ceph/src/boost/libs/functional/hash/examples/template.hpp

   1
   2 // Copyright 2012 Daniel James.
   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 // This is an example of how to write a hash function for a template
   7 // class.
   8
   9 #include <boost/functional/hash_fwd.hpp>
  10
  11 template <typename A, typename B>
  12 class my_pair
  13 {
  14     A value1;
  15     B value2;
  16 public:
  17     my_pair(A const& v1, B const& v2)
  18         : value1(v1), value2(v2)
  19     {}
  20
  21     bool operator==(my_pair const& other) const
  22     {
  23         return value1 == other.value1 &&
  24             value2 == other.value2;
  25     }
  26
  27     friend std::size_t hash_value(my_pair const& p)
  28     {
  29         std::size_t seed = 0;
  30         boost::hash_combine(seed, p.value1);
  31         boost::hash_combine(seed, p.value2);
  32
  33         return seed;
  34     }
  35 };
  36