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  1.     #include <string>
  2.     #include <iostream>
  3.     #include <tuple>
  4.     #include <vector>
  5.  
  6.     namespace detail
  7.     {
  8.         template<int... Is>
  9.         struct seq { };
  10.  
  11.         template<int N, int... Is>
  12.         struct gen_seq : gen_seq<N - 1, N - 1, Is...> { };
  13.  
  14.         template<int... Is>
  15.         struct gen_seq<0, Is...> : seq<Is...> { };
  16.  
  17.         template<typename T, typename F, int... Is>
  18.         void for_each(T&& t, F f, seq<Is...>)
  19.         {
  20.             auto l = { (f(std::get<Is>(std::forward<T>(t))), 0)... };
  21.         }
  22.     }
  23.  
  24.     template<typename... Ts, typename F>
  25.     void for_each_in_tuple(std::tuple<Ts...> const& t, F f)
  26.     {
  27.         detail::for_each(t, f, detail::gen_seq<sizeof...(Ts)>());
  28.     }
  29.  
  30.     template<typename... Ts>
  31.     struct TupleOfVectors
  32.     {
  33.         std::tuple<std::vector<Ts>...> t;
  34.  
  35.         void do_something_to_each_vec()
  36.         {
  37.             for_each_in_tuple(t, tuple_vector_functor());
  38.         }
  39.  
  40.         struct tuple_vector_functor
  41.         {
  42.             template<typename T>
  43.             void operator () (T const &v)
  44.             {
  45.                 std::cout << "{ ";
  46.                 bool first = true;
  47.                 for (auto const& x : v)
  48.                 {
  49.                     if (!first) { std::cout << ", "; };
  50.                     std::cout << x;
  51.                     first = false;
  52.                 }
  53.                 std::cout << " }" << std::endl;
  54.             }
  55.         };
  56.     };
  57.  
  58.     int main()
  59.     {
  60.         TupleOfVectors<int, double, std::string> tv;
  61.         std::get<0>(tv.t).push_back(42);
  62.         std::get<0>(tv.t).push_back(1729);
  63.  
  64.         std::get<1>(tv.t).push_back(3.14);
  65.  
  66.         std::get<2>(tv.t).push_back("Hello");
  67.         std::get<2>(tv.t).push_back("World");
  68.         std::get<2>(tv.t).push_back("of");
  69.         std::get<2>(tv.t).push_back("Tuples!");
  70.  
  71.         tv.do_something_to_each_vec();
  72.     }
  73.  
Success #stdin #stdout 0s 2988KB
comments (?)
stdin
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Standard input is empty
stdout
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{ 42, 1729 }
{ 3.14 }
{ Hello, World, of, Tuples! }
https://ideone.com/ndDaM2
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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