1 | // Functions used by iterators -*- C++ -*- |
2 | |
3 | // Copyright (C) 2001-2016 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/assertions.h> |
66 | |
67 | namespace std _GLIBCXX_VISIBILITY(default) |
68 | { |
69 | _GLIBCXX_BEGIN_NAMESPACE_CONTAINER |
70 | // Forward declaration for the overloads of __distance. |
71 | template <typename> struct _List_iterator; |
72 | template <typename> struct _List_const_iterator; |
73 | _GLIBCXX_END_NAMESPACE_CONTAINER |
74 | |
75 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
76 | |
77 | template<typename _InputIterator> |
78 | inline typename iterator_traits<_InputIterator>::difference_type |
79 | __distance(_InputIterator __first, _InputIterator __last, |
80 | input_iterator_tag) |
81 | { |
82 | // concept requirements |
83 | __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) |
84 | |
85 | typename iterator_traits<_InputIterator>::difference_type __n = 0; |
86 | while (__first != __last) |
87 | { |
88 | ++__first; |
89 | ++__n; |
90 | } |
91 | return __n; |
92 | } |
93 | |
94 | template<typename _RandomAccessIterator> |
95 | inline typename iterator_traits<_RandomAccessIterator>::difference_type |
96 | __distance(_RandomAccessIterator __first, _RandomAccessIterator __last, |
97 | random_access_iterator_tag) |
98 | { |
99 | // concept requirements |
100 | __glibcxx_function_requires(_RandomAccessIteratorConcept< |
101 | _RandomAccessIterator>) |
102 | return __last - __first; |
103 | } |
104 | |
105 | #if _GLIBCXX_USE_CXX11_ABI |
106 | // Forward declaration because of the qualified call in distance. |
107 | template<typename _Tp> |
108 | ptrdiff_t |
109 | __distance(_GLIBCXX_STD_C::_List_iterator<_Tp>, |
110 | _GLIBCXX_STD_C::_List_iterator<_Tp>, |
111 | input_iterator_tag); |
112 | |
113 | template<typename _Tp> |
114 | ptrdiff_t |
115 | __distance(_GLIBCXX_STD_C::_List_const_iterator<_Tp>, |
116 | _GLIBCXX_STD_C::_List_const_iterator<_Tp>, |
117 | input_iterator_tag); |
118 | #endif |
119 | |
120 | /** |
121 | * @brief A generalization of pointer arithmetic. |
122 | * @param __first An input iterator. |
123 | * @param __last An input iterator. |
124 | * @return The distance between them. |
125 | * |
126 | * Returns @c n such that __first + n == __last. This requires |
127 | * that @p __last must be reachable from @p __first. Note that @c |
128 | * n may be negative. |
129 | * |
130 | * For random access iterators, this uses their @c + and @c - operations |
131 | * and are constant time. For other %iterator classes they are linear time. |
132 | */ |
133 | template<typename _InputIterator> |
134 | inline typename iterator_traits<_InputIterator>::difference_type |
135 | distance(_InputIterator __first, _InputIterator __last) |
136 | { |
137 | // concept requirements -- taken care of in __distance |
138 | return std::__distance(__first, __last, |
139 | std::__iterator_category(__first)); |
140 | } |
141 | |
142 | template<typename _InputIterator, typename _Distance> |
143 | inline void |
144 | __advance(_InputIterator& __i, _Distance __n, input_iterator_tag) |
145 | { |
146 | // concept requirements |
147 | __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) |
148 | __glibcxx_assert(__n >= 0); |
149 | while (__n--) |
150 | ++__i; |
151 | } |
152 | |
153 | template<typename _BidirectionalIterator, typename _Distance> |
154 | inline void |
155 | __advance(_BidirectionalIterator& __i, _Distance __n, |
156 | bidirectional_iterator_tag) |
157 | { |
158 | // concept requirements |
159 | __glibcxx_function_requires(_BidirectionalIteratorConcept< |
160 | _BidirectionalIterator>) |
161 | if (__n > 0) |
162 | while (__n--) |
163 | ++__i; |
164 | else |
165 | while (__n++) |
166 | --__i; |
167 | } |
168 | |
169 | template<typename _RandomAccessIterator, typename _Distance> |
170 | inline void |
171 | __advance(_RandomAccessIterator& __i, _Distance __n, |
172 | random_access_iterator_tag) |
173 | { |
174 | // concept requirements |
175 | __glibcxx_function_requires(_RandomAccessIteratorConcept< |
176 | _RandomAccessIterator>) |
177 | __i += __n; |
178 | } |
179 | |
180 | /** |
181 | * @brief A generalization of pointer arithmetic. |
182 | * @param __i An input iterator. |
183 | * @param __n The @a delta by which to change @p __i. |
184 | * @return Nothing. |
185 | * |
186 | * This increments @p i by @p n. For bidirectional and random access |
187 | * iterators, @p __n may be negative, in which case @p __i is decremented. |
188 | * |
189 | * For random access iterators, this uses their @c + and @c - operations |
190 | * and are constant time. For other %iterator classes they are linear time. |
191 | */ |
192 | template<typename _InputIterator, typename _Distance> |
193 | inline void |
194 | advance(_InputIterator& __i, _Distance __n) |
195 | { |
196 | // concept requirements -- taken care of in __advance |
197 | typename iterator_traits<_InputIterator>::difference_type __d = __n; |
198 | std::__advance(__i, __d, std::__iterator_category(__i)); |
199 | } |
200 | |
201 | #if __cplusplus >= 201103L |
202 | |
203 | template<typename _ForwardIterator> |
204 | inline _ForwardIterator |
205 | next(_ForwardIterator __x, typename |
206 | iterator_traits<_ForwardIterator>::difference_type __n = 1) |
207 | { |
208 | // concept requirements |
209 | __glibcxx_function_requires(_ForwardIteratorConcept< |
210 | _ForwardIterator>) |
211 | std::advance(__x, __n); |
212 | return __x; |
213 | } |
214 | |
215 | template<typename _BidirectionalIterator> |
216 | inline _BidirectionalIterator |
217 | prev(_BidirectionalIterator __x, typename |
218 | iterator_traits<_BidirectionalIterator>::difference_type __n = 1) |
219 | { |
220 | // concept requirements |
221 | __glibcxx_function_requires(_BidirectionalIteratorConcept< |
222 | _BidirectionalIterator>) |
223 | std::advance(__x, -__n); |
224 | return __x; |
225 | } |
226 | |
227 | #endif // C++11 |
228 | |
229 | _GLIBCXX_END_NAMESPACE_VERSION |
230 | } // namespace |
231 | |
232 | #endif /* _STL_ITERATOR_BASE_FUNCS_H */ |
233 | |