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#[inline]
pub fn ordinal<T: Into<i64>>(x: T) -> String {
    let x: i64 = x.into();
    let mut suffix = "th";
    match x % 10 {
        1 => {
            if x % 100 != 11 {
                suffix = "st";
            }
        }
        2 => {
            if x % 100 != 12 {
                suffix = "nd";
            }
        }
        3 => {
            if x % 100 != 13 {
                suffix = "rd";
            }
        }
        _ => {}
    }

    return x.to_string() + suffix;
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_ordinal() {
        struct OrdinalTest(String, &'static str);

        let tests = vec![
            OrdinalTest(ordinal(0), "0th"),
            OrdinalTest(ordinal(1), "1st"),
            OrdinalTest(ordinal(2), "2nd"),
            OrdinalTest(ordinal(3), "3rd"),
            OrdinalTest(ordinal(4), "4th"),
            OrdinalTest(ordinal(10), "10th"),
            OrdinalTest(ordinal(11), "11th"),
            OrdinalTest(ordinal(12), "12th"),
            OrdinalTest(ordinal(13), "13th"),
            OrdinalTest(ordinal(14), "14th"),
            OrdinalTest(ordinal(100), "100th"),
            OrdinalTest(ordinal(101), "101st"),
            OrdinalTest(ordinal(102), "102nd"),
            OrdinalTest(ordinal(103), "103rd"),
            OrdinalTest(ordinal(104), "104th"),
        ];

        tests.iter().for_each(|test| assert_eq!(test.0, test.1));
    }

    extern crate test;
    use test::Bencher;

    #[bench]
    fn bench_ordinal(b: &mut Bencher) {
        use rand::Rng;
        let n: u8 = rand::thread_rng().gen();

        b.iter(|| ordinal(n))
    }
}