Tuples.hh

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#ifndef GAMROOT_UTILS_TUPLES_HH
#define GAMROOT_UTILS_TUPLES_HH
 
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-variable"
// auto l causes some complaints but has a purpose for enforcing
// iteration order
 
/* STD */
#include <tuple>
 
namespace GamR {
  namespace Utils {
    // https://ideone.com/j6dNE5
    // https://stackoverflow.com/questions/16387354/template-tuple-calling-a-function-on-each-element
    // Basically a missing feature in the language until C++17
    // Though be warned, in C++17 std::apply might have randomised order of
    // iteration This should be first element to last as expected.
#ifndef DOXYGEN_SHOULD_SKIP_THIS
 
    template <int... Is>
    struct seq {
    };
 
    template <int N, int... Is>
    struct gen_seq : gen_seq<N - 1, N - 1, Is...> {
    };
 
    template <int... Is>
    struct gen_seq<0, Is...> : seq<Is...> {
    };
 
    template <typename T, typename F, int... Is>
    void for_each(T &&t, F f, seq<Is...>)
    {
      auto l = {(f(std::get<Is>(t)), 0)...};
    }
 
    // Logical extension of above but for two tuples
    template <typename T1, typename T2, typename F, int... Is>
    void for_both(T1 &&t1, T2 &&t2, F f, seq<Is...>)
    {
      auto l = {(f(std::get<Is>(t1), std::get<Is>(t2)), 0)...};
    
    }
    template <typename T1, typename T2, typename F, int... Is, typename N>
    void for_both(T1 &&t1, T2 &&t2, F f, seq<Is...>, N n)
    {
      auto l = {(f(std::get<Is>(t1), std::get<Is>(t2), n), 0)...};
    }
 
    
#endif

    template <typename... Ts, typename F>
    void for_each_in_tuple(std::tuple<Ts...> &t, F f)
    {
      for_each(t, f, gen_seq<sizeof...(Ts)>());
    }

    template <typename T1, typename T2, typename F>
    void for_both_in_tuple(T1 &t1, T2 &t2, F f)
    {
      for_both(t1, t2, f, gen_seq<std::tuple_size<T1>::value>());
    }
 
    template <typename T1, typename T2, typename F, typename N>
    void for_both_in_tuple(T1 &t1, T2 &t2, F f, N n)
    {
      for_both(t1, t2, f, gen_seq<std::tuple_size<T1>::value>(), n);
    }
 
  } // namespace Utils
} // namespace GamR
 
#pragma GCC diagnostic pop
 
#endif