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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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|
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import java.io.Serializable; |
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import java.util.function.Consumer; |
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import java.util.function.Predicate; |
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import java.util.function.UnaryOperator; |
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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 remove method, the |
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* iterator will generally throw a {@link ConcurrentModificationException}. |
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* Thus, in the face of concurrent modification, the iterator fails quickly |
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* and cleanly, rather than risking arbitrary, non-deterministic behavior at |
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* an undetermined time in the future. |
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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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* future. |
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* |
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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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* <p>This class and its iterator implement all of the |
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* optional methods of the {@link Collection} and {@link |
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* Iterator} interfaces. This class is a member of the <a |
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* href="{@docRoot}/../guide/collections/index.html"> Java Collections |
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* Framework</a>. |
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* <em>optional</em> methods of the {@link Collection} and {@link |
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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}/../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 deque |
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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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*/ |
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public class ArrayDeque<E> extends AbstractCollection<E> |
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implements Deque<E>, Cloneable, Serializable |
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{ |
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/** |
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* The array in which the elements of in the deque are stored. |
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* The capacity of the deque is the length of this array, which is |
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* always a power of two. The array is never allowed to become |
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* full, except transiently within an addX method where it is |
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* resized (see doubleCapacity) immediately upon becoming full, |
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* thus avoiding head and tail wrapping around to equal each |
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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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* The array in which the elements of the deque are stored. |
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* We guarantee that all array cells not holding deque elements |
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* are always null. |
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*/ |
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private transient E[] elements; |
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transient Object[] elements; |
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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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|
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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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|
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/** |
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* The minimum capacity that we'll use for a newly created deque. |
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* Must be a power of 2. |
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* arbitrary number 0 <= head < elements.length if the deque is empty. |
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*/ |
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private static final int MIN_INITIAL_CAPACITY = 8; |
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transient int head; |
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|
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// ****** Array allocation and resizing utilities ****** |
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/** Number of elements in this collection. */ |
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transient int size; |
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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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* |
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* @param numElements the number of elements to hold. |
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*/ |
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private void allocateElements(int numElements) { |
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int initialCapacity = MIN_INITIAL_CAPACITY; |
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// Find the best power of two to hold elements. |
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// Tests "<=" because arrays aren't kept full. |
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if (numElements >= initialCapacity) { |
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initialCapacity = numElements; |
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initialCapacity |= (initialCapacity >>> 1); |
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initialCapacity |= (initialCapacity >>> 2); |
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initialCapacity |= (initialCapacity >>> 4); |
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initialCapacity |= (initialCapacity >>> 8); |
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initialCapacity |= (initialCapacity >>> 16); |
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initialCapacity++; |
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* The maximum size of array to allocate. |
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* Some VMs reserve some header words in an array. |
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* Attempts to allocate larger arrays may result in |
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* OutOfMemoryError: Requested array size exceeds VM limit |
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*/ |
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private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
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|
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/** |
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* Increases the capacity of this deque by at least the given amount. |
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* |
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* @param needed the required minimum extra capacity; must be positive |
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*/ |
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private void grow(int needed) { |
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// overflow-conscious code |
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// checkInvariants(); |
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final int oldCapacity = elements.length; |
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int newCapacity; |
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// Double size if small; else grow by 50% |
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int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1); |
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if (jump < needed |
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|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0) |
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newCapacity = newCapacity(needed, jump); |
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elements = Arrays.copyOf(elements, newCapacity); |
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if (oldCapacity - head < size) { |
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// wrap around; slide first leg forward to end of array |
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int newSpace = newCapacity - oldCapacity; |
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System.arraycopy(elements, head, |
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elements, head + newSpace, |
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oldCapacity - head); |
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Arrays.fill(elements, head, head + newSpace, null); |
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head += newSpace; |
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} |
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// checkInvariants(); |
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} |
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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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/** Capacity calculation for edge conditions, especially overflow. */ |
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private int newCapacity(int needed, int jump) { |
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final int oldCapacity = elements.length, minCapacity; |
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if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) { |
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if (minCapacity < 0) |
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throw new IllegalStateException("Sorry, deque too big"); |
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return Integer.MAX_VALUE; |
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} |
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elements = (E[]) new Object[initialCapacity]; |
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if (needed > jump) |
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return minCapacity; |
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return (oldCapacity + jump - MAX_ARRAY_SIZE < 0) |
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? oldCapacity + jump |
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: MAX_ARRAY_SIZE; |
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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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* when head and tail have wrapped around to become equal. |
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* Increases the internal storage of this collection, if necessary, |
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* to ensure that it can hold at least the given number of elements. |
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* |
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* @param minCapacity the desired minimum capacity |
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* @since TBD |
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*/ |
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private void doubleCapacity() { |
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assert head == tail; |
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int p = head; |
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int n = elements.length; |
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int r = n - p; // number of elements to the right of p |
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int newCapacity = n << 1; |
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if (newCapacity < 0) |
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throw new IllegalStateException("Sorry, deque too big"); |
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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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head = 0; |
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tail = n; |
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/* public */ void ensureCapacity(int minCapacity) { |
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if (minCapacity > elements.length) |
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grow(minCapacity - elements.length); |
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// checkInvariants(); |
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} |
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|
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/** |
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* Copy 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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* Minimizes the internal storage of this collection. |
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* |
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* @return its argument |
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* @since TBD |
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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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/* public */ void trimToSize() { |
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if (size < elements.length) { |
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elements = toArray(); |
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head = 0; |
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} |
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return a; |
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// checkInvariants(); |
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} |
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|
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/** |
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* Constructs an empty array deque with the an initial capacity |
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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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/** |
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* Constructs an empty array deque with an initial capacity |
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* sufficient to hold the specified number of elements. |
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* |
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* @param numElements lower bound on initial capacity of the deque |
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* @param numElements lower bound on initial capacity of the deque |
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*/ |
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public ArrayDeque(int numElements) { |
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allocateElements(numElements); |
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elements = new Object[numElements]; |
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} |
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|
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/** |
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* @throws NullPointerException if the specified collection is null |
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*/ |
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public ArrayDeque(Collection<? extends E> c) { |
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allocateElements(c.size()); |
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addAll(c); |
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Object[] elements = c.toArray(); |
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// defend against c.toArray (incorrectly) not returning Object[] |
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// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652) |
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size = elements.length; |
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if (elements.getClass() != Object[].class) |
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elements = Arrays.copyOf(elements, size, Object[].class); |
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for (Object obj : elements) |
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Objects.requireNonNull(obj); |
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this.elements = elements; |
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} |
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|
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// The main insertion and extraction methods are addFirst, |
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// addLast, pollFirst, pollLast. The other methods are defined in |
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// terms of these. |
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/** |
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* Increments i, mod modulus. |
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* Precondition and postcondition: 0 <= i < modulus. |
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*/ |
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static final int inc(int i, int modulus) { |
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if (++i >= modulus) i = 0; |
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return i; |
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} |
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|
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/** |
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* Inserts the specified element to the front this deque. |
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* |
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* @param e the element to insert |
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* @throws NullPointerException if <tt>e</tt> is null |
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* Decrements i, mod modulus. |
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* Precondition and postcondition: 0 <= i < modulus. |
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*/ |
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public void addFirst(E e) { |
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static final int dec(int i, int modulus) { |
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if (--i < 0) i = modulus - 1; |
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return i; |
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} |
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|
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/** |
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* Adds i and j, mod modulus. |
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* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus. |
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*/ |
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static final int add(int i, int j, int modulus) { |
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if ((i += j) - modulus >= 0) i -= modulus; |
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return i; |
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} |
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|
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/** |
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* Returns the array index of the last element. |
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* May return invalid index -1 if there are no elements. |
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*/ |
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final int tail() { |
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return add(head, size - 1, elements.length); |
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} |
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|
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/** |
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* Returns element at array index i. |
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*/ |
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@SuppressWarnings("unchecked") |
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private E elementAt(int i) { |
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return (E) elements[i]; |
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} |
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|
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/** |
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* A version of elementAt that checks for null elements. |
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* This check doesn't catch all possible comodifications, |
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* but does catch ones that corrupt traversal. |
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*/ |
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E checkedElementAt(Object[] elements, int i) { |
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@SuppressWarnings("unchecked") E e = (E) elements[i]; |
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if (e == null) |
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throw new NullPointerException(); |
249 |
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elements[head = (head - 1) & (elements.length - 1)] = e; |
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if (head == tail) |
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doubleCapacity(); |
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throw new ConcurrentModificationException(); |
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return e; |
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} |
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|
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// The main insertion and extraction methods are addFirst, |
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// addLast, pollFirst, pollLast. The other methods are defined in |
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// terms of these. |
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|
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/** |
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* Inserts the specified element to the end this deque. |
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* This method is equivalent to {@link Collection#add} and |
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* {@link #push}. |
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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 insert |
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* @throws NullPointerException if <tt>e</tt> is null |
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* @param e the element to add |
260 |
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* @throws NullPointerException if the specified element is null |
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*/ |
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public void addLast(E e) { |
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if (e == null) |
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throw new NullPointerException(); |
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elements[tail] = e; |
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if ( (tail = (tail + 1) & (elements.length - 1)) == head) |
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doubleCapacity(); |
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public void addFirst(E e) { |
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// checkInvariants(); |
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Objects.requireNonNull(e); |
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Object[] elements; |
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int capacity, h; |
267 |
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final int s; |
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if ((s = size) == (capacity = (elements = this.elements).length)) { |
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grow(1); |
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capacity = (elements = this.elements).length; |
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} |
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if ((h = head - 1) < 0) h = capacity - 1; |
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elements[head = h] = e; |
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size = s + 1; |
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// checkInvariants(); |
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} |
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|
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/** |
279 |
< |
* Retrieves and removes the first element of this deque, or |
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* <tt>null</tt> if this deque is empty. |
279 |
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* Inserts the specified element at the end of this deque. |
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* |
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* @return the first element of this deque, or <tt>null</tt> if |
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* this deque is empty |
281 |
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* <p>This method is equivalent to {@link #add}. |
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* |
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* @param e the element to add |
284 |
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* @throws NullPointerException if the specified element is null |
285 |
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*/ |
286 |
< |
public E pollFirst() { |
287 |
< |
int h = head; |
288 |
< |
E result = elements[h]; // Element is null if deque empty |
289 |
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if (result == null) |
290 |
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return null; |
291 |
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elements[h] = null; // Must null out slot |
292 |
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head = (h + 1) & (elements.length - 1); |
293 |
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return result; |
286 |
> |
public void addLast(E e) { |
287 |
> |
// checkInvariants(); |
288 |
> |
Objects.requireNonNull(e); |
289 |
> |
Object[] elements; |
290 |
> |
int capacity; |
291 |
> |
final int s; |
292 |
> |
if ((s = size) == (capacity = (elements = this.elements).length)) { |
293 |
> |
grow(1); |
294 |
> |
capacity = (elements = this.elements).length; |
295 |
> |
} |
296 |
> |
elements[add(head, s, capacity)] = e; |
297 |
> |
size = s + 1; |
298 |
> |
// checkInvariants(); |
299 |
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} |
300 |
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|
301 |
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/** |
302 |
< |
* Retrieves and removes the last element of this deque, or |
303 |
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* <tt>null</tt> if this deque is empty. |
302 |
> |
* Adds all of the elements in the specified collection at the end |
303 |
> |
* of this deque, as if by calling {@link #addLast} on each one, |
304 |
> |
* in the order that they are returned by the collection's |
305 |
> |
* iterator. |
306 |
|
* |
307 |
< |
* @return the last element of this deque, or <tt>null</tt> if |
308 |
< |
* this deque is empty |
307 |
> |
* @param c the elements to be inserted into this deque |
308 |
> |
* @return {@code true} if this deque changed as a result of the call |
309 |
> |
* @throws NullPointerException if the specified collection or any |
310 |
> |
* of its elements are null |
311 |
|
*/ |
312 |
< |
public E pollLast() { |
313 |
< |
int t = (tail - 1) & (elements.length - 1); |
314 |
< |
E result = elements[t]; |
315 |
< |
if (result == null) |
316 |
< |
return null; |
317 |
< |
elements[t] = null; |
318 |
< |
tail = t; |
247 |
< |
return result; |
312 |
> |
public boolean addAll(Collection<? extends E> c) { |
313 |
> |
final int s = size, needed = c.size() - (elements.length - s); |
314 |
> |
if (needed > 0) |
315 |
> |
grow(needed); |
316 |
> |
c.forEach((e) -> addLast(e)); |
317 |
> |
// checkInvariants(); |
318 |
> |
return size > s; |
319 |
|
} |
320 |
|
|
321 |
|
/** |
322 |
< |
* Inserts the specified element to the front this deque. |
322 |
> |
* Inserts the specified element at the front of this deque. |
323 |
|
* |
324 |
< |
* @param e the element to insert |
325 |
< |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerFirst}) |
326 |
< |
* @throws NullPointerException if <tt>e</tt> is null |
324 |
> |
* @param e the element to add |
325 |
> |
* @return {@code true} (as specified by {@link Deque#offerFirst}) |
326 |
> |
* @throws NullPointerException if the specified element is null |
327 |
|
*/ |
328 |
|
public boolean offerFirst(E e) { |
329 |
|
addFirst(e); |
331 |
|
} |
332 |
|
|
333 |
|
/** |
334 |
< |
* Inserts the specified element to the end this deque. |
334 |
> |
* Inserts the specified element at the end of this deque. |
335 |
|
* |
336 |
< |
* @param e the element to insert |
337 |
< |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerLast}) |
338 |
< |
* @throws NullPointerException if <tt>e</tt> is null |
336 |
> |
* @param e the element to add |
337 |
> |
* @return {@code true} (as specified by {@link Deque#offerLast}) |
338 |
> |
* @throws NullPointerException if the specified element is null |
339 |
|
*/ |
340 |
|
public boolean offerLast(E e) { |
341 |
|
addLast(e); |
343 |
|
} |
344 |
|
|
345 |
|
/** |
346 |
< |
* Retrieves and removes the first element of this deque. This method |
276 |
< |
* differs from the <tt>pollFirst</tt> method in that it throws an |
277 |
< |
* exception if this deque is empty. |
278 |
< |
* |
279 |
< |
* @return the first element of this deque |
280 |
< |
* @throws NoSuchElementException if this deque is empty |
346 |
> |
* @throws NoSuchElementException {@inheritDoc} |
347 |
|
*/ |
348 |
|
public E removeFirst() { |
349 |
< |
E x = pollFirst(); |
350 |
< |
if (x == null) |
349 |
> |
// checkInvariants(); |
350 |
> |
E e = pollFirst(); |
351 |
> |
if (e == null) |
352 |
|
throw new NoSuchElementException(); |
353 |
< |
return x; |
353 |
> |
return e; |
354 |
|
} |
355 |
|
|
356 |
|
/** |
357 |
< |
* Retrieves and removes the last element of this deque. This method |
291 |
< |
* differs from the <tt>pollLast</tt> method in that it throws an |
292 |
< |
* exception if this deque is empty. |
293 |
< |
* |
294 |
< |
* @return the last element of this deque |
295 |
< |
* @throws NoSuchElementException if this deque is empty |
357 |
> |
* @throws NoSuchElementException {@inheritDoc} |
358 |
|
*/ |
359 |
|
public E removeLast() { |
360 |
< |
E x = pollLast(); |
361 |
< |
if (x == null) |
360 |
> |
// checkInvariants(); |
361 |
> |
E e = pollLast(); |
362 |
> |
if (e == null) |
363 |
|
throw new NoSuchElementException(); |
364 |
< |
return x; |
364 |
> |
return e; |
365 |
|
} |
366 |
|
|
367 |
< |
/** |
368 |
< |
* Retrieves, but does not remove, the first element of this deque, |
369 |
< |
* returning <tt>null</tt> if this deque is empty. |
370 |
< |
* |
371 |
< |
* @return the first element of this deque, or <tt>null</tt> if |
372 |
< |
* this deque is empty |
373 |
< |
*/ |
374 |
< |
public E peekFirst() { |
375 |
< |
return elements[head]; // elements[head] is null if deque empty |
367 |
> |
public E pollFirst() { |
368 |
> |
// checkInvariants(); |
369 |
> |
int s, h; |
370 |
> |
if ((s = size) <= 0) |
371 |
> |
return null; |
372 |
> |
final Object[] elements = this.elements; |
373 |
> |
@SuppressWarnings("unchecked") E e = (E) elements[h = head]; |
374 |
> |
elements[h] = null; |
375 |
> |
if (++h >= elements.length) h = 0; |
376 |
> |
head = h; |
377 |
> |
size = s - 1; |
378 |
> |
return e; |
379 |
|
} |
380 |
|
|
381 |
< |
/** |
382 |
< |
* Retrieves, but does not remove, the last element of this deque, |
383 |
< |
* returning <tt>null</tt> if this deque is empty. |
384 |
< |
* |
385 |
< |
* @return the last element of this deque, or <tt>null</tt> if this deque |
386 |
< |
* is empty |
387 |
< |
*/ |
388 |
< |
public E peekLast() { |
389 |
< |
return elements[(tail - 1) & (elements.length - 1)]; |
381 |
> |
public E pollLast() { |
382 |
> |
// checkInvariants(); |
383 |
> |
final int s, tail; |
384 |
> |
if ((s = size) <= 0) |
385 |
> |
return null; |
386 |
> |
final Object[] elements = this.elements; |
387 |
> |
@SuppressWarnings("unchecked") |
388 |
> |
E e = (E) elements[tail = add(head, s - 1, elements.length)]; |
389 |
> |
elements[tail] = null; |
390 |
> |
size = s - 1; |
391 |
> |
return e; |
392 |
|
} |
393 |
|
|
394 |
|
/** |
395 |
< |
* Retrieves, but does not remove, the first element of this |
328 |
< |
* deque. This method differs from the <tt>peek</tt> method only |
329 |
< |
* in that it throws an exception if this deque is empty. |
330 |
< |
* |
331 |
< |
* @return the first element of this deque |
332 |
< |
* @throws NoSuchElementException if this deque is empty |
395 |
> |
* @throws NoSuchElementException {@inheritDoc} |
396 |
|
*/ |
397 |
|
public E getFirst() { |
398 |
< |
E x = elements[head]; |
399 |
< |
if (x == null) |
400 |
< |
throw new NoSuchElementException(); |
338 |
< |
return x; |
398 |
> |
// checkInvariants(); |
399 |
> |
if (size <= 0) throw new NoSuchElementException(); |
400 |
> |
return elementAt(head); |
401 |
|
} |
402 |
|
|
403 |
|
/** |
404 |
< |
* Retrieves, but does not remove, the last element of this |
343 |
< |
* deque. This method differs from the <tt>peek</tt> method only |
344 |
< |
* in that it throws an exception if this deque is empty. |
345 |
< |
* |
346 |
< |
* @return the last element of this deque |
347 |
< |
* @throws NoSuchElementException if this deque is empty |
404 |
> |
* @throws NoSuchElementException {@inheritDoc} |
405 |
|
*/ |
406 |
+ |
@SuppressWarnings("unchecked") |
407 |
|
public E getLast() { |
408 |
< |
E x = elements[(tail - 1) & (elements.length - 1)]; |
409 |
< |
if (x == null) |
410 |
< |
throw new NoSuchElementException(); |
411 |
< |
return x; |
408 |
> |
// checkInvariants(); |
409 |
> |
final int s; |
410 |
> |
if ((s = size) <= 0) throw new NoSuchElementException(); |
411 |
> |
final Object[] elements = this.elements; |
412 |
> |
return (E) elements[add(head, s - 1, elements.length)]; |
413 |
> |
} |
414 |
> |
|
415 |
> |
public E peekFirst() { |
416 |
> |
// checkInvariants(); |
417 |
> |
return (size <= 0) ? null : elementAt(head); |
418 |
> |
} |
419 |
> |
|
420 |
> |
@SuppressWarnings("unchecked") |
421 |
> |
public E peekLast() { |
422 |
> |
// checkInvariants(); |
423 |
> |
final int s; |
424 |
> |
if ((s = size) <= 0) return null; |
425 |
> |
final Object[] elements = this.elements; |
426 |
> |
return (E) elements[add(head, s - 1, elements.length)]; |
427 |
|
} |
428 |
|
|
429 |
|
/** |
430 |
|
* Removes the first occurrence of the specified element in this |
431 |
< |
* deque (when traversing the deque from head to tail). If the deque |
432 |
< |
* does not contain the element, it is unchanged. |
433 |
< |
* |
434 |
< |
* @param e element to be removed from this deque, if present |
435 |
< |
* @return <tt>true</tt> if the deque contained the specified element |
436 |
< |
*/ |
437 |
< |
public boolean removeFirstOccurrence(Object e) { |
438 |
< |
if (e == null) |
439 |
< |
return false; |
440 |
< |
int mask = elements.length - 1; |
441 |
< |
int i = head; |
442 |
< |
E x; |
443 |
< |
while ( (x = elements[i]) != null) { |
444 |
< |
if (e.equals(x)) { |
445 |
< |
delete(i); |
446 |
< |
return true; |
431 |
> |
* deque (when traversing the deque from head to tail). |
432 |
> |
* If the deque does not contain the element, it is unchanged. |
433 |
> |
* More formally, removes the first element {@code e} such that |
434 |
> |
* {@code o.equals(e)} (if such an element exists). |
435 |
> |
* Returns {@code true} if this deque contained the specified element |
436 |
> |
* (or equivalently, if this deque changed as a result of the call). |
437 |
> |
* |
438 |
> |
* @param o element to be removed from this deque, if present |
439 |
> |
* @return {@code true} if the deque contained the specified element |
440 |
> |
*/ |
441 |
> |
public boolean removeFirstOccurrence(Object o) { |
442 |
> |
if (o != null) { |
443 |
> |
final Object[] elements = this.elements; |
444 |
> |
final int capacity = elements.length; |
445 |
> |
int from, end, to, todo; |
446 |
> |
todo = (end = (from = head) + size) |
447 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
448 |
> |
for (;; from = 0, to = todo, todo = 0) { |
449 |
> |
for (int i = from; i < to; i++) |
450 |
> |
if (o.equals(elements[i])) { |
451 |
> |
delete(i); |
452 |
> |
return true; |
453 |
> |
} |
454 |
> |
if (todo == 0) break; |
455 |
|
} |
375 |
– |
i = (i + 1) & mask; |
456 |
|
} |
457 |
|
return false; |
458 |
|
} |
459 |
|
|
460 |
|
/** |
461 |
|
* Removes the last occurrence of the specified element in this |
462 |
< |
* deque (when traversing the deque from head to tail). If the deque |
463 |
< |
* does not contain the element, it is unchanged. |
464 |
< |
* |
465 |
< |
* @param e element to be removed from this deque, if present |
466 |
< |
* @return <tt>true</tt> if the deque contained the specified element |
467 |
< |
*/ |
468 |
< |
public boolean removeLastOccurrence(Object e) { |
469 |
< |
if (e == null) |
470 |
< |
return false; |
471 |
< |
int mask = elements.length - 1; |
472 |
< |
int i = (tail - 1) & mask; |
473 |
< |
E x; |
474 |
< |
while ( (x = elements[i]) != null) { |
475 |
< |
if (e.equals(x)) { |
476 |
< |
delete(i); |
477 |
< |
return true; |
462 |
> |
* deque (when traversing the deque from head to tail). |
463 |
> |
* If the deque does not contain the element, it is unchanged. |
464 |
> |
* More formally, removes the last element {@code e} such that |
465 |
> |
* {@code o.equals(e)} (if such an element exists). |
466 |
> |
* Returns {@code true} if this deque contained the specified element |
467 |
> |
* (or equivalently, if this deque changed as a result of the call). |
468 |
> |
* |
469 |
> |
* @param o element to be removed from this deque, if present |
470 |
> |
* @return {@code true} if the deque contained the specified element |
471 |
> |
*/ |
472 |
> |
public boolean removeLastOccurrence(Object o) { |
473 |
> |
if (o != null) { |
474 |
> |
final Object[] elements = this.elements; |
475 |
> |
final int capacity = elements.length; |
476 |
> |
int from, to, end, todo; |
477 |
> |
todo = (to = ((end = (from = tail()) - size) >= -1) ? end : -1) - end; |
478 |
> |
for (;; from = capacity - 1, to = capacity - 1 - todo, todo = 0) { |
479 |
> |
for (int i = from; i > to; i--) |
480 |
> |
if (o.equals(elements[i])) { |
481 |
> |
delete(i); |
482 |
> |
return true; |
483 |
> |
} |
484 |
> |
if (todo == 0) break; |
485 |
|
} |
399 |
– |
i = (i - 1) & mask; |
486 |
|
} |
487 |
|
return false; |
488 |
|
} |
490 |
|
// *** Queue methods *** |
491 |
|
|
492 |
|
/** |
493 |
< |
* Inserts the specified element to the end of this deque. |
408 |
< |
* |
409 |
< |
* <p>This method is equivalent to {@link #offerLast}. |
410 |
< |
* |
411 |
< |
* @param e the element to insert |
412 |
< |
* @return <tt>true</tt> (as per the spec for {@link Queue#offer}) |
413 |
< |
* @throws NullPointerException if <tt>e</tt> is null |
414 |
< |
*/ |
415 |
< |
public boolean offer(E e) { |
416 |
< |
return offerLast(e); |
417 |
< |
} |
418 |
< |
|
419 |
< |
/** |
420 |
< |
* Inserts the specified element to the end of this deque. |
493 |
> |
* Inserts the specified element at the end of this deque. |
494 |
|
* |
495 |
|
* <p>This method is equivalent to {@link #addLast}. |
496 |
|
* |
497 |
< |
* @param e the element to insert |
498 |
< |
* @return <tt>true</tt> (as per the spec for {@link Collection#add}) |
499 |
< |
* @throws NullPointerException if <tt>e</tt> is null |
497 |
> |
* @param e the element to add |
498 |
> |
* @return {@code true} (as specified by {@link Collection#add}) |
499 |
> |
* @throws NullPointerException if the specified element is null |
500 |
|
*/ |
501 |
|
public boolean add(E e) { |
502 |
|
addLast(e); |
504 |
|
} |
505 |
|
|
506 |
|
/** |
507 |
< |
* Retrieves and removes the head of the queue represented by |
435 |
< |
* this deque, or <tt>null</tt> if this deque is empty. In other words, |
436 |
< |
* retrieves and removes the first element of this deque, or <tt>null</tt> |
437 |
< |
* if this deque is empty. |
507 |
> |
* Inserts the specified element at the end of this deque. |
508 |
|
* |
509 |
< |
* <p>This method is equivalent to {@link #pollFirst}. |
509 |
> |
* <p>This method is equivalent to {@link #offerLast}. |
510 |
|
* |
511 |
< |
* @return the first element of this deque, or <tt>null</tt> if |
512 |
< |
* this deque is empty |
511 |
> |
* @param e the element to add |
512 |
> |
* @return {@code true} (as specified by {@link Queue#offer}) |
513 |
> |
* @throws NullPointerException if the specified element is null |
514 |
|
*/ |
515 |
< |
public E poll() { |
516 |
< |
return pollFirst(); |
515 |
> |
public boolean offer(E e) { |
516 |
> |
return offerLast(e); |
517 |
|
} |
518 |
|
|
519 |
|
/** |
520 |
|
* Retrieves and removes the head of the queue represented by this deque. |
521 |
< |
* This method differs from the <tt>poll</tt> method in that it throws an |
521 |
> |
* |
522 |
> |
* This method differs from {@link #poll poll} only in that it throws an |
523 |
|
* exception if this deque is empty. |
524 |
|
* |
525 |
|
* <p>This method is equivalent to {@link #removeFirst}. |
526 |
|
* |
527 |
|
* @return the head of the queue represented by this deque |
528 |
< |
* @throws NoSuchElementException if this deque is empty |
528 |
> |
* @throws NoSuchElementException {@inheritDoc} |
529 |
|
*/ |
530 |
|
public E remove() { |
531 |
|
return removeFirst(); |
532 |
|
} |
533 |
|
|
534 |
|
/** |
535 |
< |
* Retrieves, but does not remove, the head of the queue represented by |
536 |
< |
* this deque, returning <tt>null</tt> if this deque is empty. |
535 |
> |
* Retrieves and removes the head of the queue represented by this deque |
536 |
> |
* (in other words, the first element of this deque), or returns |
537 |
> |
* {@code null} if this deque is empty. |
538 |
|
* |
539 |
< |
* <p>This method is equivalent to {@link #peekFirst} |
539 |
> |
* <p>This method is equivalent to {@link #pollFirst}. |
540 |
|
* |
541 |
|
* @return the head of the queue represented by this deque, or |
542 |
< |
* <tt>null</tt> if this deque is empty |
542 |
> |
* {@code null} if this deque is empty |
543 |
|
*/ |
544 |
< |
public E peek() { |
545 |
< |
return peekFirst(); |
544 |
> |
public E poll() { |
545 |
> |
return pollFirst(); |
546 |
|
} |
547 |
|
|
548 |
|
/** |
549 |
|
* Retrieves, but does not remove, the head of the queue represented by |
550 |
< |
* this deque. This method differs from the <tt>peek</tt> method only in |
550 |
> |
* this deque. This method differs from {@link #peek peek} only in |
551 |
|
* that it throws an exception if this deque is empty. |
552 |
|
* |
553 |
< |
* <p>This method is equivalent to {@link #getFirst} |
553 |
> |
* <p>This method is equivalent to {@link #getFirst}. |
554 |
|
* |
555 |
|
* @return the head of the queue represented by this deque |
556 |
< |
* @throws NoSuchElementException if this deque is empty |
556 |
> |
* @throws NoSuchElementException {@inheritDoc} |
557 |
|
*/ |
558 |
|
public E element() { |
559 |
|
return getFirst(); |
560 |
|
} |
561 |
|
|
562 |
+ |
/** |
563 |
+ |
* Retrieves, but does not remove, the head of the queue represented by |
564 |
+ |
* this deque, or returns {@code null} if this deque is empty. |
565 |
+ |
* |
566 |
+ |
* <p>This method is equivalent to {@link #peekFirst}. |
567 |
+ |
* |
568 |
+ |
* @return the head of the queue represented by this deque, or |
569 |
+ |
* {@code null} if this deque is empty |
570 |
+ |
*/ |
571 |
+ |
public E peek() { |
572 |
+ |
return peekFirst(); |
573 |
+ |
} |
574 |
+ |
|
575 |
|
// *** Stack methods *** |
576 |
|
|
577 |
|
/** |
578 |
|
* Pushes an element onto the stack represented by this deque. In other |
579 |
< |
* words, inserts the element to the front this deque. |
579 |
> |
* words, inserts the element at the front of this deque. |
580 |
|
* |
581 |
|
* <p>This method is equivalent to {@link #addFirst}. |
582 |
|
* |
583 |
|
* @param e the element to push |
584 |
< |
* @throws NullPointerException if <tt>e</tt> is null |
584 |
> |
* @throws NullPointerException if the specified element is null |
585 |
|
*/ |
586 |
|
public void push(E e) { |
587 |
|
addFirst(e); |
594 |
|
* <p>This method is equivalent to {@link #removeFirst()}. |
595 |
|
* |
596 |
|
* @return the element at the front of this deque (which is the top |
597 |
< |
* of the stack represented by this deque) |
598 |
< |
* @throws NoSuchElementException if this deque is empty |
597 |
> |
* of the stack represented by this deque) |
598 |
> |
* @throws NoSuchElementException {@inheritDoc} |
599 |
|
*/ |
600 |
|
public E pop() { |
601 |
|
return removeFirst(); |
602 |
|
} |
603 |
|
|
604 |
|
/** |
605 |
< |
* Remove the element at the specified position in the elements array, |
606 |
< |
* adjusting head, tail, and size as necessary. This can result in |
607 |
< |
* motion of elements backwards or forwards in the array. |
608 |
< |
* |
609 |
< |
* <p>This method is called delete rather than remove to emphasize |
610 |
< |
* that its semantics differ from those of List.remove(int). |
611 |
< |
* |
605 |
> |
* Removes the element at the specified position in the elements array. |
606 |
> |
* This can result in forward or backwards motion of array elements. |
607 |
> |
* We optimize for least element motion. |
608 |
> |
* |
609 |
> |
* <p>This method is called delete rather than remove to emphasize |
610 |
> |
* that its semantics differ from those of {@link List#remove(int)}. |
611 |
> |
* |
612 |
|
* @return true if elements moved backwards |
613 |
|
*/ |
614 |
< |
private boolean delete(int i) { |
615 |
< |
// Case 1: Deque doesn't wrap |
616 |
< |
// Case 2: Deque does wrap and removed element is in the head portion |
617 |
< |
if ((head < tail || tail == 0) || i >= head) { |
618 |
< |
System.arraycopy(elements, head, elements, head + 1, i - head); |
619 |
< |
elements[head] = null; |
620 |
< |
head = (head + 1) & (elements.length - 1); |
614 |
> |
boolean delete(int i) { |
615 |
> |
// checkInvariants(); |
616 |
> |
final Object[] elements = this.elements; |
617 |
> |
final int capacity = elements.length; |
618 |
> |
final int h = head; |
619 |
> |
int front; // number of elements before to-be-deleted elt |
620 |
> |
if ((front = i - h) < 0) front += capacity; |
621 |
> |
final int back = size - front - 1; // number of elements after |
622 |
> |
if (front < back) { |
623 |
> |
// move front elements forwards |
624 |
> |
if (h <= i) { |
625 |
> |
System.arraycopy(elements, h, elements, h + 1, front); |
626 |
> |
} else { // Wrap around |
627 |
> |
System.arraycopy(elements, 0, elements, 1, i); |
628 |
> |
elements[0] = elements[capacity - 1]; |
629 |
> |
System.arraycopy(elements, h, elements, h + 1, front - (i + 1)); |
630 |
> |
} |
631 |
> |
elements[h] = null; |
632 |
> |
if ((head = (h + 1)) >= capacity) head = 0; |
633 |
> |
size--; |
634 |
> |
// checkInvariants(); |
635 |
|
return false; |
636 |
+ |
} else { |
637 |
+ |
// move back elements backwards |
638 |
+ |
int tail = tail(); |
639 |
+ |
if (i <= tail) { |
640 |
+ |
System.arraycopy(elements, i + 1, elements, i, back); |
641 |
+ |
} else { // Wrap around |
642 |
+ |
int firstLeg = capacity - (i + 1); |
643 |
+ |
System.arraycopy(elements, i + 1, elements, i, firstLeg); |
644 |
+ |
elements[capacity - 1] = elements[0]; |
645 |
+ |
System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1); |
646 |
+ |
} |
647 |
+ |
elements[tail] = null; |
648 |
+ |
size--; |
649 |
+ |
// checkInvariants(); |
650 |
+ |
return true; |
651 |
|
} |
537 |
– |
|
538 |
– |
// Case 3: Deque wraps and removed element is in the tail portion |
539 |
– |
tail--; |
540 |
– |
System.arraycopy(elements, i + 1, elements, i, tail - i); |
541 |
– |
elements[tail] = null; |
542 |
– |
return true; |
652 |
|
} |
653 |
|
|
654 |
|
// *** Collection Methods *** |
659 |
|
* @return the number of elements in this deque |
660 |
|
*/ |
661 |
|
public int size() { |
662 |
< |
return (tail - head) & (elements.length - 1); |
662 |
> |
return size; |
663 |
|
} |
664 |
|
|
665 |
|
/** |
666 |
< |
* Returns <tt>true</tt> if this collection contains no elements.<p> |
666 |
> |
* Returns {@code true} if this deque contains no elements. |
667 |
|
* |
668 |
< |
* @return <tt>true</tt> if this collection contains no elements. |
668 |
> |
* @return {@code true} if this deque contains no elements |
669 |
|
*/ |
670 |
|
public boolean isEmpty() { |
671 |
< |
return head == tail; |
671 |
> |
return size == 0; |
672 |
|
} |
673 |
|
|
674 |
|
/** |
676 |
|
* will be ordered from first (head) to last (tail). This is the same |
677 |
|
* order that elements would be dequeued (via successive calls to |
678 |
|
* {@link #remove} or popped (via successive calls to {@link #pop}). |
679 |
< |
* |
680 |
< |
* @return an <tt>Iterator</tt> over the elements in this deque |
679 |
> |
* |
680 |
> |
* @return an iterator over the elements in this deque |
681 |
|
*/ |
682 |
|
public Iterator<E> iterator() { |
683 |
|
return new DeqIterator(); |
684 |
|
} |
685 |
|
|
686 |
+ |
public Iterator<E> descendingIterator() { |
687 |
+ |
return new DescendingIterator(); |
688 |
+ |
} |
689 |
+ |
|
690 |
|
private class DeqIterator implements Iterator<E> { |
691 |
< |
/** |
692 |
< |
* Index of element to be returned by subsequent call to next. |
580 |
< |
*/ |
581 |
< |
private int cursor = head; |
691 |
> |
/** Index of element to be returned by subsequent call to next. */ |
692 |
> |
int cursor; |
693 |
|
|
694 |
< |
/** |
695 |
< |
* Tail recorded at construction (also in remove), to stop |
585 |
< |
* iterator and also to check for comodification. |
586 |
< |
*/ |
587 |
< |
private int fence = tail; |
694 |
> |
/** Number of elements yet to be returned. */ |
695 |
> |
int remaining = size; |
696 |
|
|
697 |
|
/** |
698 |
|
* Index of element returned by most recent call to next. |
699 |
|
* Reset to -1 if element is deleted by a call to remove. |
700 |
|
*/ |
701 |
< |
private int lastRet = -1; |
701 |
> |
int lastRet = -1; |
702 |
> |
|
703 |
> |
DeqIterator() { cursor = head; } |
704 |
|
|
705 |
< |
public boolean hasNext() { |
706 |
< |
return cursor != fence; |
705 |
> |
public final boolean hasNext() { |
706 |
> |
return remaining > 0; |
707 |
|
} |
708 |
|
|
709 |
|
public E next() { |
710 |
< |
E result; |
601 |
< |
if (cursor == fence) |
710 |
> |
if (remaining <= 0) |
711 |
|
throw new NoSuchElementException(); |
712 |
< |
// This check doesn't catch all possible comodifications, |
713 |
< |
// but does catch the ones that corrupt traversal |
605 |
< |
if (tail != fence || (result = elements[cursor]) == null) |
606 |
< |
throw new ConcurrentModificationException(); |
712 |
> |
final Object[] elements = ArrayDeque.this.elements; |
713 |
> |
E e = checkedElementAt(elements, cursor); |
714 |
|
lastRet = cursor; |
715 |
< |
cursor = (cursor + 1) & (elements.length - 1); |
716 |
< |
return result; |
715 |
> |
if (++cursor >= elements.length) cursor = 0; |
716 |
> |
remaining--; |
717 |
> |
return e; |
718 |
> |
} |
719 |
> |
|
720 |
> |
void postDelete(boolean leftShifted) { |
721 |
> |
if (leftShifted) |
722 |
> |
if (--cursor < 0) cursor = elements.length - 1; |
723 |
|
} |
724 |
|
|
725 |
< |
public void remove() { |
725 |
> |
public final void remove() { |
726 |
|
if (lastRet < 0) |
727 |
|
throw new IllegalStateException(); |
728 |
< |
if (delete(lastRet)) |
616 |
< |
cursor--; |
728 |
> |
postDelete(delete(lastRet)); |
729 |
|
lastRet = -1; |
730 |
< |
fence = tail; |
730 |
> |
} |
731 |
> |
|
732 |
> |
public void forEachRemaining(Consumer<? super E> action) { |
733 |
> |
final int k; |
734 |
> |
if ((k = remaining) > 0) { |
735 |
> |
remaining = 0; |
736 |
> |
ArrayDeque.forEachRemaining(action, elements, cursor, k); |
737 |
> |
if ((lastRet = cursor + k - 1) >= elements.length) |
738 |
> |
lastRet -= elements.length; |
739 |
> |
} |
740 |
> |
} |
741 |
> |
} |
742 |
> |
|
743 |
> |
private class DescendingIterator extends DeqIterator { |
744 |
> |
DescendingIterator() { cursor = tail(); } |
745 |
> |
|
746 |
> |
public final E next() { |
747 |
> |
if (remaining <= 0) |
748 |
> |
throw new NoSuchElementException(); |
749 |
> |
final Object[] elements = ArrayDeque.this.elements; |
750 |
> |
E e = checkedElementAt(elements, cursor); |
751 |
> |
lastRet = cursor; |
752 |
> |
if (--cursor < 0) cursor = elements.length - 1; |
753 |
> |
remaining--; |
754 |
> |
return e; |
755 |
> |
} |
756 |
> |
|
757 |
> |
void postDelete(boolean leftShifted) { |
758 |
> |
if (!leftShifted) |
759 |
> |
if (++cursor >= elements.length) cursor = 0; |
760 |
> |
} |
761 |
> |
|
762 |
> |
public final void forEachRemaining(Consumer<? super E> action) { |
763 |
> |
final int k; |
764 |
> |
if ((k = remaining) > 0) { |
765 |
> |
remaining = 0; |
766 |
> |
forEachRemainingDescending(action, elements, cursor, k); |
767 |
> |
if ((lastRet = cursor - (k - 1)) < 0) |
768 |
> |
lastRet += elements.length; |
769 |
> |
} |
770 |
|
} |
771 |
|
} |
772 |
|
|
773 |
|
/** |
774 |
< |
* Returns <tt>true</tt> if this deque contains the specified |
775 |
< |
* element. More formally, returns <tt>true</tt> if and only if this |
776 |
< |
* deque contains at least one element <tt>e</tt> such that |
777 |
< |
* <tt>e.equals(o)</tt>. |
774 |
> |
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> |
775 |
> |
* and <em>fail-fast</em> {@link Spliterator} over the elements in this |
776 |
> |
* deque. |
777 |
> |
* |
778 |
> |
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, |
779 |
> |
* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and |
780 |
> |
* {@link Spliterator#NONNULL}. Overriding implementations should document |
781 |
> |
* the reporting of additional characteristic values. |
782 |
> |
* |
783 |
> |
* @return a {@code Spliterator} over the elements in this deque |
784 |
> |
* @since 1.8 |
785 |
> |
*/ |
786 |
> |
public Spliterator<E> spliterator() { |
787 |
> |
return new ArrayDequeSpliterator(); |
788 |
> |
} |
789 |
> |
|
790 |
> |
final class ArrayDequeSpliterator implements Spliterator<E> { |
791 |
> |
private int cursor; |
792 |
> |
private int remaining; // -1 until late-binding first use |
793 |
> |
|
794 |
> |
/** Constructs late-binding spliterator over all elements. */ |
795 |
> |
ArrayDequeSpliterator() { |
796 |
> |
this.remaining = -1; |
797 |
> |
} |
798 |
> |
|
799 |
> |
/** Constructs spliterator over the given slice. */ |
800 |
> |
ArrayDequeSpliterator(int cursor, int count) { |
801 |
> |
this.cursor = cursor; |
802 |
> |
this.remaining = count; |
803 |
> |
} |
804 |
> |
|
805 |
> |
/** Ensures late-binding initialization; then returns remaining. */ |
806 |
> |
private int remaining() { |
807 |
> |
if (remaining < 0) { |
808 |
> |
cursor = head; |
809 |
> |
remaining = size; |
810 |
> |
} |
811 |
> |
return remaining; |
812 |
> |
} |
813 |
> |
|
814 |
> |
public ArrayDequeSpliterator trySplit() { |
815 |
> |
final int mid; |
816 |
> |
if ((mid = remaining() >> 1) > 0) { |
817 |
> |
int oldCursor = cursor; |
818 |
> |
cursor = add(cursor, mid, elements.length); |
819 |
> |
remaining -= mid; |
820 |
> |
return new ArrayDequeSpliterator(oldCursor, mid); |
821 |
> |
} |
822 |
> |
return null; |
823 |
> |
} |
824 |
> |
|
825 |
> |
public void forEachRemaining(Consumer<? super E> action) { |
826 |
> |
final int k = remaining(); // side effect! |
827 |
> |
remaining = 0; |
828 |
> |
ArrayDeque.forEachRemaining(action, elements, cursor, k); |
829 |
> |
} |
830 |
> |
|
831 |
> |
public boolean tryAdvance(Consumer<? super E> action) { |
832 |
> |
Objects.requireNonNull(action); |
833 |
> |
final int k; |
834 |
> |
if ((k = remaining()) <= 0) |
835 |
> |
return false; |
836 |
> |
action.accept(checkedElementAt(elements, cursor)); |
837 |
> |
if (++cursor >= elements.length) cursor = 0; |
838 |
> |
remaining = k - 1; |
839 |
> |
return true; |
840 |
> |
} |
841 |
> |
|
842 |
> |
public long estimateSize() { |
843 |
> |
return remaining(); |
844 |
> |
} |
845 |
> |
|
846 |
> |
public int characteristics() { |
847 |
> |
return Spliterator.NONNULL |
848 |
> |
| Spliterator.ORDERED |
849 |
> |
| Spliterator.SIZED |
850 |
> |
| Spliterator.SUBSIZED; |
851 |
> |
} |
852 |
> |
} |
853 |
> |
|
854 |
> |
@SuppressWarnings("unchecked") |
855 |
> |
public void forEach(Consumer<? super E> action) { |
856 |
> |
Objects.requireNonNull(action); |
857 |
> |
final Object[] elements = this.elements; |
858 |
> |
final int capacity = elements.length; |
859 |
> |
int from, end, to, todo; |
860 |
> |
todo = (end = (from = head) + size) |
861 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
862 |
> |
for (;; from = 0, to = todo, todo = 0) { |
863 |
> |
for (int i = from; i < to; i++) |
864 |
> |
action.accept((E) elements[i]); |
865 |
> |
if (todo == 0) break; |
866 |
> |
} |
867 |
> |
// checkInvariants(); |
868 |
> |
} |
869 |
> |
|
870 |
> |
/** |
871 |
> |
* A variant of forEach that also checks for concurrent |
872 |
> |
* modification, for use in iterators. |
873 |
> |
*/ |
874 |
> |
static <E> void forEachRemaining( |
875 |
> |
Consumer<? super E> action, Object[] elements, int from, int remaining) { |
876 |
> |
Objects.requireNonNull(action); |
877 |
> |
final int capacity = elements.length; |
878 |
> |
int end, to, todo; |
879 |
> |
todo = (end = from + remaining) |
880 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
881 |
> |
for (;; from = 0, to = todo, todo = 0) { |
882 |
> |
for (int i = from; i < to; i++) { |
883 |
> |
@SuppressWarnings("unchecked") E e = (E) elements[i]; |
884 |
> |
if (e == null) |
885 |
> |
throw new ConcurrentModificationException(); |
886 |
> |
action.accept(e); |
887 |
> |
} |
888 |
> |
if (todo == 0) break; |
889 |
> |
} |
890 |
> |
} |
891 |
> |
|
892 |
> |
static <E> void forEachRemainingDescending( |
893 |
> |
Consumer<? super E> action, Object[] elements, int from, int remaining) { |
894 |
> |
Objects.requireNonNull(action); |
895 |
> |
final int capacity = elements.length; |
896 |
> |
int end, to, todo; |
897 |
> |
todo = (to = ((end = from - remaining) >= -1) ? end : -1) - end; |
898 |
> |
for (;; from = capacity - 1, to = capacity - 1 - todo, todo = 0) { |
899 |
> |
for (int i = from; i > to; i--) { |
900 |
> |
@SuppressWarnings("unchecked") E e = (E) elements[i]; |
901 |
> |
if (e == null) |
902 |
> |
throw new ConcurrentModificationException(); |
903 |
> |
action.accept(e); |
904 |
> |
} |
905 |
> |
if (todo == 0) break; |
906 |
> |
} |
907 |
> |
} |
908 |
> |
|
909 |
> |
/** |
910 |
> |
* Replaces each element of this deque with the result of applying the |
911 |
> |
* operator to that element, as specified by {@link List#replaceAll}. |
912 |
> |
* |
913 |
> |
* @param operator the operator to apply to each element |
914 |
> |
* @since TBD |
915 |
> |
*/ |
916 |
> |
/* public */ void replaceAll(UnaryOperator<E> operator) { |
917 |
> |
Objects.requireNonNull(operator); |
918 |
> |
final Object[] elements = this.elements; |
919 |
> |
final int capacity = elements.length; |
920 |
> |
int from, end, to, todo; |
921 |
> |
todo = (end = (from = head) + size) |
922 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
923 |
> |
for (;; from = 0, to = todo, todo = 0) { |
924 |
> |
for (int i = from; i < to; i++) |
925 |
> |
elements[i] = operator.apply(elementAt(i)); |
926 |
> |
if (todo == 0) break; |
927 |
> |
} |
928 |
> |
// checkInvariants(); |
929 |
> |
} |
930 |
> |
|
931 |
> |
/** |
932 |
> |
* @throws NullPointerException {@inheritDoc} |
933 |
> |
*/ |
934 |
> |
public boolean removeIf(Predicate<? super E> filter) { |
935 |
> |
Objects.requireNonNull(filter); |
936 |
> |
return bulkRemove(filter); |
937 |
> |
} |
938 |
> |
|
939 |
> |
/** |
940 |
> |
* @throws NullPointerException {@inheritDoc} |
941 |
> |
*/ |
942 |
> |
public boolean removeAll(Collection<?> c) { |
943 |
> |
Objects.requireNonNull(c); |
944 |
> |
return bulkRemove(e -> c.contains(e)); |
945 |
> |
} |
946 |
> |
|
947 |
> |
/** |
948 |
> |
* @throws NullPointerException {@inheritDoc} |
949 |
> |
*/ |
950 |
> |
public boolean retainAll(Collection<?> c) { |
951 |
> |
Objects.requireNonNull(c); |
952 |
> |
return bulkRemove(e -> !c.contains(e)); |
953 |
> |
} |
954 |
> |
|
955 |
> |
/** Implementation of bulk remove methods. */ |
956 |
> |
private boolean bulkRemove(Predicate<? super E> filter) { |
957 |
> |
// checkInvariants(); |
958 |
> |
final Object[] elements = this.elements; |
959 |
> |
final int capacity = elements.length; |
960 |
> |
int i = head, j = i, remaining = size, deleted = 0; |
961 |
> |
try { |
962 |
> |
for (; remaining > 0; remaining--) { |
963 |
> |
@SuppressWarnings("unchecked") E e = (E) elements[i]; |
964 |
> |
if (filter.test(e)) |
965 |
> |
deleted++; |
966 |
> |
else { |
967 |
> |
if (j != i) |
968 |
> |
elements[j] = e; |
969 |
> |
if (++j >= capacity) j = 0; |
970 |
> |
} |
971 |
> |
if (++i >= capacity) i = 0; |
972 |
> |
} |
973 |
> |
return deleted > 0; |
974 |
> |
} catch (Throwable ex) { |
975 |
> |
if (deleted > 0) |
976 |
> |
for (; remaining > 0; remaining--) { |
977 |
> |
elements[j] = elements[i]; |
978 |
> |
if (++i >= capacity) i = 0; |
979 |
> |
if (++j >= capacity) j = 0; |
980 |
> |
} |
981 |
> |
throw ex; |
982 |
> |
} finally { |
983 |
> |
size -= deleted; |
984 |
> |
clearSlice(elements, j, deleted); |
985 |
> |
// checkInvariants(); |
986 |
> |
} |
987 |
> |
} |
988 |
> |
|
989 |
> |
/** |
990 |
> |
* Returns {@code true} if this deque contains the specified element. |
991 |
> |
* More formally, returns {@code true} if and only if this deque contains |
992 |
> |
* at least one element {@code e} such that {@code o.equals(e)}. |
993 |
|
* |
994 |
|
* @param o object to be checked for containment in this deque |
995 |
< |
* @return <tt>true</tt> if this deque contains the specified element |
995 |
> |
* @return {@code true} if this deque contains the specified element |
996 |
|
*/ |
997 |
|
public boolean contains(Object o) { |
998 |
< |
if (o == null) |
999 |
< |
return false; |
1000 |
< |
int mask = elements.length - 1; |
1001 |
< |
int i = head; |
1002 |
< |
E x; |
1003 |
< |
while ( (x = elements[i]) != null) { |
1004 |
< |
if (o.equals(x)) |
1005 |
< |
return true; |
1006 |
< |
i = (i + 1) & mask; |
998 |
> |
if (o != null) { |
999 |
> |
final Object[] elements = this.elements; |
1000 |
> |
final int capacity = elements.length; |
1001 |
> |
int from, end, to, todo; |
1002 |
> |
todo = (end = (from = head) + size) |
1003 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
1004 |
> |
for (;; from = 0, to = todo, todo = 0) { |
1005 |
> |
for (int i = from; i < to; i++) |
1006 |
> |
if (o.equals(elements[i])) |
1007 |
> |
return true; |
1008 |
> |
if (todo == 0) break; |
1009 |
> |
} |
1010 |
|
} |
1011 |
|
return false; |
1012 |
|
} |
1013 |
|
|
1014 |
|
/** |
1015 |
|
* Removes a single instance of the specified element from this deque. |
1016 |
< |
* This method is equivalent to {@link #removeFirstOccurrence}. |
1016 |
> |
* If the deque does not contain the element, it is unchanged. |
1017 |
> |
* More formally, removes the first element {@code e} such that |
1018 |
> |
* {@code o.equals(e)} (if such an element exists). |
1019 |
> |
* Returns {@code true} if this deque contained the specified element |
1020 |
> |
* (or equivalently, if this deque changed as a result of the call). |
1021 |
|
* |
1022 |
< |
* @param e element to be removed from this deque, if present |
1023 |
< |
* @return <tt>true</tt> if this deque contained the specified element |
1022 |
> |
* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}. |
1023 |
> |
* |
1024 |
> |
* @param o element to be removed from this deque, if present |
1025 |
> |
* @return {@code true} if this deque contained the specified element |
1026 |
|
*/ |
1027 |
< |
public boolean remove(Object e) { |
1028 |
< |
return removeFirstOccurrence(e); |
1027 |
> |
public boolean remove(Object o) { |
1028 |
> |
return removeFirstOccurrence(o); |
1029 |
|
} |
1030 |
|
|
1031 |
|
/** |
1032 |
|
* Removes all of the elements from this deque. |
1033 |
+ |
* The deque will be empty after this call returns. |
1034 |
|
*/ |
1035 |
|
public void clear() { |
1036 |
< |
int h = head; |
1037 |
< |
int t = tail; |
1038 |
< |
if (h != t) { // clear all cells |
663 |
< |
head = tail = 0; |
664 |
< |
int i = h; |
665 |
< |
int mask = elements.length - 1; |
666 |
< |
do { |
667 |
< |
elements[i] = null; |
668 |
< |
i = (i + 1) & mask; |
669 |
< |
} while(i != t); |
670 |
< |
} |
1036 |
> |
clearSlice(elements, head, size); |
1037 |
> |
size = head = 0; |
1038 |
> |
// checkInvariants(); |
1039 |
|
} |
1040 |
|
|
1041 |
|
/** |
1042 |
< |
* Returns an array containing all of the elements in this list |
1043 |
< |
* in the correct order. |
1042 |
> |
* Nulls out count elements, starting at array index from. |
1043 |
> |
*/ |
1044 |
> |
private static void clearSlice(Object[] elements, int from, int count) { |
1045 |
> |
final int capacity = elements.length, end = from + count; |
1046 |
> |
final int leg = (capacity - end >= 0) ? end : capacity; |
1047 |
> |
Arrays.fill(elements, from, leg, null); |
1048 |
> |
if (leg != end) |
1049 |
> |
Arrays.fill(elements, 0, end - capacity, null); |
1050 |
> |
} |
1051 |
> |
|
1052 |
> |
/** |
1053 |
> |
* Returns an array containing all of the elements in this deque |
1054 |
> |
* in proper sequence (from first to last element). |
1055 |
> |
* |
1056 |
> |
* <p>The returned array will be "safe" in that no references to it are |
1057 |
> |
* maintained by this deque. (In other words, this method must allocate |
1058 |
> |
* a new array). The caller is thus free to modify the returned array. |
1059 |
|
* |
1060 |
< |
* @return an array containing all of the elements in this list |
1061 |
< |
* in the correct order |
1060 |
> |
* <p>This method acts as bridge between array-based and collection-based |
1061 |
> |
* APIs. |
1062 |
> |
* |
1063 |
> |
* @return an array containing all of the elements in this deque |
1064 |
|
*/ |
1065 |
|
public Object[] toArray() { |
1066 |
< |
return copyElements(new Object[size()]); |
1066 |
> |
return toArray(Object[].class); |
1067 |
> |
} |
1068 |
> |
|
1069 |
> |
private <T> T[] toArray(Class<T[]> klazz) { |
1070 |
> |
final Object[] elements = this.elements; |
1071 |
> |
final int capacity = elements.length; |
1072 |
> |
final int head = this.head, end = head + size; |
1073 |
> |
final T[] a; |
1074 |
> |
if (end >= 0) { |
1075 |
> |
a = Arrays.copyOfRange(elements, head, end, klazz); |
1076 |
> |
} else { |
1077 |
> |
// integer overflow! |
1078 |
> |
a = Arrays.copyOfRange(elements, 0, size, klazz); |
1079 |
> |
System.arraycopy(elements, head, a, 0, capacity - head); |
1080 |
> |
} |
1081 |
> |
if (end - capacity > 0) |
1082 |
> |
System.arraycopy(elements, 0, a, capacity - head, end - capacity); |
1083 |
> |
return a; |
1084 |
|
} |
1085 |
|
|
1086 |
|
/** |
1087 |
< |
* Returns an array containing all of the elements in this deque in the |
1088 |
< |
* correct order; the runtime type of the returned array is that of the |
1089 |
< |
* specified array. If the deque fits in the specified array, it is |
1090 |
< |
* returned therein. Otherwise, a new array is allocated with the runtime |
1091 |
< |
* type of the specified array and the size of this deque. |
1087 |
> |
* Returns an array containing all of the elements in this deque in |
1088 |
> |
* proper sequence (from first to last element); the runtime type of the |
1089 |
> |
* returned array is that of the specified array. If the deque fits in |
1090 |
> |
* the specified array, it is returned therein. Otherwise, a new array |
1091 |
> |
* is allocated with the runtime type of the specified array and the |
1092 |
> |
* size of this deque. |
1093 |
> |
* |
1094 |
> |
* <p>If this deque fits in the specified array with room to spare |
1095 |
> |
* (i.e., the array has more elements than this deque), the element in |
1096 |
> |
* the array immediately following the end of the deque is set to |
1097 |
> |
* {@code null}. |
1098 |
> |
* |
1099 |
> |
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
1100 |
> |
* array-based and collection-based APIs. Further, this method allows |
1101 |
> |
* precise control over the runtime type of the output array, and may, |
1102 |
> |
* under certain circumstances, be used to save allocation costs. |
1103 |
> |
* |
1104 |
> |
* <p>Suppose {@code x} is a deque known to contain only strings. |
1105 |
> |
* The following code can be used to dump the deque into a newly |
1106 |
> |
* allocated array of {@code String}: |
1107 |
|
* |
1108 |
< |
* <p>If the deque fits in the specified array with room to spare (i.e., |
1109 |
< |
* the array has more elements than the deque), the element in the array |
1110 |
< |
* immediately following the end of the collection is set to <tt>null</tt>. |
1108 |
> |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
1109 |
> |
* |
1110 |
> |
* Note that {@code toArray(new Object[0])} is identical in function to |
1111 |
> |
* {@code toArray()}. |
1112 |
|
* |
1113 |
|
* @param a the array into which the elements of the deque are to |
1114 |
< |
* be stored, if it is big enough; otherwise, a new array of the |
1115 |
< |
* same runtime type is allocated for this purpose |
1116 |
< |
* @return an array containing the elements of the deque |
1117 |
< |
* @throws ArrayStoreException if the runtime type of a is not a supertype |
1118 |
< |
* of the runtime type of every element in this deque |
1114 |
> |
* be stored, if it is big enough; otherwise, a new array of the |
1115 |
> |
* same runtime type is allocated for this purpose |
1116 |
> |
* @return an array containing all of the elements in this deque |
1117 |
> |
* @throws ArrayStoreException if the runtime type of the specified array |
1118 |
> |
* is not a supertype of the runtime type of every element in |
1119 |
> |
* this deque |
1120 |
> |
* @throws NullPointerException if the specified array is null |
1121 |
|
*/ |
1122 |
+ |
@SuppressWarnings("unchecked") |
1123 |
|
public <T> T[] toArray(T[] a) { |
1124 |
< |
int size = size(); |
1125 |
< |
if (a.length < size) |
1126 |
< |
a = (T[])java.lang.reflect.Array.newInstance( |
1127 |
< |
a.getClass().getComponentType(), size); |
1128 |
< |
copyElements(a); |
1129 |
< |
if (a.length > size) |
1124 |
> |
final int size = this.size; |
1125 |
> |
if (size > a.length) |
1126 |
> |
return toArray((Class<T[]>) a.getClass()); |
1127 |
> |
final Object[] elements = this.elements; |
1128 |
> |
final int capacity = elements.length; |
1129 |
> |
final int head = this.head, end = head + size; |
1130 |
> |
final int front = (capacity - end >= 0) ? size : capacity - head; |
1131 |
> |
System.arraycopy(elements, head, a, 0, front); |
1132 |
> |
if (front != size) |
1133 |
> |
System.arraycopy(elements, 0, a, capacity - head, end - capacity); |
1134 |
> |
if (size < a.length) |
1135 |
|
a[size] = null; |
1136 |
|
return a; |
1137 |
|
} |
1144 |
|
* @return a copy of this deque |
1145 |
|
*/ |
1146 |
|
public ArrayDeque<E> clone() { |
1147 |
< |
try { |
1147 |
> |
try { |
1148 |
> |
@SuppressWarnings("unchecked") |
1149 |
|
ArrayDeque<E> result = (ArrayDeque<E>) super.clone(); |
1150 |
< |
// These two lines are currently faster than cloning the array: |
724 |
< |
result.elements = (E[]) new Object[elements.length]; |
725 |
< |
System.arraycopy(elements, 0, result.elements, 0, elements.length); |
1150 |
> |
result.elements = Arrays.copyOf(elements, elements.length); |
1151 |
|
return result; |
1152 |
< |
|
728 |
< |
} catch (CloneNotSupportedException e) { |
1152 |
> |
} catch (CloneNotSupportedException e) { |
1153 |
|
throw new AssertionError(); |
1154 |
|
} |
1155 |
|
} |
1156 |
|
|
733 |
– |
/** |
734 |
– |
* Appease the serialization gods. |
735 |
– |
*/ |
1157 |
|
private static final long serialVersionUID = 2340985798034038923L; |
1158 |
|
|
1159 |
|
/** |
1160 |
< |
* Serialize this deque. |
1160 |
> |
* Saves this deque to a stream (that is, serializes it). |
1161 |
|
* |
1162 |
< |
* @serialData The current size (<tt>int</tt>) of the deque, |
1162 |
> |
* @param s the stream |
1163 |
> |
* @throws java.io.IOException if an I/O error occurs |
1164 |
> |
* @serialData The current size ({@code int}) of the deque, |
1165 |
|
* followed by all of its elements (each an object reference) in |
1166 |
|
* first-to-last order. |
1167 |
|
*/ |
1168 |
< |
private void writeObject(ObjectOutputStream s) throws IOException { |
1168 |
> |
private void writeObject(java.io.ObjectOutputStream s) |
1169 |
> |
throws java.io.IOException { |
1170 |
|
s.defaultWriteObject(); |
1171 |
|
|
1172 |
|
// Write out size |
749 |
– |
int size = size(); |
1173 |
|
s.writeInt(size); |
1174 |
|
|
1175 |
|
// Write out elements in order. |
1176 |
< |
int i = head; |
1177 |
< |
int mask = elements.length - 1; |
1178 |
< |
for (int j = 0; j < size; j++) { |
1179 |
< |
s.writeObject(elements[i]); |
1180 |
< |
i = (i + 1) & mask; |
1176 |
> |
final Object[] elements = this.elements; |
1177 |
> |
final int capacity = elements.length; |
1178 |
> |
int from, end, to, todo; |
1179 |
> |
todo = (end = (from = head) + size) |
1180 |
> |
- (to = (capacity - end >= 0) ? end : capacity); |
1181 |
> |
for (;; from = 0, to = todo, todo = 0) { |
1182 |
> |
for (int i = from; i < to; i++) |
1183 |
> |
s.writeObject(elements[i]); |
1184 |
> |
if (todo == 0) break; |
1185 |
|
} |
1186 |
|
} |
1187 |
|
|
1188 |
|
/** |
1189 |
< |
* Deserialize this deque. |
1189 |
> |
* Reconstitutes this deque from a stream (that is, deserializes it). |
1190 |
> |
* @param s the stream |
1191 |
> |
* @throws ClassNotFoundException if the class of a serialized object |
1192 |
> |
* could not be found |
1193 |
> |
* @throws java.io.IOException if an I/O error occurs |
1194 |
|
*/ |
1195 |
< |
private void readObject(ObjectInputStream s) |
1196 |
< |
throws IOException, ClassNotFoundException { |
1195 |
> |
private void readObject(java.io.ObjectInputStream s) |
1196 |
> |
throws java.io.IOException, ClassNotFoundException { |
1197 |
|
s.defaultReadObject(); |
1198 |
|
|
1199 |
|
// Read in size and allocate array |
1200 |
< |
int size = s.readInt(); |
770 |
< |
allocateElements(size); |
771 |
< |
head = 0; |
772 |
< |
tail = size; |
1200 |
> |
elements = new Object[size = s.readInt()]; |
1201 |
|
|
1202 |
|
// Read in all elements in the proper order. |
1203 |
|
for (int i = 0; i < size; i++) |
1204 |
< |
elements[i] = (E)s.readObject(); |
1204 |
> |
elements[i] = s.readObject(); |
1205 |
> |
} |
1206 |
|
|
1207 |
+ |
/** debugging */ |
1208 |
+ |
void checkInvariants() { |
1209 |
+ |
try { |
1210 |
+ |
int capacity = elements.length; |
1211 |
+ |
// assert size >= 0 && size <= capacity; |
1212 |
+ |
// assert head >= 0; |
1213 |
+ |
// assert capacity == 0 || head < capacity; |
1214 |
+ |
// assert size == 0 || elements[head] != null; |
1215 |
+ |
// assert size == 0 || elements[tail()] != null; |
1216 |
+ |
// assert size == capacity || elements[dec(head, capacity)] == null; |
1217 |
+ |
// assert size == capacity || elements[inc(tail(), capacity)] == null; |
1218 |
+ |
} catch (Throwable t) { |
1219 |
+ |
System.err.printf("head=%d size=%d capacity=%d%n", |
1220 |
+ |
head, size, elements.length); |
1221 |
+ |
System.err.printf("elements=%s%n", |
1222 |
+ |
Arrays.toString(elements)); |
1223 |
+ |
throw t; |
1224 |
+ |
} |
1225 |
|
} |
1226 |
+ |
|
1227 |
|
} |