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1 : // Functions used by iterators -*- C++ -*-
2 :
3 : // Copyright (C) 2001-2018 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_VERSION
70 :
71 : _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
72 : // Forward declaration for the overloads of __distance.
73 : template <typename> struct _List_iterator;
74 : template <typename> struct _List_const_iterator;
75 : _GLIBCXX_END_NAMESPACE_CONTAINER
76 :
77 : template<typename _InputIterator>
78 : inline _GLIBCXX14_CONSTEXPR
79 : typename iterator_traits<_InputIterator>::difference_type
80 : __distance(_InputIterator __first, _InputIterator __last,
81 : input_iterator_tag)
82 : {
83 : // concept requirements
84 : __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
85 :
86 : typename iterator_traits<_InputIterator>::difference_type __n = 0;
87 : while (__first != __last)
88 : {
89 : ++__first;
90 : ++__n;
91 : }
92 : return __n;
93 : }
94 :
95 : template<typename _RandomAccessIterator>
96 : inline _GLIBCXX14_CONSTEXPR
97 : typename iterator_traits<_RandomAccessIterator>::difference_type
98 1021658 : __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
99 : random_access_iterator_tag)
100 : {
101 : // concept requirements
102 : __glibcxx_function_requires(_RandomAccessIteratorConcept<
103 : _RandomAccessIterator>)
104 1021658 : return __last - __first;
105 : }
106 :
107 : #if _GLIBCXX_USE_CXX11_ABI
108 : // Forward declaration because of the qualified call in distance.
109 : template<typename _Tp>
110 : ptrdiff_t
111 : __distance(_GLIBCXX_STD_C::_List_iterator<_Tp>,
112 : _GLIBCXX_STD_C::_List_iterator<_Tp>,
113 : input_iterator_tag);
114 :
115 : template<typename _Tp>
116 : ptrdiff_t
117 : __distance(_GLIBCXX_STD_C::_List_const_iterator<_Tp>,
118 : _GLIBCXX_STD_C::_List_const_iterator<_Tp>,
119 : input_iterator_tag);
120 : #endif
121 :
122 : /**
123 : * @brief A generalization of pointer arithmetic.
124 : * @param __first An input iterator.
125 : * @param __last An input iterator.
126 : * @return The distance between them.
127 : *
128 : * Returns @c n such that __first + n == __last. This requires
129 : * that @p __last must be reachable from @p __first. Note that @c
130 : * n may be negative.
131 : *
132 : * For random access iterators, this uses their @c + and @c - operations
133 : * and are constant time. For other %iterator classes they are linear time.
134 : */
135 : template<typename _InputIterator>
136 : inline _GLIBCXX17_CONSTEXPR
137 : typename iterator_traits<_InputIterator>::difference_type
138 1021657 : distance(_InputIterator __first, _InputIterator __last)
139 : {
140 : // concept requirements -- taken care of in __distance
141 1021657 : return std::__distance(__first, __last,
142 2043315 : std::__iterator_category(__first));
143 : }
144 :
145 : template<typename _InputIterator, typename _Distance>
146 : inline _GLIBCXX14_CONSTEXPR void
147 : __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
148 : {
149 : // concept requirements
150 : __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
151 : __glibcxx_assert(__n >= 0);
152 : while (__n--)
153 : ++__i;
154 : }
155 :
156 : template<typename _BidirectionalIterator, typename _Distance>
157 : inline _GLIBCXX14_CONSTEXPR void
158 : __advance(_BidirectionalIterator& __i, _Distance __n,
159 : bidirectional_iterator_tag)
160 : {
161 : // concept requirements
162 : __glibcxx_function_requires(_BidirectionalIteratorConcept<
163 : _BidirectionalIterator>)
164 : if (__n > 0)
165 : while (__n--)
166 : ++__i;
167 : else
168 : while (__n++)
169 : --__i;
170 : }
171 :
172 : template<typename _RandomAccessIterator, typename _Distance>
173 : inline _GLIBCXX14_CONSTEXPR void
174 91 : __advance(_RandomAccessIterator& __i, _Distance __n,
175 : random_access_iterator_tag)
176 : {
177 : // concept requirements
178 : __glibcxx_function_requires(_RandomAccessIteratorConcept<
179 : _RandomAccessIterator>)
180 : if (__builtin_constant_p(__n) && __n == 1)
181 : ++__i;
182 : else if (__builtin_constant_p(__n) && __n == -1)
183 : --__i;
184 : else
185 91 : __i += __n;
186 91 : }
187 :
188 : /**
189 : * @brief A generalization of pointer arithmetic.
190 : * @param __i An input iterator.
191 : * @param __n The @a delta by which to change @p __i.
192 : * @return Nothing.
193 : *
194 : * This increments @p i by @p n. For bidirectional and random access
195 : * iterators, @p __n may be negative, in which case @p __i is decremented.
196 : *
197 : * For random access iterators, this uses their @c + and @c - operations
198 : * and are constant time. For other %iterator classes they are linear time.
199 : */
200 : template<typename _InputIterator, typename _Distance>
201 : inline _GLIBCXX17_CONSTEXPR void
202 91 : advance(_InputIterator& __i, _Distance __n)
203 : {
204 : // concept requirements -- taken care of in __advance
205 91 : typename iterator_traits<_InputIterator>::difference_type __d = __n;
206 91 : std::__advance(__i, __d, std::__iterator_category(__i));
207 91 : }
208 :
209 : #if __cplusplus >= 201103L
210 :
211 : template<typename _InputIterator>
212 : inline _GLIBCXX17_CONSTEXPR _InputIterator
213 : next(_InputIterator __x, typename
214 : iterator_traits<_InputIterator>::difference_type __n = 1)
215 : {
216 : // concept requirements
217 : __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
218 : std::advance(__x, __n);
219 : return __x;
220 : }
221 :
222 : template<typename _BidirectionalIterator>
223 : inline _GLIBCXX17_CONSTEXPR _BidirectionalIterator
224 : prev(_BidirectionalIterator __x, typename
225 : iterator_traits<_BidirectionalIterator>::difference_type __n = 1)
226 : {
227 : // concept requirements
228 : __glibcxx_function_requires(_BidirectionalIteratorConcept<
229 : _BidirectionalIterator>)
230 : std::advance(__x, -__n);
231 : return __x;
232 : }
233 :
234 : #endif // C++11
235 :
236 : _GLIBCXX_END_NAMESPACE_VERSION
237 : } // namespace
238 :
239 : #endif /* _STL_ITERATOR_BASE_FUNCS_H */
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