1// Safe container/iterator base implementation  -*- C++ -*-
2
3// Copyright (C) 2011-2022 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 3, 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// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file debug/safe_unordered_base.h
26 *  This file is a GNU debug extension to the Standard C++ Library.
27 */
28
29#ifndef _GLIBCXX_DEBUG_SAFE_UNORDERED_BASE_H
30#define _GLIBCXX_DEBUG_SAFE_UNORDERED_BASE_H 1
31
32#include <debug/safe_base.h>
33
34namespace __gnu_debug
35{
36  class _Safe_unordered_container_base;
37
38  /** \brief Basic functionality for a @a safe iterator.
39   *
40   *  The %_Safe_local_iterator_base base class implements the functionality
41   *  of a safe local iterator that is not specific to a particular iterator
42   *  type. It contains a pointer back to the container it references
43   *  along with iterator version information and pointers to form a
44   *  doubly-linked list of local iterators referenced by the container.
45   *
46   *  This class must not perform any operations that can throw an
47   *  exception, or the exception guarantees of derived iterators will
48   *  be broken.
49   */
50  class _Safe_local_iterator_base : public _Safe_iterator_base
51  {
52  protected:
53    /** Initializes the iterator and makes it singular. */
54    _Safe_local_iterator_base()
55    { }
56
57    /** Initialize the iterator to reference the container pointed to
58     *  by @p __seq. @p __constant is true when we are initializing a
59     *  constant local iterator, and false if it is a mutable local iterator.
60     *  Note that @p __seq may be NULL, in which case the iterator will be
61     *  singular. Otherwise, the iterator will reference @p __seq and
62     *  be nonsingular.
63     */
64    _Safe_local_iterator_base(const _Safe_sequence_base* __seq, bool __constant)
65    { this->_M_attach(const_cast<_Safe_sequence_base*>(__seq), __constant); }
66
67    /** Initializes the iterator to reference the same container that
68	@p __x does. @p __constant is true if this is a constant
69	iterator, and false if it is mutable. */
70    _Safe_local_iterator_base(const _Safe_local_iterator_base& __x,
71			      bool __constant)
72    { this->_M_attach(__x._M_sequence, __constant); }
73
74    ~_Safe_local_iterator_base() { this->_M_detach(); }
75
76    _Safe_unordered_container_base*
77    _M_get_container() const noexcept;
78
79    /** Attaches this iterator to the given container, detaching it
80     *	from whatever container it was attached to originally. If the
81     *	new container is the NULL pointer, the iterator is left
82     *	unattached.
83     */
84    void
85    _M_attach(_Safe_sequence_base* __seq, bool __constant);
86
87    /** Likewise, but not thread-safe. */
88    void
89    _M_attach_single(_Safe_sequence_base* __seq, bool __constant) throw ();
90
91    /** Detach the iterator for whatever container it is attached to,
92     *	if any.
93    */
94    void
95    _M_detach();
96
97    /** Likewise, but not thread-safe. */
98    void
99    _M_detach_single() throw ();
100  };
101
102  /**
103   * @brief Base class that supports tracking of local iterators that
104   * reference an unordered container.
105   *
106   * The %_Safe_unordered_container_base class provides basic support for
107   * tracking iterators into an unordered container. Containers that track
108   * iterators must derived from %_Safe_unordered_container_base publicly, so
109   * that safe iterators (which inherit _Safe_iterator_base) can
110   * attach to them. This class contains four linked lists of
111   * iterators, one for constant iterators, one for mutable
112   * iterators, one for constant local iterators, one for mutable local
113   * iterators and a version number that allows very fast
114   * invalidation of all iterators that reference the container.
115   *
116   * This class must ensure that no operation on it may throw an
117   * exception, otherwise @a safe containers may fail to provide the
118   * exception-safety guarantees required by the C++ standard.
119   */
120  class _Safe_unordered_container_base : public _Safe_sequence_base
121  {
122    friend class _Safe_local_iterator_base;
123    typedef _Safe_sequence_base _Base;
124
125  public:
126    /// The list of mutable local iterators that reference this container
127    _Safe_iterator_base* _M_local_iterators;
128
129    /// The list of constant local iterators that reference this container
130    _Safe_iterator_base* _M_const_local_iterators;
131
132  protected:
133    // Initialize with a version number of 1 and no iterators
134    _Safe_unordered_container_base() noexcept
135    : _M_local_iterators(nullptr), _M_const_local_iterators(nullptr)
136    { }
137
138    // Copy constructor does not copy iterators.
139    _Safe_unordered_container_base(const _Safe_unordered_container_base&)
140    noexcept
141    : _Safe_unordered_container_base() { }
142
143    // When moved unordered containers iterators are swapped.
144    _Safe_unordered_container_base(_Safe_unordered_container_base&& __x)
145    noexcept
146    : _Safe_unordered_container_base()
147    { this->_M_swap(__x); }
148
149    /** Notify all iterators that reference this container that the
150	container is being destroyed. */
151    ~_Safe_unordered_container_base() noexcept
152    { this->_M_detach_all(); }
153
154    /** Detach all iterators, leaving them singular. */
155    void
156    _M_detach_all();
157
158    /** Swap this container with the given container. This operation
159     *  also swaps ownership of the iterators, so that when the
160     *  operation is complete all iterators that originally referenced
161     *  one container now reference the other container.
162     */
163    void
164    _M_swap(_Safe_unordered_container_base& __x) noexcept;
165
166  private:
167    /** Attach an iterator to this container. */
168    void
169    _M_attach_local(_Safe_iterator_base* __it, bool __constant);
170
171    /** Likewise but not thread safe. */
172    void
173    _M_attach_local_single(_Safe_iterator_base* __it, bool __constant) throw ();
174
175    /** Detach an iterator from this container */
176    void
177    _M_detach_local(_Safe_iterator_base* __it);
178
179    /** Likewise but not thread safe. */
180    void
181    _M_detach_local_single(_Safe_iterator_base* __it) throw ();
182  };
183} // namespace __gnu_debug
184
185#endif
186