Overload set optional_rule
Members
template<class R_>
constexpr
optional_rule_t<R_>
optional_rule(const R_& r);
» more...template<class Rule>
constexpr
optional_rule_t<Rule>
optional_rule(const Rule& r);
» more...template<class R_>
constexpr
optional_rule_t<R_>
optional_rule(const R_& r);
» more...template<class Rule>
constexpr
optional_rule_t<Rule>
optional_rule(const Rule& r);
» more...