1 : // Functions used by iterators -*- C++ -*-
2 :
3 : // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 : // Free Software Foundation, Inc.
5 : //
6 : // This file is part of the GNU ISO C++ Library. This library is free
7 : // software; you can redistribute it and/or modify it under the
8 : // terms of the GNU General Public License as published by the
9 : // Free Software Foundation; either version 2, or (at your option)
10 : // any later version.
11 :
12 : // This library is distributed in the hope that it will be useful,
13 : // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 : // GNU General Public License for more details.
16 :
17 : // You should have received a copy of the GNU General Public License along
18 : // with this library; see the file COPYING. If not, write to the Free
19 : // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
20 : // USA.
21 :
22 : // As a special exception, you may use this file as part of a free software
23 : // library without restriction. Specifically, if other files instantiate
24 : // templates or use macros or inline functions from this file, or you compile
25 : // this file and link it with other files to produce an executable, this
26 : // file does not by itself cause the resulting executable to be covered by
27 : // the GNU General Public License. This exception does not however
28 : // invalidate any other reasons why the executable file might be covered by
29 : // the GNU General Public License.
30 :
31 : /*
32 : *
33 : * Copyright (c) 1994
34 : * Hewlett-Packard Company
35 : *
36 : * Permission to use, copy, modify, distribute and sell this software
37 : * and its documentation for any purpose is hereby granted without fee,
38 : * provided that the above copyright notice appear in all copies and
39 : * that both that copyright notice and this permission notice appear
40 : * in supporting documentation. Hewlett-Packard Company makes no
41 : * representations about the suitability of this software for any
42 : * purpose. It is provided "as is" without express or implied warranty.
43 : *
44 : *
45 : * Copyright (c) 1996-1998
46 : * Silicon Graphics Computer Systems, Inc.
47 : *
48 : * Permission to use, copy, modify, distribute and sell this software
49 : * and its documentation for any purpose is hereby granted without fee,
50 : * provided that the above copyright notice appear in all copies and
51 : * that both that copyright notice and this permission notice appear
52 : * in supporting documentation. Silicon Graphics makes no
53 : * representations about the suitability of this software for any
54 : * purpose. It is provided "as is" without express or implied warranty.
55 : */
56 :
57 : /** @file stl_iterator_base_funcs.h
58 : * This is an internal header file, included by other library headers.
59 : * You should not attempt to use it directly.
60 : *
61 : * This file contains all of the general iterator-related utility
62 : * functions, such as distance() and advance().
63 : */
64 :
65 : #ifndef _STL_ITERATOR_BASE_FUNCS_H
66 : #define _STL_ITERATOR_BASE_FUNCS_H 1
67 :
68 : #pragma GCC system_header
69 : #include <bits/concept_check.h>
70 :
71 : _GLIBCXX_BEGIN_NAMESPACE(std)
72 :
73 : template<typename _InputIterator>
74 : inline typename iterator_traits<_InputIterator>::difference_type
75 : __distance(_InputIterator __first, _InputIterator __last,
76 13 : input_iterator_tag)
77 : {
78 : // concept requirements
79 : __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
80 :
81 13 : typename iterator_traits<_InputIterator>::difference_type __n = 0;
82 37 : while (__first != __last)
83 : {
84 11 : ++__first;
85 11 : ++__n;
86 : }
87 13 : return __n;
88 : }
89 :
90 : template<typename _RandomAccessIterator>
91 : inline typename iterator_traits<_RandomAccessIterator>::difference_type
92 : __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
93 1287 : random_access_iterator_tag)
94 : {
95 : // concept requirements
96 : __glibcxx_function_requires(_RandomAccessIteratorConcept<
97 : _RandomAccessIterator>)
98 1287 : return __last - __first;
99 : }
100 :
101 : /**
102 : * @brief A generalization of pointer arithmetic.
103 : * @param first An input iterator.
104 : * @param last An input iterator.
105 : * @return The distance between them.
106 : *
107 : * Returns @c n such that first + n == last. This requires that @p last
108 : * must be reachable from @p first. Note that @c n may be negative.
109 : *
110 : * For random access iterators, this uses their @c + and @c - operations
111 : * and are constant time. For other %iterator classes they are linear time.
112 : */
113 : template<typename _InputIterator>
114 : inline typename iterator_traits<_InputIterator>::difference_type
115 1300 : distance(_InputIterator __first, _InputIterator __last)
116 : {
117 : // concept requirements -- taken care of in __distance
118 : return std::__distance(__first, __last,
119 1300 : std::__iterator_category(__first));
120 : }
121 :
122 : template<typename _InputIterator, typename _Distance>
123 : inline void
124 10 : __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
125 : {
126 : // concept requirements
127 : __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
128 41 : while (__n--)
129 21 : ++__i;
130 10 : }
131 :
132 : template<typename _BidirectionalIterator, typename _Distance>
133 : inline void
134 : __advance(_BidirectionalIterator& __i, _Distance __n,
135 55 : bidirectional_iterator_tag)
136 : {
137 : // concept requirements
138 : __glibcxx_function_requires(_BidirectionalIteratorConcept<
139 : _BidirectionalIterator>)
140 55 : if (__n > 0)
141 165 : while (__n--)
142 55 : ++__i;
143 : else
144 0 : while (__n++)
145 0 : --__i;
146 55 : }
147 :
148 : template<typename _RandomAccessIterator, typename _Distance>
149 : inline void
150 : __advance(_RandomAccessIterator& __i, _Distance __n,
151 0 : random_access_iterator_tag)
152 : {
153 : // concept requirements
154 : __glibcxx_function_requires(_RandomAccessIteratorConcept<
155 : _RandomAccessIterator>)
156 0 : __i += __n;
157 0 : }
158 :
159 : /**
160 : * @brief A generalization of pointer arithmetic.
161 : * @param i An input iterator.
162 : * @param n The "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 65 : advance(_InputIterator& __i, _Distance __n)
174 : {
175 : // concept requirements -- taken care of in __advance
176 65 : typename iterator_traits<_InputIterator>::difference_type __d = __n;
177 65 : std::__advance(__i, __d, std::__iterator_category(__i));
178 65 : }
179 :
180 : _GLIBCXX_END_NAMESPACE
181 :
182 : #endif /* _STL_ITERATOR_BASE_FUNCS_H */
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