import Keyv from 'keyv';
/**
 * Cache class that implements the methods required to
 * act as a [Keyv](https://github.com/lukechilds/keyv) storage adapter.
 *
 * Stores values as files in a Stencila cache directory intended to
 * be used across applications and plugins. Removes the least
 * recently accessed files to maintain the size of the cache below a
 * defined size.
 *
 * Note that this differs from https://github.com/zaaack/keyv-file in that
 * if persists values across processes. This is important for CLI applications
 * since you do not want to create a new cache for every invocation (as
 * does `keyv-file` by default).
 */
export declare class Cache implements Keyv.Store<string> {
    /**
     * The directory for the cache files.
     */
    private dir;
    /**
     * The maximum size of the cache (MiB).
     */
    maximumSize: number;
    /**
     * The amount of time between cleanup checks (seconds).
     */
    cleanupInterval: number;
    /**
     * Create the cache.
     */
    constructor();
    /**
     * Generates a file name within the cache directory.
     *
     * Use a hash to avoid invalid characters and names
     * that are too long. Use SHA1 because faster than SHA256
     * and does not need to be secure.
     */
    private filename;
    /**
     * Set a value to be cached.
     */
    set(key: string, value: string): void;
    /**
     * Get a value from the cache.
     */
    get(key: string): string | undefined;
    /**
     * Delete a value from the cache.
     */
    delete(key: string): boolean;
    /**
     * Clear the cache completely.
     */
    clear(): void;
    /**
     * If the cache directory has gone over the maximum size remove
     * the files that are least recently accessed.
     */
    cleanup(): void;
}
export declare const cache: Cache;