Crate rotate_enum

rotate-enum crate

This crate provides a simple macro that implements prev() and next() methods to an enum.

Motivation

Sometimes you define an enum like this

enum Direction {
    Up,
    Left,
    Down,
    Right,
}

and you want to rotate them in some logic,

let up = Direction::Up;
let left = Direction::Left;
let down = Direction::Down;
let right = Direction::Right;
 
assert!(up.next() == left);
assert!(left.next() == down);
assert!(down.next() == right);
assert!(right.next() == up);
 
assert!(up.prev() == right);
assert!(left.prev() == up);
assert!(down.prev() == left);
assert!(right.prev() == down);

You can of course implement these methods manually, but it's repetitive and error prone. Don't you think it should be automated? This crate provides a RotateEnum derive macro to just do this.

Usage

use rotate_enum::RotateEnum;
 
#[derive(RotateEnum)]
enum Direction {
    Up,
    Left,
    Down,
    Right,
}

Derive Macros

RotateEnum

This derive macro will implement next() and prev() methods to the annotated enum.