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use std::cmp::{Eq, Ordering, PartialEq, PartialOrd};
#[allow(clippy::derive_hash_xor_eq)]
#[derive(Debug, Copy, Clone, Hash)]
#[repr(u8)]
#[derive(StableAbi)]
pub enum MaybeCmp<T> {
Just(T),
Nothing,
}
impl<T> Eq for MaybeCmp<T> where T: Eq {}
impl<T> PartialEq for MaybeCmp<T>
where
T: PartialEq,
{
fn eq(&self, other: &Self) -> bool {
match (self, other) {
(MaybeCmp::Just(l), MaybeCmp::Just(r)) => l == r,
_ => false,
}
}
}
impl<T> PartialOrd for MaybeCmp<T>
where
T: PartialOrd,
{
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
match (self, other) {
(MaybeCmp::Just(l), MaybeCmp::Just(r)) => l.partial_cmp(r),
_ => None,
}
}
}
#[cfg(all(test, not(feature = "only_new_tests")))]
mod tets {
use super::*;
#[test]
fn comparisons() {
assert_eq!(MaybeCmp::Just(0), MaybeCmp::Just(0));
assert_ne!(MaybeCmp::Just(0), MaybeCmp::Just(1));
assert_ne!(MaybeCmp::Nothing, MaybeCmp::Just(0));
assert_ne!(MaybeCmp::Just(0), MaybeCmp::Nothing);
assert_ne!(MaybeCmp::<()>::Nothing, MaybeCmp::Nothing);
assert_eq!(
MaybeCmp::Just(0).partial_cmp(&MaybeCmp::Just(0)),
Some(Ordering::Equal)
);
assert_eq!(
MaybeCmp::Just(0).partial_cmp(&MaybeCmp::Just(1)),
Some(Ordering::Less)
);
assert_eq!(MaybeCmp::Nothing.partial_cmp(&MaybeCmp::Just(0)), None);
assert_eq!(MaybeCmp::Just(0).partial_cmp(&MaybeCmp::Nothing), None);
assert_eq!(
MaybeCmp::<()>::Nothing.partial_cmp(&MaybeCmp::Nothing),
None
);
}
}