Re: [boost] Identification library preliminary version

From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2008-08-18 06:23:46

joel falcou wrote:

>>   and would be fairly
> useful, since it would allow constant-time 
>> visitation over
> std::type_info&.
> I'm afraid I don't fully understand what you're
> implying. Would you mind elaborate on this point ?

You could generate nested switches to identify what type
std::type_info::name is within a finite set of possibilities.
That allows identification to be done in constant-time.

Imagine identifying whether type_info is "a" or "aa" for example.

switch(type.name()[0]
{
    case 'a':
        switch(type.name()[1])
        {
            case 0:
                return f(*reinterpret_cast<a*>(ptr));

            case 'a':
                switch(type.name()[2])
                {
                    case 0:
                        return f(*reinterpret_cast<aa*>(ptr));

                    default:
                        assert(0);
                }

            default:
                assert(0);
        }

    default:
        assert(0);
}

If you have the mangled names at compile-time, it is possible to
generate that kind of automaton automatically.