1 // Nested Exception support header (nested_exception class) for -*- C++ -*-
2 
3 // Copyright (C) 2009-2014 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:
nested_exception()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
rethrow_nested()69     rethrow_nested() const __attribute__ ((__noreturn__))
70     { rethrow_exception(_M_ptr); }
71 
72     exception_ptr
nested_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     {
_Nested_exception_Nested_exception80       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*
_S_get__get_nested_helper89       _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
167