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 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
  81   ///  Marking output iterators.
  82   struct output_iterator_tag { };
  83
  84   /// Forward iterators support a superset of input iterator operations.
  85   struct forward_iterator_tag : public input_iterator_tag { };
  86
  87   /// Bidirectional iterators support a superset of forward iterator
  88   /// operations.
  89   struct bidirectional_iterator_tag : public forward_iterator_tag { };
  90
  91   /// Random-access iterators support a superset of bidirectional
  92   /// iterator operations.
  93   struct random_access_iterator_tag : public bidirectional_iterator_tag { };
  94
  95
  96   /**
  97    *  @brief  Common %iterator class.
  98    *
  99    *  This class does nothing but define nested typedefs.  %Iterator classes
 100    *  can inherit from this class to save some work.  The typedefs are then
 101    *  used in specializations and overloading.
 102    *
 103    *  In particular, there are no default implementations of requirements
 104    *  such as @c operator++ and the like.  (How could there be?)
 105   */
 106   template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
 107            typename _Pointer = _Tp*, typename _Reference = _Tp&>
 108     struct iterator
 109     {
 110       /// One of the @link iterator_tags tag types@endlink.
 111       typedef _Category  iterator_category;
 112       /// The type "pointed to" by the iterator.
 113       typedef _Tp        value_type;
 114       /// Distance between iterators is represented as this type.
 115       typedef _Distance  difference_type;
 116       /// This type represents a pointer-to-value_type.
 117       typedef _Pointer   pointer;
 118       /// This type represents a reference-to-value_type.
 119       typedef _Reference reference;
 120     };
 121
 122   /**
 123    *  @brief  Traits class for iterators.
 124    *
 125    *  This class does nothing but define nested typedefs.  The general
 126    *  version simply @a forwards the nested typedefs from the Iterator
 127    *  argument.  Specialized versions for pointers and pointers-to-const
 128    *  provide tighter, more correct semantics.
 129   */
 130   template<typename _Iterator>
 131     struct iterator_traits
 132     {
 133       typedef typename _Iterator::iterator_category iterator_category;
 134       typedef typename _Iterator::value_type        value_type;
 135       typedef typename _Iterator::difference_type   difference_type;
 136       typedef typename _Iterator::pointer           pointer;
 137       typedef typename _Iterator::reference         reference;
 138     };
 139
 140   /// Partial specialization for pointer types.
 141   template<typename _Tp>
 142     struct iterator_traits<_Tp*>
 143     {
 144       typedef random_access_iterator_tag iterator_category;
 145       typedef _Tp                         value_type;
 146       typedef ptrdiff_t                   difference_type;
 147       typedef _Tp*                        pointer;
 148       typedef _Tp&                        reference;
 149     };
 150
 151   /// Partial specialization for const pointer types.
 152   template<typename _Tp>
 153     struct iterator_traits<const _Tp*>
 154     {
 155       typedef random_access_iterator_tag iterator_category;
 156       typedef _Tp                         value_type;
 157       typedef ptrdiff_t                   difference_type;
 158       typedef const _Tp*                  pointer;
 159       typedef const _Tp&                  reference;
 160     };
 161
 162   /**
 163    *  This function is not a part of the C++ standard but is syntactic
 164    *  sugar for internal library use only.
 165   */
 166   template<typename _Iter>
 167     inline typename iterator_traits<_Iter>::iterator_category
 168     __iterator_category(const _Iter&)
 169     { return typename iterator_traits<_Iter>::iterator_category(); }
 170
 171   //@}
 172
 173 _GLIBCXX_END_NAMESPACE
 174
 175 #endif /* _STL_ITERATOR_BASE_TYPES_H */
 176