5821 - MapTypes

5821 - MapTypes

by Krzysztof "Wokay" Łokaj (@wokayme) #中等 #map #object #utils

题目

Implement MapTypes<T, R> which will transform types in object T to different types defined by type R which has the following structure

type StringToNumber = {
  mapFrom: string; // value of key which value is string
  mapTo: number; // will be transformed for number
}

Examples:

type StringToNumber = { mapFrom: string; mapTo: number;}
MapTypes<{iWillBeANumberOneDay: string}, StringToNumber> // gives { iWillBeANumberOneDay: number; }

Be aware that user can provide a union of types:

type StringToNumber = { mapFrom: string; mapTo: number;}
type StringToDate = { mapFrom: string; mapTo: Date;}
MapTypes<{iWillBeNumberOrDate: string}, StringToDate | StringToNumber> // gives { iWillBeNumberOrDate: number | Date; }

If the type doesn't exist in our map, leave it as it was:

type StringToNumber = { mapFrom: string; mapTo: number;}
MapTypes<{iWillBeANumberOneDay: string, iWillStayTheSame: Function}, StringToNumber> // // gives { iWillBeANumberOneDay: number, iWillStayTheSame: Function }

在 Github 上查看：https://tsch.js.org/5821/zh-CN

代码

/* _____________ 你的代码 _____________ */

type MapTypes<T, R extends { mapFrom: any, mapTo: any }> = {
  [K in keyof T]: T[K] extends R['mapFrom']
    ? R extends { mapFrom: T[K] }
      ? R['mapTo']
      : never
    : T[K]
}

测试用例

/* _____________ 测试用例 _____________ */
import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<MapTypes<{ stringToArray: string }, { mapFrom: string, mapTo: [] }>, { stringToArray: [] }>>,
  Expect<Equal<MapTypes<{ stringToNumber: string }, { mapFrom: string, mapTo: number }>, { stringToNumber: number }>>,
  Expect<Equal<MapTypes<{ stringToNumber: string, skipParsingMe: boolean }, { mapFrom: string, mapTo: number }>, { stringToNumber: number, skipParsingMe: boolean }>>,
  Expect<Equal<MapTypes<{ date: string }, { mapFrom: string, mapTo: Date } | { mapFrom: string, mapTo: null }>, { date: null | Date }>>,
  Expect<Equal<MapTypes<{ date: string }, { mapFrom: string, mapTo: Date | null }>, { date: null | Date }>>,
  Expect<Equal<MapTypes<{ fields: Record<string, boolean> }, { mapFrom: Record<string, boolean>, mapTo: string[] }>, { fields: string[] }>>,
  Expect<Equal<MapTypes<{ name: string }, { mapFrom: boolean, mapTo: never }>, { name: string }>>,
  Expect<Equal<MapTypes<{ name: string, date: Date }, { mapFrom: string, mapTo: boolean } | { mapFrom: Date, mapTo: string }>, { name: boolean, date: string }>>,
]

相关链接

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