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/* |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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|
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/* |
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* This file is available under and governed by the GNU General Public |
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* License version 2 only, as published by the Free Software Foundation. |
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* However, the following notice accompanied the original version of this |
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* file: |
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* |
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* Written by Josh Bloch of Google Inc. and released to the public domain, |
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* as explained at http://creativecommons.org/publicdomain/zero/1.0/. |
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*/ |
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|
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package java.util; |
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< |
import java.util.Spliterator; |
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> |
import java.io.Serializable; |
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> |
import java.util.function.Consumer; |
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import java.util.stream.Stream; |
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import java.util.stream.Streams; |
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import java.util.function.Block; |
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|
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/** |
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* Resizable-array implementation of the {@link Deque} interface. Array |
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* when used as a queue. |
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* |
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* <p>Most {@code ArrayDeque} operations run in amortized constant time. |
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< |
* Exceptions include {@link #remove(Object) remove}, {@link |
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< |
* #removeFirstOccurrence removeFirstOccurrence}, {@link #removeLastOccurrence |
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< |
* removeLastOccurrence}, {@link #contains contains}, {@link #iterator |
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< |
* iterator.remove()}, and the bulk operations, all of which run in linear |
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< |
* time. |
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< |
* |
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< |
* <p>The iterators returned by this class's {@code iterator} method are |
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< |
* <i>fail-fast</i>: If the deque is modified at any time after the iterator |
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* is created, in any way except through the iterator's own {@code remove} |
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* method, the iterator will generally throw a {@link |
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> |
* Exceptions include |
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> |
* {@link #remove(Object) remove}, |
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> |
* {@link #removeFirstOccurrence removeFirstOccurrence}, |
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> |
* {@link #removeLastOccurrence removeLastOccurrence}, |
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* {@link #contains contains}, |
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* {@link #iterator iterator.remove()}, |
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> |
* and the bulk operations, all of which run in linear time. |
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> |
* |
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> |
* <p>The iterators returned by this class's {@link #iterator() iterator} |
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> |
* method are <em>fail-fast</em>: If the deque is modified at any time after |
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> |
* the iterator is created, in any way except through the iterator's own |
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> |
* {@code remove} method, the iterator will generally throw a {@link |
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* ConcurrentModificationException}. Thus, in the face of concurrent |
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* modification, the iterator fails quickly and cleanly, rather than risking |
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* arbitrary, non-deterministic behavior at an undetermined time in the |
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* |
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* @author Josh Bloch and Doug Lea |
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* @since 1.6 |
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< |
* @param <E> the type of elements held in this collection |
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> |
* @param <E> the type of elements held in this deque |
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*/ |
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public class ArrayDeque<E> extends AbstractCollection<E> |
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< |
implements Deque<E>, Cloneable, java.io.Serializable |
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> |
implements Deque<E>, Cloneable, Serializable |
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{ |
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/** |
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* The array in which the elements of the deque are stored. |
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} |
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|
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/** |
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* Copies the elements from our element array into the specified array, |
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* in order (from first to last element in the deque). It is assumed |
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* that the array is large enough to hold all elements in the deque. |
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– |
* |
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* @return its argument |
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– |
*/ |
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– |
private <T> T[] copyElements(T[] a) { |
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– |
if (head < tail) { |
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– |
System.arraycopy(elements, head, a, 0, size()); |
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– |
} else if (head > tail) { |
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– |
int headPortionLen = elements.length - head; |
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– |
System.arraycopy(elements, head, a, 0, headPortionLen); |
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– |
System.arraycopy(elements, 0, a, headPortionLen, tail); |
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– |
} |
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– |
return a; |
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– |
} |
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– |
|
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– |
/** |
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* Constructs an empty array deque with an initial capacity |
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* sufficient to hold 16 elements. |
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*/ |
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* @return {@code true} if the deque contained the specified element |
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*/ |
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public boolean removeFirstOccurrence(Object o) { |
| 318 |
< |
if (o == null) |
| 319 |
< |
return false; |
| 320 |
< |
int mask = elements.length - 1; |
| 321 |
< |
int i = head; |
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< |
Object x; |
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< |
while ( (x = elements[i]) != null) { |
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< |
if (o.equals(x)) { |
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< |
delete(i); |
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< |
return true; |
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> |
if (o != null) { |
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> |
int mask = elements.length - 1; |
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> |
int i = head; |
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> |
for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) { |
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> |
if (o.equals(x)) { |
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> |
delete(i); |
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> |
return true; |
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> |
} |
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} |
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– |
i = (i + 1) & mask; |
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} |
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return false; |
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} |
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* @return {@code true} if the deque contained the specified element |
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*/ |
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public boolean removeLastOccurrence(Object o) { |
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< |
if (o == null) |
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< |
return false; |
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< |
int mask = elements.length - 1; |
| 347 |
< |
int i = (tail - 1) & mask; |
| 348 |
< |
Object x; |
| 349 |
< |
while ( (x = elements[i]) != null) { |
| 350 |
< |
if (o.equals(x)) { |
| 351 |
< |
delete(i); |
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< |
return true; |
| 344 |
> |
if (o != null) { |
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> |
int mask = elements.length - 1; |
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> |
int i = (tail - 1) & mask; |
| 347 |
> |
for (Object x; (x = elements[i]) != null; i = (i - 1) & mask) { |
| 348 |
> |
if (o.equals(x)) { |
| 349 |
> |
delete(i); |
| 350 |
> |
return true; |
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> |
} |
| 352 |
|
} |
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– |
i = (i - 1) & mask; |
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} |
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return false; |
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|
} |
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|
} |
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} |
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|
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+ |
/** |
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+ |
* This class is nearly a mirror-image of DeqIterator, using tail |
| 613 |
+ |
* instead of head for initial cursor, and head instead of tail |
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+ |
* for fence. |
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+ |
*/ |
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|
private class DescendingIterator implements Iterator<E> { |
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– |
/* |
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* This class is nearly a mirror-image of DeqIterator, using |
| 664 |
– |
* tail instead of head for initial cursor, and head instead of |
| 665 |
– |
* tail for fence. |
| 666 |
– |
*/ |
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private int cursor = tail; |
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private int fence = head; |
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private int lastRet = -1; |
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* @return {@code true} if this deque contains the specified element |
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*/ |
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public boolean contains(Object o) { |
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< |
if (o == null) |
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< |
return false; |
| 659 |
< |
int mask = elements.length - 1; |
| 660 |
< |
int i = head; |
| 661 |
< |
Object x; |
| 662 |
< |
while ( (x = elements[i]) != null) { |
| 663 |
< |
if (o.equals(x)) |
| 714 |
< |
return true; |
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< |
i = (i + 1) & mask; |
| 657 |
> |
if (o != null) { |
| 658 |
> |
int mask = elements.length - 1; |
| 659 |
> |
int i = head; |
| 660 |
> |
for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) { |
| 661 |
> |
if (o.equals(x)) |
| 662 |
> |
return true; |
| 663 |
> |
} |
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|
} |
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return false; |
| 666 |
|
} |
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* Returns {@code true} if this deque contained the specified element |
| 674 |
|
* (or equivalently, if this deque changed as a result of the call). |
| 675 |
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* |
| 676 |
< |
* <p>This method is equivalent to {@link #removeFirstOccurrence}. |
| 676 |
> |
* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}. |
| 677 |
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* |
| 678 |
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* @param o element to be removed from this deque, if present |
| 679 |
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* @return {@code true} if this deque contained the specified element |
| 714 |
|
* @return an array containing all of the elements in this deque |
| 715 |
|
*/ |
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|
public Object[] toArray() { |
| 717 |
< |
return copyElements(new Object[size()]); |
| 717 |
> |
final int head = this.head; |
| 718 |
> |
final int tail = this.tail; |
| 719 |
> |
boolean wrap = (tail < head); |
| 720 |
> |
int end = wrap ? tail + elements.length : tail; |
| 721 |
> |
Object[] a = Arrays.copyOfRange(elements, head, end); |
| 722 |
> |
if (wrap) |
| 723 |
> |
System.arraycopy(elements, 0, a, elements.length - head, tail); |
| 724 |
> |
return a; |
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|
} |
| 726 |
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|
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|
/** |
| 762 |
|
*/ |
| 763 |
|
@SuppressWarnings("unchecked") |
| 764 |
|
public <T> T[] toArray(T[] a) { |
| 765 |
< |
int size = size(); |
| 766 |
< |
if (a.length < size) |
| 767 |
< |
a = (T[])java.lang.reflect.Array.newInstance( |
| 768 |
< |
a.getClass().getComponentType(), size); |
| 769 |
< |
copyElements(a); |
| 770 |
< |
if (a.length > size) |
| 771 |
< |
a[size] = null; |
| 765 |
> |
final int head = this.head; |
| 766 |
> |
final int tail = this.tail; |
| 767 |
> |
boolean wrap = (tail < head); |
| 768 |
> |
int size = (tail - head) + (wrap ? elements.length : 0); |
| 769 |
> |
int firstLeg = size - (wrap ? tail : 0); |
| 770 |
> |
int len = a.length; |
| 771 |
> |
if (size > len) { |
| 772 |
> |
a = (T[]) Arrays.copyOfRange(elements, head, head + size, |
| 773 |
> |
a.getClass()); |
| 774 |
> |
} else { |
| 775 |
> |
System.arraycopy(elements, head, a, 0, firstLeg); |
| 776 |
> |
if (size < len) |
| 777 |
> |
a[size] = null; |
| 778 |
> |
} |
| 779 |
> |
if (wrap) |
| 780 |
> |
System.arraycopy(elements, 0, a, firstLeg, tail); |
| 781 |
|
return a; |
| 782 |
|
} |
| 783 |
|
|
| 804 |
|
/** |
| 805 |
|
* Saves this deque to a stream (that is, serializes it). |
| 806 |
|
* |
| 807 |
+ |
* @param s the stream |
| 808 |
+ |
* @throws java.io.IOException if an I/O error occurs |
| 809 |
|
* @serialData The current size ({@code int}) of the deque, |
| 810 |
|
* followed by all of its elements (each an object reference) in |
| 811 |
|
* first-to-last order. |
| 825 |
|
|
| 826 |
|
/** |
| 827 |
|
* Reconstitutes this deque from a stream (that is, deserializes it). |
| 828 |
+ |
* @param s the stream |
| 829 |
+ |
* @throws ClassNotFoundException if the class of a serialized object |
| 830 |
+ |
* could not be found |
| 831 |
+ |
* @throws java.io.IOException if an I/O error occurs |
| 832 |
|
*/ |
| 833 |
|
private void readObject(java.io.ObjectInputStream s) |
| 834 |
|
throws java.io.IOException, ClassNotFoundException { |
| 845 |
|
elements[i] = s.readObject(); |
| 846 |
|
} |
| 847 |
|
|
| 848 |
< |
public Stream<E> stream() { |
| 849 |
< |
int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED; |
| 880 |
< |
return Streams.stream |
| 881 |
< |
(() -> new DeqSpliterator<E>(this, head, tail), flags); |
| 882 |
< |
} |
| 883 |
< |
public Stream<E> parallelStream() { |
| 884 |
< |
int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED; |
| 885 |
< |
return Streams.parallelStream |
| 886 |
< |
(() -> new DeqSpliterator<E>(this, head, tail), flags); |
| 848 |
> |
public Spliterator<E> spliterator() { |
| 849 |
> |
return new DeqSpliterator<E>(this, -1, -1); |
| 850 |
|
} |
| 851 |
|
|
| 852 |
< |
|
| 890 |
< |
static final class DeqSpliterator<E> implements Spliterator<E>, Iterator<E> { |
| 852 |
> |
static final class DeqSpliterator<E> implements Spliterator<E> { |
| 853 |
|
private final ArrayDeque<E> deq; |
| 854 |
< |
private final Object[] array; |
| 855 |
< |
private final int fence; // initially tail |
| 894 |
< |
private int index; // current index, modified on traverse/split |
| 854 |
> |
private int fence; // -1 until first use |
| 855 |
> |
private int index; // current index, modified on traverse/split |
| 856 |
|
|
| 857 |
< |
/** Create new spliterator covering the given array and range */ |
| 857 |
> |
/** Creates new spliterator covering the given array and range */ |
| 858 |
|
DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) { |
| 859 |
< |
this.deq = deq; this.array = deq.elements; |
| 860 |
< |
this.index = origin; this.fence = fence; |
| 859 |
> |
this.deq = deq; |
| 860 |
> |
this.index = origin; |
| 861 |
> |
this.fence = fence; |
| 862 |
> |
} |
| 863 |
> |
|
| 864 |
> |
private int getFence() { // force initialization |
| 865 |
> |
int t; |
| 866 |
> |
if ((t = fence) < 0) { |
| 867 |
> |
t = fence = deq.tail; |
| 868 |
> |
index = deq.head; |
| 869 |
> |
} |
| 870 |
> |
return t; |
| 871 |
|
} |
| 872 |
|
|
| 873 |
< |
public DeqSpliterator<E> trySplit() { |
| 874 |
< |
int n = array.length; |
| 904 |
< |
int h = index, t = fence; |
| 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<E>(deq, h, index = m); |
| 879 |
> |
return new DeqSpliterator<>(deq, h, index = m); |
| 880 |
|
} |
| 881 |
|
return null; |
| 882 |
|
} |
| 883 |
|
|
| 884 |
< |
@SuppressWarnings("unchecked") |
| 885 |
< |
public void forEach(Block<? super E> block) { |
| 916 |
< |
if (block == null) |
| 884 |
> |
public void forEachRemaining(Consumer<? super E> consumer) { |
| 885 |
> |
if (consumer == null) |
| 886 |
|
throw new NullPointerException(); |
| 887 |
< |
Object[] a = array; |
| 888 |
< |
if (a != deq.elements) |
| 920 |
< |
throw new ConcurrentModificationException(); |
| 921 |
< |
int m = a.length - 1, f = fence, i = index; |
| 887 |
> |
Object[] a = deq.elements; |
| 888 |
> |
int m = a.length - 1, f = getFence(), i = index; |
| 889 |
|
index = f; |
| 890 |
|
while (i != f) { |
| 891 |
< |
Object e = a[i]; |
| 891 |
> |
@SuppressWarnings("unchecked") E e = (E)a[i]; |
| 892 |
> |
i = (i + 1) & m; |
| 893 |
|
if (e == null) |
| 894 |
|
throw new ConcurrentModificationException(); |
| 895 |
< |
block.accept((E)e); |
| 928 |
< |
i = (i + 1) & m; |
| 895 |
> |
consumer.accept(e); |
| 896 |
|
} |
| 897 |
|
} |
| 898 |
|
|
| 899 |
< |
@SuppressWarnings("unchecked") |
| 900 |
< |
public boolean tryAdvance(Block<? super E> block) { |
| 934 |
< |
if (block == null) |
| 899 |
> |
public boolean tryAdvance(Consumer<? super E> consumer) { |
| 900 |
> |
if (consumer == null) |
| 901 |
|
throw new NullPointerException(); |
| 902 |
< |
Object[] a = array; |
| 903 |
< |
if (a != deq.elements) |
| 938 |
< |
throw new ConcurrentModificationException(); |
| 939 |
< |
int m = a.length - 1, i = index; |
| 902 |
> |
Object[] a = deq.elements; |
| 903 |
> |
int m = a.length - 1, f = getFence(), i = index; |
| 904 |
|
if (i != fence) { |
| 905 |
< |
Object e = a[i]; |
| 905 |
> |
@SuppressWarnings("unchecked") E e = (E)a[i]; |
| 906 |
> |
index = (i + 1) & m; |
| 907 |
|
if (e == null) |
| 908 |
|
throw new ConcurrentModificationException(); |
| 909 |
< |
block.accept((E)e); |
| 945 |
< |
index = (i + 1) & m; |
| 909 |
> |
consumer.accept(e); |
| 910 |
|
return true; |
| 911 |
|
} |
| 912 |
|
return false; |
| 913 |
|
} |
| 914 |
|
|
| 951 |
– |
// Iterator support |
| 952 |
– |
public Iterator<E> iterator() { |
| 953 |
– |
return this; |
| 954 |
– |
} |
| 955 |
– |
|
| 956 |
– |
public boolean hasNext() { |
| 957 |
– |
return index >= 0 && index != fence; |
| 958 |
– |
} |
| 959 |
– |
|
| 960 |
– |
@SuppressWarnings("unchecked") |
| 961 |
– |
public E next() { |
| 962 |
– |
if (index < 0 || index == fence) |
| 963 |
– |
throw new NoSuchElementException(); |
| 964 |
– |
Object[] a = array; |
| 965 |
– |
if (a != deq.elements) |
| 966 |
– |
throw new ConcurrentModificationException(); |
| 967 |
– |
Object e = a[index]; |
| 968 |
– |
if (e == null) |
| 969 |
– |
throw new ConcurrentModificationException(); |
| 970 |
– |
index = (index + 1) & (a.length - 1); |
| 971 |
– |
return (E) e; |
| 972 |
– |
} |
| 973 |
– |
|
| 974 |
– |
public void remove() { throw new UnsupportedOperationException(); } |
| 975 |
– |
|
| 976 |
– |
// Other spliterator methods |
| 915 |
|
public long estimateSize() { |
| 916 |
< |
int n = fence - index; |
| 916 |
> |
int n = getFence() - index; |
| 917 |
|
if (n < 0) |
| 918 |
< |
n += array.length; |
| 919 |
< |
return (long)n; |
| 918 |
> |
n += deq.elements.length; |
| 919 |
> |
return (long) n; |
| 920 |
> |
} |
| 921 |
> |
|
| 922 |
> |
@Override |
| 923 |
> |
public int characteristics() { |
| 924 |
> |
return Spliterator.ORDERED | Spliterator.SIZED | |
| 925 |
> |
Spliterator.NONNULL | Spliterator.SUBSIZED; |
| 926 |
|
} |
| 983 |
– |
public boolean hasExactSize() { return true; } |
| 984 |
– |
public boolean hasExactSplits() { return true; } |
| 927 |
|
} |
| 928 |
|
|
| 929 |
|
} |
