init

lib/dune

@@ -0,0 +1,3 @@
+(library
+ (name inshellah_parser)
+ (libraries angstrom angstrom-unix))

lib/parser.ml

@@ -0,0 +1,77 @@
+(* open Angstrom_unix *)
+(* also look for "subcommands" for clapslop *)
+(* and other common help patterns *)
+open Angstrom
+
+let ( <| ) = ( @@ )
+let ( <&> ) p1 p2 = lift2 (fun a b -> (a, b)) p1 p2
+let is_whitespace = function ' ' | '\t' | '\n' | '\r' -> true | _ -> false
+
+let is_alphanumeric = function
+  | 'A' .. 'Z' | 'a' .. 'z' | '0' .. '9' -> true
+  | _ -> false
+
+let is_long_char = function
+  | 'A' .. 'Z' | 'a' .. 'z' | '0' .. '9' | '-' -> true
+  | _ -> false
+
+type switch = Short of char | Long of string | Both of char * string
+type param = Mandatory of string | Optional of string
+type entry = { switch : switch; param : param option; desc : string }
+
+let whitespace = skip_while is_whitespace
+let comma = char ',' *> whitespace
+let short_switch = char '-' *> satisfy is_alphanumeric
+let long_switch = string "--" *> take_while1 is_long_char
+
+let opt_param =
+  print_endline "opt param is running";
+  string "[=" *> take_while is_alphanumeric <* char ']' >>| fun a -> Optional a
+
+let man_param =
+  print_endline "man param is running";
+  char '=' *> take_while is_alphanumeric >>| fun a -> Mandatory a
+
+let param_parser =
+  option None (choice [ opt_param; man_param ] >>| fun a -> Some a)
+
+let switch_parser =
+  choice
+    [
+      (* -a, --all *)
+      ( short_switch >>= fun s ->
+        comma *> long_switch >>| fun l -> Both (s, l) );
+      (* -a *)
+      (short_switch >>| fun s -> Short s);
+      (* --all *)
+      (long_switch >>| fun l -> Long l);
+    ]
+
+let description = whitespace *> take_till (fun c -> c = '\n') <* end_of_line
+
+let entry =
+  skip_while (fun c -> c <> '-')
+  *> lift3 (fun a b c -> (a, b, c)) switch_parser param_parser description
+  >>| fun (switch, param, desc) -> { switch; param; desc }
+
+let endline = option () (char '\n' *> return ())
+let entry_line = entry <* endline
+let help_parser = many entry_line
+
+let parse_help txt =
+  Angstrom.parse_string ~consume:Consume.Prefix help_parser txt
+
+let print_switch = function
+  | Short o -> Printf.sprintf "Short: %c" o
+  | Long o -> Printf.sprintf "Long: %s" o
+  | Both (s, l) -> Printf.sprintf "Both, short: %c long: %s" s l
+
+let print_opt = function
+  | Some (Mandatory o) -> Printf.sprintf "Mandatory: %s" o
+  | Some (Optional o) -> Printf.sprintf "Optional: %s" o
+  | None -> "None"
+
+let print_entry e =
+  Printf.printf
+    "\n\t** ENTRY **\n\tSwitch: %s\n\tParam: %s\n\tDescription: %s\n"
+    (print_switch e.switch) (print_opt e.param) e.desc