front.hpp 1.2 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_FRONT_09162005_0343)
  7. #define FUSION_FRONT_09162005_0343
  8. #include <boost/fusion/sequence/intrinsic_fwd.hpp>
  9. #include <boost/fusion/sequence/intrinsic/begin.hpp>
  10. #include <boost/fusion/iterator/deref.hpp>
  11. #include <boost/mpl/bool.hpp>
  12. namespace boost { namespace fusion
  13. {
  14. struct fusion_sequence_tag;
  15. namespace result_of
  16. {
  17. template <typename Sequence>
  18. struct front
  19. : result_of::deref<typename result_of::begin<Sequence>::type>
  20. {};
  21. }
  22. template <typename Sequence>
  23. inline typename result_of::front<Sequence>::type
  24. front(Sequence& seq)
  25. {
  26. return *fusion::begin(seq);
  27. }
  28. template <typename Sequence>
  29. inline typename result_of::front<Sequence const>::type
  30. front(Sequence const& seq)
  31. {
  32. return *fusion::begin(seq);
  33. }
  34. }}
  35. #endif