libstdc++
hash_eq_fn.hpp
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1// -*- C++ -*-
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3// Copyright (C) 2005-2019 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
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7// of the GNU General Public License as published by the Free Software
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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.
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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
48namespace __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
GNU extensions for policy-based data structures for public use.