Struct LazyTransform

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pub struct LazyTransform<T, U> { /* private fields */ }

Expand description

LazyTransform<T, U> is a synchronized holder type, that holds a value of type T until it is lazily converted into a value of type U.

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impl<T, U> LazyTransform<T, U>

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pub fn new(t: T) -> LazyTransform<T, U>

Construct a new, untransformed LazyTransform<T, U> with an argument of type T.

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pub fn into_inner(self) -> Result<U, T>

Unwrap the contained value, returning Ok(U) if the LazyTransform<T, U> has been transformed or Err(T) if it has not.

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impl<T, U> LazyTransform<T, U>

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pub fn get_or_create<F>(&self, f: F) -> &U
where F: FnOnce(T) -> U,

Get a reference to the transformed value, invoking f to transform it if the LazyTransform<T, U> has yet to be transformed. It is guaranteed that if multiple calls to get_or_create race, only one will invoke its closure, and every call will receive a reference to the newly transformed value.

The closure can only ever be called once, so think carefully about what transformation you want to apply!

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pub fn get(&self) -> Option<&U>

Get a reference to the transformed value, returning Some(&U) if the LazyTransform<T, U> has been transformed or None if it has not. It is guaranteed that if a reference is returned it is to the transformed value inside the the LazyTransform<T>.

Trait Implementations§

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impl<T, U> Clone for LazyTransform<T, U>
where T: Clone, U: Clone,

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fn clone(&self) -> LazyTransform<T, U>

Returns a duplicate of the value. Read more

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fn clone_from(&mut self, source: &LazyTransform<T, U>)

Performs copy-assignment from source. Read more

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impl<T, U> Default for LazyTransform<T, U>
where T: Default,

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fn default() -> LazyTransform<T, U>

Returns the “default value” for a type. Read more

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impl<T, U> Sync for LazyTransform<T, U>
where T: Send, U: Send + Sync,

Auto Trait Implementations§

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impl<T, U> UnsafeUnpin for LazyTransform<T, U>
where T: UnsafeUnpin, U: UnsafeUnpin,

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impl<T, U> UnwindSafe for LazyTransform<T, U>
where T: UnwindSafe, U: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where 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 T
where 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 T
where 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> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)

Performs copy-assignment from self to dest. Read more

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impl<T> Downcast for T
where T: Any,

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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.

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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.

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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.

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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.

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impl<T> DowncastSync for T
where T: Any + Send + Sync,

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fn into_any_arc(self: Arc<T>) -> Arc<dyn Any + Send + Sync> ⓘ

Convert Arc<Trait> (where Trait: Downcast) to Arc<Any>. Arc<Any> can then be further downcast into Arc<ConcreteType> where ConcreteType implements Trait.

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impl<A> DynCastExt for A

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fn dyn_cast<T>( self, ) -> Result<<A as DynCastExtHelper<T>>::Target, <A as DynCastExtHelper<T>>::Source>
where A: DynCastExtHelper<T>, T: ?Sized,

Use this to cast from one trait object type to another. Read more

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fn dyn_upcast<T>(self) -> <A as DynCastExtAdvHelper<T, T>>::Target
where A: DynCastExtAdvHelper<T, T, Source = <A as DynCastExtAdvHelper<T, T>>::Target>, T: ?Sized,

Use this to upcast a trait to one of its supertraits. Read more

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fn dyn_cast_adv<F, T>( self, ) -> Result<<A as DynCastExtAdvHelper<F, T>>::Target, <A as DynCastExtAdvHelper<F, T>>::Source>
where A: DynCastExtAdvHelper<F, T>, F: ?Sized, T: ?Sized,

Use this to cast from one trait object type to another. This method is more customizable than the dyn_cast method. Here you can also specify the “source” trait from which the cast is defined. This can for example allow using casts from a supertrait of the current trait object. Read more

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fn dyn_cast_with_config<C>( self, ) -> Result<<A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Target, <A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Source>
where C: DynCastConfig, A: DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>,

Use this to cast from one trait object type to another. With this method the type parameter is a config type that uniquely specifies which cast should be preformed. 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> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self> ⓘ

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

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fn in_current_span(self) -> Instrumented<Self> ⓘ

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

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impl<T, U> Into for T
where 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> IntoEither for T

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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 more

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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self> ⓘ
where F: FnOnce(&Self) -> bool,

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

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