/**
 * @license
 * Copyright 2021 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.
 */
import { Observable } from 'rxjs';
import { ListenEvent, QueryChange } from './interfaces';
/**
 * Create an observable from a Database Reference or Database Query.
 * @param ref Database Reference
 * @param event Listen event type ('value', 'added', 'changed', 'removed', 'moved')
 */
export declare function fromRef(ref: import('firebase/database').Query, event: ListenEvent): Observable<QueryChange>;