Command Line Interpreter Example

This example demonstrates how Boost.Reflect can be used to create a generic command line interpreter that can interpret std::cin commands like:

    add( 1 )
    add2( 1,2.4 )

And call the proper method with the proper arguments and then print the result.

    class cli 
    {
      public:
        template<typename T>
        cli( T aptr) { 
           boost::reflect::visit( aptr, visitor<typename T::vtable_type>( *this, *aptr) ); 
        }

        boost::function<std::string(const std::string&)>& operator[]( const std::string& name ) 
        { return methods[name]; }

      private:
        template<typename VTableType> struct visitor {
            visitor( cli& c, VTableType& vtbl ):m_cli(c),m_vtbl(vtbl){}
            template<typename M, typename InterfaceName, M InterfaceName::* m>
            void operator()( const char* name ) const {
                 std::cerr << std::setw(10) << std::setiosflags(std::ios::left) << name 
                           << " " << boost::reflect::get_typename<typename M::signature>()
                           << (M::is_const ? "const" : "") <<std::endl;
                 m_cli.methods[name] = cli_functor<typename M::fused_params, M&>(m_vtbl.*m);
            }
            VTableType&   m_vtbl;
            cli&          m_cli;
        };

        template<typename Seq, typename Functor>
        struct cli_functor
        {
            cli_functor( Functor f )
            :m_func(f){}

            typedef typename boost::remove_reference<Functor>::type functor_type;

            std::string operator()( const std::string& cli ) {
                 std::stringstream ss(cli);
                 Seq s; ss >> boost::fusion::tuple_delimiter(',') >> s;
                 std::stringstream rtn;
                 rtn << m_func(s);
                 return rtn.str();
            }
            Functor m_func;
        };
        std::map<std::string, boost::function<std::string(const std::string&)> > methods;
    };

This class can then be used like so:

    int main( int argc, char** argv )
    {
        boost::reflect::any_ptr<Calculator> s( new CalculatorService() );
        printf( "Result: %f\n", s->result() );

        cli  m_cli(s);

        std::string line;
        std::string cmd;
        std::string args;

        while( true ) {
            std::cerr << "Enter Method: ";
            std::getline( std::cin, line );
            cmd = line.substr( 0, line.find('(') );
            args = line.substr( cmd.size(), line.size() );
            std::cerr << m_cli[cmd](args) << std::endl;
        }

        return 0;
    }