module Value = Ast.Value

type t = {
  vars : (string, Value.t) Hashtbl.t;
  parent : t option;
}

let init_global () = {
  vars = Hashtbl.create 100;
  parent = None;
}

let make parent = {
  vars = Hashtbl.create 100;
  parent = Some parent;
}

exception Not_found

let rec get e name =
  match Hashtbl.find_opt e.vars name with
  | None -> begin match e.parent with
      | None -> raise Not_found
      | Some p -> get p name
    end
  | Some value -> value

let get_opt e name =
  try Some (get e name)
  with Not_found -> None

let set e name value =
  Hashtbl.replace e.vars name value

let add_seq e seq =
  Hashtbl.add_seq e.vars seq