ceph/src/boost/libs/fusion/include/boost/fusion/sequence/hash.hpp

   1 /*=============================================================================
   2     Copyright (c) 2014 Christoph Weiss
   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_HASH_23072014_1017)
   8 #define FUSION_HASH_23072014_1017
   9
  10 #include <boost/functional/hash.hpp>
  11 #include <boost/fusion/algorithm/iteration/fold.hpp>
  12 #include <boost/fusion/support/is_sequence.hpp>
  13 #include <boost/utility/enable_if.hpp>
  14
  15 namespace boost { namespace fusion
  16 {
  17     namespace hashing
  18     {
  19         struct hash_combine_fold
  20         {
  21             typedef std::size_t result_type;
  22             template<typename T>
  23             inline std::size_t operator()(std::size_t seed, T const& v)
  24             {
  25                 boost::hash_combine(seed, v);
  26                 return seed;
  27             }
  28         };
  29
  30         template <typename Seq>
  31         inline typename
  32         boost::enable_if<traits::is_sequence<Seq>, std::size_t>::type
  33         hash_value(Seq const& seq)
  34         {
  35             return fold(seq, 0, hash_combine_fold());
  36         }
  37     }
  38
  39     using hashing::hash_value;
  40 }}
  41
  42 #endif