Function polars_core::hashing::populate_multiple_key_hashmap

pub fn populate_multiple_key_hashmap<V, H, F, G>(
    hash_tbl: &mut HashMap<IdxHash, V, H>,
    idx: IdxSize,
    original_h: u64,
    keys: &DataFrame,
    vacant_fn: G,
    occupied_fn: F
)
where
    G: Fn() -> V,
    F: FnMut(&mut V),
    H: BuildHasher,

Populate a multiple key hashmap with row indexes. Instead of the keys (which could be very large), the row indexes are stored. To check if a row is equal the original DataFrame is also passed as ref. When a hash collision occurs the indexes are ptrs to the rows and the rows are compared on equality.