feat(types): 新增 DotPath

src/types/DotPath.test.ts

@@ -0,0 +1,28 @@
+import { DotPath, DotPathValue } from './DotPath'
+import { expectType } from '../dev'
+
+describe('DotPath', () => {
+  test('表现正常', () => {
+    const obj = {
+      x: {
+        y: {
+          z: [0, '1'] as const,
+          哈哈: 1,
+        },
+      },
+    }
+    // eslint-disable-next-line
+    function get<T, P extends DotPath<T>>(
+      _object: T,
+      _path: P,
+    ): DotPathValue<T, P> {
+      return 1 as any
+    }
+
+    const xyz1 = get(obj, 'x.y.z.1')
+    expectType<typeof xyz1, '1'>()
+
+    const xyz哈哈 = get(obj, 'x.y.哈哈')
+    expectType<typeof xyz哈哈, number>()
+  })
+})

src/types/DotPath.ts

@@ -0,0 +1,20 @@
+// ref: https://github.com/ahejlsberg/tsconf2020-demos/blob/master/template/main.ts#L108
+type SubKeys<T, K extends string> = K extends keyof T
+  ? `${K}.${DotPath<T[K]>}`
+  : never
+
+export type DotPath<T> = object extends T
+  ? string
+  : T extends readonly any[]
+  ? Extract<keyof T, `${number}`> | SubKeys<T, Extract<keyof T, `${number}`>>
+  : T extends object
+  ? Extract<keyof T, string> | SubKeys<T, Extract<keyof T, string>>
+  : never
+
+export type DotPathValue<T, Path extends string> = Path extends keyof T
+  ? T[Path]
+  : Path extends `${infer K}.${infer R}`
+  ? K extends keyof T
+    ? DotPathValue<T[K], R>
+    : unknown
+  : unknown

src/types/Path.test.ts

@@ -1,7 +1,7 @@
 import { expectType } from '../dev'
 import { Path, PathValue } from './Path'
 
-describe('OneOrMore', () => {
+describe('Path', () => {
   test('表现正常', () => {
     const obj = {
       x: {

src/types/index.ts

@@ -57,6 +57,7 @@ export * from './AnyAsyncFunction'
 export * from './AnyFunction'
 export * from './AnyObject'
 export * from './Defined'
+export * from './DotPath'
 export * from './FirstParameter'
 export * from './IsAny'
 export * from './IsNever'