class FFI::Bitmask

def [](*query)
  flat_query = query.flatten
  raise ArgumentError, "query should be homogeneous, #{query.inspect}" unless flat_query.all? { |o| o.is_a?(Symbol) } || flat_query.all? { |o| o.is_a?(Integer) || o.respond_to?(:to_int) }
  case flat_query[0]
  when Symbol
    flat_query.inject(0) do |val, o|
      v = @kv_map[o]
      if v then val | v else val end
    end
  when Integer, ->(o) { o.respond_to?(:to_int) }
    val = flat_query.inject(0) { |mask, o| mask |= o.to_int }
    @kv_map.select { |_, v| v & val != 0 }.keys
  end
end