fix(theme/eject): allow treeshaking manually the theme/index file

Author: SoonIter

packages/core/rslib.config.ts

@@ -3,8 +3,9 @@ import { fileURLToPath } from 'node:url';
 import { pluginReact } from '@rsbuild/plugin-react';
 import { pluginSass } from '@rsbuild/plugin-sass';
 import { pluginSvgr } from '@rsbuild/plugin-svgr';
-import { defineConfig } from '@rslib/core';
+import { defineConfig, type RsbuildPlugin } from '@rslib/core';
 import { pluginPublint } from 'rsbuild-plugin-publint';
+import { exportStarOptimizerTransform } from './src/node/theme/exportStarOptimizerTransform';
 
 const COMMON_EXTERNALS = [
   'virtual-routes',
@@ -39,6 +40,7 @@ export default defineConfig({
 
           // TODO: should add entry by new URL parser in Rspack module graph
           'node/mdx/loader': './src/node/mdx/loader.ts',
+          'node/theme/loader': './src/node/theme/loader.ts',
           'node/ssg/renderPageWorker': './src/node/ssg/renderPageWorker.ts',
         },
       },
@@ -116,6 +118,17 @@ export default defineConfig({
         pluginReact(),
         pluginSvgr({ svgrOptions: { exportType: 'default' } }),
         pluginSass(),
+        {
+          name: 'export_star_optimizer',
+          setup(api) {
+            api.transform(
+              { test: /src\/theme\/index\.ts/ },
+              ({ code, resourcePath }) => {
+                return exportStarOptimizerTransform(code, resourcePath);
+              },
+            );
+          },
+        } satisfies RsbuildPlugin,
       ],
       source: {
         define: {

packages/core/src/node/initRsbuild.ts

@@ -1,5 +1,5 @@
 import { createRequire } from 'node:module';
-import path from 'node:path';
+import path, { join } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import type {
   RsbuildConfig,
@@ -367,9 +367,17 @@ async function createInternalBuildConfig(
           .test(/\.rspress[\\/]runtime[\\/]virtual-global-styles/)
           .merge({ sideEffects: true });
 
-        chain.module.rule('rspress-theme-index').test().merge({
+        // Optimize the theme
+        const themeIndexPath = join(CUSTOM_THEME_DIR, 'index');
+        const themeIndexRule = chain.module
+          .rule('rspress-theme-index')
+          .test(themeIndexPath);
+        themeIndexRule.merge({
           sideEffects: false,
         });
+        themeIndexRule
+          .use('EXPORT_STAR_OPTIMIZE')
+          .loader(fileURLToPath(new URL('./theme/loader.js', import.meta.url)));
 
         if (isSsg || isSsgMd) {
           chain.optimization.splitChunks({});

packages/core/src/node/theme/exportStarOptimizerTransform.ts

@@ -1,6 +1,6 @@
 import { readFile } from 'node:fs/promises';
+import { dirname } from 'node:path';
 import { rspack } from '@rsbuild/core';
-import { dirname } from 'path';
 
 /**
  * Convert `export *` into named exports via regex for tree-shaking friendliness.
@@ -191,15 +191,6 @@ class ExportStarOptimizer {
 
     return code;
   }
-
-  /**
-   * Transform file content.
-   */
-  static async transformFile(filepath: string): Promise<string> {
-    const code = await readFile(filepath, 'utf-8');
-    const transformer = new ExportStarOptimizer(filepath);
-    return transformer.transform(code);
-  }
 }
 
 /**

packages/core/src/node/theme/loader.ts

@@ -0,0 +1,13 @@
+import type { Rspack } from '@rsbuild/core';
+import { exportStarOptimizerTransform } from './exportStarOptimizerTransform.js';
+
+export default async function themeIndexFileOptimizerLoader(
+  this: Rspack.LoaderContext<{}>,
+  source: string,
+) {
+  this.cacheable(true);
+  const callback = this.async();
+  const filepath = this.resourcePath;
+  const content = await exportStarOptimizerTransform(source, filepath);
+  callback(null, content);
+}