(* Title: Pure/ML/ml_parse.ML
ID: $Id$
Author: Makarius
Minimal parsing for SML -- fixing integer numerals.
*)
signature ML_PARSE =
sig
val fix_ints: string -> string
end;
structure ML_Parse: ML_PARSE =
struct
structure T = ML_Lex;
(** error handling **)
fun !!! scan =
let
fun get_pos [] = " (past end-of-file!)"
| get_pos (tok :: _) = T.pos_of tok;
fun err (toks, NONE) = "SML syntax error" ^ get_pos toks
| err (toks, SOME msg) = "SML syntax error" ^ get_pos toks ^ ": " ^ msg;
in Scan.!! err scan end;
fun bad_input x =
(Scan.some (fn tok => (case T.kind_of tok of T.Error msg => SOME msg | _ => NONE)) :|--
(fn msg => Scan.fail_with (K msg))) x;
(** basic parsers **)
fun $$$ x =
Scan.one (fn tok => T.kind_of tok = T.Keyword andalso T.content_of tok = x) >> T.content_of;
val int = Scan.one (fn tok => T.kind_of tok = T.Int) >> T.content_of;
val regular = Scan.one T.is_regular >> T.content_of;
val improper = Scan.one T.is_improper >> T.content_of;
val blanks = Scan.repeat improper >> implode;
(* fix_ints *)
(*approximation only -- corrupts numeric record field patterns *)
val fix_int =
$$$ "#" ^^ blanks ^^ int ||
($$$ "infix" || $$$ "infixr") ^^ blanks ^^ int ||
int >> (fn x => "(" ^ x ^ ":int)") ||
regular ||
bad_input;
fun do_fix_ints s =
Source.of_string s
|> T.source
|> Source.source T.stopper (Scan.bulk (!!! fix_int)) NONE
|> Source.exhaust
|> implode;
val fix_ints = if ml_system_fix_ints then do_fix_ints else I;
end;