hana/concept/sequence.hpp

0001 /*!
0002 @file
0003 Defines `boost::hana::Sequence`.
0004
0005 Copyright Louis Dionne 2013-2022
0006 Distributed under the Boost Software License, Version 1.0.
0007 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
0008  */
0009
0010 #ifndef BOOST_HANA_CONCEPT_SEQUENCE_HPP
0011 #define BOOST_HANA_CONCEPT_SEQUENCE_HPP
0012
0013 #include <boost/hana/fwd/concept/sequence.hpp>
0014
0015 #include <boost/hana/config.hpp>
0016 #include <boost/hana/core/tag_of.hpp>
0017 #include <boost/hana/core/when.hpp>
0018 #include <boost/hana/detail/integral_constant.hpp>
0019
0020
0021 namespace boost { namespace hana {
0022     namespace detail {
0023         template <typename S, typename Tag = typename hana::tag_of<S>::type>
0024         struct sequence_dispatch
0025             : hana::integral_constant<bool,
0026                 hana::Sequence<Tag>::value
0027             >
0028         { };
0029
0030         template <typename S>
0031         struct sequence_dispatch<S, S>
0032             : hana::integral_constant<bool, false>
0033         { };
0034     }
0035
0036     //! @cond
0037     template <typename S, bool condition>
0038     struct Sequence<S, when<condition>>
0039         : detail::sequence_dispatch<S>
0040     { };
0041     //! @endcond
0042 }} // end namespace boost::hana
0043
0044 #endif // !BOOST_HANA_CONCEPT_SEQUENCE_HPP