/**
 * 将对象的某个属性变为可选，如：

interface User {
  name: string;
  age: string;
  gender: string;
}

// gender 变为可选
let user: PartialKey<User, "gender"> = {
  name: "",
  age: "",
};
// age 和 gender 变为可选
let user: PartialKey<User, "age" | gender"> = {
  name: "",
};

 */
declare type PartialKey<T, U extends keyof T> = Pick<T, Exclude<keyof T, U>> & Partial<Pick<T, U>>;

/**
 * 指定属性变为必选
 */
declare type RequiredKey<T, U extends keyof T> = Pick<T, Exclude<keyof T, U>> & Required<Pick<T, U>>;

/**
 * 指定的属性为必选，其他属性都变为可选
 *
 * 如 RequiredKey<User, "name">
 * 则只有 name 是必填，age 和 gender 变为可选
 */
declare type RequiredKeyPartialOther<T, U extends keyof T> = Partial<Pick<T, Exclude<keyof T, U>>> &
  Required<Pick<T, U>>;

/**
 * 指定属性变为只读
 */
declare type ReadOnlyKey<T, U extends keyof T> = Pick<T, Exclude<keyof T, U>> & Readonly<Pick<T, U>>;

/**
 * 对象类型
 */
declare type Recordable<T extends string | number | symbol = string, K = any> = Record<T extends null | undefined ? string : T, K>;

/**
 * 可空类型
 */
declare type Nullable<T> = T | null;