selection.h

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#ifndef __utl_meta_selection_h__
#define __utl_meta_selection_h__

#include <utl/core/impl.h>
#include <utl/meta/integral.h>

namespace utl {
namespace meta{


   namespace detail {
      template <bool If, typename...>
      struct if_c_ {
         using type = nil_;   
      };
      template<typename Then>
      struct if_c_<true, Then> {
         using type = Then;
      };
      template<typename Then, typename Else>
      struct if_c_<true, Then, Else> {
         using type = Then;
      };
      template<typename Then, typename Else>
      struct if_c_<false, Then, Else> {
         using type = Else;
      };
   }
   template <bool B, typename... Args>
   using if_c = eval<detail::if_c_<B, Args...>>;

   template <typename If, typename... Args>
   using if_ = if_c<If::type::value, Args...>;



   template <typename T1, typename ...> using first_of = T1;

   template <typename T1, typename T2, typename ...> using second_of = T2;

}}


#endif /* __utl_meta_selection_h__ */