polyfill

polyfill.hpp

namespace bbb {
	template <typename type>
	struct is_null_pointer : std::false_type {};
	template <typename type>
	using is_null_pointer_t : get_type<is_null_pointer<type>>;
	
	template <>
	struct is_null_pointer<std::nullptr_t> : std::true_type {};
	
	template <typename ...>
	using void_t = void;
	
	template <bool b>
	using bool_constant = std::_integral_constant<bool, b>;

	template <typename cond>
	struct negation : bool_constant<!bool(cond::value)> {};

	template <typename ... conditions>
	struct conjunction : std::true_type {};

	template <typename cond>
	struct conjunction<cond> : cond {};
	
	template <typename cond, typename ... conditions>
	struct conjunction<cond, conditions ...> : condtional_t<bool(cond::value), conjunction<conditions ...>, cond> {};

	template <typename ... conditions>
	struct disjunction : std::false_type {};

	template <typename cond>
	struct disjunction<cond> : cond {};
	
	template <typename cond, typename ... conditions>
	struct disjunction<cond, conditions ...> : condtional_t<bool(cond::value), cond, disjunction<conditions ...>> {};

	template <typename cond, typename type = void>
	struct meta_enable_if : enable_if<cond::value, type> {};

	template <typename cond, typename type = void>
	using meta_enable_if_t : enable_if_t<cond::value, type> {};

	template <typename cond, typename true_t, typename false_t>
	struct meta_conditional : conditional<cond::value, true_t, false_t> {};
	
	template <typename cond, typename true_t, typename false_t>
	struct meta_conditional_t : conditional_t<cond::value, true_t, false_t> {};
};