1 | // Functions used by iterators -*- C++ -*- |
2 | |
3 | // Copyright (C) 2001-2014 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 bits/stl_iterator_base_funcs.h |
52 | * This is an internal header file, included by other library headers. |
53 | * Do not attempt to use it directly. @headername{iterator} |
54 | * |
55 | * This file contains all of the general iterator-related utility |
56 | * functions, such as distance() and advance(). |
57 | */ |
58 | |
59 | #ifndef _STL_ITERATOR_BASE_FUNCS_H |
60 | #define _STL_ITERATOR_BASE_FUNCS_H 1 |
61 | |
62 | #pragma GCC system_header |
63 | |
64 | #include <bits/concept_check.h> |
65 | #include <debug/debug.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 | _GLIBCXX_DEBUG_ASSERT(__n >= 0); |
128 | while (__n--) |
129 | ++__i; |
130 | } |
131 | |
132 | template<typename _BidirectionalIterator, typename _Distance> |
133 | inline void |
134 | __advance(_BidirectionalIterator& __i, _Distance __n, |
135 | bidirectional_iterator_tag) |
136 | { |
137 | // concept requirements |
138 | __glibcxx_function_requires(_BidirectionalIteratorConcept< |
139 | _BidirectionalIterator>) |
140 | if (__n > 0) |
141 | while (__n--) |
142 | ++__i; |
143 | else |
144 | while (__n++) |
145 | --__i; |
146 | } |
147 | |
148 | template<typename _RandomAccessIterator, typename _Distance> |
149 | inline void |
150 | __advance(_RandomAccessIterator& __i, _Distance __n, |
151 | random_access_iterator_tag) |
152 | { |
153 | // concept requirements |
154 | __glibcxx_function_requires(_RandomAccessIteratorConcept< |
155 | _RandomAccessIterator>) |
156 | __i += __n; |
157 | } |
158 | |
159 | /** |
160 | * @brief A generalization of pointer arithmetic. |
161 | * @param __i An input iterator. |
162 | * @param __n The @a delta by which to change @p __i. |
163 | * @return Nothing. |
164 | * |
165 | * This increments @p i by @p n. For bidirectional and random access |
166 | * iterators, @p __n may be negative, in which case @p __i is decremented. |
167 | * |
168 | * For random access iterators, this uses their @c + and @c - operations |
169 | * and are constant time. For other %iterator classes they are linear time. |
170 | */ |
171 | template<typename _InputIterator, typename _Distance> |
172 | inline void |
173 | advance(_InputIterator& __i, _Distance __n) |
174 | { |
175 | // concept requirements -- taken care of in __advance |
176 | typename iterator_traits<_InputIterator>::difference_type __d = __n; |
177 | std::__advance(__i, __d, std::__iterator_category(__i)); |
178 | } |
179 | |
180 | #if __cplusplus >= 201103L |
181 | |
182 | template<typename _ForwardIterator> |
183 | inline _ForwardIterator |
184 | next(_ForwardIterator __x, typename |
185 | iterator_traits<_ForwardIterator>::difference_type __n = 1) |
186 | { |
187 | std::advance(__x, __n); |
188 | return __x; |
189 | } |
190 | |
191 | template<typename _BidirectionalIterator> |
192 | inline _BidirectionalIterator |
193 | prev(_BidirectionalIterator __x, typename |
194 | iterator_traits<_BidirectionalIterator>::difference_type __n = 1) |
195 | { |
196 | std::advance(__x, -__n); |
197 | return __x; |
198 | } |
199 | |
200 | #endif // C++11 |
201 | |
202 | _GLIBCXX_END_NAMESPACE_VERSION |
203 | } // namespace |
204 | |
205 | #endif /* _STL_ITERATOR_BASE_FUNCS_H */ |
206 | |