comments searched on bit of ocaml code ...

[Sven Luther <sven.luther@wanadoo.fr>]

Hi, ...

I just quickly wrote a (probably quick and dirty) bit of ocaml code to parse
the kernel .config file, which i may hope to evolve into something more
advanced, which would handle the setting of all the debian
arch/subarch/flavour configs after checking and parsing versus the main kernel
Kconfig stuff. Lot of work to do, but the problem is quite interesting, having
to deal the per arch kernel dependency graph and the setting of options and
such.

Anyway, it has been a long time since i wrote serious ocaml code, and i have
some doubts about the best way to parse strings, preferably using the less
non-ocaml stuff, so i post my snipplet here for comments.

Friendly,

Sven Luther

#!/usr/bin/ocamlrun /usr/bin/ocaml

let config_name = ref ""

let () = Arg.parse
  [ ]
  (function s -> config_name := s) 
  "./kconfig.ml <config_file>"

let usage () = Arg.usage
  [ ]
  "./kconfig.ml <config_file>"

type options =
  | Config_Yes of string
  | Config_No of string
  | Config_Module of string
  | Config_Value of string * string
  | Config_Comment of string
  | Config_Empty

let print_option = function
  | Config_Yes s -> Printf.printf "CONFIG_%s=y\n" s
  | Config_No s -> Printf.printf "# CONFIG_%s is not set\n" s
  | Config_Module s -> Printf.printf "CONFIG_%s=m\n" s
  | Config_Value (s,v) -> Printf.printf "CONFIG_%s=%s\n" s v
  | Config_Comment s -> Printf.printf "#%s\n" s
  | Config_Empty -> Printf.printf "\n"
  
exception Comment
  
let parse_line fd =
  let line = input_line fd in
  let len = String.length line in
  if len = 0 then Config_Empty else
  try
    if len <= 9 then raise Comment else 
    match line.[0], line.[1], line.[2], line.[3], line.[4], line.[5], line.[6], line.[7], line.[8] with 
    | '#', ' ', 'C', 'O', 'N', 'F', 'I', 'G', '_' ->
      begin
        try
          let space = String.index_from line 8 ' ' in
	  if String.sub line (space + 1) 10 = "is not set" then 
	    let o = String.sub line 9 (space - 9) in
	    Config_No o
	  else raise Comment
        with Not_found | Invalid_argument "String.sub" -> raise Comment
      end
    | '#', _, _, _, _, _, _, _, _ -> raise Comment
    | 'C', 'O', 'N', 'F', 'I', 'G', _, _, _ ->
      begin
        try
          let equal = String.index_from line 6 '=' in
	  let o = String.sub line 7 (equal - 7) in
	  let v = String.sub line (equal + 1) (len - equal - 1) in
	  match v with
	  | "y" -> Config_Yes o
	  | "m" -> Config_Module o
	  | _ -> Config_Value (o,v)
        with Not_found | Invalid_argument "String.sub" -> raise Comment
      end
    | _ -> raise Comment
  with Comment -> Config_Comment (String.sub line 1 (len - 1))

let rec parse_config fd =
  try 
    print_option (parse_line fd);
    parse_config fd
  with End_of_file -> ()
  
let () =
  if !config_name = "" then usage () else
  try
    let config = open_in !config_name in
    parse_config config
  with Sys_error s -> Printf.printf "Error: %s\n" s