feat: support custom merge (#711)

* feat: support deep merge

* chore: adjust

* chore: adjust

* chore: adjust

* chore: rename

* chore: rename

Author: zombieJ

src/index.ts

@@ -3,7 +3,7 @@ export { default as useMergedState } from './hooks/useMergedState';
 export { default as useControlledState } from './hooks/useControlledState';
 export { supportNodeRef, supportRef, useComposeRef } from './ref';
 export { default as get } from './utils/get';
-export { default as set, merge } from './utils/set';
+export { default as set, merge, mergeWith } from './utils/set';
 export { default as warning, noteOnce } from './warning';
 export { default as omit } from './omit';
 export { default as toArray } from './Children/toArray';

src/utils/set.ts

@@ -66,10 +66,25 @@ function createEmpty<T>(source: T) {
 
 const keys = typeof Reflect === 'undefined' ? Object.keys : Reflect.ownKeys;
 
+// ================================ Merge ================================
+export type MergeFn = (current: any, next: any) => any;
+
 /**
- * Merge objects which will create
+ * Merge multiple objects. Support custom merge logic.
+ * @param sources object sources
+ * @param config.prepareArray Customize array prepare function.
+ * It will return empty [] by default.
+ * So when match array, it will auto be override with next array in sources.
  */
-export function merge<T extends object>(...sources: T[]) {
+export function mergeWith<T extends object>(
+  sources: T[],
+  config: {
+    prepareArray?: MergeFn;
+  } = {},
+) {
+  const { prepareArray } = config;
+  const finalPrepareArray: MergeFn = prepareArray || (() => []);
+
   let clone = createEmpty(sources[0]);
 
   sources.forEach(src => {
@@ -89,7 +104,7 @@ export function merge<T extends object>(...sources: T[]) {
 
           if (isArr) {
             // Array will always be override
-            clone = set(clone, path, []);
+            clone = set(clone, path, finalPrepareArray(originValue, value));
           } else if (!originValue || typeof originValue !== 'object') {
             // Init container if not exist
             clone = set(clone, path, createEmpty(value));
@@ -109,3 +124,11 @@ export function merge<T extends object>(...sources: T[]) {
 
   return clone;
 }
+
+/**
+ * Merge multiple objects into a new single object.
+ * Arrays will be replaced by default.
+ */
+export function merge<T extends object>(...sources: T[]) {
+  return mergeWith(sources);
+}

tests/utils.test.ts

@@ -1,6 +1,6 @@
 import pickAttrs from '../src/pickAttrs';
 import get from '../src/utils/get';
-import set, { merge } from '../src/utils/set';
+import set, { mergeWith, merge } from '../src/utils/set';
 
 describe('utils', () => {
   it('get', () => {
@@ -252,6 +252,39 @@ describe('utils', () => {
           [symbol]: 1,
         });
       });
+
+      it('customMerge for custom logic', () => {
+        const src = {
+          rest: 233,
+          list: [
+            {
+              a: 1,
+            },
+          ],
+        };
+        const tgt = {
+          list: [
+            {
+              b: 1,
+            },
+          ],
+        };
+
+        const merged = mergeWith<any>([src, tgt], {
+          prepareArray: current => {
+            return [...(current || [])];
+          },
+        });
+        expect(merged).toEqual({
+          rest: 233,
+          list: [
+            {
+              a: 1,
+              b: 1,
+            },
+          ],
+        });
+      });
     });
   });