libstdc++-v3/include/bits/stl_iterator_base_types.h

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