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1.38 |
/* |
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dl |
1.52 |
* @(#)PriorityQueue.java 1.8 05/08/27 |
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1.38 |
* |
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1.52 |
* Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
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1.38 |
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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*/ |
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package java.util; |
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dl |
1.52 |
import java.util.*; // for javadoc (till 6280605 is fixed) |
10 |
tim |
1.1 |
|
11 |
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/** |
12 |
dl |
1.41 |
* An unbounded priority {@linkplain Queue queue} based on a priority |
13 |
dl |
1.52 |
* heap. The elements of the priority queue are ordered according to |
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* their {@linkplain Comparable natural ordering}, or by a {@link |
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* Comparator} provided at queue construction time, depending on which |
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* constructor is used. A priority queue does not permit |
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* <tt>null</tt> elements. A priority queue relying on natural |
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* ordering also does not permit insertion of non-comparable objects |
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* (doing so may result in <tt>ClassCastException</tt>). |
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dl |
1.40 |
* |
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1.41 |
* <p>The <em>head</em> of this queue is the <em>least</em> element |
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* with respect to the specified ordering. If multiple elements are |
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* tied for least value, the head is one of those elements -- ties are |
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dl |
1.42 |
* broken arbitrarily. The queue retrieval operations <tt>poll</tt>, |
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* <tt>remove</tt>, <tt>peek</tt>, and <tt>element</tt> access the |
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* element at the head of the queue. |
27 |
tim |
1.14 |
* |
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dl |
1.41 |
* <p>A priority queue is unbounded, but has an internal |
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* <i>capacity</i> governing the size of an array used to store the |
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dl |
1.40 |
* elements on the queue. It is always at least as large as the queue |
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* size. As elements are added to a priority queue, its capacity |
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* grows automatically. The details of the growth policy are not |
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* specified. |
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tim |
1.2 |
* |
35 |
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1.50 |
* <p>This class and its iterator implement all of the |
36 |
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* <em>optional</em> methods of the {@link Collection} and {@link |
37 |
dl |
1.52 |
* Iterator} interfaces. The Iterator provided in method {@link |
38 |
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* #iterator()} is <em>not</em> guaranteed to traverse the elements of |
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* the priority queue in any particular order. If you need ordered |
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* traversal, consider using <tt>Arrays.sort(pq.toArray())</tt>. |
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dl |
1.29 |
* |
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* <p> <strong>Note that this implementation is not synchronized.</strong> |
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* Multiple threads should not access a <tt>PriorityQueue</tt> |
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* instance concurrently if any of the threads modifies the list |
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* structurally. Instead, use the thread-safe {@link |
46 |
dholmes |
1.34 |
* java.util.concurrent.PriorityBlockingQueue} class. |
47 |
dl |
1.29 |
* |
48 |
dholmes |
1.11 |
* <p>Implementation note: this implementation provides O(log(n)) time |
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* for the insertion methods (<tt>offer</tt>, <tt>poll</tt>, |
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* <tt>remove()</tt> and <tt>add</tt>) methods; linear time for the |
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* <tt>remove(Object)</tt> and <tt>contains(Object)</tt> methods; and |
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* constant time for the retrieval methods (<tt>peek</tt>, |
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* <tt>element</tt>, and <tt>size</tt>). |
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1.2 |
* |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* Java Collections Framework</a>. |
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1.7 |
* @since 1.5 |
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1.52 |
* @version 1.8, 08/27/05 |
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1.7 |
* @author Josh Bloch |
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1.45 |
* @param <E> the type of elements held in this collection |
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1.2 |
*/ |
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public class PriorityQueue<E> extends AbstractQueue<E> |
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1.47 |
implements java.io.Serializable { |
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dholmes |
1.11 |
|
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1.31 |
private static final long serialVersionUID = -7720805057305804111L; |
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1.30 |
|
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1.2 |
private static final int DEFAULT_INITIAL_CAPACITY = 11; |
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1.1 |
|
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tim |
1.2 |
/** |
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* Priority queue represented as a balanced binary heap: the two children |
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* of queue[n] are queue[2*n] and queue[2*n + 1]. The priority queue is |
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* ordered by comparator, or by the elements' natural ordering, if |
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brian |
1.6 |
* comparator is null: For each node n in the heap and each descendant d |
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* of n, n <= d. |
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tim |
1.2 |
* |
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brian |
1.6 |
* The element with the lowest value is in queue[1], assuming the queue is |
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* nonempty. (A one-based array is used in preference to the traditional |
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* zero-based array to simplify parent and child calculations.) |
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1.2 |
* |
81 |
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* queue.length must be >= 2, even if size == 0. |
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*/ |
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tim |
1.16 |
private transient Object[] queue; |
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tim |
1.1 |
|
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tim |
1.2 |
/** |
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* The number of elements in the priority queue. |
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*/ |
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private int size = 0; |
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tim |
1.1 |
|
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tim |
1.2 |
/** |
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* The comparator, or null if priority queue uses elements' |
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* natural ordering. |
93 |
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*/ |
94 |
tim |
1.16 |
private final Comparator<? super E> comparator; |
95 |
tim |
1.2 |
|
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/** |
97 |
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* The number of times this priority queue has been |
98 |
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* <i>structurally modified</i>. See AbstractList for gory details. |
99 |
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*/ |
100 |
dl |
1.5 |
private transient int modCount = 0; |
101 |
tim |
1.2 |
|
102 |
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/** |
103 |
dl |
1.52 |
* Creates a <tt>PriorityQueue</tt> with the default initial |
104 |
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* capacity (11) that orders its elements according to their |
105 |
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* {@linkplain Comparable natural ordering}. |
106 |
tim |
1.2 |
*/ |
107 |
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public PriorityQueue() { |
108 |
dholmes |
1.11 |
this(DEFAULT_INITIAL_CAPACITY, null); |
109 |
tim |
1.1 |
} |
110 |
tim |
1.2 |
|
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/** |
112 |
dl |
1.52 |
* Creates a <tt>PriorityQueue</tt> with the specified initial |
113 |
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* capacity that orders its elements according to their |
114 |
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* {@linkplain Comparable natural ordering}. |
115 |
tim |
1.2 |
* |
116 |
dl |
1.52 |
* @param initialCapacity the initial capacity for this priority queue |
117 |
dholmes |
1.23 |
* @throws IllegalArgumentException if <tt>initialCapacity</tt> is less |
118 |
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* than 1 |
119 |
tim |
1.2 |
*/ |
120 |
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public PriorityQueue(int initialCapacity) { |
121 |
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this(initialCapacity, null); |
122 |
tim |
1.1 |
} |
123 |
tim |
1.2 |
|
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/** |
125 |
dholmes |
1.21 |
* Creates a <tt>PriorityQueue</tt> with the specified initial capacity |
126 |
tim |
1.2 |
* that orders its elements according to the specified comparator. |
127 |
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* |
128 |
dl |
1.52 |
* @param initialCapacity the initial capacity for this priority queue |
129 |
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* @param comparator the comparator that will be used to order |
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* this priority queue. If <tt>null</tt>, the <i>natural |
131 |
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* ordering</i> of the elements will be used. |
132 |
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* @throws IllegalArgumentException if <tt>initialCapacity</tt> is |
133 |
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* less than 1 |
134 |
tim |
1.2 |
*/ |
135 |
dl |
1.52 |
public PriorityQueue(int initialCapacity, |
136 |
dholmes |
1.23 |
Comparator<? super E> comparator) { |
137 |
tim |
1.2 |
if (initialCapacity < 1) |
138 |
dholmes |
1.15 |
throw new IllegalArgumentException(); |
139 |
tim |
1.16 |
this.queue = new Object[initialCapacity + 1]; |
140 |
tim |
1.2 |
this.comparator = comparator; |
141 |
tim |
1.1 |
} |
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143 |
tim |
1.2 |
/** |
144 |
dl |
1.22 |
* Common code to initialize underlying queue array across |
145 |
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* constructors below. |
146 |
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*/ |
147 |
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private void initializeArray(Collection<? extends E> c) { |
148 |
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int sz = c.size(); |
149 |
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int initialCapacity = (int)Math.min((sz * 110L) / 100, |
150 |
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Integer.MAX_VALUE - 1); |
151 |
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if (initialCapacity < 1) |
152 |
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initialCapacity = 1; |
153 |
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154 |
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this.queue = new Object[initialCapacity + 1]; |
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} |
156 |
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157 |
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/** |
158 |
dl |
1.52 |
* Initially fill elements of the queue array under the |
159 |
dl |
1.22 |
* knowledge that it is sorted or is another PQ, in which |
160 |
dl |
1.36 |
* case we can just place the elements in the order presented. |
161 |
dl |
1.22 |
*/ |
162 |
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private void fillFromSorted(Collection<? extends E> c) { |
163 |
dl |
1.52 |
for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) { |
164 |
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int k = ++size; |
165 |
jsr166 |
1.53 |
if (k >= queue.length) |
166 |
dl |
1.52 |
grow(k); |
167 |
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queue[k] = i.next(); |
168 |
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} |
169 |
dl |
1.22 |
} |
170 |
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171 |
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/** |
172 |
dl |
1.36 |
* Initially fill elements of the queue array that is not to our knowledge |
173 |
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* sorted, so we must rearrange the elements to guarantee the heap |
174 |
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* invariant. |
175 |
dl |
1.22 |
*/ |
176 |
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private void fillFromUnsorted(Collection<? extends E> c) { |
177 |
dl |
1.52 |
for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) { |
178 |
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int k = ++size; |
179 |
jsr166 |
1.53 |
if (k >= queue.length) |
180 |
dl |
1.52 |
grow(k); |
181 |
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queue[k] = i.next(); |
182 |
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} |
183 |
dl |
1.36 |
heapify(); |
184 |
dl |
1.22 |
} |
185 |
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186 |
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/** |
187 |
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* Creates a <tt>PriorityQueue</tt> containing the elements in the |
188 |
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* specified collection. The priority queue has an initial |
189 |
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* capacity of 110% of the size of the specified collection or 1 |
190 |
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* if the collection is empty. If the specified collection is an |
191 |
tim |
1.25 |
* instance of a {@link java.util.SortedSet} or is another |
192 |
dl |
1.52 |
* <tt>PriorityQueue</tt>, the priority queue will be ordered |
193 |
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* according to the same ordering. Otherwise, this priority queue |
194 |
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* will be ordered according to the natural ordering of its elements. |
195 |
tim |
1.2 |
* |
196 |
dl |
1.52 |
* @param c the collection whose elements are to be placed |
197 |
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* into this priority queue |
198 |
tim |
1.2 |
* @throws ClassCastException if elements of the specified collection |
199 |
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* cannot be compared to one another according to the priority |
200 |
dl |
1.52 |
* queue's ordering |
201 |
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* @throws NullPointerException if the specified collection or any |
202 |
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* of its elements are null |
203 |
tim |
1.2 |
*/ |
204 |
tim |
1.16 |
public PriorityQueue(Collection<? extends E> c) { |
205 |
dl |
1.22 |
initializeArray(c); |
206 |
dl |
1.27 |
if (c instanceof SortedSet) { |
207 |
dl |
1.46 |
SortedSet<? extends E> s = (SortedSet<? extends E>)c; |
208 |
dl |
1.22 |
comparator = (Comparator<? super E>)s.comparator(); |
209 |
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fillFromSorted(s); |
210 |
dl |
1.27 |
} else if (c instanceof PriorityQueue) { |
211 |
dl |
1.22 |
PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c; |
212 |
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comparator = (Comparator<? super E>)s.comparator(); |
213 |
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fillFromSorted(s); |
214 |
tim |
1.26 |
} else { |
215 |
tim |
1.2 |
comparator = null; |
216 |
dl |
1.22 |
fillFromUnsorted(c); |
217 |
tim |
1.2 |
} |
218 |
dl |
1.22 |
} |
219 |
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220 |
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/** |
221 |
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* Creates a <tt>PriorityQueue</tt> containing the elements in the |
222 |
dl |
1.52 |
* specified priority queue. The priority queue has an initial |
223 |
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* capacity of 110% of the size of the specified priority queue or |
224 |
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* 1 if the priority queue is empty. This priority queue will be |
225 |
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* ordered according to the same ordering as the given priority |
226 |
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* queue. |
227 |
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* |
228 |
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* @param c the priority queue whose elements are to be placed |
229 |
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* into this priority queue |
230 |
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* @throws ClassCastException if elements of <tt>c</tt> cannot be |
231 |
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* compared to one another according to <tt>c</tt>'s |
232 |
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* ordering |
233 |
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* @throws NullPointerException if the specified priority queue or any |
234 |
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* of its elements are null |
235 |
dl |
1.22 |
*/ |
236 |
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public PriorityQueue(PriorityQueue<? extends E> c) { |
237 |
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initializeArray(c); |
238 |
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comparator = (Comparator<? super E>)c.comparator(); |
239 |
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fillFromSorted(c); |
240 |
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} |
241 |
dholmes |
1.18 |
|
242 |
dl |
1.22 |
/** |
243 |
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* Creates a <tt>PriorityQueue</tt> containing the elements in the |
244 |
dl |
1.52 |
* specified sorted set. The priority queue has an initial |
245 |
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* capacity of 110% of the size of the specified sorted set or 1 |
246 |
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* if the sorted set is empty. This priority queue will be ordered |
247 |
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* according to the same ordering as the given sorted set. |
248 |
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* |
249 |
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* @param c the sorted set whose elements are to be placed |
250 |
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* into this priority queue. |
251 |
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* @throws ClassCastException if elements of the specified sorted |
252 |
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* set cannot be compared to one another according to the |
253 |
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* sorted set's ordering |
254 |
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* @throws NullPointerException if the specified sorted set or any |
255 |
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* of its elements are null |
256 |
dl |
1.22 |
*/ |
257 |
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public PriorityQueue(SortedSet<? extends E> c) { |
258 |
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initializeArray(c); |
259 |
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comparator = (Comparator<? super E>)c.comparator(); |
260 |
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fillFromSorted(c); |
261 |
tim |
1.1 |
} |
262 |
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263 |
dl |
1.22 |
/** |
264 |
dl |
1.52 |
* Resize array, if necessary, to be able to hold given index. |
265 |
dl |
1.22 |
*/ |
266 |
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private void grow(int index) { |
267 |
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int newlen = queue.length; |
268 |
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if (index < newlen) // don't need to grow |
269 |
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return; |
270 |
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if (index == Integer.MAX_VALUE) |
271 |
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throw new OutOfMemoryError(); |
272 |
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while (newlen <= index) { |
273 |
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if (newlen >= Integer.MAX_VALUE / 2) // avoid overflow |
274 |
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newlen = Integer.MAX_VALUE; |
275 |
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else |
276 |
jsr166 |
1.54 |
newlen <<= 1; |
277 |
dl |
1.22 |
} |
278 |
dl |
1.52 |
queue = Arrays.copyOf(queue, newlen); |
279 |
dl |
1.22 |
} |
280 |
dl |
1.36 |
|
281 |
tim |
1.2 |
/** |
282 |
dl |
1.42 |
* Inserts the specified element into this priority queue. |
283 |
tim |
1.2 |
* |
284 |
dl |
1.52 |
* @return <tt>true</tt> (as specified by {@link Collection#add}) |
285 |
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* @throws ClassCastException if the specified element cannot be |
286 |
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* compared with elements currently in this priority queue |
287 |
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* according to the priority queue's ordering |
288 |
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* @throws NullPointerException if the specified element is null |
289 |
tim |
1.2 |
*/ |
290 |
dl |
1.52 |
public boolean add(E e) { |
291 |
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return offer(e); |
292 |
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} |
293 |
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|
294 |
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/** |
295 |
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* Inserts the specified element into this priority queue. |
296 |
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* |
297 |
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* @return <tt>true</tt> (as specified by {@link Queue#offer}) |
298 |
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* @throws ClassCastException if the specified element cannot be |
299 |
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* compared with elements currently in this priority queue |
300 |
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* according to the priority queue's ordering |
301 |
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* @throws NullPointerException if the specified element is null |
302 |
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*/ |
303 |
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public boolean offer(E e) { |
304 |
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if (e == null) |
305 |
dholmes |
1.11 |
throw new NullPointerException(); |
306 |
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modCount++; |
307 |
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++size; |
308 |
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|
309 |
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// Grow backing store if necessary |
310 |
dl |
1.52 |
if (size >= queue.length) |
311 |
dl |
1.22 |
grow(size); |
312 |
dholmes |
1.11 |
|
313 |
dl |
1.52 |
queue[size] = e; |
314 |
dholmes |
1.11 |
fixUp(size); |
315 |
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return true; |
316 |
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} |
317 |
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|
318 |
dl |
1.40 |
public E peek() { |
319 |
tim |
1.2 |
if (size == 0) |
320 |
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return null; |
321 |
tim |
1.16 |
return (E) queue[1]; |
322 |
tim |
1.1 |
} |
323 |
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|
324 |
dl |
1.52 |
private int indexOf(Object o) { |
325 |
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if (o == null) |
326 |
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return -1; |
327 |
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for (int i = 1; i <= size; i++) |
328 |
|
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if (o.equals(queue[i])) |
329 |
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return i; |
330 |
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return -1; |
331 |
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} |
332 |
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|
333 |
|
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/** |
334 |
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* Removes a single instance of the specified element from this queue, |
335 |
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* if it is present. More formally, removes an element <tt>e</tt> such |
336 |
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* that <tt>o.equals(e)</tt>, if this queue contains one or more such |
337 |
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* elements. Returns true if this queue contained the specified element |
338 |
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* (or equivalently, if this queue changed as a result of the call). |
339 |
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* |
340 |
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* @param o element to be removed from this queue, if present |
341 |
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* @return <tt>true</tt> if this queue changed as a result of the call |
342 |
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*/ |
343 |
|
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public boolean remove(Object o) { |
344 |
|
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int i = indexOf(o); |
345 |
|
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if (i == -1) |
346 |
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return false; |
347 |
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else { |
348 |
|
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removeAt(i); |
349 |
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return true; |
350 |
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} |
351 |
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} |
352 |
dholmes |
1.11 |
|
353 |
|
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/** |
354 |
dl |
1.52 |
* Returns <tt>true</tt> if this queue contains the specified element. |
355 |
|
|
* More formally, returns <tt>true</tt> if and only if this queue contains |
356 |
|
|
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. |
357 |
dholmes |
1.23 |
* |
358 |
dl |
1.52 |
* @param o object to be checked for containment in this queue |
359 |
|
|
* @return <tt>true</tt> if this queue contains the specified element |
360 |
dholmes |
1.11 |
*/ |
361 |
dl |
1.52 |
public boolean contains(Object o) { |
362 |
|
|
return indexOf(o) != -1; |
363 |
tim |
1.14 |
} |
364 |
dholmes |
1.11 |
|
365 |
dl |
1.49 |
/** |
366 |
dl |
1.52 |
* Returns an array containing all of the elements in this queue, |
367 |
|
|
* The elements are in no particular order. |
368 |
|
|
* |
369 |
|
|
* <p>The returned array will be "safe" in that no references to it are |
370 |
|
|
* maintained by this list. (In other words, this method must allocate |
371 |
|
|
* a new array). The caller is thus free to modify the returned array. |
372 |
|
|
* |
373 |
|
|
* @return an array containing all of the elements in this queue. |
374 |
dl |
1.49 |
*/ |
375 |
dl |
1.52 |
public Object[] toArray() { |
376 |
|
|
return Arrays.copyOfRange(queue, 1, size+1); |
377 |
|
|
} |
378 |
tim |
1.2 |
|
379 |
dl |
1.52 |
/** |
380 |
|
|
* Returns an array containing all of the elements in this queue. |
381 |
|
|
* The elements are in no particular order. The runtime type of |
382 |
|
|
* the returned array is that of the specified array. If the queue |
383 |
|
|
* fits in the specified array, it is returned therein. |
384 |
|
|
* Otherwise, a new array is allocated with the runtime type of |
385 |
|
|
* the specified array and the size of this queue. |
386 |
|
|
* |
387 |
|
|
* <p>If the queue fits in the specified array with room to spare |
388 |
|
|
* (i.e., the array has more elements than the queue), the element in |
389 |
|
|
* the array immediately following the end of the collection is set to |
390 |
|
|
* <tt>null</tt>. (This is useful in determining the length of the |
391 |
|
|
* queue <i>only</i> if the caller knows that the queue does not contain |
392 |
|
|
* any null elements.) |
393 |
|
|
* |
394 |
|
|
* @param a the array into which the elements of the queue are to |
395 |
|
|
* be stored, if it is big enough; otherwise, a new array of the |
396 |
|
|
* same runtime type is allocated for this purpose. |
397 |
|
|
* @return an array containing the elements of the queue |
398 |
|
|
* @throws ArrayStoreException if the runtime type of the specified array |
399 |
|
|
* is not a supertype of the runtime type of every element in |
400 |
|
|
* this queue |
401 |
|
|
* @throws NullPointerException if the specified array is null |
402 |
|
|
*/ |
403 |
|
|
public <T> T[] toArray(T[] a) { |
404 |
|
|
if (a.length < size) |
405 |
|
|
// Make a new array of a's runtime type, but my contents: |
406 |
|
|
return (T[]) Arrays.copyOfRange(queue, 1, size+1, a.getClass()); |
407 |
|
|
System.arraycopy(queue, 1, a, 0, size); |
408 |
|
|
if (a.length > size) |
409 |
|
|
a[size] = null; |
410 |
|
|
return a; |
411 |
tim |
1.1 |
} |
412 |
tim |
1.2 |
|
413 |
dholmes |
1.23 |
/** |
414 |
|
|
* Returns an iterator over the elements in this queue. The iterator |
415 |
|
|
* does not return the elements in any particular order. |
416 |
|
|
* |
417 |
dl |
1.52 |
* @return an iterator over the elements in this queue |
418 |
dholmes |
1.23 |
*/ |
419 |
tim |
1.2 |
public Iterator<E> iterator() { |
420 |
dl |
1.7 |
return new Itr(); |
421 |
tim |
1.2 |
} |
422 |
|
|
|
423 |
|
|
private class Itr implements Iterator<E> { |
424 |
dl |
1.35 |
|
425 |
dl |
1.7 |
/** |
426 |
|
|
* Index (into queue array) of element to be returned by |
427 |
tim |
1.2 |
* subsequent call to next. |
428 |
dl |
1.7 |
*/ |
429 |
|
|
private int cursor = 1; |
430 |
tim |
1.2 |
|
431 |
dl |
1.7 |
/** |
432 |
dl |
1.36 |
* Index of element returned by most recent call to next, |
433 |
|
|
* unless that element came from the forgetMeNot list. |
434 |
|
|
* Reset to 0 if element is deleted by a call to remove. |
435 |
dl |
1.7 |
*/ |
436 |
|
|
private int lastRet = 0; |
437 |
|
|
|
438 |
|
|
/** |
439 |
|
|
* The modCount value that the iterator believes that the backing |
440 |
|
|
* List should have. If this expectation is violated, the iterator |
441 |
|
|
* has detected concurrent modification. |
442 |
|
|
*/ |
443 |
|
|
private int expectedModCount = modCount; |
444 |
tim |
1.2 |
|
445 |
dl |
1.36 |
/** |
446 |
|
|
* A list of elements that were moved from the unvisited portion of |
447 |
|
|
* the heap into the visited portion as a result of "unlucky" element |
448 |
|
|
* removals during the iteration. (Unlucky element removals are those |
449 |
|
|
* that require a fixup instead of a fixdown.) We must visit all of |
450 |
|
|
* the elements in this list to complete the iteration. We do this |
451 |
|
|
* after we've completed the "normal" iteration. |
452 |
|
|
* |
453 |
|
|
* We expect that most iterations, even those involving removals, |
454 |
|
|
* will not use need to store elements in this field. |
455 |
|
|
*/ |
456 |
|
|
private ArrayList<E> forgetMeNot = null; |
457 |
|
|
|
458 |
|
|
/** |
459 |
|
|
* Element returned by the most recent call to next iff that |
460 |
|
|
* element was drawn from the forgetMeNot list. |
461 |
|
|
*/ |
462 |
|
|
private Object lastRetElt = null; |
463 |
dl |
1.35 |
|
464 |
dl |
1.7 |
public boolean hasNext() { |
465 |
dl |
1.36 |
return cursor <= size || forgetMeNot != null; |
466 |
dl |
1.7 |
} |
467 |
|
|
|
468 |
|
|
public E next() { |
469 |
tim |
1.2 |
checkForComodification(); |
470 |
dl |
1.36 |
E result; |
471 |
|
|
if (cursor <= size) { |
472 |
|
|
result = (E) queue[cursor]; |
473 |
|
|
lastRet = cursor++; |
474 |
|
|
} |
475 |
|
|
else if (forgetMeNot == null) |
476 |
dl |
1.7 |
throw new NoSuchElementException(); |
477 |
dl |
1.36 |
else { |
478 |
|
|
int remaining = forgetMeNot.size(); |
479 |
|
|
result = forgetMeNot.remove(remaining - 1); |
480 |
dl |
1.52 |
if (remaining == 1) |
481 |
dl |
1.36 |
forgetMeNot = null; |
482 |
|
|
lastRet = 0; |
483 |
|
|
lastRetElt = result; |
484 |
|
|
} |
485 |
tim |
1.2 |
return result; |
486 |
dl |
1.7 |
} |
487 |
tim |
1.2 |
|
488 |
dl |
1.7 |
public void remove() { |
489 |
tim |
1.2 |
checkForComodification(); |
490 |
|
|
|
491 |
dl |
1.36 |
if (lastRet != 0) { |
492 |
|
|
E moved = PriorityQueue.this.removeAt(lastRet); |
493 |
|
|
lastRet = 0; |
494 |
|
|
if (moved == null) { |
495 |
|
|
cursor--; |
496 |
|
|
} else { |
497 |
|
|
if (forgetMeNot == null) |
498 |
dl |
1.37 |
forgetMeNot = new ArrayList<E>(); |
499 |
dl |
1.36 |
forgetMeNot.add(moved); |
500 |
|
|
} |
501 |
|
|
} else if (lastRetElt != null) { |
502 |
|
|
PriorityQueue.this.remove(lastRetElt); |
503 |
|
|
lastRetElt = null; |
504 |
|
|
} else { |
505 |
|
|
throw new IllegalStateException(); |
506 |
dl |
1.35 |
} |
507 |
|
|
|
508 |
tim |
1.2 |
expectedModCount = modCount; |
509 |
dl |
1.7 |
} |
510 |
tim |
1.2 |
|
511 |
dl |
1.7 |
final void checkForComodification() { |
512 |
|
|
if (modCount != expectedModCount) |
513 |
|
|
throw new ConcurrentModificationException(); |
514 |
|
|
} |
515 |
tim |
1.2 |
} |
516 |
|
|
|
517 |
tim |
1.1 |
public int size() { |
518 |
tim |
1.2 |
return size; |
519 |
tim |
1.1 |
} |
520 |
tim |
1.2 |
|
521 |
|
|
/** |
522 |
dl |
1.52 |
* Removes all of the elements from this priority queue. |
523 |
dl |
1.49 |
* The queue will be empty after this call returns. |
524 |
tim |
1.2 |
*/ |
525 |
|
|
public void clear() { |
526 |
|
|
modCount++; |
527 |
|
|
|
528 |
|
|
// Null out element references to prevent memory leak |
529 |
|
|
for (int i=1; i<=size; i++) |
530 |
|
|
queue[i] = null; |
531 |
|
|
|
532 |
|
|
size = 0; |
533 |
|
|
} |
534 |
|
|
|
535 |
dl |
1.40 |
public E poll() { |
536 |
dl |
1.36 |
if (size == 0) |
537 |
dl |
1.40 |
return null; |
538 |
dl |
1.36 |
modCount++; |
539 |
|
|
|
540 |
|
|
E result = (E) queue[1]; |
541 |
|
|
queue[1] = queue[size]; |
542 |
|
|
queue[size--] = null; // Drop extra ref to prevent memory leak |
543 |
|
|
if (size > 1) |
544 |
|
|
fixDown(1); |
545 |
|
|
|
546 |
|
|
return result; |
547 |
|
|
} |
548 |
|
|
|
549 |
|
|
/** |
550 |
|
|
* Removes and returns the ith element from queue. (Recall that queue |
551 |
|
|
* is one-based, so 1 <= i <= size.) |
552 |
tim |
1.2 |
* |
553 |
dl |
1.36 |
* Normally this method leaves the elements at positions from 1 up to i-1, |
554 |
|
|
* inclusive, untouched. Under these circumstances, it returns null. |
555 |
|
|
* Occasionally, in order to maintain the heap invariant, it must move |
556 |
|
|
* the last element of the list to some index in the range [2, i-1], |
557 |
|
|
* and move the element previously at position (i/2) to position i. |
558 |
|
|
* Under these circumstances, this method returns the element that was |
559 |
|
|
* previously at the end of the list and is now at some position between |
560 |
|
|
* 2 and i-1 inclusive. |
561 |
tim |
1.2 |
*/ |
562 |
dl |
1.52 |
private E removeAt(int i) { |
563 |
dl |
1.36 |
assert i > 0 && i <= size; |
564 |
tim |
1.2 |
modCount++; |
565 |
|
|
|
566 |
dl |
1.36 |
E moved = (E) queue[size]; |
567 |
|
|
queue[i] = moved; |
568 |
tim |
1.2 |
queue[size--] = null; // Drop extra ref to prevent memory leak |
569 |
dl |
1.35 |
if (i <= size) { |
570 |
tim |
1.2 |
fixDown(i); |
571 |
dl |
1.36 |
if (queue[i] == moved) { |
572 |
|
|
fixUp(i); |
573 |
|
|
if (queue[i] != moved) |
574 |
|
|
return moved; |
575 |
|
|
} |
576 |
dl |
1.35 |
} |
577 |
dl |
1.36 |
return null; |
578 |
tim |
1.1 |
} |
579 |
|
|
|
580 |
tim |
1.2 |
/** |
581 |
|
|
* Establishes the heap invariant (described above) assuming the heap |
582 |
|
|
* satisfies the invariant except possibly for the leaf-node indexed by k |
583 |
|
|
* (which may have a nextExecutionTime less than its parent's). |
584 |
|
|
* |
585 |
|
|
* This method functions by "promoting" queue[k] up the hierarchy |
586 |
|
|
* (by swapping it with its parent) repeatedly until queue[k] |
587 |
|
|
* is greater than or equal to its parent. |
588 |
|
|
*/ |
589 |
|
|
private void fixUp(int k) { |
590 |
|
|
if (comparator == null) { |
591 |
|
|
while (k > 1) { |
592 |
|
|
int j = k >> 1; |
593 |
dl |
1.52 |
if (((Comparable<? super E>)queue[j]).compareTo((E)queue[k]) <= 0) |
594 |
tim |
1.2 |
break; |
595 |
tim |
1.16 |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
596 |
tim |
1.2 |
k = j; |
597 |
|
|
} |
598 |
|
|
} else { |
599 |
|
|
while (k > 1) { |
600 |
dl |
1.35 |
int j = k >>> 1; |
601 |
tim |
1.16 |
if (comparator.compare((E)queue[j], (E)queue[k]) <= 0) |
602 |
tim |
1.2 |
break; |
603 |
tim |
1.16 |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
604 |
tim |
1.2 |
k = j; |
605 |
|
|
} |
606 |
|
|
} |
607 |
|
|
} |
608 |
|
|
|
609 |
|
|
/** |
610 |
|
|
* Establishes the heap invariant (described above) in the subtree |
611 |
|
|
* rooted at k, which is assumed to satisfy the heap invariant except |
612 |
|
|
* possibly for node k itself (which may be greater than its children). |
613 |
|
|
* |
614 |
|
|
* This method functions by "demoting" queue[k] down the hierarchy |
615 |
|
|
* (by swapping it with its smaller child) repeatedly until queue[k] |
616 |
|
|
* is less than or equal to its children. |
617 |
|
|
*/ |
618 |
|
|
private void fixDown(int k) { |
619 |
|
|
int j; |
620 |
|
|
if (comparator == null) { |
621 |
dl |
1.33 |
while ((j = k << 1) <= size && (j > 0)) { |
622 |
dl |
1.52 |
if (j<size && |
623 |
|
|
((Comparable<? super E>)queue[j]).compareTo((E)queue[j+1]) > 0) |
624 |
tim |
1.2 |
j++; // j indexes smallest kid |
625 |
dl |
1.35 |
|
626 |
dl |
1.52 |
if (((Comparable<? super E>)queue[k]).compareTo((E)queue[j]) <= 0) |
627 |
tim |
1.2 |
break; |
628 |
tim |
1.16 |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
629 |
tim |
1.2 |
k = j; |
630 |
|
|
} |
631 |
|
|
} else { |
632 |
dl |
1.33 |
while ((j = k << 1) <= size && (j > 0)) { |
633 |
dl |
1.52 |
if (j<size && |
634 |
dl |
1.35 |
comparator.compare((E)queue[j], (E)queue[j+1]) > 0) |
635 |
tim |
1.2 |
j++; // j indexes smallest kid |
636 |
tim |
1.16 |
if (comparator.compare((E)queue[k], (E)queue[j]) <= 0) |
637 |
tim |
1.2 |
break; |
638 |
tim |
1.16 |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
639 |
tim |
1.2 |
k = j; |
640 |
|
|
} |
641 |
|
|
} |
642 |
dl |
1.36 |
} |
643 |
dl |
1.35 |
|
644 |
dl |
1.36 |
/** |
645 |
|
|
* Establishes the heap invariant (described above) in the entire tree, |
646 |
|
|
* assuming nothing about the order of the elements prior to the call. |
647 |
|
|
*/ |
648 |
|
|
private void heapify() { |
649 |
|
|
for (int i = size/2; i >= 1; i--) |
650 |
|
|
fixDown(i); |
651 |
tim |
1.2 |
} |
652 |
|
|
|
653 |
dholmes |
1.23 |
/** |
654 |
dl |
1.52 |
* Returns the comparator used to order the elements in this |
655 |
|
|
* queue, or <tt>null</tt> if this queue is sorted according to |
656 |
|
|
* the {@linkplain Comparable natural ordering} of its elements. |
657 |
|
|
* |
658 |
|
|
* @return the comparator used to order this queue, or |
659 |
|
|
* <tt>null</tt> if this queue is sorted according to the |
660 |
|
|
* natural ordering of its elements. |
661 |
dholmes |
1.23 |
*/ |
662 |
tim |
1.16 |
public Comparator<? super E> comparator() { |
663 |
tim |
1.2 |
return comparator; |
664 |
|
|
} |
665 |
dl |
1.5 |
|
666 |
|
|
/** |
667 |
|
|
* Save the state of the instance to a stream (that |
668 |
|
|
* is, serialize it). |
669 |
|
|
* |
670 |
|
|
* @serialData The length of the array backing the instance is |
671 |
|
|
* emitted (int), followed by all of its elements (each an |
672 |
|
|
* <tt>Object</tt>) in the proper order. |
673 |
dl |
1.7 |
* @param s the stream |
674 |
dl |
1.5 |
*/ |
675 |
dl |
1.22 |
private void writeObject(java.io.ObjectOutputStream s) |
676 |
dl |
1.5 |
throws java.io.IOException{ |
677 |
dl |
1.7 |
// Write out element count, and any hidden stuff |
678 |
|
|
s.defaultWriteObject(); |
679 |
dl |
1.5 |
|
680 |
|
|
// Write out array length |
681 |
|
|
s.writeInt(queue.length); |
682 |
|
|
|
683 |
dl |
1.7 |
// Write out all elements in the proper order. |
684 |
dl |
1.39 |
for (int i=1; i<=size; i++) |
685 |
dl |
1.5 |
s.writeObject(queue[i]); |
686 |
|
|
} |
687 |
|
|
|
688 |
|
|
/** |
689 |
dl |
1.52 |
* Reconstitute the <tt>PriorityQueue</tt> instance from a stream |
690 |
|
|
* (that is, deserialize it). |
691 |
dl |
1.7 |
* @param s the stream |
692 |
dl |
1.5 |
*/ |
693 |
dl |
1.22 |
private void readObject(java.io.ObjectInputStream s) |
694 |
dl |
1.5 |
throws java.io.IOException, ClassNotFoundException { |
695 |
dl |
1.7 |
// Read in size, and any hidden stuff |
696 |
|
|
s.defaultReadObject(); |
697 |
dl |
1.5 |
|
698 |
|
|
// Read in array length and allocate array |
699 |
|
|
int arrayLength = s.readInt(); |
700 |
tim |
1.16 |
queue = new Object[arrayLength]; |
701 |
dl |
1.5 |
|
702 |
dl |
1.7 |
// Read in all elements in the proper order. |
703 |
dl |
1.39 |
for (int i=1; i<=size; i++) |
704 |
dl |
1.37 |
queue[i] = (E) s.readObject(); |
705 |
dl |
1.5 |
} |
706 |
|
|
|
707 |
tim |
1.1 |
} |