forked from mirror/async-std
50 lines
1.4 KiB
Rust
50 lines
1.4 KiB
Rust
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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, V> FromStream<Option<T>> for Option<V>
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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 `None`, no further
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/// elements are taken, and `None` is returned. Should no `None`
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/// occur, a container with the values of each `Option` is returned.
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#[inline]
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fn from_stream<'a, S: IntoStream<Item = Option<T>>>(
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stream: S,
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) -> Pin<Box<dyn core::future::Future<Output = Self> + 'a>>
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where
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<S as IntoStream>::IntoStream: 'a,
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{
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let stream = stream.into_stream();
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Pin::from(Box::new(async move {
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pin_utils::pin_mut!(stream);
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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 = false;
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let out: V = stream
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.scan((), |_, elem| {
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match elem {
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Some(elem) => Some(elem),
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None => {
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found_error = true;
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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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if found_error {
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None
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} else {
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Some(out)
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}
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}))
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}
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}
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