forked from mirror/async-std
43 lines
1.3 KiB
Rust
43 lines
1.3 KiB
Rust
use std::pin::Pin;
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use crate::prelude::*;
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use crate::stream::{FromStream, IntoStream};
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impl<T, E, V> FromStream<Result<T, E>> for Result<V, E>
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where
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V: FromStream<T>,
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{
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/// Takes each element in the stream: if it is an `Err`, no further
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/// elements are taken, and the `Err` is returned. Should no `Err`
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/// occur, a container with the values of each `Result` is returned.
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#[inline]
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fn from_stream<'a, S: IntoStream<Item = Result<T, E>> + 'a>(
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stream: S,
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) -> Pin<Box<dyn Future<Output = Self> + 'a>> {
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let stream = stream.into_stream();
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Box::pin(async move {
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// Using `scan` here because it is able to stop the stream early
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// if a failure occurs
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let mut found_error = None;
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let out: V = stream
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.scan((), |(), elem| {
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match elem {
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Ok(elem) => Some(elem),
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Err(err) => {
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found_error = Some(err);
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// Stop processing the stream on error
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None
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}
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}
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})
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.collect()
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.await;
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match found_error {
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Some(err) => Err(err),
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None => Ok(out),
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}
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})
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}
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}
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