fusion/support/sequence_base.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2011 Joel de Guzman
0003     Copyright (c) 2007 Tobias Schwinger
0004
0005     Distributed under the Boost Software License, Version 1.0. (See accompanying
0006     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007 ==============================================================================*/
0008 #if !defined(FUSION_SEQUENCE_BASE_04182005_0737)
0009 #define FUSION_SEQUENCE_BASE_04182005_0737
0010
0011 #include <boost/config.hpp>
0012 #include <boost/fusion/support/config.hpp>
0013 #include <boost/mpl/begin_end_fwd.hpp>
0014
0015 namespace boost { namespace fusion
0016 {
0017     namespace detail
0018     {
0019         struct from_sequence_convertible_type
0020         {};
0021     }
0022
0023     template <typename Sequence>
0024     struct sequence_base
0025     {
0026         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0027         Sequence const&
0028         derived() const BOOST_NOEXCEPT
0029         {
0030             return static_cast<Sequence const&>(*this);
0031         }
0032
0033         BOOST_CXX14_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0034         Sequence&
0035         derived() BOOST_NOEXCEPT
0036         {
0037             return static_cast<Sequence&>(*this);
0038         }
0039
0040         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
0041         operator detail::from_sequence_convertible_type() const BOOST_NOEXCEPT
0042         {
0043             return detail::from_sequence_convertible_type();
0044         }
0045     };
0046
0047     struct fusion_sequence_tag;
0048 }}
0049
0050 namespace boost { namespace mpl
0051 {
0052     // Deliberately break mpl::begin, so it doesn't lie that a Fusion sequence
0053     // is not an MPL sequence by returning mpl::void_.
0054     // In other words: Fusion Sequences are always MPL Sequences, but they can
0055     // be incompletely defined.
0056     template<> struct begin_impl< boost::fusion::fusion_sequence_tag >;
0057 }}
0058
0059 #endif