libstdc++

nested_exception.h
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1 // Nested Exception support header (nested_exception class) for -*- C++ -*-
2
3 // Copyright (C) 2009-2013 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
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.
55 class nested_exception
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
136 throw_with_nested(_Ex __ex)
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
154 rethrow_if_nested(const nested_exception& __ex)
155 { __ex.rethrow_nested(); }
156
157 // @} group exceptions
158 } // namespace std
159
160 } // extern "C++"
161
162 #endif // C++11
163
164 #pragma GCC visibility pop
165
166 #endif // _GLIBCXX_NESTED_EXCEPTION_H