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
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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;
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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 stl_iterator_base_types.h
53 : * This is an internal header file, included by other library headers.
54 : * You should not attempt to use it directly.
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 : #include <cstddef>
67 :
68 : _GLIBCXX_BEGIN_NAMESPACE(std)
69 :
70 : /**
71 : * @defgroup iterators Iterators
72 : * Abstractions for uniform iterating through various underlying types.
73 : */
74 : //@{
75 :
76 : /**
77 : * @defgroup iterator_tags Iterator Tags
78 : * These are empty types, used to distinguish different iterators. The
79 : * distinction is not made by what they contain, but simply by what they
80 : * are. Different underlying algorithms can then be used based on the
81 : * different operations supported by different iterator types.
82 : */
83 : //@{
84 : /// Marking input iterators.
85 : struct input_iterator_tag { };
86 :
87 : /// Marking output iterators.
88 : struct output_iterator_tag { };
89 :
90 : /// Forward iterators support a superset of input iterator operations.
91 : struct forward_iterator_tag : public input_iterator_tag { };
92 :
93 : /// Bidirectional iterators support a superset of forward iterator
94 : /// operations.
95 : struct bidirectional_iterator_tag : public forward_iterator_tag { };
96 :
97 : /// Random-access iterators support a superset of bidirectional
98 : /// iterator operations.
99 : struct random_access_iterator_tag : public bidirectional_iterator_tag { };
100 : //@}
101 :
102 : /**
103 : * @brief Common %iterator class.
104 : *
105 : * This class does nothing but define nested typedefs. %Iterator classes
106 : * can inherit from this class to save some work. The typedefs are then
107 : * used in specializations and overloading.
108 : *
109 : * In particular, there are no default implementations of requirements
110 : * such as @c operator++ and the like. (How could there be?)
111 : */
112 : template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
113 : typename _Pointer = _Tp*, typename _Reference = _Tp&>
114 : struct iterator
115 389 : {
116 : /// One of the @link iterator_tags tag types@endlink.
117 : typedef _Category iterator_category;
118 : /// The type "pointed to" by the iterator.
119 : typedef _Tp value_type;
120 : /// Distance between iterators is represented as this type.
121 : typedef _Distance difference_type;
122 : /// This type represents a pointer-to-value_type.
123 : typedef _Pointer pointer;
124 : /// This type represents a reference-to-value_type.
125 : typedef _Reference reference;
126 : };
127 :
128 : /**
129 : * @brief Traits class for iterators.
130 : *
131 : * This class does nothing but define nested typedefs. The general
132 : * version simply @a forwards the nested typedefs from the Iterator
133 : * argument. Specialized versions for pointers and pointers-to-const
134 : * provide tighter, more correct semantics.
135 : */
136 : template<typename _Iterator>
137 : struct iterator_traits
138 : {
139 : typedef typename _Iterator::iterator_category iterator_category;
140 : typedef typename _Iterator::value_type value_type;
141 : typedef typename _Iterator::difference_type difference_type;
142 : typedef typename _Iterator::pointer pointer;
143 : typedef typename _Iterator::reference reference;
144 : };
145 :
146 : /// Partial specialization for pointer types.
147 : template<typename _Tp>
148 : struct iterator_traits<_Tp*>
149 : {
150 : typedef random_access_iterator_tag iterator_category;
151 : typedef _Tp value_type;
152 : typedef ptrdiff_t difference_type;
153 : typedef _Tp* pointer;
154 : typedef _Tp& reference;
155 : };
156 :
157 : /// Partial specialization for const pointer types.
158 : template<typename _Tp>
159 : struct iterator_traits<const _Tp*>
160 : {
161 : typedef random_access_iterator_tag iterator_category;
162 : typedef _Tp value_type;
163 : typedef ptrdiff_t difference_type;
164 : typedef const _Tp* pointer;
165 : typedef const _Tp& reference;
166 : };
167 :
168 : /**
169 : * This function is not a part of the C++ standard but is syntactic
170 : * sugar for internal library use only.
171 : */
172 : template<typename _Iter>
173 : inline typename iterator_traits<_Iter>::iterator_category
174 1714 : __iterator_category(const _Iter&)
175 1714 : { return typename iterator_traits<_Iter>::iterator_category(); }
176 :
177 : //@}
178 :
179 : _GLIBCXX_END_NAMESPACE
180 :
181 : #endif /* _STL_ITERATOR_BASE_TYPES_H */
182 :
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