2013/10/2 Larry Evans <cppljevans@suddenlink.net>

On 10/02/13 12:13, Olivier Austina wrote:

Hi,
this is a basic question (I am sorry).
I am try to undestand the  calc2_ast.cpp example at
http://www.boost.org/doc/libs/1_41_0/libs/spirit/example/qi/calc2_ast.cpp
I think the instruction expression_ast() : expr(nil()){} is an
inheritance.

expr is a member variable of expression_ast.

Where can I find the definition of expr()?

See below.

This is the code
struct expression_ast
     {
         typedef
             boost::variant<
                 nil // can't happen!
               , unsigned int
               , boost::recursive_wrapper<expression_ast>
               , boost::recursive_wrapper<binary_op>
               , boost::recursive_wrapper<unary_op>
             >
         type;

*expression_ast() : expr(nil()){};*

         template <typename Expr>
         expression_ast(Expr const& expr)
           : expr(expr) {}

         expression_ast& operator+=(expression_ast const& rhs);
         expression_ast& operator-=(expression_ast const& rhs);
         expression_ast& operator*=(expression_ast const& rhs);
         expression_ast& operator/=(expression_ast const& rhs);

         type expr;

Here's the definition of expr.

     };

     //expression_ast bbb;
     struct binary_op
     {
         binary_op(
             char op
           , expression_ast const& left
           , expression_ast const& right)
         : op(op), left(left), right(right) {}

         char op;
         expression_ast left;
         expression_ast right;
     };


Thank you.



Regards
Olivier



_______________________________________________
Boost-users mailing list
Boost-users@lists.boost.org
http://lists.boost.org/mailman/listinfo.cgi/boost-users

_______________________________________________
Boost-users mailing list
Boost-users@lists.boost.org
http://lists.boost.org/mailman/listinfo.cgi/boost-users