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import scala.concurrent.pilib._;
/** Two-place buffer specification and implementation. */
object twoPlaceBuffer with Application {
/**
* Specification.
*/
def Spec[a](in: Chan[a], out: Chan[a]): unit = {
def B0: unit = choice (
in * (x => B1(x))
);
def B1(x: a): unit = choice (
out(x) * (B0),
in * (y => B2(x, y))
);
def B2(x: a, y: a): unit = choice (
out(x) * (B1(y))
);
B0
}
/**
* Implementation using two one-place buffers.
*/
def Impl[a](in: Chan[a], out: Chan[a]): unit = {
///- ... complete here ...
// one-place buffer
def OnePlaceBuffer[a](in: Chan[a], out: Chan[a]): unit = {
def B0: unit = choice ( in * (x => B1(x)) );
def B1(x: a): unit = choice ( out(x) * (B0));
B0
}
val hidden = new Chan[a];
spawn < OnePlaceBuffer(in, hidden) | OnePlaceBuffer(hidden, out) >
///+
}
val random = new java.util.Random();
def Producer(n: Int, in: Chan[String]): unit = {
Thread.sleep(random.nextInt(1000));
val msg = "" + n;
choice (in(msg) * {});
Producer(n + 1, in)
}
def Consumer(out: Chan[String]): unit = {
Thread.sleep(random.nextInt(1000));
choice (out * { msg => () });
Consumer(out)
}
val in = new Chan[String];
in.attach(s => System.out.println("put " + s));
val out = new Chan[String];
out.attach(s => System.out.println("get " + s));
//spawn < Producer(0, in) | Consumer(out) | Spec(in, out) >
spawn < Producer(0, in) | Consumer(out) | Impl(in, out) >
}
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