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 42