C++ typeid()

Does anyone know how typeid() is implemented in C++???
I mean, how do I make a function like typeid() where I can pass the TYPE as a paramter.

Example:
int main()
{
    typeid(int);//<-- works of course
    f(int);//<-- how to do something like this
           //        without using macros or templates
}

really? but C++ is suppose to be a very flexible language. I mean, they allow (...), macros, templates, operator overloading etc. I'm SURE there must be a way to make a function that takes a keyword as an argument, right? Maybe not directly of course, since that is syntax error, but there MUST be a way, like meta-template programming for example, where it plays with the syntax to compute during comilation time.