Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::xpressive::optional — Make a sub-expression optional. Equivalent to !as_xpr(expr).
// In header: <boost/xpressive/regex_primitives.hpp> template<typename Expr> proto::result_of::make_expr< proto::tag::logical_not, proto::default_domain, Exprconst & >::type const optional(Expr const & expr);