01130-medium-replacekeys.ts

// ============= Test Cases =============
import type { Equal, Expect } from "./test-utils";

type NodeA = {
  type: "A";
  name: string;
  flag: number;
};

type NodeB = {
  type: "B";
  id: number;
  flag: number;
};

type NodeC = {
  type: "C";
  name: string;
  flag: number;
};

type ReplacedNodeA = {
  type: "A";
  name: number;
  flag: string;
};

type ReplacedNodeB = {
  type: "B";
  id: number;
  flag: string;
};

type ReplacedNodeC = {
  type: "C";
  name: number;
  flag: string;
};

type NoNameNodeA = {
  type: "A";
  flag: number;
  name: never;
};

type NoNameNodeC = {
  type: "C";
  flag: number;
  name: never;
};

type Nodes = NodeA | NodeB | NodeC;
type ReplacedNodes = ReplacedNodeA | ReplacedNodeB | ReplacedNodeC;
type NodesNoName = NoNameNodeA | NoNameNodeC | NodeB;

type cases = [
  Expect<
    Equal<
      ReplaceKeys<Nodes, "name" | "flag", { name: number; flag: string }>,
      ReplacedNodes
    >
  >,
  Expect<Equal<ReplaceKeys<Nodes, "name", { aa: number }>, NodesNoName>>
];

// ============= Your Code Here =============
type ReplaceKeys<U, T, Y> = {
  [P in keyof U]: P extends T ? (P extends keyof Y ? Y[P] : never) : U[P];
};