/**
 * Filters for request headers extraction
 * @packageDocumentation
 */
import { Filter } from "../filter";
/**
 * Extracts an optional header
 *
 * @param name - Header name
 *
 * @returns Optional header value
 */
export declare function optional(name: string): Filter<[string | undefined]>;
/**
 * Extracts a required header
 *
 * @param name - Header name
 *
 * @returns Header value
 */
export declare function required(name: string): Filter<[string]>;
/**
 * Checks that the request has the header with the provided name exactly matching the provided value
 *
 * @param name - Header name
 * @param value - Header value
 */
export declare function exact(name: string, value: string | undefined): Filter<[]>;