CmpOrder

Simple Macros to implement prioritized Ord/PartialOrd

Examples

cmp_order!

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct ABC {
    a: u8,
    b: u8,
}

impl Ord for ABC {
    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
        // priority:
        // 1) a
        // 2) b%2
        // 3) b
        cmp_order!(
            self.a.cmp(&other.a),
            (self.b % 2).cmp(&(other.b % 2)),
            self.b.cmp(&other.b),
        )
    }
}

impl PartialOrd for ABC {
    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
        Some(self.cmp(other))
    }
}

let abc1 = ABC { a: 10, b: 20 };
let abc2 = ABC { a: 20, b: 10 };
let abc3 = ABC { a: 10, b: 11 };
let mut list = vec![abc1, abc2, abc3];

list.sort();
assert_eq!(list, vec![abc1, abc3, abc2]);

partial_cmp_order!

impl PartialOrd for ABC {
    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
        // priority:
        // 1) a
        // 2) b%2
        // 3) b
        partial_cmp_order!(
            self.a.partial_cmp(&other.a),
            Some((self.b % 2).cmp(&(other.b % 2))),
            self.b.partial_cmp(&other.b)
        )
    }
}