1 files changed, 74 insertions, 0 deletions
diff --git a/sources/examples/pilib/twoPlaceBuffer.scala b/sources/examples/pilib/twoPlaceBuffer.scala
new file mode 100644
index 0000000000..15f29dee07
--- /dev/null
+++ b/sources/examples/pilib/twoPlaceBuffer.scala
@@ -0,0 +1,74 @@
+/** Two-place buffer specification and implementation. */
+object twoPlaceBuffer {
+
+  import scala.concurrent.pilib._;
+
+  /**
+  * Specification.
+  */
+  def Spec[a](put: Chan[a], get: Chan[a]): unit =  {
+
+    def B0: unit = {
+      val x = put.read;
+      B1(x)
+    }
+
+    def B1(x: a): unit = choice (
+      get(x) * (B0),
+      put * (y => B2(x, y))
+    );
+
+    def B2(x: a, y: a): unit = {
+      get.write(x);
+      B1(y)
+    };
+
+    B0
+  }
+
+  /**
+  * Implementation.
+  */
+  def Impl[a](put: Chan[a], get: Chan[a]): unit =  {
+
+    // An empty one-place buffer.
+    def B0(in: Chan[a], out: Chan[a]): unit = {
+      val x = in.read;
+      B1(in, out, x)
+    }
+
+    // A full one-place buffer containing x.
+    def B1(in: Chan[a], out: Chan[a], x: a): unit = {
+      out.write(x);
+      B0(in, out)
+    };
+
+    val hidden = new Chan[a];
+    spawn < B0(put, hidden) | B0(hidden, get) >
+  }
+
+  val random = new java.util.Random();
+
+  def Producer(n: Int, put: Chan[String]): unit = {
+    Thread.sleep(1 + random.nextInt(1000));
+    val msg = "object " + n;
+    put.write(msg);
+    System.out.println("Producer gave " + msg);
+    Producer(n + 1, put)
+  }
+
+  def Consumer(get: Chan[String]): unit = {
+    Thread.sleep(1 + random.nextInt(1000));
+    val msg = get.read;
+    System.out.println("Consummer took " + msg);
+    Consumer(get)
+  }
+
+  def main(args: Array[String]): unit = {
+    val put = new Chan[String];
+    val get = new Chan[String];
+    spawn < Producer(0, put) | Consumer(get) | Spec(put, get) >
+    //spawn < Producer(0, put) | Consumer(get) | Impl(put, get) >
+  }
+
+}