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/**
* Title: Queue
* Description: The primary event queue for the Event Analysis Configurator
*/
package EAC;
public class Queue {
private class Node {
public Primitive primitive;
public long time;
public Node next;
public Node(Primitive p, long t, Node n) {
primitive = p;
time = t;
next = n;
} /* constructor */
} /* Node */
private Node head;
private int count;
public Queue() {
count = 0;
} /* constructor */
public boolean empty() {
return (count == 0);
} /* empty */
public void clear() {
while (!empty())
try {
dequeue();
} catch (EmptyQueueException eqe) {
// can't happen
}
} /* clear */
public void enqueue(Primitive p, long t) {
if (head == null) {
head = new Node(p,t,null);
count = 1;
} else { // non-empty
if ((head.time == t) && (head.primitive == p))
return; // no duplicates
else if (head.time >= t) { // need new head
Node temp = new Node(p,t,head);
head = temp;
} else { // find insertion point
Node ptr = head;
while (ptr.next != null)
if (ptr.next.time < t)
ptr = ptr.next;
else
break;
if (ptr.next == null)
ptr.next = new Node(p,t,null);
else if ((ptr.next.time == t) && (ptr.next.primitive == p))
return; // no duplicates
else {
Node temp = new Node(p,t,ptr.next);
ptr.next = temp;
}
}
count++;
} /* else */
} /* enqueue */
public Primitive dequeue () throws EmptyQueueException {
if (count == 0)
throw new EmptyQueueException("ERROR: dequeue called when queue empty");
Primitive temp = head.primitive;
head = head.next;
--count;
return temp;
} /* dequeue */
public long frontTime () throws EmptyQueueException {
if (count == 0)
throw new EmptyQueueException("ERROR: frontTime called when queue empty");
return head.time;
} /* frontTime */
}
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