result_type operator() (multi_line_string<T> const& multi_line) const { if (multi_line.empty()) { // This return is due to bug in boost geometry once it is fixed it can be removed // https://svn.boost.org/trac/boost/ticket/11710 return true; } for (auto const& line : multi_line) { if (!(*this)(line)) return false; } return true; }