Function selection_mask

arrow-array/src/array/union_array.rs:1024–1032

(type_ids_chunk: &[i8], type_id: i8)

}

fn selection_mask(type_ids_chunk: &[i8], type_id: i8) -> u64 {
    type_ids_chunk
        .iter()
        .copied()
        .enumerate()
        .fold(0, |packed, (bit_idx, v)| {
            packed | (((v == type_id) as u64) << bit_idx)
        })
}

/// Returns a bitmask where bits indicate if any id from `without_nulls_ids` exist in `type_ids_chunk`.
fn without_nulls_selected(type_ids_chunk: &[i8], without_nulls_ids: &[i8]) -> u64 {