Struct mmtk::util::api_util::NullableObjectReference
source · #[repr(transparent)]pub struct NullableObjectReference(usize);Expand description
An Option<ObjectReference> encoded as a usize (which is guaranteed to have the size of a
native pointer). It guarantees that None is encoded as 0, and Some(objref) is encoded as
the underlying usize value of the ObjectReference itself.
Note: The Rust ABI currently doesn’t guarantee the encoding of None even if the T in
Option<T> is eligible for null pointer optimization. Transmuting a None value of
Option<ObjectReference> to usize still has undefined behavior.
See: https://doc.rust-lang.org/std/option/index.html#representation
It is intended for passing an Option<ObjectReference> values to and from native programs
(usually C or C++) that have null pointers.
Tuple Fields§
§0: usizeTrait Implementations§
source§impl From<NullableObjectReference> for Option<ObjectReference>
impl From<NullableObjectReference> for Option<ObjectReference>
source§fn from(value: NullableObjectReference) -> Self
fn from(value: NullableObjectReference) -> Self
Converts to this type from the input type.
source§impl From<Option<ObjectReference>> for NullableObjectReference
impl From<Option<ObjectReference>> for NullableObjectReference
source§fn from(value: Option<ObjectReference>) -> Self
fn from(value: Option<ObjectReference>) -> Self
Converts to this type from the input type.
Auto Trait Implementations§
impl RefUnwindSafe for NullableObjectReference
impl Send for NullableObjectReference
impl Sync for NullableObjectReference
impl Unpin for NullableObjectReference
impl UnwindSafe for NullableObjectReference
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
§impl<T> Downcast for Twhere
T: Any,
impl<T> Downcast for Twhere
T: Any,
§fn into_any(self: Box<T>) -> Box<dyn Any>
fn into_any(self: Box<T>) -> Box<dyn Any>
Convert
Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can
then be further downcast into Box<ConcreteType> where ConcreteType implements Trait.§fn into_any_rc(self: Rc<T>) -> Rc<dyn Any>
fn into_any_rc(self: Rc<T>) -> Rc<dyn Any>
Convert
Rc<Trait> (where Trait: Downcast) to Rc<Any>. Rc<Any> can then be
further downcast into Rc<ConcreteType> where ConcreteType implements Trait.§fn as_any(&self) -> &(dyn Any + 'static)
fn as_any(&self) -> &(dyn Any + 'static)
Convert
&Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot
generate &Any’s vtable from &Trait’s.§fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Convert
&mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot
generate &mut Any’s vtable from &mut Trait’s.§impl<T> DowncastSync for T
impl<T> DowncastSync for T
source§impl<T> IntoEither for T
impl<T> IntoEither for T
source§fn into_either(self, into_left: bool) -> Either<Self, Self>
fn into_either(self, into_left: bool) -> Either<Self, Self>
Converts
self into a Left variant of Either<Self, Self>
if into_left is true.
Converts self into a Right variant of Either<Self, Self>
otherwise. Read moresource§fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
Converts
self into a Left variant of Either<Self, Self>
if into_left(&self) returns true.
Converts self into a Right variant of Either<Self, Self>
otherwise. Read more