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

   1 // Types used in iterator implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 2, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /*
  31  *
  32  * Copyright (c) 1994
  33  * Hewlett-Packard Company
  34  *
  35  * Permission to use, copy, modify, distribute and sell this software
  36  * and its documentation for any purpose is hereby granted without fee,
  37  * provided that the above copyright notice appear in all copies and
  38  * that both that copyright notice and this permission notice appear
  39  * in supporting documentation.  Hewlett-Packard Company makes no
  40  * representations about the suitability of this software for any
  41  * purpose.  It is provided "as is" without express or implied warranty.
  42  *
  43  *
  44  * Copyright (c) 1996-1998
  45  * Silicon Graphics Computer Systems, Inc.
  46  *
  47  * Permission to use, copy, modify, distribute and sell this software
  48  * and its documentation for any purpose is hereby granted without fee,
  49  * provided that the above copyright notice appear in all copies and
  50  * that both that copyright notice and this permission notice appear
  51  * in supporting documentation.  Silicon Graphics makes no
  52  * representations about the suitability of this software for any
  53  * purpose.  It is provided "as is" without express or implied warranty.
  54  */
  55
  56 /** @file stl_iterator_base_types.h
  57  *  This is an internal header file, included by other library headers.
  58  *  You should not attempt to use it directly.
  59  *
  60  *  This file contains all of the general iterator-related utility types,
  61  *  such as iterator_traits and struct iterator.
  62  */
  63
  64 #ifndef __GLIBCPP_INTERNAL_ITERATOR_BASE_TYPES_H
  65 #define __GLIBCPP_INTERNAL_ITERATOR_BASE_TYPES_H
  66
  67 #pragma GCC system_header
  68
  69 namespace std
  70 {
  71   /** @{
  72    *  @defgroup iterator_tags Iterator Tags
  73    *  These are empty types, used to distinguish different iterators.  The
  74    *  distinction is not made by what they contain, but simply by what they
  75    *  are.  Different underlying algorithms can then be used based on the
  76    *  different operations supporetd by different iterator types.
  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 operations.
  85   struct bidirectional_iterator_tag : public forward_iterator_tag {};
  86   /// Random-access iterators support a superset of bidirectional iterator operations.
  87   struct random_access_iterator_tag : public bidirectional_iterator_tag {};
  88   //@}
  89
  90
  91   /**
  92    *  @brief  Common %iterator class.
  93    *
  94    *  This class does nothing but define nested typedefs.  %Iterator classes
  95    *  can inherit from this class to save some work.  The typedefs are then
  96    *  used in specializations and overloading.
  97    *
  98    *  In particular, there are no default implementations of requirements
  99    *  such as @c operator++ and the like.  (How could there be?)
 100   */
 101   template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
 102            typename _Pointer = _Tp*, typename _Reference = _Tp&>
 103     struct iterator
 104     {
 105       /// One of the @link iterator_tags tag types@endlink.
 106       typedef _Category  iterator_category;
 107       /// The type "pointed to" by the iterator.
 108       typedef _Tp        value_type;
 109       /// Distance between iterators is represented as this type.
 110       typedef _Distance  difference_type;
 111       /// This type represents a pointer-to-value_type.
 112       typedef _Pointer   pointer;
 113       /// This type represents a reference-to-value_type.
 114       typedef _Reference reference;
 115     };
 116
 117   /**
 118    *  This class does nothing but define nested typedefs.  The general
 119    *  version simply "forwards" the nested typedefs from the Iterator
 120    *  argument.  Specialized versions for pointers and pointers-to-const
 121    *  provide tighter, more correct semantics.
 122   */
 123   template<typename _Iterator>
 124     struct iterator_traits {
 125       typedef typename _Iterator::iterator_category iterator_category;
 126       typedef typename _Iterator::value_type        value_type;
 127       typedef typename _Iterator::difference_type   difference_type;
 128       typedef typename _Iterator::pointer           pointer;
 129       typedef typename _Iterator::reference         reference;
 130     };
 131
 132   template<typename _Tp>
 133     struct iterator_traits<_Tp*> {
 134       typedef random_access_iterator_tag iterator_category;
 135       typedef _Tp                         value_type;
 136       typedef ptrdiff_t                   difference_type;
 137       typedef _Tp*                        pointer;
 138       typedef _Tp&                        reference;
 139     };
 140
 141   template<typename _Tp>
 142     struct iterator_traits<const _Tp*> {
 143       typedef random_access_iterator_tag iterator_category;
 144       typedef _Tp                         value_type;
 145       typedef ptrdiff_t                   difference_type;
 146       typedef const _Tp*                  pointer;
 147       typedef const _Tp&                  reference;
 148     };
 149
 150   /**
 151    *  @if maint
 152    *  This function is not a part of the C++ standard but is syntactic
 153    *  sugar for internal library use only.
 154    *  @endif
 155   */
 156   template<typename _Iter>
 157     inline typename iterator_traits<_Iter>::iterator_category
 158     __iterator_category(const _Iter&)
 159     { return typename iterator_traits<_Iter>::iterator_category(); }
 160
 161 } // namespace std
 162
 163 #endif /* __GLIBCPP_INTERNAL_ITERATOR_BASE_TYPES_H */
 164