import { Observable } from 'rxjs';
import { TaskInterface } from './definitions';
/**
 * Task queue is used to run async task sequentially
 *
 * Usage:
 * ```typescript
 * const taskQueue = new TaskQueue();
 *
 *  taskQueue.addExecutor(() => of('Task 1 finished').pipe(delay(100))).subscribe(console.log);
 *  taskQueue.addExecutor(() => of('Task 2 finished').pipe(delay(1))).subscribe(console.log);
 *
 * // Will output
 * Task 1 finished
 * Task 2 finished
 * ```
 */
export declare class TaskQueue {
    tasks: TaskInterface<any>[];
    private _subscription?;
    private set workingState(value);
    currentTask?: TaskInterface<any>;
    constructor();
    addExecutor(executor: () => Observable<any>): Observable<any>;
    addTask(task: TaskInterface<any>): Observable<any>;
    cancelAll(withError?: Error): void;
    private processNext;
}