tower::util

Struct Optional

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pub struct Optional<T> { /* private fields */ }
Available on crate feature util only.
Expand description

Optionally forwards requests to an inner service.

If the inner service is None, optional::None is returned as the response.

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impl<T> Optional<T>

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pub const fn new<Request>(inner: Option<T>) -> Optional<T>
where T: Service<Request>, T::Error: Into<BoxError>,

Create a new Optional.

Trait Implementations§

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impl<T: Debug> Debug for Optional<T>

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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<T, Request> Service<Request> for Optional<T>
where T: Service<Request>, T::Error: Into<BoxError>,

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type Response = <T as Service<Request>>::Response

Responses given by the service.
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type Error = Box<dyn Error + Send + Sync>

Errors produced by the service.
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type Future = ResponseFuture<<T as Service<Request>>::Future>

The future response value.
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fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>>

Returns Poll::Ready(Ok(())) when the service is able to process requests. Read more
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fn call(&mut self, request: Request) -> Self::Future

Process the request and return the response asynchronously. Read more

Auto Trait Implementations§

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impl<T> Freeze for Optional<T>
where T: Freeze,

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impl<T> RefUnwindSafe for Optional<T>
where T: RefUnwindSafe,

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impl<T> Send for Optional<T>
where T: Send,

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impl<T> Sync for Optional<T>
where T: Sync,

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impl<T> Unpin for Optional<T>
where T: Unpin,

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impl<T> UnwindSafe for Optional<T>
where T: 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> 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 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, Request> ServiceExt<Request> for T
where T: Service<Request> + ?Sized,

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fn ready(&mut self) -> Ready<'_, Self, Request> ⓘ
where Self: Sized,

Available on crate feature util only.
Yields a mutable reference to the service when it is ready to accept a request.
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fn ready_oneshot(self) -> ReadyOneshot<Self, Request> ⓘ
where Self: Sized,

Available on crate feature util only.
Yields the service when it is ready to accept a request.
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fn oneshot(self, req: Request) -> Oneshot<Self, Request> ⓘ
where Self: Sized,

Available on crate feature util only.
Consume this Service, calling it with the provided request once it is ready.
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fn call_all<S>(self, reqs: S) -> CallAll<Self, S>
where Self: Sized, S: Stream<Item = Request>,

Available on crate feature util only.
Process all requests from the given Stream, and produce a Stream of their responses. Read more
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fn and_then<F>(self, f: F) -> AndThen<Self, F>
where Self: Sized, F: Clone,

Available on crate feature util only.
Executes a new future after this service’s future resolves. This does not alter the behaviour of the poll_ready method. Read more
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fn map_response<F, Response>(self, f: F) -> MapResponse<Self, F>
where Self: Sized, F: FnOnce(Self::Response) -> Response + Clone,

Available on crate feature util only.
Maps this service’s response value to a different value. This does not alter the behaviour of the poll_ready method. Read more
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fn map_err<F, Error>(self, f: F) -> MapErr<Self, F>
where Self: Sized, F: FnOnce(Self::Error) -> Error + Clone,

Available on crate feature util only.
Maps this service’s error value to a different value. This does not alter the behaviour of the poll_ready method. Read more
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fn map_result<F, Response, Error>(self, f: F) -> MapResult<Self, F>
where Self: Sized, Error: From<Self::Error>, F: FnOnce(Result<Self::Response, Self::Error>) -> Result<Response, Error> + Clone,

Available on crate feature util only.
Maps this service’s result type (Result<Self::Response, Self::Error>) to a different value, regardless of whether the future succeeds or fails. Read more
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fn map_request<F, NewRequest>(self, f: F) -> MapRequest<Self, F>
where Self: Sized, F: FnMut(NewRequest) -> Request,

Available on crate feature util only.
Composes a function in front of the service. Read more
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fn then<F, Response, Error, Fut>(self, f: F) -> Then<Self, F>
where Self: Sized, Error: From<Self::Error>, F: FnOnce(Result<Self::Response, Self::Error>) -> Fut + Clone, Fut: Future<Output = Result<Response, Error>>,

Available on crate feature util only.
Composes an asynchronous function after this service. Read more
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fn map_future<F, Fut, Response, Error>(self, f: F) -> MapFuture<Self, F>
where Self: Sized, F: FnMut(Self::Future) -> Fut, Error: From<Self::Error>, Fut: Future<Output = Result<Response, Error>>,

Available on crate feature util only.
Composes a function that transforms futures produced by the service. Read more
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fn boxed(self) -> BoxService<Request, Self::Response, Self::Error>
where Self: Sized + Send + 'static, Self::Future: Send + 'static,

Available on crate feature util only.
Convert the service into a Service + Send trait object. Read more
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fn boxed_clone(self) -> BoxCloneService<Request, Self::Response, Self::Error>
where Self: Clone + Sized + Send + 'static, Self::Future: Send + 'static,

Available on crate feature util only.
Convert the service into a Service + Clone + Send trait object. Read more
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impl<T, U> TryFrom<U> for T
where 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 T
where 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.

Layout§

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.