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