q3.cpp

// Question 3
// Provide a template function “get_vector”, similar to std::get, that given the type X as parameter, returns editable access to the vector of type X in a tuple of vectors.

#include <iostream>
#include <tuple>
#include <vector>
#include <utility>
#include <type_traits>
#include <assert.h>

using namespace std;

template < std::size_t... N , typename... T >
auto tail_impl( std::index_sequence<N...> , std::tuple<T...> t ) {
   return  std::make_tuple( std::get<N+1>(t)... );
}

template <class F, class... R >
tuple<R...> tail( std::tuple<F,R...> t ) {
   return  tail_impl( std::make_index_sequence<sizeof...(R)>() , t );
}

template<class T>
void print_vec(const vector<T>& v) {
    for(auto& x:v) {
        cout << x << '\n';
    }
    cout << endl;
}


template<typename X, typename T>
vector<X>& get_vector(T& t) {
    return get<vector<X>>(t);
}

int main( int argc, const char *argv[] ) {
    auto a = vector<int>({4,5,3});
    auto b = vector<char>({'s', 'a', 'g', 'a'});
    auto c = vector<double>({3.232,32.3,2.33});
    auto t = make_tuple(a,b,c);
    vector<char>& f = get_vector<char>(t);
    f.push_back('r');
    print_vec(f);
    print_vec(get<0>(tail(t)));
    return 0;
}