ceph/src/boost/boost/fusion/sequence/intrinsic/has_key.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2011 Joel de Guzman
   3
   4     Distributed under the Boost Software License, Version 1.0. (See accompanying
   5     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 ==============================================================================*/
   7 #if !defined(FUSION_HAS_KEY_09232005_1454)
   8 #define FUSION_HAS_KEY_09232005_1454
   9
  10 #include <boost/fusion/support/config.hpp>
  11 #include <boost/fusion/sequence/intrinsic_fwd.hpp>
  12 #include <boost/fusion/support/tag_of.hpp>
  13 #include <boost/fusion/iterator/equal_to.hpp>
  14 #include <boost/fusion/algorithm/query/find.hpp>
  15 #include <boost/fusion/sequence/intrinsic/end.hpp>
  16 #include <boost/mpl/not.hpp>
  17
  18 namespace boost { namespace fusion
  19 {
  20     struct void_;
  21
  22     // Special tags:
  23     struct sequence_facade_tag;
  24     struct boost_array_tag; // boost::array tag
  25     struct mpl_sequence_tag; // mpl sequence tag
  26     struct std_pair_tag; // std::pair tag
  27
  28     namespace extension
  29     {
  30         template <typename Tag>
  31         struct has_key_impl
  32         {
  33             template <typename Seq, typename Key>
  34             struct apply
  35               : mpl::not_<
  36                     typename result_of::equal_to<
  37                         typename result_of::find<Seq, Key>::type
  38                       , typename result_of::end<Seq>::type
  39                     >::type
  40                 >::type
  41             {};
  42         };
  43
  44         template <>
  45         struct has_key_impl<sequence_facade_tag>
  46         {
  47             template <typename Sequence, typename Key>
  48             struct apply : Sequence::template has_key<Sequence, Key> {};
  49         };
  50
  51         template <>
  52         struct has_key_impl<boost_array_tag>;
  53
  54         template <>
  55         struct has_key_impl<mpl_sequence_tag>;
  56
  57         template <>
  58         struct has_key_impl<std_pair_tag>;
  59     }
  60
  61     namespace result_of
  62     {
  63         template <typename Sequence, typename Key>
  64         struct has_key
  65             : extension::has_key_impl<typename detail::tag_of<Sequence>::type>::
  66                 template apply<Sequence, Key>
  67         {};
  68     }
  69
  70     template <typename Key, typename Sequence>
  71     BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
  72     inline typename result_of::has_key<Sequence, Key>::type
  73     has_key(Sequence const&)
  74     {
  75         typedef typename result_of::has_key<Sequence, Key>::type result;
  76         return result();
  77     }
  78 }}
  79
  80 #endif
  81