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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/licenses/publicdomain. |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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package java.util; |
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import java.util.*; // for javadoc (till 6280605 is fixed) |
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import java.io.*; |
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import java.util.Spliterator; |
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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.Consumer; |
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/** |
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* Resizable-array implementation of the {@link Deque} interface. Array |
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* {@link Stack} when used as a stack, and faster than {@link LinkedList} |
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* when used as a queue. |
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* |
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* <p>Most <tt>ArrayDeque</tt> operations run in amortized constant time. |
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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 <tt>iterator</tt> method are |
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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 <tt>remove</tt> |
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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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* 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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* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed |
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* as it is, generally speaking, impossible to make any hard guarantees in the |
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* presence of unsynchronized concurrent modification. Fail-fast iterators |
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* throw <tt>ConcurrentModificationException</tt> on a best-effort basis. |
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* throw {@code ConcurrentModificationException} on a best-effort basis. |
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* Therefore, it would be wrong to write a program that depended on this |
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* exception for its correctness: <i>the fail-fast behavior of iterators |
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* should be used only to detect bugs.</i> |
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* Iterator} interfaces. |
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* |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @author Josh Bloch and Doug Lea |
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* @param <E> the type of elements held in this collection |
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*/ |
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public class ArrayDeque<E> extends AbstractCollection<E> |
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implements Deque<E>, Cloneable, Serializable |
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implements Deque<E>, Cloneable, java.io.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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* other. We also guarantee that all array cells not holding |
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* deque elements are always null. |
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*/ |
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private transient E[] elements; |
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transient Object[] elements; // non-private to simplify nested class access |
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|
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/** |
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* The index of the element at the head of the deque (which is the |
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* element that would be removed by remove() or pop()); or an |
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* arbitrary number equal to tail if the deque is empty. |
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*/ |
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private transient int head; |
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transient int head; |
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|
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/** |
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* The index at which the next element would be added to the tail |
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* of the deque (via addLast(E), add(E), or push(E)). |
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*/ |
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private transient int tail; |
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transient int tail; |
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|
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/** |
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* The minimum capacity that we'll use for a newly created deque. |
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// ****** Array allocation and resizing utilities ****** |
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|
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/** |
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* Allocate empty array to hold the given number of elements. |
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* Allocates empty array to hold the given number of elements. |
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* |
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* @param numElements the number of elements to hold |
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*/ |
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if (initialCapacity < 0) // Too many elements, must back off |
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initialCapacity >>>= 1;// Good luck allocating 2 ^ 30 elements |
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} |
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elements = (E[]) new Object[initialCapacity]; |
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elements = new Object[initialCapacity]; |
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} |
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/** |
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* Double the capacity of this deque. Call only when full, i.e., |
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* Doubles the capacity of this deque. Call only when full, i.e., |
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* when head and tail have wrapped around to become equal. |
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*/ |
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private void doubleCapacity() { |
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Object[] a = new Object[newCapacity]; |
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System.arraycopy(elements, p, a, 0, r); |
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System.arraycopy(elements, 0, a, r, p); |
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elements = (E[])a; |
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elements = a; |
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head = 0; |
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tail = n; |
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} |
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* sufficient to hold 16 elements. |
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*/ |
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public ArrayDeque() { |
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elements = (E[]) new Object[16]; |
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elements = new Object[16]; |
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} |
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/** |
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* Inserts the specified element at the front of this deque. |
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* |
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* @param e the element to add |
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* @return <tt>true</tt> (as specified by {@link Deque#offerFirst}) |
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* @return {@code true} (as specified by {@link Deque#offerFirst}) |
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* @throws NullPointerException if the specified element is null |
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*/ |
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public boolean offerFirst(E e) { |
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* Inserts the specified element at the end of this deque. |
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* |
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* @param e the element to add |
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* @return <tt>true</tt> (as specified by {@link Deque#offerLast}) |
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* @return {@code true} (as specified by {@link Deque#offerLast}) |
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* @throws NullPointerException if the specified element is null |
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*/ |
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public boolean offerLast(E e) { |
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|
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public E pollFirst() { |
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int h = head; |
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E result = elements[h]; // Element is null if deque empty |
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@SuppressWarnings("unchecked") |
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E result = (E) elements[h]; |
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// Element is null if deque empty |
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if (result == null) |
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return null; |
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elements[h] = null; // Must null out slot |
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|
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public E pollLast() { |
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int t = (tail - 1) & (elements.length - 1); |
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E result = elements[t]; |
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@SuppressWarnings("unchecked") |
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E result = (E) elements[t]; |
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if (result == null) |
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return null; |
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elements[t] = null; |
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* @throws NoSuchElementException {@inheritDoc} |
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*/ |
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public E getFirst() { |
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E x = elements[head]; |
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if (x == null) |
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@SuppressWarnings("unchecked") |
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E result = (E) elements[head]; |
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if (result == null) |
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throw new NoSuchElementException(); |
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return x; |
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return result; |
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} |
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/** |
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* @throws NoSuchElementException {@inheritDoc} |
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*/ |
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public E getLast() { |
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E x = elements[(tail - 1) & (elements.length - 1)]; |
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if (x == null) |
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@SuppressWarnings("unchecked") |
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E result = (E) elements[(tail - 1) & (elements.length - 1)]; |
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if (result == null) |
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throw new NoSuchElementException(); |
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return x; |
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return result; |
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} |
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|
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@SuppressWarnings("unchecked") |
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public E peekFirst() { |
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return elements[head]; // elements[head] is null if deque empty |
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// elements[head] is null if deque empty |
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return (E) elements[head]; |
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} |
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|
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@SuppressWarnings("unchecked") |
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public E peekLast() { |
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return elements[(tail - 1) & (elements.length - 1)]; |
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return (E) elements[(tail - 1) & (elements.length - 1)]; |
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} |
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|
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/** |
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* Removes the first occurrence of the specified element in this |
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* deque (when traversing the deque from head to tail). |
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* If the deque does not contain the element, it is unchanged. |
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* More formally, removes the first element <tt>e</tt> such that |
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* <tt>o.equals(e)</tt> (if such an element exists). |
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* Returns <tt>true</tt> if this deque contained the specified element |
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* More formally, removes the first element {@code e} such that |
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* {@code o.equals(e)} (if such an element exists). |
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* Returns {@code true} if this deque contained the specified element |
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* (or equivalently, if this deque changed as a result of the call). |
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* |
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* @param o element to be removed from this deque, if present |
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* @return <tt>true</tt> if the deque contained the specified element |
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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) { |
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if (o == null) |
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return false; |
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int mask = elements.length - 1; |
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int i = head; |
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E x; |
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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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* Removes the last occurrence of the specified element in this |
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* deque (when traversing the deque from head to tail). |
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* If the deque does not contain the element, it is unchanged. |
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* More formally, removes the last element <tt>e</tt> such that |
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* <tt>o.equals(e)</tt> (if such an element exists). |
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* Returns <tt>true</tt> if this deque contained the specified element |
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* More formally, removes the last element {@code e} such that |
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* {@code o.equals(e)} (if such an element exists). |
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* Returns {@code true} if this deque contained the specified element |
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* (or equivalently, if this deque changed as a result of the call). |
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* |
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* @param o element to be removed from this deque, if present |
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* @return <tt>true</tt> if the deque contained the specified element |
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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; |
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int i = (tail - 1) & mask; |
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E x; |
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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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* <p>This method is equivalent to {@link #addLast}. |
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* |
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* @param e the element to add |
387 |
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* @return <tt>true</tt> (as specified by {@link Collection#add}) |
387 |
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* @return {@code true} (as specified by {@link Collection#add}) |
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* @throws NullPointerException if the specified element is null |
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*/ |
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public boolean add(E e) { |
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* <p>This method is equivalent to {@link #offerLast}. |
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* |
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* @param e the element to add |
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< |
* @return <tt>true</tt> (as specified by {@link Queue#offer}) |
401 |
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* @return {@code true} (as specified by {@link Queue#offer}) |
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* @throws NullPointerException if the specified element is null |
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*/ |
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public boolean offer(E e) { |
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/** |
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* Retrieves and removes the head of the queue represented by this deque |
425 |
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* (in other words, the first element of this deque), or returns |
426 |
< |
* <tt>null</tt> if this deque is empty. |
426 |
> |
* {@code null} if this deque is empty. |
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* |
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* <p>This method is equivalent to {@link #pollFirst}. |
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* |
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* @return the head of the queue represented by this deque, or |
431 |
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* <tt>null</tt> if this deque is empty |
431 |
> |
* {@code null} if this deque is empty |
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*/ |
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public E poll() { |
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return pollFirst(); |
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|
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/** |
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* Retrieves, but does not remove, the head of the queue represented by |
453 |
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* this deque, or returns <tt>null</tt> if this deque is empty. |
453 |
> |
* this deque, or returns {@code null} if this deque is empty. |
454 |
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* |
455 |
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* <p>This method is equivalent to {@link #peekFirst}. |
456 |
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* |
457 |
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* @return the head of the queue represented by this deque, or |
458 |
< |
* <tt>null</tt> if this deque is empty |
458 |
> |
* {@code null} if this deque is empty |
459 |
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*/ |
460 |
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public E peek() { |
461 |
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return peekFirst(); |
490 |
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return removeFirst(); |
491 |
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} |
492 |
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|
493 |
+ |
private void checkInvariants() { |
494 |
+ |
assert elements[tail] == null; |
495 |
+ |
assert head == tail ? elements[head] == null : |
496 |
+ |
(elements[head] != null && |
497 |
+ |
elements[(tail - 1) & (elements.length - 1)] != null); |
498 |
+ |
assert elements[(head - 1) & (elements.length - 1)] == null; |
499 |
+ |
} |
500 |
+ |
|
501 |
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/** |
502 |
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* Removes the element at the specified position in the elements array, |
503 |
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* adjusting head and tail as necessary. This can result in motion of |
509 |
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* @return true if elements moved backwards |
510 |
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*/ |
511 |
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private boolean delete(int i) { |
512 |
< |
int mask = elements.length - 1; |
513 |
< |
|
514 |
< |
// Invariant: head <= i < tail mod circularity |
515 |
< |
if (((i - head) & mask) >= ((tail - head) & mask)) |
516 |
< |
throw new ConcurrentModificationException(); |
517 |
< |
|
518 |
< |
// Case 1: Deque doesn't wrap |
519 |
< |
// Case 2: Deque does wrap and removed element is in the head portion |
520 |
< |
if (i >= head) { |
521 |
< |
System.arraycopy(elements, head, elements, head + 1, i - head); |
522 |
< |
elements[head] = null; |
523 |
< |
head = (head + 1) & mask; |
512 |
> |
checkInvariants(); |
513 |
> |
final Object[] elements = this.elements; |
514 |
> |
final int mask = elements.length - 1; |
515 |
> |
final int h = head; |
516 |
> |
final int t = tail; |
517 |
> |
final int front = (i - h) & mask; |
518 |
> |
final int back = (t - i) & mask; |
519 |
> |
|
520 |
> |
// Invariant: head <= i < tail mod circularity |
521 |
> |
if (front >= ((t - h) & mask)) |
522 |
> |
throw new ConcurrentModificationException(); |
523 |
> |
|
524 |
> |
// Optimize for least element motion |
525 |
> |
if (front < back) { |
526 |
> |
if (h <= i) { |
527 |
> |
System.arraycopy(elements, h, elements, h + 1, front); |
528 |
> |
} else { // Wrap around |
529 |
> |
System.arraycopy(elements, 0, elements, 1, i); |
530 |
> |
elements[0] = elements[mask]; |
531 |
> |
System.arraycopy(elements, h, elements, h + 1, mask - h); |
532 |
> |
} |
533 |
> |
elements[h] = null; |
534 |
> |
head = (h + 1) & mask; |
535 |
|
return false; |
536 |
+ |
} else { |
537 |
+ |
if (i < t) { // Copy the null tail as well |
538 |
+ |
System.arraycopy(elements, i + 1, elements, i, back); |
539 |
+ |
tail = t - 1; |
540 |
+ |
} else { // Wrap around |
541 |
+ |
System.arraycopy(elements, i + 1, elements, i, mask - i); |
542 |
+ |
elements[mask] = elements[0]; |
543 |
+ |
System.arraycopy(elements, 1, elements, 0, t); |
544 |
+ |
tail = (t - 1) & mask; |
545 |
+ |
} |
546 |
+ |
return true; |
547 |
|
} |
507 |
– |
|
508 |
– |
// Case 3: Deque wraps and removed element is in the tail portion |
509 |
– |
tail--; |
510 |
– |
System.arraycopy(elements, i + 1, elements, i, tail - i); |
511 |
– |
elements[tail] = null; |
512 |
– |
return true; |
548 |
|
} |
549 |
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|
550 |
|
// *** Collection Methods *** |
559 |
|
} |
560 |
|
|
561 |
|
/** |
562 |
< |
* Returns <tt>true</tt> if this deque contains no elements. |
562 |
> |
* Returns {@code true} if this deque contains no elements. |
563 |
|
* |
564 |
< |
* @return <tt>true</tt> if this deque contains no elements |
564 |
> |
* @return {@code true} if this deque contains no elements |
565 |
|
*/ |
566 |
|
public boolean isEmpty() { |
567 |
|
return head == tail; |
606 |
|
} |
607 |
|
|
608 |
|
public E next() { |
574 |
– |
E result; |
609 |
|
if (cursor == fence) |
610 |
|
throw new NoSuchElementException(); |
611 |
+ |
@SuppressWarnings("unchecked") |
612 |
+ |
E result = (E) elements[cursor]; |
613 |
|
// This check doesn't catch all possible comodifications, |
614 |
|
// but does catch the ones that corrupt traversal |
615 |
< |
if (tail != fence || (result = elements[cursor]) == null) |
615 |
> |
if (tail != fence || result == null) |
616 |
|
throw new ConcurrentModificationException(); |
617 |
|
lastRet = cursor; |
618 |
|
cursor = (cursor + 1) & (elements.length - 1); |
622 |
|
public void remove() { |
623 |
|
if (lastRet < 0) |
624 |
|
throw new IllegalStateException(); |
625 |
< |
if (delete(lastRet)) // if left-shifted, undo increment in next() |
625 |
> |
if (delete(lastRet)) { // if left-shifted, undo increment in next() |
626 |
|
cursor = (cursor - 1) & (elements.length - 1); |
627 |
+ |
fence = tail; |
628 |
+ |
} |
629 |
|
lastRet = -1; |
592 |
– |
fence = tail; |
630 |
|
} |
631 |
|
} |
632 |
|
|
596 |
– |
|
633 |
|
private class DescendingIterator implements Iterator<E> { |
634 |
|
/* |
635 |
|
* This class is nearly a mirror-image of DeqIterator, using |
636 |
< |
* (tail-1) instead of head for initial cursor, (head-1) |
637 |
< |
* instead of tail for fence, and elements.length instead of -1 |
602 |
< |
* for sentinel. It shares the same structure, but not many |
603 |
< |
* actual lines of code. |
636 |
> |
* tail instead of head for initial cursor, and head instead of |
637 |
> |
* tail for fence. |
638 |
|
*/ |
639 |
< |
private int cursor = (tail - 1) & (elements.length - 1); |
640 |
< |
private int fence = (head - 1) & (elements.length - 1); |
641 |
< |
private int lastRet = elements.length; |
639 |
> |
private int cursor = tail; |
640 |
> |
private int fence = head; |
641 |
> |
private int lastRet = -1; |
642 |
|
|
643 |
|
public boolean hasNext() { |
644 |
|
return cursor != fence; |
645 |
|
} |
646 |
|
|
647 |
|
public E next() { |
614 |
– |
E result; |
648 |
|
if (cursor == fence) |
649 |
|
throw new NoSuchElementException(); |
650 |
< |
if (((head - 1) & (elements.length - 1)) != fence || |
651 |
< |
(result = elements[cursor]) == null) |
650 |
> |
cursor = (cursor - 1) & (elements.length - 1); |
651 |
> |
@SuppressWarnings("unchecked") |
652 |
> |
E result = (E) elements[cursor]; |
653 |
> |
if (head != fence || result == null) |
654 |
|
throw new ConcurrentModificationException(); |
655 |
|
lastRet = cursor; |
621 |
– |
cursor = (cursor - 1) & (elements.length - 1); |
656 |
|
return result; |
657 |
|
} |
658 |
|
|
659 |
|
public void remove() { |
660 |
< |
if (lastRet >= elements.length) |
660 |
> |
if (lastRet < 0) |
661 |
|
throw new IllegalStateException(); |
662 |
< |
if (!delete(lastRet)) |
662 |
> |
if (!delete(lastRet)) { |
663 |
|
cursor = (cursor + 1) & (elements.length - 1); |
664 |
< |
lastRet = elements.length; |
665 |
< |
fence = (head - 1) & (elements.length - 1); |
664 |
> |
fence = head; |
665 |
> |
} |
666 |
> |
lastRet = -1; |
667 |
|
} |
668 |
|
} |
669 |
|
|
670 |
|
/** |
671 |
< |
* Returns <tt>true</tt> if this deque contains the specified element. |
672 |
< |
* More formally, returns <tt>true</tt> if and only if this deque contains |
673 |
< |
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. |
671 |
> |
* Returns {@code true} if this deque contains the specified element. |
672 |
> |
* More formally, returns {@code true} if and only if this deque contains |
673 |
> |
* at least one element {@code e} such that {@code o.equals(e)}. |
674 |
|
* |
675 |
|
* @param o object to be checked for containment in this deque |
676 |
< |
* @return <tt>true</tt> if this deque contains the specified element |
676 |
> |
* @return {@code true} if this deque contains the specified element |
677 |
|
*/ |
678 |
|
public boolean contains(Object o) { |
679 |
|
if (o == null) |
680 |
|
return false; |
681 |
|
int mask = elements.length - 1; |
682 |
|
int i = head; |
683 |
< |
E x; |
683 |
> |
Object x; |
684 |
|
while ( (x = elements[i]) != null) { |
685 |
|
if (o.equals(x)) |
686 |
|
return true; |
692 |
|
/** |
693 |
|
* Removes a single instance of the specified element from this deque. |
694 |
|
* If the deque does not contain the element, it is unchanged. |
695 |
< |
* More formally, removes the first element <tt>e</tt> such that |
696 |
< |
* <tt>o.equals(e)</tt> (if such an element exists). |
697 |
< |
* Returns <tt>true</tt> if this deque contained the specified element |
695 |
> |
* More formally, removes the first element {@code e} such that |
696 |
> |
* {@code o.equals(e)} (if such an element exists). |
697 |
> |
* Returns {@code true} if this deque contained the specified element |
698 |
|
* (or equivalently, if this deque changed as a result of the call). |
699 |
|
* |
700 |
< |
* <p>This method is equivalent to {@link #removeFirstOccurrence}. |
700 |
> |
* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}. |
701 |
|
* |
702 |
|
* @param o element to be removed from this deque, if present |
703 |
< |
* @return <tt>true</tt> if this deque contained the specified element |
703 |
> |
* @return {@code true} if this deque contained the specified element |
704 |
|
*/ |
705 |
|
public boolean remove(Object o) { |
706 |
|
return removeFirstOccurrence(o); |
738 |
|
* @return an array containing all of the elements in this deque |
739 |
|
*/ |
740 |
|
public Object[] toArray() { |
741 |
< |
return copyElements(new Object[size()]); |
741 |
> |
return copyElements(new Object[size()]); |
742 |
|
} |
743 |
|
|
744 |
|
/** |
752 |
|
* <p>If this deque fits in the specified array with room to spare |
753 |
|
* (i.e., the array has more elements than this deque), the element in |
754 |
|
* the array immediately following the end of the deque is set to |
755 |
< |
* <tt>null</tt>. |
755 |
> |
* {@code null}. |
756 |
|
* |
757 |
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
758 |
|
* array-based and collection-based APIs. Further, this method allows |
759 |
|
* precise control over the runtime type of the output array, and may, |
760 |
|
* under certain circumstances, be used to save allocation costs. |
761 |
|
* |
762 |
< |
* <p>Suppose <tt>x</tt> is a deque known to contain only strings. |
762 |
> |
* <p>Suppose {@code x} is a deque known to contain only strings. |
763 |
|
* The following code can be used to dump the deque into a newly |
764 |
< |
* allocated array of <tt>String</tt>: |
764 |
> |
* allocated array of {@code String}: |
765 |
|
* |
766 |
< |
* <pre> |
732 |
< |
* String[] y = x.toArray(new String[0]);</pre> |
766 |
> |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
767 |
|
* |
768 |
< |
* Note that <tt>toArray(new Object[0])</tt> is identical in function to |
769 |
< |
* <tt>toArray()</tt>. |
768 |
> |
* Note that {@code toArray(new Object[0])} is identical in function to |
769 |
> |
* {@code toArray()}. |
770 |
|
* |
771 |
|
* @param a the array into which the elements of the deque are to |
772 |
|
* be stored, if it is big enough; otherwise, a new array of the |
777 |
|
* this deque |
778 |
|
* @throws NullPointerException if the specified array is null |
779 |
|
*/ |
780 |
+ |
@SuppressWarnings("unchecked") |
781 |
|
public <T> T[] toArray(T[] a) { |
782 |
|
int size = size(); |
783 |
|
if (a.length < size) |
784 |
|
a = (T[])java.lang.reflect.Array.newInstance( |
785 |
|
a.getClass().getComponentType(), size); |
786 |
< |
copyElements(a); |
786 |
> |
copyElements(a); |
787 |
|
if (a.length > size) |
788 |
|
a[size] = null; |
789 |
|
return a; |
798 |
|
*/ |
799 |
|
public ArrayDeque<E> clone() { |
800 |
|
try { |
801 |
+ |
@SuppressWarnings("unchecked") |
802 |
|
ArrayDeque<E> result = (ArrayDeque<E>) super.clone(); |
803 |
< |
// These two lines are currently faster than cloning the array: |
768 |
< |
result.elements = (E[]) new Object[elements.length]; |
769 |
< |
System.arraycopy(elements, 0, result.elements, 0, elements.length); |
803 |
> |
result.elements = Arrays.copyOf(elements, elements.length); |
804 |
|
return result; |
771 |
– |
|
805 |
|
} catch (CloneNotSupportedException e) { |
806 |
|
throw new AssertionError(); |
807 |
|
} |
808 |
|
} |
809 |
|
|
777 |
– |
/** |
778 |
– |
* Appease the serialization gods. |
779 |
– |
*/ |
810 |
|
private static final long serialVersionUID = 2340985798034038923L; |
811 |
|
|
812 |
|
/** |
813 |
< |
* Serialize this deque. |
813 |
> |
* Saves this deque to a stream (that is, serializes it). |
814 |
|
* |
815 |
< |
* @serialData The current size (<tt>int</tt>) of the deque, |
815 |
> |
* @serialData The current size ({@code int}) of the deque, |
816 |
|
* followed by all of its elements (each an object reference) in |
817 |
|
* first-to-last order. |
818 |
|
*/ |
819 |
< |
private void writeObject(ObjectOutputStream s) throws IOException { |
819 |
> |
private void writeObject(java.io.ObjectOutputStream s) |
820 |
> |
throws java.io.IOException { |
821 |
|
s.defaultWriteObject(); |
822 |
|
|
823 |
|
// Write out size |
830 |
|
} |
831 |
|
|
832 |
|
/** |
833 |
< |
* Deserialize this deque. |
833 |
> |
* Reconstitutes this deque from a stream (that is, deserializes it). |
834 |
|
*/ |
835 |
< |
private void readObject(ObjectInputStream s) |
836 |
< |
throws IOException, ClassNotFoundException { |
835 |
> |
private void readObject(java.io.ObjectInputStream s) |
836 |
> |
throws java.io.IOException, ClassNotFoundException { |
837 |
|
s.defaultReadObject(); |
838 |
|
|
839 |
|
// Read in size and allocate array |
844 |
|
|
845 |
|
// Read in all elements in the proper order. |
846 |
|
for (int i = 0; i < size; i++) |
847 |
< |
elements[i] = (E)s.readObject(); |
847 |
> |
elements[i] = s.readObject(); |
848 |
> |
} |
849 |
> |
|
850 |
> |
public Stream<E> stream() { |
851 |
> |
int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED; |
852 |
> |
return Streams.stream |
853 |
> |
(() -> new DeqSpliterator<E>(this, head, tail), flags); |
854 |
> |
} |
855 |
> |
public Stream<E> parallelStream() { |
856 |
> |
int flags = Streams.STREAM_IS_ORDERED | Streams.STREAM_IS_SIZED; |
857 |
> |
return Streams.parallelStream |
858 |
> |
(() -> new DeqSpliterator<E>(this, head, tail), flags); |
859 |
> |
} |
860 |
> |
|
861 |
> |
|
862 |
> |
static final class DeqSpliterator<E> implements Spliterator<E> { |
863 |
> |
private final ArrayDeque<E> deq; |
864 |
> |
private final int fence; // initially tail |
865 |
> |
private int index; // current index, modified on traverse/split |
866 |
> |
|
867 |
> |
/** Create new spliterator covering the given array and range */ |
868 |
> |
DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) { |
869 |
> |
this.deq = deq; this.index = origin; this.fence = fence; |
870 |
> |
} |
871 |
> |
|
872 |
> |
public DeqSpliterator<E> trySplit() { |
873 |
> |
int n = deq.elements.length; |
874 |
> |
int h = index, t = fence; |
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); |
880 |
> |
} |
881 |
> |
return null; |
882 |
> |
} |
883 |
> |
|
884 |
> |
public void forEach(Consumer<? super E> block) { |
885 |
> |
if (block == null) |
886 |
> |
throw new NullPointerException(); |
887 |
> |
Object[] a = deq.elements; |
888 |
> |
int m = a.length - 1, f = fence, 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 |
> |
block.accept(e); |
896 |
> |
} |
897 |
> |
} |
898 |
> |
|
899 |
> |
public boolean tryAdvance(Consumer<? super E> block) { |
900 |
> |
if (block == null) |
901 |
> |
throw new NullPointerException(); |
902 |
> |
Object[] a = deq.elements; |
903 |
> |
int m = a.length - 1, 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 |
> |
block.accept(e); |
910 |
> |
return true; |
911 |
> |
} |
912 |
> |
return false; |
913 |
> |
} |
914 |
|
|
915 |
+ |
// Other spliterator methods |
916 |
+ |
public long estimateSize() { |
917 |
+ |
int n = fence - index; |
918 |
+ |
if (n < 0) |
919 |
+ |
n += deq.elements.length; |
920 |
+ |
return (long)n; |
921 |
+ |
} |
922 |
+ |
public boolean hasExactSize() { return true; } |
923 |
+ |
public boolean hasExactSplits() { return true; } |
924 |
|
} |
925 |
+ |
|
926 |
|
} |