2 releases
0.1.2 | Oct 7, 2021 |
---|---|
0.1.1 | Oct 1, 2021 |
0.1.0 |
|
#22 in #u8
6KB
Zhi Enum
Easily create casting traits with unknown field support.
Usage
- Add
EnumConvert
orEnumTryConvert
into thederive
attribute.
use zhi_enum::{EnumConvert, EnumTryConvert};
#[derive(Debug, Ord, PartialOrd, Eq, PartialEq, EnumConvert)]
#[repr(u8)]
enum NumberConvert {
Zero,
One,
Two,
Three,
Four,
Ten = 10,
Eleven,
Twenty = 10 + 10,
TwentyOne,
#[zhi_enum(unknown)]
Unknown(u8),
}
#[derive(Debug, Ord, PartialOrd, Eq, PartialEq, EnumTryConvert)]
#[repr(u8)]
enum NumberTryConvert {
Zero,
One,
Two,
Three,
Four,
Ten = 10,
Eleven,
Twenty = 10 + 10,
TwentyOne,
#[zhi_enum(unknown)]
Unknown(u8),
}
- Then, you can use
.from
/.into
convert functions
assert_eq!(NumberConvert::Three.into_u8(), 3u8);
assert_eq!(NumberTryConvert::Three.try_into_u8().unwrap(), 3u8);
assert_eq!(NumberConvert::Ten.into_u8(), 10u8);
assert_eq!(NumberTryConvert::Ten.try_into_u8().unwrap(), 10u8);
assert_eq!(NumberConvert::Eleven.into_u8(), 11u8);
assert_eq!(NumberTryConvert::Eleven.try_into_u8().unwrap(), 11u8);
assert_eq!(NumberConvert::TwentyOne.into_u8(), 21u8);
assert_eq!(NumberTryConvert::TwentyOne.try_into_u8().unwrap(), 21u8);
assert_eq!(NumberConvert::from(3u8), NumberConvert::Three);
use std::convert::TryFrom;
assert_eq!(NumberTryConvert::try_from(21u8).unwrap(), NumberTryConvert::TwentyOne);
Handle unknown discriminant
-
If you have defined a variant with
#[zhi_enum(unknown)]
attribute in your enum like this :#[zhi_enum(unknown)] Whatever(repr type),
which the
repr type
is the represented type as you define use#[repr(...)]
.Then, when you convert a repr type into enum type, an unknown discriminant will be converted to this variant with its unknown value.
-
If you have not defined, the
.try_into()
will returnsErr(UnknownVariantError{})
, and the.into()
will callpanic!
.
FAQ
-
Error E0658
If you get this error:
error[E0658]: custom discriminant values are not allowed in enums with tuple or struct variants --> <source>:2:9
It means that your rustc version is lower than
1.56
.You can just upgrade your rustc. Or if you don't want upgrade, you have to add
#![feature(arbitrary_enum_discriminant)]
to your project.
License
BSD-3-Clause
Dependencies
~1.5MB
~37K SLoC