ceph/src/boost/libs/fusion/test/compile_time/sfinae_friendly.hpp

   1 /*=============================================================================
   2     Copyright (c) 2015 Kohei Takahashi
   3
   4     Use modification and distribution are subject to the Boost Software
   5     License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   6     http://www.boost.org/LICENSE_1_0.txt).
   7 ==============================================================================*/
   8
   9 #ifndef FUSION_TEST_SFINAE_FRIENDLY_HPP
  10 #define FUSION_TEST_SFINAE_FRIENDLY_HPP
  11
  12 #include <boost/config.hpp>
  13 #include <boost/mpl/bool.hpp>
  14 #include <boost/mpl/assert.hpp>
  15 #include <boost/utility/result_of.hpp>
  16 #include <boost/core/enable_if.hpp>
  17
  18 #if !defined(BOOST_NO_SFINAE) && defined(BOOST_RESULT_OF_USE_DECLTYPE)
  19
  20 #include <boost/fusion/container/vector.hpp>
  21
  22 namespace sfinae_friendly
  23 {
  24     template <typename> struct arg_;
  25     template <typename R, typename T> struct arg_<R(T)> { typedef T type; };
  26
  27     template <typename Traits, typename = void>
  28     struct check
  29         : boost::mpl::true_ { };
  30
  31     template <typename Traits>
  32     struct check<Traits, typename boost::enable_if_has_type<typename Traits::type>::type>
  33         : boost::mpl::false_ { };
  34
  35     struct unspecified {};
  36     typedef boost::fusion::vector<> v0;
  37     typedef boost::fusion::vector<unspecified> v1;
  38     typedef boost::fusion::vector<unspecified, unspecified> v2;
  39     typedef boost::fusion::vector<unspecified, unspecified, unspecified> v3;
  40 }
  41
  42 #define SFINAE_FRIENDLY_ASSERT(Traits) \
  43     BOOST_MPL_ASSERT((::sfinae_friendly::check<typename ::sfinae_friendly::arg_<void Traits>::type>))
  44
  45 #else
  46
  47 #define SFINAE_FRIENDLY_ASSERT(Traits) \
  48     BOOST_MPL_ASSERT((boost::mpl::true_))
  49
  50 #endif
  51
  52 #endif // FUSION_TEST_SFINAE_FRIENDLY_HPP
  53