libstdc++
nested_exception.h
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1 // Nested Exception support header (nested_exception class) for -*- C++ -*-
2 
3 // Copyright (C) 2009, 2010, 2011 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 #ifndef __GXX_EXPERIMENTAL_CXX0X__
36 # include <bits/c++0x_warning.h>
37 #else
38 
39 #include <bits/c++config.h>
40 
41 #if ATOMIC_INT_LOCK_FREE < 2
42 # error This platform does not support exception propagation.
43 #endif
44 
45 extern "C++" {
46 
47 namespace std
48 {
49  /**
50  * @addtogroup exceptions
51  * @{
52  */
53 
54  /// Exception class with exception_ptr data member.
56  {
57  exception_ptr _M_ptr;
58 
59  public:
60  nested_exception() noexcept : _M_ptr(current_exception()) { }
61 
62  nested_exception(const nested_exception&) = default;
63 
64  nested_exception& operator=(const nested_exception&) = default;
65 
66  virtual ~nested_exception() noexcept;
67 
68  void
69  rethrow_nested() const __attribute__ ((__noreturn__))
70  { rethrow_exception(_M_ptr); }
71 
72  exception_ptr
73  nested_ptr() const
74  { return _M_ptr; }
75  };
76 
77  template<typename _Except>
78  struct _Nested_exception : public _Except, public nested_exception
79  {
80  explicit _Nested_exception(_Except&& __ex)
81  : _Except(static_cast<_Except&&>(__ex))
82  { }
83  };
84 
85  template<typename _Ex>
86  struct __get_nested_helper
87  {
88  static const nested_exception*
89  _S_get(const _Ex& __ex)
90  { return dynamic_cast<const nested_exception*>(&__ex); }
91  };
92 
93  template<typename _Ex>
94  struct __get_nested_helper<_Ex*>
95  {
96  static const nested_exception*
97  _S_get(const _Ex* __ex)
98  { return dynamic_cast<const nested_exception*>(__ex); }
99  };
100 
101  template<typename _Ex>
102  inline const nested_exception*
103  __get_nested_exception(const _Ex& __ex)
104  { return __get_nested_helper<_Ex>::_S_get(__ex); }
105 
106  template<typename _Ex>
107  void
108  __throw_with_nested(_Ex&&, const nested_exception* = 0)
109  __attribute__ ((__noreturn__));
110 
111  template<typename _Ex>
112  void
113  __throw_with_nested(_Ex&&, ...) __attribute__ ((__noreturn__));
114 
115  // This function should never be called, but is needed to avoid a warning
116  // about ambiguous base classes when instantiating throw_with_nested<_Ex>()
117  // with a type that has an accessible nested_exception base.
118  template<typename _Ex>
119  inline void
120  __throw_with_nested(_Ex&& __ex, const nested_exception*)
121  { throw __ex; }
122 
123  template<typename _Ex>
124  inline void
125  __throw_with_nested(_Ex&& __ex, ...)
126  { throw _Nested_exception<_Ex>(static_cast<_Ex&&>(__ex)); }
127 
128  template<typename _Ex>
129  void
130  throw_with_nested(_Ex __ex) __attribute__ ((__noreturn__));
131 
132  /// If @p __ex is derived from nested_exception, @p __ex.
133  /// Else, an implementation-defined object derived from both.
134  template<typename _Ex>
135  inline void
137  {
138  if (__get_nested_exception(__ex))
139  throw __ex;
140  __throw_with_nested(static_cast<_Ex&&>(__ex), &__ex);
141  }
142 
143  /// If @p __ex is derived from nested_exception, @p __ex.rethrow_nested().
144  template<typename _Ex>
145  inline void
146  rethrow_if_nested(const _Ex& __ex)
147  {
148  if (const nested_exception* __nested = __get_nested_exception(__ex))
149  __nested->rethrow_nested();
150  }
151 
152  /// Overload, See N2619
153  inline void
155  { __ex.rethrow_nested(); }
156 
157  // @} group exceptions
158 } // namespace std
159 
160 } // extern "C++"
161 
162 #endif // __GXX_EXPERIMENTAL_CXX0X__
163 
164 #pragma GCC visibility pop
165 
166 #endif // _GLIBCXX_NESTED_EXCEPTION_H