1 : // Functions used by iterators -*- C++ -*-
2 :
3 : // Copyright (C) 2001, 2002, 2003, 2004 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 2, 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 : // You should have received a copy of the GNU General Public License along
17 : // with this library; see the file COPYING. If not, write to the Free
18 : // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
19 : // USA.
20 :
21 : // As a special exception, you may use this file as part of a free software
22 : // library without restriction. Specifically, if other files instantiate
23 : // templates or use macros or inline functions from this file, or you compile
24 : // this file and link it with other files to produce an executable, this
25 : // file does not by itself cause the resulting executable to be covered by
26 : // the GNU General Public License. This exception does not however
27 : // invalidate any other reasons why the executable file might be covered by
28 : // the GNU General Public License.
29 :
30 : /*
31 : *
32 : * Copyright (c) 1994
33 : * Hewlett-Packard Company
34 : *
35 : * Permission to use, copy, modify, distribute and sell this software
36 : * and its documentation for any purpose is hereby granted without fee,
37 : * provided that the above copyright notice appear in all copies and
38 : * that both that copyright notice and this permission notice appear
39 : * in supporting documentation. Hewlett-Packard Company makes no
40 : * representations about the suitability of this software for any
41 : * purpose. It is provided "as is" without express or implied warranty.
42 : *
43 : *
44 : * Copyright (c) 1996-1998
45 : * Silicon Graphics Computer Systems, Inc.
46 : *
47 : * Permission to use, copy, modify, distribute and sell this software
48 : * and its documentation for any purpose is hereby granted without fee,
49 : * provided that the above copyright notice appear in all copies and
50 : * that both that copyright notice and this permission notice appear
51 : * in supporting documentation. Silicon Graphics makes no
52 : * representations about the suitability of this software for any
53 : * purpose. It is provided "as is" without express or implied warranty.
54 : */
55 :
56 : /** @file stl_iterator_base_funcs.h
57 : * This is an internal header file, included by other library headers.
58 : * You should not attempt to use it directly.
59 : *
60 : * This file contains all of the general iterator-related utility
61 : * functions, such as distance() and advance().
62 : */
63 :
64 : #ifndef _ITERATOR_BASE_FUNCS_H
65 : #define _ITERATOR_BASE_FUNCS_H 1
66 :
67 : #pragma GCC system_header
68 : #include <bits/concept_check.h>
69 :
70 : namespace std
71 : {
72 : template<typename _InputIterator>
73 : inline typename iterator_traits<_InputIterator>::difference_type
74 : __distance(_InputIterator __first, _InputIterator __last,
75 23 : input_iterator_tag)
76 : {
77 : // concept requirements
78 : __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
79 :
80 23 : typename iterator_traits<_InputIterator>::difference_type __n = 0;
81 69 : while (__first != __last)
82 : {
83 23 : ++__first;
84 23 : ++__n;
85 : }
86 23 : return __n;
87 : }
88 :
89 : template<typename _RandomAccessIterator>
90 : inline typename iterator_traits<_RandomAccessIterator>::difference_type
91 : __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
92 75783 : random_access_iterator_tag)
93 : {
94 : // concept requirements
95 : __glibcxx_function_requires(_RandomAccessIteratorConcept<
96 : _RandomAccessIterator>)
97 75783 : return __last - __first;
98 : }
99 :
100 : /**
101 : * @brief A generalization of pointer arithmetic.
102 : * @param first An input iterator.
103 : * @param last An input iterator.
104 : * @return The distance between them.
105 : *
106 : * Returns @c n such that first + n == last. This requires that @p last
107 : * must be reachable from @p first. Note that @c 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 75806 : distance(_InputIterator __first, _InputIterator __last)
115 : {
116 : // concept requirements -- taken care of in __distance
117 : return std::__distance(__first, __last,
118 75806 : 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 : while (__n--)
128 : ++__i;
129 : }
130 :
131 : template<typename _BidirectionalIterator, typename _Distance>
132 : inline void
133 : __advance(_BidirectionalIterator& __i, _Distance __n,
134 : bidirectional_iterator_tag)
135 : {
136 : // concept requirements
137 : __glibcxx_function_requires(_BidirectionalIteratorConcept<
138 : _BidirectionalIterator>)
139 : if (__n > 0)
140 : while (__n--)
141 : ++__i;
142 : else
143 : while (__n++)
144 : --__i;
145 : }
146 :
147 : template<typename _RandomAccessIterator, typename _Distance>
148 : inline void
149 : __advance(_RandomAccessIterator& __i, _Distance __n,
150 51956 : random_access_iterator_tag)
151 : {
152 : // concept requirements
153 : __glibcxx_function_requires(_RandomAccessIteratorConcept<
154 : _RandomAccessIterator>)
155 51956 : __i += __n;
156 : }
157 :
158 : /**
159 : * @brief A generalization of pointer arithmetic.
160 : * @param i An input iterator.
161 : * @param n The "delta" by which to change @p i.
162 : * @return Nothing.
163 : *
164 : * This increments @p i by @p n. For bidirectional and random access
165 : * iterators, @p n may be negative, in which case @p i is decremented.
166 : *
167 : * For random access iterators, this uses their @c + and @c - operations
168 : * and are constant time. For other %iterator classes they are linear time.
169 : */
170 : template<typename _InputIterator, typename _Distance>
171 : inline void
172 51956 : advance(_InputIterator& __i, _Distance __n)
173 : {
174 : // concept requirements -- taken care of in __advance
175 51956 : std::__advance(__i, __n, std::__iterator_category(__i));
176 : }
177 : } // namespace std
178 :
179 : #endif /* _ITERATOR_BASE_FUNCS_H */
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