ceph/src/boost/boost/callable_traits/detail/forward_declarations.hpp

   1 #ifndef BOOST_CLBL_TRTS_DETAIL_FORWARD_DECLARATIONS
   2 #define BOOST_CLBL_TRTS_DETAIL_FORWARD_DECLARATIONS
   3 #include <boost/callable_traits/detail/config.hpp>
   4 #include <boost/callable_traits/detail/default_callable_traits.hpp>
   5
   6 namespace boost { namespace callable_traits { namespace detail {
   7
   8 template<typename T>
   9 struct function;
  10
  11 template<typename T>
  12 struct has_normal_call_operator
  13 {
  14     template<typename N, N Value>
  15     struct check { check(std::nullptr_t) {} };
  16
  17     template<typename U>
  18     static std::int8_t test(
  19         check<decltype(&U::operator()), &U::operator()>);
  20
  21     template<typename>
  22     static std::int16_t test(...);
  23
  24     static constexpr bool value =
  25         sizeof(test<T>(nullptr)) == sizeof(std::int8_t);
  26 };
  27
  28 struct callable_dummy {
  29     void operator()() {}
  30 };
  31
  32 template<typename T>
  33 using default_to_function_object = typename std::conditional<
  34     has_normal_call_operator<T>::value,
  35     T, callable_dummy>::type;
  36
  37 template<typename T>
  38 struct pmf;
  39
  40 template<typename T>
  41 struct pmd;
  42
  43 template<typename F, typename T = typename std::remove_reference<F>::type>
  44 using function_object_base = typename std::conditional<
  45     has_normal_call_operator<T>::value,
  46     pmf<decltype(&default_to_function_object<T>::operator())>,
  47     default_callable_traits<T>>::type;
  48
  49 template<typename T, typename Base = function_object_base<T>>
  50 struct function_object;
  51
  52 }}} // namespace boost::callable_traits::detail
  53
  54 #endif // #ifndef BOOST_CLBL_TRTS_DETAIL_FORWARD_DECLARATIONS