libstdc++
exception_ptr.h
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1 // Exception Handling support header (exception_ptr class) for -*- C++ -*-
2 
3 // Copyright (C) 2008-2021 Free Software Foundation, Inc.
4 //
5 // This file is part of GCC.
6 //
7 // GCC is free software; you can redistribute it and/or modify
8 // it under the terms of the GNU General Public License as published by
9 // the Free Software Foundation; either version 3, or (at your option)
10 // any later version.
11 //
12 // GCC 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 /** @file bits/exception_ptr.h
27  * This is an internal header file, included by other library headers.
28  * Do not attempt to use it directly. @headername{exception}
29  */
30 
31 #ifndef _EXCEPTION_PTR_H
32 #define _EXCEPTION_PTR_H
33 
34 #pragma GCC visibility push(default)
35 
36 #include <bits/c++config.h>
37 #include <bits/exception_defines.h>
39 #include <typeinfo>
40 #include <new>
41 
42 #ifdef _GLIBCXX_EH_PTR_RELOPS_COMPAT
43 # define _GLIBCXX_EH_PTR_USED __attribute__((__used__))
44 #else
45 # define _GLIBCXX_EH_PTR_USED
46 #endif
47 
48 extern "C++" {
49 
50 namespace std
51 {
52  class type_info;
53 
54  /**
55  * @addtogroup exceptions
56  * @{
57  */
58 
59  namespace __exception_ptr
60  {
61  class exception_ptr;
62  }
63 
64  using __exception_ptr::exception_ptr;
65 
66  /** Obtain an exception_ptr to the currently handled exception. If there
67  * is none, or the currently handled exception is foreign, return the null
68  * value.
69  */
70  exception_ptr current_exception() _GLIBCXX_USE_NOEXCEPT;
71 
72  template<typename _Ex>
73  exception_ptr make_exception_ptr(_Ex) _GLIBCXX_USE_NOEXCEPT;
74 
75  /// Throw the object pointed to by the exception_ptr.
76  void rethrow_exception(exception_ptr) __attribute__ ((__noreturn__));
77 
78  namespace __exception_ptr
79  {
81 
82  /**
83  * @brief An opaque pointer to an arbitrary exception.
84  * @ingroup exceptions
85  */
87  {
88  void* _M_exception_object;
89 
90  explicit exception_ptr(void* __e) _GLIBCXX_USE_NOEXCEPT;
91 
92  void _M_addref() _GLIBCXX_USE_NOEXCEPT;
93  void _M_release() _GLIBCXX_USE_NOEXCEPT;
94 
95  void *_M_get() const _GLIBCXX_NOEXCEPT __attribute__ ((__pure__));
96 
97  friend exception_ptr std::current_exception() _GLIBCXX_USE_NOEXCEPT;
99  template<typename _Ex>
100  friend exception_ptr std::make_exception_ptr(_Ex) _GLIBCXX_USE_NOEXCEPT;
101 
102  public:
103  exception_ptr() _GLIBCXX_USE_NOEXCEPT;
104 
105  exception_ptr(const exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
106 
107 #if __cplusplus >= 201103L
108  exception_ptr(nullptr_t) noexcept
109  : _M_exception_object(nullptr)
110  { }
111 
112  exception_ptr(exception_ptr&& __o) noexcept
113  : _M_exception_object(__o._M_exception_object)
114  { __o._M_exception_object = nullptr; }
115 #endif
116 
117 #if (__cplusplus < 201103L) || defined (_GLIBCXX_EH_PTR_COMPAT)
118  typedef void (exception_ptr::*__safe_bool)();
119 
120  // For construction from nullptr or 0.
121  exception_ptr(__safe_bool) _GLIBCXX_USE_NOEXCEPT;
122 #endif
123 
124  exception_ptr&
125  operator=(const exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
126 
127 #if __cplusplus >= 201103L
128  exception_ptr&
129  operator=(exception_ptr&& __o) noexcept
130  {
131  exception_ptr(static_cast<exception_ptr&&>(__o)).swap(*this);
132  return *this;
133  }
134 #endif
135 
136  ~exception_ptr() _GLIBCXX_USE_NOEXCEPT;
137 
138  void
139  swap(exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
140 
141 #ifdef _GLIBCXX_EH_PTR_COMPAT
142  // Retained for compatibility with CXXABI_1.3.
143  void _M_safe_bool_dummy() _GLIBCXX_USE_NOEXCEPT
144  __attribute__ ((__const__));
145  bool operator!() const _GLIBCXX_USE_NOEXCEPT
146  __attribute__ ((__pure__));
147  operator __safe_bool() const _GLIBCXX_USE_NOEXCEPT;
148 #endif
149 
150 #if __cplusplus >= 201103L
151  explicit operator bool() const noexcept
152  { return _M_exception_object; }
153 #endif
154 
155 #if __cpp_impl_three_way_comparison >= 201907L \
156  && ! defined _GLIBCXX_EH_PTR_RELOPS_COMPAT
157  friend bool
158  operator==(const exception_ptr&, const exception_ptr&) noexcept = default;
159 #else
160  friend _GLIBCXX_EH_PTR_USED bool
161  operator==(const exception_ptr& __x, const exception_ptr& __y)
162  _GLIBCXX_USE_NOEXCEPT
163  { return __x._M_exception_object == __y._M_exception_object; }
164 
165  friend _GLIBCXX_EH_PTR_USED bool
166  operator!=(const exception_ptr& __x, const exception_ptr& __y)
167  _GLIBCXX_USE_NOEXCEPT
168  { return __x._M_exception_object != __y._M_exception_object; }
169 #endif
170 
171  const class std::type_info*
172  __cxa_exception_type() const _GLIBCXX_USE_NOEXCEPT
173  __attribute__ ((__pure__));
174  };
175 
176  _GLIBCXX_EH_PTR_USED
177  inline
178  exception_ptr::exception_ptr() _GLIBCXX_NOEXCEPT
179  : _M_exception_object(0)
180  { }
181 
182  _GLIBCXX_EH_PTR_USED
183  inline
184  exception_ptr::exception_ptr(const exception_ptr& __other) _GLIBCXX_NOEXCEPT
185  : _M_exception_object(__other._M_exception_object)
186  {
187  if (_M_exception_object)
188  _M_addref();
189  }
190 
191  _GLIBCXX_EH_PTR_USED
192  inline
193  exception_ptr::~exception_ptr() _GLIBCXX_USE_NOEXCEPT
194  {
195  if (_M_exception_object)
196  _M_release();
197  }
198 
199  _GLIBCXX_EH_PTR_USED
200  inline exception_ptr&
201  exception_ptr::operator=(const exception_ptr& __other) _GLIBCXX_USE_NOEXCEPT
202  {
203  exception_ptr(__other).swap(*this);
204  return *this;
205  }
206 
207  _GLIBCXX_EH_PTR_USED
208  inline void
209  exception_ptr::swap(exception_ptr &__other) _GLIBCXX_USE_NOEXCEPT
210  {
211  void *__tmp = _M_exception_object;
212  _M_exception_object = __other._M_exception_object;
213  __other._M_exception_object = __tmp;
214  }
215 
216  /// @relates exception_ptr
217  inline void
218  swap(exception_ptr& __lhs, exception_ptr& __rhs)
219  { __lhs.swap(__rhs); }
220 
221  /// @cond undocumented
222  template<typename _Ex>
223  inline void
224  __dest_thunk(void* __x)
225  { static_cast<_Ex*>(__x)->~_Ex(); }
226  /// @endcond
227 
228  } // namespace __exception_ptr
229 
230  /// Obtain an exception_ptr pointing to a copy of the supplied object.
231  template<typename _Ex>
232  exception_ptr
233  make_exception_ptr(_Ex __ex) _GLIBCXX_USE_NOEXCEPT
234  {
235 #if __cpp_exceptions && __cpp_rtti && !_GLIBCXX_HAVE_CDTOR_CALLABI
236  void* __e = __cxxabiv1::__cxa_allocate_exception(sizeof(_Ex));
237  (void) __cxxabiv1::__cxa_init_primary_exception(
238  __e, const_cast<std::type_info*>(&typeid(__ex)),
239  __exception_ptr::__dest_thunk<_Ex>);
240  try
241  {
242  ::new (__e) _Ex(__ex);
243  return exception_ptr(__e);
244  }
245  catch(...)
246  {
247  __cxxabiv1::__cxa_free_exception(__e);
248  return current_exception();
249  }
250 #elif __cpp_exceptions
251  try
252  {
253  throw __ex;
254  }
255  catch(...)
256  {
257  return current_exception();
258  }
259 #else // no RTTI and no exceptions
260  return exception_ptr();
261 #endif
262  }
263 
264 #undef _GLIBCXX_EH_PTR_USED
265 
266  /// @} group exceptions
267 } // namespace std
268 
269 } // extern "C++"
270 
271 #pragma GCC visibility pop
272 
273 #endif
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:422
exception_ptr current_exception() noexcept
exception_ptr make_exception_ptr(_Ex) noexcept
Obtain an exception_ptr pointing to a copy of the supplied object.
void rethrow_exception(exception_ptr)
Throw the object pointed to by the exception_ptr.
ISO C++ entities toplevel namespace is std.
Part of RTTI.
Definition: typeinfo:89
An opaque pointer to an arbitrary exception.
Definition: exception_ptr.h:87