// -*- C++ -*-
|
|
// Copyright (C) 2005-2020 Free Software Foundation, Inc.
|
//
|
// This file is part of the GNU ISO C++ Library. This library is free
|
// software; you can redistribute it and/or modify it under the terms
|
// of the GNU General Public License as published by the Free Software
|
// Foundation; either version 3, or (at your option) any later
|
// version.
|
|
// This library is distributed in the hope that it will be useful, but
|
// WITHOUT ANY WARRANTY; without even the implied warranty of
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
// General Public License for more details.
|
|
// Under Section 7 of GPL version 3, you are granted additional
|
// permissions described in the GCC Runtime Library Exception, version
|
// 3.1, as published by the Free Software Foundation.
|
|
// You should have received a copy of the GNU General Public License and
|
// a copy of the GCC Runtime Library Exception along with this program;
|
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
// <http://www.gnu.org/licenses/>.
|
|
// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
|
|
// Permission to use, copy, modify, sell, and distribute this software
|
// is hereby granted without fee, provided that the above copyright
|
// notice appears in all copies, and that both that copyright notice
|
// and this permission notice appear in supporting documentation. None
|
// of the above authors, nor IBM Haifa Research Laboratories, make any
|
// representation about the suitability of this software for any
|
// purpose. It is provided "as is" without express or implied
|
// warranty.
|
|
/**
|
* @file mask_based_range_hashing.hpp
|
* Contains a range hashing policy base.
|
*/
|
|
#ifndef PB_DS_MASK_BASED_RANGE_HASHING_HPP
|
#define PB_DS_MASK_BASED_RANGE_HASHING_HPP
|
|
namespace __gnu_pbds
|
{
|
namespace detail
|
{
|
/// Range hashing policy.
|
template<typename Size_Type>
|
class mask_based_range_hashing
|
{
|
protected:
|
typedef Size_Type size_type;
|
|
void
|
swap(mask_based_range_hashing& other)
|
{ std::swap(m_mask, other.m_mask); }
|
|
void
|
notify_resized(size_type size);
|
|
inline size_type
|
range_hash(size_type hash) const
|
{ return size_type(hash & m_mask); }
|
|
private:
|
size_type m_mask;
|
const static size_type s_num_bits_in_size_type;
|
const static size_type s_highest_bit_1;
|
};
|
|
template<typename Size_Type>
|
const typename mask_based_range_hashing<Size_Type>::size_type
|
mask_based_range_hashing<Size_Type>::s_num_bits_in_size_type =
|
sizeof(typename mask_based_range_hashing<Size_Type>::size_type) << 3;
|
|
template<typename Size_Type>
|
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);
|
|
|
template<typename Size_Type>
|
void
|
mask_based_range_hashing<Size_Type>::
|
notify_resized(size_type size)
|
{
|
size_type i = 0;
|
while (size ^ s_highest_bit_1)
|
{
|
size <<= 1;
|
++i;
|
}
|
|
m_mask = 1;
|
i += 2;
|
while (i++ < s_num_bits_in_size_type)
|
m_mask = (m_mask << 1) ^ 1;
|
}
|
} // namespace detail
|
} // namespace __gnu_pbds
|
|
#endif
|
