push_front.hpp 1.6 KB

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  1. /*=============================================================================
  2. Copyright (c) 2001-2011 Joel de Guzman
  3. Distributed under the Boost Software License, Version 1.0. (See accompanying
  4. file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  5. ==============================================================================*/
  6. #if !defined(FUSION_PUSH_FRONT_07162005_0749)
  7. #define FUSION_PUSH_FRONT_07162005_0749
  8. #include <boost/fusion/support/config.hpp>
  9. #include <boost/fusion/support/detail/as_fusion_element.hpp>
  10. #include <boost/fusion/view/joint_view/joint_view.hpp>
  11. #include <boost/fusion/view/single_view/single_view.hpp>
  12. #include <boost/fusion/support/is_sequence.hpp>
  13. #include <boost/utility/enable_if.hpp>
  14. namespace boost { namespace fusion
  15. {
  16. namespace result_of
  17. {
  18. template <typename Sequence, typename T>
  19. struct push_front
  20. {
  21. typedef fusion::single_view<typename detail::as_fusion_element<T>::type> single_view;
  22. typedef joint_view<single_view const, Sequence> type;
  23. };
  24. }
  25. template <typename Sequence, typename T>
  26. BOOST_CXX14_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  27. inline typename
  28. lazy_enable_if<
  29. traits::is_sequence<Sequence>
  30. , result_of::push_front<Sequence const, T>
  31. >::type
  32. push_front(Sequence const& seq, T const& x)
  33. {
  34. typedef typename result_of::push_front<Sequence const, T> push_front;
  35. typedef typename push_front::single_view single_view;
  36. typedef typename push_front::type result;
  37. single_view x_(x);
  38. return result(x_, seq);
  39. }
  40. }}
  41. #endif