1 /*============================================================================= 2 Copyright (c) 2001-2011 Joel de Guzman 3 4 Distributed under the Boost Software License, Version 1.0. (See accompanying 5 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6 ==============================================================================*/ 7 #if !defined(FUSION_IS_VIEW_03202006_0015) 8 #define FUSION_IS_VIEW_03202006_0015 9 10 #include <boost/fusion/support/config.hpp> 11 #include <boost/mpl/bool.hpp> 12 #include <boost/fusion/support/tag_of.hpp> 13 14 namespace boost { namespace fusion 15 { 16 // Special tags: 17 struct non_fusion_tag; 18 struct sequence_facade_tag; 19 struct boost_tuple_tag; // boost::tuples::tuple tag 20 struct boost_array_tag; // boost::array tag 21 struct mpl_sequence_tag; // mpl sequence tag 22 struct std_pair_tag; // std::pair tag 23 24 namespace extension 25 { 26 template<typename Tag> 27 struct is_view_impl 28 { 29 template <typename T> 30 struct apply 31 { 32 typedef typename T::is_view type; 33 }; 34 }; 35 36 template <> 37 struct is_view_impl<non_fusion_tag> 38 { 39 template <typename T> 40 struct apply : mpl::false_ {}; 41 }; 42 43 template <> 44 struct is_view_impl<sequence_facade_tag> 45 { 46 template <typename Sequence> 47 struct apply : Sequence::is_view {}; 48 }; 49 50 template <> 51 struct is_view_impl<boost_tuple_tag>; 52 53 template <> 54 struct is_view_impl<boost_array_tag>; 55 56 template <> 57 struct is_view_impl<mpl_sequence_tag>; 58 59 template <> 60 struct is_view_impl<std_pair_tag>; 61 } 62 63 namespace traits 64 { 65 template <typename T> 66 struct is_view : 67 mpl::bool_< 68 (bool)extension::is_view_impl<typename fusion::detail::tag_of<T>::type>:: 69 template apply<T>::type::value 70 > 71 {}; 72 } 73 }} 74 75 #endif 76