[compiler][playground] (2/N) Config override panel (facebook#34344)

<!--
  Thanks for submitting a pull request!
We appreciate you spending the time to work on these changes. Please
provide enough information so that others can review your pull request.
The three fields below are mandatory.

Before submitting a pull request, please make sure the following is
done:

1. Fork [the repository](https://github.com/facebook/react) and create
your branch from `main`.
  2. Run `yarn` in the repository root.
3. If you've fixed a bug or added code that should be tested, add tests!
4. Ensure the test suite passes (`yarn test`). Tip: `yarn test --watch
TestName` is helpful in development.
5. Run `yarn test --prod` to test in the production environment. It
supports the same options as `yarn test`.
6. If you need a debugger, run `yarn test --debug --watch TestName`,
open `chrome://inspect`, and press "Inspect".
7. Format your code with
[prettier](https://github.com/prettier/prettier) (`yarn prettier`).
8. Make sure your code lints (`yarn lint`). Tip: `yarn linc` to only
check changed files.
  9. Run the [Flow](https://flowtype.org/) type checks (`yarn flow`).
  10. If you haven't already, complete the CLA.

Learn more about contributing:
https://reactjs.org/docs/how-to-contribute.html
-->

## Summary

Part 2 of adding a "Config Override" panel to the React compiler
playground. Added sync from the config editor (still only accessible
with the "showConfig" param) to the main source code editor. Adding a
valid config to the editor will add/replace the `@OVERRIDE` pragma above
the source code. Additionally refactored the old implementation to
remove `useEffect`s and unnecessary renders.

Realized upon testing that the user experience is quite jarring,
planning to add a `sync` button in the next PR to fix this.

## How did you test this change?

<!--
Demonstrate the code is solid. Example: The exact commands you ran and
their output, screenshots / videos if the pull request changes the user
interface.
How exactly did you verify that your PR solves the issue you wanted to
solve?
  If you leave this empty, your PR will very likely be closed.
-->



https://github.com/user-attachments/assets/a71b1b5f-0539-4c00-8d5c-22426f0280f9

Author: EugeneChoi4

compiler/apps/playground/components/Editor/ConfigEditor.tsx

@@ -6,52 +6,51 @@
  */
 
 import MonacoEditor, {loader, type Monaco} from '@monaco-editor/react';
-import {parseConfigPragmaAsString} from 'babel-plugin-react-compiler';
 import type {editor} from 'monaco-editor';
 import * as monaco from 'monaco-editor';
-import parserBabel from 'prettier/plugins/babel';
-import * as prettierPluginEstree from 'prettier/plugins/estree';
-import * as prettier from 'prettier/standalone';
-import {useState, useEffect} from 'react';
+import {useState} from 'react';
 import {Resizable} from 're-resizable';
-import {useStore} from '../StoreContext';
+import {useStore, useStoreDispatch} from '../StoreContext';
 import {monacoOptions} from './monacoOptions';
+import {
+  generateOverridePragmaFromConfig,
+  updateSourceWithOverridePragma,
+} from '../../lib/configUtils';
 
 loader.config({monaco});
 
 export default function ConfigEditor(): JSX.Element {
   const [, setMonaco] = useState<Monaco | null>(null);
   const store = useStore();
+  const dispatchStore = useStoreDispatch();
 
-  // Parse string-based override config from pragma comment and format it
-  const [configJavaScript, setConfigJavaScript] = useState('');
+  const handleChange: (value: string | undefined) => void = async value => {
+    if (value === undefined) return;
 
-  useEffect(() => {
-    const pragma = store.source.substring(0, store.source.indexOf('\n'));
-    const configString = `(${parseConfigPragmaAsString(pragma)})`;
+    try {
+      const newPragma = await generateOverridePragmaFromConfig(value);
+      const updatedSource = updateSourceWithOverridePragma(
+        store.source,
+        newPragma,
+      );
 
-    prettier
-      .format(configString, {
-        semi: true,
-        parser: 'babel-ts',
-        plugins: [parserBabel, prettierPluginEstree],
-      })
-      .then(formatted => {
-        setConfigJavaScript(formatted);
-      })
-      .catch(error => {
-        console.error('Error formatting config:', error);
-        setConfigJavaScript('({})'); // Return empty object if not valid for now
-        //TODO: Add validation and error handling for config
+      // Update the store with both the new config and updated source
+      dispatchStore({
+        type: 'updateFile',
+        payload: {
+          source: updatedSource,
+          config: value,
+        },
       });
-    console.log('Config:', configString);
-  }, [store.source]);
-
-  const handleChange: (value: string | undefined) => void = value => {
-    if (!value) return;
-
-    // TODO: Implement sync logic to update pragma comments in the source
-    console.log('Config changed:', value);
+    } catch (_) {
+      dispatchStore({
+        type: 'updateFile',
+        payload: {
+          source: store.source,
+          config: value,
+        },
+      });
+    }
   };
 
   const handleMount: (
@@ -81,12 +80,11 @@ export default function ConfigEditor(): JSX.Element {
         <MonacoEditor
           path={'config.js'}
           language={'javascript'}
-          value={configJavaScript}
+          value={store.config}
           onMount={handleMount}
           onChange={handleChange}
           options={{
             ...monacoOptions,
-            readOnly: true,
             lineNumbers: 'off',
             folding: false,
             renderLineHighlight: 'none',

compiler/apps/playground/components/Editor/EditorImpl.tsx

@@ -48,6 +48,7 @@ import {
 import {transformFromAstSync} from '@babel/core';
 import {LoggerEvent} from 'babel-plugin-react-compiler/dist/Entrypoint';
 import {useSearchParams} from 'next/navigation';
+import {parseAndFormatConfig} from '../../lib/configUtils';
 
 function parseInput(
   input: string,
@@ -315,9 +316,17 @@ export default function Editor(): JSX.Element {
       });
       mountStore = defaultStore;
     }
-    dispatchStore({
-      type: 'setStore',
-      payload: {store: mountStore},
+
+    parseAndFormatConfig(mountStore.source).then(config => {
+      dispatchStore({
+        type: 'setStore',
+        payload: {
+          store: {
+            ...mountStore,
+            config,
+          },
+        },
+      });
     });
   });
 

compiler/apps/playground/components/Editor/Input.tsx

@@ -17,6 +17,7 @@ import {useStore, useStoreDispatch} from '../StoreContext';
 import {monacoOptions} from './monacoOptions';
 // @ts-expect-error TODO: Make TS recognize .d.ts files, in addition to loading them with webpack.
 import React$Types from '../../node_modules/@types/react/index.d.ts';
+import {parseAndFormatConfig} from '../../lib/configUtils.ts';
 
 loader.config({monaco});
 
@@ -79,13 +80,17 @@ export default function Input({errors, language}: Props): JSX.Element {
     });
   }, [monaco, language]);
 
-  const handleChange: (value: string | undefined) => void = value => {
+  const handleChange: (value: string | undefined) => void = async value => {
     if (!value) return;
 
+    // Parse and format the config
+    const config = await parseAndFormatConfig(value);
+
     dispatchStore({
       type: 'updateFile',
       payload: {
         source: value,
+        config,
       },
     });
   };

compiler/apps/playground/components/StoreContext.tsx

@@ -56,6 +56,7 @@ type ReducerAction =
       type: 'updateFile';
       payload: {
         source: string;
+        config?: string;
       };
     };
 
@@ -66,10 +67,11 @@ function storeReducer(store: Store, action: ReducerAction): Store {
       return newStore;
     }
     case 'updateFile': {
-      const {source} = action.payload;
+      const {source, config} = action.payload;
       const newStore = {
         ...store,
         source,
+        config,
       };
       return newStore;
     }

compiler/apps/playground/lib/configUtils.ts

@@ -0,0 +1,87 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import parserBabel from 'prettier/plugins/babel';
+import prettierPluginEstree from 'prettier/plugins/estree';
+import * as prettier from 'prettier/standalone';
+import {parseConfigPragmaAsString} from '../../../packages/babel-plugin-react-compiler/src/Utils/TestUtils';
+
+/**
+ * Parse config from pragma and format it with prettier
+ */
+export async function parseAndFormatConfig(source: string): Promise<string> {
+  const pragma = source.substring(0, source.indexOf('\n'));
+  let configString = parseConfigPragmaAsString(pragma);
+  if (configString !== '') {
+    configString = `(${configString})`;
+  }
+
+  try {
+    const formatted = await prettier.format(configString, {
+      semi: true,
+      parser: 'babel-ts',
+      plugins: [parserBabel, prettierPluginEstree],
+    });
+    return formatted;
+  } catch (error) {
+    console.error('Error formatting config:', error);
+    return ''; // Return empty string if not valid for now
+  }
+}
+
+function extractCurlyBracesContent(input: string): string {
+  const startIndex = input.indexOf('{');
+  const endIndex = input.lastIndexOf('}');
+  if (startIndex === -1 || endIndex === -1 || endIndex <= startIndex) {
+    throw new Error('No outer curly braces found in input');
+  }
+  return input.slice(startIndex, endIndex + 1);
+}
+
+function cleanContent(content: string): string {
+  return content
+    .replace(/[\r\n]+/g, ' ')
+    .replace(/\s+/g, ' ')
+    .trim();
+}
+
+/**
+ * Generate a the override pragma comment from a formatted config object string
+ */
+export async function generateOverridePragmaFromConfig(
+  formattedConfigString: string,
+): Promise<string> {
+  const content = extractCurlyBracesContent(formattedConfigString);
+  const cleanConfig = cleanContent(content);
+
+  // Format the config to ensure it's valid
+  await prettier.format(`(${cleanConfig})`, {
+    semi: false,
+    parser: 'babel-ts',
+    plugins: [parserBabel, prettierPluginEstree],
+  });
+
+  return `// @OVERRIDE:${cleanConfig}`;
+}
+
+/**
+ * Update the override pragma comment in source code.
+ */
+export function updateSourceWithOverridePragma(
+  source: string,
+  newPragma: string,
+): string {
+  const firstLineEnd = source.indexOf('\n');
+  const firstLine = source.substring(0, firstLineEnd);
+
+  const pragmaRegex = /^\/\/\s*@/;
+  if (firstLineEnd !== -1 && pragmaRegex.test(firstLine.trim())) {
+    return newPragma + source.substring(firstLineEnd);
+  } else {
+    return newPragma + '\n' + source;
+  }
+}

compiler/apps/playground/lib/defaultStore.ts

@@ -15,8 +15,10 @@ export default function MyApp() {
 
 export const defaultStore: Store = {
   source: index,
+  config: '',
 };
 
 export const emptyStore: Store = {
   source: '',
+  config: '',
 };

compiler/apps/playground/lib/stores/store.ts

@@ -17,6 +17,7 @@ import {defaultStore} from '../defaultStore';
  */
 export interface Store {
   source: string;
+  config?: string;
 }
 export function encodeStore(store: Store): string {
   return compressToEncodedURIComponent(JSON.stringify(store));
@@ -65,5 +66,14 @@ export function initStoreFromUrlOrLocalStorage(): Store {
   const raw = decodeStore(encodedSource);
 
   invariant(isValidStore(raw), 'Invalid Store');
+
+  // Add config property if missing for backwards compatibility
+  if (!('config' in raw)) {
+    return {
+      ...raw,
+      config: '',
+    };
+  }
+
   return raw;
 }

compiler/packages/babel-plugin-react-compiler/src/Utils/TestUtils.ts

@@ -255,11 +255,16 @@ function parseConfigStringAsJS(
 
   console.log('OVERRIDE:', parsedConfig);
 
+  const environment = parseConfigPragmaEnvironmentForTest(
+    '',
+    defaults.environment ?? {},
+  );
+
   const options: Record<keyof PluginOptions, unknown> = {
     ...defaultOptions,
     panicThreshold: 'all_errors',
     compilationMode: defaults.compilationMode,
-    environment: defaults.environment ?? defaultOptions.environment,
+    environment,
   };
 
   // Apply parsed config, merging environment if it exists
@@ -269,22 +274,9 @@ function parseConfigStringAsJS(
       ...parsedConfig.environment,
     };
 
-    // Apply complex defaults for environment flags that are set to true
-    const environmentConfig: Partial<Record<keyof EnvironmentConfig, unknown>> =
-      {};
-    for (const [key, value] of Object.entries(mergedEnvironment)) {
-      if (hasOwnProperty(EnvironmentConfigSchema.shape, key)) {
-        if (value === true && key in testComplexConfigDefaults) {
-          environmentConfig[key] = testComplexConfigDefaults[key];
-        } else {
-          environmentConfig[key] = value;
-        }
-      }
-    }
-
     // Validate environment config
     const validatedEnvironment =
-      EnvironmentConfigSchema.safeParse(environmentConfig);
+      EnvironmentConfigSchema.safeParse(mergedEnvironment);
     if (!validatedEnvironment.success) {
       CompilerError.invariant(false, {
         reason: 'Invalid environment configuration in config pragma',
@@ -294,10 +286,6 @@ function parseConfigStringAsJS(
       });
     }
 
-    if (validatedEnvironment.data.enableResetCacheOnSourceFileChanges == null) {
-      validatedEnvironment.data.enableResetCacheOnSourceFileChanges = false;
-    }
-
     options.environment = validatedEnvironment.data;
   }
 
@@ -308,9 +296,7 @@ function parseConfigStringAsJS(
     }
 
     if (hasOwnProperty(defaultOptions, key)) {
-      if (value === true && key in testComplexPluginOptionDefaults) {
-        options[key] = testComplexPluginOptionDefaults[key];
-      } else if (key === 'target' && value === 'donotuse_meta_internal') {
+      if (key === 'target' && value === 'donotuse_meta_internal') {
         options[key] = {
           kind: value,
           runtimeModule: 'react',

compiler/packages/babel-plugin-react-compiler/src/index.ts

@@ -48,10 +48,7 @@ export {
   printReactiveFunction,
   printReactiveFunctionWithOutlined,
 } from './ReactiveScopes';
-export {
-  parseConfigPragmaForTests,
-  parseConfigPragmaAsString,
-} from './Utils/TestUtils';
+export {parseConfigPragmaForTests} from './Utils/TestUtils';
 declare global {
   let __DEV__: boolean | null | undefined;
 }