1// Types used in iterator implementation -*- C++ -*- 2 3// Copyright (C) 2001-2013 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 7// terms of the GNU General Public License as published by the 8// Free Software Foundation; either version 3, or (at your option) 9// any later version. 10 11// This library is distributed in the hope that it will be useful, 12// but WITHOUT ANY WARRANTY; without even the implied warranty of 13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14// GNU General Public License for more details. 15 16// Under Section 7 of GPL version 3, you are granted additional 17// permissions described in the GCC Runtime Library Exception, version 18// 3.1, as published by the Free Software Foundation. 19 20// You should have received a copy of the GNU General Public License and 21// a copy of the GCC Runtime Library Exception along with this program; 22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23// <http://www.gnu.org/licenses/>. 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, 32 * provided that the above copyright notice appear in all copies and 33 * that both that copyright notice and this permission notice appear 34 * in supporting documentation. Hewlett-Packard Company makes no 35 * representations about the suitability of this software for any 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 70namespace 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. 95 struct forward_iterator_tag : public input_iterator_tag { }; 96 97 /// Bidirectional iterators support a superset of forward iterator 98 /// operations. 99 struct bidirectional_iterator_tag : public forward_iterator_tag { }; 100 101 /// Random-access iterators support a superset of bidirectional 102 /// iterator operations. 103 struct random_access_iterator_tag : public bidirectional_iterator_tag { }; 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 { 177 typedef random_access_iterator_tag iterator_category; 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 { 188 typedef random_access_iterator_tag iterator_category; 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 */ 236 237