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

   1 // Exception Handling support header (exception_ptr class) for -*- C++ -*-
   2
   3 // Copyright (C) 2008-2024 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 #include <bits/c++config.h>
  35 #include <bits/exception_defines.h>
  36 #include <bits/cxxabi_init_exception.h>
  37 #include <typeinfo>
  38 #include <new>
  39
  40 #if __cplusplus >= 201103L
  41 # include <bits/move.h>
  42 #endif
  43
  44 #ifdef _GLIBCXX_EH_PTR_RELOPS_COMPAT
  45 # define _GLIBCXX_EH_PTR_USED __attribute__((__used__))
  46 #else
  47 # define _GLIBCXX_EH_PTR_USED
  48 #endif
  49
  50 extern "C++" {
  51
  52 namespace std _GLIBCXX_VISIBILITY(default)
  53 {
  54   class type_info;
  55
  56   /**
  57    * @addtogroup exceptions
  58    * @{
  59    */
  60
  61   namespace __exception_ptr
  62   {
  63     class exception_ptr;
  64   }
  65
  66   using __exception_ptr::exception_ptr;
  67
  68   /** Obtain an exception_ptr to the currently handled exception.
  69    *
  70    * If there is none, or the currently handled exception is foreign,
  71    * return the null value.
  72    *
  73    * @since C++11
  74    */
  75   exception_ptr current_exception() _GLIBCXX_USE_NOEXCEPT;
  76
  77   template<typename _Ex>
  78   exception_ptr make_exception_ptr(_Ex) _GLIBCXX_USE_NOEXCEPT;
  79
  80   /// Throw the object pointed to by the exception_ptr.
  81   void rethrow_exception(exception_ptr) __attribute__ ((__noreturn__));
  82
  83   namespace __exception_ptr
  84   {
  85     using std::rethrow_exception; // So that ADL finds it.
  86
  87     /**
  88      *  @brief An opaque pointer to an arbitrary exception.
  89      *
  90      * The actual name of this type is unspecified, so the alias
  91      * `std::exception_ptr` should be used to refer to it.
  92      *
  93      *  @headerfile exception
  94      *  @since C++11 (but usable in C++98 as a GCC extension)
  95      *  @ingroup exceptions
  96      */
  97     class exception_ptr
  98     {
  99       void* _M_exception_object;
 100
 101       explicit exception_ptr(void* __e) _GLIBCXX_USE_NOEXCEPT;
 102
 103       void _M_addref() _GLIBCXX_USE_NOEXCEPT;
 104       void _M_release() _GLIBCXX_USE_NOEXCEPT;
 105
 106       void *_M_get() const _GLIBCXX_NOEXCEPT __attribute__ ((__pure__));
 107
 108       friend exception_ptr std::current_exception() _GLIBCXX_USE_NOEXCEPT;
 109       friend void std::rethrow_exception(exception_ptr);
 110       template<typename _Ex>
 111       friend exception_ptr std::make_exception_ptr(_Ex) _GLIBCXX_USE_NOEXCEPT;
 112
 113     public:
 114       exception_ptr() _GLIBCXX_USE_NOEXCEPT;
 115
 116       exception_ptr(const exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
 117
 118 #if __cplusplus >= 201103L
 119       exception_ptr(nullptr_t) noexcept
 120       : _M_exception_object(nullptr)
 121       { }
 122
 123       exception_ptr(exception_ptr&& __o) noexcept
 124       : _M_exception_object(__o._M_exception_object)
 125       { __o._M_exception_object = nullptr; }
 126 #endif
 127
 128 #if (__cplusplus < 201103L) || defined (_GLIBCXX_EH_PTR_COMPAT)
 129       typedef void (exception_ptr::*__safe_bool)();
 130
 131       // For construction from nullptr or 0.
 132       exception_ptr(__safe_bool) _GLIBCXX_USE_NOEXCEPT;
 133 #endif
 134
 135       exception_ptr&
 136       operator=(const exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
 137
 138 #if __cplusplus >= 201103L
 139       exception_ptr&
 140       operator=(exception_ptr&& __o) noexcept
 141       {
 142         exception_ptr(static_cast<exception_ptr&&>(__o)).swap(*this);
 143         return *this;
 144       }
 145 #endif
 146
 147       ~exception_ptr() _GLIBCXX_USE_NOEXCEPT;
 148
 149       void
 150       swap(exception_ptr&) _GLIBCXX_USE_NOEXCEPT;
 151
 152 #ifdef _GLIBCXX_EH_PTR_COMPAT
 153       // Retained for compatibility with CXXABI_1.3.
 154       void _M_safe_bool_dummy() _GLIBCXX_USE_NOEXCEPT
 155         __attribute__ ((__const__));
 156       bool operator!() const _GLIBCXX_USE_NOEXCEPT
 157         __attribute__ ((__pure__));
 158       operator __safe_bool() const _GLIBCXX_USE_NOEXCEPT;
 159 #endif
 160
 161 #if __cplusplus >= 201103L
 162       explicit operator bool() const noexcept
 163       { return _M_exception_object; }
 164 #endif
 165
 166 #if __cpp_impl_three_way_comparison >= 201907L \
 167       && ! defined _GLIBCXX_EH_PTR_RELOPS_COMPAT
 168       friend bool
 169       operator==(const exception_ptr&, const exception_ptr&) noexcept = default;
 170 #else
 171       friend _GLIBCXX_EH_PTR_USED bool
 172       operator==(const exception_ptr& __x, const exception_ptr& __y)
 173       _GLIBCXX_USE_NOEXCEPT
 174       { return __x._M_exception_object == __y._M_exception_object; }
 175
 176       friend _GLIBCXX_EH_PTR_USED bool
 177       operator!=(const exception_ptr& __x, const exception_ptr& __y)
 178       _GLIBCXX_USE_NOEXCEPT
 179       { return __x._M_exception_object != __y._M_exception_object; }
 180 #endif
 181
 182       const class std::type_info*
 183       __cxa_exception_type() const _GLIBCXX_USE_NOEXCEPT
 184         __attribute__ ((__pure__));
 185     };
 186
 187     _GLIBCXX_EH_PTR_USED
 188     inline
 189     exception_ptr::exception_ptr() _GLIBCXX_USE_NOEXCEPT
 190     : _M_exception_object(0)
 191     { }
 192
 193     _GLIBCXX_EH_PTR_USED
 194     inline
 195     exception_ptr::exception_ptr(const exception_ptr& __other)
 196     _GLIBCXX_USE_NOEXCEPT
 197     : _M_exception_object(__other._M_exception_object)
 198     {
 199       if (_M_exception_object)
 200         _M_addref();
 201     }
 202
 203     _GLIBCXX_EH_PTR_USED
 204     inline
 205     exception_ptr::~exception_ptr() _GLIBCXX_USE_NOEXCEPT
 206     {
 207       if (_M_exception_object)
 208         _M_release();
 209     }
 210
 211     _GLIBCXX_EH_PTR_USED
 212     inline exception_ptr&
 213     exception_ptr::operator=(const exception_ptr& __other) _GLIBCXX_USE_NOEXCEPT
 214     {
 215       exception_ptr(__other).swap(*this);
 216       return *this;
 217     }
 218
 219     _GLIBCXX_EH_PTR_USED
 220     inline void
 221     exception_ptr::swap(exception_ptr &__other) _GLIBCXX_USE_NOEXCEPT
 222     {
 223       void *__tmp = _M_exception_object;
 224       _M_exception_object = __other._M_exception_object;
 225       __other._M_exception_object = __tmp;
 226     }
 227
 228     /// @relates exception_ptr
 229     inline void
 230     swap(exception_ptr& __lhs, exception_ptr& __rhs)
 231     { __lhs.swap(__rhs); }
 232
 233     /// @cond undocumented
 234     template<typename _Ex>
 235       _GLIBCXX_CDTOR_CALLABI
 236       inline void
 237       __dest_thunk(void* __x)
 238       { static_cast<_Ex*>(__x)->~_Ex(); }
 239     /// @endcond
 240
 241   } // namespace __exception_ptr
 242
 243   using __exception_ptr::swap; // So that std::swap(exp1, exp2) finds it.
 244
 245   /// Obtain an exception_ptr pointing to a copy of the supplied object.
 246 #if (__cplusplus >= 201103L && __cpp_rtti) || __cpp_exceptions
 247   template<typename _Ex>
 248     exception_ptr
 249     make_exception_ptr(_Ex __ex) _GLIBCXX_USE_NOEXCEPT
 250     {
 251 #if __cplusplus >= 201103L && __cpp_rtti
 252       using _Ex2 = typename decay<_Ex>::type;
 253       void* __e = __cxxabiv1::__cxa_allocate_exception(sizeof(_Ex));
 254       (void) __cxxabiv1::__cxa_init_primary_exception(
 255           __e, const_cast<std::type_info*>(&typeid(_Ex)),
 256           __exception_ptr::__dest_thunk<_Ex2>);
 257       __try
 258         {
 259           ::new (__e) _Ex2(__ex);
 260           return exception_ptr(__e);
 261         }
 262       __catch(...)
 263         {
 264           __cxxabiv1::__cxa_free_exception(__e);
 265           return current_exception();
 266         }
 267 #else
 268       try
 269         {
 270           throw __ex;
 271         }
 272       catch(...)
 273         {
 274           return current_exception();
 275         }
 276 #endif
 277     }
 278 #else // no RTTI and no exceptions
 279   // This is always_inline so the linker will never use this useless definition
 280   // instead of a working one compiled with RTTI and/or exceptions enabled.
 281   template<typename _Ex>
 282     __attribute__ ((__always_inline__))
 283     inline exception_ptr
 284     make_exception_ptr(_Ex) _GLIBCXX_USE_NOEXCEPT
 285     { return exception_ptr(); }
 286 #endif
 287
 288 #undef _GLIBCXX_EH_PTR_USED
 289
 290   /// @} group exceptions
 291 } // namespace std
 292
 293 } // extern "C++"
 294
 295 #endif