libstdc++-v3/include/bits/stl_iterator_base_funcs.h

   1 // Functions used by iterators -*- C++ -*-
   2
   3 // Copyright (C) 2001 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 2, 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 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /*
  31  *
  32  * Copyright (c) 1994
  33  * Hewlett-Packard Company
  34  *
  35  * Permission to use, copy, modify, distribute and sell this software
  36  * and its documentation for any purpose is hereby granted without fee,
  37  * provided that the above copyright notice appear in all copies and
  38  * that both that copyright notice and this permission notice appear
  39  * in supporting documentation.  Hewlett-Packard Company makes no
  40  * representations about the suitability of this software for any
  41  * purpose.  It is provided "as is" without express or implied warranty.
  42  *
  43  *
  44  * Copyright (c) 1996-1998
  45  * Silicon Graphics Computer Systems, Inc.
  46  *
  47  * Permission to use, copy, modify, distribute and sell this software
  48  * and its documentation for any purpose is hereby granted without fee,
  49  * provided that the above copyright notice appear in all copies and
  50  * that both that copyright notice and this permission notice appear
  51  * in supporting documentation.  Silicon Graphics makes no
  52  * representations about the suitability of this software for any
  53  * purpose.  It is provided "as is" without express or implied warranty.
  54  */
  55
  56 /* NOTE: This is an internal header file, included by other STL headers.
  57  *   You should not attempt to use it directly.
  58  */
  59
  60 #ifndef __SGI_STL_INTERNAL_ITERATOR_BASE_FUNCS_H
  61 #define __SGI_STL_INTERNAL_ITERATOR_BASE_FUNCS_H
  62
  63 // This file contains all of the general iterator-related utility
  64 // functions, such as distance() and advance().
  65 // The internal file stl_iterator.h contains predefined iterators,
  66 // such as front_insert_iterator and istream_iterator.
  67
  68 #pragma GCC system_header
  69 #include <bits/concept_check.h>
  70
  71 namespace std
  72 {
  73
  74 // There are two signatures for distance.  In addition to the one taking
  75 // two iterators and returning a result, there is another taking two
  76 // iterators and a reference-to-result variable, and returning nothing.
  77 // The latter seems to be an SGI extension.   -- pedwards
  78 template <class _InputIterator, class _Distance>
  79 inline void __distance(_InputIterator __first, _InputIterator __last,
  80                        _Distance& __n, input_iterator_tag)
  81 {
  82   // concept requirements
  83   __glibcpp_function_requires(_InputIteratorConcept<_InputIterator>);
  84   while (__first != __last) { ++__first; ++__n; }
  85 }
  86
  87 template <class _RandomAccessIterator, class _Distance>
  88 inline void __distance(_RandomAccessIterator __first,
  89                        _RandomAccessIterator __last,
  90                        _Distance& __n, random_access_iterator_tag)
  91 {
  92   // concept requirements
  93   __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>);
  94   __n += __last - __first;
  95 }
  96
  97 template <class _InputIterator, class _Distance>
  98 inline void distance(_InputIterator __first,
  99                      _InputIterator __last, _Distance& __n)
 100 {
 101   // concept requirements -- taken care of in __distance
 102   __distance(__first, __last, __n, iterator_category(__first));
 103 }
 104
 105 template <class _InputIterator>
 106 inline typename iterator_traits<_InputIterator>::difference_type
 107 __distance(_InputIterator __first, _InputIterator __last, input_iterator_tag)
 108 {
 109   // concept requirements
 110   __glibcpp_function_requires(_InputIteratorConcept<_InputIterator>);
 111   typename iterator_traits<_InputIterator>::difference_type __n = 0;
 112   while (__first != __last) {
 113     ++__first; ++__n;
 114   }
 115   return __n;
 116 }
 117
 118 template <class _RandomAccessIterator>
 119 inline typename iterator_traits<_RandomAccessIterator>::difference_type
 120 __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
 121            random_access_iterator_tag)
 122 {
 123   // concept requirements
 124   __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>);
 125   return __last - __first;
 126 }
 127
 128 template <class _InputIterator>
 129 inline typename iterator_traits<_InputIterator>::difference_type
 130 distance(_InputIterator __first, _InputIterator __last)
 131 {
 132   // concept requirements -- taken care of in __distance
 133   typedef typename iterator_traits<_InputIterator>::iterator_category
 134     _Category;
 135   return __distance(__first, __last, _Category());
 136 }
 137
 138 template <class _InputIter, class _Distance>
 139 inline void __advance(_InputIter& __i, _Distance __n, input_iterator_tag)
 140 {
 141   // concept requirements
 142   __glibcpp_function_requires(_InputIteratorConcept<_InputIter>);
 143   while (__n--) ++__i;
 144 }
 145
 146 template <class _BidirectionalIterator, class _Distance>
 147 inline void __advance(_BidirectionalIterator& __i, _Distance __n,
 148                       bidirectional_iterator_tag)
 149 {
 150   // concept requirements
 151 __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIterator>);
 152   if (__n > 0)
 153     while (__n--) ++__i;
 154   else
 155     while (__n++) --__i;
 156 }
 157
 158 template <class _RandomAccessIterator, class _Distance>
 159 inline void __advance(_RandomAccessIterator& __i, _Distance __n,
 160                       random_access_iterator_tag)
 161 {
 162   // concept requirements
 163   __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>);
 164   __i += __n;
 165 }
 166
 167 template <class _InputIterator, class _Distance>
 168 inline void advance(_InputIterator& __i, _Distance __n)
 169 {
 170   // concept requirements -- taken care of in __advance
 171   __advance(__i, __n, iterator_category(__i));
 172 }
 173
 174 } // namespace std
 175
 176 #endif /* __SGI_STL_INTERNAL_ITERATOR_BASE_FUNCS_H */
 177
 178
 179 // Local Variables:
 180 // mode:C++
 181 // End: