DescendingIterator extends DeqIterator {
754	<	DescendingIterator() { cursor = tail(); }
754	>	DescendingIterator() { cursor = dec(tail, elements.length); }
755
756	<	@Override int advance(int i, int modulus) {
757	<	return dec(i, modulus);
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	>	cursor = dec(lastRet = cursor, es.length);
762	>	remaining--;
763	>	return e;
764		}
765
766	<	@Override void doRemove() {
767	<	if (!delete(lastRet))
743	<	// if right-shifted, undo advance in next
766	>	void postDelete(boolean leftShifted) {
767	>	if (!leftShifted)
768		cursor = inc(cursor, elements.length);
769		}
770	+
771	+	public final void forEachRemaining(Consumer<? super E> action) {
772	+	Objects.requireNonNull(action);
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	+	}
791	+	}
792	+	}
793		}
794
795		/**
#	Line 759 | 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;
817	>	DeqSpliterator() {
818	>	this.fence = -1;
819		}
820
821	<	/** Constructs spliterator over the given slice. */
822	<	ArrayDequeSpliterator(int cursor, int count) {
823	<	this.cursor = cursor;
824	<	this.remaining = count;
821	>	/** Constructs spliterator over the given range. */
822	>	DeqSpliterator(int origin, int fence) {
823	>	this.cursor = origin;
824	>	this.fence = fence;
825		}
826
827	<	/** Ensures late-binding initialization; then returns remaining. */
828	<	private int remaining() {
829	<	if (remaining < 0) {
827	>	/** Ensures late-binding initialization; then returns fence. */
828	>	private int getFence() { // force initialization
829	>	int t;
830	>	if ((t = fence) < 0) {
831	>	t = fence = tail;
832		cursor = head;
784	–	remaining = size;
833		}
834	<	return remaining;
834	>	return t;
835		}
836
837	<	public ArrayDequeSpliterator trySplit() {
838	<	final int mid;
839	<	if ((mid = remaining() >> 1) > 0) {
840	<	int oldCursor = cursor;
841	<	cursor = add(cursor, mid, elements.length);
842	<	remaining -= mid;
795	<	return new ArrayDequeSpliterator(oldCursor, mid);
796	<	}
797	<	return null;
837	>	public DeqSpliterator trySplit() {
838	>	final Object[] es = elements;
839	>	final int i, n;
840	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
841	>	? null
842	>	: new DeqSpliterator(i, cursor = add(i, n, es.length));
843		}
844
845		public void forEachRemaining(Consumer<? super E> action) {
846	<	Objects.requireNonNull(action);
847	<	final Object[] elements = ArrayDeque.this.elements;
848	<	final int capacity = elements.length;
849	<	int k = remaining();
850	<	remaining = 0;
851	<	for (int i = cursor; --k >= 0; i = inc(i, capacity))
852	<	action.accept(checkedElementAt(elements, i));
846	>	if (action == null)
847	>	throw new NullPointerException();
848	>	final int end = getFence(), cursor = this.cursor;
849	>	final Object[] es = elements;
850	>	if (cursor != end) {
851	>	this.cursor = end;
852	>	// null check at both ends of range is sufficient
853	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
854	>	throw new ConcurrentModificationException();
855	>	for (int i = cursor, to = (i <= end) ? end : es.length;
856	>	; i = 0, to = end) {
857	>	for (; i < to; i++)
858	>	action.accept(elementAt(es, i));
859	>	if (to == end) break;
860	>	}
861	>	}
862		}
863
864		public boolean tryAdvance(Consumer<? super E> action) {
865		Objects.requireNonNull(action);
866	<	if (remaining() == 0)
866	>	final Object[] es = elements;
867	>	if (fence < 0) { fence = tail; cursor = head; } // late-binding
868	>	final int i;
869	>	if ((i = cursor) == fence)
870		return false;
871	<	action.accept(checkedElementAt(elements, cursor));
872	<	cursor = inc(cursor, elements.length);
873	<	remaining--;
871	>	E e = nonNullElementAt(es, i);
872	>	cursor = inc(i, es.length);
873	>	action.accept(e);
874		return true;
875		}
876
877		public long estimateSize() {
878	<	return remaining();
878	>	return sub(getFence(), cursor, elements.length);
879		}
880
881		public int characteristics() {
#	Line 829 | Line 886 | public class ArrayDeque<E> extends Abstr
886		}
887		}
888
832	–	@Override
889		public void forEach(Consumer<? super E> action) {
834	–	// checkInvariants();
890		Objects.requireNonNull(action);
891	<	final Object[] elements = this.elements;
892	<	final int capacity = elements.length;
893	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
894	<	action.accept(elementAt(i));
891	>	final Object[] es = elements;
892	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
893	>	; i = 0, to = end) {
894	>	for (; i < to; i++)
895	>	action.accept(elementAt(es, i));
896	>	if (to == end) {
897	>	if (end != tail) throw new ConcurrentModificationException();
898	>	break;
899	>	}
900	>	}
901		// checkInvariants();
902		}
903
#	Line 845 | Line 906 | public class ArrayDeque<E> extends Abstr
906		* operator to that element, as specified by {@link List#replaceAll}.
907		*
908		* @param operator the operator to apply to each element
909	<	* @since 9
909	>	* @since TBD
910		*/
911	<	public void replaceAll(UnaryOperator<E> operator) {
911	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
912		Objects.requireNonNull(operator);
913	<	final Object[] elements = this.elements;
914	<	final int capacity = elements.length;
915	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
916	<	elements[i] = operator.apply(elementAt(i));
913	>	final Object[] es = elements;
914	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
915	>	; i = 0, to = end) {
916	>	for (; i < to; i++)
917	>	es[i] = operator.apply(elementAt(es, i));
918	>	if (to == end) {
919	>	if (end != tail) throw new ConcurrentModificationException();
920	>	break;
921	>	}
922	>	}
923		// checkInvariants();
924		}
925
926		/**
927		* @throws NullPointerException {@inheritDoc}
928		*/
862	–	@Override
929		public boolean removeIf(Predicate<? super E> filter) {
930		Objects.requireNonNull(filter);
931		return bulkRemove(filter);
#	Line 868 | Line 934 | public class ArrayDeque<E> extends Abstr
934		/**
935		* @throws NullPointerException {@inheritDoc}
936		*/
871	–	@Override
937		public boolean removeAll(Collection<?> c) {
938		Objects.requireNonNull(c);
939		return bulkRemove(e -> c.contains(e));
#	Line 877 | Line 942 | public class ArrayDeque<E> extends Abstr
942		/**
943		* @throws NullPointerException {@inheritDoc}
944		*/
880	–	@Override
945		public boolean retainAll(Collection<?> c) {
946		Objects.requireNonNull(c);
947		return bulkRemove(e -> !c.contains(e));
#	Line 886 | Line 950 | public class ArrayDeque<E> extends Abstr
950		/** Implementation of bulk remove methods. */
951		private boolean bulkRemove(Predicate<? super E> filter) {
952		// checkInvariants();
953	<	final Object[] elements = this.elements;
954	<	final int capacity = elements.length;
955	<	int i = head, j = i, remaining = size, deleted = 0;
956	<	try {
957	<	for (; remaining > 0; remaining--, i = inc(i, capacity)) {
958	<	@SuppressWarnings("unchecked") E e = (E) elements[i];
959	<	if (filter.test(e))
960	<	deleted++;
961	<	else {
962	<	if (j != i)
963	<	elements[j] = e;
964	<	j = inc(j, capacity);
965	<	}
953	>	final Object[] es = elements;
954	>	// Optimize for initial run of survivors
955	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
956	>	; i = 0, to = end) {
957	>	for (; i < to; i++)
958	>	if (filter.test(elementAt(es, i)))
959	>	return bulkRemoveModified(filter, i);
960	>	if (to == end) {
961	>	if (end != tail) throw new ConcurrentModificationException();
962	>	break;
963	>	}
964	>	}
965	>	return false;
966	>	}
967	>
968	>	// A tiny bit set implementation
969	>
970	>	private static long[] nBits(int n) {
971	>	return new long[((n - 1) >> 6) + 1];
972	>	}
973	>	private static void setBit(long[] bits, int i) {
974	>	bits[i >> 6] |= 1L << i;
975	>	}
976	>	private static boolean isClear(long[] bits, int i) {
977	>	return (bits[i >> 6] & (1L << i)) == 0;
978	>	}
979	>
980	>	/**
981	>	* Helper for bulkRemove, in case of at least one deletion.
982	>	* Tolerate predicates that reentrantly access the collection for
983	>	* read (but writers still get CME), so traverse once to find
984	>	* elements to delete, a second pass to physically expunge.
985	>	*
986	>	* @param beg valid index of first element to be deleted
987	>	*/
988	>	private boolean bulkRemoveModified(
989	>	Predicate<? super E> filter, final int beg) {
990	>	final Object[] es = elements;
991	>	final int capacity = es.length;
992	>	final int end = tail;
993	>	final long[] deathRow = nBits(sub(end, beg, capacity));
994	>	deathRow[0] = 1L;   // set bit 0
995	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
996	>	; i = 0, to = end, k -= capacity) {
997	>	for (; i < to; i++)
998	>	if (filter.test(elementAt(es, i)))
999	>	setBit(deathRow, i - k);
1000	>	if (to == end) break;
1001	>	}
1002	>	// a two-finger traversal, with hare i reading, tortoise w writing
1003	>	int w = beg;
1004	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1005	>	; w = 0) { // w rejoins i on second leg
1006	>	// In this loop, i and w are on the same leg, with i > w
1007	>	for (; i < to; i++)
1008	>	if (isClear(deathRow, i - k))
1009	>	es[w++] = es[i];
1010	>	if (to == end) break;
1011	>	// In this loop, w is on the first leg, i on the second
1012	>	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1013	>	if (isClear(deathRow, i - k))
1014	>	es[w++] = es[i];
1015	>	if (i >= to) {
1016	>	if (w == capacity) w = 0; // "corner" case
1017	>	break;
1018		}
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();
1019		}
1020	+	if (end != tail) throw new ConcurrentModificationException();
1021	+	circularClear(es, tail = w, end);
1022	+	// checkInvariants();
1023	+	return true;
1024		}
1025
1026		/**
#	Line 924 | Line 1033 | public class ArrayDeque<E> extends Abstr
1033		*/
1034		public boolean contains(Object o) {
1035		if (o != null) {
1036	<	final Object[] elements = this.elements;
1037	<	final int capacity = elements.length;
1038	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1039	<	if (o.equals(elements[i]))
1040	<	return true;
1036	>	final Object[] es = elements;
1037	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1038	>	; i = 0, to = end) {
1039	>	for (; i < to; i++)
1040	>	if (o.equals(es[i]))
1041	>	return true;
1042	>	if (to == end) break;
1043	>	}
1044		}
1045		return false;
1046		}
#	Line 955 | Line 1067 | public class ArrayDeque<E> extends Abstr
1067		* The deque will be empty after this call returns.
1068		*/
1069		public void clear() {
1070	<	final Object[] elements = this.elements;
1071	<	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;
1070	>	circularClear(elements, head, tail);
1071	>	head = tail = 0;
1072		// checkInvariants();
1073		}
1074
1075		/**
1076	+	* Nulls out slots starting at array index i, upto index end.
1077	+	*/
1078	+	private static void circularClear(Object[] es, int i, int end) {
1079	+	for (int to = (i <= end) ? end : es.length;
1080	+	; i = 0, to = end) {
1081	+	Arrays.fill(es, i, to, null);
1082	+	if (to == end) break;
1083	+	}
1084	+	}
1085	+
1086	+	/**
1087		* Returns an array containing all of the elements in this deque
1088		* in proper sequence (from first to last element).
1089		*
#	Line 983 | Line 1097 | public class ArrayDeque<E> extends Abstr
1097		* @return an array containing all of the elements in this deque
1098		*/
1099		public Object[] toArray() {
1100	<	final int head = this.head;
1101	<	final int firstLeg;
1102	<	Object[] a = Arrays.copyOfRange(elements, head, head + size);
1103	<	if ((firstLeg = elements.length - head) < size)
1104	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1100	>	return toArray(Object[].class);
1101	>	}
1102	>
1103	>	private <T> T[] toArray(Class<T[]> klazz) {
1104	>	final Object[] es = elements;
1105	>	final T[] a;
1106	>	final int head = this.head, tail = this.tail, end;
1107	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1108	>	// Uses null extension feature of copyOfRange
1109	>	a = Arrays.copyOfRange(es, head, end, klazz);
1110	>	} else {
1111	>	// integer overflow!
1112	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1113	>	System.arraycopy(es, head, a, 0, es.length - head);
1114	>	}
1115	>	if (end != tail)
1116	>	System.arraycopy(es, 0, a, es.length - head, tail);
1117		return a;
1118		}
1119
#	Line 1029 | Line 1155 | public class ArrayDeque<E> extends Abstr
1155		*/
1156		@SuppressWarnings("unchecked")
1157		public <T> T[] toArray(T[] a) {
1158	<	final Object[] elements = this.elements;
1159	<	final int head = this.head;
1160	<	final int firstLeg;
1161	<	boolean wrap = (firstLeg = elements.length - head) < size;
1162	<	if (size > a.length) {
1163	<	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
1164	<	a.getClass());
1165	<	} else {
1040	<	System.arraycopy(elements, head, a, 0, wrap ? firstLeg : size);
1041	<	if (size < a.length)
1042	<	a[size] = null;
1158	>	final int size;
1159	>	if ((size = size()) > a.length)
1160	>	return toArray((Class<T[]>) a.getClass());
1161	>	final Object[] es = elements;
1162	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1163	>	; i = 0, len = tail) {
1164	>	System.arraycopy(es, i, a, j, len);
1165	>	if ((j += len) == size) break;
1166		}
1167	<	if (wrap)
1168	<	System.arraycopy(elements, 0, a, firstLeg, size - firstLeg);
1167	>	if (size < a.length)
1168	>	a[size] = null;
1169		return a;
1170		}
1171
#	Line 1080 | Line 1203 | public class ArrayDeque<E> extends Abstr
1203		s.defaultWriteObject();
1204
1205		// Write out size
1206	<	s.writeInt(size);
1206	>	s.writeInt(size());
1207
1208		// Write out elements in order.
1209	<	final Object[] elements = this.elements;
1210	<	final int capacity = elements.length;
1211	<	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1212	<	s.writeObject(elements[i]);
1209	>	final Object[] es = elements;
1210	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1211	>	; i = 0, to = end) {
1212	>	for (; i < to; i++)
1213	>	s.writeObject(es[i]);
1214	>	if (to == end) break;
1215	>	}
1216		}
1217
1218		/**
#	Line 1101 | Line 1227 | public class ArrayDeque<E> extends Abstr
1227		s.defaultReadObject();
1228
1229		// Read in size and allocate array
1230	<	elements = new Object[size = s.readInt()];
1230	>	int size = s.readInt();
1231	>	elements = new Object[size + 1];
1232	>	this.tail = size;
1233
1234		// Read in all elements in the proper order.
1235		for (int i = 0; i < size; i++)
#	Line 1109 | Line 1237 | public class ArrayDeque<E> extends Abstr
1237		}
1238
1239		/** debugging */
1240	<	private void checkInvariants() {
1240	>	void checkInvariants() {
1241	>	// Use head and tail fields with empty slot at tail strategy.
1242	>	// head == tail disambiguates to "empty".
1243		try {
1244		int capacity = elements.length;
1245	<	assert size >= 0 && size <= capacity;
1246	<	assert head >= 0 && ((capacity == 0 && head == 0 && size == 0)
1247	<	|| head < capacity);
1248	<	assert size == 0
1249	<	|| (elements[head] != null && elements[tail()] != null);
1250	<	assert size == capacity
1251	<	|| (elements[dec(head, capacity)] == null
1122	<	&& elements[inc(tail(), capacity)] == null);
1245	>	// assert head >= 0 && head < capacity;
1246	>	// assert tail >= 0 && tail < capacity;
1247	>	// assert capacity > 0;
1248	>	// assert size() < capacity;
1249	>	// assert head == tail || elements[head] != null;
1250	>	// assert elements[tail] == null;
1251	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1252		} catch (Throwable t) {
1253	<	System.err.printf("head=%d size=%d capacity=%d%n",
1254	<	head, size, elements.length);
1253	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1254	>	head, tail, elements.length);
1255		System.err.printf("elements=%s%n",
1256		Arrays.toString(elements));
1257		throw t;

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