wip logical planning

lib/logical_plan.ml

@@ -1,17 +1,34 @@
 type logical_plan =
-  | Project of logical_plan * string
+  | Project of logical_plan * string list
   | Scan of string (* Table name *)
   | Filter of logical_plan 
   | Join of logical_plan * Ast.join_type * logical_plan 
   | Group of logical_plan * string list
 
-let ast_to_logical ast =
+let rec ast_to_logical ast =
   match ast with 
-  | Ast.Select(_, _) -> Project(Scan("table"), "ok")
+  | Ast.Select(cols, _) -> Project(Scan("table"), (columns_to_logical cols))
   | _ -> failwith "Query not supported yet"
 
+and columns_to_logical columns =
+  let rec aux cols acc = 
+    match  cols with
+    | [] -> acc
+    | Ast.Column(col,_)::l ->
+      let s = expression_to_logical col in
+      aux l (s::acc)
+    | _ -> failwith "Not supported"
+  in 
+  aux columns []
+
+and expression_to_logical exp =
+  match exp with
+  | Ast.Ref(s) -> s
+  | _ -> failwith "Expression not supported yet"
+
+
 let rec pp_logical_plan plan =
   match plan with 
-  | Project(plan2, name) -> pp_logical_plan plan2 ^ name
+  | Project(plan2, name) -> pp_logical_plan plan2 ^ (String.concat ";" name)
   | _ -> "Not supported"
 

test/test_logical_plan.ml

@@ -25,7 +25,7 @@ let test_simple_select () =
   in
   let plan1 = ast_to_logical ast1 in
   let plan2 =
-    Project(Scan("table"), "string")
+    Project(Scan("table"), ["string"])
   in
   Alcotest.(check logical_plan_testable) "ok" plan1 plan2