1 // Functions used by iterators -*- C++ -*-
2
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
18 // permissions described in the GCC Runtime Library Exception, version
19 // 3.1, as published by the Free Software Foundation.
20
21 // You should have received a copy of the GNU General Public License and
22 // a copy of the GCC Runtime Library Exception along with this program;
23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 // <http://www.gnu.org/licenses/>.
25
26 /*
27 *
28 * Copyright (c) 1994
29 * Hewlett-Packard Company
30 *
31 * Permission to use, copy, modify, distribute and sell this software
32 * and its documentation for any purpose is hereby granted without fee,
33 * provided that the above copyright notice appear in all copies and
34 * that both that copyright notice and this permission notice appear
35 * in supporting documentation. Hewlett-Packard Company makes no
36 * representations about the suitability of this software for any
37 * purpose. It is provided "as is" without express or implied warranty.
38 *
39 *
40 * Copyright (c) 1996-1998
41 * Silicon Graphics Computer Systems, Inc.
42 *
43 * Permission to use, copy, modify, distribute and sell this software
44 * and its documentation for any purpose is hereby granted without fee,
45 * provided that the above copyright notice appear in all copies and
46 * that both that copyright notice and this permission notice appear
47 * in supporting documentation. Silicon Graphics makes no
48 * representations about the suitability of this software for any
49 * purpose. It is provided "as is" without express or implied warranty.
50 */
51
52 /** @file bits/stl_iterator_base_funcs.h
53 * This is an internal header file, included by other library headers.
54 * Do not attempt to use it directly. @headername{iterator}
55 *
56 * This file contains all of the general iterator-related utility
57 * functions, such as distance() and advance().
58 */
59
60 #ifndef _STL_ITERATOR_BASE_FUNCS_H
61 #define _STL_ITERATOR_BASE_FUNCS_H 1
62
63 #pragma GCC system_header
64
65 #include <bits/concept_check.h>
66
_GLIBCXX_VISIBILITY(default)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 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 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 random_access_iterator_tag)
151 {
152 // concept requirements
153 __glibcxx_function_requires(_RandomAccessIteratorConcept<
154 _RandomAccessIterator>)
155 __i += __n;
156 }
157
158 /**
159 * @brief A generalization of pointer arithmetic.
160 * @param __i An input iterator.
161 * @param __n The @a 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 advance(_InputIterator& __i, _Distance __n)
173 {
174 // concept requirements -- taken care of in __advance
175 typename iterator_traits<_InputIterator>::difference_type __d = __n;
176 std::__advance(__i, __d, std::__iterator_category(__i));
177 }
178
179 #ifdef __GXX_EXPERIMENTAL_CXX0X__
180
181 template<typename _ForwardIterator>
182 inline _ForwardIterator
183 next(_ForwardIterator __x, typename
184 iterator_traits<_ForwardIterator>::difference_type __n = 1)
185 {
186 std::advance(__x, __n);
187 return __x;
188 }
189
190 template<typename _BidirectionalIterator>
191 inline _BidirectionalIterator
192 prev(_BidirectionalIterator __x, typename
193 iterator_traits<_BidirectionalIterator>::difference_type __n = 1)
194 {
195 std::advance(__x, -__n);
196 return __x;
197 }
198
199 #endif // __GXX_EXPERIMENTAL_CXX0X__
200
201 _GLIBCXX_END_NAMESPACE_VERSION
202 } // namespace
203
204 #endif /* _STL_ITERATOR_BASE_FUNCS_H */
205