mdds
cref_wrapper.hpp
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28 
29 #pragma once
30 
31 #include <functional>
32 #include <type_traits>
33 
34 namespace mdds { namespace detail {
35 
40 template<typename T>
42 {
43  std::reference_wrapper<std::add_const_t<T>> m_value;
44 
45 public:
46  cref_wrapper(const T& v) : m_value(std::cref(v))
47  {}
48 
49  const T& get() const
50  {
51  return m_value;
52  }
53 
54  bool operator==(const cref_wrapper& r) const
55  {
56  return get() == r.get();
57  }
58 
59  bool operator!=(const cref_wrapper& r) const
60  {
61  return !operator==(r);
62  }
63 
64  struct hash
65  {
66  std::size_t operator()(const cref_wrapper& v) const
67  {
68  // NB: hash value must be based on the wrapped value, else two
69  // identical values located in different memory locations may end up
70  // in different buckets, and the lookup may fail.
71  return std::hash<T>{}(v.m_value);
72  }
73  };
74 };
75 
76 }} // namespace mdds::detail
77 
78 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
Definition: cref_wrapper.hpp:41
Definition: cref_wrapper.hpp:64
Definition: cref_wrapper.hpp:34