/* Failure observers for outcome type
(C) 2017-2024 Niall Douglas <http://www.nedproductions.biz/> (7 commits)
File Created: Oct 2017


Boost Software License - Version 1.0 - August 17th, 2003

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*/

#ifndef BOOST_OUTCOME_BASIC_OUTCOME_FAILURE_OBSERVERS_HPP
#define BOOST_OUTCOME_BASIC_OUTCOME_FAILURE_OBSERVERS_HPP

#include "basic_result_storage.hpp"

#include <exception>

BOOST_OUTCOME_V2_NAMESPACE_EXPORT_BEGIN

namespace detail
{
  namespace adl
  {
    struct search_detail_adl
    {
    };
    // Do NOT use template requirements here!
    template <class S, typename = decltype(basic_outcome_failure_exception_from_error(std::declval<S>()))>
    inline auto _delayed_lookup_basic_outcome_failure_exception_from_error(const S &ec, search_detail_adl /*unused*/)
    {
      // ADL discovered
      return basic_outcome_failure_exception_from_error(ec);
    }
  }                                        // namespace adl
#if defined(_MSC_VER) && _MSC_VER <= 1923  // VS2019
  // VS2017 and VS2019 with /permissive- chokes on the correct form due to over eager early instantiation.
  template <class S, class P> inline void _delayed_lookup_basic_outcome_failure_exception_from_error(...) { static_assert(sizeof(S) == 0, "No specialisation for these error and exception types available!"); }
#else
  template <class S, class P> inline void _delayed_lookup_basic_outcome_failure_exception_from_error(...) = delete;  // NOLINT No specialisation for these error and exception types available!
#endif

  template <class exception_type> inline exception_type current_exception_or_fatal(std::exception_ptr e) { std::rethrow_exception(e); }
  template <> inline std::exception_ptr current_exception_or_fatal<std::exception_ptr>(std::exception_ptr e) { return e; }

  template <class Base, class R, class S, class P, class NoValuePolicy> class basic_outcome_failure_observers : public Base
  {
  public:
    using exception_type = P;
    using Base::Base;

    exception_type failure() const noexcept
    {
#ifndef BOOST_NO_EXCEPTIONS
      try
#endif
      {
        if(this->_state._status.have_exception())
        {
          return this->assume_exception();
        }
        if(this->_state._status.have_error())
        {
          return _delayed_lookup_basic_outcome_failure_exception_from_error(this->assume_error(), adl::search_detail_adl());
        }
        return exception_type();
      }
#ifndef BOOST_NO_EXCEPTIONS
      catch(...)
      {
        // Return the failure if exception_type is std::exception_ptr,
        // otherwise terminate same as throwing an exception inside noexcept
        return current_exception_or_fatal<exception_type>(std::current_exception());
      }
#endif
    }
  };

}  // namespace detail

BOOST_OUTCOME_V2_NAMESPACE_END

#endif
