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 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 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; 23// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24// <http://www.gnu.org/licenses/>. 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 bits/stl_iterator_base_types.h 53 * This is an internal header file, included by other library headers. 54 * Do not attempt to use it directly. @headername{iterator} 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 67#ifdef __GXX_EXPERIMENTAL_CXX0X__ 68# include <type_traits> // For _GLIBCXX_HAS_NESTED_TYPE 69#endif 70 71namespace std _GLIBCXX_VISIBILITY(default) 72{ 73_GLIBCXX_BEGIN_NAMESPACE_VERSION 74 75 /** 76 * @defgroup iterators Iterators 77 * Abstractions for uniform iterating through various underlying types. 78 */ 79 //@{ 80 81 /** 82 * @defgroup iterator_tags Iterator Tags 83 * These are empty types, used to distinguish different iterators. The 84 * distinction is not made by what they contain, but simply by what they 85 * are. Different underlying algorithms can then be used based on the 86 * different operations supported by different iterator types. 87 */ 88 //@{ 89 /// Marking input iterators. 90 struct input_iterator_tag { }; 91 92 /// Marking output iterators. 93 struct output_iterator_tag { }; 94 95 /// Forward iterators support a superset of input iterator operations. 96 struct forward_iterator_tag : public input_iterator_tag { }; 97 98 /// Bidirectional iterators support a superset of forward iterator 99 /// operations. 100 struct bidirectional_iterator_tag : public forward_iterator_tag { }; 101 102 /// Random-access iterators support a superset of bidirectional 103 /// iterator operations. 104 struct random_access_iterator_tag : public bidirectional_iterator_tag { }; 105 //@} 106 107 /** 108 * @brief Common %iterator class. 109 * 110 * This class does nothing but define nested typedefs. %Iterator classes 111 * can inherit from this class to save some work. The typedefs are then 112 * used in specializations and overloading. 113 * 114 * In particular, there are no default implementations of requirements 115 * such as @c operator++ and the like. (How could there be?) 116 */ 117 template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t, 118 typename _Pointer = _Tp*, typename _Reference = _Tp&> 119 struct iterator 120 { 121 /// One of the @link iterator_tags tag types@endlink. 122 typedef _Category iterator_category; 123 /// The type "pointed to" by the iterator. 124 typedef _Tp value_type; 125 /// Distance between iterators is represented as this type. 126 typedef _Distance difference_type; 127 /// This type represents a pointer-to-value_type. 128 typedef _Pointer pointer; 129 /// This type represents a reference-to-value_type. 130 typedef _Reference reference; 131 }; 132 133 /** 134 * @brief Traits class for iterators. 135 * 136 * This class does nothing but define nested typedefs. The general 137 * version simply @a forwards the nested typedefs from the Iterator 138 * argument. Specialized versions for pointers and pointers-to-const 139 * provide tighter, more correct semantics. 140 */ 141#ifdef __GXX_EXPERIMENTAL_CXX0X__ 142 143_GLIBCXX_HAS_NESTED_TYPE(iterator_category) 144 145 template<typename _Iterator, 146 bool = __has_iterator_category<_Iterator>::value> 147 struct __iterator_traits { }; 148 149 template<typename _Iterator> 150 struct __iterator_traits<_Iterator, true> 151 { 152 typedef typename _Iterator::iterator_category iterator_category; 153 typedef typename _Iterator::value_type value_type; 154 typedef typename _Iterator::difference_type difference_type; 155 typedef typename _Iterator::pointer pointer; 156 typedef typename _Iterator::reference reference; 157 }; 158 159 template<typename _Iterator> 160 struct iterator_traits 161 : public __iterator_traits<_Iterator> { }; 162#else 163 template<typename _Iterator> 164 struct iterator_traits 165 { 166 typedef typename _Iterator::iterator_category iterator_category; 167 typedef typename _Iterator::value_type value_type; 168 typedef typename _Iterator::difference_type difference_type; 169 typedef typename _Iterator::pointer pointer; 170 typedef typename _Iterator::reference reference; 171 }; 172#endif 173 174 /// Partial specialization for pointer types. 175 template<typename _Tp> 176 struct iterator_traits<_Tp*> 177 { 178 typedef random_access_iterator_tag iterator_category; 179 typedef _Tp value_type; 180 typedef ptrdiff_t difference_type; 181 typedef _Tp* pointer; 182 typedef _Tp& reference; 183 }; 184 185 /// Partial specialization for const pointer types. 186 template<typename _Tp> 187 struct iterator_traits<const _Tp*> 188 { 189 typedef random_access_iterator_tag iterator_category; 190 typedef _Tp value_type; 191 typedef ptrdiff_t difference_type; 192 typedef const _Tp* pointer; 193 typedef const _Tp& reference; 194 }; 195 196 /** 197 * This function is not a part of the C++ standard but is syntactic 198 * sugar for internal library use only. 199 */ 200 template<typename _Iter> 201 inline typename iterator_traits<_Iter>::iterator_category 202 __iterator_category(const _Iter&) 203 { return typename iterator_traits<_Iter>::iterator_category(); } 204 205 //@} 206 207 // If _Iterator has a base returns it otherwise _Iterator is returned 208 // untouched 209 template<typename _Iterator, bool _HasBase> 210 struct _Iter_base 211 { 212 typedef _Iterator iterator_type; 213 static iterator_type _S_base(_Iterator __it) 214 { return __it; } 215 }; 216 217 template<typename _Iterator> 218 struct _Iter_base<_Iterator, true> 219 { 220 typedef typename _Iterator::iterator_type iterator_type; 221 static iterator_type _S_base(_Iterator __it) 222 { return __it.base(); } 223 }; 224 225_GLIBCXX_END_NAMESPACE_VERSION 226} // namespace 227 228#endif /* _STL_ITERATOR_BASE_TYPES_H */ 229 230