feat: add auto-hmr-plugin and autoHmr option

src/auto-hmr/index.ts

@@ -0,0 +1,143 @@
+import type { UnpluginOptions } from 'unplugin'
+import type { VariableDeclarator, ImportDeclaration } from 'estree'
+import type { AstNode } from 'rollup'
+
+function nameFromDeclaration(node?: VariableDeclarator) {
+  return node?.id.type === 'Identifier' ? node.id.name : ''
+}
+
+function getRouterDeclaration(nodes?: VariableDeclarator[]) {
+  return nodes?.find(
+    (x) =>
+      x.init?.type === 'CallExpression' &&
+      x.init.callee.type === 'Identifier' &&
+      x.init.callee.name === 'createRouter'
+  )
+}
+
+function getHandleHotUpdateDeclaration(node?: ImportDeclaration, modulePath?: string) {
+  return (
+    node?.type === 'ImportDeclaration' &&
+    node.source.value === modulePath &&
+    node.specifiers.some(
+      (x) =>
+        x.type === 'ImportSpecifier' &&
+        x.imported.type === 'Identifier' &&
+        x.imported.name === 'handleHotUpdate'
+    )
+  )
+}
+
+function hasHandleHotUpdateCall(ast: AstNode) {
+  function traverse(node: any) {
+    if (!node) return false;
+
+    if (
+      node.type === 'CallExpression' &&
+      node.callee.type === 'Identifier' &&
+      node.callee.name === 'handleHotUpdate'
+    ) {
+      return true;
+    }
+
+    // e.g.: autoRouter.handleHotUpdate()
+    if (
+      node.type === 'CallExpression' &&
+      node.callee.type === 'MemberExpression' &&
+      node.callee.property.type === 'Identifier' &&
+      node.callee.property.name === 'handleHotUpdate'
+    ) {
+      return true;
+    }
+
+    if (typeof node !== 'object') return false;
+
+    for (const key in node) {
+      if (key === 'type' || key === 'loc' || key === 'range') continue;
+
+      const child = node[key];
+      if (Array.isArray(child)) {
+        for (const item of child) {
+          if (traverse(item)) return true;
+        }
+      } else if (typeof child === 'object' && child !== null) {
+        if (traverse(child)) return true;
+      }
+    }
+
+    return false;
+  }
+
+  return traverse(ast);
+}
+
+interface AutoHmrPluginOptions {
+  modulePath: string
+}
+
+export function createAutoHmrPlugin({ modulePath }: AutoHmrPluginOptions): UnpluginOptions {
+  return {
+    name: 'unplugin-vue-router-auto-hmr',
+    enforce: 'post',
+
+    transform(code, id) {
+      if (id.startsWith('\x00')) return
+
+      // If you don't use automatically generated routes,
+      // maybe it will be meaningless to deal with hmr?
+      if (!code.includes('createRouter(') && !code.includes(modulePath)) {
+        return
+      }
+
+      const ast = this.parse(code)
+
+      let isImported = false
+      let routerName: string | undefined
+      let routerDeclaration: VariableDeclarator | undefined
+
+      // @ts-expect-error
+      for (const node of ast.body) {
+        if (
+          node.type === 'ExportNamedDeclaration' ||
+          node.type === 'VariableDeclaration'
+        ) {
+          if (!routerName) {
+            routerDeclaration = getRouterDeclaration(node.type === 'VariableDeclaration'
+              ? node.declarations
+              : node.declaration?.type === 'VariableDeclaration'
+                ? node.declaration?.declarations
+                : undefined)
+
+            routerName = nameFromDeclaration(routerDeclaration)
+          }
+        } else if (node.type === 'ImportDeclaration') {
+          isImported ||= getHandleHotUpdateDeclaration(node, modulePath)
+        }
+      }
+
+      if (routerName) {
+        const isCalledHandleHotUpdate = hasHandleHotUpdateCall(ast)
+
+        const handleHotUpdateCode = [code]
+
+        // add import if not imported
+        if (!isImported) {
+          handleHotUpdateCode.unshift(
+            `import { handleHotUpdate } from '${modulePath}'`
+          )
+        }
+
+        // add handleHotUpdate call if not called
+        if (!isCalledHandleHotUpdate) {
+          handleHotUpdateCode.push(`handleHotUpdate(${routerName})`)
+        }
+
+        return {
+          code: handleHotUpdateCode.join('\n')
+        }
+      }
+
+      return
+    }
+  }
+}

src/index.ts

@@ -21,6 +21,7 @@ import { join } from 'pathe'
 import { appendExtensionListToPattern } from './core/utils'
 import { MACRO_DEFINE_PAGE_QUERY } from './core/definePage'
 import { createAutoExportPlugin } from './data-loaders/auto-exports'
+import { createAutoHmrPlugin } from './auto-hmr'
 
 export type * from './types'
 
@@ -202,6 +203,14 @@ export default createUnplugin<Options | undefined>((opt = {}, _meta) => {
     )
   }
 
+  if (options.autoHmr) {
+    plugins.push(
+      createAutoHmrPlugin({
+        modulePath: MODULE_ROUTES_PATH,
+      })
+    )
+  }
+
   return plugins
 })
 

src/options.ts

@@ -213,6 +213,12 @@ export interface Options {
    */
   watch?: boolean
 
+  /**
+   * Whether to enable auto HMR for Vue Router.
+   * @default `false`
+   */
+  autoHmr?: boolean
+
   /**
    * Experimental options. **Warning**: these can change or be removed at any time, even it patch releases. Keep an eye
    * on the Changelog.