1 package org.opentrafficsim.core.perception.collections;
2
3 import java.util.Queue;
4
5 import org.opentrafficsim.core.perception.HistoryManager;
6
7 /**
8 * Queue-valued historical state. The current queue is always maintained, and past states of the queue are obtained by applying
9 * the events between now and the requested time in reverse.<br>
10 * <br>
11 * The {@code Iterator} returned by this class does not support the {@code remove()} method.
12 * <p>
13 * Copyright (c) 2013-2019 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
14 * BSD-style license. See <a href="http://opentrafficsim.org/node/13">OpenTrafficSim License</a>.
15 * <p>
16 * @version $Revision$, $LastChangedDate$, by $Author$, initial version 4 feb. 2018 <br>
17 * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
18 * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
19 * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
20 * @param <E> element type
21 * @param <Q> queue type
22 */
23 public abstract class AbstractHistoricalQueue<E, Q extends Queue<E>> extends AbstractHistoricalCollection<E, Q>
24 implements HistoricalQueue<E>
25 {
26
27 /**
28 * Constructor.
29 * @param historyManager HistoryManager; history manager
30 * @param queue Q; initial queue
31 */
32 protected AbstractHistoricalQueue(final HistoryManager historyManager, final Q queue)
33 {
34 super(historyManager, queue);
35 }
36
37 // Altering PriorityQueue methods
38
39 /** {@inheritDoc} */
40 @Override
41 public boolean offer(final E e)
42 {
43 boolean added = getCollection().offer(e);
44 if (added)
45 {
46 addEvent(new AddEvent<>(now().si, e));
47 }
48 return added;
49 }
50
51 /** {@inheritDoc} */
52 @Override
53 public E remove()
54 {
55 E e = getCollection().remove();
56 addEvent(new RemoveEvent<>(now().si, e));
57 return e;
58 }
59
60 /** {@inheritDoc} */
61 @Override
62 public E poll()
63 {
64 if (isEmpty())
65 {
66 return null;
67 }
68 return remove();
69 }
70
71 // Non-altering PriorityQueue methods
72
73 /** {@inheritDoc} */
74 @Override
75 public E peek()
76 {
77 return this.getCollection().peek();
78 }
79
80 /** {@inheritDoc} */
81 @Override
82 public E element()
83 {
84 return this.getCollection().element();
85 }
86
87 }