1// Types used in iterator implementation -*- C++ -*-
2
3// Copyright (C) 2001, 2002, 2004, 2005 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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 _ITERATOR_BASE_TYPES_H
65#define _ITERATOR_BASE_TYPES_H 1
66
67#pragma GCC system_header
68
69_GLIBCXX_BEGIN_NAMESPACE(std)
70
71  //@{
72  /**
73   *  @defgroup iterator_tags Iterator Tags
74   *  These are empty types, used to distinguish different iterators.  The
75   *  distinction is not made by what they contain, but simply by what they
76   *  are.  Different underlying algorithms can then be used based on the
77   *  different operations supporetd by different iterator types.
78  */
79  ///  Marking input iterators.
80  struct input_iterator_tag {};
81  ///  Marking output iterators.
82  struct output_iterator_tag {};
83  /// Forward iterators support a superset of input iterator operations.
84  struct forward_iterator_tag : public input_iterator_tag {};
85  /// Bidirectional iterators support a superset of forward iterator
86  /// operations.
87  struct bidirectional_iterator_tag : public forward_iterator_tag {};
88  /// Random-access iterators support a superset of bidirectional iterator
89  /// operations.
90  struct random_access_iterator_tag : public bidirectional_iterator_tag {};
91  //@}
92
93
94  /**
95   *  @brief  Common %iterator class.
96   *
97   *  This class does nothing but define nested typedefs.  %Iterator classes
98   *  can inherit from this class to save some work.  The typedefs are then
99   *  used in specializations and overloading.
100   *
101   *  In particular, there are no default implementations of requirements
102   *  such as @c operator++ and the like.  (How could there be?)
103  */
104  template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
105           typename _Pointer = _Tp*, typename _Reference = _Tp&>
106    struct iterator
107    {
108      /// One of the @link iterator_tags tag types@endlink.
109      typedef _Category  iterator_category;
110      /// The type "pointed to" by the iterator.
111      typedef _Tp        value_type;
112      /// Distance between iterators is represented as this type.
113      typedef _Distance  difference_type;
114      /// This type represents a pointer-to-value_type.
115      typedef _Pointer   pointer;
116      /// This type represents a reference-to-value_type.
117      typedef _Reference reference;
118    };
119
120  /**
121   *  This class does nothing but define nested typedefs.  The general
122   *  version simply "forwards" the nested typedefs from the Iterator
123   *  argument.  Specialized versions for pointers and pointers-to-const
124   *  provide tighter, more correct semantics.
125  */
126  template<typename _Iterator>
127    struct iterator_traits
128    {
129      typedef typename _Iterator::iterator_category iterator_category;
130      typedef typename _Iterator::value_type        value_type;
131      typedef typename _Iterator::difference_type   difference_type;
132      typedef typename _Iterator::pointer           pointer;
133      typedef typename _Iterator::reference         reference;
134    };
135
136  template<typename _Tp>
137    struct iterator_traits<_Tp*>
138    {
139      typedef random_access_iterator_tag iterator_category;
140      typedef _Tp                         value_type;
141      typedef ptrdiff_t                   difference_type;
142      typedef _Tp*                        pointer;
143      typedef _Tp&                        reference;
144    };
145
146  template<typename _Tp>
147    struct iterator_traits<const _Tp*>
148    {
149      typedef random_access_iterator_tag iterator_category;
150      typedef _Tp                         value_type;
151      typedef ptrdiff_t                   difference_type;
152      typedef const _Tp*                  pointer;
153      typedef const _Tp&                  reference;
154    };
155
156  /**
157   *  @if maint
158   *  This function is not a part of the C++ standard but is syntactic
159   *  sugar for internal library use only.
160   *  @endif
161  */
162  template<typename _Iter>
163    inline typename iterator_traits<_Iter>::iterator_category
164    __iterator_category(const _Iter&)
165    { return typename iterator_traits<_Iter>::iterator_category(); }
166
167_GLIBCXX_END_NAMESPACE
168
169#endif /* _ITERATOR_BASE_TYPES_H */
170
171