libstdc++
nested_exception.h
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1 // Nested Exception support header (nested_exception class) for -*- C++ -*-
2 
3 // Copyright (C) 2009-2016 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 bits/nested_exception.h
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{exception}
28  */
29 
30 #ifndef _GLIBCXX_NESTED_EXCEPTION_H
31 #define _GLIBCXX_NESTED_EXCEPTION_H 1
32 
33 #pragma GCC visibility push(default)
34 
35 #if __cplusplus < 201103L
36 # include <bits/c++0x_warning.h>
37 #else
38 
39 #include <bits/c++config.h>
40 #include <bits/move.h>
41 
42 #if ATOMIC_INT_LOCK_FREE < 2
43 # error This platform does not support exception propagation.
44 #endif
45 
46 extern "C++" {
47 
48 namespace std
49 {
50  /**
51  * @addtogroup exceptions
52  * @{
53  */
54 
55  /// Exception class with exception_ptr data member.
57  {
58  exception_ptr _M_ptr;
59 
60  public:
61  nested_exception() noexcept : _M_ptr(current_exception()) { }
62 
63  nested_exception(const nested_exception&) noexcept = default;
64 
65  nested_exception& operator=(const nested_exception&) noexcept = default;
66 
67  virtual ~nested_exception() noexcept;
68 
69  [[noreturn]]
70  void
71  rethrow_nested() const
72  {
73  if (_M_ptr)
74  rethrow_exception(_M_ptr);
76  }
77 
78  exception_ptr
79  nested_ptr() const noexcept
80  { return _M_ptr; }
81  };
82 
83  template<typename _Except>
84  struct _Nested_exception : public _Except, public nested_exception
85  {
86  explicit _Nested_exception(const _Except& __ex)
87  : _Except(__ex)
88  { }
89 
90  explicit _Nested_exception(_Except&& __ex)
91  : _Except(static_cast<_Except&&>(__ex))
92  { }
93  };
94 
95  template<typename _Tp,
96  bool __with_nested = !__is_base_of(nested_exception, _Tp)>
97  struct _Throw_with_nested_impl
98  {
99  template<typename _Up>
100  static void _S_throw(_Up&& __t)
101  { throw _Nested_exception<_Tp>{static_cast<_Up&&>(__t)}; }
102  };
103 
104  template<typename _Tp>
105  struct _Throw_with_nested_impl<_Tp, false>
106  {
107  template<typename _Up>
108  static void _S_throw(_Up&& __t)
109  { throw static_cast<_Up&&>(__t); }
110  };
111 
112  template<typename _Tp, bool = __is_class(_Tp) && !__is_final(_Tp)>
113  struct _Throw_with_nested_helper : _Throw_with_nested_impl<_Tp>
114  { };
115 
116  template<typename _Tp>
117  struct _Throw_with_nested_helper<_Tp, false>
118  : _Throw_with_nested_impl<_Tp, false>
119  { };
120 
121  template<typename _Tp>
122  struct _Throw_with_nested_helper<_Tp&, false>
123  : _Throw_with_nested_helper<_Tp>
124  { };
125 
126  template<typename _Tp>
127  struct _Throw_with_nested_helper<_Tp&&, false>
128  : _Throw_with_nested_helper<_Tp>
129  { };
130 
131  /// If @p __t is derived from nested_exception, throws @p __t.
132  /// Else, throws an implementation-defined object derived from both.
133  template<typename _Tp>
134  [[noreturn]]
135  inline void
136  throw_with_nested(_Tp&& __t)
137  {
138  _Throw_with_nested_helper<_Tp>::_S_throw(static_cast<_Tp&&>(__t));
139  }
140 
141  template<typename _Tp, bool = __is_polymorphic(_Tp)>
142  struct _Rethrow_if_nested_impl
143  {
144  static void _S_rethrow(const _Tp& __t)
145  {
146  if (auto __tp =
147  dynamic_cast<const nested_exception*>(std::__addressof(__t)))
148  __tp->rethrow_nested();
149  }
150  };
151 
152  template<typename _Tp>
153  struct _Rethrow_if_nested_impl<_Tp, false>
154  {
155  static void _S_rethrow(const _Tp&) { }
156  };
157 
158  /// If @p __ex is derived from nested_exception, @p __ex.rethrow_nested().
159  template<typename _Ex>
160  inline void
161  rethrow_if_nested(const _Ex& __ex)
162  {
163  _Rethrow_if_nested_impl<_Ex>::_S_rethrow(__ex);
164  }
165 
166  // @} group exceptions
167 } // namespace std
168 
169 } // extern "C++"
170 
171 #endif // C++11
172 
173 #pragma GCC visibility pop
174 
175 #endif // _GLIBCXX_NESTED_EXCEPTION_H
exception_ptr current_exception() noexcept
void throw_with_nested(_Tp &&__t)
If __t is derived from nested_exception, throws __t. Else, throws an implementation-defined object de...
void rethrow_if_nested(const _Ex &__ex)
If __ex is derived from nested_exception, __ex.rethrow_nested().
_Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:47
void rethrow_exception(exception_ptr) __attribute__((__noreturn__))
Throw the object pointed to by the exception_ptr.
void terminate() noexcept __attribute__((__noreturn__))
Exception class with exception_ptr data member.