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  1. #include <tuple>
  2. #include <utility>
  3.  
  4. #include<boost/fusion/adapted/std_tuple.hpp>
  5. #include <boost/fusion/algorithm/transformation/reverse.hpp>
  6. #include <boost/fusion/include/reverse.hpp>
  7.  
  8. #include <boost/fusion/sequence/intrinsic/size.hpp>
  9. #include <boost/fusion/include/size.hpp>
  10.  
  11. #include <iostream>
  12.  
  13. template <std::size_t... Is>
  14. struct indices {};
  15.  
  16. template <std::size_t N, std::size_t... Is>
  17. struct build_indices
  18.   : build_indices<N-1, N-1, Is...> {};
  19.  
  20. template <std::size_t... Is>
  21. struct build_indices<0, Is...> : indices<Is...> {};
  22.  
  23. template<typename Sequence, std::size_t ...Is>
  24. auto as_std_tuple_impl(const Sequence& s, indices<Is...>&&) -> decltype(std::tie(boost::fusion::at_c<Is>(s)...))
  25. {
  26.     return std::tie(boost::fusion::at_c<Is>(s)...);
  27. }
  28.  
  29. template <typename Sequence, typename Indices = build_indices<boost::fusion::result_of::size<Sequence>::value>>
  30. auto as_std_tuple(const Sequence& s)
  31. {
  32.         return as_std_tuple_impl(s, Indices());
  33. }
  34.  
  35.  
  36. template<class Tuple, std::size_t N>
  37. struct TuplePrinter
  38. {
  39.     static void print(const Tuple& t) 
  40.     {
  41.         TuplePrinter<Tuple, N-1>::print(t);
  42.         std::cout << ", " << std::get<N-1>(t);
  43.     }
  44. };
  45.  
  46. template<class Tuple>
  47. struct TuplePrinter<Tuple, 1> 
  48. {
  49.     static void print(const Tuple& t) 
  50.     {
  51.         std::cout << std::get<0>(t);
  52.     }
  53. };
  54.  
  55. template<class... Args>
  56. void print(const std::tuple<Args...>& t) 
  57. {
  58.     std::cout << "(";
  59.     TuplePrinter<decltype(t), sizeof...(Args)>::print(t);
  60.     std::cout << ")\n";
  61. }
  62.  
  63. int main()
  64. {
  65.     std::tuple<int, double, std::string> tup(1,2.5,"hello");
  66.     auto view_rev = boost::fusion::reverse(tup);
  67.     auto reversed_tup = as_std_tuple(view_rev);
  68.  
  69.     print(tup);
  70.     print(reversed_tup);
  71.     return 0;
  72. }
Success #stdin #stdout 0s 3272KB
comments (?)
stdin
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Standard input is empty
stdout
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(1, 2.5, hello)
(hello, 2.5, 1)
https://ideone.com/62PKzd
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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