Add babel bridge to switch easily between 6 and 7

Summary:
This bridge pulls in the various babel things and exports them again.

In a future update this bridge will also pull in babel 7 versions of the same thing and an env var will determine which sources to use so you can switch between using babel 6 or 7 through ENV.

Reviewed By: davidaurelio

Differential Revision: D6844862

fbshipit-source-id: 610a60eaf7bf368eddcd015e37f228651e2fd78b

packages/metro/src/Bundler/__tests__/util-test.js

@@ -12,7 +12,7 @@
 
 'use strict';
 
-const babelGenerate = require('babel-generator').default;
+const {babelGenerate} = require('../../babel-bridge');
 const {
   generateAssetCodeFileAst,
   generateRemoteAssetCodeFileAst,

packages/metro/src/Bundler/util.js

@@ -12,8 +12,8 @@
 
 'use strict';
 
-const babel = require('babel-core');
+const {babelCore: babel} = require('../babel-bridge');
-const babylon = require('babylon');
+const {babylon} = require('../babel-bridge');
 
 import type {AssetDataWithoutFiles} from '../Assets';
 import type {ModuleTransportLike} from '../shared/types.flow';

packages/metro/src/JSTransformer/worker/__tests__/constant-folding-test.js

@@ -12,9 +12,10 @@
  */
 'use strict';
 
-const babel = require('babel-core');
 const constantFolding = require('../constant-folding');
 
+const {babelCore: babel} = require('../../../babel-bridge');
+
 function parse(code) {
   return babel.transform(code, {code: false, babelrc: false, compact: true});
 }

packages/metro/src/JSTransformer/worker/__tests__/inline-test.js

@@ -13,7 +13,9 @@
 
 const inline = require('../inline');
 
-const {transform, transformFromAst} = require('babel-core');
+const {
+  babelCore: {transform, transformFromAst},
+} = require('../../../babel-bridge');
 
 const babelOptions = {
   babelrc: false,

packages/metro/src/JSTransformer/worker/constant-folding.js

@@ -12,7 +12,7 @@
 
 'use strict';
 
-const babel = require('babel-core');
+const {babelCore: babel} = require('../../babel-bridge');
 
 import type {Ast, BabelSourceMap} from 'babel-core';
 

packages/metro/src/JSTransformer/worker/index.js

@@ -15,24 +15,24 @@
 const JsFileWrapping = require('../../ModuleGraph/worker/JsFileWrapping');
 
 const assetTransformer = require('../../assetTransformer');
-const babylon = require('babylon');
 const collectDependencies = require('../../ModuleGraph/worker/collectDependencies');
 const constantFolding = require('./constant-folding');
-const generate = require('babel-generator').default;
 const inline = require('./inline');
 const minify = require('./minify');
 const optimizeDependencies = require('../../ModuleGraph/worker/optimizeDependencies');
 const path = require('path');
 
+const {babylon} = require('../../babel-bridge');
+const {babelGenerate: generate} = require('../../babel-bridge');
 const {toSegmentTuple} = require('metro-source-map');
 
-import type {LogEntry} from 'metro-core/src/Logger';
+import type {DynamicRequiresBehavior} from '../../ModuleGraph/worker/collectDependencies';
-import type {BabelSourceMap} from 'babel-core';
-import type {MetroSourceMapSegmentTuple} from 'metro-source-map';
 import type {LocalPath} from '../../node-haste/lib/toLocalPath';
 import type {ResultWithMap} from './minify';
 import type {Ast, Plugins as BabelPlugins} from 'babel-core';
-import type {DynamicRequiresBehavior} from '../../ModuleGraph/worker/collectDependencies';
+import type {BabelSourceMap} from 'babel-core';
+import type {LogEntry} from 'metro-core/src/Logger';
+import type {MetroSourceMapSegmentTuple} from 'metro-source-map';
 
 export type TransformedCode = {
   code: string,

packages/metro/src/JSTransformer/worker/inline-platform.js

@@ -12,7 +12,7 @@
 
 'use strict';
 
-const babel = require('babel-core');
+const {babelCore: babel} = require('../../babel-bridge');
 
 const t = babel.types;
 const importMap = new Map([['ReactNative', 'react-native']]);

packages/metro/src/JSTransformer/worker/inline.js

@@ -12,10 +12,11 @@
 
 'use strict';
 
-const babel = require('babel-core');
 const inlinePlatform = require('./inline-platform');
 const invariant = require('fbjs/lib/invariant');
 
+const {babelCore: babel} = require('../../babel-bridge');
+
 import type {Ast} from 'babel-core';
 import type {BabelSourceMap} from 'babel-core';
 const t = babel.types;

packages/metro/src/ModuleGraph/test-helpers.js

@@ -10,9 +10,10 @@
  */
 'use strict';
 
-const generate = require('babel-generator').default;
 const stub = require('sinon/lib/sinon/stub');
 
+const {babelGenerate: generate} = require('../babel-bridge');
+
 exports.fn = () => {
   const s = stub();
   const f = jest.fn(s);

packages/metro/src/ModuleGraph/worker/JsFileWrapping.js

@@ -14,7 +14,7 @@
 
 /* eslint-disable no-unclear-flowtypes */
 
-const babel = require('babel-core');
+const {babelCore: babel} = require('../../babel-bridge');
 
 const MODULE_FACTORY_PARAMETERS = ['global', 'require', 'module', 'exports'];
 const POLYFILL_FACTORY_PARAMETERS = ['global'];

packages/metro/src/ModuleGraph/worker/__tests__/collectDependencies-test.js

@@ -13,9 +13,9 @@
 
 'use strict';
 
-const babylon = require('babylon');
 const collectDependencies = require('../collectDependencies');
 
+const {babylon} = require('../../../babel-bridge');
 const {codeFromAst, comparableCode} = require('../../test-helpers');
 
 const {any} = expect;

packages/metro/src/ModuleGraph/worker/__tests__/optimizeDependencies-test.js

@@ -13,8 +13,9 @@
 
 'use strict';
 
-const babylon = require('babylon');
 const optimizeDependencies = require('../optimizeDependencies');
+
+const {babylon} = require('../../../babel-bridge');
 const {InvalidRequireCallError} = optimizeDependencies;
 
 const {codeFromAst, comparableCode} = require('../../test-helpers');

packages/metro/src/ModuleGraph/worker/__tests__/transform-module-test.js

@@ -15,17 +15,19 @@
 
 const invariant = require('fbjs/lib/invariant');
 const nullthrows = require('fbjs/lib/nullthrows');
-const t = require('babel-types');
 const transformModule = require('../transform-module');
 
+const {babelTypes: types} = require('../../../babel-bridge');
+const {babylon: {parse}} = require('../../../babel-bridge');
+const {babelGenerate: generate} = require('../../../babel-bridge');
+const {babelTraverse: traverse} = require('../../../babel-bridge');
 const {fn} = require('../../test-helpers');
-const {parse} = require('babylon');
 const {SourceMapConsumer} = require('source-map');
-const generate = require('babel-generator').default;
-const {traverse} = require('babel-core');
 
 import type {TransformVariants} from '../../types.flow';
 
+const t = types;
+
 jest.mock('image-size', () => buffer => {
   return JSON.parse(buffer.toString('utf8')).__size;
 });

packages/metro/src/ModuleGraph/worker/collectDependencies.js

@@ -12,11 +12,12 @@
 
 'use strict';
 
-const babelTemplate = require('babel-template');
 const nullthrows = require('fbjs/lib/nullthrows');
 
-const {traverse, types} = require('babel-core');
+const {babelTemplate} = require('../../babel-bridge');
-const prettyPrint = require('babel-generator').default;
+const {babelTraverse: traverse} = require('../../babel-bridge');
+const {babelTypes: types} = require('../../babel-bridge');
+const {babelGenerate: generate} = require('../../babel-bridge');
 
 import type {TransformResultDependency} from '../types.flow';
 import type {Ast} from 'babel-core';
@@ -189,7 +190,7 @@ const makeAsyncRequire = babelTemplate(
 );
 
 function invalidRequireOf(type, node) {
-  const str = prettyPrint(node).code;
+  const str = generate(node).code;
   return new InvalidRequireCallError(type, str, node.loc.start);
 }
 

packages/metro/src/ModuleGraph/worker/generate.js

@@ -14,7 +14,7 @@
 
 /* eslint-disable no-unclear-flowtypes */
 
-const babelGenerate = require('babel-generator').default;
+const {babelGenerate} = require('../../babel-bridge');
 
 function generate(
   ast: Object,

packages/metro/src/ModuleGraph/worker/optimize-module.js

@@ -12,7 +12,7 @@
 
 'use strict';
 
-const babel = require('babel-core');
+const {babelCore: babel} = require('../../babel-bridge');
 const constantFolding = require('../../JSTransformer/worker/constant-folding')
   .plugin;
 const generate = require('./generate');

packages/metro/src/ModuleGraph/worker/optimizeDependencies.js

@@ -12,8 +12,8 @@
 
 'use strict';
 
-const {traverse} = require('babel-core');
+const {babelTraverse: traverse} = require('../../babel-bridge');
-const prettyPrint = require('babel-generator').default;
+const {babelGenerate} = require('../../babel-bridge');
 
 import type {TransformResultDependency} from '../types.flow';
 import type {Ast} from 'babel-core';
@@ -67,7 +67,7 @@ function processRequireCall(node) {
     throw new InvalidRequireCallError(
       'Post-transform calls to require() expect 2 arguments, the first ' +
         'of which has the shape `_dependencyMapName[123]`, ' +
-        `but this was found: \`${prettyPrint(node).code}\``,
+        `but this was found: \`${babelGenerate(node).code}\``,
     );
   }
   node.arguments = [node.arguments[0]];

packages/metro/src/babel-bridge.js

@@ -0,0 +1,45 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * @emails oncall+javascript_foundation
+ * @flow (won't like this)
+ * @format
+ */
+
+'use strict';
+
+// This is a temporary migration bridge to switch between babel 6 and 7
+
+const babelCore6 = require('babel-core');
+const babelGenerate6 = require('babel-generator').default;
+const babelTemplate6 = require('babel-template');
+const babelTraverse6 = require('babel-core').traverse;
+const babelTypes6 = require('babel-core').types;
+const babylon6 = require('babylon');
+
+const externalHelpersPlugin6 = require('babel-plugin-external-helpers');
+const inlineRequiresPlugin6 = require('babel-preset-fbjs/plugins/inline-requires');
+const makeHMRConfig6 = require('babel-preset-react-native/configs/hmr');
+const resolvePlugins6 = require('babel-preset-react-native/lib/resolvePlugins');
+
+module.exports = {
+  // TODO: `babelGenerate: process.env.BABEL_VER === 7 ? babelGenerate7 : babelGenerate6,` etc
+  version: process.env.BABEL_VER === '7' ? 7 : 6,
+
+  babelCore: babelCore6,
+  babelGenerate: babelGenerate6,
+  babelTemplate: babelTemplate6,
+  babelTraverse: babelTraverse6,
+  babelTypes: babelTypes6,
+  babylon: babylon6,
+
+  externalHelpersPlugin: externalHelpersPlugin6,
+  inlineRequiresPlugin: inlineRequiresPlugin6,
+  makeHMRConfig: makeHMRConfig6,
+  resolvePlugins: resolvePlugins6,
+};

packages/metro/src/defaultTransform.js

@@ -11,7 +11,7 @@
  */
 'use strict';
 
-const babel = require('babel-core');
+const {babelCore: babel} = require('./babel-bridge');
 
 import type {TransformOptions} from './JSTransformer/worker';
 import type {Plugins as BabelPlugins} from 'babel-core';

packages/metro/src/lib/__tests__/__snapshots__/getTransformCacheKeyFn-test.js.snap

@@ -1,3 +1,3 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`getTransformCacheKeyFn Should return always the same key for the same params 1`] = `"1b825aa92d266cc01c946596e777463bd7e68c82"`;
+exports[`getTransformCacheKeyFn Should return always the same key for the same params 1`] = `"dbf93a9e80558a6a2a7d3deb2f79c523dca3c7ce"`;

packages/metro/src/lib/polyfills/__tests__/require-test.js

@@ -14,7 +14,7 @@
 
 'use strict';
 
-const babel = require('babel-core');
+const {babelCore: babel} = require('../../../babel-bridge');
 const babelConfig = require('../../../babelRegisterOnly').config;
 const fs = require('fs');
 

packages/metro/src/transformer.js

@@ -13,18 +13,19 @@
  */
 'use strict';
 
-const babel = require('babel-core');
 const crypto = require('crypto');
-const externalHelpersPlugin = require('babel-plugin-external-helpers');
 const fs = require('fs');
-const inlineRequiresPlugin = require('babel-preset-fbjs/plugins/inline-requires');
 const json5 = require('json5');
-const makeHMRConfig = require('babel-preset-react-native/configs/hmr');
 const path = require('path');
-const resolvePlugins = require('babel-preset-react-native/lib/resolvePlugins');
 
-import type {Plugins as BabelPlugins} from 'babel-core';
+const {babelCore: babel} = require('./babel-bridge');
+const {externalHelpersPlugin} = require('./babel-bridge');
+const {inlineRequiresPlugin} = require('./babel-bridge');
+const {makeHMRConfig} = require('./babel-bridge');
+const {resolvePlugins} = require('./babel-bridge');
+
 import type {Transformer, TransformOptions} from './JSTransformer/worker';
+import type {Plugins as BabelPlugins} from 'babel-core';
 
 const cacheKeyParts = [
   fs.readFileSync(__filename),