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.
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use std::fmt;

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

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

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

/// A [`Layer`] that produces [`MapErr`] services.
///
/// [`Layer`]: tower_async_layer::Layer
#[derive(Clone, Debug)]
pub struct MapErrLayer<F> {
    f: F,
}

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

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

impl<S, F, Request, Error> Service<Request> for MapErr<S, F>
where
    S: Service<Request>,
    F: Fn(S::Error) -> Error,
{
    type Response = S::Response;
    type Error = Error;

    #[inline]
    async fn call(&self, request: Request) -> Result<Self::Response, Self::Error> {
        match self.inner.call(request).await {
            Ok(response) => Ok(response),
            Err(error) => Err((self.f)(error)),
        }
    }
}

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

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

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