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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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package java.util; |
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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.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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* 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 Object[] 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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} |
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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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* 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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< |
@SuppressWarnings("unchecked") E result = (E) elements[h]; |
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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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|
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public E pollLast() { |
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int t = (tail - 1) & (elements.length - 1); |
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@SuppressWarnings("unchecked") E result = (E) 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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@SuppressWarnings("unchecked") E result = (E) elements[head]; |
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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 result; |
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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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* 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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* <p>This method is equivalent to {@link #addLast}. |
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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 Collection#add}) |
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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}) |
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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 |
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* (in other words, the first element of this deque), or returns |
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< |
* <tt>null</tt> if this deque is empty. |
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> |
* {@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 |
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< |
* <tt>null</tt> if this deque is empty |
459 |
> |
* {@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 |
481 |
< |
* this deque, or returns <tt>null</tt> if this deque is empty. |
481 |
> |
* this deque, or returns {@code null} if this deque is empty. |
482 |
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* |
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* <p>This method is equivalent to {@link #peekFirst}. |
484 |
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* |
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* @return the head of the queue represented by this deque, or |
486 |
< |
* <tt>null</tt> if this deque is empty |
486 |
> |
* {@code null} if this deque is empty |
487 |
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*/ |
488 |
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public E peek() { |
489 |
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return peekFirst(); |
587 |
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} |
588 |
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|
589 |
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/** |
590 |
< |
* Returns <tt>true</tt> if this deque contains no elements. |
590 |
> |
* Returns {@code true} if this deque contains no elements. |
591 |
|
* |
592 |
< |
* @return <tt>true</tt> if this deque contains no elements |
592 |
> |
* @return {@code true} if this deque contains no elements |
593 |
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*/ |
594 |
|
public boolean isEmpty() { |
595 |
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return head == tail; |
636 |
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public E next() { |
637 |
|
if (cursor == fence) |
638 |
|
throw new NoSuchElementException(); |
639 |
< |
@SuppressWarnings("unchecked") E result = (E) elements[cursor]; |
639 |
> |
@SuppressWarnings("unchecked") |
640 |
> |
E result = (E) elements[cursor]; |
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|
// This check doesn't catch all possible comodifications, |
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// but does catch the ones that corrupt traversal |
643 |
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if (tail != fence || result == null) |
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if (cursor == fence) |
677 |
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throw new NoSuchElementException(); |
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cursor = (cursor - 1) & (elements.length - 1); |
679 |
< |
@SuppressWarnings("unchecked") E result = (E) elements[cursor]; |
679 |
> |
@SuppressWarnings("unchecked") |
680 |
> |
E result = (E) elements[cursor]; |
681 |
|
if (head != fence || result == null) |
682 |
|
throw new ConcurrentModificationException(); |
683 |
|
lastRet = cursor; |
696 |
|
} |
697 |
|
|
698 |
|
/** |
699 |
< |
* Returns <tt>true</tt> if this deque contains the specified element. |
700 |
< |
* More formally, returns <tt>true</tt> if and only if this deque contains |
701 |
< |
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. |
699 |
> |
* Returns {@code true} if this deque contains the specified element. |
700 |
> |
* More formally, returns {@code true} if and only if this deque contains |
701 |
> |
* at least one element {@code e} such that {@code o.equals(e)}. |
702 |
|
* |
703 |
|
* @param o object to be checked for containment in this deque |
704 |
< |
* @return <tt>true</tt> if this deque contains the specified element |
704 |
> |
* @return {@code true} if this deque contains the specified element |
705 |
|
*/ |
706 |
|
public boolean contains(Object o) { |
707 |
|
if (o == null) |
720 |
|
/** |
721 |
|
* Removes a single instance of the specified element from this deque. |
722 |
|
* If the deque does not contain the element, it is unchanged. |
723 |
< |
* More formally, removes the first element <tt>e</tt> such that |
724 |
< |
* <tt>o.equals(e)</tt> (if such an element exists). |
725 |
< |
* Returns <tt>true</tt> if this deque contained the specified element |
723 |
> |
* More formally, removes the first element {@code e} such that |
724 |
> |
* {@code o.equals(e)} (if such an element exists). |
725 |
> |
* Returns {@code true} if this deque contained the specified element |
726 |
|
* (or equivalently, if this deque changed as a result of the call). |
727 |
|
* |
728 |
|
* <p>This method is equivalent to {@link #removeFirstOccurrence}. |
729 |
|
* |
730 |
|
* @param o element to be removed from this deque, if present |
731 |
< |
* @return <tt>true</tt> if this deque contained the specified element |
731 |
> |
* @return {@code true} if this deque contained the specified element |
732 |
|
*/ |
733 |
|
public boolean remove(Object o) { |
734 |
|
return removeFirstOccurrence(o); |
780 |
|
* <p>If this deque fits in the specified array with room to spare |
781 |
|
* (i.e., the array has more elements than this deque), the element in |
782 |
|
* the array immediately following the end of the deque is set to |
783 |
< |
* <tt>null</tt>. |
783 |
> |
* {@code null}. |
784 |
|
* |
785 |
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
786 |
|
* array-based and collection-based APIs. Further, this method allows |
787 |
|
* precise control over the runtime type of the output array, and may, |
788 |
|
* under certain circumstances, be used to save allocation costs. |
789 |
|
* |
790 |
< |
* <p>Suppose <tt>x</tt> is a deque known to contain only strings. |
790 |
> |
* <p>Suppose {@code x} is a deque known to contain only strings. |
791 |
|
* The following code can be used to dump the deque into a newly |
792 |
< |
* allocated array of <tt>String</tt>: |
792 |
> |
* allocated array of {@code String}: |
793 |
|
* |
794 |
|
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
795 |
|
* |
796 |
< |
* Note that <tt>toArray(new Object[0])</tt> is identical in function to |
797 |
< |
* <tt>toArray()</tt>. |
796 |
> |
* Note that {@code toArray(new Object[0])} is identical in function to |
797 |
> |
* {@code toArray()}. |
798 |
|
* |
799 |
|
* @param a the array into which the elements of the deque are to |
800 |
|
* be stored, if it is big enough; otherwise, a new array of the |
830 |
|
ArrayDeque<E> result = (ArrayDeque<E>) super.clone(); |
831 |
|
result.elements = Arrays.copyOf(elements, elements.length); |
832 |
|
return result; |
795 |
– |
|
833 |
|
} catch (CloneNotSupportedException e) { |
834 |
|
throw new AssertionError(); |
835 |
|
} |
836 |
|
} |
837 |
|
|
801 |
– |
/** |
802 |
– |
* Appease the serialization gods. |
803 |
– |
*/ |
838 |
|
private static final long serialVersionUID = 2340985798034038923L; |
839 |
|
|
840 |
|
/** |
841 |
< |
* Serialize this deque. |
841 |
> |
* Saves this deque to a stream (that is, serializes it). |
842 |
|
* |
843 |
< |
* @serialData The current size (<tt>int</tt>) of the deque, |
843 |
> |
* @serialData The current size ({@code int}) of the deque, |
844 |
|
* followed by all of its elements (each an object reference) in |
845 |
|
* first-to-last order. |
846 |
|
*/ |
858 |
|
} |
859 |
|
|
860 |
|
/** |
861 |
< |
* Deserialize this deque. |
861 |
> |
* Reconstitutes this deque from a stream (that is, deserializes it). |
862 |
|
*/ |
863 |
|
private void readObject(java.io.ObjectInputStream s) |
864 |
|
throws java.io.IOException, ClassNotFoundException { |
874 |
|
for (int i = 0; i < size; i++) |
875 |
|
elements[i] = s.readObject(); |
876 |
|
} |
877 |
+ |
|
878 |
+ |
public Stream<E> stream() { |
879 |
+ |
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); |
887 |
+ |
} |
888 |
+ |
|
889 |
+ |
|
890 |
+ |
static final class DeqSpliterator<E> implements Spliterator<E>, Iterator<E> { |
891 |
+ |
private final ArrayDeque<E> deq; |
892 |
+ |
private final Object[] array; |
893 |
+ |
private final int fence; // initially tail |
894 |
+ |
private int index; // current index, modified on traverse/split |
895 |
+ |
|
896 |
+ |
/** Create new spliterator covering the given array and range */ |
897 |
+ |
DeqSpliterator(ArrayDeque<E> deq, int origin, int fence) { |
898 |
+ |
this.deq = deq; this.array = deq.elements; |
899 |
+ |
this.index = origin; this.fence = fence; |
900 |
+ |
} |
901 |
+ |
|
902 |
+ |
public DeqSpliterator<E> trySplit() { |
903 |
+ |
int n = array.length; |
904 |
+ |
int h = index, t = fence; |
905 |
+ |
if (h != t && ((h + 1) & (n - 1)) != t) { |
906 |
+ |
if (h > t) |
907 |
+ |
t += n; |
908 |
+ |
int m = ((h + t) >>> 1) & (n - 1); |
909 |
+ |
return new DeqSpliterator<E>(deq, h, index = m); |
910 |
+ |
} |
911 |
+ |
return null; |
912 |
+ |
} |
913 |
+ |
|
914 |
+ |
@SuppressWarnings("unchecked") |
915 |
+ |
public void forEach(Block<? super E> block) { |
916 |
+ |
if (block == null) |
917 |
+ |
throw new NullPointerException(); |
918 |
+ |
Object[] a = array; |
919 |
+ |
if (a != deq.elements) |
920 |
+ |
throw new ConcurrentModificationException(); |
921 |
+ |
int m = a.length - 1, f = fence, i = index; |
922 |
+ |
index = f; |
923 |
+ |
while (i != f) { |
924 |
+ |
Object e = a[i]; |
925 |
+ |
if (e == null) |
926 |
+ |
throw new ConcurrentModificationException(); |
927 |
+ |
block.accept((E)e); |
928 |
+ |
i = (i + 1) & m; |
929 |
+ |
} |
930 |
+ |
} |
931 |
+ |
|
932 |
+ |
@SuppressWarnings("unchecked") |
933 |
+ |
public boolean tryAdvance(Block<? super E> block) { |
934 |
+ |
if (block == null) |
935 |
+ |
throw new NullPointerException(); |
936 |
+ |
Object[] a = array; |
937 |
+ |
if (a != deq.elements) |
938 |
+ |
throw new ConcurrentModificationException(); |
939 |
+ |
int m = a.length - 1, i = index; |
940 |
+ |
if (i != fence) { |
941 |
+ |
Object e = a[i]; |
942 |
+ |
if (e == null) |
943 |
+ |
throw new ConcurrentModificationException(); |
944 |
+ |
block.accept((E)e); |
945 |
+ |
index = (i + 1) & m; |
946 |
+ |
return true; |
947 |
+ |
} |
948 |
+ |
return false; |
949 |
+ |
} |
950 |
+ |
|
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 |
977 |
+ |
public long estimateSize() { |
978 |
+ |
int n = fence - index; |
979 |
+ |
if (n < 0) |
980 |
+ |
n += array.length; |
981 |
+ |
return (long)n; |
982 |
+ |
} |
983 |
+ |
public boolean hasExactSize() { return true; } |
984 |
+ |
public boolean hasExactSplits() { return true; } |
985 |
+ |
} |
986 |
+ |
|
987 |
|
} |