Refactor Rejection system

- Improved performance of "known" rejections, by not needing to store
  them as `Box<dyn std::error::Error>` in order to satisfy
  `Rejection::cause()`.
- `reject::custom()` no longer requires `std::error::Error`, just
  `Reject + Debug`. This should make it less annoying to construct new
  custom rejections.
- Removed deprecated features:
  - `Rejection::cause()`
  - `Rejection::into_cause()`
  - `Rejection::status()`
  - `Rejection::with()`
  - `Rejection::json()`
  - `impl Serialize for Rejection`
  - `reject::bad_request()`
  - `reject::forbidden()`
  - `reject::server_error()`
- Removed `path::param2()`.

examples/errors.rs

@@ -1,44 +1,36 @@
 #![deny(warnings)]
 
-use std::error::Error as StdError;
-use std::fmt::{self, Display};
-
 use serde_derive::Serialize;
 use warp::http::StatusCode;
-use warp::{Future, Filter, Rejection, Reply};
+use warp::{reject, Filter, Rejection, Reply};
 
-#[derive(Copy, Clone, Debug)]
+/// A custom `Reject` type.
+#[derive(Debug)]
 enum Error {
     Oops,
     Nope,
 }
 
+impl reject::Reject for Error {}
+
+/// A serialized message to report in JSON format.
 #[derive(Serialize)]
-struct ErrorMessage {
+struct ErrorMessage<'a> {
     code: u16,
-    message: String,
-}
-
-impl Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.write_str(match self {
-            Error::Oops => ":fire: this is fine",
-            Error::Nope => "Nope!",
-        })
-    }
+    message: &'a str,
 }
 
-impl StdError for Error {}
-
 #[tokio::main]
 async fn main() {
     let hello = warp::path::end().map(warp::reply);
 
-    let oops =
-        warp::path("oops").and_then(|| futures::future::err::<StatusCode, _>(warp::reject::custom(Error::Oops)));
+    let oops = warp::path("oops").and_then(|| async {
+        Err::<StatusCode, _>(reject::custom(Error::Oops))
+    });
 
-    let nope =
-        warp::path("nope").and_then(|| futures::future::err::<StatusCode, _>(warp::reject::custom(Error::Nope)));
+    let nope = warp::path("nope").and_then(|| async {
+        Err::<StatusCode, _>(reject::custom(Error::Nope))
+    });
 
     let routes = warp::get()
         .and(hello.or(oops).or(nope))
@@ -49,34 +41,30 @@ async fn main() {
 
 // This function receives a `Rejection` and tries to return a custom
 // value, othewise simply passes the rejection along.
-fn customize_error(err: Rejection) -> impl Future< Output = Result<impl Reply, Rejection>> {
-    let err = {
-        if let Some(&err) = err.find_cause::<Error>() {
-            let code = match err {
-                Error::Nope => StatusCode::BAD_REQUEST,
-                Error::Oops => StatusCode::INTERNAL_SERVER_ERROR,
-            };
-            let msg = err.to_string();
+async fn customize_error(err: Rejection) -> Result<impl Reply, Rejection> {
+    if let Some(err) = err.find::<Error>() {
+        let (code, msg) = match err {
+            Error::Nope => (StatusCode::BAD_REQUEST, "Nope!"),
+            Error::Oops => (StatusCode::INTERNAL_SERVER_ERROR, ":fire: this is fine"),
+        };
 
             let json = warp::reply::json(&ErrorMessage {
                 code: code.as_u16(),
                 message: msg,
             });
             Ok(warp::reply::with_status(json, code))
-        } else if let Some(_) = err.find_cause::<warp::reject::MethodNotAllowed>() {
-            // We can handle a specific error, here METHOD_NOT_ALLOWED,
-            // and render it however we want
-            let code = StatusCode::METHOD_NOT_ALLOWED;
-            let json = warp::reply::json(&ErrorMessage {
-                code: code.as_u16(),
-                message: "oops, you aren't allowed to use this method.".into(),
-            });
-            Ok(warp::reply::with_status(json, code))
-        } else {
-            // Could be a NOT_FOUND, or any other internal error... here we just
-            // let warp use its default rendering.
-            Err(err)
-        }
-    };
-    futures::future::ready(err)
+    } else if let Some(_) = err.find::<warp::reject::MethodNotAllowed>() {
+        // We can handle a specific error, here METHOD_NOT_ALLOWED,
+        // and render it however we want
+        let code = StatusCode::METHOD_NOT_ALLOWED;
+        let json = warp::reply::json(&ErrorMessage {
+            code: code.as_u16(),
+            message: "oops, you aren't allowed to use this method.".into(),
+        });
+        Ok(warp::reply::with_status(json, code))
+    } else {
+        // Could be a NOT_FOUND, or any other internal error... here we just
+        // let warp use its default rendering.
+        Err(err)
+    }
 }

examples/futures.rs

@@ -23,7 +23,7 @@ impl FromStr for Seconds {
 
 #[tokio::main]
 async fn main() {
-    // Match `/:u32`...
+    // Match `/:Seconds`...
     let routes = warp::path::param()
         // and_then create a `Future` that will simply wait N seconds...
         .and_then(|Seconds(seconds): Seconds| async move {

examples/sse_chat.rs

@@ -16,6 +16,10 @@ enum Message {
     Reply(String),
 }
 
+#[derive(Debug)]
+struct NotUtf8;
+impl warp::reject::Reject for NotUtf8 {}
+
 /// Our state of currently connected users.
 ///
 /// - Key is their id
@@ -40,7 +44,7 @@ async fn main() {
         .and(warp::body::concat().and_then(|body: warp::body::FullBody| {
             future::ready(std::str::from_utf8(body.bytes())
                 .map(String::from)
-                .map_err(warp::reject::custom))
+                .map_err(|_e| warp::reject::custom(NotUtf8))
         }))
         .and(users.clone())
         .map(|my_id, msg, users| {

src/filter/map_err.rs

@@ -6,7 +6,7 @@ use pin_project::pin_project;
 use futures::TryFuture;
 
 use super::{Filter, FilterBase};
-use crate::reject::Reject;
+use crate::reject::IsReject;
 
 #[derive(Clone, Copy, Debug)]
 pub struct MapErr<T, F> {
@@ -18,7 +18,7 @@ impl<T, F, E> FilterBase for MapErr<T, F>
 where
     T: Filter,
     F: Fn(T::Error) -> E + Clone + Send,
-    E: Reject,
+    E: IsReject,
 {
     type Extract = T::Extract;
     type Error = E;

src/filter/mod.rs

@@ -17,7 +17,7 @@ use std::future::Future;
 use futures::{future, TryFuture, TryFutureExt};
 
 pub(crate) use crate::generic::{one, Combine, Either, Func, HList, One, Tuple};
-use crate::reject::{CombineRejection, Reject, Rejection};
+use crate::reject::{CombineRejection, IsReject, Rejection};
 use crate::route::{self, Route};
 
 pub(crate) use self::and::And;
@@ -36,7 +36,7 @@ pub(crate) use self::wrap::{Wrap, WrapSealed};
 // signatures without it being a breaking change.
 pub trait FilterBase {
     type Extract: Tuple; // + Send;
-    type Error: Reject;
+    type Error: IsReject;
     type Future: Future<Output = Result<Self::Extract, Self::Error>> + Send;
 
     fn filter(&self) -> Self::Future;
@@ -416,7 +416,7 @@ where
     F: Fn(&mut Route) -> U,
     U: TryFuture,
     U::Ok: Tuple,
-    U::Error: Reject,
+    U::Error: IsReject,
 {
     FilterFn { func }
 }
@@ -427,7 +427,7 @@ pub(crate) fn filter_fn_one<F, U>(
 where
     F: Fn(&mut Route) -> U + Copy,
     U: TryFuture,
-    U::Error: Reject,
+    U::Error: IsReject,
 {
     filter_fn(move |route| func(route).map_ok(tup_one as _))
 }
@@ -448,7 +448,7 @@ where
     F: Fn(&mut Route) -> U,
     U: TryFuture + Send + 'static,
     U::Ok: Tuple + Send,
-    U::Error: Reject,
+    U::Error: IsReject,
 {
     type Extract = U::Ok;
     type Error = U::Error;

src/filter/service.rs

@@ -6,7 +6,7 @@ use std::future::Future;
 use pin_project::pin_project;
 use futures::future::TryFuture;
 
-use crate::reject::Reject;
+use crate::reject::IsReject;
 use crate::reply::Reply;
 use crate::route::{self, Route};
 use crate::server::{IntoWarpService, WarpService};
@@ -21,7 +21,7 @@ impl<F> WarpService for FilteredService<F>
 where
     F: Filter,
     <F::Future as TryFuture>::Ok: Reply,
-    <F::Future as TryFuture>::Error: Reject,
+    <F::Future as TryFuture>::Error: IsReject,
 {
     type Reply = FilteredFuture<F::Future>;
 
@@ -66,8 +66,8 @@ impl<F> IntoWarpService for FilteredService<F>
 where
     F: Filter + Send + Sync + 'static,
     F::Extract: Reply,
-    F::Error: Reject,
-    {
+    F::Error: IsReject,
+{
     type Service = FilteredService<F>;
 
     #[inline]
@@ -80,8 +80,8 @@ impl<F> IntoWarpService for F
 where
     F: Filter + Send + Sync + 'static,
     F::Extract: Reply,
-    F::Error: Reject,
-    {
+    F::Error: IsReject,
+{
     type Service = FilteredService<F>;
 
     #[inline]

src/filters/log.rs

@@ -8,7 +8,7 @@ use http::{self, header, StatusCode};
 use tokio::clock;
 
 use crate::filter::{Filter, WrapSealed};
-use crate::reject::Reject;
+use crate::reject::IsReject;
 use crate::reply::Reply;
 use crate::route::Route;
 
@@ -97,7 +97,7 @@ where
     FN: Fn(Info) + Clone + Send,
     F: Filter + Clone + Send,
     F::Extract: Reply,
-    F::Error: Reject,
+    F::Error: IsReject,
 {
     type Wrapped = WithLog<FN, F>;
 
@@ -188,7 +188,7 @@ mod internal {
 
     use super::{Info, Log};
     use crate::filter::{Filter, FilterBase};
-    use crate::reject::Reject;
+    use crate::reject::IsReject;
     use crate::reply::{Reply, Response};
     use crate::route;
 
@@ -214,7 +214,7 @@ mod internal {
         FN: Fn(Info) + Clone + Send,
         F: Filter + Clone + Send,
         F::Extract: Reply,
-        F::Error: Reject,
+        F::Error: IsReject,
     {
         type Extract = (Logged,);
         type Error = F::Error;
@@ -244,7 +244,7 @@ mod internal {
         FN: Fn(Info),
         F: TryFuture,
         F::Ok: Reply,
-        F::Error: Reject,
+        F::Error: IsReject,
     {
         type Output = Result<(Logged,), F::Error>;
 

src/filters/path.rs

@@ -238,42 +238,6 @@ pub fn param<T: FromStr + Send + 'static>() -> impl Filter<Extract = One<T>, Err
     })
 }
 
-/// Extract a parameter from a path segment.
-///
-/// This will try to parse a value from the current request path
-/// segment, and if successful, the value is returned as the `Filter`'s
-/// "extracted" value.
-///
-/// If the value could not be parsed, rejects with a `404 Not Found`. In
-/// contrast of `param` method, it reports an error cause in response.
-///
-/// # Example
-///
-/// ```
-/// use warp::Filter;
-///
-/// let route = warp::path::param2()
-///     .map(|id: u32| {
-///         format!("You asked for /{}", id)
-///     });
-/// ```
-pub fn param2<T>() -> impl Filter<Extract = One<T>, Error = Rejection> + Copy
-where
-    T: FromStr + Send + 'static,
-    T::Err: Into<crate::reject::Cause>,
-{
-    segment(|seg| {
-        log::trace!("param?: {:?}", seg);
-        if seg.is_empty() {
-            return Err(reject::not_found());
-        }
-        T::from_str(seg).map(one).map_err(|err| {
-            #[allow(deprecated)]
-            reject::not_found().with(err.into())
-        })
-    })
-}
-
 /// Extract the unmatched tail of the path.
 ///
 /// This will return a `Tail`, which allows access to the rest of the path

src/filters/sse.rs

@@ -304,10 +304,7 @@ where
     header::header("last-event-id")
         .map(Some)
         .or_else(|rejection: Rejection| {
-            if rejection
-                .find_cause::<crate::reject::MissingHeader>()
-                .is_some()
-            {
+            if rejection.find::<crate::reject::MissingHeader>().is_some() {
                 return future::ok((None,));
             }
             future::err(rejection)
@@ -336,10 +333,7 @@ pub fn sse() -> impl Filter<Extract = One<Sse>, Error = Rejection> + Copy {
         .and(
             header::exact_ignore_case("connection", "keep-alive").or_else(
                 |rejection: Rejection| {
-                    if rejection
-                        .find_cause::<crate::reject::MissingHeader>()
-                        .is_some()
-                    {
+                    if rejection.find::<crate::reject::MissingHeader>().is_some() {
                         return future::ok(());
                     }
                     future::err(rejection)