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/*
* Queue data structure
*/
public class Queue {
class Element {
Element @next;
Object @payload;
}
Element head @=> Element @tail;
fun void
push(Object @data)
{
new Element @=> tail.next @=> tail;
data @=> tail.payload;
}
fun Object @
peek()
{
if (head.next == null)
/* empty */
return null;
else
return head.next.payload;
}
fun Object @
pop()
{
head.next @=> Element @el;
if (el == null)
/* empty */
return null;
el.next @=> head.next;
if (el == tail)
/* but now it's empty! */
head @=> tail;
return el.payload;
}
fun void
flush()
{
while (pop() != null);
}
}
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