libstdc++
hash_eq_fn.hpp
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1 // -*- C++ -*-
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3 // Copyright (C) 2005-2019 Free Software Foundation, Inc.
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25 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
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35 
36 /**
37  * @file hash_eq_fn.hpp
38  * Contains 2 eqivalence functions, one employing a hash value,
39  * and one ignoring it.
40  */
41 
42 #ifndef PB_DS_HASH_EQ_FN_HPP
43 #define PB_DS_HASH_EQ_FN_HPP
44 
45 #include <utility>
46 #include <debug/debug.h>
47 
48 namespace __gnu_pbds
49 {
50  namespace detail
51  {
52  /// Primary template.
53  template<typename Key, typename Eq_Fn, typename _Alloc, bool Store_Hash>
54  struct hash_eq_fn;
55 
56  /// Specialization 1 - The client requests that hash values not be stored.
57  template<typename Key, typename Eq_Fn, typename _Alloc>
58  struct hash_eq_fn<Key, Eq_Fn, _Alloc, false> : public Eq_Fn
59  {
60  typedef Eq_Fn eq_fn_base;
61  typedef typename _Alloc::template rebind<Key>::other key_allocator;
62  typedef typename key_allocator::const_reference key_const_reference;
63 
64  hash_eq_fn() { }
65 
66  hash_eq_fn(const Eq_Fn& r_eq_fn) : Eq_Fn(r_eq_fn) { }
67 
68  bool
69  operator()(key_const_reference r_lhs_key,
70  key_const_reference r_rhs_key) const
71  { return eq_fn_base::operator()(r_lhs_key, r_rhs_key); }
72 
73  void
74  swap(const hash_eq_fn& other)
75  { std::swap((Eq_Fn&)(*this), (Eq_Fn&)other); }
76  };
77 
78 
79  /// Specialization 2 - The client requests that hash values be stored.
80  template<typename Key, class Eq_Fn, class _Alloc>
81  struct hash_eq_fn<Key, Eq_Fn, _Alloc, true> : public Eq_Fn
82  {
83  typedef typename _Alloc::size_type size_type;
84  typedef Eq_Fn eq_fn_base;
85  typedef typename _Alloc::template rebind<Key>::other key_allocator;
86  typedef typename key_allocator::const_reference key_const_reference;
87 
88  hash_eq_fn() { }
89 
90  hash_eq_fn(const Eq_Fn& r_eq_fn) : Eq_Fn(r_eq_fn) { }
91 
92  bool
93  operator()(key_const_reference r_lhs_key, size_type lhs_hash,
94  key_const_reference r_rhs_key, size_type rhs_hash) const
95  {
96  _GLIBCXX_DEBUG_ASSERT(!eq_fn_base::operator()(r_lhs_key, r_rhs_key)
97  || lhs_hash == rhs_hash);
98 
99  return (lhs_hash == rhs_hash &&
100  eq_fn_base::operator()(r_lhs_key, r_rhs_key));
101  }
102 
103  void
104  swap(const hash_eq_fn& other)
105  { std::swap((Eq_Fn&)(*this), (Eq_Fn&)(other)); }
106  };
107  } // namespace detail
108 } // namespace __gnu_pbds
109 
110 #endif
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