Crate enum_ordinalize
source ·Expand description
Enum Ordinalize
This crates provides create_ordinalized_enum
macro to let enums can not only get its variants’ ordinal but also be constructed from an ordinal.
Create an Ordinalized Enum
create_ordinalized_enum
macro can create an enum and implement a ordinal
method, as well as from_ordinal
and from_ordinal_unsafe
associated functions for it.
The new enum also implements Debug
, PartialOrd
, Ord
, PartialEq
, Clone
, Eq
, Hash
and Copy
traits.
#[macro_use] extern crate enum_ordinalize;
create_ordinalized_enum!(MyEnum,
Zero,
One,
Two
);
assert_eq!(2, MyEnum::Two.ordinal());
assert_eq!(Some(MyEnum::One), MyEnum::from_ordinal(1));
create_ordinalized_enum!(pub MyPublicEnum,
A,
B,
C
);
assert_eq!(2, MyPublicEnum::C.ordinal());
assert_eq!(Some(MyPublicEnum::B), MyPublicEnum::from_ordinal(1));
create_ordinalized_enum!(MySpecialEnum,
Two = 2,
Four = 4,
Eight = 8
);
assert_eq!(2, MySpecialEnum::Two.ordinal());
assert_eq!(Some(MySpecialEnum::Four), MySpecialEnum::from_ordinal(4));
About an Ordinalized Enum
An ordinalized enum is always sized isize in order to directly transmute into an isize value, or conversely. There is a variant named __DoNotUse whose ordinal is always the maximum of an isize value for every ordinalized enum.
If you are 100% sure that the isize value can transmute into a variant of your ordinalized enum. You can use the from_ordinal_unsafe
associated function and the unsafe keyword to speed up.
#[macro_use] extern crate enum_ordinalize;
create_ordinalized_enum!(MyEnum,
Zero,
One,
Two
);
assert_eq!(MyEnum::One, unsafe{MyEnum::from_ordinal_unsafe(1)});
Macros
ordinal
method, as well as from_ordinal
and from_ordinal_unsafe
associated functions for it. The new enum also implements Debug
, PartialOrd
, Ord
, PartialEq
, Clone
, Eq
, Hash
and Copy
traits.