1 // Nested Exception support header (nested_exception class) for -*- C++ -*- 2 3 // Copyright (C) 2009-2015 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&) noexcept = default; 63 64 nested_exception& operator=(const nested_exception&) noexcept = default; 65 66 virtual ~nested_exception() noexcept; 67 68 [[noreturn]] 69 void rethrow_nested()70 rethrow_nested() const 71 { 72 if (_M_ptr) 73 rethrow_exception(_M_ptr); 74 std::terminate(); 75 } 76 77 exception_ptr nested_ptr()78 nested_ptr() const noexcept 79 { return _M_ptr; } 80 }; 81 82 template<typename _Except> 83 struct _Nested_exception : public _Except, public nested_exception 84 { _Nested_exception_Nested_exception85 explicit _Nested_exception(const _Except& __ex) 86 : _Except(__ex) 87 { } 88 _Nested_exception_Nested_exception89 explicit _Nested_exception(_Except&& __ex) 90 : _Except(static_cast<_Except&&>(__ex)) 91 { } 92 }; 93 94 template<typename _Tp, 95 bool __with_nested = !__is_base_of(nested_exception, _Tp)> 96 struct _Throw_with_nested_impl 97 { 98 template<typename _Up> _S_throw_Throw_with_nested_impl99 static void _S_throw(_Up&& __t) 100 { throw _Nested_exception<_Tp>{static_cast<_Up&&>(__t)}; } 101 }; 102 103 template<typename _Tp> 104 struct _Throw_with_nested_impl<_Tp, false> 105 { 106 template<typename _Up> 107 static void _S_throw(_Up&& __t) 108 { throw static_cast<_Up&&>(__t); } 109 }; 110 111 template<typename _Tp, bool = __is_class(_Tp) && !__is_final(_Tp)> 112 struct _Throw_with_nested_helper : _Throw_with_nested_impl<_Tp> 113 { }; 114 115 template<typename _Tp> 116 struct _Throw_with_nested_helper<_Tp, false> 117 : _Throw_with_nested_impl<_Tp, false> 118 { }; 119 120 template<typename _Tp> 121 struct _Throw_with_nested_helper<_Tp&, false> 122 : _Throw_with_nested_helper<_Tp> 123 { }; 124 125 template<typename _Tp> 126 struct _Throw_with_nested_helper<_Tp&&, false> 127 : _Throw_with_nested_helper<_Tp> 128 { }; 129 130 /// If @p __t is derived from nested_exception, throws @p __t. 131 /// Else, throws an implementation-defined object derived from both. 132 template<typename _Tp> 133 [[noreturn]] 134 inline void 135 throw_with_nested(_Tp&& __t) 136 { 137 _Throw_with_nested_helper<_Tp>::_S_throw(static_cast<_Tp&&>(__t)); 138 } 139 140 template<typename _Tp, bool = __is_polymorphic(_Tp)> 141 struct _Rethrow_if_nested_impl 142 { 143 static void _S_rethrow(const _Tp& __t) 144 { 145 if (auto __tp = dynamic_cast<const nested_exception*>(&__t)) 146 __tp->rethrow_nested(); 147 } 148 }; 149 150 template<typename _Tp> 151 struct _Rethrow_if_nested_impl<_Tp, false> 152 { 153 static void _S_rethrow(const _Tp&) { } 154 }; 155 156 /// If @p __ex is derived from nested_exception, @p __ex.rethrow_nested(). 157 template<typename _Ex> 158 inline void 159 rethrow_if_nested(const _Ex& __ex) 160 { 161 _Rethrow_if_nested_impl<_Ex>::_S_rethrow(__ex); 162 } 163 164 // @} group exceptions 165 } // namespace std 166 167 } // extern "C++" 168 169 #endif // C++11 170 171 #pragma GCC visibility pop 172 173 #endif // _GLIBCXX_NESTED_EXCEPTION_H 174