import { AddHtmlHeadElementType } from './html-head-types.model';
import * as i0 from "@angular/core";
export declare class HtmlHeadService {
    private readonly _document;
    private readonly _knownElements;
    addElement(element: AddHtmlHeadElementType): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<HtmlHeadService, never>;
    static ɵprov: i0.ɵɵInjectableDeclaration<HtmlHeadService>;
}