my_std_rotate.cpp

my_std_rotate.cpp

// VS http://en.cppreference.com/w/cpp/algorithm/rotate
template <class ForwardIt>
ForwardIt rotate(ForwardIt first, ForwardIt n_first, ForwardIt last)
{
    if(first == n_first) return last;
    if(n_first == last) return first;
 
    ForwardIt next = n_first;
    
    do {
        std::iter_swap(first++, next++);
        if (first == n_first) n_first = next;
    }
    while (next != last);
    
    ForwardIt ret = first;
 
    while (n_first != last) {
        next = n_first;
        do {
            std::iter_swap(first++, next++);
            if (first == n_first) n_first = next;
        }
        while (next != last);
    }
 
    return ret;
}