Простой парсер /etc/passwd файла с помошью парсеров-комбинаторов

simple_angstrom_passwd_parser.ml

(* Простой парсер /etc/passwd файла с помошью парсеров-комбинаторов.

   utop # Passwd.user_of_string "dx3mod:x:1000:1000:Михаил:/home/dx3mod:/usr/bin/fish";;
   - : Passwd.user =
    {Passwd.name = "dx3mod"; hash = Passwd.Hide; uid = 1000; gid = 1000;
     description = "Михаил"; home = "/home/dx3mod"; shell = "/usr/bin/fish"}

   utop # let passwd_contents = In_channel.(with_open_text "/etc/passwd" input_all);;
   utop # Passwd.of_string passwd_contents;;
   - : Passwd.user list =
     [ ... ]
*)

type user = {
  name : string;
  hash : hash;
  uid : int;
  gid : int;
  description : string;
  home : string;
  shell : string;
}

and hash = Hidden | Hash of string

module P = struct
  open Angstrom

  let id =
    take_while1 (function '0' .. '9' -> true | _ -> false) >>| int_of_string

  let user =
    let field p = p <* char ':' in
    let text = take_while (( <> ) ':') <|> return "" in

    let+ name = field text
    and+ hash = field text >>| function "x" -> Hidden | hash -> Hash hash
    and+ uid = field id
    and+ gid = field id
    and+ description = field text
    and+ home = field text
    and+ shell = take_while (( <> ) '\n')
    and+ _ = option () end_of_line in

    { name; hash; uid; gid; description; home; shell }

  let file = many user
end

let user_of_string s =
  Angstrom.(parse_string ~consume:Consume.All P.user s) |> Result.get_ok

let of_string s =
  Angstrom.(parse_string ~consume:Consume.All P.file s) |> Result.get_ok