fusion/support/is_sequence.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2011 Joel de Guzman
0003
0004     Distributed under the Boost Software License, Version 1.0. (See accompanying
0005     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 ==============================================================================*/
0007 #if !defined(FUSION_IS_SEQUENCE_05052005_1002)
0008 #define FUSION_IS_SEQUENCE_05052005_1002
0009
0010 #include <boost/fusion/support/config.hpp>
0011 #include <boost/fusion/support/sequence_base.hpp>
0012 #include <boost/fusion/support/tag_of.hpp>
0013 #include <boost/fusion/support/detail/is_native_fusion_sequence.hpp>
0014 #include <boost/mpl/bool.hpp>
0015 #include <boost/mpl/is_sequence.hpp>
0016 #include <boost/type_traits/is_convertible.hpp>
0017
0018 namespace boost { namespace fusion
0019 {
0020     // Special tags:
0021     struct non_fusion_tag;
0022     struct boost_tuple_tag; // boost::tuples::tuple tag
0023     struct boost_array_tag; // boost::array tag
0024     struct mpl_sequence_tag; // mpl sequence tag
0025     struct std_pair_tag; // std::pair tag
0026
0027     namespace extension
0028     {
0029         template <typename T>
0030         struct is_sequence_impl
0031         {
0032             template <typename Sequence>
0033             struct apply
0034               : is_convertible<Sequence, fusion::detail::from_sequence_convertible_type>
0035             {};
0036         };
0037
0038         template <>
0039         struct is_sequence_impl<non_fusion_tag>
0040         {
0041             template <typename T>
0042             struct apply : mpl::false_ {};
0043         };
0044
0045         template <>
0046         struct is_sequence_impl<boost_tuple_tag>;
0047
0048         template <>
0049         struct is_sequence_impl<boost_array_tag>;
0050
0051         template <>
0052         struct is_sequence_impl<mpl_sequence_tag>;
0053
0054         template <>
0055         struct is_sequence_impl<std_pair_tag>;
0056     }
0057
0058     namespace traits
0059     {
0060         template <typename T>
0061         struct is_sequence
0062           : mpl::bool_<
0063                 (bool)extension::is_sequence_impl<
0064                     typename fusion::detail::tag_of<T>::type
0065                 >::template apply<T>::type::value
0066             >
0067         {};
0068
0069         using detail::is_native_fusion_sequence;
0070     }
0071 }}
0072
0073 #endif