refactor(typescript-types): Refine KeyPaths<T,O,F> logic

packages/typescript-types/src/key-paths.ts

@@ -1,5 +1,7 @@
 import type { If } from './if.js'
 import type { IsEmptyString } from './is-empty-string.js'
+import type { IsUndefined } from './is-undefined.js'
+import type { Simplify } from './simplify.js'
 import type { Assign } from './assign.js'
 
 interface KeyPaths_Options {
@@ -20,15 +22,10 @@ type GetPrefixedKey<
 
 type PrefixIfNot<Cond, Prefix, T> = If<Cond, T, Prefix | T>
 
-type KeyPathOf<
+type KeyPathOf<Obj, Options extends Required<KeyPaths_Options>, Parent extends string, Filter = never> =
-	Obj,
+	Obj extends Record<PropertyKey, unknown>
-	Key extends PropertyKey,
+		? PrefixIfNot<Options['leavesOnly'], Parent, KeyPathsOfStringKeys<Obj, Options, Filter, Parent>>
-	Options extends Required<KeyPaths_Options>,
+		: If<IsUndefined<Obj>, never, Parent>
-	Parent extends string,
-	Filter = never
-> = Obj extends { [P in Key]: Record<PropertyKey, unknown> }
-	? PrefixIfNot<Options['leavesOnly'], Parent, KeyPathsOfStringKeys<Obj[Key], Options, Filter, Parent>>
-	: Parent
 
 type KeyPathsOfStringKeys<
 	Obj extends object,
@@ -36,13 +33,13 @@ type KeyPathsOfStringKeys<
 	Filter,
 	Parent extends string = ''
 > = {
-	[Key in keyof Obj & string]: [Filter] extends [Exclude<Filter, Obj[Key]>]
+	[Key in keyof Obj & string]: Obj[Key] extends Filter
-		? KeyPathOf<Obj, Key, Options, GetPrefixedKey<Parent, Key, Options['separator']>, Filter>
+		? never
-		: never
+		: KeyPathOf<Obj[Key], Options, GetPrefixedKey<Parent, Key, Options['separator']>, Filter>
 }[keyof Obj & string]
 
 export type KeyPaths<
 	Obj extends object,
 	Options extends KeyPaths_Options = {},
 	Filter = null | undefined
-> = KeyPathsOfStringKeys<Obj, Assign<KeyPaths_Options, KeyPaths_DefaultOptions, Options>, Filter>
+> = Simplify<KeyPathsOfStringKeys<Obj, Assign<KeyPaths_Options, KeyPaths_DefaultOptions, Options>, Filter>>

packages/typescript-types/test/key-paths.tst.ts

@@ -4,7 +4,10 @@ import { expect } from 'tstyche'
 interface ExampleObject {
 	nullvalue: null
 	simplevalue: string
-	optionalKey?: string
+	optionalKey?: {
+		nullvalue: null
+		simplevalue: string
+	}
 	unknownKey: unknown
 	neverKey: never
 	config: {
@@ -13,27 +16,36 @@ interface ExampleObject {
 	}
 }
 
-expect<KeyPaths<ExampleObject>>().type.toBe<'simplevalue' | 'config.simplevalue'>()
+expect<KeyPaths<ExampleObject>>().type.toBe<
-expect<KeyPaths<ExampleObject, {}, any>>().type.toBeAssignableTo<
+	'simplevalue' | 'optionalKey.simplevalue' | 'unknownKey' | 'config.simplevalue'
-	'nullvalue' | 'simplevalue' | 'optionalKey' | 'config.nullvalue' | 'config.simplevalue'
->()
-expect<KeyPaths<ExampleObject, {}, unknown>>().type.toBeAssignableTo<
-	'nullvalue' | 'simplevalue' | 'optionalKey' | 'config.nullvalue' | 'config.simplevalue'
 >()
+expect<KeyPaths<ExampleObject, {}, any>>().type.toBeAssignableTo<never>()
+expect<KeyPaths<ExampleObject, {}, unknown>>().type.toBeAssignableTo<never>()
 expect<KeyPaths<ExampleObject, {}, never>>().type.toBe<
-	'nullvalue' | 'simplevalue' | 'optionalKey' | 'unknownKey' | 'config.nullvalue' | 'config.simplevalue'
+	| 'nullvalue'
+	| 'simplevalue'
+	| 'optionalKey.nullvalue'
+	| 'optionalKey.simplevalue'
+	| 'unknownKey'
+	| 'config.nullvalue'
+	| 'config.simplevalue'
+>()
+expect<KeyPaths<ExampleObject, {}, null>>().type.toBe<
+	'simplevalue' | 'optionalKey.simplevalue' | 'unknownKey' | 'config.simplevalue'
+>()
+expect<KeyPaths<ExampleObject, {}, string>>().type.toBe<
+	'nullvalue' | 'optionalKey.nullvalue' | 'unknownKey' | 'config.nullvalue'
+>()
+expect<KeyPaths<ExampleObject, { separator: '-' }>>().type.toBe<
+	'simplevalue' | 'optionalKey-simplevalue' | 'unknownKey' | 'config-simplevalue'
 >()
-expect<KeyPaths<ExampleObject, {}, null>>().type.toBe<'simplevalue' | 'optionalKey' | 'config.simplevalue'>()
-expect<KeyPaths<ExampleObject, {}, string>>().type.toBe<'nullvalue' | 'config.nullvalue'>()
-
-expect<KeyPaths<ExampleObject, { separator: '-' }>>().type.toBe<'simplevalue' | 'config-simplevalue'>()
 expect<KeyPaths<ExampleObject, { leavesOnly: false }>>().type.toBe<
-	'simplevalue' | 'config' | 'neverKey' | 'config.simplevalue'
+	'simplevalue' | 'optionalKey' | 'optionalKey.simplevalue' | 'unknownKey' | 'config' | 'config.simplevalue'
 >()
 
-expect<KeyPaths<any, {}, string>>().type.toBeAssignableTo<never>()
 expect<KeyPaths<any, {}, any>>().type.toBeAssignableTo<never>()
 expect<KeyPaths<never, {}, any>>().type.toBeAssignableTo<never>()
 expect<KeyPaths<never, {}, never>>().type.toBeAssignableTo<never>()
 
 expect<KeyPaths<any, {}, never>>().type.toBe<unknown>()
+expect<KeyPaths<any, {}, string>>().type.toBeAssignableTo<unknown>()