1 files changed, 24 insertions, 16 deletions
diff --git a/lib/drl/executor.ml b/lib/drl/executor.ml
index e472ec5..dcfe716 100644
--- a/lib/drl/executor.ml
+++ b/lib/drl/executor.ml
@@ -1,27 +1,35 @@
 open Utilities.Result
 
+module Error = struct
+  open Condition
+
+  let unqualified_name name =
+    condition "unqualified-name" "A relation must be named as multigroup:relation"
+      ("name" |=| Value.String name)
+end
+
 let page_limit = 16
 
-(* [mg:rel] names a relation on the session's branch; a bare name, one the session created. *)
-let path_of (ctx : Sublanguage_context.t) name =
+let relation_path branch name =
   match String.index_opt name ':' with
-  | None -> ctx.session#namespace ^ "\\" ^ name
-  | Some i ->
-      String.concat "\\"
-        [ "";
-          "branch";
-          ctx.session#branch;
-          "multigroup";
-          String.sub name 0 i;
-          "relation";
-          String.sub name (i + 1) (String.length name - i - 1) ]
+  | Some i when i > 0 && i < String.length name - 1 ->
+      Ok
+        (String.concat "\\"
+           [ branch;
+             "multigroup";
+             String.sub name 0 i;
+             "relation";
+             String.sub name (i + 1) (String.length name - i - 1) ] )
+  | _ -> Error (Error.unqualified_name name)
 
-let rec compile ctx = function
-  | Ast.Base name -> RNT.Base (path_of ctx name)
-  | Ast.Project (attributes, query) -> RNT.Project (compile ctx query, attributes)
+let rec compile branch = function
+  | Ast.Base name -> relation_path branch name |> Result.map (fun path -> RNT.Base path)
+  | Ast.Project (attributes, query) ->
+      compile branch query |> Result.map (fun plan -> RNT.Project (plan, attributes))
 
 let execute (ctx : Sublanguage_context.t) query =
-  let* relation = RNT.execute ctx.kernel (compile ctx query) in
+  let* plan = compile (ctx.session#path ^ "\\branch") query in
+  let* relation = RNT.execute ctx.kernel plan in
   Fun.protect
     ~finally:(fun () -> RNT.release relation)
     (fun () ->