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feat: Add Stream::flat_map

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This commit is contained in:
k-nasa 2019-10-18 10:43:36 +09:00
parent 2dee289750
commit 2187a2a31d
1 changed files with 39 additions and 2 deletions
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41
src/stream/stream/mod.rs
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@ -30,6 +30,7 @@ mod filter;
mod filter_map; mod filter_map;
mod find; mod find;
mod find_map; mod find_map;
mod flatten;
mod fold; mod fold;
mod for_each; mod for_each;
mod fuse; mod fuse;
@ -77,6 +78,7 @@ use try_for_each::TryForEeachFuture;
pub use chain::Chain; pub use chain::Chain;
pub use filter::Filter; pub use filter::Filter;
pub use flatten::FlatMap;
pub use fuse::Fuse; pub use fuse::Fuse;
pub use inspect::Inspect; pub use inspect::Inspect;
pub use map::Map; pub use map::Map;
@ -93,6 +95,7 @@ use std::marker::PhantomData;
use cfg_if::cfg_if; use cfg_if::cfg_if;
use crate::stream::IntoStream;
use crate::utils::extension_trait; use crate::utils::extension_trait;
cfg_if! { cfg_if! {
@ -106,7 +109,6 @@ cfg_if! {
cfg_if! { cfg_if! {
if #[cfg(any(feature = "unstable", feature = "docs"))] { if #[cfg(any(feature = "unstable", feature = "docs"))] {
mod merge; mod merge;
mod flatten;
use std::pin::Pin; use std::pin::Pin;
@ -496,7 +498,6 @@ extension_trait! {
# #
# }) } # }) }
``` ```
"#] "#]
fn last( fn last(
self, self,
@ -570,6 +571,42 @@ extension_trait! {
Filter::new(self, predicate) Filter::new(self, predicate)
} }
#[doc= r#"
Creates an stream that works like map, but flattens nested structure.
# Examples
Basic usage:
```
# async_std::task::block_on(async {
use std::collections::VecDeque;
use async_std::prelude::*;
use async_std::stream::IntoStream;
let inner1: VecDeque<u8> = vec![1,2,3].into_iter().collect();
let inner2: VecDeque<u8> = vec![4,5,6].into_iter().collect();
let s: VecDeque<_> = vec![inner1, inner2].into_iter().collect();
let flat= s.flat_map(|s| s.into_stream() );
let v: Vec<u8> = flat.collect().await;
assert_eq!(v, vec![1,2,3,4,5,6]);
# });
```
"#]
fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>
where
Self: Sized,
U: IntoStream,
F: FnMut(Self::Item) -> U,
{
FlatMap::new(self, f)
}
#[doc = r#" #[doc = r#"
Both filters and maps a stream. Both filters and maps a stream.