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

   1 // Nested Exception support header (nested_exception class) for -*- C++ -*-
   2
   3 // Copyright (C) 2009 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 headers and the
  27  *  implementation. You should not attempt to use it directly.
  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 <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   /// nested_exception
  55   class nested_exception
  56   {
  57   public:
  58     nested_exception() throw() : _M_ptr(current_exception()) { }
  59
  60     nested_exception(const nested_exception&) throw() = default;
  61
  62     nested_exception& operator=(const nested_exception&) throw() = default;
  63
  64     virtual ~nested_exception() = default;
  65
  66     void
  67     rethrow_nested() const __attribute__ ((__noreturn__))
  68     { rethrow_exception(_M_ptr); }
  69
  70     exception_ptr
  71     nested_ptr() const
  72     { return _M_ptr; }
  73
  74   private:
  75     exception_ptr _M_ptr;
  76   };
  77
  78   template<typename _Except>
  79     struct _Nested_exception : public _Except, public nested_exception
  80     {
  81       explicit
  82       _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       {
  93         return dynamic_cast<const nested_exception*>(&__ex);
  94       }
  95     };
  96
  97   template<typename _Ex>
  98     struct __get_nested_helper<_Ex*>
  99     {
 100       static const nested_exception*
 101       _S_get(const _Ex* __ex)
 102       {
 103         return dynamic_cast<const nested_exception*>(__ex);
 104       }
 105     };
 106
 107   template<typename _Ex>
 108     inline const nested_exception*
 109     __get_nested_exception(const _Ex& __ex)
 110     {
 111       return __get_nested_helper<_Ex>::_S_get(__ex);
 112     }
 113
 114   template<typename _Ex>
 115     void
 116     __throw_with_nested(_Ex&&, const nested_exception* = 0)
 117     __attribute__ ((__noreturn__));
 118
 119   template<typename _Ex>
 120     void
 121     __throw_with_nested(_Ex&&, ...) __attribute__ ((__noreturn__));
 122
 123   // This function should never be called, but is needed to avoid a warning
 124   // about ambiguous base classes when instantiating throw_with_nested<_Ex>()
 125   // with a type that has an accessible nested_exception base.
 126   template<typename _Ex>
 127     inline void
 128     __throw_with_nested(_Ex&& __ex, const nested_exception* = 0)
 129     {
 130       throw __ex;
 131     }
 132
 133   template<typename _Ex>
 134     inline void
 135     __throw_with_nested(_Ex&& __ex, ...)
 136     {
 137       throw _Nested_exception<_Ex>(static_cast<_Ex&&>(__ex));
 138     }
 139
 140   template<typename _Ex>
 141     void
 142     throw_with_nested(_Ex __ex) __attribute__ ((__noreturn__));
 143
 144   template<typename _Ex>
 145     inline void
 146     throw_with_nested(_Ex __ex)
 147     {
 148       if (__get_nested_exception(__ex))
 149         throw __ex;
 150       __throw_with_nested(static_cast<_Ex&&>(__ex), &__ex);
 151     }
 152
 153   template<typename _Ex>
 154     inline void
 155     rethrow_if_nested(const _Ex& __ex)
 156     {
 157       if (const nested_exception* __nested = __get_nested_exception(__ex))
 158         __nested->rethrow_nested();
 159     }
 160
 161   // see n2619
 162   inline void
 163   rethrow_if_nested(const nested_exception& __ex)
 164   {
 165     __ex.rethrow_nested();
 166   }
 167
 168   // @} group exceptions
 169 } // namespace std
 170
 171 } // extern "C++"
 172
 173 #endif // __GXX_EXPERIMENTAL_CXX0X__
 174
 175 #pragma GCC visibility pop
 176
 177 #endif // _GLIBCXX_NESTED_EXCEPTION_H