libstdc++
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00001 // Nested Exception support header (nested_exception class) for -*- C++ -*- 00002 00003 // Copyright (C) 2009-2016 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file bits/nested_exception.h 00026 * This is an internal header file, included by other library headers. 00027 * Do not attempt to use it directly. @headername{exception} 00028 */ 00029 00030 #ifndef _GLIBCXX_NESTED_EXCEPTION_H 00031 #define _GLIBCXX_NESTED_EXCEPTION_H 1 00032 00033 #pragma GCC visibility push(default) 00034 00035 #if __cplusplus < 201103L 00036 # include <bits/c++0x_warning.h> 00037 #else 00038 00039 #include <bits/c++config.h> 00040 #include <bits/move.h> 00041 00042 #if ATOMIC_INT_LOCK_FREE < 2 00043 # error This platform does not support exception propagation. 00044 #endif 00045 00046 extern "C++" { 00047 00048 namespace std 00049 { 00050 /** 00051 * @addtogroup exceptions 00052 * @{ 00053 */ 00054 00055 /// Exception class with exception_ptr data member. 00056 class nested_exception 00057 { 00058 exception_ptr _M_ptr; 00059 00060 public: 00061 nested_exception() noexcept : _M_ptr(current_exception()) { } 00062 00063 nested_exception(const nested_exception&) noexcept = default; 00064 00065 nested_exception& operator=(const nested_exception&) noexcept = default; 00066 00067 virtual ~nested_exception() noexcept; 00068 00069 [[noreturn]] 00070 void 00071 rethrow_nested() const 00072 { 00073 if (_M_ptr) 00074 rethrow_exception(_M_ptr); 00075 std::terminate(); 00076 } 00077 00078 exception_ptr 00079 nested_ptr() const noexcept 00080 { return _M_ptr; } 00081 }; 00082 00083 template<typename _Except> 00084 struct _Nested_exception : public _Except, public nested_exception 00085 { 00086 explicit _Nested_exception(const _Except& __ex) 00087 : _Except(__ex) 00088 { } 00089 00090 explicit _Nested_exception(_Except&& __ex) 00091 : _Except(static_cast<_Except&&>(__ex)) 00092 { } 00093 }; 00094 00095 // [except.nested]/8 00096 // Throw an exception of unspecified type that is publicly derived from 00097 // both remove_reference_t<_Tp> and nested_exception. 00098 template<typename _Tp> 00099 inline void 00100 __throw_with_nested_impl(_Tp&& __t, true_type) 00101 { 00102 using _Up = typename remove_reference<_Tp>::type; 00103 throw _Nested_exception<_Up>{std::forward<_Tp>(__t)}; 00104 } 00105 00106 template<typename _Tp> 00107 inline void 00108 __throw_with_nested_impl(_Tp&& __t, false_type) 00109 { throw std::forward<_Tp>(__t); } 00110 00111 /// If @p __t is derived from nested_exception, throws @p __t. 00112 /// Else, throws an implementation-defined object derived from both. 00113 template<typename _Tp> 00114 [[noreturn]] 00115 inline void 00116 throw_with_nested(_Tp&& __t) 00117 { 00118 using _Up = typename decay<_Tp>::type; 00119 using _CopyConstructible 00120 = __and_<is_copy_constructible<_Up>, is_move_constructible<_Up>>; 00121 static_assert(_CopyConstructible::value, 00122 "throw_with_nested argument must be CopyConstructible"); 00123 using __nest = __and_<is_class<_Up>, __bool_constant<!__is_final(_Up)>, 00124 __not_<is_base_of<nested_exception, _Up>>>; 00125 std::__throw_with_nested_impl(std::forward<_Tp>(__t), __nest{}); 00126 } 00127 00128 // Determine if dynamic_cast<const nested_exception&> would be well-formed. 00129 template<typename _Tp> 00130 using __rethrow_if_nested_cond = typename enable_if< 00131 __and_<is_polymorphic<_Tp>, 00132 __or_<__not_<is_base_of<nested_exception, _Tp>>, 00133 is_convertible<_Tp*, nested_exception*>>>::value 00134 >::type; 00135 00136 // Attempt dynamic_cast to nested_exception and call rethrow_nested(). 00137 template<typename _Ex> 00138 inline __rethrow_if_nested_cond<_Ex> 00139 __rethrow_if_nested_impl(const _Ex* __ptr) 00140 { 00141 if (auto __ne_ptr = dynamic_cast<const nested_exception*>(__ptr)) 00142 __ne_ptr->rethrow_nested(); 00143 } 00144 00145 // Otherwise, no effects. 00146 inline void 00147 __rethrow_if_nested_impl(const void*) 00148 { } 00149 00150 /// If @p __ex is derived from nested_exception, @p __ex.rethrow_nested(). 00151 template<typename _Ex> 00152 inline void 00153 rethrow_if_nested(const _Ex& __ex) 00154 { std::__rethrow_if_nested_impl(std::__addressof(__ex)); } 00155 00156 // @} group exceptions 00157 } // namespace std 00158 00159 } // extern "C++" 00160 00161 #endif // C++11 00162 00163 #pragma GCC visibility pop 00164 00165 #endif // _GLIBCXX_NESTED_EXCEPTION_H