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FizzBrrr
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| defmodule FizzBuzz.Native do | |
| @moduledoc false | |
| use Rustler, otp_app: :fizz_buzz | |
| def classify(_nums), do: :erlang.nif_error(:nif_not_loaded) | |
| end |
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| defmodule FizzBuzz do | |
| @moduledoc "FizzBuzz classification backed by a Rust NIF." | |
| @typedoc "A divisibility label or the number itself." | |
| @type classification() :: :fizz | :buzz | :fizz_buzz | integer() | |
| @doc """ | |
| Classifies numbers by divisibility. | |
| ## Examples | |
| iex> FizzBuzz.classify([1, 3, 5, 15]) | |
| [1, :fizz, :buzz, :fizz_buzz] | |
| """ | |
| @spec classify([integer()]) :: [classification()] | |
| defdelegate classify(nums), to: FizzBuzz.Native | |
| end |
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| //! NIFs for `FizzBuzz` classification. | |
| use rustler::NifUnitEnum; | |
| use rustler::NifUntaggedEnum; | |
| /// A divisibility label. | |
| #[derive(NifUnitEnum)] | |
| enum Label { | |
| Fizz, | |
| Buzz, | |
| FizzBuzz, | |
| } | |
| /// Either a divisibility label or the number itself. | |
| #[derive(NifUntaggedEnum)] | |
| enum Classification { | |
| Divisible(Label), | |
| Indivisible(i64), | |
| } | |
| /// Classifies a number based on divisibility by 3 and 5. | |
| impl From<i64> for Classification { | |
| fn from(num: i64) -> Self { | |
| match (num % 3, num % 5) { | |
| (0, 0) => Self::Divisible(Label::FizzBuzz), | |
| (0, _) => Self::Divisible(Label::Fizz), | |
| (_, 0) => Self::Divisible(Label::Buzz), | |
| _ => Self::Indivisible(num), | |
| } | |
| } | |
| } | |
| /// Exposes `FizzBuzz.classify/1` as a NIF. | |
| /// | |
| /// Returns a list of integers, `:fizz`, `:buzz` and `:fizz_buzz` on the Elixir side. | |
| /// | |
| /// Pulls ahead of pure Elixir around a thousand elements by amortizing the NIF | |
| /// boundary cost. Runs on a dirty CPU scheduler so long lists won't block BEAM | |
| /// schedulers. | |
| #[rustler::nif(schedule = "DirtyCpu")] | |
| fn classify(nums: Vec<i64>) -> Vec<Classification> { | |
| nums.into_iter().map(Classification::from).collect() | |
| } | |
| rustler::init!("Elixir.FizzBuzz.Native"); |
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