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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
96 350 : __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
97 : random_access_iterator_tag)
98 : {
99 : // concept requirements
100 : __glibcxx_function_requires(_RandomAccessIteratorConcept<
101 : _RandomAccessIterator>)
102 350 : 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
135 350 : distance(_InputIterator __first, _InputIterator __last)
136 : {
137 : // concept requirements -- taken care of in __distance
138 350 : return std::__distance(__first, __last,
139 700 : 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 */
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