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
169