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Comparing jsr166/src/main/java/util/ArrayDeque.java (file contents):
Revision 1.25 by jsr166, Sat Sep 17 17:22:17 2005 UTC vs.
Revision 1.48 by jsr166, Mon Feb 18 01:30:23 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.util.*; // for javadoc (till 6280605 is fixed)
8	<	import java.io.*;
7	>	import java.io.Serializable;
8	>	import java.util.function.Consumer;
9	>	import java.util.stream.Stream;
10	>	import java.util.stream.Streams;
11
12		/**
13		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 16 | Line 18 | import java.io.*;
18		* {@link Stack} when used as a stack, and faster than {@link LinkedList}
19		* when used as a queue.
20		*
21	<	* <p>Most <tt>ArrayDeque</tt> operations run in amortized constant time.
21	>	* <p>Most {@code ArrayDeque} operations run in amortized constant time.
22		* Exceptions include {@link #remove(Object) remove}, {@link
23		* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence
24		* removeLastOccurrence}, {@link #contains contains}, {@link #iterator
25		* iterator.remove()}, and the bulk operations, all of which run in linear
26		* time.
27		*
28	<	* <p>The iterators returned by this class's <tt>iterator</tt> method are
28	>	* <p>The iterators returned by this class's {@code iterator} method are
29		* <i>fail-fast</i>: If the deque is modified at any time after the iterator
30	<	* is created, in any way except through the iterator's own <tt>remove</tt>
30	>	* is created, in any way except through the iterator's own {@code remove}
31		* method, the iterator will generally throw a {@link
32		* ConcurrentModificationException}.  Thus, in the face of concurrent
33		* modification, the iterator fails quickly and cleanly, rather than risking
#	Line 35 | Line 37 | import java.io.*;
37		* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
38		* as it is, generally speaking, impossible to make any hard guarantees in the
39		* presence of unsynchronized concurrent modification.  Fail-fast iterators
40	<	* throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
40	>	* throw {@code ConcurrentModificationException} on a best-effort basis.
41		* Therefore, it would be wrong to write a program that depended on this
42		* exception for its correctness: <i>the fail-fast behavior of iterators
43		* should be used only to detect bugs.</i>
#	Line 45 | Line 47 | import java.io.*;
47		* Iterator} interfaces.
48		*
49		* <p>This class is a member of the
50	<	* <a href="{@docRoot}/../guide/collections/index.html">
50	>	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
51		* Java Collections Framework</a>.
52		*
53		* @author  Josh Bloch and Doug Lea
#	Line 65 | Line 67 | public class ArrayDeque<E> extends Abstr
67		* other.  We also guarantee that all array cells not holding
68		* deque elements are always null.
69		*/
70	<	private transient E[] elements;
70	>	transient Object[] elements; // non-private to simplify nested class access
71
72		/**
73		* The index of the element at the head of the deque (which is the
74		* element that would be removed by remove() or pop()); or an
75		* arbitrary number equal to tail if the deque is empty.
76		*/
77	<	private transient int head;
77	>	transient int head;
78
79		/**
80		* The index at which the next element would be added to the tail
81		* of the deque (via addLast(E), add(E), or push(E)).
82		*/
83	<	private transient int tail;
83	>	transient int tail;
84
85		/**
86		* The minimum capacity that we'll use for a newly created deque.
#	Line 89 | Line 91 | public class ArrayDeque<E> extends Abstr
91		// ******  Array allocation and resizing utilities ******
92
93		/**
94	<	* Allocate empty array to hold the given number of elements.
94	>	* Allocates empty array to hold the given number of elements.
95		*
96		* @param numElements  the number of elements to hold
97		*/
#	Line 109 | Line 111 | public class ArrayDeque<E> extends Abstr
111		if (initialCapacity < 0)   // Too many elements, must back off
112		initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements
113		}
114	<	elements = (E[]) new Object[initialCapacity];
114	>	elements = new Object[initialCapacity];
115		}
116
117		/**
118	<	* Double the capacity of this deque.  Call only when full, i.e.,
118	>	* Doubles the capacity of this deque.  Call only when full, i.e.,
119		* when head and tail have wrapped around to become equal.
120		*/
121		private void doubleCapacity() {
#	Line 127 | Line 129 | public class ArrayDeque<E> extends Abstr
129		Object[] a = new Object[newCapacity];
130		System.arraycopy(elements, p, a, 0, r);
131		System.arraycopy(elements, 0, a, r, p);
132	<	elements = (E[])a;
132	>	elements = a;
133		head = 0;
134		tail = n;
135		}
#	Line 155 | Line 157 | public class ArrayDeque<E> extends Abstr
157		* sufficient to hold 16 elements.
158		*/
159		public ArrayDeque() {
160	<	elements = (E[]) new Object[16];
160	>	elements = new Object[16];
161		}
162
163		/**
#	Line 221 | Line 223 | public class ArrayDeque<E> extends Abstr
223		* Inserts the specified element at the front of this deque.
224		*
225		* @param e the element to add
226	<	* @return <tt>true</tt> (as specified by {@link Deque#offerFirst})
226	>	* @return {@code true} (as specified by {@link Deque#offerFirst})
227		* @throws NullPointerException if the specified element is null
228		*/
229		public boolean offerFirst(E e) {
#	Line 233 | Line 235 | public class ArrayDeque<E> extends Abstr
235		* Inserts the specified element at the end of this deque.
236		*
237		* @param e the element to add
238	<	* @return <tt>true</tt> (as specified by {@link Deque#offerLast})
238	>	* @return {@code true} (as specified by {@link Deque#offerLast})
239		* @throws NullPointerException if the specified element is null
240		*/
241		public boolean offerLast(E e) {
#	Line 263 | Line 265 | public class ArrayDeque<E> extends Abstr
265
266		public E pollFirst() {
267		int h = head;
268	<	E result = elements[h]; // Element is null if deque empty
268	>	@SuppressWarnings("unchecked")
269	>	E result = (E) elements[h];
270	>	// Element is null if deque empty
271		if (result == null)
272		return null;
273		elements[h] = null;     // Must null out slot
#	Line 273 | Line 277 | public class ArrayDeque<E> extends Abstr
277
278		public E pollLast() {
279		int t = (tail - 1) & (elements.length - 1);
280	<	E result = elements[t];
280	>	@SuppressWarnings("unchecked")
281	>	E result = (E) elements[t];
282		if (result == null)
283		return null;
284		elements[t] = null;
#	Line 285 | Line 290 | public class ArrayDeque<E> extends Abstr
290		* @throws NoSuchElementException {@inheritDoc}
291		*/
292		public E getFirst() {
293	<	E x = elements[head];
294	<	if (x == null)
293	>	@SuppressWarnings("unchecked")
294	>	E result = (E) elements[head];
295	>	if (result == null)
296		throw new NoSuchElementException();
297	<	return x;
297	>	return result;
298		}
299
300		/**
301		* @throws NoSuchElementException {@inheritDoc}
302		*/
303		public E getLast() {
304	<	E x = elements[(tail - 1) & (elements.length - 1)];
305	<	if (x == null)
304	>	@SuppressWarnings("unchecked")
305	>	E result = (E) elements[(tail - 1) & (elements.length - 1)];
306	>	if (result == null)
307		throw new NoSuchElementException();
308	<	return x;
308	>	return result;
309		}
310
311	+	@SuppressWarnings("unchecked")
312		public E peekFirst() {
313	<	return elements[head]; // elements[head] is null if deque empty
313	>	// elements[head] is null if deque empty
314	>	return (E) elements[head];
315		}
316
317	+	@SuppressWarnings("unchecked")
318		public E peekLast() {
319	<	return elements[(tail - 1) & (elements.length - 1)];
319	>	return (E) elements[(tail - 1) & (elements.length - 1)];
320		}
321
322		/**
323		* Removes the first occurrence of the specified element in this
324		* deque (when traversing the deque from head to tail).
325		* If the deque does not contain the element, it is unchanged.
326	<	* More formally, removes the first element <tt>e</tt> such that
327	<	* <tt>o.equals(e)</tt> (if such an element exists).
328	<	* Returns <tt>true</tt> if this deque contained the specified element
326	>	* More formally, removes the first element {@code e} such that
327	>	* {@code o.equals(e)} (if such an element exists).
328	>	* Returns {@code true} if this deque contained the specified element
329		* (or equivalently, if this deque changed as a result of the call).
330		*
331		* @param o element to be removed from this deque, if present
332	<	* @return <tt>true</tt> if the deque contained the specified element
332	>	* @return {@code true} if the deque contained the specified element
333		*/
334		public boolean removeFirstOccurrence(Object o) {
335		if (o == null)
336		return false;
337		int mask = elements.length - 1;
338		int i = head;
339	<	E x;
339	>	Object x;
340		while ( (x = elements[i]) != null) {
341		if (o.equals(x)) {
342		delete(i);
#	Line 341 | Line 351 | public class ArrayDeque<E> extends Abstr
351		* Removes the last occurrence of the specified element in this
352		* deque (when traversing the deque from head to tail).
353		* If the deque does not contain the element, it is unchanged.
354	<	* More formally, removes the last element <tt>e</tt> such that
355	<	* <tt>o.equals(e)</tt> (if such an element exists).
356	<	* Returns <tt>true</tt> if this deque contained the specified element
354	>	* More formally, removes the last element {@code e} such that
355	>	* {@code o.equals(e)} (if such an element exists).
356	>	* Returns {@code true} if this deque contained the specified element
357		* (or equivalently, if this deque changed as a result of the call).
358		*
359		* @param o element to be removed from this deque, if present
360	<	* @return <tt>true</tt> if the deque contained the specified element
360	>	* @return {@code true} if the deque contained the specified element
361		*/
362		public boolean removeLastOccurrence(Object o) {
363		if (o == null)
364		return false;
365		int mask = elements.length - 1;
366		int i = (tail - 1) & mask;
367	<	E x;
367	>	Object x;
368		while ( (x = elements[i]) != null) {
369		if (o.equals(x)) {
370		delete(i);
#	Line 373 | Line 383 | public class ArrayDeque<E> extends Abstr
383		* <p>This method is equivalent to {@link #addLast}.
384		*
385		* @param e the element to add
386	<	* @return <tt>true</tt> (as specified by {@link Collection#add})
386	>	* @return {@code true} (as specified by {@link Collection#add})
387		* @throws NullPointerException if the specified element is null
388		*/
389		public boolean add(E e) {
#	Line 387 | Line 397 | public class ArrayDeque<E> extends Abstr
397		* <p>This method is equivalent to {@link #offerLast}.
398		*
399		* @param e the element to add
400	<	* @return <tt>true</tt> (as specified by {@link Queue#offer})
400	>	* @return {@code true} (as specified by {@link Queue#offer})
401		* @throws NullPointerException if the specified element is null
402		*/
403		public boolean offer(E e) {
#	Line 412 | Line 422 | public class ArrayDeque<E> extends Abstr
422		/**
423		* Retrieves and removes the head of the queue represented by this deque
424		* (in other words, the first element of this deque), or returns
425	<	* <tt>null</tt> if this deque is empty.
425	>	* {@code null} if this deque is empty.
426		*
427		* <p>This method is equivalent to {@link #pollFirst}.
428		*
429		* @return the head of the queue represented by this deque, or
430	<	*         <tt>null</tt> if this deque is empty
430	>	*         {@code null} if this deque is empty
431		*/
432		public E poll() {
433		return pollFirst();
#	Line 439 | Line 449 | public class ArrayDeque<E> extends Abstr
449
450		/**
451		* Retrieves, but does not remove, the head of the queue represented by
452	<	* this deque, or returns <tt>null</tt> if this deque is empty.
452	>	* this deque, or returns {@code null} if this deque is empty.
453		*
454		* <p>This method is equivalent to {@link #peekFirst}.
455		*
456		* @return the head of the queue represented by this deque, or
457	<	*         <tt>null</tt> if this deque is empty
457	>	*         {@code null} if this deque is empty
458		*/
459		public E peek() {
460		return peekFirst();
#	Line 480 | Line 490 | public class ArrayDeque<E> extends Abstr
490		}
491
492		private void checkInvariants() {
493	<	assert elements[tail] == null;
494	<	assert head == tail ? elements[head] == null :
495	<	(elements[head] != null &&
496	<	elements[(tail - 1) & (elements.length - 1)] != null);
497	<	assert elements[(head - 1) & (elements.length - 1)] == null;
493	>	assert elements[tail] == null;
494	>	assert head == tail ? elements[head] == null :
495	>	(elements[head] != null &&
496	>	elements[(tail - 1) & (elements.length - 1)] != null);
497	>	assert elements[(head - 1) & (elements.length - 1)] == null;
498		}
499
500		/**
#	Line 498 | Line 508 | public class ArrayDeque<E> extends Abstr
508		* @return true if elements moved backwards
509		*/
510		private boolean delete(int i) {
511	<	checkInvariants();
512	<	final E[] elements = this.elements;
513	<	final int mask = elements.length - 1;
514	<	final int h = head;
515	<	final int t = tail;
516	<	final int front = (i - h) & mask;
517	<	final int back  = (t - i) & mask;
518	<
519	<	// Invariant: head <= i < tail mod circularity
520	<	if (front >= ((t - h) & mask))
521	<	throw new ConcurrentModificationException();
522	<
523	<	// Optimize for least element motion
524	<	if (front < back) {
525	<	if (h <= i) {
526	<	System.arraycopy(elements, h, elements, h + 1, front);
527	<	} else { // Wrap around
528	<	System.arraycopy(elements, 0, elements, 1, i);
529	<	elements[0] = elements[mask];
530	<	System.arraycopy(elements, h, elements, h + 1, mask - h);
531	<	}
532	<	elements[h] = null;
533	<	head = (h + 1) & mask;
534	<	return false;
535	<	} else {
536	<	if (i < t) { // Copy the null tail as well
537	<	System.arraycopy(elements, i + 1, elements, i, back);
538	<	tail = t - 1;
539	<	} else { // Wrap around
540	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
541	<	elements[mask] = elements[0];
542	<	System.arraycopy(elements, 1, elements, 0, t);
543	<	tail = (t - 1) & mask;
544	<	}
545	<	return true;
546	<	}
511	>	checkInvariants();
512	>	final Object[] elements = this.elements;
513	>	final int mask = elements.length - 1;
514	>	final int h = head;
515	>	final int t = tail;
516	>	final int front = (i - h) & mask;
517	>	final int back  = (t - i) & mask;
518	>
519	>	// Invariant: head <= i < tail mod circularity
520	>	if (front >= ((t - h) & mask))
521	>	throw new ConcurrentModificationException();
522	>
523	>	// Optimize for least element motion
524	>	if (front < back) {
525	>	if (h <= i) {
526	>	System.arraycopy(elements, h, elements, h + 1, front);
527	>	} else { // Wrap around
528	>	System.arraycopy(elements, 0, elements, 1, i);
529	>	elements[0] = elements[mask];
530	>	System.arraycopy(elements, h, elements, h + 1, mask - h);
531	>	}
532	>	elements[h] = null;
533	>	head = (h + 1) & mask;
534	>	return false;
535	>	} else {
536	>	if (i < t) { // Copy the null tail as well
537	>	System.arraycopy(elements, i + 1, elements, i, back);
538	>	tail = t - 1;
539	>	} else { // Wrap around
540	>	System.arraycopy(elements, i + 1, elements, i, mask - i);
541	>	elements[mask] = elements[0];
542	>	System.arraycopy(elements, 1, elements, 0, t);
543	>	tail = (t - 1) & mask;
544	>	}
545	>	return true;
546	>	}
547		}
548
549		// *** Collection Methods ***
#	Line 548 | Line 558 | public class ArrayDeque<E> extends Abstr
558		}
559
560		/**
561	<	* Returns <tt>true</tt> if this deque contains no elements.
561	>	* Returns {@code true} if this deque contains no elements.
562		*
563	<	* @return <tt>true</tt> if this deque contains no elements
563	>	* @return {@code true} if this deque contains no elements
564		*/
565		public boolean isEmpty() {
566		return head == tail;
#	Line 595 | Line 605 | public class ArrayDeque<E> extends Abstr
605		}
606
607		public E next() {
598	–	E result;
608		if (cursor == fence)
609		throw new NoSuchElementException();
610	+	@SuppressWarnings("unchecked")
611	+	E result = (E) elements[cursor];
612		// This check doesn't catch all possible comodifications,
613		// but does catch the ones that corrupt traversal
614	<	if (tail != fence || (result = elements[cursor]) == null)
614	>	if (tail != fence || result == null)
615		throw new ConcurrentModificationException();
616		lastRet = cursor;
617		cursor = (cursor + 1) & (elements.length - 1);
#	Line 610 | Line 621 | public class ArrayDeque<E> extends Abstr
621		public void remove() {
622		if (lastRet < 0)
623		throw new IllegalStateException();
624	<	if (delete(lastRet)) // if left-shifted, undo increment in next()
624	>	if (delete(lastRet)) { // if left-shifted, undo increment in next()
625		cursor = (cursor - 1) & (elements.length - 1);
626	+	fence = tail;
627	+	}
628		lastRet = -1;
616	–	fence = tail;
629		}
630		}
631
632		private class DescendingIterator implements Iterator<E> {
633		/*
634		* This class is nearly a mirror-image of DeqIterator, using
635	<	* (tail-1) instead of head for initial cursor, (head-1)
636	<	* instead of tail for fence, and elements.length instead of -1
625	<	* for sentinel. It shares the same structure, but not many
626	<	* actual lines of code.
635	>	* tail instead of head for initial cursor, and head instead of
636	>	* tail for fence.
637		*/
638	<	private int cursor = (tail - 1) & (elements.length - 1);
639	<	private int fence =  (head - 1) & (elements.length - 1);
640	<	private int lastRet = elements.length;
638	>	private int cursor = tail;
639	>	private int fence = head;
640	>	private int lastRet = -1;
641
642		public boolean hasNext() {
643		return cursor != fence;
644		}
645
646		public E next() {
637	–	E result;
647		if (cursor == fence)
648		throw new NoSuchElementException();
649	<	if (((head - 1) & (elements.length - 1)) != fence ||
650	<	(result = elements[cursor]) == null)
649	>	cursor = (cursor - 1) & (elements.length - 1);
650	>	@SuppressWarnings("unchecked")
651	>	E result = (E) elements[cursor];
652	>	if (head != fence || result == null)
653		throw new ConcurrentModificationException();
654		lastRet = cursor;
644	–	cursor = (cursor - 1) & (elements.length - 1);
655		return result;
656		}
657
658		public void remove() {
659	<	if (lastRet >= elements.length)
659	>	if (lastRet < 0)
660		throw new IllegalStateException();
661	<	if (!delete(lastRet))
661	>	if (!delete(lastRet)) {
662		cursor = (cursor + 1) & (elements.length - 1);
663	<	lastRet = elements.length;
664	<	fence = (head - 1) & (elements.length - 1);
663	>	fence = head;
664	>	}
665	>	lastRet = -1;
666		}
667		}
668
669		/**
670	<	* Returns <tt>true</tt> if this deque contains the specified element.
671	<	* More formally, returns <tt>true</tt> if and only if this deque contains
672	<	* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
670	>	* Returns {@code true} if this deque contains the specified element.
671	>	* More formally, returns {@code true} if and only if this deque contains
672	>	* at least one element {@code e} such that {@code o.equals(e)}.
673		*
674		* @param o object to be checked for containment in this deque
675	<	* @return <tt>true</tt> if this deque contains the specified element
675	>	* @return {@code true} if this deque contains the specified element
676		*/
677		public boolean contains(Object o) {
678		if (o == null)
679		return false;
680		int mask = elements.length - 1;
681		int i = head;
682	<	E x;
682	>	Object x;
683		while ( (x = elements[i]) != null) {
684		if (o.equals(x))
685		return true;
#	Line 680 | Line 691 | public class ArrayDeque<E> extends Abstr
691		/**
692		* Removes a single instance of the specified element from this deque.
693		* If the deque does not contain the element, it is unchanged.
694	<	* More formally, removes the first element <tt>e</tt> such that
695	<	* <tt>o.equals(e)</tt> (if such an element exists).
696	<	* Returns <tt>true</tt> if this deque contained the specified element
694	>	* More formally, removes the first element {@code e} such that
695	>	* {@code o.equals(e)} (if such an element exists).
696	>	* Returns {@code true} if this deque contained the specified element
697		* (or equivalently, if this deque changed as a result of the call).
698		*
699	<	* <p>This method is equivalent to {@link #removeFirstOccurrence}.
699	>	* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}.
700		*
701		* @param o element to be removed from this deque, if present
702	<	* @return <tt>true</tt> if this deque contained the specified element
702	>	* @return {@code true} if this deque contained the specified element
703		*/
704		public boolean remove(Object o) {
705		return removeFirstOccurrence(o);
#	Line 726 | Line 737 | public class ArrayDeque<E> extends Abstr
737		* @return an array containing all of the elements in this deque
738		*/
739		public Object[] toArray() {
740	<	return copyElements(new Object[size()]);
740	>	return copyElements(new Object[size()]);
741		}
742
743		/**
#	Line 740 | Line 751 | public class ArrayDeque<E> extends Abstr
751		* <p>If this deque fits in the specified array with room to spare
752		* (i.e., the array has more elements than this deque), the element in
753		* the array immediately following the end of the deque is set to
754	<	* <tt>null</tt>.
754	>	* {@code null}.
755		*
756		* <p>Like the {@link #toArray()} method, this method acts as bridge between
757		* array-based and collection-based APIs.  Further, this method allows
758		* precise control over the runtime type of the output array, and may,
759		* under certain circumstances, be used to save allocation costs.
760		*
761	<	* <p>Suppose <tt>x</tt> is a deque known to contain only strings.
761	>	* <p>Suppose {@code x} is a deque known to contain only strings.
762		* The following code can be used to dump the deque into a newly
763	<	* allocated array of <tt>String</tt>:
763	>	* allocated array of {@code String}:
764		*
765	<	* <pre>
755	<	*     String[] y = x.toArray(new String[0]);</pre>
765	>	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
766		*
767	<	* Note that <tt>toArray(new Object[0])</tt> is identical in function to
768	<	* <tt>toArray()</tt>.
767	>	* Note that {@code toArray(new Object[0])} is identical in function to
768	>	* {@code toArray()}.
769		*
770		* @param a the array into which the elements of the deque are to
771		*          be stored, if it is big enough; otherwise, a new array of the
#	Line 766 | Line 776 | public class ArrayDeque<E> extends Abstr
776		*         this deque
777		* @throws NullPointerException if the specified array is null
778		*/
779	+	@SuppressWarnings("unchecked")
780		public <T> T[] toArray(T[] a) {
781		int size = size();
782		if (a.length < size)
783		a = (T[])java.lang.reflect.Array.newInstance(
784		a.getClass().getComponentType(), size);
785	<	copyElements(a);
785	>	copyElements(a);
786		if (a.length > size)
787		a[size] = null;
788		return a;
#	Line 786 | Line 797 | public class ArrayDeque<E> extends Abstr
797		*/
798		public ArrayDeque<E> clone() {
799		try {
800	+	@SuppressWarnings("unchecked")
801		ArrayDeque<E> result = (ArrayDeque<E>) super.clone();
802	<	// These two lines are currently faster than cloning the array:
791	<	result.elements = (E[]) new Object[elements.length];
792	<	System.arraycopy(elements, 0, result.elements, 0, elements.length);
802	>	result.elements = Arrays.copyOf(elements, elements.length);
803		return result;
794	–
804		} catch (CloneNotSupportedException e) {
805		throw new AssertionError();
806		}
807		}
808
800	–	/**
801	–	* Appease the serialization gods.
802	–	*/
809		private static final long serialVersionUID = 2340985798034038923L;
810
811		/**
812	<	* Serialize this deque.
812	>	* Saves this deque to a stream (that is, serializes it).
813		*
814	<	* @serialData The current size (<tt>int</tt>) of the deque,
814	>	* @serialData The current size ({@code int}) of the deque,
815		* followed by all of its elements (each an object reference) in
816		* first-to-last order.
817		*/
818	<	private void writeObject(ObjectOutputStream s) throws IOException {
818	>	private void writeObject(java.io.ObjectOutputStream s)
819	>	throws java.io.IOException {
820		s.defaultWriteObject();
821
822		// Write out size
#	Line 822 | Line 829 | public class ArrayDeque<E> extends Abstr
829		}
830
831		/**
832	<	* Deserialize this deque.
832	>	* Reconstitutes this deque from a stream (that is, deserializes it).
833		*/
834	<	private void readObject(ObjectInputStream s)
835	<	throws IOException, ClassNotFoundException {
834	>	private void readObject(java.io.ObjectInputStream s)
835	>	throws java.io.IOException, ClassNotFoundException {
836		s.defaultReadObject();
837
838		// Read in size and allocate array
#	Line 836 | Line 843 | public class ArrayDeque<E> extends Abstr
843
844		// Read in all elements in the proper order.
845		for (int i = 0; i < size; i++)
846	<	elements[i] = (E)s.readObject();
846	>	elements[i] = s.readObject();
847	>	}
848	>
849	>	Spliterator<E> spliterator() {
850	>	return new DeqSpliterator<E>(this, -1, -1);
851	>	}
852	>
853	>	public Stream<E> stream() {
854	>	return Streams.stream(spliterator());
855		}
856	+
857	+	public Stream<E> parallelStream() {
858	+	return Streams.parallelStream(spliterator());
859	+	}
860	+
861	+	static final class DeqSpliterator<E> implements Spliterator<E> {
862	+	private final ArrayDeque<E> deq;
863	+	private int fence;  // -1 until first use
864	+	private int index;  // current index, modified on traverse/split
865	+
866	+	/** Create 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;
935	+	}
936	+	}
937	+
938		}

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