// In header: <boost/xpressive/regex_actions.hpp>


struct at {
  // member classes/structs/unions
  template<typename This, typename Cont, typename Idx> 
  struct result<This(Cont &, Idx)> {
    // types
    typedef Cont::reference type;
  };
  template<typename This, typename Cont, typename Idx> 
  struct result<This(Cont const &, Idx)> {
    // types
    typedef Cont::const_reference type;
  };
  template<typename This, typename Cont, typename Idx> 
  struct result<This(Cont, Idx)> :
    public boost::xpressive::op::at::result< This(Cont const &, Idx)>
  {
  };

  // public member functions
  template<typename Cont, typename Idx> 
    Cont::reference operator()(Cont &, Idx idx ) const;
  template<typename Cont, typename Idx> 
    Cont::const_reference operator()(Cont const &, Idx) const;
};