Hi all, I would like to customize the example calc4.cpp at http://www.boost.org/doc/libs/1_47_0/libs/spirit/example/qi/compiler_tutoria... the following grammar: G-------> { A+; C} A--------> {B; C} B--------->E (like arithmetic expression grammar in calc4.cpp) How to modifier this boost variant instruction for this grammar or there no need to change it: typedef boost::variant< nil , unsigned int , boost::recursive_wrapper<signed_> , boost::recursive_wrapper<program> > In general what to put in boost variant for specific grammar (or AST). Any suggestion is welcome. Thank you. Regards Olivier