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The C and C++ Include Header Files

cat -n /usr/include/c++/15/ext/pb_ds/detail/hash_fn/mask_based_range_hashing.hpp

     1	// -*- C++ -*-
     2	
     3	// Copyright (C) 2005-2025 Free Software Foundation, Inc.
     4	//
     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
     9	// version.
    10	
    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.
    15	
    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.
    19	
    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/>.
    24	
    25	// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
    26	
    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
    30	// and this permission notice appear in supporting documentation. None
    31	// of the above authors, nor IBM Haifa Research Laboratories, make any
    32	// representation about the suitability of this software for any
    33	// purpose. It is provided "as is" without express or implied
    34	// warranty.
    35	
    36	/**
    37	 * @file mask_based_range_hashing.hpp
    38	 * Contains a range hashing policy base.
    39	 */
    40	
    41	#ifndef PB_DS_MASK_BASED_RANGE_HASHING_HPP
    42	#define PB_DS_MASK_BASED_RANGE_HASHING_HPP
    43	
    44	namespace __gnu_pbds
    45	{
    46	  namespace detail
    47	  {
    48	    /// Range hashing policy.
    49	    template<typename Size_Type>
    50	    class mask_based_range_hashing
    51	    {
    52	    protected:
    53	      typedef Size_Type 	size_type;
    54	
    55	      void
    56	      swap(mask_based_range_hashing& other)
    57	      { std::swap(m_mask, other.m_mask); }
    58	
    59	      void
    60	      notify_resized(size_type size);
    61	
    62	      inline size_type
    63	      range_hash(size_type hash) const
    64	      { return size_type(hash & m_mask); }
    65	
    66	    private:
    67	      size_type 		m_mask;
    68	      const static size_type 	s_num_bits_in_size_type;
    69	      const static size_type 	s_highest_bit_1;
    70	    };
    71	
    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;
    76	
    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);
    79	
    80	 
    81	    template<typename Size_Type>
    82	    void
    83	    mask_based_range_hashing<Size_Type>::
    84	    notify_resized(size_type size)
    85	    {
    86	      size_type i = 0;
    87	      while (size ^ s_highest_bit_1)
    88		{
    89		  size <<= 1;
    90		  ++i;
    91		}
    92	
    93	      m_mask = 1;
    94	      i += 2;
    95	      while (i++ < s_num_bits_in_size_type)
    96	        m_mask = (m_mask << 1) ^ 1;
    97	    }
    98	  } // namespace detail
    99	} // namespace __gnu_pbds
   100	
   101	#endif