boost/boost/spirit/fusion/sequence/tie.hpp

   1 /*=============================================================================
   2     Copyright (c) 1999-2003 Jaakko Järvi
   3     Copyright (c) 2001-2003 Joel de Guzman
   4
   5     Use, modification and distribution is subject to the Boost Software
   6     License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   7     http://www.boost.org/LICENSE_1_0.txt)
   8 ==============================================================================*/
   9 #if !defined(FUSION_SEQUENCE_TIE_HPP)
  10 #define FUSION_SEQUENCE_TIE_HPP
  11
  12 #include <boost/ref.hpp>
  13 #include <boost/preprocessor/repetition/enum.hpp>
  14 #include <boost/preprocessor/repetition/enum_params.hpp>
  15 #include <boost/preprocessor/repetition/enum_binary_params.hpp>
  16 #include <boost/preprocessor/repetition/repeat_from_to.hpp>
  17 #include <boost/spirit/fusion/sequence/tuple.hpp>
  18
  19 namespace boost { namespace fusion
  20 {
  21     //  Swallows any assignment (by Doug Gregor)
  22     namespace detail
  23     {
  24         struct swallow_assign
  25         {
  26             template<typename T>
  27             swallow_assign const&
  28             operator=(const T&) const
  29             {
  30                 return *this;
  31             }
  32         };
  33     }
  34
  35     //  "ignore" allows tuple positions to be ignored when using "tie".
  36     detail::swallow_assign const ignore = detail::swallow_assign();
  37
  38 #define FUSION_REFERENCE_TYPE(z, n, data)                                       \
  39     BOOST_PP_CAT(T, n)&
  40
  41 #define FUSION_TIE(z, n, _)                                                     \
  42                                                                                 \
  43     template <BOOST_PP_ENUM_PARAMS(n, typename T)>                              \
  44     inline tuple<BOOST_PP_ENUM(n, FUSION_REFERENCE_TYPE, _)>                    \
  45     tie(BOOST_PP_ENUM_BINARY_PARAMS(n, T, & _))                                 \
  46     {                                                                           \
  47         return tuple<BOOST_PP_ENUM(n, FUSION_REFERENCE_TYPE, _)>(               \
  48             BOOST_PP_ENUM_PARAMS(n, _));                                        \
  49     }
  50
  51     BOOST_PP_REPEAT_FROM_TO(1, FUSION_MAX_TUPLE_SIZE, FUSION_TIE, _)
  52
  53 #undef FUSION_REFERENCE_TYPE
  54 #undef FUSION_TIE
  55
  56 }}
  57
  58 #endif