IndexOf.hpp

 
// This work derives from Vittorio Romeo's code used for cppcon 2015 licensed
// under the Academic Free License.
// His code is available here: https://github.com/SuperV1234/cppcon2015
 
 
/*
    Returns the index of a type in a type list.
    If the type does not exist in the type list,
    returns the size of the type list.
*/
 
#ifndef EC_META_INDEX_OF_HPP
#define EC_META_INDEX_OF_HPP
 
#include "TypeList.hpp"
 
namespace EC
{
    namespace Meta
    {
        template <typename T, typename... Types>
        struct IndexOf : std::integral_constant<std::size_t, 0>
        {
        };
 
        template <
            typename T,
            template <typename...> class TTypeList,
            typename... Types>
        struct IndexOf<T, TTypeList<T, Types...> > :
            std::integral_constant<std::size_t, 0>
        {
        };
 
        template <
            typename T,
            template <typename...> class TTypeList,
            typename Type,
            typename... Types>
        struct IndexOf<T, TTypeList<Type, Types...> > :
            std::integral_constant<std::size_t, 1 +
                IndexOf<T, TTypeList<Types...> >::value
            >
        {
        };
    }
}
 
#endif