[boost] Re: Variant Library: visitation algorithm

From: Gennadiy Rozental (gennadiy.rozental_at_[hidden])
Date: 2003-04-07 20:36:03

> Gennadiy Rozental wrote:
> > Could you clarify in which case loop-unrolling would provide O(1)
> > complexity?
>
> Assuming your assertion that a switch-based visitation algorithm is indeed
> O(1), then the following loop-unrolling approach would provide O(1) for
the
> first N types:
>
>   switch (which_) {
>     case 1: visitor( reinterpret_cast<T1>( ... ) ); break;
>     ...
>     case N: visitor( reinterpret_cast<TN>( ... ) ); break;
>     default:
>         <some code to handle next N types>
>   }
>
> Let me know if this resolves the issue.

Yep. Looks great.

Gennadiy.