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module Field = struct
type 'a result = ('a, string) Result.t
type 'a parser = string -> 'a result
open Result.Monad_infix
let exn_validate f x msg =
try Ok (f x)
with _ -> Error msg
let int s =
exn_validate Int.of_string s "Expected integer value"
let positive_int s =
int s >>= fun i ->
if i >= 0 then Ok i
else Error "Expected positive integer value"
let bounded_int ~lo ~hi s =
int s >>= fun i ->
if i >= lo && i <= hi then Ok i
else
let msg = Printf.sprintf "Expected integer value between %d and %d" lo hi in
Error msg
let string_with_no_sep s =
if String.contains s '\n' || String.contains s '\t' then
let msg = "Expected string without tab or newline character" in
Error msg
else
Ok s
let parse ?(ctx = "<unknown>") f s =
match f s with
| Ok _ as r -> r
| Error msg ->
let msg = Printf.sprintf "Field %s is incorrect: %s" ctx msg in
Error msg
let parse_all ?ctx f xs =
parse ?ctx (fun xs -> Result.all (List.map xs ~f)) xs
end