import type { CustomOptions } from "../custom/index.ts";
export declare const CUID2_DEFAULT_LENGTH = 24;
export declare const CUID2_MIN_LENGTH = 2;
export declare const CUID2_MAX_LENGTH = 32;
export interface IsCuid2Options {
    length?: number;
}
export declare function getCuid2Length(input?: number | null | undefined): number;
/**
 * Determines if the input is a CUID.
 *
 * @param input The value to check.
 * @param options The options for the CUID.
 * @returns `true` if the input is a CUID, `false` otherwise.
 */
export declare function isCuid2(input: unknown, options?: IsCuid2Options): input is string;
export type Cuid2Options = Omit<CustomOptions<string>, "typecheck" | "validate"> & IsCuid2Options;
/**
 * Verifies that the input is a CUID, and returns it.
 * If the input is not a CUID, the fallback value is returned.
 *
 * @param input The value to check.
 * @param fallback The value to return if the input is not a CUID. Default is `null`.
 * @param options The options for the CUID.
 * @returns The CUID value of the input, or the fallback if the input is not a CUID.
 */
export declare function cuid2(input: unknown, fallback: string, options?: Cuid2Options): string;
export declare function cuid2(input: unknown, fallback?: string | null | undefined, options?: Cuid2Options): string | null;