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 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 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. 83 struct forward_iterator_tag : public input_iterator_tag { }; 84 /// Bidirectional iterators support a superset of forward iterator 85 /// operations. 86 struct bidirectional_iterator_tag : public forward_iterator_tag { }; 87 /// Random-access iterators support a superset of bidirectional iterator 88 /// operations. 89 struct random_access_iterator_tag : public bidirectional_iterator_tag { }; 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> 125 struct iterator_traits 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 */ 168 169
