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0.1.0 | May 20, 2024 |
#1676 in Encoding
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Small numbers
Small numbers can be used to describe some constrained data. For example, a number of alignment bytes:
use small_num::small_num;
small_num! {
#[derive(Clone, Debug, PartialEq, Copy, Eq, PartialOrd, Ord, Hash)]
pub enum AlignBytes: [1, 2, 4];
}
let bytes = AlignBytes::new(2);
assert_eq!(bytes, Some(AlignBytes::_2));
assert_eq!(AlignBytes::new(3), None);
assert_eq!(std::mem::size_of::<Option<AlignBytes>>(), 1);
Or an integer valid for a spicific range:
use small_num::small_num;
small_num! {
#[derive(Clone, Debug, PartialEq, Copy, Eq, PartialOrd, Ord, Hash)]
pub enum U7: ..128;
}
assert_eq!(U7::new(0), Some(U7::_0));
assert_eq!(U7::new(50), Some(U7::_50));
assert_eq!(U7::new(127), Some(U7::_127));
assert_eq!(U7::new(128), None);
assert_eq!(std::mem::size_of::<Option<U7>>(), 1);
It can be casted to an integer with as
operator:
use small_num::small_num;
small_num! {
#[derive(Clone, Debug, PartialEq, Copy, Eq, PartialOrd, Ord, Hash)]
pub enum Num50to100: 50..=100;
}
assert_eq!(Num50to100::new(69).unwrap() as u32, 69);
Where clause can be used to derive supported traits:
use small_num::small_num;
small_num! {
#[derive(Clone)]
pub enum MySmallNumber: [0, 42, 121]
where
Self: Debug + Serialize;
}
Supported traits in the where clause:
Debug
- prints your small number as a regular numberSerialize
(withserde
feature)Deserialize
(withserde
feature)
Crate features
serde
enablesSerialize
andDeserialize
derivation.
Dependencies
~170KB