Crate cenum_utils

  

cenum_utils provides a minimal set of traits and (optionally) derive macros providing const access to certain enum properties.

Currently this includes:

• EnumCount — Variant counts.
• EnumDiscriminants — Variant discriminants.
• EnumNames — Variant names.

Unfortunately, due to rust’s currently lack of const trait support, actually interacting with some of the features this crate provides in const contexts can be somewhat difficult.

Example

use cenum_utils::*;

#[derive(ConstEnum)]
#[repr(u8)]
enum Enum {
	X,
	Y,
	Z
}

fn test() {
	assert_eq!(Enum::COUNT, 3);
	assert_eq!(Enum::DISCRIMINANTS, &[0, 1, 2]);
	assert_eq!(Enum::NAMES, &["X", "Y", "Z"])
}

const fn const_test() {
	assert!(Enum::COUNT == 3);

	static NAMES: &[u8] = &[b'X', b'Y', b'Z'];

	let mut i = 0;

	while i < Enum::COUNT {
		assert!(Enum::DISCRIMINANTS[i] as usize == i);
		assert!(Enum::NAMES[i].as_bytes()[0] == NAMES[i]);
		i += 1;
	}
}

Features

• derive (enabled by default) — Derive macros for the core traits provided by this crate.

Traits

EnumCount

A trait providing access to the number of enum variants a type contains.

EnumDiscriminants

A trait providing access to the discriminants of an enum’s variants.

EnumNames

A trait providing access to the names of an enum’s variants.

Derive Macros

ConstEnumderive

Derives EnumCount and EnumNames, as well as EnumDiscriminants if the enum has a valid primitive repr type.