#ifndef IS_INTEGRAL_HPP
# define IS_INTEGRAL_HPP

namespace ft {

//struct true_type {
//	typedef bool		value_type;
//	typedef true_type	type;
//	static const bool   value = true;
//};
//
//struct false_type {
//	typedef T			value_type;
//	typedef false_type	type;
//	static const bool   value = false;
//};

template <class T> struct is_integral
{
	typedef char yes[1];
	typedef yes no[2];

	static T   type;

// integral types : https://www.cplusplus.com/reference/type_traits/is_integral/
	static yes& test(bool);
	static yes& test(char);
//	static yes& test(char16_t);
//	static yes& test(char32_t);
	static yes& test(wchar_t);
	static yes& test(signed char);
	static yes& test(short int);
	static yes& test(int);
	static yes& test(long int);
	static yes& test(long long int);
	static yes& test(unsigned char);
	static yes& test(unsigned short int);
	static yes& test(unsigned int);
	static yes& test(unsigned long int);
	static yes& test(unsigned long long int);

/*
	static yes& test(const bool);
	static yes& test(const char);
	static yes& test(const wchar_t);
	static yes& test(const signed char);
	static yes& test(const short int);
	static yes& test(const int);
	static yes& test(const long int);
	static yes& test(const long long int);
	static yes& test(const unsigned char);
	static yes& test(const unsigned short int);
	static yes& test(const unsigned int);
	static yes& test(const unsigned long int);
	static yes& test(const unsigned long long int);

	static yes& test(volatile bool);
	static yes& test(volatile char);
	static yes& test(volatile wchar_t);
	static yes& test(volatile signed char);
	static yes& test(volatile short int);
	static yes& test(volatile int);
	static yes& test(volatile long int);
	static yes& test(volatile long long int);
	static yes& test(volatile unsigned char);
	static yes& test(volatile unsigned short int);
	static yes& test(volatile unsigned int);
	static yes& test(volatile unsigned long int);
	static yes& test(volatile unsigned long long int);

	static yes& test(const volatile bool);
	static yes& test(const volatile char);
	static yes& test(const volatile wchar_t);
	static yes& test(const volatile signed char);
	static yes& test(const volatile short int);
	static yes& test(const volatile int);
	static yes& test(const volatile long int);
	static yes& test(const volatile long long int);
	static yes& test(const volatile unsigned char);
	static yes& test(const volatile unsigned short int);
	static yes& test(const volatile unsigned int);
	static yes& test(const volatile unsigned long int);
	static yes& test(const volatile unsigned long long int);
*/


	// non-template function with direct matching are always considered first
	// then the function template with direct matching are considered
	// https://stackoverflow.com/questions/12877546/how-do-i-avoid-implicit-conversions-on
	template <class C> static no& test(C);

	static const bool value = sizeof(test(type)) == sizeof(yes);
};

} // namespace ft

// "template <>" introduce a total specialization of a template :
//
//    template <typename T>
//    class A
//    {
//        // body for the general case
//    };
//
//    template <>
//    class A<bool>
//    {
//        // body that only applies for T = bool
//    };
//
// https://stackoverflow.com/questions/6288812/what-is-the-meaning-of-template-with-empty-angle-brackets-in-c

// SFINAE : https://jguegant.github.io/blogs/tech/sfinae-introduction.html

#endif