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1 : : // Functions used by iterators -*- C++ -*-
2 : :
3 : : // Copyright (C) 2001-2015 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 : 14 : 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 */
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