ceph/src/boost/libs/spirit/include/boost/spirit/home/qi/detail/unused_skipper.hpp

   1 //  Copyright (c) 2001-2011 Hartmut Kaiser
   2 //
   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(BOOST_SPIRIT_QI_UNUSED_SKIPPER_JUL_25_2009_0921AM)
   7 #define BOOST_SPIRIT_QI_UNUSED_SKIPPER_JUL_25_2009_0921AM
   8
   9 #if defined(_MSC_VER)
  10 #pragma once
  11 #endif
  12
  13 #include <boost/spirit/home/support/unused.hpp>
  14 #include <boost/mpl/bool.hpp>
  15
  16 namespace boost { namespace spirit { namespace qi { namespace detail
  17 {
  18     template <typename Skipper>
  19     struct unused_skipper : unused_type
  20     {
  21         unused_skipper(Skipper const& skipper_)
  22           : skipper(skipper_) {}
  23         Skipper const& skipper;
  24
  25     private:
  26         // silence MSVC warning C4512: assignment operator could not be generated
  27         unused_skipper& operator= (unused_skipper const&);
  28     };
  29
  30     template <typename Skipper>
  31     struct is_unused_skipper
  32       : mpl::false_ {};
  33
  34     template <typename Skipper>
  35     struct is_unused_skipper<unused_skipper<Skipper> >
  36       : mpl::true_ {};
  37
  38     template <>
  39     struct is_unused_skipper<unused_type>
  40       : mpl::true_ {};
  41
  42     // If a surrounding lexeme[] directive was specified, the current
  43     // skipper is of the type unused_skipper. In this case we
  44     // re-activate the skipper which was active before the skip[]
  45     // directive.
  46     template <typename Skipper>
  47     inline Skipper const&
  48     get_skipper(unused_skipper<Skipper> const& u)
  49     {
  50         return u.skipper;
  51     }
  52
  53     // If no surrounding lexeme[] directive was specified we keep what we got.
  54     template <typename Skipper>
  55     inline Skipper const&
  56     get_skipper(Skipper const& u)
  57     {
  58         return u;
  59     }
  60
  61 }}}}
  62
  63 #endif