Initial import.

1 files changed, 71 insertions, 0 deletions

diff --git a/src/numeric.ml b/src/numeric.ml
new file mode 100644
index 0000000..12ea04c
--- /dev/null
+++ b/src/numeric.ml
@@ -0,0 +1,71 @@
+type options = {
+  positive: bool;
+  nonnegative: bool;
+  ranges: string list;
+}
+
+let default_opts = {
+  positive = false;
+  nonnegative = false;
+  ranges = []
+}
+
+let int_of_string = Big_int.big_int_of_string
+let int_of_string_opt = Big_int.big_int_of_string_opt
+let big = Big_int.big_int_of_int
+let (>=) = Big_int.ge_big_int
+let (<=) = Big_int.le_big_int
+
+let opts = ref default_opts
+
+let number_arg = ref ""
+
+let args = [
+    ("--non-negative", Arg.Unit (fun () -> opts := {!opts with nonnegative=true}), "Check if the number is non-negative (>= 0)");
+    ("--positive", Arg.Unit (fun () -> opts := {!opts with positive=true}), "Check if the number is positive (> 0)");
+    ("--range", Arg.String (fun s -> let optsv = !opts in opts := {optsv with ranges=(s :: optsv.ranges)}), "Check if the number is within a range (inclusive)");
+]
+let usage = Printf.sprintf "Usage: %s [OPTIONS] <number>" Sys.argv.(0)
+
+let () = if Array.length Sys.argv = 1 then (Arg.usage args usage; exit 1)
+let () = Arg.parse args (fun s -> number_arg := s) usage
+
+let check_nonnegative opts n =
+  if opts.nonnegative && (n < (big 0)) then
+  failwith "Number should be non-negative."
+
+let check_positive opts n =
+  if opts.positive && (n <= (big 0)) then
+  failwith "Number should be positive"
+
+let number_of_string s =
+  let n = int_of_string_opt s in
+  match n with
+  | Some n -> n
+  | None ->
+     Printf.ksprintf failwith "'%s' is not a valid integer number" s
+
+let range_of_string s =
+  let rs = String.split_on_char '-' s |> List.map String.trim |> List.map int_of_string_opt in
+  match rs with
+  | [Some l; Some r] -> (l, r)
+  | _ -> Printf.ksprintf failwith "'%s' is not a valid number range" s
+
+let check_ranges ranges n =
+  let in_range (l, r) n = (n >= l) && (n <= r) in
+  let res = List.fold_left (fun acc r -> acc || (in_range r n)) false ranges in
+  if not res then
+  Printf.ksprintf failwith "Number is not in any of allowed ranges"
+
+let () = try
+  let opts = !opts in
+  let n = number_of_string !number_arg in
+  check_nonnegative opts n;
+  check_positive opts n;
+  if opts.ranges <> [] then
+    let ranges = List.map range_of_string opts.ranges in
+    check_ranges ranges n
+with (Failure err) ->
+  print_endline err;
+  exit 1
+