/**
 * @license
 * Copyright 2018 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 { ListenSequenceNumber } from './types';
/**
 * `SequenceNumberSyncer` defines the methods required to keep multiple instances of a
 * `ListenSequence` in sync.
 */
export interface SequenceNumberSyncer {
    writeSequenceNumber(sequenceNumber: ListenSequenceNumber): void;
    sequenceNumberHandler: ((sequenceNumber: ListenSequenceNumber) => void) | null;
}
/**
 * `ListenSequence` is a monotonic sequence. It is initialized with a minimum value to
 * exceed. All subsequent calls to next will return increasing values. If provided with a
 * `SequenceNumberSyncer`, it will additionally bump its next value when told of a new value, as
 * well as write out sequence numbers that it produces via `next()`.
 */
export declare class ListenSequence {
    private previousValue;
    static readonly INVALID: ListenSequenceNumber;
    private writeNewSequenceNumber?;
    constructor(previousValue: ListenSequenceNumber, sequenceNumberSyncer?: SequenceNumberSyncer);
    private setPreviousValue;
    next(): ListenSequenceNumber;
}