ceph/src/boost/boost/parameter/aux_/is_maybe.hpp

   1 // Copyright Daniel Wallin, David Abrahams 2010.
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE_1_0.txt or copy at
   4 // http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #ifndef BOOST_PARAMETER_IS_MAYBE_050329_HPP
   7 #define BOOST_PARAMETER_IS_MAYBE_050329_HPP
   8
   9 namespace boost { namespace parameter { namespace aux {
  10
  11     struct maybe_base
  12     {
  13     };
  14 }}} // namespace boost::parameter::aux
  15
  16 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
  17 #include <type_traits>
  18
  19 namespace boost { namespace parameter { namespace aux {
  20
  21     template <typename T>
  22     using is_maybe = ::std::is_base_of<
  23         ::boost::parameter::aux::maybe_base
  24       , typename ::std::remove_const<T>::type
  25     >;
  26 }}} // namespace boost::parameter::aux
  27
  28 #else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
  29 #include <boost/mpl/bool.hpp>
  30 #include <boost/mpl/if.hpp>
  31 #include <boost/type_traits/is_base_of.hpp>
  32 #include <boost/type_traits/remove_const.hpp>
  33
  34 namespace boost { namespace parameter { namespace aux {
  35
  36     template <typename T>
  37     struct is_maybe
  38       : ::boost::mpl::if_<
  39             ::boost::is_base_of<
  40                 ::boost::parameter::aux::maybe_base
  41               , typename ::boost::remove_const<T>::type
  42             >
  43           , ::boost::mpl::true_
  44           , ::boost::mpl::false_
  45         >::type
  46     {
  47     };
  48 }}} // namespace boost::parameter::aux
  49
  50 #endif  // BOOST_PARAMETER_CAN_USE_MP11
  51 #endif  // include guard
  52