/// <reference types="@cloudflare/workers-types/2023-07-01" />
import { Runtime } from '../types';
/**
 * This function is used to determine the runtime (Akamai or Cloudflare)
 * @returns {'cloudflare' | 'akamai' | 'unknown'} The detected runtime environment
 * */
export declare function detectRuntime(request: Request): Runtime;
/**
 * This function checks if the selector is supported based on the runtime.
 * HTMLRewriter has limited CSS selector support that varies by runtime:
 * - Cloudflare: Does not support sibling combinators (~, +), pseudo-elements, and selected pseudo-classes
 * - Akamai: Does not support sibling combinators (~, +) or any pseudo-classes/pseudo-elements
 *
 * Results are cached for performance.
 *
 * @param selector CSS selector string used in the transform
 * @param runtime The runtime environment ('cloudflare' or 'akamai')
 * @returns true if the selector is supported on the specified runtime, false otherwise
 */
export declare function isSelectorSupported(selector: string, runtime: Runtime): boolean;