handle_exception.h

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___PSTL_HANDLE_EXCEPTION_H
#define _LIBCPP___PSTL_HANDLE_EXCEPTION_H

#include <__config>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <new> // __throw_bad_alloc
#include <optional>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD
namespace __pstl {

template <class _BackendFunction, class... _Args>
_LIBCPP_HIDE_FROM_ABI auto __handle_exception_impl(_Args&&... __args) noexcept {
  return _BackendFunction{}(std::forward<_Args>(__args)...);
}

// This function is used to call a backend PSTL algorithm from a frontend algorithm.
//
// All PSTL backend algorithms return an optional denoting whether there was an
// "infrastructure"-level failure (aka failure to allocate). This function takes
// care of unwrapping that and throwing `bad_alloc()` in case there was a problem
// in the underlying implementation.
//
// We must also be careful not to call any user code that could throw an exception
// (such as moving or copying iterators) in here since that should terminate the
// program, which is why we delegate to a noexcept helper below.
template <class _BackendFunction, class... _Args>
_LIBCPP_HIDE_FROM_ABI auto __handle_exception(_Args&&... __args) {
  auto __result = __pstl::__handle_exception_impl<_BackendFunction>(std::forward<_Args>(__args)...);
  if (__result == nullopt)
    std::__throw_bad_alloc();
  else
    return std::move(*__result);
}

} // namespace __pstl
_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP___PSTL_HANDLE_EXCEPTION_H