forked from mirror/async-std
Merge branch 'master' into add_stream_flatten
k-nasa
5 years ago
commit
040227f38a
@ -0,0 +1,66 @@
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use std::pin::Pin;
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use crate::prelude::*;
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use crate::stream::{Stream, Product};
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impl<T, U> Product<Option<U>> for Option<T>
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where
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T: Product<U>,
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{
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#[doc = r#"
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Takes each element in the `Stream`: if it is a `None`, no further
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elements are taken, and the `None` is returned. Should no `None` occur,
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the product of all elements is returned.
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# Examples
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This multiplies every integer in a vector, rejecting the product if a negative element is
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encountered:
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```
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# fn main() { async_std::task::block_on(async {
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#
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use std::collections::VecDeque;
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use async_std::prelude::*;
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let v: VecDeque<_> = vec![1, 2, 4].into_iter().collect();
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let prod: Option<i32> = v.map(|x|
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if x < 0 {
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None
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} else {
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Some(x)
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}).product().await;
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assert_eq!(prod, Some(8));
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#
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# }) }
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```
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"#]
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fn product<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Option<T>> + 'a>>
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where S: Stream<Item = Option<U>> + 'a
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{
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Box::pin(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_none = false;
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let out = <T as Product<U>>::product(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_none = 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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})).await;
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if found_none {
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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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@ -0,0 +1,63 @@
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use std::pin::Pin;
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use crate::prelude::*;
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use crate::stream::{Stream, Sum};
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impl<T, U> Sum<Option<U>> for Option<T>
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where
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T: Sum<U>,
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{
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#[doc = r#"
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Takes each element in the `Iterator`: if it is a `None`, no further
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elements are taken, and the `None` is returned. Should no `None` occur,
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the sum of all elements is returned.
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# Examples
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This sums up the position of the character 'a' in a vector of strings,
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if a word did not have the character 'a' the operation returns `None`:
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```
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# fn main() { async_std::task::block_on(async {
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#
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use std::collections::VecDeque;
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use async_std::prelude::*;
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let words: VecDeque<_> = vec!["have", "a", "great", "day"]
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.into_iter()
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.collect();
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let total: Option<usize> = words.map(|w| w.find('a')).sum().await;
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assert_eq!(total, Some(5));
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#
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# }) }
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```
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"#]
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fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Option<T>> + 'a>>
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where S: Stream<Item = Option<U>> + 'a
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{
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Box::pin(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_none = false;
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let out = <T as Sum<U>>::sum(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_none = 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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})).await;
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if found_none {
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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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@ -0,0 +1,64 @@
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use std::pin::Pin;
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use crate::prelude::*;
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use crate::stream::{Stream, Product};
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impl<T, U, E> Product<Result<U, E>> for Result<T, E>
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where
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T: Product<U>,
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{
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#[doc = r#"
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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` occur,
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the product of all elements is returned.
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# Examples
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This multiplies every integer in a vector, rejecting the product if a negative element is
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encountered:
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```
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# fn main() { async_std::task::block_on(async {
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#
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use std::collections::VecDeque;
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use async_std::prelude::*;
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let v: VecDeque<_> = vec![1, 2, 4].into_iter().collect();
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let res: Result<i32, &'static str> = v.map(|x|
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if x < 0 {
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Err("Negative element found")
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} else {
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Ok(x)
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}).product().await;
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assert_eq!(res, Ok(8));
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#
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# }) }
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```
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"#]
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fn product<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Result<T, E>> + 'a>>
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where S: Stream<Item = Result<U, E>> + 'a
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{
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Box::pin(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 = None;
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let out = <T as Product<U>>::product(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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})).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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@ -0,0 +1,64 @@
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use std::pin::Pin;
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use crate::prelude::*;
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use crate::stream::{Stream, Sum};
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impl<T, U, E> Sum<Result<U, E>> for Result<T, E>
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where
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T: Sum<U>,
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{
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#[doc = r#"
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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` occur,
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the sum of all elements is returned.
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# Examples
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This sums up every integer in a vector, rejecting the sum if a negative
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element is encountered:
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```
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# fn main() { async_std::task::block_on(async {
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#
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use std::collections::VecDeque;
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use async_std::prelude::*;
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let v: VecDeque<_> = vec![1, 2].into_iter().collect();
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let res: Result<i32, &'static str> = v.map(|x|
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if x < 0 {
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Err("Negative element found")
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} else {
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Ok(x)
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}).sum().await;
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assert_eq!(res, Ok(3));
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#
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# }) }
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```
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"#]
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fn sum<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Result<T, E>> + 'a>>
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where S: Stream<Item = Result<U, E>> + 'a
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{
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Box::pin(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 = None;
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let out = <T as Sum<U>>::sum(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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})).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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@ -0,0 +1,63 @@
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use std::error::Error;
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use std::fmt;
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use std::pin::Pin;
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use std::time::Duration;
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use futures_timer::Delay;
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use pin_project_lite::pin_project;
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use crate::future::Future;
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use crate::stream::Stream;
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use crate::task::{Context, Poll};
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pin_project! {
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/// A stream with timeout time set
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#[derive(Debug)]
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pub struct Timeout<S: Stream> {
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#[pin]
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stream: S,
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#[pin]
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delay: Delay,
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}
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}
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impl<S: Stream> Timeout<S> {
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pub fn new(stream: S, dur: Duration) -> Timeout<S> {
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let delay = Delay::new(dur);
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Timeout { stream, delay }
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}
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}
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impl<S: Stream> Stream for Timeout<S> {
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type Item = Result<S::Item, TimeoutError>;
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fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
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let this = self.project();
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match this.stream.poll_next(cx) {
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Poll::Ready(Some(v)) => Poll::Ready(Some(Ok(v))),
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Poll::Ready(None) => Poll::Ready(None),
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Poll::Pending => match this.delay.poll(cx) {
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Poll::Ready(_) => Poll::Ready(Some(Err(TimeoutError { _private: () }))),
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Poll::Pending => Poll::Pending,
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},
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}
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}
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}
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/// An error returned when a stream times out.
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#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
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#[cfg(any(feature = "unstable", feature = "docs"))]
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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pub struct TimeoutError {
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_private: (),
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}
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impl Error for TimeoutError {}
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impl fmt::Display for TimeoutError {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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"stream has timed out".fmt(f)
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}
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}
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