ceph/src/boost/boost/leaf/detail/function_traits.hpp

   1 #ifndef BOOST_LEAF_DETAIL_FUNCTION_TRAITS_HPP_INCLUDED
   2 #define BOOST_LEAF_DETAIL_FUNCTION_TRAITS_HPP_INCLUDED
   3
   4 // Copyright (c) 2018-2020 Emil Dotchevski and Reverge Studios, Inc.
   5
   6 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   7 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   8
   9 #ifndef BOOST_LEAF_ENABLE_WARNINGS
  10 #   if defined(__clang__)
  11 #       pragma clang system_header
  12 #   elif (__GNUC__*100+__GNUC_MINOR__>301)
  13 #       pragma GCC system_header
  14 #   elif defined(_MSC_VER)
  15 #       pragma warning(push,1)
  16 #   endif
  17 #endif
  18
  19 #include <boost/leaf/detail/mp11.hpp>
  20 #include <tuple>
  21
  22 namespace boost { namespace leaf {
  23
  24     namespace leaf_detail
  25     {
  26         template<class...>
  27         struct gcc49_workaround //Thanks Glen Fernandes
  28         {
  29             using type = void;
  30         };
  31
  32         template<class... T>
  33         using void_t = typename gcc49_workaround<T...>::type;
  34
  35         template<class F,class V=void>
  36         struct function_traits
  37         {
  38             constexpr static int arity = -1;
  39         };
  40
  41         template<class F>
  42         struct function_traits<F, void_t<decltype(&F::operator())>>
  43         {
  44         private:
  45
  46             using tr = function_traits<decltype(&F::operator())>;
  47
  48         public:
  49
  50             using return_type = typename tr::return_type;
  51             static constexpr int arity = tr::arity - 1;
  52
  53             using mp_args = typename leaf_detail_mp11::mp_rest<typename tr::mp_args>;
  54
  55             template <int I>
  56             struct arg:
  57                 tr::template arg<I+1>
  58             {
  59             };
  60         };
  61
  62         template<class R, class... A>
  63         struct function_traits<R(A...)>
  64         {
  65             using return_type = R;
  66             static constexpr int arity = sizeof...(A);
  67
  68             using mp_args = leaf_detail_mp11::mp_list<A...>;
  69
  70             template <int I>
  71             struct arg
  72             {
  73                 static_assert(I < arity, "I out of range");
  74                 using type = typename std::tuple_element<I,std::tuple<A...>>::type;
  75             };
  76         };
  77
  78         template<class F> struct function_traits<F&> : function_traits<F> { };
  79         template<class F> struct function_traits<F&&> : function_traits<F> { };
  80         template<class R, class... A> struct function_traits<R(*)(A...)> : function_traits<R(A...)> { };
  81         template<class R, class... A> struct function_traits<R(* &)(A...)> : function_traits<R(A...)> { };
  82         template<class R, class... A> struct function_traits<R(* const &)(A...)> : function_traits<R(A...)> { };
  83         template<class C, class R, class... A> struct function_traits<R(C::*)(A...)> : function_traits<R(C&,A...)> { };
  84         template<class C, class R, class... A> struct function_traits<R(C::*)(A...) const> : function_traits<R(C const &,A...)> { };
  85         template<class C, class R> struct function_traits<R(C::*)> : function_traits<R(C&)> { };
  86
  87         template <class F>
  88         using fn_return_type = typename function_traits<F>::return_type;
  89
  90         template <class F, int I>
  91         using fn_arg_type = typename function_traits<F>::template arg<I>::type;
  92
  93         template <class F>
  94         using fn_mp_args = typename function_traits<F>::mp_args;
  95
  96     }
  97
  98 } }
  99
 100 #endif