0.1.4 (#4)

Co-authored-by: Julien Valverdé <julien.valverde@mailo.com>
Reviewed-on: https://git.jvalver.de/Thilawyn/traitify-ts/pulls/4

src/util/extend.ts

@@ -1,25 +1,71 @@
-import { Call, ComposeLeft, Fn, Match, Tuples } from "hotscript"
 import { CommonKeys } from "."
 
 
-type ExtendReducer<Super, Self> = (
-    Pick<Self, CommonKeys<Self, Super>> extends Pick<Super, CommonKeys<Self, Super>>
-        ? Omit<Super, CommonKeys<Self, Super>> & Self
-        : never
+// type ExtendReducer<Super, Self> = (
+//     Pick<Self, CommonKeys<Self, Super>> extends Pick<Super, CommonKeys<Self, Super>>
+//         ? Omit<Super, CommonKeys<Self, Super>> & Self
+//         : never
+// )
+// interface ExtendReducerFn extends Fn {
+//     return: ExtendReducer<this["arg0"], this["arg1"]>
+// }
+// export type ExtendFn = Tuples.Reduce<ExtendReducerFn, {}>
+
+// export type ExtendableFn = ComposeLeft<[
+//     ExtendFn,
+//     Match<[
+//         Match.With<never, false>,
+//         Match.With<any, true>,
+//     ]>
+// ]>
+
+
+// TODO: use OverrideProperties from type-fest?
+export type Extend<T extends readonly object[]> = (
+    T extends [
+        infer Super,
+        infer Self,
+        ...infer Rest extends object[],
+    ]
+        ? Pick<Self, CommonKeys<Self, Super>> extends Pick<Super, CommonKeys<Self, Super>>
+            ? Extend<[
+                Omit<Super, CommonKeys<Self, Super>> & Self,
+                ...Rest,
+            ]>
+            : never
+        : T extends [infer Self]
+            ? Self
+            : {}
 )
-interface ExtendReducerFn extends Fn {
-    return: ExtendReducer<this["arg0"], this["arg1"]>
-}
 
-export type ExtendFn = Tuples.Reduce<ExtendReducerFn, {}>
-export type Extend<T extends {}[]> = Call<ExtendFn, T>
+export type Extendable<T extends readonly object[]> = (
+    T extends [
+        infer Super,
+        infer Self,
+        ...infer Rest extends object[],
+    ]
+        ? Pick<Self, CommonKeys<Self, Super>> extends Pick<Super, CommonKeys<Self, Super>>
+            ? Extendable<[
+                Omit<Super, CommonKeys<Self, Super>> & Self,
+                ...Rest,
+            ]>
+            : false
+        : true
+)
 
-
-export type ExtendableFn = ComposeLeft<[
-    ExtendFn,
-    Match<[
-        Match.With<never, false>,
-        Match.With<any, true>,
-    ]>
-]>
-export type Extendable<T extends {}[]> = Call<ExtendableFn, T>
+export type NonExtendableKeys<T extends readonly object[]> = (
+    T extends [
+        infer Super   extends object,
+        infer Self    extends object,
+        ...infer Rest extends object[],
+    ]
+        ? {[K in keyof Super & keyof Self]: Self[K] extends Super[K]
+            ? never
+            : K
+        }[keyof Super & keyof Self]
+        | NonExtendableKeys<[
+            Super & Self,
+            ...Rest,
+        ]>
+        : void
+)