[C++ STL] iterator_traits

• https://cplusplus.com/reference/iterator/iterator_traits/?kw=iterator_traits
• 이터레이터 속성을 정의하는 특성 클래스이다.
• 모든 이터레이터는 최소한 아래 멤버 타입을 포함해야 함.

template <class Iterator>
class iterator_traits
{
	typedef typename Iterator::difference_type difference_type;
	typedef typename Iterator::value_type value_type;
	typedef typename Iterator::pointer pointer;
	typedef typename Iterator::reference reference;
	typedef typename Iterator::iterator_category iterator_category;
};

template <class T>
class iterator_traits<T *>
{
	typedef typename std::ptrdiff_t difference_type;
	typedef T value_type;
	typedef T *pointer;
	typedef T &reference;
	typedef typename ft::random_access_iterator_tag iterator_category;
};

template <class T>
class iterator_traits<const T *>
{
	typedef typename std::ptrdiff_t difference_type;
	typedef T value_type;
	typedef const T *pointer;
	typedef const T &reference;
	typedef typename ft::random_access_iterator_tag iterator_category;
};