/**
 * @license
 * Copyright 2017 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/**
 * Simple wrapper around a nullable UID. Mostly exists to make code more
 * readable.
 */
export declare class User {
    readonly uid: string | null;
    /** A user with a null UID. */
    static readonly UNAUTHENTICATED: User;
    static readonly GOOGLE_CREDENTIALS: User;
    static readonly FIRST_PARTY: User;
    static readonly MOCK_USER: User;
    constructor(uid: string | null);
    isAuthenticated(): boolean;
    /**
     * Returns a key representing this user, suitable for inclusion in a
     * dictionary.
     */
    toKey(): string;
    isEqual(otherUser: User): boolean;
}