import { StorageService } from './storage-service';
/**
 * In memory implementation of the storage service.
 *
 * @public
 */
export declare class InMemoryStorageService implements StorageService {
    protected storage: Record<string, any>;
    /**
     * Adds a new item in the storage.
     *
     * @param key - The key of the item.
     * @param item - The item to save.
     *
     * @public
     */
    setItem(key: string, item: any): void;
    /**
     * Retrieves an item by its key.
     *
     * @param key - The key of the item.
     * @returns The founded item or null.
     *
     * @public
     */
    getItem<Item = any>(key: string): Item | null;
    /**
     * Removes an item by its key.
     *
     * @param key - The key of the item.
     * @returns The removed item or null.
     *
     * @public
     */
    removeItem<Item = any>(key: string): Item | null;
    /**
     * Clears the storage..
     *
     * @returns The number of removed items.
     *
     * @public
     */
    clear(): number;
}