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 1.56 by jsr166, Thu Jul 18 17:48:28 2013 UTC vs.
Revision 1.121 by jsr166, Mon Nov 21 15:30:44 2016 UTC

#	Line 4 | Line 4
4		*/
5
6		package java.util;
7	+
8		import java.io.Serializable;
9		import java.util.function.Consumer;
10	<	import java.util.stream.Stream;
10	>	import java.util.function.Predicate;
11	>	import java.util.function.UnaryOperator;
12
13		/**
14		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 52 | Line 54 | import java.util.stream.Stream;
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
56	–	* @param <E> the type of elements held in this collection
59		*/
60		public class ArrayDeque<E> extends AbstractCollection<E>
61		implements Deque<E>, Cloneable, Serializable
62		{
63	+	/*
64	+	* 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.  Having only
72	+	* one hot inner loop body instead of two or three eases human
73	+	* maintenance and encourages VM loop inlining into the caller.
74	+	*/
75	+
76		/**
77		* The array in which the elements of the deque are stored.
78	<	* The capacity of the deque is the length of this array, which is
79	<	* always a power of two. The array is never allowed to become
65	<	* full, except transiently within an addX method where it is
66	<	* resized (see doubleCapacity) immediately upon becoming full,
67	<	* thus avoiding head and tail wrapping around to equal each
68	<	* other.  We also guarantee that all array cells not holding
69	<	* deque elements are always null.
78	>	* All array cells not holding deque elements are always null.
79	>	* The array always has at least one null slot (at tail).
80		*/
81	<	transient Object[] elements; // non-private to simplify nested class access
81	>	transient Object[] elements;
82
83		/**
84		* The index of the element at the head of the deque (which is the
85		* element that would be removed by remove() or pop()); or an
86	<	* arbitrary number equal to tail if the deque is empty.
86	>	* arbitrary number 0 <= head < elements.length equal to tail if
87	>	* the deque is empty.
88		*/
89		transient int head;
90
91		/**
92		* The index at which the next element would be added to the tail
93	<	* of the deque (via addLast(E), add(E), or push(E)).
93	>	* of the deque (via addLast(E), add(E), or push(E));
94	>	* elements[tail] is always null.
95		*/
96		transient int tail;
97
98		/**
99	<	* The minimum capacity that we'll use for a newly created deque.
100	<	* Must be a power of 2.
99	>	* The maximum size of array to allocate.
100	>	* Some VMs reserve some header words in an array.
101	>	* Attempts to allocate larger arrays may result in
102	>	* OutOfMemoryError: Requested array size exceeds VM limit
103		*/
104	<	private static final int MIN_INITIAL_CAPACITY = 8;
104	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
105
106	<	// ******  Array allocation and resizing utilities ******
106	>	/**
107	>	* Increases the capacity of this deque by at least the given amount.
108	>	*
109	>	* @param needed the required minimum extra capacity; must be positive
110	>	*/
111	>	private void grow(int needed) {
112	>	// overflow-conscious code
113	>	final int oldCapacity = elements.length;
114	>	int newCapacity;
115	>	// Double capacity if small; else grow by 50%
116	>	int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
117	>	if (jump < needed
118	>	|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
119	>	newCapacity = newCapacity(needed, jump);
120	>	elements = Arrays.copyOf(elements, newCapacity);
121	>	// Exceptionally, here tail == head needs to be disambiguated
122	>	if (tail < head || (tail == head && elements[head] != null)) {
123	>	// wrap around; slide first leg forward to end of array
124	>	int newSpace = newCapacity - oldCapacity;
125	>	System.arraycopy(elements, head,
126	>	elements, head + newSpace,
127	>	oldCapacity - head);
128	>	Arrays.fill(elements, head, head + newSpace, null);
129	>	head += newSpace;
130	>	}
131	>	// checkInvariants();
132	>	}
133	>
134	>	/** Capacity calculation for edge conditions, especially overflow. */
135	>	private int newCapacity(int needed, int jump) {
136	>	final int oldCapacity = elements.length, minCapacity;
137	>	if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
138	>	if (minCapacity < 0)
139	>	throw new IllegalStateException("Sorry, deque too big");
140	>	return Integer.MAX_VALUE;
141	>	}
142	>	if (needed > jump)
143	>	return minCapacity;
144	>	return (oldCapacity + jump - MAX_ARRAY_SIZE < 0)
145	>	? oldCapacity + jump
146	>	: MAX_ARRAY_SIZE;
147	>	}
148
149		/**
150	<	* Allocates empty array to hold the given number of elements.
151	<	*
152	<	* @param numElements  the number of elements to hold
153	<	*/
154	<	private void allocateElements(int numElements) {
155	<	int initialCapacity = MIN_INITIAL_CAPACITY;
156	<	// Find the best power of two to hold elements.
157	<	// Tests "<=" because arrays aren't kept full.
158	<	if (numElements >= initialCapacity) {
159	<	initialCapacity = numElements;
160	<	initialCapacity |= (initialCapacity >>>  1);
106	<	initialCapacity |= (initialCapacity >>>  2);
107	<	initialCapacity |= (initialCapacity >>>  4);
108	<	initialCapacity |= (initialCapacity >>>  8);
109	<	initialCapacity |= (initialCapacity >>> 16);
110	<	initialCapacity++;
111	<
112	<	if (initialCapacity < 0)   // Too many elements, must back off
113	<	initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements
114	<	}
115	<	elements = new Object[initialCapacity];
150	>	* Increases the internal storage of this collection, if necessary,
151	>	* to ensure that it can hold at least the given number of elements.
152	>	*
153	>	* @param minCapacity the desired minimum capacity
154	>	* @since TBD
155	>	*/
156	>	/* public */ void ensureCapacity(int minCapacity) {
157	>	int needed;
158	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
159	>	grow(needed);
160	>	// checkInvariants();
161		}
162
163		/**
164	<	* Doubles the capacity of this deque.  Call only when full, i.e.,
165	<	* when head and tail have wrapped around to become equal.
166	<	*/
167	<	private void doubleCapacity() {
168	<	assert head == tail;
169	<	int p = head;
170	<	int n = elements.length;
171	<	int r = n - p; // number of elements to the right of p
172	<	int newCapacity = n << 1;
173	<	if (newCapacity < 0)
174	<	throw new IllegalStateException("Sorry, deque too big");
175	<	Object[] a = new Object[newCapacity];
131	<	System.arraycopy(elements, p, a, 0, r);
132	<	System.arraycopy(elements, 0, a, r, p);
133	<	elements = a;
134	<	head = 0;
135	<	tail = n;
164	>	* Minimizes the internal storage of this collection.
165	>	*
166	>	* @since TBD
167	>	*/
168	>	/* public */ void trimToSize() {
169	>	int size;
170	>	if ((size = size()) + 1 < elements.length) {
171	>	elements = toArray(new Object[size + 1]);
172	>	head = 0;
173	>	tail = size;
174	>	}
175	>	// checkInvariants();
176		}
177
178		/**
#	Line 147 | Line 187 | public class ArrayDeque<E> extends Abstr
187		* Constructs an empty array deque with an initial capacity
188		* sufficient to hold the specified number of elements.
189		*
190	<	* @param numElements  lower bound on initial capacity of the deque
190	>	* @param numElements lower bound on initial capacity of the deque
191		*/
192		public ArrayDeque(int numElements) {
193	<	allocateElements(numElements);
193	>	elements =
194	>	new Object[(numElements < 1) ? 1 :
195	>	(numElements == Integer.MAX_VALUE) ? Integer.MAX_VALUE :
196	>	numElements + 1];
197		}
198
199		/**
#	Line 164 | Line 207 | public class ArrayDeque<E> extends Abstr
207		* @throws NullPointerException if the specified collection is null
208		*/
209		public ArrayDeque(Collection<? extends E> c) {
210	<	allocateElements(c.size());
210	>	this(c.size());
211		addAll(c);
212		}
213
214	+	/**
215	+	* Increments i, mod modulus.
216	+	* Precondition and postcondition: 0 <= i < modulus.
217	+	*/
218	+	static final int inc(int i, int modulus) {
219	+	if (++i >= modulus) i = 0;
220	+	return i;
221	+	}
222	+
223	+	/**
224	+	* Decrements i, mod modulus.
225	+	* Precondition and postcondition: 0 <= i < modulus.
226	+	*/
227	+	static final int dec(int i, int modulus) {
228	+	if (--i < 0) i = modulus - 1;
229	+	return i;
230	+	}
231	+
232	+	/**
233	+	* Circularly adds the given distance to index i, mod modulus.
234	+	* Precondition: 0 <= i < modulus, 0 <= distance <= modulus.
235	+	* @return index 0 <= i < modulus
236	+	*/
237	+	static final int add(int i, int distance, int modulus) {
238	+	if ((i += distance) - modulus >= 0) distance -= modulus;
239	+	return i;
240	+	}
241	+
242	+	/**
243	+	* Subtracts j from i, mod modulus.
244	+	* Index i must be logically ahead of index j.
245	+	* Precondition: 0 <= i < modulus, 0 <= j < modulus.
246	+	* @return the "circular distance" from j to i; corner case i == j
247	+	* is diambiguated to "empty", returning 0.
248	+	*/
249	+	static final int sub(int i, int j, int modulus) {
250	+	if ((i -= j) < 0) i += modulus;
251	+	return i;
252	+	}
253	+
254	+	/**
255	+	* Returns element at array index i.
256	+	* This is a slight abuse of generics, accepted by javac.
257	+	*/
258	+	@SuppressWarnings("unchecked")
259	+	static final <E> E elementAt(Object[] es, int i) {
260	+	return (E) es[i];
261	+	}
262	+
263	+	/**
264	+	* A version of elementAt that checks for null elements.
265	+	* This check doesn't catch all possible comodifications,
266	+	* but does catch ones that corrupt traversal.
267	+	*/
268	+	static final <E> E nonNullElementAt(Object[] es, int i) {
269	+	@SuppressWarnings("unchecked") E e = (E) es[i];
270	+	if (e == null)
271	+	throw new ConcurrentModificationException();
272	+	return e;
273	+	}
274	+
275		// The main insertion and extraction methods are addFirst,
276		// addLast, pollFirst, pollLast. The other methods are defined in
277		// terms of these.
#	Line 181 | Line 285 | public class ArrayDeque<E> extends Abstr
285		public void addFirst(E e) {
286		if (e == null)
287		throw new NullPointerException();
288	<	elements[head = (head - 1) & (elements.length - 1)] = e;
288	>	final Object[] es = elements;
289	>	es[head = dec(head, es.length)] = e;
290		if (head == tail)
291	<	doubleCapacity();
291	>	grow(1);
292	>	// checkInvariants();
293		}
294
295		/**
#	Line 197 | Line 303 | public class ArrayDeque<E> extends Abstr
303		public void addLast(E e) {
304		if (e == null)
305		throw new NullPointerException();
306	<	elements[tail] = e;
307	<	if ( (tail = (tail + 1) & (elements.length - 1)) == head)
308	<	doubleCapacity();
306	>	final Object[] es = elements;
307	>	es[tail] = e;
308	>	if (head == (tail = inc(tail, es.length)))
309	>	grow(1);
310	>	// checkInvariants();
311	>	}
312	>
313	>	/**
314	>	* Adds all of the elements in the specified collection at the end
315	>	* of this deque, as if by calling {@link #addLast} on each one,
316	>	* in the order that they are returned by the collection's
317	>	* iterator.
318	>	*
319	>	* @param c the elements to be inserted into this deque
320	>	* @return {@code true} if this deque changed as a result of the call
321	>	* @throws NullPointerException if the specified collection or any
322	>	*         of its elements are null
323	>	*/
324	>	public boolean addAll(Collection<? extends E> c) {
325	>	final int s, needed;
326	>	if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0)
327	>	grow(needed);
328	>	c.forEach(this::addLast);
329	>	// checkInvariants();
330	>	return size() > s;
331		}
332
333		/**
#	Line 230 | Line 358 | public class ArrayDeque<E> extends Abstr
358		* @throws NoSuchElementException {@inheritDoc}
359		*/
360		public E removeFirst() {
361	<	E x = pollFirst();
362	<	if (x == null)
361	>	E e = pollFirst();
362	>	if (e == null)
363		throw new NoSuchElementException();
364	<	return x;
364	>	// checkInvariants();
365	>	return e;
366		}
367
368		/**
369		* @throws NoSuchElementException {@inheritDoc}
370		*/
371		public E removeLast() {
372	<	E x = pollLast();
373	<	if (x == null)
372	>	E e = pollLast();
373	>	if (e == null)
374		throw new NoSuchElementException();
375	<	return x;
375	>	// checkInvariants();
376	>	return e;
377		}
378
379		public E pollFirst() {
380	<	int h = head;
381	<	@SuppressWarnings("unchecked")
382	<	E result = (E) elements[h];
383	<	// Element is null if deque empty
384	<	if (result == null)
385	<	return null;
386	<	elements[h] = null;     // Must null out slot
387	<	head = (h + 1) & (elements.length - 1);
388	<	return result;
380	>	final Object[] es;
381	>	final int h;
382	>	E e = elementAt(es = elements, h = head);
383	>	if (e != null) {
384	>	es[h] = null;
385	>	head = inc(h, es.length);
386	>	}
387	>	// checkInvariants();
388	>	return e;
389		}
390
391		public E pollLast() {
392	<	int t = (tail - 1) & (elements.length - 1);
393	<	@SuppressWarnings("unchecked")
394	<	E result = (E) elements[t];
395	<	if (result == null)
396	<	return null;
397	<	elements[t] = null;
398	<	tail = t;
269	<	return result;
392	>	final Object[] es;
393	>	final int t;
394	>	E e = elementAt(es = elements, t = dec(tail, es.length));
395	>	if (e != null)
396	>	es[tail = t] = null;
397	>	// checkInvariants();
398	>	return e;
399		}
400
401		/**
402		* @throws NoSuchElementException {@inheritDoc}
403		*/
404		public E getFirst() {
405	<	@SuppressWarnings("unchecked")
406	<	E result = (E) elements[head];
278	<	if (result == null)
405	>	E e = elementAt(elements, head);
406	>	if (e == null)
407		throw new NoSuchElementException();
408	<	return result;
408	>	// checkInvariants();
409	>	return e;
410		}
411
412		/**
413		* @throws NoSuchElementException {@inheritDoc}
414		*/
415		public E getLast() {
416	<	@SuppressWarnings("unchecked")
417	<	E result = (E) elements[(tail - 1) & (elements.length - 1)];
418	<	if (result == null)
416	>	final Object[] es = elements;
417	>	E e = elementAt(es, dec(tail, es.length));
418	>	if (e == null)
419		throw new NoSuchElementException();
420	<	return result;
420	>	// checkInvariants();
421	>	return e;
422		}
423
294	–	@SuppressWarnings("unchecked")
424		public E peekFirst() {
425	<	// elements[head] is null if deque empty
426	<	return (E) elements[head];
425	>	// checkInvariants();
426	>	return elementAt(elements, head);
427		}
428
300	–	@SuppressWarnings("unchecked")
429		public E peekLast() {
430	<	return (E) elements[(tail - 1) & (elements.length - 1)];
430	>	// checkInvariants();
431	>	final Object[] es;
432	>	return elementAt(es = elements, dec(tail, es.length));
433		}
434
435		/**
#	Line 315 | Line 445 | public class ArrayDeque<E> extends Abstr
445		* @return {@code true} if the deque contained the specified element
446		*/
447		public boolean removeFirstOccurrence(Object o) {
448	<	if (o == null)
449	<	return false;
450	<	int mask = elements.length - 1;
451	<	int i = head;
452	<	Object x;
453	<	while ( (x = elements[i]) != null) {
454	<	if (o.equals(x)) {
455	<	delete(i);
456	<	return true;
448	>	if (o != null) {
449	>	final Object[] es = elements;
450	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
451	>	; i = 0, to = end) {
452	>	for (; i < to; i++)
453	>	if (o.equals(es[i])) {
454	>	delete(i);
455	>	return true;
456	>	}
457	>	if (to == end) break;
458		}
328	–	i = (i + 1) & mask;
459		}
460		return false;
461		}
#	Line 343 | Line 473 | public class ArrayDeque<E> extends Abstr
473		* @return {@code true} if the deque contained the specified element
474		*/
475		public boolean removeLastOccurrence(Object o) {
476	<	if (o == null)
477	<	return false;
478	<	int mask = elements.length - 1;
479	<	int i = (tail - 1) & mask;
480	<	Object x;
481	<	while ( (x = elements[i]) != null) {
482	<	if (o.equals(x)) {
483	<	delete(i);
484	<	return true;
476	>	if (o != null) {
477	>	final Object[] es = elements;
478	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
479	>	; i = es.length, to = end) {
480	>	for (i--; i > to - 1; i--)
481	>	if (o.equals(es[i])) {
482	>	delete(i);
483	>	return true;
484	>	}
485	>	if (to == end) break;
486		}
356	–	i = (i - 1) & mask;
487		}
488		return false;
489		}
#	Line 472 | Line 602 | public class ArrayDeque<E> extends Abstr
602		return removeFirst();
603		}
604
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;
481	–	}
482	–
605		/**
606	<	* Removes the element at the specified position in the elements array,
607	<	* adjusting head and tail as necessary.  This can result in motion of
608	<	* elements backwards or forwards in the array.
606	>	* Removes the element at the specified position in the elements array.
607	>	* This can result in forward or backwards motion of array elements.
608	>	* We optimize for least element motion.
609		*
610		* <p>This method is called delete rather than remove to emphasize
611		* that its semantics differ from those of {@link List#remove(int)}.
612		*
613	<	* @return true if elements moved backwards
613	>	* @return true if elements near tail moved backwards
614		*/
615	<	private boolean delete(int i) {
616	<	checkInvariants();
617	<	final Object[] elements = this.elements;
618	<	final int mask = elements.length - 1;
619	<	final int h = head;
620	<	final int t = tail;
621	<	final int front = (i - h) & mask;
622	<	final int back  = (t - i) & mask;
623	<
502	<	// Invariant: head <= i < tail mod circularity
503	<	if (front >= ((t - h) & mask))
504	<	throw new ConcurrentModificationException();
505	<
506	<	// Optimize for least element motion
615	>	boolean delete(int i) {
616	>	// checkInvariants();
617	>	final Object[] es = elements;
618	>	final int capacity = es.length;
619	>	final int h, t;
620	>	// number of elements before to-be-deleted elt
621	>	final int front = sub(i, h = head, capacity);
622	>	// number of elements after to-be-deleted elt
623	>	final int back = sub(t = tail, i, capacity) - 1;
624		if (front < back) {
625	+	// move front elements forwards
626		if (h <= i) {
627	<	System.arraycopy(elements, h, elements, h + 1, front);
627	>	System.arraycopy(es, h, es, h + 1, front);
628		} else { // Wrap around
629	<	System.arraycopy(elements, 0, elements, 1, i);
630	<	elements[0] = elements[mask];
631	<	System.arraycopy(elements, h, elements, h + 1, mask - h);
629	>	System.arraycopy(es, 0, es, 1, i);
630	>	es[0] = es[capacity - 1];
631	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
632		}
633	<	elements[h] = null;
634	<	head = (h + 1) & mask;
633	>	es[h] = null;
634	>	head = inc(h, capacity);
635	>	// checkInvariants();
636		return false;
637		} else {
638	<	if (i < t) { // Copy the null tail as well
639	<	System.arraycopy(elements, i + 1, elements, i, back);
640	<	tail = t - 1;
638	>	// move back elements backwards
639	>	tail = dec(t, capacity);
640	>	if (i <= tail) {
641	>	System.arraycopy(es, i + 1, es, i, back);
642		} else { // Wrap around
643	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
644	<	elements[mask] = elements[0];
645	<	System.arraycopy(elements, 1, elements, 0, t);
526	<	tail = (t - 1) & mask;
643	>	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
644	>	es[capacity - 1] = es[0];
645	>	System.arraycopy(es, 1, es, 0, t - 1);
646		}
647	+	es[tail] = null;
648	+	// checkInvariants();
649		return true;
650		}
651		}
#	Line 537 | Line 658 | public class ArrayDeque<E> extends Abstr
658		* @return the number of elements in this deque
659		*/
660		public int size() {
661	<	return (tail - head) & (elements.length - 1);
661	>	return sub(tail, head, elements.length);
662		}
663
664		/**
#	Line 566 | Line 687 | public class ArrayDeque<E> extends Abstr
687		}
688
689		private class DeqIterator implements Iterator<E> {
690	<	/**
691	<	* Index of element to be returned by subsequent call to next.
571	<	*/
572	<	private int cursor = head;
690	>	/** Index of element to be returned by subsequent call to next. */
691	>	int cursor;
692
693	<	/**
694	<	* Tail recorded at construction (also in remove), to stop
576	<	* iterator and also to check for comodification.
577	<	*/
578	<	private int fence = tail;
693	>	/** Number of elements yet to be returned. */
694	>	int remaining = size();
695
696		/**
697		* Index of element returned by most recent call to next.
698		* Reset to -1 if element is deleted by a call to remove.
699		*/
700	<	private int lastRet = -1;
700	>	int lastRet = -1;
701	>
702	>	DeqIterator() { cursor = head; }
703
704	<	public boolean hasNext() {
705	<	return cursor != fence;
704	>	public final boolean hasNext() {
705	>	return remaining > 0;
706		}
707
708		public E next() {
709	<	if (cursor == fence)
709	>	if (remaining <= 0)
710		throw new NoSuchElementException();
711	<	@SuppressWarnings("unchecked")
712	<	E result = (E) elements[cursor];
595	<	// This check doesn't catch all possible comodifications,
596	<	// but does catch the ones that corrupt traversal
597	<	if (tail != fence || result == null)
598	<	throw new ConcurrentModificationException();
711	>	final Object[] es = elements;
712	>	E e = nonNullElementAt(es, cursor);
713		lastRet = cursor;
714	<	cursor = (cursor + 1) & (elements.length - 1);
715	<	return result;
714	>	cursor = inc(cursor, es.length);
715	>	remaining--;
716	>	return e;
717	>	}
718	>
719	>	void postDelete(boolean leftShifted) {
720	>	if (leftShifted)
721	>	cursor = dec(cursor, elements.length);
722		}
723
724	<	public void remove() {
724	>	public final void remove() {
725		if (lastRet < 0)
726		throw new IllegalStateException();
727	<	if (delete(lastRet)) { // if left-shifted, undo increment in next()
608	<	cursor = (cursor - 1) & (elements.length - 1);
609	<	fence = tail;
610	<	}
727	>	postDelete(delete(lastRet));
728		lastRet = -1;
729		}
730	+
731	+	public void forEachRemaining(Consumer<? super E> action) {
732	+	Objects.requireNonNull(action);
733	+	int r;
734	+	if ((r = remaining) <= 0)
735	+	return;
736	+	remaining = 0;
737	+	final Object[] es = elements;
738	+	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
739	+	throw new ConcurrentModificationException();
740	+	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
741	+	; i = 0, to = end) {
742	+	for (; i < to; i++)
743	+	action.accept(elementAt(es, i));
744	+	if (to == end) {
745	+	if (end != tail)
746	+	throw new ConcurrentModificationException();
747	+	lastRet = dec(end, es.length);
748	+	break;
749	+	}
750	+	}
751	+	}
752	+	}
753	+
754	+	private class DescendingIterator extends DeqIterator {
755	+	DescendingIterator() { cursor = dec(tail, elements.length); }
756	+
757	+	public final E next() {
758	+	if (remaining <= 0)
759	+	throw new NoSuchElementException();
760	+	final Object[] es = elements;
761	+	E e = nonNullElementAt(es, cursor);
762	+	lastRet = cursor;
763	+	cursor = dec(cursor, es.length);
764	+	remaining--;
765	+	return e;
766	+	}
767	+
768	+	void postDelete(boolean leftShifted) {
769	+	if (!leftShifted)
770	+	cursor = inc(cursor, elements.length);
771	+	}
772	+
773	+	public final void forEachRemaining(Consumer<? super E> action) {
774	+	Objects.requireNonNull(action);
775	+	int r;
776	+	if ((r = remaining) <= 0)
777	+	return;
778	+	remaining = 0;
779	+	final Object[] es = elements;
780	+	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
781	+	throw new ConcurrentModificationException();
782	+	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
783	+	; i = es.length - 1, to = end) {
784	+	// hotspot generates faster code than for: i >= to !
785	+	for (; i > to - 1; i--)
786	+	action.accept(elementAt(es, i));
787	+	if (to == end) {
788	+	if (end != head)
789	+	throw new ConcurrentModificationException();
790	+	lastRet = end;
791	+	break;
792	+	}
793	+	}
794	+	}
795		}
796
797		/**
798	<	* This class is nearly a mirror-image of DeqIterator, using tail
799	<	* instead of head for initial cursor, and head instead of tail
800	<	* for fence.
801	<	*/
802	<	private class DescendingIterator implements Iterator<E> {
803	<	private int cursor = tail;
804	<	private int fence = head;
805	<	private int lastRet = -1;
798	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
799	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
800	>	* deque.
801	>	*
802	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
803	>	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
804	>	* {@link Spliterator#NONNULL}.  Overriding implementations should document
805	>	* the reporting of additional characteristic values.
806	>	*
807	>	* @return a {@code Spliterator} over the elements in this deque
808	>	* @since 1.8
809	>	*/
810	>	public Spliterator<E> spliterator() {
811	>	return new DeqSpliterator();
812	>	}
813	>
814	>	final class DeqSpliterator implements Spliterator<E> {
815	>	private int fence;      // -1 until first use
816	>	private int cursor;     // current index, modified on traverse/split
817
818	<	public boolean hasNext() {
819	<	return cursor != fence;
818	>	/** Constructs late-binding spliterator over all elements. */
819	>	DeqSpliterator() {
820	>	this.fence = -1;
821		}
822
823	<	public E next() {
824	<	if (cursor == fence)
825	<	throw new NoSuchElementException();
826	<	cursor = (cursor - 1) & (elements.length - 1);
633	<	@SuppressWarnings("unchecked")
634	<	E result = (E) elements[cursor];
635	<	if (head != fence || result == null)
636	<	throw new ConcurrentModificationException();
637	<	lastRet = cursor;
638	<	return result;
823	>	/** Constructs spliterator over the given range. */
824	>	DeqSpliterator(int origin, int fence) {
825	>	this.cursor = origin;
826	>	this.fence = fence;
827		}
828
829	<	public void remove() {
830	<	if (lastRet < 0)
831	<	throw new IllegalStateException();
832	<	if (!delete(lastRet)) {
833	<	cursor = (cursor + 1) & (elements.length - 1);
834	<	fence = head;
829	>	/** Ensures late-binding initialization; then returns fence. */
830	>	private int getFence() { // force initialization
831	>	int t;
832	>	if ((t = fence) < 0) {
833	>	t = fence = tail;
834	>	cursor = head;
835	>	}
836	>	return t;
837	>	}
838	>
839	>	public DeqSpliterator trySplit() {
840	>	final Object[] es = elements;
841	>	final int i, n;
842	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
843	>	? null
844	>	: new DeqSpliterator(i, cursor = add(i, n, es.length));
845	>	}
846	>
847	>	public void forEachRemaining(Consumer<? super E> action) {
848	>	if (action == null)
849	>	throw new NullPointerException();
850	>	final int end = getFence(), cursor = this.cursor;
851	>	final Object[] es = elements;
852	>	if (cursor != end) {
853	>	this.cursor = end;
854	>	// null check at both ends of range is sufficient
855	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
856	>	throw new ConcurrentModificationException();
857	>	for (int i = cursor, to = (i <= end) ? end : es.length;
858	>	; i = 0, to = end) {
859	>	for (; i < to; i++)
860	>	action.accept(elementAt(es, i));
861	>	if (to == end) break;
862	>	}
863	>	}
864	>	}
865	>
866	>	public boolean tryAdvance(Consumer<? super E> action) {
867	>	Objects.requireNonNull(action);
868	>	final Object[] es = elements;
869	>	if (fence < 0) { fence = tail; cursor = head; } // late-binding
870	>	final int i;
871	>	if ((i = cursor) == fence)
872	>	return false;
873	>	E e = nonNullElementAt(es, i);
874	>	cursor = inc(i, es.length);
875	>	action.accept(e);
876	>	return true;
877	>	}
878	>
879	>	public long estimateSize() {
880	>	return sub(getFence(), cursor, elements.length);
881	>	}
882	>
883	>	public int characteristics() {
884	>	return Spliterator.NONNULL
885	>	| Spliterator.ORDERED
886	>	| Spliterator.SIZED
887	>	| Spliterator.SUBSIZED;
888	>	}
889	>	}
890	>
891	>	public void forEach(Consumer<? super E> action) {
892	>	Objects.requireNonNull(action);
893	>	final Object[] es = elements;
894	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
895	>	; i = 0, to = end) {
896	>	for (; i < to; i++)
897	>	action.accept(elementAt(es, i));
898	>	if (to == end) {
899	>	if (end != tail) throw new ConcurrentModificationException();
900	>	break;
901	>	}
902	>	}
903	>	// checkInvariants();
904	>	}
905	>
906	>	/**
907	>	* Replaces each element of this deque with the result of applying the
908	>	* operator to that element, as specified by {@link List#replaceAll}.
909	>	*
910	>	* @param operator the operator to apply to each element
911	>	* @since TBD
912	>	*/
913	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
914	>	Objects.requireNonNull(operator);
915	>	final Object[] es = elements;
916	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
917	>	; i = 0, to = end) {
918	>	for (; i < to; i++)
919	>	es[i] = operator.apply(elementAt(es, i));
920	>	if (to == end) {
921	>	if (end != tail) throw new ConcurrentModificationException();
922	>	break;
923	>	}
924	>	}
925	>	// checkInvariants();
926	>	}
927	>
928	>	/**
929	>	* @throws NullPointerException {@inheritDoc}
930	>	*/
931	>	public boolean removeIf(Predicate<? super E> filter) {
932	>	Objects.requireNonNull(filter);
933	>	return bulkRemove(filter);
934	>	}
935	>
936	>	/**
937	>	* @throws NullPointerException {@inheritDoc}
938	>	*/
939	>	public boolean removeAll(Collection<?> c) {
940	>	Objects.requireNonNull(c);
941	>	return bulkRemove(e -> c.contains(e));
942	>	}
943	>
944	>	/**
945	>	* @throws NullPointerException {@inheritDoc}
946	>	*/
947	>	public boolean retainAll(Collection<?> c) {
948	>	Objects.requireNonNull(c);
949	>	return bulkRemove(e -> !c.contains(e));
950	>	}
951	>
952	>	/** Implementation of bulk remove methods. */
953	>	private boolean bulkRemove(Predicate<? super E> filter) {
954	>	// checkInvariants();
955	>	final Object[] es = elements;
956	>	// Optimize for initial run of survivors
957	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
958	>	; i = 0, to = end) {
959	>	for (; i < to; i++)
960	>	if (filter.test(elementAt(es, i)))
961	>	return bulkRemoveModified(filter, i);
962	>	if (to == end) {
963	>	if (end != tail) throw new ConcurrentModificationException();
964	>	break;
965	>	}
966	>	}
967	>	return false;
968	>	}
969	>
970	>	// A tiny bit set implementation
971	>
972	>	private static long[] nBits(int n) {
973	>	return new long[((n - 1) >> 6) + 1];
974	>	}
975	>	private static void setBit(long[] bits, int i) {
976	>	bits[i >> 6] |= 1L << i;
977	>	}
978	>	private static boolean isClear(long[] bits, int i) {
979	>	return (bits[i >> 6] & (1L << i)) == 0;
980	>	}
981	>
982	>	/**
983	>	* Helper for bulkRemove, in case of at least one deletion.
984	>	* Tolerate predicates that reentrantly access the collection for
985	>	* read (but writers still get CME), so traverse once to find
986	>	* elements to delete, a second pass to physically expunge.
987	>	*
988	>	* @param beg valid index of first element to be deleted
989	>	*/
990	>	private boolean bulkRemoveModified(
991	>	Predicate<? super E> filter, final int beg) {
992	>	final Object[] es = elements;
993	>	final int capacity = es.length;
994	>	final int end = tail;
995	>	final long[] deathRow = nBits(sub(end, beg, capacity));
996	>	deathRow[0] = 1L;   // set bit 0
997	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
998	>	; i = 0, to = end, k -= capacity) {
999	>	for (; i < to; i++)
1000	>	if (filter.test(elementAt(es, i)))
1001	>	setBit(deathRow, i - k);
1002	>	if (to == end) break;
1003	>	}
1004	>	// a two-finger traversal, with hare i reading, tortoise w writing
1005	>	int w = beg;
1006	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1007	>	; w = 0) { // w rejoins i on second leg
1008	>	// In this loop, i and w are on the same leg, with i > w
1009	>	for (; i < to; i++)
1010	>	if (isClear(deathRow, i - k))
1011	>	es[w++] = es[i];
1012	>	if (to == end) break;
1013	>	// In this loop, w is on the first leg, i on the second
1014	>	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1015	>	if (isClear(deathRow, i - k))
1016	>	es[w++] = es[i];
1017	>	if (i >= to) {
1018	>	if (w == capacity) w = 0; // "corner" case
1019	>	break;
1020		}
648	–	lastRet = -1;
1021		}
1022	+	if (end != tail) throw new ConcurrentModificationException();
1023	+	circularClear(es, tail = w, end);
1024	+	// checkInvariants();
1025	+	return true;
1026		}
1027
1028		/**
#	Line 658 | Line 1034 | public class ArrayDeque<E> extends Abstr
1034		* @return {@code true} if this deque contains the specified element
1035		*/
1036		public boolean contains(Object o) {
1037	<	if (o == null)
1038	<	return false;
1039	<	int mask = elements.length - 1;
1040	<	int i = head;
1041	<	Object x;
1042	<	while ( (x = elements[i]) != null) {
1043	<	if (o.equals(x))
1044	<	return true;
1045	<	i = (i + 1) & mask;
1037	>	if (o != null) {
1038	>	final Object[] es = elements;
1039	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1040	>	; i = 0, to = end) {
1041	>	for (; i < to; i++)
1042	>	if (o.equals(es[i]))
1043	>	return true;
1044	>	if (to == end) break;
1045	>	}
1046		}
1047		return false;
1048		}
#	Line 693 | Line 1069 | public class ArrayDeque<E> extends Abstr
1069		* The deque will be empty after this call returns.
1070		*/
1071		public void clear() {
1072	<	int h = head;
1073	<	int t = tail;
1074	<	if (h != t) { // clear all cells
1075	<	head = tail = 0;
1076	<	int i = h;
1077	<	int mask = elements.length - 1;
1078	<	do {
1079	<	elements[i] = null;
1080	<	i = (i + 1) & mask;
1081	<	} while (i != t);
1072	>	circularClear(elements, head, tail);
1073	>	head = tail = 0;
1074	>	// checkInvariants();
1075	>	}
1076	>
1077	>	/**
1078	>	* Nulls out slots starting at array index i, upto index end.
1079	>	*/
1080	>	private static void circularClear(Object[] es, int i, int end) {
1081	>	for (int to = (i <= end) ? end : es.length;
1082	>	; i = 0, to = end) {
1083	>	Arrays.fill(es, i, to, null);
1084	>	if (to == end) break;
1085		}
1086		}
1087
#	Line 720 | Line 1099 | public class ArrayDeque<E> extends Abstr
1099		* @return an array containing all of the elements in this deque
1100		*/
1101		public Object[] toArray() {
1102	<	final int head = this.head;
1103	<	final int tail = this.tail;
1104	<	boolean wrap = (tail < head);
1105	<	int end = wrap ? tail + elements.length : tail;
1106	<	Object[] a = Arrays.copyOfRange(elements, head, end);
1107	<	if (wrap)
1108	<	System.arraycopy(elements, 0, a, elements.length - head, tail);
1102	>	return toArray(Object[].class);
1103	>	}
1104	>
1105	>	private <T> T[] toArray(Class<T[]> klazz) {
1106	>	final Object[] es = elements;
1107	>	final T[] a;
1108	>	final int head = this.head, tail = this.tail, end;
1109	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1110	>	// Uses null extension feature of copyOfRange
1111	>	a = Arrays.copyOfRange(es, head, end, klazz);
1112	>	} else {
1113	>	// integer overflow!
1114	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1115	>	System.arraycopy(es, head, a, 0, es.length - head);
1116	>	}
1117	>	if (end != tail)
1118	>	System.arraycopy(es, 0, a, es.length - head, tail);
1119		return a;
1120		}
1121
#	Line 752 | Line 1141 | public class ArrayDeque<E> extends Abstr
1141		* The following code can be used to dump the deque into a newly
1142		* allocated array of {@code String}:
1143		*
1144	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
1144	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
1145		*
1146		* Note that {@code toArray(new Object[0])} is identical in function to
1147		* {@code toArray()}.
#	Line 768 | Line 1157 | public class ArrayDeque<E> extends Abstr
1157		*/
1158		@SuppressWarnings("unchecked")
1159		public <T> T[] toArray(T[] a) {
1160	<	final int head = this.head;
1161	<	final int tail = this.tail;
1162	<	boolean wrap = (tail < head);
1163	<	int size = (tail - head) + (wrap ? elements.length : 0);
1164	<	int firstLeg = size - (wrap ? tail : 0);
1165	<	int len = a.length;
1166	<	if (size > len) {
1167	<	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;
1160	>	final int size;
1161	>	if ((size = size()) > a.length)
1162	>	return toArray((Class<T[]>) a.getClass());
1163	>	final Object[] es = elements;
1164	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1165	>	; i = 0, len = tail) {
1166	>	System.arraycopy(es, i, a, j, len);
1167	>	if ((j += len) == size) break;
1168		}
1169	<	if (wrap)
1170	<	System.arraycopy(elements, 0, a, firstLeg, tail);
1169	>	if (size < a.length)
1170	>	a[size] = null;
1171		return a;
1172		}
1173
#	Line 811 | Line 1195 | public class ArrayDeque<E> extends Abstr
1195		* Saves this deque to a stream (that is, serializes it).
1196		*
1197		* @param s the stream
1198	+	* @throws java.io.IOException if an I/O error occurs
1199		* @serialData The current size ({@code int}) of the deque,
1200		* followed by all of its elements (each an object reference) in
1201		* first-to-last order.
#	Line 823 | Line 1208 | public class ArrayDeque<E> extends Abstr
1208		s.writeInt(size());
1209
1210		// Write out elements in order.
1211	<	int mask = elements.length - 1;
1212	<	for (int i = head; i != tail; i = (i + 1) & mask)
1213	<	s.writeObject(elements[i]);
1211	>	final Object[] es = elements;
1212	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1213	>	; i = 0, to = end) {
1214	>	for (; i < to; i++)
1215	>	s.writeObject(es[i]);
1216	>	if (to == end) break;
1217	>	}
1218		}
1219
1220		/**
1221		* Reconstitutes this deque from a stream (that is, deserializes it).
1222		* @param s the stream
1223	+	* @throws ClassNotFoundException if the class of a serialized object
1224	+	*         could not be found
1225	+	* @throws java.io.IOException if an I/O error occurs
1226		*/
1227		private void readObject(java.io.ObjectInputStream s)
1228		throws java.io.IOException, ClassNotFoundException {
#	Line 838 | Line 1230 | public class ArrayDeque<E> extends Abstr
1230
1231		// Read in size and allocate array
1232		int size = s.readInt();
1233	<	allocateElements(size);
1234	<	head = 0;
843	<	tail = size;
1233	>	elements = new Object[size + 1];
1234	>	this.tail = size;
1235
1236		// Read in all elements in the proper order.
1237		for (int i = 0; i < size; i++)
1238		elements[i] = s.readObject();
1239		}
1240
1241	<	public Spliterator<E> spliterator() {
1242	<	return new DeqSpliterator<E>(this, -1, -1);
1243	<	}
1244	<
1245	<	static final class DeqSpliterator<E> implements Spliterator<E> {
1246	<	private final ArrayDeque<E> deq;
1247	<	private int fence;  // -1 until first use
1248	<	private int index;  // current index, modified on traverse/split
1249	<
1250	<	/** Creates new spliterator covering the given array and range */
1251	<	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
1252	<	this.deq = deq;
1253	<	this.index = origin;
1254	<	this.fence = fence;
1255	<	}
1256	<
1257	<	private int getFence() { // force initialization
1258	<	int t;
1259	<	if ((t = fence) < 0) {
869	<	t = fence = deq.tail;
870	<	index = deq.head;
871	<	}
872	<	return t;
873	<	}
874	<
875	<	public Spliterator<E> trySplit() {
876	<	int t = getFence(), h = index, n = deq.elements.length;
877	<	if (h != t && ((h + 1) & (n - 1)) != t) {
878	<	if (h > t)
879	<	t += n;
880	<	int m = ((h + t) >>> 1) & (n - 1);
881	<	return new DeqSpliterator<>(deq, h, index = m);
882	<	}
883	<	return null;
884	<	}
885	<
886	<	public void forEachRemaining(Consumer<? super E> consumer) {
887	<	if (consumer == null)
888	<	throw new NullPointerException();
889	<	Object[] a = deq.elements;
890	<	int m = a.length - 1, f = getFence(), i = index;
891	<	index = f;
892	<	while (i != f) {
893	<	@SuppressWarnings("unchecked") E e = (E)a[i];
894	<	i = (i + 1) & m;
895	<	if (e == null)
896	<	throw new ConcurrentModificationException();
897	<	consumer.accept(e);
898	<	}
899	<	}
900	<
901	<	public boolean tryAdvance(Consumer<? super E> consumer) {
902	<	if (consumer == null)
903	<	throw new NullPointerException();
904	<	Object[] a = deq.elements;
905	<	int m = a.length - 1, f = getFence(), i = index;
906	<	if (i != fence) {
907	<	@SuppressWarnings("unchecked") E e = (E)a[i];
908	<	index = (i + 1) & m;
909	<	if (e == null)
910	<	throw new ConcurrentModificationException();
911	<	consumer.accept(e);
912	<	return true;
913	<	}
914	<	return false;
915	<	}
916	<
917	<	public long estimateSize() {
918	<	int n = getFence() - index;
919	<	if (n < 0)
920	<	n += deq.elements.length;
921	<	return (long) n;
922	<	}
923	<
924	<	@Override
925	<	public int characteristics() {
926	<	return Spliterator.ORDERED | Spliterator.SIZED |
927	<	Spliterator.NONNULL | Spliterator.SUBSIZED;
1241	>	/** debugging */
1242	>	void checkInvariants() {
1243	>	// Use head and tail fields with empty slot at tail strategy.
1244	>	// head == tail disambiguates to "empty".
1245	>	try {
1246	>	int capacity = elements.length;
1247	>	// assert head >= 0 && head < capacity;
1248	>	// assert tail >= 0 && tail < capacity;
1249	>	// assert capacity > 0;
1250	>	// assert size() < capacity;
1251	>	// assert head == tail || elements[head] != null;
1252	>	// assert elements[tail] == null;
1253	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1254	>	} catch (Throwable t) {
1255	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1256	>	head, tail, elements.length);
1257	>	System.err.printf("elements=%s%n",
1258	>	Arrays.toString(elements));
1259	>	throw t;
1260		}
1261		}
1262

Diff Legend

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