import { HttpEvent, HttpHandlerFn, HttpRequest } from '@angular/common/http';
import { Observable } from 'rxjs';
/**
 * Interceptor function to handle HTTP caching for GET requests. It retrieves cached responses
 * if available and valid; otherwise, it processes the request and caches the response for future use.
 *
 * @param {HttpRequest<any>} req - The HTTP request object being intercepted.
 * @param {HttpHandlerFn} next - The next HTTP handler function in the chain to process the request.
 * @return {Observable<HttpEvent<any>>} An observable that emits the HTTP event, either from cache
 * or by invoking the next handler.
 */
export declare function httpCachingInterceptor(req: HttpRequest<any>, next: HttpHandlerFn): Observable<HttpEvent<any>>;