3 // Copyright (C) 2005-2018 Free Software Foundation, Inc.
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
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.
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.
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/>.
25 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
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
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37 * @file mask_based_range_hashing.hpp
38 * Contains a range hashing policy base.
41 #ifndef PB_DS_MASK_BASED_RANGE_HASHING_HPP
42 #define PB_DS_MASK_BASED_RANGE_HASHING_HPP
48 /// Range hashing policy.
49 template<typename Size_Type>
50 class mask_based_range_hashing
53 typedef Size_Type size_type;
56 swap(mask_based_range_hashing& other)
57 { std::swap(m_mask, other.m_mask); }
60 notify_resized(size_type size);
63 range_hash(size_type hash) const
64 { return size_type(hash & m_mask); }
68 const static size_type s_num_bits_in_size_type;
69 const static size_type s_highest_bit_1;
72 template<typename Size_Type>
73 const typename mask_based_range_hashing<Size_Type>::size_type
74 mask_based_range_hashing<Size_Type>::s_num_bits_in_size_type =
75 sizeof(typename mask_based_range_hashing<Size_Type>::size_type) << 3;
77 template<typename Size_Type>
78 const typename mask_based_range_hashing<Size_Type>::size_type mask_based_range_hashing<Size_Type>::s_highest_bit_1 = static_cast<typename mask_based_range_hashing<Size_Type>::size_type>(1) << (s_num_bits_in_size_type - 1);
81 template<typename Size_Type>
83 mask_based_range_hashing<Size_Type>::
84 notify_resized(size_type size)
87 while (size ^ s_highest_bit_1)
95 while (i++ < s_num_bits_in_size_type)
96 m_mask = (m_mask << 1) ^ 1;
99 } // namespace __gnu_pbds