Question

I want to write my own algorithm (just a function really) that takes a range of iterators. If the iterators are from a map, I want to use the data (iterator->second) value. If the iterator is “normal” like a vector or list, I just want to use the dereferenced iterator value.

Answer 1

I think, value-getter idea is right here, but you can implement it without c++11 and without structs at all, only using functions:

template <typename T> 
const T& get(const T& t)
{
    return t;
}

template <typename T, typename V>
const V& get(const std::pair<T,V>& t)
{
    return t.second;
}


int main()
{
    std::vector<int> v = {1};
    std::cout << get(*v.begin());

    std::cout << "\n----\n";

    std::map<int, std::string> m;
    m.insert(std::make_pair(0, "sss"));
    std::cout << get(*m.cbegin());
}