add HttpRequest::drop_state()

src/httprequest.rs

@@ -81,6 +81,15 @@ impl<S> HttpRequest<S> {
         }
     }
 
+    /// Construct new http request with empty state.
+    pub fn drop_state(&self) -> HttpRequest {
+        HttpRequest {
+            Rc::new(()),
+            req: self.req.as_ref().map(|r| r.clone()),
+            resource: self.resource.clone(),
+        }
+    }
+
     #[inline]
     /// Construct new http request with new RouteInfo.
     pub(crate) fn with_route_info(&self, mut resource: ResourceInfo) -> HttpRequest<S> {