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1 : // Functions used by iterators -*- C++ -*-
2 :
3 : // Copyright (C) 2001-2013 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 1291553 : __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
91 : random_access_iterator_tag)
92 : {
93 : // concept requirements
94 : __glibcxx_function_requires(_RandomAccessIteratorConcept<
95 : _RandomAccessIterator>)
96 1321484 : 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 1291527 : distance(_InputIterator __first, _InputIterator __last)
115 : {
116 : // concept requirements -- taken care of in __distance
117 : return std::__distance(__first, __last,
118 1331160 : 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 59585 : __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 59585 : typename iterator_traits<_InputIterator>::difference_type __d = __n;
177 59585 : 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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