robot/include/boost/outcome/detail/basic_result_storage.hpp

/* Storage for a very simple basic_result type
(C) 2017-2024 Niall Douglas <http://www.nedproductions.biz/> (6 commits)
File Created: Oct 2017


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

Permission is hereby granted, free of charge, to any person or organization
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*/

#ifndef BOOST_OUTCOME_BASIC_RESULT_STORAGE_HPP
#define BOOST_OUTCOME_BASIC_RESULT_STORAGE_HPP

#include "../success_failure.hpp"
#include "../trait.hpp"
#include "value_storage.hpp"

BOOST_OUTCOME_V2_NAMESPACE_EXPORT_BEGIN

namespace detail
{
  template <class R, class EC, class NoValuePolicy> class basic_result_storage;
}  // namespace detail

namespace hooks
{
  template <class R, class S, class NoValuePolicy> constexpr inline uint16_t spare_storage(const detail::basic_result_storage<R, S, NoValuePolicy> *r) noexcept;
  template <class R, class S, class NoValuePolicy>
  constexpr inline void set_spare_storage(detail::basic_result_storage<R, S, NoValuePolicy> *r, uint16_t v) noexcept;
}  // namespace hooks

namespace policy
{
  struct base;
}  // namespace policy

namespace detail
{
  template <class R, class EC, class NoValuePolicy>  //
  class basic_result_storage
  {
    static_assert(trait::type_can_be_used_in_basic_result<R>, "The type R cannot be used in a basic_result");
    static_assert(trait::type_can_be_used_in_basic_result<EC>, "The type S cannot be used in a basic_result");

    friend struct policy::base;
    template <class T, class U, class V>  //
    friend class basic_result_storage;
    template <class T, class U, class V> friend class basic_result_final;
    template <class T, class U, class V>
    friend constexpr inline uint16_t hooks::spare_storage(const detail::basic_result_storage<T, U, V> *r) noexcept;  // NOLINT
    template <class T, class U, class V>
    friend constexpr inline void hooks::set_spare_storage(detail::basic_result_storage<T, U, V> *r, uint16_t v) noexcept;  // NOLINT

    struct disable_in_place_value_type
    {
    };
    struct disable_in_place_error_type
    {
    };

  protected:
    using _value_type = std::conditional_t<std::is_same<R, EC>::value, disable_in_place_value_type, R>;
    using _error_type = std::conditional_t<std::is_same<R, EC>::value, disable_in_place_error_type, EC>;

    using _state_type = value_storage_select_impl<_value_type, _error_type>;

#ifdef BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE
    value_storage_trivial<_value_type, _error_type> _state;
#else
    _state_type _state;
#endif

  public:
    // Used by iostream support to access state
    _state_type &_iostreams_state() { return _state; }
    const _state_type &_iostreams_state() const { return _state; }

  protected:
    basic_result_storage() = default;
    basic_result_storage(const basic_result_storage &) = default;             // NOLINT
    basic_result_storage(basic_result_storage &&) = default;                  // NOLINT
    basic_result_storage &operator=(const basic_result_storage &) = default;  // NOLINT
    basic_result_storage &operator=(basic_result_storage &&) = default;       // NOLINT
    ~basic_result_storage() = default;

    template <class... Args>
    constexpr explicit basic_result_storage(in_place_type_t<_value_type> _,
                                            Args &&... args) noexcept(detail::is_nothrow_constructible<_value_type, Args...>)
        : _state{_, static_cast<Args &&>(args)...}
    {
    }
    template <class U, class... Args>
    constexpr basic_result_storage(in_place_type_t<_value_type> _, std::initializer_list<U> il,
                                   Args &&... args) noexcept(detail::is_nothrow_constructible<_value_type, std::initializer_list<U>, Args...>)
        : _state{_, il, static_cast<Args &&>(args)...}
    {
    }
    template <class... Args>
    constexpr explicit basic_result_storage(in_place_type_t<_error_type> _,
                                            Args &&... args) noexcept(detail::is_nothrow_constructible<_error_type, Args...>)
        : _state{_, static_cast<Args &&>(args)...}
    {
    }
    template <class U, class... Args>
    constexpr basic_result_storage(in_place_type_t<_error_type> _, std::initializer_list<U> il,
                                   Args &&... args) noexcept(detail::is_nothrow_constructible<_error_type, std::initializer_list<U>, Args...>)
        : _state{_, il, static_cast<Args &&>(args)...}
    {
    }

    struct compatible_conversion_tag
    {
    };
    template <class T, class U, class V>
    constexpr basic_result_storage(compatible_conversion_tag /*unused*/, const basic_result_storage<T, U, V> &o) noexcept(
    detail::is_nothrow_constructible<_value_type, T> &&detail::is_nothrow_constructible<_error_type, U>)
        : _state(o._state)
    {
    }
    template <class T, class U, class V>
    constexpr basic_result_storage(compatible_conversion_tag /*unused*/, basic_result_storage<T, U, V> &&o) noexcept(
    detail::is_nothrow_constructible<_value_type, T> &&detail::is_nothrow_constructible<_error_type, U>)
        : _state(static_cast<decltype(o._state) &&>(o._state))
    {
    }

    struct make_error_code_compatible_conversion_tag
    {
    };
    template <class T, class U, class V>
    constexpr basic_result_storage(make_error_code_compatible_conversion_tag /*unused*/, const basic_result_storage<T, U, V> &o) noexcept(
    detail::is_nothrow_constructible<_value_type, T> &&noexcept(make_error_code(std::declval<U>())))
        : _state(o._state._status.have_value() ? _state_type(in_place_type<_value_type>, o._state._value) :
                                                 _state_type(in_place_type<_error_type>, make_error_code(o._state._error)))
    {
    }
    template <class T, class U, class V>
    constexpr basic_result_storage(make_error_code_compatible_conversion_tag /*unused*/, basic_result_storage<T, U, V> &&o) noexcept(
    detail::is_nothrow_constructible<_value_type, T> &&noexcept(make_error_code(std::declval<U>())))
        : _state(o._state._status.have_value() ? _state_type(in_place_type<_value_type>, static_cast<T &&>(o._state._value)) :
                                                 _state_type(in_place_type<_error_type>, make_error_code(static_cast<U &&>(o._state._error))))
    {
    }

    struct make_exception_ptr_compatible_conversion_tag
    {
    };
    template <class T, class U, class V>
    constexpr basic_result_storage(make_exception_ptr_compatible_conversion_tag /*unused*/, const basic_result_storage<T, U, V> &o) noexcept(
    detail::is_nothrow_constructible<_value_type, T> &&noexcept(make_exception_ptr(std::declval<U>())))
        : _state(o._state._status.have_value() ? _state_type(in_place_type<_value_type>, o._state._value) :
                                                 _state_type(in_place_type<_error_type>, make_exception_ptr(o._state._error)))
    {
    }
    template <class T, class U, class V>
    constexpr basic_result_storage(make_exception_ptr_compatible_conversion_tag /*unused*/, basic_result_storage<T, U, V> &&o) noexcept(
    detail::is_nothrow_constructible<_value_type, T> &&noexcept(make_exception_ptr(std::declval<U>())))
        : _state(o._state._status.have_value() ? _state_type(in_place_type<_value_type>, static_cast<T &&>(o._state._value)) :
                                                 _state_type(in_place_type<_error_type>, make_exception_ptr(static_cast<U &&>(o._state._error))))
    {
    }
  };

}  // namespace detail
BOOST_OUTCOME_V2_NAMESPACE_END

#endif