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

use std::future::Future;

/// Checks a request synchronously
pub trait Predicate<Request, B> {
    /// The type of requests returned by [`check`](Predicate::check).
    ///
    /// This request is forwarded to the inner service if the predicate
    /// succeeds.
    type Request;

    /// The type of response return by [`check`](Predicate::check) if the predicate failed.
    type Response;

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

impl<T, Req, Res, B, F> Predicate<T, B> for F
where
    F: FnMut(T) -> Result<Req, Res>,
{
    type Request = Req;
    type Response = Res;

    fn check(&mut self, request: T) -> Result<Self::Request, Self::Response> {
        self(request)
    }
}

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

    /// The type of response return by [`check`](AsyncPredicate::check) if the predicate failed.
    type Response;

    /// The future returned by [`check`](AsyncPredicate::check)
    type Future: Future<Output = Result<Self::Request, Self::Response>>;

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

impl<T, Req, Res, B, U, F> AsyncPredicate<T, B> for F
where
    F: FnMut(T) -> U,
    U: Future<Output = Result<Req, Res>>,
{
    type Request = Req;
    type Response = Res;
    type Future = U;

    fn check(&mut self, request: T) -> Self::Future {
        self(request)
    }
}