Improve transform speed by 8.5%

Reviewed By: jeanlauliac

Differential Revision: D5443966

fbshipit-source-id: 06a151f44b7b9f8307be2ea47ce35deb3663869f

babel-preset/configs/main.js

@@ -5,55 +5,99 @@
  * This source code is licensed under the BSD-style license found in the
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @format
  */
 'use strict';
 
 var resolvePlugins = require('../lib/resolvePlugins');
 
-var base = {
-  comments: false,
-  compact: true,
-  plugins: resolvePlugins([
-    'syntax-async-functions',
+const getPreset = (src, options) => {
+  const plugins = [];
+  const isNull = src === null || src === undefined;
+  const hasClass = isNull || src.indexOf('class') !== -1;
+  const hasForOf =
+    isNull || (src.indexOf('for') !== -1 && src.indexOf('of') !== -1);
+
+  plugins.push(
     'syntax-class-properties',
     'syntax-trailing-function-commas',
     'transform-class-properties',
-    'transform-es2015-function-name',
-    'transform-es2015-arrow-functions',
     'transform-es2015-block-scoping',
-    'transform-es2015-classes',
     'transform-es2015-computed-properties',
-    'check-es2015-constants',
     'transform-es2015-destructuring',
-    ['transform-es2015-modules-commonjs', { strict: false, allowTopLevelThis: true }],
+    'transform-es2015-function-name',
+    'transform-es2015-literals',
     'transform-es2015-parameters',
     'transform-es2015-shorthand-properties',
-    'transform-es2015-spread',
-    'transform-es2015-template-literals',
-    'transform-es2015-literals',
     'transform-flow-strip-types',
-    'transform-object-assign',
-    'transform-object-rest-spread',
-    'transform-react-display-name',
     'transform-react-jsx',
     'transform-regenerator',
-    ['transform-es2015-for-of', { loose: true }],
     require('../transforms/transform-regenerator-runtime-insertion'),
-    require('../transforms/transform-symbol-member'),
-  ]),
-};
+    [
+      'transform-es2015-modules-commonjs',
+      {strict: false, allowTopLevelThis: true},
+    ],
+  );
+
+  if (isNull || src.indexOf('async') !== -1 || src.indexOf('await') !== -1) {
+    plugins.push('syntax-async-functions');
+  }
+  if (hasClass) {
+    plugins.push('transform-es2015-classes');
+  }
+  if (isNull || src.indexOf('=>') !== -1) {
+    plugins.push('transform-es2015-arrow-functions');
+  }
+  if (isNull || src.indexOf('const') !== -1) {
+    plugins.push('check-es2015-constants');
+  }
+  if (isNull || hasClass || src.indexOf('...') !== -1) {
+    plugins.push('transform-es2015-spread');
+    plugins.push('transform-object-rest-spread');
+  }
+  if (isNull || src.indexOf('`') !== -1) {
+    plugins.push('transform-es2015-template-literals');
+  }
+  if (isNull || src.indexOf('Object.assign') !== -1) {
+    plugins.push('transform-object-assign');
+  }
+  if (hasForOf) {
+    plugins.push(['transform-es2015-for-of', {loose: true}]);
+  }
+  if (hasForOf || src.indexOf('Symbol') !== -1) {
+    plugins.push(require('../transforms/transform-symbol-member'));
+  }
+  if (
+    isNull ||
+    src.indexOf('React.createClass') !== -1 ||
+    src.indexOf('createReactClass') !== -1
+  ) {
+    plugins.push('transform-react-display-name');
+  }
 
-var devTools = Object.assign({}, base);
-devTools.plugins = devTools.plugins.concat(
-  resolvePlugins(['transform-react-jsx-source'])
-);
+  if (options && options.dev) {
+    plugins.push('transform-react-jsx-source');
+  }
 
+  return {
+    comments: false,
+    compact: true,
+    plugins: resolvePlugins(plugins),
+  };
+};
 
-module.exports = function(options) {
-  var withDevTools = options.withDevTools;
-  if (withDevTools == null) {
-    var env = process.env.BABEL_ENV || process.env.NODE_ENV;
-    withDevTools = !env || env === 'development';
+const base = getPreset(null);
+const devTools = getPreset(null, {dev: true});
+
+module.exports = options => {
+  if (options.withDevTools == null) {
+    const env = process.env.BABEL_ENV || process.env.NODE_ENV;
+    if (!env || env === 'development') {
+      return devTools;
+    }
   }
-  return withDevTools ? devTools : base;
+  return base;
 };
+
+module.exports.getPreset = getPreset;