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
   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