wpi::PointerUnion< PTs > Class Template Reference

A discriminated union of two or more pointer types, with the discriminator in the low bit of the pointer. More...

#include <wpi/PointerUnion.h>

Inheritance diagram for wpi::PointerUnion< PTs >:

Public Member Functions
	PointerUnion ()=default
	PointerUnion (std::nullptr_t)
bool	isNull () const
	Test if the pointer held in the union is null, regardless of which type it is.
	operator bool () const
template<typename T >
bool	is () const
	Test if the Union currently holds the type matching T.
template<typename T >
T	get () const
	Returns the value of the specified pointer type.
template<typename T >
T	dyn_cast () const
	Returns the current pointer if it is of the specified pointer type, otherwise returns null.
First const *	getAddrOfPtr1 () const
	If the union is set to the first pointer type get an address pointing to it.
First *	getAddrOfPtr1 ()
	If the union is set to the first pointer type get an address pointing to it.
const PointerUnion &	operator= (std::nullptr_t)
	Assignment from nullptr which just clears the union.
void *	getOpaqueValue () const

Static Public Member Functions
static PointerUnion	getFromOpaqueValue (void *VP)

Friends
struct	CastInfoPointerUnionImpl< PTs... >
	This is needed to give the CastInfo implementation below access to protected members.

Detailed Description

template<typename... PTs>
class wpi::PointerUnion< PTs >

A discriminated union of two or more pointer types, with the discriminator in the low bit of the pointer.

This implementation is extremely efficient in space due to leveraging the low bits of the pointer, while exposing a natural and type-safe API.

Common use patterns would be something like this: PointerUnion<int*, float*> P; P = (int*)0; printf("%d %d", P.is<int*>(), P.is<float*>()); // prints "1 0" X = P.get<int*>(); // ok. Y = P.get<float*>(); // runtime assertion failure. Z = P.get<double*>(); // compile time failure. P = (float*)0; Y = P.get<float*>(); // ok. X = P.get<int*>(); // runtime assertion failure. PointerUnion<int*, int*> Q; // compile time failure.

Constructor & Destructor Documentation

PointerUnion() [1/2]

template<typename... PTs>

wpi::PointerUnion< PTs >::PointerUnion ( )

default

PointerUnion() [2/2]

template<typename... PTs>

wpi::PointerUnion< PTs >::PointerUnion ( std::nullptr_t )

inline

Member Function Documentation

dyn_cast()

template<typename... PTs>

template<typename T >

T wpi::PointerUnion< PTs >::dyn_cast ( ) const

inline

Returns the current pointer if it is of the specified pointer type, otherwise returns null.

get()

template<typename... PTs>

template<typename T >

T wpi::PointerUnion< PTs >::get ( ) const

inline

Returns the value of the specified pointer type.

If the specified pointer type is incorrect, assert.

getAddrOfPtr1() [1/2]

template<typename... PTs>

First * wpi::PointerUnion< PTs >::getAddrOfPtr1 ( )

inline

If the union is set to the first pointer type get an address pointing to it.

getAddrOfPtr1() [2/2]

template<typename... PTs>

First const * wpi::PointerUnion< PTs >::getAddrOfPtr1 ( ) const

inline

If the union is set to the first pointer type get an address pointing to it.

getFromOpaqueValue()

template<typename... PTs>

static PointerUnion wpi::PointerUnion< PTs >::getFromOpaqueValue ( void * VP )

inlinestatic

getOpaqueValue()

template<typename... PTs>

void * wpi::PointerUnion< PTs >::getOpaqueValue ( ) const

inline

is()

template<typename... PTs>

template<typename T >

bool wpi::PointerUnion< PTs >::is ( ) const

inline

Test if the Union currently holds the type matching T.

isNull()

template<typename... PTs>

bool wpi::PointerUnion< PTs >::isNull ( ) const

inline

Test if the pointer held in the union is null, regardless of which type it is.

operator bool()

template<typename... PTs>

wpi::PointerUnion< PTs >::operator bool ( ) const

inlineexplicit

operator=()

template<typename... PTs>

const PointerUnion & wpi::PointerUnion< PTs >::operator= ( std::nullptr_t )

inline

Assignment from nullptr which just clears the union.

Friends And Related Symbol Documentation

CastInfoPointerUnionImpl< PTs... >

template<typename... PTs>

friend struct CastInfoPointerUnionImpl< PTs... >

friend

This is needed to give the CastInfo implementation below access to protected members.

Refer to its definition for further details.

---

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

• wpi/PointerUnion.h