WPILibC++  2020.3.2-60-g3011ebe
wpi::PointerUnion< PT1, PT2 > Class Template Reference

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

#include <PointerUnion.h>

Public Types

using ValTy = PointerIntPair< void *, 1, bool, PointerUnionUIntTraits< PT1, PT2 > >
 

Public Member Functions

 PointerUnion (PT1 V)
 
 PointerUnion (PT2 V)
 
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 >
int is () const
 Test if the Union currently holds the type matching T.
 
template<typename T >
get () const
 Returns the value of the specified pointer type. More...
 
template<typename T >
dyn_cast () const
 Returns the current pointer if it is of the specified pointer type, otherwises returns null.
 
const PT1 * getAddrOfPtr1 () const
 If the union is set to the first pointer type get an address pointing to it.
 
PT1 * getAddrOfPtr1 ()
 If the union is set to the first pointer type get an address pointing to it.
 
const PointerUnionoperator= (std::nullptr_t)
 Assignment from nullptr which just clears the union.
 
const PointerUnionoperator= (const PT1 &RHS)
 Assignment operators - Allow assigning into this union from either pointer type, setting the discriminator to remember what it came from.
 
const PointerUnionoperator= (const PT2 &RHS)
 
void * getOpaqueValue () const
 

Static Public Member Functions

static PointerUnion getFromOpaqueValue (void *VP)
 

Detailed Description

template<typename PT1, typename PT2>
class wpi::PointerUnion< PT1, PT2 >

A discriminated union of two 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.

Member Function Documentation

◆ get()

template<typename PT1, typename PT2>
template<typename T >
T wpi::PointerUnion< PT1, PT2 >::get ( ) const
inline

Returns the value of the specified pointer type.

If the specified pointer type is incorrect, assert.


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