CristalCaveGem » LustreC

(** Normalisation iters through the AST of expressions and bind fresh definition

    when some criteria are met. This creation of fresh definition is performed by

    the function mk_expr_alias_opt when the alias argument is on.

    Initial expressions, ie expressions attached a variable in an equation

    definition are not aliased. This non-alias feature is propagated in the

    expression AST for array access and power construct, tuple, and some special

    cases of arrows.

    Two global variables may impact the normalization process:

    - unfold_arrow_active

    - force_alias_ite: when set, bind a fresh alias for then and else

      definitions.

*)

(* Two global variables *)

let unfold_arrow_active = ref true

let force_alias_ite = ref false

  | _ when !force_alias_ite ->

     (* Forcing alias creation for then/else expressions *)

     let defvars, norm_expr =

       normalize_expr ~alias:alias node offsets defvars expr

     in

     mk_expr_alias_opt true node defvars norm_expr

  | _ -> (* default case without the force_alias_ite option *)

     normalize_expr ~alias:alias node offsets defvars expr

let normalize_prog ?(backend="C") decls =

  let old_unfold_arrow_active = !unfold_arrow_active in

  let old_force_alias_ite = !force_alias_ite in

  (* Backend specific configurations for normalization *)

  let _ =

    match backend with

    | "lustre" ->

    (* Special treatment of arrows in lustre backend. We want to keep them *)

       unfold_arrow_active := false;

    | "emf" -> (* Forcing ite normalization *)

       force_alias_ite := true;

    | _ -> () (* No fancy options for other backends *)

  in

  (* Main algorithm: iterates over nodes *)

  let res = List.map normalize_decl decls in

  (* Restoring previous settings *)

  unfold_arrow_active := old_unfold_arrow_active;

  force_alias_ite := old_force_alias_ite;

  res

  (* Local Variables: *)