added missing file from last commit. no review.

git-svn-id: http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk@21142 5e8d7ff9-d8ef-0310-90f0-a4852d11357a

src/continuations/library/scala/util/continuations/ControlContext.scala

@@ -0,0 +1,60 @@
+// $Id$
+
+package scala.util.continuations
+
+
+class cpsParam[-B,+C] extends StaticAnnotation with TypeConstraint
+
+private class cpsSym[B] extends Annotation // implementation detail
+
+private class cpsSynth extends Annotation // implementation detail
+
+private class cpsPlus extends StaticAnnotation with TypeConstraint // implementation detail
+private class cpsMinus extends Annotation // implementation detail
+
+
+
+@serializable final class ControlContext[+A,-B,+C](val fun: (A => B) => C, val x: A) {
+  
+  final def map[A1](f: (A => A1)): ControlContext[A1,B,C] = {
+    if (fun eq null)
+      new ControlContext(null, f(x))
+    else
+      new ControlContext((k:(A1 => B)) => fun((x:A) => k(f(x))), null.asInstanceOf[A1])
+  }
+  
+  /*  
+    final def flatMap[A1,B1<:B](f: (A => ControlContext[A1,B1,B])): ControlContext[A1,B1,C] = {
+      new ControlContext((k:(A1 => B1)) => fun((x:A) => f(x).fun(k)))
+    }
+  */
+
+  // it would be nice if @inline would turn the trivial path into a tail call.
+  // unfortunately it doesn't, so we do it ourselves in SelectiveCPSTransform
+  
+  /*@inline*/ final def flatMap[A1,B1,C1<:B](f: (A => ControlContext[A1,B1,C1])): ControlContext[A1,B1,C] = {
+    if (fun eq null)
+      f(x).asInstanceOf[ControlContext[A1,B1,C]]
+    else
+      new ControlContext({ k:(A1 => B1) =>
+        fun { (x:A) =>
+          val ctxR = f(x)
+          val res: C1 = ctxR.foreach(k)
+          res
+        }
+      }, null.asInstanceOf[A1])
+  }
+
+  final def foreach(f: (A => B)) = {
+    if (fun eq null)
+      f(x).asInstanceOf[C]
+    else
+      fun(f)
+  }
+
+  final def isTrivial = fun eq null
+  final def getTrivialValue = x.asInstanceOf[A]
+
+  // need filter or other functions?
+
+}