feat(rest): add rest.router binding to allow customization

packages/rest/src/http-handler.ts

@@ -21,12 +21,14 @@ import {RestBindings} from './keys';
 import {RequestContext} from './request-context';
 
 export class HttpHandler {
-  protected _routes: RoutingTable = new RoutingTable();
   protected _apiDefinitions: SchemasObject;
 
   public handleRequest: (request: Request, response: Response) => Promise<void>;
 
-  constructor(protected _rootContext: Context) {
+  constructor(
+    protected _rootContext: Context,
+    protected _routes = new RoutingTable(),
+  ) {
     this.handleRequest = (req, res) => this._handleRequest(req, res);
   }
 

packages/rest/src/keys.ts

@@ -30,6 +30,7 @@ import {
 import {HttpProtocol} from '@loopback/http-server';
 import * as https from 'https';
 import {ErrorWriterOptions} from 'strong-error-handler';
+import {RestRouter} from './router';
 
 /**
  * RestServer-specific bindings
@@ -65,6 +66,12 @@ export namespace RestBindings {
    * Internal binding key for http-handler
    */
   export const HANDLER = BindingKey.create<HttpHandler>('rest.handler');
+
+  /**
+   * Internal binding key for rest router
+   */
+  export const ROUTER = BindingKey.create<RestRouter>('rest.router');
+
   /**
    * Binding key for setting and injecting Reject action's error handling
    * options.

packages/rest/src/rest.server.ts

@@ -32,6 +32,7 @@ import {
   createControllerFactoryForBinding,
   Route,
   RouteEntry,
+  RoutingTable,
 } from './router/routing-table';
 
 import {DefaultSequence, SequenceFunction, SequenceHandler} from './sequence';
@@ -281,7 +282,14 @@ export class RestServer extends Context implements Server, HttpServerLike {
     // See https://github.com/strongloop/loopback-next/issues/433
     if (this._httpHandler) return;
 
-    this._httpHandler = new HttpHandler(this);
+    const router = this.getSync(RestBindings.ROUTER, {optional: true});
+    let routingTable: RoutingTable;
+    if (router) {
+      routingTable = new RoutingTable(router);
+    } else {
+      routingTable = new RoutingTable();
+    }
+    this._httpHandler = new HttpHandler(this, routingTable);
     for (const b of this.find('controllers.*')) {
       const controllerName = b.key.replace(/^controllers\./, '');
       const ctor = b.valueConstructor;

packages/rest/test/acceptance/routing/routing.acceptance.ts

@@ -34,6 +34,7 @@ import {anOpenApiSpec, anOperationSpec} from '@loopback/openapi-spec-builder';
 import {inject, Context, BindingScope} from '@loopback/context';
 
 import {createUnexpectedHttpErrorLogger} from '../../helpers';
+import {TrieRouter} from '../../../src';
 
 /* # Feature: Routing
  * - In order to build REST APIs
@@ -701,7 +702,16 @@ describe('Routing', () => {
         .expect(200, 'hello');
     });
 
-    it('sorts routes based on their specifics', async () => {
+    it('allows pluggable router', async () => {
+      const app = new RestApplication();
+      app.bind(RestBindings.ROUTER).toClass(TrieRouter);
+      const server = await app.getServer(RestServer);
+      const handler = await server.get(RestBindings.HANDLER);
+      // tslint:disable-next-line:no-any
+      expect((handler as any)._routes._router).to.be.instanceof(TrieRouter);
+    });
+
+    it('matches routes based on their specifics', async () => {
       const app = new RestApplication();
 
       app.route(