traits.hpp

#ifndef NGEN_UTILITIES_TRAITS_HPP
#define NGEN_UTILITIES_TRAITS_HPP
 
#include <type_traits>
#include <boost/variant.hpp>
 
namespace ngen {
namespace traits {
 
template<bool...>
struct bool_pack
{};
 
template<bool B>
using bool_constant = std::integral_constant<bool, B>;
 
// a C++17 conjunction impl
template<bool... Bs>
using conjunction = std::is_same<bool_pack<true, Bs...>, bool_pack<Bs..., true>>;
 
// a C++17 disjunction impl
template<bool... Bs>
using disjunction = bool_constant<!conjunction<!Bs...>::value>;
 
template<typename T, typename... Ts>
using all_is_same = conjunction<std::is_same<Ts, T>::value...>;
 
template<typename To, typename... From>
using all_is_convertible = conjunction<std::is_convertible<From, To>::value...>;
 
template<typename From, typename... To>
using is_convertible_to_any = disjunction<std::is_convertible<From, To>::value...>;
 
template<typename T, typename... Ts>
using is_same_to_any = disjunction<std::is_same<T, Ts>::value...>;
 
template<typename... Ts>
struct type_list{
    using variant_scalar = boost::variant<Ts...>;
 
    template<template<typename> class Container>
    using variant_container = boost::variant<Container<Ts>...>;
 
    template<typename S>
    using is_supported = is_convertible_to_any<S, Ts...>;
 
    template<typename S, typename Tp>
    using enable_if_supports = std::enable_if_t<is_supported<S>::value, Tp>;
};
 
} // namespace traits
} // namespace ngen
 
#endif // NGEN_IO_TRAITS_HPP