futures_util::future

Struct Lazy

Source 
pub struct Lazy<F> { /* private fields */ }
Expand description

Future for the lazy function.

Trait Implementations§

Source§

impl<F: Debug> Debug for Lazy<F>

Source§

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

Formats the value using the given formatter. Read more
Source§

impl<F, R> FusedFuture for Lazy<F>
where F: FnOnce(&mut Context<'_>) -> R,

Source§

fn is_terminated(&self) -> bool

Returns true if the underlying future should no longer be polled.
Source§

impl<F, R> Future for Lazy<F>
where F: FnOnce(&mut Context<'_>) -> R,

Source§

type Output = R

The type of value produced on completion.
Source§

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<R>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. Read more
Source§

impl<F> Unpin for Lazy<F>

Auto Trait Implementations§

§

impl<F> Freeze for Lazy<F>
where F: Freeze,

§

impl<F> RefUnwindSafe for Lazy<F>
where F: RefUnwindSafe,

§

impl<F> Send for Lazy<F>
where F: Send,

§

impl<F> Sync for Lazy<F>
where F: Sync,

§

impl<F> UnwindSafe for Lazy<F>
where F: UnwindSafe,

Blanket Implementations§

§

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

§

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
§

impl<T> Borrow<T> for T
where T: ?Sized,

§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
§

impl<T> BorrowMut<T> for T
where T: ?Sized,

§

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

Mutably borrows from an owned value. Read more
§

impl<T> From<T> for T

§

fn from(t: T) -> T

Returns the argument unchanged.

Source§

impl<T> FutureExt for T
where T: Future + ?Sized,

Source§

fn map<U, F>(self, f: F) -> Map<Self, F> ⓘ
where F: FnOnce(Self::Output) -> U, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more
Source§

fn map_into<U>(self) -> MapInto<Self, U> ⓘ
where Self::Output: Into<U>, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more
Source§

fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F> ⓘ
where F: FnOnce(Self::Output) -> Fut, Fut: Future, Self: Sized,

Chain on a computation for when a future finished, passing the result of the future to the provided closure f. Read more
Source§

fn left_future<B>(self) -> Either<Self, B> ⓘ
where B: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the left-hand variant of that Either. Read more
Source§

fn right_future<A>(self) -> Either<A, Self> ⓘ
where A: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the right-hand variant of that Either. Read more
Source§

fn into_stream(self) -> IntoStream<Self>
where Self: Sized,

Convert this future into a single element stream. Read more
Source§

fn flatten(self) -> Flatten<Self> ⓘ
where Self::Output: Future, Self: Sized,

Flatten the execution of this future when the output of this future is itself another future. Read more
Source§

fn flatten_stream(self) -> FlattenStream<Self>
where Self::Output: Stream, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more
Source§

fn fuse(self) -> Fuse<Self> ⓘ
where Self: Sized,

Fuse a future such that poll will never again be called once it has completed. This method can be used to turn any Future into a FusedFuture. Read more
Source§

fn inspect<F>(self, f: F) -> Inspect<Self, F> ⓘ
where F: FnOnce(&Self::Output), Self: Sized,

Do something with the output of a future before passing it on. Read more
Source§

fn boxed<'a>(self) -> BoxFuture<'a, Self::Output>
where Self: Sized + Send + 'a,

Wrap the future in a Box, pinning it. Read more
Source§

fn boxed_local<'a>(self) -> LocalBoxFuture<'a, Self::Output>
where Self: Sized + 'a,

Wrap the future in a Box, pinning it. Read more
Source§

fn unit_error(self) -> UnitError<Self> ⓘ
where Self: Sized,

Turns a Future<Output = T> into a TryFuture<Ok = T, Error = ()>.
Source§

fn never_error(self) -> NeverError<Self> ⓘ
where Self: Sized,

Turns a Future<Output = T> into a TryFuture<Ok = T, Error = Never>.
Source§

fn poll_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>
where Self: Unpin,

A convenience for calling Future::poll on Unpin future types.
Source§

fn now_or_never(self) -> Option<Self::Output>
where Self: Sized,

Evaluates and consumes the future, returning the resulting output if the future is ready after the first call to Future::poll. Read more
§

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

§

fn into(self) -> U

Calls U::from(self).

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

§

impl<F> IntoFuture for F
where F: Future,

§

type Output = <F as Future>::Output

The output that the future will produce on completion.
§

type IntoFuture = F

Which kind of future are we turning this into?
§

fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more
§

impl<T, U> TryFrom<U> for T
where U: Into<T>,

§

type Error = Infallible

The type returned in the event of a conversion error.
§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
Source§

impl<F, T, E> TryFuture for F
where F: Future<Output = Result<T, E>> + ?Sized,

Source§

type Ok = T

The type of successful values yielded by this future
Source§

type Error = E

The type of failures yielded by this future
Source§

fn try_poll( self: Pin<&mut F>, cx: &mut Context<'_>, ) -> Poll<<F as Future>::Output>

Poll this TryFuture as if it were a Future. Read more
Source§

impl<Fut> TryFutureExt for Fut
where Fut: TryFuture + ?Sized,

Source§

fn flatten_sink<Item>(self) -> FlattenSink<Self, Self::Ok>
where Self::Ok: Sink<Item, Error = Self::Error>, Self: Sized,

Flattens the execution of this future when the successful result of this future is a Sink. Read more
Source§

fn map_ok<T, F>(self, f: F) -> MapOk<Self, F> ⓘ
where F: FnOnce(Self::Ok) -> T, Self: Sized,

Maps this future’s success value to a different value. Read more
Source§

fn map_ok_or_else<T, E, F>(self, e: E, f: F) -> MapOkOrElse<Self, F, E> ⓘ
where F: FnOnce(Self::Ok) -> T, E: FnOnce(Self::Error) -> T, Self: Sized,

Maps this future’s success value to a different value, and permits for error handling resulting in the same type. Read more
Source§

fn map_err<E, F>(self, f: F) -> MapErr<Self, F> ⓘ
where F: FnOnce(Self::Error) -> E, Self: Sized,

Maps this future’s error value to a different value. Read more
Source§

fn err_into<E>(self) -> ErrInto<Self, E> ⓘ
where Self: Sized, Self::Error: Into<E>,

Maps this future’s Error to a new error type using the Into trait. Read more
Source§

fn ok_into<U>(self) -> OkInto<Self, U> ⓘ
where Self: Sized, Self::Ok: Into<U>,

Maps this future’s Ok to a new type using the Into trait.
Source§

fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F> ⓘ
where F: FnOnce(Self::Ok) -> Fut, Fut: TryFuture<Error = Self::Error>, Self: Sized,

Executes another future after this one resolves successfully. The success value is passed to a closure to create this subsequent future. Read more
Source§

fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F> ⓘ
where F: FnOnce(Self::Error) -> Fut, Fut: TryFuture<Ok = Self::Ok>, Self: Sized,

Executes another future if this one resolves to an error. The error value is passed to a closure to create this subsequent future. Read more
Source§

fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F> ⓘ
where F: FnOnce(&Self::Ok), Self: Sized,

Do something with the success value of a future before passing it on. Read more
Source§

fn inspect_err<F>(self, f: F) -> InspectErr<Self, F> ⓘ
where F: FnOnce(&Self::Error), Self: Sized,

Do something with the error value of a future before passing it on. Read more
Source§

fn try_flatten(self) -> TryFlatten<Self, Self::Ok> ⓘ
where Self::Ok: TryFuture<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is another future. Read more
Source§

fn try_flatten_stream(self) -> TryFlattenStream<Self>
where Self::Ok: TryStream<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more
Source§

fn unwrap_or_else<F>(self, f: F) -> UnwrapOrElse<Self, F> ⓘ
where Self: Sized, F: FnOnce(Self::Error) -> Self::Ok,

Unwraps this future’s output, producing a future with this future’s Ok type as its Output type. Read more
Source§

fn into_future(self) -> IntoFuture<Self> ⓘ
where Self: Sized,

Wraps a TryFuture into a type that implements Future. Read more
Source§

fn try_poll_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<Self::Ok, Self::Error>>
where Self: Unpin,

A convenience method for calling TryFuture::try_poll on [Unpin] future types.
§

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

§

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

The type returned in the event of a conversion error.
§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.