[improvement] rename packages dir to src (#3659)

src/locale/index.ts

@@ -0,0 +1,34 @@
+import Vue from 'vue';
+import { deepAssign } from '../utils/deep-assign';
+import defaultMessages from './lang/zh-CN';
+
+declare module 'vue' {
+  interface VueConstructor {
+    util: {
+      defineReactive(obj: object, key: string, value: any): void;
+    };
+  }
+}
+
+const proto = Vue.prototype;
+const { defineReactive } = Vue.util;
+
+defineReactive(proto, '$vantLang', 'zh-CN');
+defineReactive(proto, '$vantMessages', {
+  'zh-CN': defaultMessages
+});
+
+export default {
+  messages() {
+    return proto.$vantMessages[proto.$vantLang];
+  },
+
+  use(lang: string, messages?: object) {
+    proto.$vantLang = lang;
+    this.add({ [lang]: messages });
+  },
+
+  add(messages = {}) {
+    deepAssign(proto.$vantMessages, messages);
+  }
+};