import type { CustomOptions, CustomValidate } from "../custom";
export declare const FOUR_PART_VERSION_PATTERN: RegExp;
export type FourPartVersion = `${number}.${number}.${number}`;
/**
 * Determines whether the input is a four-part version number.
 *
 * @param input The input to check.
 * @returns `true` if the input is a four-part version number, or `false` otherwise.
 */
export declare function isFourPartVersion(input: unknown, validate?: CustomValidate<FourPartVersion>): input is FourPartVersion;
export type FourPartVersionOptions = Omit<CustomOptions<FourPartVersion>, "typecheck">;
/**
 * Verifies that the input is a four-part version, and returns it.
 *
 * @param input The value to check.
 * @param fallback The value to return if the input is not a four-part version. Default is `null`.
 * @returns The four-part version value of the input, or the fallback if the input is not a four-part version.
 */
export declare function fourPartVersion(input: unknown, fallback: FourPartVersion, options?: FourPartVersionOptions): FourPartVersion;
export declare function fourPartVersion(input: unknown, fallback?: FourPartVersion | null | undefined, options?: FourPartVersionOptions): FourPartVersion | null;