paradis 0.2.1

Parallel processing with disjoint indices
Documentation 
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use crate::index::{IndexList, UniqueIndexList};
use paradis_core::Bounds;

/// A Cartesian product of index sets.
///
/// TODO: Example, document row-major behavior etc.
/// TODO: Also provide `IndexRProduct` for alternative column-major ordering
///       that's probably a bad name, since it's not "reverse" as "R" might suggest.
///       IndexCProduct? Not sure..
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct IndexProduct<A, B>(pub A, pub B);

unsafe impl<A, B> IndexList for IndexProduct<A, B>
where
    A: IndexList,
    B: IndexList,
{
    type Index = (A::Index, B::Index);
    const ALWAYS_BOUNDED: bool = A::ALWAYS_BOUNDED && B::ALWAYS_BOUNDED;

    unsafe fn get_index_unchecked(&self, loc: usize) -> Self::Index {
        let m = self.1.num_indices();
        let i = loc / m;
        let j = loc % m;
        unsafe { (self.0.get_index_unchecked(i), self.1.get_index_unchecked(j)) }
    }

    fn num_indices(&self) -> usize {
        self.0.num_indices() * self.1.num_indices()
    }

    fn bounds(&self) -> Option<Bounds<Self::Index>> {
        self.0.bounds().zip(self.1.bounds()).map(|(a, b)| a.zip(b))
    }
}

unsafe impl<A, B> UniqueIndexList for IndexProduct<A, B>
where
    A: UniqueIndexList,
    B: UniqueIndexList,
{
}

#[cfg(test)]
mod tests {
    use crate::index::combinators::IndexProduct;
    use crate::index::index_list::IndexList;

    #[test]
    fn index_product_basic_tests() {
        let product = IndexProduct(0..3, 1..4);
        assert_eq!(product.num_indices(), 9);

        assert_eq!(product.get_index(0), (0, 1));
        assert_eq!(product.get_index(1), (0, 2));
        assert_eq!(product.get_index(2), (0, 3));
        assert_eq!(product.get_index(3), (1, 1));
        assert_eq!(product.get_index(4), (1, 2));
        assert_eq!(product.get_index(5), (1, 3));
        assert_eq!(product.get_index(6), (2, 1));
        assert_eq!(product.get_index(7), (2, 2));
        assert_eq!(product.get_index(8), (2, 3));
    }
}