From 8799b32d58a531442108d4ceb5ed0d87077bbba1 Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Wed, 8 Nov 2017 00:47:30 +0000
Subject: [PATCH 1/3] Consolidate build process with GCC

---
 package.json            |   4 +-
 scripts/rollup/build.js | 276 +++++++++++++---------------------------
 yarn.lock               |  75 +++++++----
 3 files changed, 143 insertions(+), 212 deletions(-)

diff --git a/package.json b/package.json
index 4b42bb5ebdf26..6ad64860566cd 100644
--- a/package.json
+++ b/package.json
@@ -83,13 +83,13 @@
     "rollup-plugin-commonjs": "^8.2.6",
     "rollup-plugin-inject": "^2.0.0",
     "rollup-plugin-node-resolve": "^2.0.0",
+    "rollup-plugin-prettier": "^0.3.0",
     "rollup-plugin-replace": "^1.1.1",
-    "rollup-plugin-uglify": "^1.0.1",
+    "rollup-plugin-strip-banner": "^0.2.0",
     "run-sequence": "^1.1.4",
     "through2": "^2.0.0",
     "tmp": "~0.0.28",
     "typescript": "~1.8.10",
-    "uglify-js": "^2.5.0",
     "yargs": "^6.3.0"
   },
   "devEngines": {
diff --git a/scripts/rollup/build.js b/scripts/rollup/build.js
index e1756d717b165..47bcbaaa0226c 100644
--- a/scripts/rollup/build.js
+++ b/scripts/rollup/build.js
@@ -2,10 +2,12 @@
 
 const rollup = require('rollup').rollup;
 const babel = require('rollup-plugin-babel');
+const closure = require('rollup-plugin-closure-compiler-js');
 const commonjs = require('rollup-plugin-commonjs');
 const alias = require('rollup-plugin-alias');
-const uglify = require('rollup-plugin-uglify');
+const prettier = require('rollup-plugin-prettier');
 const replace = require('rollup-plugin-replace');
+const stripBanner = require('rollup-plugin-strip-banner');
 const chalk = require('chalk');
 const join = require('path').join;
 const resolve = require('path').resolve;
@@ -24,7 +26,6 @@ const syncReactNativeRT = require('./sync').syncReactNativeRT;
 const syncReactNativeCS = require('./sync').syncReactNativeCS;
 const Packaging = require('./packaging');
 const Header = require('./header');
-const closure = require('rollup-plugin-closure-compiler-js');
 
 const UMD_DEV = Bundles.bundleTypes.UMD_DEV;
 const UMD_PROD = Bundles.bundleTypes.UMD_PROD;
@@ -51,31 +52,16 @@ const errorCodeOpts = {
   errorMapFilePath: 'scripts/error-codes/codes.json',
 };
 
-function getHeaderSanityCheck(bundleType, globalName) {
-  switch (bundleType) {
-    case FB_DEV:
-    case FB_PROD:
-    case RN_DEV:
-    case RN_PROD:
-      let hasteFinalName = globalName;
-      switch (bundleType) {
-        case FB_DEV:
-        case RN_DEV:
-          hasteFinalName += '-dev';
-          break;
-        case FB_PROD:
-        case RN_PROD:
-          hasteFinalName += '-prod';
-          break;
-      }
-      return hasteFinalName;
-    case UMD_DEV:
-    case UMD_PROD:
-      return reactVersion;
-    default:
-      return null;
-  }
-}
+const closureOptions = {
+  compilationLevel: 'SIMPLE',
+  languageIn: 'ECMASCRIPT5_STRICT',
+  languageOut: 'ECMASCRIPT5_STRICT',
+  env: 'CUSTOM',
+  warningLevel: 'QUIET',
+  applyInputSourceMaps: false,
+  useTypesForOptimization: false,
+  processCommonJsModules: false,
+};
 
 function getBanner(bundleType, globalName, filename, moduleType) {
   if (moduleType === RECONCILER) {
@@ -261,7 +247,6 @@ function getRollupOutputOptions(
   return Object.assign(
     {},
     {
-      banner: getBanner(bundleType, globalName, filename, moduleType),
       destDir: 'build/',
       file:
         'build/' +
@@ -270,7 +255,6 @@ function getRollupOutputOptions(
           filename,
           globalName
         ),
-      footer: getFooter(bundleType, filename, moduleType),
       format,
       globals,
       interop: false,
@@ -280,13 +264,6 @@ function getRollupOutputOptions(
   );
 }
 
-function stripEnvVariables(production) {
-  return {
-    __DEV__: production ? 'false' : 'true',
-    'process.env.NODE_ENV': production ? "'production'" : "'development'",
-  };
-}
-
 function getFormat(bundleType) {
   switch (bundleType) {
     case UMD_DEV:
@@ -323,86 +300,21 @@ function getFilename(name, globalName, bundleType) {
   }
 }
 
-function getUglifyConfig(configs) {
-  var mangle = configs.mangle;
-  var preserveVersionHeader = configs.preserveVersionHeader;
-  var removeComments = configs.removeComments;
-  var headerSanityCheck = configs.headerSanityCheck;
-  return {
-    warnings: false,
-    compress: {
-      screw_ie8: true,
-      dead_code: true,
-      unused: true,
-      drop_debugger: true,
-      // we have a string literal <script> that we don't want to evaluate
-      // for FB prod bundles (where we disable mangling)
-      evaluate: mangle,
-      booleans: true,
-      // Our www inline transform combined with Jest resetModules is confused
-      // in some rare cases unless we keep all requires at the top:
-      hoist_funs: mangle,
-    },
-    output: {
-      beautify: !mangle,
-      comments(node, comment) {
-        if (preserveVersionHeader && comment.pos === 0 && comment.col === 0) {
-          // Keep the very first comment (the bundle header) in prod bundles.
-          if (
-            headerSanityCheck &&
-            comment.value.indexOf(headerSanityCheck) === -1
-          ) {
-            // Sanity check: this doesn't look like the bundle header!
-            throw new Error(
-              'Expected the first comment to be the file header but got: ' +
-                comment.value
-            );
-          }
-          return true;
-        }
-        return !removeComments;
-      },
-    },
-    mangle: mangle
-      ? {
-          toplevel: true,
-          screw_ie8: true,
-        }
-      : false,
-  };
-}
-
-// FB uses require('React') instead of require('react').
-// We can't set up a forwarding module due to case sensitivity issues.
-function rewriteFBReactImport() {
-  return {
-    transformBundle(source) {
-      return source.replace(/require\(['"]react['"]\)/g, "require('React')");
-    },
-  };
-}
-
-// Strip 'use strict' directives in individual modules
-// because we always emit them in the file headers.
-// The whole bundle is strict.
-function stripUseStrict() {
-  return {
-    transform(source) {
-      return source.replace(/['"]use strict['"']/g, '');
-    },
-  };
-}
-
-// Plugin that writes to the error code file so that by the time it is picked
-// up by Babel, the errors are already extracted.
-function writeErrorCodes() {
-  const flush = extractErrorCodes(errorCodeOpts);
-  return {
-    transform(source) {
-      flush(source);
-      return source;
-    },
-  };
+function isProductionBundleType(bundleType) {
+  switch (bundleType) {
+    case UMD_DEV:
+    case NODE_DEV:
+    case FB_DEV:
+    case RN_DEV:
+      return false;
+    case UMD_PROD:
+    case NODE_PROD:
+    case FB_PROD:
+    case RN_PROD:
+      return true;
+    default:
+      throw new Error(`Unknown type: ${bundleType}`);
+  }
 }
 
 function getPlugins(
@@ -416,88 +328,77 @@ function getPlugins(
   modulesToStub,
   featureFlags
 ) {
+  const findAndRecordErrorCodes = extractErrorCodes(errorCodeOpts);
   const shims = Modules.getShims(bundleType, entry, featureFlags);
-  const plugins = [
+  const isProduction = isProductionBundleType(bundleType);
+  const isInGlobalScope = bundleType === UMD_DEV || bundleType === UMD_PROD;
+  const isFBBundle = bundleType === FB_DEV || bundleType === FB_PROD;
+  const isRNBundle = bundleType === RN_DEV || bundleType === RN_PROD;
+  const shouldStayReadable = isFBBundle || isRNBundle;
+  return [
     // Extract error codes from invariant() messages into a file.
-    shouldExtractErrors && writeErrorCodes(),
+    shouldExtractErrors && {
+      transform(source) {
+        findAndRecordErrorCodes(source);
+        return source;
+      },
+    },
     // Shim some modules for www custom behavior and optimizations.
     alias(shims),
     // Use Node resolution mechanism.
     resolvePlugin({
       skip: externals,
     }),
+    // Remove license headers from individual modules
+    stripBanner({
+      exclude: 'node_modules/**/*',
+    }),
     // Compile to ES5.
     babel(getBabelConfig(updateBabelOptions, bundleType)),
-    stripUseStrict(),
-  ].filter(Boolean);
-
-  const headerSanityCheck = getHeaderSanityCheck(bundleType, globalName);
-  switch (bundleType) {
-    case UMD_DEV:
-    case NODE_DEV:
-      plugins.push(replace(stripEnvVariables(false)), commonjs());
-      break;
-    case UMD_PROD:
-    case NODE_PROD:
-      plugins.push(
-        replace(stripEnvVariables(true)),
-        commonjs(),
-        closure({
-          compilationLevel: 'SIMPLE',
-          languageIn: 'ECMASCRIPT5_STRICT',
-          languageOut: 'ECMASCRIPT5_STRICT',
-          env: 'CUSTOM',
-          warningLevel: 'QUIET',
+    // Remove 'use strict' from individual source files.
+    {
+      transform(source) {
+        return source.replace(/['"]use strict['"']/g, '');
+      },
+    },
+    // Turn __DEV__ and process.env checks into constants.
+    replace({
+      __DEV__: isProduction ? 'false' : 'true',
+      'process.env.NODE_ENV': isProduction ? "'production'" : "'development'",
+    }),
+    // We still need CommonJS for external deps like object-assign.
+    commonjs(),
+    // www still needs require('React') rather than require('react')
+    isFBBundle && {
+      transformBundle(source) {
+        return source.replace(/require\(['"]react['"]\)/g, "require('React')");
+      },
+    },
+    // Apply dead code elimination and/or minification.
+    isProduction &&
+      closure(
+        Object.assign({}, closureOptions, {
           // Don't let it create global variables in the browser.
           // https://github.com/facebook/react/issues/10909
-          assumeFunctionWrapper: bundleType !== UMD_PROD,
-          applyInputSourceMaps: false,
-          useTypesForOptimization: false,
-          processCommonJsModules: false,
+          assumeFunctionWrapper: !isInGlobalScope,
+          // Works because `google-closure-compiler-js` is forked in Yarn lockfile.
+          // We can remove this if GCC merges my PR:
+          // https://github.com/google/closure-compiler/pull/2707
+          // and then the compiled version is released via `google-closure-compiler-js`.
+          renaming: !shouldStayReadable,
         })
-      );
-      break;
-    case FB_DEV:
-      plugins.push(
-        replace(stripEnvVariables(false)),
-        commonjs(),
-        rewriteFBReactImport()
-      );
-      break;
-    case FB_PROD:
-      plugins.push(
-        replace(stripEnvVariables(true)),
-        commonjs(),
-        uglify(
-          getUglifyConfig({
-            mangle: bundleType !== FB_PROD,
-            preserveVersionHeader: bundleType === UMD_PROD,
-            // leave comments in for source map debugging purposes
-            // they will be stripped as part of FB's build process
-            removeComments: bundleType !== FB_PROD,
-            headerSanityCheck,
-          })
-        ),
-        rewriteFBReactImport()
-      );
-      break;
-    case RN_DEV:
-    case RN_PROD:
-      plugins.push(
-        replace(stripEnvVariables(bundleType === RN_PROD)),
-        commonjs(),
-        uglify(
-          getUglifyConfig({
-            mangle: false,
-            preserveVersionHeader: true,
-            removeComments: true,
-            headerSanityCheck,
-          })
-        )
-      );
-      break;
-  }
-  plugins.push(
+      ),
+    // Add the whitespace back if necessary.
+    shouldStayReadable && prettier(),
+    // License and haste headers, top-level `if` blocks.
+    {
+      transformBundle(source) {
+        const banner = getBanner(bundleType, globalName, filename, moduleType);
+        const footer = getFooter(bundleType, filename, moduleType);
+        return banner + '\n' + source + '\n' + footer;
+      },
+    },
+    // Record bundle size.
     sizes({
       getSize: (size, gzip) => {
         const key = `${filename} (${bundleType})`;
@@ -506,9 +407,8 @@ function getPlugins(
           gzip,
         };
       },
-    })
-  );
-  return plugins;
+    }),
+  ].filter(Boolean);
 }
 
 function createBundle(bundle, bundleType) {
diff --git a/yarn.lock b/yarn.lock
index 8b42751657a85..983d7b9d6b19b 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1437,7 +1437,7 @@ detective@^4.3.1:
     acorn "^4.0.3"
     defined "^1.0.0"
 
-diff@^3.2.0:
+diff@3.3.0, diff@^3.2.0:
   version "3.3.0"
   resolved "https://registry.yarnpkg.com/diff/-/diff-3.3.0.tgz#056695150d7aa93237ca7e378ac3b1682b7963b9"
 
@@ -1798,6 +1798,13 @@ extglob@^0.3.1:
   dependencies:
     is-extglob "^1.0.0"
 
+extract-banner@0.1.2:
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/extract-banner/-/extract-banner-0.1.2.tgz#61d1ed5cce3acdadb35f4323910b420364241a7f"
+  dependencies:
+    strip-bom-string "^0.1.2"
+    strip-use-strict "^0.1.0"
+
 extsprintf@1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/extsprintf/-/extsprintf-1.0.2.tgz#e1080e0658e300b06294990cc70e1502235fd550"
@@ -2150,8 +2157,8 @@ glogg@^1.0.0:
     sparkles "^1.0.0"
 
 google-closure-compiler-js@>20170000:
-  version "20170626.0.0"
-  resolved "https://registry.yarnpkg.com/google-closure-compiler-js/-/google-closure-compiler-js-20170626.0.0.tgz#5df265b277d1ec6fdea12eed131d1491cd8a8d71"
+  version "20170910.0.1"
+  resolved "https://registry.yarnpkg.com/@gaearon/google-closure-compiler-js/-/google-closure-compiler-js-20170910.0.1.tgz#b0cf7ef408219a19c390375a76bf0a82ccf65eea"
   dependencies:
     minimist "^1.2.0"
     vinyl "^2.0.1"
@@ -3208,6 +3215,18 @@ lru-cache@^4.0.1:
     pseudomap "^1.0.2"
     yallist "^2.1.2"
 
+magic-string@0.19.1:
+  version "0.19.1"
+  resolved "https://registry.yarnpkg.com/magic-string/-/magic-string-0.19.1.tgz#14d768013caf2ec8fdea16a49af82fc377e75201"
+  dependencies:
+    vlq "^0.2.1"
+
+magic-string@0.22.4, magic-string@^0.22.4:
+  version "0.22.4"
+  resolved "https://registry.yarnpkg.com/magic-string/-/magic-string-0.22.4.tgz#31039b4e40366395618c1d6cf8193c53917475ff"
+  dependencies:
+    vlq "^0.2.1"
+
 magic-string@^0.15.2:
   version "0.15.2"
   resolved "https://registry.yarnpkg.com/magic-string/-/magic-string-0.15.2.tgz#0681d7388741bbc3addaa65060992624c6c09e9c"
@@ -3220,12 +3239,6 @@ magic-string@^0.16.0:
   dependencies:
     vlq "^0.2.1"
 
-magic-string@^0.22.4:
-  version "0.22.4"
-  resolved "https://registry.yarnpkg.com/magic-string/-/magic-string-0.22.4.tgz#31039b4e40366395618c1d6cf8193c53917475ff"
-  dependencies:
-    vlq "^0.2.1"
-
 makeerror@1.0.x:
   version "1.0.11"
   resolved "https://registry.yarnpkg.com/makeerror/-/makeerror-1.0.11.tgz#e01a5c9109f2af79660e4e8b9587790184f5a96c"
@@ -3671,7 +3684,7 @@ preserve@^0.2.0:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/preserve/-/preserve-0.2.0.tgz#815ed1f6ebc65926f865b310c0713bcb3315ce4b"
 
-prettier@1.8.1:
+prettier@1.8.1, prettier@^1.0.0:
   version "1.8.1"
   resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.8.1.tgz#91064d778c08c85ac1cbe6b23195c34310d039f9"
 
@@ -4104,6 +4117,14 @@ rollup-plugin-node-resolve@^2.0.0:
     builtin-modules "^1.1.0"
     resolve "^1.1.6"
 
+rollup-plugin-prettier@^0.3.0:
+  version "0.3.0"
+  resolved "https://registry.yarnpkg.com/rollup-plugin-prettier/-/rollup-plugin-prettier-0.3.0.tgz#1000df8a2914d367b79507c1caa582fdbed8b0f3"
+  dependencies:
+    diff "3.3.0"
+    magic-string "0.22.4"
+    prettier "^1.0.0"
+
 rollup-plugin-replace@^1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/rollup-plugin-replace/-/rollup-plugin-replace-1.1.1.tgz#396315ded050a6ce43b9518a886a3f60efb1ea33"
@@ -4112,11 +4133,20 @@ rollup-plugin-replace@^1.1.1:
     minimatch "^3.0.2"
     rollup-pluginutils "^1.5.0"
 
-rollup-plugin-uglify@^1.0.1:
-  version "1.0.2"
-  resolved "https://registry.yarnpkg.com/rollup-plugin-uglify/-/rollup-plugin-uglify-1.0.2.tgz#d4aa6f5df13522eae1ba17780c7c4c7096038359"
+rollup-plugin-strip-banner@^0.2.0:
+  version "0.2.0"
+  resolved "https://registry.yarnpkg.com/rollup-plugin-strip-banner/-/rollup-plugin-strip-banner-0.2.0.tgz#d5c86979c7871427f9d7f797e09a493750769fd4"
   dependencies:
-    uglify-js "^2.6.1"
+    extract-banner "0.1.2"
+    magic-string "0.19.1"
+    rollup-pluginutils "2.0.1"
+
+rollup-pluginutils@2.0.1, rollup-pluginutils@^2.0.1:
+  version "2.0.1"
+  resolved "https://registry.yarnpkg.com/rollup-pluginutils/-/rollup-pluginutils-2.0.1.tgz#7ec95b3573f6543a46a6461bd9a7c544525d0fc0"
+  dependencies:
+    estree-walker "^0.3.0"
+    micromatch "^2.3.11"
 
 rollup-pluginutils@^1.2.0, rollup-pluginutils@^1.5.0:
   version "1.5.2"
@@ -4125,13 +4155,6 @@ rollup-pluginutils@^1.2.0, rollup-pluginutils@^1.5.0:
     estree-walker "^0.2.1"
     minimatch "^3.0.2"
 
-rollup-pluginutils@^2.0.1:
-  version "2.0.1"
-  resolved "https://registry.yarnpkg.com/rollup-pluginutils/-/rollup-pluginutils-2.0.1.tgz#7ec95b3573f6543a46a6461bd9a7c544525d0fc0"
-  dependencies:
-    estree-walker "^0.3.0"
-    micromatch "^2.3.11"
-
 rollup@^0.49.3:
   version "0.49.3"
   resolved "https://registry.yarnpkg.com/rollup/-/rollup-0.49.3.tgz#4cce32643dd8cf2154c69ff0e43470067db0adbf"
@@ -4399,6 +4422,10 @@ strip-ansi@^4.0.0:
   dependencies:
     ansi-regex "^3.0.0"
 
+strip-bom-string@^0.1.2:
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/strip-bom-string/-/strip-bom-string-0.1.2.tgz#9c6e720a313ba9836589518405ccfb88a5f41b9c"
+
 strip-bom@3.0.0, strip-bom@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/strip-bom/-/strip-bom-3.0.0.tgz#2334c18e9c759f7bdd56fdef7e9ae3d588e68ed3"
@@ -4417,6 +4444,10 @@ strip-json-comments@~2.0.1:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/strip-json-comments/-/strip-json-comments-2.0.1.tgz#3c531942e908c2697c0ec344858c286c7ca0a60a"
 
+strip-use-strict@^0.1.0:
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/strip-use-strict/-/strip-use-strict-0.1.0.tgz#e30e8fd2206834e41e5eb3f3dc1ea7a4e4258f5f"
+
 supports-color@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-2.0.0.tgz#535d045ce6b6363fa40117084629995e9df324c7"
@@ -4600,7 +4631,7 @@ ua-parser-js@^0.7.9:
   version "0.7.17"
   resolved "https://registry.yarnpkg.com/ua-parser-js/-/ua-parser-js-0.7.17.tgz#e9ec5f9498b9ec910e7ae3ac626a805c4d09ecac"
 
-uglify-js@^2.5.0, uglify-js@^2.6, uglify-js@^2.6.1:
+uglify-js@^2.6:
   version "2.8.22"
   resolved "https://registry.yarnpkg.com/uglify-js/-/uglify-js-2.8.22.tgz#d54934778a8da14903fa29a326fb24c0ab51a1a0"
   dependencies:

From 6840eab1a3130356eb45e247b64d2b747bfa5baf Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Wed, 8 Nov 2017 01:49:42 +0000
Subject: [PATCH 2/3] Record sizes

---
 scripts/rollup/results.json | 208 ++++++++++++++++++------------------
 1 file changed, 104 insertions(+), 104 deletions(-)

diff --git a/scripts/rollup/results.json b/scripts/rollup/results.json
index b357fd2a69638..0b851c074d138 100644
--- a/scripts/rollup/results.json
+++ b/scripts/rollup/results.json
@@ -1,212 +1,212 @@
 {
   "bundleSizes": {
     "react.development.js (UMD_DEV)": {
-      "size": 57647,
-      "gzip": 14957
+      "size": 54797,
+      "gzip": 14830
     },
     "react.production.min.js (UMD_PROD)": {
-      "size": 6676,
-      "gzip": 2774
+      "size": 6578,
+      "gzip": 2732
     },
     "react.development.js (NODE_DEV)": {
-      "size": 48028,
-      "gzip": 12662
+      "size": 45178,
+      "gzip": 12543
     },
     "react.production.min.js (NODE_PROD)": {
-      "size": 5475,
-      "gzip": 2351
+      "size": 5378,
+      "gzip": 2311
     },
     "React-dev.js (FB_DEV)": {
-      "size": 46073,
-      "gzip": 12047
+      "size": 45067,
+      "gzip": 12285
     },
     "React-prod.js (FB_PROD)": {
-      "size": 25976,
-      "gzip": 6831
+      "size": 12470,
+      "gzip": 3323
     },
     "react-dom.development.js (UMD_DEV)": {
-      "size": 587808,
-      "gzip": 133625
+      "size": 566430,
+      "gzip": 132064
     },
     "react-dom.production.min.js (UMD_PROD)": {
-      "size": 94541,
-      "gzip": 30614
+      "size": 94572,
+      "gzip": 30628
     },
     "react-dom.development.js (NODE_DEV)": {
-      "size": 568590,
-      "gzip": 128929
+      "size": 547412,
+      "gzip": 127147
     },
     "react-dom.production.min.js (NODE_PROD)": {
-      "size": 92717,
-      "gzip": 29846
+      "size": 92748,
+      "gzip": 29858
     },
     "ReactDOM-dev.js (FB_DEV)": {
-      "size": 572114,
-      "gzip": 130091
+      "size": 572910,
+      "gzip": 131679
     },
     "ReactDOM-prod.js (FB_PROD)": {
-      "size": 418963,
-      "gzip": 92847
+      "size": 270892,
+      "gzip": 51324
     },
     "react-dom-test-utils.development.js (NODE_DEV)": {
-      "size": 37878,
-      "gzip": 10319
+      "size": 35989,
+      "gzip": 10254
     },
     "react-dom-test-utils.production.min.js (NODE_PROD)": {
-      "size": 10173,
-      "gzip": 3834
+      "size": 10196,
+      "gzip": 3841
     },
     "ReactTestUtils-dev.js (FB_DEV)": {
-      "size": 37278,
-      "gzip": 10187
+      "size": 36706,
+      "gzip": 10335
     },
     "react-dom-unstable-native-dependencies.development.js (UMD_DEV)": {
-      "size": 66834,
-      "gzip": 16686
+      "size": 63441,
+      "gzip": 16548
     },
     "react-dom-unstable-native-dependencies.production.min.js (UMD_PROD)": {
-      "size": 11351,
-      "gzip": 3902
+      "size": 11374,
+      "gzip": 3909
     },
     "react-dom-unstable-native-dependencies.development.js (NODE_DEV)": {
-      "size": 62186,
-      "gzip": 15358
+      "size": 58984,
+      "gzip": 15263
     },
     "react-dom-unstable-native-dependencies.production.min.js (NODE_PROD)": {
-      "size": 10894,
-      "gzip": 3773
+      "size": 10917,
+      "gzip": 3779
     },
     "ReactDOMUnstableNativeDependencies-dev.js (FB_DEV)": {
-      "size": 61619,
-      "gzip": 15202
+      "size": 60056,
+      "gzip": 15408
     },
     "ReactDOMUnstableNativeDependencies-prod.js (FB_PROD)": {
-      "size": 52151,
-      "gzip": 12591
+      "size": 26611,
+      "gzip": 5328
     },
     "react-dom-server.browser.development.js (UMD_DEV)": {
-      "size": 101089,
-      "gzip": 26192
+      "size": 94236,
+      "gzip": 25347
     },
     "react-dom-server.browser.production.min.js (UMD_PROD)": {
-      "size": 14718,
-      "gzip": 5827
+      "size": 14741,
+      "gzip": 5836
     },
     "react-dom-server.browser.development.js (NODE_DEV)": {
-      "size": 89855,
-      "gzip": 23451
+      "size": 83193,
+      "gzip": 22547
     },
     "react-dom-server.browser.production.min.js (NODE_PROD)": {
-      "size": 14193,
-      "gzip": 5709
+      "size": 14216,
+      "gzip": 5715
     },
     "ReactDOMServer-dev.js (FB_DEV)": {
-      "size": 89282,
-      "gzip": 23287
+      "size": 86914,
+      "gzip": 22798
     },
     "ReactDOMServer-prod.js (FB_PROD)": {
-      "size": 45189,
-      "gzip": 11995
+      "size": 31383,
+      "gzip": 8115
     },
     "react-dom-server.node.development.js (NODE_DEV)": {
-      "size": 92021,
-      "gzip": 23959
+      "size": 85175,
+      "gzip": 23048
     },
     "react-dom-server.node.production.min.js (NODE_PROD)": {
-      "size": 15018,
-      "gzip": 6017
+      "size": 15041,
+      "gzip": 6023
     },
     "react-art.development.js (UMD_DEV)": {
-      "size": 361649,
-      "gzip": 79069
+      "size": 356117,
+      "gzip": 78805
     },
     "react-art.production.min.js (UMD_PROD)": {
-      "size": 83540,
-      "gzip": 25716
+      "size": 83551,
+      "gzip": 25721
     },
     "react-art.development.js (NODE_DEV)": {
-      "size": 285841,
-      "gzip": 60122
+      "size": 280509,
+      "gzip": 59801
     },
     "react-art.production.min.js (NODE_PROD)": {
-      "size": 47425,
-      "gzip": 14826
+      "size": 47448,
+      "gzip": 14833
     },
     "ReactART-dev.js (FB_DEV)": {
-      "size": 285290,
-      "gzip": 60273
+      "size": 291930,
+      "gzip": 61728
     },
     "ReactART-prod.js (FB_PROD)": {
-      "size": 223089,
-      "gzip": 45921
+      "size": 146917,
+      "gzip": 25076
     },
     "ReactNativeRenderer-dev.js (RN_DEV)": {
-      "size": 264179,
-      "gzip": 45201
+      "size": 410167,
+      "gzip": 89964
     },
     "ReactNativeRenderer-prod.js (RN_PROD)": {
-      "size": 212604,
-      "gzip": 36247
+      "size": 200641,
+      "gzip": 34583
     },
     "ReactRTRenderer-dev.js (RN_DEV)": {
-      "size": 195908,
-      "gzip": 32822
+      "size": 286373,
+      "gzip": 60712
     },
     "ReactRTRenderer-prod.js (RN_PROD)": {
-      "size": 153400,
-      "gzip": 25311
+      "size": 137995,
+      "gzip": 23152
     },
     "ReactCSRenderer-dev.js (RN_DEV)": {
-      "size": 189445,
-      "gzip": 31430
+      "size": 277226,
+      "gzip": 57865
     },
     "ReactCSRenderer-prod.js (RN_PROD)": {
-      "size": 149120,
-      "gzip": 24267
+      "size": 130882,
+      "gzip": 21854
     },
     "react-test-renderer.development.js (NODE_DEV)": {
-      "size": 284278,
-      "gzip": 59193
+      "size": 278466,
+      "gzip": 58909
     },
     "react-test-renderer.production.min.js (NODE_PROD)": {
-      "size": 46027,
-      "gzip": 14218
+      "size": 46050,
+      "gzip": 14225
     },
     "ReactTestRenderer-dev.js (FB_DEV)": {
-      "size": 283739,
-      "gzip": 59348
+      "size": 289988,
+      "gzip": 60842
     },
     "react-test-renderer-shallow.development.js (NODE_DEV)": {
-      "size": 10659,
-      "gzip": 2682
+      "size": 9691,
+      "gzip": 2634
     },
     "react-test-renderer-shallow.production.min.js (NODE_PROD)": {
-      "size": 4850,
-      "gzip": 1791
+      "size": 4873,
+      "gzip": 1801
     },
     "ReactShallowRenderer-dev.js (FB_DEV)": {
-      "size": 10154,
-      "gzip": 2521
+      "size": 9917,
+      "gzip": 2597
     },
     "react-noop-renderer.development.js (NODE_DEV)": {
-      "size": 280242,
-      "gzip": 58186
+      "size": 274982,
+      "gzip": 57892
     },
     "react-reconciler.development.js (NODE_DEV)": {
-      "size": 265017,
-      "gzip": 54727
+      "size": 260143,
+      "gzip": 54443
     },
     "react-reconciler.production.min.js (NODE_PROD)": {
-      "size": 39270,
-      "gzip": 12270
+      "size": 39445,
+      "gzip": 12258
     },
     "react-call-return.development.js (NODE_DEV)": {
-      "size": 3050,
-      "gzip": 980
+      "size": 2519,
+      "gzip": 928
     },
     "react-call-return.production.min.js (NODE_PROD)": {
-      "size": 875,
-      "gzip": 505
+      "size": 898,
+      "gzip": 512
     }
   }
 }
\ No newline at end of file

From 45a8b3fea023906450e075ec8cd361b9fe276f95 Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Wed, 8 Nov 2017 21:19:19 +0000
Subject: [PATCH 3/3] Refactor header and footer wrapping

It is easier to understand if we just explicitly type them out.
---
 scripts/circleci/check_modules.sh |   2 +-
 scripts/rollup/build.js           | 118 ++----------------
 scripts/rollup/header.js          |  32 -----
 scripts/rollup/results.json       | 162 ++++++++++++------------
 scripts/rollup/wrappers.js        | 199 ++++++++++++++++++++++++++++++
 5 files changed, 289 insertions(+), 224 deletions(-)
 delete mode 100644 scripts/rollup/header.js
 create mode 100644 scripts/rollup/wrappers.js

diff --git a/scripts/circleci/check_modules.sh b/scripts/circleci/check_modules.sh
index b71b4cd616d2d..8ecd67dfbbee3 100755
--- a/scripts/circleci/check_modules.sh
+++ b/scripts/circleci/check_modules.sh
@@ -5,7 +5,7 @@ set -e
 # Make sure we don't introduce accidental @providesModule annotations.
 EXPECTED='packages/react-cs-renderer/src/ReactNativeCSTypes.js
 packages/react-native-renderer/src/ReactNativeTypes.js
-scripts/rollup/header.js'
+scripts/rollup/wrappers.js'
 ACTUAL=$(git grep -l @providesModule -- './*.js' ':!scripts/rollup/shims/*.js')
 
 if [ "$EXPECTED" != "$ACTUAL" ]; then
diff --git a/scripts/rollup/build.js b/scripts/rollup/build.js
index 47bcbaaa0226c..a842086209de1 100644
--- a/scripts/rollup/build.js
+++ b/scripts/rollup/build.js
@@ -25,7 +25,7 @@ const syncReactNative = require('./sync').syncReactNative;
 const syncReactNativeRT = require('./sync').syncReactNativeRT;
 const syncReactNativeCS = require('./sync').syncReactNativeCS;
 const Packaging = require('./packaging');
-const Header = require('./header');
+const Wrappers = require('./wrappers');
 
 const UMD_DEV = Bundles.bundleTypes.UMD_DEV;
 const UMD_PROD = Bundles.bundleTypes.UMD_PROD;
@@ -36,9 +36,6 @@ const FB_PROD = Bundles.bundleTypes.FB_PROD;
 const RN_DEV = Bundles.bundleTypes.RN_DEV;
 const RN_PROD = Bundles.bundleTypes.RN_PROD;
 
-const RECONCILER = Bundles.moduleTypes.RECONCILER;
-
-const reactVersion = require('../../package.json').version;
 const requestedBundleTypes = (argv.type || '')
   .split(',')
   .map(type => type.toUpperCase());
@@ -63,109 +60,6 @@ const closureOptions = {
   processCommonJsModules: false,
 };
 
-function getBanner(bundleType, globalName, filename, moduleType) {
-  if (moduleType === RECONCILER) {
-    // Standalone reconciler is only used by third-party renderers.
-    // It is handled separately.
-    return getReconcilerBanner(bundleType, filename);
-  }
-
-  switch (bundleType) {
-    // UMDs are not wrapped in conditions.
-    case UMD_DEV:
-    case UMD_PROD:
-      return Header.getHeader(filename, reactVersion);
-    // CommonJS DEV bundle is guarded to help weak dead code elimination.
-    case NODE_DEV:
-      let banner = Header.getHeader(filename, reactVersion);
-      // Wrap the contents of the if-DEV check with an IIFE.
-      // Block-level function definitions can cause problems for strict mode.
-      banner += `'use strict';\n\n\nif (process.env.NODE_ENV !== "production") {\n(function() {\n`;
-      return banner;
-    case NODE_PROD:
-      return Header.getHeader(filename, reactVersion);
-    // All FB and RN bundles need Haste headers.
-    // DEV bundle is guarded to help weak dead code elimination.
-    case FB_DEV:
-    case FB_PROD:
-    case RN_DEV:
-    case RN_PROD:
-      const isDev = bundleType === FB_DEV || bundleType === RN_DEV;
-      const hasteFinalName = globalName + (isDev ? '-dev' : '-prod');
-      // Wrap the contents of the if-DEV check with an IIFE.
-      // Block-level function definitions can cause problems for strict mode.
-      return (
-        Header.getProvidesHeader(hasteFinalName) +
-        (isDev ? `\n\n'use strict';\n\n\nif (__DEV__) {\n(function() {\n` : '')
-      );
-    default:
-      throw new Error('Unknown type.');
-  }
-}
-
-function getFooter(bundleType, filename, moduleType) {
-  if (moduleType === RECONCILER) {
-    // Standalone reconciler is only used by third-party renderers.
-    // It is handled separately.
-    return getReconcilerFooter(bundleType);
-  }
-
-  // Only need a footer if getBanner() has an opening brace.
-  switch (bundleType) {
-    // Non-UMD DEV bundles need conditions to help weak dead code elimination.
-    case NODE_DEV:
-    case FB_DEV:
-    case RN_DEV:
-      return '\n})();\n}\n';
-    default:
-      return '';
-  }
-}
-
-// TODO: this is extremely gross.
-// But it only affects the "experimental" standalone reconciler build.
-// The goal is to avoid having any shared state between renderers sharing it on npm.
-// Ideally we should just remove shared state in all Fiber modules and then lint against it.
-// But for now, we store the exported function in a variable, and then put the rest of the code
-// into a closure that makes all module-level state private to each call.
-const RECONCILER_WRAPPER_INTRO = `var $$$reconciler;\nmodule.exports = function(config) {\n`;
-const RECONCILER_WRAPPER_OUTRO = `return ($$$reconciler || ($$$reconciler = module.exports))(config);\n};\n`;
-
-function getReconcilerBanner(bundleType, filename) {
-  let banner = `${Header.getHeader(
-    filename,
-    reactVersion
-  )}\n\n'use strict';\n\n\n`;
-  switch (bundleType) {
-    case NODE_DEV:
-      banner += `if (process.env.NODE_ENV !== "production") {\n${
-        RECONCILER_WRAPPER_INTRO
-      }`;
-      break;
-    case NODE_PROD:
-      banner += RECONCILER_WRAPPER_INTRO;
-      break;
-    default:
-      throw new Error(
-        'Standalone reconciler does not support ' + bundleType + ' builds.'
-      );
-  }
-  return banner;
-}
-
-function getReconcilerFooter(bundleType) {
-  switch (bundleType) {
-    case NODE_DEV:
-      return `\n${RECONCILER_WRAPPER_OUTRO}\n}`;
-    case NODE_PROD:
-      return `\n${RECONCILER_WRAPPER_OUTRO}`;
-    default:
-      throw new Error(
-        'Standalone reconciler does not support ' + bundleType + ' builds.'
-      );
-  }
-}
-
 function getBabelConfig(updateBabelOptions, bundleType, filename) {
   let options = {
     exclude: 'node_modules/**',
@@ -393,9 +287,13 @@ function getPlugins(
     // License and haste headers, top-level `if` blocks.
     {
       transformBundle(source) {
-        const banner = getBanner(bundleType, globalName, filename, moduleType);
-        const footer = getFooter(bundleType, filename, moduleType);
-        return banner + '\n' + source + '\n' + footer;
+        return Wrappers.wrapBundle(
+          source,
+          bundleType,
+          globalName,
+          filename,
+          moduleType
+        );
       },
     },
     // Record bundle size.
diff --git a/scripts/rollup/header.js b/scripts/rollup/header.js
deleted file mode 100644
index 0a931b3a48e83..0000000000000
--- a/scripts/rollup/header.js
+++ /dev/null
@@ -1,32 +0,0 @@
-'use strict';
-
-function getProvidesHeader(hasteFinalName) {
-  return `/**
- * Copyright (c) 2013-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.
- *
- * @noflow
- * @providesModule ${hasteFinalName}
- * @preventMunge
- */
-`;
-}
-
-function getHeader(filename, reactVersion) {
-  return `/** @license React v${reactVersion}
- * ${filename}
- *
- * Copyright (c) 2013-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.
- */
-`;
-}
-
-module.exports = {
-  getProvidesHeader,
-  getHeader,
-};
diff --git a/scripts/rollup/results.json b/scripts/rollup/results.json
index 0b851c074d138..e7f9cfe39522b 100644
--- a/scripts/rollup/results.json
+++ b/scripts/rollup/results.json
@@ -1,175 +1,175 @@
 {
   "bundleSizes": {
     "react.development.js (UMD_DEV)": {
-      "size": 54797,
-      "gzip": 14830
+      "size": 54812,
+      "gzip": 14834
     },
     "react.production.min.js (UMD_PROD)": {
-      "size": 6578,
-      "gzip": 2732
+      "size": 6577,
+      "gzip": 2731
     },
     "react.development.js (NODE_DEV)": {
-      "size": 45178,
-      "gzip": 12543
+      "size": 45180,
+      "gzip": 12540
     },
     "react.production.min.js (NODE_PROD)": {
-      "size": 5378,
-      "gzip": 2311
+      "size": 5377,
+      "gzip": 2310
     },
     "React-dev.js (FB_DEV)": {
       "size": 45067,
-      "gzip": 12285
+      "gzip": 12284
     },
     "React-prod.js (FB_PROD)": {
-      "size": 12470,
-      "gzip": 3323
+      "size": 12469,
+      "gzip": 3322
     },
     "react-dom.development.js (UMD_DEV)": {
-      "size": 566430,
-      "gzip": 132064
+      "size": 566445,
+      "gzip": 132067
     },
     "react-dom.production.min.js (UMD_PROD)": {
-      "size": 94572,
+      "size": 94571,
       "gzip": 30628
     },
     "react-dom.development.js (NODE_DEV)": {
-      "size": 547412,
-      "gzip": 127147
+      "size": 547414,
+      "gzip": 127145
     },
     "react-dom.production.min.js (NODE_PROD)": {
-      "size": 92748,
-      "gzip": 29858
+      "size": 92747,
+      "gzip": 29857
     },
     "ReactDOM-dev.js (FB_DEV)": {
       "size": 572910,
       "gzip": 131679
     },
     "ReactDOM-prod.js (FB_PROD)": {
-      "size": 270892,
-      "gzip": 51324
+      "size": 270891,
+      "gzip": 51323
     },
     "react-dom-test-utils.development.js (NODE_DEV)": {
-      "size": 35989,
-      "gzip": 10254
+      "size": 35991,
+      "gzip": 10251
     },
     "react-dom-test-utils.production.min.js (NODE_PROD)": {
-      "size": 10196,
-      "gzip": 3841
+      "size": 10195,
+      "gzip": 3840
     },
     "ReactTestUtils-dev.js (FB_DEV)": {
       "size": 36706,
       "gzip": 10335
     },
     "react-dom-unstable-native-dependencies.development.js (UMD_DEV)": {
-      "size": 63441,
-      "gzip": 16548
+      "size": 63456,
+      "gzip": 16551
     },
     "react-dom-unstable-native-dependencies.production.min.js (UMD_PROD)": {
-      "size": 11374,
-      "gzip": 3909
+      "size": 11373,
+      "gzip": 3908
     },
     "react-dom-unstable-native-dependencies.development.js (NODE_DEV)": {
-      "size": 58984,
-      "gzip": 15263
+      "size": 58986,
+      "gzip": 15262
     },
     "react-dom-unstable-native-dependencies.production.min.js (NODE_PROD)": {
-      "size": 10917,
-      "gzip": 3779
+      "size": 10916,
+      "gzip": 3778
     },
     "ReactDOMUnstableNativeDependencies-dev.js (FB_DEV)": {
       "size": 60056,
-      "gzip": 15408
+      "gzip": 15406
     },
     "ReactDOMUnstableNativeDependencies-prod.js (FB_PROD)": {
-      "size": 26611,
-      "gzip": 5328
+      "size": 26610,
+      "gzip": 5327
     },
     "react-dom-server.browser.development.js (UMD_DEV)": {
-      "size": 94236,
-      "gzip": 25347
+      "size": 94251,
+      "gzip": 25351
     },
     "react-dom-server.browser.production.min.js (UMD_PROD)": {
-      "size": 14741,
-      "gzip": 5836
+      "size": 14740,
+      "gzip": 5834
     },
     "react-dom-server.browser.development.js (NODE_DEV)": {
-      "size": 83193,
-      "gzip": 22547
+      "size": 83195,
+      "gzip": 22545
     },
     "react-dom-server.browser.production.min.js (NODE_PROD)": {
-      "size": 14216,
-      "gzip": 5715
+      "size": 14215,
+      "gzip": 5714
     },
     "ReactDOMServer-dev.js (FB_DEV)": {
       "size": 86914,
-      "gzip": 22798
+      "gzip": 22797
     },
     "ReactDOMServer-prod.js (FB_PROD)": {
-      "size": 31383,
-      "gzip": 8115
+      "size": 31382,
+      "gzip": 8114
     },
     "react-dom-server.node.development.js (NODE_DEV)": {
-      "size": 85175,
-      "gzip": 23048
+      "size": 85177,
+      "gzip": 23046
     },
     "react-dom-server.node.production.min.js (NODE_PROD)": {
-      "size": 15041,
-      "gzip": 6023
+      "size": 15040,
+      "gzip": 6022
     },
     "react-art.development.js (UMD_DEV)": {
-      "size": 356117,
-      "gzip": 78805
+      "size": 356132,
+      "gzip": 78808
     },
     "react-art.production.min.js (UMD_PROD)": {
-      "size": 83551,
-      "gzip": 25721
+      "size": 83550,
+      "gzip": 25720
     },
     "react-art.development.js (NODE_DEV)": {
-      "size": 280509,
-      "gzip": 59801
+      "size": 280511,
+      "gzip": 59802
     },
     "react-art.production.min.js (NODE_PROD)": {
-      "size": 47448,
+      "size": 47447,
       "gzip": 14833
     },
     "ReactART-dev.js (FB_DEV)": {
       "size": 291930,
-      "gzip": 61728
+      "gzip": 61727
     },
     "ReactART-prod.js (FB_PROD)": {
-      "size": 146917,
+      "size": 146916,
       "gzip": 25076
     },
     "ReactNativeRenderer-dev.js (RN_DEV)": {
       "size": 410167,
-      "gzip": 89964
+      "gzip": 89963
     },
     "ReactNativeRenderer-prod.js (RN_PROD)": {
-      "size": 200641,
-      "gzip": 34583
+      "size": 200640,
+      "gzip": 34582
     },
     "ReactRTRenderer-dev.js (RN_DEV)": {
       "size": 286373,
       "gzip": 60712
     },
     "ReactRTRenderer-prod.js (RN_PROD)": {
-      "size": 137995,
-      "gzip": 23152
+      "size": 137994,
+      "gzip": 23151
     },
     "ReactCSRenderer-dev.js (RN_DEV)": {
       "size": 277226,
-      "gzip": 57865
+      "gzip": 57864
     },
     "ReactCSRenderer-prod.js (RN_PROD)": {
-      "size": 130882,
-      "gzip": 21854
+      "size": 130881,
+      "gzip": 21853
     },
     "react-test-renderer.development.js (NODE_DEV)": {
-      "size": 278466,
+      "size": 278468,
       "gzip": 58909
     },
     "react-test-renderer.production.min.js (NODE_PROD)": {
-      "size": 46050,
+      "size": 46049,
       "gzip": 14225
     },
     "ReactTestRenderer-dev.js (FB_DEV)": {
@@ -177,35 +177,35 @@
       "gzip": 60842
     },
     "react-test-renderer-shallow.development.js (NODE_DEV)": {
-      "size": 9691,
+      "size": 9693,
       "gzip": 2634
     },
     "react-test-renderer-shallow.production.min.js (NODE_PROD)": {
-      "size": 4873,
-      "gzip": 1801
+      "size": 4872,
+      "gzip": 1800
     },
     "ReactShallowRenderer-dev.js (FB_DEV)": {
       "size": 9917,
-      "gzip": 2597
+      "gzip": 2596
     },
     "react-noop-renderer.development.js (NODE_DEV)": {
-      "size": 274982,
+      "size": 274984,
       "gzip": 57892
     },
     "react-reconciler.development.js (NODE_DEV)": {
-      "size": 260143,
-      "gzip": 54443
+      "size": 260419,
+      "gzip": 54546
     },
     "react-reconciler.production.min.js (NODE_PROD)": {
-      "size": 39445,
-      "gzip": 12258
+      "size": 39408,
+      "gzip": 12244
     },
     "react-call-return.development.js (NODE_DEV)": {
-      "size": 2519,
-      "gzip": 928
+      "size": 2521,
+      "gzip": 929
     },
     "react-call-return.production.min.js (NODE_PROD)": {
-      "size": 898,
+      "size": 897,
       "gzip": 512
     }
   }
diff --git a/scripts/rollup/wrappers.js b/scripts/rollup/wrappers.js
new file mode 100644
index 0000000000000..0f14bcbf558f6
--- /dev/null
+++ b/scripts/rollup/wrappers.js
@@ -0,0 +1,199 @@
+'use strict';
+
+const Bundles = require('./bundles');
+const reactVersion = require('../../package.json').version;
+
+const UMD_DEV = Bundles.bundleTypes.UMD_DEV;
+const UMD_PROD = Bundles.bundleTypes.UMD_PROD;
+const NODE_DEV = Bundles.bundleTypes.NODE_DEV;
+const NODE_PROD = Bundles.bundleTypes.NODE_PROD;
+const FB_DEV = Bundles.bundleTypes.FB_DEV;
+const FB_PROD = Bundles.bundleTypes.FB_PROD;
+const RN_DEV = Bundles.bundleTypes.RN_DEV;
+const RN_PROD = Bundles.bundleTypes.RN_PROD;
+
+const RECONCILER = Bundles.moduleTypes.RECONCILER;
+
+const license = ` * Copyright (c) 2013-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.`;
+
+const wrappers = {
+  /***************** UMD_DEV *****************/
+  [UMD_DEV](source, globalName, filename, moduleType) {
+    return `/** @license React v${reactVersion}
+ * ${filename}
+ *
+${license}
+ */
+
+'use strict';
+
+${source}`;
+  },
+
+  /***************** UMD_PROD *****************/
+  [UMD_PROD](source, globalName, filename, moduleType) {
+    return `/** @license React v${reactVersion}
+ * ${filename}
+ *
+${license}
+ */
+${source}`;
+  },
+
+  /***************** NODE_DEV *****************/
+  [NODE_DEV](source, globalName, filename, moduleType) {
+    return `/** @license React v${reactVersion}
+ * ${filename}
+ *
+${license}
+ */
+
+'use strict';
+
+if (process.env.NODE_ENV !== "production") {
+  (function() {
+${source}
+  })();
+}`;
+  },
+
+  /***************** NODE_PROD *****************/
+  [NODE_PROD](source, globalName, filename, moduleType) {
+    return `/** @license React v${reactVersion}
+ * ${filename}
+ *
+${license}
+ */
+${source}`;
+  },
+
+  /****************** FB_DEV ******************/
+  [FB_DEV](source, globalName, filename, moduleType) {
+    return `/**
+${license}
+ *
+ * @noflow
+ * @providesModule ${globalName}-dev
+ * @preventMunge
+ */
+
+'use strict';
+
+if (__DEV__) {
+  (function() {
+${source}
+  })();
+}`;
+  },
+
+  /****************** FB_PROD ******************/
+  [FB_PROD](source, globalName, filename, moduleType) {
+    return `/**
+${license}
+ *
+ * @noflow
+ * @providesModule ${globalName}-prod
+ * @preventMunge
+ */
+
+${source}`;
+  },
+
+  /****************** RN_DEV ******************/
+  [RN_DEV](source, globalName, filename, moduleType) {
+    return `/**
+${license}
+ *
+ * @noflow
+ * @providesModule ${globalName}-dev
+ * @preventMunge
+ */
+
+'use strict';
+
+if (__DEV__) {
+  (function() {
+${source}
+  })();
+}`;
+  },
+
+  /****************** RN_DEV ******************/
+  [RN_PROD](source, globalName, filename, moduleType) {
+    return `/**
+${license}
+ *
+ * @noflow
+ * @providesModule ${globalName}-prod
+ * @preventMunge
+ */
+
+${source}`;
+  },
+};
+
+const reconcilerWrappers = {
+  /***************** NODE_DEV (reconciler only) *****************/
+  [NODE_DEV](source, globalName, filename, moduleType) {
+    return `/** @license React v${reactVersion}
+ * ${filename}
+ *
+${license}
+ */
+
+'use strict';
+
+if (process.env.NODE_ENV !== "production") {
+  // This is a hacky way to ensure third party renderers don't share
+  // top-level module state inside the reconciler. Ideally we should
+  // remove this hack by putting all top-level state into the closures
+  // and then forbidding adding more of it in the reconciler.
+  var $$$reconciler;
+  module.exports = function(config) {
+${source}
+    return ($$$reconciler || ($$$reconciler = module.exports))(config);
+  };
+}`;
+  },
+
+  /***************** NODE_PROD (reconciler only) *****************/
+  [NODE_PROD](source, globalName, filename, moduleType) {
+    return `/** @license React v${reactVersion}
+ * ${filename}
+ *
+${license}
+ */
+var $$$reconciler;
+module.exports = function(config) {
+${source}
+  return ($$$reconciler || ($$$reconciler = module.exports))(config);
+};`;
+  },
+};
+
+function wrapBundle(source, bundleType, globalName, filename, moduleType) {
+  if (moduleType === RECONCILER) {
+    // Standalone reconciler is only used by third-party renderers.
+    // It is handled separately.
+    const wrapper = reconcilerWrappers[bundleType];
+    if (typeof wrapper !== 'function') {
+      throw new Error(
+        `Unsupported build type for the reconciler package: ${bundleType}.`
+      );
+    }
+    return wrapper(source, globalName, filename, moduleType);
+  }
+  // All the other packages.
+  const wrapper = wrappers[bundleType];
+  if (typeof wrapper !== 'function') {
+    throw new Error(`Unsupported build type: ${bundleType}.`);
+  }
+  return wrapper(source, globalName, filename, moduleType);
+}
+
+module.exports = {
+  wrapBundle,
+};