Function count

pub fn count<G, Tr, K, R, F, P>(
    prefixes: &Collection<G, (P, usize, usize), R>,
    arrangement: Arranged<G, Tr>,
    key_selector: F,
    index: usize,
) -> Collection<G, (P, usize, usize), R>
where
    G: Scope<Timestamp = Tr::Time>,
    Tr: TraceReader<Diff = isize> + Clone + 'static,
    for<'a> Tr::Key<'a>: IntoOwned<'a, Owned = K>,
    for<'a> Tr::Diff: Semigroup<Tr::DiffGat<'a>>,
    K: Hashable + Ord + Default + 'static,
    R: Monoid + Multiply<Output = R> + ExchangeData,
    F: Fn(&P) -> K + Clone + 'static,
    P: ExchangeData,

Reports a number of extensions to a stream of prefixes.

This method takes as input a stream of (prefix, count, index) triples. For each triple, it extracts a key using key_selector, and finds the associated count in arrangement. If the found count is less than count, the count and index fields are overwritten with their new values.