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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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* as explained at http://creativecommons.org/publicdomain/zero/1.0/. |
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*/ |
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package java.util; |
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import java.io.*; |
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import java.io.Serializable; |
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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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* 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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* <p>Most {@code ArrayDeque} operations run in amortized constant time. |
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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 <tt>iterator</tt> 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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* method, the iterator will generally throw a {@link |
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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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* <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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* |
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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, Serializable |
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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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* 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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* 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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* 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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|
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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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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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|
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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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if (result == null) |
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return null; |
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elements[h] = null; // Must null out slot |
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head = (h + 1) & (elements.length - 1); |
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final Object[] elements = this.elements; |
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final int h = head; |
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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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elements[h] = null; // Must null out slot |
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head = (h + 1) & (elements.length - 1); |
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} |
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return result; |
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} |
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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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if (result == null) |
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return null; |
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elements[t] = null; |
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tail = t; |
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final Object[] elements = this.elements; |
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final int t = (tail - 1) & (elements.length - 1); |
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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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elements[t] = null; |
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tail = t; |
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} |
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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 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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/** |
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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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< |
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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* 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. |
| 337 |
< |
* More formally, removes the last element <tt>e</tt> such that |
| 338 |
< |
* <tt>o.equals(e)</tt> (if such an element exists). |
| 339 |
< |
* Returns <tt>true</tt> if this deque contained the specified element |
| 337 |
> |
* More formally, removes the last element {@code e} such that |
| 338 |
> |
* {@code o.equals(e)} (if such an element exists). |
| 339 |
> |
* Returns {@code true} if this deque contained the specified element |
| 340 |
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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 |
| 343 |
< |
* @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) { |
| 346 |
< |
if (o == null) |
| 347 |
< |
return false; |
| 348 |
< |
int mask = elements.length - 1; |
| 349 |
< |
int i = (tail - 1) & mask; |
| 350 |
< |
E x; |
| 351 |
< |
while ( (x = elements[i]) != null) { |
| 352 |
< |
if (o.equals(x)) { |
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< |
delete(i); |
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< |
return true; |
| 346 |
> |
if (o != null) { |
| 347 |
> |
int mask = elements.length - 1; |
| 348 |
> |
int i = (tail - 1) & mask; |
| 349 |
> |
for (Object x; (x = elements[i]) != null; i = (i - 1) & mask) { |
| 350 |
> |
if (o.equals(x)) { |
| 351 |
> |
delete(i); |
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> |
return true; |
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> |
} |
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} |
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– |
i = (i - 1) & mask; |
| 355 |
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} |
| 356 |
|
return false; |
| 357 |
|
} |
| 364 |
|
* <p>This method is equivalent to {@link #addLast}. |
| 365 |
|
* |
| 366 |
|
* @param e the element to add |
| 367 |
< |
* @return <tt>true</tt> (as specified by {@link Collection#add}) |
| 367 |
> |
* @return {@code true} (as specified by {@link Collection#add}) |
| 368 |
|
* @throws NullPointerException if the specified element is null |
| 369 |
|
*/ |
| 370 |
|
public boolean add(E e) { |
| 378 |
|
* <p>This method is equivalent to {@link #offerLast}. |
| 379 |
|
* |
| 380 |
|
* @param e the element to add |
| 381 |
< |
* @return <tt>true</tt> (as specified by {@link Queue#offer}) |
| 381 |
> |
* @return {@code true} (as specified by {@link Queue#offer}) |
| 382 |
|
* @throws NullPointerException if the specified element is null |
| 383 |
|
*/ |
| 384 |
|
public boolean offer(E e) { |
| 403 |
|
/** |
| 404 |
|
* Retrieves and removes the head of the queue represented by this deque |
| 405 |
|
* (in other words, the first element of this deque), or returns |
| 406 |
< |
* <tt>null</tt> if this deque is empty. |
| 406 |
> |
* {@code null} if this deque is empty. |
| 407 |
|
* |
| 408 |
|
* <p>This method is equivalent to {@link #pollFirst}. |
| 409 |
|
* |
| 410 |
|
* @return the head of the queue represented by this deque, or |
| 411 |
< |
* <tt>null</tt> if this deque is empty |
| 411 |
> |
* {@code null} if this deque is empty |
| 412 |
|
*/ |
| 413 |
|
public E poll() { |
| 414 |
|
return pollFirst(); |
| 430 |
|
|
| 431 |
|
/** |
| 432 |
|
* Retrieves, but does not remove, the head of the queue represented by |
| 433 |
< |
* this deque, or returns <tt>null</tt> if this deque is empty. |
| 433 |
> |
* this deque, or returns {@code null} if this deque is empty. |
| 434 |
|
* |
| 435 |
|
* <p>This method is equivalent to {@link #peekFirst}. |
| 436 |
|
* |
| 437 |
|
* @return the head of the queue represented by this deque, or |
| 438 |
< |
* <tt>null</tt> if this deque is empty |
| 438 |
> |
* {@code null} if this deque is empty |
| 439 |
|
*/ |
| 440 |
|
public E peek() { |
| 441 |
|
return peekFirst(); |
| 490 |
|
*/ |
| 491 |
|
private boolean delete(int i) { |
| 492 |
|
checkInvariants(); |
| 493 |
< |
final E[] elements = this.elements; |
| 493 |
> |
final Object[] elements = this.elements; |
| 494 |
|
final int mask = elements.length - 1; |
| 495 |
|
final int h = head; |
| 496 |
|
final int t = tail; |
| 539 |
|
} |
| 540 |
|
|
| 541 |
|
/** |
| 542 |
< |
* Returns <tt>true</tt> if this deque contains no elements. |
| 542 |
> |
* Returns {@code true} if this deque contains no elements. |
| 543 |
|
* |
| 544 |
< |
* @return <tt>true</tt> if this deque contains no elements |
| 544 |
> |
* @return {@code true} if this deque contains no elements |
| 545 |
|
*/ |
| 546 |
|
public boolean isEmpty() { |
| 547 |
|
return head == tail; |
| 588 |
|
public E next() { |
| 589 |
|
if (cursor == fence) |
| 590 |
|
throw new NoSuchElementException(); |
| 591 |
< |
E result = elements[cursor]; |
| 591 |
> |
@SuppressWarnings("unchecked") |
| 592 |
> |
E result = (E) elements[cursor]; |
| 593 |
|
// This check doesn't catch all possible comodifications, |
| 594 |
|
// but does catch the ones that corrupt traversal |
| 595 |
|
if (tail != fence || result == null) |
| 608 |
|
} |
| 609 |
|
lastRet = -1; |
| 610 |
|
} |
| 611 |
+ |
|
| 612 |
+ |
public void forEachRemaining(Consumer<? super E> action) { |
| 613 |
+ |
Objects.requireNonNull(action); |
| 614 |
+ |
Object[] a = elements; |
| 615 |
+ |
int m = a.length - 1, f = fence, i = cursor; |
| 616 |
+ |
cursor = f; |
| 617 |
+ |
while (i != f) { |
| 618 |
+ |
@SuppressWarnings("unchecked") E e = (E)a[i]; |
| 619 |
+ |
i = (i + 1) & m; |
| 620 |
+ |
if (e == null) |
| 621 |
+ |
throw new ConcurrentModificationException(); |
| 622 |
+ |
action.accept(e); |
| 623 |
+ |
} |
| 624 |
+ |
} |
| 625 |
|
} |
| 626 |
|
|
| 627 |
+ |
/** |
| 628 |
+ |
* This class is nearly a mirror-image of DeqIterator, using tail |
| 629 |
+ |
* instead of head for initial cursor, and head instead of tail |
| 630 |
+ |
* for fence. |
| 631 |
+ |
*/ |
| 632 |
|
private class DescendingIterator implements Iterator<E> { |
| 621 |
– |
/* |
| 622 |
– |
* This class is nearly a mirror-image of DeqIterator, using |
| 623 |
– |
* tail instead of head for initial cursor, and head instead of |
| 624 |
– |
* tail for fence. |
| 625 |
– |
*/ |
| 633 |
|
private int cursor = tail; |
| 634 |
|
private int fence = head; |
| 635 |
|
private int lastRet = -1; |
| 642 |
|
if (cursor == fence) |
| 643 |
|
throw new NoSuchElementException(); |
| 644 |
|
cursor = (cursor - 1) & (elements.length - 1); |
| 645 |
< |
E result = elements[cursor]; |
| 645 |
> |
@SuppressWarnings("unchecked") |
| 646 |
> |
E result = (E) elements[cursor]; |
| 647 |
|
if (head != fence || result == null) |
| 648 |
|
throw new ConcurrentModificationException(); |
| 649 |
|
lastRet = cursor; |
| 662 |
|
} |
| 663 |
|
|
| 664 |
|
/** |
| 665 |
< |
* Returns <tt>true</tt> if this deque contains the specified element. |
| 666 |
< |
* More formally, returns <tt>true</tt> if and only if this deque contains |
| 667 |
< |
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. |
| 665 |
> |
* Returns {@code true} if this deque contains the specified element. |
| 666 |
> |
* More formally, returns {@code true} if and only if this deque contains |
| 667 |
> |
* at least one element {@code e} such that {@code o.equals(e)}. |
| 668 |
|
* |
| 669 |
|
* @param o object to be checked for containment in this deque |
| 670 |
< |
* @return <tt>true</tt> if this deque contains the specified element |
| 670 |
> |
* @return {@code true} if this deque contains the specified element |
| 671 |
|
*/ |
| 672 |
|
public boolean contains(Object o) { |
| 673 |
< |
if (o == null) |
| 674 |
< |
return false; |
| 675 |
< |
int mask = elements.length - 1; |
| 676 |
< |
int i = head; |
| 677 |
< |
E x; |
| 678 |
< |
while ( (x = elements[i]) != null) { |
| 679 |
< |
if (o.equals(x)) |
| 672 |
< |
return true; |
| 673 |
< |
i = (i + 1) & mask; |
| 673 |
> |
if (o != null) { |
| 674 |
> |
int mask = elements.length - 1; |
| 675 |
> |
int i = head; |
| 676 |
> |
for (Object x; (x = elements[i]) != null; i = (i + 1) & mask) { |
| 677 |
> |
if (o.equals(x)) |
| 678 |
> |
return true; |
| 679 |
> |
} |
| 680 |
|
} |
| 681 |
|
return false; |
| 682 |
|
} |
| 684 |
|
/** |
| 685 |
|
* Removes a single instance of the specified element from this deque. |
| 686 |
|
* If the deque does not contain the element, it is unchanged. |
| 687 |
< |
* More formally, removes the first element <tt>e</tt> such that |
| 688 |
< |
* <tt>o.equals(e)</tt> (if such an element exists). |
| 689 |
< |
* Returns <tt>true</tt> if this deque contained the specified element |
| 687 |
> |
* More formally, removes the first element {@code e} such that |
| 688 |
> |
* {@code o.equals(e)} (if such an element exists). |
| 689 |
> |
* Returns {@code true} if this deque contained the specified element |
| 690 |
|
* (or equivalently, if this deque changed as a result of the call). |
| 691 |
|
* |
| 692 |
< |
* <p>This method is equivalent to {@link #removeFirstOccurrence}. |
| 692 |
> |
* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}. |
| 693 |
|
* |
| 694 |
|
* @param o element to be removed from this deque, if present |
| 695 |
< |
* @return <tt>true</tt> if this deque contained the specified element |
| 695 |
> |
* @return {@code true} if this deque contained the specified element |
| 696 |
|
*/ |
| 697 |
|
public boolean remove(Object o) { |
| 698 |
|
return removeFirstOccurrence(o); |
| 730 |
|
* @return an array containing all of the elements in this deque |
| 731 |
|
*/ |
| 732 |
|
public Object[] toArray() { |
| 733 |
< |
return copyElements(new Object[size()]); |
| 733 |
> |
final int head = this.head; |
| 734 |
> |
final int tail = this.tail; |
| 735 |
> |
boolean wrap = (tail < head); |
| 736 |
> |
int end = wrap ? tail + elements.length : tail; |
| 737 |
> |
Object[] a = Arrays.copyOfRange(elements, head, end); |
| 738 |
> |
if (wrap) |
| 739 |
> |
System.arraycopy(elements, 0, a, elements.length - head, tail); |
| 740 |
> |
return a; |
| 741 |
|
} |
| 742 |
|
|
| 743 |
|
/** |
| 751 |
|
* <p>If this deque fits in the specified array with room to spare |
| 752 |
|
* (i.e., the array has more elements than this deque), the element in |
| 753 |
|
* the array immediately following the end of the deque is set to |
| 754 |
< |
* <tt>null</tt>. |
| 754 |
> |
* {@code null}. |
| 755 |
|
* |
| 756 |
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
| 757 |
|
* array-based and collection-based APIs. Further, this method allows |
| 758 |
|
* precise control over the runtime type of the output array, and may, |
| 759 |
|
* under certain circumstances, be used to save allocation costs. |
| 760 |
|
* |
| 761 |
< |
* <p>Suppose <tt>x</tt> is a deque known to contain only strings. |
| 761 |
> |
* <p>Suppose {@code x} is a deque known to contain only strings. |
| 762 |
|
* The following code can be used to dump the deque into a newly |
| 763 |
< |
* allocated array of <tt>String</tt>: |
| 763 |
> |
* allocated array of {@code String}: |
| 764 |
|
* |
| 765 |
< |
* <pre> |
| 753 |
< |
* String[] y = x.toArray(new String[0]);</pre> |
| 765 |
> |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
| 766 |
|
* |
| 767 |
< |
* Note that <tt>toArray(new Object[0])</tt> is identical in function to |
| 768 |
< |
* <tt>toArray()</tt>. |
| 767 |
> |
* Note that {@code toArray(new Object[0])} is identical in function to |
| 768 |
> |
* {@code toArray()}. |
| 769 |
|
* |
| 770 |
|
* @param a the array into which the elements of the deque are to |
| 771 |
|
* be stored, if it is big enough; otherwise, a new array of the |
| 776 |
|
* this deque |
| 777 |
|
* @throws NullPointerException if the specified array is null |
| 778 |
|
*/ |
| 779 |
+ |
@SuppressWarnings("unchecked") |
| 780 |
|
public <T> T[] toArray(T[] a) { |
| 781 |
< |
int size = size(); |
| 782 |
< |
if (a.length < size) |
| 783 |
< |
a = (T[])java.lang.reflect.Array.newInstance( |
| 784 |
< |
a.getClass().getComponentType(), size); |
| 785 |
< |
copyElements(a); |
| 786 |
< |
if (a.length > size) |
| 787 |
< |
a[size] = null; |
| 781 |
> |
final int head = this.head; |
| 782 |
> |
final int tail = this.tail; |
| 783 |
> |
boolean wrap = (tail < head); |
| 784 |
> |
int size = (tail - head) + (wrap ? elements.length : 0); |
| 785 |
> |
int firstLeg = size - (wrap ? tail : 0); |
| 786 |
> |
int len = a.length; |
| 787 |
> |
if (size > len) { |
| 788 |
> |
a = (T[]) Arrays.copyOfRange(elements, head, head + size, |
| 789 |
> |
a.getClass()); |
| 790 |
> |
} else { |
| 791 |
> |
System.arraycopy(elements, head, a, 0, firstLeg); |
| 792 |
> |
if (size < len) |
| 793 |
> |
a[size] = null; |
| 794 |
> |
} |
| 795 |
> |
if (wrap) |
| 796 |
> |
System.arraycopy(elements, 0, a, firstLeg, tail); |
| 797 |
|
return a; |
| 798 |
|
} |
| 799 |
|
|
| 806 |
|
*/ |
| 807 |
|
public ArrayDeque<E> clone() { |
| 808 |
|
try { |
| 809 |
+ |
@SuppressWarnings("unchecked") |
| 810 |
|
ArrayDeque<E> result = (ArrayDeque<E>) super.clone(); |
| 811 |
|
result.elements = Arrays.copyOf(elements, elements.length); |
| 812 |
|
return result; |
| 790 |
– |
|
| 813 |
|
} catch (CloneNotSupportedException e) { |
| 814 |
|
throw new AssertionError(); |
| 815 |
|
} |
| 816 |
|
} |
| 817 |
|
|
| 796 |
– |
/** |
| 797 |
– |
* Appease the serialization gods. |
| 798 |
– |
*/ |
| 818 |
|
private static final long serialVersionUID = 2340985798034038923L; |
| 819 |
|
|
| 820 |
|
/** |
| 821 |
< |
* Serialize this deque. |
| 821 |
> |
* Saves this deque to a stream (that is, serializes it). |
| 822 |
|
* |
| 823 |
< |
* @serialData The current size (<tt>int</tt>) of the deque, |
| 823 |
> |
* @param s the stream |
| 824 |
> |
* @throws java.io.IOException if an I/O error occurs |
| 825 |
> |
* @serialData The current size ({@code int}) of the deque, |
| 826 |
|
* followed by all of its elements (each an object reference) in |
| 827 |
|
* first-to-last order. |
| 828 |
|
*/ |
| 829 |
< |
private void writeObject(ObjectOutputStream s) throws IOException { |
| 829 |
> |
private void writeObject(java.io.ObjectOutputStream s) |
| 830 |
> |
throws java.io.IOException { |
| 831 |
|
s.defaultWriteObject(); |
| 832 |
|
|
| 833 |
|
// Write out size |
| 840 |
|
} |
| 841 |
|
|
| 842 |
|
/** |
| 843 |
< |
* Deserialize this deque. |
| 843 |
> |
* Reconstitutes this deque from a stream (that is, deserializes it). |
| 844 |
> |
* @param s the stream |
| 845 |
> |
* @throws ClassNotFoundException if the class of a serialized object |
| 846 |
> |
* could not be found |
| 847 |
> |
* @throws java.io.IOException if an I/O error occurs |
| 848 |
|
*/ |
| 849 |
< |
private void readObject(ObjectInputStream s) |
| 850 |
< |
throws IOException, ClassNotFoundException { |
| 849 |
> |
private void readObject(java.io.ObjectInputStream s) |
| 850 |
> |
throws java.io.IOException, ClassNotFoundException { |
| 851 |
|
s.defaultReadObject(); |
| 852 |
|
|
| 853 |
|
// Read in size and allocate array |
| 858 |
|
|
| 859 |
|
// Read in all elements in the proper order. |
| 860 |
|
for (int i = 0; i < size; i++) |
| 861 |
< |
elements[i] = (E)s.readObject(); |
| 861 |
> |
elements[i] = s.readObject(); |
| 862 |
> |
} |
| 863 |
> |
|
| 864 |
> |
/** |
| 865 |
> |
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> |
| 866 |
> |
* and <em>fail-fast</em> {@link Spliterator} over the elements in this |
| 867 |
> |
* deque. |
| 868 |
> |
* |
| 869 |
> |
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, |
| 870 |
> |
* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and |
| 871 |
> |
* {@link Spliterator#NONNULL}. Overriding implementations should document |
| 872 |
> |
* the reporting of additional characteristic values. |
| 873 |
> |
* |
| 874 |
> |
* @return a {@code Spliterator} over the elements in this deque |
| 875 |
> |
* @since 1.8 |
| 876 |
> |
*/ |
| 877 |
> |
public Spliterator<E> spliterator() { |
| 878 |
> |
return new DeqSpliterator<>(this, -1, -1); |
| 879 |
> |
} |
| 880 |
> |
|
| 881 |
> |
static final class DeqSpliterator<E> implements Spliterator<E> { |
| 882 |
> |
private final ArrayDeque<E> deq; |
| 883 |
> |
private int fence; // -1 until first use |
| 884 |
> |
private int index; // current index, modified on traverse/split |
| 885 |
> |
|
| 886 |
> |
/** Creates new spliterator covering the given array and range */ |
| 887 |
> |
DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) { |
| 888 |
> |
this.deq = deq; |
| 889 |
> |
this.index = origin; |
| 890 |
> |
this.fence = fence; |
| 891 |
> |
} |
| 892 |
> |
|
| 893 |
> |
private int getFence() { // force initialization |
| 894 |
> |
int t; |
| 895 |
> |
if ((t = fence) < 0) { |
| 896 |
> |
t = fence = deq.tail; |
| 897 |
> |
index = deq.head; |
| 898 |
> |
} |
| 899 |
> |
return t; |
| 900 |
> |
} |
| 901 |
> |
|
| 902 |
> |
public Spliterator<E> trySplit() { |
| 903 |
> |
int t = getFence(), h = index, n = deq.elements.length; |
| 904 |
> |
if (h != t && ((h + 1) & (n - 1)) != t) { |
| 905 |
> |
if (h > t) |
| 906 |
> |
t += n; |
| 907 |
> |
int m = ((h + t) >>> 1) & (n - 1); |
| 908 |
> |
return new DeqSpliterator<>(deq, h, index = m); |
| 909 |
> |
} |
| 910 |
> |
return null; |
| 911 |
> |
} |
| 912 |
> |
|
| 913 |
> |
public void forEachRemaining(Consumer<? super E> consumer) { |
| 914 |
> |
if (consumer == null) |
| 915 |
> |
throw new NullPointerException(); |
| 916 |
> |
Object[] a = deq.elements; |
| 917 |
> |
int m = a.length - 1, f = getFence(), i = index; |
| 918 |
> |
index = f; |
| 919 |
> |
while (i != f) { |
| 920 |
> |
@SuppressWarnings("unchecked") E e = (E)a[i]; |
| 921 |
> |
i = (i + 1) & m; |
| 922 |
> |
if (e == null) |
| 923 |
> |
throw new ConcurrentModificationException(); |
| 924 |
> |
consumer.accept(e); |
| 925 |
> |
} |
| 926 |
> |
} |
| 927 |
> |
|
| 928 |
> |
public boolean tryAdvance(Consumer<? super E> consumer) { |
| 929 |
> |
if (consumer == null) |
| 930 |
> |
throw new NullPointerException(); |
| 931 |
> |
Object[] a = deq.elements; |
| 932 |
> |
int m = a.length - 1, f = getFence(), i = index; |
| 933 |
> |
if (i != f) { |
| 934 |
> |
@SuppressWarnings("unchecked") E e = (E)a[i]; |
| 935 |
> |
index = (i + 1) & m; |
| 936 |
> |
if (e == null) |
| 937 |
> |
throw new ConcurrentModificationException(); |
| 938 |
> |
consumer.accept(e); |
| 939 |
> |
return true; |
| 940 |
> |
} |
| 941 |
> |
return false; |
| 942 |
> |
} |
| 943 |
> |
|
| 944 |
> |
public long estimateSize() { |
| 945 |
> |
int n = getFence() - index; |
| 946 |
> |
if (n < 0) |
| 947 |
> |
n += deq.elements.length; |
| 948 |
> |
return (long) n; |
| 949 |
> |
} |
| 950 |
> |
|
| 951 |
> |
@Override |
| 952 |
> |
public int characteristics() { |
| 953 |
> |
return Spliterator.ORDERED | Spliterator.SIZED | |
| 954 |
> |
Spliterator.NONNULL | Spliterator.SUBSIZED; |
| 955 |
> |
} |
| 956 |
|
} |
| 957 |
+ |
|
| 958 |
|
} |
