slice-group-by 0.3.1

mod binary_group;
mod binary_group_by;
mod binary_group_by_key;

pub use self::binary_group::{BinaryGroup, BinaryGroupMut};
pub use self::binary_group_by::{BinaryGroupBy, BinaryGroupByMut};
pub use self::binary_group_by_key::{BinaryGroupByKey, BinaryGroupByKeyMut};

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

    #[derive(Debug, Eq)]
    enum Guard {
        Valid(i32),
        Invalid(i32),
    }

    impl PartialEq for Guard {
        fn eq(&self, other: &Self) -> bool {
            match (self, other) {
                (Guard::Valid(_), Guard::Valid(_)) => true,
                (a, b) => panic!("denied read on Guard::Invalid variant ({:?}, {:?})", a, b),
            }
        }
    }

    #[test]
    fn one_big_group() {
        let slice = &[1, 1, 1, 1];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next(), Some(&[1, 1, 1, 1][..]));
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn two_equal_groups() {
        let slice = &[1, 1, 1, 1, 2, 2, 2, 2];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next(), Some(&[1, 1, 1, 1][..]));
        assert_eq!(iter.next(), Some(&[2, 2, 2, 2][..]));
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn two_little_equal_groups() {
        let slice = &[1, 2];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next(), Some(&[1][..]));
        assert_eq!(iter.next(), Some(&[2][..]));
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn three_groups() {
        let slice = &[1, 1, 1, 2, 2, 2, 3, 3];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
        assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
        assert_eq!(iter.next(), Some(&[3, 3][..]));
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn three_little_groups() {
        let slice = &[1, 2, 3];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next(), Some(&[1][..]));
        assert_eq!(iter.next(), Some(&[2][..]));
        assert_eq!(iter.next(), Some(&[3][..]));
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn overflow() {
        let slice = &[Guard::Invalid(0), Guard::Valid(1), Guard::Valid(2), Guard::Invalid(3)];

        let mut iter = BinaryGroup::new(&slice[1..3]);

        assert_eq!(iter.next(), Some(&[Guard::Valid(1), Guard::Valid(2)][..]));
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn last_three_little_groups() {
        let slice = &[1, 2, 3];

        let iter = BinaryGroup::new(slice);

        assert_eq!(iter.last(), Some(&[3][..]));
    }

    #[test]
    fn last_three_groups() {
        let slice = &[1, 1, 1, 2, 2, 2, 3, 3];

        let iter = BinaryGroup::new(slice);

        assert_eq!(iter.last(), Some(&[3, 3][..]));
    }

    #[test]
    fn last_overflow() {
        let slice = &[Guard::Invalid(0), Guard::Valid(1), Guard::Valid(2), Guard::Invalid(3)];

        println!("{:?}", (&slice[1..3]).as_ptr());

        let iter = BinaryGroup::new(&slice[1..3]);

        assert_eq!(iter.last(), Some(&[Guard::Valid(1), Guard::Valid(2)][..]));
    }

    #[test]
    fn back_empty_slice() {
        let slice: &[i32] = &[];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next_back(), None);
    }

    #[test]
    fn back_one_little_group() {
        let slice = &[1];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next_back(), Some(&[1][..]));
        assert_eq!(iter.next_back(), None);
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn back_three_little_groups() {
        let slice = &[1, 2, 3];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next_back(), Some(&[3][..]));
        assert_eq!(iter.next_back(), Some(&[2][..]));
        assert_eq!(iter.next_back(), Some(&[1][..]));
        assert_eq!(iter.next_back(), None);
    }

    #[test]
    fn back_three_groups() {
        let slice = &[1, 1, 1, 2, 2, 2, 3, 3];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next_back(), Some(&[3, 3][..]));
        assert_eq!(iter.next_back(), Some(&[2, 2, 2][..]));
        assert_eq!(iter.next_back(), Some(&[1, 1, 1][..]));
        assert_eq!(iter.next_back(), None);
    }

    #[test]
    fn double_ended_dont_cross() {
        let slice = &[1, 1, 1, 2, 2, 2, 3, 3];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
        assert_eq!(iter.next_back(), Some(&[3, 3][..]));
        assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
        assert_eq!(iter.next_back(), None);
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn fused_iterator() {
        let slice = &[1, 2, 3];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next(), Some(&[1][..]));
        assert_eq!(iter.next(), Some(&[2][..]));
        assert_eq!(iter.next(), Some(&[3][..]));
        assert_eq!(iter.next(), None);
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn back_fused_iterator() {
        let slice = &[1, 2, 3];

        let mut iter = BinaryGroup::new(slice);

        assert_eq!(iter.next_back(), Some(&[3][..]));
        assert_eq!(iter.next_back(), Some(&[2][..]));
        assert_eq!(iter.next_back(), Some(&[1][..]));
        assert_eq!(iter.next_back(), None);
        assert_eq!(iter.next_back(), None);
    }
}

#[cfg(all(feature = "nightly", test))]
mod bench {
    extern crate test;
    extern crate rand;

    use super::*;
    use self::rand::{Rng, SeedableRng};
    use self::rand::rngs::StdRng;
    use self::rand::distributions::Alphanumeric;

    #[bench]
    fn vector_16_000_sorted(b: &mut test::Bencher) {
        let mut rng = StdRng::from_seed([42; 32]);

        let len = 16_000;
        let mut vec = Vec::with_capacity(len);
        for _ in 0..len {
            vec.push(rng.sample(Alphanumeric));
        }

        vec.sort_unstable();

        b.iter(|| {
            let group_by = BinaryGroup::new(vec.as_slice());
            test::black_box(group_by.count())
        })
    }

    #[bench]
    fn vector_little_sorted(b: &mut test::Bencher) {
        let mut rng = StdRng::from_seed([42; 32]);

        let len = 30;
        let mut vec = Vec::with_capacity(len);
        for _ in 0..len {
            vec.push(rng.sample(Alphanumeric));
        }

        vec.sort_unstable();

        b.iter(|| {
            let group_by = BinaryGroup::new(vec.as_slice());
            test::black_box(group_by.count())
        })
    }

    #[bench]
    fn vector_16_000_one_group(b: &mut test::Bencher) {
        let vec = vec![1; 16_000];

        b.iter(|| {
            let group_by = BinaryGroup::new(vec.as_slice());
            test::black_box(group_by.count())
        })
    }

    #[bench]
    fn rev_vector_16_000_sorted(b: &mut test::Bencher) {
        let mut rng = StdRng::from_seed([42; 32]);

        let len = 16_000;
        let mut vec = Vec::with_capacity(len);
        for _ in 0..len {
            vec.push(rng.sample(Alphanumeric));
        }

        vec.sort_unstable();

        b.iter(|| {
            let group_by = BinaryGroup::new(vec.as_slice());
            test::black_box(group_by.rev().count())
        })
    }

    #[bench]
    fn rev_vector_16_000_one_group(b: &mut test::Bencher) {
        let vec = vec![1; 16_000];

        b.iter(|| {
            let group_by = BinaryGroup::new(vec.as_slice());
            test::black_box(group_by.rev().count())
        })
    }
}