Add unbundling to packager

Reviewed By: tadeuzagallo

Differential Revision: D2707409

fb-gh-sync-id: 30216c36066dae68d83622dba2d598e9dc0a29db

local-cli/bundle/output/bundle.js

@@ -33,7 +33,7 @@ function saveBundleAndMap(bundle, options, log) {
     'bundle-encoding': encoding,
     dev,
     'sourcemap-output': sourcemapOutput,
-} = options;
+  } = options;
 
   log('start');
   const codeWithMap = createCodeWithMap(bundle, dev);

local-cli/bundle/output/unbundle.js

@@ -0,0 +1,126 @@
+/**
+ * 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.
+ */
+'use strict';
+
+const fs = require('fs');
+const Promise = require('promise');
+const writeFile = require('./writeFile');
+
+const MAGIC_STARTUP_MODULE_ID = '';
+
+function buildBundle(packagerClient, requestOptions) {
+  return packagerClient.buildBundle({...requestOptions, unbundle: true});
+}
+
+function saveUnbundle(bundle, options, log) {
+  const {
+    'bundle-output': bundleOutput,
+    'bundle-encoding': encoding,
+    dev,
+    'sourcemap-output': sourcemapOutput,
+  } = options;
+
+  log('start');
+  const {startupCode, modules} = bundle.getUnbundle({minify: !dev});
+  log('finish');
+
+  log('Writing unbundle output to:', bundleOutput);
+  const writeUnbundle = writeBuffers(
+    fs.createWriteStream(bundleOutput),
+    buildTableAndContents(startupCode, modules, encoding)
+  );
+
+  writeUnbundle.then(() => log('Done writing unbundle output'));
+
+  if (sourcemapOutput) {
+    log('Writing sourcemap output to:', sourcemapOutput);
+    const writeMap = writeFile(sourcemapOutput, '', null);
+    writeMap.then(() => log('Done writing sourcemap output'));
+    return Promise.all([writeUnbundle, writeMap]);
+  } else {
+    return writeUnbundle;
+  }
+}
+
+/* global Buffer: true */
+const nullByteBuffer = Buffer(1).fill(0);
+
+const moduleToBuffer = ({name, code}, encoding) => ({
+  name,
+  buffer: Buffer.concat([
+    Buffer(code, encoding),
+    nullByteBuffer // create \0-terminated strings
+  ])
+});
+
+function buildModuleBuffers(startupCode, modules, encoding) {
+  return (
+    [moduleToBuffer({name: '', code: startupCode}, encoding)]
+      .concat(modules.map(module => moduleToBuffer(module, encoding)))
+  );
+}
+
+function uInt32Buffer(n) {
+  const buffer = Buffer(4);
+  buffer.writeUInt32LE(n, 0); // let's assume LE for now :)
+  return buffer;
+}
+
+function buildModuleTable(buffers) {
+  // table format:
+  //  - table_length: uint_32 length of all table entries in bytes
+  //  - entries: entry...
+  //
+  // entry:
+  //  - module_id: NUL terminated utf8 string
+  //  - module_offset: uint_32 offset into the module string
+  //  - module_length: uint_32 length of the module string, including terminating NUL byte
+
+  const numBuffers = buffers.length;
+
+  const tableLengthBuffer = uInt32Buffer(0);
+  let tableLength = 4; // the table length itself, 4 == tableLengthBuffer.length
+  let currentOffset = 0;
+
+  const offsetTable = [tableLengthBuffer];
+  for (let i = 0; i < numBuffers; i++) {
+    const {name, buffer: {length}} = buffers[i];
+    const entry = Buffer.concat([
+      Buffer(i === 0 ? MAGIC_STARTUP_MODULE_ID : name, 'utf8'),
+      nullByteBuffer,
+      uInt32Buffer(currentOffset),
+      uInt32Buffer(length)
+    ]);
+    currentOffset += length;
+    tableLength += entry.length;
+    offsetTable.push(entry);
+  }
+
+  tableLengthBuffer.writeUInt32LE(tableLength, 0);
+  return Buffer.concat(offsetTable);
+}
+
+function buildTableAndContents(startupCode, modules, encoding) {
+  const buffers = buildModuleBuffers(startupCode, modules, encoding);
+  const table = buildModuleTable(buffers, encoding);
+  return [table].concat(buffers.map(({buffer}) => buffer));
+}
+
+function writeBuffers(stream, buffers) {
+  buffers.forEach(buffer => stream.write(buffer));
+  return new Promise((resolve, reject) => {
+    stream.on('error', reject);
+    stream.on('finish', () => resolve());
+    stream.end();
+  });
+}
+
+exports.build = buildBundle;
+exports.save = saveUnbundle;
+exports.formatName = 'bundle';