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package test;
import scala.actors.TIMEOUT;
class MailBox {
private class LinkedList[a] {
var elem: a = _;
var next: LinkedList[a] = null;
}
private def insert[a](l: LinkedList[a], x: a): LinkedList[a] = {
l.next = new LinkedList[a];
l.next.elem = x;
l.next.next = l.next;
l
}
private abstract class Receiver {
def isDefined(msg: Any): Boolean;
var msg: Any = null;
}
private val sent = new LinkedList[Any];
private var lastSent = sent;
private val receivers = new LinkedList[Receiver];
private var lastReceiver = receivers;
def send(msg: Any): Unit = synchronized {
var r = receivers;
var r1 = r.next;
while (r1 != null && !r1.elem.isDefined(msg)) {
r = r1; r1 = r1.next;
}
if (r1 != null) {
r.next = r1.next; r1.elem.msg = msg; r1.elem.notify();
} else {
lastSent = insert(lastSent, msg);
}
}
def receive[a](f: PartialFunction[Any, a]): a = {
val msg: Any = synchronized {
var s = sent;
var s1 = s.next;
while (s1 != null && !f.isDefinedAt(s1.elem)) {
s = s1; s1 = s1.next
}
if (s1 != null) {
s.next = s1.next; s1.elem
} else {
val r = insert(lastReceiver, new Receiver {
def isDefined(msg: Any) = f.isDefinedAt(msg);
});
lastReceiver = r;
r.elem.wait();
r.elem.msg
}
}
f(msg)
}
def receiveWithin[a](msec: Long)(f: PartialFunction[Any, a]): a = {
val msg: Any = synchronized {
var s = sent;
var s1 = s.next;
while (s1 != null && !f.isDefinedAt(s1.elem)) {
s = s1; s1 = s1.next ;
}
if (s1 != null) {
s.next = s1.next; s1.elem
} else {
val r = insert(lastReceiver, new Receiver {
def isDefined(msg: Any) = f.isDefinedAt(msg);
});
lastReceiver = r;
r.elem.wait(msec);
if (r.elem.msg == null) r.elem.msg = TIMEOUT;
r.elem.msg
}
}
f(msg)
}
}
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