1 // Nested Exception support header (nested_exception class) for -*- C++ -*-
3 // Copyright (C) 2009-2022 Free Software Foundation, Inc.
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)
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.
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.
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/>.
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}
30 #ifndef _GLIBCXX_NESTED_EXCEPTION_H
31 #define _GLIBCXX_NESTED_EXCEPTION_H 1
33 #pragma GCC visibility push(default)
35 #if __cplusplus < 201103L
36 # include <bits/c++0x_warning.h>
39 #include <bits/c++config.h>
40 #include <bits/move.h>
47 * @addtogroup exceptions
51 /// Exception class with exception_ptr data member.
52 class nested_exception
57 nested_exception() noexcept
: _M_ptr(current_exception()) { }
59 nested_exception(const nested_exception
&) noexcept
= default;
61 nested_exception
& operator=(const nested_exception
&) noexcept
= default;
63 virtual ~nested_exception() noexcept
;
67 rethrow_nested() const
70 rethrow_exception(_M_ptr
);
75 nested_ptr() const noexcept
79 /// @cond undocumented
81 template<typename _Except
>
82 struct _Nested_exception
: public _Except
, public nested_exception
84 explicit _Nested_exception(const _Except
& __ex
)
88 explicit _Nested_exception(_Except
&& __ex
)
89 : _Except(static_cast<_Except
&&>(__ex
))
94 // Throw an exception of unspecified type that is publicly derived from
95 // both remove_reference_t<_Tp> and nested_exception.
96 template<typename _Tp
>
99 __throw_with_nested_impl(_Tp
&& __t
, true_type
)
101 using _Up
= typename remove_reference
<_Tp
>::type
;
102 throw _Nested_exception
<_Up
>{std::forward
<_Tp
>(__t
)};
105 template<typename _Tp
>
108 __throw_with_nested_impl(_Tp
&& __t
, false_type
)
109 { throw std::forward
<_Tp
>(__t
); }
113 /// If @p __t is derived from nested_exception, throws @p __t.
114 /// Else, throws an implementation-defined object derived from both.
115 template<typename _Tp
>
118 throw_with_nested(_Tp
&& __t
)
120 using _Up
= typename decay
<_Tp
>::type
;
121 using _CopyConstructible
122 = __and_
<is_copy_constructible
<_Up
>, is_move_constructible
<_Up
>>;
123 static_assert(_CopyConstructible::value
,
124 "throw_with_nested argument must be CopyConstructible");
125 using __nest
= __and_
<is_class
<_Up
>, __bool_constant
<!__is_final(_Up
)>,
126 __not_
<is_base_of
<nested_exception
, _Up
>>>;
127 std::__throw_with_nested_impl(std::forward
<_Tp
>(__t
), __nest
{});
130 /// @cond undocumented
132 // Determine if dynamic_cast<const nested_exception&> would be well-formed.
133 template<typename _Tp
>
134 using __rethrow_if_nested_cond
= typename enable_if
<
135 __and_
<is_polymorphic
<_Tp
>,
136 __or_
<__not_
<is_base_of
<nested_exception
, _Tp
>>,
137 is_convertible
<_Tp
*, nested_exception
*>>>::value
140 // Attempt dynamic_cast to nested_exception and call rethrow_nested().
141 template<typename _Ex
>
142 inline __rethrow_if_nested_cond
<_Ex
>
143 __rethrow_if_nested_impl(const _Ex
* __ptr
)
145 if (auto __ne_ptr
= dynamic_cast<const nested_exception
*>(__ptr
))
146 __ne_ptr
->rethrow_nested();
149 // Otherwise, no effects.
151 __rethrow_if_nested_impl(const void*)
156 /// If @p __ex is derived from nested_exception, @p __ex.rethrow_nested().
157 template<typename _Ex
>
159 rethrow_if_nested(const _Ex
& __ex
)
160 { std::__rethrow_if_nested_impl(std::__addressof(__ex
)); }
162 /// @} group exceptions
169 #pragma GCC visibility pop
171 #endif // _GLIBCXX_NESTED_EXCEPTION_H