1 files changed, 112 insertions, 0 deletions
diff --git a/vendor/tower-layer/src/lib.rs b/vendor/tower-layer/src/lib.rs
new file mode 100644
index 00000000..4823fcc1
--- /dev/null
+++ b/vendor/tower-layer/src/lib.rs
@@ -0,0 +1,112 @@
+#![warn(
+    missing_debug_implementations,
+    missing_docs,
+    rust_2018_idioms,
+    unreachable_pub
+)]
+#![forbid(unsafe_code)]
+// `rustdoc::broken_intra_doc_links` is checked on CI
+
+//! Layer traits and extensions.
+//!
+//! A layer decorates an service and provides additional functionality. It
+//! allows other services to be composed with the service that implements layer.
+//!
+//! A middleware implements the [`Layer`] and [`Service`] trait.
+//!
+//! [`Service`]: https://docs.rs/tower/*/tower/trait.Service.html
+
+mod identity;
+mod layer_fn;
+mod stack;
+mod tuple;
+
+pub use self::{
+    identity::Identity,
+    layer_fn::{layer_fn, LayerFn},
+    stack::Stack,
+};
+
+/// Decorates a [`Service`], transforming either the request or the response.
+///
+/// Often, many of the pieces needed for writing network applications can be
+/// reused across multiple services. The `Layer` trait can be used to write
+/// reusable components that can be applied to very different kinds of services;
+/// for example, it can be applied to services operating on different protocols,
+/// and to both the client and server side of a network transaction.
+///
+/// # Log
+///
+/// Take request logging as an example:
+///
+/// ```rust
+/// # use tower_service::Service;
+/// # use std::task::{Poll, Context};
+/// # use tower_layer::Layer;
+/// # use std::fmt;
+///
+/// pub struct LogLayer {
+///     target: &'static str,
+/// }
+///
+/// impl<S> Layer<S> for LogLayer {
+///     type Service = LogService<S>;
+///
+///     fn layer(&self, service: S) -> Self::Service {
+///         LogService {
+///             target: self.target,
+///             service
+///         }
+///     }
+/// }
+///
+/// // This service implements the Log behavior
+/// pub struct LogService<S> {
+///     target: &'static str,
+///     service: S,
+/// }
+///
+/// impl<S, Request> Service<Request> for LogService<S>
+/// where
+///     S: Service<Request>,
+///     Request: fmt::Debug,
+/// {
+///     type Response = S::Response;
+///     type Error = S::Error;
+///     type Future = S::Future;
+///
+///     fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+///         self.service.poll_ready(cx)
+///     }
+///
+///     fn call(&mut self, request: Request) -> Self::Future {
+///         // Insert log statement here or other functionality
+///         println!("request = {:?}, target = {:?}", request, self.target);
+///         self.service.call(request)
+///     }
+/// }
+/// ```
+///
+/// The above log implementation is decoupled from the underlying protocol and
+/// is also decoupled from client or server concerns. In other words, the same
+/// log middleware could be used in either a client or a server.
+///
+/// [`Service`]: https://docs.rs/tower/*/tower/trait.Service.html
+pub trait Layer<S> {
+    /// The wrapped service
+    type Service;
+    /// Wrap the given service with the middleware, returning a new service
+    /// that has been decorated with the middleware.
+    fn layer(&self, inner: S) -> Self::Service;
+}
+
+impl<'a, T, S> Layer<S> for &'a T
+where
+    T: ?Sized + Layer<S>,
+{
+    type Service = T::Service;
+
+    fn layer(&self, inner: S) -> Self::Service {
+        (**self).layer(inner)
+    }
+}