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Use take_while instead of scan for Option

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This commit is contained in:
Oleg Nosov 2020-01-12 17:32:59 +03:00
parent 98d45f4be1
commit 83afbab2ef
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GPG key ID: DE90B83800644E24
3 changed files with 37 additions and 34 deletions
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23
src/option/from_stream.rs
View file

@ -17,24 +17,25 @@ where
let stream = stream.into_stream();
Box::pin(async move {
// Using `scan` here because it is able to stop the stream early
// Using `take_while` here because it is able to stop the stream early
// if a failure occurs
let mut found_error = false;
let mut found_none = false;
let out: V = stream
.scan((), |_, elem| {
match elem {
Some(elem) => Some(elem),
None => {
found_error = true;
// Stop processing the stream on error
None
}
.take_while(|elem| {
elem.is_some() || {
found_none = true;
false
}
})
.map(Option::unwrap)
.collect()
.await;
if found_error { None } else { Some(out) }
if found_none {
None
} else {
Some(out)
}
})
}
}

25
src/option/product.rs
View file

@ -1,7 +1,7 @@
use std::pin::Pin;
use crate::prelude::*;
use crate::stream::{Stream, Product};
use crate::stream::{Product, Stream};
impl<T, U> Product<Option<U>> for Option<T>
where
@ -36,23 +36,24 @@ where
```
"#]
fn product<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Option<T>> + 'a>>
where S: Stream<Item = Option<U>> + 'a
where
S: Stream<Item = Option<U>> + 'a,
{
Box::pin(async move {
// Using `scan` here because it is able to stop the stream early
// Using `take_while` here because it is able to stop the stream early
// if a failure occurs
let mut found_none = false;
let out = <T as Product<U>>::product(stream
.scan((), |_, elem| {
match elem {
Some(elem) => Some(elem),
None => {
let out = <T as Product<U>>::product(
stream
.take_while(|elem| {
elem.is_some() || {
found_none = true;
// Stop processing the stream on error
None
false
}
}
})).await;
})
.map(Option::unwrap),
)
.await;
if found_none {
None

23
src/option/sum.rs
View file

@ -31,23 +31,24 @@ where
```
"#]
fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Option<T>> + 'a>>
where S: Stream<Item = Option<U>> + 'a
where
S: Stream<Item = Option<U>> + 'a,
{
Box::pin(async move {
// Using `scan` here because it is able to stop the stream early
// Using `take_while` here because it is able to stop the stream early
// if a failure occurs
let mut found_none = false;
let out = <T as Sum<U>>::sum(stream
.scan((), |_, elem| {
match elem {
Some(elem) => Some(elem),
None => {
let out = <T as Sum<U>>::sum(
stream
.take_while(|elem| {
elem.is_some() || {
found_none = true;
// Stop processing the stream on error
None
false
}
}
})).await;
})
.map(Option::unwrap),
)
.await;
if found_none {
None