Lazy zipper

#include <iostream>
#include <vector>
#include <tuple>

template <class T, class Y>
class zipper {
    class iterator {
    public:
        iterator(typename T::iterator tIt, typename Y::iterator yIt) : tIt(tIt), yIt(yIt) {}
        bool operator==(const iterator &i) {
            return (tIt==i.tIt || yIt==i.yIt);
        }
        std::tuple<typename T::value_type&, typename Y::value_type&> operator*() {
            return std::forward_as_tuple(*tIt, *yIt);
        }
        iterator& operator++() {
            ++tIt;
            ++yIt;
            return *this;
        }
        iterator operator++(int) {
            iterator tmp = *this;
            ++*this;
            return tmp;
        }
        bool operator!=(const iterator &i) {
            return (tIt!=i.tIt && yIt!=i.yIt);
        }
    private:
        typename T::iterator tIt;
        typename Y::iterator yIt;
    };
    T& t;
    Y& y;
public:
    zipper(T& t, Y& y) : t(t), y(y) {}
    iterator begin() { return iterator(t.begin(), y.begin()); }
    iterator end() { return iterator(t.end(), y.end()); }
};

template<class T, class Y>
zipper<T,Y> zip(T& t, Y& y) { return zipper<T,Y>(t, y); }

using namespace std;

int main() {
    vector<int> v{0,1,2};
    vector<string> u{"five","four","three","two","one"};
    for ( auto x : zip(u,v) ) {
        cout << get<0>(x) << "\t" << get<1>(x) << endl;
    }
}

/* Output:
 * "five    0"
 * "four    1"
 * "three   2"
 */