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dl |
1.1 |
/* |
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1.47 |
* 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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dl |
1.1 |
*/ |
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package java.util; |
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jsr166 |
1.61 |
|
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dl |
1.47 |
import java.io.Serializable; |
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import java.util.function.Consumer; |
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jsr166 |
1.75 |
import java.util.function.Predicate; |
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import java.util.function.UnaryOperator; |
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1.1 |
|
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/** |
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* Resizable-array implementation of the {@link Deque} interface. Array |
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* deques have no capacity restrictions; they grow as necessary to support |
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* usage. They are not thread-safe; in the absence of external |
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* synchronization, they do not support concurrent access by multiple threads. |
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* Null elements are prohibited. This class is likely to be faster than |
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dl |
1.2 |
* {@link Stack} when used as a stack, and faster than {@link LinkedList} |
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1.1 |
* when used as a queue. |
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* |
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jsr166 |
1.43 |
* <p>Most {@code ArrayDeque} operations run in amortized constant time. |
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1.51 |
* 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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1.41 |
* |
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1.51 |
* <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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jsr166 |
1.7 |
* 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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1.1 |
* |
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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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1.43 |
* throw {@code ConcurrentModificationException} on a best-effort basis. |
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1.1 |
* 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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jsr166 |
1.9 |
* <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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jsr166 |
1.29 |
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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jsr166 |
1.9 |
* Java Collections Framework</a>. |
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dl |
1.1 |
* |
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* @author Josh Bloch and Doug Lea |
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1.74 |
* @param <E> the type of elements held in this deque |
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1.1 |
* @since 1.6 |
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*/ |
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public class ArrayDeque<E> extends AbstractCollection<E> |
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1.47 |
implements Deque<E>, Cloneable, Serializable |
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1.1 |
{ |
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/** |
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1.4 |
* The array in which the elements of the deque are stored. |
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1.75 |
* We guarantee that all array cells not holding deque elements |
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* are always null. |
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1.1 |
*/ |
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1.75 |
transient Object[] elements; |
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1.1 |
|
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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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jsr166 |
1.75 |
* arbitrary number 0 <= head < elements.length if the deque is empty. |
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dl |
1.1 |
*/ |
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dl |
1.41 |
transient int head; |
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1.1 |
|
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1.75 |
/** Number of elements in this collection. */ |
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transient int size; |
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1.1 |
/** |
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1.75 |
* 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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1.1 |
*/ |
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jsr166 |
1.75 |
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
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1.1 |
|
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/** |
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jsr166 |
1.75 |
* 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 |
92 |
dl |
1.1 |
*/ |
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jsr166 |
1.75 |
private void grow(int needed) { |
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// overflow-conscious code |
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// checkInvariants(); |
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int oldCapacity = elements.length; |
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int newCapacity; |
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// Double size if small; else grow by 50% |
99 |
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int jump = (oldCapacity < 64) ? (oldCapacity + 2) : (oldCapacity >> 1); |
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if (jump < needed |
101 |
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|| (newCapacity = (oldCapacity + jump)) - MAX_ARRAY_SIZE > 0) |
102 |
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newCapacity = newCapacity(needed, jump); |
103 |
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elements = Arrays.copyOf(elements, newCapacity); |
104 |
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if (oldCapacity - head < size) { |
105 |
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// wrap around; slide first leg forward to end of array |
106 |
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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; |
112 |
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} |
113 |
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// checkInvariants(); |
114 |
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} |
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1.1 |
|
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1.75 |
/** Capacity calculation for edge conditions, especially overflow. */ |
117 |
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private int newCapacity(int needed, int jump) { |
118 |
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int oldCapacity = elements.length; |
119 |
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int minCapacity; |
120 |
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if ((minCapacity = oldCapacity + needed) - MAX_ARRAY_SIZE > 0) { |
121 |
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if (minCapacity < 0) |
122 |
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throw new IllegalStateException("Sorry, deque too big"); |
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return Integer.MAX_VALUE; |
124 |
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} |
125 |
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if (needed > jump) |
126 |
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return minCapacity; |
127 |
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return (oldCapacity + jump - MAX_ARRAY_SIZE < 0) |
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? oldCapacity + jump |
129 |
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: MAX_ARRAY_SIZE; |
130 |
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} |
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dl |
1.1 |
|
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/** |
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1.75 |
* 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. |
135 |
dl |
1.1 |
* |
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jsr166 |
1.75 |
* @param minCapacity the desired minimum capacity |
137 |
jsr166 |
1.80 |
* @since TBD |
138 |
dl |
1.1 |
*/ |
139 |
jsr166 |
1.80 |
/* public */ void ensureCapacity(int minCapacity) { |
140 |
jsr166 |
1.75 |
if (minCapacity > elements.length) |
141 |
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grow(minCapacity - elements.length); |
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// checkInvariants(); |
143 |
dl |
1.1 |
} |
144 |
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145 |
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/** |
146 |
jsr166 |
1.75 |
* Minimizes the internal storage of this collection. |
147 |
jsr166 |
1.80 |
* |
148 |
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* @since TBD |
149 |
dl |
1.1 |
*/ |
150 |
jsr166 |
1.80 |
/* public */ void trimToSize() { |
151 |
jsr166 |
1.75 |
if (size < elements.length) { |
152 |
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elements = toArray(); |
153 |
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head = 0; |
154 |
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} |
155 |
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// checkInvariants(); |
156 |
dl |
1.1 |
} |
157 |
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158 |
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/** |
159 |
dl |
1.4 |
* Constructs an empty array deque with an initial capacity |
160 |
dl |
1.1 |
* sufficient to hold 16 elements. |
161 |
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*/ |
162 |
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public ArrayDeque() { |
163 |
jsr166 |
1.34 |
elements = new Object[16]; |
164 |
dl |
1.1 |
} |
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/** |
167 |
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* Constructs an empty array deque with an initial capacity |
168 |
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* sufficient to hold the specified number of elements. |
169 |
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* |
170 |
jsr166 |
1.75 |
* @param numElements lower bound on initial capacity of the deque |
171 |
dl |
1.1 |
*/ |
172 |
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public ArrayDeque(int numElements) { |
173 |
jsr166 |
1.75 |
elements = new Object[numElements]; |
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dl |
1.1 |
} |
175 |
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176 |
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/** |
177 |
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* Constructs a deque containing the elements of the specified |
178 |
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* collection, in the order they are returned by the collection's |
179 |
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* iterator. (The first element returned by the collection's |
180 |
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* iterator becomes the first element, or <i>front</i> of the |
181 |
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* deque.) |
182 |
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* |
183 |
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* @param c the collection whose elements are to be placed into the deque |
184 |
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* @throws NullPointerException if the specified collection is null |
185 |
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*/ |
186 |
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public ArrayDeque(Collection<? extends E> c) { |
187 |
jsr166 |
1.75 |
Object[] elements = c.toArray(); |
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// defend against c.toArray (incorrectly) not returning Object[] |
189 |
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// (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652) |
190 |
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if (elements.getClass() != Object[].class) |
191 |
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elements = Arrays.copyOf(elements, size, Object[].class); |
192 |
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for (Object obj : elements) |
193 |
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Objects.requireNonNull(obj); |
194 |
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size = elements.length; |
195 |
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this.elements = elements; |
196 |
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} |
197 |
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198 |
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/** |
199 |
jsr166 |
1.79 |
* Increments i, mod modulus. |
200 |
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* Precondition and postcondition: 0 <= i < modulus. |
201 |
jsr166 |
1.75 |
*/ |
202 |
jsr166 |
1.79 |
static final int inc(int i, int modulus) { |
203 |
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if (++i == modulus) i = 0; |
204 |
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return i; |
205 |
jsr166 |
1.75 |
} |
206 |
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207 |
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/** |
208 |
jsr166 |
1.79 |
* Decrements i, mod modulus. |
209 |
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* Precondition and postcondition: 0 <= i < modulus. |
210 |
jsr166 |
1.75 |
*/ |
211 |
jsr166 |
1.79 |
static final int dec(int i, int modulus) { |
212 |
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if (--i < 0) i += modulus; |
213 |
jsr166 |
1.75 |
return i; |
214 |
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} |
215 |
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216 |
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/** |
217 |
jsr166 |
1.79 |
* Adds i and j, mod modulus. |
218 |
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* Precondition and postcondition: 0 <= i < modulus, 0 <= j <= modulus. |
219 |
jsr166 |
1.75 |
*/ |
220 |
jsr166 |
1.79 |
static final int add(int i, int j, int modulus) { |
221 |
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if ((i += j) - modulus >= 0) i -= modulus; |
222 |
jsr166 |
1.75 |
return i; |
223 |
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} |
224 |
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225 |
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/** |
226 |
jsr166 |
1.79 |
* Returns the array index of the last element. |
227 |
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* May return invalid index -1 if there are no elements. |
228 |
jsr166 |
1.75 |
*/ |
229 |
jsr166 |
1.79 |
final int tail() { |
230 |
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return add(head, size - 1, elements.length); |
231 |
jsr166 |
1.75 |
} |
232 |
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233 |
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/** |
234 |
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* Returns element at array index i. |
235 |
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*/ |
236 |
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@SuppressWarnings("unchecked") |
237 |
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final E elementAt(int i) { |
238 |
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return (E) elements[i]; |
239 |
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} |
240 |
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241 |
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/** |
242 |
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* A version of elementAt that checks for null elements. |
243 |
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* This check doesn't catch all possible comodifications, |
244 |
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* but does catch ones that corrupt traversal. |
245 |
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*/ |
246 |
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E checkedElementAt(Object[] elements, int i) { |
247 |
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@SuppressWarnings("unchecked") E e = (E) elements[i]; |
248 |
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if (e == null) |
249 |
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throw new ConcurrentModificationException(); |
250 |
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return e; |
251 |
dl |
1.1 |
} |
252 |
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253 |
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// The main insertion and extraction methods are addFirst, |
254 |
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// addLast, pollFirst, pollLast. The other methods are defined in |
255 |
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// terms of these. |
256 |
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257 |
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/** |
258 |
dl |
1.5 |
* Inserts the specified element at the front of this deque. |
259 |
dl |
1.1 |
* |
260 |
jsr166 |
1.9 |
* @param e the element to add |
261 |
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* @throws NullPointerException if the specified element is null |
262 |
dl |
1.1 |
*/ |
263 |
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public void addFirst(E e) { |
264 |
jsr166 |
1.75 |
// checkInvariants(); |
265 |
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Objects.requireNonNull(e); |
266 |
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Object[] elements; |
267 |
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int capacity, s = size; |
268 |
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while (s == (capacity = (elements = this.elements).length)) |
269 |
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grow(1); |
270 |
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elements[head = dec(head, capacity)] = e; |
271 |
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size = s + 1; |
272 |
dl |
1.1 |
} |
273 |
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|
274 |
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/** |
275 |
dl |
1.6 |
* Inserts the specified element at the end of this deque. |
276 |
jsr166 |
1.14 |
* |
277 |
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* <p>This method is equivalent to {@link #add}. |
278 |
dl |
1.1 |
* |
279 |
jsr166 |
1.9 |
* @param e the element to add |
280 |
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* @throws NullPointerException if the specified element is null |
281 |
dl |
1.1 |
*/ |
282 |
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public void addLast(E e) { |
283 |
jsr166 |
1.75 |
// checkInvariants(); |
284 |
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Objects.requireNonNull(e); |
285 |
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Object[] elements; |
286 |
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int capacity, s = size; |
287 |
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while (s == (capacity = (elements = this.elements).length)) |
288 |
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grow(1); |
289 |
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elements[add(head, s, capacity)] = e; |
290 |
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size = s + 1; |
291 |
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} |
292 |
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|
293 |
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/** |
294 |
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* Adds all of the elements in the specified collection at the end |
295 |
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* of this deque, as if by calling {@link #addLast} on each one, |
296 |
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* in the order that they are returned by the collection's |
297 |
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* iterator. |
298 |
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* |
299 |
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* @param c the elements to be inserted into this deque |
300 |
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* @return {@code true} if this deque changed as a result of the call |
301 |
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* @throws NullPointerException if the specified collection or any |
302 |
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* of its elements are null |
303 |
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*/ |
304 |
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@Override |
305 |
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public boolean addAll(Collection<? extends E> c) { |
306 |
|
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// checkInvariants(); |
307 |
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Object[] a, elements; |
308 |
jsr166 |
1.79 |
int newcomers, capacity, s = size; |
309 |
|
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if ((newcomers = (a = c.toArray()).length) == 0) |
310 |
jsr166 |
1.75 |
return false; |
311 |
jsr166 |
1.79 |
while ((capacity = (elements = this.elements).length) - s < newcomers) |
312 |
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grow(newcomers - (capacity - s)); |
313 |
jsr166 |
1.75 |
int i = add(head, s, capacity); |
314 |
|
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for (Object x : a) { |
315 |
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Objects.requireNonNull(x); |
316 |
|
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elements[i] = x; |
317 |
|
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i = inc(i, capacity); |
318 |
|
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size++; |
319 |
|
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} |
320 |
|
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return true; |
321 |
dl |
1.1 |
} |
322 |
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|
323 |
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/** |
324 |
dl |
1.5 |
* Inserts the specified element at the front of this deque. |
325 |
dl |
1.1 |
* |
326 |
jsr166 |
1.9 |
* @param e the element to add |
327 |
jsr166 |
1.40 |
* @return {@code true} (as specified by {@link Deque#offerFirst}) |
328 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
329 |
dl |
1.1 |
*/ |
330 |
|
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public boolean offerFirst(E e) { |
331 |
|
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addFirst(e); |
332 |
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return true; |
333 |
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} |
334 |
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|
335 |
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/** |
336 |
dl |
1.6 |
* Inserts the specified element at the end of this deque. |
337 |
dl |
1.1 |
* |
338 |
jsr166 |
1.9 |
* @param e the element to add |
339 |
jsr166 |
1.40 |
* @return {@code true} (as specified by {@link Deque#offerLast}) |
340 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
341 |
dl |
1.1 |
*/ |
342 |
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public boolean offerLast(E e) { |
343 |
|
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addLast(e); |
344 |
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return true; |
345 |
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} |
346 |
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|
347 |
|
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/** |
348 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
349 |
dl |
1.1 |
*/ |
350 |
|
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public E removeFirst() { |
351 |
jsr166 |
1.75 |
// checkInvariants(); |
352 |
dl |
1.1 |
E x = pollFirst(); |
353 |
|
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if (x == null) |
354 |
|
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throw new NoSuchElementException(); |
355 |
|
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return x; |
356 |
|
|
} |
357 |
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|
358 |
|
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/** |
359 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
360 |
dl |
1.1 |
*/ |
361 |
|
|
public E removeLast() { |
362 |
jsr166 |
1.75 |
// checkInvariants(); |
363 |
dl |
1.1 |
E x = pollLast(); |
364 |
|
|
if (x == null) |
365 |
|
|
throw new NoSuchElementException(); |
366 |
|
|
return x; |
367 |
|
|
} |
368 |
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|
369 |
jsr166 |
1.9 |
public E pollFirst() { |
370 |
jsr166 |
1.75 |
// checkInvariants(); |
371 |
|
|
final int s, h; |
372 |
|
|
if ((s = size) == 0) |
373 |
|
|
return null; |
374 |
jsr166 |
1.66 |
final Object[] elements = this.elements; |
375 |
jsr166 |
1.75 |
@SuppressWarnings("unchecked") E e = (E) elements[h = head]; |
376 |
|
|
elements[h] = null; |
377 |
|
|
head = inc(h, elements.length); |
378 |
|
|
size = s - 1; |
379 |
|
|
return e; |
380 |
dl |
1.1 |
} |
381 |
|
|
|
382 |
jsr166 |
1.9 |
public E pollLast() { |
383 |
jsr166 |
1.75 |
// checkInvariants(); |
384 |
|
|
final int s, tail; |
385 |
|
|
if ((s = size) == 0) |
386 |
|
|
return null; |
387 |
jsr166 |
1.66 |
final Object[] elements = this.elements; |
388 |
jsr166 |
1.37 |
@SuppressWarnings("unchecked") |
389 |
jsr166 |
1.75 |
E e = (E) elements[tail = add(head, s - 1, elements.length)]; |
390 |
|
|
elements[tail] = null; |
391 |
|
|
size = s - 1; |
392 |
|
|
return e; |
393 |
dl |
1.1 |
} |
394 |
|
|
|
395 |
|
|
/** |
396 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
397 |
dl |
1.1 |
*/ |
398 |
|
|
public E getFirst() { |
399 |
jsr166 |
1.75 |
// checkInvariants(); |
400 |
|
|
if (size == 0) throw new NoSuchElementException(); |
401 |
|
|
return elementAt(head); |
402 |
dl |
1.1 |
} |
403 |
|
|
|
404 |
|
|
/** |
405 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
406 |
dl |
1.1 |
*/ |
407 |
|
|
public E getLast() { |
408 |
jsr166 |
1.75 |
// checkInvariants(); |
409 |
|
|
if (size == 0) throw new NoSuchElementException(); |
410 |
|
|
return elementAt(tail()); |
411 |
dl |
1.1 |
} |
412 |
|
|
|
413 |
jsr166 |
1.9 |
public E peekFirst() { |
414 |
jsr166 |
1.75 |
// checkInvariants(); |
415 |
|
|
return (size == 0) ? null : elementAt(head); |
416 |
jsr166 |
1.9 |
} |
417 |
|
|
|
418 |
|
|
public E peekLast() { |
419 |
jsr166 |
1.75 |
// checkInvariants(); |
420 |
|
|
return (size == 0) ? null : elementAt(tail()); |
421 |
jsr166 |
1.9 |
} |
422 |
|
|
|
423 |
dl |
1.1 |
/** |
424 |
|
|
* Removes the first occurrence of the specified element in this |
425 |
jsr166 |
1.9 |
* deque (when traversing the deque from head to tail). |
426 |
|
|
* If the deque does not contain the element, it is unchanged. |
427 |
jsr166 |
1.40 |
* More formally, removes the first element {@code e} such that |
428 |
|
|
* {@code o.equals(e)} (if such an element exists). |
429 |
|
|
* Returns {@code true} if this deque contained the specified element |
430 |
jsr166 |
1.12 |
* (or equivalently, if this deque changed as a result of the call). |
431 |
dl |
1.1 |
* |
432 |
dl |
1.5 |
* @param o element to be removed from this deque, if present |
433 |
jsr166 |
1.40 |
* @return {@code true} if the deque contained the specified element |
434 |
dl |
1.1 |
*/ |
435 |
dl |
1.5 |
public boolean removeFirstOccurrence(Object o) { |
436 |
jsr166 |
1.75 |
// checkInvariants(); |
437 |
jsr166 |
1.58 |
if (o != null) { |
438 |
jsr166 |
1.75 |
final Object[] elements = this.elements; |
439 |
|
|
final int capacity = elements.length; |
440 |
|
|
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) { |
441 |
|
|
if (o.equals(elements[i])) { |
442 |
jsr166 |
1.58 |
delete(i); |
443 |
|
|
return true; |
444 |
|
|
} |
445 |
dl |
1.1 |
} |
446 |
|
|
} |
447 |
|
|
return false; |
448 |
|
|
} |
449 |
|
|
|
450 |
|
|
/** |
451 |
|
|
* Removes the last occurrence of the specified element in this |
452 |
jsr166 |
1.9 |
* deque (when traversing the deque from head to tail). |
453 |
|
|
* If the deque does not contain the element, it is unchanged. |
454 |
jsr166 |
1.40 |
* More formally, removes the last element {@code e} such that |
455 |
|
|
* {@code o.equals(e)} (if such an element exists). |
456 |
|
|
* Returns {@code true} if this deque contained the specified element |
457 |
jsr166 |
1.12 |
* (or equivalently, if this deque changed as a result of the call). |
458 |
dl |
1.1 |
* |
459 |
dl |
1.5 |
* @param o element to be removed from this deque, if present |
460 |
jsr166 |
1.40 |
* @return {@code true} if the deque contained the specified element |
461 |
dl |
1.1 |
*/ |
462 |
dl |
1.5 |
public boolean removeLastOccurrence(Object o) { |
463 |
jsr166 |
1.59 |
if (o != null) { |
464 |
jsr166 |
1.75 |
final Object[] elements = this.elements; |
465 |
|
|
final int capacity = elements.length; |
466 |
|
|
for (int k = size, i = add(head, k - 1, capacity); |
467 |
|
|
--k >= 0; i = dec(i, capacity)) { |
468 |
|
|
if (o.equals(elements[i])) { |
469 |
jsr166 |
1.59 |
delete(i); |
470 |
|
|
return true; |
471 |
|
|
} |
472 |
dl |
1.1 |
} |
473 |
|
|
} |
474 |
|
|
return false; |
475 |
|
|
} |
476 |
|
|
|
477 |
|
|
// *** Queue methods *** |
478 |
|
|
|
479 |
|
|
/** |
480 |
dl |
1.6 |
* Inserts the specified element at the end of this deque. |
481 |
dl |
1.1 |
* |
482 |
|
|
* <p>This method is equivalent to {@link #addLast}. |
483 |
|
|
* |
484 |
jsr166 |
1.9 |
* @param e the element to add |
485 |
jsr166 |
1.40 |
* @return {@code true} (as specified by {@link Collection#add}) |
486 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
487 |
dl |
1.1 |
*/ |
488 |
|
|
public boolean add(E e) { |
489 |
|
|
addLast(e); |
490 |
|
|
return true; |
491 |
|
|
} |
492 |
|
|
|
493 |
|
|
/** |
494 |
jsr166 |
1.9 |
* Inserts the specified element at the end of this deque. |
495 |
dl |
1.1 |
* |
496 |
jsr166 |
1.9 |
* <p>This method is equivalent to {@link #offerLast}. |
497 |
dl |
1.1 |
* |
498 |
jsr166 |
1.9 |
* @param e the element to add |
499 |
jsr166 |
1.40 |
* @return {@code true} (as specified by {@link Queue#offer}) |
500 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
501 |
dl |
1.1 |
*/ |
502 |
jsr166 |
1.9 |
public boolean offer(E e) { |
503 |
|
|
return offerLast(e); |
504 |
dl |
1.1 |
} |
505 |
|
|
|
506 |
|
|
/** |
507 |
|
|
* Retrieves and removes the head of the queue represented by this deque. |
508 |
jsr166 |
1.15 |
* |
509 |
|
|
* This method differs from {@link #poll poll} only in that it throws an |
510 |
jsr166 |
1.9 |
* exception if this deque is empty. |
511 |
dl |
1.1 |
* |
512 |
|
|
* <p>This method is equivalent to {@link #removeFirst}. |
513 |
|
|
* |
514 |
|
|
* @return the head of the queue represented by this deque |
515 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
516 |
dl |
1.1 |
*/ |
517 |
|
|
public E remove() { |
518 |
|
|
return removeFirst(); |
519 |
|
|
} |
520 |
|
|
|
521 |
|
|
/** |
522 |
jsr166 |
1.9 |
* Retrieves and removes the head of the queue represented by this deque |
523 |
|
|
* (in other words, the first element of this deque), or returns |
524 |
jsr166 |
1.40 |
* {@code null} if this deque is empty. |
525 |
dl |
1.1 |
* |
526 |
jsr166 |
1.9 |
* <p>This method is equivalent to {@link #pollFirst}. |
527 |
dl |
1.1 |
* |
528 |
|
|
* @return the head of the queue represented by this deque, or |
529 |
jsr166 |
1.40 |
* {@code null} if this deque is empty |
530 |
dl |
1.1 |
*/ |
531 |
jsr166 |
1.9 |
public E poll() { |
532 |
|
|
return pollFirst(); |
533 |
dl |
1.1 |
} |
534 |
|
|
|
535 |
|
|
/** |
536 |
|
|
* Retrieves, but does not remove, the head of the queue represented by |
537 |
jsr166 |
1.15 |
* this deque. This method differs from {@link #peek peek} only in |
538 |
|
|
* that it throws an exception if this deque is empty. |
539 |
dl |
1.1 |
* |
540 |
jsr166 |
1.8 |
* <p>This method is equivalent to {@link #getFirst}. |
541 |
dl |
1.1 |
* |
542 |
|
|
* @return the head of the queue represented by this deque |
543 |
jsr166 |
1.9 |
* @throws NoSuchElementException {@inheritDoc} |
544 |
dl |
1.1 |
*/ |
545 |
|
|
public E element() { |
546 |
|
|
return getFirst(); |
547 |
|
|
} |
548 |
|
|
|
549 |
jsr166 |
1.9 |
/** |
550 |
|
|
* Retrieves, but does not remove, the head of the queue represented by |
551 |
jsr166 |
1.40 |
* this deque, or returns {@code null} if this deque is empty. |
552 |
jsr166 |
1.9 |
* |
553 |
|
|
* <p>This method is equivalent to {@link #peekFirst}. |
554 |
|
|
* |
555 |
|
|
* @return the head of the queue represented by this deque, or |
556 |
jsr166 |
1.40 |
* {@code null} if this deque is empty |
557 |
jsr166 |
1.9 |
*/ |
558 |
|
|
public E peek() { |
559 |
|
|
return peekFirst(); |
560 |
|
|
} |
561 |
|
|
|
562 |
dl |
1.1 |
// *** Stack methods *** |
563 |
|
|
|
564 |
|
|
/** |
565 |
|
|
* Pushes an element onto the stack represented by this deque. In other |
566 |
dl |
1.5 |
* words, inserts the element at the front of this deque. |
567 |
dl |
1.1 |
* |
568 |
|
|
* <p>This method is equivalent to {@link #addFirst}. |
569 |
|
|
* |
570 |
|
|
* @param e the element to push |
571 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified element is null |
572 |
dl |
1.1 |
*/ |
573 |
|
|
public void push(E e) { |
574 |
|
|
addFirst(e); |
575 |
|
|
} |
576 |
|
|
|
577 |
|
|
/** |
578 |
|
|
* Pops an element from the stack represented by this deque. In other |
579 |
dl |
1.2 |
* words, removes and returns the first element of this deque. |
580 |
dl |
1.1 |
* |
581 |
|
|
* <p>This method is equivalent to {@link #removeFirst()}. |
582 |
|
|
* |
583 |
|
|
* @return the element at the front of this deque (which is the top |
584 |
jsr166 |
1.9 |
* of the stack represented by this deque) |
585 |
|
|
* @throws NoSuchElementException {@inheritDoc} |
586 |
dl |
1.1 |
*/ |
587 |
|
|
public E pop() { |
588 |
|
|
return removeFirst(); |
589 |
|
|
} |
590 |
|
|
|
591 |
|
|
/** |
592 |
jsr166 |
1.75 |
* Removes the element at the specified position in the elements array. |
593 |
|
|
* This can result in forward or backwards motion of array elements. |
594 |
|
|
* We optimize for least element motion. |
595 |
dl |
1.1 |
* |
596 |
dl |
1.5 |
* <p>This method is called delete rather than remove to emphasize |
597 |
jsr166 |
1.9 |
* that its semantics differ from those of {@link List#remove(int)}. |
598 |
dl |
1.5 |
* |
599 |
dl |
1.1 |
* @return true if elements moved backwards |
600 |
|
|
*/ |
601 |
jsr166 |
1.71 |
boolean delete(int i) { |
602 |
jsr166 |
1.75 |
// checkInvariants(); |
603 |
jsr166 |
1.34 |
final Object[] elements = this.elements; |
604 |
jsr166 |
1.75 |
final int capacity = elements.length; |
605 |
jsr166 |
1.30 |
final int h = head; |
606 |
jsr166 |
1.75 |
int front; // number of elements before to-be-deleted elt |
607 |
|
|
if ((front = i - h) < 0) front += capacity; |
608 |
|
|
final int back = size - front - 1; // number of elements after |
609 |
jsr166 |
1.30 |
if (front < back) { |
610 |
jsr166 |
1.75 |
// move front elements forwards |
611 |
jsr166 |
1.30 |
if (h <= i) { |
612 |
|
|
System.arraycopy(elements, h, elements, h + 1, front); |
613 |
|
|
} else { // Wrap around |
614 |
|
|
System.arraycopy(elements, 0, elements, 1, i); |
615 |
jsr166 |
1.75 |
elements[0] = elements[capacity - 1]; |
616 |
|
|
System.arraycopy(elements, h, elements, h + 1, front - (i + 1)); |
617 |
jsr166 |
1.30 |
} |
618 |
|
|
elements[h] = null; |
619 |
jsr166 |
1.75 |
head = inc(h, capacity); |
620 |
|
|
size--; |
621 |
|
|
// checkInvariants(); |
622 |
jsr166 |
1.30 |
return false; |
623 |
|
|
} else { |
624 |
jsr166 |
1.75 |
// move back elements backwards |
625 |
|
|
int tail = tail(); |
626 |
|
|
if (i <= tail) { |
627 |
jsr166 |
1.30 |
System.arraycopy(elements, i + 1, elements, i, back); |
628 |
|
|
} else { // Wrap around |
629 |
jsr166 |
1.75 |
int firstLeg = capacity - (i + 1); |
630 |
|
|
System.arraycopy(elements, i + 1, elements, i, firstLeg); |
631 |
|
|
elements[capacity - 1] = elements[0]; |
632 |
|
|
System.arraycopy(elements, 1, elements, 0, back - firstLeg - 1); |
633 |
jsr166 |
1.30 |
} |
634 |
jsr166 |
1.75 |
elements[tail] = null; |
635 |
|
|
size--; |
636 |
|
|
// checkInvariants(); |
637 |
jsr166 |
1.30 |
return true; |
638 |
|
|
} |
639 |
dl |
1.23 |
} |
640 |
|
|
|
641 |
dl |
1.1 |
// *** Collection Methods *** |
642 |
|
|
|
643 |
|
|
/** |
644 |
|
|
* Returns the number of elements in this deque. |
645 |
|
|
* |
646 |
|
|
* @return the number of elements in this deque |
647 |
|
|
*/ |
648 |
|
|
public int size() { |
649 |
jsr166 |
1.75 |
return size; |
650 |
dl |
1.1 |
} |
651 |
|
|
|
652 |
|
|
/** |
653 |
jsr166 |
1.40 |
* Returns {@code true} if this deque contains no elements. |
654 |
dl |
1.1 |
* |
655 |
jsr166 |
1.40 |
* @return {@code true} if this deque contains no elements |
656 |
dl |
1.1 |
*/ |
657 |
|
|
public boolean isEmpty() { |
658 |
jsr166 |
1.75 |
return size == 0; |
659 |
dl |
1.1 |
} |
660 |
|
|
|
661 |
|
|
/** |
662 |
|
|
* Returns an iterator over the elements in this deque. The elements |
663 |
|
|
* will be ordered from first (head) to last (tail). This is the same |
664 |
|
|
* order that elements would be dequeued (via successive calls to |
665 |
|
|
* {@link #remove} or popped (via successive calls to {@link #pop}). |
666 |
dl |
1.5 |
* |
667 |
jsr166 |
1.18 |
* @return an iterator over the elements in this deque |
668 |
dl |
1.1 |
*/ |
669 |
|
|
public Iterator<E> iterator() { |
670 |
|
|
return new DeqIterator(); |
671 |
|
|
} |
672 |
|
|
|
673 |
dl |
1.16 |
public Iterator<E> descendingIterator() { |
674 |
|
|
return new DescendingIterator(); |
675 |
|
|
} |
676 |
|
|
|
677 |
dl |
1.1 |
private class DeqIterator implements Iterator<E> { |
678 |
jsr166 |
1.75 |
/** Index of element to be returned by subsequent call to next. */ |
679 |
|
|
int cursor; |
680 |
dl |
1.1 |
|
681 |
jsr166 |
1.75 |
/** Number of elements yet to be returned. */ |
682 |
|
|
int remaining = size; |
683 |
dl |
1.1 |
|
684 |
|
|
/** |
685 |
|
|
* Index of element returned by most recent call to next. |
686 |
|
|
* Reset to -1 if element is deleted by a call to remove. |
687 |
|
|
*/ |
688 |
jsr166 |
1.75 |
int lastRet = -1; |
689 |
dl |
1.1 |
|
690 |
jsr166 |
1.75 |
DeqIterator() { cursor = head; } |
691 |
|
|
|
692 |
jsr166 |
1.77 |
int advance(int i, int modulus) { |
693 |
|
|
return inc(i, modulus); |
694 |
dl |
1.1 |
} |
695 |
|
|
|
696 |
jsr166 |
1.75 |
void doRemove() { |
697 |
|
|
if (delete(lastRet)) |
698 |
|
|
// if left-shifted, undo advance in next() |
699 |
|
|
cursor = dec(cursor, elements.length); |
700 |
|
|
} |
701 |
|
|
|
702 |
|
|
public final boolean hasNext() { |
703 |
|
|
return remaining > 0; |
704 |
|
|
} |
705 |
|
|
|
706 |
|
|
public final E next() { |
707 |
|
|
if (remaining == 0) |
708 |
dl |
1.1 |
throw new NoSuchElementException(); |
709 |
jsr166 |
1.75 |
E e = checkedElementAt(elements, cursor); |
710 |
dl |
1.1 |
lastRet = cursor; |
711 |
jsr166 |
1.77 |
cursor = advance(cursor, elements.length); |
712 |
jsr166 |
1.75 |
remaining--; |
713 |
|
|
return e; |
714 |
dl |
1.1 |
} |
715 |
|
|
|
716 |
jsr166 |
1.75 |
public final void remove() { |
717 |
dl |
1.1 |
if (lastRet < 0) |
718 |
|
|
throw new IllegalStateException(); |
719 |
jsr166 |
1.75 |
doRemove(); |
720 |
dl |
1.1 |
lastRet = -1; |
721 |
|
|
} |
722 |
jsr166 |
1.68 |
|
723 |
jsr166 |
1.75 |
public final void forEachRemaining(Consumer<? super E> action) { |
724 |
jsr166 |
1.68 |
Objects.requireNonNull(action); |
725 |
jsr166 |
1.75 |
final Object[] elements = ArrayDeque.this.elements; |
726 |
|
|
final int capacity = elements.length; |
727 |
jsr166 |
1.77 |
int k = remaining; |
728 |
|
|
remaining = 0; |
729 |
|
|
for (int i = cursor; --k >= 0; i = advance(i, capacity)) |
730 |
|
|
action.accept(checkedElementAt(elements, i)); |
731 |
jsr166 |
1.68 |
} |
732 |
dl |
1.1 |
} |
733 |
|
|
|
734 |
jsr166 |
1.75 |
private class DescendingIterator extends DeqIterator { |
735 |
|
|
DescendingIterator() { cursor = tail(); } |
736 |
|
|
|
737 |
jsr166 |
1.77 |
@Override int advance(int i, int modulus) { |
738 |
|
|
return dec(i, modulus); |
739 |
jsr166 |
1.75 |
} |
740 |
|
|
|
741 |
|
|
@Override void doRemove() { |
742 |
|
|
if (!delete(lastRet)) |
743 |
|
|
// if right-shifted, undo advance in next |
744 |
|
|
cursor = inc(cursor, elements.length); |
745 |
|
|
} |
746 |
|
|
} |
747 |
|
|
|
748 |
jsr166 |
1.52 |
/** |
749 |
jsr166 |
1.75 |
* Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> |
750 |
|
|
* and <em>fail-fast</em> {@link Spliterator} over the elements in this |
751 |
|
|
* deque. |
752 |
|
|
* |
753 |
|
|
* <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, |
754 |
|
|
* {@link Spliterator#SUBSIZED}, {@link Spliterator#ORDERED}, and |
755 |
|
|
* {@link Spliterator#NONNULL}. Overriding implementations should document |
756 |
|
|
* the reporting of additional characteristic values. |
757 |
|
|
* |
758 |
|
|
* @return a {@code Spliterator} over the elements in this deque |
759 |
|
|
* @since 1.8 |
760 |
jsr166 |
1.52 |
*/ |
761 |
jsr166 |
1.75 |
public Spliterator<E> spliterator() { |
762 |
jsr166 |
1.76 |
return new ArrayDequeSpliterator(); |
763 |
jsr166 |
1.75 |
} |
764 |
|
|
|
765 |
|
|
final class ArrayDequeSpliterator implements Spliterator<E> { |
766 |
|
|
private int cursor; |
767 |
jsr166 |
1.76 |
private int remaining; // -1 until late-binding first use |
768 |
jsr166 |
1.75 |
|
769 |
jsr166 |
1.76 |
/** Constructs late-binding spliterator over all elements. */ |
770 |
|
|
ArrayDequeSpliterator() { |
771 |
|
|
this.remaining = -1; |
772 |
|
|
} |
773 |
|
|
|
774 |
|
|
/** Constructs spliterator over the given slice. */ |
775 |
jsr166 |
1.75 |
ArrayDequeSpliterator(int cursor, int count) { |
776 |
|
|
this.cursor = cursor; |
777 |
|
|
this.remaining = count; |
778 |
|
|
} |
779 |
|
|
|
780 |
jsr166 |
1.76 |
/** Ensures late-binding initialization; then returns remaining. */ |
781 |
|
|
private int remaining() { |
782 |
|
|
if (remaining < 0) { |
783 |
|
|
cursor = head; |
784 |
|
|
remaining = size; |
785 |
|
|
} |
786 |
|
|
return remaining; |
787 |
|
|
} |
788 |
|
|
|
789 |
jsr166 |
1.75 |
public ArrayDequeSpliterator trySplit() { |
790 |
jsr166 |
1.77 |
final int mid; |
791 |
|
|
if ((mid = remaining() >> 1) > 0) { |
792 |
jsr166 |
1.75 |
int oldCursor = cursor; |
793 |
jsr166 |
1.76 |
cursor = add(cursor, mid, elements.length); |
794 |
jsr166 |
1.75 |
remaining -= mid; |
795 |
|
|
return new ArrayDequeSpliterator(oldCursor, mid); |
796 |
|
|
} |
797 |
|
|
return null; |
798 |
|
|
} |
799 |
dl |
1.16 |
|
800 |
jsr166 |
1.75 |
public void forEachRemaining(Consumer<? super E> action) { |
801 |
|
|
Objects.requireNonNull(action); |
802 |
|
|
final Object[] elements = ArrayDeque.this.elements; |
803 |
|
|
final int capacity = elements.length; |
804 |
jsr166 |
1.77 |
int k = remaining(); |
805 |
|
|
remaining = 0; |
806 |
|
|
for (int i = cursor; --k >= 0; i = inc(i, capacity)) |
807 |
|
|
action.accept(checkedElementAt(elements, i)); |
808 |
dl |
1.16 |
} |
809 |
|
|
|
810 |
jsr166 |
1.75 |
public boolean tryAdvance(Consumer<? super E> action) { |
811 |
|
|
Objects.requireNonNull(action); |
812 |
jsr166 |
1.76 |
if (remaining() == 0) |
813 |
jsr166 |
1.75 |
return false; |
814 |
|
|
action.accept(checkedElementAt(elements, cursor)); |
815 |
|
|
cursor = inc(cursor, elements.length); |
816 |
|
|
remaining--; |
817 |
|
|
return true; |
818 |
|
|
} |
819 |
|
|
|
820 |
|
|
public long estimateSize() { |
821 |
jsr166 |
1.76 |
return remaining(); |
822 |
jsr166 |
1.75 |
} |
823 |
|
|
|
824 |
|
|
public int characteristics() { |
825 |
|
|
return Spliterator.NONNULL |
826 |
|
|
| Spliterator.ORDERED |
827 |
|
|
| Spliterator.SIZED |
828 |
|
|
| Spliterator.SUBSIZED; |
829 |
dl |
1.16 |
} |
830 |
jsr166 |
1.75 |
} |
831 |
dl |
1.16 |
|
832 |
jsr166 |
1.75 |
@Override |
833 |
|
|
public void forEach(Consumer<? super E> action) { |
834 |
|
|
// checkInvariants(); |
835 |
|
|
Objects.requireNonNull(action); |
836 |
|
|
final Object[] elements = this.elements; |
837 |
|
|
final int capacity = elements.length; |
838 |
|
|
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) |
839 |
|
|
action.accept(elementAt(i)); |
840 |
|
|
// checkInvariants(); |
841 |
|
|
} |
842 |
|
|
|
843 |
|
|
/** |
844 |
|
|
* Replaces each element of this deque with the result of applying the |
845 |
|
|
* operator to that element, as specified by {@link List#replaceAll}. |
846 |
|
|
* |
847 |
|
|
* @param operator the operator to apply to each element |
848 |
jsr166 |
1.80 |
* @since TBD |
849 |
jsr166 |
1.75 |
*/ |
850 |
jsr166 |
1.80 |
/* public */ void replaceAll(UnaryOperator<E> operator) { |
851 |
jsr166 |
1.75 |
Objects.requireNonNull(operator); |
852 |
|
|
final Object[] elements = this.elements; |
853 |
|
|
final int capacity = elements.length; |
854 |
|
|
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) |
855 |
|
|
elements[i] = operator.apply(elementAt(i)); |
856 |
|
|
// checkInvariants(); |
857 |
|
|
} |
858 |
|
|
|
859 |
|
|
/** |
860 |
|
|
* @throws NullPointerException {@inheritDoc} |
861 |
|
|
*/ |
862 |
|
|
@Override |
863 |
|
|
public boolean removeIf(Predicate<? super E> filter) { |
864 |
|
|
Objects.requireNonNull(filter); |
865 |
|
|
return bulkRemove(filter); |
866 |
|
|
} |
867 |
|
|
|
868 |
|
|
/** |
869 |
|
|
* @throws NullPointerException {@inheritDoc} |
870 |
|
|
*/ |
871 |
|
|
@Override |
872 |
|
|
public boolean removeAll(Collection<?> c) { |
873 |
|
|
Objects.requireNonNull(c); |
874 |
|
|
return bulkRemove(e -> c.contains(e)); |
875 |
|
|
} |
876 |
|
|
|
877 |
|
|
/** |
878 |
|
|
* @throws NullPointerException {@inheritDoc} |
879 |
|
|
*/ |
880 |
|
|
@Override |
881 |
|
|
public boolean retainAll(Collection<?> c) { |
882 |
|
|
Objects.requireNonNull(c); |
883 |
|
|
return bulkRemove(e -> !c.contains(e)); |
884 |
|
|
} |
885 |
|
|
|
886 |
|
|
/** Implementation of bulk remove methods. */ |
887 |
|
|
private boolean bulkRemove(Predicate<? super E> filter) { |
888 |
|
|
// checkInvariants(); |
889 |
|
|
final Object[] elements = this.elements; |
890 |
|
|
final int capacity = elements.length; |
891 |
|
|
int i = head, j = i, remaining = size, deleted = 0; |
892 |
|
|
try { |
893 |
|
|
for (; remaining > 0; remaining--, i = inc(i, capacity)) { |
894 |
|
|
@SuppressWarnings("unchecked") E e = (E) elements[i]; |
895 |
|
|
if (filter.test(e)) |
896 |
|
|
deleted++; |
897 |
|
|
else { |
898 |
|
|
if (j != i) |
899 |
|
|
elements[j] = e; |
900 |
|
|
j = inc(j, capacity); |
901 |
|
|
} |
902 |
jsr166 |
1.30 |
} |
903 |
jsr166 |
1.75 |
return deleted > 0; |
904 |
|
|
} catch (Throwable ex) { |
905 |
jsr166 |
1.78 |
if (deleted > 0) |
906 |
|
|
for (; remaining > 0; |
907 |
|
|
remaining--, i = inc(i, capacity), j = inc(j, capacity)) |
908 |
|
|
elements[j] = elements[i]; |
909 |
jsr166 |
1.75 |
throw ex; |
910 |
|
|
} finally { |
911 |
|
|
size -= deleted; |
912 |
|
|
for (; --deleted >= 0; j = inc(j, capacity)) |
913 |
|
|
elements[j] = null; |
914 |
|
|
// checkInvariants(); |
915 |
dl |
1.16 |
} |
916 |
|
|
} |
917 |
|
|
|
918 |
dl |
1.1 |
/** |
919 |
jsr166 |
1.40 |
* Returns {@code true} if this deque contains the specified element. |
920 |
|
|
* More formally, returns {@code true} if and only if this deque contains |
921 |
|
|
* at least one element {@code e} such that {@code o.equals(e)}. |
922 |
dl |
1.1 |
* |
923 |
|
|
* @param o object to be checked for containment in this deque |
924 |
jsr166 |
1.40 |
* @return {@code true} if this deque contains the specified element |
925 |
dl |
1.1 |
*/ |
926 |
|
|
public boolean contains(Object o) { |
927 |
jsr166 |
1.58 |
if (o != null) { |
928 |
jsr166 |
1.75 |
final Object[] elements = this.elements; |
929 |
|
|
final int capacity = elements.length; |
930 |
|
|
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) |
931 |
|
|
if (o.equals(elements[i])) |
932 |
jsr166 |
1.58 |
return true; |
933 |
dl |
1.1 |
} |
934 |
|
|
return false; |
935 |
|
|
} |
936 |
|
|
|
937 |
|
|
/** |
938 |
|
|
* Removes a single instance of the specified element from this deque. |
939 |
jsr166 |
1.9 |
* If the deque does not contain the element, it is unchanged. |
940 |
jsr166 |
1.40 |
* More formally, removes the first element {@code e} such that |
941 |
|
|
* {@code o.equals(e)} (if such an element exists). |
942 |
|
|
* Returns {@code true} if this deque contained the specified element |
943 |
jsr166 |
1.12 |
* (or equivalently, if this deque changed as a result of the call). |
944 |
jsr166 |
1.9 |
* |
945 |
jsr166 |
1.46 |
* <p>This method is equivalent to {@link #removeFirstOccurrence(Object)}. |
946 |
dl |
1.1 |
* |
947 |
jsr166 |
1.9 |
* @param o element to be removed from this deque, if present |
948 |
jsr166 |
1.40 |
* @return {@code true} if this deque contained the specified element |
949 |
dl |
1.1 |
*/ |
950 |
jsr166 |
1.9 |
public boolean remove(Object o) { |
951 |
|
|
return removeFirstOccurrence(o); |
952 |
dl |
1.1 |
} |
953 |
|
|
|
954 |
|
|
/** |
955 |
|
|
* Removes all of the elements from this deque. |
956 |
jsr166 |
1.7 |
* The deque will be empty after this call returns. |
957 |
dl |
1.1 |
*/ |
958 |
|
|
public void clear() { |
959 |
jsr166 |
1.75 |
final Object[] elements = this.elements; |
960 |
|
|
final int capacity = elements.length; |
961 |
|
|
final int h = this.head; |
962 |
|
|
final int s = size; |
963 |
|
|
if (capacity - h >= s) |
964 |
|
|
Arrays.fill(elements, h, h + s, null); |
965 |
|
|
else { |
966 |
|
|
Arrays.fill(elements, h, capacity, null); |
967 |
|
|
Arrays.fill(elements, 0, s - capacity + h, null); |
968 |
dl |
1.1 |
} |
969 |
jsr166 |
1.75 |
size = head = 0; |
970 |
|
|
// checkInvariants(); |
971 |
dl |
1.1 |
} |
972 |
|
|
|
973 |
|
|
/** |
974 |
dl |
1.5 |
* Returns an array containing all of the elements in this deque |
975 |
jsr166 |
1.10 |
* in proper sequence (from first to last element). |
976 |
dl |
1.1 |
* |
977 |
jsr166 |
1.10 |
* <p>The returned array will be "safe" in that no references to it are |
978 |
|
|
* maintained by this deque. (In other words, this method must allocate |
979 |
|
|
* a new array). The caller is thus free to modify the returned array. |
980 |
jsr166 |
1.13 |
* |
981 |
jsr166 |
1.11 |
* <p>This method acts as bridge between array-based and collection-based |
982 |
|
|
* APIs. |
983 |
|
|
* |
984 |
dl |
1.5 |
* @return an array containing all of the elements in this deque |
985 |
dl |
1.1 |
*/ |
986 |
|
|
public Object[] toArray() { |
987 |
jsr166 |
1.50 |
final int head = this.head; |
988 |
jsr166 |
1.75 |
final int firstLeg; |
989 |
|
|
Object[] a = Arrays.copyOfRange(elements, head, head + size); |
990 |
|
|
if ((firstLeg = elements.length - head) < size) |
991 |
|
|
System.arraycopy(elements, 0, a, firstLeg, size - firstLeg); |
992 |
jsr166 |
1.50 |
return a; |
993 |
dl |
1.1 |
} |
994 |
|
|
|
995 |
|
|
/** |
996 |
jsr166 |
1.10 |
* Returns an array containing all of the elements in this deque in |
997 |
|
|
* proper sequence (from first to last element); the runtime type of the |
998 |
|
|
* returned array is that of the specified array. If the deque fits in |
999 |
|
|
* the specified array, it is returned therein. Otherwise, a new array |
1000 |
|
|
* is allocated with the runtime type of the specified array and the |
1001 |
|
|
* size of this deque. |
1002 |
|
|
* |
1003 |
|
|
* <p>If this deque fits in the specified array with room to spare |
1004 |
|
|
* (i.e., the array has more elements than this deque), the element in |
1005 |
|
|
* the array immediately following the end of the deque is set to |
1006 |
jsr166 |
1.40 |
* {@code null}. |
1007 |
jsr166 |
1.10 |
* |
1008 |
|
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
1009 |
|
|
* array-based and collection-based APIs. Further, this method allows |
1010 |
|
|
* precise control over the runtime type of the output array, and may, |
1011 |
|
|
* under certain circumstances, be used to save allocation costs. |
1012 |
|
|
* |
1013 |
jsr166 |
1.40 |
* <p>Suppose {@code x} is a deque known to contain only strings. |
1014 |
jsr166 |
1.10 |
* The following code can be used to dump the deque into a newly |
1015 |
jsr166 |
1.40 |
* allocated array of {@code String}: |
1016 |
jsr166 |
1.10 |
* |
1017 |
jsr166 |
1.63 |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
1018 |
jsr166 |
1.10 |
* |
1019 |
jsr166 |
1.40 |
* Note that {@code toArray(new Object[0])} is identical in function to |
1020 |
|
|
* {@code toArray()}. |
1021 |
dl |
1.1 |
* |
1022 |
|
|
* @param a the array into which the elements of the deque are to |
1023 |
jsr166 |
1.9 |
* be stored, if it is big enough; otherwise, a new array of the |
1024 |
|
|
* same runtime type is allocated for this purpose |
1025 |
jsr166 |
1.10 |
* @return an array containing all of the elements in this deque |
1026 |
|
|
* @throws ArrayStoreException if the runtime type of the specified array |
1027 |
|
|
* is not a supertype of the runtime type of every element in |
1028 |
|
|
* this deque |
1029 |
|
|
* @throws NullPointerException if the specified array is null |
1030 |
dl |
1.1 |
*/ |
1031 |
jsr166 |
1.34 |
@SuppressWarnings("unchecked") |
1032 |
dl |
1.1 |
public <T> T[] toArray(T[] a) { |
1033 |
jsr166 |
1.75 |
final Object[] elements = this.elements; |
1034 |
jsr166 |
1.50 |
final int head = this.head; |
1035 |
jsr166 |
1.75 |
final int firstLeg; |
1036 |
|
|
boolean wrap = (firstLeg = elements.length - head) < size; |
1037 |
|
|
if (size > a.length) { |
1038 |
jsr166 |
1.50 |
a = (T[]) Arrays.copyOfRange(elements, head, head + size, |
1039 |
|
|
a.getClass()); |
1040 |
|
|
} else { |
1041 |
jsr166 |
1.75 |
System.arraycopy(elements, head, a, 0, wrap ? firstLeg : size); |
1042 |
|
|
if (size < a.length) |
1043 |
jsr166 |
1.50 |
a[size] = null; |
1044 |
|
|
} |
1045 |
|
|
if (wrap) |
1046 |
jsr166 |
1.75 |
System.arraycopy(elements, 0, a, firstLeg, size - firstLeg); |
1047 |
dl |
1.1 |
return a; |
1048 |
|
|
} |
1049 |
|
|
|
1050 |
|
|
// *** Object methods *** |
1051 |
|
|
|
1052 |
|
|
/** |
1053 |
|
|
* Returns a copy of this deque. |
1054 |
|
|
* |
1055 |
|
|
* @return a copy of this deque |
1056 |
|
|
*/ |
1057 |
|
|
public ArrayDeque<E> clone() { |
1058 |
dl |
1.5 |
try { |
1059 |
jsr166 |
1.34 |
@SuppressWarnings("unchecked") |
1060 |
dl |
1.1 |
ArrayDeque<E> result = (ArrayDeque<E>) super.clone(); |
1061 |
jsr166 |
1.28 |
result.elements = Arrays.copyOf(elements, elements.length); |
1062 |
dl |
1.1 |
return result; |
1063 |
dl |
1.5 |
} catch (CloneNotSupportedException e) { |
1064 |
dl |
1.1 |
throw new AssertionError(); |
1065 |
|
|
} |
1066 |
|
|
} |
1067 |
|
|
|
1068 |
|
|
private static final long serialVersionUID = 2340985798034038923L; |
1069 |
|
|
|
1070 |
|
|
/** |
1071 |
jsr166 |
1.38 |
* Saves this deque to a stream (that is, serializes it). |
1072 |
dl |
1.1 |
* |
1073 |
jsr166 |
1.56 |
* @param s the stream |
1074 |
jsr166 |
1.57 |
* @throws java.io.IOException if an I/O error occurs |
1075 |
jsr166 |
1.40 |
* @serialData The current size ({@code int}) of the deque, |
1076 |
dl |
1.1 |
* followed by all of its elements (each an object reference) in |
1077 |
|
|
* first-to-last order. |
1078 |
|
|
*/ |
1079 |
jsr166 |
1.32 |
private void writeObject(java.io.ObjectOutputStream s) |
1080 |
|
|
throws java.io.IOException { |
1081 |
dl |
1.1 |
s.defaultWriteObject(); |
1082 |
|
|
|
1083 |
|
|
// Write out size |
1084 |
jsr166 |
1.75 |
s.writeInt(size); |
1085 |
dl |
1.1 |
|
1086 |
|
|
// Write out elements in order. |
1087 |
jsr166 |
1.75 |
final Object[] elements = this.elements; |
1088 |
|
|
final int capacity = elements.length; |
1089 |
|
|
for (int k = size, i = head; --k >= 0; i = inc(i, capacity)) |
1090 |
dl |
1.1 |
s.writeObject(elements[i]); |
1091 |
|
|
} |
1092 |
|
|
|
1093 |
|
|
/** |
1094 |
jsr166 |
1.38 |
* Reconstitutes this deque from a stream (that is, deserializes it). |
1095 |
jsr166 |
1.56 |
* @param s the stream |
1096 |
jsr166 |
1.57 |
* @throws ClassNotFoundException if the class of a serialized object |
1097 |
|
|
* could not be found |
1098 |
|
|
* @throws java.io.IOException if an I/O error occurs |
1099 |
dl |
1.1 |
*/ |
1100 |
jsr166 |
1.32 |
private void readObject(java.io.ObjectInputStream s) |
1101 |
|
|
throws java.io.IOException, ClassNotFoundException { |
1102 |
dl |
1.1 |
s.defaultReadObject(); |
1103 |
|
|
|
1104 |
|
|
// Read in size and allocate array |
1105 |
jsr166 |
1.75 |
elements = new Object[size = s.readInt()]; |
1106 |
dl |
1.1 |
|
1107 |
|
|
// Read in all elements in the proper order. |
1108 |
|
|
for (int i = 0; i < size; i++) |
1109 |
jsr166 |
1.34 |
elements[i] = s.readObject(); |
1110 |
dl |
1.1 |
} |
1111 |
dl |
1.41 |
|
1112 |
jsr166 |
1.75 |
/** debugging */ |
1113 |
|
|
private void checkInvariants() { |
1114 |
|
|
try { |
1115 |
|
|
int capacity = elements.length; |
1116 |
|
|
assert size >= 0 && size <= capacity; |
1117 |
|
|
assert head >= 0 && ((capacity == 0 && head == 0 && size == 0) |
1118 |
|
|
|| head < capacity); |
1119 |
|
|
assert size == 0 |
1120 |
|
|
|| (elements[head] != null && elements[tail()] != null); |
1121 |
|
|
assert size == capacity |
1122 |
|
|
|| (elements[dec(head, capacity)] == null |
1123 |
|
|
&& elements[inc(tail(), capacity)] == null); |
1124 |
|
|
} catch (Throwable t) { |
1125 |
|
|
System.err.printf("head=%d size=%d capacity=%d%n", |
1126 |
|
|
head, size, elements.length); |
1127 |
|
|
System.err.printf("elements=%s%n", |
1128 |
|
|
Arrays.toString(elements)); |
1129 |
|
|
throw t; |
1130 |
dl |
1.41 |
} |
1131 |
|
|
} |
1132 |
|
|
|
1133 |
dl |
1.1 |
} |