text: ///////////////////////////////////////////////////////////////////////////////
  /// \file pop_back.hpp
  /// Proto callables Fusion pop_back
  //
  //  Copyright 2010 Eric Niebler. 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)
  
  #ifndef QSBOOST_PROTO_FUNCTIONAL_FUSION_POP_BACK_HPP_EAN_11_27_2010
  #define QSBOOST_PROTO_FUNCTIONAL_FUSION_POP_BACK_HPP_EAN_11_27_2010
  
  #include <qsboost/fusion/include/begin.hpp>
  #include <qsboost/fusion/include/end.hpp>
  #include <qsboost/fusion/include/prior.hpp>
  #include <qsboost/fusion/include/pop_back.hpp>
  #include <qsboost/proto/proto_fwd.hpp>
  
  namespace qsboost { namespace proto { namespace functional
  {
      /// \brief A PolymorphicFunctionObject type that invokes the
      /// \c fusion::pop_back() algorithm on its argument.
      ///
      /// A PolymorphicFunctionObject type that invokes the
      /// \c fusion::pop_back() algorithm on its argument.
      struct pop_back
      {
          QSBOOST_PROTO_CALLABLE()
  
          template<typename Sig>
          struct result;
  
          template<typename This, typename Seq>
          struct result<This(Seq)>
            : result<This(Seq const &)>
          {};
  
          template<typename This, typename Seq>
          struct result<This(Seq &)>
            : fusion::result_of::pop_back<Seq>
          {};
  
          template<typename Seq>
          typename fusion::result_of::pop_back<Seq>::type
          operator ()(Seq &seq) const
          {
              // Work around a const-correctness issue in Fusion
              typedef typename fusion::result_of::pop_back<Seq>::type result_type;
              return result_type(fusion::begin(seq), fusion::prior(fusion::end(seq)));
          }
  
          template<typename Seq>
          typename fusion::result_of::pop_back<Seq const>::type
          operator ()(Seq const &seq) const
          {
              return fusion::pop_back(seq);
          }
      };
  }}}
  
  #endif
  