ceph/src/boost/boost/callable_traits/is_invocable.hpp

   1 /*
   2
   3 @Copyright Barrett Adair 2015-2017
   4 Distributed under the Boost Software License, Version 1.0.
   5 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   6
   7 */
   8
   9 #ifndef BOOST_CLBL_TRTS_IS_INVOCABLE_HPP
  10 #define BOOST_CLBL_TRTS_IS_INVOCABLE_HPP
  11
  12 #include <boost/callable_traits/detail/core.hpp>
  13 #include <boost/callable_traits/detail/is_invocable_impl.hpp>
  14
  15 namespace boost { namespace callable_traits {
  16
  17 //[ is_invocable_hpp
  18 /*`[section:ref_is_invocable is_invocable]
  19 [heading Header]
  20 ``#include <boost/callable_traits/is_invocable.hpp>``
  21 [heading Definition]
  22 */
  23
  24 // inherits from either std::true_type or std::false_type
  25 template<typename T, typename... Args>
  26 struct is_invocable;
  27
  28 // inherits from either std::true_type or std::false_type
  29 template<typename Ret, typename T, typename... Args>
  30 struct is_invocable_r;
  31
  32 //<-
  33 template<typename T, typename... Args>
  34 struct is_invocable : detail::is_invocable_impl<T, Args...>::type {
  35     using type = typename detail::is_invocable_impl<T, Args...>::type;
  36 };
  37
  38 template<typename Ret, typename T, typename... Args>
  39 struct is_invocable_r
  40   : detail::is_invocable_r_impl<
  41         typename detail::is_invocable_impl<T, Args...>::type, Ret, T, Args...>::type
  42 {
  43     using type = typename detail::is_invocable_r_impl<
  44         typename detail::is_invocable_impl<T, Args...>::type, Ret, T, Args...>::type;
  45 };
  46
  47 #ifdef BOOST_CLBL_TRTS_DISABLE_VARIABLE_TEMPLATES
  48
  49 template<typename T, typename... Args>
  50 struct is_invocable_v {
  51     static_assert(std::is_same<T, detail::dummy>::value,
  52         "Variable templates not supported on this compiler.");
  53 };
  54
  55 template<typename Ret, typename T, typename... Args>
  56 struct is_invocable_r_v {
  57     static_assert(std::is_same<T, detail::dummy>::value,
  58         "Variable templates not supported on this compiler.");
  59 };
  60
  61 #else
  62 //->
  63 // only available when variable templates are supported
  64 template<typename T, typename... Args>
  65 //<-
  66 BOOST_CLBL_TRAITS_INLINE_VAR
  67 //->
  68 constexpr bool is_invocable_v = //see below
  69 //<-
  70     detail::is_invocable_impl<detail::traits<T>, Args...>::type::value;
  71 //->
  72
  73 // only available when variable templates are supported
  74 template<typename Ret, typename T, typename... Args>
  75 //<-
  76 BOOST_CLBL_TRAITS_INLINE_VAR
  77 //->
  78 constexpr bool is_invocable_r_v = //see below
  79 //<-
  80     detail::is_invocable_r_impl<
  81         typename detail::is_invocable_impl<T, Args...>::type,
  82         Ret, T, Args...>::type::value;
  83 #endif
  84
  85 }} // namespace boost::callable_traits
  86 //->
  87
  88 /*`
  89 [heading Constraints]
  90 * none
  91
  92 [heading Behavior]
  93 * standalone c++11 implementation of c++17 `std::is_invocable`, `std::is_invocable_r`
  94 [note ref-qualified overloads of `operator()` with different signatures are not handled correctly yet.]
  95
  96 [heading Example Program]
  97 [import ../example/is_invocable.cpp]
  98 [is_invocable]
  99 [endsect]
 100 */
 101 //]
 102
 103 #endif // #ifndef BOOST_CLBL_TRTS_IS_INVOCABLE_HPP