import type { ContentSecurityPolicyOptions } from 'helmet-csp';
import type { ServerResponse, IncomingMessage } from 'node:http';
import type { ValueOf } from '../../types.js';
/**
 * A collection of CSP keywords that are resolved to actual values
 * during an HTTP request.
 */
declare class CSPKeywords {
    #private;
    /**
     * Register a custom CSP directive keyword and resolve
     * it to a value during an HTTP request.
     */
    register(keyword: string, resolver: (_: IncomingMessage, response: ServerResponse) => string): this;
    /**
     * Resolves keywords
     */
    resolve(directiveValues: ValueOf<Exclude<ContentSecurityPolicyOptions['directives'], undefined>>): ValueOf<Exclude<ContentSecurityPolicyOptions['directives'], undefined>>;
}
declare const cspKeywords: CSPKeywords;
export { cspKeywords };