...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::parser::attr
// In header: <boost/parser/parser.hpp> template<typename Attribute> constexpr auto attr(Attribute a);
Returns an attr_parser
which matches anything, and consumes no input, and which produces a
as its attribute.