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43_TypeTraits.cpp
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43_TypeTraits.cpp
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#include <iostream>
#include <type_traits>
// remove const
template <typename _Tp>
struct remove_const {
typedef _Tp type;
};
template <typename _Tp>
struct remove_const<_Tp const> {
typedef _Tp type;
};
// remove volatile
template <typename _Tp>
struct remove_volatile {
typedef _Tp type;
};
template <typename _Tp>
struct remove_volatile<_Tp volatile> {
typedef _Tp type;
};
// remove const and volatile
template <typename _Tp>
struct remove_cv {
typedef typename remove_const<typename remove_volatile<_Tp>::type>::type type;
};
// add const
template <typename _Tp>
struct add_const {
typedef _Tp const type;
};
// is void helper
template <typename _Tp>
struct __is_void_helper: public std::__false_type {};
template <>
struct __is_void_helper<void>: public std::__true_type {};
// is void
template <typename _Tp>
struct is_void: public __is_void_helper<typename remove_cv<_Tp>::type>::type {};
// is integral helper
template<typename>
struct __is_integral_helper: public std::__false_type {};
template <>
struct __is_integral_helper<bool>: public std::__true_type {};
template <>
struct __is_integral_helper<char>: public std::__true_type {};
template <>
struct __is_integral_helper<signed char>: public std::__true_type {};
template <>
struct __is_integral_helper<unsigned char>: public std::__true_type {};
// ....
template <>
struct __is_integral_helper<int>: public std::__true_type {};
template <>
struct __is_integral_helper<unsigned int>: public std::__true_type {};
// ....
template <>
struct __is_integral_helper<long long>: public std::__true_type {};
template <>
struct __is_integral_helper<unsigned long long>: public std::__true_type {};
// is integral
template <typename _Tp>
struct is_integral: public __is_integral_helper<typename remove_cv<_Tp>::type>::type {};