import { ObservableDescriptor } from "./descriptor";
import { ObservableAssembler } from "./assembler";
export declare function checkSourceNonNull(source: any): boolean;
export declare function nullifyOutput(): any;
export declare function checkArrayNonNull(sourceField: any): boolean;
export declare function nullifyArray(ret: any, fieldName: string): void;
export declare function popArrayUntilTargetLength(retArrayField: any, targetLength: number): void;
export declare function copyField(sourceField: any): any;
export declare let OBSERVABLE_COPIER: ObservableAssembler;
export declare function copyObservable<T>(from: T, descriptor: ObservableDescriptor<T>, to?: T): T;