import { AbstractValidator } from '../types';
import type { Validator } from '../types';
/** A `Validator` for _constants_. */
export declare class ConstantValidator<T extends string | number | boolean | bigint | null> extends AbstractValidator<T> {
    readonly constant: T;
    constructor(constant: T);
    validate(value: unknown): T;
}
/** Validate _constants_. */
export declare function constant<T extends string | number | boolean | bigint | null>(constant: T): Validator<T>;