1// Types used in iterator implementation -*- 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_types.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 types,
57 * such as iterator_traits and struct iterator.
58 */
59
60#ifndef _STL_ITERATOR_BASE_TYPES_H
61#define _STL_ITERATOR_BASE_TYPES_H 1
62
63#pragma GCC system_header
64
65#include <bits/c++config.h>
66
67#ifdef __GXX_EXPERIMENTAL_CXX0X__
68# include <type_traits> // For _GLIBCXX_HAS_NESTED_TYPE
69#endif
70
71namespace std _GLIBCXX_VISIBILITY(default)
72{
73_GLIBCXX_BEGIN_NAMESPACE_VERSION
74
75 /**
76 * @defgroup iterators Iterators
77 * Abstractions for uniform iterating through various underlying types.
78 */
79 //@{
80
81 /**
82 * @defgroup iterator_tags Iterator Tags
83 * These are empty types, used to distinguish different iterators. The
84 * distinction is not made by what they contain, but simply by what they
85 * are. Different underlying algorithms can then be used based on the
86 * different operations supported by different iterator types.
87 */
88 //@{
89 /// Marking input iterators.
90 struct input_iterator_tag { };
91
92 /// Marking output iterators.
93 struct output_iterator_tag { };
94
95 /// Forward iterators support a superset of input iterator operations.
96 struct forward_iterator_tag : public input_iterator_tag { };
97
98 /// Bidirectional iterators support a superset of forward iterator
99 /// operations.
100 struct bidirectional_iterator_tag : public forward_iterator_tag { };
101
102 /// Random-access iterators support a superset of bidirectional
103 /// iterator operations.
104 struct random_access_iterator_tag : public bidirectional_iterator_tag { };
105 //@}
106
107 /**
108 * @brief Common %iterator class.
109 *
110 * This class does nothing but define nested typedefs. %Iterator classes
111 * can inherit from this class to save some work. The typedefs are then
112 * used in specializations and overloading.
113 *
114 * In particular, there are no default implementations of requirements
115 * such as @c operator++ and the like. (How could there be?)
116 */
117 template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
118 typename _Pointer = _Tp*, typename _Reference = _Tp&>
119 struct iterator
120 {
121 /// One of the @link iterator_tags tag types@endlink.
122 typedef _Category iterator_category;
123 /// The type "pointed to" by the iterator.
124 typedef _Tp value_type;
125 /// Distance between iterators is represented as this type.
126 typedef _Distance difference_type;
127 /// This type represents a pointer-to-value_type.
128 typedef _Pointer pointer;
129 /// This type represents a reference-to-value_type.
130 typedef _Reference reference;
131 };
132
133 /**
134 * @brief Traits class for iterators.
135 *
136 * This class does nothing but define nested typedefs. The general
137 * version simply @a forwards the nested typedefs from the Iterator
138 * argument. Specialized versions for pointers and pointers-to-const
139 * provide tighter, more correct semantics.
140 */
141#ifdef __GXX_EXPERIMENTAL_CXX0X__
142
143_GLIBCXX_HAS_NESTED_TYPE(iterator_category)
144
145 template<typename _Iterator,
146 bool = __has_iterator_category<_Iterator>::value>
147 struct __iterator_traits { };
148
149 template<typename _Iterator>
150 struct __iterator_traits<_Iterator, true>
151 {
152 typedef typename _Iterator::iterator_category iterator_category;
153 typedef typename _Iterator::value_type value_type;
154 typedef typename _Iterator::difference_type difference_type;
155 typedef typename _Iterator::pointer pointer;
156 typedef typename _Iterator::reference reference;
157 };
158
159 template<typename _Iterator>
160 struct iterator_traits
161 : public __iterator_traits<_Iterator> { };
162#else
163 template<typename _Iterator>
164 struct iterator_traits
165 {
166 typedef typename _Iterator::iterator_category iterator_category;
167 typedef typename _Iterator::value_type value_type;
168 typedef typename _Iterator::difference_type difference_type;
169 typedef typename _Iterator::pointer pointer;
170 typedef typename _Iterator::reference reference;
171 };
172#endif
173
174 /// Partial specialization for pointer types.
175 template<typename _Tp>
176 struct iterator_traits<_Tp*>
177 {
178 typedef random_access_iterator_tag iterator_category;
179 typedef _Tp value_type;
180 typedef ptrdiff_t difference_type;
181 typedef _Tp* pointer;
182 typedef _Tp& reference;
183 };
184
185 /// Partial specialization for const pointer types.
186 template<typename _Tp>
187 struct iterator_traits<const _Tp*>
188 {
189 typedef random_access_iterator_tag iterator_category;
190 typedef _Tp value_type;
191 typedef ptrdiff_t difference_type;
192 typedef const _Tp* pointer;
193 typedef const _Tp& reference;
194 };
195
196 /**
197 * This function is not a part of the C++ standard but is syntactic
198 * sugar for internal library use only.
199 */
200 template<typename _Iter>
201 inline typename iterator_traits<_Iter>::iterator_category
202 __iterator_category(const _Iter&)
203 { return typename iterator_traits<_Iter>::iterator_category(); }
204
205 //@}
206
207 // If _Iterator has a base returns it otherwise _Iterator is returned
208 // untouched
209 template<typename _Iterator, bool _HasBase>
210 struct _Iter_base
211 {
212 typedef _Iterator iterator_type;
213 static iterator_type _S_base(_Iterator __it)
214 { return __it; }
215 };
216
217 template<typename _Iterator>
218 struct _Iter_base<_Iterator, true>
219 {
220 typedef typename _Iterator::iterator_type iterator_type;
221 static iterator_type _S_base(_Iterator __it)
222 { return __it.base(); }
223 };
224
225_GLIBCXX_END_NAMESPACE_VERSION
226} // namespace
227
228#endif /* _STL_ITERATOR_BASE_TYPES_H */
229
230