v1.12.3

Update logo on README

.gitignore

@@ -4,5 +4,9 @@ test/tmp
 *.log
 *.cache
 /templates.json
+/tests.json
+/browser.js
+/browser-polyfill.js
+/runtime.js
 coverage
 dist

.jshintrc

@@ -17,5 +17,13 @@
   "loopfunc": true,
   "white": true,
   "maxparams": 5,
-  "maxdepth": 4
+  "maxdepth": 4,
+
+  "globals": {
+    "window": true,
+    "suite": true,
+    "set": true,
+    "before": true,
+    "bench": true
+  }
 }

.npmignore

@@ -7,4 +7,5 @@ benchmark
 Makefile
 .*
 dist
+tests.json
 !README.md

.travis.yml

@@ -3,10 +3,17 @@ node_js:
   - "0.10"
   - "0.11"
 
+branches:
+  except:
+   - experimental
+
 before_script: "npm install -g codeclimate-test-reporter"
 script: "make test-travis"
 
-addons:
-  code_climate:
-    repo_token:
-      secure: "PfP9sDUJzSznDb+ZEPO2cignXabSTXJxEVm5ESRPgEcFr+/4b0pt3hI8R9b+9mLtBEwtw3DLUq48MOeqEKnq29csQmpjPVcN6gT4uR2DdNa1JpVgDuwxT05NB3fBea9U2reM73iV8ylCgPHExr2uGR9/87JzR2beY/56EUL5NjY="
+notifications:
+  webhooks:
+    urls:
+      - https://webhooks.gitter.im/e/acf1870e9d223c65e8d5
+    on_success: always
+    on_failure: always
+    on_start: false

CHANGELOG.md

@@ -0,0 +1,34 @@
+# 1.12.3
+
+ * Support generator comprehensions.
+ * Use `Array.from` instead of `Array.prototype.slice` in spread transformer.
+ * Support spread in `NewExpression`s.
+
+# 1.12.2
+
+ * Upgrade `matcha` to `0.6.0` and `browserify` to `6.3.2`.
+ * Add own `trimRight` helper instead of relying on the string instance method.
+ * Support JSX spreads that aren't the first.
+
+# 1.12.1
+
+ * Fix `this` and `arguments` mapping in the `_aliasFunctions` transformer.
+
+# 1.12.0
+
+ * Combine `jsx` and `react` transformers to `react`.
+ * Update `react` syntax output to React v0.12.
+
+# 1.11.15
+
+ * Fix JSX literal whitespace generation.
+
+# 1.11.14
+
+ * Avoid using a switch for let-scoping continue and break statements and use an if statement instead.
+ * Remove excess whitespace and newlines from JSX literals.
+
+# 1.11.13
+
+ * Update regenerator-6to5
+ * Add support for most escodegen formatting options

FEATURES.md

@@ -6,6 +6,16 @@
 [for (i of [1, 2, 3]) i * i]; // [1, 4, 9]
 ```
 
+## Async functions
+
+```javascript
+async function chainAnimationsAsync(elem, animations) {
+  for (var anim of animations) {
+    await anim(elem);
+  }
+}
+```
+
 ## Arrow functions
 
 ```javascript
@@ -85,6 +95,11 @@ for (var i of [1, 2, 3]) {
 ```javascript
 ```
 
+## Generator comprehension
+
+```javascript
+```
+
 ## Modules
 
 ```javascript

MODULES.md

@@ -109,10 +109,35 @@ export function bar() {
 });
 ```
 
+### Ignore
+
+
+**In**
+
+```javascript
+import foo from "foo";
+
+export function bar() {
+  return foo("foobar");
+}
+```
+
+**Out**
+
+```javascript
+function bar() {
+  return foo("foobar");
+}
+```
+
 ## Custom
 
 You can alternatively specify module names instead of one of the built-in types.
 
+    $ 6to5 --modules custom-module-formatter
+
+**node_modules/custom-module-formatter/index.js**
+
 ```javascript
 module.exports = ModuleFormatter;
 

Makefile

@@ -1,10 +1,12 @@
+BROWSERIFY_CMD = node_modules/browserify/bin/cmd.js
 ISTANBUL_CMD = node_modules/istanbul/lib/cli.js cover
+UGLIFY_CMD = node_modules/uglify-js/bin/uglifyjs
 JSHINT_CMD = node_modules/jshint/bin/jshint
 MOCHA_CMD = node_modules/mocha/bin/_mocha
 
 export NODE_ENV = test
 
-.PHONY: clean test test-cov test-travis test-browser publish bench build
+.PHONY: clean test test-cov test-clean lint test-travis test-spec test-browser publish bench build
 
 clean:
 	rm -rf coverage templates.json test/tmp dist
@@ -13,21 +15,36 @@ bench:
 	npm install es6-transpiler traceur esnext es6now jstransform
 	node node_modules/matcha/bin/_matcha
 
+lint:
+	$(JSHINT_CMD) lib bin benchmark/index.js
+
+test-clean:
+	rm -rf test/tmp
+
 test:
-	$(JSHINT_CMD) lib
+	make lint
 	$(MOCHA_CMD)
+	make test-clean
 
 test-cov:
 	rm -rf coverage
 	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
 
-test-travis:
+test-spec:
 	node $(ISTANBUL_CMD) $(MOCHA_CMD) -- --reporter spec
+
+test-travis:
+	make test-spec
 	if test -n "$$CODECLIMATE_REPO_TOKEN"; then codeclimate < coverage/lcov.info; fi
 
 test-browser:
-	make build
-	node bin/generate-browser-test >dist/6to5-test.js
+	mkdir -p dist
+
+	node bin/cache-templates
+	node bin/cache-tests
+	node $(BROWSERIFY_CMD) -e test/_browser.js >dist/6to5-test.js
+	rm -rf templates.json tests.json
+
 	test -n "`which open`" && open test/browser.html
 
 build:
@@ -35,8 +52,14 @@ build:
 
 	node bin/cache-templates
 
-	browserify lib/6to5/browser.js -s to5 >dist/6to5.js
-	uglifyjs dist/6to5.js >dist/6to5.min.js
+	node $(BROWSERIFY_CMD) -e lib/6to5/polyfill.js >dist/polyfill.js
+	node $(UGLIFY_CMD) dist/polyfill.js >dist/polyfill.min.js
+
+	node $(BROWSERIFY_CMD) lib/6to5/browser.js -s to5 >dist/6to5.js
+	node $(UGLIFY_CMD) dist/6to5.js >dist/6to5.min.js
+
+	node bin/6to5-runtime >dist/runtime.js
+	node $(UGLIFY_CMD) dist/runtime.js >dist/runtime.min.js
 
 	rm -rf templates.json
 
@@ -45,16 +68,18 @@ publish:
 
 	make test
 
+	make build
+	cp dist/6to5.min.js browser.js
+	cp dist/polyfill.min.js browser-polyfill.js
+	cp dist/runtime.min.js runtime.js
+
 	node bin/cache-templates
 	test -f templates.json
 
-	make build
-	cp dist/6to5.js browser.js
-
 	read -p "Version: "  version; \
   npm version $$version --message "v%s"
 	npm publish
 
 	git push --follow-tags
 
-	rm -rf templates.json
+	rm -rf templates.json browser.js runtime.js browser-polyfill.js

README.md

@@ -1,22 +1,26 @@
 <p align="center">
-  <img alt="6to5" src="http://i.imgur.com/hVl9KRw.png">
+  <img alt="6to5" src="https://raw.githubusercontent.com/6to5/logo/master/logo.png" width="546">
 </p>
 
 <p align="center">
-  <a href="https://travis-ci.org/sebmck/6to5">
-    <img alt="Travis Status" src="http://img.shields.io/travis/sebmck/6to5.svg?style=flat&amp;label=travis">
+  <a href="https://travis-ci.org/6to5/6to5">
+    <img alt="Travis Status" src="http://img.shields.io/travis/6to5/6to5.svg?branch=master&amp;style=flat&amp;label=travis">
   </a>
 
-  <a href="https://codeclimate.com/github/sebmck/6to5">
-    <img alt="Code Climate Score" src="http://img.shields.io/codeclimate/github/sebmck/6to5.svg?style=flat">
+  <a href="https://ci.appveyor.com/project/sebmck/6to5">
+    <img alt="Appveyor Status" src="http://img.shields.io/appveyor/ci/sebmck/6to5.svg?style=flat&amp;label=appveyor">
   </a>
 
-  <a href="https://codeclimate.com/github/sebmck/6to5">
-    <img alt="Coverage" src="http://img.shields.io/codeclimate/coverage/github/sebmck/6to5.svg?style=flat">
+  <a href="https://codeclimate.com/github/6to5/6to5">
+    <img alt="Code Climate Score" src="http://img.shields.io/codeclimate/github/6to5/6to5.svg?style=flat">
   </a>
 
-  <a href="https://david-dm.org/sebmck/6to5">
-    <img alt="Dependency Status" src="http://img.shields.io/david/sebmck/6to5.svg?style=flat">
+  <a href="https://codeclimate.com/github/6to5/6to5">
+    <img alt="Coverage" src="http://img.shields.io/codeclimate/coverage/github/6to5/6to5.svg?style=flat">
+  </a>
+
+  <a href="https://david-dm.org/6to5/6to5">
+    <img alt="Dependency Status" src="http://img.shields.io/david/6to5/6to5.svg?style=flat">
   </a>
 </p>
 
@@ -43,11 +47,15 @@ It's as easy as:
   - [Browser](#browser)
 - [Modules](#modules)
 - [Caveats](#caveats)
+- [Polyfill](#polyfill)
+- [Optional runtime](#optional-runtime)
+- [React/JSX](#reactjsx)
 - [Differences](#differences)
 
 ## [Features](FEATURES.md)
 
  - [Array comprehension](FEATURES.md#array-comprehension)
+ - [Async functions](FEATURES.md#async-functions) via [regenerator](https://github.com/facebook/regenerator)
  - [Arrow functions](FEATURES.md#arrow-functions)
  - [Classes](FEATURES.md#classes)
  - [Computed property names](FEATURES.md#computed-property-names)
@@ -56,11 +64,13 @@ It's as easy as:
  - [Destructuring](FEATURES.md#destructuring)
  - [For-of](FEATURES.md#for-of)
  - [Generators](FEATURES.md#generators) via [regenerator](https://github.com/facebook/regenerator)
+ - [Generator comprehension](FEATURES.md#generator-comprehension)
  - [Let scoping](FEATURES.md#let-scoping)
  - [Modules](FEATURES.md#modules)
  - [Numeric literals](FEATURES.md#numeric-literals)
  - [Property method assignment](FEATURES.md#property-method-assignment)
  - [Property name shorthand](FEATURES.md#property-name-shorthand)
+ - [React/JSX](#reactjsx)
  - [Rest parameters](FEATURES.md#rest-parameters)
  - [Spread](FEATURES.md#spread)
  - [Template literals](FEATURES.md#template-literals)
@@ -71,12 +81,17 @@ It's as easy as:
 ### Plugins
 
  - [Broccoli](https://github.com/very-geek/broccoli-6to5-transpiler)
- - [Browserify](https://github.com/sebmck/6to5-browserify)
+ - [Browserify](https://github.com/6to5/6to5-browserify)
  - [Brunch](https://github.com/es128/6to5-brunch)
- - [Connect](https://github.com/sebmck/6to5-connect)
+ - [Duo](https://github.com/bdo-labs/duo6to5)
+ - [Connect](https://github.com/6to5/6to5-connect)
  - [Gulp](https://github.com/sindresorhus/gulp-6to5)
  - [Grunt](https://github.com/sindresorhus/grunt-6to5)
  - [Jade](https://github.com/Apoxx/jade-6to5)
+ - [Jest](https://github.com/6to5/6to5-jest)
+ - [Karma](https://github.com/shuhei/karma-6to5-preprocessor)
+ - [Mocha](https://github.com/6to5/6to5-mocha)
+ - [Rails](https://github.com/6to5/6to5-rails)
  - [webpack](https://github.com/Couto/6to5-loader)
 
 ### CLI
@@ -103,6 +118,10 @@ Compile the entire `src` directory and output it to the `lib` directory.
 
     $ 6to5 src --out-dir lib
 
+Compile the entire `src` directory and output it to the one concatenated file.
+
+    $ 6to5 src --out-file script-compiled.js
+
 Pipe a file in via stdin and output it to `script-compiled.js`
 
     $ 6to5 --out-file script-compiled.js < script.js
@@ -171,7 +190,12 @@ to5.transformFile("filename.js", options, function (err, result) {
 
   // Set `sources[0]` on returned source map.
   // Default: `filename` option.
-  sourceFileName: "filename"
+  sourceFileName: "filename",
+
+  // Optionally replace all 6to5 helper declarations with a referenece to this
+  // variable. If set to `true` then the default namespace is used "to5Runtime".
+  // Default: false
+  runtime: true
 }
 ```
 
@@ -189,24 +213,64 @@ require("6to5/register");
 override this by passing an ignore regex via:
 
 ```javascript
-require("6to5/register")(/regex/);
+require("6to5/register")({
+  // This will override `node_modules` ignoring - you can alternatively pass
+  // a regex
+  ignore: false
+});
 ```
 
-You can also customise the file extensions that the require hook will use via:
+##### Options
 
 ```javascript
 require("6to5/register")({
-  // optional ignore regex
-  ignoreRegex: /regex/,
+  // Optional ignore regex - if any filenames **do** match this regex then they
+  // aren't compiled
+  ignore: /regex/,
 
-  // this will remove the currently hooked extensions of .es6 and .js so you'll
-  // have to add them back if you want them to be used again
+  // Optional only regex - if any filenames **don't** match this regex then they
+  // aren't compiled
+  only: /my_es6_folder/,
+
+  // See options above for usage
+  whitelist: [],
+  blacklist: [],
+
+  // This will remove the currently hooked extensions of .es6 and .js so you'll
+  // have to add them back if you want them to be used again.
   extensions: [".js", ".es6"]
 });
 ```
 
 ### Browser
 
+A browser version of 6to5 is available from `browser.js` inside the 6to5
+directory in an npm release.
+
+#### Scripts
+
+While it's not recommended for serious use, when the browser version is included
+all scripts with the type `text/ecmascript-6` and `text/6to5` are automatically
+compiled and ran.
+
+For example:
+
+```html
+<script src="node_modules/6to5/browser.js"></script>
+<script type="text/6to5">
+class Test {
+  test() {
+    return "test";
+  }
+}
+
+var test = new Test;
+test.test();
+</script>
+```
+
+#### Build
+
 You can build a browser version of the compiler by running the following in the
 6to5 directory:
 
@@ -214,11 +278,10 @@ You can build a browser version of the compiler by running the following in the
 
 This will output the files `dist/6to5.js` and `dist/6to5.min.js`.
 
-Just include one of those in the browser and access the transform method via the
-global `to5`.
+#### API
 
 ```javascript
-to5("class Test {}").code;
+to5.transform("class Test {}").code;
 ```
 
 #### Test
@@ -238,32 +301,6 @@ Alternatively see [Modules](MODULES.md) for all other supported module formattin
 
 ## Caveats
 
-### Polyfill
-
-6to5 does not include a runtime nor polyfill and it's up to the developer to
-include one in compiled browser code.
-
-#### Node
-
-A polyfill is included with the 6to5 module that can be included in node like
-so:
-
-```javascript
-require("6to5/polyfill");
-```
-
-This is simply a wrapper around the
-[regenerator runtime](https://github.com/facebook/regenerator/blob/master/runtime.js) and the
-[es6-shim](https://github.com/paulmillr/es6-shim) and
-[es6-symbol](https://github.com/medikoo/es6-symbol) polyfills.
-
-#### Browser
-
-If you're planning on using 6to5 output in the browser then it's up to you
-to include polyfills. [es6-symbol](https://github.com/medikoo/es6-symbol#browser)
-and [es6-shim](https://raw.githubusercontent.com/paulmillr/es6-shim/master/es6-shim.js)
-fill the vast majority of polyfill concerns.
-
 ### For-of
 
 A polyfill is required for for-of functionality that implements `Symbol` and
@@ -279,11 +316,111 @@ If you're inheriting from a class then static properties are inherited from it
 via [\_\_proto\_\_](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto),
 this is widely supported but you may run into problems with much older browsers.
 
+**NOTE:** `__proto__` is not supported on IE <= 9 so static properties
+**will not** be inherited. A possible workaround is to use `super();`:
+
+```javascript
+class Foo {
+  static foo() {
+
+  }
+}
+
+class Bar extends Foo {
+  static foo() {
+    super();
+  }
+}
+```
+
+### Spread
+
+An [ES6 polyfill](#polyfill) is required in order for spread to work. More
+specifically a polyfill for `Array.from`.
+
 ### Generators
 
 The [regenerator runtime](https://github.com/facebook/regenerator/blob/master/runtime.js)
 and an [ES6 polyfill](#polyfill) are required in order for generators to work.
 
+## Polyfill
+
+6to5 includes a polyfill that includes the
+[regenerator runtime](https://github.com/facebook/regenerator/blob/master/runtime.js) and the
+[es6-shim](https://github.com/paulmillr/es6-shim) and
+[es6-symbol](https://github.com/medikoo/es6-symbol) polyfills.
+
+### Node
+
+```javascript
+require("6to5/polyfill");
+```
+
+### Browser
+
+Available from the `browser-polyfill.js` file within the 6to5 directory of an
+npm release.
+
+## Optional runtime
+
+6to5 has a few helper functions that'll be placed at the top of the generated
+code if needed so it's not inlined multiple times throughout that file. This may
+become an issue if you have multiple files, especially when you're sending them
+to the browser. gzip alleviates most of this concern but it's still not ideal.
+
+You can tell 6to5 to not place any declarations at the top of your files and
+instead just point them to a reference contained within the runtime.
+
+Simply use the following option if you're using the [Node API](#node-1):
+
+```javascript
+{
+  runtime: true
+}
+```
+
+or the following flag if you're using the [CLI](#cli):
+
+    $ 6to5 --runtime
+
+Then just include the runtime before your generated code.
+
+### Getting the runtime
+
+You can get the runtime via either:
+
+    $ 6to5-runtime
+
+or
+
+```javascript
+require("6to5").runtime();
+```
+
+or from an npm release in `runtime.js` from the 6to5 directory.
+
+### Customising namespace
+
+You can also customise the runtime namespace by passing an optional namespace
+argument:
+
+```javascript
+require("6to5").runtime("myCustomNamespace");
+```
+
+    $ 6to5-runtime myCustomNamespace
+
+See [Options - runtime](#options) for documentation on changing the reference in
+generated code.
+
+## React/JSX
+
+6to5 has built-in support for React v0.12. Tags are automatically transformed to
+their equivalent `React.createElement(...)` and `displayName` is automatically
+inferred and added to all `React.createClass` calls.
+
+To disable this behaviour add `react` to your blacklist.
+
 ## Differences
 
 ### Philosophy

appveyor.yml

@@ -0,0 +1,17 @@
+environment:
+  matrix:
+    - nodejs_version: "0.10"
+    - nodejs_version: "0.11"
+
+install:
+ - "npm install"
+ - "cinst make"
+
+test_script:
+ - "node --version"
+ - "npm --version"
+ - "make test-spec"
+
+build: "off"
+
+version: "{build}"

benchmark/index.js

@@ -7,13 +7,10 @@ var es6now  = require("es6now");
 var esnext  = require("esnext");
 var to5     = require("../lib/6to5");
 
-var uglify  = require("uglify-js");
+//var uglify  = require("uglify-js");
 var matcha  = require("matcha");
-var stream  = require("stream");
 var path    = require("path");
-var zlib    = require("zlib");
 var fs      = require("fs");
-var vm      = require("vm");
 var _       = require("lodash");
 
 var readResolve = function (filename) {
@@ -51,7 +48,7 @@ var compilers = {
 
   traceur: {
     runtime: readResolve("traceur/bin/traceur-runtime.js"),
-    compile: function (code, filename) {
+    compile: function (code) {
       return traceur.compile(code, {
         modules: "commonjs",
         experimental: true
@@ -61,20 +58,20 @@ var compilers = {
 
   esnext: {
     runtime: readResolve("esnext/node_modules/regenerator/runtime.js") || readResolve("regenerator/runtime.js"),
-    compile: function (code, filename) {
+    compile: function (code) {
       return esnext.compile(code).code;
     }
   },
 
   es6now: {
     runtime: readResolve("es6now/runtime/ES6.js"),
-    compile: function (code, filename) {
+    compile: function (code) {
       return es6now.translate(code);
     }
   },
 
   "es6-transpiler": {
-    compile: function (code, filename) {
+    compile: function (code) {
       var result = es6tr.run({ src: code });
       if (result.errors.length) throw new Error(result.join("; "));
       return result.src;
@@ -82,7 +79,7 @@ var compilers = {
   },
 
   jstransform: {
-    compile: function (code, filename) {
+    compile: function (code) {
       return jsTrans.transform(jsTransVisitors, code).code;
     }
   }
@@ -90,7 +87,7 @@ var compilers = {
 
 // versions
 
-var uglifyTitle = "uglify v" + getVersion("uglify-js");
+//var uglifyTitle = "uglify v" + getVersion("uglify-js");
 
 _.each(compilers, function (compiler, name) {
   compiler.title = name + " v" + (compiler.version || getVersion(name));
@@ -162,7 +159,7 @@ _.each(fs.readdirSync(__dirname + "/fixtures"), function (name) {
       });
     });
 
-    _.each(compilers, function (compiler, name) {
+    _.each(compilers, function (compiler) {
       bench(compiler.title, function () {
         compiler.compile(code, loc);
       });

bin/6to5-node

@@ -1,84 +1,56 @@
 #!/usr/bin/env node
 
-var commander = require("commander");
-var Module    = require("module");
-var util      = require("../lib/6to5/util");
-var path      = require("path");
-var repl      = require("repl");
-var to5       = require("../lib/6to5");
-var vm        = require("vm");
-var _         = require("lodash");
+/**
+ * This tiny wrapper file checks for known node flags and appends them
+ * when found, before invoking the "real" _6to5-node(1) executable.
+ */
 
-commander.option("-e, --eval [script]", "evaluate script");
-commander.option("-p, --print", "evaluate script and print result");
-commander.option("-i, --ignore [regex]", "ignore all files that match this regex when using the require hook");
-commander.option("-x, --extensions [extensions]", "list of extensions to hook into [.es6,.js]", util.list);
+var spawn = require("child_process").spawn;
+var args  = ["--harmony", __dirname + "/_6to5-node"];
 
-var pkg = require("../package.json");
-commander.version(pkg.version);
-commander.usage("[options] [ -e script | script.js ] [arguments]");
-commander.parse(process.argv);
+process.argv.slice(2).forEach(function(arg){
+  var flag = arg.split("=")[0];
 
-//
-
-var registerOpts = {};
-
-if (commander.ignore) {
-  registerOpts.ignoreRegex = new RegExp(commander.ignore);
-}
-
-if (commander.extensions && commander.extensions.length) {
-  registerOpts.extensions = commander.extensions
-}
-
-to5.register(registerOpts);
-
-//
-
-var _eval = function (code, filename) {
-  code = to5.transform(code, { filename: filename }).code;
-  return vm.runInThisContext(code, filename);
-};
-
-if (commander.eval) {
-  var result = _eval(commander.eval, "eval");
-  if (commander.print) console.log(result);
-} else {
-  var filenames = commander.args;
-
-  if (filenames.length) {
-    _.each(filenames, function (filename) {
-      if (!util.isAbsolute(filename)) {
-        filename = path.join(process.cwd(), filename);
-      }
-
-      require(require.resolve(filename));
-    });
-  } else {
-    replStart();
+  switch (flag) {
+    case "-d":
+      args.unshift("--debug");
+      args.push("--no-timeouts");
+      break;
+    case "debug":
+    case "--debug":
+    case "--debug-brk":
+      args.unshift(arg);
+      args.push("--no-timeouts");
+      break;
+    case "-gc":
+    case "--expose-gc":
+      args.unshift("--expose-gc");
+      break;
+    case "--gc-global":
+    case "--harmony":
+    case "--harmony-proxies":
+    case "--harmony-collections":
+    case "--harmony-generators":
+    case "--no-deprecation":
+    case "--prof":
+    case "--throw-deprecation":
+    case "--trace-deprecation":
+      args.unshift(arg);
+      break;
+    default:
+      if (0 == arg.indexOf("--trace")) args.unshift(arg);
+      else args.push(arg);
+      break;
   }
-}
+});
 
-function replStart() {
-  repl.start({
-    prompt: "> ",
-    input: process.stdin,
-    output: process.stdout,
-    eval: replEval,
-    useGlobal: true
+var proc = spawn(process.argv[0], args, { stdio: "inherit" });
+proc.on("exit", function (code, signal) {
+  process.on("exit", function (){
+    if (signal) {
+      process.kill(process.pid, signal);
+    } else {
+      process.exit(code);
+    }
   });
-}
-
-function replEval(code, context, filename, callback) {
-  var err;
-  var result;
-
-  try {
-    code = code.slice(1, -2); // remove "(" and "\n)"
-    result = _eval(code, filename);
-  } catch (e) {
-    err = e;
-  }
-
-  callback(err, result);
-}
+});

bin/6to5-runtime

@@ -0,0 +1,4 @@
+#!/usr/bin/env node
+
+var runtime = require("../lib/6to5/runtime");
+console.log(runtime(process.argv[2]));

bin/6to5/file.js

@@ -6,7 +6,7 @@ var util      = require("./util");
 var fs        = require("fs");
 var _         = require("lodash");
 
-module.exports = function (commander, filenames, opts) {
+module.exports = function (commander, filenames) {
   var results = [];
 
   var buildResult = function () {
@@ -48,7 +48,7 @@ module.exports = function (commander, filenames, opts) {
     return {
       map: map,
       code: code
-    }
+    };
   };
 
   var output = function () {
@@ -100,8 +100,8 @@ module.exports = function (commander, filenames, opts) {
       }
     });
 
-    _.each(_filenames, function (filename, i) {
-      results.push(util.compile(filename, { _noStrict: i != 0 }));
+    _.each(_filenames, function (filename) {
+      results.push(util.compile(filename));
     });
 
     output();

bin/6to5/index.js

@@ -1,13 +1,8 @@
 #!/usr/bin/env node
 
 var commander = require("commander");
-var sourceMap = require("source-map");
-var transform = require("../../lib/6to5/transform");
-var chokidar  = require("chokidar");
-var mkdirp    = require("mkdirp");
-var util2     = require("../../lib/6to5/util");
-var util      = require("./util");
-var path      = require("path");
+var transform = require("../../lib/6to5/transformation/transform");
+var util      = require("../../lib/6to5/util");
 var fs        = require("fs");
 var _         = require("lodash");
 
@@ -15,10 +10,11 @@ commander.option("-t, --source-maps-inline", "Append sourceMappingURL comment to
 commander.option("-s, --source-maps", "Save source map alongside the compiled code");
 commander.option("-f, --filename [filename]", "Filename to use when reading from stdin - this will be used in source-maps, errors etc [stdin]", "stdin");
 commander.option("-w, --watch", "Recompile files on changes");
+commander.option("-r, --runtime", "Replace 6to5 declarations with references to a runtime");
 
 commander.option("-m, --modules [modules]", "Module formatter type to use [common]", "common");
-commander.option("-w, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util2.list);
-commander.option("-b, --blacklist [blacklist]", "Blacklist of transformers to NOT use", util2.list);
+commander.option("-w, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util.list);
+commander.option("-b, --blacklist [blacklist]", "Blacklist of transformers to NOT use", util.list);
 commander.option("-o, --out-file [out]", "Compile all input files into a single file");
 commander.option("-d, --out-dir [out]", "Compile an input directory of modules into an output directory");
 
@@ -92,6 +88,7 @@ exports.opts = {
   blacklist:     commander.blacklist,
   whitelist:     commander.whitelist,
   sourceMap:     commander.sourceMaps || commander.sourceMapsInline,
+  runtime:       commander.runtime,
   modules:       commander.modules
 };
 

bin/6to5/util.js

@@ -6,7 +6,9 @@ var fs      = require("fs");
 var _       = require("lodash");
 
 exports.readdirFilter = function (filename) {
-  return readdir(filename).filter(util.canCompile);
+  return readdir(filename).filter(function (filename) {
+    return util.canCompile(filename);
+  });
 };
 
 exports.transform = function (filename, code, opts) {

bin/_6to5-node

@@ -0,0 +1,86 @@
+#!/usr/bin/env node
+
+var commander = require("commander");
+var path      = require("path");
+var repl      = require("repl");
+var to5       = require("../lib/6to5");
+var util      = require("../lib/6to5/util");
+var vm        = require("vm");
+var _         = require("lodash");
+
+commander.option("-e, --eval [script]", "evaluate script");
+commander.option("-p, --print", "evaluate script and print result");
+commander.option("-i, --ignore [regex]", "ignore all files that match this regex when using the require hook");
+commander.option("-x, --extensions [extensions]", "list of extensions to hook into [.es6,.js]", util.list);
+
+var pkg = require("../package.json");
+commander.version(pkg.version);
+commander.usage("[options] [ -e script | script.js ] [arguments]");
+commander.parse(process.argv);
+
+//
+
+var registerOpts = {};
+
+if (commander.ignore) {
+  registerOpts.ignoreRegex = new RegExp(commander.ignore);
+}
+
+if (commander.extensions && commander.extensions.length) {
+  registerOpts.extensions = commander.extensions;
+}
+
+to5.register(registerOpts);
+
+//
+
+var _eval = function (code, filename) {
+  code = to5.transform(code, { filename: filename, blacklist: ["useStrict"] }).code;
+  return vm.runInThisContext(code, filename);
+};
+
+if (commander.eval) {
+  var result = _eval(commander.eval, "eval");
+  if (commander.print) console.log(result);
+} else {
+  var filenames = commander.args;
+
+  if (filenames.length) {
+    _.each(filenames, function (filename) {
+      if (!util.isAbsolute(filename)) {
+        filename = path.join(process.cwd(), filename);
+      }
+
+      require(require.resolve(filename));
+    });
+  } else {
+    replStart();
+  }
+}
+
+function replStart() {
+  repl.start({
+    prompt: "> ",
+    input: process.stdin,
+    output: process.stdout,
+    eval: replEval,
+    useGlobal: true
+  });
+}
+
+function replEval(code, context, filename, callback) {
+  var err;
+  var result;
+
+  try {
+    if (/^\((.*?)\n\)$/.test(code)) {
+      code = code.slice(1, -2); // remove "(" and "\n)"
+    }
+
+    result = _eval(code, filename);
+  } catch (e) {
+    err = e;
+  }
+
+  callback(err, result);
+}

bin/cache-tests

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+
+var fs = require("fs");
+var cache = require("../test/_helper").cache;
+fs.writeFileSync("tests.json", JSON.stringify(cache));

bin/generate-browser-test

@@ -1,6 +0,0 @@
-#!/usr/bin/env node
-
-var helper = require("../test/_helper");
-var util   = require("../lib/6to5/util");
-
-console.log("(" + helper.run + ")(" + JSON.stringify(helper.getTests()) + ", to5, proclaim)");

lib/6to5/browser.js

@@ -1,3 +1,87 @@
-var transform = require("./transform");
+var transform = module.exports = require("./transformation/transform");
 
-module.exports = transform;
+transform.transform = transform;
+
+transform.eval = function (code, opts) {
+  opts = opts || {};
+  opts.filename = opts.filename || "eval";
+  opts.sourceMap = "inline";
+  return eval(transform(code, opts).code);
+};
+
+transform.run = function (code, opts) {
+  opts = opts || {};
+  opts.sourceMap = "inline";
+  return new Function(transform(code, opts).code)();
+};
+
+transform.load = function (url, callback, opts, hold) {
+  opts = opts || {};
+  opts.filename = opts.filename || url;
+
+  var xhr = window.ActiveXObject ? new window.ActiveXObject("Microsoft.XMLHTTP") : new window.XMLHttpRequest();
+  xhr.open("GET", url, true);
+  if ("overrideMimeType" in xhr) xhr.overrideMimeType("text/plain");
+
+  xhr.onreadystatechange = function () {
+    if (xhr.readyState !== 4) return;
+
+    var status = xhr.status;
+    if (status === 0 || status === 200) {
+      var param = [xhr.responseText, opts];
+      if (!hold) transform.run.apply(transform, param);
+      if (callback) callback(param);
+    } else {
+      throw new Error("Could not load " + url);
+    }
+  };
+
+  xhr.send(null);
+};
+
+var runScripts = function () {
+  var scripts = [];
+  var types   = ["text/ecmascript-6", "text/6to5"];
+  var index   = 0;
+
+  var exec = function () {
+    var param = scripts[index];
+    if (param instanceof Array) {
+      transform.run.apply(transform, param);
+      index++;
+      exec();
+    }
+  };
+
+  var run = function (script, i) {
+    var opts = {};
+
+    if (script.src) {
+      transform.load(script.src, function (param) {
+        scripts[i] = param;
+        exec();
+      }, opts, true);
+    } else {
+      opts.filename = "embedded";
+      scripts[i] = [script.innerHTML, opts];
+    }
+  };
+
+  var _scripts = window.document.getElementsByTagName("script");
+  for (var i in _scripts) {
+    var _script = _scripts[i];
+    if (types.indexOf(_script.type) >= 0) scripts.push(_script);
+  }
+
+  for (i in scripts) {
+    run(scripts[i], i);
+  }
+
+  exec();
+};
+
+if (window.addEventListener) {
+  window.addEventListener("DOMContentLoaded", runScripts, false);
+} else {
+  window.attachEvent("onload", runScripts);
+}

lib/6to5/file.js

@@ -2,37 +2,50 @@ module.exports = File;
 
 var SHEBANG_REGEX = /^\#\!.*/;
 
-var transform = require("./transform");
-var recast    = require("acorn-recast");
+var transform = require("./transformation/transform");
+var generate  = require("./generation/generator");
+var Scope     = require("./traverse/scope");
 var util      = require("./util");
-var b         = require("acorn-ast-types").builders;
+var t         = require("./types");
 var _         = require("lodash");
 
 function File(opts) {
   this.opts            = File.normaliseOptions(opts);
-  this.moduleFormatter = this.getModuleFormatter(opts.modules);
+  this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
 
   this.declarations = {};
   this.uids         = {};
   this.ast          = {};
 }
 
+File.declarations = ["extends", "class-props", "slice", "apply-constructor"];
+
 File.normaliseOptions = function (opts) {
-  opts = opts || {};
+  opts = _.cloneDeep(opts || {});
 
   _.defaults(opts, {
-    blacklist: [],
-    whitelist: [],
-    sourceMap: false,
-    filename:  "unknown",
-    modules:   "common"
+    whitespace: true,
+    blacklist:  [],
+    whitelist:  [],
+    sourceMap:  false,
+    filename:   "unknown",
+    modules:    "common",
+    runtime:    false,
+    code:       true
   });
 
+  // normalise windows path separators to unix
+  opts.filename = opts.filename.replace(/\\/g, "/");
+
   _.defaults(opts, {
     sourceFileName: opts.filename,
     sourceMapName:  opts.filename
   });
 
+  if (opts.runtime === true) {
+    opts.runtime = "to5Runtime";
+  }
+
   transform._ensureTransformerNames("blacklist", opts.blacklist);
   transform._ensureTransformerNames("whitelist", opts.whitelist);
 
@@ -40,18 +53,18 @@ File.normaliseOptions = function (opts) {
 };
 
 File.prototype.getModuleFormatter = function (type) {
-  var ModuleLoader = transform.moduleFormatters[type];
+  var ModuleFormatter = transform.moduleFormatters[type];
 
-  if (!ModuleLoader) {
+  if (!ModuleFormatter) {
     var loc = util.resolve(type);
-    if (loc) ModuleLoader = require(loc);
+    if (loc) ModuleFormatter = require(loc);
   }
 
-  if (!ModuleLoader) {
+  if (!ModuleFormatter) {
     throw new ReferenceError("unknown module formatter type " + type);
   }
 
-  return new ModuleLoader(this);
+  return new ModuleFormatter(this);
 };
 
 File.prototype.parseShebang = function (code) {
@@ -67,20 +80,46 @@ File.prototype.parseShebang = function (code) {
 };
 
 File.prototype.addDeclaration = function (name) {
+  if (!_.contains(File.declarations, name)) {
+    throw new ReferenceError("unknown declaration " + name);
+  }
+
   var declar = this.declarations[name];
   if (declar) return declar.uid;
 
-  var uid = b.identifier(this.generateUid(name));
+  var ref;
+  var runtimeNamespace = this.opts.runtime;
+  if (runtimeNamespace) {
+    name = t.identifier(t.toIdentifier(name));
+    return t.memberExpression(t.identifier(runtimeNamespace), name);
+  } else {
+    ref = util.template(name);
+  }
+
+  var uid = t.identifier(this.generateUid(name));
   this.declarations[name] = {
     uid: uid,
-    node: util.template(name)
+    node: ref
   };
   return uid;
 };
 
+File.prototype.errorWithNode = function (node, msg, Error) {
+  Error = Error || SyntaxError;
+
+  var loc = node.loc.start;
+  var err = new Error("Line " + loc.line + ": " + msg);
+  err.loc = loc;
+  return err;
+};
+
 File.prototype.parse = function (code) {
+  code = (code || "") + "";
+
   var self = this;
 
+  this.code = code;
+
   code = this.parseShebang(code);
 
   return util.parse(this.opts, code, function (tree) {
@@ -91,6 +130,7 @@ File.prototype.parse = function (code) {
 
 File.prototype.transform = function (ast) {
   this.ast = ast;
+  this.scope = new Scope(null, ast.program);
 
   var self = this;
 
@@ -103,43 +143,43 @@ File.prototype.generate = function () {
   var opts = this.opts;
   var ast  = this.ast;
 
-  var printOpts = { tabWidth: 2 };
-
-  if (opts.sourceMap) {
-    printOpts.sourceMapName = opts.sourceMapName;
+  if (!opts.code) {
+    return {
+      code: "",
+      map:  null,
+      ast:  ast
+    };
   }
 
-  var result = recast.print(ast, printOpts);
-  var code   = result.code;
+  var result = generate(ast, opts, this.code);
 
   if (this.shebang) {
     // add back shebang
-    code = this.shebang + code;
+    result.code = this.shebang + "\n" + result.code;
   }
 
   if (opts.sourceMap === "inline") {
-    code += "\n" + util.sourceMapToComment(result.map);
+    result.code += "\n" + util.sourceMapToComment(result.map);
   }
 
-  return {
-    code: code,
-    map:  result.map || null,
-    ast:  ast
-  };
+  result.ast = result;
+
+  return result;
 };
 
-File.prototype.generateUid = function (name) {
-  // replace all non-valid identifiers with dashes
-  name = name.replace(/[^a-zA-Z0-9]/g, "-");
+File.prototype.generateUid = function (name, scope) {
+  name = t.toIdentifier(name);
 
-  // remove all dashes and numbers from start of name
-  name = name.replace(/^[-0-9]+/, "");
+  scope = scope || this.scope;
 
-  // camel case
-  name = name.replace(/[-_\s]+(.)?/g, function (match, c) {
-    return c ? c.toUpperCase() : "";
-  });
+  var uid;
+  do {
+    uid = this._generateUid(name);
+  } while (scope.has(uid));
+  return uid;
+};
 
+File.prototype._generateUid = function (name) {
   var uids = this.uids;
   var i = uids[name] || 1;
 

lib/6to5/generation/buffer.js

@@ -0,0 +1,123 @@
+module.exports = Buffer;
+
+var util = require("../util");
+var _    = require("lodash");
+
+function Buffer(position, format) {
+  this.position = position;
+  this._indent  = format.indent.base;
+  this.format   = format;
+  this.buf      = "";
+}
+
+Buffer.prototype.get = function () {
+  return util.trimRight(this.buf);
+};
+
+Buffer.prototype.getIndent = function () {
+  if (this.format.compact) {
+    return "";
+  } else {
+    return util.repeat(this._indent, this.format.indent.style);
+  }
+};
+
+Buffer.prototype.indentSize = function () {
+  return this.getIndent().length;
+};
+
+Buffer.prototype.indent = function () {
+  this._indent++;
+};
+
+Buffer.prototype.dedent = function () {
+  this._indent--;
+};
+
+Buffer.prototype.semicolon = function () {
+  if (this.format.semicolons) this.push(";");
+};
+
+Buffer.prototype.ensureSemicolon = function () {
+  if (!this.isLast(";")) this.semicolon();
+};
+
+Buffer.prototype.rightBrace = function () {
+  this.newline(true);
+  this.push("}");
+};
+
+Buffer.prototype.keyword = function (name) {
+  this.push(name);
+  this.push(" ");
+};
+
+Buffer.prototype.space = function () {
+  if (this.buf && !this.isLast([" ", "\n"])) {
+    this.push(" ");
+  }
+};
+
+Buffer.prototype.removeLast = function (cha) {
+  if (!this.isLast(cha)) return;
+
+  this.buf = this.buf.slice(0, -1);
+  this.position.unshift(cha);
+};
+
+Buffer.prototype.newline = function (i, removeLast) {
+  if (!this.buf) return;
+  if (this.format.compact) return;
+  if (this.endsWith("{\n")) return;
+
+  if (_.isBoolean(i)) {
+    removeLast = i;
+    i = null;
+  }
+
+  if (_.isNumber(i)) {
+    var self = this;
+    _.times(i, function () {
+      self.newline(null, removeLast);
+    });
+    return;
+  }
+
+  if (removeLast && this.isLast("\n")) this.removeLast("\n");
+
+  this.removeLast(" ");
+  this.buf = this.buf.replace(/\n(\s+)$/, "\n");
+  this._push("\n");
+};
+
+Buffer.prototype.push = function (str, noIndent) {
+  if (this._indent && !noIndent && str !== "\n") {
+    // we have an indent level and we aren't pushing a newline
+    var indent = this.getIndent();
+
+    // replace all newlines with newlines with the indentation
+    str = str.replace(/\n/g, "\n" + indent);
+
+    // we've got a newline before us so prepend on the indentation
+    if (this.isLast("\n")) str = indent + str;
+  }
+
+  this._push(str);
+};
+
+Buffer.prototype._push = function (str) {
+  this.position.push(str);
+  this.buf += str;
+};
+
+Buffer.prototype.endsWith = function (str) {
+  return this.buf.slice(-str.length) === str;
+};
+
+Buffer.prototype.isLast = function (cha, trimRight) {
+  var buf = this.buf;
+  if (trimRight) buf = util.trimRight(buf);
+
+  var chars = [].concat(cha);
+  return _.contains(chars, _.last(buf));
+};

lib/6to5/generation/generator.js

@@ -0,0 +1,300 @@
+module.exports = function (ast, opts, code) {
+  var gen = new CodeGenerator(ast, opts, code);
+  return gen.generate();
+};
+
+module.exports.CodeGenerator = CodeGenerator;
+
+var Whitespace = require("./whitespace");
+var SourceMap  = require("./source-map");
+var Position   = require("./position");
+var Buffer     = require("./buffer");
+var util       = require("../util");
+var n          = require("./node");
+var t          = require("../types");
+var _          = require("lodash");
+
+function CodeGenerator(ast, opts, code) {
+  opts = opts || {};
+
+  this.comments = ast.comments || [];
+  this.tokens   = ast.tokens || [];
+  this.format   = CodeGenerator.normaliseOptions(opts);
+  this.ast      = ast;
+
+  this.whitespace = new Whitespace(this.tokens, this.comments);
+  this.position   = new Position;
+  this.map        = new SourceMap(this.position, opts, code);
+  this.buffer     = new Buffer(this.position, this.format);
+}
+
+_.each(Buffer.prototype, function (fn, key) {
+  CodeGenerator.prototype[key] = function () {
+    return fn.apply(this.buffer, arguments);
+  };
+});
+
+CodeGenerator.normaliseOptions = function (opts) {
+  opts = opts.format || {};
+
+  opts = _.merge({
+    parentheses: true,
+    semicolons: true,
+    comments: true,
+    compact: false,
+    indent: {
+      adjustMultilineComment: true,
+      style: "  ",
+      base: 0
+    }
+  }, opts);
+
+  return opts;
+};
+
+CodeGenerator.generators = {
+  templateLiterals: require("./generators/template-literals"),
+  comprehensions:   require("./generators/comprehensions"),
+  expressions:      require("./generators/expressions"),
+  statements:       require("./generators/statements"),
+  classes:          require("./generators/classes"),
+  methods:          require("./generators/methods"),
+  modules:          require("./generators/modules"),
+  types:            require("./generators/types"),
+  base:             require("./generators/base"),
+  jsx:              require("./generators/jsx")
+};
+
+_.each(CodeGenerator.generators, function (generator) {
+  _.extend(CodeGenerator.prototype, generator);
+});
+
+CodeGenerator.prototype.generate = function () {
+  var ast = this.ast;
+
+  this.print(ast);
+
+  return {
+    map:  this.map.get(),
+    code: this.buffer.get()
+  };
+};
+
+CodeGenerator.prototype.buildPrint = function (parent) {
+  var self = this;
+
+  var print = function (node, opts) {
+    return self.print(node, parent, opts);
+  };
+
+  print.sequence = function (nodes, opts) {
+    opts = opts || {};
+    opts.statement = true;
+    return self.printJoin(print, nodes, opts);
+  };
+
+  print.join = function (nodes, opts) {
+    return self.printJoin(print, nodes, opts);
+  };
+
+  print.block = function (node) {
+    return self.printBlock(print, node);
+  };
+
+  print.indentOnComments = function (node) {
+    return self.printAndIndentOnComments(print, node);
+  };
+
+  return print;
+};
+
+CodeGenerator.prototype.print = function (node, parent, opts) {
+  if (!node) return "";
+
+  var self = this;
+  opts = opts || {};
+
+  var newline = function (leading) {
+    var ignoreDuplicates = false;
+
+    if (!opts.statement && !n.isUserWhitespacable(node, parent)) {
+      return;
+    }
+
+    var lines = 0;
+
+    if (node.start != null) {
+      // user node
+      if (leading) {
+        lines = self.whitespace.getNewlinesBefore(node);
+      } else {
+        lines = self.whitespace.getNewlinesAfter(node);
+      }
+    } else {
+      // generated node
+      if (!leading) lines++; // always include at least a single line after
+
+      var needs = n.needsWhitespaceAfter;
+      if (leading) needs = n.needsWhitespaceBefore;
+      lines += needs(node, parent);
+    }
+
+    self.newline(lines, ignoreDuplicates);
+  };
+
+  if (this[node.type]) {
+    this.printLeadingComments(node, parent);
+
+    newline(true);
+
+    if (opts.before) opts.before();
+    this.map.mark(node, "start");
+
+    // only compute if this node needs parens if our parent has been changed
+    // since acorn would've wrapped us in a ParanthesizedExpression
+    var needsParens = parent !== node._parent && n.needsParens(node, parent);
+    if (needsParens) this.push("(");
+
+    this[node.type](node, this.buildPrint(node), parent);
+
+    if (needsParens) this.push(")");
+
+    this.map.mark(node, "end");
+    if (opts.after) opts.after();
+
+    newline(false);
+
+    this.printTrailingComments(node, parent);
+  } else {
+    throw new ReferenceError("unknown node " + node.type + " " + JSON.stringify(node));
+  }
+};
+
+CodeGenerator.prototype.printJoin = function (print, nodes, opts) {
+  opts = opts || {};
+
+  var self = this;
+  var len  = nodes.length;
+
+  if (opts.indent) self.indent();
+
+  _.each(nodes, function (node, i) {
+    print(node, {
+      statement: opts.statement,
+      after: function () {
+        if (opts.iterator) {
+          opts.iterator(node, i);
+        }
+
+        if (opts.separator && i < len - 1) {
+          self.push(opts.separator);
+        }
+      }
+    });
+  });
+
+  if (opts.indent) self.dedent();
+};
+
+CodeGenerator.prototype.printAndIndentOnComments = function (print, node) {
+  var indent = !!node.leadingComments;
+  if (indent) this.indent();
+  print(node);
+  if (indent) this.dedent();
+};
+
+CodeGenerator.prototype.printBlock = function (print, node) {
+  if (t.isEmptyStatement(node)) {
+    this.semicolon();
+  } else {
+    this.push(" ");
+    print(node);
+  }
+};
+
+CodeGenerator.prototype.generateComment = function (comment) {
+  var val = comment.value;
+  if (comment.type === "Line") {
+    val = "//" + val;
+  } else {
+    val = "/*" + val + "*/";
+  }
+  return val;
+};
+
+CodeGenerator.prototype.printTrailingComments = function (node, parent) {
+  this._printComments(this.getComments("trailingComments", node, parent));
+};
+
+CodeGenerator.prototype.printLeadingComments = function (node, parent) {
+  this._printComments(this.getComments("leadingComments", node, parent));
+};
+
+CodeGenerator.prototype.getComments = function (key, node, parent) {
+  if (t.isExpressionStatement(parent)) {
+    return [];
+  }
+
+  var comments = [];
+  var nodes    = [node];
+  var self     = this;
+
+  if (t.isExpressionStatement(node)) {
+    nodes.push(node.argument);
+  }
+
+  _.each(nodes, function (node) {
+    comments = comments.concat(self._getComments(key, node));
+  });
+
+  return comments;
+};
+
+CodeGenerator.prototype._getComments = function (key, node) {
+  return (node && node[key]) || [];
+};
+
+CodeGenerator.prototype._printComments = function (comments) {
+  if (this.format.compact) return;
+  if (!this.format.comments) return;
+  if (!comments || !comments.length) return;
+
+  var self = this;
+
+  _.each(comments, function (comment) {
+    // whitespace before
+    self.newline(self.whitespace.getNewlinesBefore(comment));
+
+    var column = self.position.column;
+    var val    = self.generateComment(comment);
+
+    if (column && !self.isLast(["\n", " ", "[", "{"])) {
+      self._push(" ");
+      column++;
+    }
+
+    //
+
+    if (comment.type === "Block" && self.format.indent.adjustMultilineComment) {
+      var offset = comment.loc.start.column;
+      if (offset) {
+        var newlineRegex = new RegExp("\\n\\s{1," + offset + "}", "g");
+        val = val.replace(newlineRegex, "\n");
+      }
+
+      var indent = Math.max(self.indentSize(), column);
+      val = val.replace(/\n/g, "\n" + util.repeat(indent));
+    }
+
+    if (column === 0) {
+      val = self.getIndent() + val;
+    }
+
+    //
+
+    self._push(val);
+
+    // whitespace after
+    self.newline(self.whitespace.getNewlinesAfter(comment));
+  });
+};

lib/6to5/generation/generators/base.js

@@ -0,0 +1,19 @@
+exports.File = function (node, print) {
+  print(node.program);
+};
+
+exports.Program = function (node, print) {
+  print.sequence(node.body);
+};
+
+exports.BlockStatement = function (node, print) {
+  if (node.body.length === 0) {
+    this.push("{}");
+  } else {
+    this.push("{");
+    this.newline();
+    print.sequence(node.body, { indent: true });
+    this.removeLast("\n");
+    this.rightBrace();
+  }
+};

lib/6to5/generation/generators/classes.js

@@ -0,0 +1,32 @@
+exports.ClassExpression =
+exports.ClassDeclaration = function (node, print) {
+  this.push("class");
+
+  if (node.id) {
+    this.space();
+    print(node.id);
+  }
+
+  if (node.superClass) {
+    this.push(" extends ");
+    print(node.superClass);
+  }
+
+  this.space();
+  print(node.body);
+};
+
+exports.ClassBody = function (node, print) {
+  if (node.body.length === 0) {
+    this.push("{}");
+  } else {
+    this.push("{");
+    this.newline();
+
+    this.indent();
+    print.sequence(node.body);
+    this.dedent();
+
+    this.rightBrace();
+  }
+};

lib/6to5/generation/generators/comprehensions.js

@@ -0,0 +1,27 @@
+exports.ComprehensionBlock = function (node, print) {
+  this.keyword("for");
+  this.push("(");
+  print(node.left);
+  this.push(" of ");
+  print(node.right);
+  this.push(")");
+};
+
+exports.ComprehensionExpression = function (node, print) {
+  this.push(node.generator ? "(" : "[");
+
+  print.join(node.blocks, { separator: " " });
+  this.space();
+
+  if (node.filter) {
+    this.keyword("if");
+    this.push("(");
+    print(node.filter);
+    this.push(")");
+    this.space();
+  }
+
+  print(node.body);
+
+  this.push(node.generator ? ")" : "]");
+};

lib/6to5/generation/generators/expressions.js

@@ -0,0 +1,111 @@
+var t = require("../../types");
+
+exports.UnaryExpression = function (node, print) {
+  var hasSpace = /[a-z]$/.test(node.operator);
+  var arg = node.argument;
+
+  if (t.isUpdateExpression(arg) || t.isUnaryExpression(arg)) {
+    hasSpace = true;
+  }
+
+  if (t.isUnaryExpression(arg) && arg.operator === "!") {
+    hasSpace = false;
+  }
+
+  this.push(node.operator);
+  if (hasSpace) this.space();
+  print(node.argument);
+};
+
+exports.ParenthesizedExpression = function (node, print) {
+  this.push("(");
+  print(node.expression);
+  this.push(")");
+};
+
+exports.UpdateExpression = function (node, print) {
+  if (node.prefix) {
+    this.push(node.operator);
+    print(node.argument);
+  } else {
+    print(node.argument);
+    this.push(node.operator);
+  }
+};
+
+exports.ConditionalExpression = function (node, print) {
+  print(node.test);
+  this.push(" ? ");
+  print(node.consequent);
+  this.push(" : ");
+  print(node.alternate);
+};
+
+exports.NewExpression = function (node, print) {
+  this.push("new ");
+  print(node.callee);
+  if (node.arguments.length || this.format.parentheses) {
+    this.push("(");
+    print.join(node.arguments, { separator: ", " });
+    this.push(")");
+  }
+};
+
+exports.SequenceExpression = function (node, print) {
+  print.join(node.expressions, { separator: ", " });
+};
+
+exports.ThisExpression = function () {
+  this.push("this");
+};
+
+exports.CallExpression = function (node, print) {
+  print(node.callee);
+  this.push("(");
+  print.join(node.arguments, { separator: ", " });
+  this.push(")");
+};
+
+var buildYieldAwait = function (keyword) {
+  return function (node, print) {
+    this.push(keyword);
+    if (node.delegate) this.push("*");
+    if (node.argument) {
+      this.space();
+      print(node.argument);
+    }
+  };
+};
+
+exports.YieldExpression = buildYieldAwait("yield");
+exports.AwaitExpression = buildYieldAwait("await");
+
+exports.EmptyStatement = function () {
+  this.semicolon();
+};
+
+exports.ExpressionStatement = function (node, print) {
+  print(node.expression);
+  this.semicolon();
+};
+
+exports.BinaryExpression =
+exports.LogicalExpression =
+exports.AssignmentExpression = function (node, print) {
+  print(node.left);
+  this.push(" " + node.operator + " ");
+  print(node.right);
+};
+
+exports.MemberExpression = function (node, print) {
+  print(node.object);
+
+  if (node.computed) {
+    this.push("[");
+    print(node.property);
+    this.push("]");
+  } else {
+    this.push(".");
+    print(node.property);
+  }
+};

lib/6to5/generation/generators/jsx.js

@@ -0,0 +1,78 @@
+var t = require("../../types");
+var _ = require("lodash");
+
+exports.XJSAttribute = function (node, print) {
+  print(node.name);
+  if (node.value) {
+    this.push("=");
+    print(node.value);
+  }
+};
+
+exports.XJSIdentifier = function (node) {
+  this.push(node.name);
+};
+
+exports.XJSNamespacedName = function (node, print) {
+  print(node.namespace);
+  this.push(":");
+  print(node.name);
+};
+
+exports.XJSMemberExpression = function (node, print) {
+  print(node.object);
+  this.push(".");
+  print(node.property);
+};
+
+exports.XJSSpreadAttribute = function (node, print) {
+  this.push("{...");
+  print(node.argument);
+  this.push("}");
+};
+
+exports.XJSExpressionContainer = function (node, print) {
+  this.push("{");
+  print(node.expression);
+  this.push("}");
+};
+
+exports.XJSElement = function (node, print) {
+  var self = this;
+
+  var open = node.openingElement;
+  print(open);
+  if (open.selfClosing) return;
+
+  this.indent();
+  _.each(node.children, function (child) {
+    if (t.isLiteral(child)) {
+      self.push(child.value);
+    } else {
+      print(child);
+    }
+  });
+  this.dedent();
+
+  print(node.closingElement);
+};
+
+exports.XJSOpeningElement = function (node, print) {
+  this.push("<");
+  print(node.name);
+  if (node.attributes.length > 0) {
+    this.space();
+    print.join(node.attributes, { separator: " " });
+  }
+  this.push(node.selfClosing ? " />" : ">");
+};
+
+exports.XJSClosingElement = function (node, print) {
+  this.push("</");
+  print(node.name);
+  this.push(">");
+};
+
+exports.XJSEmptyExpression = function () {
+  this.push("null");
+};

lib/6to5/generation/generators/methods.js

@@ -0,0 +1,85 @@
+var t = require("../../types");
+
+exports._params = function (node, print) {
+  var self = this;
+
+  this.push("(");
+
+  print.join(node.params, {
+    separator: ", ",
+    iterator: function (param, i) {
+      var def = node.defaults && node.defaults[i];
+      if (def) {
+        self.push(" = ");
+        print(def);
+      }
+    }
+  });
+
+  if (node.rest) {
+    if (node.params.length) {
+      this.push(", ");
+    }
+
+    this.push("...");
+    print(node.rest);
+  }
+
+  this.push(")");
+};
+
+exports._method = function (node, print) {
+  var value = node.value;
+  var kind  = node.kind;
+  var key   = node.key;
+
+  if (!kind || kind === "init") {
+    if (value.generator) {
+      this.push("*");
+    }
+  } else {
+    this.push(kind + " ");
+  }
+
+  if (node.computed) {
+    this.push("[");
+    print(key);
+    this.push("]");
+  } else {
+    print(key);
+  }
+
+  this._params(value, print);
+  this.space();
+  print(value.body);
+};
+
+exports.MethodDefinition = function (node, print) {
+  if (node.static) {
+    this.push("static ");
+  }
+
+  this._method(node, print);
+};
+
+exports.FunctionDeclaration =
+exports.FunctionExpression = function (node, print) {
+  this.push("function");
+  if (node.generator) this.push("*");
+  this.space();
+  if (node.id) print(node.id);
+  this._params(node, print);
+  this.space();
+  print(node.body);
+};
+
+exports.ArrowFunctionExpression = function (node, print) {
+  if (node.params.length === 1 && !node.defaults.length && !node.rest && t.isIdentifier(node.params[0])) {
+    print(node.params[0]);
+  } else {
+    this._params(node, print);
+  }
+
+  this.push(" => ");
+  print(node.body);
+};

lib/6to5/generation/generators/modules.js

@@ -0,0 +1,86 @@
+var t = require("../../types");
+var _ = require("lodash");
+
+exports.ImportSpecifier =
+exports.ExportSpecifier = function (node, print) {
+  print(node.id);
+  if (node.name) {
+    this.push(" as ");
+    print(node.name);
+  }
+};
+
+exports.ExportBatchSpecifier = function () {
+  this.push("*");
+};
+
+exports.ExportDeclaration = function (node, print) {
+  this.push("export ");
+
+  var specifiers = node.specifiers;
+
+  if (node.default) {
+    this.push("default ");
+  }
+
+  if (node.declaration) {
+    print(node.declaration);
+  } else {
+    if (specifiers.length === 1 && t.isExportBatchSpecifier(specifiers[0])) {
+      this.push("*");
+    } else {
+      this.push("{");
+      if (specifiers.length) {
+        this.space();
+        print.join(specifiers, { separator: ", " });
+        this.space();
+      }
+      this.push("}");
+    }
+
+    if (node.source) {
+      this.push(" from ");
+      print(node.source);
+    }
+  }
+
+  this.ensureSemicolon();
+};
+
+exports.ImportDeclaration = function (node, print) {
+  var self = this;
+
+  this.push("import ");
+
+  var specfiers = node.specifiers;
+  if (specfiers && specfiers.length) {
+    var foundImportSpecifier = false;
+
+    _.each(node.specifiers, function (spec, i) {
+      if (+i > 0) {
+        self.push(", ");
+      }
+
+      if (!spec.default && spec.type !== "ImportBatchSpecifier" && !foundImportSpecifier) {
+        foundImportSpecifier = true;
+        self.push("{ ");
+      }
+
+      print(spec);
+    });
+
+    if (foundImportSpecifier) {
+      this.push(" }");
+    }
+
+    this.push(" from ");
+  }
+
+  print(node.source);
+  this.semicolon();
+};
+
+exports.ImportBatchSpecifier = function (node, print) {
+  this.push("* as ");
+  print(node.name);
+};

lib/6to5/generation/generators/statements.js

@@ -0,0 +1,188 @@
+var t = require("../../types");
+
+exports.WithStatement = function (node, print) {
+  this.keyword("with");
+  this.push("(");
+  print(node.object);
+  print.block(node.body);
+};
+
+exports.IfStatement = function (node, print) {
+  this.keyword("if");
+  this.push("(");
+  print(node.test);
+  this.push(") ");
+
+  print.indentOnComments(node.consequent);
+
+  if (node.alternate) {
+    if (this.isLast("}")) this.space();
+    this.keyword("else");
+    print.indentOnComments(node.alternate);
+  }
+};
+
+exports.ForStatement = function (node, print) {
+  this.keyword("for");
+  this.push("(");
+
+  print(node.init);
+  this.push(";");
+
+  if (node.test) {
+    this.space();
+    print(node.test);
+  }
+  this.push(";");
+
+  if (node.update) {
+    this.space();
+    print(node.update);
+  }
+
+  this.push(")");
+  print.block(node.body);
+};
+
+exports.WhileStatement = function (node, print) {
+  this.keyword("while");
+  this.push("(");
+  print(node.test);
+  this.push(")");
+  print.block(node.body);
+};
+
+var buildForXStatement = function (op) {
+  return function (node, print) {
+    this.keyword("for");
+    this.push("(");
+    print(node.left);
+    this.push(" " + op + " ");
+    print(node.right);
+    this.push(")");
+    print.block(node.body);
+  };
+};
+
+exports.ForInStatement = buildForXStatement("in");
+exports.ForOfStatement = buildForXStatement("of");
+
+exports.DoWhileStatement = function (node, print) {
+  this.keyword("do");
+  print(node.body);
+  this.space();
+  this.keyword("while");
+  this.push("(");
+  print(node.test);
+  this.push(");");
+};
+
+var buildLabelStatement = function (prefix, key) {
+  return function (node, print) {
+    this.push(prefix);
+
+    var label = node[key || "label"];
+    if (label) {
+      this.space();
+      print(label);
+    }
+
+    this.semicolon();
+  };
+};
+
+exports.ContinueStatement = buildLabelStatement("continue");
+exports.ReturnStatement   = buildLabelStatement("return", "argument");
+exports.BreakStatement    = buildLabelStatement("break");
+
+exports.LabeledStatement = function (node, print) {
+  print(node.label);
+  this.push(": ");
+  print(node.body);
+};
+
+exports.TryStatement = function (node, print) {
+  this.keyword("try");
+  print(node.block);
+  this.space();
+  print(node.handler);
+  if (node.finalizer) {
+    this.space();
+    this.push("finally ");
+    print(node.finalizer);
+  }
+};
+
+exports.CatchClause = function (node, print) {
+  this.keyword("catch");
+  this.push("(");
+  print(node.param);
+  this.push(") ");
+  print(node.body);
+};
+
+exports.ThrowStatement = function (node, print) {
+  this.push("throw ");
+  print(node.argument);
+  this.semicolon();
+};
+
+exports.SwitchStatement = function (node, print) {
+  this.keyword("switch");
+  this.push("(");
+  print(node.discriminant);
+  this.push(") {");
+  print.sequence(node.cases, { indent: true });
+  this.push("}");
+
+  //if (node.cases.length) {
+  //  this.newline();
+  //  print.sequence(node.cases, { indent: true });
+  //  this.newline();
+  //  this.rightBrace();
+  //} else {
+  //  this.push("}");
+  //}
+};
+
+exports.SwitchCase = function (node, print) {
+  if (node.test) {
+    this.push("case ");
+    print(node.test);
+    this.push(":");
+  } else {
+    this.push("default:");
+  }
+
+  if (node.consequent.length === 1) {
+    this.space();
+    print(node.consequent[0]);
+  } else if (node.consequent.length > 1) {
+    this.newline();
+    print.sequence(node.consequent, { indent: true });
+  }
+};
+
+exports.DebuggerStatement = function () {
+  this.push("debugger;");
+};
+
+exports.VariableDeclaration = function (node, print, parent) {
+  this.push(node.kind + " ");
+
+  print.join(node.declarations, { separator: ", " });
+
+  if (!t.isFor(parent)) {
+    this.semicolon();
+  }
+};
+
+exports.VariableDeclarator = function (node, print) {
+  if (node.init) {
+    print(node.id);
+    this.push(" = ");
+    print(node.init);
+  } else {
+    print(node.id);
+  }
+};

lib/6to5/generation/generators/template-literals.js

@@ -0,0 +1,30 @@
+var _ = require("lodash");
+
+exports.TaggedTemplateExpression = function (node, print) {
+  print(node.tag);
+  print(node.quasi);
+};
+
+exports.TemplateElement = function (node) {
+  this._push(node.value.raw);
+};
+
+exports.TemplateLiteral = function (node, print) {
+  this.push("`");
+
+  var quasis = node.quasis;
+  var self   = this;
+  var len    = quasis.length;
+
+  _.each(quasis, function (quasi, i) {
+    print(quasi);
+
+    if (i + 1 < len) {
+      self.push("${ ");
+      print(node.expressions[i]);
+      self.push(" }");
+    }
+  });
+
+  this._push("`");
+};

lib/6to5/generation/generators/types.js

@@ -0,0 +1,86 @@
+var _ = require("lodash");
+
+exports.Identifier = function (node) {
+  this.push(node.name);
+};
+
+exports.SpreadElement = function (node, print) {
+  this.push("...");
+  print(node.argument);
+};
+
+exports.ObjectExpression =
+exports.ObjectPattern = function (node, print) {
+  var props = node.properties;
+
+  if (props.length) {
+    this.push("{");
+    this.space();
+
+    print.join(props, { separator: ", ", indent: true });
+
+    this.space();
+    this.push("}");
+  } else {
+    this.push("{}");
+  }
+};
+
+exports.Property = function (node, print) {
+  if (node.method || node.kind === "get" || node.kind === "set") {
+    this._method(node, print);
+  } else {
+    if (node.computed) {
+      this.push("[");
+      print(node.key);
+      this.push("]");
+    } else {
+      print(node.key);
+      if (node.shorthand) return;
+    }
+
+    this.push(": ");
+    print(node.value);
+  }
+};
+
+exports.ArrayExpression =
+exports.ArrayPattern = function (node, print) {
+  var elems = node.elements;
+  var self  = this;
+  var len   = elems.length;
+
+  this.push("[");
+
+  _.each(elems, function (elem, i) {
+    if (!elem) {
+      // If the array expression ends with a hole, that hole
+      // will be ignored by the interpreter, but if it ends with
+      // two (or more) holes, we need to write out two (or more)
+      // commas so that the resulting code is interpreted with
+      // both (all) of the holes.
+      self.push(",");
+    } else {
+      if (i > 0) self.push(" ");
+      print(elem);
+      if (i < len - 1) self.push(",");
+    }
+  });
+
+  this.push("]");
+};
+
+exports.Literal = function (node) {
+  var val  = node.value;
+  var type = typeof val;
+
+  if (type === "boolean" || type === "number" || type === "string") {
+    this.push(JSON.stringify(val));
+  } else if (node.regex) {
+    this.push("/" + node.regex.pattern + "/" + node.regex.flags);
+  } else if (val === null) {
+    this.push("null");
+  } else if (node.raw) {
+    this.push(node.raw);
+  }
+};

lib/6to5/generation/node/index.js

@@ -0,0 +1,90 @@
+module.exports = Node;
+
+var whitespace = require("./whitespace");
+var parens     = require("./parentheses");
+var t           = require("../../types");
+var _           = require("lodash");
+
+var find = function (obj, node, parent) {
+  var result;
+
+  _.each(obj, function (fn, type) {
+    if (t["is" + type](node)) {
+      result = fn(node, parent);
+      if (result != null) return false;
+    }
+  });
+
+  return result;
+};
+
+function Node(node, parent) {
+  this.parent = parent;
+  this.node   = node;
+}
+
+Node.prototype.isUserWhitespacable = function () {
+  //var parent = this.parent;
+  var node = this.node;
+
+  if (t.isUserWhitespacable(node)) {
+    return true;
+  }
+
+  //if (t.isArrayExpression(parent)) {
+  //  return true;
+  //}
+
+  return false;
+};
+
+Node.prototype.needsWhitespace = function (type) {
+  var parent = this.parent;
+  var node   = this.node;
+  if (!node) return 0;
+
+  if (t.isExpressionStatement(node)) {
+    node = node.expression;
+  }
+
+  var lines = find(whitespace[type].nodes, node, parent);
+  if (lines) return lines;
+
+  _.each(find(whitespace[type].list, node, parent), function (expr) {
+    lines = Node.needsWhitespace(expr, node, type);
+    if (lines) return false;
+  });
+  return lines || 0;
+};
+
+Node.prototype.needsWhitespaceBefore = function () {
+  return this.needsWhitespace("before");
+};
+
+Node.prototype.needsWhitespaceAfter = function () {
+  return this.needsWhitespace("after");
+};
+
+Node.prototype.needsParens = function () {
+  var parent = this.parent;
+  var node   = this.node;
+
+  if (!parent) return false;
+
+  if (t.isNewExpression(parent) && parent.callee === node) {
+    return t.isCallExpression(node) || _.some(node, function (val) {
+      return t.isCallExpression(val);
+    });
+  }
+
+  return find(parens, node, parent);
+};
+
+_.each(Node.prototype, function (fn, key) {
+  Node[key] = function (node, parent) {
+    var n = new Node(node, parent);
+
+    var args = _.toArray(arguments).slice(2);
+    return n[key].apply(n, args);
+  };
+});

lib/6to5/generation/node/parentheses.js

@@ -0,0 +1,150 @@
+var t = require("../../types");
+var _ = require("lodash");
+
+var PRECEDENCE = {};
+
+_.each([
+  ["||"],
+  ["&&"],
+  ["|"],
+  ["^"],
+  ["&"],
+  ["==", "===", "!=", "!=="],
+  ["<", ">", "<=", ">=", "in", "instanceof"],
+  [">>", "<<", ">>>"],
+  ["+", "-"],
+  ["*", "/", "%"]
+], function (tier, i) {
+  _.each(tier, function (op) {
+    PRECEDENCE[op] = i;
+  });
+});
+
+exports.Binary = function (node, parent) {
+  if (t.isCallExpression(parent) && parent.callee === node) {
+    return true;
+  }
+
+  if (t.isUnaryLike(parent)) {
+    return true;
+  }
+
+  if (t.isMemberExpression(parent) && parent.object === node) {
+    return true;
+  }
+
+  if (t.isBinary(parent)) {
+    var parentOp  = parent.operator;
+    var parentPos = PRECEDENCE[parentOp];
+
+    var nodeOp = node.operator;
+    var nodePos = PRECEDENCE[nodeOp];
+
+    if (parentPos > nodePos) {
+      return true;
+    }
+
+    if (parentPos === nodePos && parent.right === node) {
+      return true;
+    }
+  }
+};
+
+exports.BinaryExpression = function (node, parent) {
+  if (node.operator === "in") {
+    // var i = (1 in []);
+    if (t.isVariableDeclarator(parent)) {
+      return true;
+    }
+
+    // for ((1 in []);;);
+    if (t.isFor(parent)) {
+      return true;
+    }
+  }
+};
+
+exports.SequenceExpression = function (node, parent) {
+  if (t.isForStatement(parent)) {
+    // Although parentheses wouldn't hurt around sequence
+    // expressions in the head of for loops, traditional style
+    // dictates that e.g. i++, j++ should not be wrapped with
+    // parentheses.
+    return false;
+  }
+
+  if (t.isExpressionStatement(parent) && parent.expression === node) {
+    return false;
+  }
+
+  // Otherwise err on the side of overparenthesization, adding
+  // explicit exceptions above if this proves overzealous.
+  return true;
+};
+
+exports.YieldExpression = function (node, parent) {
+  return t.isBinary(parent) ||
+         t.isUnaryLike(parent) ||
+         t.isCallExpression(parent) ||
+         t.isMemberExpression(parent) ||
+         t.isNewExpression(parent) ||
+         t.isConditionalExpression(parent) ||
+         t.isYieldExpression(parent);
+};
+
+exports.Literal = function (node, parent) {
+  // (1).valueOf()
+  if (_.isNumber(node.value) && t.isMemberExpression(parent) && parent.object === node) {
+    return true;
+  }
+};
+
+exports.ClassExpression = function (node, parent) {
+  return t.isExpressionStatement(parent);
+};
+
+exports.UnaryLike = function (node, parent) {
+  return t.isMemberExpression(parent) && parent.object === node;
+};
+
+exports.FunctionExpression = function (node, parent) {
+  // function () {};
+  if (t.isExpressionStatement(parent)) {
+    return true;
+  }
+
+  // (function test() {}).name;
+  if (t.isMemberExpression(parent) && parent.object === node) {
+    return true;
+  }
+
+  // (function () {})();
+  if (t.isCallExpression(parent) && parent.callee === node) {
+    return true;
+  }
+};
+
+exports.AssignmentExpression =
+exports.ConditionalExpression = function (node, parent) {
+  if (t.isUnaryLike(parent)) {
+    return true;
+  }
+
+  if (t.isBinary(parent)) {
+    return true;
+  }
+
+  if (t.isCallExpression(parent) && parent.callee === node) {
+    return true;
+  }
+
+  if (t.isConditionalExpression(parent) && parent.test === node) {
+    return true;
+  }
+
+  if (t.isMemberExpression(parent) && parent.object === node) {
+    return true;
+  }
+
+  return false;
+};

lib/6to5/generation/node/whitespace.js

@@ -0,0 +1,60 @@
+var _ = require("lodash");
+var t = require("../../types");
+
+exports.before = {
+  nodes: {
+    Property: function (node, parent) {
+      if (parent.properties[0] === node) {
+        return 1;
+      }
+    },
+
+    SwitchCase: function (node, parent) {
+      if (parent.cases[0] === node) {
+        return 1;
+      }
+    },
+
+    CallExpression: function (node) {
+      if (t.isFunction(node.callee)) {
+        return 1;
+      }
+    }
+  }
+};
+
+exports.after = {
+  nodes: {},
+
+  list: {
+    VariableDeclaration: function (node) {
+      return _.map(node.declarations, "init");
+    },
+
+    ArrayExpression: function (node) {
+      return node.elements;
+    },
+
+    ObjectExpression: function (node) {
+      return node.properties;
+    }
+  }
+};
+
+_.each({
+  Function: 1,
+  Class: 1,
+  For: 1,
+  SwitchStatement: 1,
+  IfStatement: { before: 1 },
+  CallExpression: { after: 1 },
+  Literal: { after: 1 }
+}, function (amounts, type) {
+  if (_.isNumber(amounts)) amounts = { after: amounts, before: amounts };
+
+  _.each(amounts, function (amount, key) {
+    exports[key].nodes[type] = function () {
+      return amount;
+    };
+  });
+});

lib/6to5/generation/position.js

@@ -0,0 +1,33 @@
+module.exports = Position;
+
+var _ = require("lodash");
+
+function Position() {
+  this.line = 1;
+  this.column = 0;
+}
+
+Position.prototype.push = function (str) {
+  var self = this;
+
+  _.each(str, function (cha) {
+    if (cha === "\n") {
+      self.line++;
+      self.column = 0;
+    } else {
+      self.column++;
+    }
+  });
+};
+
+Position.prototype.unshift = function (str) {
+  var self = this;
+
+  _.each(str, function (cha) {
+    if (cha === "\n") {
+      self.line--;
+    } else {
+      self.column--;
+    }
+  });
+};

lib/6to5/generation/source-map.js

@@ -0,0 +1,55 @@
+module.exports = SourceMap;
+
+var sourceMap = require("source-map");
+var t         = require("../types");
+
+function SourceMap(position, opts, code) {
+  this.position = position;
+  this.opts     = opts;
+
+  if (opts.sourceMap) {
+    this.map = new sourceMap.SourceMapGenerator({
+      file: opts.sourceMapName
+    });
+
+    this.map.setSourceContent(opts.sourceFileName, code);
+  } else {
+    this.map = null;
+  }
+}
+
+SourceMap.prototype.get = function () {
+  var map = this.map;
+  if (map) {
+    return map.toJSON();
+  } else {
+    return map;
+  }
+};
+
+SourceMap.prototype.mark = function (node, type) {
+  var loc = node.loc;
+  if (!loc) return; // no location info
+
+  var map = this.map;
+  if (!map) return; // no source map
+
+  if (t.isProgram(node) || t.isFile(node)) return; // illegal mapping nodes
+
+  var position = this.position;
+
+  var generated = {
+    line: position.line,
+    column: position.column
+  };
+
+  var original = loc[type];
+
+  if (generated.line === original.line && generated.column === original.column) return; // nothing to map
+
+  map.addMapping({
+    source: this.opts.sourceFileName,
+    generated: generated,
+    original: original
+  });
+};

lib/6to5/generation/whitespace.js

@@ -0,0 +1,58 @@
+module.exports = Whitespace;
+
+var _ = require("lodash");
+
+function Whitespace(tokens, comments) {
+  this.tokens = _.sortBy(tokens.concat(comments), "start");
+  this.used   = [];
+}
+
+Whitespace.prototype.getNewlinesBefore = function (node) {
+  var startToken;
+  var endToken;
+  var tokens = this.tokens;
+
+  _.each(tokens, function (token, i) {
+    // this is the token this node starts with
+    if (node.start === token.start) {
+      startToken = tokens[i - 1];
+      endToken = token;
+      return false;
+    }
+  });
+
+  return this.getNewlinesBetween(startToken, endToken);
+};
+
+Whitespace.prototype.getNewlinesAfter = function (node) {
+  var startToken;
+  var endToken;
+  var tokens = this.tokens;
+
+  _.each(tokens, function (token, i) {
+    // this is the token this node ends with
+    if (node.end === token.end) {
+      startToken = token;
+      endToken = tokens[i + 1];
+      return false;
+    }
+  });
+
+  return this.getNewlinesBetween(startToken, endToken);
+};
+
+Whitespace.prototype.getNewlinesBetween = function (startToken, endToken) {
+  var start = startToken ? startToken.loc.end.line : 1;
+  var end   = endToken.loc.start.line;
+
+  var lines = 0;
+
+  for (var line = start; line < end; line++) {
+    if (!_.contains(this.used, line)) {
+      this.used.push(line);
+      lines++;
+    }
+  }
+
+  return lines;
+};

lib/6to5/index.js

@@ -1,8 +1,9 @@
-var transform = require("./transform");
+var transform = require("./transformation/transform");
+var util      = require("./util");
 var fs        = require("fs");
 var _         = require("lodash");
 
-exports.util = require("./util");
+exports.runtime = require("./runtime");
 
 exports.register = function (opts) {
   var register = require("./register");
@@ -14,6 +15,8 @@ exports.polyfill = function () {
   require("./polyfill");
 };
 
+exports.canCompile = util.canCompile;
+
 exports.transform = transform;
 
 exports.transformFile = function (filename, opts, callback) {

lib/6to5/patch.js

@@ -0,0 +1,28 @@
+var t = require("./types");
+var _ = require("lodash");
+
+var types = require("ast-types");
+var def   = types.Type.def;
+
+// Program wrapper
+def("File")
+  .bases("Node")
+  .build("program")
+  .field("program", def("Program"));
+
+// Non-standard Acorn type
+def("ParenthesizedExpression")
+  .bases("Expression")
+  .build("expression")
+  .field("expression", def("Expression"));
+
+// Same as ImportNamespaceSpecifier but `id` is `name`
+def("ImportBatchSpecifier")
+  .bases("Specifier")
+  .build("name")
+  .field("name", def("Identifier"));
+
+types.finalize();
+
+var estraverse = require("estraverse");
+_.extend(estraverse.VisitorKeys, t.VISITOR_KEYS);

lib/6to5/polyfill.js

@@ -1,3 +1,6 @@
-require("es6-symbol/implement");
+if (typeof Symbol === "undefined") {
+  require("es6-symbol/implement");
+}
+
 require("es6-shim");
-require("regenerator/runtime");
+require("regenerator-6to5/runtime");

lib/6to5/register.js

@@ -6,7 +6,7 @@ var _                = require("lodash");
 
 sourceMapSupport.install({
   retrieveSourceMap: function (source) {
-    var map = maps[source];
+    var map = maps && maps[source];
     if (map) {
       return {
         url: null,
@@ -20,17 +20,57 @@ sourceMapSupport.install({
 
 //
 
+var blacklist  = [];
+
+var blacklistTest = function (transformer, code) {
+  try {
+    if (_.isFunction(code)) {
+      code();
+    } else {
+      new Function(code);
+    }
+    blacklist.push(transformer);
+  } catch (err) {
+    if (err.name !== "SyntaxError") throw err;
+  }
+};
+
+blacklistTest("arrayComprehension", "var foo = [for (foo of bar) foo * foo];");
+//blacklistTest("generatorComprehension", "");
+blacklistTest("arrowFunctions", "var foo = x => x * x;");
+blacklistTest("classes", "class Foo {}");
+blacklistTest("computedPropertyNames", "var foo = { [foo]: bar };");
+//blacklistTest("constants", "const foo = 0;");
+blacklistTest("defaultParamaters", "var foo = function (bar = 0) {};");
+blacklistTest("destructuring", "var { x, y } = { x: 0, y: 0 };");
+blacklistTest("forOf", "for (var foo of bar) {}");
+blacklistTest("generators", "function* foo() {}");
+blacklistTest("letScoping", "let foo = 0;");
+blacklistTest("modules", 'import foo from "from";');
+blacklistTest("propertyMethodAssignment", "{ get foo() {} }");
+blacklistTest("propertyNameShorthand", "var foo = { x, y };");
+blacklistTest("restParameters", "function foo(...bar) {}");
+blacklistTest("spread", "foo(...bar);");
+blacklistTest("templateLiterals", "var foo = `foo`;");
+blacklistTest("unicodeRegex", function () { new RegExp("foo", "u"); });
+
+//
+
 var ignoreRegex = /node_modules/;
+var onlyRegex;
+var whitelist   = [];
 var exts        = {};
 var maps        = {};
 var old         = require.extensions[".js"];
 
 var loader = function (m, filename) {
-  if (ignoreRegex && ignoreRegex.test(filename)) {
+  if ((ignoreRegex && ignoreRegex.test(filename)) || (onlyRegex && !onlyRegex.test(filename))) {
     return old.apply(this, arguments);
   }
 
   var result = to5.transformFileSync(filename, {
+    whitelist: whitelist,
+    blacklist: blacklist,
     sourceMap: true
   });
 
@@ -55,12 +95,16 @@ var hookExtensions = function (_exts) {
 hookExtensions([".es6", ".js"]);
 
 module.exports = function (opts) {
+  // normalise options
   opts = opts || {};
-  if (_.isRegExp(opts)) opts = { ignoreRegex: opts };
+  if (_.isRegExp(opts)) opts = { ignore: opts };
+  if (opts.ignoreRegex != null) opts.ignore = opts.ignoreRegex;
 
-  if (opts.ignoreRegex != null) {
-    ignoreRegex = opts.ignoreRegex;
-  }
+  if (opts.only != null) onlyRegex = opts.only;
+  if (opts.ignore != null) ignoreRegex = opts.ignore;
 
   if (opts.extensions) hookExtensions(opts.extensions);
+
+  if (opts.blacklist) blacklist = opts.blacklist;
+  if (opts.whitelist) whitelist = opts.whitelist;
 };

lib/6to5/runtime.js

@@ -0,0 +1,31 @@
+var generator = require("./generation/generator");
+var util      = require("./util");
+var File      = require("./file");
+var t         = require("./types");
+var _         = require("lodash");
+
+module.exports = function (namespace) {
+  namespace = t.identifier(namespace || "to5Runtime");
+
+  var body      = [];
+  var container = t.functionExpression(null, [], t.blockStatement(body));
+  var tree      = t.program([t.expressionStatement(t.callExpression(container, []))]);
+
+  body.push(util.template("self-global", true));
+
+  body.push(t.variableDeclaration("var", [
+    t.variableDeclarator(
+      namespace,
+      t.assignmentExpression("=", t.memberExpression(t.identifier("self"), namespace), t.objectExpression([]))
+    )
+  ]));
+
+  _.each(File.declarations, function (name) {
+    var key = t.identifier(t.toIdentifier(name));
+    body.push(t.expressionStatement(
+      t.assignmentExpression("=", t.memberExpression(namespace, key), util.template(name))
+    ));
+  });
+
+  return generator(tree).code;
+};

lib/6to5/templates/apply-constructor.js

@@ -0,0 +1,5 @@
+(function (Constructor, args) {
+  var bindArgs = [null].concat(args);
+  var Factory = Constructor.bind.apply(Constructor, bindArgs);
+  return new Factory;
+});

lib/6to5/templates/class-props.js

@@ -0,0 +1,4 @@
+(function (child, staticProps, instanceProps) {
+  if (staticProps) Object.defineProperties(child, staticProps);
+  if (instanceProps) Object.defineProperties(child.prototype, instanceProps);
+})

lib/6to5/templates/let-scoping-return.js

@@ -0,0 +1 @@
+if (typeof RETURN === "object") return RETURN.v;

lib/6to5/templates/self-global.js

@@ -0,0 +1 @@
+var self = typeof global === "undefined" ? window : global;

lib/6to5/transformation/modules/amd.js

@@ -1,8 +1,8 @@
 module.exports = AMDFormatter;
 
 var CommonJSFormatter = require("./common");
-var util              = require("../util");
-var b                 = require("acorn-ast-types").builders;
+var util              = require("../../util");
+var t                 = require("../../types");
 var _                 = require("lodash");
 
 function AMDFormatter(file) {
@@ -18,21 +18,21 @@ AMDFormatter.prototype.transform = function (ast) {
 
   // build an array of module names
 
-  var names = [b.literal("exports")];
+  var names = [t.literal("exports")];
   _.each(this.ids, function (id, name) {
-    names.push(b.literal(name));
+    names.push(t.literal(name));
   });
-  names = b.arrayExpression(names);
+  names = t.arrayExpression(names);
 
   // build up define container
 
   var params = _.values(this.ids);
-  params.unshift(b.identifier("exports"));
+  params.unshift(t.identifier("exports"));
 
-  var container = b.functionExpression(null, params, b.blockStatement(body));
-  var call = b.callExpression(b.identifier("define"), [names, container]);
+  var container = t.functionExpression(null, params, t.blockStatement(body));
+  var call = t.callExpression(t.identifier("define"), [names, container]);
 
-  program.body = [b.expressionStatement(call)];
+  program.body = [t.expressionStatement(call)];
 };
 
 AMDFormatter.prototype._push = function (node) {
@@ -42,7 +42,7 @@ AMDFormatter.prototype._push = function (node) {
   if (ids[id]) {
     return ids[id];
   } else {
-    return this.ids[id] = b.identifier(this.file.generateUid(id));
+    return this.ids[id] = t.identifier(this.file.generateUid(id));
   }
 };
 
@@ -51,26 +51,26 @@ AMDFormatter.prototype.import = function (node) {
 };
 
 AMDFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
-  var key = util.getSpecifierName(specifier);
+  var key = t.getSpecifierName(specifier);
   var id  = specifier.id;
 
   // import foo from "foo";
   if (specifier.default) {
-    id = b.identifier("default");
+    id = t.identifier("default");
   }
 
   var ref;
 
-  if (specifier.type === "ImportBatchSpecifier") {
+  if (t.isImportBatchSpecifier(specifier)) {
     // import * as bar from "foo";
     ref = this._push(node);
   } else {
     // import foo from "foo";
-    ref = b.memberExpression(this._push(node), id, false);
+    ref = t.memberExpression(this._push(node), id, false);
   }
 
-  nodes.push(b.variableDeclaration("var", [
-    b.variableDeclarator(key, ref)
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(key, ref)
   ]));
 };
 

lib/6to5/transformation/modules/common.js

@@ -1,7 +1,7 @@
 module.exports = CommonJSFormatter;
 
-var util = require("../util");
-var b    = require("acorn-ast-types").builders;
+var util = require("../../util");
+var t    = require("../../types");
 
 function CommonJSFormatter(file) {
   this.file = file;
@@ -10,16 +10,18 @@ function CommonJSFormatter(file) {
 CommonJSFormatter.prototype.import = function (node, nodes) {
   // import "foo";
   nodes.push(util.template("require", {
+    //inherits: node,
+
     MODULE_NAME: node.source.raw
   }, true));
 };
 
 CommonJSFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
-  var variableName = util.getSpecifierName(specifier);
+  var variableName = t.getSpecifierName(specifier);
 
   // import foo from "foo";
   if (specifier.default) {
-    specifier.id = b.identifier("default");
+    specifier.id = t.identifier("default");
   }
 
   var templateName = "require-assign";
@@ -28,6 +30,8 @@ CommonJSFormatter.prototype.importSpecifier = function (specifier, node, nodes)
   if (specifier.type !== "ImportBatchSpecifier") templateName += "-key";
 
   nodes.push(util.template(templateName, {
+    //inherits: node.specifiers.length === 1 && node,
+
     VARIABLE_NAME: variableName,
     MODULE_NAME:   node.source.raw,
     KEY:           specifier.id
@@ -38,44 +42,73 @@ CommonJSFormatter.prototype.export = function (node, nodes) {
   var declar = node.declaration;
 
   if (node.default) {
-    util.ensureExpressionType(declar);
+    var ref = declar;
+
+    if (t.isClass(ref) || t.isFunction(ref)) {
+      if (ref.id) {
+        nodes.push(t.toStatement(ref));
+        ref = ref.id;
+      }
+    }
 
     nodes.push(util.template("exports-default", {
-      VALUE: declar
+      //inherits: node,
+
+      VALUE: ref
     }, true));
   } else {
-    var id = declar.id;
-    if (declar.type === "VariableDeclaration") {
-      id = declar.declarations[0].id;
+    var assign;
+
+    if (t.isVariableDeclaration(declar)) {
+      var decl = declar.declarations[0];
+
+      if (decl.init) {
+        decl.init = util.template("exports-assign", {
+          //inherits: node,
+
+          VALUE: decl.init,
+          KEY:   decl.id
+        });
+      }
+
+      nodes.push(declar);
+    } else {
+      assign = util.template("exports-assign", {
+        //inherits: node,
+
+        VALUE: declar.id,
+        KEY:   declar.id
+      }, true);
+
+      nodes.push(t.toStatement(declar));
+      nodes.push(assign);
+
+      if (t.isFunctionDeclaration(declar)) {
+        assign._blockHoist = true;
+      }
     }
-
-    var assign = util.template("exports-assign", {
-      VALUE: id,
-      KEY:   id
-    }, true);
-
-    nodes.push(declar);
-
-    if (declar.type === "FunctionDeclaration") {
-      assign._blockHoist = true;
-    }
-
-    nodes.push(assign);
   }
 };
 
 CommonJSFormatter.prototype._exportSpecifier = function (getRef, specifier, node, nodes) {
-  var variableName = util.getSpecifierName(specifier);
+  var variableName = t.getSpecifierName(specifier);
+
+  var inherits = false;
+  if (node.specifiers.length === 1) inherits = node;
 
   if (node.source) {
-    if (specifier.type === "ExportBatchSpecifier") {
+    if (t.isExportBatchSpecifier(specifier)) {
       // export * from "foo";
       nodes.push(util.template("exports-wildcard", {
+        //inherits: inherits,
+
         OBJECT: getRef()
       }, true));
     } else {
       // export { foo } from "test";
       nodes.push(util.template("exports-assign-key", {
+        //inherits: inherits,
+
         VARIABLE_NAME: variableName.name,
         OBJECT:        getRef(),
         KEY:           specifier.id
@@ -84,6 +117,8 @@ CommonJSFormatter.prototype._exportSpecifier = function (getRef, specifier, node
   } else {
     // export { foo };
     nodes.push(util.template("exports-assign", {
+      //inherits: inherits,
+
       VALUE: specifier.id,
       KEY:   variableName
     }, true));
@@ -92,6 +127,6 @@ CommonJSFormatter.prototype._exportSpecifier = function (getRef, specifier, node
 
 CommonJSFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
   return this._exportSpecifier(function () {
-    return b.callExpression(b.identifier("require"), [node.source]);
+    return t.callExpression(t.identifier("require"), [node.source]);
   }, specifier, node, nodes);
 };

lib/6to5/transformation/modules/ignore.js

@@ -0,0 +1,24 @@
+module.exports = IgnoreFormatter;
+
+var t = require("../../types");
+
+function IgnoreFormatter() {
+
+}
+
+IgnoreFormatter.prototype.import = function () {
+
+};
+
+IgnoreFormatter.prototype.importSpecifier = function () {
+
+};
+
+IgnoreFormatter.prototype.export = function (node, nodes) {
+  var declar = t.toStatement(node.declaration, true);
+  if (declar) nodes.push(t.inherits(declar, node));
+};
+
+IgnoreFormatter.prototype.exportSpecifier = function () {
+
+};

lib/6to5/transformation/modules/umd.js

@@ -1,8 +1,8 @@
 module.exports = UMDFormatter;
 
 var AMDFormatter = require("./amd");
-var util         = require("../util");
-var b            = require("acorn-ast-types").builders;
+var util         = require("../../util");
+var t            = require("../../types");
 var _            = require("lodash");
 
 function UMDFormatter(file) {
@@ -20,28 +20,28 @@ UMDFormatter.prototype.transform = function (ast) {
 
   var names = [];
   _.each(this.ids, function (id, name) {
-    names.push(b.literal(name));
+    names.push(t.literal(name));
   });
 
   // factory
 
   var ids  = _.values(this.ids);
-  var args = [b.identifier("exports")].concat(ids);
+  var args = [t.identifier("exports")].concat(ids);
 
-  var factory = b.functionExpression(null, args, b.blockStatement(body));
+  var factory = t.functionExpression(null, args, t.blockStatement(body));
 
   // runner
 
   var runner = util.template("umd-runner-body", {
-    AMD_ARGUMENTS: b.arrayExpression([b.literal("exports")].concat(names)),
+    AMD_ARGUMENTS: t.arrayExpression([t.literal("exports")].concat(names)),
 
     COMMON_ARGUMENTS: names.map(function (name) {
-      return b.callExpression(b.identifier("require"), [name]);
+      return t.callExpression(t.identifier("require"), [name]);
     })
   });
 
   //
 
-  var call = b.callExpression(runner, [factory]);
-  program.body = [b.expressionStatement(call)];
+  var call = t.callExpression(runner, [factory]);
+  program.body = [t.expressionStatement(call)];
 };

lib/6to5/transformation/transform.js

@@ -1,74 +1,14 @@
 module.exports = transform;
 
 var Transformer = require("./transformer");
-var sourceMap   = require("source-map");
-var recast      = require("acorn-recast");
-var File        = require("./file");
-var util        = require("./util");
+var File        = require("../file");
 var _           = require("lodash");
 
 function transform(code, opts) {
-  opts = opts || {};
-  code = (code || "") + "";
-
   var file = new File(opts);
   return file.parse(code);
 }
 
-transform.test = function (task, assert) {
-  var actual = task.actual;
-  var expect = task.expect;
-  var opts   = task.options;
-  var exec   = task.exec;
-
-  var getOpts = function (filename) {
-    return _.merge({ filename: filename }, opts);
-  };
-
-  var execCode = exec.code.trim();
-  var result;
-
-  if (execCode) {
-    result = transform(execCode, getOpts(exec.filename));
-    execCode = result.code;
-
-    require("./polyfill");
-    var fn = new Function("assert", execCode);
-    fn(assert);
-  } else {
-    var actualCode = actual.code.trim();
-    var expectCode = expect.code.trim();
-
-    var printOpts = { tabWidth: 2 };
-
-    result     = transform(actualCode, getOpts(actual.filename));
-    actualCode = recast.prettyPrint(result.ast, printOpts).code;
-
-    var expectAst    = util.parse(expect, expectCode);
-    var expectResult = recast.prettyPrint(expectAst, printOpts);
-    expectCode       = expectResult.code;
-
-    assert.equal(actualCode, expectCode);
-  }
-
-  if (task.sourceMap) {
-    assert.deepEqual(task.sourceMap, result.map);
-  }
-
-  if (task.sourceMappings) {
-    var consumer = new sourceMap.SourceMapConsumer(result.map);
-
-    _.each(task.sourceMappings, function (mapping, i) {
-      var generated = mapping.generated;
-      var original  = mapping.original;
-
-      var pos = consumer.originalPositionFor(generated);
-      var msg = "source mapping " + i + " - generated: " + generated.line + ":" + generated.column;
-      assert.equal(pos.line + ":" + pos.column, original.line + ":" + original.column, msg);
-    });
-  }
-};
-
 transform._ensureTransformerNames = function (type, keys) {
   _.each(keys, function (key) {
     if (!_.has(transform.transformers, key)) {
@@ -77,42 +17,47 @@ transform._ensureTransformerNames = function (type, keys) {
   });
 };
 
-transform.transformers = {
-  modules:                  require("./transformers/modules"),
-  computedPropertyNames:    require("./transformers/computed-property-names"),
-  propertyNameShorthand:    require("./transformers/property-name-shorthand"),
-  constants:                require("./transformers/constants"),
-  arrayComprehension:       require("./transformers/array-comprehension"),
-  arrowFunctions:           require("./transformers/arrow-functions"),
-  classes:                  require("./transformers/classes"),
-  spread:                   require("./transformers/spread"),
-  templateLiterals:         require("./transformers/template-literals"),
-  propertyMethodAssignment: require("./transformers/property-method-assignment"),
-  defaultParameters:        require("./transformers/default-parameters"),
-  letScoping:               require("./transformers/let-scoping"),
-  restParameters:           require("./transformers/rest-parameters"),
-  destructuring:            require("./transformers/destructuring"),
-  forOf:                    require("./transformers/for-of"),
-  unicodeRegex:             require("./transformers/unicode-regex"),
-  generators:               require("./transformers/generators"),
-
-  react:                    require("./transformers/react"),
-  jsx:                      require("./transformers/jsx"),
-
-  _aliasFunctions:          require("./transformers/_alias-functions"),
-  _blockHoist:              require("./transformers/_block-hoist"),
-  _declarations:            require("./transformers/_declarations"),
-  _moduleFormatter:         require("./transformers/_module-formatter"),
-
-  useStrict:                require("./transformers/use-strict")
-};
+transform.transformers = {};
 
 transform.moduleFormatters = {
   common: require("./modules/common"),
+  ignore: require("./modules/ignore"),
   amd:    require("./modules/amd"),
   umd:    require("./modules/umd")
 };
 
-_.each(transform.transformers, function (transformer, key) {
+_.each({
+  modules:                  require("./transformers/modules"),
+  propertyNameShorthand:    require("./transformers/property-name-shorthand"),
+  constants:                require("./transformers/constants"),
+  arrayComprehension:       require("./transformers/array-comprehension"),
+  generatorComprehension:   require("./transformers/generator-comprehension"),
+  arrowFunctions:           require("./transformers/arrow-functions"),
+  classes:                  require("./transformers/classes"),
+
+  _propertyLiterals:        require("./transformers/_property-literals"),
+  computedPropertyNames:    require("./transformers/computed-property-names"),
+
+  spread:                   require("./transformers/spread"),
+  templateLiterals:         require("./transformers/template-literals"),
+  propertyMethodAssignment: require("./transformers/property-method-assignment"),
+  defaultParameters:        require("./transformers/default-parameters"),
+  restParameters:           require("./transformers/rest-parameters"),
+  destructuring:            require("./transformers/destructuring"),
+  letScoping:               require("./transformers/let-scoping"),
+  forOf:                    require("./transformers/for-of"),
+  unicodeRegex:             require("./transformers/unicode-regex"),
+
+  react:                    require("./transformers/react"),
+
+  _aliasFunctions:          require("./transformers/_alias-functions"),
+  _blockHoist:              require("./transformers/_block-hoist"),
+  _declarations:            require("./transformers/_declarations"),
+
+  generators:               require("./transformers/generators"),
+  useStrict:                require("./transformers/use-strict"),
+
+  _moduleFormatter:         require("./transformers/_module-formatter")
+}, function (transformer, key) {
   transform.transformers[key] = new Transformer(key, transformer);
 });

lib/6to5/transformation/transformer.js

@@ -1,6 +1,7 @@
 module.exports = Transformer;
 
-var traverse = require("./traverse");
+var traverse = require("../traverse");
+var t        = require("../types");
 var _        = require("lodash");
 
 function Transformer(key, transformer) {
@@ -14,6 +15,7 @@ Transformer.normalise = function (transformer) {
   }
 
   _.each(transformer, function (fns, type) {
+    if (type[0] === "_") return;
     if (_.isFunction(fns)) fns = { enter: fns };
     transformer[type] = fns;
   });
@@ -27,14 +29,18 @@ Transformer.prototype.transform = function (file) {
   var transformer = this.transformer;
   var ast         = file.ast;
 
-  if (transformer.ast && transformer.ast.enter) {
-    transformer.ast.enter(ast, file);
-  }
+  var astRun = function (key) {
+    if (transformer.ast && transformer.ast[key]) {
+      transformer.ast[key](ast, file);
+    }
+  };
+
+  astRun("enter");
 
   var build = function (exit) {
-    return function (node, parent) {
+    return function (node, parent, scope) {
       // add any node type aliases that exist
-      var types = [node.type].concat(traverse.aliases[node.type] || []);
+      var types = [node.type].concat(t.ALIAS_KEYS[node.type] || []);
 
       var fns = transformer.all;
 
@@ -49,7 +55,7 @@ Transformer.prototype.transform = function (file) {
       if (exit) fn = fns.exit;
       if (!fn) return;
 
-      return fn(node, parent, file);
+      return fn(node, parent, file, scope);
     };
   };
 
@@ -58,19 +64,20 @@ Transformer.prototype.transform = function (file) {
     exit:  build(true)
   });
 
-  if (transformer.ast && transformer.ast.exit) {
-    transformer.ast.exit(ast, file);
-  }
+  astRun("exit");
 };
 
 Transformer.prototype.canRun = function (file) {
   var opts = file.opts;
+  var key  = this.key;
 
   var blacklist = opts.blacklist;
-  if (blacklist.length && _.contains(blacklist, this.key)) return false;
+  if (blacklist.length && _.contains(blacklist, key)) return false;
 
-  var whitelist = opts.whitelist;
-  if (whitelist.length && !_.contains(whitelist, this.key)) return false;
+  if (key[0] !== "_") {
+    var whitelist = opts.whitelist;
+    if (whitelist.length && !_.contains(whitelist, key)) return false;
+  }
 
   return true;
 };

lib/6to5/transformation/transformers/_alias-functions.js

@@ -0,0 +1,82 @@
+var traverse = require("../../traverse");
+var t        = require("../../types");
+
+var go = function (getBody, node, file, scope) {
+  var argumentsId;
+  var thisId;
+
+  var getArgumentsId = function () {
+    return argumentsId = argumentsId || t.identifier(file.generateUid("arguments", scope));
+  };
+
+  var getThisId = function () {
+    return thisId = thisId || t.identifier(file.generateUid("this", scope));
+  };
+
+  // traverse the function and find all alias functions so we can alias
+  // `arguments` and `this` if necessary
+  traverse(node, function (node) {
+    if (!node._aliasFunction) {
+      if (t.isFunction(node)) {
+        // stop traversal of this node as it'll be hit again by this transformer
+        return false;
+      } else {
+        return;
+      }
+    }
+
+    // traverse all child nodes of this function and find `arguments` and `this`
+    traverse(node, function (node, parent) {
+      if (t.isFunction(node) && !node._aliasFunction) {
+        return false;
+      }
+
+      if (node._ignoreAliasFunctions) return;
+
+      var getId;
+
+      if (t.isIdentifier(node) && node.name === "arguments") {
+        getId = getArgumentsId;
+      } else if (t.isThisExpression(node)) {
+        getId = getThisId;
+      } else {
+        return;
+      }
+
+      if (t.isReferenced(node, parent)) return getId();
+    });
+
+    return false;
+  });
+
+  var body;
+
+  var pushDeclaration = function (id, init) {
+    body = body || getBody();
+    body.unshift(t.variableDeclaration("var", [
+      t.variableDeclarator(id, init)
+    ]));
+  };
+
+  if (argumentsId) {
+    pushDeclaration(argumentsId, t.identifier("arguments"));
+  }
+
+  if (thisId) {
+    pushDeclaration(thisId, t.identifier("this"));
+  }
+};
+
+exports.Program = function (node, parent, file, scope) {
+  go(function () {
+    return node.body;
+  }, node, file, scope);
+};
+
+exports.FunctionDeclaration =
+exports.FunctionExpression = function (node, parent, file, scope) {
+  go(function () {
+    t.ensureBlock(node);
+    return node.body.body;
+  }, node, file, scope);
+};

lib/6to5/transformation/transformers/_declarations.js

@@ -1,12 +1,12 @@
-var b = require("acorn-ast-types").builders;
+var t = require("../../types");
 var _ = require("lodash");
 
 module.exports = function (ast, file) {
   var body = ast.program.body;
 
   _.each(file.declarations, function (declar) {
-    body.unshift(b.variableDeclaration("var", [
-      b.variableDeclarator(declar.uid, declar.node)
+    body.unshift(t.variableDeclaration("var", [
+      t.variableDeclarator(declar.uid, declar.node)
     ]));
   });
 };

lib/6to5/transformation/transformers/_property-literals.js

@@ -0,0 +1,15 @@
+var esutils = require("esutils");
+var t       = require("../../types");
+var _       = require("lodash");
+
+exports.Property = function (node) {
+  // ignore key literals that are valid identifiers
+  var key = node.key;
+  if (t.isLiteral(key) && _.isString(key.value) && esutils.keyword.isIdentifierName(key.value)) {
+    key.type = "Identifier";
+    key.name = key.value;
+    delete key.value;
+
+    node.computed = false;
+  }
+};

lib/6to5/transformation/transformers/array-comprehension.js

@@ -0,0 +1,81 @@
+var util = require("../../util");
+var t    = require("../../types");
+var _    = require("lodash");
+
+var singleArrayExpression = function (node) {
+  var block = node.blocks[0];
+
+  var templateName = "array-expression-comprehension-map";
+  if (node.filter) templateName = "array-expression-comprehension-filter";
+
+  var result = util.template(templateName, {
+    STATEMENT: node.body,
+    FILTER:    node.filter,
+    ARRAY:     block.right,
+    KEY:       block.left
+  });
+
+  _.each([result.callee.object, result], function (call) {
+    if (t.isCallExpression(call)) {
+      call.arguments[0]._aliasFunction = true;
+    }
+  });
+
+  return result;
+};
+
+var multiple = function (node, file) {
+  var uid = file.generateUid("arr");
+
+  var container = util.template("array-comprehension-container", {
+    KEY: uid
+  });
+  container.callee.expression._aliasFunction = true;
+
+  var block = container.callee.expression.body;
+  var body  = block.body;
+
+  var returnStatement = body.pop();
+
+  body.push(exports._build(node, function () {
+    return util.template("array-push", {
+      STATEMENT: node.body,
+      KEY:       uid
+    }, true);
+  }));
+  body.push(returnStatement);
+
+  return container;
+};
+
+exports._build = function (node, buildBody) {
+  var self = node.blocks.shift();
+  if (!self) return;
+
+  var child = exports._build(node, buildBody);
+  if (!child) {
+    // last item
+    child = buildBody();
+
+    // add a filter as this is our final stop
+    if (node.filter) {
+      child = t.ifStatement(node.filter, t.blockStatement([child]));
+    }
+  }
+
+  return t.forOfStatement(
+    t.variableDeclaration("var", [t.variableDeclarator(self.left)]),
+    self.right,
+    t.blockStatement([child])
+  );
+};
+
+exports.ComprehensionExpression = function (node, parent, file) {
+  if (node.generator) return;
+
+  if (node.blocks.length === 1 && t.isArrayExpression(node.blocks[0].right)) {
+    return singleArrayExpression(node);
+  } else {
+    return multiple(node, file);
+  }
+};

lib/6to5/transformation/transformers/arrow-functions.js

@@ -1,9 +1,9 @@
-var util = require("../util");
+var t = require("../../types");
 
 exports.ArrowFunctionExpression = function (node) {
-  util.ensureBlock(node);
+  t.ensureBlock(node);
 
-  node._aliasFunction = "arrows";
+  node._aliasFunction = true;
   node.expression = false;
   node.type = "FunctionExpression";
 

lib/6to5/transformation/transformers/classes.js

@@ -0,0 +1,262 @@
+var traverse = require("../../traverse");
+var util     = require("../../util");
+var t        = require("../../types");
+var _        = require("lodash");
+
+exports.ClassDeclaration = function (node, parent, file, scope) {
+  return t.variableDeclaration("var", [
+    t.variableDeclarator(node.id, new Class(node, file, scope).run())
+  ]);
+};
+
+exports.ClassExpression = function (node, parent, file, scope) {
+  return new Class(node, file, scope).run();
+};
+
+var getMemberExpressionObject = function (node) {
+  while (t.isMemberExpression(node)) {
+    node = node.object;
+  }
+  return node;
+};
+
+/**
+ * Description
+ *
+ * @param {Node} node
+ * @param {File} file
+ * @param {Scope} scope
+ */
+
+function Class(node, file, scope) {
+  this.scope = scope;
+  this.node  = node;
+  this.file  = file;
+
+  this.instanceMutatorMap = {};
+  this.staticMutatorMap   = {};
+  this.hasConstructor     = false;
+  this.className          = node.id || t.identifier(file.generateUid("class", scope));
+  this.superName          = node.superClass;
+}
+
+/**
+ * Description
+ *
+ * @returns {Array}
+ */
+
+Class.prototype.run = function () {
+  var superClassArgument = this.superName;
+  var superClassCallee   = this.superName;
+  var superName          = this.superName;
+  var className          = this.className;
+  var file               = this.file;
+
+  if (superName) {
+    if (t.isMemberExpression(superName)) {
+      superClassArgument = superClassCallee = getMemberExpressionObject(superName);
+    } else if (!t.isIdentifier(superName)) {
+      superClassArgument = superName;
+      superClassCallee   = superName = t.identifier(file.generateUid("ref", this.scope));
+    }
+  }
+
+  this.superName = superName;
+
+  var container = util.template("class", {
+    CLASS_NAME: className
+  });
+
+  var block       = container.callee.expression.body;
+  var body        = this.body = block.body;
+  var constructor = this.constructor = body[0].declarations[0].init;
+
+  if (this.node.id) constructor.id = className;
+
+  var returnStatement = body.pop();
+
+  if (superName) {
+    body.push(t.expressionStatement(t.callExpression(file.addDeclaration("extends"), [className, superName])));
+
+    container.arguments.push(superClassArgument);
+    container.callee.expression.params.push(superClassCallee);
+  }
+
+  this.buildBody();
+
+  if (body.length === 1) {
+    // only a constructor so no need for a closure container
+    return constructor;
+  } else {
+    body.push(returnStatement);
+    return container;
+  }
+};
+
+/**
+ * Description
+ */
+
+Class.prototype.buildBody = function () {
+  var constructor = this.constructor;
+  var className   = this.className;
+  var superName   = this.superName;
+  var classBody   = this.node.body.body;
+  var body        = this.body;
+  var self        = this;
+
+  _.each(classBody, function (node) {
+    self.replaceInstanceSuperReferences(node);
+
+    if (node.key.name === "constructor") {
+      self.pushConstructor(node);
+    } else {
+      self.pushMethod(node);
+    }
+  });
+
+  if (!this.hasConstructor && superName) {
+    constructor.body.body.push(util.template("class-super-constructor-call", {
+      SUPER_NAME: superName
+    }, true));
+  }
+
+  var instanceProps;
+  var staticProps;
+
+  if (!_.isEmpty(this.instanceMutatorMap)) {
+    var protoId = util.template("prototype-identifier", {
+      CLASS_NAME: className
+    });
+
+    instanceProps = util.buildDefineProperties(this.instanceMutatorMap, protoId);
+  }
+
+  if (!_.isEmpty(this.staticMutatorMap)) {
+    staticProps = util.buildDefineProperties(this.staticMutatorMap, className);
+  }
+
+  if (instanceProps || staticProps) {
+    staticProps = staticProps || t.literal(null);
+
+    var args = [className, staticProps];
+    if (instanceProps) args.push(instanceProps);
+
+    body.push(t.expressionStatement(
+      t.callExpression(this.file.addDeclaration("class-props"), args)
+    ));
+  }
+};
+
+/**
+ * Push a method to it's respective mutatorMap.
+ *
+ * @param {Node} node MethodDefinition
+ */
+
+Class.prototype.pushMethod = function (node) {
+  var methodName = node.key;
+
+  var mutatorMap = this.instanceMutatorMap;
+  if (node.static) mutatorMap = this.staticMutatorMap;
+
+  var kind = node.kind;
+
+  if (kind === "") {
+    kind = "value";
+    util.pushMutatorMap(mutatorMap, methodName, "writable", t.identifier("true"));
+  }
+
+  util.pushMutatorMap(mutatorMap, methodName, kind, node);
+};
+
+/**
+ * Given a `methodNode`, produce a `MemberExpression` super class reference.
+ *
+ * @param {Node} methodNode MethodDefinition
+ * @param {Node} node Identifier
+ * @param {Node} parent
+ *
+ * @returns {Node}
+ */
+
+Class.prototype.superIdentifier = function (methodNode, id, parent) {
+  var methodName = methodNode.key;
+  var superName  = this.superName || t.identifier("Function");
+
+  if (parent.property === id) {
+    return;
+  } else if (t.isCallExpression(parent, { callee: id })) {
+    // super(); -> ClassName.prototype.MethodName.call(this);
+    parent.arguments.unshift(t.thisExpression());
+
+    if (methodName.name === "constructor") {
+      // constructor() { super(); }
+      return t.memberExpression(superName, t.identifier("call"));
+    } else {
+      id = superName;
+
+      // foo() { super(); }
+      if (!methodNode.static) {
+        id = t.memberExpression(id, t.identifier("prototype"));
+      }
+
+      id = t.memberExpression(id, methodName, methodNode.computed);
+      return t.memberExpression(id, t.identifier("call"));
+    }
+  } else if (t.isMemberExpression(parent) && !methodNode.static) {
+    // super.test -> ClassName.prototype.test
+    return t.memberExpression(superName, t.identifier("prototype"));
+  } else {
+    return superName;
+  }
+};
+
+/**
+ * Replace all `super` references with a reference to our `superClass`.
+ *
+ * @param {Node} methodNode MethodDefinition
+ */
+
+Class.prototype.replaceInstanceSuperReferences = function (methodNode) {
+  var method = methodNode.value;
+  var self = this;
+
+  traverse(method, function (node, parent) {
+    if (t.isIdentifier(node, { name: "super" })) {
+      return self.superIdentifier(methodNode, node, parent);
+    } else if (t.isCallExpression(node)) {
+      var callee = node.callee;
+      if (!t.isMemberExpression(callee)) return;
+      if (callee.object.name !== "super") return;
+
+      // super.test(); -> ClassName.prototype.MethodName.call(this);
+      callee.property = t.memberExpression(callee.property, t.identifier("call"));
+      node.arguments.unshift(t.thisExpression());
+    }
+  });
+};
+
+/**
+ * Replace the constructor body of our class.
+ *
+ * @param {Node} method MethodDefinition
+ */
+
+Class.prototype.pushConstructor = function (method) {
+  if (method.kind !== "") {
+    throw this.file.errorWithNode(method, "illegal kind for constructor method");
+  }
+
+  var construct = this.constructor;
+  var fn        = method.value;
+
+  this.hasConstructor = true;
+  t.inherits(construct, fn);
+
+  construct.defaults = fn.defaults;
+  construct.params   = fn.params;
+  construct.body     = fn.body;
+  construct.rest     = fn.rest;
+};

lib/6to5/transformation/transformers/computed-property-names.js

@@ -1,5 +1,5 @@
-var util = require("../util");
-var b    = require("acorn-ast-types").builders;
+var util = require("../../util");
+var t    = require("../../types");
 var _    = require("lodash");
 
 exports.ObjectExpression = function (node, parent, file) {
@@ -26,17 +26,17 @@ exports.ObjectExpression = function (node, parent, file) {
     OBJECT: node
   });
 
-  var containerCallee = container.callee;
+  var containerCallee = container.callee.expression;
   var containerBody = containerCallee.body.body;
 
-  containerCallee._aliasFunction = "arrows";
+  containerCallee._aliasFunction = true;
 
   _.each(computed, function (prop) {
     containerBody.unshift(
-      b.expressionStatement(
-        b.assignmentExpression(
+      t.expressionStatement(
+        t.assignmentExpression(
           "=",
-          b.memberExpression(objId, prop.key, true),
+          t.memberExpression(objId, prop.key, true),
           prop.value
         )
       )

lib/6to5/transformation/transformers/constants.js

@@ -0,0 +1,49 @@
+var traverse = require("../../traverse");
+var t        = require("../../types");
+var _        = require("lodash");
+
+exports.Program =
+exports.BlockStatement =
+exports.ForInStatement =
+exports.ForOfStatement =
+exports.ForStatement = function (node, parent, file) {
+  var constants = [];
+
+  var check = function (node, names) {
+    _.each(names, function (name) {
+      if (constants.indexOf(name) >= 0) {
+        throw file.errorWithNode(node, name + " is read-only");
+      }
+    });
+  };
+
+  var getIds = function (node) {
+    return t.getIds(node, false, ["MemberExpression"]);
+  };
+
+  _.each(node.body, function (child) {
+    if (child && t.isVariableDeclaration(child, { kind: "const" })) {
+      _.each(child.declarations, function (declar) {
+        _.each(getIds(declar), function (name) {
+          check(declar, [name]);
+          constants.push(name);
+        });
+
+        declar._ignoreConstant = true;
+      });
+
+      child._ignoreConstant = true;
+      child.kind = "let";
+    }
+  });
+
+  if (!constants.length) return;
+
+  traverse(node, function (child) {
+    if (child._ignoreConstant) return;
+
+    if (t.isVariableDeclarator(child) || t.isDeclaration(child) || t.isAssignmentExpression(child)) {
+      check(child, getIds(child));
+    }
+  });
+};

lib/6to5/transformation/transformers/default-parameters.js

@@ -1,9 +1,10 @@
-var util = require("../util");
+var util = require("../../util");
+var t    = require("../../types");
 var _    = require("lodash");
 
 exports.Function = function (node) {
-  if (!node.defaults.length) return;
-  util.ensureBlock(node);
+  if (!node.defaults || !node.defaults.length) return;
+  t.ensureBlock(node);
 
   _.each(node.defaults, function (def, i) {
     if (!def) return;

lib/6to5/transformation/transformers/destructuring.js

@@ -0,0 +1,198 @@
+var t = require("../../types");
+var _ = require("lodash");
+
+var buildVariableAssign = function (kind, id, init) {
+  if (kind === false) {
+    return t.expressionStatement(t.assignmentExpression("=", id, init));
+  } else {
+    return t.variableDeclaration(kind, [
+      t.variableDeclarator(id, init)
+    ]);
+  }
+};
+
+var push = function (kind, nodes, elem, parentId) {
+  if (t.isObjectPattern(elem)) {
+    pushObjectPattern(kind, nodes, elem, parentId);
+  } else if (t.isArrayPattern(elem)) {
+    pushArrayPattern(kind, nodes, elem, parentId);
+  } else if (t.isMemberExpression(elem)) {
+    nodes.push(buildVariableAssign(false, elem, parentId));
+  } else {
+    nodes.push(buildVariableAssign(kind, elem, parentId));
+  }
+};
+
+var pushObjectPattern = function (kind, nodes, pattern, parentId) {
+  _.each(pattern.properties, function (prop) {
+    var pattern2   = prop.value;
+    var patternId2 = t.memberExpression(parentId, prop.key);
+
+    if (t.isPattern(pattern2)) {
+      push(kind, nodes, pattern2, patternId2);
+    } else {
+      nodes.push(buildVariableAssign(kind, pattern2, patternId2));
+    }
+  });
+};
+
+var pushArrayPattern = function (kind, nodes, pattern, parentId) {
+  _.each(pattern.elements, function (elem, i) {
+    if (!elem) return;
+
+    var newPatternId;
+
+    if (t.isSpreadElement(elem)) {
+      newPatternId = t.callExpression(t.memberExpression(parentId, t.identifier("slice")), [t.literal(i)]);
+      elem = elem.argument;
+    } else {
+      newPatternId = t.memberExpression(parentId, t.literal(i), true);
+    }
+
+    push(kind, nodes, elem, newPatternId);
+  });
+};
+
+var pushPattern = function (opts) {
+  var kind = opts.kind;
+  var nodes = opts.nodes;
+  var pattern = opts.pattern;
+  var parentId = opts.id;
+  var file = opts.file;
+  var scope = opts.scope;
+
+  if (!t.isMemberExpression(parentId) && !t.isIdentifier(parentId)) {
+    var key = t.identifier(file.generateUid("ref", scope));
+
+    nodes.push(t.variableDeclaration("var", [
+      t.variableDeclarator(key, parentId)
+    ]));
+
+    parentId = key;
+  }
+
+  push(kind, nodes, pattern, parentId);
+};
+
+exports.ForInStatement =
+exports.ForOfStatement = function (node, parent, file, scope) {
+  var declar = node.left;
+  if (!t.isVariableDeclaration(declar)) return;
+
+  var pattern = declar.declarations[0].id;
+  if (!t.isPattern(pattern)) return;
+
+  var key = t.identifier(file.generateUid("ref", scope));
+  node.left = t.variableDeclaration(declar.kind, [
+    t.variableDeclarator(key, null)
+  ]);
+
+  var nodes = [];
+
+  push(declar.kind, nodes, pattern, key);
+
+  t.ensureBlock(node);
+
+  var block = node.body;
+  block.body = nodes.concat(block.body);
+};
+
+exports.Function = function (node, parent, file, scope) {
+  var nodes = [];
+
+  var hasDestructuring = false;
+
+  node.params = node.params.map(function (pattern) {
+    if (!t.isPattern(pattern)) return pattern;
+
+    hasDestructuring = true;
+    var parentId = t.identifier(file.generateUid("ref", scope));
+
+    pushPattern({
+      kind:    "var",
+      nodes:   nodes,
+      pattern: pattern,
+      id:      parentId,
+      file:    file,
+      scope:   scope
+    });
+
+    return parentId;
+  });
+
+  if (!hasDestructuring) return;
+
+  t.ensureBlock(node);
+
+  var block = node.body;
+  block.body = nodes.concat(block.body);
+};
+
+exports.ExpressionStatement = function (node, parent, file, scope) {
+  var expr = node.expression;
+  if (expr.type !== "AssignmentExpression") return;
+
+  if (!t.isPattern(expr.left)) return;
+
+  var nodes = [];
+
+  var ref = t.identifier(file.generateUid("ref", scope));
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(ref, expr.right)
+  ]));
+
+  push(false, nodes, expr.left, ref);
+
+  return nodes;
+};
+
+exports.VariableDeclaration = function (node, parent, file, scope) {
+  if (t.isForInStatement(parent) || t.isForOfStatement(parent)) return;
+
+  var nodes = [];
+
+  var hasPattern = false;
+  _.each(node.declarations, function (declar) {
+    if (t.isPattern(declar.id)) {
+      hasPattern = true;
+      return false;
+    }
+  });
+  if (!hasPattern) return;
+
+  _.each(node.declarations, function (declar) {
+    var patternId = declar.init;
+    var pattern   = declar.id;
+    if (t.isPattern(pattern) && patternId) {
+      pushPattern({
+        kind:    node.kind,
+        nodes:   nodes,
+        pattern: pattern,
+        id:      patternId,
+        file:    file,
+        scope:   scope
+      });
+    } else {
+      nodes.push(buildVariableAssign(node.kind, declar.id, declar.init));
+    }
+  });
+
+  if (!t.isProgram(parent) && !t.isBlockStatement(parent)) {
+    var declar;
+
+    _.each(nodes, function (node) {
+      declar = declar || t.variableDeclaration(node.kind, []);
+
+      if (!t.isVariableDeclaration(node) && declar.kind !== node.kind) {
+        throw file.errorWithNode(node, "Cannot use this node within the current parent");
+      }
+
+      declar.declarations = declar.declarations.concat(node.declarations);
+    });
+
+    return declar;
+  }
+
+  return nodes;
+};
+

lib/6to5/transformation/transformers/for-of.js

@@ -0,0 +1,34 @@
+var util = require("../../util");
+var t    = require("../../types");
+
+exports.ForOfStatement = function (node, parent, file, scope) {
+  var left = node.left;
+  var declar;
+
+  var stepKey = t.identifier(file.generateUid("step", scope));
+  var stepValueId = t.memberExpression(stepKey, t.identifier("value"));
+
+  if (t.isIdentifier(left)) {
+    declar = t.expressionStatement(t.assignmentExpression("=", left, stepValueId));
+  } else if (t.isVariableDeclaration(left)) {
+    declar = t.variableDeclaration(left.kind, [
+      t.variableDeclarator(left.declarations[0].id, stepValueId)
+    ]);
+  } else {
+    return;
+  }
+
+  var node2 = util.template("for-of", {
+    ITERATOR_KEY: file.generateUid("iterator", scope),
+    STEP_KEY:     stepKey,
+    OBJECT:       node.right
+  });
+
+  t.ensureBlock(node);
+
+  var block = node2.body;
+  block.body.push(declar);
+  block.body = block.body.concat(node.body.body);
+
+  return node2;
+};

lib/6to5/transformation/transformers/generator-comprehension.js

@@ -0,0 +1,15 @@
+var arrayComprehension = require("./array-comprehension");
+var t                  = require("../../types");
+
+exports.ComprehensionExpression = function (node) {
+  if (!node.generator) return;
+
+  var body = [];
+  var container = t.functionExpression(null, [], t.blockStatement(body), true);
+
+  body.push(arrayComprehension._build(node, function () {
+    return t.expressionStatement(t.yieldExpression(node.body));
+  }));
+
+  return t.callExpression(container, []);
+};

lib/6to5/transformation/transformers/generators.js

@@ -0,0 +1,3 @@
+var regenerator = require("regenerator-6to5");
+
+module.exports = regenerator.transform;

lib/6to5/transformation/transformers/let-scoping.js

@@ -0,0 +1,431 @@
+var traverse = require("../../traverse");
+var util     = require("../../util");
+var t        = require("../../types");
+var _        = require("lodash");
+
+var isLet = function (node) {
+  if (!t.isVariableDeclaration(node)) return false;
+  if (node._let) return true;
+  if (node.kind !== "let") return false;
+
+  node._let = true;
+  node.kind = "var";
+  return true;
+};
+
+var isVar = function (node) {
+  return t.isVariableDeclaration(node, { kind: "var" }) && !isLet(node);
+};
+
+var standardiseLets = function (declars) {
+  _.each(declars, function (declar) {
+    delete declar._let;
+  });
+};
+
+exports.VariableDeclaration = function (node) {
+  isLet(node);
+};
+
+exports.For = function (node, parent, file, scope) {
+  var init = node.left || node.init;
+  if (isLet(init)) {
+    t.ensureBlock(node);
+    node.body._letDeclars = [init];
+  }
+
+  if (t.isLabeledStatement(parent)) {
+    // set label so `run` has access to it
+    node.label = parent.label;
+  }
+
+  var letScoping = new LetScoping(node, node.body, parent, file, scope);
+  letScoping.run();
+
+  if (node.label && !t.isLabeledStatement(parent)) {
+    // we've been given a label so let's wrap ourselves
+    return t.labeledStatement(node.label, node);
+  }
+};
+
+exports.BlockStatement = function (block, parent, file, scope) {
+  if (!t.isFor(parent)) {
+    var letScoping = new LetScoping(false, block, parent, file, scope);
+    letScoping.run();
+  }
+};
+
+/**
+ * Description
+ *
+ * @param {Boolean|Node} forParent
+ * @param {Node} block
+ * @param {Node} parent
+ * @param {File} file
+ * @param {Scope} scope
+ */
+
+function LetScoping(forParent, block, parent, file, scope) {
+  this.forParent = forParent;
+  this.parent    = parent;
+  this.scope     = scope;
+  this.block     = block;
+  this.file      = file;
+
+  this.letReferences = {};
+  this.body          = [];
+  this.info          = this.getInfo();
+}
+
+/**
+ * Start the ball rolling.
+ */
+
+LetScoping.prototype.run = function () {
+  var block = this.block;
+
+  if (block._letDone) return;
+  block._letDone = true;
+
+  // this is a block within a `Function` so we can safely leave it be
+  if (t.isFunction(this.parent)) return;
+
+  // this block has no let references so let's clean up
+  if (!this.info.keys.length) return this.noClosure();
+
+  // returns whether or not there are any outside let references within any
+  // functions
+  var referencesInClosure = this.getLetReferences();
+
+  // no need for a closure so let's clean up
+  if (!referencesInClosure) return this.noClosure();
+
+  // if we're inside of a for loop then we search to see if there are any
+  // `break`s, `continue`s, `return`s etc
+  this.has = this.checkFor();
+
+  // hoist var references to retain scope
+  this.hoistVarDeclarations();
+
+  // set let references to plain var references
+  standardiseLets(this.info.declarators);
+
+  // turn letReferences into an array
+  var letReferences = _.values(this.letReferences);
+
+  // build the closure that we're going to wrap the block with
+  var fn = t.functionExpression(null, letReferences, t.blockStatement(block.body));
+  fn._aliasFunction = true;
+
+  // replace the current block body with the one we're going to build
+  block.body = this.body;
+
+  // change upper scope references with their uid if they have one
+  var params = this.getParams(letReferences);
+
+  // build a call and a unique id that we can assign the return value to
+  var call = t.callExpression(fn, params);
+  var ret  = t.identifier(this.file.generateUid("ret", this.scope));
+
+  this.build(ret, call);
+};
+
+/**
+ * There are no let references accessed within a closure so we can just traverse
+ * through this block and replace all references that exist in a high scope to
+ * their uids.
+ */
+
+LetScoping.prototype.noClosure = function () {
+  var replacements = this.info.duplicates;
+  var declarators  = this.info.declarators;
+  var block        = this.block;
+
+  standardiseLets(declarators);
+
+  if (_.isEmpty(replacements)) return;
+
+  traverse(block, function (node, parent) {
+    if (!t.isIdentifier(node)) return;
+    if (!t.isReferenced(node, parent)) return;
+    node.name = replacements[node.name] || node.name;
+  });
+};
+
+/**
+ * Description
+ *
+ * @returns {Object}
+ */
+
+LetScoping.prototype.getInfo = function () {
+  var block = this.block;
+  var scope = this.scope;
+  var file  = this.file;
+
+  var opts = {
+    // array of `Identifier` names of let variables that appear lexically out of
+    // this scope but should be accessible - eg. `ForOfStatement`.left
+    outsideKeys: [],
+
+    // array of let `VariableDeclarator`s that are a part of this block
+    declarators: block._letDeclars || [],
+
+    // object of duplicate ids and their aliases - if there's an `Identifier`
+    // name that's used in an upper scope we generate a unique id and replace
+    // all references with it
+    duplicates:  {},
+
+    // array of `Identifier` names of let variables that are accessible within
+    // the current block
+    keys:        []
+  };
+
+  _.each(opts.declarators, function (declar) {
+    opts.declarators.push(declar);
+
+    var keys = t.getIds(declar);
+    opts.outsideKeys = opts.outsideKeys.concat(keys);
+    opts.keys = opts.keys.concat(keys);
+  });
+
+  _.each(block.body, function (declar) {
+    if (!isLet(declar)) return;
+
+    _.each(t.getIds(declar, true), function (id, key) {
+      var has = scope.parentGet(key);
+
+      if (has && has !== id) {
+        // there's a variable with this exact name in an upper scope so we need
+        // to generate a new name
+        opts.duplicates[key] = id.name = file.generateUid(key, scope);
+      }
+
+      opts.keys.push(key);
+    });
+  });
+
+  return opts;
+};
+
+/**
+ * If we're inside of a `For*Statement` then traverse it and check if it has one
+ * of the following node types `ReturnStatement`, `BreakStatement`,
+ * `ContinueStatement` and replace it with a return value we can track later on.
+ *
+ * @returns {Object}
+ */
+
+LetScoping.prototype.checkFor = function () {
+  var has = {
+    hasContinue: false,
+    hasReturn:   false,
+    hasBreak:    false,
+  };
+
+  if (this.forParent) {
+    traverse(this.block, function (node) {
+      var replace;
+
+      if (t.isFunction(node) || t.isFor(node)) {
+        return false;
+      } else if (t.isBreakStatement(node) && !node.label) {
+        has.hasBreak = true;
+        replace = t.returnStatement(t.literal("break"));
+      } else if (t.isContinueStatement(node) && !node.label) {
+        has.hasContinue = true;
+        replace = t.returnStatement(t.literal("continue"));
+      } else if (t.isReturnStatement(node)) {
+        has.hasReturn = true;
+        replace = t.returnStatement(t.objectExpression([
+          t.property("init", t.identifier("v"), node.argument || t.identifier("undefined"))
+        ]));
+      }
+
+      if (replace) return t.inherits(replace, node);
+    });
+  }
+
+  return has;
+};
+
+/**
+ * Hoist all var declarations in this block to before it so they retain scope
+ * once we wrap everything is in a closure.
+ */
+
+LetScoping.prototype.hoistVarDeclarations = function () {
+  var self = this;
+  traverse(this.block, function (node) {
+    if (t.isForStatement(node)) {
+      if (isVar(node.init)) {
+        node.init = t.sequenceExpression(self.pushDeclar(node.init));
+      }
+    } else if (t.isFor(node)) {
+      if (isVar(node.left)) {
+        node.left = node.left.declarations[0].id;
+      }
+    } else if (isVar(node)) {
+      return self.pushDeclar(node).map(t.expressionStatement);
+    } else if (t.isFunction(node)) {
+      return false;
+    }
+  });
+};
+
+/**
+ * Build up a parameter list that we'll call our closure wrapper with, replacing
+ * all duplicate ids with their uid.
+ *
+ * @param {Array} params
+ * @returns {Array}
+ */
+
+LetScoping.prototype.getParams = function (params) {
+  var info = this.info;
+  params = _.cloneDeep(params);
+  _.each(params, function (param) {
+    param.name = info.duplicates[param.name] || param.name;
+  });
+  return params;
+};
+
+/**
+ * Get all let references within this block. Stopping whenever we reach another
+ * block.
+ */
+
+LetScoping.prototype.getLetReferences = function () {
+  var closurify = false;
+  var self = this;
+
+  // traverse through this block, stopping on functions and checking if they
+  // contain any outside let references
+  traverse(this.block, function (node, parent, scope) {
+    if (t.isFunction(node)) {
+      traverse(node, function (node, parent) {
+        // not an identifier so we have no use
+        if (!t.isIdentifier(node)) return;
+
+        // not a direct reference
+        if (!t.isReferenced(node, parent)) return;
+
+        // this scope has a variable with the same name so it couldn't belong
+        // to our let scope
+        if (scope.hasOwn(node.name)) return;
+
+        closurify = true;
+
+        // this key doesn't appear just outside our scope
+        if (!_.contains(self.info.outsideKeys, node.name)) return;
+
+        // push this badboy
+        self.letReferences[node.name] = node;
+      });
+
+      return false;
+    } else if (t.isFor(node)) {
+      return false;
+    }
+  });
+
+  return closurify;
+};
+
+/**
+ * Turn a `VariableDeclaration` into an array of `AssignmentExpressions` with
+ * their declarations hoisted to before the closure wrapper.
+ *
+ * @param {Node} node VariableDeclaration
+ * @returns {Array}
+ */
+
+LetScoping.prototype.buildPushDeclar = function (node) {
+  this.body.push(t.variableDeclaration(node.kind, node.declarations.map(function (declar) {
+    return t.variableDeclarator(declar.id);
+  })));
+
+  var replace = [];
+
+  _.each(node.declarations, function (declar) {
+    if (!declar.init) return;
+
+    var expr = t.assignmentExpression("=", declar.id, declar.init);
+    replace.push(t.inherits(expr, declar));
+  });
+
+  return replace;
+};
+
+/**
+ * Push the closure to the body.
+ *
+ * @param {Node} ret Identifier
+ * @param {Node} call CallExpression
+ */
+
+LetScoping.prototype.build = function (ret, call) {
+  var has = this.has;
+  if (has.hasReturn || has.hasBreak || has.hasContinue) {
+    this.buildHas(ret, call);
+  } else {
+    this.body.push(t.expressionStatement(call));
+  }
+};
+
+/**
+ * Description
+ *
+ * @param {Node} ret Identifier
+ * @param {Node} call CallExpression
+ */
+
+LetScoping.prototype.buildHas = function (ret, call) {
+  var body = this.body;
+
+  body.push(t.variableDeclaration("var", [
+    t.variableDeclarator(ret, call)
+  ]));
+
+  var forParent = this.forParent;
+  var retCheck;
+  var has = this.has;
+  var cases = [];
+
+  if (has.hasReturn) {
+    // typeof ret === "object"
+    retCheck = util.template("let-scoping-return", {
+      RETURN: ret
+    });
+  }
+
+  if (has.hasBreak || has.hasContinue) {
+    // ensure that the parent has a label as we're building a switch and we
+    // need to be able to access it
+    var label = forParent.label = forParent.label || t.identifier(this.file.generateUid("loop", this.scope));
+
+    if (has.hasBreak) {
+      cases.push(t.switchCase(t.literal("break"), [t.breakStatement(label)]));
+    }
+
+    if (has.hasContinue) {
+      cases.push(t.switchCase(t.literal("continue"), [t.continueStatement(label)]));
+    }
+
+    if (has.hasReturn) {
+      cases.push(t.switchCase(null, [retCheck]));
+    }
+
+    if (cases.length === 1) {
+      var single = cases[0];
+      body.push(t.ifStatement(
+        t.binaryExpression("===", ret, single.test),
+        single.consequent[0]
+      ));
+    } else {
+      body.push(t.switchStatement(ret, cases));
+    }
+  } else {
+    if (has.hasReturn) body.push(retCheck);
+  }
+};

lib/6to5/transformation/transformers/property-method-assignment.js

@@ -1,4 +1,4 @@
-var util = require("../util");
+var util = require("../../util");
 var _    = require("lodash");
 
 exports.Property = function (node) {
@@ -10,7 +10,7 @@ exports.ObjectExpression = function (node, parent, file) {
 
   node.properties = node.properties.filter(function (prop) {
     if (prop.kind === "get" || prop.kind === "set") {
-      util.pushMutatorMap(mutatorMap, prop.key.name, prop.kind, prop.value);
+      util.pushMutatorMap(mutatorMap, prop.key, prop.kind, prop.value);
       return false;
     } else {
       return true;
@@ -24,6 +24,9 @@ exports.ObjectExpression = function (node, parent, file) {
   return util.template("object-define-properties-closure", {
     KEY: objId,
     OBJECT: node,
-    CONTENT: util.buildDefineProperties(mutatorMap, objId).expression
+    CONTENT: util.template("object-define-properties", {
+      OBJECT: objId,
+      PROPS:  util.buildDefineProperties(mutatorMap)
+    })
   });
 };

lib/6to5/transformation/transformers/react.js

@@ -0,0 +1,182 @@
+// Based upon the excellent jsx-transpiler by Ingvar Stepanyan (RReverser)
+// https://github.com/RReverser/jsx-transpiler
+
+// jsx
+
+var esutils = require("esutils");
+var t       = require("../../types");
+var _       = require("lodash");
+
+exports.XJSIdentifier = function (node) {
+  if (esutils.keyword.isIdentifierName(node.name)) {
+    node.type = "Identifier";
+  } else {
+    return t.literal(node.name);
+  }
+};
+
+exports.XJSNamespacedName = function (node, parent, file) {
+  throw file.errorWithNode(node, "Namespace tags are not supported. ReactJSX is not XML.");
+};
+
+exports.XJSMemberExpression = {
+  exit: function (node) {
+    node.computed = t.isLiteral(node.property);
+    node.type = "MemberExpression";
+  }
+};
+
+exports.XJSExpressionContainer = function (node) {
+  return node.expression;
+};
+
+exports.XJSAttribute = {
+  exit: function (node) {
+    var value = node.value || t.literal(true);
+    return t.property("init", node.name, value);
+  }
+};
+
+exports.XJSOpeningElement = {
+  exit: function (node) {
+    var tagExpr = node.name;
+    var args = [];
+
+    var tagName;
+    if (t.isIdentifier(tagExpr)) {
+      tagName = tagExpr.name;
+    } else if (t.isLiteral(tagExpr)) {
+      tagName = tagExpr.value;
+    }
+
+    if (tagName && (/[a-z]/.exec(tagName[0]) || _.contains(tagName, "-"))) {
+      args.push(t.literal(tagName));
+    } else {
+      args.push(tagExpr);
+    }
+
+    var props = node.attributes;
+    if (props.length) {
+      var _props = [];
+      var objs = [];
+
+      var pushProps = function () {
+        if (!_props.length) return;
+
+        objs.push(t.objectExpression(_props));
+        _props = [];
+      };
+
+      while (props.length) {
+        var prop = props.shift();
+        if (t.isXJSSpreadAttribute(prop)) {
+          pushProps();
+          objs.push(prop.argument);
+        } else {
+          _props.push(prop);
+        }
+      }
+
+      pushProps();
+
+      if (objs.length === 1) {
+        props = objs[0];
+      } else {
+        if (!t.isObjectExpression(objs[0])) {
+          objs.unshift(t.objectExpression([]));
+        }
+
+        props = t.callExpression(
+          t.memberExpression(t.identifier("React"), t.identifier("__spread")),
+          objs
+        );
+      }
+    } else {
+      props = t.literal(null);
+    }
+
+    args.push(props);
+
+    tagExpr = t.memberExpression(t.identifier("React"), t.identifier("createElement"));
+    return t.callExpression(tagExpr, args);
+  }
+};
+
+exports.XJSElement = {
+  exit: function (node) {
+    var callExpr = node.openingElement;
+
+    var childrenToRender = node.children.filter(function(child) {
+      return !(t.isLiteral(child) && _.isString(child.value) && child.value.match(/^[ \t]*[\r\n][ \t\r\n]*$/));
+    });
+
+    _.each(childrenToRender, function (child) {
+      callExpr.arguments.push(child);
+    });
+
+    return t.inherits(callExpr, node);
+  }
+};
+
+// display names
+
+var addDisplayName = function (id, call) {
+  if (!call || !t.isCallExpression(call)) return;
+
+  var callee = call.callee;
+  if (!t.isMemberExpression(callee)) return;
+
+  // not React
+  var obj = callee.object;
+  if (!t.isIdentifier(obj, { name: "React" })) return;
+
+  // not createClass
+  var prop = callee.property;
+  if (!t.isIdentifier(prop, { name: "createClass" })) return;
+
+  // no arguments
+  var args = call.arguments;
+  if (args.length !== 1) return;
+
+  // not an object
+  var first = args[0];
+  if (!t.isObjectExpression(first)) return;
+
+  var props = first.properties;
+  var safe = true;
+
+  _.each(props, function (prop) {
+    if (t.isIdentifier(prop.key, { name: "displayName" })) {
+      return safe = false;
+    }
+  });
+
+  if (safe) {
+    props.unshift(t.property("init", t.identifier("displayName"), t.literal(id)));
+  }
+};
+
+exports.AssignmentExpression =
+exports.Property =
+exports.VariableDeclarator = function (node) {
+  var left, right;
+
+  if (t.isAssignmentExpression(node)) {
+    left = node.left;
+    right = node.right;
+  } else if (t.isProperty(node)) {
+    left = node.key;
+    right = node.value;
+  } else if (t.isVariableDeclarator(node)) {
+    left = node.id;
+    right = node.init;
+  }
+
+  if (t.isMemberExpression(left)) {
+    left = left.property;
+  }
+
+  if (t.isIdentifier(left)) {
+    addDisplayName(left.name, right);
+  }
+};

lib/6to5/transformation/transformers/rest-parameters.js

@@ -0,0 +1,24 @@
+var util = require("../../util");
+var t    = require("../../types");
+
+exports.Function = function (node, parent, file) {
+  if (!node.rest) return;
+
+  var rest = node.rest;
+  delete node.rest;
+
+  var templateName = "arguments-slice-assign";
+  if (node.params.length) templateName += "-arg";
+
+  t.ensureBlock(node);
+
+  var template = util.template(templateName, {
+    SLICE_KEY: file.addDeclaration("slice"),
+    VARIABLE_NAME: rest,
+    SLICE_ARG: t.literal(node.params.length)
+  });
+
+  template.declarations[0].init.arguments[0]._ignoreAliasFunctions = true;
+
+  node.body.body.unshift(template);
+};

lib/6to5/transformation/transformers/spread.js

@@ -0,0 +1,113 @@
+var t = require("../../types");
+var _ = require("lodash");
+
+var getSpreadLiteral = function (spread) {
+  var literal = spread.argument;
+  if (!t.isArrayExpression(literal)) {
+    literal = t.callExpression(
+      t.memberExpression(t.identifier("Array"), t.identifier("from")),
+      [literal]
+    );
+  }
+  return literal;
+};
+
+var hasSpread = function (nodes) {
+  var has = false;
+  _.each(nodes, function (node) {
+    if (t.isSpreadElement(node)) {
+      has = true;
+      return false;
+    }
+  });
+  return has;
+};
+
+var build = function (props) {
+  var nodes = [];
+
+  var _props = [];
+
+  var push = function () {
+    if (!_props.length) return;
+    nodes.push(t.arrayExpression(_props));
+    _props = [];
+  };
+
+  _.each(props, function (prop) {
+    if (t.isSpreadElement(prop)) {
+      push();
+      nodes.push(getSpreadLiteral(prop));
+    } else {
+      _props.push(prop);
+    }
+  });
+
+  push();
+
+  return nodes;
+};
+
+exports.ArrayExpression = function (node) {
+  var elements = node.elements;
+  if (!hasSpread(elements)) return;
+
+  var nodes = build(elements);
+  var first = nodes.shift();
+
+  if (!nodes.length) return first;
+
+  return t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes);
+};
+
+exports.CallExpression = function (node) {
+  var args = node.arguments;
+  if (!hasSpread(args)) return;
+
+  var contextLiteral = t.literal(null);
+
+  node.arguments = [];
+
+  var nodes = build(args);
+  var first = nodes.shift();
+
+  if (nodes.length) {
+    node.arguments.push(t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes));
+  } else {
+    node.arguments.push(first);
+  }
+
+  var callee = node.callee;
+
+  if (t.isMemberExpression(callee)) {
+    contextLiteral = callee.object;
+
+    if (callee.computed) {
+      callee.object = t.memberExpression(callee.object, callee.property, true);
+      callee.property = t.identifier("apply");
+      callee.computed = false;
+    } else {
+      callee.property = t.memberExpression(callee.property, t.identifier("apply"));
+    }
+  } else {
+    node.callee = t.memberExpression(node.callee, t.identifier("apply"));
+  }
+
+  node.arguments.unshift(contextLiteral);
+};
+
+exports.NewExpression = function (node, parent, file) {
+  var args = node.arguments;
+  if (!hasSpread(args)) return;
+
+  var nodes = build(args);
+  var first = nodes.shift();
+
+  if (nodes.length) {
+    args = t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes);
+  } else {
+    args = first;
+  }
+
+  return t.callExpression(file.addDeclaration("apply-constructor"), [node.callee, args]);
+};

lib/6to5/transformation/transformers/template-literals.js

@@ -1,8 +1,8 @@
-var b = require("acorn-ast-types").builders;
+var t = require("../../types");
 var _ = require("lodash");
 
 var buildBinaryExpression = function (left, right) {
-  return b.binaryExpression("+", left, right);
+  return t.binaryExpression("+", left, right);
 };
 
 exports.TaggedTemplateExpression = function (node) {
@@ -10,31 +10,34 @@ exports.TaggedTemplateExpression = function (node) {
   var quasi = node.quasi;
 
   var strings = quasi.quasis.map(function (elem) {
-    return b.literal(elem.value.raw);
+    return t.literal(elem.value.raw);
   });
-  args.push(b.arrayExpression(strings));
+  args.push(t.arrayExpression(strings));
 
   _.each(quasi.expressions, function (expr) {
     args.push(expr);
   });
 
-  return b.callExpression(node.tag, args);
+  return t.callExpression(node.tag, args);
 };
 
 exports.TemplateLiteral = function (node) {
   var nodes = [];
 
   _.each(node.quasis, function (elem) {
-    nodes.push(b.literal(elem.value.raw));
+    nodes.push(t.literal(elem.value.raw));
 
     var expr = node.expressions.shift();
-    if (expr) nodes.push(expr);
+    if (expr) {
+      if (t.isBinary(expr)) expr = t.parenthesizedExpression(expr);
+      nodes.push(expr);
+    }
   });
 
   if (nodes.length > 1) {
     // remove redundant '' at the end of the expression
     var last = _.last(nodes);
-    if (last.type === "Literal" && last.value === "") nodes.pop();
+    if (t.isLiteral(last, { value: "" })) nodes.pop();
 
     var root = buildBinaryExpression(nodes.shift(), nodes.shift());
 

lib/6to5/transformation/transformers/unicode-regex.js

@@ -1,5 +1,4 @@
 var rewritePattern = require("regexpu/rewrite-pattern");
-var b              = require("acorn-ast-types").builders;
 var _              = require("lodash");
 
 exports.Literal = function (node) {
@@ -10,6 +9,6 @@ exports.Literal = function (node) {
   if (!_.contains(regex.flags, "u")) return;
   _.pull(flags, "u");
 
-  var pattern = rewritePattern(regex.pattern, regex.flags);
-  return b.literal(new RegExp(pattern, flags.join("")));
+  regex.pattern = rewritePattern(regex.pattern, regex.flags);
+  regex.flags   = flags.join("");
 };

lib/6to5/transformation/transformers/use-strict.js

@@ -0,0 +1,12 @@
+var t = require("../../types");
+
+module.exports = function (ast) {
+  var body = ast.program.body;
+  var first = body[0];
+
+  var noStrict = !first || !t.isExpressionStatement(first) || !t.isLiteral(first.expression) || first.expression.value !== "use strict";
+
+  if (noStrict) {
+    body.unshift(t.expressionStatement(t.literal("use strict")));
+  }
+};

lib/6to5/transformers/_alias-functions.js

@@ -1,84 +0,0 @@
-var traverse = require("../traverse");
-var util     = require("../util");
-var b        = require("acorn-ast-types").builders;
-
-var go = function (getBody, node, file) {
-  var argumentsId;
-  var thisId;
-
-  var getArgumentsId = function () {
-    return argumentsId = argumentsId || b.identifier(file.generateUid("arguments"));
-  };
-
-  var getThisId = function () {
-    return thisId = thisId || b.identifier(file.generateUid("this"));
-  };
-
-  // traverse the function and find all alias functions so we can alias
-  // arguments and this if neccesary
-  traverse(node, function (node) {
-    var _aliasFunction = node._aliasFunction;
-    if (!_aliasFunction) {
-      if (traverse.isFunction(node)) {
-        // stop traversal of this node as it'll be hit again by this transformer
-        return false;
-      } else {
-        return;
-      }
-    }
-
-    // traverse all child nodes of this function and find arguments and this
-    traverse(node, function (node, parent) {
-      if (_aliasFunction === "arrows") {
-        if (traverse.isFunction(node) && node._aliasFunction !== "arrows") {
-          return false;
-        }
-      }
-
-      var getId;
-
-      if (node.type === "Identifier" && node.name === "arguments") {
-        getId = getArgumentsId;
-      } else if (node.type === "ThisExpression") {
-        getId = getThisId;
-      } else {
-        return;
-      }
-
-      if (util.isReferenced(node, parent)) return getId();
-    });
-
-    return false;
-  });
-
-  var body;
-
-  var pushDeclaration = function (id, init) {
-    body = body || getBody();
-    body.unshift(b.variableDeclaration("var", [
-      b.variableDeclarator(id, init)
-    ]));
-  };
-
-  if (argumentsId) {
-    pushDeclaration(argumentsId, b.identifier("arguments"));
-  }
-
-  if (thisId) {
-    pushDeclaration(thisId, b.identifier("this"));
-  }
-};
-
-exports.Program = function (node, parent, file) {
-  go(function () {
-    return node.body;
-  }, node, file);
-};
-
-exports.FunctionDeclaration =
-exports.FunctionExpression = function (node, parent, file) {
-  go(function () {
-    util.ensureBlock(node);
-    return node.body.body;
-  }, node, file);
-};

lib/6to5/transformers/array-comprehension.js

@@ -1,75 +0,0 @@
-var util = require("../util");
-var b    = require("acorn-ast-types").builders;
-
-var single = function (node) {
-  var block = node.blocks[0];
-
-  var templateName = "array-comprehension-map";
-  if (node.filter) templateName = "array-comprehension-filter";
-
-  var result = util.template(templateName, {
-    STATEMENT: node.body,
-    FILTER:    node.filter,
-    ARRAY:     block.right,
-    KEY:       block.left
-  });
-  result._aliasFunction = true;
-  return result;
-};
-
-var multiple = function (node, file) {
-  var uid = file.generateUid("arr");
-
-  var container = util.template("array-comprehension-container", {
-    KEY: uid
-  });
-  container._aliasFunction = true;
-
-  var block = container.callee.body;
-  var body  = block.body;
-
-  var returnStatement = body.pop();
-
-  var build = function () {
-    var self = node.blocks.shift();
-    if (!self) return;
-
-    var child = build();
-    if (!child) {
-      // last item
-
-      child = util.template("array-push", {
-        STATEMENT: node.body,
-        KEY:       uid
-      }, true);
-
-      // add a filter as this is our final stop
-      if (node.filter) {
-        child = b.ifStatement(node.filter, b.blockStatement([child]));
-      }
-    }
-
-    var container2 = util.template("array-comprehension-for-each", {
-      ARRAY: self.right,
-      KEY:   self.left
-    }, true);
-
-    // set function body
-    container2.expression.arguments[0].body.body = [child];
-
-    return container2;
-  };
-
-  body.push(build());
-  body.push(returnStatement);
-
-  return container;
-};
-
-exports.ComprehensionExpression = function (node, parent, file) {
-  if (node.blocks.length === 1) {
-    return single(node);
-  } else {
-    return multiple(node, file);
-  }
-};

lib/6to5/transformers/classes.js

@@ -1,173 +0,0 @@
-var traverse = require("../traverse");
-var util     = require("../util");
-var b        = require("acorn-ast-types").builders;
-var _        = require("lodash");
-
-exports.ClassDeclaration = function (node, parent, file) {
-  return b.variableDeclaration("var", [
-    b.variableDeclarator(node.id, buildClass(node, file))
-  ]);
-};
-
-exports.ClassExpression = function (node, parent, file) {
-  return buildClass(node, file);
-};
-
-var getMemberExpressionObject = function (node) {
-  while (node.type === "MemberExpression") {
-    node = node.object;
-  }
-  return node;
-};
-
-var buildClass = function (node, file) {
-  var superName = node.superClass;
-  var className = node.id || b.identifier(file.generateUid("class"));
-
-  var superClassArgument = node.superClass;
-  var superClassCallee   = node.superClass;
-
-  if (superName) {
-    if (superName.type === "MemberExpression") {
-      superClassArgument = superClassCallee = getMemberExpressionObject(superName);
-    } else if (superName.type !== "Identifier") {
-      superClassArgument = superName;
-      superClassCallee = superName = b.identifier(file.generateUid("ref"));
-    }
-  }
-
-  var container = util.template("class", {
-    CLASS_NAME: className
-  });
-
-  var block     = container.callee.body;
-  var body      = block.body;
-
-  if (node.id) {
-    body[0].declarations[0].init.id = className;
-  }
-
-  var returnStatement = body.pop();
-
-  if (superName) {
-    body.push(b.expressionStatement(b.callExpression(file.addDeclaration("extends"), [className, superName])));
-
-    container.arguments.push(superClassArgument);
-    container.callee.params.push(superClassCallee);
-  }
-
-  buildClassBody(body, className, superName, node);
-
-  body.push(returnStatement);
-
-  return container;
-};
-
-var buildClassBody = function (body, className, superName, node) {
-  var instanceMutatorMap = {};
-  var staticMutatorMap   = {};
-  var hasConstructor     = false;
-
-  var construct = body[0].declarations[0].init;
-  var classBody = node.body.body;
-
-  _.each(classBody, function (node) {
-    var methodName = node.key.name;
-    var method     = node.value;
-
-    replaceInstanceSuperReferences(superName, method, node, methodName);
-
-    if (methodName === "constructor") {
-      if (node.kind === "") {
-        hasConstructor = true;
-        addConstructor(construct, method);
-      } else {
-        throw util.errorWithNode(node, "unknown kind for constructor method");
-      }
-    } else {
-      var mutatorMap = instanceMutatorMap;
-      if (node.static) mutatorMap = staticMutatorMap;
-
-      var kind = node.kind;
-
-      if (kind === "") {
-        kind = "value";
-        util.pushMutatorMap(mutatorMap, methodName, "writable", b.identifier("true"));
-      }
-
-      util.pushMutatorMap(mutatorMap, methodName, kind, node);
-    }
-  });
-
-  if (!hasConstructor && superName) {
-    construct.body.body.push(util.template("class-super-constructor-call", {
-      SUPER_NAME: superName
-    }, true));
-  }
-
-  if (!_.isEmpty(instanceMutatorMap)) {
-    var protoId = util.template("prototype-identifier", {
-      CLASS_NAME: className
-    });
-
-    body.push(util.buildDefineProperties(instanceMutatorMap, protoId));
-  }
-
-  if (!_.isEmpty(staticMutatorMap)) {
-    body.push(util.buildDefineProperties(staticMutatorMap, className));
-  }
-};
-
-var superIdentifier = function (superName, methodNode, methodName, node, parent) {
-  if (parent.property === node) {
-    return;
-  } else if (parent.type === "CallExpression" && parent.callee === node) {
-    // super(); -> ClassName.prototype.MethodName.call(this);
-    parent.arguments.unshift(b.thisExpression());
-
-    if (methodName === "constructor") {
-      // constructor() { super(); }
-      return b.memberExpression(superName, b.identifier("call"), false);
-    } else {
-      node = superName;
-
-      // foo() { super(); }
-      if (!methodNode.static) {
-        node = b.memberExpression(node, b.identifier("prototype"), false);
-      }
-
-      node = b.memberExpression(node, b.identifier(methodName), false);
-      return b.memberExpression(node, b.identifier("call"), false);
-    }
-  } else if (parent.type === "MemberExpression" && !methodNode.static) {
-    // super.test -> ClassName.prototype.test
-    return b.memberExpression(superName, b.identifier("prototype"), false);
-  } else {
-    return superName;
-  }
-};
-
-var replaceInstanceSuperReferences = function (superName, method, methodNode, methodName) {
-  superName = superName || b.identifier("Function");
-
-  traverse(method, function (node, parent) {
-    if (node.type === "Identifier" && node.name === "super") {
-      return superIdentifier(superName, methodNode, methodName, node, parent);
-    } else if (node.type === "CallExpression") {
-      var callee = node.callee;
-      if (callee.type !== "MemberExpression") return;
-      if (callee.object.name !== "super") return;
-
-      //  super.test(); -> ClassName.prototype.MethodName.call(this);
-      callee.property.name = callee.property.name + ".call";
-      node.arguments.unshift(b.thisExpression());
-    }
-  });
-};
-
-var addConstructor = function (construct, method) {
-  construct.defaults = method.defaults;
-  construct.params   = method.params;
-  construct.body     = method.body;
-  construct.rest     = method.rest;
-};

lib/6to5/transformers/constants.js

@@ -1,45 +0,0 @@
-var traverse = require("../traverse");
-var util     = require("../util");
-var _        = require("lodash");
-
-exports.Program =
-exports.BlockStatement =
-exports.ForInStatement =
-exports.ForOfStatement =
-exports.ForStatement = function (node) {
-  var constants = [];
-
-  var check = function (node, name) {
-    if (constants.indexOf(name) >= 0) {
-      throw util.errorWithNode(node, name + " is read-only");
-    }
-  };
-
-  _.each(node.body, function (child) {
-    if (child && child.type === "VariableDeclaration" && child.kind === "const") {
-      _.each(child.declarations, function (declar) {
-        _.each(util.getIds(declar.id), function (name) {
-          check(declar, name);
-          constants.push(name);
-        });
-
-        declar._ignoreConstant = true;
-      });
-      child.kind = "let";
-    }
-  });
-
-  if (!constants.length) return;
-
-  traverse(node, function (child) {
-    if (child._ignoreConstant) return;
-
-    if (child.type === "VariableDeclarator" ||
-        child.type === "FunctionDeclaration" ||
-        child.type === "ClassDeclaration") {
-      check(child, child.id.name);
-    } else if (child.type === "AssignmentExpression") {
-      check(child, child.left.name);
-    }
-  });
-};

lib/6to5/transformers/destructuring.js

@@ -1,155 +0,0 @@
-var traverse = require("../traverse");
-var util     = require("../util");
-var b        = require("acorn-ast-types").builders;
-var _        = require("lodash");
-
-var buildVariableAssign = function (kind, id, init) {
-  if (kind === false) {
-    return b.expressionStatement(b.assignmentExpression("=", id, init));
-  } else {
-    return b.variableDeclaration(kind, [
-      b.variableDeclarator(id, init)
-    ]);
-  }
-};
-
-var push = function (kind, nodes, pattern, parentId) {
-  if (pattern.type === "ObjectPattern") {
-    pushObjectPattern(kind, nodes, pattern, parentId);
-  } else if (pattern.type === "ArrayPattern") {
-    pushArrayPattern(kind, nodes, pattern, parentId);
-  }
-};
-
-var pushObjectPattern = function (kind, nodes, pattern, parentId) {
-  _.each(pattern.properties, function (prop) {
-    var pattern2   = prop.value;
-    var patternId2 = b.memberExpression(parentId, prop.key, false);
-
-    if (traverse.isPattern(pattern2)) {
-      push(kind, nodes, pattern2, patternId2);
-    } else {
-      nodes.push(buildVariableAssign(kind, pattern2, patternId2));
-    }
-  });
-};
-
-var pushArrayPattern = function (kind, nodes, pattern, parentId) {
-  _.each(pattern.elements, function (elem, i) {
-    if (!elem) return;
-
-    var newPatternId = b.memberExpression(parentId, b.literal(i), true);
-
-    if (elem.type === "Identifier") {
-      nodes.push(buildVariableAssign(kind, elem, newPatternId));
-    } else if (elem.type === "MemberExpression") {
-      nodes.push(buildVariableAssign(false, elem, newPatternId));
-    } else {
-      push(kind, nodes, elem, newPatternId);
-    }
-  });
-};
-
-var pushPattern = function (kind, nodes, pattern, parentId, file) {
-  if (parentId.type !== "MemberExpression" && parentId.type !== "Identifier") {
-    var key = b.identifier(file.generateUid("ref"));
-
-    nodes.push(b.variableDeclaration("var", [
-      b.variableDeclarator(key, parentId)
-    ]));
-
-    parentId = key;
-  }
-
-  push(kind, nodes, pattern, parentId);
-};
-
-exports.ForInStatement =
-exports.ForOfStatement = function (node, parent, file) {
-  var declar = node.left;
-  if (declar.type !== "VariableDeclaration") return;
-
-  var pattern = declar.declarations[0].id;
-  if (!traverse.isPattern(pattern)) return;
-
-  var key = b.identifier(file.generateUid("ref"));
-  node.left = b.variableDeclaration(declar.kind, [
-    b.variableDeclarator(key, null)
-  ]);
-
-  var nodes = [];
-
-  push(declar.kind, nodes, pattern, key);
-
-  util.ensureBlock(node);
-
-  var block = node.body;
-  block.body = nodes.concat(block.body);
-};
-
-exports.Function = function (node, parent, file) {
-  var nodes = [];
-
-  var hasDestructuring = false;
-
-  node.params = node.params.map(function (pattern) {
-    if (!traverse.isPattern(pattern)) return pattern;
-
-    hasDestructuring = true;
-    var parentId = b.identifier(file.generateUid("ref"));
-    pushPattern("var", nodes, pattern, parentId, file);
-    return parentId;
-  });
-
-  if (!hasDestructuring) return;
-
-  util.ensureBlock(node);
-
-  var block = node.body;
-  block.body = nodes.concat(block.body);
-};
-
-exports.ExpressionStatement = function (node, parent, file) {
-  var expr = node.expression;
-  if (expr.type !== "AssignmentExpression") return;
-
-  if (!traverse.isPattern(expr.left)) return;
-
-  var nodes = [];
-
-  var ref = b.identifier(file.generateUid("ref"));
-  nodes.push(b.variableDeclaration("var", [
-    b.variableDeclarator(ref, expr.right)
-  ]));
-
-  push(false, nodes, expr.left, ref);
-
-  return nodes;
-};
-
-exports.VariableDeclaration = function (node, parent, file) {
-  if (parent.type === "ForInStatement") return;
-
-  var nodes = [];
-
-  var hasPattern = false;
-  _.each(node.declarations, function (declar) {
-    if (traverse.isPattern(declar.id)) {
-      hasPattern = true;
-      return false;
-    }
-  });
-  if (!hasPattern) return;
-
-  _.each(node.declarations, function (declar) {
-    var patternId = declar.init;
-    var pattern   = declar.id;
-    if (traverse.isPattern(pattern) && patternId) {
-      pushPattern(node.kind, nodes, pattern, patternId, file);
-    } else {
-      nodes.push(buildVariableAssign(node.kind, declar.id, declar.init));
-    }
-  });
-
-  return nodes;
-};

lib/6to5/transformers/for-of.js

@@ -1,34 +0,0 @@
-var util = require("../util");
-var b    = require("acorn-ast-types").builders;
-
-exports.ForOfStatement = function (node, parent, file) {
-  var left = node.left;
-  var declar;
-
-  var stepKey = b.identifier(file.generateUid("step"));
-  var stepValueId = b.memberExpression(stepKey, b.identifier("value"), false);
-
-  if (left.type === "Identifier") {
-    declar = b.expressionStatement(b.assignmentExpression("=", left, stepValueId));
-  } else if (left.type === "VariableDeclaration") {
-    declar = b.variableDeclaration(left.kind, [
-      b.variableDeclarator(left.declarations[0].id, stepValueId)
-    ]);
-  } else {
-    return;
-  }
-
-  var node2 = util.template("for-of", {
-    ITERATOR_KEY: file.generateUid("iterator"),
-    STEP_KEY:     stepKey,
-    OBJECT:       node.right
-  });
-
-  util.ensureBlock(node);
-
-  var block = node2.body;
-  block.body.push(declar);
-  block.body = block.body.concat(node.body.body);
-
-  return node2;
-};

lib/6to5/transformers/generators.js

@@ -1,3 +0,0 @@
-var regenerator = require("regenerator");
-
-module.exports = regenerator.transform;

lib/6to5/transformers/jsx/index.js

@@ -1,97 +0,0 @@
-// Based upon the excellent jsx-transpiler by Ingvar Stepanyan (RReverser)
-// https://github.com/RReverser/jsx-transpiler
-
-var esutils = require("esutils");
-var b       = require("acorn-ast-types").builders;
-var _       = require("lodash");
-
-var JSX_ANNOTATION_REGEX = /^\*\s*@jsx\s+([^\s]+)/;
-var KNOWN_TAGS           = require("./known-tags");
-
-exports.Program = function (node, parent, file) {
-  var jsx = "React.DOM";
-
-  // looking for namespace annotation
-  _.each(node.comments, function (comment) {
-    if (!comment.possiblyLeading) return;
-
-    var matches = JSX_ANNOTATION_REGEX.exec(comment.value);
-    if (matches) jsx = matches[1];
-  });
-
-  // prebuilding AST node
-  file.jsx = jsx.split(".").map(b.identifier).reduce(function (object, property) {
-    return b.memberExpression(object, property, false);
-  });
-};
-
-exports.XJSIdentifier = function (node) {
-  if (esutils.keyword.isIdentifierName(node.name)) {
-    node.type = "Identifier";
-  } else {
-    return b.literal(node.name);
-  }
-};
-
-exports.XJSNamespacedName = function () {
-  throw new Error("Namespace tags are not supported. ReactJSX is not XML.");
-};
-
-exports.XJSMemberExpression = {
-  exit: function (node) {
-    node.computed = node.property.type === "Literal";
-    node.type = "MemberExpression";
-  }
-};
-
-exports.XJSEmptyExpression = function (node) {
-  node.value = null;
-  node.type = "Literal";
-};
-
-exports.XJSExpressionContainer = function (node) {
-  return node.expression;
-};
-
-exports.XJSAttribute = {
-  exit: function (node) {
-    var value = node.value || b.literal(true);
-    var propNode = b.property("init", node.name, value);
-    propNode.loc = node.loc;
-    return propNode;
-  }
-};
-
-exports.XJSOpeningElement = {
-  exit: function (node, parent, file) {
-    var tagExpr = node.name;
-
-    if (_.contains(KNOWN_TAGS, tagExpr.name)) {
-      tagExpr = b.memberExpression(file.jsx, tagExpr, false);
-    }
-
-    var props = node.attributes;
-    if (props.length) {
-      props = b.objectExpression(props);
-    } else {
-      props = b.literal(null);
-    }
-
-    return b.callExpression(tagExpr, [props]);
-  }
-};
-
-exports.XJSElement = {
-  exit: function (node) {
-    var callExpr = node.openingElement;
-    var children = node.children;
-
-    _.each(children, function (child) {
-      delete child.raw;
-      callExpr.arguments.push(child);
-    });
-
-    callExpr.loc = node.loc;
-    return callExpr;
-  }
-};

lib/6to5/transformers/jsx/known-tags.json

@@ -1,132 +0,0 @@
-[
-  "a",
-  "abbr",
-  "address",
-  "applet",
-  "area",
-  "article",
-  "aside",
-  "audio",
-  "b",
-  "base",
-  "bdi",
-  "bdo",
-  "big",
-  "blockquote",
-  "body",
-  "br",
-  "button",
-  "canvas",
-  "caption",
-  "circle",
-  "cite",
-  "code",
-  "col",
-  "colgroup",
-  "command",
-  "data",
-  "datalist",
-  "dd",
-  "defs",
-  "del",
-  "details",
-  "dfn",
-  "dialog",
-  "div",
-  "dl",
-  "dt",
-  "ellipse",
-  "em",
-  "embed",
-  "fieldset",
-  "figcaption",
-  "figure",
-  "footer",
-  "form",
-  "g",
-  "h1",
-  "h2",
-  "h3",
-  "h4",
-  "h5",
-  "h6",
-  "head",
-  "header",
-  "hgroup",
-  "hr",
-  "html",
-  "i",
-  "iframe",
-  "img",
-  "input",
-  "ins",
-  "kbd",
-  "keygen",
-  "label",
-  "legend",
-  "li",
-  "line",
-  "linearGradient",
-  "link",
-  "main",
-  "map",
-  "mark",
-  "marquee",
-  "menu",
-  "menuitem",
-  "meta",
-  "meter",
-  "nav",
-  "noscript",
-  "object",
-  "ol",
-  "optgroup",
-  "option",
-  "output",
-  "p",
-  "param",
-  "path",
-  "polygon",
-  "polyline",
-  "pre",
-  "progress",
-  "q",
-  "radialGradient",
-  "rect",
-  "rp",
-  "rt",
-  "ruby",
-  "s",
-  "samp",
-  "script",
-  "section",
-  "select",
-  "small",
-  "source",
-  "span",
-  "stop",
-  "strong",
-  "style",
-  "sub",
-  "summary",
-  "sup",
-  "svg",
-  "table",
-  "tbody",
-  "td",
-  "text",
-  "textarea",
-  "tfoot",
-  "th",
-  "thead",
-  "time",
-  "title",
-  "tr",
-  "track",
-  "tspan",
-  "u",
-  "ul",
-  "var",
-  "video",
-  "wbr"
-]

lib/6to5/transformers/let-scoping.js

@@ -1,58 +0,0 @@
-var traverse = require("../traverse");
-var util     = require("../util");
-var b        = require("acorn-ast-types").builders;
-var _        = require("lodash");
-
-exports.VariableDeclaration = function (node, parent, file) {
-  if (node.kind !== "let") return;
-  node.kind = "var";
-
-  var ids = {};
-
-  _.each(node.declarations, function (declar) {
-    _.each(util.getIds(declar.id), function (id) {
-      ids[id] = b.identifier(file.generateUid(id));
-    });
-  });
-
-  var replaceId = function (node, parent) {
-    // not an identifier so we have no use for this node
-    if (node.type !== "Identifier") return;
-
-    // not a let reference
-    var id = ids[node.name];
-    if (!id) return;
-
-    if (util.isReferenced(node, parent)) return id;
-  };
-
-  var isProgram = parent.type === "Program";
-
-  var replace = function (node, parent) {
-    if (!isProgram && _.contains(traverse.FUNCTION_TYPES, node.type)) {
-      var letReferences = [];
-
-      traverse(node, function (node, parent) {
-        var id = replaceId(node, parent);
-        if (id && !_.contains(letReferences, id)) letReferences.push(id);
-        return id;
-      });
-
-      if (letReferences.length) {
-        if (node.type === "FunctionDeclaration") {
-          throw new Error("`FunctionDeclaration`s that use `let` and `constant` references aren't allowed outside of the root scope");
-        } else {
-          return b.callExpression(b.functionExpression(null, letReferences, b.blockStatement([
-            b.returnStatement(node)
-          ])), letReferences);
-        }
-      } else {
-        return false;
-      }
-    }
-
-    return replaceId(node, parent);
-  };
-
-  traverse(parent, replace);
-};

lib/6to5/transformers/react.js

@@ -1,63 +0,0 @@
-var b = require("acorn-ast-types").builders;
-var _ = require("lodash");
-
-var addDisplayName = function (id, call) {
-  if (!call || call.type !== "CallExpression") return;
-
-  var callee = call.callee;
-  if (callee.type !== "MemberExpression") return;
-
-  // not React
-  var obj = callee.object;
-  if (obj.type !== "Identifier" || obj.name !== "React") return;
-
-  // not createClass
-  var prop = callee.property;
-  if (prop.type !== "Identifier" || prop.name !== "createClass") return;
-
-  // no arguments
-  var args = call.arguments;
-  if (args.length !== 1) return;
-
-  // not an object
-  var first = args[0];
-  if (first.type !== "ObjectExpression") return;
-
-  var props = first.properties;
-  var safe = true;
-
-  _.each(props, function (prop) {
-    if (prop.key.name === "displayName") {
-      return safe = false;
-    }
-  });
-
-  if (safe) {
-    props.unshift(b.property("init", b.identifier("displayName"), b.literal(id)));
-  }
-};
-
-exports.AssignmentExpression =
-exports.Property =
-exports.VariableDeclarator = function (node) {
-  var left, right;
-
-  if (node.type === "AssignmentExpression") {
-    left = node.left;
-    right = node.right;
-  } else if (node.type === "Property") {
-    left = node.key;
-    right = node.value;
-  } else if (node.type === "VariableDeclarator") {
-    left = node.id;
-    right = node.init;
-  }
-
-  if (left && left.type === "MemberExpression") {
-    left = left.property;
-  }
-
-  if (left && left.type === "Identifier") {
-    addDisplayName(left.name, right);
-  }
-};

lib/6to5/transformers/rest-parameters.js

@@ -1,19 +0,0 @@
-var util = require("../util");
-var b    = require("acorn-ast-types").builders;
-
-exports.Function = function (node, parent, file) {
-  if (!node.rest) return;
-
-  var rest = node.rest;
-  delete node.rest;
-
-  var templateName = "arguments-slice-assign";
-  if (node.params.length) templateName += "-arg";
-
-  util.ensureBlock(node);
-  node.body.body.unshift(util.template(templateName, {
-    SLICE_KEY: file.addDeclaration("slice"),
-    VARIABLE_NAME: rest,
-    SLICE_ARG: b.literal(node.params.length)
-  }));
-};

lib/6to5/transformers/spread.js

@@ -1,98 +0,0 @@
-var util = require("../util");
-var b    = require("acorn-ast-types").builders;
-var _    = require("lodash");
-
-var getSpreadLiteral = function (spread, file) {
-  var literal = spread.argument;
-  if (literal.type !== "ArrayExpression") {
-    literal = util.template("call", {
-      OBJECT: file.addDeclaration("slice"),
-      CONTEXT: literal
-    });
-  }
-  return literal;
-};
-
-var hasSpread = function (nodes) {
-  var has = false;
-  _.each(nodes, function (node) {
-    if (node.type === "SpreadElement") {
-      has = true;
-      return false;
-    }
-  });
-  return has;
-};
-
-var build = function (props, file) {
-  var nodes = [];
-
-  var _props = [];
-
-  var push = function () {
-    if (!_props.length) return;
-    nodes.push(b.arrayExpression(_props));
-    _props = [];
-  };
-
-  _.each(props, function (prop) {
-    if (prop.type === "SpreadElement") {
-      push();
-      nodes.push(getSpreadLiteral(prop, file));
-    } else {
-      _props.push(prop);
-    }
-  });
-
-  push();
-
-  return nodes;
-};
-
-exports.ArrayExpression = function (node, parent, file) {
-  var elements = node.elements;
-  if (!hasSpread(elements)) return;
-
-  var nodes = build(elements, file);
-  var first = nodes.shift();
-
-  if (!nodes.length) return first;
-
-  return b.callExpression(b.memberExpression(first, b.identifier("concat"), false), nodes);
-};
-
-exports.CallExpression = function (node, parent, file) {
-  var args = node.arguments;
-  if (!hasSpread(args)) return;
-
-  var contextLiteral = b.literal(null);
-
-  node.arguments = [];
-
-  var nodes = build(args, file);
-  var first = nodes.shift();
-
-  if (nodes.length) {
-    node.arguments.push(b.callExpression(b.memberExpression(first, b.identifier("concat"), false), nodes));
-  } else {
-    node.arguments.push(first);
-  }
-
-  var callee = node.callee;
-
-  if (callee.type === "MemberExpression") {
-    contextLiteral = callee.object;
-
-    if (callee.computed) {
-      callee.object = b.memberExpression(callee.object, callee.property, true);
-      callee.property = b.identifier("apply");
-      callee.computed = false;
-    } else {
-      callee.property = b.memberExpression(callee.property, b.identifier("apply"), false);
-    }
-  } else {
-    node.callee = b.memberExpression(node.callee, b.identifier("apply"), false);
-  }
-
-  node.arguments.unshift(contextLiteral);
-};

lib/6to5/transformers/use-strict.js

@@ -1,15 +0,0 @@
-var b = require("acorn-ast-types").builders;
-
-module.exports = function (ast, file) {
-  var body = ast.program.body;
-  var first = body[0];
-
-  var noStrict = !first || first.type !== "ExpressionStatement" || first.expression.type !== "Literal" || first.expression.value !== "use strict";
-
-  if (noStrict) {
-    if (file.opts._noStrict) return;
-    body.unshift(b.expressionStatement(b.literal("use strict")));
-  } else {
-    if (file.opts._noStrict) body.shift();
-  }
-};

lib/6to5/traverse/index.js

@@ -1,24 +1,30 @@
-var VISITOR_KEYS = require("./visitor-keys");
-var _            = require("lodash");
+module.exports = traverse;
 
-var traverse = module.exports = function (parent, callbacks, blacklistTypes) {
+var Scope = require("./scope");
+var t     = require("../types");
+var _     = require("lodash");
+
+function traverse(parent, callbacks, opts) {
   // falsy node
   if (!parent) return;
 
   // array of nodes
   if (_.isArray(parent)) {
     _.each(parent, function (node) {
-      traverse(node, callbacks, blacklistTypes);
+      traverse(node, callbacks, opts);
     });
     return;
   }
 
   // unknown node type to traverse
-  var keys = VISITOR_KEYS[parent.type];
+  var keys = t.VISITOR_KEYS[parent.type];
   if (!keys) return;
 
+  opts = opts || {};
+  if (_.isArray(opts)) opts = { blacklist: opts };
+
   // blacklist these node types from being traversed
-  blacklistTypes = blacklistTypes || [];
+  var blacklistTypes = opts.blacklist || [];
 
   // normalise callbacks
   if (_.isFunction(callbacks)) callbacks = { enter: callbacks };
@@ -34,29 +40,31 @@ var traverse = module.exports = function (parent, callbacks, blacklistTypes) {
       // type is blacklisted
       if (_.contains(blacklistTypes, node.type)) return;
 
-      var result;
-
       // replace node
       var maybeReplace = function (result) {
-        if (result != null) obj[key] = result;
+        if (result === false) return;
+        if (result != null) node = obj[key] = result;
       };
 
+      //
+      var opts2 = _.clone(opts);
+      if (t.isScope(node)) opts2.scope = new Scope(opts.scope, node);
+
       // enter
       if (callbacks.enter) {
-        result = callbacks.enter(node, parent, obj, key);
+        var result = callbacks.enter(node, parent, opts2.scope);
+        maybeReplace(result);
 
         // stop iteration
         if (result === false) return;
-
-        maybeReplace(result);
       }
 
       // traverse node
-      traverse(node, callbacks, blacklistTypes);
+      traverse(node, callbacks, opts2);
 
       // exit
       if (callbacks.exit) {
-        maybeReplace(callbacks.exit(node, parent, obj, key));
+        maybeReplace(callbacks.exit(node, parent, opts2.scope));
       }
     };
 
@@ -65,63 +73,56 @@ var traverse = module.exports = function (parent, callbacks, blacklistTypes) {
         handle(nodes, i);
       });
 
-      // remove deleted nodes
-      parent[key] = _.flatten(parent[key]).filter(function (node) {
-        return node !== traverse.Delete;
-      });
+      parent[key] = _.flatten(parent[key]);
     } else {
       handle(parent, key);
-
-      if (parent[key] === traverse.Delete) {
-        throw new Error("trying to delete property " + key + " from " +
-                        parent.type + " but can't because it's required");
-      }
     }
   });
+}
+
+traverse.removeProperties = function (tree) {
+  var clear = function (node) {
+    delete node.extendedRange;
+    delete node._scopeIds;
+    delete node._parent;
+    delete node.tokens;
+    delete node.range;
+    delete node.start;
+    delete node.end;
+    delete node.loc;
+    delete node.raw;
+
+    clearComments(node.trailingComments);
+    clearComments(node.leadingComments);
+  };
+
+  var clearComments = function (comments) {
+    _.each(comments, clear);
+  };
+
+  clear(tree);
+  traverse(tree, clear);
+
+  return tree;
 };
 
-traverse.FUNCTION_TYPES = ["ArrowFunctionExpression", "FunctionDeclaration", "FunctionExpression"];
-
-traverse.aliases = {
-  ArrowFunctionExpression: ["Function"],
-  FunctionDeclaration:     ["Function"],
-  FunctionExpression:      ["Function"]
-};
-
-traverse.isFunction = function (node) {
-  return _.contains(traverse.FUNCTION_TYPES, node.type);
-};
-
-traverse.isPattern = function (node) {
-  return node.type === "ArrayPattern" || node.type === "ObjectPattern";
-};
-
-traverse.Delete = {};
-
 traverse.hasType = function (tree, type, blacklistTypes) {
   blacklistTypes = [].concat(blacklistTypes || []);
 
   var has = false;
 
-  if (_.isArray(tree)) {
-    // array of nodes, find the first
-    return !!_.find(tree, function (node) {
-      return traverse.hasType(node, type, blacklistTypes);
-    });
-  } else {
-    // the node we're searching in is blacklisted
-    if (_.contains(blacklistTypes, tree.type)) return false;
+  // the node we're searching in is blacklisted
+  if (_.contains(blacklistTypes, tree.type)) return false;
 
-    // the type we're looking for is the same as the passed node
-    if (tree.type === type) return true;
+  // the type we're looking for is the same as the passed node
+  if (tree.type === type) return true;
 
-    traverse(tree, function (node) {
-      if (node.type === type) {
-        has = true;
-        return false;
-      }
-    }, blacklistTypes);
-  }
+  traverse(tree, function (node) {
+    if (node.type === type) {
+      has = true;
+      return false;
+    }
+  }, { blacklist: blacklistTypes });
 
   return has;
 };

lib/6to5/traverse/scope.js

@@ -0,0 +1,79 @@
+module.exports = Scope;
+
+var traverse = require("./index");
+var t        = require("../types");
+var _        = require("lodash");
+
+function Scope(parent, block) {
+  this.parent = parent;
+  this.block  = block;
+  this.ids    = this.getIds();
+
+  this.getIds();
+}
+
+Scope.prototype.getIds = function () {
+  var block = this.block;
+  if (block._scopeIds) return block._scopeIds;
+
+  var self = this;
+  var ids  = block._scopeIds = {};
+
+  if (t.isBlockStatement(block)) {
+    _.each(block.body, function (node) {
+      if (t.isVariableDeclaration(node) && node.kind !== "var") {
+        self.add(node, ids);
+      }
+    });
+  } else if (t.isProgram(block) || t.isFunction(block)) {
+    traverse(block, function (node, parent) {
+      if (parent !== block && t.isVariableDeclaration(node) && node.kind !== "var") {
+        return;
+      }
+
+      if (t.isDeclaration(node)) {
+        self.add(node, ids);
+      } else if (t.isFunction(node)) {
+        return false;
+      }
+    });
+  } else if (t.isCatchClause(block)) {
+    self.add(block.param, ids);
+  }
+
+  if (t.isFunction(block)) {
+    _.each(block.params, function (param) {
+      self.add(param, ids);
+    });
+  }
+
+  return ids;
+};
+
+Scope.prototype.add = function (node, ids) {
+  _.merge(ids || this.ids, t.getIds(node, true));
+};
+
+Scope.prototype.get = function (id) {
+  return id && (this.getOwn(id) || this.parentGet(id));
+};
+
+Scope.prototype.getOwn = function (id) {
+  return _.has(this.ids, id) && this.ids[id];
+};
+
+Scope.prototype.parentGet = function (id) {
+  return this.parent && this.parent.get(id);
+};
+
+Scope.prototype.has = function (id) {
+  return id && (this.hasOwn(id) || this.parentHas(id));
+};
+
+Scope.prototype.hasOwn = function (id) {
+  return !!this.getOwn(id);
+};
+
+Scope.prototype.parentHas = function (id) {
+  return this.parent && this.parent.has(id);
+};

lib/6to5/traverse/visitor-keys.json

@@ -1,86 +0,0 @@
-{
-  "ArrayExpression":               ["elements"],
-  "ArrayPattern":                  ["elements"],
-  "ArrowFunctionExpression":       ["params", "defaults", "rest", "body"],
-  "AssignmentExpression":          ["left", "right"],
-  "AwaitExpression":               ["argument"],
-  "BinaryExpression":              ["left", "right"],
-  "BlockStatement":                ["body"],
-  "BreakStatement":                ["label"],
-  "CallExpression":                ["callee", "arguments"],
-  "CatchClause":                   ["param", "body"],
-  "ClassBody":                     ["body"],
-  "ClassDeclaration":              ["id", "body", "superClass"],
-  "ClassExpression":               ["id", "body", "superClass"],
-  "ClassProperty":                 ["key", "value"],
-  "ComprehensionBlock":            ["left", "right", "body"],
-  "ComprehensionExpression":       ["filter", "blocks", "body"],
-  "ConditionalExpression":         ["test", "consequent", "alternate"],
-  "ContinueStatement":             ["label"],
-  "DebuggerStatement":             [],
-  "DoWhileStatement":              ["body", "test"],
-  "EmptyStatement":                [],
-  "ExportDeclaration":             ["declaration", "specifiers", "source"],
-  "ExportBatchSpecifier":          [],
-  "ExportSpecifier":               ["id", "name"],
-  "ExpressionStatement":           ["expression"],
-  "File":                          ["program"],
-  "ForInStatement":                ["left", "right", "body"],
-  "ForOfStatement":                ["left", "right", "body"],
-  "ForStatement":                  ["init", "test", "update", "body"],
-  "FunctionDeclaration":           ["id", "params", "defaults", "rest", "body"],
-  "FunctionExpression":            ["id", "params", "defaults", "rest", "body"],
-  "Identifier":                    [],
-  "IfStatement":                   ["test", "consequent", "alternate"],
-  "ImportDeclaration":             ["specifiers", "source"],
-  "ImportDefaultSpecifier":        ["id"],
-  "ImportNamespaceSpecifier":      ["id"],
-  "ImportSpecifier":               ["id", "name"],
-  "LabeledStatement":              ["label", "body"],
-  "Literal":                       [],
-  "LogicalExpression":             ["left", "right"],
-  "MemberExpression":              ["object", "property"],
-  "MethodDefinition":              ["key", "value"],
-  "ModuleSpecifier":               [],
-  "NewExpression":                 ["callee", "arguments"],
-  "ObjectExpression":              ["properties"],
-  "ObjectPattern":                 ["properties"],
-  "ObjectTypeAnnotation":          ["properties"],
-  "OptionalParameter":             ["id"],
-  "ParametricTypeAnnotation":      ["params"],
-  "ParametricallyTypedIdentifier": [],
-  "Program":                       ["body"],
-  "Property":                      ["key", "value"],
-  "ReturnStatement":               ["argument"],
-  "SequenceExpression":            ["expressions"],
-  "SpreadElement":                 ["argument"],
-  "SpreadProperty":                ["argument"],
-  "SwitchCase":                    ["test", "consequent"],
-  "SwitchStatement":               ["discriminant", "cases"],
-  "TaggedTemplateExpression":      ["tag", "quasi"],
-  "TemplateElement":               [],
-  "TemplateLiteral":               ["quasis", "expressions"],
-  "ThisExpression":                [],
-  "ThrowStatement":                ["argument"],
-  "TryStatement":                  ["block", "handlers", "handler", "guardedHandlers", "finalizer"],
-  "TypeAnnotatedIdentifier":       ["id", "annotation"],
-  "TypeAnnotation":                ["id", "params", "returnType", "parametricType"],
-  "UnaryExpression":               ["argument"],
-  "UpdateExpression":              ["argument"],
-  "VariableDeclaration":           ["declarations"],
-  "VariableDeclarator":            ["id", "init"],
-  "VoidTypeAnnotation":            [],
-  "WhileStatement":                ["test", "body"],
-  "WithStatement":                 ["object", "body"],
-  "XJSIdentifier":                 [],
-  "XJSNamespacedName":             ["namespace", "name"],
-  "XJSMemberExpression":           ["object", "property"],
-  "XJSEmptyExpression":            [],
-  "XJSExpressionContainer":        ["expression"],
-  "XJSElement":                    ["openingElement", "closingElement", "children"],
-  "XJSClosingElement":             ["name"],
-  "XJSOpeningElement":             ["name", "attributes"],
-  "XJSAttribute":                  ["name", "value"],
-  "XJSText":                       [],
-  "YieldExpression":               ["argument"]
-}

lib/6to5/types/alias-keys.json

@@ -0,0 +1,46 @@
+{
+  "ExpressionStatement": ["Statement"],
+  "BreakStatement":      ["Statement"],
+  "ContinueStatement":   ["Statement"],
+  "DebuggerStatement":   ["Statement"],
+  "DoWhileStatement":    ["Statement"],
+  "IfStatement":         ["Statement"],
+  "ReturnStatement":     ["Statement"],
+  "SwitchStatement":     ["Statement"],
+  "ThrowStatement":      ["Statement"],
+  "TryStatement":        ["Statement"],
+  "WhileStatement":      ["Statement"],
+  "WithStatement":       ["Statement"],
+  "EmptyStatement":      ["Statement"],
+  "LabeledStatement":    ["Statement"],
+  "VariableDeclaration": ["Statement", "Declaration"],
+  "ExportDeclaration":   ["Statement", "Declaration"],
+  "ImportDeclaration":   ["Statement", "Declaration"],
+
+  "ArrowFunctionExpression": ["Scope", "Function"],
+  "FunctionDeclaration":     ["Statement", "Declaration", "Scope", "Function"],
+  "FunctionExpression":      ["Scope", "Function"],
+
+  "BlockStatement": ["Statement", "Scope"],
+  "Program":        ["Scope"],
+  "CatchClause":    ["Scope"],
+
+  "LogicalExpression": ["Binary"],
+  "BinaryExpression":  ["Binary"],
+
+  "UnaryExpression": ["UnaryLike"],
+  "SpreadProperty":  ["UnaryLike"],
+  "SpreadElement":   ["UnaryLike"],
+
+  "ClassDeclaration": ["Statement", "Declaration", "Class"],
+  "ClassExpression":  ["Class"],
+
+  "ForOfStatement": ["Statement", "For"],
+  "ForInStatement": ["Statement", "For"],
+  "ForStatement":   ["Statement", "For"],
+
+  "ObjectPattern": ["Pattern"],
+  "ArrayPattern":  ["Pattern"],
+
+  "Property": ["UserWhitespacable"]
+}

lib/6to5/types/builder-keys.json

@@ -0,0 +1,25 @@
+{
+  "ArrayExpression":         ["elements"],
+  "AssignmentExpression":    ["operator", "left", "right"],
+  "BinaryExpression":        ["operator", "left", "right"],
+  "BlockStatement":          ["body"],
+  "CallExpression":          ["callee", "arguments"],
+  "ConditionalExpression":   ["test", "consequent", "alternate"],
+  "ExpressionStatement":     ["expression"],
+  "File":                    ["program", "comments", "tokens"],
+  "FunctionExpression":      ["id", "params", "body", "generator"],
+  "Identifier":              ["name"],
+  "IfStatement":             ["test", "consequent", "alternate"],
+  "Literal":                 ["value"],
+  "MemberExpression":        ["object", "property", "computed"],
+  "NewExpression":           ["callee", "arguments"],
+  "ObjectExpression":        ["properties"],
+  "ParenthesizedExpression": ["expression"],
+  "Program":                 ["body"],
+  "Property":                ["kind", "key", "value", "computed"],
+  "ReturnStatement":         ["argument"],
+  "SequenceExpression":      ["expressions"],
+  "UnaryExpression":         ["operator", "argument", "prefix"],
+  "VariableDeclaration":     ["kind", "declarations"],
+  "VariableDeclarator":      ["id", "init"]
+}