lewaimai_pos_windows/include/boost/outcome/detail/value_storage.hpp

/* Essentially an internal optional implementation :)
(C) 2017-2019 Niall Douglas <http://www.nedproductions.biz/> (59 commits)
File Created: June 2017


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

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*/

#ifndef BOOST_OUTCOME_VALUE_STORAGE_HPP
#define BOOST_OUTCOME_VALUE_STORAGE_HPP

#include "../config.hpp"

BOOST_OUTCOME_V2_NAMESPACE_BEGIN

namespace detail
{
  using status_bitfield_type = uint32_t;

  // WARNING: These bits are not tracked by abi-dumper, but changing them will break ABI!
  static constexpr status_bitfield_type status_have_value = (1U << 0U);
  static constexpr status_bitfield_type status_have_error = (1U << 1U);
  static constexpr status_bitfield_type status_have_exception = (1U << 2U);
  static constexpr status_bitfield_type status_error_is_errno = (1U << 4U);  // can errno be set from this error?
  // bit 7 unused
  // bits 8-15 unused
  // bits 16-31 used for user supplied 16 bit value
  static constexpr status_bitfield_type status_2byte_shift = 16;
  static constexpr status_bitfield_type status_2byte_mask = (0xffffU << status_2byte_shift);

  // Used if T is trivial
  template <class T> struct value_storage_trivial
  {
    using value_type = T;
    union {
      empty_type _empty;
      devoid<T> _value;
    };
    status_bitfield_type _status{0};
    constexpr value_storage_trivial() noexcept : _empty{} {}
    // Special from-void catchall constructor, always constructs default T irrespective of whether void is valued or not (can do no better if T cannot be copied)
    struct disable_void_catchall
    {
    };
    using void_value_storage_trivial = std::conditional_t<std::is_void<T>::value, disable_void_catchall, value_storage_trivial<void>>;
    explicit constexpr value_storage_trivial(const void_value_storage_trivial &o) noexcept(std::is_nothrow_default_constructible<value_type>::value)
        : _value()
        , _status(o._status)
    {
    }
    value_storage_trivial(const value_storage_trivial &) = default;             // NOLINT
    value_storage_trivial(value_storage_trivial &&) = default;                  // NOLINT
    value_storage_trivial &operator=(const value_storage_trivial &) = default;  // NOLINT
    value_storage_trivial &operator=(value_storage_trivial &&) = default;       // NOLINT
    ~value_storage_trivial() = default;
    constexpr explicit value_storage_trivial(status_bitfield_type status)
        : _empty()
        , _status(status)
    {
    }
    template <class... Args>
    constexpr explicit value_storage_trivial(in_place_type_t<value_type> /*unused*/, Args &&... args) noexcept(std::is_nothrow_constructible<value_type, Args...>::value)
        : _value(static_cast<Args &&>(args)...)
        , _status(status_have_value)
    {
    }
    template <class U, class... Args>
    constexpr value_storage_trivial(in_place_type_t<value_type> /*unused*/, std::initializer_list<U> il, Args &&... args) noexcept(std::is_nothrow_constructible<value_type, std::initializer_list<U>, Args...>::value)
        : _value(il, static_cast<Args &&>(args)...)
        , _status(status_have_value)
    {
    }
    template <class U> static constexpr bool enable_converting_constructor = !std::is_same<std::decay_t<U>, value_type>::value && std::is_constructible<value_type, U>::value;
    BOOST_OUTCOME_TEMPLATE(class U)
    BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_converting_constructor<U>))
    constexpr explicit value_storage_trivial(const value_storage_trivial<U> &o) noexcept(std::is_nothrow_constructible<value_type, U>::value)
        : value_storage_trivial(((o._status & status_have_value) != 0) ? value_storage_trivial(in_place_type<value_type>, o._value) : value_storage_trivial())  // NOLINT
    {
      _status = o._status;
    }
    BOOST_OUTCOME_TEMPLATE(class U)
    BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_converting_constructor<U>))
    constexpr explicit value_storage_trivial(value_storage_trivial<U> &&o) noexcept(std::is_nothrow_constructible<value_type, U>::value)
        : value_storage_trivial(((o._status & status_have_value) != 0) ? value_storage_trivial(in_place_type<value_type>, static_cast<U &&>(o._value)) : value_storage_trivial())  // NOLINT
    {
      _status = o._status;
    }
    constexpr void swap(value_storage_trivial &o) noexcept
    {
      // storage is trivial, so just use assignment
      auto temp = static_cast<value_storage_trivial &&>(*this);
      *this = static_cast<value_storage_trivial &&>(o);
      o = static_cast<value_storage_trivial &&>(temp);
    }
  };
  // Used if T is non-trivial
  template <class T> struct value_storage_nontrivial
  {
    using value_type = T;
    union {
      empty_type _empty;
      value_type _value;
    };
    status_bitfield_type _status{0};
    value_storage_nontrivial() noexcept : _empty{} {}
    value_storage_nontrivial &operator=(const value_storage_nontrivial &) = default;                                        // if reaches here, copy assignment is trivial
    value_storage_nontrivial &operator=(value_storage_nontrivial &&) = default;                                             // NOLINT if reaches here, move assignment is trivial
    value_storage_nontrivial(value_storage_nontrivial &&o) noexcept(std::is_nothrow_move_constructible<value_type>::value)  // NOLINT
    : _status(o._status)
    {
      if(this->_status & status_have_value)
      {
        this->_status &= ~status_have_value;
        new(&_value) value_type(static_cast<value_type &&>(o._value));  // NOLINT
        _status = o._status;
      }
    }
    value_storage_nontrivial(const value_storage_nontrivial &o) noexcept(std::is_nothrow_copy_constructible<value_type>::value)
        : _status(o._status)
    {
      if(this->_status & status_have_value)
      {
        this->_status &= ~status_have_value;
        new(&_value) value_type(o._value);  // NOLINT
        _status = o._status;
      }
    }
    // Special from-void constructor, constructs default T if void valued
    explicit value_storage_nontrivial(const value_storage_trivial<void> &o) noexcept(std::is_nothrow_default_constructible<value_type>::value)
        : _status(o._status)
    {
      if(this->_status & status_have_value)
      {
        this->_status &= ~status_have_value;
        new(&_value) value_type;  // NOLINT
        _status = o._status;
      }
    }
    explicit value_storage_nontrivial(status_bitfield_type status)
        : _empty()
        , _status(status)
    {
    }
    template <class... Args>
    explicit value_storage_nontrivial(in_place_type_t<value_type> /*unused*/, Args &&... args) noexcept(std::is_nothrow_constructible<value_type, Args...>::value)
        : _value(static_cast<Args &&>(args)...)  // NOLINT
        , _status(status_have_value)
    {
    }
    template <class U, class... Args>
    value_storage_nontrivial(in_place_type_t<value_type> /*unused*/, std::initializer_list<U> il, Args &&... args) noexcept(std::is_nothrow_constructible<value_type, std::initializer_list<U>, Args...>::value)
        : _value(il, static_cast<Args &&>(args)...)
        , _status(status_have_value)
    {
    }
    template <class U> static constexpr bool enable_converting_constructor = !std::is_same<std::decay_t<U>, value_type>::value && std::is_constructible<value_type, U>::value;
    BOOST_OUTCOME_TEMPLATE(class U)
    BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_converting_constructor<U>))
    constexpr explicit value_storage_nontrivial(const value_storage_nontrivial<U> &o) noexcept(std::is_nothrow_constructible<value_type, U>::value)
        : value_storage_nontrivial((o._status & status_have_value) != 0 ? value_storage_nontrivial(in_place_type<value_type>, o._value) : value_storage_nontrivial())
    {
      _status = o._status;
    }
    BOOST_OUTCOME_TEMPLATE(class U)
    BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_converting_constructor<U>))
    constexpr explicit value_storage_nontrivial(const value_storage_trivial<U> &o) noexcept(std::is_nothrow_constructible<value_type, U>::value)
        : value_storage_nontrivial((o._status & status_have_value) != 0 ? value_storage_nontrivial(in_place_type<value_type>, o._value) : value_storage_nontrivial())
    {
      _status = o._status;
    }
    BOOST_OUTCOME_TEMPLATE(class U)
    BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_converting_constructor<U>))
    constexpr explicit value_storage_nontrivial(value_storage_nontrivial<U> &&o) noexcept(std::is_nothrow_constructible<value_type, U>::value)
        : value_storage_nontrivial((o._status & status_have_value) != 0 ? value_storage_nontrivial(in_place_type<value_type>, static_cast<U &&>(o._value)) : value_storage_nontrivial())
    {
      _status = o._status;
    }
    BOOST_OUTCOME_TEMPLATE(class U)
    BOOST_OUTCOME_TREQUIRES(BOOST_OUTCOME_TPRED(enable_converting_constructor<U>))
    constexpr explicit value_storage_nontrivial(value_storage_trivial<U> &&o) noexcept(std::is_nothrow_constructible<value_type, U>::value)
        : value_storage_nontrivial((o._status & status_have_value) != 0 ? value_storage_nontrivial(in_place_type<value_type>, static_cast<U &&>(o._value)) : value_storage_nontrivial())
    {
      _status = o._status;
    }
    ~value_storage_nontrivial() noexcept(std::is_nothrow_destructible<T>::value)
    {
      if(this->_status & status_have_value)
      {
        this->_value.~value_type();  // NOLINT
        this->_status &= ~status_have_value;
      }
    }
    constexpr void swap(value_storage_nontrivial &o) noexcept(detail::is_nothrow_swappable<value_type>::value &&std::is_nothrow_move_constructible<value_type>::value)
    {
      using std::swap;
      if((_status & status_have_value) == 0 && (o._status & status_have_value) == 0)
      {
        swap(_status, o._status);
        return;
      }
      if((_status & status_have_value) != 0 && (o._status & status_have_value) != 0)
      {
        swap(_value, o._value);  // NOLINT
        swap(_status, o._status);
        return;
      }
      // One must be empty and the other non-empty, so use move construction
      if((_status & status_have_value) != 0)
      {
        // Move construct me into other
        new(&o._value) value_type(static_cast<value_type &&>(_value));  // NOLINT
        this->_value.~value_type();                                     // NOLINT
        swap(_status, o._status);
      }
      else
      {
        // Move construct other into me
        new(&_value) value_type(static_cast<value_type &&>(o._value));  // NOLINT
        o._value.~value_type();                                         // NOLINT
        swap(_status, o._status);
      }
    }
  };
  template <class Base> struct value_storage_delete_copy_constructor : Base  // NOLINT
  {
    using Base::Base;
    using value_type = typename Base::value_type;
    value_storage_delete_copy_constructor() = default;
    value_storage_delete_copy_constructor(const value_storage_delete_copy_constructor &) = delete;
    value_storage_delete_copy_constructor(value_storage_delete_copy_constructor &&) = default;  // NOLINT
  };
  template <class Base> struct value_storage_delete_copy_assignment : Base  // NOLINT
  {
    using Base::Base;
    using value_type = typename Base::value_type;
    value_storage_delete_copy_assignment() = default;
    value_storage_delete_copy_assignment(const value_storage_delete_copy_assignment &) = default;
    value_storage_delete_copy_assignment(value_storage_delete_copy_assignment &&) = default;  // NOLINT
    value_storage_delete_copy_assignment &operator=(const value_storage_delete_copy_assignment &o) = delete;
    value_storage_delete_copy_assignment &operator=(value_storage_delete_copy_assignment &&o) = default;  // NOLINT
  };
  template <class Base> struct value_storage_delete_move_assignment : Base  // NOLINT
  {
    using Base::Base;
    using value_type = typename Base::value_type;
    value_storage_delete_move_assignment() = default;
    value_storage_delete_move_assignment(const value_storage_delete_move_assignment &) = default;
    value_storage_delete_move_assignment(value_storage_delete_move_assignment &&) = default;  // NOLINT
    value_storage_delete_move_assignment &operator=(const value_storage_delete_move_assignment &o) = default;
    value_storage_delete_move_assignment &operator=(value_storage_delete_move_assignment &&o) = delete;
  };
  template <class Base> struct value_storage_delete_move_constructor : Base  // NOLINT
  {
    using Base::Base;
    using value_type = typename Base::value_type;
    value_storage_delete_move_constructor() = default;
    value_storage_delete_move_constructor(const value_storage_delete_move_constructor &) = default;
    value_storage_delete_move_constructor(value_storage_delete_move_constructor &&) = delete;
  };
  template <class Base> struct value_storage_nontrivial_move_assignment : Base  // NOLINT
  {
    using Base::Base;
    using value_type = typename Base::value_type;
    value_storage_nontrivial_move_assignment() = default;
    value_storage_nontrivial_move_assignment(const value_storage_nontrivial_move_assignment &) = default;
    value_storage_nontrivial_move_assignment(value_storage_nontrivial_move_assignment &&) = default;  // NOLINT
    value_storage_nontrivial_move_assignment &operator=(const value_storage_nontrivial_move_assignment &o) = default;
    value_storage_nontrivial_move_assignment &operator=(value_storage_nontrivial_move_assignment &&o) noexcept(std::is_nothrow_move_assignable<value_type>::value)  // NOLINT
    {
      if((this->_status & status_have_value) != 0 && (o._status & status_have_value) != 0)
      {
        this->_value = static_cast<value_type &&>(o._value);  // NOLINT
      }
      else if((this->_status & status_have_value) != 0 && (o._status & status_have_value) == 0)
      {
        this->_value.~value_type();  // NOLINT
      }
      else if((this->_status & status_have_value) == 0 && (o._status & status_have_value) != 0)
      {
        new(&this->_value) value_type(static_cast<value_type &&>(o._value));  // NOLINT
      }
      this->_status = o._status;
      return *this;
    }
  };
  template <class Base> struct value_storage_nontrivial_copy_assignment : Base  // NOLINT
  {
    using Base::Base;
    using value_type = typename Base::value_type;
    value_storage_nontrivial_copy_assignment() = default;
    value_storage_nontrivial_copy_assignment(const value_storage_nontrivial_copy_assignment &) = default;
    value_storage_nontrivial_copy_assignment(value_storage_nontrivial_copy_assignment &&) = default;              // NOLINT
    value_storage_nontrivial_copy_assignment &operator=(value_storage_nontrivial_copy_assignment &&o) = default;  // NOLINT
    value_storage_nontrivial_copy_assignment &operator=(const value_storage_nontrivial_copy_assignment &o) noexcept(std::is_nothrow_copy_assignable<value_type>::value)
    {
      if((this->_status & status_have_value) != 0 && (o._status & status_have_value) != 0)
      {
        this->_value = o._value;  // NOLINT
      }
      else if((this->_status & status_have_value) != 0 && (o._status & status_have_value) == 0)
      {
        this->_value.~value_type();  // NOLINT
      }
      else if((this->_status & status_have_value) == 0 && (o._status & status_have_value) != 0)
      {
        new(&this->_value) value_type(o._value);  // NOLINT
      }
      this->_status = o._status;
      return *this;
    }
  };

  // We don't actually need all of std::is_trivial<>, std::is_trivially_copyable<> is sufficient
  template <class T> using value_storage_select_trivality = std::conditional_t<std::is_trivially_copyable<devoid<T>>::value, value_storage_trivial<T>, value_storage_nontrivial<T>>;
  template <class T> using value_storage_select_move_constructor = std::conditional_t<std::is_move_constructible<devoid<T>>::value, value_storage_select_trivality<T>, value_storage_delete_move_constructor<value_storage_select_trivality<T>>>;
  template <class T> using value_storage_select_copy_constructor = std::conditional_t<std::is_copy_constructible<devoid<T>>::value, value_storage_select_move_constructor<T>, value_storage_delete_copy_constructor<value_storage_select_move_constructor<T>>>;
  template <class T>
  using value_storage_select_move_assignment = std::conditional_t<std::is_trivially_move_assignable<devoid<T>>::value, value_storage_select_copy_constructor<T>,
                                                                  std::conditional_t<std::is_move_assignable<devoid<T>>::value, value_storage_nontrivial_move_assignment<value_storage_select_copy_constructor<T>>, value_storage_delete_copy_assignment<value_storage_select_copy_constructor<T>>>>;
  template <class T>
  using value_storage_select_copy_assignment = std::conditional_t<std::is_trivially_copy_assignable<devoid<T>>::value, value_storage_select_move_assignment<T>,
                                                                  std::conditional_t<std::is_copy_assignable<devoid<T>>::value, value_storage_nontrivial_copy_assignment<value_storage_select_move_assignment<T>>, value_storage_delete_copy_assignment<value_storage_select_move_assignment<T>>>>;
  template <class T> using value_storage_select_impl = value_storage_select_copy_assignment<T>;
#ifndef NDEBUG
  // Check is trivial in all ways except default constructibility
  // static_assert(std::is_trivial<value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not trivial!");
  // static_assert(std::is_trivially_default_constructible<value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not trivially default constructible!");
  static_assert(std::is_trivially_copyable<value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not trivially copyable!");
  static_assert(std::is_trivially_assignable<value_storage_select_impl<int>, value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not trivially assignable!");
  static_assert(std::is_trivially_destructible<value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not trivially destructible!");
  static_assert(std::is_trivially_copy_constructible<value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not trivially copy constructible!");
  static_assert(std::is_trivially_move_constructible<value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not trivially move constructible!");
  static_assert(std::is_trivially_copy_assignable<value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not trivially copy assignable!");
  static_assert(std::is_trivially_move_assignable<value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not trivially move assignable!");
  // Also check is standard layout
  static_assert(std::is_standard_layout<value_storage_select_impl<int>>::value, "value_storage_select_impl<int> is not a standard layout type!");
#endif
}  // namespace detail

BOOST_OUTCOME_V2_NAMESPACE_END

#endif