libstdc++

stl_iterator_base_types.h
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1 // Types used in iterator implementation -*- 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_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 _GLIBCXX_HAS_NESTED_TYPE, 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
142 _GLIBCXX_HAS_NESTED_TYPE(iterator_category)
143
144 template<typename _Iterator,
145 bool = __has_iterator_category<_Iterator>::value>
146 struct __iterator_traits { };
147
148 template<typename _Iterator>
149 struct __iterator_traits<_Iterator, true>
150 {
151 typedef typename _Iterator::iterator_category iterator_category;
152 typedef typename _Iterator::value_type value_type;
153 typedef typename _Iterator::difference_type difference_type;
154 typedef typename _Iterator::pointer pointer;
155 typedef typename _Iterator::reference reference;
156 };
157
158 template<typename _Iterator>
159 struct iterator_traits
160 : public __iterator_traits<_Iterator> { };
161 #else
162 template<typename _Iterator>
163 struct iterator_traits
164 {
165 typedef typename _Iterator::iterator_category iterator_category;
166 typedef typename _Iterator::value_type value_type;
167 typedef typename _Iterator::difference_type difference_type;
168 typedef typename _Iterator::pointer pointer;
169 typedef typename _Iterator::reference reference;
170 };
171 #endif
172
173 /// Partial specialization for pointer types.
174 template<typename _Tp>
175 struct iterator_traits<_Tp*>
176 {
177 typedef random_access_iterator_tag iterator_category;
178 typedef _Tp value_type;
179 typedef ptrdiff_t difference_type;
180 typedef _Tp* pointer;
181 typedef _Tp& reference;
182 };
183
184 /// Partial specialization for const pointer types.
185 template<typename _Tp>
186 struct iterator_traits<const _Tp*>
187 {
188 typedef random_access_iterator_tag iterator_category;
189 typedef _Tp value_type;
190 typedef ptrdiff_t difference_type;
191 typedef const _Tp* pointer;
192 typedef const _Tp& reference;
193 };
194
195 /**
196 * This function is not a part of the C++ standard but is syntactic
197 * sugar for internal library use only.
198 */
199 template<typename _Iter>
200 inline typename iterator_traits<_Iter>::iterator_category
201 __iterator_category(const _Iter&)
202 { return typename iterator_traits<_Iter>::iterator_category(); }
203
204 //@}
205
206 // If _Iterator has a base returns it otherwise _Iterator is returned
207 // untouched
208 template<typename _Iterator, bool _HasBase>
209 struct _Iter_base
210 {
211 typedef _Iterator iterator_type;
212 static iterator_type _S_base(_Iterator __it)
213 { return __it; }
214 };
215
216 template<typename _Iterator>
217 struct _Iter_base<_Iterator, true>
218 {
219 typedef typename _Iterator::iterator_type iterator_type;
220 static iterator_type _S_base(_Iterator __it)
221 { return __it.base(); }
222 };
223
224 #if __cplusplus >= 201103L
225 template<typename _InIter>
226 using _RequireInputIter = typename
227 enable_if<is_convertible<typename
228 iterator_traits<_InIter>::iterator_category,
229 input_iterator_tag>::value>::type;
230 #endif
231
232 _GLIBCXX_END_NAMESPACE_VERSION
233 } // namespace
234
235 #endif /* _STL_ITERATOR_BASE_TYPES_H */
236