Initial move from Spirit CVS

[SVN r34896]

include/boost/fusion/sequence/intrinsic/empty.hpp

@@ -0,0 +1,49 @@
+/*=============================================================================
+    Copyright (c) 2001-2006 Joel de Guzman
+
+    Use, modification and distribution is subject to 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(FUSION_EMPTY_09162005_0335)
+#define FUSION_EMPTY_09162005_0335
+
+#include <boost/fusion/sequence/intrinsic/size.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/fusion/support/tag_of.hpp>
+
+namespace boost { namespace fusion
+{
+    struct fusion_sequence_tag;
+
+    namespace extension
+    {
+        template <typename Tag>
+        struct empty_impl
+        {
+            template <typename Sequence>
+            struct apply 
+                : mpl::bool_<(result_of::size<Sequence>::value == 0)>
+            {};
+        };
+    }
+
+    namespace result_of
+    {
+        template <typename Sequence>
+        struct empty 
+            : extension::empty_impl<typename detail::tag_of<Sequence>::type>::
+                template apply<Sequence>
+        {};
+    }
+
+    template <typename Sequence>
+    inline typename result_of::empty<Sequence>::type
+    empty(Sequence const&)
+    {
+        static typename result_of::empty<Sequence>::type result;
+        return result;
+    }
+}}
+
+#endif