Source file parse_fuzzy.ml

(* Yoann Padioleau
 *
 * Copyright (C) 2013 Facebook
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * version 2.1 as published by the Free Software Foundation, with the
 * special exception on linking described in file license.txt.
 * 
 * This library 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 file
 * license.txt for more details.
 *)
open Common

module PI = Parse_info

(*****************************************************************************)
(* Prelude *)
(*****************************************************************************)
(* A few helpers function to build Ast_fuzzy tree from a list of tokens.
 * It factorizes the language-independent part of those AST fuzzy builder.
 *)

(*****************************************************************************)
(* Types *)
(*****************************************************************************)

type 'tok hooks = {
  kind: 'tok -> Parse_info.token_kind;
  tokf: 'tok -> Parse_info.info;
}

exception Unclosed of string * Parse_info.info (* starting point *)

(*****************************************************************************)
(* Helpers *)
(*****************************************************************************)
let char_of_token_kind = function
 | PI.RAngle -> '>'
 | PI.RBracket -> ']'
 | PI.RBrace -> '}'
 | _ -> raise (Impossible)

(*****************************************************************************)
(* Entry point *)
(*****************************************************************************)

(*
 * less: I should also factorize with Parse_cpp.parse_fuzzy. 
 * put here also generic parts of  token_views_of_xxx?
 * 
 * less: check that it's consistent with the indentation? 
 * less: more fault tolerance? if col == 0 and { then reset?
 *)

let mk_trees h xs =

 (* filter comment tokens *)
  let xs = xs +> Common.exclude (fun t ->
      let kind = h.kind t in
      match kind with
      | PI.Esthet _ | PI.Eof -> true
      | _ -> false
  )
  in

  let rec consume x xs =
    match x with
    | tok when h.kind tok = PI.LBrace -> 
        let body, closing, rest = look_close PI.RBrace x [] xs in
        Ast_fuzzy.Braces (h.tokf x, body, h.tokf closing), rest
    | tok when h.kind tok = PI.LBracket -> 
        let body, closing, rest = look_close PI.RBracket x [] xs in
        Ast_fuzzy.Bracket (h.tokf x, body, h.tokf closing), rest
    | tok when h.kind tok = PI.LAngle -> 
        let body, closing, rest = look_close PI.RAngle x [] xs in
        Ast_fuzzy.Angle (h.tokf x, body, h.tokf closing), rest
    | tok when h.kind tok = PI.LPar ->
        let body, closing, rest = look_close_paren x [] xs in
        let body' = split_comma body in
        Ast_fuzzy.Parens (h.tokf x, body', h.tokf closing), rest
    | tok -> 
      Ast_fuzzy.Tok (PI.str_of_info (h.tokf tok), h.tokf x), xs
(*
    (match Ast.str_of_info (tokext tok) with
    | "..." -> Ast_fuzzy.Dots (tokext tok)
    | s when Ast_fuzzy.is_metavar s -> Ast_fuzzy.Metavar (s, tokext tok)
    | s -> Ast_fuzzy.Tok (s, tokext tok)
*)
  
  and aux xs =
  match xs with
  | [] -> []
  | x::xs ->
      let x', xs' = consume x xs in
      x'::aux xs'

  and look_close close_kind tok_start accbody xs = 
    match xs with
    | [] -> 
        raise (Unclosed (spf "look_close '%c'"
                         (char_of_token_kind close_kind),
                         h.tokf tok_start))

    | x::xs -> 
        (match x with
        | tok when h.kind tok = close_kind -> 
          List.rev accbody, x, xs
        | _ -> let (x', xs') = consume x xs in
               look_close close_kind tok_start (x'::accbody) xs'
        )

  (* todo? diff with look_close PI.RPar ? *)
  and look_close_paren tok_start accbody xs =
    match xs with
    | [] -> 
        raise (Unclosed ("look_close_paren", h.tokf tok_start))
    | x::xs -> 
        (match x with
        | tok when h.kind tok = PI.RPar -> 
            List.rev accbody, x, xs
        | _ -> 
            let (x', xs') = consume x xs in
            look_close_paren tok_start (x'::accbody) xs'
        )

  and split_comma xs =
     let rec aux acc xs =
       match xs with
       | [] ->
         if null acc
         then []
         else [Left (acc +> List.rev)]
       | x::xs ->
         (match x with
         | Ast_fuzzy.Tok (",", info) ->
           let before = acc +> List.rev in
           if null before
           then aux [] xs
           else (Left before)::(Right (info))::aux [] xs
         | _ ->
           aux (x::acc) xs
         )
     in
     aux [] xs
  in
  aux xs