c++ enumerate

enumerate.hpp

// http://reedbeta.com/blog/python-like-enumerate-in-cpp17/?fbclid=IwAR3b_OJ61ol7pU525NxcIzureSBU1emoSQtvVG3L_q_pCvBcO4yKyyHU6OA

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


template <typename T,
          typename TIter = decltype(std::begin(std::declval<T>())),
          typename = decltype(std::end(std::declval<T>()))>
constexpr auto enumerate(T && iterable)
{
    struct iterator
    {
        size_t i;
        TIter iter;
        bool operator != (const iterator & other) const { return iter != other.iter; }
        void operator ++ () { ++i; ++iter; }
        auto operator * () const { return std::tie(i, *iter); }
    };
    struct iterable_wrapper
    {
        T iterable;
        auto begin() { return iterator{ 0, std::begin(iterable) }; }
        auto end() { return iterator{ 0, std::end(iterable) }; }
    };
    return iterable_wrapper{ std::forward<T>(iterable) };
}


int main()
{
    std::vector<int> v = {1,2,3,4,5,6,7,8,9,10};
    for (auto [i, thing] : enumerate(v))
        {
            std::cout << "i:" << i << "\tT:" << thing << std::endl;
        }
    return 0;
}