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 1.55 by jsr166, Thu May 2 06:02:17 2013 UTC vs.
Revision 1.129 by jsr166, Wed May 31 19:01:08 2017 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 48 | Line 50 | import java.util.stream.Stream;
50		* Iterator} interfaces.
51		*
52		* <p>This class is a member of the
53	<	* <a href="{@docRoot}/../technotes/guides/collections/index.html">
53	>	* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
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	>	final Object[] es = elements = Arrays.copyOf(elements, newCapacity);
121	>	// Exceptionally, here tail == head needs to be disambiguated
122	>	if (tail < head || (tail == head && es[head] != null)) {
123	>	// wrap around; slide first leg forward to end of array
124	>	int newSpace = newCapacity - oldCapacity;
125	>	System.arraycopy(es, head,
126	>	es, head + newSpace,
127	>	oldCapacity - head);
128	>	for (int i = head, to = (head += newSpace); i < to; i++)
129	>	es[i] = null;
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) i -= 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 iterator.
317	>	*
318	>	* @param c the elements to be inserted into this deque
319	>	* @return {@code true} if this deque changed as a result of the call
320	>	* @throws NullPointerException if the specified collection or any
321	>	*         of its elements are null
322	>	*/
323	>	public boolean addAll(Collection<? extends E> c) {
324	>	final int s, needed;
325	>	if ((needed = (s = size()) + c.size() + 1 - elements.length) > 0)
326	>	grow(needed);
327	>	c.forEach(this::addLast);
328	>	// checkInvariants();
329	>	return size() > s;
330		}
331
332		/**
#	Line 230 | Line 357 | public class ArrayDeque<E> extends Abstr
357		* @throws NoSuchElementException {@inheritDoc}
358		*/
359		public E removeFirst() {
360	<	E x = pollFirst();
361	<	if (x == null)
360	>	E e = pollFirst();
361	>	if (e == null)
362		throw new NoSuchElementException();
363	<	return x;
363	>	// checkInvariants();
364	>	return e;
365		}
366
367		/**
368		* @throws NoSuchElementException {@inheritDoc}
369		*/
370		public E removeLast() {
371	<	E x = pollLast();
372	<	if (x == null)
371	>	E e = pollLast();
372	>	if (e == null)
373		throw new NoSuchElementException();
374	<	return x;
374	>	// checkInvariants();
375	>	return e;
376		}
377
378		public E pollFirst() {
379	<	int h = head;
380	<	@SuppressWarnings("unchecked")
381	<	E result = (E) elements[h];
382	<	// Element is null if deque empty
383	<	if (result == null)
384	<	return null;
385	<	elements[h] = null;     // Must null out slot
386	<	head = (h + 1) & (elements.length - 1);
387	<	return result;
379	>	final Object[] es;
380	>	final int h;
381	>	E e = elementAt(es = elements, h = head);
382	>	if (e != null) {
383	>	es[h] = null;
384	>	head = inc(h, es.length);
385	>	}
386	>	// checkInvariants();
387	>	return e;
388		}
389
390		public E pollLast() {
391	<	int t = (tail - 1) & (elements.length - 1);
392	<	@SuppressWarnings("unchecked")
393	<	E result = (E) elements[t];
394	<	if (result == null)
395	<	return null;
396	<	elements[t] = null;
397	<	tail = t;
269	<	return result;
391	>	final Object[] es;
392	>	final int t;
393	>	E e = elementAt(es = elements, t = dec(tail, es.length));
394	>	if (e != null)
395	>	es[tail = t] = null;
396	>	// checkInvariants();
397	>	return e;
398		}
399
400		/**
401		* @throws NoSuchElementException {@inheritDoc}
402		*/
403		public E getFirst() {
404	<	@SuppressWarnings("unchecked")
405	<	E result = (E) elements[head];
278	<	if (result == null)
404	>	E e = elementAt(elements, head);
405	>	if (e == null)
406		throw new NoSuchElementException();
407	<	return result;
407	>	// checkInvariants();
408	>	return e;
409		}
410
411		/**
412		* @throws NoSuchElementException {@inheritDoc}
413		*/
414		public E getLast() {
415	<	@SuppressWarnings("unchecked")
416	<	E result = (E) elements[(tail - 1) & (elements.length - 1)];
417	<	if (result == null)
415	>	final Object[] es = elements;
416	>	E e = elementAt(es, dec(tail, es.length));
417	>	if (e == null)
418		throw new NoSuchElementException();
419	<	return result;
419	>	// checkInvariants();
420	>	return e;
421		}
422
294	–	@SuppressWarnings("unchecked")
423		public E peekFirst() {
424	<	// elements[head] is null if deque empty
425	<	return (E) elements[head];
424	>	// checkInvariants();
425	>	return elementAt(elements, head);
426		}
427
300	–	@SuppressWarnings("unchecked")
428		public E peekLast() {
429	<	return (E) elements[(tail - 1) & (elements.length - 1)];
429	>	// checkInvariants();
430	>	final Object[] es;
431	>	return elementAt(es = elements, dec(tail, es.length));
432		}
433
434		/**
#	Line 315 | Line 444 | public class ArrayDeque<E> extends Abstr
444		* @return {@code true} if the deque contained the specified element
445		*/
446		public boolean removeFirstOccurrence(Object o) {
447	<	if (o == null)
448	<	return false;
449	<	int mask = elements.length - 1;
450	<	int i = head;
451	<	Object x;
452	<	while ( (x = elements[i]) != null) {
453	<	if (o.equals(x)) {
454	<	delete(i);
455	<	return true;
447	>	if (o != null) {
448	>	final Object[] es = elements;
449	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
450	>	; i = 0, to = end) {
451	>	for (; i < to; i++)
452	>	if (o.equals(es[i])) {
453	>	delete(i);
454	>	return true;
455	>	}
456	>	if (to == end) break;
457		}
328	–	i = (i + 1) & mask;
458		}
459		return false;
460		}
#	Line 343 | Line 472 | public class ArrayDeque<E> extends Abstr
472		* @return {@code true} if the deque contained the specified element
473		*/
474		public boolean removeLastOccurrence(Object o) {
475	<	if (o == null)
476	<	return false;
477	<	int mask = elements.length - 1;
478	<	int i = (tail - 1) & mask;
479	<	Object x;
480	<	while ( (x = elements[i]) != null) {
481	<	if (o.equals(x)) {
482	<	delete(i);
483	<	return true;
475	>	if (o != null) {
476	>	final Object[] es = elements;
477	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
478	>	; i = es.length, to = end) {
479	>	for (i--; i > to - 1; i--)
480	>	if (o.equals(es[i])) {
481	>	delete(i);
482	>	return true;
483	>	}
484	>	if (to == end) break;
485		}
356	–	i = (i - 1) & mask;
486		}
487		return false;
488		}
#	Line 390 | Line 519 | public class ArrayDeque<E> extends Abstr
519		/**
520		* Retrieves and removes the head of the queue represented by this deque.
521		*
522	<	* This method differs from {@link #poll poll} only in that it throws an
523	<	* exception if this deque is empty.
522	>	* This method differs from {@link #poll() poll()} only in that it
523	>	* throws an exception if this deque is empty.
524		*
525		* <p>This method is equivalent to {@link #removeFirst}.
526		*
#	Line 472 | Line 601 | public class ArrayDeque<E> extends Abstr
601		return removeFirst();
602		}
603
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	–
604		/**
605	<	* Removes the element at the specified position in the elements array,
606	<	* adjusting head and tail as necessary.  This can result in motion of
607	<	* elements backwards or forwards in the array.
605	>	* Removes the element at the specified position in the elements array.
606	>	* This can result in forward or backwards motion of array elements.
607	>	* We optimize for least element motion.
608		*
609		* <p>This method is called delete rather than remove to emphasize
610		* that its semantics differ from those of {@link List#remove(int)}.
611		*
612	<	* @return true if elements moved backwards
612	>	* @return true if elements near tail moved backwards
613		*/
614	<	private boolean delete(int i) {
615	<	checkInvariants();
616	<	final Object[] elements = this.elements;
617	<	final int mask = elements.length - 1;
618	<	final int h = head;
619	<	final int t = tail;
620	<	final int front = (i - h) & mask;
621	<	final int back  = (t - i) & mask;
622	<
502	<	// Invariant: head <= i < tail mod circularity
503	<	if (front >= ((t - h) & mask))
504	<	throw new ConcurrentModificationException();
505	<
506	<	// Optimize for least element motion
614	>	boolean delete(int i) {
615	>	// checkInvariants();
616	>	final Object[] es = elements;
617	>	final int capacity = es.length;
618	>	final int h, t;
619	>	// number of elements before to-be-deleted elt
620	>	final int front = sub(i, h = head, capacity);
621	>	// number of elements after to-be-deleted elt
622	>	final int back = sub(t = tail, i, capacity) - 1;
623		if (front < back) {
624	+	// move front elements forwards
625		if (h <= i) {
626	<	System.arraycopy(elements, h, elements, h + 1, front);
626	>	System.arraycopy(es, h, es, h + 1, front);
627		} else { // Wrap around
628	<	System.arraycopy(elements, 0, elements, 1, i);
629	<	elements[0] = elements[mask];
630	<	System.arraycopy(elements, h, elements, h + 1, mask - h);
628	>	System.arraycopy(es, 0, es, 1, i);
629	>	es[0] = es[capacity - 1];
630	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
631		}
632	<	elements[h] = null;
633	<	head = (h + 1) & mask;
632	>	es[h] = null;
633	>	head = inc(h, capacity);
634	>	// checkInvariants();
635		return false;
636		} else {
637	<	if (i < t) { // Copy the null tail as well
638	<	System.arraycopy(elements, i + 1, elements, i, back);
639	<	tail = t - 1;
637	>	// move back elements backwards
638	>	tail = dec(t, capacity);
639	>	if (i <= tail) {
640	>	System.arraycopy(es, i + 1, es, i, back);
641		} else { // Wrap around
642	<	System.arraycopy(elements, i + 1, elements, i, mask - i);
643	<	elements[mask] = elements[0];
644	<	System.arraycopy(elements, 1, elements, 0, t);
526	<	tail = (t - 1) & mask;
642	>	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
643	>	es[capacity - 1] = es[0];
644	>	System.arraycopy(es, 1, es, 0, t - 1);
645		}
646	+	es[tail] = null;
647	+	// checkInvariants();
648		return true;
649		}
650		}
#	Line 537 | Line 657 | public class ArrayDeque<E> extends Abstr
657		* @return the number of elements in this deque
658		*/
659		public int size() {
660	<	return (tail - head) & (elements.length - 1);
660	>	return sub(tail, head, elements.length);
661		}
662
663		/**
#	Line 566 | Line 686 | public class ArrayDeque<E> extends Abstr
686		}
687
688		private class DeqIterator implements Iterator<E> {
689	<	/**
690	<	* Index of element to be returned by subsequent call to next.
571	<	*/
572	<	private int cursor = head;
689	>	/** Index of element to be returned by subsequent call to next. */
690	>	int cursor;
691
692	<	/**
693	<	* Tail recorded at construction (also in remove), to stop
576	<	* iterator and also to check for comodification.
577	<	*/
578	<	private int fence = tail;
692	>	/** Number of elements yet to be returned. */
693	>	int remaining = size();
694
695		/**
696		* Index of element returned by most recent call to next.
697		* Reset to -1 if element is deleted by a call to remove.
698		*/
699	<	private int lastRet = -1;
699	>	int lastRet = -1;
700	>
701	>	DeqIterator() { cursor = head; }
702
703	<	public boolean hasNext() {
704	<	return cursor != fence;
703	>	public final boolean hasNext() {
704	>	return remaining > 0;
705		}
706
707		public E next() {
708	<	if (cursor == fence)
708	>	if (remaining <= 0)
709		throw new NoSuchElementException();
710	<	@SuppressWarnings("unchecked")
711	<	E result = (E) elements[cursor];
712	<	// This check doesn't catch all possible comodifications,
713	<	// but does catch the ones that corrupt traversal
714	<	if (tail != fence || result == null)
715	<	throw new ConcurrentModificationException();
716	<	lastRet = cursor;
717	<	cursor = (cursor + 1) & (elements.length - 1);
718	<	return result;
710	>	final Object[] es = elements;
711	>	E e = nonNullElementAt(es, cursor);
712	>	cursor = inc(lastRet = cursor, es.length);
713	>	remaining--;
714	>	return e;
715	>	}
716	>
717	>	void postDelete(boolean leftShifted) {
718	>	if (leftShifted)
719	>	cursor = dec(cursor, elements.length);
720		}
721
722	<	public void remove() {
722	>	public final void remove() {
723		if (lastRet < 0)
724		throw new IllegalStateException();
725	<	if (delete(lastRet)) { // if left-shifted, undo increment in next()
608	<	cursor = (cursor - 1) & (elements.length - 1);
609	<	fence = tail;
610	<	}
725	>	postDelete(delete(lastRet));
726		lastRet = -1;
727		}
728	+
729	+	public void forEachRemaining(Consumer<? super E> action) {
730	+	Objects.requireNonNull(action);
731	+	int r;
732	+	if ((r = remaining) <= 0)
733	+	return;
734	+	remaining = 0;
735	+	final Object[] es = elements;
736	+	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
737	+	throw new ConcurrentModificationException();
738	+	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
739	+	; i = 0, to = end) {
740	+	for (; i < to; i++)
741	+	action.accept(elementAt(es, i));
742	+	if (to == end) {
743	+	if (end != tail)
744	+	throw new ConcurrentModificationException();
745	+	lastRet = dec(end, es.length);
746	+	break;
747	+	}
748	+	}
749	+	}
750	+	}
751	+
752	+	private class DescendingIterator extends DeqIterator {
753	+	DescendingIterator() { cursor = dec(tail, elements.length); }
754	+
755	+	public final E next() {
756	+	if (remaining <= 0)
757	+	throw new NoSuchElementException();
758	+	final Object[] es = elements;
759	+	E e = nonNullElementAt(es, cursor);
760	+	cursor = dec(lastRet = cursor, es.length);
761	+	remaining--;
762	+	return e;
763	+	}
764	+
765	+	void postDelete(boolean leftShifted) {
766	+	if (!leftShifted)
767	+	cursor = inc(cursor, elements.length);
768	+	}
769	+
770	+	public final void forEachRemaining(Consumer<? super E> action) {
771	+	Objects.requireNonNull(action);
772	+	int r;
773	+	if ((r = remaining) <= 0)
774	+	return;
775	+	remaining = 0;
776	+	final Object[] es = elements;
777	+	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
778	+	throw new ConcurrentModificationException();
779	+	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
780	+	; i = es.length - 1, to = end) {
781	+	// hotspot generates faster code than for: i >= to !
782	+	for (; i > to - 1; i--)
783	+	action.accept(elementAt(es, i));
784	+	if (to == end) {
785	+	if (end != head)
786	+	throw new ConcurrentModificationException();
787	+	lastRet = end;
788	+	break;
789	+	}
790	+	}
791	+	}
792		}
793
794		/**
795	<	* This class is nearly a mirror-image of DeqIterator, using tail
796	<	* instead of head for initial cursor, and head instead of tail
797	<	* for fence.
798	<	*/
799	<	private class DescendingIterator implements Iterator<E> {
800	<	private int cursor = tail;
801	<	private int fence = head;
802	<	private int lastRet = -1;
795	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
796	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
797	>	* deque.
798	>	*
799	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
800	>	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
801	>	* {@link Spliterator#NONNULL}.  Overriding implementations should document
802	>	* the reporting of additional characteristic values.
803	>	*
804	>	* @return a {@code Spliterator} over the elements in this deque
805	>	* @since 1.8
806	>	*/
807	>	public Spliterator<E> spliterator() {
808	>	return new DeqSpliterator();
809	>	}
810	>
811	>	final class DeqSpliterator implements Spliterator<E> {
812	>	private int fence;      // -1 until first use
813	>	private int cursor;     // current index, modified on traverse/split
814
815	<	public boolean hasNext() {
816	<	return cursor != fence;
815	>	/** Constructs late-binding spliterator over all elements. */
816	>	DeqSpliterator() {
817	>	this.fence = -1;
818		}
819
820	<	public E next() {
821	<	if (cursor == fence)
822	<	throw new NoSuchElementException();
823	<	cursor = (cursor - 1) & (elements.length - 1);
824	<	@SuppressWarnings("unchecked")
825	<	E result = (E) elements[cursor];
635	<	if (head != fence || result == null)
636	<	throw new ConcurrentModificationException();
637	<	lastRet = cursor;
638	<	return result;
820	>	/** Constructs spliterator over the given range. */
821	>	DeqSpliterator(int origin, int fence) {
822	>	// assert 0 <= origin && origin < elements.length;
823	>	// assert 0 <= fence && fence < elements.length;
824	>	this.cursor = origin;
825	>	this.fence = fence;
826		}
827
828	<	public void remove() {
829	<	if (lastRet < 0)
830	<	throw new IllegalStateException();
831	<	if (!delete(lastRet)) {
832	<	cursor = (cursor + 1) & (elements.length - 1);
833	<	fence = head;
828	>	/** Ensures late-binding initialization; then returns fence. */
829	>	private int getFence() { // force initialization
830	>	int t;
831	>	if ((t = fence) < 0) {
832	>	t = fence = tail;
833	>	cursor = head;
834	>	}
835	>	return t;
836	>	}
837	>
838	>	public DeqSpliterator trySplit() {
839	>	final Object[] es = elements;
840	>	final int i, n;
841	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
842	>	? null
843	>	: new DeqSpliterator(i, cursor = add(i, n, es.length));
844	>	}
845	>
846	>	public void forEachRemaining(Consumer<? super E> action) {
847	>	if (action == null)
848	>	throw new NullPointerException();
849	>	final int end = getFence(), cursor = this.cursor;
850	>	final Object[] es = elements;
851	>	if (cursor != end) {
852	>	this.cursor = end;
853	>	// null check at both ends of range is sufficient
854	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
855	>	throw new ConcurrentModificationException();
856	>	for (int i = cursor, to = (i <= end) ? end : es.length;
857	>	; i = 0, to = end) {
858	>	for (; i < to; i++)
859	>	action.accept(elementAt(es, i));
860	>	if (to == end) break;
861	>	}
862	>	}
863	>	}
864	>
865	>	public boolean tryAdvance(Consumer<? super E> action) {
866	>	Objects.requireNonNull(action);
867	>	final Object[] es = elements;
868	>	if (fence < 0) { fence = tail; cursor = head; } // late-binding
869	>	final int i;
870	>	if ((i = cursor) == fence)
871	>	return false;
872	>	E e = nonNullElementAt(es, i);
873	>	cursor = inc(i, es.length);
874	>	action.accept(e);
875	>	return true;
876	>	}
877	>
878	>	public long estimateSize() {
879	>	return sub(getFence(), cursor, elements.length);
880	>	}
881	>
882	>	public int characteristics() {
883	>	return Spliterator.NONNULL
884	>	| Spliterator.ORDERED
885	>	| Spliterator.SIZED
886	>	| Spliterator.SUBSIZED;
887	>	}
888	>	}
889	>
890	>	/**
891	>	* @throws NullPointerException {@inheritDoc}
892	>	*/
893	>	public void forEach(Consumer<? super E> action) {
894	>	Objects.requireNonNull(action);
895	>	final Object[] es = elements;
896	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
897	>	; i = 0, to = end) {
898	>	for (; i < to; i++)
899	>	action.accept(elementAt(es, i));
900	>	if (to == end) {
901	>	if (end != tail) throw new ConcurrentModificationException();
902	>	break;
903	>	}
904	>	}
905	>	// checkInvariants();
906	>	}
907	>
908	>	/**
909	>	* Replaces each element of this deque with the result of applying the
910	>	* operator to that element, as specified by {@link List#replaceAll}.
911	>	*
912	>	* @param operator the operator to apply to each element
913	>	* @since TBD
914	>	*/
915	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
916	>	Objects.requireNonNull(operator);
917	>	final Object[] es = elements;
918	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
919	>	; i = 0, to = end) {
920	>	for (; i < to; i++)
921	>	es[i] = operator.apply(elementAt(es, i));
922	>	if (to == end) {
923	>	if (end != tail) throw new ConcurrentModificationException();
924	>	break;
925		}
648	–	lastRet = -1;
926		}
927	+	// checkInvariants();
928	+	}
929	+
930	+	/**
931	+	* @throws NullPointerException {@inheritDoc}
932	+	*/
933	+	public boolean removeIf(Predicate<? super E> filter) {
934	+	Objects.requireNonNull(filter);
935	+	return bulkRemove(filter);
936	+	}
937	+
938	+	/**
939	+	* @throws NullPointerException {@inheritDoc}
940	+	*/
941	+	public boolean removeAll(Collection<?> c) {
942	+	Objects.requireNonNull(c);
943	+	return bulkRemove(e -> c.contains(e));
944	+	}
945	+
946	+	/**
947	+	* @throws NullPointerException {@inheritDoc}
948	+	*/
949	+	public boolean retainAll(Collection<?> c) {
950	+	Objects.requireNonNull(c);
951	+	return bulkRemove(e -> !c.contains(e));
952	+	}
953	+
954	+	/** Implementation of bulk remove methods. */
955	+	private boolean bulkRemove(Predicate<? super E> filter) {
956	+	// checkInvariants();
957	+	final Object[] es = elements;
958	+	// Optimize for initial run of survivors
959	+	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
960	+	; i = 0, to = end) {
961	+	for (; i < to; i++)
962	+	if (filter.test(elementAt(es, i)))
963	+	return bulkRemoveModified(filter, i);
964	+	if (to == end) {
965	+	if (end != tail) throw new ConcurrentModificationException();
966	+	break;
967	+	}
968	+	}
969	+	return false;
970	+	}
971	+
972	+	// A tiny bit set implementation
973	+
974	+	private static long[] nBits(int n) {
975	+	return new long[((n - 1) >> 6) + 1];
976	+	}
977	+	private static void setBit(long[] bits, int i) {
978	+	bits[i >> 6] |= 1L << i;
979	+	}
980	+	private static boolean isClear(long[] bits, int i) {
981	+	return (bits[i >> 6] & (1L << i)) == 0;
982	+	}
983	+
984	+	/**
985	+	* Helper for bulkRemove, in case of at least one deletion.
986	+	* Tolerate predicates that reentrantly access the collection for
987	+	* read (but writers still get CME), so traverse once to find
988	+	* elements to delete, a second pass to physically expunge.
989	+	*
990	+	* @param beg valid index of first element to be deleted
991	+	*/
992	+	private boolean bulkRemoveModified(
993	+	Predicate<? super E> filter, final int beg) {
994	+	final Object[] es = elements;
995	+	final int capacity = es.length;
996	+	final int end = tail;
997	+	final long[] deathRow = nBits(sub(end, beg, capacity));
998	+	deathRow[0] = 1L;   // set bit 0
999	+	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1000	+	; i = 0, to = end, k -= capacity) {
1001	+	for (; i < to; i++)
1002	+	if (filter.test(elementAt(es, i)))
1003	+	setBit(deathRow, i - k);
1004	+	if (to == end) break;
1005	+	}
1006	+	// a two-finger traversal, with hare i reading, tortoise w writing
1007	+	int w = beg;
1008	+	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1009	+	; w = 0) { // w rejoins i on second leg
1010	+	// In this loop, i and w are on the same leg, with i > w
1011	+	for (; i < to; i++)
1012	+	if (isClear(deathRow, i - k))
1013	+	es[w++] = es[i];
1014	+	if (to == end) break;
1015	+	// In this loop, w is on the first leg, i on the second
1016	+	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1017	+	if (isClear(deathRow, i - k))
1018	+	es[w++] = es[i];
1019	+	if (i >= to) {
1020	+	if (w == capacity) w = 0; // "corner" case
1021	+	break;
1022	+	}
1023	+	}
1024	+	if (end != tail) throw new ConcurrentModificationException();
1025	+	circularClear(es, tail = w, end);
1026	+	// checkInvariants();
1027	+	return true;
1028		}
1029
1030		/**
#	Line 658 | Line 1036 | public class ArrayDeque<E> extends Abstr
1036		* @return {@code true} if this deque contains the specified element
1037		*/
1038		public boolean contains(Object o) {
1039	<	if (o == null)
1040	<	return false;
1041	<	int mask = elements.length - 1;
1042	<	int i = head;
1043	<	Object x;
1044	<	while ( (x = elements[i]) != null) {
1045	<	if (o.equals(x))
1046	<	return true;
1047	<	i = (i + 1) & mask;
1039	>	if (o != null) {
1040	>	final Object[] es = elements;
1041	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1042	>	; i = 0, to = end) {
1043	>	for (; i < to; i++)
1044	>	if (o.equals(es[i]))
1045	>	return true;
1046	>	if (to == end) break;
1047	>	}
1048		}
1049		return false;
1050		}
#	Line 693 | Line 1071 | public class ArrayDeque<E> extends Abstr
1071		* The deque will be empty after this call returns.
1072		*/
1073		public void clear() {
1074	<	int h = head;
1075	<	int t = tail;
1076	<	if (h != t) { // clear all cells
1077	<	head = tail = 0;
1078	<	int i = h;
1079	<	int mask = elements.length - 1;
1080	<	do {
1081	<	elements[i] = null;
1082	<	i = (i + 1) & mask;
1083	<	} while (i != t);
1074	>	circularClear(elements, head, tail);
1075	>	head = tail = 0;
1076	>	// checkInvariants();
1077	>	}
1078	>
1079	>	/**
1080	>	* Nulls out slots starting at array index i, upto index end.
1081	>	* Condition i == end means "empty" - nothing to do.
1082	>	*/
1083	>	private static void circularClear(Object[] es, int i, int end) {
1084	>	// assert 0 <= i && i < es.length;
1085	>	// assert 0 <= end && end < es.length;
1086	>	for (int to = (i <= end) ? end : es.length;
1087	>	; i = 0, to = end) {
1088	>	for (; i < to; i++) es[i] = null;
1089	>	if (to == end) break;
1090		}
1091		}
1092
#	Line 720 | Line 1104 | public class ArrayDeque<E> extends Abstr
1104		* @return an array containing all of the elements in this deque
1105		*/
1106		public Object[] toArray() {
1107	<	final int head = this.head;
1108	<	final int tail = this.tail;
1109	<	boolean wrap = (tail < head);
1110	<	int end = wrap ? tail + elements.length : tail;
1111	<	Object[] a = Arrays.copyOfRange(elements, head, end);
1112	<	if (wrap)
1113	<	System.arraycopy(elements, 0, a, elements.length - head, tail);
1107	>	return toArray(Object[].class);
1108	>	}
1109	>
1110	>	private <T> T[] toArray(Class<T[]> klazz) {
1111	>	final Object[] es = elements;
1112	>	final T[] a;
1113	>	final int head = this.head, tail = this.tail, end;
1114	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1115	>	// Uses null extension feature of copyOfRange
1116	>	a = Arrays.copyOfRange(es, head, end, klazz);
1117	>	} else {
1118	>	// integer overflow!
1119	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1120	>	System.arraycopy(es, head, a, 0, es.length - head);
1121	>	}
1122	>	if (end != tail)
1123	>	System.arraycopy(es, 0, a, es.length - head, tail);
1124		return a;
1125		}
1126
#	Line 752 | Line 1146 | public class ArrayDeque<E> extends Abstr
1146		* The following code can be used to dump the deque into a newly
1147		* allocated array of {@code String}:
1148		*
1149	<	*  <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
1149	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
1150		*
1151		* Note that {@code toArray(new Object[0])} is identical in function to
1152		* {@code toArray()}.
#	Line 768 | Line 1162 | public class ArrayDeque<E> extends Abstr
1162		*/
1163		@SuppressWarnings("unchecked")
1164		public <T> T[] toArray(T[] a) {
1165	<	final int head = this.head;
1166	<	final int tail = this.tail;
1167	<	boolean wrap = (tail < head);
1168	<	int size = (tail - head) + (wrap ? elements.length : 0);
1169	<	int firstLeg = size - (wrap ? tail : 0);
1170	<	int len = a.length;
1171	<	if (size > len) {
1172	<	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;
1165	>	final int size;
1166	>	if ((size = size()) > a.length)
1167	>	return toArray((Class<T[]>) a.getClass());
1168	>	final Object[] es = elements;
1169	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1170	>	; i = 0, len = tail) {
1171	>	System.arraycopy(es, i, a, j, len);
1172	>	if ((j += len) == size) break;
1173		}
1174	<	if (wrap)
1175	<	System.arraycopy(elements, 0, a, firstLeg, tail);
1174	>	if (size < a.length)
1175	>	a[size] = null;
1176		return a;
1177		}
1178
#	Line 810 | Line 1199 | public class ArrayDeque<E> extends Abstr
1199		/**
1200		* Saves this deque to a stream (that is, serializes it).
1201		*
1202	+	* @param s the stream
1203	+	* @throws java.io.IOException if an I/O error occurs
1204		* @serialData The current size ({@code int}) of the deque,
1205		* followed by all of its elements (each an object reference) in
1206		* first-to-last order.
#	Line 822 | Line 1213 | public class ArrayDeque<E> extends Abstr
1213		s.writeInt(size());
1214
1215		// Write out elements in order.
1216	<	int mask = elements.length - 1;
1217	<	for (int i = head; i != tail; i = (i + 1) & mask)
1218	<	s.writeObject(elements[i]);
1216	>	final Object[] es = elements;
1217	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1218	>	; i = 0, to = end) {
1219	>	for (; i < to; i++)
1220	>	s.writeObject(es[i]);
1221	>	if (to == end) break;
1222	>	}
1223		}
1224
1225		/**
1226		* Reconstitutes this deque from a stream (that is, deserializes it).
1227	+	* @param s the stream
1228	+	* @throws ClassNotFoundException if the class of a serialized object
1229	+	*         could not be found
1230	+	* @throws java.io.IOException if an I/O error occurs
1231		*/
1232		private void readObject(java.io.ObjectInputStream s)
1233		throws java.io.IOException, ClassNotFoundException {
#	Line 836 | Line 1235 | public class ArrayDeque<E> extends Abstr
1235
1236		// Read in size and allocate array
1237		int size = s.readInt();
1238	<	allocateElements(size);
1239	<	head = 0;
841	<	tail = size;
1238	>	elements = new Object[size + 1];
1239	>	this.tail = size;
1240
1241		// Read in all elements in the proper order.
1242		for (int i = 0; i < size; i++)
1243		elements[i] = s.readObject();
1244		}
1245
1246	<	public Spliterator<E> spliterator() {
1247	<	return new DeqSpliterator<E>(this, -1, -1);
1248	<	}
1249	<
1250	<	static final class DeqSpliterator<E> implements Spliterator<E> {
1251	<	private final ArrayDeque<E> deq;
1252	<	private int fence;  // -1 until first use
1253	<	private int index;  // current index, modified on traverse/split
1254	<
1255	<	/** Creates new spliterator covering the given array and range */
1256	<	DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) {
1257	<	this.deq = deq;
1258	<	this.index = origin;
1259	<	this.fence = fence;
1260	<	}
1261	<
1262	<	private int getFence() { // force initialization
1263	<	int t;
1264	<	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;
1246	>	/** debugging */
1247	>	void checkInvariants() {
1248	>	// Use head and tail fields with empty slot at tail strategy.
1249	>	// head == tail disambiguates to "empty".
1250	>	try {
1251	>	int capacity = elements.length;
1252	>	// assert 0 <= head && head < capacity;
1253	>	// assert 0 <= tail && tail < capacity;
1254	>	// assert capacity > 0;
1255	>	// assert size() < capacity;
1256	>	// assert head == tail || elements[head] != null;
1257	>	// assert elements[tail] == null;
1258	>	// assert head == tail || elements[dec(tail, capacity)] != null;
1259	>	} catch (Throwable t) {
1260	>	System.err.printf("head=%d tail=%d capacity=%d%n",
1261	>	head, tail, elements.length);
1262	>	System.err.printf("elements=%s%n",
1263	>	Arrays.toString(elements));
1264	>	throw t;
1265		}
1266		}
1267

Diff Legend

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