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

   1 // Exception Handling support header (exception_ptr class) for -*- C++ -*-
   2
   3 // Copyright (C) 2008-2018 Free Software Foundation, Inc.
   4 //
   5 // This file is part of GCC.
   6 //
   7 // GCC is free software; you can redistribute it and/or modify
   8 // it under the terms of the GNU General Public License as published by
   9 // the Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11 //
  12 // GCC is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // Under Section 7 of GPL version 3, you are granted additional
  18 // permissions described in the GCC Runtime Library Exception, version
  19 // 3.1, as published by the Free Software Foundation.
  20
  21 // You should have received a copy of the GNU General Public License and
  22 // a copy of the GCC Runtime Library Exception along with this program;
  23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 // <http://www.gnu.org/licenses/>.
  25
  26 /** @file bits/exception_ptr.h
  27  *  This is an internal header file, included by other library headers.
  28  *  Do not attempt to use it directly. @headername{exception}
  29  */
  30
  31 #ifndef _EXCEPTION_PTR_H
  32 #define _EXCEPTION_PTR_H
  33
  34 #pragma GCC visibility push(default)
  35
  36 #include <bits/c++config.h>
  37 #include <bits/exception_defines.h>
  38 #include <bits/cxxabi_init_exception.h>
  39 #include <typeinfo>
  40 #include <new>
  41
  42 extern "C++" {
  43
  44 namespace std
  45 {
  46   class type_info;
  47
  48   /**
  49    * @addtogroup exceptions
  50    * @{
  51    */
  52   namespace __exception_ptr
  53   {
  54     class exception_ptr;
  55   }
  56
  57   using __exception_ptr::exception_ptr;
  58
  59   /** Obtain an exception_ptr to the currently handled exception. If there
  60    *  is none, or the currently handled exception is foreign, return the null
  61    *  value.
  62    */
  63   exception_ptr current_exception() _GLIBCXX_USE_NOEXCEPT;
  64
  65   template<typename _Ex>
  66   exception_ptr make_exception_ptr(_Ex) _GLIBCXX_USE_NOEXCEPT;
  67
  68   /// Throw the object pointed to by the exception_ptr.
  69   void rethrow_exception(exception_ptr) __attribute__ ((__noreturn__));
  70
  71   namespace __exception_ptr
  72   {
  73     using std::rethrow_exception;
  74
  75     /**
  76      *  @brief An opaque pointer to an arbitrary exception.
  77      *  @ingroup exceptions
  78      */
  79     class exception_ptr
  80     {
  81       void* _M_exception_object;
  82
  83       explicit exception_ptr(void* __e) _GLIBCXX_USE_NOEXCEPT;
  84
  85       void _M_addref() _GLIBCXX_USE_NOEXCEPT;
  86       void _M_release() _GLIBCXX_USE_NOEXCEPT;
  87
  88       void *_M_get() const _GLIBCXX_NOEXCEPT __attribute__ ((__pure__));
  89
  90       friend exception_ptr std::current_exception() _GLIBCXX_USE_NOEXCEPT;
  91       friend void std::rethrow_exception(exception_ptr);
  92       template<typename _Ex>
  93       friend exception_ptr std::make_exception_ptr(_Ex) _GLIBCXX_USE_NOEXCEPT;
  94
  95     public:
  96       exception_ptr() _GLIBCXX_USE_NOEXCEPT;
  97
  98       exception_ptr(const exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
  99
 100 #if __cplusplus >= 201103L
 101       exception_ptr(nullptr_t) noexcept
 102       : _M_exception_object(0)
 103       { }
 104
 105       exception_ptr(exception_ptr&& __o) noexcept
 106       : _M_exception_object(__o._M_exception_object)
 107       { __o._M_exception_object = 0; }
 108 #endif
 109
 110 #if (__cplusplus < 201103L) || defined (_GLIBCXX_EH_PTR_COMPAT)
 111       typedef void (exception_ptr::*__safe_bool)();
 112
 113       // For construction from nullptr or 0.
 114       exception_ptr(__safe_bool) _GLIBCXX_USE_NOEXCEPT;
 115 #endif
 116
 117       exception_ptr&
 118       operator=(const exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
 119
 120 #if __cplusplus >= 201103L
 121       exception_ptr&
 122       operator=(exception_ptr&& __o) noexcept
 123       {
 124         exception_ptr(static_cast<exception_ptr&&>(__o)).swap(*this);
 125         return *this;
 126       }
 127 #endif
 128
 129       ~exception_ptr() _GLIBCXX_USE_NOEXCEPT;
 130
 131       void
 132       swap(exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
 133
 134 #ifdef _GLIBCXX_EH_PTR_COMPAT
 135       // Retained for compatibility with CXXABI_1.3.
 136       void _M_safe_bool_dummy() _GLIBCXX_USE_NOEXCEPT
 137         __attribute__ ((__const__));
 138       bool operator!() const _GLIBCXX_USE_NOEXCEPT
 139         __attribute__ ((__pure__));
 140       operator __safe_bool() const _GLIBCXX_USE_NOEXCEPT;
 141 #endif
 142
 143 #if __cplusplus >= 201103L
 144       explicit operator bool() const
 145       { return _M_exception_object; }
 146 #endif
 147
 148       friend bool
 149       operator==(const exception_ptr&, const exception_ptr&)
 150         _GLIBCXX_USE_NOEXCEPT __attribute__ ((__pure__));
 151
 152       const class std::type_info*
 153       __cxa_exception_type() const _GLIBCXX_USE_NOEXCEPT
 154         __attribute__ ((__pure__));
 155     };
 156
 157     bool
 158     operator==(const exception_ptr&, const exception_ptr&)
 159       _GLIBCXX_USE_NOEXCEPT __attribute__ ((__pure__));
 160
 161     bool
 162     operator!=(const exception_ptr&, const exception_ptr&)
 163       _GLIBCXX_USE_NOEXCEPT __attribute__ ((__pure__));
 164
 165     inline void
 166     swap(exception_ptr& __lhs, exception_ptr& __rhs)
 167     { __lhs.swap(__rhs); }
 168
 169     template<typename _Ex>
 170       inline void
 171       __dest_thunk(void* __x)
 172       { static_cast<_Ex*>(__x)->~_Ex(); }
 173
 174   } // namespace __exception_ptr
 175
 176   /// Obtain an exception_ptr pointing to a copy of the supplied object.
 177   template<typename _Ex>
 178     exception_ptr
 179     make_exception_ptr(_Ex __ex) _GLIBCXX_USE_NOEXCEPT
 180     {
 181 #if __cpp_exceptions
 182       try
 183         {
 184 #if __cpp_rtti && !_GLIBCXX_HAVE_CDTOR_CALLABI
 185           void *__e = __cxxabiv1::__cxa_allocate_exception(sizeof(_Ex));
 186           (void)__cxxabiv1::__cxa_init_primary_exception(
 187               __e, const_cast<std::type_info*>(&typeid(__ex)),
 188               __exception_ptr::__dest_thunk<_Ex>);
 189           ::new (__e) _Ex(__ex);
 190           return exception_ptr(__e);
 191 #else
 192           throw __ex;
 193 #endif
 194         }
 195       catch(...)
 196         {
 197           return current_exception();
 198         }
 199 #else
 200       return exception_ptr();
 201 #endif
 202     }
 203
 204   // @} group exceptions
 205 } // namespace std
 206
 207 } // extern "C++"
 208
 209 #pragma GCC visibility pop
 210
 211 #endif