Struct servo_arc::ArcUnion

pub struct ArcUnion<A, B> {
    pub(crate) p: NonNull<()>,
    pub(crate) phantom_a: PhantomData<A>,
    pub(crate) phantom_b: PhantomData<B>,
}

A tagged union that can represent Arc<A> or Arc<B> while only consuming a single word. The type is also NonNull, and thus can be stored in an Option without increasing size.

This is functionally equivalent to enum ArcUnion<A, B> { First(Arc<A>), Second(Arc<B>) but only takes up up a single word of stack space.

This could probably be extended to support four types if necessary.

Fields

p: NonNull<()>

phantom_a: PhantomData<A>

phantom_b: PhantomData<B>

Implementations

impl<A, B> ArcUnion<A, B>

pub(crate) unsafe fn new(ptr: *mut ()) -> Self

pub fn ptr_eq(this: &Self, other: &Self) -> bool

Returns true if the two values are pointer-equal.

pub fn ptr(&self) -> NonNull<()>

pub fn borrow(&self) -> ArcUnionBorrow<'_, A, B>

Returns an enum representing a borrow of either A or B.

pub fn from_first(other: Arc<A>) -> Self

Creates an ArcUnion from an instance of the first type.

pub fn from_second(other: Arc<B>) -> Self

Creates an ArcUnion from an instance of the second type.

pub fn is_first(&self) -> bool

Returns true if this ArcUnion contains the first type.

pub fn is_second(&self) -> bool

Returns true if this ArcUnion contains the second type.

pub fn as_first(&self) -> Option<ArcBorrow<'_, A>>

Returns a borrow of the first type if applicable, otherwise None.

pub fn as_second(&self) -> Option<ArcBorrow<'_, B>>

Returns a borrow of the second type if applicable, otherwise None.

Trait Implementations

impl<A, B> Clone for ArcUnion<A, B>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<A: Debug, B: Debug> Debug for ArcUnion<A, B>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<A, B> Drop for ArcUnion<A, B>

fn drop(&mut self)

Executes the destructor for this type.

impl<A: PartialEq, B: PartialEq> PartialEq for ArcUnion<A, B>

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<A: Eq, B: Eq> Eq for ArcUnion<A, B>

impl<A: Sync + Send, B: Send + Sync> Send for ArcUnion<A, B>

impl<A: Sync + Send, B: Send + Sync> Sync for ArcUnion<A, B>