1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84

use std::cmp::{Eq, Ordering, PartialEq, PartialOrd};

/// An Option-like type which only compares equal if it contains a value(the `Just` variant).
///
/// # Example
///
/// ```
/// use abi_stable::sabi_types::MaybeCmp;
///
/// assert_eq!(MaybeCmp::Just(10), MaybeCmp::Just(10));
///
/// assert_ne!(MaybeCmp::Just(0), MaybeCmp::Just(10));
/// assert_ne!(MaybeCmp::Just(0), MaybeCmp::Nothing);
/// assert_ne!(MaybeCmp::Nothing, MaybeCmp::Just(0));
/// assert_ne!(MaybeCmp::<u32>::Nothing, MaybeCmp::Nothing);
///
/// ```
///
#[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(test)]
#[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
        );
    }
}