libcxx/include/__exception/exception_ptr.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___EXCEPTION_EXCEPTION_PTR_H
  10 #define _LIBCPP___EXCEPTION_EXCEPTION_PTR_H
  11
  12 #include <__config>
  13 #include <__cstddef/nullptr_t.h>
  14 #include <__exception/operations.h>
  15 #include <__memory/addressof.h>
  16 #include <__memory/construct_at.h>
  17 #include <__type_traits/decay.h>
  18 #include <cstdlib>
  19 #include <new>
  20 #include <typeinfo>
  21
  22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  23 #  pragma GCC system_header
  24 #endif
  25
  26 #ifndef _LIBCPP_ABI_MICROSOFT
  27
  28 #  if _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION
  29
  30 namespace __cxxabiv1 {
  31
  32 extern "C" {
  33 _LIBCPP_OVERRIDABLE_FUNC_VIS void* __cxa_allocate_exception(size_t) throw();
  34 _LIBCPP_OVERRIDABLE_FUNC_VIS void __cxa_free_exception(void*) throw();
  35
  36 struct __cxa_exception;
  37 _LIBCPP_OVERRIDABLE_FUNC_VIS __cxa_exception* __cxa_init_primary_exception(
  38     void*,
  39     std::type_info*,
  40 #    if defined(_WIN32)
  41     void(__thiscall*)(void*)) throw();
  42 #    elif defined(__wasm__)
  43     // In Wasm, a destructor returns its argument
  44     void* (*)(void*)) throw();
  45 #    else
  46     void (*)(void*)) throw();
  47 #    endif
  48 }
  49
  50 } // namespace __cxxabiv1
  51
  52 #  endif
  53
  54 #endif
  55
  56 namespace std { // purposefully not using versioning namespace
  57
  58 #ifndef _LIBCPP_ABI_MICROSOFT
  59
  60 class _LIBCPP_EXPORTED_FROM_ABI exception_ptr {
  61   void* __ptr_;
  62
  63   static exception_ptr __from_native_exception_pointer(void*) _NOEXCEPT;
  64
  65   template <class _Ep>
  66   friend _LIBCPP_HIDE_FROM_ABI exception_ptr make_exception_ptr(_Ep) _NOEXCEPT;
  67
  68 public:
  69   // exception_ptr is basically a COW string.
  70   using __trivially_relocatable = exception_ptr;
  71
  72   _LIBCPP_HIDE_FROM_ABI exception_ptr() _NOEXCEPT : __ptr_() {}
  73   _LIBCPP_HIDE_FROM_ABI exception_ptr(nullptr_t) _NOEXCEPT : __ptr_() {}
  74
  75   exception_ptr(const exception_ptr&) _NOEXCEPT;
  76   exception_ptr& operator=(const exception_ptr&) _NOEXCEPT;
  77   ~exception_ptr() _NOEXCEPT;
  78
  79   _LIBCPP_HIDE_FROM_ABI explicit operator bool() const _NOEXCEPT { return __ptr_ != nullptr; }
  80
  81   friend _LIBCPP_HIDE_FROM_ABI bool operator==(const exception_ptr& __x, const exception_ptr& __y) _NOEXCEPT {
  82     return __x.__ptr_ == __y.__ptr_;
  83   }
  84
  85   friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const exception_ptr& __x, const exception_ptr& __y) _NOEXCEPT {
  86     return !(__x == __y);
  87   }
  88
  89   friend _LIBCPP_EXPORTED_FROM_ABI exception_ptr current_exception() _NOEXCEPT;
  90   friend _LIBCPP_EXPORTED_FROM_ABI void rethrow_exception(exception_ptr);
  91 };
  92
  93 template <class _Ep>
  94 _LIBCPP_HIDE_FROM_ABI exception_ptr make_exception_ptr(_Ep __e) _NOEXCEPT {
  95 #  if _LIBCPP_HAS_EXCEPTIONS
  96 #    if _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION && __cplusplus >= 201103L
  97   using _Ep2 = __decay_t<_Ep>;
  98
  99   void* __ex = __cxxabiv1::__cxa_allocate_exception(sizeof(_Ep));
 100 #      ifdef __wasm__
 101   // In Wasm, a destructor returns its argument
 102   (void)__cxxabiv1::__cxa_init_primary_exception(
 103       __ex, const_cast<std::type_info*>(&typeid(_Ep)), [](void* __p) -> void* {
 104 #      else
 105   (void)__cxxabiv1::__cxa_init_primary_exception(__ex, const_cast<std::type_info*>(&typeid(_Ep)), [](void* __p) {
 106 #      endif
 107         std::__destroy_at(static_cast<_Ep2*>(__p));
 108 #      ifdef __wasm__
 109         return __p;
 110 #      endif
 111       });
 112
 113   try {
 114     ::new (__ex) _Ep2(__e);
 115     return exception_ptr::__from_native_exception_pointer(__ex);
 116   } catch (...) {
 117     __cxxabiv1::__cxa_free_exception(__ex);
 118     return current_exception();
 119   }
 120 #    else
 121   try {
 122     throw __e;
 123   } catch (...) {
 124     return current_exception();
 125   }
 126 #    endif
 127 #  else
 128   ((void)__e);
 129   std::abort();
 130 #  endif
 131 }
 132
 133 #else // _LIBCPP_ABI_MICROSOFT
 134
 135 class _LIBCPP_EXPORTED_FROM_ABI exception_ptr {
 136   _LIBCPP_DIAGNOSTIC_PUSH
 137   _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wunused-private-field")
 138   void* __ptr1_;
 139   void* __ptr2_;
 140   _LIBCPP_DIAGNOSTIC_POP
 141
 142 public:
 143   exception_ptr() _NOEXCEPT;
 144   exception_ptr(nullptr_t) _NOEXCEPT;
 145   exception_ptr(const exception_ptr& __other) _NOEXCEPT;
 146   exception_ptr& operator=(const exception_ptr& __other) _NOEXCEPT;
 147   exception_ptr& operator=(nullptr_t) _NOEXCEPT;
 148   ~exception_ptr() _NOEXCEPT;
 149   explicit operator bool() const _NOEXCEPT;
 150 };
 151
 152 _LIBCPP_EXPORTED_FROM_ABI bool operator==(const exception_ptr& __x, const exception_ptr& __y) _NOEXCEPT;
 153
 154 inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const exception_ptr& __x, const exception_ptr& __y) _NOEXCEPT {
 155   return !(__x == __y);
 156 }
 157
 158 _LIBCPP_EXPORTED_FROM_ABI void swap(exception_ptr&, exception_ptr&) _NOEXCEPT;
 159
 160 _LIBCPP_EXPORTED_FROM_ABI exception_ptr __copy_exception_ptr(void* __except, const void* __ptr);
 161 _LIBCPP_EXPORTED_FROM_ABI exception_ptr current_exception() _NOEXCEPT;
 162 [[__noreturn__]] _LIBCPP_EXPORTED_FROM_ABI void rethrow_exception(exception_ptr);
 163
 164 // This is a built-in template function which automagically extracts the required
 165 // information.
 166 template <class _E>
 167 void* __GetExceptionInfo(_E);
 168
 169 template <class _Ep>
 170 _LIBCPP_HIDE_FROM_ABI exception_ptr make_exception_ptr(_Ep __e) _NOEXCEPT {
 171   return __copy_exception_ptr(std::addressof(__e), __GetExceptionInfo(__e));
 172 }
 173
 174 #endif // _LIBCPP_ABI_MICROSOFT
 175 } // namespace std
 176
 177 #endif // _LIBCPP___EXCEPTION_EXCEPTION_PTR_H