import { AbstractType } from "@angular/core";
export declare function injectParent<T = any>(type?: AbstractType<T>): T;
export declare function injectParent<T = any>(type: AbstractType<T>, options: {
    optional: true;
}): T | undefined;
export declare function injectParent<T = any>(type: AbstractType<T> | undefined, options: {
    optional: true;
}): T | undefined;