import { IExtensionAfterEventHandler, IExtensionBeforeEventHandler, IExtensionEvent } from './IExtension';
export declare class ExtensionEvent<I extends unknown[], O> implements IExtensionEvent<I, O> {
    protected beforeHandlers: IExtensionBeforeEventHandler<I, O>[];
    protected afterHandlers: IExtensionAfterEventHandler<I, O>[];
    before(handler: IExtensionBeforeEventHandler<I, O>): void;
    after(handler: IExtensionAfterEventHandler<I, O>): void;
    offAfter(handler: IExtensionAfterEventHandler<I, O>): void;
    offBefore(handler: IExtensionBeforeEventHandler<I, O>): void;
    triggerBefore(input: I, event: {
        stopPropagation: boolean;
    }): Promise<I | O>;
    triggerAfter(input: I, output: O): Promise<O>;
}