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// -*- C++ -*-
// Copyright (C) 2005 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 2, 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.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING. If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
// 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 MASK_BASED_RANGE_HASHING_HPP
#define MASK_BASED_RANGE_HASHING_HPP
namespace pb_assoc
{
namespace detail
{
#define PB_ASSOC_CLASS_T_DEC \
template<typename Size_Type>
#define PB_ASSOC_CLASS_C_DEC \
mask_based_range_hashing< \
Size_Type>
template<typename Size_Type>
class mask_based_range_hashing
{
protected:
typedef Size_Type size_type;
protected:
void
swap(PB_ASSOC_CLASS_C_DEC& r_other);
void
notify_resized(size_type size);
inline size_type
range_hash(size_type hash) const;
private:
size_type m_mask;
const static size_type s_num_bits_in_size_type;
const static size_type s_highest_bit_1;
};
PB_ASSOC_CLASS_T_DEC
const typename PB_ASSOC_CLASS_C_DEC::size_type
PB_ASSOC_CLASS_C_DEC::s_num_bits_in_size_type =
sizeof(typename PB_ASSOC_CLASS_C_DEC::size_type) << 3;
PB_ASSOC_CLASS_T_DEC
const typename PB_ASSOC_CLASS_C_DEC::size_type
PB_ASSOC_CLASS_C_DEC::s_highest_bit_1 =
(typename PB_ASSOC_CLASS_C_DEC::size_type) 1
<< (s_num_bits_in_size_type - 1);
PB_ASSOC_CLASS_T_DEC
void
PB_ASSOC_CLASS_C_DEC::
swap(PB_ASSOC_CLASS_C_DEC& r_other)
{
std::swap(m_mask, r_other.m_mask);
}
PB_ASSOC_CLASS_T_DEC
void
PB_ASSOC_CLASS_C_DEC::
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;
}
PB_ASSOC_CLASS_T_DEC
inline typename PB_ASSOC_CLASS_C_DEC::size_type
PB_ASSOC_CLASS_C_DEC::
range_hash(size_type hash) const
{
return (hash& m_mask);
}
#undef PB_ASSOC_CLASS_T_DEC
#undef PB_ASSOC_CLASS_C_DEC
} // namespace detail
} // namespace pb_assoc
#endif // #ifndef MASK_BASED_RANGE_HASHING_HPP
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