import { Subject, Observable } from 'rxjs';
import { DragBackendEvent } from './drag-backend-event';
import { Unsubscribe } from './unsubscribe';
import { DragMonitor } from '../drag-monitor';
export declare abstract class DragBackend {
    protected readonly monitor: DragMonitor;
    protected readonly eventStream: Subject<DragBackendEvent<any>>;
    readonly eventStream$: Observable<DragBackendEvent>;
    abstract connectDragSource(sourceId: string, node: any): Unsubscribe;
    abstract connectDropTarget(targetId: string, node: any): Unsubscribe;
    constructor(monitor: DragMonitor);
}