errors.ml

open Ast

exception Typing_error of label*string

let typing_error lbl reason =
  raise (Typing_error (lbl,reason))

let make_label startpos endpos =
  let sp = startpos.Lexing.pos_bol in
  {file=(startpos.Lexing.pos_fname);
    line=(startpos.Lexing.pos_lnum);
    cbegin=(startpos.Lexing.pos_cnum - sp);
    cend=(endpos.Lexing.pos_cnum - sp)} 

let string_of_label lb =
  let cend = (if lb.cbegin < lb.cend then lb.cend else lb.cbegin+1) in
  Format.sprintf "File %s, line %d, characters %d-%d:\n"
    lb.file
    lb.line
    lb.cbegin
    cend