/**
 * @license
 * Copyright 2024 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 { OnCompleteSubscription, OnErrorSubscription, OnResultSubscription, QueryRef, QueryUnsubscribe, SubscriptionOptions } from './api/query';
import { SerializedRef } from './api/Reference';
/**
 * Subscribe to a `QueryRef`
 * @param queryRefOrSerializedResult query ref or serialized result.
 * @param observer observer object to use for subscribing.
 * @returns `SubscriptionOptions`
 */
export declare function subscribe<Data, Variables>(queryRefOrSerializedResult: QueryRef<Data, Variables> | SerializedRef<Data, Variables>, observer: SubscriptionOptions<Data, Variables>): QueryUnsubscribe;
/**
 * Subscribe to a `QueryRef`
 * @param queryRefOrSerializedResult query ref or serialized result.
 * @param onNext Callback to call when result comes back.
 * @param onError Callback to call when error gets thrown.
 * @param onComplete Called when subscription completes.
 * @returns `SubscriptionOptions`
 */
export declare function subscribe<Data, Variables>(queryRefOrSerializedResult: QueryRef<Data, Variables> | SerializedRef<Data, Variables>, onNext: OnResultSubscription<Data, Variables>, onError?: OnErrorSubscription, onComplete?: OnCompleteSubscription): QueryUnsubscribe;