Trait int_enum::IntEnum

source · [−]

pub trait IntEnum: Copy {
    type Int: PrimInt;

    fn int_value(self) -> Self::Int;
    fn from_int(n: Self::Int) -> Result<Self, IntEnumError<Self>>
    where
        Self: Sized;
}

Expand description

Trait used for implementations of integer and enum conversions.

Examples

Basic usage:

use int_enum::IntEnum;

#[repr(u8)]
#[derive(Clone, Copy, Debug, Eq, PartialEq, IntEnum)]
pub enum SmallInt {
    One = 1,
    Two = 2,
}

assert_eq!(1, SmallInt::One.int_value());
assert_eq!(2, SmallInt::Two.int_value());

assert_eq!(SmallInt::One, SmallInt::from_int(1)?);
assert_eq!(SmallInt::Two, SmallInt::from_int(2)?);

assert!(SmallInt::from_int(5).is_err());

Serde support (requires feature serialize):

use int_enum::IntEnum;

#[repr(i8)]
#[derive(Clone, Copy, Debug, Eq, PartialEq, IntEnum)]
enum Num {
    MinusThree = -3,
    Zero = 0,
    Five = 5,
}

assert_eq!("-3", serde_json::to_string(&Num::MinusThree)?);
assert_eq!("0", serde_json::to_string(&Num::Zero)?);
assert_eq!("5", serde_json::to_string(&Num::Five)?);

assert_eq!(Num::MinusThree, serde_json::from_str("-3")?);
assert_eq!(Num::Zero, serde_json::from_str("0")?);
assert_eq!(Num::Five, serde_json::from_str("5")?);

assert!(serde_json::from_str::<Num>("4").is_err());

From and TryFrom support (requires convert feature):

use std::convert::TryFrom;
use int_enum::IntEnum;

#[repr(u16)]
#[derive(Clone, Copy, Debug, Eq, PartialEq, IntEnum)]
enum Value {
    A = 1_000,
    B = 1_001,
    C = 1_002,
}

assert_eq!(1_000, u16::from(Value::A));
assert_eq!(1_001, u16::from(Value::B));
assert_eq!(1_002, u16::from(Value::C));

assert_eq!(Value::A, Value::try_from(1_000)?);
assert_eq!(Value::B, Value::try_from(1_001)?);
assert_eq!(Value::C, Value::try_from(1_002)?);

assert!(Value::try_from(2_000).is_err());