front_impl.hpp 1.0 KB

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  1. #ifndef BOOST_MPL_AUX_FRONT_IMPL_HPP_INCLUDED
  2. #define BOOST_MPL_AUX_FRONT_IMPL_HPP_INCLUDED
  3. // Copyright Aleksey Gurtovoy 2000-2004
  4. //
  5. // Distributed under the Boost Software License, Version 1.0.
  6. // (See accompanying file LICENSE_1_0.txt or copy at
  7. // http://www.boost.org/LICENSE_1_0.txt)
  8. //
  9. // See http://www.boost.org/libs/mpl for documentation.
  10. // $Id$
  11. // $Date$
  12. // $Revision$
  13. #include <boost/mpl/front_fwd.hpp>
  14. #include <boost/mpl/begin_end.hpp>
  15. #include <boost/mpl/deref.hpp>
  16. #include <boost/mpl/aux_/traits_lambda_spec.hpp>
  17. namespace boost { namespace mpl {
  18. // default implementation; conrete sequences might override it by
  19. // specializing either the 'front_impl' or the primary 'front' template
  20. template< typename Tag >
  21. struct front_impl
  22. {
  23. template< typename Sequence > struct apply
  24. {
  25. typedef typename begin<Sequence>::type iter_;
  26. typedef typename deref<iter_>::type type;
  27. };
  28. };
  29. BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(1,front_impl)
  30. }}
  31. #endif // BOOST_MPL_AUX_FRONT_IMPL_HPP_INCLUDED