C++14 De/serialization structures made simple

cxx14-serialization.cpp

#include <iostream>
#include <sstream>
#include <string>
#include <tuple>

template <size_t First, size_t Last>
struct ReadAux {
  template <typename Tuple>
  static auto& Exec(std::istream& os, Tuple&& args) {
    os >> std::get<First>(args);
    return ReadAux<First + 1, Last>::Exec(os, std::forward<Tuple>(args));
  }
};

template <size_t Last>
struct ReadAux<Last, Last> {
  template <typename Tuple>
  static auto& Exec(std::istream& os, Tuple&& args) {
    return os >> std::get<Last>(args);
  }
};

template <typename Tuple>
auto& operator>>(std::istream& os, Tuple&& args) {
  constexpr size_t size = std::tuple_size<Tuple>::value;
  return ReadAux<0, size - 1>::Exec(os, std::forward<Tuple>(args));
}

template <size_t First, size_t Last>
struct WriteAux {
  template <typename Tuple>
  static auto& Exec(std::ostream& os, Tuple&& args) {
    os << std::get<First>(args) << ", ";
    return WriteAux<First + 1, Last>::Exec(os, std::forward<Tuple>(args));
  }
};

template <size_t Last>
struct WriteAux<Last, Last> {
  template <typename Tuple>
  static auto& Exec(std::ostream& os, Tuple&& args) {
    return os << std::get<Last>(args);
  }
};

template <typename Tuple>
auto& operator<<(std::ostream& os, Tuple&& args) {
  constexpr size_t size = std::tuple_size<Tuple>::value;
  return WriteAux<0, size - 1>::Exec(os, std::forward<Tuple>(args));
}

// --- client

struct S {
  int num = 123;
  std::string str = "abc";
  auto members() const { return std::tie(num, str); }
  auto members() { return std::tie(num, str); }
};

int main() {
  std::stringstream ss;
  // avoid ambiguous overloading
  ss.write("123 abc", 7);
  S s;
  ss >> s.members();
  std::cout << s.members() << std::endl;
  return 0;
}