function_traits.h

Go to the documentation of this file.

#pragma once

#include <functional>
#include <type_traits>

// Type traits class for functions.
// Allows to query result and argument types of free and member functions as
// well as of operator() of functors.

namespace tc {

template <typename T>
struct function_traits : public function_traits<decltype(&T::operator())> {};

#define FUNCTION_TRAITS_STRUCT_BODY                                         \
  typedef R result_type;                                                    \
                                                                            \
  template <size_t i>                                                       \
  struct arg {                                                              \
    typedef typename std::tuple_element<i, std::tuple<Args...>>::type type; \
  };                                                                        \
                                                                            \
  typedef std::tuple<Args...> packed_args_type;                             \
  typedef R (*c_function_type)(Args...);                                    \
  constexpr static size_t n_args = sizeof...(Args)

template <typename ClassType, typename R, typename... Args>
struct function_traits<R (ClassType::*)(Args...) const> {
  FUNCTION_TRAITS_STRUCT_BODY;
  constexpr static bool is_member = true;
  constexpr static bool is_static_member = true;
  typedef ClassType class_type;
};

template <typename R, typename... Args>
struct function_traits<R (*)(Args...)> {
  FUNCTION_TRAITS_STRUCT_BODY;
  constexpr static bool is_member = false;
};

} // namespace tc