#include <cstddef>
#include <utility>
#include <string>
#include <map>

enum TestEnum {
   BeginVal = 0,
   One = BeginVal,
   Two,
   Three,
   EndVal
};

template<TestEnum e>
struct MapEntry {
  enum { val = e };
  std::string s;
  MapEntry( std::string s_ ):s(s_) {}
};

void do_in_order() {}
template<typename F0, typename... Fs>
void do_in_order(F0&& f0, Fs&&... fs) {
  std::forward<F0>(f0)();
  do_in_order( std::forward<Fs>(fs)... );
}

template<typename... MapEntries>
struct count_entries:std::integral_constant< std::size_t, sizeof...(MapEntries) > {};

// should also detect duplicates and check the range of the values:
template<typename... MapEntries>
struct caught_them_all:
    std::integral_constant<
		bool,
		count_entries<MapEntries...>::value == (TestEnum::EndVal-TestEnum::BeginVal)
	>
{};

struct BuildMap {
  typedef std::map<std::string, TestEnum> result_map;
  mutable result_map val;
  operator result_map() const {
    return std::move(val);
  }
  template<typename... MapEntries>
  BuildMap( MapEntries&&... entries ) {
    static_assert( caught_them_all<MapEntries...>::value, "Missing enum value" );
    bool _[] = { ( (val[ entries.s ] = TestEnum(MapEntries::val)), false )... };
  }
};

std::map< std::string, TestEnum > bob = BuildMap(
	MapEntry<One>("One")
	,MapEntry<Two>("Two")
#if 0
	,MapEntry<Three>("Three")
#endif
);

int main() {}