updates to scalax collections and standard libr...

updates to scalax collections and standard library classes.

1 files changed, 24 insertions, 0 deletions

diff --git a/src/library/scalax/util/control/TailRec.scala b/src/library/scalax/util/control/TailRec.scala
new file mode 100644
index 0000000000..db6cbfa2ed
--- /dev/null
+++ b/src/library/scalax/util/control/TailRec.scala
@@ -0,0 +1,24 @@
+package scala.util.control
+
+abstract class TailRec[+A]
+
+object TailRec {
+
+  case class Call[A](rest: () => TailRec[A]) extends TailRec[A]
+  case class Done[A](result: A) extends TailRec[A]
+
+  def tailcall[A](rest: => TailRec[A]) = new Call(() => rest)
+  def done    [A](result: A) = new Done(result)
+  def trampoline[A](body: TailRec[A]): A = {
+    def loop(body: TailRec[A]): A = body match {
+      case Call(rest) => loop(rest())
+      case Done(result) => result
+    }
+    loop(body)
+  }
+  def loop[A](body: TailRec[A]): A = body match {
+    case Call(rest) => loop[A](rest())
+    case Done(result) => result
+  }
+}
+