text: 
  #ifndef BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED
  #define BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED
  
  // Copyright Aleksey Gurtovoy 2000-2004
  //
  // Distributed under the Boost Software License, Version 1.0.
  // (See accompanying file LICENSE_1_0.txt or copy at 
  // http://www.boost.org/LICENSE_1_0.txt)
  //
  // See http://www.boost.org/libs/mpl for documentation.
  
  // $Id: begin_end_impl.hpp 49267 2008-10-11 06:19:02Z agurtovoy $
  // $Date: 2008-10-11 08:19:02 +0200 (sam., 11 oct. 2008) $
  // $Revision: 49267 $
  
  #include <boost/mpl/begin_end_fwd.hpp>
  #include <boost/mpl/sequence_tag_fwd.hpp>
  #include <boost/mpl/void.hpp>
  #include <boost/mpl/eval_if.hpp>
  #include <boost/mpl/aux_/has_begin.hpp>
  #include <boost/mpl/aux_/na.hpp>
  #include <boost/mpl/aux_/traits_lambda_spec.hpp>
  #include <boost/mpl/aux_/config/eti.hpp>
  
  namespace boost { namespace mpl {
  
  
  namespace aux { 
  
  template< typename Sequence > 
  struct begin_type 
  { 
      typedef typename Sequence::begin type; 
  };
  template< typename Sequence > 
  struct end_type
  { 
      typedef typename Sequence::end type; 
  };
  
  }
  
  // default implementation; conrete sequences might override it by 
  // specializing either the 'begin_impl/end_impl' or the primary 
  // 'begin/end' templates
  
  template< typename Tag >
  struct begin_impl
  {
      template< typename Sequence > struct apply
      {
          typedef typename eval_if<aux::has_begin<Sequence, true_>,
                                   aux::begin_type<Sequence>, void_>::type type;
      };
  };
  
  template< typename Tag >
  struct end_impl
  {
      template< typename Sequence > struct apply
      {
          typedef typename eval_if<aux::has_begin<Sequence, true_>,
                                   aux::end_type<Sequence>, void_>::type type;
      };
  };
  
  // specialize 'begin_trait/end_trait' for two pre-defined tags
  
  #   define AUX778076_IMPL_SPEC(name, tag, result) \
  template<> \
  struct name##_impl<tag> \
  { \
      template< typename Sequence > struct apply \
      { \
          typedef result type; \
      }; \
  }; \
  /**/
  
  // a sequence with nested 'begin/end' typedefs; just query them
  AUX778076_IMPL_SPEC(begin, nested_begin_end_tag, typename Sequence::begin)
  AUX778076_IMPL_SPEC(end, nested_begin_end_tag, typename Sequence::end)
  
  // if a type 'T' does not contain 'begin/end' or 'tag' members 
  // and doesn't specialize either 'begin/end' or 'begin_impl/end_impl' 
  // templates, then we end up here
  AUX778076_IMPL_SPEC(begin, non_sequence_tag, void_)
  AUX778076_IMPL_SPEC(end, non_sequence_tag, void_)
  AUX778076_IMPL_SPEC(begin, na, void_)
  AUX778076_IMPL_SPEC(end, na, void_)
  
  #   undef AUX778076_IMPL_SPEC
  
  
  BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC_IMPL(1,begin_impl)
  BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC_IMPL(1,end_impl)
  
  }}
  
  #endif // BOOST_MPL_AUX_BEGIN_END_IMPL_HPP_INCLUDED
  