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 2, 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 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING.  If not, write to the Free
  19 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  20 // USA.
  21
  22 // As a special exception, you may use this file as part of a free software
  23 // library without restriction.  Specifically, if other files instantiate
  24 // templates or use macros or inline functions from this file, or you compile
  25 // this file and link it with other files to produce an executable, this
  26 // file does not by itself cause the resulting executable to be covered by
  27 // the GNU General Public License.  This exception does not however
  28 // invalidate any other reasons why the executable file might be covered by
  29 // the GNU General Public License.
  30
  31 /*
  32  *
  33  * Copyright (c) 1994
  34  * Hewlett-Packard Company
  35  *
  36  * Permission to use, copy, modify, distribute and sell this software
  37  * and its documentation for any purpose is hereby granted without fee,
  38  * provided that the above copyright notice appear in all copies and
  39  * that both that copyright notice and this permission notice appear
  40  * in supporting documentation.  Hewlett-Packard Company makes no
  41  * representations about the suitability of this software for any
  42  * purpose.  It is provided "as is" without express or implied warranty.
  43  *
  44  *
  45  * Copyright (c) 1996-1998
  46  * Silicon Graphics Computer Systems, Inc.
  47  *
  48  * Permission to use, copy, modify, distribute and sell this software
  49  * and its documentation for any purpose is hereby granted without fee,
  50  * provided that the above copyright notice appear in all copies and
  51  * that both that copyright notice and this permission notice appear
  52  * in supporting documentation.  Silicon Graphics makes no
  53  * representations about the suitability of this software for any
  54  * purpose.  It is provided "as is" without express or implied warranty.
  55  */
  56
  57 /** @file stl_iterator_base_types.h
  58  *  This is an internal header file, included by other library headers.
  59  *  You should not attempt to use it directly.
  60  *
  61  *  This file contains all of the general iterator-related utility types,
  62  *  such as iterator_traits and struct iterator.
  63  */
  64
  65 #ifndef _STL_ITERATOR_BASE_TYPES_H
  66 #define _STL_ITERATOR_BASE_TYPES_H 1
  67
  68 #pragma GCC system_header
  69
  70 #include <bits/c++config.h>
  71 #include <cstddef>
  72
  73 _GLIBCXX_BEGIN_NAMESPACE(std)
  74
  75   /**
  76    *  @defgroup iterators Iterators
  77    *  These are empty types, used to distinguish different iterators.  The
  78    *  distinction is not made by what they contain, but simply by what they
  79    *  are.  Different underlying algorithms can then be used based on the
  80    *  different operations supported by different iterator types.
  81   */
  82   //@{
  83   ///  Marking input iterators.
  84   struct input_iterator_tag { };
  85   ///  Marking output iterators.
  86   struct output_iterator_tag { };
  87   /// Forward iterators support a superset of input iterator operations.
  88   struct forward_iterator_tag : public input_iterator_tag { };
  89   /// Bidirectional iterators support a superset of forward iterator
  90   /// operations.
  91   struct bidirectional_iterator_tag : public forward_iterator_tag { };
  92   /// Random-access iterators support a superset of bidirectional iterator
  93   /// operations.
  94   struct random_access_iterator_tag : public bidirectional_iterator_tag { };
  95
  96
  97   /**
  98    *  @brief  Common %iterator class.
  99    *
 100    *  This class does nothing but define nested typedefs.  %Iterator classes
 101    *  can inherit from this class to save some work.  The typedefs are then
 102    *  used in specializations and overloading.
 103    *
 104    *  In particular, there are no default implementations of requirements
 105    *  such as @c operator++ and the like.  (How could there be?)
 106   */
 107   template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
 108            typename _Pointer = _Tp*, typename _Reference = _Tp&>
 109     struct iterator
 110     {
 111       /// One of the @link iterator_tags tag types@endlink.
 112       typedef _Category  iterator_category;
 113       /// The type "pointed to" by the iterator.
 114       typedef _Tp        value_type;
 115       /// Distance between iterators is represented as this type.
 116       typedef _Distance  difference_type;
 117       /// This type represents a pointer-to-value_type.
 118       typedef _Pointer   pointer;
 119       /// This type represents a reference-to-value_type.
 120       typedef _Reference reference;
 121     };
 122
 123   /**
 124    *  This class does nothing but define nested typedefs.  The general
 125    *  version simply "forwards" the nested typedefs from the Iterator
 126    *  argument.  Specialized versions for pointers and pointers-to-const
 127    *  provide tighter, more correct semantics.
 128   */
 129   template<typename _Iterator>
 130     struct iterator_traits
 131     {
 132       typedef typename _Iterator::iterator_category iterator_category;
 133       typedef typename _Iterator::value_type        value_type;
 134       typedef typename _Iterator::difference_type   difference_type;
 135       typedef typename _Iterator::pointer           pointer;
 136       typedef typename _Iterator::reference         reference;
 137     };
 138
 139   template<typename _Tp>
 140     struct iterator_traits<_Tp*>
 141     {
 142       typedef random_access_iterator_tag iterator_category;
 143       typedef _Tp                         value_type;
 144       typedef ptrdiff_t                   difference_type;
 145       typedef _Tp*                        pointer;
 146       typedef _Tp&                        reference;
 147     };
 148
 149   template<typename _Tp>
 150     struct iterator_traits<const _Tp*>
 151     {
 152       typedef random_access_iterator_tag iterator_category;
 153       typedef _Tp                         value_type;
 154       typedef ptrdiff_t                   difference_type;
 155       typedef const _Tp*                  pointer;
 156       typedef const _Tp&                  reference;
 157     };
 158
 159   /**
 160    *  This function is not a part of the C++ standard but is syntactic
 161    *  sugar for internal library use only.
 162   */
 163   template<typename _Iter>
 164     inline typename iterator_traits<_Iter>::iterator_category
 165     __iterator_category(const _Iter&)
 166     { return typename iterator_traits<_Iter>::iterator_category(); }
 167
 168   //@}
 169
 170 _GLIBCXX_END_NAMESPACE
 171
 172 #endif /* _STL_ITERATOR_BASE_TYPES_H */
 173