import MillenniumDBError from './millenniumdb-error';
export interface ResponseMessage {
    type: number;
    payload: any;
}
export interface QueryPreamble {
    workerIndex: number;
    cancellationToken: string;
}
export interface ResponseHandlerObserver {
    /** Event handler triggered when variables are available. This should be the first event triggered during a query */
    onVariables?: (variables: Array<string>, queryPreamble: QueryPreamble) => void;
    /** Event handler triggered when a record is available */
    onRecord?: (record: Array<any>) => void;
    /** Event handler triggered after a successful execution */
    onSuccess?: (summary: any) => void;
    /** Event handler triggered when an error occurs */
    onError?: (error: MillenniumDBError) => void;
}
/**
 * ResponseHandler handles the responses coming from the server
 */
declare class ResponseHandler {
    private _currentObserver;
    private readonly _pendingObservers;
    constructor();
    /**
     * Handle an incoming response
     *
     * @param message the message to handle
     */
    handle(message: ResponseMessage): void;
    /**
     * Enqueue a new observer for handling a response
     *
     * @param observer that will handle the received data
     */
    addObserver(observer: ResponseHandlerObserver): void;
    /**
     * Notify the connection error to current observer and cancel the other observers
     *
     * @param errorString the error to notify
     */
    triggerConnectionError(errorString: string): void;
    /**
     * Shift the current observer to the next one in the queue
     */
    private _nextObserver;
}
export default ResponseHandler;