hphp/hack/src/typing/typing_substring.ml

   1 (*
   2  * Copyright (c) 2015, 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 Typing_defs
  11 open Typing_env_types
  12 module Reason = Typing_reason
  13 module Env = Typing_env
  14 module TUtils = Typing_utils
  15 module MakeType = Typing_make_type
  16
  17 let is_object env ty =
  18   Typing_solver.is_sub_type env ty (MakeType.ty_object (get_reason ty))
  19
  20 let sub_string (p : Pos.Map.key) (env : env) (ty : locl_ty) : env =
  21   (* Under constraint-based inference, we implement sub_string as a subtype test.
  22    * All the cases in the legacy implementation just fall out from subtyping rules.
  23    * We test against ?(arraykey | bool | float | resource | object | dynamic |
  24    * HH\FormatString<T>).
  25    *)
  26   let r = Reason.Rwitness p in
  27   let (env, formatter_tyvar) = Env.fresh_invariant_type_var env p in
  28   let tyl =
  29     [
  30       MakeType.arraykey r;
  31       MakeType.bool r;
  32       MakeType.float r;
  33       MakeType.resource r;
  34       MakeType.dynamic r;
  35       MakeType.class_type r SN.Classes.cHHFormatString [formatter_tyvar];
  36     ]
  37   in
  38   let stringish = MakeType.class_type r SN.Classes.cStringish [] in
  39   let stringlike = MakeType.nullable_locl r (MakeType.union r tyl) in
  40   Typing_subtype.sub_type_or_fail env ty stringlike (fun () ->
  41       if Typing_solver.is_sub_type env ty stringish then
  42         Errors.object_string_deprecated p
  43       else if is_object env ty then
  44         Errors.object_string p (get_pos ty)
  45       else
  46         Errors.invalid_sub_string p (Typing_print.error env ty))