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Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.51 by jsr166, Wed Feb 20 12:39:06 2013 UTC vs.
Revision 1.88 by jsr166, Mon Oct 24 16:01:25 2016 UTC

#	Line 4 | Line 4
4		*/
5
6		package java.util;
7	+
8		import java.io.Serializable;
9		import java.util.function.Consumer;
10	<	import java.util.stream.Stream;
11	<	import java.util.stream.Streams;
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 53 | Line 54 | import java.util.stream.Streams;
54		* Java Collections Framework</a>.
55		*
56		* @author  Josh Bloch and Doug Lea
57	+	* @param <E> the type of elements held in this deque
58		* @since   1.6
57	–	* @param <E> the type of elements held in this collection
59		*/
60		public class ArrayDeque<E> extends AbstractCollection<E>
61		implements Deque<E>, Cloneable, Serializable
62		{
63		/**
64		* The array in which the elements of the deque are stored.
65	<	* The capacity of the deque is the length of this array, which is
66	<	* always a power of two. The array is never allowed to become
66	<	* full, except transiently within an addX method where it is
67	<	* resized (see doubleCapacity) immediately upon becoming full,
68	<	* thus avoiding head and tail wrapping around to equal each
69	<	* other.  We also guarantee that all array cells not holding
70	<	* deque elements are always null.
65	>	* We guarantee that all array cells not holding deque elements
66	>	* are always null.
67		*/
68	<	transient Object[] elements; // non-private to simplify nested class access
68	>	transient Object[] elements;
69
70		/**
71		* The index of the element at the head of the deque (which is the
72		* element that would be removed by remove() or pop()); or an
73	<	* arbitrary number equal to tail if the deque is empty.
73	>	* arbitrary number 0 <= head < elements.length if the deque is empty.
74		*/
75		transient int head;
76
77	+	/** Number of elements in this collection. */
78	+	transient int size;
79	+
80		/**
81	<	* The index at which the next element would be added to the tail
82	<	* of the deque (via addLast(E), add(E), or push(E)).
81	>	* The maximum size of array to allocate.
82	>	* Some VMs reserve some header words in an array.
83	>	* Attempts to allocate larger arrays may result in
84	>	* OutOfMemoryError: Requested array size exceeds VM limit
85		*/
86	<	transient int tail;
86	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
87
88		/**
89	<	* The minimum capacity that we'll use for a newly created deque.
90	<	* Must be a power of 2.
89	>	* Increases the capacity of this deque by at least the given amount.
90	>	*
91	>	* @param needed the required minimum extra capacity; must be positive
92		*/
93	<	private static final int MIN_INITIAL_CAPACITY = 8;
93	>	private void grow(int needed) {
94	>	// overflow-conscious code
95	>	// checkInvariants();
96	>	int oldCapacity = elements.length;
97	>	int newCapacity;
98	>	// Double size if small; else grow by 50%
99	>	int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
100	>	if (jump < needed
101	>	|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
102	>	newCapacity = newCapacity(needed, jump);
103	>	elements = Arrays.copyOf(elements, newCapacity);
104	>	if (oldCapacity - head < size) {
105	>	// wrap around; slide first leg forward to end of array
106	>	int newSpace = newCapacity - oldCapacity;
107	>	System.arraycopy(elements, head,
108	>	elements, head + newSpace,
109	>	oldCapacity - head);
110	>	Arrays.fill(elements, head, head + newSpace, null);
111	>	head += newSpace;
112	>	}
113	>	// checkInvariants();
114	>	}
115
116	<	// ******  Array allocation and resizing utilities ******
116	>	/** Capacity calculation for edge conditions, especially overflow. */
117	>	private int newCapacity(int needed, int jump) {
118	>	int oldCapacity = elements.length;
119	>	int minCapacity;
120	>	if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
121	>	if (minCapacity < 0)
122	>	throw new IllegalStateException("Sorry, deque too big");
123	>	return Integer.MAX_VALUE;
124	>	}
125	>	if (needed > jump)
126	>	return minCapacity;
127	>	return (oldCapacity + jump - MAX_ARRAY_SIZE < 0)
128	>	? oldCapacity + jump
129	>	: MAX_ARRAY_SIZE;
130	>	}
131
132		/**
133	<	* Allocates empty array to hold the given number of elements.
133	>	* Increases the internal storage of this collection, if necessary,
134	>	* to ensure that it can hold at least the given number of elements.
135		*
136	<	* @param numElements  the number of elements to hold
136	>	* @param minCapacity the desired minimum capacity
137	>	* @since TBD
138		*/
139	<	private void allocateElements(int numElements) {
140	<	int initialCapacity = MIN_INITIAL_CAPACITY;
141	<	// Find the best power of two to hold elements.
142	<	// Tests "<=" because arrays aren't kept full.
104	<	if (numElements >= initialCapacity) {
105	<	initialCapacity = numElements;
106	<	initialCapacity |= (initialCapacity >>>  1);
107	<	initialCapacity |= (initialCapacity >>>  2);
108	<	initialCapacity |= (initialCapacity >>>  4);
109	<	initialCapacity |= (initialCapacity >>>  8);
110	<	initialCapacity |= (initialCapacity >>> 16);
111	<	initialCapacity++;
112	<
113	<	if (initialCapacity < 0)   // Too many elements, must back off
114	<	initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements
115	<	}
116	<	elements = new Object[initialCapacity];
139	>	/* public */ void ensureCapacity(int minCapacity) {
140	>	if (minCapacity > elements.length)
141	>	grow(minCapacity - elements.length);
142	>	// checkInvariants();
143		}
144
145		/**
146	<	* Doubles the capacity of this deque.  Call only when full, i.e.,
147	<	* when head and tail have wrapped around to become equal.
146	>	* Minimizes the internal storage of this collection.
147	>	*
148	>	* @since TBD
149		*/
150	<	private void doubleCapacity() {
151	<	assert head == tail;
152	<	int p = head;
153	<	int n = elements.length;
154	<	int r = n - p; // number of elements to the right of p
155	<	int newCapacity = n << 1;
129	<	if (newCapacity < 0)
130	<	throw new IllegalStateException("Sorry, deque too big");
131	<	Object[] a = new Object[newCapacity];
132	<	System.arraycopy(elements, p, a, 0, r);
133	<	System.arraycopy(elements, 0, a, r, p);
134	<	elements = a;
135	<	head = 0;
136	<	tail = n;
150	>	/* public */ void trimToSize() {
151	>	if (size < elements.length) {
152	>	elements = toArray();
153	>	head = 0;
154	>	}
155	>	// checkInvariants();
156		}
157
158		/**
#	Line 148 | Line 167 | public class ArrayDeque<E> extends Abstr
167		* Constructs an empty array deque with an initial capacity
168		* sufficient to hold the specified number of elements.
169		*
170	<	* @param numElements  lower bound on initial capacity of the deque
170	>	* @param numElements lower bound on initial capacity of the deque
171		*/
172		public ArrayDeque(int numElements) {
173	<	allocateElements(numElements);
173	>	elements = new Object[numElements];
174		}
175
176		/**
#	Line 165 | Line 184 | public class ArrayDeque<E> extends Abstr
184		* @throws NullPointerException if the specified collection is null
185		*/
186		public ArrayDeque(Collection<? extends E> c) {
187	<	allocateElements(c.size());
188	<	addAll(c);
187	>	Object[] elements = c.toArray();
188	>	// defend against c.toArray (incorrectly) not returning Object[]
189	>	// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652)
190	>	size = elements.length;
191	>	if (elements.getClass() != Object[].class)
192	>	elements = Arrays.copyOf(elements, size, Object[].class);
193	>	for (Object obj : elements)
194	>	Objects.requireNonNull(obj);
195	>	this.elements = elements;
196	>	}
197	>
198	>	/**
199	>	* Increments i, mod modulus.
200	>	* Precondition and postcondition: 0 <= i < modulus.
201	>	*/
202	>	static final int inc(int i, int modulus) {
203	>	if (++i == modulus) i = 0;
204	>	return i;
205	>	}
206	>
207	>	/**
208	>	* Decrements i, mod modulus.
209	>	* Precondition and postcondition: 0 <= i < modulus.
210	>	*/
211	>	static final int dec(int i, int modulus) {
212	>	if (--i < 0) i += modulus;
213	>	return i;
214	>	}
215	>
216	>	/**
217	>	* Adds i and j, mod modulus.
218	>	* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus.
219	>	*/
220	>	static final int add(int i, int j, int modulus) {
221	>	if ((i += j) - modulus >= 0) i -= modulus;
222	>	return i;
223	>	}
224	>
225	>	/**
226	>	* Returns the array index of the last element.
227	>	* May return invalid index -1 if there are no elements.
228	>	*/
229	>	final int tail() {
230	>	return add(head, size - 1, elements.length);
231	>	}
232	>
233	>	/**
234	>	* Returns element at array index i.
235	>	*/
236	>	@SuppressWarnings("unchecked")
237	>	private E elementAt(int i) {
238	>	return (E) elements[i];
239	>	}
240	>
241	>	/**
242	>	* A version of elementAt that checks for null elements.
243	>	* This check doesn't catch all possible comodifications,
244	>	* but does catch ones that corrupt traversal.
245	>	*/
246	>	E checkedElementAt(Object[] elements, int i) {
247	>	@SuppressWarnings("unchecked") E e = (E) elements[i];
248	>	if (e == null)
249	>	throw new ConcurrentModificationException();
250	>	return e;
251		}
252
253		// The main insertion and extraction methods are addFirst,
#	Line 180 | Line 261 | public class ArrayDeque<E> extends Abstr
261		* @throws NullPointerException if the specified element is null
262		*/
263		public void addFirst(E e) {
264	<	if (e == null)
265	<	throw new NullPointerException();
266	<	elements[head = (head - 1) & (elements.length - 1)] = e;
267	<	if (head == tail)
268	<	doubleCapacity();
264	>	// checkInvariants();
265	>	Objects.requireNonNull(e);
266	>	final Object[] elements;
267	>	final int capacity, s;
268	>	if ((s = size) == (capacity = (elements = this.elements).length))
269	>	addFirstSlowPath(e);
270	>	else
271	>	elements[head = dec(head, capacity)] = e;
272	>	size = s + 1;
273	>	// checkInvariants();
274	>	}
275	>
276	>	private void addFirstSlowPath(E e) {
277	>	grow(1);
278	>	final Object[] elements = this.elements;
279	>	elements[head = dec(head, elements.length)] = e;
280		}
281
282		/**
#	Line 196 | Line 288 | public class ArrayDeque<E> extends Abstr
288		* @throws NullPointerException if the specified element is null
289		*/
290		public void addLast(E e) {
291	<	if (e == null)
292	<	throw new NullPointerException();
293	<	elements[tail] = e;
294	<	if ( (tail = (tail + 1) & (elements.length - 1)) == head)
295	<	doubleCapacity();
291	>	// checkInvariants();
292	>	Objects.requireNonNull(e);
293	>	final Object[] elements;
294	>	final int capacity, s;
295	>	if ((s = size) == (capacity = (elements = this.elements).length))
296	>	addLastSlowPath(e);
297	>	else
298	>	elements[add(head, s, capacity)] = e;
299	>	size = s + 1;
300	>	// checkInvariants();
301	>	}
302	>
303	>	private void addLastSlowPath(E e) {
304	>	grow(1);
305	>	final Object[] elements = this.elements;
306	>	elements[add(head, size, elements.length)] = e;
307	>	}
308	>
309	>	/**
310	>	* Adds all of the elements in the specified collection at the end
311	>	* of this deque, as if by calling {@link #addLast} on each one,
312	>	* in the order that they are returned by the collection's
313	>	* iterator.
314	>	*
315	>	* @param c the elements to be inserted into this deque
316	>	* @return {@code true} if this deque changed as a result of the call
317	>	* @throws NullPointerException if the specified collection or any
318	>	*         of its elements are null
319	>	*/
320	>	public boolean addAll(Collection<? extends E> c) {
321	>	final int s = size, needed = c.size() - (elements.length - s);
322	>	if (needed > 0)
323	>	grow(needed);
324	>	c.forEach((e) -> addLast(e));
325	>	// checkInvariants();
326	>	return size > s;
327		}
328
329		/**
#	Line 231 | Line 354 | public class ArrayDeque<E> extends Abstr
354		* @throws NoSuchElementException {@inheritDoc}
355		*/
356		public E removeFirst() {
357	<	E x = pollFirst();
358	<	if (x == null)
357	>	// checkInvariants();
358	>	E e = pollFirst();
359	>	if (e == null)
360		throw new NoSuchElementException();
361	<	return x;
361	>	return e;
362		}
363
364		/**
365		* @throws NoSuchElementException {@inheritDoc}
366		*/
367		public E removeLast() {
368	<	E x = pollLast();
369	<	if (x == null)
368	>	// checkInvariants();
369	>	E e = pollLast();
370	>	if (e == null)
371		throw new NoSuchElementException();
372	<	return x;
372	>	return e;
373		}
374
375		public E pollFirst() {
376	<	int h = head;
377	<	@SuppressWarnings("unchecked")
378	<	E result = (E) elements[h];
254	<	// Element is null if deque empty
255	<	if (result == null)
376	>	// checkInvariants();
377	>	final int s, h;
378	>	if ((s = size) == 0)
379		return null;
380	<	elements[h] = null;     // Must null out slot
381	<	head = (h + 1) & (elements.length - 1);
382	<	return result;
380	>	final Object[] elements = this.elements;
381	>	@SuppressWarnings("unchecked") E e = (E) elements[h = head];
382	>	elements[h] = null;
383	>	head = inc(h, elements.length);
384	>	size = s - 1;
385	>	return e;
386		}
387
388		public E pollLast() {
389	<	int t = (tail - 1) & (elements.length - 1);
390	<	@SuppressWarnings("unchecked")
391	<	E result = (E) elements[t];
266	<	if (result == null)
389	>	// checkInvariants();
390	>	final int s, tail;
391	>	if ((s = size) == 0)
392		return null;
393	<	elements[t] = null;
394	<	tail = t;
395	<	return result;
393	>	final Object[] elements = this.elements;
394	>	@SuppressWarnings("unchecked")
395	>	E e = (E) elements[tail = add(head, s - 1, elements.length)];
396	>	elements[tail] = null;
397	>	size = s - 1;
398	>	return e;
399		}
400
401		/**
402		* @throws NoSuchElementException {@inheritDoc}
403		*/
404		public E getFirst() {
405	<	@SuppressWarnings("unchecked")
406	<	E result = (E) elements[head];
407	<	if (result == null)
280	<	throw new NoSuchElementException();
281	<	return result;
405	>	// checkInvariants();
406	>	if (size == 0) throw new NoSuchElementException();
407	>	return elementAt(head);
408		}
409
410		/**
411		* @throws NoSuchElementException {@inheritDoc}
412		*/
413		public E getLast() {
414	<	@SuppressWarnings("unchecked")
415	<	E result = (E) elements[(tail - 1) & (elements.length - 1)];
416	<	if (result == null)
291	<	throw new NoSuchElementException();
292	<	return result;
414	>	// checkInvariants();
415	>	if (size == 0) throw new NoSuchElementException();
416	>	return elementAt(tail());
417		}
418
295	–	@SuppressWarnings("unchecked")
419		public E peekFirst() {
420	<	// elements[head] is null if deque empty
421	<	return (E) elements[head];
420	>	// checkInvariants();
421	>	return (size == 0) ? null : elementAt(head);
422		}
423
301	–	@SuppressWarnings("unchecked")
424		public E peekLast() {
425	<	return (E) elements[(tail - 1) & (elements.length - 1)];
425	>	// checkInvariants();
426	>	return (size == 0) ? null : elementAt(tail());
427		}
428
429		/**
#	Line 316 | Line 439 | public class ArrayDeque<E> extends Abstr
439		* @return {@code true} if the deque contained the specified element
440		*/
441		public boolean removeFirstOccurrence(Object o) {
442	<	if (o == null)
443	<	return false;
444	<	int mask = elements.length - 1;
445	<	int i = head;
446	<	Object x;
447	<	while ( (x = elements[i]) != null) {
448	<	if (o.equals(x)) {
449	<	delete(i);
450	<	return true;
442	>	// checkInvariants();
443	>	if (o != null) {
444	>	final Object[] elements = this.elements;
445	>	final int capacity = elements.length;
446	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) {
447	>	if (o.equals(elements[i])) {
448	>	delete(i);
449	>	return true;
450	>	}
451		}
329	–	i = (i + 1) & mask;
452		}
453		return false;
454		}
#	Line 344 | Line 466 | public class ArrayDeque<E> extends Abstr
466		* @return {@code true} if the deque contained the specified element
467		*/
468		public boolean removeLastOccurrence(Object o) {
469	<	if (o == null)
470	<	return false;
471	<	int mask = elements.length - 1;
472	<	int i = (tail - 1) & mask;
473	<	Object x;
474	<	while ( (x = elements[i]) != null) {
475	<	if (o.equals(x)) {
476	<	delete(i);
477	<	return true;
469	>	if (o != null) {
470	>	final Object[] elements = this.elements;
471	>	final int capacity = elements.length;
472	>	for (int k = size, i = add(head, k - 1, capacity);
473	>	--k >= 0; i = dec(i, capacity)) {
474	>	if (o.equals(elements[i])) {
475	>	delete(i);
476	>	return true;
477	>	}
478		}
357	–	i = (i - 1) & mask;
479		}
480		return false;
481		}
#	Line 473 | Line 594 | public class ArrayDeque<E> extends Abstr
594		return removeFirst();
595		}
596
476	–	private void checkInvariants() {
477	–	assert elements[tail] == null;
478	–	assert head == tail ? elements[head] == null :
479	–	(elements[head] != null &&
480	–	elements[(tail - 1) & (elements.length - 1)] != null);
481	–	assert elements[(head - 1) & (elements.length - 1)] == null;
482	–	}
483	–
597		/**
598	<	* Removes the element at the specified position in the elements array,
599	<	* adjusting head and tail as necessary.  This can result in motion of
600	<	* elements backwards or forwards in the array.
598	>	* Removes the element at the specified position in the elements array.
599	>	* This can result in forward or backwards motion of array elements.
600	>	* We optimize for least element motion.
601		*
602		* <p>This method is called delete rather than remove to emphasize
603		* that its semantics differ from those of {@link List#remove(int)}.
604		*
605		* @return true if elements moved backwards
606		*/
607	<	private boolean delete(int i) {
608	<	checkInvariants();
607	>	boolean delete(int i) {
608	>	// checkInvariants();
609		final Object[] elements = this.elements;
610	<	final int mask = elements.length - 1;
610	>	final int capacity = elements.length;
611		final int h = head;
612	<	final int t = tail;
613	<	final int front = (i - h) & mask;
614	<	final int back  = (t - i) & mask;
502	<
503	<	// Invariant: head <= i < tail mod circularity
504	<	if (front >= ((t - h) & mask))
505	<	throw new ConcurrentModificationException();
506	<
507	<	// Optimize for least element motion
612	>	int front;              // number of elements before to-be-deleted elt
613	>	if ((front = i - h) < 0) front += capacity;
614	>	final int back = size - front - 1; // number of elements after
615		if (front < back) {
616	+	// move front elements forwards
617		if (h <= i) {
618		System.arraycopy(elements, h, elements, h + 1, front);
619		} else { // Wrap around
620		System.arraycopy(elements, 0, elements, 1, i);
621	<	elements[0] = elements[mask];
622	<	System.arraycopy(elements, h, elements, h + 1, mask - h);
621	>	elements[0] = elements[capacity - 1];
622	>	System.arraycopy(elements, h, elements, h + 1, front - (i + 1));
623		}
624		elements[h] = null;
625	<	head = (h + 1) & mask;
625	>	head = inc(h, capacity);
626	>	size--;
627	>	// checkInvariants();
628		return false;
629		} else {
630	<	if (i < t) { // Copy the null tail as well
630	>	// move back elements backwards
631	>	int tail = tail();
632	>	if (i <= tail) {
633		System.arraycopy(elements, i + 1, elements, i, back);
522	–	tail = t - 1;
634		} else { // Wrap around
635	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
636	<	elements[mask] = elements[0];
637	<	System.arraycopy(elements, 1, elements, 0, t);
638	<	tail = (t - 1) & mask;
635	>	int firstLeg = capacity - (i + 1);
636	>	System.arraycopy(elements, i + 1, elements, i, firstLeg);
637	>	elements[capacity - 1] = elements[0];
638	>	System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1);
639		}
640	+	elements[tail] = null;
641	+	size--;
642	+	// checkInvariants();
643		return true;
644		}
645		}
#	Line 538 | Line 652 | public class ArrayDeque<E> extends Abstr
652		* @return the number of elements in this deque
653		*/
654		public int size() {
655	<	return (tail - head) & (elements.length - 1);
655	>	return size;
656		}
657
658		/**
#	Line 547 | Line 661 | public class ArrayDeque<E> extends Abstr
661		* @return {@code true} if this deque contains no elements
662		*/
663		public boolean isEmpty() {
664	<	return head == tail;
664	>	return size == 0;
665		}
666
667		/**
#	Line 567 | Line 681 | public class ArrayDeque<E> extends Abstr
681		}
682
683		private class DeqIterator implements Iterator<E> {
684	<	/**
685	<	* Index of element to be returned by subsequent call to next.
572	<	*/
573	<	private int cursor = head;
684	>	/** Index of element to be returned by subsequent call to next. */
685	>	int cursor;
686
687	<	/**
688	<	* Tail recorded at construction (also in remove), to stop
577	<	* iterator and also to check for comodification.
578	<	*/
579	<	private int fence = tail;
687	>	/** Number of elements yet to be returned. */
688	>	int remaining = size;
689
690		/**
691		* Index of element returned by most recent call to next.
692		* Reset to -1 if element is deleted by a call to remove.
693		*/
694	<	private int lastRet = -1;
694	>	int lastRet = -1;
695	>
696	>	DeqIterator() { cursor = head; }
697
698	<	public boolean hasNext() {
699	<	return cursor != fence;
698	>	public final boolean hasNext() {
699	>	return remaining > 0;
700		}
701
702		public E next() {
703	<	if (cursor == fence)
703	>	if (remaining == 0)
704		throw new NoSuchElementException();
705	<	@SuppressWarnings("unchecked")
595	<	E result = (E) elements[cursor];
596	<	// This check doesn't catch all possible comodifications,
597	<	// but does catch the ones that corrupt traversal
598	<	if (tail != fence || result == null)
599	<	throw new ConcurrentModificationException();
705	>	E e = checkedElementAt(elements, cursor);
706		lastRet = cursor;
707	<	cursor = (cursor + 1) & (elements.length - 1);
708	<	return result;
707	>	cursor = inc(cursor, elements.length);
708	>	remaining--;
709	>	return e;
710	>	}
711	>
712	>	void postDelete(boolean leftShifted) {
713	>	if (leftShifted)
714	>	cursor = dec(cursor, elements.length); // undo inc in next
715		}
716
717	<	public void remove() {
717	>	public final void remove() {
718		if (lastRet < 0)
719		throw new IllegalStateException();
720	<	if (delete(lastRet)) { // if left-shifted, undo increment in next()
609	<	cursor = (cursor - 1) & (elements.length - 1);
610	<	fence = tail;
611	<	}
720	>	postDelete(delete(lastRet));
721		lastRet = -1;
722		}
614	–	}
723
724	<	private class DescendingIterator implements Iterator<E> {
725	<	/*
726	<	* This class is nearly a mirror-image of DeqIterator, using
727	<	* tail instead of head for initial cursor, and head instead of
728	<	* tail for fence.
729	<	*/
730	<	private int cursor = tail;
731	<	private int fence = head;
624	<	private int lastRet = -1;
625	<
626	<	public boolean hasNext() {
627	<	return cursor != fence;
724	>	public void forEachRemaining(Consumer<? super E> action) {
725	>	Objects.requireNonNull(action);
726	>	final Object[] elements = ArrayDeque.this.elements;
727	>	final int capacity = elements.length;
728	>	int k = remaining;
729	>	remaining = 0;
730	>	for (int i = cursor; --k >= 0; i = inc(i, capacity))
731	>	action.accept(checkedElementAt(elements, i));
732		}
733	+	}
734
735	<	public E next() {
736	<	if (cursor == fence)
735	>	private class DescendingIterator extends DeqIterator {
736	>	DescendingIterator() { cursor = tail(); }
737	>
738	>	public final E next() {
739	>	if (remaining == 0)
740		throw new NoSuchElementException();
741	<	cursor = (cursor - 1) & (elements.length - 1);
634	<	@SuppressWarnings("unchecked")
635	<	E result = (E) elements[cursor];
636	<	if (head != fence || result == null)
637	<	throw new ConcurrentModificationException();
741	>	E e = checkedElementAt(elements, cursor);
742		lastRet = cursor;
743	<	return result;
743	>	cursor = dec(cursor, elements.length);
744	>	remaining--;
745	>	return e;
746		}
747
748	<	public void remove() {
749	<	if (lastRet < 0)
750	<	throw new IllegalStateException();
751	<	if (!delete(lastRet)) {
752	<	cursor = (cursor + 1) & (elements.length - 1);
753	<	fence = head;
748	>	void postDelete(boolean leftShifted) {
749	>	if (!leftShifted)
750	>	cursor = inc(cursor, elements.length); // undo dec in next
751	>	}
752	>
753	>	public final void forEachRemaining(Consumer<? super E> action) {
754	>	Objects.requireNonNull(action);
755	>	final Object[] elements = ArrayDeque.this.elements;
756	>	final int capacity = elements.length;
757	>	int k = remaining;
758	>	remaining = 0;
759	>	for (int i = cursor; --k >= 0; i = dec(i, capacity))
760	>	action.accept(checkedElementAt(elements, i));
761	>	}
762	>	}
763	>
764	>	/**
765	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
766	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
767	>	* deque.
768	>	*
769	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
770	>	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
771	>	* {@link Spliterator#NONNULL}.  Overriding implementations should document
772	>	* the reporting of additional characteristic values.
773	>	*
774	>	* @return a {@code Spliterator} over the elements in this deque
775	>	* @since 1.8
776	>	*/
777	>	public Spliterator<E> spliterator() {
778	>	return new ArrayDequeSpliterator();
779	>	}
780	>
781	>	final class ArrayDequeSpliterator implements Spliterator<E> {
782	>	private int cursor;
783	>	private int remaining; // -1 until late-binding first use
784	>
785	>	/** Constructs late-binding spliterator over all elements. */
786	>	ArrayDequeSpliterator() {
787	>	this.remaining = -1;
788	>	}
789	>
790	>	/** Constructs spliterator over the given slice. */
791	>	ArrayDequeSpliterator(int cursor, int count) {
792	>	this.cursor = cursor;
793	>	this.remaining = count;
794	>	}
795	>
796	>	/** Ensures late-binding initialization; then returns remaining. */
797	>	private int remaining() {
798	>	if (remaining < 0) {
799	>	cursor = head;
800	>	remaining = size;
801		}
802	<	lastRet = -1;
802	>	return remaining;
803	>	}
804	>
805	>	public ArrayDequeSpliterator trySplit() {
806	>	final int mid;
807	>	if ((mid = remaining() >> 1) > 0) {
808	>	int oldCursor = cursor;
809	>	cursor = add(cursor, mid, elements.length);
810	>	remaining -= mid;
811	>	return new ArrayDequeSpliterator(oldCursor, mid);
812	>	}
813	>	return null;
814	>	}
815	>
816	>	public void forEachRemaining(Consumer<? super E> action) {
817	>	Objects.requireNonNull(action);
818	>	final Object[] elements = ArrayDeque.this.elements;
819	>	final int capacity = elements.length;
820	>	int k = remaining();
821	>	remaining = 0;
822	>	for (int i = cursor; --k >= 0; i = inc(i, capacity))
823	>	action.accept(checkedElementAt(elements, i));
824	>	}
825	>
826	>	public boolean tryAdvance(Consumer<? super E> action) {
827	>	Objects.requireNonNull(action);
828	>	if (remaining() == 0)
829	>	return false;
830	>	action.accept(checkedElementAt(elements, cursor));
831	>	cursor = inc(cursor, elements.length);
832	>	remaining--;
833	>	return true;
834	>	}
835	>
836	>	public long estimateSize() {
837	>	return remaining();
838	>	}
839	>
840	>	public int characteristics() {
841	>	return Spliterator.NONNULL
842	>	| Spliterator.ORDERED
843	>	| Spliterator.SIZED
844	>	| Spliterator.SUBSIZED;
845	>	}
846	>	}
847	>
848	>	public void forEach(Consumer<? super E> action) {
849	>	// checkInvariants();
850	>	Objects.requireNonNull(action);
851	>	final Object[] elements = this.elements;
852	>	final int capacity = elements.length;
853	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
854	>	action.accept(elementAt(i));
855	>	// checkInvariants();
856	>	}
857	>
858	>	/**
859	>	* Replaces each element of this deque with the result of applying the
860	>	* operator to that element, as specified by {@link List#replaceAll}.
861	>	*
862	>	* @param operator the operator to apply to each element
863	>	* @since TBD
864	>	*/
865	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
866	>	Objects.requireNonNull(operator);
867	>	final Object[] elements = this.elements;
868	>	final int capacity = elements.length;
869	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
870	>	elements[i] = operator.apply(elementAt(i));
871	>	// checkInvariants();
872	>	}
873	>
874	>	/**
875	>	* @throws NullPointerException {@inheritDoc}
876	>	*/
877	>	public boolean removeIf(Predicate<? super E> filter) {
878	>	Objects.requireNonNull(filter);
879	>	return bulkRemove(filter);
880	>	}
881	>
882	>	/**
883	>	* @throws NullPointerException {@inheritDoc}
884	>	*/
885	>	public boolean removeAll(Collection<?> c) {
886	>	Objects.requireNonNull(c);
887	>	return bulkRemove(e -> c.contains(e));
888	>	}
889	>
890	>	/**
891	>	* @throws NullPointerException {@inheritDoc}
892	>	*/
893	>	public boolean retainAll(Collection<?> c) {
894	>	Objects.requireNonNull(c);
895	>	return bulkRemove(e -> !c.contains(e));
896	>	}
897	>
898	>	/** Implementation of bulk remove methods. */
899	>	private boolean bulkRemove(Predicate<? super E> filter) {
900	>	// checkInvariants();
901	>	final Object[] elements = this.elements;
902	>	final int capacity = elements.length;
903	>	int i = head, j = i, remaining = size, deleted = 0;
904	>	try {
905	>	for (; remaining > 0; remaining--, i = inc(i, capacity)) {
906	>	@SuppressWarnings("unchecked") E e = (E) elements[i];
907	>	if (filter.test(e))
908	>	deleted++;
909	>	else {
910	>	if (j != i)
911	>	elements[j] = e;
912	>	j = inc(j, capacity);
913	>	}
914	>	}
915	>	return deleted > 0;
916	>	} catch (Throwable ex) {
917	>	if (deleted > 0)
918	>	for (; remaining > 0;
919	>	remaining--, i = inc(i, capacity), j = inc(j, capacity))
920	>	elements[j] = elements[i];
921	>	throw ex;
922	>	} finally {
923	>	size -= deleted;
924	>	for (; --deleted >= 0; j = inc(j, capacity))
925	>	elements[j] = null;
926	>	// checkInvariants();
927		}
928		}
929
#	Line 659 | Line 936 | public class ArrayDeque<E> extends Abstr
936		* @return {@code true} if this deque contains the specified element
937		*/
938		public boolean contains(Object o) {
939	<	if (o == null)
940	<	return false;
941	<	int mask = elements.length - 1;
942	<	int i = head;
943	<	Object x;
944	<	while ( (x = elements[i]) != null) {
668	<	if (o.equals(x))
669	<	return true;
670	<	i = (i + 1) & mask;
939	>	if (o != null) {
940	>	final Object[] elements = this.elements;
941	>	final int capacity = elements.length;
942	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
943	>	if (o.equals(elements[i]))
944	>	return true;
945		}
946		return false;
947		}
#	Line 694 | Line 968 | public class ArrayDeque<E> extends Abstr
968		* The deque will be empty after this call returns.
969		*/
970		public void clear() {
971	<	int h = head;
972	<	int t = tail;
973	<	if (h != t) { // clear all cells
974	<	head = tail = 0;
975	<	int i = h;
976	<	int mask = elements.length - 1;
977	<	do {
704	<	elements[i] = null;
705	<	i = (i + 1) & mask;
706	<	} while (i != t);
971	>	final Object[] elements = this.elements;
972	>	final int capacity = elements.length, tail = head + size;
973	>	if (capacity - tail >= 0)
974	>	Arrays.fill(elements, head, tail, null);
975	>	else {
976	>	Arrays.fill(elements, head, capacity, null);
977	>	Arrays.fill(elements, 0, tail - capacity, null);
978		}
979	+	size = head = 0;
980	+	// checkInvariants();
981		}
982
983		/**
#	Line 721 | Line 994 | public class ArrayDeque<E> extends Abstr
994		* @return an array containing all of the elements in this deque
995		*/
996		public Object[] toArray() {
997	<	final int head = this.head;
998	<	final int tail = this.tail;
999	<	boolean wrap = (tail < head);
1000	<	int end = wrap ? tail + elements.length : tail;
1001	<	Object[] a = Arrays.copyOfRange(elements, head, end);
1002	<	if (wrap)
1003	<	System.arraycopy(elements, 0, a, elements.length - head, tail);
997	>	return toArray(Object[].class);
998	>	}
999	>
1000	>	private <T> T[] toArray(Class<T[]> klazz) {
1001	>	final Object[] elements = this.elements;
1002	>	final int capacity = elements.length;
1003	>	final int head = this.head, tail = head + size;
1004	>	final T[] a;
1005	>	if (tail >= 0) {
1006	>	a = Arrays.copyOfRange(elements, head, tail, klazz);
1007	>	} else {
1008	>	// integer overflow!
1009	>	a = Arrays.copyOfRange(elements, 0, size, klazz);
1010	>	System.arraycopy(elements, head, a, 0, capacity - head);
1011	>	}
1012	>	if (tail - capacity > 0)
1013	>	System.arraycopy(elements, 0, a, capacity - head, tail - capacity);
1014		return a;
1015		}
1016
#	Line 753 | Line 1036 | public class ArrayDeque<E> extends Abstr
1036		* The following code can be used to dump the deque into a newly
1037		* allocated array of {@code String}:
1038		*
1039	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
1039	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
1040		*
1041		* Note that {@code toArray(new Object[0])} is identical in function to
1042		* {@code toArray()}.
#	Line 769 | Line 1052 | public class ArrayDeque<E> extends Abstr
1052		*/
1053		@SuppressWarnings("unchecked")
1054		public <T> T[] toArray(T[] a) {
1055	<	final int head = this.head;
1056	<	final int tail = this.tail;
1057	<	boolean wrap = (tail < head);
1058	<	int size = (tail - head) + (wrap ? elements.length : 0);
1059	<	int firstLeg = size - (wrap ? tail : 0);
1060	<	int len = a.length;
1061	<	if (size > len) {
1062	<	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
1063	<	a.getClass());
1064	<	} else {
1065	<	System.arraycopy(elements, head, a, 0, firstLeg);
783	<	if (size < len)
784	<	a[size] = null;
1055	>	final int size = this.size;
1056	>	if (size > a.length)
1057	>	return toArray((Class<T[]>) a.getClass());
1058	>	final Object[] elements = this.elements;
1059	>	final int capacity = elements.length;
1060	>	final int head = this.head, tail = head + size;
1061	>	if (capacity - tail >= 0)
1062	>	System.arraycopy(elements, head, a, 0, size);
1063	>	else {
1064	>	System.arraycopy(elements, head, a, 0, capacity - head);
1065	>	System.arraycopy(elements, 0, a, capacity - head, tail - capacity);
1066		}
1067	<	if (wrap)
1068	<	System.arraycopy(elements, 0, a, firstLeg, tail);
1067	>	if (size < a.length)
1068	>	a[size] = null;
1069		return a;
1070		}
1071
#	Line 811 | Line 1092 | public class ArrayDeque<E> extends Abstr
1092		/**
1093		* Saves this deque to a stream (that is, serializes it).
1094		*
1095	+	* @param s the stream
1096	+	* @throws java.io.IOException if an I/O error occurs
1097		* @serialData The current size ({@code int}) of the deque,
1098		* followed by all of its elements (each an object reference) in
1099		* first-to-last order.
#	Line 820 | Line 1103 | public class ArrayDeque<E> extends Abstr
1103		s.defaultWriteObject();
1104
1105		// Write out size
1106	<	s.writeInt(size());
1106	>	s.writeInt(size);
1107
1108		// Write out elements in order.
1109	<	int mask = elements.length - 1;
1110	<	for (int i = head; i != tail; i = (i + 1) & mask)
1109	>	final Object[] elements = this.elements;
1110	>	final int capacity = elements.length;
1111	>	for (int k = size, i = head; --k >= 0; i = inc(i, capacity))
1112		s.writeObject(elements[i]);
1113		}
1114
1115		/**
1116		* Reconstitutes this deque from a stream (that is, deserializes it).
1117	+	* @param s the stream
1118	+	* @throws ClassNotFoundException if the class of a serialized object
1119	+	*         could not be found
1120	+	* @throws java.io.IOException if an I/O error occurs
1121		*/
1122		private void readObject(java.io.ObjectInputStream s)
1123		throws java.io.IOException, ClassNotFoundException {
1124		s.defaultReadObject();
1125
1126		// Read in size and allocate array
1127	<	int size = s.readInt();
840	<	allocateElements(size);
841	<	head = 0;
842	<	tail = size;
1127	>	elements = new Object[size = s.readInt()];
1128
1129		// Read in all elements in the proper order.
1130		for (int i = 0; i < size; i++)
1131		elements[i] = s.readObject();
1132		}
1133
1134	<	Spliterator<E> spliterator() {
1135	<	return new DeqSpliterator<E>(this, -1, -1);
1136	<	}
1137	<
1138	<	public Stream<E> stream() {
1139	<	return Streams.stream(spliterator());
1140	<	}
1141	<
1142	<	public Stream<E> parallelStream() {
1143	<	return Streams.parallelStream(spliterator());
1144	<	}
1145	<
1146	<	static final class DeqSpliterator<E> implements Spliterator<E> {
1147	<	private final ArrayDeque<E> deq;
1148	<	private int fence;  // -1 until first use
1149	<	private int index;  // current index, modified on traverse/split
1150	<
1151	<	/** Creates new spliterator covering the given array and range */
867	<	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
868	<	this.deq = deq;
869	<	this.index = origin;
870	<	this.fence = fence;
871	<	}
872	<
873	<	private int getFence() { // force initialization
874	<	int t;
875	<	if ((t = fence) < 0) {
876	<	t = fence = deq.tail;
877	<	index = deq.head;
878	<	}
879	<	return t;
880	<	}
881	<
882	<	public DeqSpliterator<E> trySplit() {
883	<	int t = getFence(), h = index, n = deq.elements.length;
884	<	if (h != t && ((h + 1) & (n - 1)) != t) {
885	<	if (h > t)
886	<	t += n;
887	<	int m = ((h + t) >>> 1) & (n - 1);
888	<	return new DeqSpliterator<>(deq, h, index = m);
889	<	}
890	<	return null;
891	<	}
892	<
893	<	public void forEach(Consumer<? super E> consumer) {
894	<	if (consumer == null)
895	<	throw new NullPointerException();
896	<	Object[] a = deq.elements;
897	<	int m = a.length - 1, f = getFence(), i = index;
898	<	index = f;
899	<	while (i != f) {
900	<	@SuppressWarnings("unchecked") E e = (E)a[i];
901	<	i = (i + 1) & m;
902	<	if (e == null)
903	<	throw new ConcurrentModificationException();
904	<	consumer.accept(e);
905	<	}
906	<	}
907	<
908	<	public boolean tryAdvance(Consumer<? super E> consumer) {
909	<	if (consumer == null)
910	<	throw new NullPointerException();
911	<	Object[] a = deq.elements;
912	<	int m = a.length - 1, f = getFence(), i = index;
913	<	if (i != fence) {
914	<	@SuppressWarnings("unchecked") E e = (E)a[i];
915	<	index = (i + 1) & m;
916	<	if (e == null)
917	<	throw new ConcurrentModificationException();
918	<	consumer.accept(e);
919	<	return true;
920	<	}
921	<	return false;
922	<	}
923	<
924	<	public long estimateSize() {
925	<	int n = getFence() - index;
926	<	if (n < 0)
927	<	n += deq.elements.length;
928	<	return (long) n;
929	<	}
930	<
931	<	@Override
932	<	public int characteristics() {
933	<	return Spliterator.ORDERED | Spliterator.SIZED |
934	<	Spliterator.NONNULL | Spliterator.SUBSIZED;
1134	>	/** debugging */
1135	>	private void checkInvariants() {
1136	>	try {
1137	>	int capacity = elements.length;
1138	>	assert size >= 0 && size <= capacity;
1139	>	assert head >= 0 && ((capacity == 0 && head == 0 && size == 0)
1140	>	|| head < capacity);
1141	>	assert size == 0
1142	>	|| (elements[head] != null && elements[tail()] != null);
1143	>	assert size == capacity
1144	>	|| (elements[dec(head, capacity)] == null
1145	>	&& elements[inc(tail(), capacity)] == null);
1146	>	} catch (Throwable t) {
1147	>	System.err.printf("head=%d size=%d capacity=%d%n",
1148	>	head, size, elements.length);
1149	>	System.err.printf("elements=%s%n",
1150	>	Arrays.toString(elements));
1151	>	throw t;
1152		}
1153		}
1154

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