libstdc++
stl_iterator_base_funcs.h
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1 // Functions used by iterators -*- C++ -*-
2 
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
4 // Free Software Foundation, Inc.
5 //
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 3, or (at your option)
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11 
12 // This library is distributed in the hope that it will be useful,
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14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
16 
17 // Under Section 7 of GPL version 3, you are granted additional
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19 // 3.1, as published by the Free Software Foundation.
20 
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25 
26 /*
27  *
28  * Copyright (c) 1994
29  * Hewlett-Packard Company
30  *
31  * Permission to use, copy, modify, distribute and sell this software
32  * and its documentation for any purpose is hereby granted without fee,
33  * provided that the above copyright notice appear in all copies and
34  * that both that copyright notice and this permission notice appear
35  * in supporting documentation. Hewlett-Packard Company makes no
36  * representations about the suitability of this software for any
37  * purpose. It is provided "as is" without express or implied warranty.
38  *
39  *
40  * Copyright (c) 1996-1998
41  * Silicon Graphics Computer Systems, Inc.
42  *
43  * Permission to use, copy, modify, distribute and sell this software
44  * and its documentation for any purpose is hereby granted without fee,
45  * provided that the above copyright notice appear in all copies and
46  * that both that copyright notice and this permission notice appear
47  * in supporting documentation. Silicon Graphics makes no
48  * representations about the suitability of this software for any
49  * purpose. It is provided "as is" without express or implied warranty.
50  */
51 
52 /** @file bits/stl_iterator_base_funcs.h
53  * This is an internal header file, included by other library headers.
54  * Do not attempt to use it directly. @headername{iterator}
55  *
56  * This file contains all of the general iterator-related utility
57  * functions, such as distance() and advance().
58  */
59 
60 #ifndef _STL_ITERATOR_BASE_FUNCS_H
61 #define _STL_ITERATOR_BASE_FUNCS_H 1
62 
63 #pragma GCC system_header
64 
65 #include <bits/concept_check.h>
66 
67 namespace std _GLIBCXX_VISIBILITY(default)
68 {
69 _GLIBCXX_BEGIN_NAMESPACE_VERSION
70 
71  template<typename _InputIterator>
72  inline typename iterator_traits<_InputIterator>::difference_type
73  __distance(_InputIterator __first, _InputIterator __last,
74  input_iterator_tag)
75  {
76  // concept requirements
77  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
78 
79  typename iterator_traits<_InputIterator>::difference_type __n = 0;
80  while (__first != __last)
81  {
82  ++__first;
83  ++__n;
84  }
85  return __n;
86  }
87 
88  template<typename _RandomAccessIterator>
89  inline typename iterator_traits<_RandomAccessIterator>::difference_type
90  __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
91  random_access_iterator_tag)
92  {
93  // concept requirements
94  __glibcxx_function_requires(_RandomAccessIteratorConcept<
95  _RandomAccessIterator>)
96  return __last - __first;
97  }
98 
99  /**
100  * @brief A generalization of pointer arithmetic.
101  * @param __first An input iterator.
102  * @param __last An input iterator.
103  * @return The distance between them.
104  *
105  * Returns @c n such that __first + n == __last. This requires
106  * that @p __last must be reachable from @p __first. Note that @c
107  * n may be negative.
108  *
109  * For random access iterators, this uses their @c + and @c - operations
110  * and are constant time. For other %iterator classes they are linear time.
111  */
112  template<typename _InputIterator>
113  inline typename iterator_traits<_InputIterator>::difference_type
114  distance(_InputIterator __first, _InputIterator __last)
115  {
116  // concept requirements -- taken care of in __distance
117  return std::__distance(__first, __last,
118  std::__iterator_category(__first));
119  }
120 
121  template<typename _InputIterator, typename _Distance>
122  inline void
123  __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
124  {
125  // concept requirements
126  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
127  while (__n--)
128  ++__i;
129  }
130 
131  template<typename _BidirectionalIterator, typename _Distance>
132  inline void
133  __advance(_BidirectionalIterator& __i, _Distance __n,
134  bidirectional_iterator_tag)
135  {
136  // concept requirements
137  __glibcxx_function_requires(_BidirectionalIteratorConcept<
138  _BidirectionalIterator>)
139  if (__n > 0)
140  while (__n--)
141  ++__i;
142  else
143  while (__n++)
144  --__i;
145  }
146 
147  template<typename _RandomAccessIterator, typename _Distance>
148  inline void
149  __advance(_RandomAccessIterator& __i, _Distance __n,
150  random_access_iterator_tag)
151  {
152  // concept requirements
153  __glibcxx_function_requires(_RandomAccessIteratorConcept<
154  _RandomAccessIterator>)
155  __i += __n;
156  }
157 
158  /**
159  * @brief A generalization of pointer arithmetic.
160  * @param __i An input iterator.
161  * @param __n The @a delta by which to change @p __i.
162  * @return Nothing.
163  *
164  * This increments @p i by @p n. For bidirectional and random access
165  * iterators, @p __n may be negative, in which case @p __i is decremented.
166  *
167  * For random access iterators, this uses their @c + and @c - operations
168  * and are constant time. For other %iterator classes they are linear time.
169  */
170  template<typename _InputIterator, typename _Distance>
171  inline void
172  advance(_InputIterator& __i, _Distance __n)
173  {
174  // concept requirements -- taken care of in __advance
175  typename iterator_traits<_InputIterator>::difference_type __d = __n;
176  std::__advance(__i, __d, std::__iterator_category(__i));
177  }
178 
179 #ifdef __GXX_EXPERIMENTAL_CXX0X__
180 
181  template<typename _ForwardIterator>
182  inline _ForwardIterator
183  next(_ForwardIterator __x, typename
184  iterator_traits<_ForwardIterator>::difference_type __n = 1)
185  {
186  std::advance(__x, __n);
187  return __x;
188  }
189 
190  template<typename _BidirectionalIterator>
191  inline _BidirectionalIterator
192  prev(_BidirectionalIterator __x, typename
193  iterator_traits<_BidirectionalIterator>::difference_type __n = 1)
194  {
195  std::advance(__x, -__n);
196  return __x;
197  }
198 
199 #endif // __GXX_EXPERIMENTAL_CXX0X__
200 
201 _GLIBCXX_END_NAMESPACE_VERSION
202 } // namespace
203 
204 #endif /* _STL_ITERATOR_BASE_FUNCS_H */