hphp/hack/src/typing/typing_disposable.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 (* Typing code concerned with disposable types. *)
  11
  12 open Hh_core
  13 open Typing_defs
  14
  15 module Env = Typing_env
  16
  17 let is_disposable_visitor env =
  18   object(this)
  19   inherit [string option] Type_visitor.type_visitor
  20   (* Only bother looking at classish types. Other types can spuriously
  21    * claim to implement these interfaces. Ideally we should check
  22    * constrained generics, abstract types, etc.
  23    *)
  24   method! on_tclass acc _ (_, class_name) tyl =
  25     let default () =
  26       List.fold_left tyl ~f:this#on_type ~init:acc in
  27     begin match Env.get_class env class_name with
  28     | None -> default ()
  29     | Some c ->
  30       if c.tc_is_disposable
  31       then Some (Utils.strip_ns class_name)
  32       else default ()
  33     end
  34   end
  35
  36 (* Does ty (or a type embedded in ty) implement IDisposable
  37  * or IAsyncDisposable, directly or indirectly?
  38  * Return Some class_name if it does, None if it doesn't.
  39  *)
  40 let is_disposable_type env ty =
  41   match Env.expand_type env ty with
  42   | _env, ety ->
  43     (is_disposable_visitor env)#on_type None ety
  44
  45 let enforce_is_disposable env hint =
  46   match hint with
  47     | (_, Nast.Happly ((p, c), _)) ->
  48       begin match Decl_env.get_class_dep env.Env.decl_env c with
  49       | None -> ()
  50       | Some c ->
  51         if not c.Decl_defs.dc_is_disposable
  52         then Errors.must_extend_disposable p
  53       end
  54     | _ -> ()
  55
  56 (* Ensure that `ty` is a subtype of IDisposable (for `using`) or
  57  * IAsyncDisposable (for `await using`)
  58  *)
  59 let enforce_is_disposable_type env has_await pos ty =
  60   let class_name =
  61     if has_await
  62     then SN.Classes.cIAsyncDisposable
  63     else SN.Classes.cIDisposable in
  64   let disposable_ty = (Reason.Rusing pos, Tclass ((pos, class_name), [])) in
  65   Typing_ops.sub_type pos Reason.URusing env ty disposable_ty