feat: add patch function

Author: Thanga-Ganapathy

.changeset/little-jokes-jam.md

@@ -0,0 +1,5 @@
+---
+"@opentf/obj-diff": minor
+---
+
+Added patch function.

README.md

@@ -12,15 +12,17 @@
 
 </div>
 
-> The Fast, Accurate, JavaScript Objects Diffing Library.
+> The Fast, Accurate, JavaScript Objects Diffing & Patching Library.
 
 **[LIVE DEMO](https://obj-diff.pages.dev/)**
 
 ## Features
 
 - Deep Objects Diffing
 
-- Supports More Object Types, eg: `Map`, `Set`
+- Patching
+
+- Supports comparing more object types
 
 - TypeScript Support
 
@@ -198,6 +200,21 @@ diff(a, b);
 */
 ```
 
+## Patching
+
+You can apply the diff result onto the original object to get the modified object.
+
+```js
+import { diff, patch } from '@opentf/obj-diff';
+
+const a = {a: 1, b: 2};
+const b = {a: 2, c: 3};
+
+const out = patch(a, diff(a, b));
+
+assert.deepStrictEqual(out, b); // ok
+```
+
 ## Benchmark
 
 ```diff

apps/demo/src/App.tsx

@@ -142,7 +142,7 @@ function App() {
         <Box sx={{ display: "flex", justifyContent: "center", mt: 2 }}>
           <Card size="sm">
             <Typography level="body-lg">
-              🚀 The Fast, Accurate, JavaScript Objects Diffing Library.
+              🚀 The Fast, Accurate, JavaScript Objects Diffing & Patching Library.
             </Typography>
           </Card>
         </Box>

demo.png

@@ -12,15 +12,17 @@
 
 </div>
 
-> The Fast, Accurate, JavaScript Objects Diffing Library.
+> The Fast, Accurate, JavaScript Objects Diffing & Patching Library.
 
 **[LIVE DEMO](https://obj-diff.pages.dev/)**
 
 ## Features
 
 - Deep Objects Diffing
 
-- Supports More Object Types, eg: `Map`, `Set`
+- Patching
+
+- Supports comparing more object types
 
 - TypeScript Support
 
@@ -198,6 +200,21 @@ diff(a, b);
 */
 ```
 
+## Patching
+
+You can apply the diff result onto the original object to get the modified object.
+
+```js
+import { diff, patch } from '@opentf/obj-diff';
+
+const a = {a: 1, b: 2};
+const b = {a: 2, c: 3};
+
+const out = patch(a, diff(a, b));
+
+assert.deepStrictEqual(out, b); // ok
+```
+
 ## Benchmark
 
 ```diff

packages/obj-diff/README.md

@@ -0,0 +1,42 @@
+import { diff, patch } from "../src";
+
+describe("patch", () => {
+  test("simple objects", () => {
+    const a = { a: 1, b: 2 };
+    const b = { a: 2, c: 3 };
+    expect(patch(a, diff(a, b))).toEqual(b);
+  });
+
+  test("simple arrays", () => {
+    const a = [1, 2, 3, 4, 5];
+    const b = [1, 3, 5];
+    expect(patch(a, diff(a, b))).toEqual(b);
+  });
+
+  test("deep objects", () => {
+    const a = {
+      foo: {
+        bar: {
+          a: ["a", "b"],
+          b: 2,
+          c: ["x", "y"],
+          e: 100,
+        },
+      },
+      buzz: "world",
+    };
+
+    const b = {
+      foo: {
+        bar: {
+          a: ["a"],
+          b: 2,
+          c: ["x", "y", "z"],
+          d: "Hello, world!",
+        },
+      },
+      buzz: "fizz",
+    };
+    expect(patch(a, diff(a, b))).toEqual(b);
+  });
+});

packages/obj-diff/__tests__/patch.test.ts

@@ -1,5 +1,5 @@
 {
   "name": "@opentf/obj-diff",
-  "version": "0.1.1",
+  "version": "0.5.0",
   "exports": "./src/index.ts"
 }

packages/obj-diff/jsr.json

@@ -1,6 +1,6 @@
 {
   "name": "@opentf/obj-diff",
-  "description": "The Fast, Accurate, JavaScript Objects Diffing Library.",
+  "description": "The Fast, Accurate, JavaScript Objects Diffing & Patching Library.",
   "keywords": [
     "diff",
     "object",
@@ -61,5 +61,8 @@
     "tsup": "^8.0.2",
     "typescript": "^5.4.5",
     "typescript-eslint": "^7.7.1"
+  },
+  "dependencies": {
+    "@opentf/std": "^0.11.0"
   }
 }

packages/obj-diff/package.json

@@ -1,4 +1,5 @@
 import diff from "./diff";
+import patch from "./patch";
 import type { DiffResult } from "./types";
 
-export { diff, DiffResult };
+export { diff, patch, DiffResult };

packages/obj-diff/src/index.ts

@@ -0,0 +1,18 @@
+import { clone, set, unset } from "@opentf/std";
+import { DiffResult } from "./types";
+
+export default function patch(obj: object, patches: Array<DiffResult>) {
+  const c = clone(obj);
+
+  for (const p of patches) {
+    if (p.t === 1 || p.t === 2) {
+      set(c, p.p, p.v);
+    }
+
+    if (p.t === 0) {
+      unset(c, p.p);
+    }
+  }
+
+  return c;
+}