import { StringFormatType } from '../../utils/index';
import { ValueTypeValidatorBase } from './index';
export declare const VALIDATOR_FUNCTION_METADATA_KEY: unique symbol;
export declare function isFunction(errorMessage?: StringFormatType): (target: Record<string, any>, propertyKey: string | symbol, descriptor: TypedPropertyDescriptor<any>) => void;
export declare class FunctionValidator extends ValueTypeValidatorBase {
    constructor(errorMessage?: StringFormatType);
}