ceph/src/boost/boost/callable_traits/has_varargs.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_HAS_VARARGS_HPP
  10 #define BOOST_CLBL_TRTS_HAS_VARARGS_HPP
  11
  12 #include <boost/callable_traits/detail/core.hpp>
  13
  14 namespace boost { namespace callable_traits {
  15
  16 //[ has_varargs_hpp
  17 /*`[section:ref_has_varargs has_varargs]
  18 [heading Header]
  19 ``#include <boost/callable_traits/has_varargs.hpp>``
  20 [heading Definition]
  21 */
  22
  23
  24 // inherits from either std::true_type or std::false_type
  25 template<typename T>
  26 struct has_varargs;
  27
  28 //<-
  29 template<typename T>
  30 struct has_varargs : detail::traits<
  31     detail::shallow_decay<T>>::has_varargs {
  32
  33     using type = typename detail::traits<
  34         detail::shallow_decay<T>>::has_varargs;
  35 };
  36
  37 #ifdef BOOST_CLBL_TRTS_DISABLE_VARIABLE_TEMPLATES
  38
  39 template<typename T>
  40 struct has_varargs_v {
  41     static_assert(std::is_same<T, detail::dummy>::value,
  42         "Variable templates not supported on this compiler.");
  43 };
  44
  45 #else
  46 //->
  47 // only available when variable templates are supported
  48 template<typename T>
  49 //<-
  50 BOOST_CLBL_TRAITS_INLINE_VAR
  51 //->
  52 constexpr bool has_varargs_v = //see below
  53 //<-
  54     detail::traits<detail::shallow_decay<T>>::has_varargs::value;
  55
  56 #endif
  57
  58 }} // namespace boost::callable_traits
  59 //->
  60
  61 /*`
  62 [heading Constraints]
  63 * none
  64
  65 [heading Behavior]
  66 * `std::false_type` is inherited by `has_varargs<T>` and is aliased by `typename has_varargs<T>::type`, except when one of the following criteria is met, in which case `std::true_type` would be similarly inherited and aliased:
  67   * `T` is a function, function pointer, or function reference where the function's parameter list includes C-style variadics.
  68   * `T` is a pointer to a member function with C-style variadics in the parameter list.
  69   * `T` is a function object with a non-overloaded `operator()`, which has C-style variadics in the parameter list of its `operator()`.
  70 * On compilers that support variable templates, `has_varargs_v<T>` is equivalent to `has_varargs<T>::value`.
  71
  72 [heading Input/Output Examples]
  73 [table
  74     [[`T`]                              [`has_varargs_v<T>`]]
  75     [[`void(...)`]                      [`true`]]
  76     [[`void(int, ...) const`]           [`true`]]
  77     [[`void(* volatile)(...)`]          [`true`]]
  78     [[`void(&)(...)`]                   [`true`]]
  79     [[`void(foo::*)(...) const`]        [`true`]]
  80     [[`void(*)()`]                      [`false`]]
  81     [[`void(*&)()`]                     [`false`]]
  82     [[`int`]                            [`false`]]
  83     [[`const int`]                      [`false`]]
  84     [[`int foo::*`]                     [`false`]]
  85 ]
  86
  87 [heading Example Program]
  88 [import ../example/has_varargs.cpp]
  89 [has_varargs]
  90 [endsect]
  91 */
  92 //]
  93
  94 #endif