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Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.73 by jsr166, Sun Oct 11 00:50:06 2015 UTC vs.
Revision 1.108 by jsr166, Sat Nov 5 14:41:14 2016 UTC

#	Line 7 | Line 7 | package java.util;
7
8		import java.io.Serializable;
9		import java.util.function.Consumer;
10	+	import java.util.function.Predicate;
11	+	import java.util.function.UnaryOperator;
12
13		/**
14		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 52 | Line 54 | import java.util.function.Consumer;
54		* Java Collections Framework</a>.
55		*
56		* @author  Josh Bloch and Doug Lea
55	–	* @since   1.6
57		* @param <E> the type of elements held in this deque
58	+	* @since   1.6
59		*/
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.
72	+	*/
73	+
74		/**
75		* The array in which the elements of the deque are stored.
76	<	* The capacity of the deque is the length of this array, which is
77	<	* always a power of two. The array is never allowed to become
65	<	* full, except transiently within an addX method where it is
66	<	* resized (see doubleCapacity) immediately upon becoming full,
67	<	* thus avoiding head and tail wrapping around to equal each
68	<	* other.  We also guarantee that all array cells not holding
69	<	* deque elements are always null.
76	>	* We guarantee that all array cells not holding deque elements
77	>	* are always null.
78		*/
79	<	transient Object[] elements; // non-private to simplify nested class access
79	>	transient Object[] elements;
80
81		/**
82		* The index of the element at the head of the deque (which is the
83		* element that would be removed by remove() or pop()); or an
84	<	* arbitrary number equal to tail if the deque is empty.
84	>	* arbitrary number 0 <= head < elements.length equal to tail if
85	>	* the deque is empty.
86		*/
87		transient int head;
88
#	Line 84 | Line 93 | public class ArrayDeque<E> extends Abstr
93		transient int tail;
94
95		/**
96	<	* The minimum capacity that we'll use for a newly created deque.
97	<	* Must be a power of 2.
96	>	* The maximum size of array to allocate.
97	>	* Some VMs reserve some header words in an array.
98	>	* Attempts to allocate larger arrays may result in
99	>	* OutOfMemoryError: Requested array size exceeds VM limit
100		*/
101	<	private static final int MIN_INITIAL_CAPACITY = 8;
101	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
102
103	<	// ******  Array allocation and resizing utilities ******
103	>	/**
104	>	* Increases the capacity of this deque by at least the given amount.
105	>	*
106	>	* @param needed the required minimum extra capacity; must be positive
107	>	*/
108	>	private void grow(int needed) {
109	>	// overflow-conscious code
110	>	final int oldCapacity = elements.length;
111	>	int newCapacity;
112	>	// Double capacity if small; else grow by 50%
113	>	int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
114	>	if (jump < needed
115	>	|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
116	>	newCapacity = newCapacity(needed, jump);
117	>	elements = Arrays.copyOf(elements, newCapacity);
118	>	// Exceptionally, here tail == head needs to be disambiguated
119	>	if (tail < head || (tail == head && elements[head] != null)) {
120	>	// wrap around; slide first leg forward to end of array
121	>	int newSpace = newCapacity - oldCapacity;
122	>	System.arraycopy(elements, head,
123	>	elements, head + newSpace,
124	>	oldCapacity - head);
125	>	Arrays.fill(elements, head, head + newSpace, null);
126	>	head += newSpace;
127	>	}
128	>	// checkInvariants();
129	>	}
130	>
131	>	/** Capacity calculation for edge conditions, especially overflow. */
132	>	private int newCapacity(int needed, int jump) {
133	>	final int oldCapacity = elements.length, minCapacity;
134	>	if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
135	>	if (minCapacity < 0)
136	>	throw new IllegalStateException("Sorry, deque too big");
137	>	return Integer.MAX_VALUE;
138	>	}
139	>	if (needed > jump)
140	>	return minCapacity;
141	>	return (oldCapacity + jump - MAX_ARRAY_SIZE < 0)
142	>	? oldCapacity + jump
143	>	: MAX_ARRAY_SIZE;
144	>	}
145
146		/**
147	<	* Allocates empty array to hold the given number of elements.
148	<	*
149	<	* @param numElements  the number of elements to hold
150	<	*/
151	<	private void allocateElements(int numElements) {
152	<	int initialCapacity = MIN_INITIAL_CAPACITY;
153	<	// Find the best power of two to hold elements.
154	<	// Tests "<=" because arrays aren't kept full.
155	<	if (numElements >= initialCapacity) {
156	<	initialCapacity = numElements;
157	<	initialCapacity |= (initialCapacity >>>  1);
106	<	initialCapacity |= (initialCapacity >>>  2);
107	<	initialCapacity |= (initialCapacity >>>  4);
108	<	initialCapacity |= (initialCapacity >>>  8);
109	<	initialCapacity |= (initialCapacity >>> 16);
110	<	initialCapacity++;
111	<
112	<	if (initialCapacity < 0)    // Too many elements, must back off
113	<	initialCapacity >>>= 1; // Good luck allocating 2^30 elements
114	<	}
115	<	elements = new Object[initialCapacity];
147	>	* Increases the internal storage of this collection, if necessary,
148	>	* to ensure that it can hold at least the given number of elements.
149	>	*
150	>	* @param minCapacity the desired minimum capacity
151	>	* @since TBD
152	>	*/
153	>	/* public */ void ensureCapacity(int minCapacity) {
154	>	int needed;
155	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
156	>	grow(needed);
157	>	// checkInvariants();
158		}
159
160		/**
161	<	* Doubles the capacity of this deque.  Call only when full, i.e.,
162	<	* when head and tail have wrapped around to become equal.
163	<	*/
164	<	private void doubleCapacity() {
165	<	assert head == tail;
166	<	int p = head;
167	<	int n = elements.length;
168	<	int r = n - p; // number of elements to the right of p
169	<	int newCapacity = n << 1;
170	<	if (newCapacity < 0)
171	<	throw new IllegalStateException("Sorry, deque too big");
172	<	Object[] a = new Object[newCapacity];
131	<	System.arraycopy(elements, p, a, 0, r);
132	<	System.arraycopy(elements, 0, a, r, p);
133	<	elements = a;
134	<	head = 0;
135	<	tail = n;
161	>	* Minimizes the internal storage of this collection.
162	>	*
163	>	* @since TBD
164	>	*/
165	>	/* public */ void trimToSize() {
166	>	int size;
167	>	if ((size = size()) + 1 < elements.length) {
168	>	elements = toArray(new Object[size + 1]);
169	>	head = 0;
170	>	tail = size;
171	>	}
172	>	// checkInvariants();
173		}
174
175		/**
#	Line 147 | Line 184 | public class ArrayDeque<E> extends Abstr
184		* Constructs an empty array deque with an initial capacity
185		* sufficient to hold the specified number of elements.
186		*
187	<	* @param numElements  lower bound on initial capacity of the deque
187	>	* @param numElements lower bound on initial capacity of the deque
188		*/
189		public ArrayDeque(int numElements) {
190	<	allocateElements(numElements);
190	>	elements = new Object[Math.max(1, numElements + 1)];
191		}
192
193		/**
#	Line 164 | Line 201 | public class ArrayDeque<E> extends Abstr
201		* @throws NullPointerException if the specified collection is null
202		*/
203		public ArrayDeque(Collection<? extends E> c) {
204	<	allocateElements(c.size());
204	>	elements = new Object[c.size() + 1];
205		addAll(c);
206		}
207
208	+	/**
209	+	* Increments i, mod modulus.
210	+	* Precondition and postcondition: 0 <= i < modulus.
211	+	*/
212	+	static final int inc(int i, int modulus) {
213	+	if (++i >= modulus) i = 0;
214	+	return i;
215	+	}
216	+
217	+	/**
218	+	* Decrements i, mod modulus.
219	+	* Precondition and postcondition: 0 <= i < modulus.
220	+	*/
221	+	static final int dec(int i, int modulus) {
222	+	if (--i < 0) i = modulus - 1;
223	+	return i;
224	+	}
225	+
226	+	/**
227	+	* Adds i and j, mod modulus.
228	+	* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus.
229	+	*/
230	+	static final int add(int i, int j, int modulus) {
231	+	if ((i += j) - modulus >= 0) i -= modulus;
232	+	return i;
233	+	}
234	+
235	+	/**
236	+	* Subtracts j from i, mod modulus.
237	+	* Index i must be logically ahead of j.
238	+	* Returns the "circular distance" from j to i.
239	+	* Precondition and postcondition: 0 <= i < modulus, 0 <= j < modulus.
240	+	*/
241	+	static final int sub(int i, int j, int modulus) {
242	+	if ((i -= j) < 0) i += modulus;
243	+	return i;
244	+	}
245	+
246	+	/**
247	+	* Returns the array index of the last element.
248	+	* May return invalid index -1 if there are no elements.
249	+	*/
250	+	final int last() {
251	+	return dec(tail, elements.length);
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	+	static final <E> E elementAt(Object[] es, int i) {
260	+	return (E) es[i];
261	+	}
262	+
263	+	/**
264	+	* A version of elementAt that checks for null elements.
265	+	* This check doesn't catch all possible comodifications,
266	+	* but does catch ones that corrupt traversal.
267	+	*/
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;
273	+	}
274	+
275		// The main insertion and extraction methods are addFirst,
276		// addLast, pollFirst, pollLast. The other methods are defined in
277		// terms of these.
#	Line 181 | Line 285 | public class ArrayDeque<E> extends Abstr
285		public void addFirst(E e) {
286		if (e == null)
287		throw new NullPointerException();
288	<	elements[head = (head - 1) & (elements.length - 1)] = e;
288	>	final Object[] es = elements;
289	>	es[head = dec(head, es.length)] = e;
290		if (head == tail)
291	<	doubleCapacity();
291	>	grow(1);
292	>	// checkInvariants();
293		}
294
295		/**
#	Line 197 | Line 303 | public class ArrayDeque<E> extends Abstr
303		public void addLast(E e) {
304		if (e == null)
305		throw new NullPointerException();
306	<	elements[tail] = e;
307	<	if ( (tail = (tail + 1) & (elements.length - 1)) == head)
308	<	doubleCapacity();
306	>	final Object[] es = elements;
307	>	es[tail] = e;
308	>	if (head == (tail = inc(tail, es.length)))
309	>	grow(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
317	>	* 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
321	>	* @throws NullPointerException if the specified collection or any
322	>	*         of its elements are null
323	>	*/
324	>	public boolean addAll(Collection<? extends E> c) {
325	>	final int s = size(), needed;
326	>	if ((needed = s + c.size() - elements.length + 1) > 0)
327	>	grow(needed);
328	>	c.forEach((e) -> addLast(e));
329	>	// checkInvariants();
330	>	return size() > s;
331		}
332
333		/**
#	Line 230 | Line 358 | public class ArrayDeque<E> extends Abstr
358		* @throws NoSuchElementException {@inheritDoc}
359		*/
360		public E removeFirst() {
361	<	E x = pollFirst();
362	<	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	<	E x = pollLast();
373	<	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[] elements = this.elements;
381	<	final int h = head;
382	<	@SuppressWarnings("unchecked")
383	<	E result = (E) elements[h];
384	<	// Element is null if deque empty
385	<	if (result != null) {
256	<	elements[h] = null; // Must null out slot
257	<	head = (h + 1) & (elements.length - 1);
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	<	return result;
387	>	// checkInvariants();
388	>	return e;
389		}
390
391		public E pollLast() {
392	<	final Object[] elements = this.elements;
393	<	final int t = (tail - 1) & (elements.length - 1);
394	<	@SuppressWarnings("unchecked")
395	<	E result = (E) elements[t];
396	<	if (result != null) {
397	<	elements[t] = null;
398	<	tail = t;
270	<	}
271	<	return result;
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();
398	>	return e;
399		}
400
401		/**
402		* @throws NoSuchElementException {@inheritDoc}
403		*/
404		public E getFirst() {
405	<	@SuppressWarnings("unchecked")
406	<	E result = (E) elements[head];
280	<	if (result == null)
405	>	E e = elementAt(elements, head);
406	>	if (e == null)
407		throw new NoSuchElementException();
408	<	return result;
408	>	// checkInvariants();
409	>	return e;
410		}
411
412		/**
413		* @throws NoSuchElementException {@inheritDoc}
414		*/
415		public E getLast() {
416	<	@SuppressWarnings("unchecked")
417	<	E result = (E) elements[(tail - 1) & (elements.length - 1)];
418	<	if (result == null)
416	>	final Object[] es = elements;
417	>	E e = elementAt(es, dec(tail, es.length));
418	>	if (e == null)
419		throw new NoSuchElementException();
420	<	return result;
420	>	// checkInvariants();
421	>	return e;
422		}
423
296	–	@SuppressWarnings("unchecked")
424		public E peekFirst() {
425	<	// elements[head] is null if deque empty
426	<	return (E) elements[head];
425	>	// checkInvariants();
426	>	return elementAt(elements, head);
427		}
428
302	–	@SuppressWarnings("unchecked")
429		public E peekLast() {
430	<	return (E) elements[(tail - 1) & (elements.length - 1)];
430	>	// checkInvariants();
431	>	final Object[] es;
432	>	return elementAt(es = elements, dec(tail, es.length));
433		}
434
435		/**
#	Line 318 | Line 446 | public class ArrayDeque<E> extends Abstr
446		*/
447		public boolean removeFirstOccurrence(Object o) {
448		if (o != null) {
449	<	int mask = elements.length - 1;
450	<	int i = head;
451	<	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
452	<	if (o.equals(x)) {
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 344 | Line 474 | public class ArrayDeque<E> extends Abstr
474		*/
475		public boolean removeLastOccurrence(Object o) {
476		if (o != null) {
477	<	int mask = elements.length - 1;
478	<	int i = (tail - 1) & mask;
479	<	for (Object x; (x = elements[i]) != null; i = (i - 1) & mask) {
480	<	if (o.equals(x)) {
481	<	delete(i);
482	<	return true;
483	<	}
477	>	final Object[] es = elements;
478	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
479	>	; i = es.length, to = end) {
480	>	while (--i >= to)
481	>	if (o.equals(es[i])) {
482	>	delete(i);
483	>	return true;
484	>	}
485	>	if (to == end) break;
486		}
487		}
488		return false;
#	Line 470 | Line 602 | public class ArrayDeque<E> extends Abstr
602		return removeFirst();
603		}
604
473	–	private void checkInvariants() {
474	–	assert elements[tail] == null;
475	–	assert head == tail ? elements[head] == null :
476	–	(elements[head] != null &&
477	–	elements[(tail - 1) & (elements.length - 1)] != null);
478	–	assert elements[(head - 1) & (elements.length - 1)] == null;
479	–	}
480	–
605		/**
606	<	* Removes the element at the specified position in the elements array,
607	<	* adjusting head and tail as necessary.  This can result in motion of
608	<	* elements backwards or forwards in the array.
606	>	* Removes the element at the specified position in the elements array.
607	>	* This can result in forward or backwards motion of array elements.
608	>	* We optimize for least element motion.
609		*
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 mask = elements.length - 1;
616	>	// checkInvariants();
617	>	final Object[] es = elements;
618	>	final int capacity = es.length;
619		final int h = head;
620	<	final int t = tail;
621	<	final int front = (i - h) & mask;
622	<	final int back  = (t - i) & mask;
499	<
500	<	// Invariant: head <= i < tail mod circularity
501	<	if (front >= ((t - h) & mask))
502	<	throw new ConcurrentModificationException();
503	<
504	<	// Optimize for least element motion
620	>	// number of elements before to-be-deleted elt
621	>	final int front = sub(i, h, capacity);
622	>	final int back = size() - front - 1; // number of elements after
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[mask];
630	<	System.arraycopy(elements, h, elements, h + 1, mask - h);
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;
633	<	head = (h + 1) & mask;
632	>	es[h] = null;
633	>	head = inc(h, capacity);
634	>	// checkInvariants();
635		return false;
636		} else {
637	<	if (i < t) { // Copy the null tail as well
638	<	System.arraycopy(elements, i + 1, elements, i, back);
639	<	tail = t - 1;
637	>	// move back elements backwards
638	>	tail = dec(tail, capacity);
639	>	if (i <= tail) {
640	>	System.arraycopy(es, i + 1, es, i, back);
641		} else { // Wrap around
642	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
643	<	elements[mask] = elements[0];
644	<	System.arraycopy(elements, 1, elements, 0, t);
645	<	tail = (t - 1) & mask;
642	>	int firstLeg = capacity - (i + 1);
643	>	System.arraycopy(es, i + 1, es, i, firstLeg);
644	>	es[capacity - 1] = es[0];
645	>	System.arraycopy(es, 1, es, 0, back - firstLeg - 1);
646		}
647	+	es[tail] = null;
648	+	// checkInvariants();
649		return true;
650		}
651		}
#	Line 535 | Line 658 | public class ArrayDeque<E> extends Abstr
658		* @return the number of elements in this deque
659		*/
660		public int size() {
661	<	return (tail - head) & (elements.length - 1);
661	>	return sub(tail, head, elements.length);
662		}
663
664		/**
#	Line 564 | Line 687 | public class ArrayDeque<E> extends Abstr
687		}
688
689		private class DeqIterator implements Iterator<E> {
690	<	/**
691	<	* Index of element to be returned by subsequent call to next.
569	<	*/
570	<	private int cursor = head;
690	>	/** Index of element to be returned by subsequent call to next. */
691	>	int cursor;
692
693	<	/**
694	<	* Tail recorded at construction (also in remove), to stop
574	<	* iterator and also to check for comodification.
575	<	*/
576	<	private int fence = tail;
693	>	/** Number of elements yet to be returned. */
694	>	int remaining = size();
695
696		/**
697		* Index of element returned by most recent call to next.
698		* Reset to -1 if element is deleted by a call to remove.
699		*/
700	<	private int lastRet = -1;
700	>	int lastRet = -1;
701
702	<	public boolean hasNext() {
703	<	return cursor != fence;
702	>	DeqIterator() { cursor = head; }
703	>
704	>	public final boolean hasNext() {
705	>	return remaining > 0;
706		}
707
708		public E next() {
709	<	if (cursor == fence)
709	>	if (remaining <= 0)
710		throw new NoSuchElementException();
711	<	@SuppressWarnings("unchecked")
712	<	E result = (E) elements[cursor];
593	<	// This check doesn't catch all possible comodifications,
594	<	// but does catch the ones that corrupt traversal
595	<	if (tail != fence || result == null)
596	<	throw new ConcurrentModificationException();
711	>	final Object[] es = elements;
712	>	E e = nonNullElementAt(es, cursor);
713		lastRet = cursor;
714	<	cursor = (cursor + 1) & (elements.length - 1);
715	<	return result;
714	>	cursor = inc(cursor, es.length);
715	>	remaining--;
716	>	return e;
717	>	}
718	>
719	>	void postDelete(boolean leftShifted) {
720	>	if (leftShifted)
721	>	cursor = dec(cursor, elements.length);
722		}
723
724	<	public void remove() {
724	>	public final void remove() {
725		if (lastRet < 0)
726		throw new IllegalStateException();
727	<	if (delete(lastRet)) { // if left-shifted, undo increment in next()
606	<	cursor = (cursor - 1) & (elements.length - 1);
607	<	fence = tail;
608	<	}
727	>	postDelete(delete(lastRet));
728		lastRet = -1;
729		}
730
731		public void forEachRemaining(Consumer<? super E> action) {
732		Objects.requireNonNull(action);
733	<	Object[] a = elements;
734	<	int m = a.length - 1, f = fence, i = cursor;
735	<	cursor = f;
736	<	while (i != f) {
737	<	@SuppressWarnings("unchecked") E e = (E)a[i];
738	<	i = (i + 1) & m;
739	<	if (e == null)
740	<	throw new ConcurrentModificationException();
741	<	action.accept(e);
733	>	int r;
734	>	if ((r = remaining) <= 0)
735	>	return;
736	>	remaining = 0;
737	>	final Object[] es = elements;
738	>	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
739	>	throw new ConcurrentModificationException();
740	>	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
741	>	; i = 0, to = end) {
742	>	for (; i < to; i++)
743	>	action.accept(elementAt(es, i));
744	>	if (to == end) {
745	>	if (end != tail)
746	>	throw new ConcurrentModificationException();
747	>	lastRet = dec(end, es.length);
748	>	break;
749	>	}
750	>	}
751	>	}
752	>	}
753	>
754	>	private class DescendingIterator extends DeqIterator {
755	>	DescendingIterator() { cursor = last(); }
756	>
757	>	public final E next() {
758	>	if (remaining <= 0)
759	>	throw new NoSuchElementException();
760	>	final Object[] es = elements;
761	>	E e = nonNullElementAt(es, cursor);
762	>	lastRet = cursor;
763	>	cursor = dec(cursor, es.length);
764	>	remaining--;
765	>	return e;
766	>	}
767	>
768	>	void postDelete(boolean leftShifted) {
769	>	if (!leftShifted)
770	>	cursor = inc(cursor, elements.length);
771	>	}
772	>
773	>	public final void forEachRemaining(Consumer<? super E> action) {
774	>	Objects.requireNonNull(action);
775	>	int r;
776	>	if ((r = remaining) <= 0)
777	>	return;
778	>	remaining = 0;
779	>	final Object[] es = elements;
780	>	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
781	>	throw new ConcurrentModificationException();
782	>	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
783	>	; i = es.length - 1, to = end) {
784	>	for (; i >= to; i--)
785	>	action.accept(elementAt(es, i));
786	>	if (to == end) {
787	>	if (end != head)
788	>	throw new ConcurrentModificationException();
789	>	lastRet = head;
790	>	break;
791	>	}
792		}
793		}
794		}
795
796		/**
797	<	* This class is nearly a mirror-image of DeqIterator, using tail
798	<	* instead of head for initial cursor, and head instead of tail
799	<	* for fence.
797	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
798	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
799	>	* deque.
800	>	*
801	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
802	>	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
803	>	* {@link Spliterator#NONNULL}.  Overriding implementations should document
804	>	* the reporting of additional characteristic values.
805	>	*
806	>	* @return a {@code Spliterator} over the elements in this deque
807	>	* @since 1.8
808		*/
809	<	private class DescendingIterator implements Iterator<E> {
810	<	private int cursor = tail;
811	<	private int fence = head;
812	<	private int lastRet = -1;
809	>	public Spliterator<E> spliterator() {
810	>	return new DeqSpliterator();
811	>	}
812	>
813	>	final class DeqSpliterator implements Spliterator<E> {
814	>	private int fence;      // -1 until first use
815	>	private int cursor;     // current index, modified on traverse/split
816
817	<	public boolean hasNext() {
818	<	return cursor != fence;
817	>	/** Constructs late-binding spliterator over all elements. */
818	>	DeqSpliterator() {
819	>	this.fence = -1;
820		}
821
822	<	public E next() {
823	<	if (cursor == fence)
824	<	throw new NoSuchElementException();
825	<	cursor = (cursor - 1) & (elements.length - 1);
645	<	@SuppressWarnings("unchecked")
646	<	E result = (E) elements[cursor];
647	<	if (head != fence || result == null)
648	<	throw new ConcurrentModificationException();
649	<	lastRet = cursor;
650	<	return result;
822	>	/** Constructs spliterator over the given range. */
823	>	DeqSpliterator(int origin, int fence) {
824	>	this.cursor = origin;
825	>	this.fence = fence;
826		}
827
828	<	public void remove() {
829	<	if (lastRet < 0)
830	<	throw new IllegalStateException();
831	<	if (!delete(lastRet)) {
832	<	cursor = (cursor + 1) & (elements.length - 1);
833	<	fence = head;
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;
834		}
835	<	lastRet = -1;
835	>	return t;
836	>	}
837	>
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	>	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	>	if (action == null)
867	>	throw new NullPointerException();
868	>	int t, i;
869	>	if ((t = fence) < 0) t = getFence();
870	>	if (t == (i = cursor))
871	>	return false;
872	>	final Object[] es;
873	>	action.accept(nonNullElementAt(es = elements, i));
874	>	cursor = inc(i, es.length);
875	>	return true;
876	>	}
877	>
878	>	public long estimateSize() {
879	>	return sub(getFence(), cursor, elements.length);
880	>	}
881	>
882	>	public int characteristics() {
883	>	return Spliterator.NONNULL
884	>	| Spliterator.ORDERED
885	>	| Spliterator.SIZED
886	>	| Spliterator.SUBSIZED;
887	>	}
888	>	}
889	>
890	>	public void forEach(Consumer<? super E> action) {
891	>	Objects.requireNonNull(action);
892	>	final Object[] es = elements;
893	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
894	>	; i = 0, to = end) {
895	>	for (; i < to; i++)
896	>	action.accept(elementAt(es, i));
897	>	if (to == end) {
898	>	if (end != tail) throw new ConcurrentModificationException();
899	>	break;
900	>	}
901	>	}
902	>	// checkInvariants();
903	>	}
904	>
905	>	/**
906	>	* Replaces each element of this deque with the result of applying the
907	>	* operator to that element, as specified by {@link List#replaceAll}.
908	>	*
909	>	* @param operator the operator to apply to each element
910	>	* @since TBD
911	>	*/
912	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
913	>	Objects.requireNonNull(operator);
914	>	final Object[] es = elements;
915	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
916	>	; i = 0, to = end) {
917	>	for (; i < to; i++)
918	>	es[i] = operator.apply(elementAt(es, i));
919	>	if (to == end) {
920	>	if (end != tail) throw new ConcurrentModificationException();
921	>	break;
922	>	}
923	>	}
924	>	// checkInvariants();
925	>	}
926	>
927	>	/**
928	>	* @throws NullPointerException {@inheritDoc}
929	>	*/
930	>	public boolean removeIf(Predicate<? super E> filter) {
931	>	Objects.requireNonNull(filter);
932	>	return bulkRemove(filter);
933	>	}
934	>
935	>	/**
936	>	* @throws NullPointerException {@inheritDoc}
937	>	*/
938	>	public boolean removeAll(Collection<?> c) {
939	>	Objects.requireNonNull(c);
940	>	return bulkRemove(e -> c.contains(e));
941	>	}
942	>
943	>	/**
944	>	* @throws NullPointerException {@inheritDoc}
945	>	*/
946	>	public boolean retainAll(Collection<?> c) {
947	>	Objects.requireNonNull(c);
948	>	return bulkRemove(e -> !c.contains(e));
949	>	}
950	>
951	>	/** Implementation of bulk remove methods. */
952	>	private boolean bulkRemove(Predicate<? super E> filter) {
953	>	// checkInvariants();
954	>	final Object[] es = elements;
955	>	// Optimize for initial run of survivors
956	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
957	>	; i = 0, to = end) {
958	>	for (; i < to; i++)
959	>	if (filter.test(elementAt(es, i)))
960	>	return bulkRemoveModified(filter, i, to);
961	>	if (to == end) {
962	>	if (end != tail) throw new ConcurrentModificationException();
963	>	break;
964	>	}
965	>	}
966	>	return false;
967	>	}
968	>
969	>	/**
970	>	* Helper for bulkRemove, in case of at least one deletion.
971	>	* @param i valid index of first element to be deleted
972	>	*/
973	>	private boolean bulkRemoveModified(
974	>	Predicate<? super E> filter, int i, int to) {
975	>	final Object[] es = elements;
976	>	final int capacity = es.length;
977	>	// a two-finger algorithm, with hare i reading, tortoise j writing
978	>	int j = i++;
979	>	final int end = tail;
980	>	try {
981	>	for (;; j = 0) {    // j rejoins i on second leg
982	>	E e;
983	>	// In this loop, i and j are on the same leg, with i > j
984	>	for (; i < to; i++)
985	>	if (!filter.test(e = elementAt(es, i)))
986	>	es[j++] = e;
987	>	if (to == end) break;
988	>	// In this loop, j is on the first leg, i on the second
989	>	for (i = 0, to = end; i < to && j < capacity; i++)
990	>	if (!filter.test(e = elementAt(es, i)))
991	>	es[j++] = e;
992	>	if (i >= to) {
993	>	if (j == capacity) j = 0; // "corner" case
994	>	break;
995	>	}
996	>	}
997	>	return true;
998	>	} catch (Throwable ex) {
999	>	// copy remaining elements
1000	>	for (; i != end; i = inc(i, capacity), j = inc(j, capacity))
1001	>	es[j] = es[i];
1002	>	throw ex;
1003	>	} finally {
1004	>	if (end != tail) throw new ConcurrentModificationException();
1005	>	circularClear(es, tail = j, end);
1006	>	// checkInvariants();
1007		}
1008		}
1009
#	Line 671 | Line 1017 | public class ArrayDeque<E> extends Abstr
1017		*/
1018		public boolean contains(Object o) {
1019		if (o != null) {
1020	<	int mask = elements.length - 1;
1021	<	int i = head;
1022	<	for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) {
1023	<	if (o.equals(x))
1024	<	return true;
1020	>	final Object[] es = elements;
1021	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1022	>	; i = 0, to = end) {
1023	>	for (; i < to; i++)
1024	>	if (o.equals(es[i]))
1025	>	return true;
1026	>	if (to == end) break;
1027		}
1028		}
1029		return false;
#	Line 703 | Line 1051 | public class ArrayDeque<E> extends Abstr
1051		* The deque will be empty after this call returns.
1052		*/
1053		public void clear() {
1054	<	int h = head;
1055	<	int t = tail;
1056	<	if (h != t) { // clear all cells
1057	<	head = tail = 0;
1058	<	int i = h;
1059	<	int mask = elements.length - 1;
1060	<	do {
1061	<	elements[i] = null;
1062	<	i = (i + 1) & mask;
1063	<	} while (i != t);
1054	>	circularClear(elements, head, tail);
1055	>	head = tail = 0;
1056	>	// checkInvariants();
1057	>	}
1058	>
1059	>	/**
1060	>	* Nulls out slots starting at array index i, upto index end.
1061	>	*/
1062	>	private static void circularClear(Object[] es, int i, int end) {
1063	>	for (int to = (i <= end) ? end : es.length;
1064	>	; i = 0, to = end) {
1065	>	Arrays.fill(es, i, to, null);
1066	>	if (to == end) break;
1067		}
1068		}
1069
#	Line 730 | Line 1081 | public class ArrayDeque<E> extends Abstr
1081		* @return an array containing all of the elements in this deque
1082		*/
1083		public Object[] toArray() {
1084	<	final int head = this.head;
1085	<	final int tail = this.tail;
1086	<	boolean wrap = (tail < head);
1087	<	int end = wrap ? tail + elements.length : tail;
1088	<	Object[] a = Arrays.copyOfRange(elements, head, end);
1089	<	if (wrap)
1090	<	System.arraycopy(elements, 0, a, elements.length - head, tail);
1084	>	return toArray(Object[].class);
1085	>	}
1086	>
1087	>	private <T> T[] toArray(Class<T[]> klazz) {
1088	>	final Object[] es = elements;
1089	>	final T[] a;
1090	>	final int size = size(), head = this.head, end;
1091	>	final int len = Math.min(size, es.length - head);
1092	>	if ((end = head + size) >= 0) {
1093	>	a = Arrays.copyOfRange(es, head, end, klazz);
1094	>	} else {
1095	>	// integer overflow!
1096	>	a = Arrays.copyOfRange(es, 0, size, klazz);
1097	>	System.arraycopy(es, head, a, 0, len);
1098	>	}
1099	>	if (tail < head)
1100	>	System.arraycopy(es, 0, a, len, tail);
1101		return a;
1102		}
1103
#	Line 778 | Line 1139 | public class ArrayDeque<E> extends Abstr
1139		*/
1140		@SuppressWarnings("unchecked")
1141		public <T> T[] toArray(T[] a) {
1142	<	final int head = this.head;
1143	<	final int tail = this.tail;
1144	<	boolean wrap = (tail < head);
1145	<	int size = (tail - head) + (wrap ? elements.length : 0);
1146	<	int firstLeg = size - (wrap ? tail : 0);
1147	<	int len = a.length;
1148	<	if (size > len) {
1149	<	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
789	<	a.getClass());
790	<	} else {
791	<	System.arraycopy(elements, head, a, 0, firstLeg);
792	<	if (size < len)
793	<	a[size] = null;
1142	>	final int size;
1143	>	if ((size = size()) > a.length)
1144	>	return toArray((Class<T[]>) a.getClass());
1145	>	final Object[] es = elements;
1146	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1147	>	; i = 0, len = tail) {
1148	>	System.arraycopy(es, i, a, j, len);
1149	>	if ((j += len) == size) break;
1150		}
1151	<	if (wrap)
1152	<	System.arraycopy(elements, 0, a, firstLeg, tail);
1151	>	if (size < a.length)
1152	>	a[size] = null;
1153		return a;
1154		}
1155
#	Line 834 | Line 1190 | public class ArrayDeque<E> extends Abstr
1190		s.writeInt(size());
1191
1192		// Write out elements in order.
1193	<	int mask = elements.length - 1;
1194	<	for (int i = head; i != tail; i = (i + 1) & mask)
1195	<	s.writeObject(elements[i]);
1193	>	final Object[] es = elements;
1194	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1195	>	; i = 0, to = end) {
1196	>	for (; i < to; i++)
1197	>	s.writeObject(es[i]);
1198	>	if (to == end) break;
1199	>	}
1200		}
1201
1202		/**
#	Line 852 | Line 1212 | public class ArrayDeque<E> extends Abstr
1212
1213		// Read in size and allocate array
1214		int size = s.readInt();
1215	<	allocateElements(size);
1216	<	head = 0;
857	<	tail = size;
1215	>	elements = new Object[size + 1];
1216	>	this.tail = size;
1217
1218		// Read in all elements in the proper order.
1219		for (int i = 0; i < size; i++)
1220		elements[i] = s.readObject();
1221		}
1222
1223	<	/**
1224	<	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
1225	<	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
1226	<	* deque.
1227	<	*
1228	<	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
1229	<	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
1230	<	* {@link Spliterator#NONNULL}.  Overriding implementations should document
1231	<	* the reporting of additional characteristic values.
1232	<	*
1233	<	* @return a {@code Spliterator} over the elements in this deque
1234	<	* @since 1.8
1235	<	*/
1236	<	public Spliterator<E> spliterator() {
1237	<	return new DeqSpliterator<>(this, -1, -1);
1238	<	}
1239	<
881	<	static final class DeqSpliterator<E> implements Spliterator<E> {
882	<	private final ArrayDeque<E> deq;
883	<	private int fence;  // -1 until first use
884	<	private int index;  // current index, modified on traverse/split
885	<
886	<	/** Creates new spliterator covering the given array and range. */
887	<	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
888	<	this.deq = deq;
889	<	this.index = origin;
890	<	this.fence = fence;
891	<	}
892	<
893	<	private int getFence() { // force initialization
894	<	int t;
895	<	if ((t = fence) < 0) {
896	<	t = fence = deq.tail;
897	<	index = deq.head;
898	<	}
899	<	return t;
900	<	}
901	<
902	<	public DeqSpliterator<E> trySplit() {
903	<	int t = getFence(), h = index, n = deq.elements.length;
904	<	if (h != t && ((h + 1) & (n - 1)) != t) {
905	<	if (h > t)
906	<	t += n;
907	<	int m = ((h + t) >>> 1) & (n - 1);
908	<	return new DeqSpliterator<E>(deq, h, index = m);
909	<	}
910	<	return null;
911	<	}
912	<
913	<	public void forEachRemaining(Consumer<? super E> consumer) {
914	<	if (consumer == null)
915	<	throw new NullPointerException();
916	<	Object[] a = deq.elements;
917	<	int m = a.length - 1, f = getFence(), i = index;
918	<	index = f;
919	<	while (i != f) {
920	<	@SuppressWarnings("unchecked") E e = (E)a[i];
921	<	i = (i + 1) & m;
922	<	if (e == null)
923	<	throw new ConcurrentModificationException();
924	<	consumer.accept(e);
925	<	}
926	<	}
927	<
928	<	public boolean tryAdvance(Consumer<? super E> consumer) {
929	<	if (consumer == null)
930	<	throw new NullPointerException();
931	<	Object[] a = deq.elements;
932	<	int m = a.length - 1, f = getFence(), i = index;
933	<	if (i != f) {
934	<	@SuppressWarnings("unchecked") E e = (E)a[i];
935	<	index = (i + 1) & m;
936	<	if (e == null)
937	<	throw new ConcurrentModificationException();
938	<	consumer.accept(e);
939	<	return true;
940	<	}
941	<	return false;
942	<	}
943	<
944	<	public long estimateSize() {
945	<	int n = getFence() - index;
946	<	if (n < 0)
947	<	n += deq.elements.length;
948	<	return (long) n;
949	<	}
950	<
951	<	@Override
952	<	public int characteristics() {
953	<	return Spliterator.ORDERED | Spliterator.SIZED |
954	<	Spliterator.NONNULL | Spliterator.SUBSIZED;
1223	>	/** debugging */
1224	>	void checkInvariants() {
1225	>	try {
1226	>	int capacity = elements.length;
1227	>	// assert head >= 0 && head < capacity;
1228	>	// assert tail >= 0 && tail < capacity;
1229	>	// assert capacity > 0;
1230	>	// assert size() < capacity;
1231	>	// assert head == tail || elements[head] != null;
1232	>	// assert elements[tail] == null;
1233	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1234	>	} catch (Throwable t) {
1235	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1236	>	head, tail, elements.length);
1237	>	System.err.printf("elements=%s%n",
1238	>	Arrays.toString(elements));
1239	>	throw t;
1240		}
1241		}
1242

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