diff options
Diffstat (limited to 'discocaml/util.ml')
| -rw-r--r-- | discocaml/util.ml | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/discocaml/util.ml b/discocaml/util.ml new file mode 100644 index 0000000..9c70a1a --- /dev/null +++ b/discocaml/util.ml @@ -0,0 +1,19 @@ +let break_to_subscript (s : string) : (string * int) option = + let rec loop (i : int) : (string * int) option = + if i < 0 then None + else + let ch = String.get s i in + if '0' <= ch && ch <= '9' then loop (i - 1) + else + let name = String.sub s 0 (i + 1) + and sub = String.sub s (i + 1) (String.length s - i - 1) in + if sub = "" then None + else int_of_string_opt sub |> Option.map (fun i -> (name, i)) + in + loop (String.length s - 1) + +let%test "break_to_subscript fail" = break_to_subscript "x1y" = None +let%test "break_to_subscript simple" = break_to_subscript "x1" = Some ("x", 1) +let%test "break_to_subscript empty" = break_to_subscript "" = None +let%test "break_to_subscript number" = break_to_subscript "123" = None +let%test "break_to_subscript multi" = break_to_subscript "x12" = Some ("x", 12) |