ceph/src/boost/libs/spirit/include/boost/spirit/home/x3/support/traits/is_variant.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2014 Joel de Guzman
   3     http://spirit.sourceforge.net/
   4
   5     Distributed under the Boost Software License, Version 1.0. (See accompanying
   6     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7 =============================================================================*/
   8 #if !defined(BOOST_SPIRIT_X3_IS_VARIANT_JAN_10_2012_0823AM)
   9 #define BOOST_SPIRIT_X3_IS_VARIANT_JAN_10_2012_0823AM
  10
  11 #include <boost/variant.hpp>
  12 #include <boost/mpl/has_xxx.hpp>
  13 #include <boost/mpl/bool.hpp>
  14
  15 namespace boost { namespace spirit { namespace x3 { namespace traits
  16 {
  17     namespace detail
  18     {
  19         // By declaring a nested struct in your class/struct, you tell
  20         // spirit that it is regarded as a variant type. The minimum
  21         // required interface for such a variant is that it has constructors
  22         // for various types supported by your variant and a typedef 'types'
  23         // which is an mpl sequence of the contained types.
  24         //
  25         // This is an intrusive interface. For a non-intrusive interface,
  26         // use the is_variant trait.
  27         BOOST_MPL_HAS_XXX_TRAIT_DEF(adapted_variant_tag)
  28     }
  29
  30     template <typename T, typename Enable = void>
  31     struct is_variant
  32       : detail::has_adapted_variant_tag<T>
  33     {};
  34
  35     template <BOOST_VARIANT_ENUM_PARAMS(typename T)>
  36     struct is_variant<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>>
  37       : mpl::true_
  38     {};
  39 }}}}
  40
  41 #endif