import { Cache } from '../Cache';
import { CommonCacheOptions } from '../CommonCacheOptions';
import { KeyType } from '../KeyType';
import { WrappedCache } from '../WrappedCache';
import { Loader } from './Loader';
import { LoadingCache } from './LoadingCache';
declare const DATA: unique symbol;
/**
 * Options available for a loading cache.
 */
export interface LoadingCacheOptions<K extends KeyType, V> extends CommonCacheOptions<K, V> {
    loader?: Loader<K, V> | undefined | null;
    parent: Cache<K, V>;
}
/**
 * Extension to another cache that will load items if they are not cached.
 */
export declare class DefaultLoadingCache<K extends KeyType, V> extends WrappedCache<K, V> implements LoadingCache<K, V> {
    private [DATA];
    constructor(options: LoadingCacheOptions<K, V>);
    /**
     * Get cached value or load it if not currently cached. Updates the usage
     * of the key.
     *
     * @param key -
     *   key to get
     * @param loader -
     *   optional loader to use for loading the object
     * @returns
     *   promise that resolves to the loaded value
     */
    get(key: K, loader?: Loader<K, V>): Promise<V>;
}
export {};