feat(typescript-types): Fully rewrite KeyPaths<T,O,F>

packages/typescript-types/README.md

@@ -46,13 +46,13 @@ The types included in this library are categorized by their purpose.
 
 | Type                       | Description                                                                                                                                                                |
 | -------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| [`KeyPaths<T, F, O>`][]    | A union of all keypaths of `T` where the value does not extend `F`. Separator can be set via `O['separator']`.                                                             |
+| [`KeyPaths<T, O, F>`][]    | A union of all keypaths of `T` where the value does not extend `F`. Separator can be set via `O['separator']`.                                                             |
 | [`OptionalKeysOf<T>`][]    | A union of all keys of `T` that are marked as optional. If `T` is a union, a union of the optional keys of all union members of `T` is returned[^optional-keys-of_remark]. |
 | [`PickAssignable<T, K>`][] | Return a mapped type with all keys of `T` that extend `K`. If no key does extend `K` an empty type is returned.                                                            |
 
 [^optional-keys-of_remark]: If `T` is `any`, it returns a union of string and number 'string | number'.
 
-[`KeyPaths<T, F, O>`]: src/key-paths.ts
+[`KeyPaths<T, O, F>`]: src/key-paths.ts
 [`OptionalKeysOf<T>`]: src/optional-keys-of.ts
 [`PickAssignable<T, K>`]: src/pick-assignable.ts
 

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

@@ -22,28 +22,27 @@ type PrefixIfNot<Cond, Prefix, T> = If<Cond, T, Prefix | T>
 
 type KeyPathOf<
 	Obj,
+	Key extends PropertyKey,
 	Options extends Required<KeyPaths_Options>,
 	Parent extends string,
 	Filter = never
-> = Obj extends object
-	? PrefixIfNot<Options['leavesOnly'], Parent, KeyPathsOfStringKeys<Obj, Options, Filter, Parent>>
+> = Obj extends { [P in Key]: Record<PropertyKey, unknown> }
+	? PrefixIfNot<Options['leavesOnly'], Parent, KeyPathsOfStringKeys<Obj[Key], Options, Filter, Parent>>
 	: Parent
 
-type DoesNotMatchFilter<T, Filter> = T extends Filter ? false : true
-
 type KeyPathsOfStringKeys<
 	Obj extends object,
 	Options extends Required<KeyPaths_Options>,
-	Filter = never,
+	Filter,
 	Parent extends string = ''
 > = {
-	[Key in keyof Obj & string]: DoesNotMatchFilter<Obj[Key], Filter> extends true
-		? KeyPathOf<Obj[Key], Options, GetPrefixedKey<Parent, Key, Options['separator']>, Filter>
+	[Key in keyof Obj & string]: [Filter] extends [Exclude<Filter, Obj[Key]>]
+		? KeyPathOf<Obj, Key, Options, GetPrefixedKey<Parent, Key, Options['separator']>, Filter>
 		: never
 }[keyof Obj & string]
 
 export type KeyPaths<
 	Obj extends object,
-	Filter = null | undefined | never,
-	Options extends KeyPaths_Options = {}
+	Options extends KeyPaths_Options = {},
+	Filter = null | undefined
 > = KeyPathsOfStringKeys<Obj, Assign<KeyPaths_Options, KeyPaths_DefaultOptions, Options>, Filter>

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

@@ -5,6 +5,8 @@ interface ExampleObject {
 	nullvalue: null
 	simplevalue: string
 	optionalKey?: string
+	unknownKey: unknown
+	neverKey: never
 	config: {
 		nullvalue: null
 		simplevalue: string
@@ -12,23 +14,26 @@ interface ExampleObject {
 }
 
 expect<KeyPaths<ExampleObject>>().type.toBe<'simplevalue' | 'config.simplevalue'>()
-expect<KeyPaths<ExampleObject, never>>().type.toBe<
+expect<KeyPaths<ExampleObject, {}, any>>().type.toBeAssignableTo<
 	'nullvalue' | 'simplevalue' | 'optionalKey' | 'config.nullvalue' | 'config.simplevalue'
 >()
-expect<KeyPaths<ExampleObject, null>>().type.toBe<'simplevalue' | 'optionalKey' | 'config.simplevalue'>()
-expect<KeyPaths<ExampleObject, string>>().type.toBe<'nullvalue' | 'config.nullvalue'>()
-
-expect<KeyPaths<ExampleObject, null, { separator: '-' }>>().type.toBe<
-	'simplevalue' | 'optionalKey' | 'config-simplevalue'
+expect<KeyPaths<ExampleObject, {}, unknown>>().type.toBeAssignableTo<
+	'nullvalue' | 'simplevalue' | 'optionalKey' | 'config.nullvalue' | 'config.simplevalue'
 >()
-expect<KeyPaths<ExampleObject, null, { leavesOnly: false }>>().type.toBe<
-	'simplevalue' | 'optionalKey' | 'config' | 'config.simplevalue'
+expect<KeyPaths<ExampleObject, {}, never>>().type.toBe<
+	'nullvalue' | 'simplevalue' | 'optionalKey' | 'unknownKey' | 'config.nullvalue' | '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'
 >()
 
-expect<KeyPaths<any, string>>().type.toBeAssignableTo<never>()
-expect<KeyPaths<any, never>>().type.toBeAssignableTo<never>()
-expect<KeyPaths<ExampleObject, any>>().type.toBeAssignableTo<never>()
-expect<KeyPaths<ExampleObject, unknown>>().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, {}, 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>()