import { Provider, Type } from '@angular/core';
import { OperatorFunction } from 'rxjs';
export declare function noop(): void;
/**
 * Use in the `providers` of a component that implements `ControlValueAccessor` to reduce some boilerplate.
 *
 * ```ts
 * @Component({ providers: [provideValueAccessor(MyFormControl)] }
 * class MyFormControl extends BaseFormControl {
 *   // ...
 * }
 * ```
 */
export declare function provideValueAccessor(type: Type<any>): Provider;
/**
 * @usage
 * ```
 * source$.pipe(filterOutNullish())
 * ```
 */
export declare function filterOutNullish<T>(): OperatorFunction<T | null | undefined, T>;
export declare function conditionalStartWith<T>(condition: () => boolean, cb: () => T): OperatorFunction<unknown, T>;