...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(xpr).
template<typename Xpr> unspecified optional(Xpr const & xpr);
Copyright © 2003, 2004 Eric Niebler |