simplify Resource trait (#2568)

Co-authored-by: Rob Ede <robjtede@icloud.com>

actix-router/CHANGES.md

@@ -1,6 +1,10 @@
 # Changes
 
 ## Unreleased - 2021-xx-xx
+- `Resource` trait now have an associated type, `Path`, instead of the generic parameter. [#2568]
+- `Resource` is now implemented for `&mut Path<_>` and `RefMut<Path<_>>`. [#2568]
+
+[#2568]: https://github.com/actix/actix-web/pull/2568
 
 
 ## 0.5.0-beta.4 - 2022-01-04

actix-router/src/path.rs

@@ -1,5 +1,5 @@
 use std::borrow::Cow;
-use std::ops::Index;
+use std::ops::{DerefMut, Index};
 
 use firestorm::profile_method;
 use serde::de;
@@ -213,8 +213,38 @@ impl<T: ResourcePath> Index<usize> for Path<T> {
     }
 }
 
-impl<T: ResourcePath> Resource<T> for Path<T> {
-    fn resource_path(&mut self) -> &mut Self {
+impl<T: ResourcePath> Resource for Path<T> {
+    type Path = T;
+
+    fn resource_path(&mut self) -> &mut Path<Self::Path> {
         self
     }
 }
+
+impl<T, P> Resource for T
+where
+    T: DerefMut<Target = Path<P>>,
+    P: ResourcePath,
+{
+    type Path = P;
+
+    fn resource_path(&mut self) -> &mut Path<Self::Path> {
+        &mut *self
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::cell::RefCell;
+
+    use super::*;
+
+    #[test]
+    fn deref_impls() {
+        let mut foo = Path::new("/foo");
+        let _ = (&mut foo).resource_path();
+
+        let foo = RefCell::new(foo);
+        let _ = foo.borrow_mut().resource_path();
+    }
+}

actix-router/src/resource.rs

@@ -678,15 +678,14 @@ impl ResourceDef {
     /// assert!(!try_match(&resource, &mut path));
     /// assert_eq!(path.unprocessed(), "/user/admin/stars");
     /// ```
-    pub fn capture_match_info_fn<R, T, F, U>(
+    pub fn capture_match_info_fn<R, F, U>(
         &self,
         resource: &mut R,
         check_fn: F,
         user_data: U,
     ) -> bool
     where
-        R: Resource<T>,
-        T: ResourcePath,
+        R: Resource,
         F: FnOnce(&R, U) -> bool,
     {
         profile_method!(capture_match_info_fn);

actix-router/src/resource_path.rs

@@ -2,8 +2,11 @@ use crate::Path;
 
 // TODO: this trait is necessary, document it
 // see impl Resource for ServiceRequest
-pub trait Resource<T: ResourcePath> {
-    fn resource_path(&mut self) -> &mut Path<T>;
+pub trait Resource {
+    /// Type of resource's path returned in `resource_path`.
+    type Path: ResourcePath;
+
+    fn resource_path(&mut self) -> &mut Path<Self::Path>;
 }
 
 pub trait ResourcePath {

actix-router/src/router.rs

@@ -1,6 +1,6 @@
 use firestorm::profile_method;
 
-use crate::{IntoPatterns, Resource, ResourceDef, ResourcePath};
+use crate::{IntoPatterns, Resource, ResourceDef};
 
 #[derive(Debug, Copy, Clone, PartialEq)]
 pub struct ResourceId(pub u16);
@@ -26,10 +26,9 @@ impl<T, U> Router<T, U> {
         }
     }
 
-    pub fn recognize<R, P>(&self, resource: &mut R) -> Option<(&T, ResourceId)>
+    pub fn recognize<R>(&self, resource: &mut R) -> Option<(&T, ResourceId)>
     where
-        R: Resource<P>,
-        P: ResourcePath,
+        R: Resource,
     {
         profile_method!(recognize);
 
@@ -42,10 +41,9 @@ impl<T, U> Router<T, U> {
         None
     }
 
-    pub fn recognize_mut<R, P>(&mut self, resource: &mut R) -> Option<(&mut T, ResourceId)>
+    pub fn recognize_mut<R>(&mut self, resource: &mut R) -> Option<(&mut T, ResourceId)>
     where
-        R: Resource<P>,
-        P: ResourcePath,
+        R: Resource,
     {
         profile_method!(recognize_mut);
 
@@ -58,11 +56,10 @@ impl<T, U> Router<T, U> {
         None
     }
 
-    pub fn recognize_fn<R, P, F>(&self, resource: &mut R, check: F) -> Option<(&T, ResourceId)>
+    pub fn recognize_fn<R, F>(&self, resource: &mut R, check: F) -> Option<(&T, ResourceId)>
     where
         F: Fn(&R, &Option<U>) -> bool,
-        R: Resource<P>,
-        P: ResourcePath,
+        R: Resource,
     {
         profile_method!(recognize_checked);
 
@@ -75,15 +72,14 @@ impl<T, U> Router<T, U> {
         None
     }
 
-    pub fn recognize_mut_fn<R, P, F>(
+    pub fn recognize_mut_fn<R, F>(
         &mut self,
         resource: &mut R,
         check: F,
     ) -> Option<(&mut T, ResourceId)>
     where
         F: Fn(&R, &Option<U>) -> bool,
-        R: Resource<P>,
-        P: ResourcePath,
+        R: Resource,
     {
         profile_method!(recognize_mut_checked);
 

src/service.rs

@@ -307,9 +307,11 @@ impl ServiceRequest {
     }
 }
 
-impl Resource<Url> for ServiceRequest {
+impl Resource for ServiceRequest {
+    type Path = Url;
+
     #[inline]
-    fn resource_path(&mut self) -> &mut Path<Url> {
+    fn resource_path(&mut self) -> &mut Path<Self::Path> {
         self.match_info_mut()
     }
 }