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

Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.27 by jsr166, Tue Feb 7 20:54:24 2006 UTC vs.
Revision 1.55 by jsr166, Thu May 2 06:02:17 2013 UTC

#	Line 1 | Line 1
1		/*
2		* Written by Josh Bloch of Google Inc. and released to the public domain,
3	<	* as explained at http://creativecommons.org/licenses/publicdomain.
3	>	* as explained at http://creativecommons.org/publicdomain/zero/1.0/.
4		*/
5
6		package java.util;
7	<	import java.io.*;
7	>	import java.io.Serializable;
8	>	import java.util.function.Consumer;
9	>	import java.util.stream.Stream;
10
11		/**
12		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 15 | Line 17 | import java.io.*;
17		* {@link Stack} when used as a stack, and faster than {@link LinkedList}
18		* when used as a queue.
19		*
20	<	* <p>Most <tt>ArrayDeque</tt> operations run in amortized constant time.
21	<	* Exceptions include {@link #remove(Object) remove}, {@link
22	<	* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence
23	<	* removeLastOccurrence}, {@link #contains contains}, {@link #iterator
24	<	* iterator.remove()}, and the bulk operations, all of which run in linear
25	<	* time.
20	>	* <p>Most {@code ArrayDeque} operations run in amortized constant time.
21	>	* Exceptions include
22	>	* {@link #remove(Object) remove},
23	>	* {@link #removeFirstOccurrence removeFirstOccurrence},
24	>	* {@link #removeLastOccurrence removeLastOccurrence},
25	>	* {@link #contains contains},
26	>	* {@link #iterator iterator.remove()},
27	>	* and the bulk operations, all of which run in linear time.
28		*
29	<	* <p>The iterators returned by this class's <tt>iterator</tt> method are
30	<	* <i>fail-fast</i>: If the deque is modified at any time after the iterator
31	<	* is created, in any way except through the iterator's own <tt>remove</tt>
32	<	* method, the iterator will generally throw a {@link
29	>	* <p>The iterators returned by this class's {@link #iterator() iterator}
30	>	* method are <em>fail-fast</em>: If the deque is modified at any time after
31	>	* the iterator is created, in any way except through the iterator's own
32	>	* {@code remove} method, the iterator will generally throw a {@link
33		* ConcurrentModificationException}.  Thus, in the face of concurrent
34		* modification, the iterator fails quickly and cleanly, rather than risking
35		* arbitrary, non-deterministic behavior at an undetermined time in the
#	Line 34 | Line 38 | import java.io.*;
38		* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
39		* as it is, generally speaking, impossible to make any hard guarantees in the
40		* presence of unsynchronized concurrent modification.  Fail-fast iterators
41	<	* throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
41	>	* throw {@code ConcurrentModificationException} on a best-effort basis.
42		* Therefore, it would be wrong to write a program that depended on this
43		* exception for its correctness: <i>the fail-fast behavior of iterators
44		* should be used only to detect bugs.</i>
#	Line 44 | Line 48 | import java.io.*;
48		* Iterator} interfaces.
49		*
50		* <p>This class is a member of the
51	<	* <a href="{@docRoot}/../guide/collections/index.html">
51	>	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
52		* Java Collections Framework</a>.
53		*
54		* @author  Josh Bloch and Doug Lea
#	Line 64 | Line 68 | public class ArrayDeque<E> extends Abstr
68		* other.  We also guarantee that all array cells not holding
69		* deque elements are always null.
70		*/
71	<	private transient E[] elements;
71	>	transient Object[] elements; // non-private to simplify nested class access
72
73		/**
74		* The index of the element at the head of the deque (which is the
75		* element that would be removed by remove() or pop()); or an
76		* arbitrary number equal to tail if the deque is empty.
77		*/
78	<	private transient int head;
78	>	transient int head;
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)).
83		*/
84	<	private transient int tail;
84	>	transient int tail;
85
86		/**
87		* The minimum capacity that we'll use for a newly created deque.
#	Line 88 | Line 92 | public class ArrayDeque<E> extends Abstr
92		// ******  Array allocation and resizing utilities ******
93
94		/**
95	<	* Allocate empty array to hold the given number of elements.
95	>	* Allocates empty array to hold the given number of elements.
96		*
97		* @param numElements  the number of elements to hold
98		*/
#	Line 108 | Line 112 | public class ArrayDeque<E> extends Abstr
112		if (initialCapacity < 0)   // Too many elements, must back off
113		initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements
114		}
115	<	elements = (E[]) new Object[initialCapacity];
115	>	elements = new Object[initialCapacity];
116		}
117
118		/**
119	<	* Double the capacity of this deque.  Call only when full, i.e.,
119	>	* Doubles the capacity of this deque.  Call only when full, i.e.,
120		* when head and tail have wrapped around to become equal.
121		*/
122		private void doubleCapacity() {
#	Line 126 | Line 130 | public class ArrayDeque<E> extends Abstr
130		Object[] a = new Object[newCapacity];
131		System.arraycopy(elements, p, a, 0, r);
132		System.arraycopy(elements, 0, a, r, p);
133	<	elements = (E[])a;
133	>	elements = a;
134		head = 0;
135		tail = n;
136		}
137
138		/**
135	–	* Copies the elements from our element array into the specified array,
136	–	* in order (from first to last element in the deque).  It is assumed
137	–	* that the array is large enough to hold all elements in the deque.
138	–	*
139	–	* @return its argument
140	–	*/
141	–	private <T> T[] copyElements(T[] a) {
142	–	if (head < tail) {
143	–	System.arraycopy(elements, head, a, 0, size());
144	–	} else if (head > tail) {
145	–	int headPortionLen = elements.length - head;
146	–	System.arraycopy(elements, head, a, 0, headPortionLen);
147	–	System.arraycopy(elements, 0, a, headPortionLen, tail);
148	–	}
149	–	return a;
150	–	}
151	–
152	–	/**
139		* Constructs an empty array deque with an initial capacity
140		* sufficient to hold 16 elements.
141		*/
142		public ArrayDeque() {
143	<	elements = (E[]) new Object[16];
143	>	elements = new Object[16];
144		}
145
146		/**
#	Line 220 | Line 206 | public class ArrayDeque<E> extends Abstr
206		* Inserts the specified element at the front of this deque.
207		*
208		* @param e the element to add
209	<	* @return <tt>true</tt> (as specified by {@link Deque#offerFirst})
209	>	* @return {@code true} (as specified by {@link Deque#offerFirst})
210		* @throws NullPointerException if the specified element is null
211		*/
212		public boolean offerFirst(E e) {
#	Line 232 | Line 218 | public class ArrayDeque<E> extends Abstr
218		* Inserts the specified element at the end of this deque.
219		*
220		* @param e the element to add
221	<	* @return <tt>true</tt> (as specified by {@link Deque#offerLast})
221	>	* @return {@code true} (as specified by {@link Deque#offerLast})
222		* @throws NullPointerException if the specified element is null
223		*/
224		public boolean offerLast(E e) {
#	Line 262 | Line 248 | public class ArrayDeque<E> extends Abstr
248
249		public E pollFirst() {
250		int h = head;
251	<	E result = elements[h]; // Element is null if deque empty
251	>	@SuppressWarnings("unchecked")
252	>	E result = (E) elements[h];
253	>	// Element is null if deque empty
254		if (result == null)
255		return null;
256		elements[h] = null;     // Must null out slot
#	Line 272 | Line 260 | public class ArrayDeque<E> extends Abstr
260
261		public E pollLast() {
262		int t = (tail - 1) & (elements.length - 1);
263	<	E result = elements[t];
263	>	@SuppressWarnings("unchecked")
264	>	E result = (E) elements[t];
265		if (result == null)
266		return null;
267		elements[t] = null;
#	Line 284 | Line 273 | public class ArrayDeque<E> extends Abstr
273		* @throws NoSuchElementException {@inheritDoc}
274		*/
275		public E getFirst() {
276	<	E x = elements[head];
277	<	if (x == null)
276	>	@SuppressWarnings("unchecked")
277	>	E result = (E) elements[head];
278	>	if (result == null)
279		throw new NoSuchElementException();
280	<	return x;
280	>	return result;
281		}
282
283		/**
284		* @throws NoSuchElementException {@inheritDoc}
285		*/
286		public E getLast() {
287	<	E x = elements[(tail - 1) & (elements.length - 1)];
288	<	if (x == null)
287	>	@SuppressWarnings("unchecked")
288	>	E result = (E) elements[(tail - 1) & (elements.length - 1)];
289	>	if (result == null)
290		throw new NoSuchElementException();
291	<	return x;
291	>	return result;
292		}
293
294	+	@SuppressWarnings("unchecked")
295		public E peekFirst() {
296	<	return elements[head]; // elements[head] is null if deque empty
296	>	// elements[head] is null if deque empty
297	>	return (E) elements[head];
298		}
299
300	+	@SuppressWarnings("unchecked")
301		public E peekLast() {
302	<	return elements[(tail - 1) & (elements.length - 1)];
302	>	return (E) elements[(tail - 1) & (elements.length - 1)];
303		}
304
305		/**
306		* Removes the first occurrence of the specified element in this
307		* deque (when traversing the deque from head to tail).
308		* If the deque does not contain the element, it is unchanged.
309	<	* More formally, removes the first element <tt>e</tt> such that
310	<	* <tt>o.equals(e)</tt> (if such an element exists).
311	<	* Returns <tt>true</tt> if this deque contained the specified element
309	>	* More formally, removes the first element {@code e} such that
310	>	* {@code o.equals(e)} (if such an element exists).
311	>	* Returns {@code true} if this deque contained the specified element
312		* (or equivalently, if this deque changed as a result of the call).
313		*
314		* @param o element to be removed from this deque, if present
315	<	* @return <tt>true</tt> if the deque contained the specified element
315	>	* @return {@code true} if the deque contained the specified element
316		*/
317		public boolean removeFirstOccurrence(Object o) {
318		if (o == null)
319		return false;
320		int mask = elements.length - 1;
321		int i = head;
322	<	E x;
322	>	Object x;
323		while ( (x = elements[i]) != null) {
324		if (o.equals(x)) {
325		delete(i);
#	Line 340 | Line 334 | public class ArrayDeque<E> extends Abstr
334		* Removes the last occurrence of the specified element in this
335		* deque (when traversing the deque from head to tail).
336		* If the deque does not contain the element, it is unchanged.
337	<	* More formally, removes the last element <tt>e</tt> such that
338	<	* <tt>o.equals(e)</tt> (if such an element exists).
339	<	* Returns <tt>true</tt> if this deque contained the specified element
337	>	* More formally, removes the last element {@code e} such that
338	>	* {@code o.equals(e)} (if such an element exists).
339	>	* Returns {@code true} if this deque contained the specified element
340		* (or equivalently, if this deque changed as a result of the call).
341		*
342		* @param o element to be removed from this deque, if present
343	<	* @return <tt>true</tt> if the deque contained the specified element
343	>	* @return {@code true} if the deque contained the specified element
344		*/
345		public boolean removeLastOccurrence(Object o) {
346		if (o == null)
347		return false;
348		int mask = elements.length - 1;
349		int i = (tail - 1) & mask;
350	<	E x;
350	>	Object x;
351		while ( (x = elements[i]) != null) {
352		if (o.equals(x)) {
353		delete(i);
#	Line 372 | Line 366 | public class ArrayDeque<E> extends Abstr
366		* <p>This method is equivalent to {@link #addLast}.
367		*
368		* @param e the element to add
369	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
369	>	* @return {@code true} (as specified by {@link Collection#add})
370		* @throws NullPointerException if the specified element is null
371		*/
372		public boolean add(E e) {
#	Line 386 | Line 380 | public class ArrayDeque<E> extends Abstr
380		* <p>This method is equivalent to {@link #offerLast}.
381		*
382		* @param e the element to add
383	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
383	>	* @return {@code true} (as specified by {@link Queue#offer})
384		* @throws NullPointerException if the specified element is null
385		*/
386		public boolean offer(E e) {
#	Line 411 | Line 405 | public class ArrayDeque<E> extends Abstr
405		/**
406		* Retrieves and removes the head of the queue represented by this deque
407		* (in other words, the first element of this deque), or returns
408	<	* <tt>null</tt> if this deque is empty.
408	>	* {@code null} if this deque is empty.
409		*
410		* <p>This method is equivalent to {@link #pollFirst}.
411		*
412		* @return the head of the queue represented by this deque, or
413	<	*         <tt>null</tt> if this deque is empty
413	>	*         {@code null} if this deque is empty
414		*/
415		public E poll() {
416		return pollFirst();
#	Line 438 | Line 432 | public class ArrayDeque<E> extends Abstr
432
433		/**
434		* Retrieves, but does not remove, the head of the queue represented by
435	<	* this deque, or returns <tt>null</tt> if this deque is empty.
435	>	* this deque, or returns {@code null} if this deque is empty.
436		*
437		* <p>This method is equivalent to {@link #peekFirst}.
438		*
439		* @return the head of the queue represented by this deque, or
440	<	*         <tt>null</tt> if this deque is empty
440	>	*         {@code null} if this deque is empty
441		*/
442		public E peek() {
443		return peekFirst();
#	Line 479 | Line 473 | public class ArrayDeque<E> extends Abstr
473		}
474
475		private void checkInvariants() {
476	<	assert elements[tail] == null;
477	<	assert head == tail ? elements[head] == null :
478	<	(elements[head] != null &&
479	<	elements[(tail - 1) & (elements.length - 1)] != null);
480	<	assert elements[(head - 1) & (elements.length - 1)] == null;
476	>	assert elements[tail] == null;
477	>	assert head == tail ? elements[head] == null :
478	>	(elements[head] != null &&
479	>	elements[(tail - 1) & (elements.length - 1)] != null);
480	>	assert elements[(head - 1) & (elements.length - 1)] == null;
481		}
482
483		/**
#	Line 497 | Line 491 | public class ArrayDeque<E> extends Abstr
491		* @return true if elements moved backwards
492		*/
493		private boolean delete(int i) {
494	<	checkInvariants();
495	<	final E[] elements = this.elements;
496	<	final int mask = elements.length - 1;
497	<	final int h = head;
498	<	final int t = tail;
499	<	final int front = (i - h) & mask;
500	<	final int back  = (t - i) & mask;
501	<
502	<	// Invariant: head <= i < tail mod circularity
503	<	if (front >= ((t - h) & mask))
504	<	throw new ConcurrentModificationException();
505	<
506	<	// Optimize for least element motion
507	<	if (front < back) {
508	<	if (h <= i) {
509	<	System.arraycopy(elements, h, elements, h + 1, front);
510	<	} else { // Wrap around
511	<	System.arraycopy(elements, 0, elements, 1, i);
512	<	elements[0] = elements[mask];
513	<	System.arraycopy(elements, h, elements, h + 1, mask - h);
514	<	}
515	<	elements[h] = null;
516	<	head = (h + 1) & mask;
517	<	return false;
518	<	} else {
519	<	if (i < t) { // Copy the null tail as well
520	<	System.arraycopy(elements, i + 1, elements, i, back);
521	<	tail = t - 1;
522	<	} else { // Wrap around
523	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
524	<	elements[mask] = elements[0];
525	<	System.arraycopy(elements, 1, elements, 0, t);
526	<	tail = (t - 1) & mask;
527	<	}
528	<	return true;
529	<	}
494	>	checkInvariants();
495	>	final Object[] elements = this.elements;
496	>	final int mask = elements.length - 1;
497	>	final int h = head;
498	>	final int t = tail;
499	>	final int front = (i - h) & mask;
500	>	final int back  = (t - i) & mask;
501	>
502	>	// Invariant: head <= i < tail mod circularity
503	>	if (front >= ((t - h) & mask))
504	>	throw new ConcurrentModificationException();
505	>
506	>	// Optimize for least element motion
507	>	if (front < back) {
508	>	if (h <= i) {
509	>	System.arraycopy(elements, h, elements, h + 1, front);
510	>	} else { // Wrap around
511	>	System.arraycopy(elements, 0, elements, 1, i);
512	>	elements[0] = elements[mask];
513	>	System.arraycopy(elements, h, elements, h + 1, mask - h);
514	>	}
515	>	elements[h] = null;
516	>	head = (h + 1) & mask;
517	>	return false;
518	>	} else {
519	>	if (i < t) { // Copy the null tail as well
520	>	System.arraycopy(elements, i + 1, elements, i, back);
521	>	tail = t - 1;
522	>	} else { // Wrap around
523	>	System.arraycopy(elements, i + 1, elements, i, mask - i);
524	>	elements[mask] = elements[0];
525	>	System.arraycopy(elements, 1, elements, 0, t);
526	>	tail = (t - 1) & mask;
527	>	}
528	>	return true;
529	>	}
530		}
531
532		// *** Collection Methods ***
#	Line 547 | Line 541 | public class ArrayDeque<E> extends Abstr
541		}
542
543		/**
544	<	* Returns <tt>true</tt> if this deque contains no elements.
544	>	* Returns {@code true} if this deque contains no elements.
545		*
546	<	* @return <tt>true</tt> if this deque contains no elements
546	>	* @return {@code true} if this deque contains no elements
547		*/
548		public boolean isEmpty() {
549		return head == tail;
#	Line 596 | Line 590 | public class ArrayDeque<E> extends Abstr
590		public E next() {
591		if (cursor == fence)
592		throw new NoSuchElementException();
593	<	E result = elements[cursor];
593	>	@SuppressWarnings("unchecked")
594	>	E result = (E) elements[cursor];
595		// This check doesn't catch all possible comodifications,
596		// but does catch the ones that corrupt traversal
597		if (tail != fence || result == null)
#	Line 611 | Line 606 | public class ArrayDeque<E> extends Abstr
606		throw new IllegalStateException();
607		if (delete(lastRet)) { // if left-shifted, undo increment in next()
608		cursor = (cursor - 1) & (elements.length - 1);
609	<	fence = tail;
610	<	}
609	>	fence = tail;
610	>	}
611		lastRet = -1;
612		}
613		}
614
615	+	/**
616	+	* This class is nearly a mirror-image of DeqIterator, using tail
617	+	* instead of head for initial cursor, and head instead of tail
618	+	* for fence.
619	+	*/
620		private class DescendingIterator implements Iterator<E> {
621	–	/*
622	–	* This class is nearly a mirror-image of DeqIterator, using
623	–	* tail instead of head for initial cursor, and head instead of
624	–	* tail for fence.
625	–	*/
621		private int cursor = tail;
622		private int fence = head;
623		private int lastRet = -1;
#	Line 635 | Line 630 | public class ArrayDeque<E> extends Abstr
630		if (cursor == fence)
631		throw new NoSuchElementException();
632		cursor = (cursor - 1) & (elements.length - 1);
633	<	E result = elements[cursor];
633	>	@SuppressWarnings("unchecked")
634	>	E result = (E) elements[cursor];
635		if (head != fence || result == null)
636		throw new ConcurrentModificationException();
637		lastRet = cursor;
#	Line 647 | Line 643 | public class ArrayDeque<E> extends Abstr
643		throw new IllegalStateException();
644		if (!delete(lastRet)) {
645		cursor = (cursor + 1) & (elements.length - 1);
646	<	fence = head;
647	<	}
646	>	fence = head;
647	>	}
648		lastRet = -1;
649		}
650		}
651
652		/**
653	<	* Returns <tt>true</tt> if this deque contains the specified element.
654	<	* More formally, returns <tt>true</tt> if and only if this deque contains
655	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
653	>	* Returns {@code true} if this deque contains the specified element.
654	>	* More formally, returns {@code true} if and only if this deque contains
655	>	* at least one element {@code e} such that {@code o.equals(e)}.
656		*
657		* @param o object to be checked for containment in this deque
658	<	* @return <tt>true</tt> if this deque contains the specified element
658	>	* @return {@code true} if this deque contains the specified element
659		*/
660		public boolean contains(Object o) {
661		if (o == null)
662		return false;
663		int mask = elements.length - 1;
664		int i = head;
665	<	E x;
665	>	Object x;
666		while ( (x = elements[i]) != null) {
667		if (o.equals(x))
668		return true;
#	Line 678 | Line 674 | public class ArrayDeque<E> extends Abstr
674		/**
675		* Removes a single instance of the specified element from this deque.
676		* If the deque does not contain the element, it is unchanged.
677	<	* More formally, removes the first element <tt>e</tt> such that
678	<	* <tt>o.equals(e)</tt> (if such an element exists).
679	<	* Returns <tt>true</tt> if this deque contained the specified element
677	>	* More formally, removes the first element {@code e} such that
678	>	* {@code o.equals(e)} (if such an element exists).
679	>	* Returns {@code true} if this deque contained the specified element
680		* (or equivalently, if this deque changed as a result of the call).
681		*
682	<	* <p>This method is equivalent to {@link #removeFirstOccurrence}.
682	>	* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}.
683		*
684		* @param o element to be removed from this deque, if present
685	<	* @return <tt>true</tt> if this deque contained the specified element
685	>	* @return {@code true} if this deque contained the specified element
686		*/
687		public boolean remove(Object o) {
688		return removeFirstOccurrence(o);
#	Line 724 | Line 720 | public class ArrayDeque<E> extends Abstr
720		* @return an array containing all of the elements in this deque
721		*/
722		public Object[] toArray() {
723	<	return copyElements(new Object[size()]);
723	>	final int head = this.head;
724	>	final int tail = this.tail;
725	>	boolean wrap = (tail < head);
726	>	int end = wrap ? tail + elements.length : tail;
727	>	Object[] a = Arrays.copyOfRange(elements, head, end);
728	>	if (wrap)
729	>	System.arraycopy(elements, 0, a, elements.length - head, tail);
730	>	return a;
731		}
732
733		/**
#	Line 738 | Line 741 | public class ArrayDeque<E> extends Abstr
741		* <p>If this deque fits in the specified array with room to spare
742		* (i.e., the array has more elements than this deque), the element in
743		* the array immediately following the end of the deque is set to
744	<	* <tt>null</tt>.
744	>	* {@code null}.
745		*
746		* <p>Like the {@link #toArray()} method, this method acts as bridge between
747		* array-based and collection-based APIs.  Further, this method allows
748		* precise control over the runtime type of the output array, and may,
749		* under certain circumstances, be used to save allocation costs.
750		*
751	<	* <p>Suppose <tt>x</tt> is a deque known to contain only strings.
751	>	* <p>Suppose {@code x} is a deque known to contain only strings.
752		* The following code can be used to dump the deque into a newly
753	<	* allocated array of <tt>String</tt>:
753	>	* allocated array of {@code String}:
754		*
755	<	* <pre>
753	<	*     String[] y = x.toArray(new String[0]);</pre>
755	>	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
756		*
757	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
758	<	* <tt>toArray()</tt>.
757	>	* Note that {@code toArray(new Object[0])} is identical in function to
758	>	* {@code toArray()}.
759		*
760		* @param a the array into which the elements of the deque are to
761		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 764 | Line 766 | public class ArrayDeque<E> extends Abstr
766		*         this deque
767		* @throws NullPointerException if the specified array is null
768		*/
769	+	@SuppressWarnings("unchecked")
770		public <T> T[] toArray(T[] a) {
771	<	int size = size();
772	<	if (a.length < size)
773	<	a = (T[])java.lang.reflect.Array.newInstance(
774	<	a.getClass().getComponentType(), size);
775	<	copyElements(a);
776	<	if (a.length > size)
777	<	a[size] = null;
771	>	final int head = this.head;
772	>	final int tail = this.tail;
773	>	boolean wrap = (tail < head);
774	>	int size = (tail - head) + (wrap ? elements.length : 0);
775	>	int firstLeg = size - (wrap ? tail : 0);
776	>	int len = a.length;
777	>	if (size > len) {
778	>	a = (T[]) Arrays.copyOfRange(elements, head, head + size,
779	>	a.getClass());
780	>	} else {
781	>	System.arraycopy(elements, head, a, 0, firstLeg);
782	>	if (size < len)
783	>	a[size] = null;
784	>	}
785	>	if (wrap)
786	>	System.arraycopy(elements, 0, a, firstLeg, tail);
787		return a;
788		}
789
#	Line 784 | Line 796 | public class ArrayDeque<E> extends Abstr
796		*/
797		public ArrayDeque<E> clone() {
798		try {
799	+	@SuppressWarnings("unchecked")
800		ArrayDeque<E> result = (ArrayDeque<E>) super.clone();
801	<	// These two lines are currently faster than cloning the array:
789	<	result.elements = (E[]) new Object[elements.length];
790	<	System.arraycopy(elements, 0, result.elements, 0, elements.length);
801	>	result.elements = Arrays.copyOf(elements, elements.length);
802		return result;
792	–
803		} catch (CloneNotSupportedException e) {
804		throw new AssertionError();
805		}
806		}
807
798	–	/**
799	–	* Appease the serialization gods.
800	–	*/
808		private static final long serialVersionUID = 2340985798034038923L;
809
810		/**
811	<	* Serialize this deque.
811	>	* Saves this deque to a stream (that is, serializes it).
812		*
813	<	* @serialData The current size (<tt>int</tt>) of the deque,
813	>	* @serialData The current size ({@code int}) of the deque,
814		* followed by all of its elements (each an object reference) in
815		* first-to-last order.
816		*/
817	<	private void writeObject(ObjectOutputStream s) throws IOException {
817	>	private void writeObject(java.io.ObjectOutputStream s)
818	>	throws java.io.IOException {
819		s.defaultWriteObject();
820
821		// Write out size
#	Line 820 | Line 828 | public class ArrayDeque<E> extends Abstr
828		}
829
830		/**
831	<	* Deserialize this deque.
831	>	* Reconstitutes this deque from a stream (that is, deserializes it).
832		*/
833	<	private void readObject(ObjectInputStream s)
834	<	throws IOException, ClassNotFoundException {
833	>	private void readObject(java.io.ObjectInputStream s)
834	>	throws java.io.IOException, ClassNotFoundException {
835		s.defaultReadObject();
836
837		// Read in size and allocate array
#	Line 834 | Line 842 | public class ArrayDeque<E> extends Abstr
842
843		// Read in all elements in the proper order.
844		for (int i = 0; i < size; i++)
845	<	elements[i] = (E)s.readObject();
845	>	elements[i] = s.readObject();
846		}
847	+
848	+	public Spliterator<E> spliterator() {
849	+	return new DeqSpliterator<E>(this, -1, -1);
850	+	}
851	+
852	+	static final class DeqSpliterator<E> implements Spliterator<E> {
853	+	private final ArrayDeque<E> deq;
854	+	private int fence;  // -1 until first use
855	+	private int index;  // current index, modified on traverse/split
856	+
857	+	/** Creates new spliterator covering the given array and range */
858	+	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
859	+	this.deq = deq;
860	+	this.index = origin;
861	+	this.fence = fence;
862	+	}
863	+
864	+	private int getFence() { // force initialization
865	+	int t;
866	+	if ((t = fence) < 0) {
867	+	t = fence = deq.tail;
868	+	index = deq.head;
869	+	}
870	+	return t;
871	+	}
872	+
873	+	public Spliterator<E> trySplit() {
874	+	int t = getFence(), h = index, n = deq.elements.length;
875	+	if (h != t && ((h + 1) & (n - 1)) != t) {
876	+	if (h > t)
877	+	t += n;
878	+	int m = ((h + t) >>> 1) & (n - 1);
879	+	return new DeqSpliterator<>(deq, h, index = m);
880	+	}
881	+	return null;
882	+	}
883	+
884	+	public void forEachRemaining(Consumer<? super E> consumer) {
885	+	if (consumer == null)
886	+	throw new NullPointerException();
887	+	Object[] a = deq.elements;
888	+	int m = a.length - 1, f = getFence(), i = index;
889	+	index = f;
890	+	while (i != f) {
891	+	@SuppressWarnings("unchecked") E e = (E)a[i];
892	+	i = (i + 1) & m;
893	+	if (e == null)
894	+	throw new ConcurrentModificationException();
895	+	consumer.accept(e);
896	+	}
897	+	}
898	+
899	+	public boolean tryAdvance(Consumer<? super E> consumer) {
900	+	if (consumer == null)
901	+	throw new NullPointerException();
902	+	Object[] a = deq.elements;
903	+	int m = a.length - 1, f = getFence(), i = index;
904	+	if (i != fence) {
905	+	@SuppressWarnings("unchecked") E e = (E)a[i];
906	+	index = (i + 1) & m;
907	+	if (e == null)
908	+	throw new ConcurrentModificationException();
909	+	consumer.accept(e);
910	+	return true;
911	+	}
912	+	return false;
913	+	}
914	+
915	+	public long estimateSize() {
916	+	int n = getFence() - index;
917	+	if (n < 0)
918	+	n += deq.elements.length;
919	+	return (long) n;
920	+	}
921	+
922	+	@Override
923	+	public int characteristics() {
924	+	return Spliterator.ORDERED | Spliterator.SIZED |
925	+	Spliterator.NONNULL | Spliterator.SUBSIZED;
926	+	}
927	+	}
928	+
929		}

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