type FilterOptional<T> = Pick<T, Exclude<{
    [K in keyof T]: T extends Record<K, T[K]> ? K : never;
}[keyof T], undefined>>;
type FilterNotOptional<T> = Pick<T, Exclude<{
    [K in keyof T]: T extends Record<K, T[K]> ? never : K;
}[keyof T], undefined>>;
type PartialEither<T, K extends keyof any> = {
    [P in Exclude<keyof FilterOptional<T>, K>]-?: T[P];
} & {
    [P in Exclude<keyof FilterNotOptional<T>, K>]?: T[P];
} & {
    [P in Extract<keyof T, K>]?: undefined;
};
/**
 * 属性二选一
 * @example
 * type RawType = { a: 'a', b: 'b' }
 * type ResType = EitherOr<RawType, 'a', 'b'> // 只能存在 a 或者 b
 *
 * const a: ResType = { a: 'a' }
 * const b: ResType = { b: 'b' }
 * const c: ResType = { a: 'a', b: 'b', } // 报错
 */
type EitherOr<O extends Object, L extends string, R extends string> = (PartialEither<Pick<O, (L | R) & keyof O>, L> | PartialEither<Pick<O, (L | R) & keyof O>, R>) & Omit<O, L | R>;
export default EitherOr;