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The C and C++ Include Header Files

cat -n /usr/include/c++/15/ext/iterator

     1	// HP/SGI iterator extensions -*- C++ -*-
     2	
     3	// Copyright (C) 2001-2025 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
     7	// terms of the GNU General Public License as published by the
     8	// Free Software Foundation; either version 3, or (at your option)
     9	// any later version.
    10	
    11	// This library is distributed in the hope that it will be useful,
    12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
    13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    14	// GNU 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	/*
    26	 *
    27	 * Copyright (c) 1994
    28	 * Hewlett-Packard Company
    29	 *
    30	 * Permission to use, copy, modify, distribute and sell this software
    31	 * and its documentation for any purpose is hereby granted without fee,
    32	 * provided that the above copyright notice appear in all copies and
    33	 * that both that copyright notice and this permission notice appear
    34	 * in supporting documentation.  Hewlett-Packard Company makes no
    35	 * representations about the suitability of this software for any
    36	 * purpose.  It is provided "as is" without express or implied warranty.
    37	 *
    38	 *
    39	 * Copyright (c) 1996-1998
    40	 * Silicon Graphics Computer Systems, Inc.
    41	 *
    42	 * Permission to use, copy, modify, distribute and sell this software
    43	 * and its documentation for any purpose is hereby granted without fee,
    44	 * provided that the above copyright notice appear in all copies and
    45	 * that both that copyright notice and this permission notice appear
    46	 * in supporting documentation.  Silicon Graphics makes no
    47	 * representations about the suitability of this software for any
    48	 * purpose.  It is provided "as is" without express or implied warranty.
    49	 */
    50	
    51	/** @file ext/iterator
    52	 *  This file is a GNU extension to the Standard C++ Library (possibly
    53	 *  containing extensions from the HP/SGI STL subset).
    54	 */
    55	
    56	#ifndef _EXT_ITERATOR
    57	#define _EXT_ITERATOR 1
    58	
    59	#ifdef _GLIBCXX_SYSHDR
    60	#pragma GCC system_header
    61	#endif
    62	
    63	#include <bits/concept_check.h>
    64	#include <iterator>
    65	
    66	namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
    67	{
    68	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    69	
    70	  // There are two signatures for distance.  In addition to the one
    71	  // taking two iterators and returning a result, there is another
    72	  // taking two iterators and a reference-to-result variable, and
    73	  // returning nothing.  The latter seems to be an SGI extension.
    74	  // -- pedwards
    75	  template<typename _InputIterator, typename _Distance>
    76	    inline void
    77	    __distance(_InputIterator __first, _InputIterator __last,
    78		       _Distance& __n, std::input_iterator_tag)
    79	    {
    80	      // concept requirements
    81	      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    82	      while (__first != __last)
    83		{
    84		  ++__first;
    85		  ++__n;
    86		}
    87	    }
    88	
    89	  template<typename _RandomAccessIterator, typename _Distance>
    90	    inline void
    91	    __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
    92		       _Distance& __n, std::random_access_iterator_tag)
    93	    {
    94	      // concept requirements
    95	      __glibcxx_function_requires(_RandomAccessIteratorConcept<
    96					  _RandomAccessIterator>)
    97	      __n += __last - __first;
    98	    }
    99	
   100	  /**
   101	   *  This is an SGI extension.
   102	   *  @ingroup SGIextensions
   103	   *  @doctodo
   104	  */
   105	  template<typename _InputIterator, typename _Distance>
   106	    inline void
   107	    distance(_InputIterator __first, _InputIterator __last,
   108	             _Distance& __n)
   109	    {
   110	      // concept requirements -- taken care of in __distance
   111	      __distance(__first, __last, __n, std::__iterator_category(__first));
   112	    }
   113	
   114	_GLIBCXX_END_NAMESPACE_VERSION
   115	} // namespace
   116	
   117	#endif
   118