Move hmr config generator into its own file, burn the bridge

Reviewed By: mjesun

Differential Revision: D7788847

fbshipit-source-id: 481a457abe58b41f5e7001601c126adc457cd28c

packages/metro/src/babel-bridge.js

@@ -1,63 +0,0 @@
-/**
- * Copyright (c) 2015-present, Facebook, Inc.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
- * @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 makeHMRConfig7 = makeMakeHMRConfig7();
-
-module.exports = {
-  makeHMRConfig: makeHMRConfig7,
-};
-
-function makeMakeHMRConfig7() {
-  // from: babel-preset-react-native/configs/hmr
-  /**
-   * Copyright (c) 2015-present, Facebook, Inc.
-   *
-   * This source code is licensed under the MIT license found in the
-   * LICENSE file in the root directory of this source tree.
-   */
-  'use strict';
-
-  var path = require('path');
-  var hmrTransform = 'react-transform-hmr/lib/index.js';
-  var transformPath = require.resolve(hmrTransform);
-
-  return function(options: mixed, filename?: string) {
-    var transform = filename
-      ? './' + path.relative(path.dirname(filename), transformPath) // packager can't handle absolute paths
-      : hmrTransform;
-
-    // Fix the module path to use '/' on Windows.
-    if (path.sep === '\\') {
-      transform = transform.replace(/\\/g, '/');
-    }
-
-    return {
-      plugins: [
-        [
-          require('metro-babel7-plugin-react-transform'),
-          {
-            transforms: [
-              {
-                transform,
-                imports: ['react'],
-                locals: ['module'],
-              },
-            ],
-          },
-        ],
-      ],
-    };
-  };
-}

packages/metro/src/hmrConfig.js

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails oncall+javascript_foundation
+ * @flow
+ * @format
+ */
+
+'use strict';
+
+// imported from: babel-preset-react-native/configs/hmr
+
+const path = require('path');
+const hmrTransform = 'react-transform-hmr/lib/index.js';
+const transformPath = require.resolve(hmrTransform);
+
+function makeHMRConfig(options: mixed, filename?: string) {
+  // We need to get a _path_ to transform relative to/from.
+  // Either take the filename that is passed on or use the transform as base.
+  let relativePath = filename
+    ? // packager can't handle absolute paths
+      './' + path.relative(path.dirname(filename), transformPath)
+    : hmrTransform;
+
+  // Fix the module path to use '/' on Windows.
+  if (path.sep === '\\') {
+    relativePath = relativePath.replace(/\\/g, '/');
+  }
+
+  return {
+    plugins: [
+      [
+        // This is a Babel 7 compatible fork
+        // of https://github.com/gaearon/babel-plugin-react-transform
+        require('metro-babel7-plugin-react-transform'),
+        {
+          transforms: [
+            {
+              transform: relativePath,
+              imports: ['react'],
+              locals: ['module'],
+            },
+          ],
+        },
+      ],
+    ],
+  };
+}
+
+module.exports = makeHMRConfig;

packages/metro/src/legacy.js

@@ -13,8 +13,8 @@
 const blacklist = require('./blacklist');
 const debug = require('debug');
 const invariant = require('fbjs/lib/invariant');
+const makeHMRConfig = require('./hmrConfig');
 
-const {makeHMRConfig} = require('./babel-bridge');
 const {Logger} = require('metro-core');
 const {fromRawMappings, toSegmentTuple} = require('metro-source-map');
 

packages/metro/src/transformer.js

@@ -16,9 +16,9 @@ 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('./hmrConfig');
 const path = require('path');
 
-const {makeHMRConfig} = require('./babel-bridge');
 const {transformSync} = require('@babel/core');
 
 import type {Transformer, TransformOptions} from './JSTransformer/worker';