tower-async 0.2.0

Tower Async is a library of modular and reusable components for building robust clients and servers. An "Async Trait" fork from the original Tower Library.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63

use futures_core::Future;
use futures_util::TryFutureExt;

use crate::BoxError;

/// Checks a request asynchronously.
pub trait AsyncPredicate<Request> {
    /// The type of requests returned by [`check`].
    ///
    /// This request is forwarded to the inner service if the predicate
    /// succeeds.
    ///
    /// [`check`]: crate::filter::AsyncPredicate::check
    type Request;

    /// Check whether the given request should be forwarded.
    ///
    /// If the future resolves with [`Ok`], the request is forwarded to the inner service.
    fn check(
        &self,
        request: Request,
    ) -> impl std::future::Future<Output = Result<Self::Request, BoxError>>;
}
/// Checks a request synchronously.
pub trait Predicate<Request> {
    /// The type of requests returned by [`check`].
    ///
    /// This request is forwarded to the inner service if the predicate
    /// succeeds.
    ///
    /// [`check`]: crate::filter::Predicate::check
    type Request;

    /// Check whether the given request should be forwarded.
    ///
    /// If the future resolves with [`Ok`], the request is forwarded to the inner service.
    fn check(&self, request: Request) -> Result<Self::Request, BoxError>;
}

impl<F, T, U, R, E> AsyncPredicate<T> for F
where
    F: Fn(T) -> U,
    U: Future<Output = Result<R, E>>,
    E: Into<BoxError>,
{
    type Request = R;

    async fn check(&self, request: T) -> Result<Self::Request, BoxError> {
        self(request).err_into().await
    }
}

impl<F, T, R, E> Predicate<T> for F
where
    F: Fn(T) -> Result<R, E>,
    E: Into<BoxError>,
{
    type Request = R;

    fn check(&self, request: T) -> Result<Self::Request, BoxError> {
        self(request).map_err(Into::into)
    }
}