add flow

Summary: This adds flow types to new code written for the Buck/Packager integration.

Reviewed By: cpojer

Differential Revision: D4175156

fbshipit-source-id: 38c3d2c9176c7b3cf22b8baed7d445a75d033d04

react-packager/src/ModuleGraph/Graph.js

@@ -10,10 +10,10 @@
  */
 'use strict';
 
+const invariant = require('fbjs/lib/invariant');
 const memoize = require('async/memoize');
 const queue = require('async/queue');
 const seq = require('async/seq');
-const invariant = require('fbjs/lib/invariant');
 
 import type {GraphFn, LoadFn, ResolveFn, File, Module} from './types.flow';
 
@@ -28,7 +28,8 @@ exports.create = function create(resolve: ResolveFn, load: LoadFn): GraphFn {
 
     if (typeof platform !== 'string') {
       log.error('`Graph`, called without a platform');
-      return callback(Error('The target platform has to be passed'));
+      callback(Error('The target platform has to be passed'));
+      return;
     }
 
     const modules: Map<string | null, Module> = new Map();

react-packager/src/ModuleGraph/types.flow.js

@@ -12,47 +12,48 @@
 
 import type {Console} from 'console';
 
-type callback<T> = (error: ?Error, result?: T) => any;
+export type Callback<A = void, B = void>
-type callback2<T, T1> = (error: ?Error, a?: T, b?: T1) => any;
+  = ((error: Error) => mixed)
+  & ((error: null | void, a: A, b: B) => mixed);
 
 type ResolveOptions = {
   log?: Console,
 };
 
-type LoadOptions = {
+type LoadOptions = {|
   log?: Console,
   optimize?: boolean,
   platform?: string,
-};
+|};
 
-type GraphOptions = {
+type GraphOptions = {|
   cwd?: string,
   log?: Console,
   optimize?: boolean,
   skip?: Set<string>,
-};
+|};
 
-type Dependency = {
+type Dependency = {|
   id: string,
   path: string,
-};
+|};
 
-export type File = {
+export type File = {|
-  path: string,
-  code?: string,
   ast: Object,
-};
+  code?: string,
+  path: string,
+|};
 
-export type Module = {
+export type Module = {|
-  file: File,
   dependencies: Array<Dependency>,
-};
+  file: File,
+|};
 
 export type GraphFn = (
   entryPoints: Iterable<string>,
   platform: string,
   options?: GraphOptions,
-  callback?: callback<Array<Module>>,
+  callback?: Callback<Array<Module>>,
 ) => void;
 
 export type ResolveFn = (
@@ -60,32 +61,49 @@ export type ResolveFn = (
   source: string,
   platform: string,
   options?: ResolveOptions,
-  callback: callback<string>,
+  callback: Callback<string>,
 ) => void;
 
 export type LoadFn = (
   file: string,
   options: LoadOptions,
-  callback: callback2<File, Array<string>>,
+  callback: Callback<File, Array<string>>,
 ) => void;
 
-type TransformResult = {
+export type TransformResult = {|
   code: string,
+  dependencies: Array<string>,
+  dependencyMapName?: string,
   map: ?Object,
-  dependencies: Array<String>,
+|};
-};
 
 export type TransformedFile = {
-  file: string,
   code: string,
-  transformed: {[variant: string]: TransformResult},
+  file: string,
   hasteID: ?string,
+  isPolyfill: boolean,
   package?: PackageData,
+  transformed: {[variant: string]: TransformResult},
 };
 
-export type PackageData = {
+export type PackageData = {|
-  name?: string,
-  main?: string,
   browser?: Object | string,
+  main?: string,
+  name?: string,
   'react-native'?: Object | string,
-};
+|};
+
+export type TransformFnResult = {|
+  ast: Object,
+  map?: Object,
+|};
+
+export type TransformFn = (
+  data: {|
+    filename: string,
+    options?: Object,
+    plugins?: Array<string | Object | [string | Object, any]>,
+    sourceCode: string,
+  |},
+  callback: Callback<TransformFnResult>
+) => void;

react-packager/src/ModuleGraph/worker.js

@@ -5,257 +5,21 @@
  * 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.
+ *
+ * @flow
  */
 'use strict';
 
-// RUNS UNTRANSFORMED IN A WORKER PROCESS. ONLY USE NODE 4 COMPATIBLE FEATURES!
+const optimizeModule = require('./worker/optimize-module');
+const transformModule = require('./worker/transform-module');
+const wrapWorkerFn = require('./worker/wrap-worker-fn');
 
-const babel = require('babel-core');
+import type {OptimizationOptions} from './worker/optimize-module';
-const babelGenerate = require('babel-generator').default;
+import type {TransformOptions} from './worker/transform-module';
-const collectDependencies = require('../JSTransformer/worker/collect-dependencies');
+import type {WorkerFnWithIO} from './worker/wrap-worker-fn';
-const constantFolding = require('../JSTransformer/worker/constant-folding').plugin;
-const docblock = require('../node-haste/DependencyGraph/docblock');
-const fs = require('fs');
-const inline = require('../JSTransformer/worker/inline').plugin;
-const minify = require('../JSTransformer/worker/minify');
-const mkdirp = require('mkdirp');
-const path = require('path');
-const series = require('async/series');
-const sourceMap = require('source-map');
 
-const basename = path.basename;
-const dirname = path.dirname;
-const defaultVariants = {default: {}};
-const moduleFactoryParameters = ['require', 'module', 'global', 'exports'];
-const polyfillFactoryParameters = ['global'];
 
-function transformJSON(infile, options, outfile, callback) {
+exports.optimizeModule =
-  const json = fs.readFileSync(infile, 'utf8');
+  (wrapWorkerFn(optimizeModule): WorkerFnWithIO<OptimizationOptions>);
-  const value = JSON.parse(json);
+exports.transformModule =
-
+  (wrapWorkerFn(transformModule): WorkerFnWithIO<TransformOptions>);
-  const filename = options.filename || infile;
-  const code =
-    `__d(function(${moduleFactoryParameters.join(', ')}) { module.exports = \n${
-      json
-    }\n})`;
-
-  const moduleData = {
-    code,
-    map: null, // no source map for JSON files!
-    dependencies: [],
-  };
-  const transformed = {};
-
-  Object
-    .keys(options.variants || defaultVariants)
-    .forEach(key => (transformed[key] = moduleData));
-
-  const result = {
-    file: filename,
-    code: json,
-    transformed,
-    hasteID: value.name,
-  };
-
-  if (basename(filename) === 'package.json') {
-    result.package = {
-      name: value.name,
-      main: value.main,
-      browser: value.browser,
-      'react-native': value['react-native'],
-    };
-  }
-
-  writeResult(outfile, result);
-  callback(null);
-}
-
-function transformModule(infile, options, outfile, callback) {
-  const filename = infile;
-  if (filename.endsWith('.json')) {
-    return transformJSON(infile, options, outfile, callback);
-  }
-
-  const transform = require(options.transform);
-  const code = fs.readFileSync(infile, 'utf8');
-
-  const variants = options.variants || defaultVariants;
-  const tasks = {};
-  Object.keys(variants).forEach(name => {
-    tasks[name] = cb => transform({
-      filename,
-      sourceCode: code,
-      options: variants[name],
-    }, cb);
-  });
-
-  series(tasks, (error, transformed) => {
-    if (error) {
-      callback(error);
-      return;
-    }
-
-    Object.keys(transformed).forEach(key => {
-      transformed[key] =
-        makeResult(transformed[key].ast, filename, code, options.polyfill);
-    });
-
-    const annotations = docblock.parseAsObject(docblock.extract(code));
-
-    const result = {
-      code,
-      file: filename,
-      isPolyfill: !!options.polyfill,
-      hasteID: annotations.providesModule || annotations.provide || null,
-      transformed,
-    };
-
-    try {
-      writeResult(outfile, result);
-    } catch (writeError) {
-      callback(writeError);
-      return;
-    }
-    callback(null);
-  });
-}
-
-function optimizeModule(
-  infile,
-  outfile,
-  optimizationOptions,
-  callback,
-) {
-  const data = JSON.parse(fs.readFileSync(infile, 'utf8'));
-  const transformed = data.transformed;
-  const result = Object.assign({}, data);
-  result.transformed = {};
-
-  const file = data.file;
-  const code = data.code;
-
-  Object.keys(transformed).forEach(key => {
-    result.transformed[key] =
-      optimize(transformed[key], file, code, optimizationOptions);
-  });
-  writeResult(outfile, result);
-
-  callback(null);
-}
-
-function makeResult(ast, filename, sourceCode, isPolyfill = false) {
-  const {dependencies, dependencyMapName} = isPolyfill
-    ? {dependencies: []}
-    : collectDependencies(ast);
-  const file = isPolyfill
-    ? wrapPolyfill(ast)
-    : wrapModule(ast, dependencyMapName);
-
-  const gen = generate(file, filename, sourceCode);
-  return {code: gen.code, map: gen.map, dependencies, dependencyMapName};
-}
-
-function wrapModule(file, dependencyMapName) {
-  const t = babel.types;
-  const params = moduleFactoryParameters.concat(dependencyMapName);
-  const factory = functionFromProgram(file.program, params);
-  const def = t.callExpression(t.identifier('__d'), [factory]);
-  return t.file(t.program([t.expressionStatement(def)]));
-}
-
-function wrapPolyfill(file) {
-  const t = babel.types;
-  const factory = functionFromProgram(file.program, polyfillFactoryParameters);
-  const iife = t.callExpression(factory, [t.identifier('this')]);
-  return t.file(t.program([t.expressionStatement(iife)]));
-}
-
-function functionFromProgram(program, parameters) {
-  const t = babel.types;
-  return t.functionExpression(
-    t.identifier(''),
-    parameters.map(makeIdentifier),
-    t.blockStatement(program.body, program.directives),
-  );
-}
-
-function optimize(transformed, file, originalCode, options) {
-  const optimized =
-    optimizeCode(transformed.code, transformed.map, file, options);
-
-  const dependencies = options.isPolyfill
-    ? []
-    : collectDependencies.forOptimization(
-        optimized.ast,
-        transformed.dependencies,
-        transformed.dependencyMapName,
-      );
-
-  const inputMap = transformed.map;
-  const gen = generate(optimized.ast, file, originalCode);
-
-  const min = minify(
-    file,
-    gen.code,
-    inputMap && mergeSourceMaps(file, inputMap, gen.map),
-  );
-  return {code: min.code, map: inputMap && min.map, dependencies};
-}
-
-function optimizeCode(code, map, filename, inliningOptions) {
-  return babel.transform(code, {
-    plugins: [
-      [constantFolding],
-      [inline, Object.assign({isWrapped: true}, inliningOptions)],
-    ],
-    babelrc: false,
-    code: false,
-    filename,
-  });
-}
-
-function generate(ast, filename, sourceCode) {
-  return babelGenerate(ast, {
-    comments: false,
-    compact: true,
-    filename,
-    sourceFileName: filename,
-    sourceMaps: true,
-    sourceMapTarget: filename,
-  }, sourceCode);
-}
-
-function mergeSourceMaps(file, originalMap, secondMap) {
-  const merged = new sourceMap.SourceMapGenerator();
-  const inputMap = new sourceMap.SourceMapConsumer(originalMap);
-  new sourceMap.SourceMapConsumer(secondMap)
-    .eachMapping(mapping => {
-      const original = inputMap.originalPositionFor({
-        line: mapping.originalLine,
-        column: mapping.originalColumn,
-      });
-      if (original.line == null) {
-        return;
-      }
-
-      merged.addMapping({
-        generated: {line: mapping.generatedLine, column: mapping.generatedColumn},
-        original: {line: original.line, column: original.column || 0},
-        source: file,
-        name: original.name || mapping.name,
-      });
-    });
-  return merged.toJSON();
-}
-
-function writeResult(outfile, result) {
-  mkdirp.sync(dirname(outfile));
-  fs.writeFileSync(outfile, JSON.stringify(result), 'utf8');
-}
-
-function makeIdentifier(name) {
-  return babel.types.identifier(name);
-}
-
-exports.transformModule = transformModule;
-exports.optimizeModule = optimizeModule;

react-packager/src/ModuleGraph/worker.js.flow

@@ -1,43 +0,0 @@
-/**
- * Copyright (c) 2016-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.
- *
- * @flow
- */
-'use strict';
-
-declare export function transformModule(
-  infile: string,
-  options: {
-    filename?: string,
-    transform: string,
-    variants?: {[key: string]: Object},
-  },
-  outfile: string,
-  callback: (e?: Error) => void,
-): void
-
-declare export function optimizeModule(
-  infile: string,
-  outfile: string,
-  optimizationOptions: {
-    dev?: boolean,
-    isPolyfill?: boolean,
-    platform?: string,
-  },
-  callback: (e?: Error) => void,
-): void
-
-declare function optimizeCode(
-  code: string,
-  map: Object,
-  filename: string,
-  inliningOptions: {|
-    dev?: boolean,
-    platform?: string,
-  |},
-): {code: string, map: Object};

react-packager/src/ModuleGraph/worker/__tests__/wrap-worker-fn-test.js

@@ -0,0 +1,89 @@
+/**
+ * Copyright (c) 2016-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.
+ */
+'use strict';
+
+jest
+  .disableAutomock()
+  .setMock('fs', jest.genMockFromModule('fs'))
+  .mock('mkdirp');
+
+const wrapWorkerFn = require('../wrap-worker-fn');
+const {dirname} = require('path');
+const {fn} = require('../../test-helpers');
+
+const {any} = jasmine;
+
+describe('wrapWorkerFn:', () => {
+  const infile = '/arbitrary/in/file';
+  const outfile = '/arbitrary/in/file';
+
+  let workerFn, wrapped;
+  beforeEach(() => {
+    workerFn = fn();
+    workerFn.stub.yields();
+    wrapped = wrapWorkerFn(workerFn);
+  });
+
+  const fs = require('fs');
+  const mkdirp = require('mkdirp');
+
+  it('reads the passed-in file synchronously as UTF-8', done => {
+    wrapped(infile, outfile, {}, () => {
+      expect(fs.readFileSync).toBeCalledWith(infile, 'utf8');
+      done();
+    });
+  });
+
+  it('calls the worker function with file contents and options', done => {
+    const contents = 'arbitrary(contents);';
+    const options = {arbitrary: 'options'};
+    fs.readFileSync.mockReturnValue(contents);
+    wrapped(infile, outfile, options, () => {
+      expect(workerFn).toBeCalledWith(contents, options, any(Function));
+      done();
+    });
+  });
+
+  it('passes through any error that the worker function calls back with', done => {
+    const error = new Error();
+    workerFn.stub.yields(error);
+    wrapped(infile, outfile, {}, e => {
+      expect(e).toBe(error);
+      done();
+    });
+  });
+
+  it('writes the result to disk', done => {
+    const result = {arbitrary: 'result'};
+    workerFn.stub.yields(null, result);
+    wrapped(infile, outfile, {}, () => {
+      expect(mkdirp.sync).toBeCalledWith(dirname(outfile));
+      expect(fs.writeFileSync).toBeCalledWith(outfile, JSON.stringify(result), 'utf8');
+      done();
+    });
+  });
+
+  it('calls back with any error thrown by `mkdirp.sync`', done => {
+    const error = new Error();
+    mkdirp.sync.mockImplementationOnce(() => { throw error; });
+    wrapped(infile, outfile, {}, e => {
+      expect(e).toBe(error);
+      done();
+    });
+  });
+
+  it('calls back with any error thrown by `fs.writeFileSync`', done => {
+    const error = new Error();
+    fs.writeFileSync.mockImplementationOnce(() => { throw error; });
+    wrapped(infile, outfile, {}, e => {
+      expect(e).toBe(error);
+      done();
+    });
+  });
+});

react-packager/src/ModuleGraph/worker/collect-dependencies.js

@@ -5,14 +5,21 @@
  * 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.
+ *
+ * @flow
  */
 'use strict';
 
-// RUNS UNTRANSFORMED IN A WORKER PROCESS. ONLY USE NODE 4 COMPATIBLE FEATURES!
+const nullthrows = require('fbjs/lib/nullthrows');
 
 const {traverse, types} = require('babel-core');
 
+type AST = Object;
+
 class Replacement {
+  nameToIndex: Map<string, number>;
+  nextIndex: number;
+
   constructor() {
     this.nameToIndex = new Map();
     this.nextIndex = 0;
@@ -47,6 +54,9 @@ class Replacement {
 }
 
 class ProdReplacement {
+  replacement: Replacement;
+  names: Array<string>;
+
   constructor(names) {
     this.replacement = new Replacement();
     this.names = names;
@@ -118,14 +128,15 @@ function collectDependencies(ast, replacement, dependencyMapIdentifier) {
 
   return {
     dependencies: replacement.getNames(),
-    dependencyMapName: traversalState.dependencyMapIdentifier.name,
+    dependencyMapName: nullthrows(traversalState.dependencyMapIdentifier).name,
   };
 }
 
 exports = module.exports =
-  ast => collectDependencies(ast, new Replacement());
+  (ast: AST) => collectDependencies(ast, new Replacement());
 exports.forOptimization =
-  (ast, names, dependencyMapName) => collectDependencies(
+  (ast: AST, names: Array<string>, dependencyMapName?: string) =>
+    collectDependencies(
       ast,
       new ProdReplacement(names),
       dependencyMapName && types.identifier(dependencyMapName),

react-packager/src/ModuleGraph/worker/generate.js

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) 2016-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.
+ *
+ * @flow
+ */
+'use strict';
+
+const babelGenerate = require('babel-generator').default;
+
+function generate(ast: Object, filename: string, sourceCode: string) {
+  return babelGenerate(ast, {
+    comments: false,
+    compact: true,
+    filename,
+    sourceFileName: filename,
+    sourceMaps: true,
+    sourceMapTarget: filename,
+  }, sourceCode);
+}
+
+module.exports = generate;

react-packager/src/ModuleGraph/worker/optimize-module.js

@@ -0,0 +1,106 @@
+/**
+ * Copyright (c) 2016-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.
+ *
+ * @flow
+ */
+'use strict';
+
+const babel = require('babel-core');
+const collectDependencies = require('./collect-dependencies');
+const constantFolding = require('../../JSTransformer/worker/constant-folding').plugin;
+const generate = require('./generate');
+const inline = require('../../JSTransformer/worker/inline').plugin;
+const minify = require('../../JSTransformer/worker/minify');
+const sourceMap = require('source-map');
+
+import type {Callback, TransformedFile, TransformResult} from '../types.flow';
+
+export type OptimizationOptions = {|
+  dev?: boolean,
+  isPolyfill?: boolean,
+  platform?: string,
+|};
+
+function optimizeModule(
+  json: string,
+  optimizationOptions: OptimizationOptions,
+  callback: Callback<TransformedFile>,
+): void {
+  const data: TransformedFile = JSON.parse(json);
+  const {code, file, transformed} = data;
+  const result = {...data, transformed: {}};
+
+  //$FlowIssue #14545724
+  Object.entries(transformed).forEach(([k, t: TransformResult]: [*, TransformResult]) => {
+    result.transformed[k] = optimize(t, file, code, optimizationOptions);
+  });
+  callback(null, result);
+}
+
+function optimize(transformed, file, originalCode, options): TransformResult {
+  const {code, dependencyMapName, map} = transformed;
+  const optimized = optimizeCode(code, map, file, options);
+
+  let dependencies;
+  if (options.isPolyfill) {
+    dependencies = [];
+  } else {
+    ({dependencies} = collectDependencies.forOptimization(
+      optimized.ast,
+      transformed.dependencies,
+      dependencyMapName,
+    ));
+  }
+
+  const inputMap = transformed.map;
+  const gen = generate(optimized.ast, file, originalCode);
+
+  const min = minify(
+    file,
+    gen.code,
+    inputMap && mergeSourceMaps(file, inputMap, gen.map),
+  );
+  return {code: min.code, map: inputMap && min.map, dependencies};
+}
+
+function optimizeCode(code, map, filename, inliningOptions) {
+  return babel.transform(code, {
+    plugins: [
+      [constantFolding],
+      [inline, {...inliningOptions, isWrapped: true}],
+    ],
+    babelrc: false,
+    code: false,
+    filename,
+  });
+}
+
+function mergeSourceMaps(file, originalMap, secondMap) {
+  const merged = new sourceMap.SourceMapGenerator();
+  const inputMap = new sourceMap.SourceMapConsumer(originalMap);
+  new sourceMap.SourceMapConsumer(secondMap)
+    .eachMapping(mapping => {
+      const original = inputMap.originalPositionFor({
+        line: mapping.originalLine,
+        column: mapping.originalColumn,
+      });
+      if (original.line == null) {
+        return;
+      }
+
+      merged.addMapping({
+        generated: {line: mapping.generatedLine, column: mapping.generatedColumn},
+        original: {line: original.line, column: original.column || 0},
+        source: file,
+        name: original.name || mapping.name,
+      });
+    });
+  return merged.toJSON();
+}
+
+module.exports = optimizeModule;

react-packager/src/ModuleGraph/worker/transform-module.js

@@ -0,0 +1,165 @@
+/**
+ * Copyright (c) 2016-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.
+ *
+ * @flow
+ */
+'use strict';
+
+const babel = require('babel-core');
+const collectDependencies = require('./collect-dependencies');
+const docblock = require('../../node-haste/DependencyGraph/docblock');
+const generate = require('./generate');
+const series = require('async/series');
+
+const {basename} = require('path');
+
+import type {
+  Callback,
+  TransformedFile,
+  TransformFn,
+  TransformFnResult,
+  TransformResult,
+} from '../types.flow';
+
+type TransformVariants = {[key: string]: Object};
+export type TransformOptions = {|
+  filename: string,
+  polyfill?: boolean,
+  transform: TransformFn,
+  variants?: TransformVariants,
+|};
+
+const defaultVariants = {default: {}};
+const moduleFactoryParameters = ['require', 'module', 'global', 'exports'];
+const polyfillFactoryParameters = ['global'];
+
+function transformModule(
+  code: string,
+  options: TransformOptions,
+  callback: Callback<TransformedFile>,
+): void {
+  if (options.filename.endsWith('.json')) {
+    return transformJSON(code, options, callback);
+  }
+
+  const {filename, transform, variants = defaultVariants} = options;
+  const tasks = {};
+  Object.keys(variants).forEach(name => {
+    tasks[name] = cb => transform({
+      filename,
+      sourceCode: code,
+      options: variants[name],
+    }, cb);
+  });
+
+  series(tasks, (error, results: {[key: string]: TransformFnResult}) => {
+    if (error) {
+      callback(error);
+      return;
+    }
+
+    const transformed: {[key: string]: TransformResult} = {};
+
+    //$FlowIssue #14545724
+    Object.entries(results).forEach(([key, value]: [*, TransformFnResult]) => {
+      transformed[key] = makeResult(value.ast, filename, code, options.polyfill);
+    });
+
+    const annotations = docblock.parseAsObject(docblock.extract(code));
+
+    callback(null, {
+      code,
+      file: filename,
+      isPolyfill: !!options.polyfill,
+      hasteID: annotations.providesModule || annotations.provide || null,
+      transformed,
+    });
+  });
+}
+
+function transformJSON(json, options, callback) {
+  const value = JSON.parse(json);
+  const {filename} = options;
+  const code =
+    `__d(function(${moduleFactoryParameters.join(', ')}) { module.exports = \n${
+      json
+    }\n})`;
+
+  const moduleData = {
+    code,
+    map: null, // no source map for JSON files!
+    dependencies: [],
+  };
+  const transformed = {};
+
+  Object
+    .keys(options.variants || defaultVariants)
+    .forEach(key => (transformed[key] = moduleData));
+
+  const result: TransformedFile = {
+    code: json,
+    file: filename,
+    hasteID: value.name,
+    isPolyfill: false,
+    transformed,
+  };
+
+  if (basename(filename) === 'package.json') {
+    result.package = {
+      name: value.name,
+      main: value.main,
+      browser: value.browser,
+      'react-native': value['react-native'],
+    };
+  }
+  callback(null, result);
+}
+
+function makeResult(ast, filename, sourceCode, isPolyfill = false) {
+  let dependencies, dependencyMapName, file;
+  if (isPolyfill) {
+    dependencies = [];
+    file = wrapPolyfill(ast);
+  } else {
+    ({dependencies, dependencyMapName} = collectDependencies(ast));
+    file = wrapModule(ast, dependencyMapName);
+  }
+
+  const gen = generate(file, filename, sourceCode);
+  return {code: gen.code, map: gen.map, dependencies, dependencyMapName};
+}
+
+function wrapModule(file, dependencyMapName) {
+  const t = babel.types;
+  const params = moduleFactoryParameters.concat(dependencyMapName);
+  const factory = functionFromProgram(file.program, params);
+  const def = t.callExpression(t.identifier('__d'), [factory]);
+  return t.file(t.program([t.expressionStatement(def)]));
+}
+
+function wrapPolyfill(file) {
+  const t = babel.types;
+  const factory = functionFromProgram(file.program, polyfillFactoryParameters);
+  const iife = t.callExpression(factory, [t.identifier('this')]);
+  return t.file(t.program([t.expressionStatement(iife)]));
+}
+
+function functionFromProgram(program, parameters) {
+  const t = babel.types;
+  return t.functionExpression(
+    t.identifier(''),
+    parameters.map(makeIdentifier),
+    t.blockStatement(program.body, program.directives),
+  );
+}
+
+function makeIdentifier(name) {
+  return babel.types.identifier(name);
+}
+
+module.exports = transformModule;

react-packager/src/ModuleGraph/worker/wrap-worker-fn.js

@@ -0,0 +1,62 @@
+/**
+ * Copyright (c) 2016-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.
+ *
+ * @flow
+ */
+'use strict';
+
+const fs = require('fs');
+const mkdirp = require('mkdirp');
+
+const {dirname} = require('path');
+
+import type {Callback} from '../types.flow';
+
+type Path = string;
+type WorkerFn<Options> = (
+  fileContents: string,
+  options: Options,
+  callback: Callback<Object>,
+) => void;
+export type WorkerFnWithIO<Options> = (
+  infile: Path,
+  outfile: Path,
+  options: Options,
+  callback: Callback<>,
+) => void;
+
+function wrapWorkerFn<Options>(
+  workerFunction: WorkerFn<Options>,
+): WorkerFnWithIO<Options> {
+  return (
+    infile: Path,
+    outfile: Path,
+    options: Options,
+    callback: Callback<>,
+  ) => {
+    const contents = fs.readFileSync(infile, 'utf8');
+    workerFunction(contents, options, (error, result) => {
+      if (error) {
+        callback(error);
+        return;
+      }
+
+      try {
+        mkdirp.sync(dirname(outfile));
+        fs.writeFileSync(outfile, JSON.stringify(result), 'utf8');
+      } catch (writeError) {
+        callback(writeError);
+        return;
+      }
+
+      callback(null);
+    });
+  };
+}
+
+module.exports = wrapWorkerFn;