hphp/hack/src/typing/nast_check/record_field_check.ml

   1 (*
   2  * Copyright (c) 2019, Facebook, Inc.
   3  * All rights reserved.
   4  *
   5  * This source code is licensed under the MIT license found in the
   6  * LICENSE file in the "hack" directory of this source tree.
   7  *
   8  *)
   9
  10 open Core_kernel
  11 open Aast
  12
  13 let id_if_string expr : 'a option =
  14   let (pos, expr_) = expr in
  15   match expr_ with
  16   | String s -> Some (pos, s)
  17   | _ -> None
  18
  19 let check_duplicates (ids : Aast.sid list) : unit =
  20   let _ =
  21     List.fold ids ~init:SMap.empty ~f:(fun acc (pos, name) ->
  22         (match SMap.find_opt name acc with
  23         | Some prev_pos -> Errors.repeated_record_field name pos prev_pos
  24         | None -> ());
  25         SMap.add name pos acc)
  26   in
  27   ()
  28
  29 let handler =
  30   object
  31     inherit Nast_visitor.handler_base as super
  32
  33     (* Ban duplicate fields in declarations: record Foo { x: int, x: int } *)
  34     method! at_record_def _env rd =
  35       let field_names = List.map rd.rd_fields ~f:(fun (id, _, _) -> id) in
  36       check_duplicates field_names
  37
  38     (* Ban duplicate fields in instantiations: Foo['x' => 1, 'x' => 2]; *)
  39     method! at_expr env (pos, e) =
  40       match e with
  41       | Aast.Record (_, fields) ->
  42         let field_names =
  43           List.map fields ~f:(fun (id, _) -> id_if_string id) |> List.filter_opt
  44         in
  45         check_duplicates field_names
  46       | _ -> super#at_expr env (pos, e)
  47   end