This crate provides the EnumLike trait, which defines a mapping from
a given type to usize.
This is similar to std::mem::discriminant, however it has a few
differences. First of all, all the values are consecutive starting from
zero. This means that if an enum has 10 variants, the discriminant will
always be lower than 10. If a field has an explicit discriminant, that
value is ignored: in
enum { A = 100 }, A will have the value of 0.
And most importantly, this trait allows to create
an instance of the type from the usize, because the enum data, if present,
is also encoded in the discriminant (if possible). For example:
enum ABC { A, B, C }
enum DEF { D, E, F }
enum AD { A(ABC), D(DEF) }
The AD enum has 2 variants, but since each of these variants is an enum
with 3 variants, the AD::values().count() will return 6 instead of 2.