(* wrappi
 * Copyright (C) 2011 Red Hat Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *)

(* For general information about camlp4, see:
 * http://brion.inria.fr/gallium/index.php/Camlp4
 *
 * For information about quotations, see:
 * http://brion.inria.fr/gallium/index.php/Quotation
 *)

open Camlp4.PreCast
open Syntax
open Ast

open Wrappi_types

(* Convert a plain list into a list AST. *)
let rec expr_of_list _loc = function
  | [] -> <:expr< [] >>
  | h::t -> let t = expr_of_list _loc t in <:expr< $h$ :: $t$ >>

(* Convert an optional type into an option AST. *)
let expr_of_option _loc = function
  | None -> <:expr< None >>
  | Some x -> <:expr< Some $x$ >>

(* Convert a _loc to an AST. *)
let expr_of_loc _loc loc =
  let file_name,
    start_line, start_bol, start_off,
    stop_line, stop_bol, stop_off,
    ghost = Loc.to_tuple loc in
  <:expr< Camlp4.PreCast.Loc.of_tuple
    ($str:file_name$,
     $`int:start_line$, $`int:start_bol$, $`int:start_off$,
     $`int:stop_line$, $`int:stop_bol$, $`int:stop_off$,
     $`bool:ghost$) >>

let add_entry_point _loc name parameters return_type code =
  let parameters = List.map (
    fun (name, t) -> <:expr< ($str:name$, $t$) >>
  ) parameters in
  let parameters = expr_of_list _loc parameters in

  let code = expr_of_option _loc code in

  let loc = expr_of_loc _loc _loc in

  <:str_item<
    let ep = { Wrappi_types.ep_loc = $loc$;
               ep_name = $str:name$;
               ep_params = $parameters$;
               ep_return = $return_type$;
               ep_code = $code$ } in
    Wrappi_globals.add_entry_point ep
  >>

let () =
  (* Quotation expander for C code. *)
  let c_quotation_expander _loc _ code =
    (* XXX Expand %- or $- expressions in code. *)
    (* XXX Escape >> in code. *)
    ExStr (_loc, code)
  in
  Quotation.add "c" Quotation.DynAst.expr_tag c_quotation_expander;

  (* Default quotation expander (<< .. >>) should be C code ("c"). *)
  Quotation.default := "c"

;;

(* Extend the regular OCaml grammar. *)
EXTEND Gram
  GLOBAL: str_item;

  (* A parameter or return type. *)
  any_type: [
    [ "int32" -> <:expr< Wrappi_types.TInt32 >> ]
  | [ "int64" -> <:expr< Wrappi_types.TInt64 >> ]
  | [ t = LIDENT -> <:expr< Wrappi_types.Type $str:t$ >> ]
  ];

  (* A return type. *)
  return_type: [
    [ "err" -> <:expr< Wrappi_types.RErr >> ]
  | [ t = any_type -> <:expr< Wrappi_types.Return $t$ >> ]
  ];

  (* A single function parameter. *)
  parameter: [[ t = any_type; name = LIDENT -> (name, t) ]];

  str_item: LEVEL "top" [
    [ "entry_point";
      return_type = return_type; name = LIDENT;
      "("; parameters = LIST0 parameter SEP ","; ")";
      code = OPT [ code = expr -> code ] ->
      add_entry_point _loc name parameters return_type code
    ]
  ];

END