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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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,

// 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