//See what iter_fold_if does.
#include <boost/mpl/range_c.hpp>
#include <boost/mpl/iter_fold_if.hpp>
#include <boost/mpl/arg.hpp>
#include <boost/mpl/next.hpp>
#include <boost/mpl/push_front.hpp>
#include <boost/mpl/list.hpp>
#include <boost/mpl/for_each.hpp>

#include <iostream>


namespace boost
{
namespace mpl
{
      
    struct print_unsigned
    {
        template <unsigned Value>
        void operator()(r_iter<integral_c<unsigned,Value> >&) const
        {
            std::cout <<"   r_iter:"<< Value << std::endl;
        }
        template <unsigned Value>
        void operator()(integral_c<unsigned,Value>&) const
        {
            std::cout <<"   value:"<< Value << std::endl;
        }
    };
    
      template
      < unsigned N
      >
    void test_iter_fold_if(void)
    {
            typedef 
          range_c<unsigned,0,N> 
        numbers;
        std::cout<<"***test_iter_fold_if<"<<N<<"> numbers=:\n";
        for_each<numbers>(print_unsigned());
            typedef typename 
          iter_fold_if
          < numbers
          , list<>
          , push_front<arg<1>,arg<2> >
          , always<true_>
          , push_front<arg<1>,arg<2> >
          , always<true_>
          >::type
        result;
        std::cout<<"***test_iter_fold_if<"<<N<<"> result::state=:\n";
        for_each<typename result::first>(print_unsigned());
    }

}}//exit boost::mpl namespace

int main(void)
{
    boost::mpl::test_iter_fold_if<1>();
    boost::mpl::test_iter_fold_if<2>();
    return 0;
}