src/Pure/ML-Systems/polyml-interrupt-timeout.ML

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Pure/ML-Systems/polyml-interrupt-timeout.ML	Mon Jan 23 17:29:52 2006 +0100
@@ -0,0 +1,44 @@
+(*  Title:      Pure/ML-Systems/polyml-interrupt-timeout.ML
+    ID:         $Id$
+    Author:     Tjark Weber, Makarius
+    Copyright   2006
+
+Bounded time execution (similar to SML/NJ's TimeLimit structure) for Poly/ML.
+*)
+
+local
+
+  val alarm_active = ref false;
+
+  val _ = Signal.signal (Posix.Signal.alrm, Signal.SIG_HANDLE (fn _ =>
+    let val active = ! alarm_active in
+      alarm_active := false;
+      if active then
+        Process.interruptConsoleProcesses ()
+      else
+        ()
+    end));
+
+in
+
+  (* Time.time -> ('a -> 'b) -> 'a -> 'b *)
+
+  fun interrupt_timeout time f x =
+  let
+    fun deactivate_alarm () = (
+      alarm_active := false;
+      Posix.Process.alarm Time.zeroTime
+    )
+  in
+    alarm_active := true;
+    Posix.Process.alarm time;
+    let val result = f x in
+      deactivate_alarm ();
+      result
+    end handle exn => (
+      deactivate_alarm ();
+      raise exn
+    )
+  end;
+
+end;