safe-discriminant

safe-discriminant provides a minimalistic, no_std compatible trait and procedural macro for extracting discriminants from enums at zero cost. It automatically generates unsafe { ... } blocks, ensuring semantic safety so you don’t have to worry about it.

Installation

This crate is available on crates.io and can be easily included in your project by:

• Adding the following line to your Cargo.toml:

  [dependencies]
  safe-discriminant = "0.2.0"
  

• Or runing this command in your cargo project:

  $ cargo add safe-discriminant
  

Usage

use safe_discriminant::Discriminant;

#[derive(Discriminant)]
#[repr(i64)]
pub enum Foo<T> {
    A = 1,
    B(T) = -1,
    C { fst: T, snd: T } = -2,
}

fn main() {
    let a: Foo<u8> = Foo::A;
    let b = Foo::B(5);
    let c = Foo::C { fst: 2, snd: 3 };
    assert_eq!(a.discriminant(), 1);
    assert_eq!(b.discriminant(), -1);
    assert_eq!(c.discriminant(), -2);
}

Similar Projects

• strum provides a collection of macros designed to simplify working with enums. Among these macros is EnumDiscriminants, which extracts the name of each variant from the enum and organizes them into a separate enum.