import CompoundWithState from './compound_with_state';
import type { OptionalState, Traverser, Schema } from '../types';
declare class Optional<T> extends CompoundWithState<T | undefined, T | undefined, OptionalState<T | undefined, T | undefined, T>> {
    constructor(state: OptionalState<T | undefined, T | undefined, T>);
    filter(value: unknown, defaultable: false, quiet: true): boolean;
    filter(value: unknown, defaultable?: boolean, quiet?: false): T | undefined;
    filter(value: unknown, defaultable?: boolean, quiet?: boolean): T | undefined | boolean;
    test(value: unknown): value is T | undefined;
    traverse(traverser: Traverser, parent?: Schema, key?: string | number): void;
}
export default Optional;