Shared via Rust Playground

playground.rs

/// Takes two iterators over an ordered (key, value) sequence,
/// removing all entries which keys don't find a match in place
/// and zips the resulting filtered iterators afterwards.
///
/// Assumes the keys are in ascending order.
pub fn filter_zip<K, V, W, A, B>(a: &mut A, b: &mut B) // -> Iterator<Item=(K,(V, W))>
    where K: Ord,
          A: Iterator<Item=(K, V)>,
          B: Iterator<Item=(K, W)>,
{
    a.filter(|&(ref key_a,_)| {
            let mut is_equal = false;
            b.filter(|&(ref key_b,_)| {
                if key_a == key_b {
                    is_equal = true;
                    true
                } else {
                    key_a > key_b
                }
            });
            is_equal
        })
//        .zip(b)
        ;
}

fn main() {}