pub struct FnStream<Item> { /* private fields */ }
Expand description

The closure is passed a reference to a Sender which acts as a rendezvous channel. Messages sent to the sender will be emitted to the stream. Because the stream is 1-bounded, the function will not proceed until the stream is read.

This utility is used by generated paginators to generate a stream of paginated results.

If tx.send returns an error, the function MUST return immediately.

Note FnStream is only Send but not Sync because generator is a boxed future that is Send and returns () as output when it is done.

§Examples

use aws_smithy_async::future::pagination_stream::fn_stream::FnStream;
let mut stream = FnStream::new(|tx| Box::pin(async move {
    if let Err(_) = tx.send("Hello!").await {
        return;
    }
    if let Err(_) = tx.send("Goodbye!").await {
        return;
    }
}));
assert_eq!(stream.collect::<Vec<_>>().await, vec!["Hello!", "Goodbye!"]);

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impl<Item> FnStream<Item>

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pub fn new<T>(generator: T) -> Self
where T: FnOnce(Sender<Item>) -> Pin<Box<dyn Future<Output = ()> + Send + 'static>>,

Creates a new function based stream driven by generator.

For examples, see the documentation for FnStream

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pub async fn next(&mut self) -> Option<Item>
where Self: Unpin,

Consumes and returns the next Item from this stream.

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pub async fn collect<T: Collectable<Item>>(self) -> T

Consumes this stream and gathers elements into a collection.

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impl<T, E> FnStream<Result<T, E>>

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pub async fn try_next(&mut self) -> Result<Option<T>, E>

Yields the next item in the stream or returns an error if an error is encountered.

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pub async fn try_collect(self) -> Result<Vec<T>, E>

Convenience method for .collect::<Result<Vec<_>, _>().

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impl<Item> Debug for FnStream<Item>

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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<'__pin, Item> Unpin for FnStream<Item>
where __Origin<'__pin, Item>: Unpin,

Auto Trait Implementations§

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impl<Item> Freeze for FnStream<Item>

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impl<Item> !RefUnwindSafe for FnStream<Item>

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impl<Item> Send for FnStream<Item>
where Item: Send,

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impl<Item> !Sync for FnStream<Item>

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impl<Item> !UnwindSafe for FnStream<Item>

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, 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.