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
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89

use std::fmt;

use tower_async_layer::Layer;
use tower_async_service::Service;

/// Service returned by the [`and_then`] combinator.
///
/// [`and_then`]: crate::util::ServiceExt::and_then
#[derive(Clone)]
pub struct AndThen<S, F> {
    inner: S,
    f: F,
}

impl<S, F> fmt::Debug for AndThen<S, F>
where
    S: fmt::Debug,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("AndThen")
            .field("inner", &self.inner)
            .field("f", &format_args!("{}", std::any::type_name::<F>()))
            .finish()
    }
}

/// A [`Layer`] that produces a [`AndThen`] service.
///
/// [`Layer`]: tower_async_layer::Layer
#[derive(Clone, Debug)]
pub struct AndThenLayer<F> {
    f: F,
}

impl<S, F> AndThen<S, F> {
    /// Creates a new `AndThen` service.
    pub fn new(inner: S, f: F) -> Self {
        AndThen { f, inner }
    }

    /// Returns a new [`Layer`] that produces [`AndThen`] services.
    ///
    /// This is a convenience function that simply calls [`AndThenLayer::new`].
    ///
    /// [`Layer`]: tower_async_layer::Layer
    pub fn layer(f: F) -> AndThenLayer<F> {
        AndThenLayer { f }
    }
}

impl<S, F, Request, Fut, Output, Error> Service<Request> for AndThen<S, F>
where
    S: Service<Request>,
    S::Error: Into<Error>,
    F: Fn(S::Response) -> Fut,
    Fut: std::future::Future<Output = Result<Output, Error>>,
{
    type Response = Output;
    type Error = Error;

    async fn call(&self, request: Request) -> Result<Self::Response, Self::Error> {
        let result = self.inner.call(request).await;
        match result {
            Ok(response) => (self.f)(response).await,
            Err(error) => Err(error.into()),
        }
    }
}

impl<F> AndThenLayer<F> {
    /// Creates a new [`AndThenLayer`] layer.
    pub fn new(f: F) -> Self {
        AndThenLayer { f }
    }
}

impl<S, F> Layer<S> for AndThenLayer<F>
where
    F: Clone,
{
    type Service = AndThen<S, F>;

    fn layer(&self, inner: S) -> Self::Service {
        AndThen {
            f: self.f.clone(),
            inner,
        }
    }
}