fix: independent ref state option (CT-000)

Author: DecathectZero

src/index.ts

@@ -7,18 +7,24 @@ type ReducerMap<T extends Record<string, any>, A> = {
 type ReducerMapState<T> = T extends ReducerMap<infer R, any> ? R : never;
 type ReducerMapAction<T> = T extends ReducerMap<any, infer R> ? R : never;
 
+interface CompositeReducerOptions {
+  independent?: boolean;
+}
+
 const compositeReducer =
   <S extends Record<string, any>, A extends Record<string, any>, M extends ReducerMap<Record<string, any>, any>>(
     rootReducer: RootReducer<S, A>,
-    reducers: M
+    reducers: M,
+    options: CompositeReducerOptions = {}
   ): RootReducer<S & ReducerMapState<M>, A | ReducerMapAction<M>> =>
   (state, action) =>
     Object.keys(reducers).reduce((acc, key) => {
-      if (acc) {
-        const subState = reducers[key]!(acc[key], action as ReducerMapAction<M>);
-        if (subState !== acc[key]) {
+      const refState = options.independent ? state : acc;
+      if (refState) {
+        const subState = reducers[key]!(refState[key], action as ReducerMapAction<M>);
+        if (subState !== refState[key]) {
           return {
-            ...acc,
+            ...refState,
             [key]: subState,
           };
         }