76 lines
1.3 KiB
Rust
76 lines
1.3 KiB
Rust
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// build-pass
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fn main() {
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let mut log_service = LogService { inner: Inner };
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log_service.call(());
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}
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pub trait Service<Request> {
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type Response;
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fn call(&mut self, req: Request) -> Self::Response;
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}
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pub struct LogService<S> {
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inner: S,
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}
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impl<T, U, S> Service<T> for LogService<S>
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where
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S: Service<T, Response = U>,
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U: Extension + 'static,
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for<'a> U::Item<'a>: std::fmt::Debug,
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{
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type Response = S::Response;
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fn call(&mut self, req: T) -> Self::Response {
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self.inner.call(req)
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}
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}
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pub struct Inner;
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impl Service<()> for Inner {
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type Response = Resp;
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fn call(&mut self, req: ()) -> Self::Response {
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Resp::A(req)
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}
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}
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pub trait Extension {
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type Item<'a>;
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fn touch<F>(self, f: F) -> Self
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where
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for<'a> F: Fn(Self::Item<'a>);
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}
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pub enum Resp {
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A(()),
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}
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impl Extension for Resp {
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type Item<'a> = RespItem<'a>;
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fn touch<F>(self, _f: F) -> Self
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where
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for<'a> F: Fn(Self::Item<'a>),
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{
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match self {
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Self::A(a) => Self::A(a),
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}
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}
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}
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pub enum RespItem<'a> {
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A(&'a ()),
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}
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impl<'a> std::fmt::Debug for RespItem<'a> {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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match self {
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Self::A(arg0) => f.debug_tuple("A").field(arg0).finish(),
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}
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}
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}
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