11.2.0/debug/safe_base.h

// Safe sequence/iterator base implementation  -*- C++ -*-

// Copyright (C) 2003-2021 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file debug/safe_base.h
 *  This file is a GNU debug extension to the Standard C++ Library.
 */

#ifndef _GLIBCXX_DEBUG_SAFE_BASE_H
#define _GLIBCXX_DEBUG_SAFE_BASE_H 1

#include <ext/concurrence.h>

namespace __gnu_debug
{
  class _Safe_sequence_base;

  /** \brief Basic functionality for a @a safe iterator.
   *
   *  The %_Safe_iterator_base base class implements the functionality
   *  of a safe iterator that is not specific to a particular iterator
   *  type. It contains a pointer back to the sequence it references
   *  along with iterator version information and pointers to form a
   *  doubly-linked list of iterators referenced by the container.
   *
   *  This class must not perform any operations that can throw an
   *  exception, or the exception guarantees of derived iterators will
   *  be broken.
   */
  class _Safe_iterator_base
  {
    friend class _Safe_sequence_base;

  public:
    /** The sequence this iterator references; may be NULL to indicate
        a singular iterator. */
    _Safe_sequence_base*        _M_sequence;

    /** The version number of this iterator. The sentinel value 0 is
     *  used to indicate an invalidated iterator (i.e., one that is
     *  singular because of an operation on the container). This
     *  version number must equal the version number in the sequence
     *  referenced by _M_sequence for the iterator to be
     *  non-singular.
     */
    unsigned int                _M_version;

    /** Pointer to the previous iterator in the sequence's list of
        iterators. Only valid when _M_sequence != NULL. */
    _Safe_iterator_base*        _M_prior;

    /** Pointer to the next iterator in the sequence's list of
        iterators. Only valid when _M_sequence != NULL. */
    _Safe_iterator_base*        _M_next;

  protected:
    /** Initializes the iterator and makes it singular. */
    _Safe_iterator_base()
    : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
    { }

    /** Initialize the iterator to reference the sequence pointed to
     *  by @p __seq. @p __constant is true when we are initializing a
     *  constant iterator, and false if it is a mutable iterator. Note
     *  that @p __seq may be NULL, in which case the iterator will be
     *  singular. Otherwise, the iterator will reference @p __seq and
     *  be nonsingular.
     */
    _Safe_iterator_base(const _Safe_sequence_base* __seq, bool __constant)
    : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
    { this->_M_attach(const_cast<_Safe_sequence_base*>(__seq), __constant); }

    /** Initializes the iterator to reference the same sequence that
        @p __x does. @p __constant is true if this is a constant
        iterator, and false if it is mutable. */
    _Safe_iterator_base(const _Safe_iterator_base& __x, bool __constant)
    : _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
    { this->_M_attach(__x._M_sequence, __constant); }

    ~_Safe_iterator_base() { this->_M_detach(); }

    /** For use in _Safe_iterator. */
    __gnu_cxx::__mutex&
    _M_get_mutex() throw ();

    /** Attaches this iterator to the given sequence, detaching it
     *  from whatever sequence it was attached to originally. If the
     *  new sequence is the NULL pointer, the iterator is left
     *  unattached.
     */
    void
    _M_attach(_Safe_sequence_base* __seq, bool __constant);

    /** Likewise, but not thread-safe. */
    void
    _M_attach_single(_Safe_sequence_base* __seq, bool __constant) throw ();

    /** Detach the iterator for whatever sequence it is attached to,
     *  if any.
    */
    void
    _M_detach();

  public:
    /** Likewise, but not thread-safe. */
    void
    _M_detach_single() throw ();

    /** Determines if we are attached to the given sequence. */
    bool
    _M_attached_to(const _Safe_sequence_base* __seq) const
    { return _M_sequence == __seq; }

    /** Is this iterator singular? */
    _GLIBCXX_PURE bool
    _M_singular() const throw ();

    /** Can we compare this iterator to the given iterator @p __x?
        Returns true if both iterators are nonsingular and reference
        the same sequence. */
    _GLIBCXX_PURE bool
    _M_can_compare(const _Safe_iterator_base& __x) const throw ();

    /** Invalidate the iterator, making it singular. */
    void
    _M_invalidate()
    { _M_version = 0; }

    /** Reset all member variables */
    void
    _M_reset() throw ();

    /** Unlink itself */
    void
    _M_unlink() throw ()
    {
      if (_M_prior)
        _M_prior->_M_next = _M_next;
      if (_M_next)
        _M_next->_M_prior = _M_prior;
    }
  };

  /** Iterators that derive from _Safe_iterator_base can be determined singular
   *  or non-singular.
   **/
  inline bool
  __check_singular_aux(const _Safe_iterator_base* __x)
  { return __x->_M_singular(); }

  /**
   * @brief Base class that supports tracking of iterators that
   * reference a sequence.
   *
   * The %_Safe_sequence_base class provides basic support for
   * tracking iterators into a sequence. Sequences that track
   * iterators must derived from %_Safe_sequence_base publicly, so
   * that safe iterators (which inherit _Safe_iterator_base) can
   * attach to them. This class contains two linked lists of
   * iterators, one for constant iterators and one for mutable
   * iterators, and a version number that allows very fast
   * invalidation of all iterators that reference the container.
   *
   * This class must ensure that no operation on it may throw an
   * exception, otherwise @a safe sequences may fail to provide the
   * exception-safety guarantees required by the C++ standard.
   */
  class _Safe_sequence_base
  {
    friend class _Safe_iterator_base;

  public:
    /// The list of mutable iterators that reference this container
    _Safe_iterator_base* _M_iterators;

    /// The list of constant iterators that reference this container
    _Safe_iterator_base* _M_const_iterators;

    /// The container version number. This number may never be 0.
    mutable unsigned int _M_version;

  protected:
    // Initialize with a version number of 1 and no iterators
    _Safe_sequence_base() _GLIBCXX_NOEXCEPT
    : _M_iterators(0), _M_const_iterators(0), _M_version(1)
    { }

#if __cplusplus >= 201103L
    _Safe_sequence_base(const _Safe_sequence_base&) noexcept
    : _Safe_sequence_base() { }

    // Move constructor swap iterators.
    _Safe_sequence_base(_Safe_sequence_base&& __seq) noexcept
    : _Safe_sequence_base()
    { _M_swap(__seq); }
#endif

    /** Notify all iterators that reference this sequence that the
        sequence is being destroyed. */
    ~_Safe_sequence_base()
    { this->_M_detach_all(); }

    /** Detach all iterators, leaving them singular. */
    void
    _M_detach_all();

    /** Detach all singular iterators.
     *  @post for all iterators i attached to this sequence,
     *   i->_M_version == _M_version.
     */
    void
    _M_detach_singular();

    /** Revalidates all attached singular iterators.  This method may
     *  be used to validate iterators that were invalidated before
     *  (but for some reason, such as an exception, need to become
     *  valid again).
     */
    void
    _M_revalidate_singular();

    /** Swap this sequence with the given sequence. This operation
     *  also swaps ownership of the iterators, so that when the
     *  operation is complete all iterators that originally referenced
     *  one container now reference the other container.
     */
    void
    _M_swap(_Safe_sequence_base& __x) _GLIBCXX_USE_NOEXCEPT;

    /** For use in _Safe_sequence. */
    __gnu_cxx::__mutex&
    _M_get_mutex() throw ();

    /** Invalidates all iterators. */
    void
    _M_invalidate_all() const
    { if (++_M_version == 0) _M_version = 1; }

  private:
    /** Attach an iterator to this sequence. */
    void
    _M_attach(_Safe_iterator_base* __it, bool __constant);

    /** Likewise but not thread safe. */
    void
    _M_attach_single(_Safe_iterator_base* __it, bool __constant) throw ();

    /** Detach an iterator from this sequence */
    void
    _M_detach(_Safe_iterator_base* __it);

    /** Likewise but not thread safe. */
    void
    _M_detach_single(_Safe_iterator_base* __it) throw ();
  };
} // namespace __gnu_debug

#endif
Revision:	1166
Committed:	Tue Oct 26 14:22:36 2021 UTC (4 years ago) by rossy
Content type:	text/x-chdr
File size:	9279 byte(s)
Log Message:	Daodan: Replace MinGW build env with an up-to-date MSYS2 env
#	Content
1	// Safe sequence/iterator base implementation -- C++ --
2
3	// Copyright (C) 2003-2021 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_base.h
26	* This file is a GNU debug extension to the Standard C++ Library.
27	*/
28
29	#ifndef _GLIBCXX_DEBUG_SAFE_BASE_H
30	#define _GLIBCXX_DEBUG_SAFE_BASE_H 1
31
32	#include <ext/concurrence.h>
33
34	namespace __gnu_debug
35	{
36	class _Safe_sequence_base;
37
38	/** \brief Basic functionality for a @a safe iterator.
39	*
40	* The %_Safe_iterator_base base class implements the functionality
41	* of a safe iterator that is not specific to a particular iterator
42	* type. It contains a pointer back to the sequence it references
43	* along with iterator version information and pointers to form a
44	* doubly-linked list of 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_iterator_base
51	{
52	friend class _Safe_sequence_base;
53
54	public:
55	/** The sequence this iterator references; may be NULL to indicate
56	a singular iterator. */
57	_Safe_sequence_base* _M_sequence;
58
59	/** The version number of this iterator. The sentinel value 0 is
60	* used to indicate an invalidated iterator (i.e., one that is
61	* singular because of an operation on the container). This
62	* version number must equal the version number in the sequence
63	* referenced by _M_sequence for the iterator to be
64	* non-singular.
65	*/
66	unsigned int _M_version;
67
68	/** Pointer to the previous iterator in the sequence's list of
69	iterators. Only valid when _M_sequence != NULL. */
70	_Safe_iterator_base* _M_prior;
71
72	/** Pointer to the next iterator in the sequence's list of
73	iterators. Only valid when _M_sequence != NULL. */
74	_Safe_iterator_base* _M_next;
75
76	protected:
77	/** Initializes the iterator and makes it singular. */
78	_Safe_iterator_base()
79	: _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
80	{ }
81
82	/** Initialize the iterator to reference the sequence pointed to
83	* by @p __seq. @p __constant is true when we are initializing a
84	* constant iterator, and false if it is a mutable iterator. Note
85	* that @p __seq may be NULL, in which case the iterator will be
86	* singular. Otherwise, the iterator will reference @p __seq and
87	* be nonsingular.
88	*/
89	_Safe_iterator_base(const _Safe_sequence_base* __seq, bool __constant)
90	: _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
91	{ this->_M_attach(const_cast<_Safe_sequence_base*>(__seq), __constant); }
92
93	/** Initializes the iterator to reference the same sequence that
94	@p __x does. @p __constant is true if this is a constant
95	iterator, and false if it is mutable. */
96	_Safe_iterator_base(const _Safe_iterator_base& __x, bool __constant)
97	: _M_sequence(0), _M_version(0), _M_prior(0), _M_next(0)
98	{ this->_M_attach(__x._M_sequence, __constant); }
99
100	~_Safe_iterator_base() { this->_M_detach(); }
101
102	/** For use in _Safe_iterator. */
103	__gnu_cxx::__mutex&
104	_M_get_mutex() throw ();
105
106	/** Attaches this iterator to the given sequence, detaching it
107	* from whatever sequence it was attached to originally. If the
108	* new sequence is the NULL pointer, the iterator is left
109	* unattached.
110	*/
111	void
112	_M_attach(_Safe_sequence_base* __seq, bool __constant);
113
114	/** Likewise, but not thread-safe. */
115	void
116	_M_attach_single(_Safe_sequence_base* __seq, bool __constant) throw ();
117
118	/** Detach the iterator for whatever sequence it is attached to,
119	* if any.
120	*/
121	void
122	_M_detach();
123
124	public:
125	/** Likewise, but not thread-safe. */
126	void
127	_M_detach_single() throw ();
128
129	/** Determines if we are attached to the given sequence. */
130	bool
131	_M_attached_to(const _Safe_sequence_base* __seq) const
132	{ return _M_sequence == __seq; }
133
134	/** Is this iterator singular? */
135	_GLIBCXX_PURE bool
136	_M_singular() const throw ();
137
138	/** Can we compare this iterator to the given iterator @p __x?
139	Returns true if both iterators are nonsingular and reference
140	the same sequence. */
141	_GLIBCXX_PURE bool
142	_M_can_compare(const _Safe_iterator_base& __x) const throw ();
143
144	/** Invalidate the iterator, making it singular. */
145	void
146	_M_invalidate()
147	{ _M_version = 0; }
148
149	/** Reset all member variables */
150	void
151	_M_reset() throw ();
152
153	/** Unlink itself */
154	void
155	_M_unlink() throw ()
156	{
157	if (_M_prior)
158	_M_prior->_M_next = _M_next;
159	if (_M_next)
160	_M_next->_M_prior = _M_prior;
161	}
162	};
163
164	/** Iterators that derive from _Safe_iterator_base can be determined singular
165	* or non-singular.
166	**/
167	inline bool
168	__check_singular_aux(const _Safe_iterator_base* __x)
169	{ return __x->_M_singular(); }
170
171	/**
172	* @brief Base class that supports tracking of iterators that
173	* reference a sequence.
174	*
175	* The %_Safe_sequence_base class provides basic support for
176	* tracking iterators into a sequence. Sequences that track
177	* iterators must derived from %_Safe_sequence_base publicly, so
178	* that safe iterators (which inherit _Safe_iterator_base) can
179	* attach to them. This class contains two linked lists of
180	* iterators, one for constant iterators and one for mutable
181	* iterators, and a version number that allows very fast
182	* invalidation of all iterators that reference the container.
183	*
184	* This class must ensure that no operation on it may throw an
185	* exception, otherwise @a safe sequences may fail to provide the
186	* exception-safety guarantees required by the C++ standard.
187	*/
188	class _Safe_sequence_base
189	{
190	friend class _Safe_iterator_base;
191
192	public:
193	/// The list of mutable iterators that reference this container
194	_Safe_iterator_base* _M_iterators;
195
196	/// The list of constant iterators that reference this container
197	_Safe_iterator_base* _M_const_iterators;
198
199	/// The container version number. This number may never be 0.
200	mutable unsigned int _M_version;
201
202	protected:
203	// Initialize with a version number of 1 and no iterators
204	_Safe_sequence_base() _GLIBCXX_NOEXCEPT
205	: _M_iterators(0), _M_const_iterators(0), _M_version(1)
206	{ }
207
208	#if __cplusplus >= 201103L
209	_Safe_sequence_base(const _Safe_sequence_base&) noexcept
210	: _Safe_sequence_base() { }
211
212	// Move constructor swap iterators.
213	_Safe_sequence_base(_Safe_sequence_base&& __seq) noexcept
214	: _Safe_sequence_base()
215	{ _M_swap(__seq); }
216	#endif
217
218	/** Notify all iterators that reference this sequence that the
219	sequence is being destroyed. */
220	~_Safe_sequence_base()
221	{ this->_M_detach_all(); }
222
223	/** Detach all iterators, leaving them singular. */
224	void
225	_M_detach_all();
226
227	/** Detach all singular iterators.
228	* @post for all iterators i attached to this sequence,
229	* i->_M_version == _M_version.
230	*/
231	void
232	_M_detach_singular();
233
234	/** Revalidates all attached singular iterators. This method may
235	* be used to validate iterators that were invalidated before
236	* (but for some reason, such as an exception, need to become
237	* valid again).
238	*/
239	void
240	_M_revalidate_singular();
241
242	/** Swap this sequence with the given sequence. This operation
243	* also swaps ownership of the iterators, so that when the
244	* operation is complete all iterators that originally referenced
245	* one container now reference the other container.
246	*/
247	void
248	_M_swap(_Safe_sequence_base& __x) _GLIBCXX_USE_NOEXCEPT;
249
250	/** For use in _Safe_sequence. */
251	__gnu_cxx::__mutex&
252	_M_get_mutex() throw ();
253
254	/** Invalidates all iterators. */
255	void
256	_M_invalidate_all() const
257	{ if (++_M_version == 0) _M_version = 1; }
258
259	private:
260	/** Attach an iterator to this sequence. */
261	void
262	_M_attach(_Safe_iterator_base* __it, bool __constant);
263
264	/** Likewise but not thread safe. */
265	void
266	_M_attach_single(_Safe_iterator_base* __it, bool __constant) throw ();
267
268	/** Detach an iterator from this sequence */
269	void
270	_M_detach(_Safe_iterator_base* __it);
271
272	/** Likewise but not thread safe. */
273	void
274	_M_detach_single(_Safe_iterator_base* __it) throw ();
275	};
276	} // namespace __gnu_debug
277
278	#endif