ceph/src/boost/boost/type_traits/detail/detector.hpp

   1 /*
   2 Copyright 2017-2018 Glen Joseph Fernandes
   3 <glenjofe -at- gmail.com>
   4
   5 Distributed under the Boost Software License,
   6 Version 1.0. (See accompanying file LICENSE_1_0.txt
   7 or copy at http://www.boost.org/LICENSE_1_0.txt)
   8 */
   9
  10 #ifndef BOOST_TT_DETAIL_DETECTOR_HPP_INCLUDED
  11 #define BOOST_TT_DETAIL_DETECTOR_HPP_INCLUDED
  12
  13 #include <boost/type_traits/integral_constant.hpp>
  14 #include <boost/type_traits/make_void.hpp>
  15
  16 namespace boost {
  17 namespace detail {
  18
  19 template<class T>
  20 using detector_t = typename boost::make_void<T>::type;
  21
  22 template<class Default, class, template<class...> class, class...>
  23 struct detector {
  24     using value_t = boost::false_type;
  25     using type = Default;
  26 };
  27
  28 template<class Default, template<class...> class Op, class... Args>
  29 struct detector<Default, detector_t<Op<Args...> >, Op, Args...> {
  30     using value_t = boost::true_type;
  31     using type = Op<Args...>;
  32 };
  33
  34 } /* detail */
  35 } /* boost */
  36
  37 #endif