#include <cstdlib>
#include <iostream>
#include <map>
#include <string>
#include <boost/phoenix/phoenix.hpp>
#include <boost/function.hpp>


using namespace std;

#define BOOST_LOG_REGISTER_ATTRIBUTE( _name, attr, type ) \
namespace tag\
{\
    struct attr\
    {\
        typedef type value_type;\
\
        char const* const name;\
\
        typedef attribute_value const& result_type;\
\
        template <typename Env>\
        attribute_value const&\
        operator()(Env const& env) const\
        {/*warning: the checking for iterator is ignored for simplicity here */\
            return ::boost::fusion::at_c<0>(env.args()).find(_name)->second;\
        }\
    };\
}\
\
BOOST_PHOENIX_DEFINE_CUSTOM_TERMINAL(\
    template <>\
  , ::tag::attr\
  , mpl::false_\
  , ::tag::attr(functional::env(proto::_state))\
)\
\
typedef ::boost::phoenix::actor<tag::attr> attr##_type;\
attr##_type attr = {{_name}};

typedef int attribute_value;
typedef map< string, attribute_value > attribute_values_view;
typedef boost::function< bool (attribute_values_view const&) > filter;
 
enum my_severity { info, warning, error };

BOOST_LOG_REGISTER_ATTRIBUTE("Severity", severity, my_severity)

int main(int argc, char *argv[])
{
    filter flt = severity >= warning;
    attribute_values_view a;
    a["Severity"] = warning;

    cout << flt(a);

    return EXIT_SUCCESS;
}