/// <reference types="express" />
/**
 * @license
 * Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
 * This code may only be used under the BSD style license found at
 * http://polymer.github.io/LICENSE.txt
 * The complete set of authors may be found at
 * http://polymer.github.io/AUTHORS.txt
 * The complete set of contributors may be found at
 * http://polymer.github.io/CONTRIBUTORS.txt
 * Code distributed by Google as part of the polymer project is also
 * subject to an additional IP rights grant found at
 * http://polymer.github.io/PATENTS.txt
 */
import { Request, RequestHandler, Response } from 'express';
export declare function transformResponse(transformer: ResponseTransformer): RequestHandler;
export interface ResponseTransformer {
    /**
     * Returns `true` if this transformer should be invoked.
     * Transformers should only look at headers, do not call res.write().
     */
    shouldTransform(request: Request, response: Response): boolean;
    transform(request: Request, response: Response, body: string): string;
}