pub trait Product<A = Self>: Sized {
// Required method
fn product<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Self> + 'a>>
where S: Stream<Item = A> + 'a;
}Expand description
Trait to represent types that can be created by multiplying the elements of a stream.
This trait is used to implement the product method on streams. Types which
implement the trait can be generated by the product method. Like
FromStream this trait should rarely be called directly and instead
interacted with through Stream::product.
Required Methods§
Object Safety§
Implementations on Foreign Types§
source§impl<T, U> Product<Option<U>> for Option<T>where
T: Product<U>,
impl<T, U> Product<Option<U>> for Option<T>where
T: Product<U>,
source§fn product<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Option<T>> + 'a>>
fn product<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Option<T>> + 'a>>
Takes each element in the Stream: if it is a None, no further
elements are taken, and the None is returned. Should no None occur,
the product of all elements is returned.
Examples
This multiplies every integer in a vector, rejecting the product if a negative element is encountered:
use async_std::prelude::*;
use async_std::stream;
let v = stream::from_iter(vec![1, 2, 4]);
let prod: Option<i32> = v.map(|x|
if x < 0 {
None
} else {
Some(x)
}).product().await;
assert_eq!(prod, Some(8));source§impl<T, U, E> Product<Result<U, E>> for Result<T, E>where
T: Product<U>,
impl<T, U, E> Product<Result<U, E>> for Result<T, E>where
T: Product<U>,
source§fn product<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Result<T, E>> + 'a>>
fn product<'a, S>(stream: S) -> Pin<Box<dyn Future<Output = Result<T, E>> + 'a>>
Takes each element in the Stream: if it is an Err, no further
elements are taken, and the Err is returned. Should no Err occur,
the product of all elements is returned.
Examples
This multiplies every integer in a vector, rejecting the product if a negative element is encountered:
use async_std::prelude::*;
use async_std::stream;
let v = stream::from_iter(vec![1, 2, 4]);
let res: Result<i32, &'static str> = v.map(|x|
if x < 0 {
Err("Negative element found")
} else {
Ok(x)
}).product().await;
assert_eq!(res, Ok(8));