import type { CustomOptions, CustomValidate } from "../custom/index.ts";
export declare const REGEX_SEMVER: RegExp;
export type SemVer = `${number}.${number}.${number}${`-${string}` | ""}${`+${string}` | ""}`;
/**
 * Determines whether the input is a semantic version number.
 *
 * @param input The input to check.
 * @param validate Additional validation to run against the input if it is a semantic version number. Default is `undefined`.
 * @returns `true` if the input is a semantic version number, or `false` otherwise.
 */
export declare function isSemVer(input: unknown, validate?: CustomValidate<SemVer>): input is SemVer;
export type SemVerOptions = Omit<CustomOptions<SemVer>, "typecheck">;
/**
 * Verifies that the input is a semantic version, and returns it.
 *
 * @param input The value to check.
 * @param fallback The value to return if the input is not a semantic version. Default is `null`.
 * @returns The semantic version value of the input, or the fallback if the input is not a semantic version.
 */
export declare function semver(input: unknown, fallback: SemVer, options?: SemVerOptions): SemVer;
export declare function semver(input: unknown, fallback?: SemVer | null | undefined, options?: SemVerOptions): SemVer | null;