1// Types used in iterator implementation -*- C++ -*-
2
3// Copyright (C) 2001-2015 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
70namespace 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 typename iterator_traits<_Iter>::iterator_category
204 __iterator_category(const _Iter&)
205 { return typename iterator_traits<_Iter>::iterator_category(); }
206
207 //@}
208
209 // If _Iterator has a base returns it otherwise _Iterator is returned
210 // untouched
211 template<typename _Iterator, bool _HasBase>
212 struct _Iter_base
213 {
214 typedef _Iterator iterator_type;
215 static iterator_type _S_base(_Iterator __it)
216 { return __it; }
217 };
218
219 template<typename _Iterator>
220 struct _Iter_base<_Iterator, true>
221 {
222 typedef typename _Iterator::iterator_type iterator_type;
223 static iterator_type _S_base(_Iterator __it)
224 { return __it.base(); }
225 };
226
227#if __cplusplus >= 201103L
228 template<typename _InIter>
229 using _RequireInputIter = typename
230 enable_if<is_convertible<typename
231 iterator_traits<_InIter>::iterator_category,
232 input_iterator_tag>::value>::type;
233#endif
234
235_GLIBCXX_END_NAMESPACE_VERSION
236} // namespace
237
238#endif /* _STL_ITERATOR_BASE_TYPES_H */
239
240