open Lexing
open Types

let loc_from_lexpos pstart pend =
  let (fname, ystart, xstart) = begin
    pstart.pos_fname,
    pstart.pos_lnum,
    (pstart.pos_cnum - pstart.pos_bol + 1)
  end in
  (fname, ystart, xstart)

let loc_msg lexbuf msg =
  let p = lexbuf.lex_curr_p in
  let y = p.pos_lnum in
  let x = p.pos_cnum - p.pos_bol in
  Printf.sprintf "%s at line %d, character %d" msg y x

let parse_with_error lexbuf =
  try Parser.program Lexer.token lexbuf with
  | Lexer.Syntax_error msg ->
    raise (Fatal_error (loc_msg lexbuf msg))
  | Parser.Error ->
    raise (Fatal_error (loc_msg lexbuf "syntax error"))