Macro struct_iter

macro_rules! struct_iter {
    (
        $( #[ $type_attr:meta ] )*
        $vis:vis struct $struct_name:ident {
            $(
                $( #[ $field_attr:meta ] )*
                $field_vis:vis $field:ident: $field_type:ty
            ),* $(,)?
        }
    ) => { ... };
}

Implements the iter function, which returns an iterator over all possible combinations of the struct’s fields, assuming each field’s type implements the iter function itself.

Example

enum_iter! {
    #[derive(Eq, PartialEq, Debug, Clone)]
    enum Species {
        BlueDragon,
        RedDragon,
    }
}

enum_iter! {
    #[derive(Eq, PartialEq, Debug, Clone)]
    enum BodyType {
        Male,
        Female,
    }
}

struct_iter! {
    #[derive(Eq, PartialEq, Debug)]
    struct Body {
        species: Species,
        body_type: BodyType,
    }
}

let results: Vec<_> = Body::iter().collect();
assert_eq!(results, vec![
    Body {
        species: Species::BlueDragon,
        body_type: BodyType::Male
    },
    Body {
        species: Species::BlueDragon,
        body_type: BodyType::Female
    },
    Body {
        species: Species::RedDragon,
        body_type: BodyType::Male
    },
    Body {
        species: Species::RedDragon,
        body_type: BodyType::Female
    },
])