Apt package installation querying of dispatcher

[hcoop/domtool2.git] / src / env.sml

diff --git a/src/env.sml b/src/env.sml
index d9905dd..edb1ffd 100644 (file)
--- a/src/env.sml
+++ b/src/env.sml
@@ -41,6 +41,11 @@ fun registerContainer (name, befor, after) =
     containers := SM.insert (!containers, name, (befor, after))
 fun container name = SM.find (!containers, name)
 
+val functions : (exp list -> exp option) SM.map ref = ref SM.empty
+fun registerFunction (name, f) =
+    functions := SM.insert (!functions, name, f)
+fun function name = SM.find (!functions, name)
+
 local
     val pr = ref (fn () => ())
 in
@@ -135,6 +140,14 @@ fun two func (name1, arg1, name2, arg2) f (_, [e1, e2]) =
                                SM.empty))
   | two func _ _ (_, es) = badArgs (func, es)
 
+fun three func (name1, arg1, name2, arg2, name3, arg3) f (_, [e1, e2, e3]) =
+    (case (arg1 e1, arg2 e2, arg3 e3) of
+        (NONE, _, _) => badArg (func, name1, e1)
+       | (_, NONE, _) => badArg (func, name2, e2)
+       | (_, _, NONE) => badArg (func, name3, e3)
+       | (SOME v1, SOME v2, SOME v3) => (f (v1, v2, v3);
+                                        SM.empty))
+  | three func _ _ (_, es) = badArgs (func, es)
 
 fun oneV func (name, arg) f (evs, [e]) =
     (case arg e of
@@ -157,7 +170,9 @@ fun env arg (evs, name) =
        NONE => raise Fail ("Unavailable environment variable " ^ name)
       | SOME e =>
        case arg e of
-           NONE => raise Fail ("Bad format for environment variable " ^ name)
+           NONE => (Print.preface ("Unexpected value for " ^ name ^ ":",
+                                   Print.p_exp e);
+                    raise Fail ("Bad format for environment variable " ^ name))
          | SOME v => v
 
 fun type_one func arg f =
@@ -169,6 +184,7 @@ fun type_one func arg f =
 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 action_three name args f = registerAction (name, three 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)