ok amount

src/amount.ml

@@ -3,6 +3,8 @@
    and specialize amount.ml to Config.currency??
 
    have safe amount arithmetic *)
+open Syntax
+
 type sign =
   | Sign_plus
   | Sign_minus
@@ -14,14 +16,15 @@ type t = {
   fraction: Int32.t;
 }
 
-let maximum_currency_length = 11
+let currency_length_limit = 12
-let value_upper_bound = Int64.of_float @@ Float.pow 2. 52.
+let value_limit = Int64.add 1_L (Int64.of_float (Float.pow 2. 52.))
-let fraction_max_number_of_digits = 8
+let fraction_nb_digits = 8
 
-(* TODO choose to either include or exclude upper limit for all bounds
+let fraction_limit =
-   need a -1 here *)
+  Int32.of_float (Float.pow 10. (Int.to_float fraction_nb_digits))
-let fraction_upper_bound =
+
-  Int32.of_float @@ Float.pow 10. (Int.to_float fraction_max_number_of_digits)
+let is_letter = function 'a' .. 'z' | 'A' .. 'Z' -> true | _ -> false
+let is_digit = function '0' .. '9' -> true | _ -> false
 
 let check_currency s =
   if not @@ String.for_all is_letter s then
@@ -29,28 +32,28 @@ let check_currency s =
   else
     let len = String.length s in
     if len = 0 then Error "currency is empty string"
-    else if len > maximum_currency_length then
+    else if len < currency_length_limit then Ok ()
-      Fmt.error "currency is more than %d characters long"
+    else
-        maximum_currency_length
+      Fmt.error "currency is more than %d characters long" currency_length_limit
-    else Ok ()
 
 let check_value v =
-  if Int64.unsigned_compare v value_upper_bound > 0 then
+  if Int64.unsigned_compare v value_limit < 0 then Ok ()
-    Error "value is greater than 2^52"
+  else Error "value is greater than 2^52"
-  else Ok v
 
 let check_fraction v =
-  if Int32.unsigned_compare v fraction_upper_bound > 0 then
+  if Int32.unsigned_compare v fraction_limit < 0 then Ok ()
-    Fmt.error "fraction has more than %d digits" fraction_max_number_of_digits
+  else Fmt.error "fraction has more than %d digits" fraction_nb_digits
-  else Ok v
 
 let make ~sign ~currency ~value ~fraction =
+  let* () = check_currency currency in
+  let* () = check_value value in
+  let* () = check_fraction fraction in
+  let currency = String.uppercase_ascii currency in
   Ok { sign; currency; value; fraction }
 
+module Parser = struct
   open Angstrom
 
-let is_letter = function 'a' .. 'z' | 'A' .. 'Z' -> true | _ -> false
-let is_digit = function '0' .. '9' -> true | _ -> false
   let letters = take_while1 is_letter
   let digits = take_while1 is_digit
 
@@ -62,75 +65,85 @@ let sign =
         return None;
       ]
 
-let currency_of_string s =
+  let value =
-  if not @@ String.for_all is_letter s then
+    digits >>= fun s ->
-    Error "currency contains forbidden character"
-  else if String.length s > maximum_currency_length then
-    Fmt.error "currency is more than %d characters long" maximum_currency_length
-  else Ok (String.uppercase_ascii s)
-
-let value_of_string s =
-  if not @@ String.for_all is_digit s then
-    Error "value contains forbidden character"
-  else
     match Int64.of_string_opt s with
-    | None -> Error "value is not a valid integer"
+    | None -> fail "not a valid int64"
-    | Some v ->
+    | Some n -> return n
-        if v > value_upper_bound then Error "value is greater than 2^52"
-        else if v < Int64.zero then Error "value is negative"
-        else Ok v
 
-let fraction_of_string s =
+  let fraction =
-  if not @@ String.for_all is_digit s then
+    digits >>= fun s ->
-    Error "fraction contains forbidden character"
+    let len = String.length s in
-  else if String.length s > fraction_max_number_of_digits then
+    match len <= fraction_nb_digits with
-    Fmt.error "fraction has more than %d digits" fraction_max_number_of_digits
+    | false ->
-  else
+        fail (Fmt.str "fraction has more than %d digits" fraction_nb_digits)
+    | true -> (
         match Int32.of_string_opt s with
-    | None -> Error "fraction is not a valid integer"
+        | None -> fail "not a valid int32"
-    | Some v -> if v < Int32.zero then Error "fraction is negative" else Ok v
+        | Some n ->
+            let magnitude =
+              let exp = Int.to_float (fraction_nb_digits - len) in
+              Int32.of_float @@ Float.pow 10. exp
+            in
+            let n = Int32.mul n magnitude in
+            return n)
 
   let amount =
     lift4
       (fun sign currency value fraction ->
-      let open Syntax in
+        make ~sign ~currency ~value ~fraction)
-      let* currency = currency_of_string currency in
-      let* value = value_of_string value in
-      let* fraction = fraction_of_string fraction in
-      Ok { sign; currency; value; fraction })
       sign letters
-    (char ':' *> digits)
+      (char ':' *> value)
-    (option "" (char '.' *> digits))
+      (option 0_l (char '.' *> fraction))
     <* end_of_input
 
-let of_string s = parse_string ~consume:Consume.All amount s |> Result.join
+  let parse s =
+    Angstrom.parse_string ~consume:Consume.All amount s |> Result.join
+end
+
+let of_string = Parser.parse
 
 let pp =
   let open Fmt in
-  let pp_sign ppf = function
+  let pp_sign =
+    let pp ppf = function
       | Sign_plus -> char ppf '+'
       | Sign_minus -> char ppf '-'
     in
+    Fmt.option pp
+  in
+  let rec rm_trailing_zeros count x =
+    if x <> 0_l && Int32.rem x 10_l = 0_l then
+      rm_trailing_zeros (succ count) (Int32.div x 10_l)
+    else (count, x)
+  in
+  let pp_fraction ppf fraction =
+    match fraction = 0_l with
+    | true -> Fmt.nop ppf ()
+    | false ->
+        let count, x = rm_trailing_zeros 0 fraction in
+        let nb_leading_zeros = fraction_nb_digits - count in
+        pf ppf ".%0*lu" nb_leading_zeros x
+  in
   fun ppf { sign; currency; value; fraction } ->
-    (* TODO
+    pf ppf "%a%s:%Lu%a" pp_sign sign currency value pp_fraction fraction
-       depends on the currency's number of fraction digits *)
-    pf ppf "%a%s:%Lu.%02lu" (Fmt.option pp_sign) sign currency value fraction
 
 let to_string = Fmt.str "%a" pp
 
 (* - *)
 
 let jsont = Jsont.of_of_string ~kind:"Amount" of_string ~enc:to_string
-let currency_length = 12
 
 let pad_currency_string s =
   let len = String.length s in
-  assert (len < currency_len);
+  match len < currency_length_limit with
-  let b = Bytes.make 12 '\x00' in
+  | false -> Fmt.failwith "amount with invalid currency"
+  | true ->
+      let b = Bytes.make currency_length_limit '\x00' in
       Bytes.blit_string s 0 b 0 len;
-  Bytes.to_string b
+      Bytes.unsafe_to_string b
 
-(* binary decoding unused? *)
+(* binary decoding never unused *)
 let make_exn value fraction currency =
   match make ~sign:None ~currency ~value ~fraction with
   | Error _ -> Fmt.failwith "Amount of binary data failure"
@@ -140,6 +153,7 @@ let bin =
   let open Bin in
   record make_exn
   |+ field beint64 (fun t -> t.value)
-  |+ field beint32 (fun t -> Int32.mul t.fraction 1_000_000_l)
+  |+ field beint32 (fun t -> t.fraction)
-  |+ field (bytes currency_len) (fun t -> pad_currency_string t.currency)
+  |+ field (bytes currency_length_limit) (fun t ->
+      pad_currency_string t.currency)
   |> sealr

test/test.ml

@@ -35,14 +35,9 @@ let () =
   check_bad Timestamp.jsont {|{"t_s": "123456780"}|};
   check_bad Timestamp.jsont {|{"t_s": "agagou"}|};
 
-  (* CS not implemented *)
+  (* TODO CS not implemented *)
   check_bad DenominationKey.jsont
     {|{"cipher": "CS", "age_mask": 18, "cs_pub": "ouhagag"}|};
-
-  (* TODO test with a valid rsa_pub value *)
-  (* TODO handle "rsa pub_of_octets failure" correctly *)
-  (* check_bad DenominationKey.jsont
-    {|{"cipher": "RSA", "age_mask": 18, "rsa_pub": "agagouh"}|}; *)
   ()
 
 let () =