libstdc++
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00001 // Types used in iterator implementation -*- C++ -*- 00002 00003 // Copyright (C) 2001-2015 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /* 00026 * 00027 * Copyright (c) 1994 00028 * Hewlett-Packard Company 00029 * 00030 * Permission to use, copy, modify, distribute and sell this software 00031 * and its documentation for any purpose is hereby granted without fee, 00032 * provided that the above copyright notice appear in all copies and 00033 * that both that copyright notice and this permission notice appear 00034 * in supporting documentation. Hewlett-Packard Company makes no 00035 * representations about the suitability of this software for any 00036 * purpose. It is provided "as is" without express or implied warranty. 00037 * 00038 * 00039 * Copyright (c) 1996-1998 00040 * Silicon Graphics Computer Systems, Inc. 00041 * 00042 * Permission to use, copy, modify, distribute and sell this software 00043 * and its documentation for any purpose is hereby granted without fee, 00044 * provided that the above copyright notice appear in all copies and 00045 * that both that copyright notice and this permission notice appear 00046 * in supporting documentation. Silicon Graphics makes no 00047 * representations about the suitability of this software for any 00048 * purpose. It is provided "as is" without express or implied warranty. 00049 */ 00050 00051 /** @file bits/stl_iterator_base_types.h 00052 * This is an internal header file, included by other library headers. 00053 * Do not attempt to use it directly. @headername{iterator} 00054 * 00055 * This file contains all of the general iterator-related utility types, 00056 * such as iterator_traits and struct iterator. 00057 */ 00058 00059 #ifndef _STL_ITERATOR_BASE_TYPES_H 00060 #define _STL_ITERATOR_BASE_TYPES_H 1 00061 00062 #pragma GCC system_header 00063 00064 #include <bits/c++config.h> 00065 00066 #if __cplusplus >= 201103L 00067 # include <type_traits> // For __void_t, is_convertible 00068 #endif 00069 00070 namespace std _GLIBCXX_VISIBILITY(default) 00071 { 00072 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00073 00074 /** 00075 * @defgroup iterators Iterators 00076 * Abstractions for uniform iterating through various underlying types. 00077 */ 00078 //@{ 00079 00080 /** 00081 * @defgroup iterator_tags Iterator Tags 00082 * These are empty types, used to distinguish different iterators. The 00083 * distinction is not made by what they contain, but simply by what they 00084 * are. Different underlying algorithms can then be used based on the 00085 * different operations supported by different iterator types. 00086 */ 00087 //@{ 00088 /// Marking input iterators. 00089 struct input_iterator_tag { }; 00090 00091 /// Marking output iterators. 00092 struct output_iterator_tag { }; 00093 00094 /// Forward iterators support a superset of input iterator operations. 00095 struct forward_iterator_tag : public input_iterator_tag { }; 00096 00097 /// Bidirectional iterators support a superset of forward iterator 00098 /// operations. 00099 struct bidirectional_iterator_tag : public forward_iterator_tag { }; 00100 00101 /// Random-access iterators support a superset of bidirectional 00102 /// iterator operations. 00103 struct random_access_iterator_tag : public bidirectional_iterator_tag { }; 00104 //@} 00105 00106 /** 00107 * @brief Common %iterator class. 00108 * 00109 * This class does nothing but define nested typedefs. %Iterator classes 00110 * can inherit from this class to save some work. The typedefs are then 00111 * used in specializations and overloading. 00112 * 00113 * In particular, there are no default implementations of requirements 00114 * such as @c operator++ and the like. (How could there be?) 00115 */ 00116 template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t, 00117 typename _Pointer = _Tp*, typename _Reference = _Tp&> 00118 struct iterator 00119 { 00120 /// One of the @link iterator_tags tag types@endlink. 00121 typedef _Category iterator_category; 00122 /// The type "pointed to" by the iterator. 00123 typedef _Tp value_type; 00124 /// Distance between iterators is represented as this type. 00125 typedef _Distance difference_type; 00126 /// This type represents a pointer-to-value_type. 00127 typedef _Pointer pointer; 00128 /// This type represents a reference-to-value_type. 00129 typedef _Reference reference; 00130 }; 00131 00132 /** 00133 * @brief Traits class for iterators. 00134 * 00135 * This class does nothing but define nested typedefs. The general 00136 * version simply @a forwards the nested typedefs from the Iterator 00137 * argument. Specialized versions for pointers and pointers-to-const 00138 * provide tighter, more correct semantics. 00139 */ 00140 #if __cplusplus >= 201103L 00141 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00142 // 2408. SFINAE-friendly common_type/iterator_traits is missing in C++14 00143 template<typename _Iterator, typename = __void_t<>> 00144 struct __iterator_traits { }; 00145 00146 template<typename _Iterator> 00147 struct __iterator_traits<_Iterator, 00148 __void_t<typename _Iterator::iterator_category, 00149 typename _Iterator::value_type, 00150 typename _Iterator::difference_type, 00151 typename _Iterator::pointer, 00152 typename _Iterator::reference>> 00153 { 00154 typedef typename _Iterator::iterator_category iterator_category; 00155 typedef typename _Iterator::value_type value_type; 00156 typedef typename _Iterator::difference_type difference_type; 00157 typedef typename _Iterator::pointer pointer; 00158 typedef typename _Iterator::reference reference; 00159 }; 00160 00161 template<typename _Iterator> 00162 struct iterator_traits 00163 : public __iterator_traits<_Iterator> { }; 00164 #else 00165 template<typename _Iterator> 00166 struct iterator_traits 00167 { 00168 typedef typename _Iterator::iterator_category iterator_category; 00169 typedef typename _Iterator::value_type value_type; 00170 typedef typename _Iterator::difference_type difference_type; 00171 typedef typename _Iterator::pointer pointer; 00172 typedef typename _Iterator::reference reference; 00173 }; 00174 #endif 00175 00176 /// Partial specialization for pointer types. 00177 template<typename _Tp> 00178 struct iterator_traits<_Tp*> 00179 { 00180 typedef random_access_iterator_tag iterator_category; 00181 typedef _Tp value_type; 00182 typedef ptrdiff_t difference_type; 00183 typedef _Tp* pointer; 00184 typedef _Tp& reference; 00185 }; 00186 00187 /// Partial specialization for const pointer types. 00188 template<typename _Tp> 00189 struct iterator_traits<const _Tp*> 00190 { 00191 typedef random_access_iterator_tag iterator_category; 00192 typedef _Tp value_type; 00193 typedef ptrdiff_t difference_type; 00194 typedef const _Tp* pointer; 00195 typedef const _Tp& reference; 00196 }; 00197 00198 /** 00199 * This function is not a part of the C++ standard but is syntactic 00200 * sugar for internal library use only. 00201 */ 00202 template<typename _Iter> 00203 inline typename iterator_traits<_Iter>::iterator_category 00204 __iterator_category(const _Iter&) 00205 { return typename iterator_traits<_Iter>::iterator_category(); } 00206 00207 //@} 00208 00209 // If _Iterator has a base returns it otherwise _Iterator is returned 00210 // untouched 00211 template<typename _Iterator, bool _HasBase> 00212 struct _Iter_base 00213 { 00214 typedef _Iterator iterator_type; 00215 static iterator_type _S_base(_Iterator __it) 00216 { return __it; } 00217 }; 00218 00219 template<typename _Iterator> 00220 struct _Iter_base<_Iterator, true> 00221 { 00222 typedef typename _Iterator::iterator_type iterator_type; 00223 static iterator_type _S_base(_Iterator __it) 00224 { return __it.base(); } 00225 }; 00226 00227 #if __cplusplus >= 201103L 00228 template<typename _InIter> 00229 using _RequireInputIter = typename 00230 enable_if<is_convertible<typename 00231 iterator_traits<_InIter>::iterator_category, 00232 input_iterator_tag>::value>::type; 00233 #endif 00234 00235 _GLIBCXX_END_NAMESPACE_VERSION 00236 } // namespace 00237 00238 #endif /* _STL_ITERATOR_BASE_TYPES_H */ 00239