import type { CustomOptions, CustomValidate } from "../custom/index.ts";
/**
 * Determines if the input is a URL.
 *
 * @param input The value to check.
 * @param validate Additional validation to run against the input if it is a URL. Default is `undefined`.
 * @returns `true` if the input is a URL, `false` otherwise.
 */
export declare function isUrl(input: unknown, validate?: CustomValidate<URL>): input is URL;
export type URLOptions = Omit<CustomOptions<URL>, "typecheck">;
/**
 * Verifies that the input is a URL, and returns it.
 * If the input is not a URL, the fallback value is returned.
 *
 * @param input The value to check.
 * @param fallback The value to return if the input is not a URL. Default is `null`.
 * @returns The URL value of the input, or the fallback if the input is not a URL.
 */
export declare function url(input: unknown, fallback: URL, options?: URLOptions): URL;
export declare function url(input: unknown, fallback?: URL | null | undefined, options?: URLOptions): URL | null;
/**
 * Converts the input into a URL.
 *
 * @param input The value to convert.
 * @param baseUrl The base URL to use when converting a relative URL. Default is `undefined`.
 * @returns The URL value of the input, or `null` if the input cannot be converted.
 */
export declare function toUrl(input: unknown, baseUrl?: string | URL): URL | null;