tower-util 0.1.0

Utilities for working with `Service`. 
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use crate::sealed::Sealed;
use futures::{Future, Poll};
use tokio_io::{AsyncRead, AsyncWrite};
use tower_service::Service;

/// The MakeConnection trait is used to create transports
///
/// The goal of this service is to allow composable methods for creating
/// `AsyncRead + AsyncWrite` transports. This could mean creating a TLS
/// based connection or using some other method to authenticate the connection.
pub trait MakeConnection<Target>: Sealed<(Target,)> {
    /// The transport provided by this service
    type Connection: AsyncRead + AsyncWrite;

    /// Errors produced by the connecting service
    type Error;

    /// The future that eventually produces the transport
    type Future: Future<Item = Self::Connection, Error = Self::Error>;

    /// Returns `Ready` when it is able to make more connections.
    fn poll_ready(&mut self) -> Poll<(), Self::Error>;

    /// Connect and return a transport asynchronously
    fn make_connection(&mut self, target: Target) -> Self::Future;
}

impl<S, Target> Sealed<(Target,)> for S where S: Service<Target> {}

impl<C, Target> MakeConnection<Target> for C
where
    C: Service<Target>,
    C::Response: AsyncRead + AsyncWrite,
{
    type Connection = C::Response;
    type Error = C::Error;
    type Future = C::Future;

    fn poll_ready(&mut self) -> Poll<(), Self::Error> {
        Service::poll_ready(self)
    }

    fn make_connection(&mut self, target: Target) -> Self::Future {
        Service::call(self, target)
    }
}