import { Validatable } from '../types/Validatable';
import { Json } from '../types/Json';
export declare abstract class Struct implements Validatable {
    protected readonly state: any;
    constructor(state?: any);
    get isValid(): boolean;
    toJSON(): Json;
    toString(): string;
    update(_add: Json): Struct;
    protected merge(a: unknown): Json;
}
export declare function isStruct(s?: unknown): s is Struct;