export interface TransformFn<T> {
    (value: unknown): T;
}
export interface Transformer<T> extends TransformFn<T> {
    /**
     * @returns True if specified value is recognized as valid.
     */
    isValid(value: unknown): value is T;
}
export interface TransformerGen<T> {
    /**
     * @param optional - is result optional.
     * @returns A function, which transforms the value to the type T. If optional is `true` or omitted,
     * it skips parsing the `undefined` value and returns it.
     */
    (optional: true): Transformer<T | undefined>;
    /**
     * @param optional - is result optional.
     * @returns A function, which transforms the value to the type T. If optional is `true` or omitted,
     * it skips parsing the `undefined` value and returns it.
     */
    (optional?: boolean): Transformer<T>;
}
/**
 * Object schema definition.
 */
export type Schema<T> = {
    [K in keyof T]: TransformFn<T[K]> | [
        /**
         * Source property name.
         */
        from: string,
        /**
         * Value transformer.
         */
        transform: TransformFn<T[K]>
    ];
};