Clean up middleware; solidify support for route handler classes

lib/src/http/Middleware.ts

@@ -1,4 +1,6 @@
 import AppClass from '../lifecycle/AppClass.ts'
+import {Request} from './Request.ts'
+import {RouteHandlerReturnValue} from '../unit/Routing.ts'
 
 /**
  * Base class for HTTP middleware.
@@ -6,4 +8,13 @@ import AppClass from '../lifecycle/AppClass.ts'
  */
 export default class Middleware extends AppClass {
 
+    /**
+     * Handle the incoming request and apply this middleware.
+     * @param {Request} request
+     * @return RouteHandlerReturnValue
+     */
+    public handleRequest(request: Request): RouteHandlerReturnValue {
+        return
+    }
+
 }

lib/src/http/kernel/module/ApplyRouteHandlers.ts

@@ -6,6 +6,7 @@ import {Request} from '../../Request.ts'
 import ResponseFactory from '../../response/ResponseFactory.ts'
 import {http, error} from '../../response/helpers.ts'
 import {HTTPStatus} from '../../../const/http.ts'
+import {isRouteHandlerClass} from "../../../unit/Routing.ts";
 
 /**
  * HTTP kernel module to apply route handlers to the incoming request.
@@ -47,7 +48,13 @@ export default class ApplyRouteHandlers extends Module {
         let current_request: Request = request
         for ( const handler of request.route.handlers ) {
             try {
-                const result = await handler(current_request)
+                let result
+                if ( isRouteHandlerClass(handler) ) {
+                    result = await handler.handleRequest(current_request)
+                } else {
+                    result = await handler(current_request)
+                }
+
                 if ( result instanceof Request ) {
                     // If we got a request instance back, use that for further handlers
                     current_request = result