TVariant< T, Ts > Class Template Reference

#include <TVariant.h>

Inheritance diagram for TVariant< T, Ts >:

Public Member Functions
	TVariant ()
template<typename U , typename... ArgTypes>
	TVariant (TInPlaceType< U > &&, ArgTypes &&... Args)
	TVariant (const TVariant &Other)
	TVariant (TVariant &&Other)
TVariant &	operator= (const TVariant &Other)
TVariant &	operator= (TVariant &&Other)
	~TVariant ()=default
template<typename U >
bool	IsType () const
template<typename U >
U &	Get () UE_LIFETIMEBOUND
template<typename U >
const U &	Get () const UE_LIFETIMEBOUND
template<typename U >
const U &	Get (const TIdentity_T< U > &DefaultValue UE_LIFETIMEBOUND) const UE_LIFETIMEBOUND
template<typename U >
U *	TryGet () UE_LIFETIMEBOUND
template<typename U >
const U *	TryGet () const UE_LIFETIMEBOUND
template<typename U >
void	Set (typename TIdentity< U >::Type &&Value)
template<typename U >
void	Set (const typename TIdentity< U >::Type &Value)
template<typename U , typename... ArgTypes>
void	Emplace (ArgTypes &&... Args)
SIZE_T	GetIndex () const
template<typename U >
	TVariant (UE::Core::Private::TUninitializedType< U > &&)

Static Public Member Functions
template<typename U >
static constexpr SIZE_T	IndexOfType ()

Detailed Description

template<typename T, typename... Ts>
class TVariant< T, Ts >

A type-safe union based loosely on std::variant. This flavor of variant requires that all the types in the declaring template parameter pack be unique. Attempting to use the value of a Get() when the underlying type is different leads to undefined behavior.

Constructor & Destructor Documentation

TVariant() [1/5]

template<typename T , typename... Ts>

TVariant< T, Ts >::TVariant ( )

inline

Default initialize the TVariant to the first type in the parameter pack

TVariant() [2/5]

template<typename T , typename... Ts>

template<typename U , typename... ArgTypes>

TVariant< T, Ts >::TVariant ( TInPlaceType< U > &&  , ArgTypes &&...  Args  )

inlineexplicit

Perform in-place construction of a type into the variant

TVariant() [3/5]

template<typename T , typename... Ts>

TVariant< T, Ts >::TVariant ( const TVariant< T, Ts > &  Other )

inline

Copy construct the variant from another variant of the same type

TVariant() [4/5]

template<typename T , typename... Ts>

TVariant< T, Ts >::TVariant ( TVariant< T, Ts > &&  Other )

inline

Move construct the variant from another variant of the same type

~TVariant()

template<typename T , typename... Ts>

TVariant< T, Ts >::~TVariant ( )

default

TVariant() [5/5]

template<typename T , typename... Ts>

template<typename U >

TVariant< T, Ts >::TVariant ( UE::Core::Private::TUninitializedType< U > &&  )

inlineexplicit

INTERNAL USE ONLY – Do not call this constructor, it will put the variant in a bad state. Its internal use case is for in-place construction of non-default-constructible types during serialization.

Construct the TVariant to store the specified uninitialized element type. The caller must unconditionally get a pointer to the element and construct an object of the right type in that position. This is all totally exception-unsafe. This relies on undefined behavior by dereferencing a pointer to an object (inside Get) that doesn't exist, and then turning it back to an pointer. Any other attempts to use or destroy the variant before an object of the right type has been constructed is completely unsafe, it may e.g. result in trying to destroy an object that is not there.

Member Function Documentation

Emplace()

template<typename T , typename... Ts>

template<typename U , typename... ArgTypes>

void TVariant< T, Ts >::Emplace ( ArgTypes &&...  Args )

inline

Set a specifically-typed value into the variant using in-place construction

Get() [1/3]

template<typename T , typename... Ts>

template<typename U >

const U & TVariant< T, Ts >::Get ( ) const

inline

Get a reference to the held value. Bad things can happen if this is called on a variant that does not hold the type asked for

Get() [2/3]

template<typename T , typename... Ts>

template<typename U >

U & TVariant< T, Ts >::Get ( )

inline

Get a reference to the held value. Bad things can happen if this is called on a variant that does not hold the type asked for

Get() [3/3]

template<typename T , typename... Ts>

template<typename U >

const U & TVariant< T, Ts >::Get ( const TIdentity_T< U > &DefaultValue  UE_LIFETIMEBOUND ) const

inline

Get a reference to the held value if set, otherwise the DefaultValue

GetIndex()

template<typename T , typename... Ts>

SIZE_T TVariant< T, Ts >::GetIndex ( ) const

inline

Returns the currently held type's index into the template parameter pack

IndexOfType()

template<typename T , typename... Ts>

template<typename U >

static constexpr SIZE_T TVariant< T, Ts >::IndexOfType ( )

inlinestaticconstexpr

Lookup the index of a type in the template parameter pack at compile time.

IsType()

template<typename T , typename... Ts>

template<typename U >

bool TVariant< T, Ts >::IsType ( ) const

inline

Determine if the variant holds the specific type

operator=() [1/2]

template<typename T , typename... Ts>

TVariant & TVariant< T, Ts >::operator= ( const TVariant< T, Ts > &  Other )

inline

Copy assign a variant from another variant of the same type

operator=() [2/2]

template<typename T , typename... Ts>

TVariant & TVariant< T, Ts >::operator= ( TVariant< T, Ts > &&  Other )

inline

Move assign a variant from another variant of the same type

Set() [1/2]

template<typename T , typename... Ts>

template<typename U >

void TVariant< T, Ts >::Set ( const typename TIdentity< U >::Type &  Value )

inline

Set a specifically-typed value into the variant

Set() [2/2]

template<typename T , typename... Ts>

template<typename U >

void TVariant< T, Ts >::Set ( typename TIdentity< U >::Type &&  Value )

inline

Set a specifically-typed value into the variant

TryGet() [1/2]

template<typename T , typename... Ts>

template<typename U >

const U * TVariant< T, Ts >::TryGet ( ) const

inline

Get a pointer to the held value if the held type is the same as the one specified

TryGet() [2/2]

template<typename T , typename... Ts>

template<typename U >

U * TVariant< T, Ts >::TryGet ( )

inline

Get a pointer to the held value if the held type is the same as the one specified

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

• Engine/Source/Runtime/Core/Public/Misc/TVariant.h