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FromStream impl for Option<T> + Revised impl for Vec<T> #265

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Merged
merged 4 commits into from
Oct 1, 2019
Merged

FromStream impl for Option<T> + Revised impl for Vec<T> #265

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76b10c4
FromStream for Option<T>
sunjay Sep 29, 2019
ab7129c
FromStream for Vec<T> in terms of Extend
sunjay Sep 29, 2019
fb7582b
Using Box::pin(...) instead of Pin::from(Box::new(...))
sunjay Sep 29, 2019
a05b564
rustfmt
sunjay Oct 1, 2019
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1 change: 1 addition & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,7 @@ cfg_if! {

mod vec;
mod result;
mod option;
}
}

Expand Down
45 changes: 45 additions & 0 deletions src/option/from_stream.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,45 @@
use std::pin::Pin;

use crate::prelude::*;
use crate::stream::{FromStream, IntoStream};

impl<T, V> FromStream<Option<T>> for Option<V>
where
V: FromStream<T>,
{
/// Takes each element in the stream: if it is `None`, no further
/// elements are taken, and `None` is returned. Should no `None`
/// occur, a container with the values of each `Option` is returned.
#[inline]
fn from_stream<'a, S: IntoStream<Item = Option<T>>>(
stream: S,
) -> Pin<Box<dyn core::future::Future<Output = Self> + 'a>>
where
<S as IntoStream>::IntoStream: 'a,
{
let stream = stream.into_stream();

Box::pin(async move {
pin_utils::pin_mut!(stream);

// Using `scan` here because it is able to stop the stream early
// if a failure occurs
let mut found_error = false;
let out: V = stream
.scan((), |_, elem| {
match elem {
Some(elem) => Some(elem),
None => {
found_error = true;
// Stop processing the stream on error
None
}
}
})
.collect()
.await;

if found_error { None } else { Some(out) }
})
}
}
9 changes: 9 additions & 0 deletions src/option/mod.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
//! The Rust core optional value type
//!
//! This module provides the `Option<T>` type for returning and
//! propagating optional values.

mod from_stream;

#[doc(inline)]
pub use std::option::Option;
4 changes: 2 additions & 2 deletions src/result/from_stream.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ where
{
let stream = stream.into_stream();

Pin::from(Box::new(async move {
Box::pin(async move {
pin_utils::pin_mut!(stream);

// Using `scan` here because it is able to stop the stream early
Expand All @@ -43,6 +43,6 @@ where
Some(err) => Err(err),
None => Ok(out),
}
}))
})
}
}
11 changes: 4 additions & 7 deletions src/vec/from_stream.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
use std::pin::Pin;

use crate::prelude::*;
use crate::stream::{FromStream, IntoStream};
use crate::stream::{Extend, FromStream, IntoStream};

impl<T> FromStream<T> for Vec<T> {
#[inline]
Expand All @@ -13,14 +12,12 @@ impl<T> FromStream<T> for Vec<T> {
{
let stream = stream.into_stream();

Pin::from(Box::new(async move {
Box::pin(async move {
pin_utils::pin_mut!(stream);

let mut out = vec![];
while let Some(item) = stream.next().await {
out.push(item);
}
out.stream_extend(stream).await;
out
}))
})
}
}