[Boost-users] MPL intersection of type sequences and compile-time performance

From: Andrej van der Zee (mavdzee_at_[hidden])
Date: 2007-06-10 13:03:21

Hi,

Sorry if this already has been posted, but I have a
problem with compile-time performance when trying to
get the intersection of two type sequences. For
example, when I do something like this:

template<typename list1, typename list2>
struct intersect
{
  typedef typename boost::mpl::remove_if<list1,
    mpl::not_< mpl::contains<list2, mpl::_1>
   >::type type;
};

typedef mpl::vector<a,b,...,z> l1;
typedef mpl::vector<c,e,t,u,v> l2;

typename intersect<list1,list2>::type my_intersection;

Then for large type sequences compile-time becomes
unacceptable (O(M*N)). 

Is there a better way to do this?

Thanks,
Andrej
 

                
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