Struct servo_arc::ArcUnion

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

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§

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

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

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

Returns true if the two values are pointer-equal.

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

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

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

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

Creates an ArcUnion from an instance of the first type.

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

Creates an ArcUnion from an instance of the second type.

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pub fn is_first(&self) -> bool

Returns true if this ArcUnion contains the first type.

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pub fn is_second(&self) -> bool

Returns true if this ArcUnion contains the second type.

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

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

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

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

Trait Implementations§

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

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fn clone(&self) -> Self

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<A: Debug, B: Debug> Debug for ArcUnion<A, B>

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

Formats the value using the given formatter. Read more
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impl<A, B> Drop for ArcUnion<A, B>

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fn drop(&mut self)

Executes the destructor for this type. Read more
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impl<A: PartialEq, B: PartialEq> PartialEq<ArcUnion<A, B>> for ArcUnion<A, B>

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

This method tests for self and other values to be equal, and is used by ==.
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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.
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impl<A: Sync + Send, B: Send + Sync> Send for ArcUnion<A, B>

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

Auto Trait Implementations§

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impl<A, B> RefUnwindSafe for ArcUnion<A, B>where A: RefUnwindSafe, B: RefUnwindSafe,

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impl<A, B> Unpin for ArcUnion<A, B>where A: Unpin, B: Unpin,

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impl<A, B> UnwindSafe for ArcUnion<A, B>where A: UnwindSafe, B: UnwindSafe,

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.