1 | // Types used in iterator implementation -*- C++ -*- |
2 | |
3 | // Copyright (C) 2001-2019 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_types.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 types, |
56 | * such as iterator_traits and struct iterator. |
57 | */ |
58 | |
59 | #ifndef _STL_ITERATOR_BASE_TYPES_H |
60 | #define _STL_ITERATOR_BASE_TYPES_H 1 |
61 | |
62 | #pragma GCC system_header |
63 | |
64 | #include <bits/c++config.h> |
65 | |
66 | #if __cplusplus >= 201103L |
67 | # include <type_traits> // For __void_t, is_convertible |
68 | #endif |
69 | |
70 | namespace std _GLIBCXX_VISIBILITY(default) |
71 | { |
72 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
73 | |
74 | /** |
75 | * @defgroup iterators Iterators |
76 | * Abstractions for uniform iterating through various underlying types. |
77 | */ |
78 | ///@{ |
79 | |
80 | /** |
81 | * @defgroup iterator_tags Iterator Tags |
82 | * These are empty types, used to distinguish different iterators. The |
83 | * distinction is not made by what they contain, but simply by what they |
84 | * are. Different underlying algorithms can then be used based on the |
85 | * different operations supported by different iterator types. |
86 | */ |
87 | ///@{ |
88 | /// Marking input iterators. |
89 | struct input_iterator_tag { }; |
90 | |
91 | /// Marking output iterators. |
92 | struct output_iterator_tag { }; |
93 | |
94 | /// Forward iterators support a superset of input iterator operations. |
95 | struct forward_iterator_tag : public input_iterator_tag { }; |
96 | |
97 | /// Bidirectional iterators support a superset of forward iterator |
98 | /// operations. |
99 | struct bidirectional_iterator_tag : public forward_iterator_tag { }; |
100 | |
101 | /// Random-access iterators support a superset of bidirectional |
102 | /// iterator operations. |
103 | struct random_access_iterator_tag : public bidirectional_iterator_tag { }; |
104 | ///@} |
105 | |
106 | /** |
107 | * @brief Common %iterator class. |
108 | * |
109 | * This class does nothing but define nested typedefs. %Iterator classes |
110 | * can inherit from this class to save some work. The typedefs are then |
111 | * used in specializations and overloading. |
112 | * |
113 | * In particular, there are no default implementations of requirements |
114 | * such as @c operator++ and the like. (How could there be?) |
115 | */ |
116 | template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t, |
117 | typename _Pointer = _Tp*, typename _Reference = _Tp&> |
118 | struct iterator |
119 | { |
120 | /// One of the @link iterator_tags tag types@endlink. |
121 | typedef _Category iterator_category; |
122 | /// The type "pointed to" by the iterator. |
123 | typedef _Tp value_type; |
124 | /// Distance between iterators is represented as this type. |
125 | typedef _Distance difference_type; |
126 | /// This type represents a pointer-to-value_type. |
127 | typedef _Pointer pointer; |
128 | /// This type represents a reference-to-value_type. |
129 | typedef _Reference reference; |
130 | }; |
131 | |
132 | /** |
133 | * @brief Traits class for iterators. |
134 | * |
135 | * This class does nothing but define nested typedefs. The general |
136 | * version simply @a forwards the nested typedefs from the Iterator |
137 | * argument. Specialized versions for pointers and pointers-to-const |
138 | * provide tighter, more correct semantics. |
139 | */ |
140 | #if __cplusplus >= 201103L |
141 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
142 | // 2408. SFINAE-friendly common_type/iterator_traits is missing in C++14 |
143 | template<typename _Iterator, typename = __void_t<>> |
144 | struct __iterator_traits { }; |
145 | |
146 | template<typename _Iterator> |
147 | struct __iterator_traits<_Iterator, |
148 | __void_t<typename _Iterator::iterator_category, |
149 | typename _Iterator::value_type, |
150 | typename _Iterator::difference_type, |
151 | typename _Iterator::pointer, |
152 | typename _Iterator::reference>> |
153 | { |
154 | typedef typename _Iterator::iterator_category iterator_category; |
155 | typedef typename _Iterator::value_type value_type; |
156 | typedef typename _Iterator::difference_type difference_type; |
157 | typedef typename _Iterator::pointer pointer; |
158 | typedef typename _Iterator::reference reference; |
159 | }; |
160 | |
161 | template<typename _Iterator> |
162 | struct iterator_traits |
163 | : public __iterator_traits<_Iterator> { }; |
164 | #else |
165 | template<typename _Iterator> |
166 | struct iterator_traits |
167 | { |
168 | typedef typename _Iterator::iterator_category iterator_category; |
169 | typedef typename _Iterator::value_type value_type; |
170 | typedef typename _Iterator::difference_type difference_type; |
171 | typedef typename _Iterator::pointer pointer; |
172 | typedef typename _Iterator::reference reference; |
173 | }; |
174 | #endif |
175 | |
176 | /// Partial specialization for pointer types. |
177 | template<typename _Tp> |
178 | struct iterator_traits<_Tp*> |
179 | { |
180 | typedef random_access_iterator_tag iterator_category; |
181 | typedef _Tp value_type; |
182 | typedef ptrdiff_t difference_type; |
183 | typedef _Tp* pointer; |
184 | typedef _Tp& reference; |
185 | }; |
186 | |
187 | /// Partial specialization for const pointer types. |
188 | template<typename _Tp> |
189 | struct iterator_traits<const _Tp*> |
190 | { |
191 | typedef random_access_iterator_tag iterator_category; |
192 | typedef _Tp value_type; |
193 | typedef ptrdiff_t difference_type; |
194 | typedef const _Tp* pointer; |
195 | typedef const _Tp& reference; |
196 | }; |
197 | |
198 | /** |
199 | * This function is not a part of the C++ standard but is syntactic |
200 | * sugar for internal library use only. |
201 | */ |
202 | template<typename _Iter> |
203 | inline _GLIBCXX_CONSTEXPR |
204 | typename iterator_traits<_Iter>::iterator_category |
205 | __iterator_category(const _Iter&) |
206 | { return typename iterator_traits<_Iter>::iterator_category(); } |
207 | |
208 | ///@} |
209 | |
210 | #if __cplusplus < 201103L |
211 | // If _Iterator has a base returns it otherwise _Iterator is returned |
212 | // untouched |
213 | template<typename _Iterator, bool _HasBase> |
214 | struct _Iter_base |
215 | { |
216 | typedef _Iterator iterator_type; |
217 | static iterator_type _S_base(_Iterator __it) |
218 | { return __it; } |
219 | }; |
220 | |
221 | template<typename _Iterator> |
222 | struct _Iter_base<_Iterator, true> |
223 | { |
224 | typedef typename _Iterator::iterator_type iterator_type; |
225 | static iterator_type _S_base(_Iterator __it) |
226 | { return __it.base(); } |
227 | }; |
228 | #endif |
229 | |
230 | #if __cplusplus >= 201103L |
231 | template<typename _InIter> |
232 | using _RequireInputIter = typename |
233 | enable_if<is_convertible<typename |
234 | iterator_traits<_InIter>::iterator_category, |
235 | input_iterator_tag>::value>::type; |
236 | #endif |
237 | |
238 | _GLIBCXX_END_NAMESPACE_VERSION |
239 | } // namespace |
240 | |
241 | #endif /* _STL_ITERATOR_BASE_TYPES_H */ |
242 | |
243 | |