libstdc++
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00001 // Nested Exception support header (nested_exception class) for -*- C++ -*- 00002 00003 // Copyright (C) 2009-2019 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 extern "C++" { 00043 00044 namespace std 00045 { 00046 /** 00047 * @addtogroup exceptions 00048 * @{ 00049 */ 00050 00051 /// Exception class with exception_ptr data member. 00052 class nested_exception 00053 { 00054 exception_ptr _M_ptr; 00055 00056 public: 00057 nested_exception() noexcept : _M_ptr(current_exception()) { } 00058 00059 nested_exception(const nested_exception&) noexcept = default; 00060 00061 nested_exception& operator=(const nested_exception&) noexcept = default; 00062 00063 virtual ~nested_exception() noexcept; 00064 00065 [[noreturn]] 00066 void 00067 rethrow_nested() const 00068 { 00069 if (_M_ptr) 00070 rethrow_exception(_M_ptr); 00071 std::terminate(); 00072 } 00073 00074 exception_ptr 00075 nested_ptr() const noexcept 00076 { return _M_ptr; } 00077 }; 00078 00079 template<typename _Except> 00080 struct _Nested_exception : public _Except, public nested_exception 00081 { 00082 explicit _Nested_exception(const _Except& __ex) 00083 : _Except(__ex) 00084 { } 00085 00086 explicit _Nested_exception(_Except&& __ex) 00087 : _Except(static_cast<_Except&&>(__ex)) 00088 { } 00089 }; 00090 00091 // [except.nested]/8 00092 // Throw an exception of unspecified type that is publicly derived from 00093 // both remove_reference_t<_Tp> and nested_exception. 00094 template<typename _Tp> 00095 [[noreturn]] 00096 inline void 00097 __throw_with_nested_impl(_Tp&& __t, true_type) 00098 { 00099 using _Up = typename remove_reference<_Tp>::type; 00100 throw _Nested_exception<_Up>{std::forward<_Tp>(__t)}; 00101 } 00102 00103 template<typename _Tp> 00104 [[noreturn]] 00105 inline void 00106 __throw_with_nested_impl(_Tp&& __t, false_type) 00107 { throw std::forward<_Tp>(__t); } 00108 00109 /// If @p __t is derived from nested_exception, throws @p __t. 00110 /// Else, throws an implementation-defined object derived from both. 00111 template<typename _Tp> 00112 [[noreturn]] 00113 inline void 00114 throw_with_nested(_Tp&& __t) 00115 { 00116 using _Up = typename decay<_Tp>::type; 00117 using _CopyConstructible 00118 = __and_<is_copy_constructible<_Up>, is_move_constructible<_Up>>; 00119 static_assert(_CopyConstructible::value, 00120 "throw_with_nested argument must be CopyConstructible"); 00121 using __nest = __and_<is_class<_Up>, __bool_constant<!__is_final(_Up)>, 00122 __not_<is_base_of<nested_exception, _Up>>>; 00123 std::__throw_with_nested_impl(std::forward<_Tp>(__t), __nest{}); 00124 } 00125 00126 // Determine if dynamic_cast<const nested_exception&> would be well-formed. 00127 template<typename _Tp> 00128 using __rethrow_if_nested_cond = typename enable_if< 00129 __and_<is_polymorphic<_Tp>, 00130 __or_<__not_<is_base_of<nested_exception, _Tp>>, 00131 is_convertible<_Tp*, nested_exception*>>>::value 00132 >::type; 00133 00134 // Attempt dynamic_cast to nested_exception and call rethrow_nested(). 00135 template<typename _Ex> 00136 inline __rethrow_if_nested_cond<_Ex> 00137 __rethrow_if_nested_impl(const _Ex* __ptr) 00138 { 00139 if (auto __ne_ptr = dynamic_cast<const nested_exception*>(__ptr)) 00140 __ne_ptr->rethrow_nested(); 00141 } 00142 00143 // Otherwise, no effects. 00144 inline void 00145 __rethrow_if_nested_impl(const void*) 00146 { } 00147 00148 /// If @p __ex is derived from nested_exception, @p __ex.rethrow_nested(). 00149 template<typename _Ex> 00150 inline void 00151 rethrow_if_nested(const _Ex& __ex) 00152 { std::__rethrow_if_nested_impl(std::__addressof(__ex)); } 00153 00154 // @} group exceptions 00155 } // namespace std 00156 00157 } // extern "C++" 00158 00159 #endif // C++11 00160 00161 #pragma GCC visibility pop 00162 00163 #endif // _GLIBCXX_NESTED_EXCEPTION_H