ast_exp_extension.ml

(* Copyright (C) 2018 Hongbo Zhang, Authors of ReScript
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * In addition to the permissions granted to you by the LGPL, you may combine
 * or link a "work that uses the Library" with a publicly distributed version
 * of this file to produce a combined library or application, then distribute
 * that combined work under the terms of your choosing, with no requirement
 * to comply with the obligations normally placed on you by section 4 of the
 * LGPL version 3 (or the corresponding section of a later version of the LGPL
 * should you choose to use a later version).
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)
open Ast_helper

let handle_extension e (self : Bs_ast_mapper.mapper)
    (({txt; loc}, payload) : Parsetree.extension) =
  match txt with
  | "ffi" -> Ast_exp_handle_external.handle_ffi ~loc ~payload
  | "raw" -> Ast_exp_handle_external.handle_raw ~kind:Raw_exp loc payload
  | "re" ->
    Exp.constraint_ ~loc
      (Ast_exp_handle_external.handle_raw ~kind:Raw_re loc payload)
      (Ast_comb.to_js_re_type loc)
  | "external" -> (
    match Ast_payload.as_ident payload with
    | Some {txt = Lident x} ->
      Ast_exp_handle_external.handle_external loc x
      (* do we need support [%external gg.xx ]

         {[ Js.Undefined.to_opt (if Js.typeof x == "undefined" then x else Js.Undefined.empty ) ]}
      *)
    | None | Some _ ->
      Location.raise_errorf ~loc "external expects a single identifier")
  | "time" -> (
    match payload with
    | PStr [{pstr_desc = Pstr_eval (e, _)}] ->
      let locString =
        if loc.loc_ghost then "GHOST LOC"
        else
          let loc_start = loc.loc_start in
          let file, lnum, __ = Location.get_pos_info loc_start in
          Printf.sprintf "%s %d" (Filename.basename file) lnum
      in
      let e = self.expr self e in
      Exp.sequence ~loc
        (Ast_compatible.app1 ~loc
           (Exp.ident ~loc
              {loc; txt = Ldot (Ldot (Lident "Js", "Console"), "timeStart")})
           (Ast_compatible.const_exp_string ~loc locString))
        (Exp.let_ ~loc Nonrecursive
           [Vb.mk ~loc (Pat.var ~loc {loc; txt = "timed"}) e]
           (Exp.sequence ~loc
              (Ast_compatible.app1 ~loc
                 (Exp.ident ~loc
                    {loc; txt = Ldot (Ldot (Lident "Js", "Console"), "timeEnd")})
                 (Ast_compatible.const_exp_string ~loc locString))
              (Exp.ident ~loc {loc; txt = Lident "timed"})))
    | _ ->
      Location.raise_errorf ~loc "expect a boolean expression in the payload")
  | "debugger" ->
    {e with pexp_desc = Ast_exp_handle_external.handle_debugger loc payload}
  | "obj" -> (
    match payload with
    | PStr
        [
          {
            pstr_desc =
              Pstr_eval (({pexp_desc = Pexp_record (label_exprs, None)} as e), _);
          };
        ] ->
      {
        e with
        pexp_desc = Ast_util.record_as_js_object e.pexp_loc self label_exprs;
      }
    | _ -> Location.raise_errorf ~loc "Expect a record expression here")
  | _ -> e
(* For an unknown extension, we don't really need to process further*)
(* Exp.extension ~loc ~attrs:e.pexp_attributes (
    self.extension self extension) *)
(* Bs_ast_mapper.default_mapper.expr self e   *)