Imported Upstream version 1.57.0upstream/1.57.0

1 files changed, 45 insertions, 0 deletions

diff --git a/boost/spirit/home/x3/support/traits/is_variant.hpp b/boost/spirit/home/x3/support/traits/is_variant.hpp
new file mode 100644
index 0000000000..829a673c3f
--- /dev/null
+++ b/boost/spirit/home/x3/support/traits/is_variant.hpp
@@ -0,0 +1,45 @@
+/*=============================================================================
+    Copyright (c) 2001-2014 Joel de Guzman
+    http://spirit.sourceforge.net/
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#if !defined(BOOST_SPIRIT_X3_IS_VARIANT_JAN_10_2012_0823AM)
+#define BOOST_SPIRIT_X3_IS_VARIANT_JAN_10_2012_0823AM
+
+#if defined(_MSC_VER)
+#pragma once
+#endif
+
+#include <boost/variant.hpp>
+#include <boost/mpl/has_xxx.hpp>
+#include <boost/mpl/bool.hpp>
+
+namespace boost { namespace spirit { namespace x3 { namespace traits
+{
+    namespace detail
+    {
+        // By declaring a nested struct in your class/struct, you tell
+        // spirit that it is regarded as a variant type. The minimum
+        // required interface for such a variant is that it has constructors
+        // for various types supported by your variant and a typedef 'types'
+        // which is an mpl sequence of the contained types.
+        //
+        // This is an intrusive interface. For a non-intrusive interface,
+        // use the is_variant trait.
+        BOOST_MPL_HAS_XXX_TRAIT_DEF(adapted_variant_tag)
+    }
+
+    template <typename T, typename Enable = void>
+    struct is_variant
+      : detail::has_adapted_variant_tag<T>
+    {};
+
+    template <BOOST_VARIANT_ENUM_PARAMS(typename T)>
+    struct is_variant<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>>
+      : mpl::true_
+    {};
+}}}}
+
+#endif