libcxx/include/__expected/bad_expected_access.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9 #ifndef _LIBCPP___EXPECTED_BAD_EXPECTED_ACCESS_H
  10 #define _LIBCPP___EXPECTED_BAD_EXPECTED_ACCESS_H
  11
  12 #include <__config>
  13 #include <__exception/exception.h>
  14 #include <__utility/move.h>
  15
  16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  17 #  pragma GCC system_header
  18 #endif
  19
  20 _LIBCPP_PUSH_MACROS
  21 #include <__undef_macros>
  22
  23 #if _LIBCPP_STD_VER >= 23
  24
  25 _LIBCPP_BEGIN_NAMESPACE_STD
  26
  27 template <class _Err>
  28 class bad_expected_access;
  29
  30 template <>
  31 class bad_expected_access<void> : public exception {
  32 protected:
  33   _LIBCPP_HIDE_FROM_ABI bad_expected_access() noexcept                             = default;
  34   _LIBCPP_HIDE_FROM_ABI bad_expected_access(const bad_expected_access&)            = default;
  35   _LIBCPP_HIDE_FROM_ABI bad_expected_access(bad_expected_access&&)                 = default;
  36   _LIBCPP_HIDE_FROM_ABI bad_expected_access& operator=(const bad_expected_access&) = default;
  37   _LIBCPP_HIDE_FROM_ABI bad_expected_access& operator=(bad_expected_access&&)      = default;
  38   _LIBCPP_HIDE_FROM_ABI_VIRTUAL ~bad_expected_access() override                    = default;
  39
  40 public:
  41   // The way this has been designed (by using a class template below) means that we'll already
  42   // have a profusion of these vtables in TUs, and the dynamic linker will already have a bunch
  43   // of work to do. So it is not worth hiding the <void> specialization in the dylib, given that
  44   // it adds deployment target restrictions.
  45   _LIBCPP_HIDE_FROM_ABI_VIRTUAL const char* what() const noexcept override { return "bad access to std::expected"; }
  46 };
  47
  48 template <class _Err>
  49 class bad_expected_access : public bad_expected_access<void> {
  50 public:
  51   _LIBCPP_HIDE_FROM_ABI explicit bad_expected_access(_Err __e) : __unex_(std::move(__e)) {}
  52
  53   _LIBCPP_HIDE_FROM_ABI _Err& error() & noexcept { return __unex_; }
  54   _LIBCPP_HIDE_FROM_ABI const _Err& error() const& noexcept { return __unex_; }
  55   _LIBCPP_HIDE_FROM_ABI _Err&& error() && noexcept { return std::move(__unex_); }
  56   _LIBCPP_HIDE_FROM_ABI const _Err&& error() const&& noexcept { return std::move(__unex_); }
  57
  58 private:
  59   _Err __unex_;
  60 };
  61
  62 _LIBCPP_END_NAMESPACE_STD
  63
  64 #endif // _LIBCPP_STD_VER >= 23
  65
  66 _LIBCPP_POP_MACROS
  67
  68 #endif // _LIBCPP___EXPECTED_BAD_EXPECTED_ACCESS_H