libstdc++
stl_iterator_base_types.h
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1 // Types used in iterator implementation -*- C++ -*-
2 
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
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 
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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
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19 // 3.1, as published by the Free Software Foundation.
20 
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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  * These are empty types, used to distinguish different iterators. The
73  * distinction is not made by what they contain, but simply by what they
74  * are. Different underlying algorithms can then be used based on the
75  * different operations supported by different iterator types.
76  */
77  //@{
78  /// Marking input iterators.
79  struct input_iterator_tag { };
80  /// Marking output iterators.
81  struct output_iterator_tag { };
82  /// Forward iterators support a superset of input iterator operations.
84  /// Bidirectional iterators support a superset of forward iterator
85  /// operations.
87  /// Random-access iterators support a superset of bidirectional iterator
88  /// operations.
90 
91 
92  /**
93  * @brief Common %iterator class.
94  *
95  * This class does nothing but define nested typedefs. %Iterator classes
96  * can inherit from this class to save some work. The typedefs are then
97  * used in specializations and overloading.
98  *
99  * In particular, there are no default implementations of requirements
100  * such as @c operator++ and the like. (How could there be?)
101  */
102  template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
103  typename _Pointer = _Tp*, typename _Reference = _Tp&>
104  struct iterator
105  {
106  /// One of the @link iterator_tags tag types@endlink.
107  typedef _Category iterator_category;
108  /// The type "pointed to" by the iterator.
109  typedef _Tp value_type;
110  /// Distance between iterators is represented as this type.
111  typedef _Distance difference_type;
112  /// This type represents a pointer-to-value_type.
113  typedef _Pointer pointer;
114  /// This type represents a reference-to-value_type.
115  typedef _Reference reference;
116  };
117 
118  /**
119  * This class does nothing but define nested typedefs. The general
120  * version simply "forwards" the nested typedefs from the Iterator
121  * argument. Specialized versions for pointers and pointers-to-const
122  * provide tighter, more correct semantics.
123  */
124  template<typename _Iterator>
126  {
127  typedef typename _Iterator::iterator_category iterator_category;
128  typedef typename _Iterator::value_type value_type;
129  typedef typename _Iterator::difference_type difference_type;
130  typedef typename _Iterator::pointer pointer;
131  typedef typename _Iterator::reference reference;
132  };
133 
134  template<typename _Tp>
135  struct iterator_traits<_Tp*>
136  {
137  typedef random_access_iterator_tag iterator_category;
138  typedef _Tp value_type;
139  typedef ptrdiff_t difference_type;
140  typedef _Tp* pointer;
141  typedef _Tp& reference;
142  };
143 
144  template<typename _Tp>
145  struct iterator_traits<const _Tp*>
146  {
147  typedef random_access_iterator_tag iterator_category;
148  typedef _Tp value_type;
149  typedef ptrdiff_t difference_type;
150  typedef const _Tp* pointer;
151  typedef const _Tp& reference;
152  };
153 
154  /**
155  * This function is not a part of the C++ standard but is syntactic
156  * sugar for internal library use only.
157  */
158  template<typename _Iter>
159  inline typename iterator_traits<_Iter>::iterator_category
160  __iterator_category(const _Iter&)
161  { return typename iterator_traits<_Iter>::iterator_category(); }
162 
163  //@}
164 
165 _GLIBCXX_END_NAMESPACE
166 
167 #endif /* _STL_ITERATOR_BASE_TYPES_H */
168 
Common iterator class.
Bidirectional iterators support a superset of forward iterator operations.
_Tp value_type
The type "pointed to" by the iterator.
Marking input iterators.
_Pointer pointer
This type represents a pointer-to-value_type.
Marking output iterators.
iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
_Distance difference_type
Distance between iterators is represented as this type.
_Category iterator_category
One of the tag types.
Random-access iterators support a superset of bidirectional iterator operations.
_Reference reference
This type represents a reference-to-value_type.
Forward iterators support a superset of input iterator operations.