libstdc++

hash_eq_fn.hpp
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1 // -*- C++ -*-
2
3 // Copyright (C) 2005-2013 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the terms
7 // of the GNU General Public License as published by the Free Software
8 // Foundation; either version 3, or (at your option) any later
9 // version.
10
11 // This library is distributed in the hope that it will be useful, but
12 // WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 // General Public License for more details.
15
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
26
27 // Permission to use, copy, modify, sell, and distribute this software
28 // is hereby granted without fee, provided that the above copyright
29 // notice appears in all copies, and that both that copyright notice
30 // and this permission notice appear in supporting documentation. None
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34 // warranty.
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