X-Git-Url: http://git.hcoop.net/clinton/domtool2.git/blobdiff_plain/6ae327f88a6be8efd02cfe4b713444f9f3ac2672..e0b0abd209a1ecbd9266cfcf8735af171f96869b:/src/env.sml

diff --git a/src/env.sml b/src/env.sml
index 91fb69d..167adce 100644
--- a/src/env.sml
+++ b/src/env.sml
@@ -41,6 +41,34 @@ fun registerContainer (name, befor, after) =
     containers := SM.insert (!containers, name, (befor, after))
 fun container name = SM.find (!containers, name)
 
+local
+    val pr = ref (fn () => ())
+in
+
+fun registerPre f =
+    let
+	val old = !pr
+    in
+	pr := (fn () => (old (); f ()))
+    end
+fun pre () = !pr ()
+
+end
+
+local
+    val pst = ref (fn () => ())
+in
+
+fun registerPost f =
+    let
+	val old = !pst
+    in
+	pst := (fn () => (old (); f ()))
+    end
+fun post () = !pst ()
+
+end
+
 fun badArgs (name, args) =
     (print ("Invalid arguments to " ^ name ^ "\n");
      app (fn arg => Print.preface ("Argument: ", Print.p_exp arg)) args;
@@ -97,6 +125,14 @@ fun oneV func (name, arg) f (evs, [e]) =
 		    SM.empty))
   | oneV func _ _ (_, es) = badArgs (func, es)
 
+fun twoV func (name1, arg1, name2, arg2) f (evs, [e1, e2]) =
+    (case (arg1 e1, arg2 e2) of
+	 (NONE, _) => badArg (func, name1, e1)
+       | (_, NONE) => badArg (func, name2, e2)
+       | (SOME v1, SOME v2) => (f (evs, v1, v2);
+				SM.empty))
+  | twoV func _ _ (_, es) = badArgs (func, es)
+
 
 fun env arg (evs, name) =
     case SM.find (evs, name) of
@@ -116,7 +152,9 @@ fun action_none name f = registerAction (name, none name f)
 fun action_one name args f = registerAction (name, one name args f)
 fun action_two name args f = registerAction (name, two name args f)
 
+fun actionV_none name f = registerAction (name, fn (env, _) => (f env; env))
 fun actionV_one name args f = registerAction (name, oneV name args f)
+fun actionV_two name args f = registerAction (name, twoV name args f)
 
 fun container_none name (f, g) = registerContainer (name, none name f, g)
 fun container_one name args (f, g) = registerContainer (name, one name args f, g)