ext_js_regex.ml

(* Copyright (C) 2015-2016 Bloomberg Finance L.P.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * In addition to the permissions granted to you by the LGPL, you may combine
 * or link a "work that uses the Library" with a publicly distributed version
 * of this file to produce a combined library or application, then distribute
 * that combined work under the terms of your choosing, with no requirement
 * to comply with the obligations normally placed on you by section 4 of the
 * LGPL version 3 (or the corresponding section of a later version of the LGPL
 * should you choose to use a 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)


let check_from_end al =
  let rec aux l seen =
    match l with
    | [] -> false
    | (e::r) ->
      if e < 0 || e > 255 then false
      else (let c = Char.chr e in
            if c = '/' then true
            else (if Ext_list.exists seen (fun x -> x = c)  then false (* flag should not be repeated *)
                  else (if c = 'i' || c = 'g' || c = 'm' || c = 'y' || c ='u' then aux r (c::seen) 
                        else false)))
  in aux al []

let js_regex_checker s =
  match Ext_utf8.decode_utf8_string s with 
  | [] -> false 
  | 47 (* [Char.code '/' = 47 ]*)::tail -> 
    check_from_end (List.rev tail)       
  | _ :: _ -> false 
  | exception Ext_utf8.Invalid_utf8 _ -> false