mijin2/source/mijin/util/traits.hpp
2023-05-29 14:51:44 +02:00

119 lines
2.9 KiB
C++

#pragma once
#if !defined(MIJIN_UTIL_TRAITS_HPP_INCLUDED)
#define MIJIN_UTIL_TRAITS_HPP_INCLUDED 1
#include <tuple>
namespace mijin
{
//
// public defines
//
//
// public constants
//
//
// public types
//
template<typename T>
struct always_false
{
static constexpr bool value = false;
};
template<typename T>
inline constexpr bool always_false_v = always_false<T>::value;
template<auto V>
struct always_false_val
{
static constexpr bool value = false;
};
template<auto V>
inline constexpr bool always_false_val_v = always_false_val<V>::value;
template<template<typename> typename TFilter, typename... TArgs>
struct TypeFilter;
template<template<typename> typename TFilter>
struct TypeFilter<TFilter>
{
using type_t = std::tuple<>;
};
template<template<typename> typename TFilter, typename TFirst, typename... TArgs>
struct TypeFilter<TFilter, TFirst, TArgs...>
{
static consteval auto makeTypeHelper()
{
using base_t = typename TypeFilter<TFilter, TArgs...>::type_t;
// note: not using decltype, as the compiler might think it is being evaluated
if constexpr (!TFilter<TFirst>::value) {
return static_cast<base_t*>(nullptr);
}
else {
auto wrapper = []<typename... TArgsInner>(std::tuple<TArgsInner...>*)
{
return static_cast<std::tuple<TFirst, TArgsInner...>*>(nullptr);
};
return wrapper(static_cast<base_t*>(nullptr));
}
}
using type_t = std::remove_pointer_t<decltype(makeTypeHelper())>;
};
template<template<typename> typename TFilter, typename... TArgs>
auto typeFilterHelper(std::tuple<TArgs...>*)
{
return static_cast<typename TypeFilter<TFilter, TArgs...>::type_t*>(nullptr);
}
template<template<typename> typename TFilter, typename TTuple>
using filter_types_t = std::remove_pointer_t<decltype(typeFilterHelper<TFilter>(static_cast<TTuple*>(nullptr)))>;
template<template<typename> typename TPredicate, typename... TArgs>
auto mapTypesHelper(std::tuple<TArgs...>)
{
return static_cast<std::tuple<TPredicate<TArgs>...>*>(nullptr);
}
template<template<typename> typename TPredicate, typename TTuple>
using map_types_t = std::remove_pointer_t<decltype(mapTypesHelper<TPredicate>(std::declval<TTuple>()))>;
template<template<typename> typename TPredicate, template<typename> typename TTemplate>
struct map_template {
template<typename T>
using type_t = TTemplate<TPredicate<T>>;
};
template<typename T, typename... Types>
struct is_any_type : std::disjunction<std::is_same<T, Types>...> {};
template<typename T, typename... Types>
static constexpr bool is_any_type_v = is_any_type<T, Types...>::value;
//
// public functions
//
template<typename THelper, typename TType>
decltype(auto) delayEvaluation(TType&& value)
{
return static_cast<TType&&>(value);
}
} // namespace mijin
#endif // !defined(MIJIN_UTIL_TRAITS_HPP_INCLUDED)