//Purpose:
//  Test whether a function template can be specialized on fusion::list<>.
//
#include <boost/fusion/container/list.hpp>
#include <boost/fusion/include/empty.hpp>
#include <boost/fusion/include/pop_front.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/mpl/not.hpp>

#include <boost/mpl/assert.hpp>
#include <boost/type_traits/is_same.hpp>
#include <iostream>

  template
  < typename FusionSeq
  >
  unsigned
seq_size
  ( FusionSeq const& a_seq
  )
;
  template
  < typename IsEmpty
  , typename FusionSeq
  >
  struct
seq_size_impl
{
        static
      unsigned
    _( FusionSeq const& a_seq
     )
   {
       return 1+seq_size(boost::fusion::pop_front(a_seq));
   }
};
  template
  < typename FusionSeq
  >
  struct
seq_size_impl
  < boost::mpl::true_
  , FusionSeq
  >
{
        static
      unsigned
    _( FusionSeq const& a_seq
     )
   {
       return 0;
   }
};
  template
  < typename FusionSeq
  >
  unsigned
seq_size
  ( FusionSeq const& a_seq
  )
{
        typedef 
      seq_size_impl
      < typename boost::fusion::result_of::empty<FusionSeq>::type
      , FusionSeq
      >
    impl;
    return impl::_(a_seq);
}    

int main(void)
{
    typedef boost::fusion::list<int,char> list_t;
    list_t list_v(0,'a');
    unsigned list_v_size=seq_size(list_v);
    std::cout<<"list_v_size="<<list_v_size<<"\n";
    return 0;
}