import _isBoolean from 'validator/lib/isBoolean';
import { TReferenceProps } from '../../..';
import { IStringProps, TStringValidatorResult } from '../_types';
declare type TParameters = Parameters<typeof _isBoolean>;
export interface IIsBooleanProps {
    /**
     * `options` is an object which defaults to `{ loose: false }`. If `loose` is is set to `false`, the validator will strictly match `['true', 'false', '0', '1']`. If `loose` is set to `true`, the validator will also match 'yes', 'no', and will match a valid boolean string of any case. (eg: `['true', 'True', 'TRUE']`).
     */
    options?: TParameters[1];
}
/**
 * Check if a string is a boolean.
 */
export declare const isBoolean: (props?: TReferenceProps<IIsBooleanProps> & IStringProps) => TStringValidatorResult;
export {};