Seoul-Rs

Trait Isomorphism

• To handle enum data type. Convenient transformation of enum values with derive macro.

• Basic methods:

  • fn title(&self) -> String;
  • fn list() -> Vec<Self>;

• Using derive macro, also are implemented

  • Into<T> for Self and &Self
  • From<T> and From<&T> for Self (when Default is implemented and "has_default" syntax is given)

derive syntax and fallback

• When title is not given at variant level, the variant's name (Ident) will be used as titile.
• When list is not given at the top level attribute, list of each variant's default format will be returned.
• When into value is not given at variant level, the into type(T)'s default value will be used in <Into<T>> trait.
• When the type implements Default and has_default is given at top level attribute, the From<T> and From<&T> will be implemented for each given into types(T).

Examples

use seoul::Isomorphism;

#[derive(PartialEq, Debug, Isomorphism)]
#[isomorphism(u8, list=[A, B(10)])]
enum ABC {
  #[into(0)] #[title("A")] A,
  #[into(1)] B(i32),
  C,
}

// `list()`
let list = ABC::list();
assert_eq!(list, vec![ABC::A, ABC::B(10)]);

let a: ABC = ABC::A;
let b = ABC::B(10);
let c = ABC::C;

// `title()`
assert_eq!(a.title(), "A");
assert_eq!(b.title(), "B");
assert_eq!(c.title(), "C");

// `Into<T>` for `&Self` and `Self`
assert_eq!(Into::<u8>::into(&a), 0);
assert_eq!(Into::<u8>::into(a), 0);
assert_eq!(Into::<u8>::into(&b), 1);
assert_eq!(Into::<u8>::into(c), 0);

#[derive(Default, Debug, Isomorphism, PartialEq)]
#[isomorphism(into=[u8, i8], has_default)]
pub enum CD {
  #[default] #[into([0, 1])] C,
  #[into([0, -1])] D,
}

// list
assert_eq!(CD::list(), vec![CD::C, CD::D]);

// Into
assert_eq!(Into::<u8>::into(CD::C), 0);
assert_eq!(Into::<i8>::into(CD::C), 1);
assert_eq!(Into::<u8>::into(CD::D), 0);
assert_eq!(Into::<i8>::into(CD::D), -1);

// From
assert_eq!(Into::<CD>::into(1i8), CD::C);
assert_eq!(Into::<CD>::into(-1i8), CD::D);
// fallback to default value of `CD`
assert_eq!(Into::<CD>::into(-0i8), CD::C);

Dev Log

• ver.0.2.0
  • From<T> implemented only with has_default attribute syntax when Default is implemented.
• ver 0.2.1~2
  • correct some typos