This class is a replacement for C++17 std::optional. More...

#include <cvb/shims/optional.hpp>

Public Member Functions
	optional () noexcept
	Default ctor not storing a value.

	optional (nullopt_t) noexcept
	Ctor for explicitly not storing a value.

template<class... ARGS>
	optional (in_place_t, ARGS &&... args)
	In-place constructs a new `T` object. More...

template<class U , typename std::enable_if< std::is_assignable< T &, U >::value, int >::type = 0>
	optional (U &&value)
	Ctor from an object assignable to `T`. More...

template<class U , typename std::enable_if< std::is_assignable< T &, U >::value, int >::type = 0>
optional &	operator= (U &&value)
	Assignment operator for an object assignable to `T`. More...

template<typename std::enable_if< std::is_copy_constructible< T >::value, int >::type = 0>
	optional (const optional &rhs)
	Copy ctor. More...

template<typename std::enable_if< std::is_copy_assignable< T >::value, int >::type = 0>
optional &	operator= (const optional &rhs)
	Copy operator. More...

template<typename std::enable_if< std::is_move_constructible< T >::value, int >::type = 0>
	optional (optional &&rhs)
	Move ctor. More...

template<typename std::enable_if< std::is_move_assignable< T >::value, int >::type = 0>
optional &	operator= (optional &&rhs)
	Move operator. More...

	~optional ()
	Dtor.

const T *	operator-> () const noexcept
	Gets the reference to the stored object. More...

T *	operator-> () noexcept
	Gets the reference to the stored object. More...

const T &	operator* () const noexcept
	Gets the reference to the stored object. More...

T &	operator* () noexcept
	Gets the reference to the stored object. More...

	operator bool () const noexcept
	Gets whether this optional contains a value. More...

template<class... ARGS>
T &	emplace (ARGS &&... args)
	Constructs a new `T` in-place. More...

bool	has_value () const noexcept
	Gets whether this optional contains a value. More...

void	reset ()
	Destroys any contained value.

void	swap (optional &other)
	Swaps this object with the other object. More...

const T &	value () const
	Gets the contained value. More...

T &	value ()
	Gets the contained value. More...

template<class U , typename std::enable_if< std::is_assignable< T &, U >::value, int >::type = 0>
T	value_or (U &&default_value) const
	Gets the contained value if has_value() is true; default_value otherwise. More...

Related Functions
(Note that these are not member functions.)
template<class T >
optional< typename std::decay< T >::type >	make_optional (T &&value)
	Factory function to create an optional from a `T` object. More...

template<class T , class... ARGS>
optional< T >	make_optional (ARGS &&... args)
	Factory function to in-place construct a `T` in an optional. More...

Detailed Description

template<class T>
class Cvb::Shims::optional< T >

This class is a replacement for C++17 std::optional.

Constructor & Destructor Documentation

◆ optional() [1/4]

optional	(	in_place_t	,
		ARGS &&...	args
	)

inline

In-place constructs a new T object.

Template Parameters

ARGS	Type list of all arguments to be forwarded to `T`.

Parameters

[in] args Arguments that are forwarded to the ctor of

◆ optional() [2/4]

optional ( U && value )

inline

Ctor from an object assignable to T.

Template Parameters

U	Type assignable to `T`.

Parameters

[in] value Value to store.

◆ optional() [3/4]

optional ( const optional< T > & rhs )

inline

Copy ctor.

Parameters

[in] rhs Object to copy.

◆ optional() [4/4]

optional ( optional< T > && rhs )

inline

Move ctor.

Parameters

[in] rhs Object to copy.

Member Function Documentation

◆ emplace()

T & emplace ( ARGS &&... args )

inline

Constructs a new T in-place.

If a this object has_value() is true, the old value is destroyed via its destructor.

Template Parameters

ARGS	Type list of all arguments to be forwarded to `T`.

Parameters

[in] args Command line arguments forwarded to the ctor of T.

Returns: Reference to the newly created object.

◆ has_value()

bool has_value ( ) const

inlinenoexcept

Gets whether this optional contains a value.

Returns: true if this object contains a value;

◆ operator bool()

operator bool ( ) const

inlineexplicitnoexcept

Gets whether this optional contains a value.

Returns: true if this object contains a value;

◆ operator*() [1/2]

const T & operator* ( ) const

inlinenoexcept

Gets the reference to the stored object.

Precondition: has_value() == true

Returns: Reference to the contained value.

◆ operator*() [2/2]

T & operator* ( )

inlinenoexcept

Gets the reference to the stored object.

Precondition: has_value() == true

Returns: Reference to the contained value.

◆ operator->() [1/2]

const T * operator-> ( ) const

inlinenoexcept

Gets the reference to the stored object.

Precondition: has_value() == true

Returns: Reference to the contained value.

◆ operator->() [2/2]

T * operator-> ( )

inlinenoexcept

Gets the reference to the stored object.

Precondition: has_value() == true

Returns: Reference to the contained value.

◆ operator=() [1/3]

optional & operator= ( const optional< T > & rhs )

inline

Copy operator.

Parameters

[in] rhs Object to copy.

Returns: Reference to this object.

◆ operator=() [2/3]

optional & operator= ( optional< T > && rhs )

inline

Move operator.

Parameters

[in] rhs Object to copy.

Returns: Reference to this object.

◆ operator=() [3/3]

optional & operator= ( U && value )

inline

Assignment operator for an object assignable to T.

Template Parameters

U	Type assignable to `T`.

Parameters

[in] value Value to store.

Returns: Reference to this object.

◆ swap()

void swap ( optional< T > & other )

inline

Swaps this object with the other object.

The contents of this and the other are swapped.

Parameters

[in] other Optional to swap value with.

◆ value() [1/2]

T & value ( )

inline

Gets the contained value.

Returns: Reference to the contained value.

Exceptions

bad_optional_access thrown if has_value() is false.

◆ value() [2/2]

const T & value ( ) const

inline

Gets the contained value.

Returns: Reference to the contained value.

Exceptions

bad_optional_access thrown if has_value() is false.

◆ value_or()

T value_or ( U && default_value ) const

inline

Gets the contained value if has_value() is true; default_value otherwise.

Returns: Either the contained value or the default_value.

Friends And Related Function Documentation

◆ make_optional() [1/2]

optional< T > make_optional ( ARGS &&... args )

Template Parameters

T	Type of value to store.
ARGS	Type list of all arguments to be forwarded to `T`.

Parameters

[in] args Arguments to be forwarded to the ctor of T.

Returns: optional with newly constructed T.

◆ make_optional() [2/2]

optional< typename std::decay< T >::type > make_optional ( T && value )

Template Parameters

T	Type of value to store.

Parameters

[in] value Value to be forwarded to the optional.

Returns: optional with the set value.

Public Member Functions

Related Functions

Detailed Description

Constructor & Destructor Documentation

◆ optional() [1/4]

◆ optional() [2/4]

◆ optional() [3/4]

◆ optional() [4/4]

Member Function Documentation

◆ emplace()

◆ has_value()

◆ operator bool()

◆ operator*() [1/2]

◆ operator*() [2/2]

◆ operator->() [1/2]

◆ operator->() [2/2]

◆ operator=() [1/3]

◆ operator=() [2/3]

◆ operator=() [3/3]

◆ swap()

◆ value() [1/2]

◆ value() [2/2]

◆ value_or()

Friends And Related Function Documentation

◆ make_optional() [1/2]

◆ make_optional() [2/2]