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 1.2 by dl, Tue Mar 8 12:27:06 2005 UTC vs.
Revision 1.134 by jsr166, Sat Jun 30 22:35:55 2018 UTC

#	Line 1 | Line 1
1		/*
2		* Written by Josh Bloch of Google Inc. and released to the public domain,
3	<	* as explained at http://creativecommons.org/licenses/publicdomain.
3	>	* as explained at http://creativecommons.org/publicdomain/zero/1.0/.
4		*/
5
6		package java.util;
7	<	import java.io.*;
7	>
8	>	import java.io.Serializable;
9	>	import java.util.function.Consumer;
10	>	import java.util.function.Predicate;
11	>	import java.util.function.UnaryOperator;
12	>	import jdk.internal.misc.SharedSecrets;
13
14		/**
15		* Resizable-array implementation of the {@link Deque} interface.  Array
#	Line 15 | Line 20 | import java.io.*;
20		* {@link Stack} when used as a stack, and faster than {@link LinkedList}
21		* when used as a queue.
22		*
23	<	* <p>Most <tt>ArrayDeque</tt> operations run in amortized constant time.
24	<	* Exceptions include {@link #remove(Object) remove}, {@link
25	<	* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence
26	<	* removeLastOccurrence}, {@link #contains contains }, {@link #iterator
27	<	* iterator.remove()}, and the bulk operations, all of which run in linear
28	<	* time.
23	>	* <p>Most {@code ArrayDeque} operations run in amortized constant time.
24	>	* Exceptions include
25	>	* {@link #remove(Object) remove},
26	>	* {@link #removeFirstOccurrence removeFirstOccurrence},
27	>	* {@link #removeLastOccurrence removeLastOccurrence},
28	>	* {@link #contains contains},
29	>	* {@link #iterator iterator.remove()},
30	>	* and the bulk operations, all of which run in linear time.
31		*
32	<	* <p>The iterators returned by this class's <tt>iterator</tt> method are
33	<	* <i>fail-fast</i>: If the deque is modified at any time after the iterator
34	<	* is created, in any way except through the iterator's own remove method, the
35	<	* iterator will generally throw a {@link ConcurrentModificationException}.
36	<	* Thus, in the face of concurrent modification, the iterator fails quickly
37	<	* and cleanly, rather than risking arbitrary, non-deterministic behavior at
38	<	* an undetermined time in the future.
32	>	* <p>The iterators returned by this class's {@link #iterator() iterator}
33	>	* method are <em>fail-fast</em>: If the deque is modified at any time after
34	>	* the iterator is created, in any way except through the iterator's own
35	>	* {@code remove} method, the iterator will generally throw a {@link
36	>	* ConcurrentModificationException}.  Thus, in the face of concurrent
37	>	* modification, the iterator fails quickly and cleanly, rather than risking
38	>	* arbitrary, non-deterministic behavior at an undetermined time in the
39	>	* future.
40		*
41		* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
42		* as it is, generally speaking, impossible to make any hard guarantees in the
43		* presence of unsynchronized concurrent modification.  Fail-fast iterators
44	<	* throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
44	>	* throw {@code ConcurrentModificationException} on a best-effort basis.
45		* Therefore, it would be wrong to write a program that depended on this
46		* exception for its correctness: <i>the fail-fast behavior of iterators
47		* should be used only to detect bugs.</i>
48		*
49		* <p>This class and its iterator implement all of the
50	<	* optional methods of the {@link Collection} and {@link
51	<	* Iterator} interfaces.  This class is a member of the <a
52	<	* href="{@docRoot}/../guide/collections/index.html"> Java Collections
53	<	* Framework</a>.
50	>	* <em>optional</em> methods of the {@link Collection} and {@link
51	>	* Iterator} interfaces.
52	>	*
53	>	* <p>This class is a member of the
54	>	* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
55	>	* Java Collections Framework</a>.
56		*
57		* @author  Josh Bloch and Doug Lea
58	+	* @param <E> the type of elements held in this deque
59		* @since   1.6
49	–	* @param <E> the type of elements held in this collection
60		*/
61		public class ArrayDeque<E> extends AbstractCollection<E>
62		implements Deque<E>, Cloneable, Serializable
63		{
64	+	/*
65	+	* VMs excel at optimizing simple array loops where indices are
66	+	* incrementing or decrementing over a valid slice, e.g.
67	+	*
68	+	* for (int i = start; i < end; i++) ... elements[i]
69	+	*
70	+	* Because in a circular array, elements are in general stored in
71	+	* two disjoint such slices, we help the VM by writing unusual
72	+	* nested loops for all traversals over the elements.  Having only
73	+	* one hot inner loop body instead of two or three eases human
74	+	* maintenance and encourages VM loop inlining into the caller.
75	+	*/
76	+
77		/**
78	<	* The array in which the elements of in the deque are stored.
79	<	* The capacity of the deque is the length of this array, which is
80	<	* always a power of two. The array is never allowed to become
58	<	* full, except transiently within an addX method where it is
59	<	* resized (see doubleCapacity) immediately upon becoming full,
60	<	* thus avoiding head and tail wrapping around to equal each
61	<	* other.  We also guarantee that all array cells not holding
62	<	* deque elements are always null.
78	>	* The array in which the elements of the deque are stored.
79	>	* All array cells not holding deque elements are always null.
80	>	* The array always has at least one null slot (at tail).
81		*/
82	<	private transient E[] elements;
82	>	transient Object[] elements;
83
84		/**
85		* The index of the element at the head of the deque (which is the
86		* element that would be removed by remove() or pop()); or an
87	<	* arbitrary number equal to tail if the deque is empty.
87	>	* arbitrary number 0 <= head < elements.length equal to tail if
88	>	* the deque is empty.
89		*/
90	<	private transient int head;
90	>	transient int head;
91
92		/**
93		* The index at which the next element would be added to the tail
94	<	* of the deque (via addLast(E), add(E), or push(E)).
94	>	* of the deque (via addLast(E), add(E), or push(E));
95	>	* elements[tail] is always null.
96		*/
97	<	private transient int tail;
97	>	transient int tail;
98
99		/**
100	<	* The minimum capacity that we'll use for a newly created deque.
101	<	* Must be a power of 2.
102	<	*/
103	<	private static final int MIN_INITIAL_CAPACITY = 8;
104	<
105	<	// ******  Array allocation and resizing utilities ******
106	<
107	<	/**
108	<	* Allocate empty array to hold the given number of elements.
109	<	*
110	<	* @param numElements  the number of elements to hold.
111	<	*/
112	<	private void allocateElements(int numElements) {
113	<	int initialCapacity = MIN_INITIAL_CAPACITY;
114	<	// Find the best power of two to hold elements.
115	<	// Tests "<=" because arrays aren't kept full.
116	<	if (numElements >= initialCapacity) {
117	<	initialCapacity = numElements;
118	<	initialCapacity |= (initialCapacity >>>  1);
119	<	initialCapacity |= (initialCapacity >>>  2);
120	<	initialCapacity |= (initialCapacity >>>  4);
121	<	initialCapacity |= (initialCapacity >>>  8);
122	<	initialCapacity |= (initialCapacity >>> 16);
123	<	initialCapacity++;
100	>	* The maximum size of array to allocate.
101	>	* Some VMs reserve some header words in an array.
102	>	* Attempts to allocate larger arrays may result in
103	>	* OutOfMemoryError: Requested array size exceeds VM limit
104	>	*/
105	>	private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
106	>
107	>	/**
108	>	* Increases the capacity of this deque by at least the given amount.
109	>	*
110	>	* @param needed the required minimum extra capacity; must be positive
111	>	*/
112	>	private void grow(int needed) {
113	>	// overflow-conscious code
114	>	final int oldCapacity = elements.length;
115	>	int newCapacity;
116	>	// Double capacity if small; else grow by 50%
117	>	int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1);
118	>	if (jump < needed
119	>	|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0)
120	>	newCapacity = newCapacity(needed, jump);
121	>	final Object[] es = elements = Arrays.copyOf(elements, newCapacity);
122	>	// Exceptionally, here tail == head needs to be disambiguated
123	>	if (tail < head || (tail == head && es[head] != null)) {
124	>	// wrap around; slide first leg forward to end of array
125	>	int newSpace = newCapacity - oldCapacity;
126	>	System.arraycopy(es, head,
127	>	es, head + newSpace,
128	>	oldCapacity - head);
129	>	for (int i = head, to = (head += newSpace); i < to; i++)
130	>	es[i] = null;
131	>	}
132	>	// checkInvariants();
133	>	}
134
135	<	if (initialCapacity < 0)   // Too many elements, must back off
136	<	initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements
135	>	/** Capacity calculation for edge conditions, especially overflow. */
136	>	private int newCapacity(int needed, int jump) {
137	>	final int oldCapacity = elements.length, minCapacity;
138	>	if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) {
139	>	if (minCapacity < 0)
140	>	throw new IllegalStateException("Sorry, deque too big");
141	>	return Integer.MAX_VALUE;
142		}
143	<	elements = (E[]) new Object[initialCapacity];
143	>	if (needed > jump)
144	>	return minCapacity;
145	>	return (oldCapacity + jump - MAX_ARRAY_SIZE < 0)
146	>	? oldCapacity + jump
147	>	: MAX_ARRAY_SIZE;
148		}
149
150		/**
151	<	* Double the capacity of this deque.  Call only when full, i.e.,
152	<	* when head and tail have wrapped around to become equal.
151	>	* Increases the internal storage of this collection, if necessary,
152	>	* to ensure that it can hold at least the given number of elements.
153	>	*
154	>	* @param minCapacity the desired minimum capacity
155	>	* @since TBD
156		*/
157	<	private void doubleCapacity() {
158	<	assert head == tail;
159	<	int p = head;
160	<	int n = elements.length;
161	<	int r = n - p; // number of elements to the right of p
120	<	int newCapacity = n << 1;
121	<	if (newCapacity < 0)
122	<	throw new IllegalStateException("Sorry, deque too big");
123	<	Object[] a = new Object[newCapacity];
124	<	System.arraycopy(elements, p, a, 0, r);
125	<	System.arraycopy(elements, 0, a, r, p);
126	<	elements = (E[])a;
127	<	head = 0;
128	<	tail = n;
157	>	/* public */ void ensureCapacity(int minCapacity) {
158	>	int needed;
159	>	if ((needed = (minCapacity + 1 - elements.length)) > 0)
160	>	grow(needed);
161	>	// checkInvariants();
162		}
163
164		/**
165	<	* Copy the elements from our element array into the specified array,
133	<	* in order (from first to last element in the deque).  It is assumed
134	<	* that the array is large enough to hold all elements in the deque.
165	>	* Minimizes the internal storage of this collection.
166		*
167	<	* @return its argument
167	>	* @since TBD
168		*/
169	<	private <T> T[] copyElements(T[] a) {
170	<	if (head < tail) {
171	<	System.arraycopy(elements, head, a, 0, size());
172	<	} else if (head > tail) {
173	<	int headPortionLen = elements.length - head;
174	<	System.arraycopy(elements, head, a, 0, headPortionLen);
144	<	System.arraycopy(elements, 0, a, headPortionLen, tail);
169	>	/* public */ void trimToSize() {
170	>	int size;
171	>	if ((size = size()) + 1 < elements.length) {
172	>	elements = toArray(new Object[size + 1]);
173	>	head = 0;
174	>	tail = size;
175		}
176	<	return a;
176	>	// checkInvariants();
177		}
178
179		/**
180	<	* Constructs an empty array deque with the an initial capacity
180	>	* Constructs an empty array deque with an initial capacity
181		* sufficient to hold 16 elements.
182		*/
183		public ArrayDeque() {
184	<	elements = (E[]) new Object[16];
184	>	elements = new Object[16 + 1];
185		}
186
187		/**
188		* Constructs an empty array deque with an initial capacity
189		* sufficient to hold the specified number of elements.
190		*
191	<	* @param numElements  lower bound on initial capacity of the deque
191	>	* @param numElements lower bound on initial capacity of the deque
192		*/
193		public ArrayDeque(int numElements) {
194	<	allocateElements(numElements);
194	>	elements =
195	>	new Object[(numElements < 1) ? 1 :
196	>	(numElements == Integer.MAX_VALUE) ? Integer.MAX_VALUE :
197	>	numElements + 1];
198		}
199
200		/**
#	Line 175 | Line 208 | public class ArrayDeque<E> extends Abstr
208		* @throws NullPointerException if the specified collection is null
209		*/
210		public ArrayDeque(Collection<? extends E> c) {
211	<	allocateElements(c.size());
212	<	addAll(c);
211	>	this(c.size());
212	>	copyElements(c);
213	>	}
214	>
215	>	/**
216	>	* Circularly increments i, mod modulus.
217	>	* Precondition and postcondition: 0 <= i < modulus.
218	>	*/
219	>	static final int inc(int i, int modulus) {
220	>	if (++i >= modulus) i = 0;
221	>	return i;
222	>	}
223	>
224	>	/**
225	>	* Circularly decrements i, mod modulus.
226	>	* Precondition and postcondition: 0 <= i < modulus.
227	>	*/
228	>	static final int dec(int i, int modulus) {
229	>	if (--i < 0) i = modulus - 1;
230	>	return i;
231	>	}
232	>
233	>	/**
234	>	* Circularly adds the given distance to index i, mod modulus.
235	>	* Precondition: 0 <= i < modulus, 0 <= distance <= modulus.
236	>	* @return index 0 <= i < modulus
237	>	*/
238	>	static final int inc(int i, int distance, int modulus) {
239	>	if ((i += distance) - modulus >= 0) i -= modulus;
240	>	return i;
241	>	}
242	>
243	>	/**
244	>	* Subtracts j from i, mod modulus.
245	>	* Index i must be logically ahead of index j.
246	>	* Precondition: 0 <= i < modulus, 0 <= j < modulus.
247	>	* @return the "circular distance" from j to i; corner case i == j
248	>	* is disambiguated to "empty", returning 0.
249	>	*/
250	>	static final int sub(int i, int j, int modulus) {
251	>	if ((i -= j) < 0) i += modulus;
252	>	return i;
253	>	}
254	>
255	>	/**
256	>	* Returns element at array index i.
257	>	* This is a slight abuse of generics, accepted by javac.
258	>	*/
259	>	@SuppressWarnings("unchecked")
260	>	static final <E> E elementAt(Object[] es, int i) {
261	>	return (E) es[i];
262	>	}
263	>
264	>	/**
265	>	* A version of elementAt that checks for null elements.
266	>	* This check doesn't catch all possible comodifications,
267	>	* but does catch ones that corrupt traversal.
268	>	*/
269	>	static final <E> E nonNullElementAt(Object[] es, int i) {
270	>	@SuppressWarnings("unchecked") E e = (E) es[i];
271	>	if (e == null)
272	>	throw new ConcurrentModificationException();
273	>	return e;
274		}
275
276		// The main insertion and extraction methods are addFirst,
#	Line 184 | Line 278 | public class ArrayDeque<E> extends Abstr
278		// terms of these.
279
280		/**
281	<	* Inserts the specified element to the front this deque.
281	>	* Inserts the specified element at the front of this deque.
282		*
283	<	* @param e the element to insert
284	<	* @throws NullPointerException if <tt>e</tt> is null
283	>	* @param e the element to add
284	>	* @throws NullPointerException if the specified element is null
285		*/
286		public void addFirst(E e) {
287		if (e == null)
288		throw new NullPointerException();
289	<	elements[head = (head - 1) & (elements.length - 1)] = e;
290	<	if (head == tail)
291	<	doubleCapacity();
289	>	final Object[] es = elements;
290	>	es[head = dec(head, es.length)] = e;
291	>	if (head == tail)
292	>	grow(1);
293	>	// checkInvariants();
294		}
295
296		/**
297	<	* Inserts the specified element to the end this deque.
298	<	* This method is equivalent to {@link Collection#add} and
299	<	* {@link #push}.
297	>	* Inserts the specified element at the end of this deque.
298	>	*
299	>	* <p>This method is equivalent to {@link #add}.
300		*
301	<	* @param e the element to insert
302	<	* @throws NullPointerException if <tt>e</tt> is null
301	>	* @param e the element to add
302	>	* @throws NullPointerException if the specified element is null
303		*/
304		public void addLast(E e) {
305		if (e == null)
306		throw new NullPointerException();
307	<	elements[tail] = e;
308	<	if ( (tail = (tail + 1) & (elements.length - 1)) == head)
309	<	doubleCapacity();
307	>	final Object[] es = elements;
308	>	es[tail] = e;
309	>	if (head == (tail = inc(tail, es.length)))
310	>	grow(1);
311	>	// checkInvariants();
312		}
313
314		/**
315	<	* Retrieves and removes the first element of this deque, or
316	<	* <tt>null</tt> if this deque is empty.
315	>	* Adds all of the elements in the specified collection at the end
316	>	* of this deque, as if by calling {@link #addLast} on each one,
317	>	* in the order that they are returned by the collection's iterator.
318		*
319	<	* @return the first element of this deque, or <tt>null</tt> if
320	<	*     this deque is empty
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 E pollFirst() {
325	<	int h = head;
326	<	E result = elements[h]; // Element is null if deque empty
327	<	if (result == null)
328	<	return null;
329	<	elements[h] = null;     // Must null out slot
330	<	head = (h + 1) & (elements.length - 1);
230	<	return result;
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	>	copyElements(c);
329	>	// checkInvariants();
330	>	return size() > s;
331		}
332
333	<	/**
334	<	* Retrieves and removes the last element of this deque, or
235	<	* <tt>null</tt> if this deque is empty.
236	<	*
237	<	* @return the last element of this deque, or <tt>null</tt> if
238	<	*     this deque is empty
239	<	*/
240	<	public E pollLast() {
241	<	int t = (tail - 1) & (elements.length - 1);
242	<	E result = elements[t];
243	<	if (result == null)
244	<	return null;
245	<	elements[t] = null;
246	<	tail = t;
247	<	return result;
333	>	private void copyElements(Collection<? extends E> c) {
334	>	c.forEach(this::addLast);
335		}
336
337		/**
338	<	* Inserts the specified element to the front this deque.
338	>	* Inserts the specified element at the front of this deque.
339		*
340	<	* @param e the element to insert
341	<	* @return <tt>true</tt> (as per the spec for {@link Deque#offerFirst})
342	<	* @throws NullPointerException if <tt>e</tt> is null
340	>	* @param e the element to add
341	>	* @return {@code true} (as specified by {@link Deque#offerFirst})
342	>	* @throws NullPointerException if the specified element is null
343		*/
344		public boolean offerFirst(E e) {
345		addFirst(e);
#	Line 260 | Line 347 | public class ArrayDeque<E> extends Abstr
347		}
348
349		/**
350	<	* Inserts the specified element to the end this deque.
350	>	* Inserts the specified element at the end of this deque.
351		*
352	<	* @param e the element to insert
353	<	* @return <tt>true</tt> (as per the spec for {@link Deque#offerLast})
354	<	* @throws NullPointerException if <tt>e</tt> is null
352	>	* @param e the element to add
353	>	* @return {@code true} (as specified by {@link Deque#offerLast})
354	>	* @throws NullPointerException if the specified element is null
355		*/
356		public boolean offerLast(E e) {
357		addLast(e);
#	Line 272 | Line 359 | public class ArrayDeque<E> extends Abstr
359		}
360
361		/**
362	<	* Retrieves and removes the first element of this deque.  This method
276	<	* differs from the <tt>pollFirst</tt> method in that it throws an
277	<	* exception if this deque is empty.
278	<	*
279	<	* @return the first element of this deque
280	<	* @throws NoSuchElementException if this deque is empty
362	>	* @throws NoSuchElementException {@inheritDoc}
363		*/
364		public E removeFirst() {
365	<	E x = pollFirst();
366	<	if (x == null)
365	>	E e = pollFirst();
366	>	if (e == null)
367		throw new NoSuchElementException();
368	<	return x;
368	>	// checkInvariants();
369	>	return e;
370		}
371
372		/**
373	<	* Retrieves and removes the last element of this deque.  This method
291	<	* differs from the <tt>pollLast</tt> method in that it throws an
292	<	* exception if this deque is empty.
293	<	*
294	<	* @return the last element of this deque
295	<	* @throws NoSuchElementException if this deque is empty
373	>	* @throws NoSuchElementException {@inheritDoc}
374		*/
375		public E removeLast() {
376	<	E x = pollLast();
377	<	if (x == null)
376	>	E e = pollLast();
377	>	if (e == null)
378		throw new NoSuchElementException();
379	<	return x;
379	>	// checkInvariants();
380	>	return e;
381		}
382
383	<	/**
384	<	* Retrieves, but does not remove, the first element of this deque,
385	<	* returning <tt>null</tt> if this deque is empty.
386	<	*
387	<	* @return the first element of this deque, or <tt>null</tt> if
388	<	*     this deque is empty
389	<	*/
390	<	public E peekFirst() {
391	<	return elements[head]; // elements[head] is null if deque empty
383	>	public E pollFirst() {
384	>	final Object[] es;
385	>	final int h;
386	>	E e = elementAt(es = elements, h = head);
387	>	if (e != null) {
388	>	es[h] = null;
389	>	head = inc(h, es.length);
390	>	}
391	>	// checkInvariants();
392	>	return e;
393		}
394
395	<	/**
396	<	* Retrieves, but does not remove, the last element of this deque,
397	<	* returning <tt>null</tt> if this deque is empty.
398	<	*
399	<	* @return the last element of this deque, or <tt>null</tt> if this deque
400	<	*     is empty
401	<	*/
402	<	public E peekLast() {
323	<	return elements[(tail - 1) & (elements.length - 1)];
395	>	public E pollLast() {
396	>	final Object[] es;
397	>	final int t;
398	>	E e = elementAt(es = elements, t = dec(tail, es.length));
399	>	if (e != null)
400	>	es[tail = t] = null;
401	>	// checkInvariants();
402	>	return e;
403		}
404
405		/**
406	<	* Retrieves, but does not remove, the first element of this
328	<	* deque.  This method differs from the <tt>peek</tt> method only
329	<	* in that it throws an exception if this deque is empty.
330	<	*
331	<	* @return the first element of this deque
332	<	* @throws NoSuchElementException if this deque is empty
406	>	* @throws NoSuchElementException {@inheritDoc}
407		*/
408		public E getFirst() {
409	<	E x = elements[head];
410	<	if (x == null)
409	>	E e = elementAt(elements, head);
410	>	if (e == null)
411		throw new NoSuchElementException();
412	<	return x;
412	>	// checkInvariants();
413	>	return e;
414		}
415
416		/**
417	<	* Retrieves, but does not remove, the last element of this
343	<	* deque.  This method differs from the <tt>peek</tt> method only
344	<	* in that it throws an exception if this deque is empty.
345	<	*
346	<	* @return the last element of this deque
347	<	* @throws NoSuchElementException if this deque is empty
417	>	* @throws NoSuchElementException {@inheritDoc}
418		*/
419		public E getLast() {
420	<	E x = elements[(tail - 1) & (elements.length - 1)];
421	<	if (x == null)
420	>	final Object[] es = elements;
421	>	E e = elementAt(es, dec(tail, es.length));
422	>	if (e == null)
423		throw new NoSuchElementException();
424	<	return x;
424	>	// checkInvariants();
425	>	return e;
426	>	}
427	>
428	>	public E peekFirst() {
429	>	// checkInvariants();
430	>	return elementAt(elements, head);
431	>	}
432	>
433	>	public E peekLast() {
434	>	// checkInvariants();
435	>	final Object[] es;
436	>	return elementAt(es = elements, dec(tail, es.length));
437		}
438
439		/**
440		* Removes the first occurrence of the specified element in this
441	<	* deque (when traversing the deque from head to tail).  If the deque
442	<	* does not contain the element, it is unchanged.
443	<	*
444	<	* @param e element to be removed from this deque, if present
445	<	* @return <tt>true</tt> if the deque contained the specified element
446	<	*/
447	<	public boolean removeFirstOccurrence(Object e) {
448	<	if (e == null)
449	<	return false;
450	<	int mask = elements.length - 1;
451	<	int i = head;
452	<	E x;
453	<	while ( (x = elements[i]) != null) {
454	<	if (e.equals(x)) {
455	<	delete(i);
456	<	return true;
441	>	* deque (when traversing the deque from head to tail).
442	>	* If the deque does not contain the element, it is unchanged.
443	>	* More formally, removes the first element {@code e} such that
444	>	* {@code o.equals(e)} (if such an element exists).
445	>	* Returns {@code true} if this deque contained the specified element
446	>	* (or equivalently, if this deque changed as a result of the call).
447	>	*
448	>	* @param o element to be removed from this deque, if present
449	>	* @return {@code true} if the deque contained the specified element
450	>	*/
451	>	public boolean removeFirstOccurrence(Object o) {
452	>	if (o != null) {
453	>	final Object[] es = elements;
454	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
455	>	; i = 0, to = end) {
456	>	for (; i < to; i++)
457	>	if (o.equals(es[i])) {
458	>	delete(i);
459	>	return true;
460	>	}
461	>	if (to == end) break;
462		}
375	–	i = (i + 1) & mask;
463		}
464		return false;
465		}
466
467		/**
468		* Removes the last occurrence of the specified element in this
469	<	* deque (when traversing the deque from head to tail).  If the deque
470	<	* does not contain the element, it is unchanged.
471	<	*
472	<	* @param e element to be removed from this deque, if present
473	<	* @return <tt>true</tt> if the deque contained the specified element
474	<	*/
475	<	public boolean removeLastOccurrence(Object e) {
476	<	if (e == null)
477	<	return false;
478	<	int mask = elements.length - 1;
479	<	int i = (tail - 1) & mask;
480	<	E x;
481	<	while ( (x = elements[i]) != null) {
482	<	if (e.equals(x)) {
483	<	delete(i);
484	<	return true;
469	>	* deque (when traversing the deque from head to tail).
470	>	* If the deque does not contain the element, it is unchanged.
471	>	* More formally, removes the last element {@code e} such that
472	>	* {@code o.equals(e)} (if such an element exists).
473	>	* Returns {@code true} if this deque contained the specified element
474	>	* (or equivalently, if this deque changed as a result of the call).
475	>	*
476	>	* @param o element to be removed from this deque, if present
477	>	* @return {@code true} if the deque contained the specified element
478	>	*/
479	>	public boolean removeLastOccurrence(Object o) {
480	>	if (o != null) {
481	>	final Object[] es = elements;
482	>	for (int i = tail, end = head, to = (i >= end) ? end : 0;
483	>	; i = es.length, to = end) {
484	>	for (i--; i > to - 1; i--)
485	>	if (o.equals(es[i])) {
486	>	delete(i);
487	>	return true;
488	>	}
489	>	if (to == end) break;
490		}
399	–	i = (i - 1) & mask;
491		}
492		return false;
493		}
#	Line 404 | Line 495 | public class ArrayDeque<E> extends Abstr
495		// *** Queue methods ***
496
497		/**
498	<	* Inserts the specified element to the end of this deque.
408	<	*
409	<	* <p>This method is equivalent to {@link #offerLast}.
410	<	*
411	<	* @param e the element to insert
412	<	* @return <tt>true</tt> (as per the spec for {@link Queue#offer})
413	<	* @throws NullPointerException if <tt>e</tt> is null
414	<	*/
415	<	public boolean offer(E e) {
416	<	return offerLast(e);
417	<	}
418	<
419	<	/**
420	<	* Inserts the specified element to the end of this deque.
498	>	* Inserts the specified element at the end of this deque.
499		*
500		* <p>This method is equivalent to {@link #addLast}.
501		*
502	<	* @param e the element to insert
503	<	* @return <tt>true</tt> (as per the spec for {@link Collection#add})
504	<	* @throws NullPointerException if <tt>e</tt> is null
502	>	* @param e the element to add
503	>	* @return {@code true} (as specified by {@link Collection#add})
504	>	* @throws NullPointerException if the specified element is null
505		*/
506		public boolean add(E e) {
507		addLast(e);
#	Line 431 | Line 509 | public class ArrayDeque<E> extends Abstr
509		}
510
511		/**
512	<	* Retrieves and removes the head of the queue represented by
435	<	* this deque, or <tt>null</tt> if this deque is empty.  In other words,
436	<	* retrieves and removes the first element of this deque, or <tt>null</tt>
437	<	* if this deque is empty.
512	>	* Inserts the specified element at the end of this deque.
513		*
514	<	* <p>This method is equivalent to {@link #pollFirst}.
514	>	* <p>This method is equivalent to {@link #offerLast}.
515		*
516	<	* @return the first element of this deque, or <tt>null</tt> if
517	<	*     this deque is empty
516	>	* @param e the element to add
517	>	* @return {@code true} (as specified by {@link Queue#offer})
518	>	* @throws NullPointerException if the specified element is null
519		*/
520	<	public E poll() {
521	<	return pollFirst();
520	>	public boolean offer(E e) {
521	>	return offerLast(e);
522		}
523
524		/**
525		* Retrieves and removes the head of the queue represented by this deque.
526	<	* This method differs from the <tt>poll</tt> method in that it throws an
527	<	* exception if this deque is empty.
526	>	*
527	>	* This method differs from {@link #poll() poll()} only in that it
528	>	* throws an exception if this deque is empty.
529		*
530		* <p>This method is equivalent to {@link #removeFirst}.
531		*
532		* @return the head of the queue represented by this deque
533	<	* @throws NoSuchElementException if this deque is empty
533	>	* @throws NoSuchElementException {@inheritDoc}
534		*/
535		public E remove() {
536		return removeFirst();
537		}
538
539		/**
540	<	* Retrieves, but does not remove, the head of the queue represented by
541	<	* this deque, returning <tt>null</tt> if this deque is empty.
540	>	* Retrieves and removes the head of the queue represented by this deque
541	>	* (in other words, the first element of this deque), or returns
542	>	* {@code null} if this deque is empty.
543		*
544	<	* <p>This method is equivalent to {@link #peekFirst}
544	>	* <p>This method is equivalent to {@link #pollFirst}.
545		*
546		* @return the head of the queue represented by this deque, or
547	<	*     <tt>null</tt> if this deque is empty
547	>	*         {@code null} if this deque is empty
548		*/
549	<	public E peek() {
550	<	return peekFirst();
549	>	public E poll() {
550	>	return pollFirst();
551		}
552
553		/**
554		* Retrieves, but does not remove, the head of the queue represented by
555	<	* this deque.  This method differs from the <tt>peek</tt> method only in
555	>	* this deque.  This method differs from {@link #peek peek} only in
556		* that it throws an exception if this deque is empty.
557		*
558	<	* <p>This method is equivalent to {@link #getFirst}
558	>	* <p>This method is equivalent to {@link #getFirst}.
559		*
560		* @return the head of the queue represented by this deque
561	<	* @throws NoSuchElementException if this deque is empty
561	>	* @throws NoSuchElementException {@inheritDoc}
562		*/
563		public E element() {
564		return getFirst();
565		}
566
567	+	/**
568	+	* Retrieves, but does not remove, the head of the queue represented by
569	+	* this deque, or returns {@code null} if this deque is empty.
570	+	*
571	+	* <p>This method is equivalent to {@link #peekFirst}.
572	+	*
573	+	* @return the head of the queue represented by this deque, or
574	+	*         {@code null} if this deque is empty
575	+	*/
576	+	public E peek() {
577	+	return peekFirst();
578	+	}
579	+
580		// *** Stack methods ***
581
582		/**
583		* Pushes an element onto the stack represented by this deque.  In other
584	<	* words, inserts the element to the front this deque.
584	>	* words, inserts the element at the front of this deque.
585		*
586		* <p>This method is equivalent to {@link #addFirst}.
587		*
588		* @param e the element to push
589	<	* @throws NullPointerException if <tt>e</tt> is null
589	>	* @throws NullPointerException if the specified element is null
590		*/
591		public void push(E e) {
592		addFirst(e);
#	Line 508 | Line 599 | public class ArrayDeque<E> extends Abstr
599		* <p>This method is equivalent to {@link #removeFirst()}.
600		*
601		* @return the element at the front of this deque (which is the top
602	<	*     of the stack represented by this deque)
603	<	* @throws NoSuchElementException if this deque is empty
602	>	*         of the stack represented by this deque)
603	>	* @throws NoSuchElementException {@inheritDoc}
604		*/
605		public E pop() {
606		return removeFirst();
607		}
608
609		/**
610	<	* Remove the element at the specified position in the elements array,
611	<	* adjusting head, tail, and size as necessary.  This can result in
612	<	* motion of elements backwards or forwards in the array.
613	<	*
614	<	* <p>This method is called delete rather than remove to emphasize the
615	<	* that its semantics differ from those of List.remove(int).
616	<	*
617	<	* @return true if elements moved backwards
618	<	*/
619	<	private boolean delete(int i) {
620	<	// Case 1: Deque doesn't wrap
621	<	// Case 2: Deque does wrap and removed element is in the head portion
622	<	if ((head < tail || tail == 0) || i >= head) {
623	<	System.arraycopy(elements, head, elements, head + 1, i - head);
624	<	elements[head] = null;
625	<	head = (head + 1) & (elements.length - 1);
610	>	* Removes the element at the specified position in the elements array.
611	>	* This can result in forward or backwards motion of array elements.
612	>	* We optimize for least element motion.
613	>	*
614	>	* <p>This method is called delete rather than remove to emphasize
615	>	* that its semantics differ from those of {@link List#remove(int)}.
616	>	*
617	>	* @return true if elements near tail moved backwards
618	>	*/
619	>	boolean delete(int i) {
620	>	// checkInvariants();
621	>	final Object[] es = elements;
622	>	final int capacity = es.length;
623	>	final int h, t;
624	>	// number of elements before to-be-deleted elt
625	>	final int front = sub(i, h = head, capacity);
626	>	// number of elements after to-be-deleted elt
627	>	final int back = sub(t = tail, i, capacity) - 1;
628	>	if (front < back) {
629	>	// move front elements forwards
630	>	if (h <= i) {
631	>	System.arraycopy(es, h, es, h + 1, front);
632	>	} else { // Wrap around
633	>	System.arraycopy(es, 0, es, 1, i);
634	>	es[0] = es[capacity - 1];
635	>	System.arraycopy(es, h, es, h + 1, front - (i + 1));
636	>	}
637	>	es[h] = null;
638	>	head = inc(h, capacity);
639	>	// checkInvariants();
640		return false;
641	+	} else {
642	+	// move back elements backwards
643	+	tail = dec(t, capacity);
644	+	if (i <= tail) {
645	+	System.arraycopy(es, i + 1, es, i, back);
646	+	} else { // Wrap around
647	+	System.arraycopy(es, i + 1, es, i, capacity - (i + 1));
648	+	es[capacity - 1] = es[0];
649	+	System.arraycopy(es, 1, es, 0, t - 1);
650	+	}
651	+	es[tail] = null;
652	+	// checkInvariants();
653	+	return true;
654		}
537	–
538	–	// Case 3: Deque wraps and removed element is in the tail portion
539	–	tail--;
540	–	System.arraycopy(elements, i + 1, elements, i, tail - i);
541	–	elements[tail] = null;
542	–	return true;
655		}
656
657		// *** Collection Methods ***
#	Line 550 | Line 662 | public class ArrayDeque<E> extends Abstr
662		* @return the number of elements in this deque
663		*/
664		public int size() {
665	<	return (tail - head) & (elements.length - 1);
665	>	return sub(tail, head, elements.length);
666		}
667
668		/**
669	<	* Returns <tt>true</tt> if this collection contains no elements.<p>
669	>	* Returns {@code true} if this deque contains no elements.
670		*
671	<	* @return <tt>true</tt> if this collection contains no elements.
671	>	* @return {@code true} if this deque contains no elements
672		*/
673		public boolean isEmpty() {
674		return head == tail;
#	Line 567 | Line 679 | public class ArrayDeque<E> extends Abstr
679		* will be ordered from first (head) to last (tail).  This is the same
680		* order that elements would be dequeued (via successive calls to
681		* {@link #remove} or popped (via successive calls to {@link #pop}).
682	<	*
683	<	* @return an <tt>Iterator</tt> over the elements in this deque
682	>	*
683	>	* @return an iterator over the elements in this deque
684		*/
685		public Iterator<E> iterator() {
686		return new DeqIterator();
687		}
688
689	+	public Iterator<E> descendingIterator() {
690	+	return new DescendingIterator();
691	+	}
692	+
693		private class DeqIterator implements Iterator<E> {
694	<	/**
695	<	* Index of element to be returned by subsequent call to next.
580	<	*/
581	<	private int cursor = head;
694	>	/** Index of element to be returned by subsequent call to next. */
695	>	int cursor;
696
697	<	/**
698	<	* Tail recorded at construction (also in remove), to stop
585	<	* iterator and also to check for comodification.
586	<	*/
587	<	private int fence = tail;
697	>	/** Number of elements yet to be returned. */
698	>	int remaining = size();
699
700		/**
701		* Index of element returned by most recent call to next.
702		* Reset to -1 if element is deleted by a call to remove.
703		*/
704	<	private int lastRet = -1;
704	>	int lastRet = -1;
705
706	<	public boolean hasNext() {
707	<	return cursor != fence;
706	>	DeqIterator() { cursor = head; }
707	>
708	>	public final boolean hasNext() {
709	>	return remaining > 0;
710		}
711
712		public E next() {
713	<	E result;
601	<	if (cursor == fence)
713	>	if (remaining <= 0)
714		throw new NoSuchElementException();
715	<	// This check doesn't catch all possible comodifications,
716	<	// but does catch the ones that corrupt traversal
717	<	if (tail != fence || (result = elements[cursor]) == null)
718	<	throw new ConcurrentModificationException();
719	<	lastRet = cursor;
608	<	cursor = (cursor + 1) & (elements.length - 1);
609	<	return result;
715	>	final Object[] es = elements;
716	>	E e = nonNullElementAt(es, cursor);
717	>	cursor = inc(lastRet = cursor, es.length);
718	>	remaining--;
719	>	return e;
720		}
721
722	<	public void remove() {
722	>	void postDelete(boolean leftShifted) {
723	>	if (leftShifted)
724	>	cursor = dec(cursor, elements.length);
725	>	}
726	>
727	>	public final void remove() {
728		if (lastRet < 0)
729		throw new IllegalStateException();
730	<	if (delete(lastRet))
616	<	cursor--;
730	>	postDelete(delete(lastRet));
731		lastRet = -1;
732	<	fence = tail;
732	>	}
733	>
734	>	public void forEachRemaining(Consumer<? super E> action) {
735	>	Objects.requireNonNull(action);
736	>	int r;
737	>	if ((r = remaining) <= 0)
738	>	return;
739	>	remaining = 0;
740	>	final Object[] es = elements;
741	>	if (es[cursor] == null || sub(tail, cursor, es.length) != r)
742	>	throw new ConcurrentModificationException();
743	>	for (int i = cursor, end = tail, to = (i <= end) ? end : es.length;
744	>	; i = 0, to = end) {
745	>	for (; i < to; i++)
746	>	action.accept(elementAt(es, i));
747	>	if (to == end) {
748	>	if (end != tail)
749	>	throw new ConcurrentModificationException();
750	>	lastRet = dec(end, es.length);
751	>	break;
752	>	}
753	>	}
754	>	}
755	>	}
756	>
757	>	private class DescendingIterator extends DeqIterator {
758	>	DescendingIterator() { cursor = dec(tail, elements.length); }
759	>
760	>	public final E next() {
761	>	if (remaining <= 0)
762	>	throw new NoSuchElementException();
763	>	final Object[] es = elements;
764	>	E e = nonNullElementAt(es, cursor);
765	>	cursor = dec(lastRet = cursor, es.length);
766	>	remaining--;
767	>	return e;
768	>	}
769	>
770	>	void postDelete(boolean leftShifted) {
771	>	if (!leftShifted)
772	>	cursor = inc(cursor, elements.length);
773	>	}
774	>
775	>	public final void forEachRemaining(Consumer<? super E> action) {
776	>	Objects.requireNonNull(action);
777	>	int r;
778	>	if ((r = remaining) <= 0)
779	>	return;
780	>	remaining = 0;
781	>	final Object[] es = elements;
782	>	if (es[cursor] == null || sub(cursor, head, es.length) + 1 != r)
783	>	throw new ConcurrentModificationException();
784	>	for (int i = cursor, end = head, to = (i >= end) ? end : 0;
785	>	; i = es.length - 1, to = end) {
786	>	// hotspot generates faster code than for: i >= to !
787	>	for (; i > to - 1; i--)
788	>	action.accept(elementAt(es, i));
789	>	if (to == end) {
790	>	if (end != head)
791	>	throw new ConcurrentModificationException();
792	>	lastRet = end;
793	>	break;
794	>	}
795	>	}
796		}
797		}
798
799		/**
800	<	* Returns <tt>true</tt> if this deque contains the specified
801	<	* element.  More formally, returns <tt>true</tt> if and only if this
802	<	* deque contains at least one element <tt>e</tt> such that
803	<	* <tt>e.equals(o)</tt>.
800	>	* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
801	>	* and <em>fail-fast</em> {@link Spliterator} over the elements in this
802	>	* deque.
803	>	*
804	>	* <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
805	>	* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and
806	>	* {@link Spliterator#NONNULL}.  Overriding implementations should document
807	>	* the reporting of additional characteristic values.
808	>	*
809	>	* @return a {@code Spliterator} over the elements in this deque
810	>	* @since 1.8
811	>	*/
812	>	public Spliterator<E> spliterator() {
813	>	return new DeqSpliterator();
814	>	}
815	>
816	>	final class DeqSpliterator implements Spliterator<E> {
817	>	private int fence;      // -1 until first use
818	>	private int cursor;     // current index, modified on traverse/split
819	>
820	>	/** Constructs late-binding spliterator over all elements. */
821	>	DeqSpliterator() {
822	>	this.fence = -1;
823	>	}
824	>
825	>	/** Constructs spliterator over the given range. */
826	>	DeqSpliterator(int origin, int fence) {
827	>	// assert 0 <= origin && origin < elements.length;
828	>	// assert 0 <= fence && fence < elements.length;
829	>	this.cursor = origin;
830	>	this.fence = fence;
831	>	}
832	>
833	>	/** Ensures late-binding initialization; then returns fence. */
834	>	private int getFence() { // force initialization
835	>	int t;
836	>	if ((t = fence) < 0) {
837	>	t = fence = tail;
838	>	cursor = head;
839	>	}
840	>	return t;
841	>	}
842	>
843	>	public DeqSpliterator trySplit() {
844	>	final Object[] es = elements;
845	>	final int i, n;
846	>	return ((n = sub(getFence(), i = cursor, es.length) >> 1) <= 0)
847	>	? null
848	>	: new DeqSpliterator(i, cursor = inc(i, n, es.length));
849	>	}
850	>
851	>	public void forEachRemaining(Consumer<? super E> action) {
852	>	if (action == null)
853	>	throw new NullPointerException();
854	>	final int end = getFence(), cursor = this.cursor;
855	>	final Object[] es = elements;
856	>	if (cursor != end) {
857	>	this.cursor = end;
858	>	// null check at both ends of range is sufficient
859	>	if (es[cursor] == null || es[dec(end, es.length)] == null)
860	>	throw new ConcurrentModificationException();
861	>	for (int i = cursor, to = (i <= end) ? end : es.length;
862	>	; i = 0, to = end) {
863	>	for (; i < to; i++)
864	>	action.accept(elementAt(es, i));
865	>	if (to == end) break;
866	>	}
867	>	}
868	>	}
869	>
870	>	public boolean tryAdvance(Consumer<? super E> action) {
871	>	Objects.requireNonNull(action);
872	>	final Object[] es = elements;
873	>	if (fence < 0) { fence = tail; cursor = head; } // late-binding
874	>	final int i;
875	>	if ((i = cursor) == fence)
876	>	return false;
877	>	E e = nonNullElementAt(es, i);
878	>	cursor = inc(i, es.length);
879	>	action.accept(e);
880	>	return true;
881	>	}
882	>
883	>	public long estimateSize() {
884	>	return sub(getFence(), cursor, elements.length);
885	>	}
886	>
887	>	public int characteristics() {
888	>	return Spliterator.NONNULL
889	>	| Spliterator.ORDERED
890	>	| Spliterator.SIZED
891	>	| Spliterator.SUBSIZED;
892	>	}
893	>	}
894	>
895	>	/**
896	>	* @throws NullPointerException {@inheritDoc}
897	>	*/
898	>	public void forEach(Consumer<? super E> action) {
899	>	Objects.requireNonNull(action);
900	>	final Object[] es = elements;
901	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
902	>	; i = 0, to = end) {
903	>	for (; i < to; i++)
904	>	action.accept(elementAt(es, i));
905	>	if (to == end) {
906	>	if (end != tail) throw new ConcurrentModificationException();
907	>	break;
908	>	}
909	>	}
910	>	// checkInvariants();
911	>	}
912	>
913	>	/**
914	>	* Replaces each element of this deque with the result of applying the
915	>	* operator to that element, as specified by {@link List#replaceAll}.
916	>	*
917	>	* @param operator the operator to apply to each element
918	>	* @since TBD
919	>	*/
920	>	/* public */ void replaceAll(UnaryOperator<E> operator) {
921	>	Objects.requireNonNull(operator);
922	>	final Object[] es = elements;
923	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
924	>	; i = 0, to = end) {
925	>	for (; i < to; i++)
926	>	es[i] = operator.apply(elementAt(es, i));
927	>	if (to == end) {
928	>	if (end != tail) throw new ConcurrentModificationException();
929	>	break;
930	>	}
931	>	}
932	>	// checkInvariants();
933	>	}
934	>
935	>	/**
936	>	* @throws NullPointerException {@inheritDoc}
937	>	*/
938	>	public boolean removeIf(Predicate<? super E> filter) {
939	>	Objects.requireNonNull(filter);
940	>	return bulkRemove(filter);
941	>	}
942	>
943	>	/**
944	>	* @throws NullPointerException {@inheritDoc}
945	>	*/
946	>	public boolean removeAll(Collection<?> c) {
947	>	Objects.requireNonNull(c);
948	>	return bulkRemove(e -> c.contains(e));
949	>	}
950	>
951	>	/**
952	>	* @throws NullPointerException {@inheritDoc}
953	>	*/
954	>	public boolean retainAll(Collection<?> c) {
955	>	Objects.requireNonNull(c);
956	>	return bulkRemove(e -> !c.contains(e));
957	>	}
958	>
959	>	/** Implementation of bulk remove methods. */
960	>	private boolean bulkRemove(Predicate<? super E> filter) {
961	>	// checkInvariants();
962	>	final Object[] es = elements;
963	>	// Optimize for initial run of survivors
964	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
965	>	; i = 0, to = end) {
966	>	for (; i < to; i++)
967	>	if (filter.test(elementAt(es, i)))
968	>	return bulkRemoveModified(filter, i);
969	>	if (to == end) {
970	>	if (end != tail) throw new ConcurrentModificationException();
971	>	break;
972	>	}
973	>	}
974	>	return false;
975	>	}
976	>
977	>	// A tiny bit set implementation
978	>
979	>	private static long[] nBits(int n) {
980	>	return new long[((n - 1) >> 6) + 1];
981	>	}
982	>	private static void setBit(long[] bits, int i) {
983	>	bits[i >> 6] |= 1L << i;
984	>	}
985	>	private static boolean isClear(long[] bits, int i) {
986	>	return (bits[i >> 6] & (1L << i)) == 0;
987	>	}
988	>
989	>	/**
990	>	* Helper for bulkRemove, in case of at least one deletion.
991	>	* Tolerate predicates that reentrantly access the collection for
992	>	* read (but writers still get CME), so traverse once to find
993	>	* elements to delete, a second pass to physically expunge.
994	>	*
995	>	* @param beg valid index of first element to be deleted
996	>	*/
997	>	private boolean bulkRemoveModified(
998	>	Predicate<? super E> filter, final int beg) {
999	>	final Object[] es = elements;
1000	>	final int capacity = es.length;
1001	>	final int end = tail;
1002	>	final long[] deathRow = nBits(sub(end, beg, capacity));
1003	>	deathRow[0] = 1L;   // set bit 0
1004	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1005	>	; i = 0, to = end, k -= capacity) {
1006	>	for (; i < to; i++)
1007	>	if (filter.test(elementAt(es, i)))
1008	>	setBit(deathRow, i - k);
1009	>	if (to == end) break;
1010	>	}
1011	>	// a two-finger traversal, with hare i reading, tortoise w writing
1012	>	int w = beg;
1013	>	for (int i = beg + 1, to = (i <= end) ? end : es.length, k = beg;
1014	>	; w = 0) { // w rejoins i on second leg
1015	>	// In this loop, i and w are on the same leg, with i > w
1016	>	for (; i < to; i++)
1017	>	if (isClear(deathRow, i - k))
1018	>	es[w++] = es[i];
1019	>	if (to == end) break;
1020	>	// In this loop, w is on the first leg, i on the second
1021	>	for (i = 0, to = end, k -= capacity; i < to && w < capacity; i++)
1022	>	if (isClear(deathRow, i - k))
1023	>	es[w++] = es[i];
1024	>	if (i >= to) {
1025	>	if (w == capacity) w = 0; // "corner" case
1026	>	break;
1027	>	}
1028	>	}
1029	>	if (end != tail) throw new ConcurrentModificationException();
1030	>	circularClear(es, tail = w, end);
1031	>	// checkInvariants();
1032	>	return true;
1033	>	}
1034	>
1035	>	/**
1036	>	* Returns {@code true} if this deque contains the specified element.
1037	>	* More formally, returns {@code true} if and only if this deque contains
1038	>	* at least one element {@code e} such that {@code o.equals(e)}.
1039		*
1040		* @param o object to be checked for containment in this deque
1041	<	* @return <tt>true</tt> if this deque contains the specified element
1041	>	* @return {@code true} if this deque contains the specified element
1042		*/
1043		public boolean contains(Object o) {
1044	<	if (o == null)
1045	<	return false;
1046	<	int mask = elements.length - 1;
1047	<	int i = head;
1048	<	E x;
1049	<	while ( (x = elements[i]) != null) {
1050	<	if (o.equals(x))
1051	<	return true;
1052	<	i = (i + 1) & mask;
1044	>	if (o != null) {
1045	>	final Object[] es = elements;
1046	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1047	>	; i = 0, to = end) {
1048	>	for (; i < to; i++)
1049	>	if (o.equals(es[i]))
1050	>	return true;
1051	>	if (to == end) break;
1052	>	}
1053		}
1054		return false;
1055		}
1056
1057		/**
1058		* Removes a single instance of the specified element from this deque.
1059	<	* This method is equivalent to {@link #removeFirstOccurrence}.
1059	>	* If the deque does not contain the element, it is unchanged.
1060	>	* More formally, removes the first element {@code e} such that
1061	>	* {@code o.equals(e)} (if such an element exists).
1062	>	* Returns {@code true} if this deque contained the specified element
1063	>	* (or equivalently, if this deque changed as a result of the call).
1064	>	*
1065	>	* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}.
1066		*
1067	<	* @param e element to be removed from this deque, if present
1068	<	* @return <tt>true</tt> if this deque contained the specified element
1067	>	* @param o element to be removed from this deque, if present
1068	>	* @return {@code true} if this deque contained the specified element
1069		*/
1070	<	public boolean remove(Object e) {
1071	<	return removeFirstOccurrence(e);
1070	>	public boolean remove(Object o) {
1071	>	return removeFirstOccurrence(o);
1072		}
1073
1074		/**
1075		* Removes all of the elements from this deque.
1076	+	* The deque will be empty after this call returns.
1077		*/
1078		public void clear() {
1079	<	int h = head;
1080	<	int t = tail;
1081	<	if (h != t) { // clear all cells
1082	<	head = tail = 0;
1083	<	int i = h;
1084	<	int mask = elements.length - 1;
1085	<	do {
1086	<	elements[i] = null;
1087	<	i = (i + 1) & mask;
1088	<	} while(i != t);
1079	>	circularClear(elements, head, tail);
1080	>	head = tail = 0;
1081	>	// checkInvariants();
1082	>	}
1083	>
1084	>	/**
1085	>	* Nulls out slots starting at array index i, upto index end.
1086	>	* Condition i == end means "empty" - nothing to do.
1087	>	*/
1088	>	private static void circularClear(Object[] es, int i, int end) {
1089	>	// assert 0 <= i && i < es.length;
1090	>	// assert 0 <= end && end < es.length;
1091	>	for (int to = (i <= end) ? end : es.length;
1092	>	; i = 0, to = end) {
1093	>	for (; i < to; i++) es[i] = null;
1094	>	if (to == end) break;
1095		}
1096		}
1097
1098		/**
1099	<	* Returns an array containing all of the elements in this list
1100	<	* in the correct order.
1099	>	* Returns an array containing all of the elements in this deque
1100	>	* in proper sequence (from first to last element).
1101		*
1102	<	* @return an array containing all of the elements in this list
1103	<	*         in the correct order
1102	>	* <p>The returned array will be "safe" in that no references to it are
1103	>	* maintained by this deque.  (In other words, this method must allocate
1104	>	* a new array).  The caller is thus free to modify the returned array.
1105	>	*
1106	>	* <p>This method acts as bridge between array-based and collection-based
1107	>	* APIs.
1108	>	*
1109	>	* @return an array containing all of the elements in this deque
1110		*/
1111		public Object[] toArray() {
1112	<	return copyElements(new Object[size()]);
1112	>	return toArray(Object[].class);
1113	>	}
1114	>
1115	>	private <T> T[] toArray(Class<T[]> klazz) {
1116	>	final Object[] es = elements;
1117	>	final T[] a;
1118	>	final int head = this.head, tail = this.tail, end;
1119	>	if ((end = tail + ((head <= tail) ? 0 : es.length)) >= 0) {
1120	>	// Uses null extension feature of copyOfRange
1121	>	a = Arrays.copyOfRange(es, head, end, klazz);
1122	>	} else {
1123	>	// integer overflow!
1124	>	a = Arrays.copyOfRange(es, 0, end - head, klazz);
1125	>	System.arraycopy(es, head, a, 0, es.length - head);
1126	>	}
1127	>	if (end != tail)
1128	>	System.arraycopy(es, 0, a, es.length - head, tail);
1129	>	return a;
1130		}
1131
1132		/**
1133	<	* Returns an array containing all of the elements in this deque in the
1134	<	* correct order; the runtime type of the returned array is that of the
1135	<	* specified array.  If the deque fits in the specified array, it is
1136	<	* returned therein.  Otherwise, a new array is allocated with the runtime
1137	<	* type of the specified array and the size of this deque.
1133	>	* Returns an array containing all of the elements in this deque in
1134	>	* proper sequence (from first to last element); the runtime type of the
1135	>	* returned array is that of the specified array.  If the deque fits in
1136	>	* the specified array, it is returned therein.  Otherwise, a new array
1137	>	* is allocated with the runtime type of the specified array and the
1138	>	* size of this deque.
1139	>	*
1140	>	* <p>If this deque fits in the specified array with room to spare
1141	>	* (i.e., the array has more elements than this deque), the element in
1142	>	* the array immediately following the end of the deque is set to
1143	>	* {@code null}.
1144	>	*
1145	>	* <p>Like the {@link #toArray()} method, this method acts as bridge between
1146	>	* array-based and collection-based APIs.  Further, this method allows
1147	>	* precise control over the runtime type of the output array, and may,
1148	>	* under certain circumstances, be used to save allocation costs.
1149	>	*
1150	>	* <p>Suppose {@code x} is a deque known to contain only strings.
1151	>	* The following code can be used to dump the deque into a newly
1152	>	* allocated array of {@code String}:
1153	>	*
1154	>	* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
1155		*
1156	<	* <p>If the deque fits in the specified array with room to spare (i.e.,
1157	<	* the array has more elements than the deque), the element in the array
693	<	* immediately following the end of the collection is set to <tt>null</tt>.
1156	>	* Note that {@code toArray(new Object[0])} is identical in function to
1157	>	* {@code toArray()}.
1158		*
1159		* @param a the array into which the elements of the deque are to
1160	<	*          be stored, if it is big enough; otherwise, a new array of the
1161	<	*          same runtime type is allocated for this purpose
1162	<	* @return an array containing the elements of the deque
1163	<	* @throws ArrayStoreException if the runtime type of a is not a supertype
1164	<	*         of the runtime type of every element in this deque
1160	>	*          be stored, if it is big enough; otherwise, a new array of the
1161	>	*          same runtime type is allocated for this purpose
1162	>	* @return an array containing all of the elements in this deque
1163	>	* @throws ArrayStoreException if the runtime type of the specified array
1164	>	*         is not a supertype of the runtime type of every element in
1165	>	*         this deque
1166	>	* @throws NullPointerException if the specified array is null
1167		*/
1168	+	@SuppressWarnings("unchecked")
1169		public <T> T[] toArray(T[] a) {
1170	<	int size = size();
1171	<	if (a.length < size)
1172	<	a = (T[])java.lang.reflect.Array.newInstance(
1173	<	a.getClass().getComponentType(), size);
1174	<	copyElements(a);
1175	<	if (a.length > size)
1170	>	final int size;
1171	>	if ((size = size()) > a.length)
1172	>	return toArray((Class<T[]>) a.getClass());
1173	>	final Object[] es = elements;
1174	>	for (int i = head, j = 0, len = Math.min(size, es.length - i);
1175	>	; i = 0, len = tail) {
1176	>	System.arraycopy(es, i, a, j, len);
1177	>	if ((j += len) == size) break;
1178	>	}
1179	>	if (size < a.length)
1180		a[size] = null;
1181		return a;
1182		}
#	Line 718 | Line 1189 | public class ArrayDeque<E> extends Abstr
1189		* @return a copy of this deque
1190		*/
1191		public ArrayDeque<E> clone() {
1192	<	try {
1192	>	try {
1193	>	@SuppressWarnings("unchecked")
1194		ArrayDeque<E> result = (ArrayDeque<E>) super.clone();
1195	<	// These two lines are currently faster than cloning the array:
724	<	result.elements = (E[]) new Object[elements.length];
725	<	System.arraycopy(elements, 0, result.elements, 0, elements.length);
1195	>	result.elements = Arrays.copyOf(elements, elements.length);
1196		return result;
1197	<
728	<	} catch (CloneNotSupportedException e) {
1197	>	} catch (CloneNotSupportedException e) {
1198		throw new AssertionError();
1199		}
1200		}
1201
733	–	/**
734	–	* Appease the serialization gods.
735	–	*/
1202		private static final long serialVersionUID = 2340985798034038923L;
1203
1204		/**
1205	<	* Serialize this deque.
1205	>	* Saves this deque to a stream (that is, serializes it).
1206		*
1207	<	* @serialData The current size (<tt>int</tt>) of the deque,
1207	>	* @param s the stream
1208	>	* @throws java.io.IOException if an I/O error occurs
1209	>	* @serialData The current size ({@code int}) of the deque,
1210		* followed by all of its elements (each an object reference) in
1211		* first-to-last order.
1212		*/
1213	<	private void writeObject(ObjectOutputStream s) throws IOException {
1213	>	private void writeObject(java.io.ObjectOutputStream s)
1214	>	throws java.io.IOException {
1215		s.defaultWriteObject();
1216
1217		// Write out size
1218	<	int size = size();
750	<	s.writeInt(size);
1218	>	s.writeInt(size());
1219
1220		// Write out elements in order.
1221	<	int i = head;
1222	<	int mask = elements.length - 1;
1223	<	for (int j = 0; j < size; j++) {
1224	<	s.writeObject(elements[i]);
1225	<	i = (i + 1) & mask;
1221	>	final Object[] es = elements;
1222	>	for (int i = head, end = tail, to = (i <= end) ? end : es.length;
1223	>	; i = 0, to = end) {
1224	>	for (; i < to; i++)
1225	>	s.writeObject(es[i]);
1226	>	if (to == end) break;
1227		}
1228		}
1229
1230		/**
1231	<	* Deserialize this deque.
1231	>	* Reconstitutes this deque from a stream (that is, deserializes it).
1232	>	* @param s the stream
1233	>	* @throws ClassNotFoundException if the class of a serialized object
1234	>	*         could not be found
1235	>	* @throws java.io.IOException if an I/O error occurs
1236		*/
1237	<	private void readObject(ObjectInputStream s)
1238	<	throws IOException, ClassNotFoundException {
1237	>	private void readObject(java.io.ObjectInputStream s)
1238	>	throws java.io.IOException, ClassNotFoundException {
1239		s.defaultReadObject();
1240
1241		// Read in size and allocate array
1242		int size = s.readInt();
1243	<	allocateElements(size);
1244	<	head = 0;
1245	<	tail = size;
1243	>	SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size + 1);
1244	>	elements = new Object[size + 1];
1245	>	this.tail = size;
1246
1247		// Read in all elements in the proper order.
1248		for (int i = 0; i < size; i++)
1249	<	elements[i] = (E)s.readObject();
1249	>	elements[i] = s.readObject();
1250	>	}
1251
1252	+	/** debugging */
1253	+	void checkInvariants() {
1254	+	// Use head and tail fields with empty slot at tail strategy.
1255	+	// head == tail disambiguates to "empty".
1256	+	try {
1257	+	int capacity = elements.length;
1258	+	// assert 0 <= head && head < capacity;
1259	+	// assert 0 <= tail && tail < capacity;
1260	+	// assert capacity > 0;
1261	+	// assert size() < capacity;
1262	+	// assert head == tail || elements[head] != null;
1263	+	// assert elements[tail] == null;
1264	+	// assert head == tail || elements[dec(tail, capacity)] != null;
1265	+	} catch (Throwable t) {
1266	+	System.err.printf("head=%d tail=%d capacity=%d%n",
1267	+	head, tail, elements.length);
1268	+	System.err.printf("elements=%s%n",
1269	+	Arrays.toString(elements));
1270	+	throw t;
1271	+	}
1272		}
1273	+
1274		}

Diff Legend

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