The class template optional manages an optional contained value, i.e. a value that may or may not be present. More...

#include <optional.hpp>

Public Types
using	value_type = T
	The underlying type of this Optional.

Public Member Functions
	optional (detail::enable_overload_if_t< std::is_copy_constructible< T >::value, const optional & > other)
	Copy constructs an optional. More...

	optional (detail::disable_overload_if_t< std::is_copy_constructible< T >::value, const optional & > other)=delete

	optional (detail::enable_overload_if_t< std::is_move_constructible< T >::value, optional && > other)
	Move constructs an optional. More...

	optional (detail::disable_overload_if_t< std::is_move_constructible< T >::value, optional && > other)=delete

template<typename... Args, typename = enable_if_t<std::is_constructible<T,Args...>::value>>
constexpr	optional (in_place_t, Args &&... args)
	Constructs an optional object that contains a value. More...

template<typename U , typename... Args, typename = enable_if_t<std::is_constructible<T, std::initializer_list<U>&, Args...>::value>>
constexpr	optional (in_place_t, std::initializer_list< U > ilist, Args &&...args)
	Constructs an optional object that contains a value. More...

optional &	operator= (nullopt_t)
	Assigns this optional to be a null optional. More...

optional &	operator= (detail::enable_overload_if_t< std::is_copy_constructible< T >::value &&std::is_copy_assignable< T >::value, const optional & > other)
	Copy assigns the optional stored in `other`. More...

optional &	operator= (detail::disable_overload_if_t< std::is_copy_constructible< T >::value &&std::is_copy_assignable< T >::value, const optional & > other)=delete

optional &	operator= (detail::enable_overload_if_t< std::is_move_constructible< T >::value &&std::is_move_assignable< T >::value, optional && > other)
	Move assigns the optional stored in `other`. More...

optional &	operator= (detail::disable_overload_if_t< std::is_move_constructible< T >::value &&std::is_move_assignable< T >::value, optional && > other)=delete

template<typename U = T, typename = enable_if_t<detail::optional_is_value_assignable<T,U>::value>>
optional &	operator= (U &&value)
	Perfect-forwarded assignment. More...

template<typename U >
optional &	operator= (enable_if_t< detail::optional_is_copy_convert_assignable< T, U >::value, const optional< U > & > other)
	Assigns the state of `other`. More...

template<typename U >
optional &	operator= (enable_if_t< detail::optional_is_move_convert_assignable< T, U >::value, optional< U > && > other)
	Assigns the state of `other`. More...

constexpr	operator bool () const noexcept
	Checks whether `*this` contains a value. More...

constexpr bool	has_value () const noexcept
	Checks whether `*this` contains a value. More...

void	swap (optional &other)
	Swaps the contents with those of other. More...

void	reset () noexcept(std::is_nothrow_destructible< T >::value)
	If `*this` contains a value, destroy that value as if by `value()`.T::~T(). More...

template<typename... Args>
void	emplace (Args &&...args)
	Constructs the contained value in-place. More...

template<typename U , typename... Args>
void	emplace (std::initializer_list< U > ilist, Args &&...args)
	Constructs the contained value in-place. More...

template<typename U , bpstd::enable_if_t< bpstd::detail::optional_is_copy_convertible< T, U >::value &&std::is_convertible< const U &, T >::value > * >
BPSTD_INLINE_VISIBILITY	optional (const optional< U > &other)

template<typename U , bpstd::enable_if_t< bpstd::detail::optional_is_move_convertible< T, U >::value &&std::is_convertible< U &&, T >::value > * >
BPSTD_INLINE_VISIBILITY	optional (optional< U > &&other)

template<typename... Args, typename >
constexpr BPSTD_INLINE_VISIBILITY	optional (in_place_t, Args &&...args)

template<typename U , typename... Args, typename >
constexpr BPSTD_INLINE_VISIBILITY	optional (in_place_t, std::initializer_list< U > ilist, Args &&...args)

template<typename U , bpstd::enable_if_t< bpstd::detail::optional_is_value_convertible< T, U >::value &&std::is_convertible< U &&, T >::value > * >
constexpr BPSTD_INLINE_VISIBILITY	optional (U &&value)

template<typename U , typename >
BPSTD_INLINE_VISIBILITY bpstd::optional< T > &	operator= (U &&value)

template<typename U >
constexpr BPSTD_INLINE_VISIBILITY bpstd::optional< T >::value_type	value_or (U &&default_value) const &

template<typename U >
BPSTD_INLINE_VISIBILITY BPSTD_CPP14_CONSTEXPR bpstd::optional< T >::value_type	value_or (U &&default_value) &&

template<typename... Args>
BPSTD_INLINE_VISIBILITY void	emplace (Args &&...args)

template<typename U , typename... Args>
BPSTD_INLINE_VISIBILITY void	emplace (std::initializer_list< U > ilist, Args &&...args)


constexpr	optional () noexcept
	Constructs an optional that does not contain a value.

constexpr	optional (nullopt_t) noexcept
	Constructs an optional that does not contain a value.


template<typename U , enable_if_t< detail::optional_is_copy_convertible< T, U >::value &&std::is_convertible< const U &, T >::value > * = nullptr>
	optional (const optional< U > &other)
	Converting copy constructor. More...

template<typename U , enable_if_t< detail::optional_is_copy_convertible< T, U >::value &&!std::is_convertible< const U &, T >::value > * = nullptr>
	optional (const optional< U > &other)
	Converting copy constructor. More...


template<typename U , enable_if_t< detail::optional_is_move_convertible< T, U >::value &&std::is_convertible< U &&, T >::value > * = nullptr>
	optional (optional< U > &&other)
	Converting move constructor. More...

template<typename U , enable_if_t< detail::optional_is_move_convertible< T, U >::value &&!std::is_convertible< U &&, T >::value > * = nullptr>
	optional (optional< U > &&other)
	Converting move constructor. More...


template<typename U = T, enable_if_t< detail::optional_is_value_convertible< T, U >::value &&std::is_convertible< U &&, T >::value > * = nullptr>
constexpr	optional (U &&value)
	Constructs an optional object that contains a value. More...

template<typename U = T, enable_if_t< detail::optional_is_value_convertible< T, U >::value &&!std::is_convertible< U &&, T >::value > * = nullptr>
constexpr	optional (U &&value)
	Constructs an optional object that contains a value. More...


BPSTD_CPP14_CONSTEXPR value_type *	operator-> () noexcept
	Accesses the contained value. More...

constexpr const value_type *	operator-> () const noexcept
	Accesses the contained value. More...


BPSTD_CPP14_CONSTEXPR value_type &	operator* () &noexcept
	Accesses the contained value. More...

BPSTD_CPP14_CONSTEXPR value_type &&	operator* () &&noexcept
	Accesses the contained value. More...

constexpr const value_type &	operator* () const &noexcept
	Accesses the contained value. More...

constexpr const value_type &&	operator* () const &&noexcept
	Accesses the contained value. More...


BPSTD_CPP14_CONSTEXPR value_type &	value () &
	Returns the contained value. More...

BPSTD_CPP14_CONSTEXPR value_type &&	value () &&
	Returns the contained value. More...


const BPSTD_CPP14_CONSTEXPR value_type &	value () const &
	Returns the contained value. More...

const BPSTD_CPP14_CONSTEXPR value_type &&	value () const &&
	Returns the contained value. More...


template<typename U >
constexpr value_type	value_or (U &&default_value) const &
	Returns the contained value if `*this` has a value, otherwise returns `default_value`. More...

template<typename U >
BPSTD_CPP14_CONSTEXPR value_type	value_or (U &&default_value) &&
	Returns the contained value if `*this` has a value, otherwise returns `default_value`. More...

Detailed Description

template<typename T>
class bpstd::optional< T >

The class template optional manages an optional contained value, i.e. a value that may or may not be present.

A common use case for optional is the return value of a function that may fail. As opposed to other approaches, such as std::pair<T,bool>, optional handles expensive to construct objects well and is more readable, as the intent is expressed explicitly.

Any instance of optional<T> at any given point in time either contains a value or does not contain a value.

If an optional<T> contains a value, the value is guaranteed to be allocated as part of the optional object footprint, i.e. no dynamic memory allocation ever takes place. Thus, an optional object models an object, not a pointer, even though the operator*() and operator->() are defined.

When an object of type optional<T> is contextually converted to bool, the conversion returns true if the object contains a value and false if it does not contain a value.

The optional object contains a value in the following conditions:

The object is initialized with a value of type T
The object is assigned from another optional that contains a value.
The object does not contain a value in the following conditions:
The object is default-initialized.
The object is initialized with a value of nullopt_t or an optional object that does not contain a value.
The object is assigned from a value of nullopt_t or from an optional that does not contain a value

Template Parameters

T	the underlying type

Definition at line 53 of file optional.hpp.

Constructor & Destructor Documentation

◆ optional() [1/10]

template<typename T >

BPSTD_INLINE_VISIBILITY bpstd::optional< T >::optional ( detail::enable_overload_if_t< std::is_copy_constructible< T >::value, const optional< T > & > other )

inline

Copy constructs an optional.

If other contains a value, initializes the contained value as if direct-initializing (but not direct-list-initializing) an object of type T with the expression *other.

If other does not contain a value, constructs an object that does not contain a value.

Note: This constructor is defined as deleted if std::is_copy_constructible_v<T> is false

Parameters

other the optional to copy

Definition at line 1084 of file optional.hpp.

◆ optional() [2/10]

template<typename T >

BPSTD_INLINE_VISIBILITY bpstd::optional< T >::optional ( detail::enable_overload_if_t< std::is_move_constructible< T >::value, optional< T > && > other )

inline

Move constructs an optional.

If other contains a value, initializes the contained value as if direct-initializing (but not direct-list-initializing) an object of type T with the expression std::move(*other) and does not make other empty: a moved-from optional still contains a value, but the value itself is moved from.

If other does not contain a value, constructs an object that does not contain a value.

Note: This constructor is defined as deleted if std::is_move_constructible_v<T> is false

Parameters

other the optional to move

Definition at line 1096 of file optional.hpp.

◆ optional() [3/10]

template<typename T >

template<typename U , enable_if_t< detail::optional_is_copy_convertible< T, U >::value &&std::is_convertible< const U &, T >::value > * = nullptr>

bpstd::optional< T >::optional ( const optional & other )

Converting copy constructor.

If other doesn't contain a value, constructs an optional object that does not contain a value. Otherwise, constructs an optional object that contains a value, initialized as if direct-initializing (but not direct-list-initializing) an object of type T with the expression *other.

Note

This constructor does not participate in overload resolution unless the following conditions are met:

std::is_constructible_v<T, const U&> is true
T is not constructible or convertible from any expression of type (possibly const) optional
, i.e., the following 8 type traits are all false:
- std::is_constructible_v<T, std::optional&>
- std::is_constructible_v<T, const std::optional&>
- std::is_constructible_v<T, std::optional&&>
- std::is_constructible_v<T, const std::optional&&>
- std::is_convertible_v<std::optional&, T>
- std::is_convertible_v<const std::optional&, T>
- std::is_convertible_v<std::optional&&, T>
- std::is_convertible_v<const std::optional&&, T>

This constructor is explicit if and only if std::is_convertible_v<const U&, T> is false

Parameters

other the other type to convert

◆ optional() [4/10]

template<typename T >

template<typename U , enable_if_t< detail::optional_is_copy_convertible< T, U >::value &&!std::is_convertible< const U &, T >::value > * = nullptr>

bpstd::optional< T >::optional ( const optional & other )

explicit

Converting copy constructor.

If other doesn't contain a value, constructs an optional object that does not contain a value. Otherwise, constructs an optional object that contains a value, initialized as if direct-initializing (but not direct-list-initializing) an object of type T with the expression *other.

Note

This constructor does not participate in overload resolution unless the following conditions are met:

std::is_constructible_v<T, const U&> is true
T is not constructible or convertible from any expression of type (possibly const) optional
, i.e., the following 8 type traits are all false:
- std::is_constructible_v<T, std::optional&>
- std::is_constructible_v<T, const std::optional&>
- std::is_constructible_v<T, std::optional&&>
- std::is_constructible_v<T, const std::optional&&>
- std::is_convertible_v<std::optional&, T>
- std::is_convertible_v<const std::optional&, T>
- std::is_convertible_v<std::optional&&, T>
- std::is_convertible_v<const std::optional&&, T>

This constructor is explicit if and only if std::is_convertible_v<const U&, T> is false

Parameters

other the other type to convert

◆ optional() [5/10]

template<typename T >

template<typename U , enable_if_t< detail::optional_is_move_convertible< T, U >::value &&std::is_convertible::value > * = nullptr>

bpstd::optional< T >::optional ( optional && other )

Converting move constructor.

If other doesn't contain a value, constructs an optional object that does not contain a value. Otherwise, constructs an optional object that contains a value, initialized as if direct-initializing (but not direct-list-initializing) an object of type T with the expression std::move(*other).

Note

This constructor does not participate in overload resolution unless the following conditions are met:

std::is_constructible_v<T, U&&> is true
T is not constructible or convertible from any expression of type (possibly const) optional
, i.e., the following 8 type traits are all false:
- std::is_constructible_v<T, std::optional&>
- std::is_constructible_v<T, const std::optional&>
- std::is_constructible_v<T, std::optional&&>
- std::is_constructible_v<T, const std::optional&&>
- std::is_convertible_v<std::optional&, T>
- std::is_convertible_v<const std::optional&, T>
- std::is_convertible_v<std::optional&&, T>
- std::is_convertible_v<const std::optional&&, T>

This constructor is explicit if and only if std::is_convertible_v<U&&, T> is false

Parameters

other the other optional to move

◆ optional() [6/10]

template<typename T >

template<typename U , enable_if_t< detail::optional_is_move_convertible< T, U >::value &&!std::is_convertible::value > * = nullptr>

bpstd::optional< T >::optional ( optional && other )

explicit

Converting move constructor.

If other doesn't contain a value, constructs an optional object that does not contain a value. Otherwise, constructs an optional object that contains a value, initialized as if direct-initializing (but not direct-list-initializing) an object of type T with the expression std::move(*other).

Note

This constructor does not participate in overload resolution unless the following conditions are met:

std::is_constructible_v<T, U&&> is true
T is not constructible or convertible from any expression of type (possibly const) optional
, i.e., the following 8 type traits are all false:
- std::is_constructible_v<T, std::optional&>
- std::is_constructible_v<T, const std::optional&>
- std::is_constructible_v<T, std::optional&&>
- std::is_constructible_v<T, const std::optional&&>
- std::is_convertible_v<std::optional&, T>
- std::is_convertible_v<const std::optional&, T>
- std::is_convertible_v<std::optional&&, T>
- std::is_convertible_v<const std::optional&&, T>

This constructor is explicit if and only if std::is_convertible_v<U&&, T> is false

Parameters

other the other optional to move

◆ optional() [7/10]

template<typename T >

template<typename... Args, typename = enable_if_t<std::is_constructible<T,Args...>::value>>

constexpr bpstd::optional< T >::optional	(	in_place_t	,
		Args &&...	args
	)

explicitconstexpr

Constructs an optional object that contains a value.

the value is initialized as if direct-initializing (but not direct-list-initializing) an object of type T from the arguments std::forward<Args>(args)...

Parameters

args	the arguments to pass to T's constructor

◆ optional() [8/10]

template<typename T >

template<typename U , typename... Args, typename = enable_if_t<std::is_constructible<T, std::initializer_list&, Args...>::value>>

constexpr bpstd::optional< T >::optional	(	in_place_t	,
		std::initializer_list< U >	ilist,
		Args &&...	args
	)

explicitconstexpr

Constructs an optional object that contains a value.

The value is initialized as if direct-initializing (but not direct-list-initializing) an object of type T from the arguments std::forward<std::initializer_list>(ilist), std::forward<Args>(args)...

Parameters

ilist	An initializer list of entries to forward
args	the arguments to pass to T's constructor

◆ optional() [9/10]

template<typename T >

template<typename U = T, enable_if_t< detail::optional_is_value_convertible< T, U >::value &&std::is_convertible::value > * = nullptr>

constexpr bpstd::optional< T >::optional ( U && value )

constexpr

Constructs an optional object that contains a value.

The value is initialized as if direct-initializing (but not direct-list-initializing) an object of type T with the expression value.

Note: This constructor is constexpr if the constructor of T selected by direct-initialization is constexpr; This constructor does not participate in overload resolution unless std::is_constructible_v<T, U&&> is true and decay_t is neither std::in_place_t nor optional<T>.; This constructor is explicit if and only if std::is_convertible_v<U&&, T> is false

Parameters

value the value to copy

◆ optional() [10/10]

template<typename T >

template<typename U = T, enable_if_t< detail::optional_is_value_convertible< T, U >::value &&!std::is_convertible::value > * = nullptr>

constexpr bpstd::optional< T >::optional ( U && value )

explicitconstexpr

Constructs an optional object that contains a value.

The value is initialized as if direct-initializing (but not direct-list-initializing) an object of type T with the expression value.

Note: This constructor is constexpr if the constructor of T selected by direct-initialization is constexpr; This constructor does not participate in overload resolution unless std::is_constructible_v<T, U&&> is true and decay_t is neither std::in_place_t nor optional<T>.; This constructor is explicit if and only if std::is_convertible_v<U&&, T> is false

Parameters

value the value to copy

Member Function Documentation

◆ emplace() [1/2]

template<typename T >

template<typename... Args>

void bpstd::optional< T >::emplace ( Args &&... args )

Constructs the contained value in-place.

If *this already contains a value before the call, the contained value is destroyed by calling its destructor.

Parameters

args	the arguments to pass to the constructor

◆ emplace() [2/2]

template<typename T >

template<typename U , typename... Args>

void bpstd::optional< T >::emplace	(	std::initializer_list< U >	ilist,
		Args &&...	args
	)

Constructs the contained value in-place.

If *this already contains a value before the call, the contained value is destroyed by calling its destructor.

Parameters

ilist	the initializer list to pass to the constructor
args	the arguments to pass to the constructor

◆ has_value()

template<typename T >

constexpr BPSTD_INLINE_VISIBILITY bool bpstd::optional< T >::has_value

inlineconstexprnoexcept

Checks whether *this contains a value.

Returns: true if *this contains a value, false if *this does not contain a value

Definition at line 1270 of file optional.hpp.

◆ operator bool()

template<typename T >

constexpr BPSTD_INLINE_VISIBILITY bpstd::optional< T >::operator bool

inlineexplicitconstexprnoexcept

Checks whether *this contains a value.

Returns: true if *this contains a value, false if *this does not contain a value

Definition at line 1262 of file optional.hpp.

◆ operator*() [1/4]

template<typename T >

BPSTD_CPP14_CONSTEXPR value_type&& bpstd::optional< T >::operator* ( ) &&

noexcept

Accesses the contained value.

Note: The behaviour is undefined if *this does not contain a value

Returns: a reference to the contained value

◆ operator*() [2/4]

template<typename T >

constexpr const BPSTD_INLINE_VISIBILITY bpstd::optional< T >::value_type && bpstd::optional< T >::operator*

inlineconstexprnoexcept

Accesses the contained value.

Note: The behaviour is undefined if *this does not contain a value

Returns: a reference to the contained value

Definition at line 1301 of file optional.hpp.

◆ operator*() [3/4]

template<typename T >

constexpr const value_type&& bpstd::optional< T >::operator* ( ) const &&

constexprnoexcept

Accesses the contained value.

Note: The behaviour is undefined if *this does not contain a value

Returns: a reference to the contained value

◆ operator*() [4/4]

template<typename T >

constexpr const value_type& bpstd::optional< T >::operator* ( ) const &

constexprnoexcept

Accesses the contained value.

Note: The behaviour is undefined if *this does not contain a value

Returns: a reference to the contained value

◆ operator->() [1/2]

template<typename T >

constexpr const value_type* bpstd::optional< T >::operator-> ( ) const

constexprnoexcept

Accesses the contained value.

Note: The behavior is undefined if *this does not contain a value.

Returns: a pointer to the contained value

◆ operator->() [2/2]

template<typename T >

constexpr const BPSTD_INLINE_VISIBILITY bpstd::optional< T >::value_type * bpstd::optional< T >::operator->

inlineconstexprnoexcept

Accesses the contained value.

Note: The behavior is undefined if *this does not contain a value.

Returns: a pointer to the contained value

Definition at line 1281 of file optional.hpp.

◆ operator=() [1/6]

template<typename T >

BPSTD_INLINE_VISIBILITY bpstd::optional< T > & bpstd::optional< T >::operator= ( detail::enable_overload_if_t< std::is_copy_constructible< T >::value &&std::is_copy_assignable< T >::value, const optional< T > & > other )

inline

Copy assigns the optional stored in other.

Parameters

other the other optional to copy

Definition at line 1214 of file optional.hpp.

◆ operator=() [2/6]

template<typename T >

BPSTD_INLINE_VISIBILITY bpstd::optional< T > & bpstd::optional< T >::operator= ( detail::enable_overload_if_t< std::is_move_constructible< T >::value &&std::is_move_assignable< T >::value, optional< T > && > other )

inline

Move assigns the optional stored in other.

Note: If other contained a value before the call, it is left as a null optional

Remarks: This assignment does not participate in overload resolution unless U is

Parameters

other the other optional to move

Definition at line 1230 of file optional.hpp.

◆ operator=() [3/6]

template<typename T >

template<typename U >

optional& bpstd::optional< T >::operator= ( enable_if_t< detail::optional_is_copy_convert_assignable< T, U >::value, const optional & > other )

Assigns the state of other.

If both *this and other do not contain a value, the function has no effect.

If *this contains a value, but other does not, then the contained value is destroyed by calling its destructor. *this does not contain a value after the call.

If other contains a value, then depending on whether *this contains a value, the contained value is either direct-initialized or assigned from *other.

Note

A moved-from optional still contains a value.

This overload does not participate in overload resolution unless the following conditions are met:

std::is_constructible_v<T, const U&> and std::is_assignable_v<T&, const U&> are both true.
T is not constructible, convertible, or assignable from any expression of type (possibly const) :optional
, i.e., the following 12 type traits are all false:
- std::is_constructible_v<T, std::optional&>
- std::is_constructible_v<T, const std::optional&>
- std::is_constructible_v<T, std::optional&&>
- std::is_constructible_v<T, const std::optional&&>
- std::is_convertible_v<std::optional&, T>
- std::is_convertible_v<const std::optional&, T>
- std::is_convertible_v<std::optional&&, T>
- std::is_convertible_v<const std::optional&&, T>
- std::is_assignable_v<T&, std::optional&>
- std::is_assignable_v<T&, const std::optional&>
- std::is_assignable_v<T&, std::optional&&>
- std::is_assignable_v<T&, const std::optional&&>.

Parameters

other another optional object whose contained value to assign

Returns: reference to (*this)

◆ operator=() [4/6]

template<typename T >

template<typename U >

optional& bpstd::optional< T >::operator= ( enable_if_t< detail::optional_is_move_convert_assignable< T, U >::value, optional && > other )

Assigns the state of other.

If both *this and other do not contain a value, the function has no effect.

If *this contains a value, but other does not, then the contained value is destroyed by calling its destructor. *this does not contain a value after the call.

If other contains a value, then depending on whether *this contains a value, the contained value is either direct-initialized or assigned from std::move(*other).

Note

A moved-from optional still contains a value.

This overload does not participate in overload resolution unless the following conditions are met:

std::is_constructible_v<T, U&&> and std::is_assignable_v<T&, U&&> are both true.
T is not constructible, convertible, or assignable from any expression of type (possibly const) :optional
, i.e., the following 12 type traits are all false:
- std::is_constructible_v<T, std::optional&>
- std::is_constructible_v<T, const std::optional&>
- std::is_constructible_v<T, std::optional&&>
- std::is_constructible_v<T, const std::optional&&>
- std::is_convertible_v<std::optional&, T>
- std::is_convertible_v<const std::optional&, T>
- std::is_convertible_v<std::optional&&, T>
- std::is_convertible_v<const std::optional&&, T>
- std::is_assignable_v<T&, std::optional&>
- std::is_assignable_v<T&, const std::optional&>
- std::is_assignable_v<T&, std::optional&&>
- std::is_assignable_v<T&, const std::optional&&>.

Parameters

other another optional object whose contained value to assign

Returns: reference to (*this)

◆ operator=() [5/6]

template<typename T >

BPSTD_INLINE_VISIBILITY bpstd::optional< T > & bpstd::optional< T >::operator= ( nullopt_t )

inline

Assigns this optional to be a null optional.

If (*this) had a value before the call, the contained value is destroyed.

Definition at line 1205 of file optional.hpp.

◆ operator=() [6/6]

template<typename T >

template<typename U = T, typename = enable_if_t<detail::optional_is_value_assignable<T,U>::value>>

optional& bpstd::optional< T >::operator= ( U && value )

Perfect-forwarded assignment.

Depending on whether *this contains a value before the call, the contained value is either direct-initialized from std::forward(value) or assigned from std::forward(value).

Note

The function does not participate in overload resolution unless

decay_t is not optional<T>,
std::is_constructible_v<T, U> is true
std::is_assignable_v<T&, U> is true
and at least one of the following is true:
- T is not a scalar type;
- decay_t is not T.

Parameters

value to assign to the contained value

Returns: reference to (*this)

◆ reset()

template<typename T >

BPSTD_INLINE_VISIBILITY void bpstd::optional< T >::reset

inlinenoexcept

If *this contains a value, destroy that value as if by value().T::~T().

Otherwise, there are no effects. *this does not contain a value after this call.

Definition at line 1428 of file optional.hpp.

◆ swap()

template<typename T >

BPSTD_INLINE_VISIBILITY void bpstd::optional< T >::swap ( optional< T > & other )

inline

Swaps the contents with those of other.

Parameters

other the optional object to exchange the contents with

Definition at line 1411 of file optional.hpp.

◆ value() [1/4]

template<typename T >

BPSTD_INLINE_VISIBILITY const BPSTD_CPP14_CONSTEXPR bpstd::optional< T >::value_type && bpstd::optional< T >::value

inline

Returns the contained value.

Exceptions

bad_optional_access if *this does not contain a value.

Returns: the value of *this

Definition at line 1339 of file optional.hpp.

◆ value() [2/4]

template<typename T >

BPSTD_CPP14_CONSTEXPR value_type&& bpstd::optional< T >::value ( ) &&

Returns the contained value.

Exceptions

bad_optional_access if *this does not contain a value.

Returns: the value of *this

◆ value() [3/4]

template<typename T >

const BPSTD_CPP14_CONSTEXPR value_type& bpstd::optional< T >::value ( ) const &

Returns the contained value.

Exceptions

bad_optional_access if *this does not contain a value.

Returns: the value of *this

◆ value() [4/4]

template<typename T >

const BPSTD_CPP14_CONSTEXPR value_type&& bpstd::optional< T >::value ( ) const &&

Returns the contained value.

Exceptions

bad_optional_access if *this does not contain a value.

Returns: the value of *this

◆ value_or() [1/2]

template<typename T >

template<typename U >

BPSTD_CPP14_CONSTEXPR value_type bpstd::optional< T >::value_or ( U && default_value ) &&

Returns the contained value if *this has a value, otherwise returns default_value.

Parameters

default_value the value to use in case *this is empty

Returns: the value to use in case *this is empty

◆ value_or() [2/2]

template<typename T >

template<typename U >

constexpr value_type bpstd::optional< T >::value_or ( U && default_value ) const &

constexpr

Returns the contained value if *this has a value, otherwise returns default_value.

Parameters

default_value the value to use in case *this is empty

Returns: the value to use in case *this is empty

The documentation for this class was generated from the following file:

include/bpstd/optional.hpp

Public Types

Public Member Functions

Detailed Description

template<typename T> class bpstd::optional< T >

Constructor & Destructor Documentation

◆ optional() [1/10]

◆ optional() [2/10]

◆ optional() [3/10]

◆ optional() [4/10]

◆ optional() [5/10]

◆ optional() [6/10]

◆ optional() [7/10]

◆ optional() [8/10]

◆ optional() [9/10]

◆ optional() [10/10]

Member Function Documentation

◆ emplace() [1/2]

◆ emplace() [2/2]

◆ has_value()

◆ operator bool()

◆ operator*() [1/4]

◆ operator*() [2/4]

◆ operator*() [3/4]

◆ operator*() [4/4]

◆ operator->() [1/2]

◆ operator->() [2/2]

◆ operator=() [1/6]

◆ operator=() [2/6]

◆ operator=() [3/6]

◆ operator=() [4/6]

◆ operator=() [5/6]

◆ operator=() [6/6]

◆ reset()

◆ swap()

◆ value() [1/4]

◆ value() [2/4]

◆ value() [3/4]

◆ value() [4/4]

◆ value_or() [1/2]

◆ value_or() [2/2]

template<typename T>
class bpstd::optional< T >