Template Class Unexpected

• Defined in File Expected.h

Class Documentation

template<typename E>
class Unexpected

The class template TRAP::Unexpected represents an unexpected value stored in TRAP::Expected. In particular, TRAP::Expected has constructors with TRAP::Unexpected as a single argument, which creates an expected object that contains an unexpected value.

A program is ill-formed if it instantiates an unexpected with a non-object type, an array type, a specialization of TRAP::Unexpected, or a cv-qualified type.

Template Parameters:

E – The type of the unexpected value. The type must not be an array type, a non-object type, a specialization of TRAP::Unexpected, or a cv-qualified type.

Public Functions

consteval Unexpected() = delete

Constructor. Constructs a TRAP::Unexpected object.

constexpr ~Unexpected() = default

Destructor. Destroys a TRAP::Unexpected object.

constexpr Unexpected(const Unexpected&) = default

Copy constructor. Constructs a TRAP::Unexpected object. Copies the stored value.

constexpr Unexpected(Unexpected&&) = default

Move constructor. Constructs a TRAP::Unexpected object. Moves the stored value.

constexpr Unexpected &operator=(const Unexpected&) = default

Copy assignment operator.

Returns:

*this.

constexpr Unexpected &operator=(Unexpected&&) = default

Move assignment operator.

Returns:

*this.

template<typename Err = E>
inline explicit constexpr Unexpected(Err &&e) noexcept(std::is_nothrow_constructible_v<E, Err>)

Constructs a TRAP::Unexpected object. Constructs the stored value, as if by direct-initializing a value of type E from std::forward<Err>(e).

Parameters:

e – Value with which to initialize the contained value.

template<typename ...Args>
inline explicit constexpr Unexpected(const std::in_place_t _, Args&&... args) noexcept(std::is_nothrow_constructible_v<E, Args...>)

Constructs a TRAP::Unexpected object. Constructs the stored value, as if by direct-initializing a value of type E from the arguments std::forward<Args>(args)….

Parameters:

args – Arguments with which to initialize the contained value.

template<typename U, typename ...Args>
inline explicit constexpr Unexpected(const std::in_place_t _, std::initializer_list<U> il, Args&&... args)

Constructs a TRAP::Unexpected object. Constructs the stored value, as if by direct-initializing a value of type E from the arguments il, std::forward<Args>(args)….

Parameters:

• il – Initializer list with which to initialize the contained value.

• args – Arguments with which to initialize the contained value.

inline constexpr const E &Error() const & noexcept

Retrieve a reference to the stored value.

Returns:

Reference to the stored value.

inline constexpr E &Error() & noexcept

Retrieve a reference to the stored value.

Returns:

Reference to the stored value.

inline constexpr const E &&Error() const && noexcept

Retrieve a reference to the stored value.

Returns:

Reference to the stored value.

inline constexpr E &&Error() && noexcept

Retrieve a reference to the stored value.

Returns:

Reference to the stored value.

inline constexpr void Swap(Unexpected &other) noexcept(std::is_nothrow_swappable_v<E>)

Swaps the stored values, as if by using std::swap; swap(Error(), other.Error());. The program is ill-formed if std::is_swappable_v<E> is false.

Friends

template<typename E2>
inline friend constexpr bool operator==(const Unexpected &x, const TRAP::Unexpected<E2> &y)

Compares the stored values, as if by return x.Error() == y.Error(). If the expression x.Error() == e.Error() is not well-formed, or if its result is not convertible to bool, the program is ill-formed.

Note

This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when TRAP::Unexpected<E> is an associated class of the arguments.

template<typename E2>
inline friend constexpr bool operator!=(const Unexpected &x, const TRAP::Unexpected<E2> &y)

Compares the stored values, as if by return x.Error() != y.Error(). If the expression x.Error() != e.Error() is not well-formed, or if its result is not convertible to bool, the program is ill-formed.

Note

This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when TRAP::Unexpected<E> is an associated class of the arguments.

inline friend constexpr void swap(Unexpected &lhs, Unexpected &rhs) noexcept(noexcept(lhs.Swap(rhs)))

Equivalent to x.Swap(y);.

Note

This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when TRAP::Unexpected<E> is an associated class of the arguments.