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

   1 /*
   2  *
   3  * Copyright (c) 1994
   4  * Hewlett-Packard Company
   5  *
   6  * Permission to use, copy, modify, distribute and sell this software
   7  * and its documentation for any purpose is hereby granted without fee,
   8  * provided that the above copyright notice appear in all copies and
   9  * that both that copyright notice and this permission notice appear
  10  * in supporting documentation.  Hewlett-Packard Company makes no
  11  * representations about the suitability of this software for any
  12  * purpose.  It is provided "as is" without express or implied warranty.
  13  *
  14  *
  15  * Copyright (c) 1996-1998
  16  * Silicon Graphics Computer Systems, Inc.
  17  *
  18  * Permission to use, copy, modify, distribute and sell this software
  19  * and its documentation for any purpose is hereby granted without fee,
  20  * provided that the above copyright notice appear in all copies and
  21  * that both that copyright notice and this permission notice appear
  22  * in supporting documentation.  Silicon Graphics makes no
  23  * representations about the suitability of this software for any
  24  * purpose.  It is provided "as is" without express or implied warranty.
  25  */
  26
  27 /* NOTE: This is an internal header file, included by other STL headers.
  28  *   You should not attempt to use it directly.
  29  */
  30
  31 #ifndef __SGI_STL_INTERNAL_ITERATOR_BASE_FUNCS_H
  32 #define __SGI_STL_INTERNAL_ITERATOR_BASE_FUNCS_H
  33
  34 // This file contains all of the general iterator-related utility
  35 // functions, such as distance() and advance().
  36 // The internal file stl_iterator.h contains predefined iterators,
  37 // such as front_insert_iterator and istream_iterator.
  38
  39 #pragma GCC system_header
  40 #include <bits/concept_check.h>
  41
  42 namespace std
  43 {
  44
  45 // There are two signatures for distance.  In addition to the one taking
  46 // two iterators and returning a result, there is another taking two
  47 // iterators and a reference-to-result variable, and returning nothing.
  48 // The latter seems to be an SGI extension.   -- pedwards
  49 template <class _InputIterator, class _Distance>
  50 inline void __distance(_InputIterator __first, _InputIterator __last,
  51                        _Distance& __n, input_iterator_tag)
  52 {
  53   // concept requirements
  54   __glibcpp_function_requires(_InputIteratorConcept<_InputIterator>);
  55   while (__first != __last) { ++__first; ++__n; }
  56 }
  57
  58 template <class _RandomAccessIterator, class _Distance>
  59 inline void __distance(_RandomAccessIterator __first,
  60                        _RandomAccessIterator __last,
  61                        _Distance& __n, random_access_iterator_tag)
  62 {
  63   // concept requirements
  64   __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>);
  65   __n += __last - __first;
  66 }
  67
  68 template <class _InputIterator, class _Distance>
  69 inline void distance(_InputIterator __first,
  70                      _InputIterator __last, _Distance& __n)
  71 {
  72   // concept requirements -- taken care of in __distance
  73   __distance(__first, __last, __n, iterator_category(__first));
  74 }
  75
  76 template <class _InputIterator>
  77 inline typename iterator_traits<_InputIterator>::difference_type
  78 __distance(_InputIterator __first, _InputIterator __last, input_iterator_tag)
  79 {
  80   // concept requirements
  81   __glibcpp_function_requires(_InputIteratorConcept<_InputIterator>);
  82   typename iterator_traits<_InputIterator>::difference_type __n = 0;
  83   while (__first != __last) {
  84     ++__first; ++__n;
  85   }
  86   return __n;
  87 }
  88
  89 template <class _RandomAccessIterator>
  90 inline typename iterator_traits<_RandomAccessIterator>::difference_type
  91 __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
  92            random_access_iterator_tag)
  93 {
  94   // concept requirements
  95   __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>);
  96   return __last - __first;
  97 }
  98
  99 template <class _InputIterator>
 100 inline typename iterator_traits<_InputIterator>::difference_type
 101 distance(_InputIterator __first, _InputIterator __last)
 102 {
 103   // concept requirements -- taken care of in __distance
 104   typedef typename iterator_traits<_InputIterator>::iterator_category
 105     _Category;
 106   return __distance(__first, __last, _Category());
 107 }
 108
 109 template <class _InputIter, class _Distance>
 110 inline void __advance_InputIter& __i, _Distance __n, input_iterator_tag)
 111 {
 112   // concept requirements
 113   __glibcpp_function_requires(_InputIteratorConcept<_InputIter>);
 114   while (__n--) ++__i;
 115 }
 116
 117 template <class _BidirectionalIterator, class _Distance>
 118 inline void __advance(_BidirectionalIterator& __i, _Distance __n,
 119                       bidirectional_iterator_tag)
 120 {
 121   // concept requirements
 122 __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIterator>);
 123   if (__n > 0)
 124     while (__n--) ++__i;
 125   else
 126     while (__n++) --__i;
 127 }
 128
 129 template <class _RandomAccessIterator, class _Distance>
 130 inline void __advance(_RandomAccessIterator& __i, _Distance __n,
 131                       random_access_iterator_tag)
 132 {
 133   // concept requirements
 134   __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>);
 135   __i += __n;
 136 }
 137
 138 template <class _InputIterator, class _Distance>
 139 inline void advance(_InputIterator& __i, _Distance __n)
 140 {
 141   // concept requirements -- taken care of in __advance
 142   __advance(__i, __n, iterator_category(__i));
 143 }
 144
 145 } // namespace std
 146
 147 #endif /* __SGI_STL_INTERNAL_ITERATOR_BASE_FUNCS_H */
 148
 149
 150 // Local Variables:
 151 // mode:C++
 152 // End: