libstdc++
stl_iterator_base_types.h
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1 // Types used in iterator implementation -*- C++ -*-
2 
3 // Copyright (C) 2001-2014 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
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10 
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15 
16 // Under Section 7 of GPL version 3, you are granted additional
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18 // 3.1, as published by the Free Software Foundation.
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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,
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33  * that both that copyright notice and this permission notice appear
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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.
96 
97  /// Bidirectional iterators support a superset of forward iterator
98  /// operations.
100 
101  /// Random-access iterators support a superset of bidirectional
102  /// iterator operations.
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  {
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  {
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 
_Pointer pointer
This type represents a pointer-to-value_type.
_Distance difference_type
Distance between iterators is represented as this type.
Common iterator class.
Forward iterators support a superset of input iterator operations.
Marking input iterators.
ISO C++ entities toplevel namespace is std.
_Reference reference
This type represents a reference-to-value_type.
_Tp value_type
The type "pointed to" by the iterator.
Bidirectional iterators support a superset of forward iterator operations.
iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Marking output iterators.
Random-access iterators support a superset of bidirectional iterator operations.
_Category iterator_category
One of the tag types.