at_impl.hpp 1.4 KB

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  1. /*=============================================================================
  2. Copyright (c) 2007 Tobias Schwinger
  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(BOOST_FUSION_ITERATOR_RANGE_AT_IMPL_HPP_INCLUDED)
  7. #define BOOST_FUSION_ITERATOR_RANGE_AT_IMPL_HPP_INCLUDED
  8. #include <boost/fusion/support/config.hpp>
  9. #include <boost/fusion/iterator/advance.hpp>
  10. #include <boost/fusion/iterator/deref.hpp>
  11. namespace boost { namespace fusion
  12. {
  13. struct iterator_range_tag;
  14. namespace extension
  15. {
  16. template <typename Tag>
  17. struct at_impl;
  18. template <>
  19. struct at_impl<iterator_range_tag>
  20. {
  21. template <typename Seq, typename N>
  22. struct apply
  23. {
  24. typedef typename Seq::begin_type begin_type;
  25. typedef typename result_of::advance<begin_type,N>::type pos;
  26. typedef typename result_of::deref<pos>::type type;
  27. BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  28. static type
  29. call(Seq& s)
  30. {
  31. return * fusion::advance<N>(s.first);
  32. }
  33. };
  34. };
  35. }
  36. }}
  37. #endif