How can I parse different structures with Boost.Spirit.Qi?

Question

In this example, employee structs are parsed in the form "employee{int, string, string, double}".

I would like to know whether it is possible to modify this example to also parse different types of structs, like "intern{int, string, string}".

Specifically, I would like to then pass the structure to a function overloaded on the structure type. It would be great if I can avoid using polymorphic double dispatch for this, and instead preserve the concrete type that gets parsed to statically match the correct overloaded function.

Answer 1

Sure, that's possible. Create a rule for each of the types you want to parse:

rule<Iterator, std::string()> s = ...;
rule<Iterator, intern()> intern_r = int_ >> s >> s;
rule<Iterator, employee()> employee_r = int_ >> s >> s >> double_;

and combine those into an alternative:

rule<Iterator> r = 
        intern_r   [phoenix::bind(receive_intern, _1)]
    |   employee_r [phoenix::bind(receive_employee, _1)]
    ;

This assumes you have 2 functions handling the parsed data:

void receive_intern(intern const&);
void receive_employee(employee const&);

Is that what you want?