libstdc++-v3/libsupc++/nested_exception.h

   1 // Nested Exception support header (nested_exception class) for -*- C++ -*-
   2
   3 // Copyright (C) 2009, 2010 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 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 #ifndef __GXX_EXPERIMENTAL_CXX0X__
  36 # include <bits/c++0x_warning.h>
  37 #else
  38
  39 #include <bits/c++config.h>
  40
  41 #if !defined(_GLIBCXX_ATOMIC_BUILTINS_4)
  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:
  60     nested_exception() throw() : _M_ptr(current_exception()) { }
  61
  62     nested_exception(const nested_exception&) = default;
  63
  64     nested_exception& operator=(const nested_exception&) = default;
  65
  66     inline virtual ~nested_exception();
  67
  68     void
  69     rethrow_nested() const __attribute__ ((__noreturn__))
  70     { rethrow_exception(_M_ptr); }
  71
  72     exception_ptr
  73     nested_ptr() const
  74     { return _M_ptr; }
  75   };
  76
  77   inline nested_exception::~nested_exception() = default;
  78
  79   template<typename _Except>
  80     struct _Nested_exception : public _Except, public nested_exception
  81     {
  82       explicit _Nested_exception(_Except&& __ex)
  83       : _Except(static_cast<_Except&&>(__ex))
  84       { }
  85     };
  86
  87   template<typename _Ex>
  88     struct __get_nested_helper
  89     {
  90       static const nested_exception*
  91       _S_get(const _Ex& __ex)
  92       { return dynamic_cast<const nested_exception*>(&__ex); }
  93     };
  94
  95   template<typename _Ex>
  96     struct __get_nested_helper<_Ex*>
  97     {
  98       static const nested_exception*
  99       _S_get(const _Ex* __ex)
 100       { return dynamic_cast<const nested_exception*>(__ex); }
 101     };
 102
 103   template<typename _Ex>
 104     inline const nested_exception*
 105     __get_nested_exception(const _Ex& __ex)
 106     { return __get_nested_helper<_Ex>::_S_get(__ex); }
 107
 108   template<typename _Ex>
 109     void
 110     __throw_with_nested(_Ex&&, const nested_exception* = 0)
 111     __attribute__ ((__noreturn__));
 112
 113   template<typename _Ex>
 114     void
 115     __throw_with_nested(_Ex&&, ...) __attribute__ ((__noreturn__));
 116
 117   // This function should never be called, but is needed to avoid a warning
 118   // about ambiguous base classes when instantiating throw_with_nested<_Ex>()
 119   // with a type that has an accessible nested_exception base.
 120   template<typename _Ex>
 121     inline void
 122     __throw_with_nested(_Ex&& __ex, const nested_exception* = 0)
 123     { throw __ex; }
 124
 125   template<typename _Ex>
 126     inline void
 127     __throw_with_nested(_Ex&& __ex, ...)
 128     { throw _Nested_exception<_Ex>(static_cast<_Ex&&>(__ex)); }
 129
 130   template<typename _Ex>
 131     void
 132     throw_with_nested(_Ex __ex) __attribute__ ((__noreturn__));
 133
 134   /// If @p __ex is derived from nested_exception, @p __ex.
 135   /// Else, an implementation-defined object derived from both.
 136   template<typename _Ex>
 137     inline void
 138     throw_with_nested(_Ex __ex)
 139     {
 140       if (__get_nested_exception(__ex))
 141         throw __ex;
 142       __throw_with_nested(static_cast<_Ex&&>(__ex), &__ex);
 143     }
 144
 145   /// If @p __ex is derived from nested_exception, @p __ex.rethrow_nested().
 146   template<typename _Ex>
 147     inline void
 148     rethrow_if_nested(const _Ex& __ex)
 149     {
 150       if (const nested_exception* __nested = __get_nested_exception(__ex))
 151         __nested->rethrow_nested();
 152     }
 153
 154   /// Overload, See N2619
 155   inline void
 156   rethrow_if_nested(const nested_exception& __ex)
 157   { __ex.rethrow_nested(); }
 158
 159   // @} group exceptions
 160 } // namespace std
 161
 162 } // extern "C++"
 163
 164 #endif // __GXX_EXPERIMENTAL_CXX0X__
 165
 166 #pragma GCC visibility pop
 167
 168 #endif // _GLIBCXX_NESTED_EXCEPTION_H