ViewVC Help

View File | Revision Log | Show Annotations | Download File | Root Listing

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

Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.42 by jsr166, Wed Jan 16 21:18:50 2013 UTC vs.
Revision 1.109 by jsr166, Sat Nov 5 16:21:06 2016 UTC

#	Line 1 | Line 1
1		/*
2	–	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3	–	*
4	–	* This code is free software; you can redistribute it and/or modify it
5	–	* under the terms of the GNU General Public License version 2 only, as
6	–	* published by the Free Software Foundation.  Oracle designates this
7	–	* particular file as subject to the "Classpath" exception as provided
8	–	* by Oracle in the LICENSE file that accompanied this code.
9	–	*
10	–	* This code is distributed in the hope that it will be useful, but WITHOUT
11	–	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12	–	* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13	–	* version 2 for more details (a copy is included in the LICENSE file that
14	–	* accompanied this code).
15	–	*
16	–	* You should have received a copy of the GNU General Public License version
17	–	* 2 along with this work; if not, write to the Free Software Foundation,
18	–	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19	–	*
20	–	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21	–	* or visit www.oracle.com if you need additional information or have any
22	–	* questions.
23	–	*/
24	–
25	–	/*
26	–	* This file is available under and governed by the GNU General Public
27	–	* License version 2 only, as published by the Free Software Foundation.
28	–	* However, the following notice accompanied the original version of this
29	–	* file:
30	–	*
2		* Written by Josh Bloch of Google Inc. and released to the public domain,
3		* as explained at http://creativecommons.org/publicdomain/zero/1.0/.
4		*/
5
6		package java.util;
7	<	import java.util.Spliterator;
8	<	import java.util.stream.Stream;
9	<	import java.util.stream.Streams;
10	<	import java.util.function.Block;
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 47 | Line 19 | import java.util.function.Block;
19		* {@link Stack} when used as a stack, and faster than {@link LinkedList}
20		* when used as a queue.
21		*
22	<	* <p>Most <tt>ArrayDeque</tt> operations run in amortized constant time.
23	<	* Exceptions include {@link #remove(Object) remove}, {@link
24	<	* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence
25	<	* removeLastOccurrence}, {@link #contains contains}, {@link #iterator
26	<	* iterator.remove()}, and the bulk operations, all of which run in linear
27	<	* time.
22	>	* <p>Most {@code ArrayDeque} operations run in amortized constant time.
23	>	* Exceptions include
24	>	* {@link #remove(Object) remove},
25	>	* {@link #removeFirstOccurrence removeFirstOccurrence},
26	>	* {@link #removeLastOccurrence removeLastOccurrence},
27	>	* {@link #contains contains},
28	>	* {@link #iterator iterator.remove()},
29	>	* and the bulk operations, all of which run in linear time.
30		*
31	<	* <p>The iterators returned by this class's <tt>iterator</tt> method are
32	<	* <i>fail-fast</i>: If the deque is modified at any time after the iterator
33	<	* is created, in any way except through the iterator's own <tt>remove</tt>
34	<	* method, the iterator will generally throw a {@link
31	>	* <p>The iterators returned by this class's {@link #iterator() iterator}
32	>	* method are <em>fail-fast</em>: If the deque is modified at any time after
33	>	* the iterator is created, in any way except through the iterator's own
34	>	* {@code remove} method, the iterator will generally throw a {@link
35		* ConcurrentModificationException}.  Thus, in the face of concurrent
36		* modification, the iterator fails quickly and cleanly, rather than risking
37		* arbitrary, non-deterministic behavior at an undetermined time in the
#	Line 66 | Line 40 | import java.util.function.Block;
40		* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
41		* as it is, generally speaking, impossible to make any hard guarantees in the
42		* presence of unsynchronized concurrent modification.  Fail-fast iterators
43	<	* throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
43	>	* throw {@code ConcurrentModificationException} on a best-effort basis.
44		* Therefore, it would be wrong to write a program that depended on this
45		* exception for its correctness: <i>the fail-fast behavior of iterators
46		* should be used only to detect bugs.</i>
#	Line 80 | Line 54 | import java.util.function.Block;
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
84	–	* @param <E> the type of elements held in this collection
59		*/
60		public class ArrayDeque<E> extends AbstractCollection<E>
61	<	implements Deque<E>, Cloneable, java.io.Serializable
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
93	<	* full, except transiently within an addX method where it is
94	<	* resized (see doubleCapacity) immediately upon becoming full,
95	<	* thus avoiding head and tail wrapping around to equal each
96	<	* other.  We also guarantee that all array cells not holding
97	<	* 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 112 | 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;
119	<
120	<	// ******  Array allocation and resizing utilities ******
101	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
102
103		/**
104	<	* Allocates empty array to hold the given number of elements.
104	>	* Increases the capacity of this deque by at least the given amount.
105		*
106	<	* @param numElements  the number of elements to hold
106	>	* @param needed the required minimum extra capacity; must be positive
107		*/
108	<	private void allocateElements(int numElements) {
109	<	int initialCapacity = MIN_INITIAL_CAPACITY;
110	<	// Find the best power of two to hold elements.
111	<	// Tests "<=" because arrays aren't kept full.
112	<	if (numElements >= initialCapacity) {
113	<	initialCapacity = numElements;
114	<	initialCapacity |= (initialCapacity >>>  1);
115	<	initialCapacity |= (initialCapacity >>>  2);
116	<	initialCapacity |= (initialCapacity >>>  4);
117	<	initialCapacity |= (initialCapacity >>>  8);
118	<	initialCapacity |= (initialCapacity >>> 16);
119	<	initialCapacity++;
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	<	if (initialCapacity < 0)   // Too many elements, must back off
132	<	initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements
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	<	elements = new Object[initialCapacity];
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	<	* Doubles the capacity of this deque.  Call only when full, i.e.,
148	<	* when head and tail have wrapped around to become equal.
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	<	private void doubleCapacity() {
154	<	assert head == tail;
155	<	int p = head;
156	<	int n = elements.length;
157	<	int r = n - p; // number of elements to the right of p
155	<	int newCapacity = n << 1;
156	<	if (newCapacity < 0)
157	<	throw new IllegalStateException("Sorry, deque too big");
158	<	Object[] a = new Object[newCapacity];
159	<	System.arraycopy(elements, p, a, 0, r);
160	<	System.arraycopy(elements, 0, a, r, p);
161	<	elements = a;
162	<	head = 0;
163	<	tail = n;
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	<	* Copies the elements from our element array into the specified array,
168	<	* in order (from first to last element in the deque).  It is assumed
169	<	* that the array is large enough to hold all elements in the deque.
161	>	* Minimizes the internal storage of this collection.
162		*
163	<	* @return its argument
163	>	* @since TBD
164		*/
165	<	private <T> T[] copyElements(T[] a) {
166	<	if (head < tail) {
167	<	System.arraycopy(elements, head, a, 0, size());
168	<	} else if (head > tail) {
169	<	int headPortionLen = elements.length - head;
170	<	System.arraycopy(elements, head, a, 0, headPortionLen);
179	<	System.arraycopy(elements, 0, a, headPortionLen, tail);
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	<	return a;
172	>	// checkInvariants();
173		}
174
175		/**
#	Line 193 | 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 210 | 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 element at array index i.
248	+	* This is a slight abuse of generics, accepted by javac.
249	+	*/
250	+	@SuppressWarnings("unchecked")
251	+	static final <E> E elementAt(Object[] es, int i) {
252	+	return (E) es[i];
253	+	}
254	+
255	+	/**
256	+	* A version of elementAt that checks for null elements.
257	+	* This check doesn't catch all possible comodifications,
258	+	* but does catch ones that corrupt traversal.
259	+	*/
260	+	static final <E> E nonNullElementAt(Object[] es, int i) {
261	+	@SuppressWarnings("unchecked") E e = (E) es[i];
262	+	if (e == null)
263	+	throw new ConcurrentModificationException();
264	+	return e;
265	+	}
266	+
267		// The main insertion and extraction methods are addFirst,
268		// addLast, pollFirst, pollLast. The other methods are defined in
269		// terms of these.
#	Line 227 | Line 277 | public class ArrayDeque<E> extends Abstr
277		public void addFirst(E e) {
278		if (e == null)
279		throw new NullPointerException();
280	<	elements[head = (head - 1) & (elements.length - 1)] = e;
280	>	final Object[] es = elements;
281	>	es[head = dec(head, es.length)] = e;
282		if (head == tail)
283	<	doubleCapacity();
283	>	grow(1);
284	>	// checkInvariants();
285		}
286
287		/**
#	Line 243 | Line 295 | public class ArrayDeque<E> extends Abstr
295		public void addLast(E e) {
296		if (e == null)
297		throw new NullPointerException();
298	<	elements[tail] = e;
299	<	if ( (tail = (tail + 1) & (elements.length - 1)) == head)
300	<	doubleCapacity();
298	>	final Object[] es = elements;
299	>	es[tail] = e;
300	>	if (head == (tail = inc(tail, es.length)))
301	>	grow(1);
302	>	// checkInvariants();
303	>	}
304	>
305	>	/**
306	>	* Adds all of the elements in the specified collection at the end
307	>	* of this deque, as if by calling {@link #addLast} on each one,
308	>	* in the order that they are returned by the collection's
309	>	* iterator.
310	>	*
311	>	* @param c the elements to be inserted into this deque
312	>	* @return {@code true} if this deque changed as a result of the call
313	>	* @throws NullPointerException if the specified collection or any
314	>	*         of its elements are null
315	>	*/
316	>	public boolean addAll(Collection<? extends E> c) {
317	>	final int s = size(), needed;
318	>	if ((needed = s + c.size() - elements.length + 1) > 0)
319	>	grow(needed);
320	>	c.forEach((e) -> addLast(e));
321	>	// checkInvariants();
322	>	return size() > s;
323		}
324
325		/**
#	Line 276 | Line 350 | public class ArrayDeque<E> extends Abstr
350		* @throws NoSuchElementException {@inheritDoc}
351		*/
352		public E removeFirst() {
353	<	E x = pollFirst();
354	<	if (x == null)
353	>	E e = pollFirst();
354	>	if (e == null)
355		throw new NoSuchElementException();
356	<	return x;
356	>	// checkInvariants();
357	>	return e;
358		}
359
360		/**
361		* @throws NoSuchElementException {@inheritDoc}
362		*/
363		public E removeLast() {
364	<	E x = pollLast();
365	<	if (x == null)
364	>	E e = pollLast();
365	>	if (e == null)
366		throw new NoSuchElementException();
367	<	return x;
367	>	// checkInvariants();
368	>	return e;
369		}
370
371		public E pollFirst() {
372	<	int h = head;
373	<	@SuppressWarnings("unchecked")
374	<	E result = (E) elements[h];
375	<	// Element is null if deque empty
376	<	if (result == null)
377	<	return null;
378	<	elements[h] = null;     // Must null out slot
379	<	head = (h + 1) & (elements.length - 1);
380	<	return result;
372	>	final Object[] es;
373	>	final int h;
374	>	E e = elementAt(es = elements, h = head);
375	>	if (e != null) {
376	>	es[h] = null;
377	>	head = inc(h, es.length);
378	>	}
379	>	// checkInvariants();
380	>	return e;
381		}
382
383		public E pollLast() {
384	<	int t = (tail - 1) & (elements.length - 1);
385	<	@SuppressWarnings("unchecked")
386	<	E result = (E) elements[t];
387	<	if (result == null)
388	<	return null;
389	<	elements[t] = null;
390	<	tail = t;
315	<	return result;
384	>	final Object[] es;
385	>	final int t;
386	>	E e = elementAt(es = elements, t = dec(tail, es.length));
387	>	if (e != null)
388	>	es[tail = t] = null;
389	>	// checkInvariants();
390	>	return e;
391		}
392
393		/**
394		* @throws NoSuchElementException {@inheritDoc}
395		*/
396		public E getFirst() {
397	<	@SuppressWarnings("unchecked")
398	<	E result = (E) elements[head];
324	<	if (result == null)
397	>	E e = elementAt(elements, head);
398	>	if (e == null)
399		throw new NoSuchElementException();
400	<	return result;
400	>	// checkInvariants();
401	>	return e;
402		}
403
404		/**
405		* @throws NoSuchElementException {@inheritDoc}
406		*/
407		public E getLast() {
408	<	@SuppressWarnings("unchecked")
409	<	E result = (E) elements[(tail - 1) & (elements.length - 1)];
410	<	if (result == null)
408	>	final Object[] es = elements;
409	>	E e = elementAt(es, dec(tail, es.length));
410	>	if (e == null)
411		throw new NoSuchElementException();
412	<	return result;
412	>	// checkInvariants();
413	>	return e;
414		}
415
340	–	@SuppressWarnings("unchecked")
416		public E peekFirst() {
417	<	// elements[head] is null if deque empty
418	<	return (E) elements[head];
417	>	// checkInvariants();
418	>	return elementAt(elements, head);
419		}
420
346	–	@SuppressWarnings("unchecked")
421		public E peekLast() {
422	<	return (E) elements[(tail - 1) & (elements.length - 1)];
422	>	// checkInvariants();
423	>	final Object[] es;
424	>	return elementAt(es = elements, dec(tail, es.length));
425		}
426
427		/**
#	Line 361 | Line 437 | public class ArrayDeque<E> extends Abstr
437		* @return {@code true} if the deque contained the specified element
438		*/
439		public boolean removeFirstOccurrence(Object o) {
440	<	if (o == null)
441	<	return false;
442	<	int mask = elements.length - 1;
443	<	int i = head;
444	<	Object x;
445	<	while ( (x = elements[i]) != null) {
446	<	if (o.equals(x)) {
447	<	delete(i);
448	<	return true;
440	>	if (o != null) {
441	>	final Object[] es = elements;
442	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
443	>	; i = 0, to = end) {
444	>	for (; i < to; i++)
445	>	if (o.equals(es[i])) {
446	>	delete(i);
447	>	return true;
448	>	}
449	>	if (to == end) break;
450		}
374	–	i = (i + 1) & mask;
451		}
452		return false;
453		}
#	Line 389 | Line 465 | public class ArrayDeque<E> extends Abstr
465		* @return {@code true} if the deque contained the specified element
466		*/
467		public boolean removeLastOccurrence(Object o) {
468	<	if (o == null)
469	<	return false;
470	<	int mask = elements.length - 1;
471	<	int i = (tail - 1) & mask;
472	<	Object x;
473	<	while ( (x = elements[i]) != null) {
474	<	if (o.equals(x)) {
475	<	delete(i);
476	<	return true;
468	>	if (o != null) {
469	>	final Object[] es = elements;
470	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
471	>	; i = es.length, to = end) {
472	>	while (--i >= to)
473	>	if (o.equals(es[i])) {
474	>	delete(i);
475	>	return true;
476	>	}
477	>	if (to == end) break;
478		}
402	–	i = (i - 1) & mask;
479		}
480		return false;
481		}
#	Line 518 | Line 594 | public class ArrayDeque<E> extends Abstr
594		return removeFirst();
595		}
596
521	–	private void checkInvariants() {
522	–	assert elements[tail] == null;
523	–	assert head == tail ? elements[head] == null :
524	–	(elements[head] != null &&
525	–	elements[(tail - 1) & (elements.length - 1)] != null);
526	–	assert elements[(head - 1) & (elements.length - 1)] == null;
527	–	}
528	–
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
605	>	* @return true if elements near tail moved backwards
606		*/
607	<	private boolean delete(int i) {
608	<	checkInvariants();
609	<	final Object[] elements = this.elements;
610	<	final int mask = elements.length - 1;
607	>	boolean delete(int i) {
608	>	// checkInvariants();
609	>	final Object[] es = elements;
610	>	final int capacity = es.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;
547	<
548	<	// Invariant: head <= i < tail mod circularity
549	<	if (front >= ((t - h) & mask))
550	<	throw new ConcurrentModificationException();
551	<
552	<	// Optimize for least element motion
612	>	// number of elements before to-be-deleted elt
613	>	final int front = sub(i, h, 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);
618	>	System.arraycopy(es, h, es, 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);
620	>	System.arraycopy(es, 0, es, 1, i);
621	>	es[0] = es[capacity - 1];
622	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
623		}
624	<	elements[h] = null;
625	<	head = (h + 1) & mask;
624	>	es[h] = null;
625	>	head = inc(h, capacity);
626	>	// checkInvariants();
627		return false;
628		} else {
629	<	if (i < t) { // Copy the null tail as well
630	<	System.arraycopy(elements, i + 1, elements, i, back);
631	<	tail = t - 1;
629	>	// move back elements backwards
630	>	tail = dec(tail, capacity);
631	>	if (i <= tail) {
632	>	System.arraycopy(es, i + 1, es, i, back);
633		} else { // Wrap around
634	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
635	<	elements[mask] = elements[0];
636	<	System.arraycopy(elements, 1, elements, 0, t);
637	<	tail = (t - 1) & mask;
634	>	int firstLeg = capacity - (i + 1);
635	>	System.arraycopy(es, i + 1, es, i, firstLeg);
636	>	es[capacity - 1] = es[0];
637	>	System.arraycopy(es, 1, es, 0, back - firstLeg - 1);
638		}
639	+	es[tail] = null;
640	+	// checkInvariants();
641		return true;
642		}
643		}
#	Line 583 | Line 650 | public class ArrayDeque<E> extends Abstr
650		* @return the number of elements in this deque
651		*/
652		public int size() {
653	<	return (tail - head) & (elements.length - 1);
653	>	return sub(tail, head, elements.length);
654		}
655
656		/**
#	Line 612 | Line 679 | public class ArrayDeque<E> extends Abstr
679		}
680
681		private class DeqIterator implements Iterator<E> {
682	<	/**
683	<	* Index of element to be returned by subsequent call to next.
617	<	*/
618	<	private int cursor = head;
682	>	/** Index of element to be returned by subsequent call to next. */
683	>	int cursor;
684
685	<	/**
686	<	* Tail recorded at construction (also in remove), to stop
622	<	* iterator and also to check for comodification.
623	<	*/
624	<	private int fence = tail;
685	>	/** Number of elements yet to be returned. */
686	>	int remaining = size();
687
688		/**
689		* Index of element returned by most recent call to next.
690		* Reset to -1 if element is deleted by a call to remove.
691		*/
692	<	private int lastRet = -1;
692	>	int lastRet = -1;
693	>
694	>	DeqIterator() { cursor = head; }
695
696	<	public boolean hasNext() {
697	<	return cursor != fence;
696	>	public final boolean hasNext() {
697	>	return remaining > 0;
698		}
699
700		public E next() {
701	<	if (cursor == fence)
701	>	if (remaining <= 0)
702		throw new NoSuchElementException();
703	<	@SuppressWarnings("unchecked")
704	<	E result = (E) elements[cursor];
641	<	// This check doesn't catch all possible comodifications,
642	<	// but does catch the ones that corrupt traversal
643	<	if (tail != fence || result == null)
644	<	throw new ConcurrentModificationException();
703	>	final Object[] es = elements;
704	>	E e = nonNullElementAt(es, cursor);
705		lastRet = cursor;
706	<	cursor = (cursor + 1) & (elements.length - 1);
707	<	return result;
706	>	cursor = inc(cursor, es.length);
707	>	remaining--;
708	>	return e;
709	>	}
710	>
711	>	void postDelete(boolean leftShifted) {
712	>	if (leftShifted)
713	>	cursor = dec(cursor, elements.length);
714		}
715
716	<	public void remove() {
716	>	public final void remove() {
717		if (lastRet < 0)
718		throw new IllegalStateException();
719	<	if (delete(lastRet)) { // if left-shifted, undo increment in next()
654	<	cursor = (cursor - 1) & (elements.length - 1);
655	<	fence = tail;
656	<	}
719	>	postDelete(delete(lastRet));
720		lastRet = -1;
721		}
659	–	}
722
723	<	private class DescendingIterator implements Iterator<E> {
724	<	/*
725	<	* This class is nearly a mirror-image of DeqIterator, using
726	<	* tail instead of head for initial cursor, and head instead of
727	<	* tail for fence.
728	<	*/
729	<	private int cursor = tail;
730	<	private int fence = head;
731	<	private int lastRet = -1;
732	<
733	<	public boolean hasNext() {
734	<	return cursor != fence;
723	>	public void forEachRemaining(Consumer<? super E> action) {
724	>	Objects.requireNonNull(action);
725	>	int r;
726	>	if ((r = remaining) <= 0)
727	>	return;
728	>	remaining = 0;
729	>	final Object[] es = elements;
730	>	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
731	>	throw new ConcurrentModificationException();
732	>	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
733	>	; i = 0, to = end) {
734	>	for (; i < to; i++)
735	>	action.accept(elementAt(es, i));
736	>	if (to == end) {
737	>	if (end != tail)
738	>	throw new ConcurrentModificationException();
739	>	lastRet = dec(end, es.length);
740	>	break;
741	>	}
742	>	}
743		}
744	+	}
745
746	<	public E next() {
747	<	if (cursor == fence)
746	>	private class DescendingIterator extends DeqIterator {
747	>	DescendingIterator() { cursor = dec(tail, elements.length); }
748	>
749	>	public final E next() {
750	>	if (remaining <= 0)
751		throw new NoSuchElementException();
752	<	cursor = (cursor - 1) & (elements.length - 1);
753	<	@SuppressWarnings("unchecked")
680	<	E result = (E) elements[cursor];
681	<	if (head != fence || result == null)
682	<	throw new ConcurrentModificationException();
752	>	final Object[] es = elements;
753	>	E e = nonNullElementAt(es, cursor);
754		lastRet = cursor;
755	<	return result;
755	>	cursor = dec(cursor, es.length);
756	>	remaining--;
757	>	return e;
758	>	}
759	>
760	>	void postDelete(boolean leftShifted) {
761	>	if (!leftShifted)
762	>	cursor = inc(cursor, elements.length);
763	>	}
764	>
765	>	public final void forEachRemaining(Consumer<? super E> action) {
766	>	Objects.requireNonNull(action);
767	>	int r;
768	>	if ((r = remaining) <= 0)
769	>	return;
770	>	remaining = 0;
771	>	final Object[] es = elements;
772	>	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
773	>	throw new ConcurrentModificationException();
774	>	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
775	>	; i = es.length - 1, to = end) {
776	>	for (; i >= to; i--)
777	>	action.accept(elementAt(es, i));
778	>	if (to == end) {
779	>	if (end != head)
780	>	throw new ConcurrentModificationException();
781	>	lastRet = head;
782	>	break;
783	>	}
784	>	}
785		}
786	+	}
787
788	<	public void remove() {
789	<	if (lastRet < 0)
790	<	throw new IllegalStateException();
791	<	if (!delete(lastRet)) {
792	<	cursor = (cursor + 1) & (elements.length - 1);
793	<	fence = head;
788	>	/**
789	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
790	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
791	>	* deque.
792	>	*
793	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
794	>	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
795	>	* {@link Spliterator#NONNULL}.  Overriding implementations should document
796	>	* the reporting of additional characteristic values.
797	>	*
798	>	* @return a {@code Spliterator} over the elements in this deque
799	>	* @since 1.8
800	>	*/
801	>	public Spliterator<E> spliterator() {
802	>	return new DeqSpliterator();
803	>	}
804	>
805	>	final class DeqSpliterator implements Spliterator<E> {
806	>	private int fence;      // -1 until first use
807	>	private int cursor;     // current index, modified on traverse/split
808	>
809	>	/** Constructs late-binding spliterator over all elements. */
810	>	DeqSpliterator() {
811	>	this.fence = -1;
812	>	}
813	>
814	>	/** Constructs spliterator over the given range. */
815	>	DeqSpliterator(int origin, int fence) {
816	>	this.cursor = origin;
817	>	this.fence = fence;
818	>	}
819	>
820	>	/** Ensures late-binding initialization; then returns fence. */
821	>	private int getFence() { // force initialization
822	>	int t;
823	>	if ((t = fence) < 0) {
824	>	t = fence = tail;
825	>	cursor = head;
826		}
827	<	lastRet = -1;
827	>	return t;
828	>	}
829	>
830	>	public DeqSpliterator trySplit() {
831	>	final Object[] es = elements;
832	>	final int i, n;
833	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
834	>	? null
835	>	: new DeqSpliterator(i, cursor = add(i, n, es.length));
836	>	}
837	>
838	>	public void forEachRemaining(Consumer<? super E> action) {
839	>	if (action == null)
840	>	throw new NullPointerException();
841	>	final int end = getFence(), cursor = this.cursor;
842	>	final Object[] es = elements;
843	>	if (cursor != end) {
844	>	this.cursor = end;
845	>	// null check at both ends of range is sufficient
846	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
847	>	throw new ConcurrentModificationException();
848	>	for (int i = cursor, to = (i <= end) ? end : es.length;
849	>	; i = 0, to = end) {
850	>	for (; i < to; i++)
851	>	action.accept(elementAt(es, i));
852	>	if (to == end) break;
853	>	}
854	>	}
855	>	}
856	>
857	>	public boolean tryAdvance(Consumer<? super E> action) {
858	>	if (action == null)
859	>	throw new NullPointerException();
860	>	int t, i;
861	>	if ((t = fence) < 0) t = getFence();
862	>	if (t == (i = cursor))
863	>	return false;
864	>	final Object[] es;
865	>	action.accept(nonNullElementAt(es = elements, i));
866	>	cursor = inc(i, es.length);
867	>	return true;
868	>	}
869	>
870	>	public long estimateSize() {
871	>	return sub(getFence(), cursor, elements.length);
872	>	}
873	>
874	>	public int characteristics() {
875	>	return Spliterator.NONNULL
876	>	| Spliterator.ORDERED
877	>	| Spliterator.SIZED
878	>	| Spliterator.SUBSIZED;
879	>	}
880	>	}
881	>
882	>	public void forEach(Consumer<? super E> action) {
883	>	Objects.requireNonNull(action);
884	>	final Object[] es = elements;
885	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
886	>	; i = 0, to = end) {
887	>	for (; i < to; i++)
888	>	action.accept(elementAt(es, i));
889	>	if (to == end) {
890	>	if (end != tail) throw new ConcurrentModificationException();
891	>	break;
892	>	}
893	>	}
894	>	// checkInvariants();
895	>	}
896	>
897	>	/**
898	>	* Replaces each element of this deque with the result of applying the
899	>	* operator to that element, as specified by {@link List#replaceAll}.
900	>	*
901	>	* @param operator the operator to apply to each element
902	>	* @since TBD
903	>	*/
904	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
905	>	Objects.requireNonNull(operator);
906	>	final Object[] es = elements;
907	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
908	>	; i = 0, to = end) {
909	>	for (; i < to; i++)
910	>	es[i] = operator.apply(elementAt(es, i));
911	>	if (to == end) {
912	>	if (end != tail) throw new ConcurrentModificationException();
913	>	break;
914	>	}
915	>	}
916	>	// checkInvariants();
917	>	}
918	>
919	>	/**
920	>	* @throws NullPointerException {@inheritDoc}
921	>	*/
922	>	public boolean removeIf(Predicate<? super E> filter) {
923	>	Objects.requireNonNull(filter);
924	>	return bulkRemove(filter);
925	>	}
926	>
927	>	/**
928	>	* @throws NullPointerException {@inheritDoc}
929	>	*/
930	>	public boolean removeAll(Collection<?> c) {
931	>	Objects.requireNonNull(c);
932	>	return bulkRemove(e -> c.contains(e));
933	>	}
934	>
935	>	/**
936	>	* @throws NullPointerException {@inheritDoc}
937	>	*/
938	>	public boolean retainAll(Collection<?> c) {
939	>	Objects.requireNonNull(c);
940	>	return bulkRemove(e -> !c.contains(e));
941	>	}
942	>
943	>	/** Implementation of bulk remove methods. */
944	>	private boolean bulkRemove(Predicate<? super E> filter) {
945	>	// checkInvariants();
946	>	final Object[] es = elements;
947	>	// Optimize for initial run of survivors
948	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
949	>	; i = 0, to = end) {
950	>	for (; i < to; i++)
951	>	if (filter.test(elementAt(es, i)))
952	>	return bulkRemoveModified(filter, i, to);
953	>	if (to == end) {
954	>	if (end != tail) throw new ConcurrentModificationException();
955	>	break;
956	>	}
957	>	}
958	>	return false;
959	>	}
960	>
961	>	/**
962	>	* Helper for bulkRemove, in case of at least one deletion.
963	>	* @param i valid index of first element to be deleted
964	>	*/
965	>	private boolean bulkRemoveModified(
966	>	Predicate<? super E> filter, int i, int to) {
967	>	final Object[] es = elements;
968	>	final int capacity = es.length;
969	>	// a two-finger algorithm, with hare i reading, tortoise j writing
970	>	int j = i++;
971	>	final int end = tail;
972	>	try {
973	>	for (;; j = 0) {    // j rejoins i on second leg
974	>	E e;
975	>	// In this loop, i and j are on the same leg, with i > j
976	>	for (; i < to; i++)
977	>	if (!filter.test(e = elementAt(es, i)))
978	>	es[j++] = e;
979	>	if (to == end) break;
980	>	// In this loop, j is on the first leg, i on the second
981	>	for (i = 0, to = end; i < to && j < capacity; i++)
982	>	if (!filter.test(e = elementAt(es, i)))
983	>	es[j++] = e;
984	>	if (i >= to) {
985	>	if (j == capacity) j = 0; // "corner" case
986	>	break;
987	>	}
988	>	}
989	>	return true;
990	>	} catch (Throwable ex) {
991	>	// copy remaining elements
992	>	for (; i != end; i = inc(i, capacity), j = inc(j, capacity))
993	>	es[j] = es[i];
994	>	throw ex;
995	>	} finally {
996	>	if (end != tail) throw new ConcurrentModificationException();
997	>	circularClear(es, tail = j, end);
998	>	// checkInvariants();
999		}
1000		}
1001
#	Line 704 | Line 1008 | public class ArrayDeque<E> extends Abstr
1008		* @return {@code true} if this deque contains the specified element
1009		*/
1010		public boolean contains(Object o) {
1011	<	if (o == null)
1012	<	return false;
1013	<	int mask = elements.length - 1;
1014	<	int i = head;
1015	<	Object x;
1016	<	while ( (x = elements[i]) != null) {
1017	<	if (o.equals(x))
1018	<	return true;
1019	<	i = (i + 1) & mask;
1011	>	if (o != null) {
1012	>	final Object[] es = elements;
1013	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1014	>	; i = 0, to = end) {
1015	>	for (; i < to; i++)
1016	>	if (o.equals(es[i]))
1017	>	return true;
1018	>	if (to == end) break;
1019	>	}
1020		}
1021		return false;
1022		}
#	Line 725 | Line 1029 | public class ArrayDeque<E> extends Abstr
1029		* Returns {@code true} if this deque contained the specified element
1030		* (or equivalently, if this deque changed as a result of the call).
1031		*
1032	<	* <p>This method is equivalent to {@link #removeFirstOccurrence}.
1032	>	* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}.
1033		*
1034		* @param o element to be removed from this deque, if present
1035		* @return {@code true} if this deque contained the specified element
#	Line 739 | Line 1043 | public class ArrayDeque<E> extends Abstr
1043		* The deque will be empty after this call returns.
1044		*/
1045		public void clear() {
1046	<	int h = head;
1047	<	int t = tail;
1048	<	if (h != t) { // clear all cells
1049	<	head = tail = 0;
1050	<	int i = h;
1051	<	int mask = elements.length - 1;
1052	<	do {
1053	<	elements[i] = null;
1054	<	i = (i + 1) & mask;
1055	<	} while (i != t);
1046	>	circularClear(elements, head, tail);
1047	>	head = tail = 0;
1048	>	// checkInvariants();
1049	>	}
1050	>
1051	>	/**
1052	>	* Nulls out slots starting at array index i, upto index end.
1053	>	*/
1054	>	private static void circularClear(Object[] es, int i, int end) {
1055	>	for (int to = (i <= end) ? end : es.length;
1056	>	; i = 0, to = end) {
1057	>	Arrays.fill(es, i, to, null);
1058	>	if (to == end) break;
1059		}
1060		}
1061
#	Line 766 | Line 1073 | public class ArrayDeque<E> extends Abstr
1073		* @return an array containing all of the elements in this deque
1074		*/
1075		public Object[] toArray() {
1076	<	return copyElements(new Object[size()]);
1076	>	return toArray(Object[].class);
1077	>	}
1078	>
1079	>	private <T> T[] toArray(Class<T[]> klazz) {
1080	>	final Object[] es = elements;
1081	>	final T[] a;
1082	>	final int size = size(), head = this.head, end;
1083	>	final int len = Math.min(size, es.length - head);
1084	>	if ((end = head + size) >= 0) {
1085	>	a = Arrays.copyOfRange(es, head, end, klazz);
1086	>	} else {
1087	>	// integer overflow!
1088	>	a = Arrays.copyOfRange(es, 0, size, klazz);
1089	>	System.arraycopy(es, head, a, 0, len);
1090	>	}
1091	>	if (tail < head)
1092	>	System.arraycopy(es, 0, a, len, tail);
1093	>	return a;
1094		}
1095
1096		/**
#	Line 791 | Line 1115 | public class ArrayDeque<E> extends Abstr
1115		* The following code can be used to dump the deque into a newly
1116		* allocated array of {@code String}:
1117		*
1118	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
1118	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
1119		*
1120		* Note that {@code toArray(new Object[0])} is identical in function to
1121		* {@code toArray()}.
#	Line 807 | Line 1131 | public class ArrayDeque<E> extends Abstr
1131		*/
1132		@SuppressWarnings("unchecked")
1133		public <T> T[] toArray(T[] a) {
1134	<	int size = size();
1135	<	if (a.length < size)
1136	<	a = (T[])java.lang.reflect.Array.newInstance(
1137	<	a.getClass().getComponentType(), size);
1138	<	copyElements(a);
1139	<	if (a.length > size)
1134	>	final int size;
1135	>	if ((size = size()) > a.length)
1136	>	return toArray((Class<T[]>) a.getClass());
1137	>	final Object[] es = elements;
1138	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1139	>	; i = 0, len = tail) {
1140	>	System.arraycopy(es, i, a, j, len);
1141	>	if ((j += len) == size) break;
1142	>	}
1143	>	if (size < a.length)
1144		a[size] = null;
1145		return a;
1146		}
#	Line 840 | Line 1168 | public class ArrayDeque<E> extends Abstr
1168		/**
1169		* Saves this deque to a stream (that is, serializes it).
1170		*
1171	+	* @param s the stream
1172	+	* @throws java.io.IOException if an I/O error occurs
1173		* @serialData The current size ({@code int}) of the deque,
1174		* followed by all of its elements (each an object reference) in
1175		* first-to-last order.
#	Line 852 | Line 1182 | public class ArrayDeque<E> extends Abstr
1182		s.writeInt(size());
1183
1184		// Write out elements in order.
1185	<	int mask = elements.length - 1;
1186	<	for (int i = head; i != tail; i = (i + 1) & mask)
1187	<	s.writeObject(elements[i]);
1185	>	final Object[] es = elements;
1186	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1187	>	; i = 0, to = end) {
1188	>	for (; i < to; i++)
1189	>	s.writeObject(es[i]);
1190	>	if (to == end) break;
1191	>	}
1192		}
1193
1194		/**
1195		* Reconstitutes this deque from a stream (that is, deserializes it).
1196	+	* @param s the stream
1197	+	* @throws ClassNotFoundException if the class of a serialized object
1198	+	*         could not be found
1199	+	* @throws java.io.IOException if an I/O error occurs
1200		*/
1201		private void readObject(java.io.ObjectInputStream s)
1202		throws java.io.IOException, ClassNotFoundException {
#	Line 866 | Line 1204 | public class ArrayDeque<E> extends Abstr
1204
1205		// Read in size and allocate array
1206		int size = s.readInt();
1207	<	allocateElements(size);
1208	<	head = 0;
871	<	tail = size;
1207	>	elements = new Object[size + 1];
1208	>	this.tail = size;
1209
1210		// Read in all elements in the proper order.
1211		for (int i = 0; i < size; i++)
1212		elements[i] = s.readObject();
1213		}
1214
1215	<	public Stream<E> stream() {
1216	<	int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED;
1217	<	return Streams.stream
1218	<	(() -> new DeqSpliterator<E>(this, head, tail), flags);
1219	<	}
1220	<	public Stream<E> parallelStream() {
1221	<	int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED;
1222	<	return Streams.parallelStream
1223	<	(() -> new DeqSpliterator<E>(this, head, tail), flags);
1224	<	}
1225	<
1226	<
1227	<	static final class DeqSpliterator<E> implements Spliterator<E>, Iterator<E> {
1228	<	private final ArrayDeque<E> deq;
1229	<	private final Object[] array;
1230	<	private final int fence;  // initially tail
1231	<	private int index;        // current index, modified on traverse/split
895	<
896	<	/** Create new spliterator covering the given array and range */
897	<	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
898	<	this.deq = deq; this.array = deq.elements;
899	<	this.index = origin; this.fence = fence;
900	<	}
901	<
902	<	public DeqSpliterator<E> trySplit() {
903	<	int n = array.length;
904	<	int h = index, t = fence;
905	<	if (h != t && ((h + 1) & (n - 1)) != t) {
906	<	if (h > t)
907	<	t += n;
908	<	int m = ((h + t) >>> 1) & (n - 1);
909	<	return new DeqSpliterator<E>(deq, h, index = m);
910	<	}
911	<	return null;
912	<	}
913	<
914	<	@SuppressWarnings("unchecked")
915	<	public void forEach(Block<? super E> block) {
916	<	if (block == null)
917	<	throw new NullPointerException();
918	<	Object[] a = array;
919	<	if (a != deq.elements)
920	<	throw new ConcurrentModificationException();
921	<	int m = a.length - 1, f = fence, i = index;
922	<	index = f;
923	<	while (i != f) {
924	<	Object e = a[i];
925	<	if (e == null)
926	<	throw new ConcurrentModificationException();
927	<	block.accept((E)e);
928	<	i = (i + 1) & m;
929	<	}
930	<	}
931	<
932	<	@SuppressWarnings("unchecked")
933	<	public boolean tryAdvance(Block<? super E> block) {
934	<	if (block == null)
935	<	throw new NullPointerException();
936	<	Object[] a = array;
937	<	if (a != deq.elements)
938	<	throw new ConcurrentModificationException();
939	<	int m = a.length - 1, i = index;
940	<	if (i != fence) {
941	<	Object e = a[i];
942	<	if (e == null)
943	<	throw new ConcurrentModificationException();
944	<	block.accept((E)e);
945	<	index = (i + 1) & m;
946	<	return true;
947	<	}
948	<	return false;
949	<	}
950	<
951	<	// Iterator support
952	<	public Iterator<E> iterator() {
953	<	return this;
954	<	}
955	<
956	<	public boolean hasNext() {
957	<	return index >= 0 && index != fence;
958	<	}
959	<
960	<	@SuppressWarnings("unchecked")
961	<	public E next() {
962	<	if (index < 0 || index == fence)
963	<	throw new NoSuchElementException();
964	<	Object[] a = array;
965	<	if (a != deq.elements)
966	<	throw new ConcurrentModificationException();
967	<	Object e = a[index];
968	<	if (e == null)
969	<	throw new ConcurrentModificationException();
970	<	index = (index + 1) & (a.length - 1);
971	<	return (E) e;
972	<	}
973	<
974	<	public void remove() { throw new UnsupportedOperationException(); }
975	<
976	<	// Other spliterator methods
977	<	public long estimateSize() {
978	<	int n = fence - index;
979	<	if (n < 0)
980	<	n += array.length;
981	<	return (long)n;
1215	>	/** debugging */
1216	>	void checkInvariants() {
1217	>	try {
1218	>	int capacity = elements.length;
1219	>	// assert head >= 0 && head < capacity;
1220	>	// assert tail >= 0 && tail < capacity;
1221	>	// assert capacity > 0;
1222	>	// assert size() < capacity;
1223	>	// assert head == tail || elements[head] != null;
1224	>	// assert elements[tail] == null;
1225	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1226	>	} catch (Throwable t) {
1227	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1228	>	head, tail, elements.length);
1229	>	System.err.printf("elements=%s%n",
1230	>	Arrays.toString(elements));
1231	>	throw t;
1232		}
983	–	public boolean hasExactSize() { return true; }
984	–	public boolean hasExactSplits() { return true; }
1233		}
1234
1235		}

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines