import { BusEvent, EventBus } from './eventBus.js';
import { Logger } from './logging.js';
export interface StateEvent extends BusEvent {
    data: {
        old: object;
        new: object;
    };
}
export declare type StateListener = (StateEvent: any) => any;
interface Tools {
    logger: Logger;
    bus: EventBus;
}
export declare class SharedState {
    private tools;
    private frozenState;
    constructor(tools: Tools);
    cleanKey(key: string): string;
    addListener(key: string, listener: StateListener): boolean;
    removeListener(key: string, listener: StateListener): boolean;
    getState(key: string): Promise<object>;
    /**
     * Change the state associated with the given key,
     * and trigger a lw-sc: event if handler()
     * returns an object.  NOOP of handler returns null
     * or undefined.
     *
     * @param key
     * @param handler
     */
    changeState(key: string, handler: (object: any) => object | Promise<object>): Promise<object>;
    static get providerName(): string;
}
export declare function getSharedState(): Promise<SharedState>;
export {};