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Add Float.toFixed and friends #142

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Add Float.toFixed and friends #142

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a468b75
add Float.toFixed and friends
jchavarri Jun 27, 2024
6590eb2
add more tests
jchavarri Jun 27, 2024
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72 changes: 68 additions & 4 deletions packages/melange.js/Js.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -1593,9 +1593,45 @@ end = struct
let _NaN = Stdlib.Float.nan
let isNaN float = Stdlib.Float.is_nan float
let isFinite float = Stdlib.Float.is_finite float
let toExponential ?digits:_ _ = notImplemented "Js.Float" "toExponential"
let toFixed ?digits:_ _ = notImplemented "Js.Float" "toFixed"
let toPrecision ?digits:_ _ = notImplemented "Js.Float" "toPrecision"

let remove_leading_zeros s =
(* Remove leading zero in the exponent part *)
let regex = Str.regexp "e\\([+-]\\)0" in
Str.global_replace regex "e\\1" s

let toExponential ?digits n =
let result =
match digits with
| None -> Printf.sprintf "%e" n
| Some d ->
if d < 0 || d > 100 then
invalid_arg
"the digits argument passed to toFixed must be between 0 and 100";

Printf.sprintf "%.*e" d n
in
remove_leading_zeros result

let toFixed ?(digits = 0) n =
if digits < 0 || digits > 100 then
invalid_arg
"the digits argument passed to toFixed must be between 0 and 100";
let factor = 10.0 ** float_of_int digits in
let rounded = Float.round (n *. factor) in
Printf.sprintf "%.*f" digits (rounded /. factor)

let toPrecision ?digits n =
let result =
match digits with
| None -> Printf.sprintf "%g" n
| Some d ->
if d < 0 || d > 100 then
invalid_arg
"the digits argument passed to toPrecision must be between 0 and \
100";
Printf.sprintf "%.*g" d n
in
remove_leading_zeros result

let toString ?radix f =
match radix with
Expand All @@ -1607,7 +1643,35 @@ end = struct
if Stdlib.Float.equal (Stdlib.Float.round f) f then
f |> int_of_float |> string_of_int
else Printf.sprintf "%g" f
| Some _ -> notImplemented "Js.Float" "toString ~radix"
| Some radix ->
let module String = Stdlib.String in
if radix < 2 || radix > 36 then
invalid_arg "radix must be between 2 and 36";

let digits = "0123456789abcdefghijklmnopqrstuvwxyz" in

let rec int_to_radix n =
if n < radix then String.make 1 digits.[n]
else int_to_radix (n / radix) ^ String.make 1 digits.[n mod radix]
in

let rec frac_to_radix frac precision =
if precision = 0 then ""
else
let whole_part = int_of_float (frac *. float_of_int radix) in
String.make 1 digits.[whole_part]
^ frac_to_radix
((frac *. float_of_int radix) -. float_of_int whole_part)
(precision - 1)
in

let int_part = int_of_float f in
let frac_part = abs_float (f -. float_of_int int_part) in
let sign = if f < 0. then "-" else "" in

if frac_part = 0. then sign ^ int_to_radix (abs int_part)
else
sign ^ int_to_radix (abs int_part) ^ "." ^ frac_to_radix frac_part 12

let fromString = Stdlib.float_of_string
end
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10 changes: 0 additions & 10 deletions packages/melange.js/Js.mli
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Expand Up @@ -1290,19 +1290,9 @@ module Float : sig
val _NaN : float
val isNaN : float -> bool
val isFinite : float -> bool

val toExponential : ?digits:int -> t -> string
[@@alert
not_implemented "is not implemented in native under server-reason-react.js"]

val toFixed : ?digits:int -> t -> string
[@@alert
not_implemented "is not implemented in native under server-reason-react.js"]

val toPrecision : ?digits:int -> t -> string
[@@alert
not_implemented "is not implemented in native under server-reason-react.js"]

val toString : ?radix:int -> t -> string
val fromString : string -> float
end
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48 changes: 47 additions & 1 deletion packages/melange.js/test.ml
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Expand Up @@ -516,7 +516,53 @@ let float_tests =
assert_string (Js.Float.toString 80.0) "80";
assert_string (Js.Float.toString 80.) "80";
assert_string (Js.Float.toString 80.0001) "80.0001";
assert_string (Js.Float.toString 80.00000000001) "80");
assert_string (Js.Float.toString 80.00000000001) "80";
assert_string (Js.Float.toString 123.456) "123.456";
assert_string (Js.Float.toString ~radix:2 10.) "1010";
assert_string (Js.Float.toString ~radix:16 255.) "ff";
assert_string (Js.Float.toString ~radix:8 8.) "10";
assert_string (Js.Float.toString ~radix:16 255.1231) "ff.1f837b4a2338";
(* todo: javascript is actually "1010.0001111010111000010100011110101110000101000111101" *)
assert_string (Js.Float.toString ~radix:2 10.12) "1010.000111101011";
assert_string (Js.Float.toString ~radix:2 0.) "0";
assert_string (Js.Float.toString ~radix:16 0.) "0";
assert_string (Js.Float.toString ~radix:8 0.) "0";
assert_string (Js.Float.toString ~radix:36 12345.) "9ix";
assert_string (Js.Float.toString ~radix:10 1000000.) "1000000";
assert_string (Js.Float.toString ~radix:2 255.) "11111111");
test "toExponential" (fun () ->
assert_string (Js.Float.toExponential ~digits:2 0.005) "5.00e-3";
assert_string (Js.Float.toExponential ~digits:5 12345.6789) "1.23457e+4";
assert_string
(Js.Float.toExponential 12345.6789)
(* todo: javascript is actually "1.23456789e+4" *) "1.234568e+4";
assert_string (Js.Float.toExponential ~digits:1 12345.6789) "1.2e+4";
assert_string (Js.Float.toExponential ~digits:2 0.0001234) "1.23e-4";
assert_string (Js.Float.toExponential ~digits:3 1e-10) "1.000e-10";
assert_string (Js.Float.toExponential ~digits:6 1e+20) "1.000000e+20");
test "toFixed" (fun () ->
assert_string (Js.Float.toFixed ~digits:0 123.456) "123";
assert_string (Js.Float.toFixed ~digits:2 123.456) "123.46";
assert_string (Js.Float.toFixed ~digits:5 123.456) "123.45600";
assert_string (Js.Float.toFixed 123.456) "123";
assert_string (Js.Float.toFixed ~digits:3 0.0001234) "0.000";
assert_string (Js.Float.toFixed ~digits:2 1000000.0) "1000000.00";
assert_string (Js.Float.toFixed ~digits:10 1.23456789) "1.2345678900");
test "toPrecision" (fun () ->
assert_string (Js.Float.toPrecision ~digits:4 12345.6789) "1.235e+4";
assert_string (Js.Float.toPrecision ~digits:2 0.00123) "0.0012";
assert_string (Js.Float.toPrecision ~digits:6 12345.6789) "12345.7";
assert_string (Js.Float.toPrecision ~digits:9 12345.6789) "12345.6789";
assert_string
(Js.Float.toPrecision 12345.6789)
(* todo: javascript is "12345.6789" *) "12345.7";
assert_string
(Js.Float.toPrecision ~digits:10 1.23456789)
(* todo: javascript is "1.234567890" *) "1.23456789";
assert_string
(Js.Float.toPrecision ~digits:2 1000000.0)
(* todo: javascript is "1.0e+6" *) "1e+6";
assert_string (Js.Float.toPrecision ~digits:1 1.23456789) "1");
]

let () =
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