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

   1 (*
   2  * Copyright (c) 2018, 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 Hh_prelude
  11 open Aast
  12
  13 type ctx = { class_tparams: Nast.tparam list }
  14
  15 let visitor =
  16   object (this)
  17     inherit [ctx] Nast_visitor.iter_with_state as super
  18
  19     method! on_hint (env, state) (pos, h) =
  20       begin
  21         match h with
  22         | Habstr (tp_name, args) ->
  23           List.iter
  24             state.class_tparams
  25             ~f:(fun { tp_name = (c_tp_pos, c_tp_name); _ } ->
  26               if String.equal c_tp_name tp_name then
  27                 Errors.typeconst_depends_on_external_tparam
  28                   pos
  29                   c_tp_pos
  30                   c_tp_name);
  31           List.iter args ~f:(this#on_hint (env, state))
  32         | _ -> ()
  33       end;
  34       super#on_hint (env, state) (pos, h)
  35   end
  36
  37 let handler =
  38   object
  39     inherit Nast_visitor.handler_base
  40
  41     method! at_class_ env c =
  42       let state = { class_tparams = c.c_tparams } in
  43       let on_hint = visitor#on_hint (env, state) in
  44       List.iter c.c_typeconsts ~f:(fun t ->
  45           match t.c_tconst_kind with
  46           | TCAbstract
  47               {
  48                 c_atc_as_constraint = a;
  49                 c_atc_super_constraint = s;
  50                 c_atc_default = d;
  51               } ->
  52             Option.iter a ~f:on_hint;
  53             Option.iter s ~f:on_hint;
  54             Option.iter d ~f:on_hint
  55           | TCConcrete { c_tc_type = t } -> on_hint t)
  56   end