869 - DistributeUnions

[goddnsgit]

// your answers
// 把前面几位的代码翻看了几十遍后模仿着写了一边
// Merze { } & { } => {...} 
// UnionToIntersection { } | { } => { } & { } 
// DistObj { ... , ... } => { _temp:{} } | { _temp:{} } => { _temp:{} } & { _temp:{} } => {} & {}
// ----------------------------------------------------------------------------
type Merze<T> = T extends Function ? T : { [K in keyof T]: T[K] };
// ----------------------------------------------------------------------------
type UnionToIntersection<U>
    = (U extends any ? (k: U) => void : never) extends (k: infer I) => void ? I : never;
// ----------------------------------------------------------------------------
type ValueExt<K, V> = V extends V ? { [_ in K & string]: V } : never
// ----------------------------------------------------------------------------
type DistObj<T, K extends keyof T = keyof T> = Merze<
    UnionToIntersection<
        K extends K ? { _temp: ValueExt<K, DistributeUnions<T[K]>> } : never
    > extends { _temp: infer O } ? O : {}>
// ----------------------------------------------------------------------------
type ArrExt<A extends any[], U> = A extends A ? U extends U ? [U, ...A] : never : never
// ----------------------------------------------------------------------------
type DistArr<T> = T extends [infer U, ... infer L] ? ArrExt<DistArr<L>, DistributeUnions<U>> : []
// ----------------------------------------------------------------------------
type DistributeUnions<T>
    = T extends readonly any[]
    ? DistArr<T>
    : T extends Function
    ? T // 这个似乎还得完善一下。。。
    : T extends { [_: string]: any }
    ? DistObj<T>
    : T
// ----------------------------------------------------------------------------