feat: support offset modification (#4)

Author: zhiyuanzmj

package.json

@@ -52,7 +52,7 @@
   },
   "dependencies": {
     "@ampproject/remapping": "^2.3.0",
-    "magic-string": "^0.30.10"
+    "magic-string": "^0.30.17"
   },
   "devDependencies": {
     "@antfu/eslint-config": "^2.14.0",

pnpm-lock.yaml

@@ -44,7 +44,10 @@ export default class MagicStringStack implements MagicStringStackType {
         return parent
       },
       set: (_, p, value) => {
-        return Reflect.set(this, p, value, this)
+        if (Reflect.has(this, p))
+          return Reflect.set(this, p, value, this)
+
+        return Reflect.set(this._current, p, value)
       },
     }) as any
 
@@ -58,6 +61,7 @@ export default class MagicStringStack implements MagicStringStackType {
    */
   commit() {
     const newOne = new MagicString(this._current.toString(), this._options)
+    newOne.offset = this._current.offset
     this._current = newOne
     this._stack.unshift(newOne)
     return this

src/index.ts

@@ -111,6 +111,17 @@ it('should be chainable', () => {
     .toMatchInlineSnapshot(`"AAAA,OAAK,CAAC"`)
 })
 
+it('should support offset modification', () => {
+  const s = new MagicStringStack(' problems = 99')
+  s.offset = 1
+  s.update(0, 8, 'answer')
+  expect(s.toString()).toMatchInlineSnapshot(`" answer = 99"`)
+
+  s.commit()
+  s.update(0, 6, 'problems')
+  expect(s.toString()).toMatchInlineSnapshot(`" problems = 99"`)
+})
+
 function removeEmptyKeys(obj: any) {
   return Object.fromEntries(Object.entries(obj).filter(([_, v]) => !(v == null || (Array.isArray(v) && !v.length))))
 }