sequence.hpp 1.1 KB

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  1. /*!
  2. @file
  3. Defines `boost::hana::Sequence`.
  4. @copyright Louis Dionne 2013-2017
  5. Distributed under the Boost Software License, Version 1.0.
  6. (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
  7. */
  8. #ifndef BOOST_HANA_CONCEPT_SEQUENCE_HPP
  9. #define BOOST_HANA_CONCEPT_SEQUENCE_HPP
  10. #include <boost/hana/fwd/concept/sequence.hpp>
  11. #include <boost/hana/config.hpp>
  12. #include <boost/hana/core/tag_of.hpp>
  13. #include <boost/hana/core/when.hpp>
  14. #include <boost/hana/detail/integral_constant.hpp>
  15. BOOST_HANA_NAMESPACE_BEGIN
  16. namespace detail {
  17. template <typename S, typename Tag = typename hana::tag_of<S>::type>
  18. struct sequence_dispatch
  19. : hana::integral_constant<bool,
  20. hana::Sequence<Tag>::value
  21. >
  22. { };
  23. template <typename S>
  24. struct sequence_dispatch<S, S>
  25. : hana::integral_constant<bool, false>
  26. { };
  27. }
  28. //! @cond
  29. template <typename S, bool condition>
  30. struct Sequence<S, when<condition>>
  31. : detail::sequence_dispatch<S>
  32. { };
  33. //! @endcond
  34. BOOST_HANA_NAMESPACE_END
  35. #endif // !BOOST_HANA_CONCEPT_SEQUENCE_HPP