apply.hh

// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_COMMON_STD_APPLY_HH
#define DUNE_COMMON_STD_APPLY_HH
 
#if __cpp_lib_apply
  #include <tuple>
#elif __cpp_lib_experimental_apply
  #include <experimental/tuple>
#else
  #include <cstddef>
  #include <utility>
  #include <tuple>
#endif
 
 
 
namespace Dune
{
 
  namespace Std
  {
 
#if __cpp_lib_apply
 
    using std::apply;
 
#elif __cpp_lib_experimental_apply
 
    using std::experimental::apply;
 
#else
 
    namespace Impl
    {
      template<class F, class ArgTuple, std::size_t... i>
      decltype(auto) applyHelper(F&& f, ArgTuple&& args, std::index_sequence<i...>)
      {
        return f(std::get<i>(args)...);
      }
    } // namespace Impl
 
 
 
    template<class F, class ArgTuple>
    decltype(auto) apply(F&& f, ArgTuple&& args)
    {
      auto indices = std::make_index_sequence<std::tuple_size<std::decay_t<ArgTuple>>::value>();
      return Impl::applyHelper(std::forward<F>(f), std::forward<ArgTuple>(args), indices);
    }
 
#endif
 
  } // namespace Std
} // namespace Dune
 
#endif // #ifndef DUNE_COMMON_STD_APPLY_HH