v1.14.7

Only slice arguments when necessary - fixes #239

.hound.yml

@@ -1,3 +0,0 @@
-java_script:
-  enabled: true
-  config_file: .jshintrc

CHANGELOG.md

@@ -1,3 +1,122 @@
+# 1.14.6
+
+ * Avoid ensuring a block on non-array node replacements.
+
+# 1.14.5
+
+ * Upgrade `acorn-6to5`.
+ * Fix JSON recursion error for unknown code generator node types.
+ * Ensure that a statement is a block on block/statement types when replacing them with multiple nodes.
+
+# 1.14.4
+
+ * Merge pretzel maps and method binding.
+
+# 1.14.3
+
+ * Add playground pretzel maps.
+
+# 1.14.2
+
+ * Fix `commonInterop` default export handling.
+ * Fix keyworded property key identifiers being turned into computed property key literals.
+
+# 1.14.1
+
+ * Inherit comments from `ClassDeclaration`.
+
+# 1.14.0
+
+ * Add [playground](https://6to5.github.io/playground.html).
+
+# 1.13.13
+
+ * Fix `--debug` in `bin/6to5-node`. Thanks [@timoxley](https://github.com/timoxley).
+
+# 1.13.12
+
+ * Ignore `XJSEmptyExpression`s in `react` transformer output.
+
+# 1.13.11
+
+ * Fix `util.regexify` on falsy values.
+ * Fix `_aliasFunction` with rest parameters.
+ * Export as `module.exports` instead of `exports.default` if there are no other `ExportDeclaration`s in `commonInterop` module formatter.
+ * Add `system` module formatter. Thanks [@douglasduteil](https://github.com/douglasduteil).
+
+# 1.13.10
+
+ * Add support for `AssignmentExpression` destructuring outside of `ExpressionStatement`.
+
+# 1.13.9
+
+ * Fix `VirtualPropertyExpression` visitor keys.
+
+# 1.13.8
+
+ * Only use a single reference in abstract references.
+
+# 1.13.7
+
+ * Upgrade `acorn-6to5`.
+ * Add experimental exponentiation operator support.
+
+# 1.13.6
+
+ * Fix experimental object spread/rest helper.
+
+# 1.13.5
+
+ * Upgrade `acorn-6to5`.
+ * Add experimental support for object spread/rest.
+ * Change `arguments` to array to an additional helper method.
+
+# 1.13.4
+
+ * Fix single spread element returning itself.
+
+# 1.13.3
+
+ * Upgrade `acorn-6to5`.
+ * Add experimental support for abstract references.
+
+# 1.13.2
+
+ * Optimise `Array.from` usage by adding a helper method.
+ * Upgrade `acorn-6to5`.
+
+# 1.13.1
+
+ * Fix constructor spread optimisation. Thanks [@zloirock](https://github.com/zloirock).
+
+# 1.13.0
+
+ * Put experimental ES7 features behind a flag `--experimental` and `experimental` option.
+ * Constructor spread performance increase. Thanks [@RReverser](https://github.com/RReverser).
+ * Use `self` instead of `window` in the optional 6to5 runtime. Thanks [@RReverser](https://github.com/RReverser).
+
+# 1.12.26
+
+ * Support computed property destructuring.
+
+# 1.12.25
+
+ * Update `acorn-6to5`, `ast-types`, `es6-shim`, `chokidar`, `estraverse` and `private`.
+
+# 1.12.24
+
+ * Collect references that haven't been declared in scope.
+
+# 1.12.23
+
+ * Fix generator function export hoisting.
+
+# 1.12.22
+
+ * Update `fs-readdir-recursive` and `chokidar`.
+ * Support array destructuring on iterables.
+ * Make amd module id optional. Thanks [@webpro](https://github.com/webpro).
+
 # 1.12.21
 
  * Fix unneccesary let scoping replacement.

CONTRIBUTING.md

@@ -9,7 +9,6 @@
    * CamelCase all class names
    * camelBack all variable names
  * **Spacing**
-   * 80 character line max
    * Spaces after all keywords
    * Spaces before all left curly braces
  * **Comments**

README.md

@@ -4,7 +4,7 @@
 
 <p align="center">
   <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">
+    <img alt="Travis Status" src="http://img.shields.io/travis/6to5/6to5/master.svg?style=flat&amp;label=travis">
   </a>
 
   <a href="https://ci.appveyor.com/project/sebmck/6to5">
@@ -26,4 +26,5 @@
 
 **6to5** turns ES6+ code into vanilla ES5, so you can use next generation features **today.**
 
-For more information view the [documentation](https://6to5.github.io).
+For more information view the [documentation](https://6to5.github.io). For
+support visit the [gitter room](https://gitter.im/6to5/6to5).

bin/6to5-node

@@ -14,13 +14,11 @@ process.argv.slice(2).forEach(function(arg){
   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":

bin/6to5/index.js

@@ -11,6 +11,8 @@ commander.option("-s, --source-maps", "Save source map alongside the compiled co
 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("-e, --experimental", "Enable experimental support for proposed ES7 features");
+commander.option("-p, --playground", "Enable playground support");
 
 commander.option("-m, --modules [modules]", "Module formatter type to use [common]", "common");
 commander.option("-w, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util.list);
@@ -18,6 +20,7 @@ commander.option("-b, --blacklist [blacklist]", "Blacklist of transformers to NO
 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");
 commander.option("-c, --remove-comments", "Remove comments from the compiled code", false);
+commander.option("-a, --amd-module-ids", "Insert module id in AMD modules", false);
 
 commander.on("--help", function(){
   var outKeys = function (title, obj) {
@@ -86,6 +89,9 @@ if (errors.length) {
 
 exports.opts = {
   sourceMapName: commander.outFile,
+  amdModuleIds:  commander.amdModuleIds,
+  experimental:  commander.experimental,
+  playground:    commander.playground,
   blacklist:     commander.blacklist,
   whitelist:     commander.whitelist,
   sourceMap:     commander.sourceMaps || commander.sourceMapsInline,

bin/_6to5-node

@@ -8,10 +8,12 @@ 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);
+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]");
+commander.option("-r, --experimental", "Enable experimental support for proposed ES7 features");
+commander.option("-g, --playground", "Enable playground support");
 
 var pkg = require("../package.json");
 commander.version(pkg.version);
@@ -20,22 +22,21 @@ 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);
+to5.register({
+  experimental: commander.experimental,
+  extensions:   commander.extensions,
+  ignore:       commander.ignore
+});
 
 //
 
 var _eval = function (code, filename) {
-  code = to5.transform(code, { filename: filename, blacklist: ["useStrict"] }).code;
+  code = to5.transform(code, {
+    modules: "commonInterop",
+    filename: filename,
+    blacklist: ["useStrict"],
+    experimental: commander.experimental
+  }).code;
   return vm.runInThisContext(code, filename);
 };
 

doc/browser.md

@@ -30,7 +30,9 @@ test.test();
 You can build a browser version of the compiler by running the following in the
 6to5 directory:
 
-    $ make build
+```sh
+$ make build
+```
 
 This will output the files `dist/6to5.js` and `dist/6to5.min.js`.
 
@@ -38,7 +40,9 @@ This will output the files `dist/6to5.js` and `dist/6to5.min.js`.
 
 To test 6to5 in your browser run:
 
-    $ make test-browser
+```sh
+$ make test-browser
+```
 
 And open `test/browser.html` in your browser if it doesn't open automatically.
 

doc/caveats.md

@@ -1,9 +1,18 @@
 # Caveats
 
-## Async/Generators
+In order for certain features to work they require certain polyfills. You can
+satisfy **all** 6to5 feature requirements by using the included
+[polyfill](polyfill.md). You may alternatively selectively include what you need:
 
-The [regenerator runtime](https://github.com/facebook/regenerator/blob/master/runtime.js)
-and an [ES6 polyfill](polyfill.md) are required in order for generators to work.
+| Feature                     | Requirements                                                                                                                 |
+| --------------------------- | ---------------------------------------------------------------------------------------------------------------------------- |
+| Abstract References         | [experimental](usage.md#experimental), `Symbol`                                                                              |
+| Array destructuring         | `Array.isArray`, `Array.from`                                                                                                |
+| Async functions, Generators | [experimental](usage.md#experimental), [regenerator runtime](https://github.com/facebook/regenerator/blob/master/runtime.js) |
+| Comprehensions              | [experimental](usage.md#experimental), `Array.isArray`, `Array.from`                                                         |
+| For Of                      | `Symbol`, `prototype[Symbol.iterator]`                                                                                       |
+| Object spread/rest          | [experimental](usage.md#experimental), `Object.assign`                                                                       |
+| Spread                      | `Array.isArray`, `Array.from`                                                                                                |
 
 ## Classes
 
@@ -30,14 +39,3 @@ class Bar extends Foo {
   }
 }
 ```
-
-## For-of
-
-A polyfill is required for for-of functionality that implements `Symbol` and
-adds `prototype[Symbol.iterator]` behaviour to built-ins. Using the polyfills
-specified in [polyfill](polyfill.md) suffices.
-
-## Spread
-
-An [ES6 polyfill](polyfill.md) is required in order for spread to work. More
-specifically a polyfill for `Array.from`.

doc/differences.md

@@ -62,13 +62,14 @@ better suited if you'd like a full ES6 environment with polyfills and all.
 | ---------------------------- | ---- | ------- | -------------- | ------ | ------ | ----------- |
 | Source maps                  | ✓    | ✓       | ✓              | ✓      |        | ✓           |
 | No compiler global pollution | ✓    |         | ✓              | ✓      |        | ✓           |
-| No runtime                   | ✓    |         | ✓              |        |        | ✓           |
+| Optional runtime             | ✓    |         | ✓              |        |        | ✓           |
 | Browser support              | ✓    | ✓       |                | ✓      |        |             |
 
 ### Language Support
 
 |                              | 6to5  | Traceur | es6-transpiler | esnext | es6now | jstransform |
 | ---------------------------- | ----- | ------- | -------------- | ------ | ------ | ----------- |
+| Abstract references          | ✓     |         |                |        |        |             |
 | Array comprehension          | ✓     | ✓       | ✓              |        |        |             |
 | Arrow functions              | ✓     | ✓       | ✓              | ✓      | ✓      | ✓           |
 | Async functions              | ✓     | ✓       |                | ✓      |        |             |
@@ -77,11 +78,13 @@ better suited if you'd like a full ES6 environment with polyfills and all.
 | Constants                    | ✓     | ✓       | ✓              |        |        |             |
 | Default parameters           | ✓     | ✓       | ✓              | ✓      | ✓      |             |
 | Destructuring                | ✓     | ✓       | ✓              | ✓      | ✓      | ✓           |
+| Exponentiation operator      | ✓     | ✓       |                |        |        |             |
 | For-of                       | ✓     | ✓       | ✓              | ✓      | ✓      |             |
 | Generators                   | ✓     | ✓       |                | ✓      |        |             |
 | Generator comprehension      | ✓     | ✓       |                |        |        |             |
 | Let scoping                  | ✓     | ✓       | ✓              |        |        |             |
 | Modules                      | ✓     | ✓       |                |        | ✓      |             |
+| Object rest/spread           | ✓     |         |                |        |        | ✓           |
 | Property method assignment   | ✓     | ✓       | ✓              | ✓      | ✓      | ✓           |
 | Property name shorthand      | ✓     | ✓       | ✓              | ✓      | ✓      | ✓           |
 | Rest parameters              | ✓     | ✓       | ✓              | ✓      | ✓      | ✓           |
@@ -89,15 +92,11 @@ better suited if you'd like a full ES6 environment with polyfills and all.
 | Template literals            | ✓     | ✓       | ✓              | ✓      | ✓      | ✓           |
 | Unicode regex                | ✓     | ✓       | ✓              |        |        |             |
 
-
-
-
-
 ### [Traceur](https://github.com/google/traceur-compiler)
 
 Traceur requires quite a bulky runtime (~75KB) and produces quite verbose code.
 While this can be trimmed down by selectively building the runtime, it's an
-unneccesary step when a runtime can be eliminated entirely.
+unneccesary step when a large runtime can be eliminated entirely.
 
 ### [es6now](https://github.com/zenparsing/es6now)
 

doc/features.md

@@ -1,6 +1,14 @@
 # Features
 
-## Array comprehension
+## Abstract references ([experimental](usage.md#experimental)) ([spec](https://github.com/zenparsing/es-abstract-refs))
+
+```javascript
+foo::bar;
+foo::bar = baz;
+delete foo::bar;
+```
+
+## Array comprehensions ([experimental](usage.md#experimental))
 
 ```javascript
 var results = [for (c of customers) if (c.city == "Seattle") { name: c.name, age: c.age }]
@@ -31,7 +39,7 @@ var bob = {
 };
 ```
 
-## Async functions
+## Async functions ([experimental](usage.md#experimental)) ([spec](https://github.com/lukehoban/ecmascript-asyncawait))
 
 ```javascript
 async function chainAnimationsAsync(elem, animations) {
@@ -122,6 +130,15 @@ var [a] = [];
 a === undefined;
 ```
 
+## Exponentiation operator ([experimental](usage.md#experimental)) ([spec](https://github.com/rwaldron/exponentiation-operator))
+
+```javascript
+var a = 2;
+a **= 2;
+
+var squared = 2 ** 2;
+```
+
 ## For-of
 
 ```javascript
@@ -133,13 +150,31 @@ for (var i of [1, 2, 3]) {
 ## Generators
 
 ```javascript
+function* fibonacci() {
+  var pre = 0, cur = 1;
+  for (;;) {
+    var temp = pre;
+    pre = cur;
+    cur += temp;
+    yield cur;
+  }
+}
 
+for (var n of fibonacci()) {
+  // truncate the sequence at 1000
+  if (n > 1000) break;
+  console.log(n);
+}
 ```
 
-## Generator comprehension
+## Generator comprehensions ([experimental](usage.md#experimental))
 
 ```javascript
-
+var nums = [1, 2, 3, 4, 5, 6];
+var multiples = (for (i of nums) if (i % 2) i * i);
+assert.equal(multiples.next().value, 1);
+assert.equal(multiples.next().value, 9);
+assert.equal(multiples.next().value, 25);
 ```
 
 ## Let scoping
@@ -153,7 +188,17 @@ for (let i in arr) {
 ## Modules
 
 ```javascript
+import "foo";
+import foo from "foo";
+import * as foo from "foo";
+import {bar} from "foo";
+import {foo as bar} from "foo";
 
+export { test };
+export var test = 5;
+export function test() {}
+
+export default test;
 ```
 
 ## Numeric literals
@@ -163,6 +208,13 @@ for (let i in arr) {
 0o767 === 503; // true
 ```
 
+## Object spread/rest ([experimental](usage.md#experimental)) ([spec](https://github.com/sebmarkbage/ecmascript-rest-spread))
+
+```javascript
+var n = { x, y, ...z };
+var { x, y, ...z } = { x: 1, y: 2, a: 3, b: 4 };
+```
+
 ## Property method assignment
 
 ```javascript
@@ -216,7 +268,6 @@ var x = 5;
 var y = 10;
 console.log(`${x} + ${y} = ${x + y}`); // "5 + 10 = 15"
 ```
-
 ## Unicode regex
 
 ```javascript

doc/index.md

@@ -3,7 +3,7 @@
  - **Readable** - formatting is retained if possible so your generated code is as similar as possible.
  - **Extensible** - with a large range of [plugins](plugins.md) and **browser support**.
  - **Lossless** - **source map support** so you can debug your compiled code with ease.
- - **Compact** - maps directly to the equivalent ES5 with **no runtime**[\*](caveats.md#generators).
+ - **Compact** - maps directly to the equivalent ES5 with **no runtime**[\*](caveats.md).
 
 ## Installation
 
@@ -19,32 +19,39 @@ how you want to use it.
 6to5 will simply compile your ES6+ script to ES5 if you pass it as an argument
 to the command-line tool `6to5`:
 
-    $ 6to5 script.js
+```sh
+$ 6to5 script.js
+```
 
 If you have a file written using ES6+ and you just want to run it, `6to5-node`
 has you covered:
 
-    $ 6to5-node script.js
+```sh
+$ 6to5-node script.js
+```
 
 And it doesn't end here! To see all the ways you can use 6to5, check out the
 [Usage](http://6to5.github.io/usage.html) page.
 
 ## [Features](features.md)
 
- - [Array comprehension](features.md#array-comprehension)
- - [Async functions](features.md#async-functions) via [regenerator](https://github.com/facebook/regenerator)
+ - [Abstract references](features.md#abstract-references) ([experimental](usage.md#experimental))
+ - [Array comprehension](features.md#array-comprehension) ([experimental](usage.md#experimental))
+ - [Async functions](features.md#async-functions) ([experimental](usage.md#experimental))
  - [Arrow functions](features.md#arrow-functions)
  - [Classes](features.md#classes)
  - [Computed property names](features.md#computed-property-names)
  - [Constants](features.md#constants)
  - [Default parameters](features.md#default-parameters)
  - [Destructuring](features.md#destructuring)
+ - [Exponentiation operator](features.md#exponentiation-operator) ([experimental](usage.md#experimental))
  - [For-of](features.md#for-of)
- - [Generators](features.md#generators) via [regenerator](https://github.com/facebook/regenerator)
- - [Generator comprehension](features.md#generator-comprehension)
+ - [Generators](features.md#generators)
+ - [Generator comprehension](features.md#generator-comprehension) ([experimental](usage.md#experimental))
  - [Let scoping](features.md#let-scoping)
  - [Modules](features.md#modules)
  - [Numeric literals](features.md#numeric-literals)
+ - [Object Rest/Spread](features.md#object-rest-spread) ([experimental](usage.md#experimental))
  - [Property method assignment](features.md#property-method-assignment)
  - [Property name shorthand](features.md#property-name-shorthand)
  - [React/JSX](react.md)

doc/modules.md

@@ -4,7 +4,9 @@
 
 ### CLI
 
-    $ 6to5 --modules common script.js
+```sh
+$ 6to5 --modules common script.js
+```
 
 ### Node
 
@@ -15,8 +17,19 @@ to5.transform('import "foo";', { modules: "common" });
 
 ## Formats
 
+ * [AMD](#amd)
+ * [Common (Default)](#common-default)
+ * [Common Interop](#common-interop)
+ * [Ignore](#ignore)
+ * [System](#system)
+ * [UMD](#umd)
+
 ### Common (Default)
 
+```sh
+$ 6to5 --modules common
+```
+
 **In**
 
 ```javascript
@@ -51,8 +64,79 @@ var test = 5; exports.test = test;
 exports.default = test;
 ```
 
+### Common interop
+
+```sh
+$ 6to5 --modules commonInterop
+```
+
+**In**
+
+```javascript
+import "foo";
+
+import foo from "foo";
+import * as foo from "foo";
+
+import {bar} from "foo";
+import {foo as bar} from "foo";
+
+export {test};
+export var test = 5;
+
+export default test;
+```
+
+**Out**
+
+```javascript
+var _interopRequire = function (obj) {
+  return obj && (obj["default"] || obj);
+};
+
+require("foo");
+
+var foo = _interopRequire(require("foo"));
+var foo = require("foo");
+
+var bar = require("foo").bar;
+var bar = require("foo").foo;
+
+exports.test = test;
+var test = exports.test = 5;
+
+exports["default"] = test;
+```
+
+#### module.exports behaviour
+
+If there exist no other non-default `export`s then `default exports` are
+exported as `module.exports` instead of `exports.default`.
+
+**In**
+
+```javascript
+export default function foo() {
+
+}
+```
+
+**Out**
+
+```javascript
+module.exports = foo;
+
+function foo() {
+
+}
+```
+
 ### AMD
 
+```sh
+$ 6to5 --modules amd
+```
+
 **In**
 
 ```javascript
@@ -66,7 +150,7 @@ export function bar() {
 **Out**
 
 ```javascript
-define("filename", ["exports", "foo"], function (exports, _foo) {
+define(["exports", "foo"], function (exports, _foo) {
   exports.bar = bar;
 
   var foo = _foo.default;
@@ -77,8 +161,18 @@ define("filename", ["exports", "foo"], function (exports, _foo) {
 });
 ```
 
+You can optionally specify to include the module id (using the `--amd-module-id` argument):
+
+```javascript
+define("filename", ["exports", "foo"], function (exports, _foo) {})
+```
+
 ### UMD
 
+```sh
+$ 6to5 --modules umd
+```
+
 **In**
 
 ```javascript
@@ -94,7 +188,7 @@ export function bar() {
 ```javascript
 (function (factory) {
   if (typeof define === "function" && define.amd) {
-    define("filename", ["exports", "foo"], factory);
+    define(["exports", "foo"], factory);
   } else if (typeof exports !== "undefined") {
     factory(exports, require("foo"));
   }
@@ -111,6 +205,10 @@ export function bar() {
 
 ### Ignore
 
+```sh
+$ 6to5 --modules ignore
+```
+
 **In**
 
 ```javascript
@@ -129,11 +227,52 @@ function bar() {
 }
 ```
 
+### System
+
+```sh
+$ 6to5 --modules system
+```
+
+**In**
+
+```javascript
+import foo from "foo";
+
+export function bar() {
+  return foo("foobar");
+}
+```
+
+**Out**
+
+```javascript
+System.register("bar", ["foo"], function (_export) {
+  "use strict";
+
+  var __moduleName = "bar";
+
+  var foo;
+  function bar() {
+    return foo("foobar");
+  }
+  return {
+    setters: [function (m) {
+      foo = m.default;
+    }],
+    execute: function () {
+      _export("bar", bar);
+    }
+  };
+});
+```
+
 ## Custom
 
 You can alternatively specify module names instead of one of the built-in types.
 
-    $ 6to5 --modules custom-module-formatter
+```sh
+$ 6to5 --modules custom-module-formatter
+```
 
 **node_modules/custom-module-formatter/index.js**
 

doc/optional-runtime.md

@@ -18,7 +18,9 @@ Simply use the following option if you're using the [Node API](usage.md#node):
 
 or the following flag if you're using the [CLI](usage.md#cli):
 
-    $ 6to5 --runtime
+```ssh
+$ 6to5 --runtime
+```
 
 Then just include the runtime before your generated code.
 
@@ -26,7 +28,9 @@ Then just include the runtime before your generated code.
 
 You can get the runtime via either:
 
-    $ 6to5-runtime
+```sh
+$ 6to5-runtime
+```
 
 or
 
@@ -45,7 +49,9 @@ argument:
 require("6to5").runtime("myCustomNamespace");
 ```
 
-    $ 6to5-runtime myCustomNamespace
+```sh
+$ 6to5-runtime myCustomNamespace
+```
 
 See [Options - runtime](usage.md#options) for documentation on changing the
 reference in generated code.

doc/playground.md

@@ -0,0 +1,68 @@
+# Playground
+
+Playground is a proving ground for **possible** ES7 proposals.
+
+**NOTE: These features are in no way endorsed by Ecma International and are not a part of ES6. They might become a part of ECMAScript in the future.**
+
+## Usage
+
+    $ 6to5 --playground
+
+```javascript
+to5.transform("code", { playground: true });
+```
+
+**NOTE:** Enabling `playground` also enables [experimental support](usage.md#experimental).
+
+## Features
+
+ * [Memoization operator](#memoization-operator)
+ * [Method binding](#method-binding)
+
+### Memoization assignment operator
+
+```javascript
+var obj = {};
+obj.x ?= 2;
+obj.x; // 2
+
+obj = { x: 1 };
+obj.x ?= 2;
+obj.x; // 1
+
+obj = { x: undefined }
+obj.x ?= 2;
+obj.x; // undefined
+```
+
+```javascript
+var obj = {};
+obj.x ?= 2;
+```
+
+equivalent to:
+
+```javascript
+var obj = {};
+if (!Object.prototype.hasOwnProperty.call(obj, "x")) obj.x = 2;
+```
+
+### Method binding
+
+```javascript
+var fn = obj:method;
+var fn = obj:method("foob");
+
+["foo", "bar"].map(:toUpperCase); // ["FOO", "BAR"]
+[1.1234, 23.53245, 3].map(:toFixed(2)); // ["1.12", "23.53", "3.00"]
+```
+
+equivalent to:
+
+```javascript
+var fn = obj.method.bind(obj);
+var fn = obj.method.bind(obj, "foob");
+
+["foo", "bar"].map(function (val) { return val.toUpperCase(); });
+[1.1234, 23.53245, 3].map(function (val) { return val.toFixed(2); });
+```

doc/plugins.md

@@ -8,9 +8,10 @@
  - [Gobble](https://github.com/gobblejs/gobble-6to5)
  - [Gulp](https://github.com/sindresorhus/gulp-6to5)
  - [Grunt](https://github.com/sindresorhus/grunt-6to5)
+ - [Isparta](https://github.com/douglasduteil/isparta) - Code coverage with `karma` and `instanbul` using 6to5
  - [Jade](https://github.com/Apoxx/jade-6to5)
  - [Jest](https://github.com/6to5/6to5-jest)
- - [JSXHint](https://github.com/STRML/JSXHint) (A wrapper around JSHint to allow linting of JSX files)
+ - [JSXHint](https://github.com/STRML/JSXHint) - A wrapper around JSHint to allow linting of JSX files
  - [Karma](https://github.com/shuhei/karma-6to5-preprocessor)
  - [Mocha](https://github.com/6to5/6to5-mocha)
  - [Rails](https://github.com/josh/sprockets-es6) or via [browserify-rails](https://github.com/6to5/6to5-rails)

doc/polyfill.md

@@ -5,13 +5,23 @@
 [es6-shim](https://github.com/paulmillr/es6-shim) and
 [es6-symbol](https://github.com/medikoo/es6-symbol) polyfills.
 
-## Node
+This will emulate a full ES6 environment. This polyfill is automatically loaded
+when using [6to5-node](usage.md#node).
+
+## Usage
+
+### Node
+
+You need to include the polyfill require at the top the **entry point** to your
+application.
 
 ```javascript
 require("6to5/polyfill");
 ```
 
-## Browser
+### Browser
 
 Available from the `browser-polyfill.js` file within the 6to5 directory of an
-npm release.
+npm release. This needs to be included **before** all your compiled 6to5 code.
+You can either prepend it to your compiled code or include it in a `<script>`
+before it.

doc/react.md

@@ -12,5 +12,6 @@ To disable this behaviour add `react` to your blacklist:
 to5.transform("code", { blacklist: ["react"] });
 ```
 
-
-    $ 6to5 --blacklist react
+```sh
+$ 6to5 --blacklist react
+```

doc/usage.md

@@ -4,47 +4,67 @@
 
 Compile the file `script.js` and output it to stdout.
 
-    $ 6to5 script.js
+```sh
+$ 6to5 script.js
+```
 
 Compile the file `script.js` and output it to `script-compiled.js`.
 
-    $ 6to5 script.js --out-file script-compiled.js
+```sh
+$ 6to5 script.js --out-file script-compiled.js
+```
 
 Compile the file `script.js` and output it to `script-compiled.js` and save a
 source map to `script-compiled.js.map`.
 
-    $ 6to5 script.js --source-maps --out-file script-compiled.js
+```sh
+$ 6to5 script.js --source-maps --out-file script-compiled.js
+```
 
 Compile the file `script.js` and output it to `script-compiled.js` with a source
 map embedded in a comment at the bottom.
 
-    $ 6to5 script.js --source-maps-inline --out-file script-compiled.js
+```sh
+$ 6to5 script.js --source-maps-inline --out-file script-compiled.js
+```
 
 Compile the entire `src` directory and output it to the `lib` directory.
 
-    $ 6to5 src --out-dir lib
+```sh
+$ 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
+```sh
+$ 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
+```sh
+$ 6to5 --out-file script-compiled.js < script.js
+```
 
 ### Node
 
 Launch a repl.
 
-    $ 6to5-node
+```sh
+$ 6to5-node
+```
 
 Evaluate code.
 
-    $ 6to5-node -e "class Test { }"
+```sh
+$ 6to5-node -e "class Test { }"
+```
 
 Compile and run `test.js`.
 
-    $ 6to5-node test
+```sh
+$ 6to5-node test
+```
 
 ## Node
 
@@ -115,12 +135,19 @@ to5.transformFile("filename.js", options, function (err, result) {
   sourceFileName: "filename",
 
   // The root from which all sources are relative
+  // Default: `moduleRoot` option.
   sourceRoot: "assets/scripts",
 
   // Optional prefix for the AMD module formatter that will be prepend to the
   // filename on module definitions
+  // Default: `sourceRoot` option.
   moduleRoot: "my-app",
 
+  // If truthy, insert an explicit id for each defined AMD module.
+  // By default, AMD modules are anonymous.
+  // Default: false
+  amdModuleIds: true,
+
   // 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
@@ -128,7 +155,11 @@ to5.transformFile("filename.js", options, function (err, result) {
 
   // Output comments in generated output
   // Default: true
-  comments: false
+  comments: false,
+
+  // Enable support for experimental ES7 features
+  // Default: false
+  experimental: true
 }
 ```
 
@@ -174,3 +205,12 @@ require("6to5/register")({
   extensions: [".js", ".es6"]
 });
 ```
+
+## Experimental
+
+6to5 also has experimental support for ES7 proposals. You can enable this with
+the `experimental: true` option when using the [Node API](#node) or
+`--experimental` when using the [CLI](#cli).
+
+**WARNING:** These proposals are subject to change so use with
+**extreme caution**.

lib/6to5/file.js

@@ -10,30 +10,38 @@ var t         = require("./types");
 var _         = require("lodash");
 
 function File(opts) {
-  this.opts            = File.normaliseOptions(opts);
-  this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
-
-  this.declarations = {};
-  this.uids         = {};
-  this.ast          = {};
+  this.opts = File.normaliseOptions(opts);
+  this.uids = {};
+  this.ast  = {};
 }
 
-File.declarations = ["extends", "class-props", "slice", "apply-constructor",
-                     "tagged-template-literal", "interop-require"];
+File.declarations = [
+  "extends",
+  "class-props",
+  "apply-constructor",
+  "tagged-template-literal",
+  "interop-require",
+  "to-array",
+  "object-spread",
+  "has-own",
+  "slice"
+];
 
 File.normaliseOptions = function (opts) {
   opts = _.cloneDeep(opts || {});
 
   _.defaults(opts, {
-    whitespace: true,
-    blacklist:  [],
-    whitelist:  [],
-    sourceMap:  false,
-    comments:   true,
-    filename:   "unknown",
-    modules:    "common",
-    runtime:    false,
-    code:       true
+    experimental: false,
+    playground:   false,
+    whitespace:   true,
+    blacklist:    [],
+    whitelist:    [],
+    sourceMap:    false,
+    comments:     true,
+    filename:     "unknown",
+    modules:      "common",
+    runtime:      false,
+    code:         true
   });
 
   // normalise windows path separators to unix
@@ -63,12 +71,26 @@ File.normaliseOptions = function (opts) {
     opts.runtime = "to5Runtime";
   }
 
+  if (opts.playground) {
+    opts.experimental = true;
+  }
+
   transform._ensureTransformerNames("blacklist", opts.blacklist);
   transform._ensureTransformerNames("whitelist", opts.whitelist);
 
   return opts;
 };
 
+File.prototype.toArray = function (node) {
+  if (t.isArrayExpression(node)) {
+    return node;
+  } else if (t.isIdentifier(node) && node.name === "arguments") {
+    return t.callExpression(t.memberExpression(this.addDeclaration("slice"), t.identifier("call")), [node]);
+  } else {
+    return t.callExpression(this.addDeclaration("to-array"), [node]);
+  }
+};
+
 File.prototype.getModuleFormatter = function (type) {
   var ModuleFormatter = _.isFunction(type) ? type : transform.moduleFormatters[type];
 
@@ -101,8 +123,10 @@ File.prototype.addDeclaration = function (name) {
     throw new ReferenceError("unknown declaration " + name);
   }
 
-  var declar = this.declarations[name];
-  if (declar) return declar.uid;
+  var program = this.ast.program;
+
+  var declar = program._declarations && program._declarations[name];
+  if (declar) return declar.id;
 
   var ref;
   var runtimeNamespace = this.opts.runtime;
@@ -113,11 +137,12 @@ File.prototype.addDeclaration = function (name) {
     ref = util.template(name);
   }
 
-  var uid = t.identifier(this.generateUid(name));
-  this.declarations[name] = {
-    uid: uid,
-    node: ref
-  };
+  var uid = this.generateUidIdentifier(name);
+  this.scope.push({
+    key: name,
+    id: uid,
+    init: ref
+  });
   return uid;
 };
 
@@ -147,7 +172,8 @@ File.prototype.parse = function (code) {
 
 File.prototype.transform = function (ast) {
   this.ast = ast;
-  this.scope = new Scope(null, ast.program);
+  this.scope = new Scope(ast.program);
+  this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
 
   var self = this;
 
@@ -196,6 +222,10 @@ File.prototype.generateUid = function (name, scope) {
   return uid;
 };
 
+File.prototype.generateUidIdentifier = function (name, scope) {
+  return t.identifier(this.generateUid(name, scope));
+};
+
 File.prototype._generateUid = function (name) {
   var uids = this.uids;
   var i = uids[name] || 1;

lib/6to5/generation/generator.js

@@ -53,6 +53,7 @@ CodeGenerator.generators = {
   comprehensions:   require("./generators/comprehensions"),
   expressions:      require("./generators/expressions"),
   statements:       require("./generators/statements"),
+  playground:       require("./generators/playground"),
   classes:          require("./generators/classes"),
   methods:          require("./generators/methods"),
   modules:          require("./generators/modules"),
@@ -160,7 +161,7 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
 
     this.printTrailingComments(node, parent);
   } else {
-    throw new ReferenceError("unknown node " + node.type + " " + JSON.stringify(node));
+    throw new ReferenceError("unknown node " + node.type);
   }
 };
 

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

@@ -0,0 +1,7 @@
+var _ = require("lodash");
+
+_.each(["BindMemberExpression", "BindFunctionExpression"], function (type) {
+  exports[type] = function () {
+    throw new ReferenceError("Trying to render non-standard playground node " + JSON.stringify(type));
+  };
+});

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

@@ -4,11 +4,18 @@ exports.Identifier = function (node) {
   this.push(node.name);
 };
 
-exports.SpreadElement = function (node, print) {
+exports.SpreadElement =
+exports.SpreadProperty = function (node, print) {
   this.push("...");
   print(node.argument);
 };
 
+exports.VirtualPropertyExpression = function (node, print) {
+  print(node.object);
+  this.push("::");
+  print(node.property);
+};
+
 exports.ObjectExpression =
 exports.ObjectPattern = function (node, print) {
   var props = node.properties;
@@ -78,7 +85,7 @@ exports.Literal = function (node) {
     val = JSON.stringify(val);
 
     // escape unicode characters
-    val = val.replace(/[\u007f-\uffff]/g, function(c) {
+    val = val.replace(/[\u007f-\uffff]/g, function (c) {
       return "\\u" + ("0000" + c.charCodeAt(0).toString(16)).slice(-4);
     });
 

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

@@ -24,15 +24,7 @@ function Node(node, parent) {
 }
 
 Node.prototype.isUserWhitespacable = function () {
-  var parent = this.parent;
-  var node = this.node;
-
-  if (t.isUserWhitespacable(node) ||
-      t.isSequenceExpression(parent)) {
-    return true;
-  }
-
-  return false;
+  return t.isUserWhitespacable(this.node);
 };
 
 Node.prototype.needsWhitespace = function (type) {

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

@@ -9,6 +9,10 @@ exports.before = {
       }
     },
 
+    SpreadProperty: function (node, parent) {
+      return exports.before.nodes.Property(node, parent);
+    },
+
     SwitchCase: function (node, parent) {
       if (parent.cases[0] === node) {
         return 1;

lib/6to5/patch.js

@@ -3,6 +3,7 @@ var _ = require("lodash");
 
 var types = require("ast-types");
 var def   = types.Type.def;
+var or    = types.Type.or;
 
 // Program wrapper
 def("File")
@@ -16,12 +17,33 @@ def("ParenthesizedExpression")
   .build("expression")
   .field("expression", def("Expression"));
 
-// Same as ImportNamespaceSpecifier but `id` is `name`
+// Acorn - Same as ImportNamespaceSpecifier but `id` is `name`
 def("ImportBatchSpecifier")
   .bases("Specifier")
   .build("name")
   .field("name", def("Identifier"));
 
+// Abstract references
+def("VirtualPropertyExpression")
+  .bases("Expression")
+  .build("object", "property")
+  .field("object", def("Expression"))
+  .field("property", or(def("Identifier"), def("Expression")));
+
+// Playground
+def("BindMemberExpression")
+  .bases("Expression")
+  .build("object", "property", "arguments")
+  .field("object", def("Expression"))
+  .field("property", or(def("Identifier"), def("Expression")))
+  .field("arguments", [def("Expression")]);
+
+def("BindFunctionExpression")
+  .bases("Expression")
+  .build("callee", "arguments")
+  .field("callee", def("Expression"))
+  .field("arguments", [def("Expression")]);
+
 types.finalize();
 
 var estraverse = require("estraverse");

lib/6to5/polyfill.js

@@ -1,6 +1,37 @@
+/* jshint newcap: false */
+
+var ensureSymbol = function (key) {
+  Symbol[key] = Symbol[key] || Symbol();
+};
+
+var ensureProto = function (Constructor, key, val) {
+  var proto = Constructor.prototype;
+  proto[key] = proto[key] || val;
+};
+
+//
+
 if (typeof Symbol === "undefined") {
   require("es6-symbol/implement");
 }
 
 require("es6-shim");
-require("./transformation/transformers/generators/runtime");
+require("./transformation/transformers/es6-generators/runtime");
+
+// Abstract references
+
+ensureSymbol("referenceGet");
+ensureSymbol("referenceSet");
+ensureSymbol("referenceDelete");
+
+ensureProto(Function, Symbol.referenceGet, function () { return this; });
+
+ensureProto(Map, Symbol.referenceGet, Map.prototype.get);
+ensureProto(Map, Symbol.referenceSet, Map.prototype.set);
+ensureProto(Map, Symbol.referenceDelete, Map.prototype.delete);
+
+if (global.WeakMap) {
+  ensureProto(WeakMap, Symbol.referenceGet, WeakMap.prototype.get);
+  ensureProto(WeakMap, Symbol.referenceSet, WeakMap.prototype.set);
+  ensureProto(WeakMap, Symbol.referenceDelete, WeakMap.prototype.delete);
+}

lib/6to5/register.js

@@ -1,8 +1,10 @@
 require("./polyfill");
 
 var sourceMapSupport = require("source-map-support");
+var roadrunner       = require('roadrunner');
 var util             = require("./util");
 var to5              = require("./index");
+var fs               = require("fs");
 var _                = require("lodash");
 
 sourceMapSupport.install({
@@ -57,24 +59,41 @@ blacklistTest("unicodeRegex", function () { new RegExp("foo", "u"); });
 
 //
 
-var ignoreRegex = /node_modules/;
+var transformOpts = {};
+var ignoreRegex   = /node_modules/;
 var onlyRegex;
-var whitelist   = [];
-var exts        = {};
-var maps        = {};
-var old         = require.extensions[".js"];
+var whitelist     = [];
+var cache;
+var exts          = {};
+var maps          = {};
+var old           = require.extensions[".js"];
+
+var mtime = function (filename) {
+  return +fs.statSync(filename).mtime;
+};
 
 var loader = function (m, filename) {
   if ((ignoreRegex && ignoreRegex.test(filename)) || (onlyRegex && !onlyRegex.test(filename))) {
     return old.apply(this, arguments);
   }
 
-  var result = to5.transformFileSync(filename, {
+  var result;
+
+  if (cache && cache[filename].mtime === mtime(filename)) {
+    result = cache[filename];
+  }
+
+  result = result || to5.transformFileSync(filename, _.extend({
     whitelist: whitelist,
     blacklist: blacklist,
     sourceMap: true,
     modules:   "commonInterop"
-  });
+  }, transformOpts));
+
+  if (cache) {
+    result.mtime = mtime(filename);
+    cache[filename] = result;
+  }
 
   maps[filename] = result.map;
 
@@ -107,6 +126,8 @@ module.exports = function (opts) {
 
   if (opts.extensions) hookExtensions(util.arrayify(opts.extensions));
 
-  if (opts.blacklist) blacklist = util.arrayify(opts.blacklist);
-  if (opts.whitelist) whitelist = util.arrayify(opts.whitelist);
+  if (opts.cache) cache = roadrunner.get('6to5');
+  if (opts.cache === false) cache = null;
+
+  _.extend(transformOpts, opts);
 };

lib/6to5/runtime.js

@@ -8,15 +8,13 @@ module.exports = function (namespace) {
   namespace = t.identifier(t.toIdentifier(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));
+  var container = t.functionExpression(null, [t.identifier("global")], t.blockStatement(body));
+  var tree      = t.program([t.expressionStatement(t.callExpression(container, [util.template("self-global")]))]);
 
   body.push(t.variableDeclaration("var", [
     t.variableDeclarator(
       namespace,
-      t.assignmentExpression("=", t.memberExpression(t.identifier("self"), namespace), t.objectExpression([]))
+      t.assignmentExpression("=", t.memberExpression(t.identifier("global"), namespace), t.objectExpression([]))
     )
   ]));
 

lib/6to5/templates/abstract-expression-call.js

@@ -0,0 +1 @@
+PROPERTY[Symbol.referenceGet](OBJECT).call(OBJECT)

lib/6to5/templates/abstract-expression-delete.js

@@ -0,0 +1 @@
+PROPERTY[Symbol.referenceDelete](OBJECT)

lib/6to5/templates/abstract-expression-get.js

@@ -0,0 +1 @@
+PROPERTY[Symbol.referenceGet](OBJECT)

lib/6to5/templates/abstract-expression-set.js

@@ -0,0 +1 @@
+PROPERTY[Symbol.referenceSet](OBJECT, VALUE)

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

@@ -1,5 +1,5 @@
 (function (Constructor, args) {
-  var bindArgs = [null].concat(args);
-  var Factory = Constructor.bind.apply(Constructor, bindArgs);
-  return new Factory;
+  var instance = Object.create(Constructor.prototype);
+  var result = Constructor.apply(instance, args);
+  return result != null && (typeof result == "object" || typeof result == "function") ? result : instance;
 });

lib/6to5/templates/arguments-slice-assign-arg.js

@@ -1 +0,0 @@
-var VARIABLE_NAME = SLICE_KEY.call(arguments, SLICE_ARG);

lib/6to5/templates/arguments-slice-assign.js

@@ -1 +0,0 @@
-var VARIABLE_NAME = SLICE_KEY.call(arguments);

lib/6to5/templates/arguments-slice.js

@@ -1 +0,0 @@
-SLICE_KEY.call(arguments);

lib/6to5/templates/array-from.js

@@ -0,0 +1 @@
+Array.from(VALUE);

lib/6to5/templates/exports-default-module.js

@@ -0,0 +1 @@
+module.exports = VALUE;

lib/6to5/templates/has-own.js

@@ -0,0 +1 @@
+Object.prototype.hasOwnProperty;

lib/6to5/templates/object-spread.js

@@ -0,0 +1,9 @@
+(function (obj, keys) {
+  var target = {};
+  for (var i in obj) {
+    if (keys.indexOf(i) >= 0) continue;
+    if (!Object.prototype.hasOwnProperty.call(obj, i)) continue;
+    target[i] = obj[i];
+  }
+  return target;
+})

lib/6to5/templates/register.js

@@ -0,0 +1 @@
+System.register(MODULE_NAME, MODULE_DEPENDENCIES, MODULE_BODY);

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

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

lib/6to5/templates/to-array.js

@@ -0,0 +1,3 @@
+(function (arr) {
+  return Array.isArray(arr) ? arr : Array.from(arr);
+});

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

@@ -29,39 +29,23 @@ AMDFormatter.prototype.transform = function (ast) {
   var params = _.values(this.ids);
   params.unshift(t.identifier("exports"));
 
-  var moduleName = this.getModuleName();
-
   var container = t.functionExpression(null, params, t.blockStatement(body));
-  var call = t.callExpression(t.identifier("define"), [t.literal(moduleName), names, container]);
+
+  var defineArgs = [names, container];
+  var moduleName = this.getModuleName();
+  if (moduleName) defineArgs.unshift(t.literal(moduleName));
+
+  var call = t.callExpression(t.identifier("define"), defineArgs);
 
   program.body = [t.expressionStatement(call)];
 };
 
 AMDFormatter.prototype.getModuleName = function () {
-  var opts = this.file.opts;
-  var filenameRelative = opts.filenameRelative;
-  var moduleName = "";
-
-  if (opts.moduleRoot) {
-    moduleName = opts.moduleRoot + "/";
+  if (this.file.opts.amdModuleIds) {
+    return CommonJSFormatter.prototype.getModuleName.apply(this, arguments);
+  } else {
+    return null;
   }
-
-  if (!opts.filenameRelative) {
-    return moduleName + opts.filename.replace(/^\//, "");
-  }
-
-  if (opts.sourceRoot) {
-    // remove sourceRoot from filename
-    var sourceRootRegEx = new RegExp("^" + opts.sourceRoot + "\/?");
-    filenameRelative = filenameRelative.replace(sourceRootRegEx, "");
-  }
-
-  // remove extension
-  filenameRelative = filenameRelative.replace(/\.(.*?)$/, "");
-
-  moduleName += filenameRelative;
-
-  return moduleName;
 };
 
 AMDFormatter.prototype._push = function (node) {
@@ -71,7 +55,7 @@ AMDFormatter.prototype._push = function (node) {
   if (ids[id]) {
     return ids[id];
   } else {
-    return this.ids[id] = t.identifier(this.file.generateUid(id));
+    return this.ids[id] = this.file.generateUidIdentifier(id);
   }
 };
 

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

@@ -3,9 +3,16 @@ module.exports = CommonJSInteropFormatter;
 var CommonJSFormatter = require("./common");
 var util              = require("../../util");
 var t                 = require("../../types");
+var _                 = require("lodash");
 
 function CommonJSInteropFormatter(file) {
-  this.file = file;
+  CommonJSFormatter.apply(this, arguments);
+
+  var has = false;
+  _.each(file.ast.program.body, function (node) {
+    if (t.isExportDeclaration(node) && !node.default) has = true;
+  });
+  this.has = has;
 }
 
 util.inherits(CommonJSInteropFormatter, CommonJSFormatter);
@@ -22,8 +29,28 @@ CommonJSInteropFormatter.prototype.importSpecifier = function (specifier, node,
         })])
       )
     ]));
+  } else {
+    CommonJSFormatter.prototype.importSpecifier.apply(this, arguments);
+  }
+};
+
+CommonJSInteropFormatter.prototype.export = function (node, nodes) {
+  if (node.default && !this.has) {
+    var declar = node.declaration;
+
+    // module.exports = VALUE;
+    var assign = util.template("exports-default-module", {
+      VALUE: this._pushStatement(declar, nodes)
+    }, true);
+
+    // hoist to the top if this default is a function
+    nodes.push(this._hoistExport(declar, assign));
     return;
   }
 
-  CommonJSFormatter.prototype.importSpecifier.apply(this, arguments);
+  CommonJSFormatter.prototype.export.apply(this, arguments);
+};
+
+CommonJSInteropFormatter.prototype.exportSpecifier = function () {
+  CommonJSFormatter.prototype.exportSpecifier.apply(this, arguments);
 };

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

@@ -7,6 +7,33 @@ function CommonJSFormatter(file) {
   this.file = file;
 }
 
+CommonJSFormatter.prototype.getModuleName = function () {
+  var opts = this.file.opts;
+  var filenameRelative = opts.filenameRelative;
+  var moduleName = "";
+
+  if (opts.moduleRoot) {
+    moduleName = opts.moduleRoot + "/";
+  }
+
+  if (!opts.filenameRelative) {
+    return moduleName + opts.filename.replace(/^\//, "");
+  }
+
+  if (opts.sourceRoot) {
+    // remove sourceRoot from filename
+    var sourceRootRegEx = new RegExp("^" + opts.sourceRoot + "\/?");
+    filenameRelative = filenameRelative.replace(sourceRootRegEx, "");
+  }
+
+  // remove extension
+  filenameRelative = filenameRelative.replace(/\.(.*?)$/, "");
+
+  moduleName += filenameRelative;
+
+  return moduleName;
+};
+
 CommonJSFormatter.prototype.import = function (node, nodes) {
   // import "foo";
   nodes.push(util.template("require", {
@@ -38,23 +65,32 @@ CommonJSFormatter.prototype.importSpecifier = function (specifier, node, nodes)
   }));
 };
 
+CommonJSFormatter.prototype._hoistExport = function (declar, assign) {
+  if (t.isFunctionDeclaration(declar)) {
+    assign._blockHoist = true;
+  }
+
+  return assign;
+};
+
+CommonJSFormatter.prototype._pushStatement = function (ref, nodes) {
+  if (t.isClass(ref) || t.isFunction(ref)) {
+    if (ref.id) {
+      nodes.push(t.toStatement(ref));
+      ref = ref.id;
+    }
+  }
+  return ref;
+};
+
 CommonJSFormatter.prototype.export = function (node, nodes) {
   var declar = node.declaration;
 
   if (node.default) {
-    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", {
       //inherits: node,
 
-      VALUE: ref
+      VALUE: this._pushStatement(declar, nodes)
     }, true));
   } else {
     var assign;
@@ -83,9 +119,7 @@ CommonJSFormatter.prototype.export = function (node, nodes) {
       nodes.push(t.toStatement(declar));
       nodes.push(assign);
 
-      if (t.isFunctionDeclaration(declar)) {
-        assign._blockHoist = true;
-      }
+      this._hoistExport(declar, assign);
     }
   }
 };
@@ -126,7 +160,7 @@ CommonJSFormatter.prototype._exportSpecifier = function (getRef, specifier, node
 };
 
 CommonJSFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
-  return this._exportSpecifier(function () {
+  this._exportSpecifier(function () {
     return t.callExpression(t.identifier("require"), [node.source]);
   }, specifier, node, nodes);
 };

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

@@ -0,0 +1,202 @@
+module.exports = SystemFormatter;
+
+var util = require("../../util");
+var t    = require("../../types");
+var _    = require("lodash");
+
+var SETTER_MODULE_NAMESPACE = t.identifier("m");
+var DEFAULT_IDENTIFIER      = t.identifier("default");
+var NULL_SETTER             = t.literal(null);
+
+function SystemFormatter(file) {
+  this.exportedStatements = [];
+  this.importedModule     = {};
+
+  this.exportIdentifier   = file.generateUidIdentifier("export");
+  this.file               = file;
+}
+
+SystemFormatter.prototype.transform = function (ast) {
+  var program = ast.program;
+  var body    = program.body;
+
+  // extract the module name
+  var moduleName = this.file.opts.filename
+    .replace(/^.*\//, "").replace(/\..*$/, "");
+
+  // build an array of module names
+  var dependencies = Object.keys(this.importedModule).map(t.literal);
+
+  // generate the __moduleName variable
+  var moduleNameVariableNode = t.variableDeclaration("var", [
+    t.variableDeclarator(
+      t.identifier("__moduleName"),
+      t.literal(moduleName)
+    )
+  ]);
+  body.splice(1, 0, moduleNameVariableNode);
+
+  // generate an array of import variables
+
+  var declaredSetters = _(this.importedModule)
+    .map()
+    .flatten()
+    .pluck("variableName")
+    .pluck("name")
+    .uniq()
+    .map(t.identifier)
+    .map(function (name) {
+      return t.variableDeclarator(name);
+    })
+    .value();
+
+  if (declaredSetters.length) {
+    body.splice(2, 0, t.variableDeclaration("var", declaredSetters));
+  }
+
+  // generate the execute function expression
+  var executeFunctionExpression = t.functionExpression(
+    null, [], t.blockStatement(this.exportedStatements)
+  );
+
+  // generate the execute function expression
+  var settersArrayExpression = t.arrayExpression(this._buildSetters());
+
+  // generate the return statement
+  var moduleReturnStatement = t.returnStatement(t.objectExpression([
+    t.property("init", t.identifier("setters"), settersArrayExpression),
+    t.property("init", t.identifier("execute"), executeFunctionExpression)
+  ]));
+  body.push(moduleReturnStatement);
+
+  // runner
+  var runner = util.template("register", {
+    MODULE_NAME: t.literal(moduleName),
+    MODULE_DEPENDENCIES: t.arrayExpression(dependencies),
+    MODULE_BODY: t.functionExpression(
+      null,
+      [this.exportIdentifier],
+      t.blockStatement(body)
+    )
+  });
+
+  program.body = [t.expressionStatement(runner)];
+};
+
+SystemFormatter.prototype._buildSetters = function () {
+  // generate setters array expression elements
+  return _.map(this.importedModule, function (specs) {
+    if (!specs.length) {
+      return NULL_SETTER;
+    }
+
+    var expressionStatements = _.map(specs, function (spec) {
+      var right = SETTER_MODULE_NAMESPACE;
+      if (!spec.isBatch) {
+        right = t.memberExpression(right, spec.key);
+      }
+
+      return t.expressionStatement(
+        t.assignmentExpression("=", spec.variableName, right
+        )
+      );
+    });
+
+    return t.functionExpression(
+      null, [SETTER_MODULE_NAMESPACE], t.blockStatement(expressionStatements)
+    );
+  });
+};
+
+SystemFormatter.prototype.import = function (node) {
+  var MODULE_NAME = node.source.value;
+  this.importedModule[MODULE_NAME] = this.importedModule[MODULE_NAME] || [];
+};
+
+SystemFormatter.prototype.importSpecifier = function (specifier, node) {
+  var variableName = t.getSpecifierName(specifier);
+
+  // import foo from "foo";
+  if (specifier.default) {
+    specifier.id = DEFAULT_IDENTIFIER;
+  }
+
+  var MODULE_NAME = node.source.value;
+
+  this.importedModule[MODULE_NAME] = this.importedModule[MODULE_NAME] || [];
+
+  this.importedModule[MODULE_NAME].push({
+    variableName: variableName,
+    isBatch:      specifier.type === "ImportBatchSpecifier",
+    key:          specifier.id
+  });
+};
+
+SystemFormatter.prototype._export = function (name, identifier) {
+  this.exportedStatements.push(t.expressionStatement(
+    t.callExpression(this.exportIdentifier, [t.literal(name), identifier])
+  ));
+};
+
+SystemFormatter.prototype.export = function (node, nodes) {
+  var declar = node.declaration;
+  var variableName, identifier;
+
+  if (node.default) {
+    // export default foo
+    variableName = DEFAULT_IDENTIFIER.name;
+    if (t.isClass(declar) || t.isFunction(declar)) {
+      if (!declar.id) {
+        declar.id = this.file.generateUidIdentifier("anonymous");
+      }
+
+      nodes.push(t.toStatement(declar));
+      declar = declar.id;
+    }
+
+    identifier = declar;
+  } else if (t.isVariableDeclaration(declar)) {
+    // export var foo
+    variableName = declar.declarations[0].id.name;
+    identifier = declar.declarations[0].id;
+
+    nodes.push(declar);
+  } else {
+    // export function foo () {}
+    variableName = declar.id.name;
+    identifier = declar.id;
+
+    nodes.push(declar);
+  }
+
+  this._export(variableName, identifier);
+};
+
+SystemFormatter.prototype.exportSpecifier = function (specifier, node) {
+  var variableName = t.getSpecifierName(specifier);
+
+  if (node.source) {
+    if (t.isExportBatchSpecifier(specifier)) {
+      // export * from "foo";
+      var exportIdentifier = t.identifier("exports");
+      this.exportedStatements.push(
+        t.variableDeclaration("var", [
+          t.variableDeclarator(exportIdentifier, this.exportIdentifier)
+        ])
+      );
+
+      this.exportedStatements.push(util.template("exports-wildcard", {
+        OBJECT: t.identifier(node.source.value)
+      }, true));
+    } else {
+      // export { foo } from "test";
+      this._export(variableName.name, t.memberExpression(
+        t.identifier(node.source.value),
+        specifier.id
+      ));
+    }
+  } else {
+    // export { foo };
+    this._export(variableName.name, specifier.id);
+  }
+};

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

@@ -5,9 +5,8 @@ var util         = require("../../util");
 var t            = require("../../types");
 var _            = require("lodash");
 
-function UMDFormatter(file) {
-  this.file = file;
-  this.ids  = {};
+function UMDFormatter() {
+  AMDFormatter.apply(this, arguments);
 }
 
 util.inherits(UMDFormatter, AMDFormatter);
@@ -32,10 +31,12 @@ UMDFormatter.prototype.transform = function (ast) {
 
   // runner
 
+  var defineArgs = [t.arrayExpression([t.literal("exports")].concat(names))];
   var moduleName = this.getModuleName();
+  if (moduleName) defineArgs.unshift(t.literal(moduleName));
 
   var runner = util.template("umd-runner-body", {
-    AMD_ARGUMENTS: [t.literal(moduleName), t.arrayExpression([t.literal("exports")].concat(names))],
+    AMD_ARGUMENTS: defineArgs,
 
     COMMON_ARGUMENTS: names.map(function (name) {
       return t.callExpression(t.identifier("require"), [name]);

lib/6to5/transformation/transform.js

@@ -22,36 +22,43 @@ transform.transformers = {};
 transform.moduleFormatters = {
   common:        require("./modules/common"),
   commonInterop: require("./modules/common-interop"),
+  system:        require("./modules/system"),
   ignore:        require("./modules/ignore"),
   amd:           require("./modules/amd"),
   umd:           require("./modules/umd")
 };
 
 _.each({
-  modules:                   require("./transformers/modules"),
-  propertyNameShorthand:     require("./transformers/property-name-shorthand"),
-  arrayComprehension:        require("./transformers/array-comprehension"),
-  generatorComprehension:    require("./transformers/generator-comprehension"),
-  arrowFunctions:            require("./transformers/arrow-functions"),
-  classes:                   require("./transformers/classes"),
+  modules:                   require("./transformers/es6-modules"),
+  propertyNameShorthand:     require("./transformers/es6-property-name-shorthand"),
+  arrayComprehension:        require("./transformers/es7-array-comprehension"),
+  generatorComprehension:    require("./transformers/es7-generator-comprehension"),
+  arrowFunctions:            require("./transformers/es6-arrow-functions"),
+  classes:                   require("./transformers/es6-classes"),
 
-  _propertyLiterals:         require("./transformers/_property-literals"),
-  computedPropertyNames:     require("./transformers/computed-property-names"),
+  computedPropertyNames:     require("./transformers/es6-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"),
-  forOf:                     require("./transformers/for-of"),
-  unicodeRegex:              require("./transformers/unicode-regex"),
+  objectSpread:              require("./transformers/es7-object-spread"),
+  exponentiationOperator:    require("./transformers/es7-exponentiation-operator"),
+  spread:                    require("./transformers/es6-spread"),
+  templateLiterals:          require("./transformers/es6-template-literals"),
+  propertyMethodAssignment:  require("./transformers/es5-property-method-assignment"),
+  defaultParameters:         require("./transformers/es6-default-parameters"),
+  restParameters:            require("./transformers/es6-rest-parameters"),
+  destructuring:             require("./transformers/es6-destructuring"),
+  forOf:                     require("./transformers/es6-for-of"),
+  unicodeRegex:              require("./transformers/es6-unicode-regex"),
+  abstractReferences:        require("./transformers/es7-abstract-references"),
   react:                     require("./transformers/react"),
 
-  constants:                 require("./transformers/constants"),
-  letScoping:                require("./transformers/let-scoping"),
+  constants:                 require("./transformers/es6-constants"),
+  letScoping:                require("./transformers/es6-let-scoping"),
 
-  generators:                require("./transformers/generators"),
+  generators:                require("./transformers/es6-generators"),
+
+  // plyground
+  methodBinding:             require("./transformers/playground-method-binding"),
+  memoizationOperator:       require("./transformers/playground-memoization-operator"),
 
   _blockHoist:               require("./transformers/_block-hoist"),
   _declarations:             require("./transformers/_declarations"),
@@ -59,7 +66,8 @@ _.each({
 
   useStrict:                 require("./transformers/use-strict"),
 
-  _memberExpressionKeywords: require("./transformers/_member-expression-keywords"),
+  _propertyLiterals:         require("./transformers/_property-literals"),
+  _memberExpressioLiterals:  require("./transformers/_member-expression-literals"),
   _moduleFormatter:          require("./transformers/_module-formatter")
 }, function (transformer, key) {
   transform.transformers[key] = new Transformer(key, transformer);

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

@@ -6,11 +6,11 @@ var go = function (getBody, node, file, scope) {
   var thisId;
 
   var getArgumentsId = function () {
-    return argumentsId = argumentsId || t.identifier(file.generateUid("arguments", scope));
+    return argumentsId = argumentsId || file.generateUidIdentifier("arguments", scope);
   };
 
   var getThisId = function () {
-    return thisId = thisId || t.identifier(file.generateUid("this", scope));
+    return thisId = thisId || file.generateUidIdentifier("this", scope);
   };
 
   // traverse the function and find all alias functions so we can alias
@@ -31,7 +31,7 @@ var go = function (getBody, node, file, scope) {
         return false;
       }
 
-      if (node._ignoreAliasFunctions) return;
+      if (node._ignoreAliasFunctions) return false;
 
       var getId;
 

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

@@ -1,12 +1,23 @@
 var t = require("../../types");
 var _ = require("lodash");
 
-module.exports = function (ast, file) {
-  var body = ast.program.body;
+exports.BlockStatement =
+exports.Program = function (node) {
+  var kinds = {};
 
-  _.each(file.declarations, function (declar) {
-    body.unshift(t.variableDeclaration("var", [
-      t.variableDeclarator(declar.uid, declar.node)
-    ]));
+  _.each(node._declarations, function (declar) {
+    var kind = declar.kind || "var";
+    var declarNode = t.variableDeclarator(declar.id, declar.init);
+
+    if (!declar.init) {
+      kinds[kind] = kinds[kind] || [];
+      kinds[kind].push(declarNode);
+    } else {
+      node.body.unshift(t.variableDeclaration(kind, [declarNode]));
+    }
+  });
+
+  _.each(kinds, function (declars, kind) {
+    node.body.unshift(t.variableDeclaration(kind, declars));
   });
 };

lib/6to5/transformation/transformers/_member-expression-keywords.js

@@ -1,10 +0,0 @@
-var esutils = require("esutils");
-var t = require("../../types");
-
-exports.MemberExpression = function (node) {
-  var prop = node.property;
-  if (t.isIdentifier(prop) && esutils.keyword.isKeywordES6(prop.name, true)) {
-    node.property = t.literal(prop.name);
-    node.computed = true;
-  }
-};

lib/6to5/transformation/transformers/_member-expression-literals.js

@@ -0,0 +1,14 @@
+var esutils = require("esutils");
+var t       = require("../../types");
+
+exports.MemberExpression = function (node) {
+  var prop = node.property;
+  if (node.computed && t.isLiteral(prop) && t.isValidIdentifier(prop.value)) {
+    // computed literal that is a valid identifier
+    node.property = t.identifier(prop.value);
+    node.computed = false;
+  } else if (!node.computed && t.isIdentifier(prop) && esutils.keyword.isKeywordES6(prop.name, true)) {
+    node.property = t.literal(prop.name);
+    node.computed = true;
+  }
+};

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

@@ -1,15 +1,14 @@
 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;
-
+  if (t.isLiteral(key) && t.isValidIdentifier(key.value)) {
+    // property key is a literal but a valid identifier
+    node.key = t.identifier(key.value);
     node.computed = false;
+  } else if (!node.computed && t.isIdentifier(key) && esutils.keyword.isKeywordES6(key.name, true)) {
+    // property key is a keyword
+    node.key = t.literal(key.name);
   }
 };

lib/6to5/transformation/transformers/es6-classes.js

@@ -4,9 +4,13 @@ var t        = require("../../types");
 var _        = require("lodash");
 
 exports.ClassDeclaration = function (node, parent, file, scope) {
-  return t.variableDeclaration("let", [
-    t.variableDeclarator(node.id, new Class(node, file, scope).run())
+  var built = new Class(node, file, scope).run();
+
+  var declar = t.variableDeclaration("let", [
+    t.variableDeclarator(node.id, built)
   ]);
+  t.inheritsComments(declar, node);
+  return declar;
 };
 
 exports.ClassExpression = function (node, parent, file, scope) {
@@ -36,7 +40,7 @@ function Class(node, file, scope) {
   this.instanceMutatorMap = {};
   this.staticMutatorMap   = {};
   this.hasConstructor     = false;
-  this.className          = node.id || t.identifier(file.generateUid("class", scope));
+  this.className          = node.id || file.generateUidIdentifier("class", scope);
   this.superName          = node.superClass;
 }
 
@@ -58,7 +62,7 @@ Class.prototype.run = function () {
       superClassArgument = superClassCallee = getMemberExpressionObject(superName);
     } else if (!t.isIdentifier(superName)) {
       superClassArgument = superName;
-      superClassCallee   = superName = t.identifier(file.generateUid("ref", this.scope));
+      superClassCallee   = superName = file.generateUidIdentifier("ref", this.scope);
     }
   }
 

lib/6to5/transformation/transformers/es6-destructuring.js

@@ -1,60 +1,92 @@
+// TODO: Clean up
+
 var t = require("../../types");
 var _ = require("lodash");
 
-var buildVariableAssign = function (kind, id, init) {
-  if (kind === false) {
+var buildVariableAssign = function (opts, id, init) {
+  var op = opts.operator;
+  if (t.isMemberExpression(id)) op = "=";
+
+  if (op) {
     return t.expressionStatement(t.assignmentExpression("=", id, init));
   } else {
-    return t.variableDeclaration(kind, [
+    return t.variableDeclaration(opts.kind, [
       t.variableDeclarator(id, init)
     ]);
   }
 };
 
-var push = function (kind, nodes, elem, parentId) {
+var push = function (opts, nodes, elem, parentId) {
   if (t.isObjectPattern(elem)) {
-    pushObjectPattern(kind, nodes, elem, parentId);
+    pushObjectPattern(opts, nodes, elem, parentId);
   } else if (t.isArrayPattern(elem)) {
-    pushArrayPattern(kind, nodes, elem, parentId);
-  } else if (t.isMemberExpression(elem)) {
-    nodes.push(buildVariableAssign(false, elem, parentId));
+    pushArrayPattern(opts, nodes, elem, parentId);
   } else {
-    nodes.push(buildVariableAssign(kind, elem, parentId));
+    nodes.push(buildVariableAssign(opts, 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);
+var pushObjectPattern = function (opts, nodes, pattern, parentId) {
+  _.each(pattern.properties, function (prop, i) {
+    if (t.isSpreadProperty(prop)) {
+        // get all the keys that appear in this object before the current spread
+        var keys = [];
+        _.each(pattern.properties, function (prop2, i2) {
+          if (i2 >= i) return false;
+          if (t.isSpreadProperty(prop2)) return;
 
-    if (t.isPattern(pattern2)) {
-      push(kind, nodes, pattern2, patternId2);
+          var key = prop2.key;
+          if (t.isIdentifier(key)) {
+            key = t.literal(prop2.key.name);
+          }
+          keys.push(key);
+        });
+        keys = t.arrayExpression(keys);
+
+        var value = t.callExpression(opts.file.addDeclaration("object-spread"), [parentId, keys]);
+        nodes.push(buildVariableAssign(opts, prop.argument, value));
     } else {
-      nodes.push(buildVariableAssign(kind, pattern2, patternId2));
+      var pattern2   = prop.value;
+      var patternId2 = t.memberExpression(parentId, prop.key, prop.computed);
+
+      if (t.isPattern(pattern2)) {
+        push(opts, nodes, pattern2, patternId2);
+      } else {
+        nodes.push(buildVariableAssign(opts, pattern2, patternId2));
+      }
     }
   });
 };
 
-var pushArrayPattern = function (kind, nodes, pattern, parentId) {
+var pushArrayPattern = function (opts, nodes, pattern, parentId) {
+  var _parentId = opts.file.generateUidIdentifier("ref", opts.scope);
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(_parentId, opts.file.toArray(parentId))
+  ]));
+  parentId = _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)]);
+      newPatternId = opts.file.toArray(parentId);
+
+      if (+i > 0) {
+        newPatternId = t.callExpression(t.memberExpression(newPatternId, t.identifier("slice")), [t.literal(i)]);
+      }
+
       elem = elem.argument;
     } else {
       newPatternId = t.memberExpression(parentId, t.literal(i), true);
     }
 
-    push(kind, nodes, elem, newPatternId);
+    push(opts, nodes, elem, newPatternId);
   });
 };
 
 var pushPattern = function (opts) {
-  var kind = opts.kind;
   var nodes = opts.nodes;
   var pattern = opts.pattern;
   var parentId = opts.id;
@@ -62,7 +94,7 @@ var pushPattern = function (opts) {
   var scope = opts.scope;
 
   if (!t.isMemberExpression(parentId) && !t.isIdentifier(parentId)) {
-    var key = t.identifier(file.generateUid("ref", scope));
+    var key = file.generateUidIdentifier("ref", scope);
 
     nodes.push(t.variableDeclaration("var", [
       t.variableDeclarator(key, parentId)
@@ -71,7 +103,7 @@ var pushPattern = function (opts) {
     parentId = key;
   }
 
-  push(kind, nodes, pattern, parentId);
+  push(opts, nodes, pattern, parentId);
 };
 
 exports.ForInStatement =
@@ -82,14 +114,18 @@ exports.ForOfStatement = function (node, parent, file, scope) {
   var pattern = declar.declarations[0].id;
   if (!t.isPattern(pattern)) return;
 
-  var key = t.identifier(file.generateUid("ref", scope));
+  var key = file.generateUidIdentifier("ref", scope);
   node.left = t.variableDeclaration(declar.kind, [
     t.variableDeclarator(key, null)
   ]);
 
   var nodes = [];
 
-  push(declar.kind, nodes, pattern, key);
+  push({
+    kind: declar.kind,
+    file: file,
+    scope: scope
+  }, nodes, pattern, key);
 
   t.ensureBlock(node);
 
@@ -106,7 +142,7 @@ exports.Function = function (node, parent, file, scope) {
     if (!t.isPattern(pattern)) return pattern;
 
     hasDestructuring = true;
-    var parentId = t.identifier(file.generateUid("ref", scope));
+    var parentId = file.generateUidIdentifier("ref", scope);
 
     pushPattern({
       kind:    "var",
@@ -136,20 +172,43 @@ exports.ExpressionStatement = function (node, parent, file, scope) {
 
   var nodes = [];
 
-  var ref = t.identifier(file.generateUid("ref", scope));
+  var ref = file.generateUidIdentifier("ref", scope);
   nodes.push(t.variableDeclaration("var", [
     t.variableDeclarator(ref, expr.right)
   ]));
 
-  push(false, nodes, expr.left, ref);
+  push({
+    operator: expr.operator,
+    file: file,
+    scope: scope
+  }, nodes, expr.left, ref);
 
   return nodes;
 };
 
-exports.AssignmentExpression = function (node, parent, file) {
+exports.AssignmentExpression = function (node, parent, file, scope) {
   if (parent.type === "ExpressionStatement") return;
   if (!t.isPattern(node.left)) return;
-  throw file.errorWithNode(node, "AssignmentExpression destructuring outside of a ExpressionStatement is forbidden due to current 6to5 limitations");
+
+  var tempName = file.generateUid("temp", scope);
+  var ref = t.identifier(tempName);
+  scope.push({
+    key: tempName,
+    id: ref
+  });
+
+  var nodes = [];
+  nodes.push(t.assignmentExpression("=", ref, node.right));
+
+  push({
+    operator: node.operator,
+    file: file,
+    scope: scope
+  }, nodes, node.left, ref);
+
+  nodes.push(ref);
+
+  return t.toSequenceExpression(nodes, scope);
 };
 
 exports.VariableDeclaration = function (node, parent, file, scope) {
@@ -169,17 +228,18 @@ exports.VariableDeclaration = function (node, parent, file, scope) {
   _.each(node.declarations, function (declar) {
     var patternId = declar.init;
     var pattern   = declar.id;
+    var opts = {
+      kind:    node.kind,
+      nodes:   nodes,
+      pattern: pattern,
+      id:      patternId,
+      file:    file,
+      scope:   scope
+    };
     if (t.isPattern(pattern) && patternId) {
-      pushPattern({
-        kind:    node.kind,
-        nodes:   nodes,
-        pattern: pattern,
-        id:      patternId,
-        file:    file,
-        scope:   scope
-      });
+      pushPattern(opts);
     } else {
-      nodes.push(buildVariableAssign(node.kind, declar.id, declar.init));
+      nodes.push(buildVariableAssign(opts, declar.id, declar.init));
     }
   });
 
@@ -201,4 +261,3 @@ exports.VariableDeclaration = function (node, parent, file, scope) {
 
   return nodes;
 };
-

lib/6to5/transformation/transformers/es6-for-of.js

@@ -5,7 +5,7 @@ exports.ForOfStatement = function (node, parent, file, scope) {
   var left = node.left;
   var declar;
 
-  var stepKey   = t.identifier(file.generateUid("step", scope));
+  var stepKey   = file.generateUidIdentifier("step", scope);
   var stepValue = t.memberExpression(stepKey, t.identifier("value"));
 
   if (t.isIdentifier(left)) {
@@ -19,7 +19,7 @@ exports.ForOfStatement = function (node, parent, file, scope) {
   }
 
   var node2 = util.template("for-of", {
-    ITERATOR_KEY: file.generateUid("iterator", scope),
+    ITERATOR_KEY: file.generateUidIdentifier("iterator", scope),
     STEP_KEY:     stepKey,
     OBJECT:       node.right
   });

lib/6to5/transformation/transformers/es6-generators/emit/explode-expressions.js

@@ -0,0 +1,204 @@
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * https://raw.github.com/facebook/regenerator/master/LICENSE file. An
+ * additional grant of patent rights can be found in the PATENTS file in
+ * the same directory.
+ */
+
+var assert = require("assert");
+var loc    = require("../util").loc;
+var t      = require("../../../../types");
+
+exports.ParenthesizedExpression = function (expr, path, explodeViaTempVar, finish) {
+  return finish(this.explodeExpression(path.get("expression")));
+};
+
+exports.MemberExpression = function (expr, path, explodeViaTempVar, finish) {
+  return finish(t.memberExpression(
+    this.explodeExpression(path.get("object")),
+    expr.computed ? explodeViaTempVar(null, path.get("property")) : expr.property,
+    expr.computed
+  ));
+};
+
+exports.CallExpression = function (expr, path, explodeViaTempVar, finish) {
+  var oldCalleePath = path.get("callee");
+  var newCallee = this.explodeExpression(oldCalleePath);
+
+  // If the callee was not previously a MemberExpression, then the
+  // CallExpression was "unqualified," meaning its `this` object should
+  // be the global object. If the exploded expression has become a
+  // MemberExpression, then we need to force it to be unqualified by
+  // using the (0, object.property)(...) trick; otherwise, it will
+  // receive the object of the MemberExpression as its `this` object.
+  if (!t.isMemberExpression(oldCalleePath.node) && t.isMemberExpression(newCallee)) {
+    newCallee = t.sequenceExpression([
+      t.literal(0),
+      newCallee
+    ]);
+  }
+
+  return finish(t.callExpression(
+    newCallee,
+    path.get("arguments").map(function (argPath) {
+      return explodeViaTempVar(null, argPath);
+    })
+  ));
+};
+
+exports.NewExpression = function (expr, path, explodeViaTempVar, finish) {
+  return finish(t.newExpression(
+    explodeViaTempVar(null, path.get("callee")),
+    path.get("arguments").map(function (argPath) {
+      return explodeViaTempVar(null, argPath);
+    })
+  ));
+};
+
+exports.ObjectExpression = function (expr, path, explodeViaTempVar, finish) {
+  return finish(t.objectExpression(
+    path.get("properties").map(function (propPath) {
+      return t.property(
+        propPath.value.kind,
+        propPath.value.key,
+        explodeViaTempVar(null, propPath.get("value"))
+      );
+    })
+  ));
+};
+
+exports.ArrayExpression = function (expr, path, explodeViaTempVar, finish) {
+  return finish(t.arrayExpression(
+    path.get("elements").map(function (elemPath) {
+      return explodeViaTempVar(null, elemPath);
+    })
+  ));
+};
+
+exports.SequenceExpression = function (expr, path, explodeViaTempVar, finish, ignoreResult) {
+  var lastIndex = expr.expressions.length - 1;
+  var self = this;
+  var result;
+
+  path.get("expressions").each(function (exprPath) {
+    if (exprPath.name === lastIndex) {
+      result = self.explodeExpression(exprPath, ignoreResult);
+    } else {
+      self.explodeExpression(exprPath, true);
+    }
+  });
+
+  return result;
+};
+
+exports.LogicalExpression = function (expr, path, explodeViaTempVar, finish, ignoreResult) {
+  var after = loc();
+  var result;
+
+  if (!ignoreResult) {
+    result = this.makeTempVar();
+  }
+
+  var left = explodeViaTempVar(result, path.get("left"));
+
+  if (expr.operator === "&&") {
+    this.jumpIfNot(left, after);
+  } else {
+    assert.strictEqual(expr.operator, "||");
+    this.jumpIf(left, after);
+  }
+
+  explodeViaTempVar(result, path.get("right"), ignoreResult);
+
+  this.mark(after);
+
+  return result;
+};
+
+exports.ConditionalExpression = function (expr, path, explodeViaTempVar, finish, ignoreResult) {
+  var elseLoc = loc();
+  var after = loc();
+  var test = this.explodeExpression(path.get("test"));
+  var result;
+
+  this.jumpIfNot(test, elseLoc);
+
+  if (!ignoreResult) {
+    result = this.makeTempVar();
+  }
+
+  explodeViaTempVar(result, path.get("consequent"), ignoreResult);
+  this.jump(after);
+
+  this.mark(elseLoc);
+  explodeViaTempVar(result, path.get("alternate"), ignoreResult);
+
+  this.mark(after);
+
+  return result;
+};
+
+exports.UnaryExpression = function (expr, path, explodeViaTempVar, finish) {
+  return finish(t.unaryExpression(
+    expr.operator,
+    // Can't (and don't need to) break up the syntax of the argument.
+    // Think about delete a[b].
+    this.explodeExpression(path.get("argument")),
+    !!expr.prefix
+  ));
+};
+
+exports.BinaryExpression = function (expr, path, explodeViaTempVar, finish) {
+  return finish(t.binaryExpression(
+    expr.operator,
+    explodeViaTempVar(null, path.get("left")),
+    explodeViaTempVar(null, path.get("right"))
+  ));
+};
+
+exports.AssignmentExpression = function (expr, path, explodeViaTempVar, finish) {
+  return finish(t.assignmentExpression(
+    expr.operator,
+    this.explodeExpression(path.get("left")),
+    this.explodeExpression(path.get("right"))
+  ));
+};
+
+exports.UpdateExpression = function (expr, path, explodeViaTempVar, finish) {
+  return finish(t.updateExpression(
+    expr.operator,
+    this.explodeExpression(path.get("argument")),
+    expr.prefix
+  ));
+};
+
+exports.YieldExpression = function (expr, path) {
+  var after = loc();
+  var arg = expr.argument && this.explodeExpression(path.get("argument"));
+  var result;
+
+  if (arg && expr.delegate) {
+    result = this.makeTempVar();
+
+    this.emit(t.returnStatement(t.callExpression(
+      this.contextProperty("delegateYield"), [
+        arg,
+        t.literal(result.property.name),
+        after
+      ]
+    )));
+
+    this.mark(after);
+
+    return result;
+  }
+
+  this.emitAssign(this.contextProperty("next"), after);
+  this.emit(t.returnStatement(arg || null));
+  this.mark(after);
+
+  return this.contextProperty("sent");
+};

lib/6to5/transformation/transformers/es6-generators/emit/explode-statements.js

@@ -0,0 +1,334 @@
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * https://raw.github.com/facebook/regenerator/master/LICENSE file. An
+ * additional grant of patent rights can be found in the PATENTS file in
+ * the same directory.
+ */
+
+var assert = require("assert");
+var types  = require("ast-types");
+var leap   = require("../leap");
+var util   = require("../util");
+var t      = require("../../../../types");
+
+var runtimeKeysMethod = util.runtimeProperty("keys");
+var loc               = util.loc;
+
+exports.ExpressionStatement = function (path) {
+  this.explodeExpression(path.get("expression"), true);
+};
+
+exports.LabeledStatement = function (path, stmt) {
+  this.explodeStatement(path.get("body"), stmt.label);
+};
+
+exports.WhileStatement = function (path, stmt, labelId) {
+  var before = loc();
+  var after = loc();
+
+  this.mark(before);
+  this.jumpIfNot(this.explodeExpression(path.get("test")), after);
+  this.leapManager.withEntry(
+    new leap.LoopEntry(after, before, labelId),
+    function () { this.explodeStatement(path.get("body")); }
+  );
+  this.jump(before);
+  this.mark(after);
+};
+
+exports.DoWhileStatement = function (path, stmt, labelId) {
+  var first = loc();
+  var test = loc();
+  var after = loc();
+
+  this.mark(first);
+  this.leapManager.withEntry(
+    new leap.LoopEntry(after, test, labelId),
+    function () { this.explode(path.get("body")); }
+  );
+  this.mark(test);
+  this.jumpIf(this.explodeExpression(path.get("test")), first);
+  this.mark(after);
+};
+
+exports.ForStatement = function (path, stmt, labelId) {
+  var head = loc();
+  var update = loc();
+  var after = loc();
+
+  if (stmt.init) {
+    // We pass true here to indicate that if stmt.init is an expression
+    // then we do not care about its result.
+    this.explode(path.get("init"), true);
+  }
+
+  this.mark(head);
+
+  if (stmt.test) {
+    this.jumpIfNot(this.explodeExpression(path.get("test")), after);
+  } else {
+    // No test means continue unconditionally.
+  }
+
+  this.leapManager.withEntry(
+    new leap.LoopEntry(after, update, labelId),
+    function () { this.explodeStatement(path.get("body")); }
+  );
+
+  this.mark(update);
+
+  if (stmt.update) {
+    // We pass true here to indicate that if stmt.update is an
+    // expression then we do not care about its result.
+    this.explode(path.get("update"), true);
+  }
+
+  this.jump(head);
+
+  this.mark(after);
+};
+
+exports.ForInStatement = function (path, stmt, labelId) {
+  t.assertIdentifier(stmt.left);
+
+  var head = loc();
+  var after = loc();
+
+  var keyIterNextFn = this.makeTempVar();
+  this.emitAssign(
+    keyIterNextFn,
+    t.callExpression(
+      runtimeKeysMethod,
+      [this.explodeExpression(path.get("right"))]
+    )
+  );
+
+  this.mark(head);
+
+  var keyInfoTmpVar = this.makeTempVar();
+  this.jumpIf(
+    t.memberExpression(
+      t.assignmentExpression(
+        "=",
+        keyInfoTmpVar,
+        t.callExpression(keyIterNextFn, [])
+      ),
+      t.identifier("done"),
+      false
+    ),
+    after
+  );
+
+  this.emitAssign(
+    stmt.left,
+    t.memberExpression(
+      keyInfoTmpVar,
+      t.identifier("value"),
+      false
+    )
+  );
+
+  this.leapManager.withEntry(
+    new leap.LoopEntry(after, head, labelId),
+    function () { this.explodeStatement(path.get("body")); }
+  );
+
+  this.jump(head);
+
+  this.mark(after);
+};
+
+exports.BreakStatement = function (path, stmt) {
+  this.emitAbruptCompletion({
+    type: "break",
+    target: this.leapManager.getBreakLoc(stmt.label)
+  });
+};
+
+exports.ContinueStatement = function (path, stmt) {
+  this.emitAbruptCompletion({
+    type: "continue",
+    target: this.leapManager.getContinueLoc(stmt.label)
+  });
+};
+
+exports.SwitchStatement = function (path, stmt) {
+  // Always save the discriminant into a temporary variable in case the
+  // test expressions overwrite values like context.sent.
+  var disc = this.emitAssign(
+    this.makeTempVar(),
+    this.explodeExpression(path.get("discriminant"))
+  );
+
+  var after = loc();
+  var defaultLoc = loc();
+  var condition = defaultLoc;
+  var caseLocs = [];
+  var self = this;
+
+  // If there are no cases, .cases might be undefined.
+  var cases = stmt.cases || [];
+
+  for (var i = cases.length - 1; i >= 0; --i) {
+    var c = cases[i];
+    t.assertSwitchCase(c);
+
+    if (c.test) {
+      condition = t.conditionalExpression(
+        t.binaryExpression("===", disc, c.test),
+        caseLocs[i] = loc(),
+        condition
+      );
+    } else {
+      caseLocs[i] = defaultLoc;
+    }
+  }
+
+  this.jump(this.explodeExpression(
+    new types.NodePath(condition, path, "discriminant")
+  ));
+
+  this.leapManager.withEntry(
+    new leap.SwitchEntry(after),
+    function () {
+      path.get("cases").each(function (casePath) {
+        var i = casePath.name;
+
+        self.mark(caseLocs[i]);
+
+        casePath.get("consequent").each(
+          self.explodeStatement,
+          self
+        );
+      });
+    }
+  );
+
+  this.mark(after);
+  if (defaultLoc.value === -1) {
+    this.mark(defaultLoc);
+    assert.strictEqual(after.value, defaultLoc.value);
+  }
+};
+
+exports.IfStatement = function (path, stmt) {
+  var elseLoc = stmt.alternate && loc();
+  var after = loc();
+
+  this.jumpIfNot(
+    this.explodeExpression(path.get("test")),
+    elseLoc || after
+  );
+
+  this.explodeStatement(path.get("consequent"));
+
+  if (elseLoc) {
+    this.jump(after);
+    this.mark(elseLoc);
+    this.explodeStatement(path.get("alternate"));
+  }
+
+  this.mark(after);
+};
+
+exports.ReturnStatement = function (path) {
+  this.emitAbruptCompletion({
+    type: "return",
+    value: this.explodeExpression(path.get("argument"))
+  });
+};
+
+exports.TryStatement = function (path, stmt) {
+  var after = loc();
+  var self = this;
+
+  var handler = stmt.handler;
+  if (!handler && stmt.handlers) {
+    handler = stmt.handlers[0] || null;
+  }
+
+  var catchLoc = handler && loc();
+  var catchEntry = catchLoc && new leap.CatchEntry(
+    catchLoc,
+    handler.param
+  );
+
+  var finallyLoc = stmt.finalizer && loc();
+  var finallyEntry = finallyLoc && new leap.FinallyEntry(finallyLoc);
+
+  var tryEntry = new leap.TryEntry(
+    this.getUnmarkedCurrentLoc(),
+    catchEntry,
+    finallyEntry
+  );
+
+  this.tryEntries.push(tryEntry);
+  this.updateContextPrevLoc(tryEntry.firstLoc);
+
+  this.leapManager.withEntry(tryEntry, function () {
+    this.explodeStatement(path.get("block"));
+
+    if (catchLoc) {
+      if (finallyLoc) {
+        // If we have both a catch block and a finally block, then
+        // because we emit the catch block first, we need to jump over
+        // it to the finally block.
+        this.jump(finallyLoc);
+
+      } else {
+        // If there is no finally block, then we need to jump over the
+        // catch block to the fall-through location.
+        this.jump(after);
+      }
+
+      this.updateContextPrevLoc(self.mark(catchLoc));
+
+      var bodyPath = path.get("handler", "body");
+      var safeParam = this.makeTempVar();
+      this.clearPendingException(tryEntry.firstLoc, safeParam);
+
+      var catchScope = bodyPath.scope;
+      var catchParamName = handler.param.name;
+      t.assertCatchClause(catchScope.node);
+      assert.strictEqual(catchScope.lookup(catchParamName), catchScope);
+
+      types.visit(bodyPath, {
+        visitIdentifier: function (path) {
+          if (path.value.name === catchParamName &&
+              path.scope.lookup(catchParamName) === catchScope) {
+            return safeParam;
+          }
+          this.traverse(path);
+        }
+      });
+
+      this.leapManager.withEntry(catchEntry, function () {
+        this.explodeStatement(bodyPath);
+      });
+    }
+
+    if (finallyLoc) {
+      this.updateContextPrevLoc(this.mark(finallyLoc));
+
+      this.leapManager.withEntry(finallyEntry, function () {
+        this.explodeStatement(path.get("finalizer"));
+      });
+
+      this.emit(t.callExpression(
+        this.contextProperty("finish"),
+        [finallyEntry.firstLoc]
+      ));
+    }
+  });
+
+  this.mark(after);
+};
+
+exports.ThrowStatement = function (path) {
+  this.emit(t.throwStatement(
+    this.explodeExpression(path.get("argument"))
+  ));
+};

lib/6to5/transformation/transformers/es6-generators/emit/index.js

@@ -10,16 +10,18 @@
 
 exports.Emitter = Emitter;
 
-var runtimeProperty = require("./util").runtimeProperty;
-var assert          = require("assert");
-var types           = require("ast-types");
-var leap            = require("./leap");
-var meta            = require("./meta");
-var t               = require("../../../types");
-var _               = require("lodash");
+var explodeExpressions = require("./explode-expressions");
+var explodeStatements  = require("./explode-statements");
+var assert             = require("assert");
+var types              = require("ast-types");
+var leap               = require("../leap");
+var meta               = require("../meta");
+var util               = require("../util");
+var t                  = require("../../../../types");
+var _                  = require("lodash");
 
-var runtimeKeysMethod = runtimeProperty("keys");
-var n                 = types.namedTypes;
+var loc = util.loc;
+var n   = types.namedTypes;
 
 function Emitter(contextId) {
   assert.ok(this instanceof Emitter);
@@ -52,18 +54,9 @@ function Emitter(contextId) {
   this.leapManager = new leap.LeapManager(this);
 }
 
-// Offsets into this.listing that could be used as targets for branches or
-// jumps are represented as numeric Literal nodes. This representation has
-// the amazingly convenient benefit of allowing the exact value of the
-// location to be determined at any time, even after generating code that
-// refers to the location.
-function loc() {
-  return t.literal(-1);
-}
-
 // Sets the exact value of the given location to the offset of the next
 // Statement emitted.
-Emitter.prototype.mark = function(loc) {
+Emitter.prototype.mark = function (loc) {
   t.assertLiteral(loc);
   var index = this.listing.length;
   if (loc.value === -1) {
@@ -77,7 +70,7 @@ Emitter.prototype.mark = function(loc) {
   return loc;
 };
 
-Emitter.prototype.emit = function(node) {
+Emitter.prototype.emit = function (node) {
   if (t.isExpression(node)) node = t.expressionStatement(node);
   t.assertStatement(node);
   this.listing.push(node);
@@ -85,20 +78,20 @@ Emitter.prototype.emit = function(node) {
 
 // Shorthand for emitting assignment statements. This will come in handy
 // for assignments to temporary variables.
-Emitter.prototype.emitAssign = function(lhs, rhs) {
+Emitter.prototype.emitAssign = function (lhs, rhs) {
   this.emit(this.assign(lhs, rhs));
   return lhs;
 };
 
 // Shorthand for an assignment statement.
-Emitter.prototype.assign = function(lhs, rhs) {
+Emitter.prototype.assign = function (lhs, rhs) {
   return t.expressionStatement(
     t.assignmentExpression("=", lhs, rhs));
 };
 
 // Convenience function for generating expressions like context.next,
 // context.sent, and context.rval.
-Emitter.prototype.contextProperty = function(name, computed) {
+Emitter.prototype.contextProperty = function (name, computed) {
   return t.memberExpression(
     this.contextId,
     computed ? t.literal(name) : t.identifier(name),
@@ -116,7 +109,7 @@ var volatileContextPropertyNames = {
 // A "volatile" context property is a MemberExpression like context.sent
 // that should probably be stored in a temporary variable when there's a
 // possibility the property will get overwritten.
-Emitter.prototype.isVolatileContextProperty = function(expr) {
+Emitter.prototype.isVolatileContextProperty = function (expr) {
   if (t.isMemberExpression(expr)) {
     if (expr.computed) {
       // If it's a computed property such as context[couldBeAnything],
@@ -136,7 +129,7 @@ Emitter.prototype.isVolatileContextProperty = function(expr) {
 };
 
 // Shorthand for setting context.rval and jumping to `context.stop()`.
-Emitter.prototype.stop = function(rval) {
+Emitter.prototype.stop = function (rval) {
   if (rval) {
     this.setReturnValue(rval);
   }
@@ -144,7 +137,7 @@ Emitter.prototype.stop = function(rval) {
   this.jump(this.finalLoc);
 };
 
-Emitter.prototype.setReturnValue = function(valuePath) {
+Emitter.prototype.setReturnValue = function (valuePath) {
   t.assertExpression(valuePath.value);
 
   this.emitAssign(
@@ -153,7 +146,7 @@ Emitter.prototype.setReturnValue = function(valuePath) {
   );
 };
 
-Emitter.prototype.clearPendingException = function(tryLoc, assignee) {
+Emitter.prototype.clearPendingException = function (tryLoc, assignee) {
   t.assertLiteral(tryLoc);
 
   var catchCall = t.callExpression(
@@ -170,13 +163,13 @@ Emitter.prototype.clearPendingException = function(tryLoc, assignee) {
 
 // Emits code for an unconditional jump to the given location, even if the
 // exact value of the location is not yet known.
-Emitter.prototype.jump = function(toLoc) {
+Emitter.prototype.jump = function (toLoc) {
   this.emitAssign(this.contextProperty("next"), toLoc);
   this.emit(t.breakStatement());
 };
 
 // Conditional jump.
-Emitter.prototype.jumpIf = function(test, toLoc) {
+Emitter.prototype.jumpIf = function (test, toLoc) {
   t.assertExpression(test);
   t.assertLiteral(toLoc);
 
@@ -190,7 +183,7 @@ Emitter.prototype.jumpIf = function(test, toLoc) {
 };
 
 // Conditional jump, with the condition negated.
-Emitter.prototype.jumpIfNot = function(test, toLoc) {
+Emitter.prototype.jumpIfNot = function (test, toLoc) {
   t.assertExpression(test);
   t.assertLiteral(toLoc);
 
@@ -217,11 +210,11 @@ Emitter.prototype.jumpIfNot = function(test, toLoc) {
 // other local variables, and since we just increment `nextTempId`
 // monotonically, uniqueness is assured.
 var nextTempId = 0;
-Emitter.prototype.makeTempVar = function() {
+Emitter.prototype.makeTempVar = function () {
   return this.contextProperty("t" + nextTempId++);
 };
 
-Emitter.prototype.getContextFunction = function(id) {
+Emitter.prototype.getContextFunction = function (id) {
   var node = t.functionExpression(
     id || null,
     [this.contextId],
@@ -244,7 +237,7 @@ Emitter.prototype.getContextFunction = function(id) {
 //
 // Each marked location in this.listing will correspond to one generated
 // case statement.
-Emitter.prototype.getDispatchLoop = function() {
+Emitter.prototype.getDispatchLoop = function () {
   var self = this;
   var cases = [];
   var current;
@@ -253,7 +246,7 @@ Emitter.prototype.getDispatchLoop = function() {
   // case, we can skip the rest of the statements until the next case.
   var alreadyEnded = false;
 
-  self.listing.forEach(function(stmt, i) {
+  self.listing.forEach(function (stmt, i) {
     if (self.marked.hasOwnProperty(i)) {
       cases.push(t.switchCase(t.literal(i), current = []));
       alreadyEnded = false;
@@ -306,7 +299,7 @@ function isSwitchCaseEnder(stmt) {
          t.isThrowStatement(stmt);
 }
 
-Emitter.prototype.getTryEntryList = function() {
+Emitter.prototype.getTryEntryList = function () {
   if (this.tryEntries.length === 0) {
     // To avoid adding a needless [] to the majority of runtime.wrap
     // argument lists, force the caller to handle this case specially.
@@ -316,7 +309,7 @@ Emitter.prototype.getTryEntryList = function() {
   var lastLocValue = 0;
 
   return t.arrayExpression(
-    this.tryEntries.map(function(tryEntry) {
+    this.tryEntries.map(function (tryEntry) {
       var thisLocValue = tryEntry.firstLoc.value;
       assert.ok(thisLocValue >= lastLocValue, "try entries out of order");
       lastLocValue = thisLocValue;
@@ -346,7 +339,7 @@ Emitter.prototype.getTryEntryList = function() {
 
 // No destructive modification of AST nodes.
 
-Emitter.prototype.explode = function(path, ignoreResult) {
+Emitter.prototype.explode = function (path, ignoreResult) {
   assert.ok(path instanceof types.NodePath);
 
   var node = path.value;
@@ -389,12 +382,11 @@ function getDeclError(node) {
     JSON.stringify(node));
 }
 
-Emitter.prototype.explodeStatement = function(path, labelId) {
+Emitter.prototype.explodeStatement = function (path, labelId) {
   assert.ok(path instanceof types.NodePath);
 
   var stmt = path.value;
   var self = this;
-  var after, head;
 
   t.assertStatement(stmt);
 
@@ -423,338 +415,15 @@ Emitter.prototype.explodeStatement = function(path, labelId) {
     return;
   }
 
-  switch (stmt.type) {
-  case "ExpressionStatement":
-    self.explodeExpression(path.get("expression"), true);
-    break;
-
-  case "LabeledStatement":
-    self.explodeStatement(path.get("body"), stmt.label);
-    break;
-
-  case "WhileStatement":
-    var before = loc();
-    after = loc();
-
-    self.mark(before);
-    self.jumpIfNot(self.explodeExpression(path.get("test")), after);
-    self.leapManager.withEntry(
-      new leap.LoopEntry(after, before, labelId),
-      function() { self.explodeStatement(path.get("body")); }
-    );
-    self.jump(before);
-    self.mark(after);
-
-    break;
-
-  case "DoWhileStatement":
-    var first = loc();
-    var test = loc();
-    after = loc();
-
-    self.mark(first);
-    self.leapManager.withEntry(
-      new leap.LoopEntry(after, test, labelId),
-      function() { self.explode(path.get("body")); }
-    );
-    self.mark(test);
-    self.jumpIf(self.explodeExpression(path.get("test")), first);
-    self.mark(after);
-
-    break;
-
-  case "ForStatement":
-    head = loc();
-    var update = loc();
-    after = loc();
-
-    if (stmt.init) {
-      // We pass true here to indicate that if stmt.init is an expression
-      // then we do not care about its result.
-      self.explode(path.get("init"), true);
-    }
-
-    self.mark(head);
-
-    if (stmt.test) {
-      self.jumpIfNot(self.explodeExpression(path.get("test")), after);
-    } else {
-      // No test means continue unconditionally.
-    }
-
-    self.leapManager.withEntry(
-      new leap.LoopEntry(after, update, labelId),
-      function() { self.explodeStatement(path.get("body")); }
-    );
-
-    self.mark(update);
-
-    if (stmt.update) {
-      // We pass true here to indicate that if stmt.update is an
-      // expression then we do not care about its result.
-      self.explode(path.get("update"), true);
-    }
-
-    self.jump(head);
-
-    self.mark(after);
-
-    break;
-
-  case "ForInStatement":
-    t.assertIdentifier(stmt.left);
-
-    head = loc();
-    after = loc();
-
-    var keyIterNextFn = self.makeTempVar();
-    self.emitAssign(
-      keyIterNextFn,
-      t.callExpression(
-        runtimeKeysMethod,
-        [self.explodeExpression(path.get("right"))]
-      )
-    );
-
-    self.mark(head);
-
-    var keyInfoTmpVar = self.makeTempVar();
-    self.jumpIf(
-      t.memberExpression(
-        t.assignmentExpression(
-          "=",
-          keyInfoTmpVar,
-          t.callExpression(keyIterNextFn, [])
-        ),
-        t.identifier("done"),
-        false
-      ),
-      after
-    );
-
-    self.emitAssign(
-      stmt.left,
-      t.memberExpression(
-        keyInfoTmpVar,
-        t.identifier("value"),
-        false
-      )
-    );
-
-    self.leapManager.withEntry(
-      new leap.LoopEntry(after, head, labelId),
-      function() { self.explodeStatement(path.get("body")); }
-    );
-
-    self.jump(head);
-
-    self.mark(after);
-
-    break;
-
-  case "BreakStatement":
-    self.emitAbruptCompletion({
-      type: "break",
-      target: self.leapManager.getBreakLoc(stmt.label)
-    });
-
-    break;
-
-  case "ContinueStatement":
-    self.emitAbruptCompletion({
-      type: "continue",
-      target: self.leapManager.getContinueLoc(stmt.label)
-    });
-
-    break;
-
-  case "SwitchStatement":
-    // Always save the discriminant into a temporary variable in case the
-    // test expressions overwrite values like context.sent.
-    var disc = self.emitAssign(
-      self.makeTempVar(),
-      self.explodeExpression(path.get("discriminant"))
-    );
-
-    after = loc();
-    var defaultLoc = loc();
-    var condition = defaultLoc;
-    var caseLocs = [];
-
-    // If there are no cases, .cases might be undefined.
-    var cases = stmt.cases || [];
-
-    for (var i = cases.length - 1; i >= 0; --i) {
-      var c = cases[i];
-      t.assertSwitchCase(c);
-
-      if (c.test) {
-        condition = t.conditionalExpression(
-          t.binaryExpression("===", disc, c.test),
-          caseLocs[i] = loc(),
-          condition
-        );
-      } else {
-        caseLocs[i] = defaultLoc;
-      }
-    }
-
-    self.jump(self.explodeExpression(
-      new types.NodePath(condition, path, "discriminant")
-    ));
-
-    self.leapManager.withEntry(
-      new leap.SwitchEntry(after),
-      function() {
-        path.get("cases").each(function(casePath) {
-          var i = casePath.name;
-
-          self.mark(caseLocs[i]);
-
-          casePath.get("consequent").each(
-            self.explodeStatement,
-            self
-          );
-        });
-      }
-    );
-
-    self.mark(after);
-    if (defaultLoc.value === -1) {
-      self.mark(defaultLoc);
-      assert.strictEqual(after.value, defaultLoc.value);
-    }
-
-    break;
-
-  case "IfStatement":
-    var elseLoc = stmt.alternate && loc();
-    after = loc();
-
-    self.jumpIfNot(
-      self.explodeExpression(path.get("test")),
-      elseLoc || after
-    );
-
-    self.explodeStatement(path.get("consequent"));
-
-    if (elseLoc) {
-      self.jump(after);
-      self.mark(elseLoc);
-      self.explodeStatement(path.get("alternate"));
-    }
-
-    self.mark(after);
-
-    break;
-
-  case "ReturnStatement":
-    self.emitAbruptCompletion({
-      type: "return",
-      value: self.explodeExpression(path.get("argument"))
-    });
-
-    break;
-
-  case "TryStatement":
-    after = loc();
-
-    var handler = stmt.handler;
-    if (!handler && stmt.handlers) {
-      handler = stmt.handlers[0] || null;
-    }
-
-    var catchLoc = handler && loc();
-    var catchEntry = catchLoc && new leap.CatchEntry(
-      catchLoc,
-      handler.param
-    );
-
-    var finallyLoc = stmt.finalizer && loc();
-    var finallyEntry = finallyLoc && new leap.FinallyEntry(finallyLoc);
-
-    var tryEntry = new leap.TryEntry(
-      self.getUnmarkedCurrentLoc(),
-      catchEntry,
-      finallyEntry
-    );
-
-    self.tryEntries.push(tryEntry);
-    self.updateContextPrevLoc(tryEntry.firstLoc);
-
-    self.leapManager.withEntry(tryEntry, function() {
-      self.explodeStatement(path.get("block"));
-
-      if (catchLoc) {
-        if (finallyLoc) {
-          // If we have both a catch block and a finally block, then
-          // because we emit the catch block first, we need to jump over
-          // it to the finally block.
-          self.jump(finallyLoc);
-
-        } else {
-          // If there is no finally block, then we need to jump over the
-          // catch block to the fall-through location.
-          self.jump(after);
-        }
-
-        self.updateContextPrevLoc(self.mark(catchLoc));
-
-        var bodyPath = path.get("handler", "body");
-        var safeParam = self.makeTempVar();
-        self.clearPendingException(tryEntry.firstLoc, safeParam);
-
-        var catchScope = bodyPath.scope;
-        var catchParamName = handler.param.name;
-        t.assertCatchClause(catchScope.node);
-        assert.strictEqual(catchScope.lookup(catchParamName), catchScope);
-
-        types.visit(bodyPath, {
-          visitIdentifier: function(path) {
-            if (path.value.name === catchParamName &&
-                path.scope.lookup(catchParamName) === catchScope) {
-              return safeParam;
-            }
-            this.traverse(path);
-          }
-        });
-
-        self.leapManager.withEntry(catchEntry, function() {
-          self.explodeStatement(bodyPath);
-        });
-      }
-
-      if (finallyLoc) {
-        self.updateContextPrevLoc(self.mark(finallyLoc));
-
-        self.leapManager.withEntry(finallyEntry, function() {
-          self.explodeStatement(path.get("finalizer"));
-        });
-
-        self.emit(t.callExpression(
-          self.contextProperty("finish"),
-          [finallyEntry.firstLoc]
-        ));
-      }
-    });
-
-    self.mark(after);
-
-    break;
-
-  case "ThrowStatement":
-    self.emit(t.throwStatement(
-      self.explodeExpression(path.get("argument"))
-    ));
-
-    break;
-
-  default:
+  var fn = explodeStatements[stmt.type];
+  if (fn) {
+    fn.call(this, path, stmt, labelId);
+  } else {
     throw new Error("unknown Statement of type " + JSON.stringify(stmt.type));
   }
 };
 
-Emitter.prototype.emitAbruptCompletion = function(record) {
+Emitter.prototype.emitAbruptCompletion = function (record) {
   if (!isValidCompletion(record)) {
     assert.ok(
       false,
@@ -816,7 +485,7 @@ function isValidCompletion(record) {
 // statements). There's no logical harm in marking such locations as jump
 // targets, but minimizing the number of switch cases keeps the generated
 // code shorter.
-Emitter.prototype.getUnmarkedCurrentLoc = function() {
+Emitter.prototype.getUnmarkedCurrentLoc = function () {
   return t.literal(this.listing.length);
 };
 
@@ -830,7 +499,7 @@ Emitter.prototype.getUnmarkedCurrentLoc = function() {
 // would know the location of the current instruction with complete
 // precision at all times, but we don't have that luxury here, as it would
 // be costly and verbose to set context.prev before every statement.
-Emitter.prototype.updateContextPrevLoc = function(loc) {
+Emitter.prototype.updateContextPrevLoc = function (loc) {
   if (loc) {
     t.assertLiteral(loc);
 
@@ -853,7 +522,7 @@ Emitter.prototype.updateContextPrevLoc = function(loc) {
   this.emitAssign(this.contextProperty("prev"), loc);
 };
 
-Emitter.prototype.explodeExpression = function(path, ignoreResult) {
+Emitter.prototype.explodeExpression = function (path, ignoreResult) {
   assert.ok(path instanceof types.NodePath);
 
   var expr = path.value;
@@ -864,7 +533,6 @@ Emitter.prototype.explodeExpression = function(path, ignoreResult) {
   }
 
   var self = this;
-  var result, after; // Used optionally by several cases below.
 
   function finish(expr) {
     t.assertExpression(expr);
@@ -934,180 +602,10 @@ Emitter.prototype.explodeExpression = function(path, ignoreResult) {
   // emitting the expression with all its side effects, and we should not
   // return a result.
 
-  switch (expr.type) {
-  case "ParenthesizedExpression":
-    return finish(self.explodeExpression(path.get("expression")));
-
-  case "MemberExpression":
-    return finish(t.memberExpression(
-      self.explodeExpression(path.get("object")),
-      expr.computed ? explodeViaTempVar(null, path.get("property")) : expr.property,
-      expr.computed
-    ));
-
-  case "CallExpression":
-    var oldCalleePath = path.get("callee");
-    var newCallee = self.explodeExpression(oldCalleePath);
-
-    // If the callee was not previously a MemberExpression, then the
-    // CallExpression was "unqualified," meaning its `this` object should
-    // be the global object. If the exploded expression has become a
-    // MemberExpression, then we need to force it to be unqualified by
-    // using the (0, object.property)(...) trick; otherwise, it will
-    // receive the object of the MemberExpression as its `this` object.
-    if (!t.isMemberExpression(oldCalleePath.node) && t.isMemberExpression(newCallee)) {
-      newCallee = t.sequenceExpression([
-        t.literal(0),
-        newCallee
-      ]);
-    }
-
-    return finish(t.callExpression(
-      newCallee,
-      path.get("arguments").map(function(argPath) {
-        return explodeViaTempVar(null, argPath);
-      })
-    ));
-
-  case "NewExpression":
-    return finish(t.newExpression(
-      explodeViaTempVar(null, path.get("callee")),
-      path.get("arguments").map(function(argPath) {
-        return explodeViaTempVar(null, argPath);
-      })
-    ));
-
-  case "ObjectExpression":
-    return finish(t.objectExpression(
-      path.get("properties").map(function(propPath) {
-        return t.property(
-          propPath.value.kind,
-          propPath.value.key,
-          explodeViaTempVar(null, propPath.get("value"))
-        );
-      })
-    ));
-
-  case "ArrayExpression":
-    return finish(t.arrayExpression(
-      path.get("elements").map(function(elemPath) {
-        return explodeViaTempVar(null, elemPath);
-      })
-    ));
-
-  case "SequenceExpression":
-    var lastIndex = expr.expressions.length - 1;
-
-    path.get("expressions").each(function(exprPath) {
-      if (exprPath.name === lastIndex) {
-        result = self.explodeExpression(exprPath, ignoreResult);
-      } else {
-        self.explodeExpression(exprPath, true);
-      }
-    });
-
-    return result;
-
-  case "LogicalExpression":
-    after = loc();
-
-    if (!ignoreResult) {
-      result = self.makeTempVar();
-    }
-
-    var left = explodeViaTempVar(result, path.get("left"));
-
-    if (expr.operator === "&&") {
-      self.jumpIfNot(left, after);
-    } else {
-      assert.strictEqual(expr.operator, "||");
-      self.jumpIf(left, after);
-    }
-
-    explodeViaTempVar(result, path.get("right"), ignoreResult);
-
-    self.mark(after);
-
-    return result;
-
-  case "ConditionalExpression":
-    var elseLoc = loc();
-    after = loc();
-    var test = self.explodeExpression(path.get("test"));
-
-    self.jumpIfNot(test, elseLoc);
-
-    if (!ignoreResult) {
-      result = self.makeTempVar();
-    }
-
-    explodeViaTempVar(result, path.get("consequent"), ignoreResult);
-    self.jump(after);
-
-    self.mark(elseLoc);
-    explodeViaTempVar(result, path.get("alternate"), ignoreResult);
-
-    self.mark(after);
-
-    return result;
-
-  case "UnaryExpression":
-    return finish(t.unaryExpression(
-      expr.operator,
-      // Can't (and don't need to) break up the syntax of the argument.
-      // Think about delete a[b].
-      self.explodeExpression(path.get("argument")),
-      !!expr.prefix
-    ));
-
-  case "BinaryExpression":
-    return finish(t.binaryExpression(
-      expr.operator,
-      explodeViaTempVar(null, path.get("left")),
-      explodeViaTempVar(null, path.get("right"))
-    ));
-
-  case "AssignmentExpression":
-    return finish(t.assignmentExpression(
-      expr.operator,
-      self.explodeExpression(path.get("left")),
-      self.explodeExpression(path.get("right"))
-    ));
-
-  case "UpdateExpression":
-    return finish(t.updateExpression(
-      expr.operator,
-      self.explodeExpression(path.get("argument")),
-      expr.prefix
-    ));
-
-  case "YieldExpression":
-    after = loc();
-    var arg = expr.argument && self.explodeExpression(path.get("argument"));
-
-    if (arg && expr.delegate) {
-      result = self.makeTempVar();
-
-      self.emit(t.returnStatement(t.callExpression(
-        self.contextProperty("delegateYield"), [
-          arg,
-          t.literal(result.property.name),
-          after
-        ]
-      )));
-
-      self.mark(after);
-
-      return result;
-    }
-
-    self.emitAssign(self.contextProperty("next"), after);
-    self.emit(t.returnStatement(arg || null));
-    self.mark(after);
-
-    return self.contextProperty("sent");
-
-  default:
+  var fn = explodeExpressions[expr.type];
+  if (fn) {
+    return fn.call(this, expr, path, explodeViaTempVar, finish, ignoreResult);
+  } else {
     throw new Error("unknown Expression of type " + JSON.stringify(expr.type));
   }
 };

lib/6to5/transformation/transformers/es6-generators/hoist.js

@@ -17,7 +17,7 @@ var _      = require("lodash");
 // and replaces any Declaration nodes in its body with assignments, then
 // returns a VariableDeclaration containing just the names of the removed
 // declarations.
-exports.hoist = function(funPath) {
+exports.hoist = function (funPath) {
   assert.ok(funPath instanceof types.NodePath);
   t.assertFunction(funPath.value);
 
@@ -27,7 +27,7 @@ exports.hoist = function(funPath) {
     t.assertVariableDeclaration(vdec);
     var exprs = [];
 
-    vdec.declarations.forEach(function(dec) {
+    vdec.declarations.forEach(function (dec) {
       vars[dec.id.name] = dec.id;
 
       if (dec.init) {
@@ -49,7 +49,7 @@ exports.hoist = function(funPath) {
   }
 
   types.visit(funPath.get("body"), {
-    visitVariableDeclaration: function(path) {
+    visitVariableDeclaration: function (path) {
       var expr = varDeclToExpr(path.value, false);
       if (expr === null) {
         path.replace();
@@ -64,7 +64,7 @@ exports.hoist = function(funPath) {
       return false;
     },
 
-    visitForStatement: function(path) {
+    visitForStatement: function (path) {
       var init = path.value.init;
       if (t.isVariableDeclaration(init)) {
         path.get("init").replace(varDeclToExpr(init, false));
@@ -72,7 +72,7 @@ exports.hoist = function(funPath) {
       this.traverse(path);
     },
 
-    visitForInStatement: function(path) {
+    visitForInStatement: function (path) {
       var left = path.value.left;
       if (t.isVariableDeclaration(left)) {
         path.get("left").replace(varDeclToExpr(left, true));
@@ -80,7 +80,7 @@ exports.hoist = function(funPath) {
       this.traverse(path);
     },
 
-    visitFunctionDeclaration: function(path) {
+    visitFunctionDeclaration: function (path) {
       var node = path.value;
       vars[node.id.name] = node.id;
 
@@ -118,14 +118,14 @@ exports.hoist = function(funPath) {
       return false;
     },
 
-    visitFunctionExpression: function() {
+    visitFunctionExpression: function () {
       // Don't descend into nested function expressions.
       return false;
     }
   });
 
   var paramNames = {};
-  funPath.get("params").each(function(paramPath) {
+  funPath.get("params").each(function (paramPath) {
     var param = paramPath.value;
     if (t.isIdentifier(param)) {
       paramNames[param.name] = param;
@@ -137,7 +137,7 @@ exports.hoist = function(funPath) {
 
   var declarations = [];
 
-  Object.keys(vars).forEach(function(name) {
+  Object.keys(vars).forEach(function (name) {
     if (!_.has(paramNames, name)) {
       declarations.push(t.variableDeclarator(vars[name], null));
     }

lib/6to5/transformation/transformers/es6-generators/leap.js

@@ -124,7 +124,7 @@ function LeapManager(emitter) {
   this.entryStack = [new FunctionEntry(emitter.finalLoc)];
 }
 
-LeapManager.prototype.withEntry = function(entry, callback) {
+LeapManager.prototype.withEntry = function (entry, callback) {
   assert.ok(entry instanceof Entry);
   this.entryStack.push(entry);
   try {
@@ -135,7 +135,7 @@ LeapManager.prototype.withEntry = function(entry, callback) {
   }
 };
 
-LeapManager.prototype._findLeapLocation = function(property, label) {
+LeapManager.prototype._findLeapLocation = function (property, label) {
   for (var i = this.entryStack.length - 1; i >= 0; --i) {
     var entry = this.entryStack[i];
     var loc = entry[property];
@@ -154,10 +154,10 @@ LeapManager.prototype._findLeapLocation = function(property, label) {
   return null;
 };
 
-LeapManager.prototype.getBreakLoc = function(label) {
+LeapManager.prototype.getBreakLoc = function (label) {
   return this._findLeapLocation("breakLoc", label);
 };
 
-LeapManager.prototype.getContinueLoc = function(label) {
+LeapManager.prototype.getContinueLoc = function (label) {
   return this._findLeapLocation("continueLoc", label);
 };

lib/6to5/transformation/transformers/es6-generators/meta.js

@@ -35,7 +35,7 @@ function makePredicate(propertyName, knownTypes) {
       return result;
     }
 
-    types.eachField(node, function(name, child) {
+    types.eachField(node, function (name, child) {
       check(child);
     });
 

lib/6to5/transformation/transformers/es6-generators/runtime.js

@@ -38,19 +38,19 @@ var GFName = "GeneratorFunction";
 if (GF.name !== GFName) GF.name = GFName;
 if (GF.name !== GFName) throw new Error(GFName + " renamed?");
 
-runtime.isGeneratorFunction = function(genFun) {
+runtime.isGeneratorFunction = function (genFun) {
   var ctor = genFun && genFun.constructor;
   return ctor ? GF.name === ctor.name : false;
 };
 
-runtime.mark = function(genFun) {
+runtime.mark = function (genFun) {
   genFun.__proto__ = GFp;
   genFun.prototype = Object.create(Gp);
   return genFun;
 };
 
-runtime.async = function(innerFn, outerFn, self, tryList) {
-  return new Promise(function(resolve, reject) {
+runtime.async = function (innerFn, outerFn, self, tryList) {
+  return new Promise(function (resolve, reject) {
     var generator = wrap(innerFn, outerFn, self, tryList);
     var callNext = step.bind(generator.next);
     var callThrow = step.bind(generator["throw"]);
@@ -202,11 +202,11 @@ function Generator(innerFn, outerFn, self, tryList) {
   return generator;
 }
 
-Gp[iteratorSymbol] = function() {
+Gp[iteratorSymbol] = function () {
   return this;
 };
 
-Gp.toString = function() {
+Gp.toString = function () {
   return "[object Generator]";
 };
 
@@ -240,7 +240,7 @@ function Context(tryList) {
   this.reset();
 }
 
-runtime.keys = function(object) {
+runtime.keys = function (object) {
   var keys = [];
   for (var key in object) {
     keys.push(key);
@@ -293,7 +293,7 @@ runtime.values = values;
 Context.prototype = {
   constructor: Context,
 
-  reset: function() {
+  reset: function () {
     this.prev = 0;
     this.next = 0;
     this.sent = undefined;
@@ -311,7 +311,7 @@ Context.prototype = {
     }
   },
 
-  stop: function() {
+  stop: function () {
     this.done = true;
 
     var rootEntry = this.tryEntries[0];
@@ -323,7 +323,7 @@ Context.prototype = {
     return this.rval;
   },
 
-  dispatchException: function(exception) {
+  dispatchException: function (exception) {
     if (this.done) {
       throw exception;
     }
@@ -375,7 +375,7 @@ Context.prototype = {
     }
   },
 
-  _findFinallyEntry: function(finallyLoc) {
+  _findFinallyEntry: function (finallyLoc) {
     for (var i = this.tryEntries.length - 1; i >= 0; --i) {
       var entry = this.tryEntries[i];
       if (entry.tryLoc <= this.prev &&
@@ -387,7 +387,7 @@ Context.prototype = {
     }
   },
 
-  abrupt: function(type, arg) {
+  abrupt: function (type, arg) {
     var entry = this._findFinallyEntry();
     var record = entry ? entry.completion : {};
 
@@ -403,7 +403,7 @@ Context.prototype = {
     return ContinueSentinel;
   },
 
-  complete: function(record) {
+  complete: function (record) {
     if (record.type === "throw") {
       throw record.arg;
     }
@@ -418,12 +418,12 @@ Context.prototype = {
     return ContinueSentinel;
   },
 
-  finish: function(finallyLoc) {
+  finish: function (finallyLoc) {
     var entry = this._findFinallyEntry(finallyLoc);
     return this.complete(entry.completion);
   },
 
-  "catch": function(tryLoc) {
+  "catch": function (tryLoc) {
     for (var i = this.tryEntries.length - 1; i >= 0; --i) {
       var entry = this.tryEntries[i];
       if (entry.tryLoc === tryLoc) {
@@ -442,7 +442,7 @@ Context.prototype = {
     throw new Error("illegal catch attempt");
   },
 
-  delegateYield: function(iterable, resultName, nextLoc) {
+  delegateYield: function (iterable, resultName, nextLoc) {
     this.delegate = {
       iterator: values(iterable),
       resultName: resultName,

lib/6to5/transformation/transformers/es6-generators/util.js

@@ -16,3 +16,13 @@ exports.runtimeProperty = function (name) {
     t.identifier(name)
   );
 };
+
+// Offsets into this.listing that could be used as targets for branches or
+// jumps are represented as numeric Literal nodes. This representation has
+// the amazingly convenient benefit of allowing the exact value of the
+// location to be determined at any time, even after generating code that
+// refers to the location.
+
+exports.loc = function () {
+  return t.literal(-1);
+};

lib/6to5/transformation/transformers/es6-generators/visit.js

@@ -0,0 +1,221 @@
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * https://raw.githut.com/facebook/regenerator/master/LICENSE file. An
+ * additional grant of patent rights can be found in the PATENTS file in
+ * the same directory.
+ */
+
+var runtimeProperty = require("./util").runtimeProperty;
+var Emitter         = require("./emit").Emitter;
+var hoist           = require("./hoist").hoist;
+var types           = require("ast-types");
+var t               = require("../../../types");
+
+var runtimeAsyncMethod = runtimeProperty("async");
+var runtimeWrapMethod  = runtimeProperty("wrap");
+var runtimeMarkMethod  = runtimeProperty("mark");
+
+exports.transform = function transform(node, file) {
+  return types.visit(node, {
+    visitFunction: function (path) {
+      return visitor.call(this, path, file);
+    }
+  });
+};
+
+var visitor = function (path, file) {
+  // Calling this.traverse(path) first makes for a post-order traversal.
+  this.traverse(path);
+
+  var node = path.value;
+  var scope; // we need to actually get the current scope
+
+  if (!node.generator && !node.async) {
+    return;
+  }
+
+  node.generator = false;
+
+  if (node.expression) {
+    // Transform expression lambdas into normal functions.
+    node.expression = false;
+    node.body = t.blockStatement([
+      t.returnStatement(node.body)
+    ]);
+  }
+
+  if (node.async) {
+    awaitVisitor.visit(path.get("body"));
+  }
+
+  var outerFnId = node.id || (
+    node.id = file.generateUidIdentifier("callee", scope)
+  );
+
+  var innerFnId = t.identifier(node.id.name + "$");
+  var contextId = file.generateUidIdentifier("context", scope);
+  var vars = hoist(path);
+
+  var emitter = new Emitter(contextId);
+  emitter.explode(path.get("body"));
+
+  var outerBody = [];
+
+  if (vars && vars.declarations.length > 0) {
+    outerBody.push(vars);
+  }
+
+  var wrapArgs = [
+    emitter.getContextFunction(innerFnId),
+    // Async functions don't care about the outer function because they
+    // don't need it to be marked and don't inherit from its .prototype.
+    node.async ? t.literal(null) : outerFnId,
+    t.thisExpression()
+  ];
+
+  var tryEntryList = emitter.getTryEntryList();
+  if (tryEntryList) {
+    wrapArgs.push(tryEntryList);
+  }
+
+  var wrapCall = t.callExpression(
+    node.async ? runtimeAsyncMethod : runtimeWrapMethod,
+    wrapArgs
+  );
+
+  outerBody.push(t.returnStatement(wrapCall));
+  node.body = t.blockStatement(outerBody);
+
+  if (node.async) {
+    node.async = false;
+    return;
+  }
+
+  if (t.isFunctionDeclaration(node)) {
+    var pp = path.parent;
+
+    while (pp && !(t.isBlockStatement(pp.value) || t.isProgram(pp.value))) {
+      pp = pp.parent;
+    }
+
+    if (!pp) {
+      return;
+    }
+
+    // Here we turn the FunctionDeclaration into a named
+    // FunctionExpression that will be assigned to a variable of the
+    // same name at the top of the enclosing block. This is important
+    // for a very subtle reason: named function expressions can refer to
+    // themselves by name without fear that the binding may change due
+    // to code executing outside the function, whereas function
+    // declarations are vulnerable to the following rebinding:
+    //
+    //   function f() { return f }
+    //   var g = f;
+    //   f = "asdf";
+    //   g(); // "asdf"
+    //
+    // One way to prevent the problem illustrated above is to transform
+    // the function declaration thus:
+    //
+    //   var f = function f() { return f };
+    //   var g = f;
+    //   f = "asdf";
+    //   g(); // f
+    //   g()()()()(); // f
+    //
+    // In the code below, we transform generator function declarations
+    // in the following way:
+    //
+    //   gen().next(); // { value: gen, done: true }
+    //   function *gen() {
+    //     return gen;
+    //   }
+    //
+    // becomes something like
+    //
+    //   var gen = runtime.mark(function *gen() {
+    //     return gen;
+    //   });
+    //   gen().next(); // { value: gen, done: true }
+    //
+    // which ensures that the generator body can always reliably refer
+    // to gen by name.
+
+    // Remove the FunctionDeclaration so that we can add it back as a
+    // FunctionExpression passed to runtime.mark.
+    path.replace();
+
+    // Change the type of the function to be an expression instead of a
+    // declaration. Note that all the other fields are the same.
+    node.type = "FunctionExpression";
+
+    var varDecl = t.variableDeclaration("var", [
+      t.variableDeclarator(
+        node.id,
+        t.callExpression(runtimeMarkMethod, [node])
+      )
+    ]);
+
+    // Copy any comments preceding the function declaration to the
+    // variable declaration, to avoid weird formatting consequences.
+    t.inheritsComments(varDecl, node);
+    t.removeComments(node);
+
+    varDecl._blockHoist = true;
+
+    var bodyPath = pp.get("body");
+    var bodyLen = bodyPath.value.length;
+
+    for (var i = 0; i < bodyLen; ++i) {
+      var firstStmtPath = bodyPath.get(i);
+      if (!shouldNotHoistAbove(firstStmtPath)) {
+        firstStmtPath.insertBefore(varDecl);
+        return;
+      }
+    }
+
+    bodyPath.push(varDecl);
+  } else {
+    t.assertFunctionExpression(node);
+    return t.callExpression(runtimeMarkMethod, [node]);
+  }
+};
+
+function shouldNotHoistAbove(stmtPath) {
+  var value = stmtPath.value;
+  t.assertStatement(value);
+
+  // If the first statement is a "use strict" declaration, make sure to
+  // insert hoisted declarations afterwards.
+  if (t.isExpressionStatement(value) &&
+      t.isLiteral(value.expression) &&
+      value.expression.value === "use strict") {
+    return true;
+  }
+
+  if (t.isVariableDeclaration(value)) {
+    for (var i = 0; i < value.declarations.length; ++i) {
+      var decl = value.declarations[i];
+      if (t.isCallExpression(decl.init) && types.astNodesAreEquivalent(decl.init.callee, runtimeMarkMethod)) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+var awaitVisitor = types.PathVisitor.fromMethodsObject({
+  visitFunction: function () {
+    return false; // Don't descend into nested function scopes.
+  },
+
+  visitAwaitExpression: function (path) {
+    // Convert await expressions to yield expressions.
+    return t.yieldExpression(path.value.argument, false);
+  }
+});

lib/6to5/transformation/transformers/es6-let-scoping.js

@@ -129,7 +129,7 @@ LetScoping.prototype.run = function () {
 
   // 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));
+  var ret  = this.file.generateUidIdentifier("ret", this.scope);
 
   var hasYield = traverse.hasType(fn.body, "YieldExpression", t.FUNCTION_TYPES);
   if (hasYield) {
@@ -445,7 +445,7 @@ LetScoping.prototype.buildHas = function (ret, call) {
   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));
+    var label = forParent.label = forParent.label || this.file.generateUidIdentifier("loop", this.scope);
 
     if (has.hasBreak) {
       cases.push(t.switchCase(t.literal("break"), [t.breakStatement(label)]));

lib/6to5/transformation/transformers/es6-modules.js

@@ -5,10 +5,10 @@ exports.ImportDeclaration = function (node, parent, file) {
 
   if (node.specifiers.length) {
     _.each(node.specifiers, function (specifier) {
-      file.moduleFormatter.importSpecifier(specifier, node, nodes);
+      file.moduleFormatter.importSpecifier(specifier, node, nodes, parent);
     });
   } else {
-    file.moduleFormatter.import(node, nodes);
+    file.moduleFormatter.import(node, nodes, parent);
   }
 
   return nodes;
@@ -18,10 +18,10 @@ exports.ExportDeclaration = function (node, parent, file) {
   var nodes = [];
 
   if (node.declaration) {
-    file.moduleFormatter.export(node, nodes);
+    file.moduleFormatter.export(node, nodes, parent);
   } else {
     _.each(node.specifiers, function (specifier) {
-      file.moduleFormatter.exportSpecifier(specifier, node, nodes);
+      file.moduleFormatter.exportSpecifier(specifier, node, nodes, parent);
     });
   }
 

lib/6to5/transformation/transformers/es6-property-name-shorthand.js

@@ -0,0 +1,4 @@
+exports.Property = function (node) {
+  if (!node.shorthand) return;
+  node.shorthand = false;
+};

lib/6to5/transformation/transformers/es6-rest-parameters.js

@@ -0,0 +1,22 @@
+var t = require("../../types");
+
+exports.Function = function (node, parent, file) {
+  if (!node.rest) return;
+
+  var rest = node.rest;
+  delete node.rest;
+
+  t.ensureBlock(node);
+
+  var call = file.toArray(t.identifier("arguments"));
+
+  if (node.params.length) {
+    call.arguments.push(t.literal(node.params.length));
+  }
+
+  call._ignoreAliasFunctions = true;
+
+  node.body.body.unshift(t.variableDeclaration("var", [
+    t.variableDeclarator(rest, call)
+  ]));
+};

lib/6to5/transformation/transformers/es6-spread.js

@@ -1,15 +1,8 @@
 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 getSpreadLiteral = function (spread, file) {
+  return file.toArray(spread.argument);
 };
 
 var hasSpread = function (nodes) {
@@ -23,7 +16,7 @@ var hasSpread = function (nodes) {
   return has;
 };
 
-var build = function (props) {
+var build = function (props, file) {
   var nodes = [];
 
   var _props = [];
@@ -37,7 +30,7 @@ var build = function (props) {
   _.each(props, function (prop) {
     if (t.isSpreadElement(prop)) {
       push();
-      nodes.push(getSpreadLiteral(prop));
+      nodes.push(getSpreadLiteral(prop, file));
     } else {
       _props.push(prop);
     }
@@ -48,19 +41,22 @@ var build = function (props) {
   return nodes;
 };
 
-exports.ArrayExpression = function (node) {
+exports.ArrayExpression = function (node, parent, file) {
   var elements = node.elements;
   if (!hasSpread(elements)) return;
 
-  var nodes = build(elements);
+  var nodes = build(elements, file);
   var first = nodes.shift();
 
-  if (!nodes.length) return first;
+  if (!t.isArrayExpression(first)) {
+    nodes.unshift(first);
+    first = t.arrayExpression([]);
+  }
 
   return t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes);
 };
 
-exports.CallExpression = function (node) {
+exports.CallExpression = function (node, parent, file) {
   var args = node.arguments;
   if (!hasSpread(args)) return;
 
@@ -68,7 +64,12 @@ exports.CallExpression = function (node) {
 
   node.arguments = [];
 
-  var nodes = build(args);
+  var nodes;
+  if (args.length === 1 && args[0].argument.name === 'arguments') {
+    nodes = [args[0].argument];
+  } else {
+    nodes = build(args, file);
+  }
   var first = nodes.shift();
 
   if (nodes.length) {
@@ -100,7 +101,7 @@ exports.NewExpression = function (node, parent, file) {
   var args = node.arguments;
   if (!hasSpread(args)) return;
 
-  var nodes = build(args);
+  var nodes = build(args, file);
   var first = nodes.shift();
 
   if (nodes.length) {

lib/6to5/transformation/transformers/es6-template-literals.js

@@ -22,9 +22,7 @@ exports.TaggedTemplateExpression = function (node, parent, file) {
     t.arrayExpression(raw)
   ]));
 
-  _.each(quasi.expressions, function (expr) {
-    args.push(expr);
-  });
+  args = args.concat(quasi.expressions);
 
   return t.callExpression(node.tag, args);
 };

lib/6to5/transformation/transformers/es7-abstract-references.js

@@ -0,0 +1,108 @@
+// https://github.com/zenparsing/es-abstract-refs
+
+var util = require("../../util");
+var t    = require("../../types");
+
+var container = function (parent, call, ret) {
+  if (t.isExpressionStatement(parent)) {
+    // we don't need to worry about return values
+    return call;
+  } else {
+    var exprs = [];
+    if (t.isSequenceExpression(call)) {
+      exprs = call.expressions;
+    } else {
+      exprs.push(call);
+    }
+    exprs.push(ret);
+    return t.sequenceExpression(exprs);
+  }
+};
+
+exports.AssignmentExpression = function (node, parent, file, scope) {
+  var left = node.left;
+  if (!t.isVirtualPropertyExpression(left)) return;
+
+  var value = node.right;
+  var temp;
+
+  // we need to return `node.right`
+  if (!t.isExpressionStatement(parent)) {
+    // `node.right` isn't a simple identifier so we need to reference it
+    if (t.isDynamic(value)) {
+      var tempName = file.generateUid("temp");
+      temp = value = t.identifier(tempName);
+      scope.push({
+        key: tempName,
+        id: temp
+      });
+    }
+  }
+
+  var call = util.template("abstract-expression-set", {
+    PROPERTY: left.property,
+    OBJECT:   left.object,
+    VALUE:    value
+  });
+
+  if (temp) {
+    call = t.sequenceExpression([
+      t.assignmentExpression("=", temp, node.right),
+      call
+    ]);
+  }
+
+  return container(parent, call, value);
+};
+
+exports.UnaryExpression = function (node, parent) {
+  var arg = node.argument;
+  if (!t.isVirtualPropertyExpression(arg)) return;
+  if (node.operator !== "delete") return;
+
+  var call = util.template("abstract-expression-delete", {
+    PROPERTY: arg.property,
+    OBJECT:   arg.object
+  });
+
+  return container(parent, call, t.literal(true));
+};
+
+exports.CallExpression = function (node, parent, file, scope) {
+  var callee = node.callee;
+  if (!t.isVirtualPropertyExpression(callee)) return;
+
+  var temp;
+  if (t.isDynamic(callee.object)) {
+    // we need to save `callee.object` so we can call it again
+    var tempName = file.generateUid("temp");
+    temp = t.identifier(tempName);
+    scope.push({
+      key: tempName,
+      id: temp
+    });
+  }
+
+  var call = util.template("abstract-expression-call", {
+    PROPERTY: callee.property,
+    OBJECT:   temp || callee.object
+  });
+
+  call.arguments = call.arguments.concat(node.arguments);
+
+  if (temp) {
+    return t.sequenceExpression([
+      t.assignmentExpression("=", temp, callee.object),
+      call
+    ]);
+  } else {
+    return call;
+  }
+};
+
+exports.VirtualPropertyExpression = function (node) {
+  return util.template("abstract-expression-get", {
+    PROPERTY: node.property,
+    OBJECT:   node.object
+  });
+};

lib/6to5/transformation/transformers/es7-array-comprehension.js

@@ -2,7 +2,7 @@ var util = require("../../util");
 var t    = require("../../types");
 var _    = require("lodash");
 
-var singleArrayExpression = function (node) {
+var single = function (node, file) {
   var block = node.blocks[0];
 
   var templateName = "array-expression-comprehension-map";
@@ -11,7 +11,7 @@ var singleArrayExpression = function (node) {
   var result = util.template(templateName, {
     STATEMENT: node.body,
     FILTER:    node.filter,
-    ARRAY:     block.right,
+    ARRAY:     file.toArray(block.right),
     KEY:       block.left
   });
 
@@ -25,7 +25,7 @@ var singleArrayExpression = function (node) {
 };
 
 var multiple = function (node, file) {
-  var uid = file.generateUid("arr");
+  var uid = file.generateUidIdentifier("arr");
 
   var container = util.template("array-comprehension-container", {
     KEY: uid
@@ -73,8 +73,8 @@ exports._build = function (node, buildBody) {
 exports.ComprehensionExpression = function (node, parent, file) {
   if (node.generator) return;
 
-  if (node.blocks.length === 1 && t.isArrayExpression(node.blocks[0].right)) {
-    return singleArrayExpression(node);
+  if (node.blocks.length === 1) {
+    return single(node, file);
   } else {
     return multiple(node, file);
   }

lib/6to5/transformation/transformers/es7-exponentiation-operator.js

@@ -0,0 +1,16 @@
+// https://github.com/rwaldron/exponentiation-operator
+
+var t = require("../../types");
+var pow = t.memberExpression(t.identifier("Math"), t.identifier("pow"));
+
+exports.AssignmentExpression = function (node) {
+  if (node.operator !== "**=") return;
+  node.operator = "=";
+  node.right = t.callExpression(pow, [node.left, node.right]);
+};
+
+exports.BinaryExpression = function (node) {
+  if (node.operator !== "**") return;
+
+  return t.callExpression(pow, [node.left, node.right]);
+};

lib/6to5/transformation/transformers/es7-generator-comprehension.js

@@ -1,4 +1,4 @@
-var arrayComprehension = require("./array-comprehension");
+var arrayComprehension = require("./es7-array-comprehension");
 var t                  = require("../../types");
 
 exports.ComprehensionExpression = function (node) {

lib/6to5/transformation/transformers/es7-object-spread.js

@@ -0,0 +1,41 @@
+// https://github.com/sebmarkbage/ecmascript-rest-spread
+
+var t = require("../../types");
+var _ = require("lodash");
+
+exports.ObjectExpression = function (node) {
+  var hasSpread = false;
+  _.each(node.properties, function (prop) {
+    if (t.isSpreadProperty(prop)) {
+      hasSpread = true;
+      return false;
+    }
+  });
+  if (!hasSpread) return;
+
+  var args = [];
+  var props = [];
+
+  var push = function () {
+    if (!props.length) return;
+    args.push(t.objectExpression(props));
+    props = [];
+  };
+
+  _.each(node.properties, function (prop) {
+    if (t.isSpreadProperty(prop)) {
+      push();
+      args.push(prop.argument);
+    } else {
+      props.push(prop);
+    }
+  });
+
+  push();
+
+  if (!t.isObjectExpression(args[0])) {
+    args.unshift(t.objectExpression([]));
+  }
+
+  return t.callExpression(t.memberExpression(t.identifier("Object"), t.identifier("assign")), args);
+};

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

@@ -1,219 +0,0 @@
-/**
- * Copyright (c) 2014, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * https://raw.githut.com/facebook/regenerator/master/LICENSE file. An
- * additional grant of patent rights can be found in the PATENTS file in
- * the same directory.
- */
-
-var runtimeProperty = require("./util").runtimeProperty;
-var Emitter         = require("./emit").Emitter;
-var hoist           = require("./hoist").hoist;
-var types           = require("ast-types");
-var t               = require("../../../types");
-
-var runtimeAsyncMethod = runtimeProperty("async");
-var runtimeWrapMethod  = runtimeProperty("wrap");
-var runtimeMarkMethod  = runtimeProperty("mark");
-
-exports.transform = function transform(node) {
-  return types.visit(node, visitor);
-};
-
-var visitor = types.PathVisitor.fromMethodsObject({
-  visitFunction: function(path) {
-    // Calling this.traverse(path) first makes for a post-order traversal.
-    this.traverse(path);
-
-    var node = path.value;
-
-    if (!node.generator && !node.async) {
-      return;
-    }
-
-    node.generator = false;
-
-    if (node.expression) {
-      // Transform expression lambdas into normal functions.
-      node.expression = false;
-      node.body = t.blockStatement([
-        t.returnStatement(node.body)
-      ]);
-    }
-
-    if (node.async) {
-      awaitVisitor.visit(path.get("body"));
-    }
-
-    var outerFnId = node.id || (
-      node.id = path.scope.parent.declareTemporary("callee$")
-    );
-
-    var innerFnId = t.identifier(node.id.name + "$");
-    var contextId = path.scope.declareTemporary("context$");
-    var vars = hoist(path);
-
-    var emitter = new Emitter(contextId);
-    emitter.explode(path.get("body"));
-
-    var outerBody = [];
-
-    if (vars && vars.declarations.length > 0) {
-      outerBody.push(vars);
-    }
-
-    var wrapArgs = [
-      emitter.getContextFunction(innerFnId),
-      // Async functions don't care about the outer function because they
-      // don't need it to be marked and don't inherit from its .prototype.
-      node.async ? t.literal(null) : outerFnId,
-      t.thisExpression()
-    ];
-
-    var tryEntryList = emitter.getTryEntryList();
-    if (tryEntryList) {
-      wrapArgs.push(tryEntryList);
-    }
-
-    var wrapCall = t.callExpression(
-      node.async ? runtimeAsyncMethod : runtimeWrapMethod,
-      wrapArgs
-    );
-
-    outerBody.push(t.returnStatement(wrapCall));
-    node.body = t.blockStatement(outerBody);
-
-    if (node.async) {
-      node.async = false;
-      return;
-    }
-
-    if (t.isFunctionDeclaration(node)) {
-      var pp = path.parent;
-
-      while (pp && !(t.isBlockStatement(pp.value) || t.isProgram(pp.value))) {
-        pp = pp.parent;
-      }
-
-      if (!pp) {
-        return;
-      }
-
-      // Here we turn the FunctionDeclaration into a named
-      // FunctionExpression that will be assigned to a variable of the
-      // same name at the top of the enclosing block. This is important
-      // for a very subtle reason: named function expressions can refer to
-      // themselves by name without fear that the binding may change due
-      // to code executing outside the function, whereas function
-      // declarations are vulnerable to the following rebinding:
-      //
-      //   function f() { return f }
-      //   var g = f;
-      //   f = "asdf";
-      //   g(); // "asdf"
-      //
-      // One way to prevent the problem illustrated above is to transform
-      // the function declaration thus:
-      //
-      //   var f = function f() { return f };
-      //   var g = f;
-      //   f = "asdf";
-      //   g(); // f
-      //   g()()()()(); // f
-      //
-      // In the code below, we transform generator function declarations
-      // in the following way:
-      //
-      //   gen().next(); // { value: gen, done: true }
-      //   function *gen() {
-      //     return gen;
-      //   }
-      //
-      // becomes something like
-      //
-      //   var gen = runtime.mark(function *gen() {
-      //     return gen;
-      //   });
-      //   gen().next(); // { value: gen, done: true }
-      //
-      // which ensures that the generator body can always reliably refer
-      // to gen by name.
-
-      // Remove the FunctionDeclaration so that we can add it back as a
-      // FunctionExpression passed to runtime.mark.
-      path.replace();
-
-      // Change the type of the function to be an expression instead of a
-      // declaration. Note that all the other fields are the same.
-      node.type = "FunctionExpression";
-
-      var varDecl = t.variableDeclaration("var", [
-        t.variableDeclarator(
-          node.id,
-          t.callExpression(runtimeMarkMethod, [node])
-        )
-      ]);
-
-      if (node.comments) {
-        // Copy any comments preceding the function declaration to the
-        // variable declaration, to avoid weird formatting consequences.
-        varDecl.comments = node.comments;
-        node.comments = null;
-      }
-
-      var bodyPath = pp.get("body");
-      var bodyLen = bodyPath.value.length;
-
-      for (var i = 0; i < bodyLen; ++i) {
-        var firstStmtPath = bodyPath.get(i);
-        if (!shouldNotHoistAbove(firstStmtPath)) {
-          firstStmtPath.insertBefore(varDecl);
-          return;
-        }
-      }
-
-      bodyPath.push(varDecl);
-
-    } else {
-      t.assertFunctionExpression(node);
-      return t.callExpression(runtimeMarkMethod, [node]);
-    }
-  }
-});
-
-function shouldNotHoistAbove(stmtPath) {
-  var value = stmtPath.value;
-  t.assertStatement(value);
-
-  // If the first statement is a "use strict" declaration, make sure to
-  // insert hoisted declarations afterwards.
-  if (t.isExpressionStatement(value) &&
-      t.isLiteral(value.expression) &&
-      value.expression.value === "use strict") {
-    return true;
-  }
-
-  if (t.isVariableDeclaration(value)) {
-    for (var i = 0; i < value.declarations.length; ++i) {
-      var decl = value.declarations[i];
-      if (t.isCallExpression(decl.init) && types.astNodesAreEquivalent(decl.init.callee, runtimeMarkMethod)) {
-        return true;
-      }
-    }
-  }
-
-  return false;
-}
-
-var awaitVisitor = types.PathVisitor.fromMethodsObject({
-  visitFunction: function() {
-    return false; // Don't descend into nested function scopes.
-  },
-
-  visitAwaitExpression: function(path) {
-    // Convert await expressions to yield expressions.
-    return t.yieldExpression(path.value.argument, false);
-  }
-});

lib/6to5/transformation/transformers/playground-memoization-operator.js

@@ -0,0 +1,90 @@
+var t = require("../../types");
+
+var isMemo = function (node) {
+  var is = t.isAssignmentExpression(node) && node.operator === "?=";
+  if (is) t.assertMemberExpression(node.left);
+  return is;
+};
+
+var getPropRef = function (nodes, prop, file, scope) {
+  if (t.isIdentifier(prop)) {
+    return t.literal(prop.name);
+  } else {
+    var temp = file.generateUidIdentifier("propKey", scope);
+    nodes.push(t.variableDeclaration("var", [
+      t.variableDeclarator(temp, prop)
+    ]));
+    return temp;
+  }
+};
+
+var getObjRef = function (nodes, obj, file, scope) {
+  if (t.isDynamic(obj)) {
+    var temp = file.generateUidIdentifier("obj", scope);
+    nodes.push(t.variableDeclaration("var", [
+      t.variableDeclarator(temp, obj)
+    ]));
+    return temp;
+  } else {
+    return obj;
+  }
+};
+
+var buildHasOwn = function (obj, prop, file) {
+  return t.unaryExpression(
+    "!",
+    t.callExpression(
+      t.memberExpression(file.addDeclaration("has-own"), t.identifier("call")),
+      [obj, prop]
+    ),
+    true
+  );
+};
+
+var buildAbsoluteRef = function (left, obj, prop) {
+  var computed = left.computed || t.isLiteral(prop);
+  return t.memberExpression(obj, prop, computed);
+};
+
+var buildAssignment = function (expr, obj, prop) {
+  return t.assignmentExpression("=", buildAbsoluteRef(expr.left, obj, prop), expr.right);
+};
+
+exports.ExpressionStatement = function (node, parent, file, scope) {
+  var expr = node.expression;
+  if (!isMemo(expr)) return;
+
+  var nodes = [];
+
+  var left = expr.left;
+  var obj  = getObjRef(nodes, left.object, file, scope);
+  var prop = getPropRef(nodes, left.property, file, scope);
+
+  nodes.push(t.ifStatement(
+    buildHasOwn(obj, prop, file),
+    t.expressionStatement(buildAssignment(expr, obj, prop))
+  ));
+
+  return nodes;
+};
+
+exports.AssignmentExpression = function (node, parent, file, scope) {
+  if (t.isExpressionStatement(parent)) return;
+  if (!isMemo(node)) return;
+
+  var nodes = [];
+
+  var left = node.left;
+  var obj  = getObjRef(nodes, left.object, file, scope);
+  var prop = getPropRef(nodes, left.property, file, scope);
+
+  nodes.push(t.logicalExpression(
+    "&&",
+    buildHasOwn(obj, prop, file),
+    buildAssignment(node, obj, prop)
+  ));
+
+  nodes.push(buildAbsoluteRef(left, obj, prop));
+
+  return t.toSequenceExpression(nodes, scope);
+};

lib/6to5/transformation/transformers/playground-method-binding.js

@@ -0,0 +1,58 @@
+var t = require("../../types");
+var _ = require("lodash");
+
+exports.BindMemberExpression = function (node, parent, file, scope) {
+  var object = node.object;
+  var prop   = node.property;
+
+  var temp;
+  if (t.isDynamic(object)) {
+    var tempName = file.generateUid("temp", scope);
+    temp =  object = t.identifier(tempName);
+    scope.push({
+      key: tempName,
+      id: temp
+    });
+  }
+
+  var call = t.callExpression(
+    t.memberExpression(t.memberExpression(object, prop), t.identifier("bind")),
+    [object].concat(node.arguments)
+  );
+
+  if (temp) {
+    return t.sequenceExpression([
+      t.assignmentExpression("=", temp, node.object),
+      call
+    ]);
+  } else {
+    return call;
+  }
+};
+
+exports.BindFunctionExpression = function (node, parent, file, scope) {
+  var buildCall = function (args) {
+    var param = file.generateUidIdentifier("val", scope);
+    return t.functionExpression(null, [param], t.blockStatement([
+      t.returnStatement(t.callExpression(t.memberExpression(param, node.callee), args))
+    ]));
+  };
+
+  if (_.find(node.arguments, t.isDynamic)) {
+    var argsIdName = file.generateUid("args", scope);
+    var argsId = t.identifier(argsIdName);
+    scope.push({
+      key: argsIdName,
+      id: argsId
+    });
+
+    return t.sequenceExpression([
+      t.assignmentExpression("=", argsId, t.arrayExpression(node.arguments)),
+      buildCall(node.arguments.map(function (node, i) {
+        return t.memberExpression(argsId, t.literal(i), true);
+      }))
+    ]);
+  } else {
+    return buildCall(node.arguments);
+  }
+};

lib/6to5/transformation/transformers/property-name-shorthand.js

@@ -1,3 +0,0 @@
-exports.Property = function (node) {
-  if (node.shorthand) node.shorthand = false;
-};

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

@@ -132,6 +132,8 @@ exports.XJSElement = {
           }
         });
 
+        return;
+      } else if (t.isXJSEmptyExpression(child)) {
         return;
       }
 

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

@@ -1,24 +0,0 @@
-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/traverse/index.js

@@ -50,12 +50,16 @@ function traverse(parent, callbacks, opts) {
         if (result != null) {
           updated = true;
           node = obj[key] = result;
+
+          if (_.isArray(result) && _.contains(t.STATEMENT_OR_BLOCK_KEYS, key) && !t.isBlockStatement(obj)) {
+            t.ensureBlock(obj, key);
+          }
         }
       };
 
       //
       var opts2 = { scope: opts.scope, blacklist: opts.blacklist };
-      if (t.isScope(node)) opts2.scope = new Scope(opts.scope, node);
+      if (t.isScope(node)) opts2.scope = new Scope(node, opts.scope);
 
       // enter
       if (callbacks.enter) {
@@ -89,9 +93,11 @@ function traverse(parent, callbacks, opts) {
 
 traverse.removeProperties = function (tree) {
   var clear = function (node) {
+    delete node._scopeReferences;
+    delete node._declarations;
     delete node.extendedRange;
-    delete node._scopeIds;
     delete node._parent;
+    delete node._scope;
     delete node.tokens;
     delete node.range;
     delete node.start;

lib/6to5/traverse/scope.js

@@ -6,25 +6,34 @@ var _        = require("lodash");
 
 var FOR_KEYS = ["left", "init"];
 
-function Scope(parent, block) {
+/**
+ * This searches the current "scope" and collects all references/declarations
+ * within.
+ *
+ * @param {Node} block
+ * @param {Scope} [parent]
+ */
+
+function Scope(block, parent) {
   this.parent = parent;
   this.block  = block;
 
-  this.info         = this.getInfo();
-  this.declarations = this.info.declarations;
+  this.references = this.getReferences();
 }
 
-Scope.prototype.getInfo = function () {
-  var block = this.block;
-  if (block._scope) return block._scope;
+Scope.add = function (node, references) {
+  if (!node) return;
+  _.merge(references, t.getIds(node, true));
+};
 
-  var self = this;
-  var info = block._scope = {
-    declarations: {}
-  };
+Scope.prototype.getReferences = function () {
+  var block = this.block;
+  if (block._scopeReferences) return block._scopeReferences;
+
+  var references = block._scopeReferences = {};
 
   var add = function (node) {
-    self.addDeclaration(node, info.declarations);
+    Scope.add(node, references);
   };
 
   // ForStatement - left, init
@@ -56,7 +65,7 @@ Scope.prototype.getInfo = function () {
   // Program, Function - var variables
 
   if (t.isProgram(block) || t.isFunction(block)) {
-    traverse(block, function (node) {
+    traverse(block, function (node, parent, scope) {
       if (t.isFor(node)) {
         _.each(FOR_KEYS, function (key) {
           var declar = node[key];
@@ -68,12 +77,16 @@ Scope.prototype.getInfo = function () {
       // declared within are accessible
       if (t.isFunction(node)) return false;
 
+      if (t.isIdentifier(node) && t.isReferenced(node, parent) && !scope.has(node.name)) {
+        add(node);
+      }
+
       // we've ran into a declaration!
       // we'll let the BlockStatement scope deal with `let` declarations
       if (t.isDeclaration(node) && !t.isLet(node)) {
         add(node);
       }
-    });
+    }, { scope: this });
   }
 
   // Function - params, rest
@@ -85,12 +98,31 @@ Scope.prototype.getInfo = function () {
     });
   }
 
-  return info;
+  return references;
 };
 
-Scope.prototype.addDeclaration = function (node, declarations) {
-  if (!node) return;
-  _.merge(declarations || this.declarations, t.getIds(node, true));
+Scope.prototype.push = function (opts) {
+  var block = this.block;
+
+  if (t.isFor(block) || t.isCatchClause(block) || t.isFunction(block)) {
+    t.ensureBlock(block);
+    block = block.body;
+  }
+
+  if (t.isBlockStatement(block) || t.isProgram(block)) {
+    block._declarations = block._declarations || {};
+    block._declarations[opts.key] = {
+      kind: opts.kind,
+      id: opts.id,
+      init: opts.init
+    };
+  } else {
+    throw new TypeError("cannot add a declaration here in node type " + block.type);
+  }
+};
+
+Scope.prototype.add = function (node) {
+  Scope.add(node, this.references);
 };
 
 Scope.prototype.get = function (id) {
@@ -98,7 +130,7 @@ Scope.prototype.get = function (id) {
 };
 
 Scope.prototype.getOwn = function (id) {
-  return _.has(this.declarations, id) && this.declarations[id];
+  return _.has(this.references, id) && this.references[id];
 };
 
 Scope.prototype.parentGet = function (id) {

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

@@ -11,6 +11,7 @@
   "Identifier":              ["name"],
   "IfStatement":             ["test", "consequent", "alternate"],
   "Literal":                 ["value"],
+  "LogicalExpression":       ["operator", "left", "right"],
   "MemberExpression":        ["object", "property", "computed"],
   "NewExpression":           ["callee", "arguments"],
   "ObjectExpression":        ["properties"],

lib/6to5/types/index.js

@@ -1,4 +1,5 @@
-var _ = require("lodash");
+var esutils = require("esutils");
+var _       = require("lodash");
 
 var t = exports;
 
@@ -11,6 +12,8 @@ var addAssert = function (type, is) {
   };
 };
 
+t.STATEMENT_OR_BLOCK_KEYS = ["consequent", "body"];
+
 //
 
 t.VISITOR_KEYS = require("./visitor-keys");
@@ -71,6 +74,31 @@ addAssert("Expression", t.isExpression);
 
 //
 
+t.toSequenceExpression = function (nodes, scope) {
+  var exprs = [];
+
+  _.each(nodes, function (node) {
+    if (t.isExpression(node)) {
+      exprs.push(node);
+    } if (t.isExpressionStatement(node)) {
+      exprs.push(node.expression);
+    } else if (t.isVariableDeclaration(node)) {
+      _.each(node.declarations, function (declar) {
+        scope.push({
+          kind: node.kind,
+          key: declar.id.name,
+          id: declar.id
+        });
+        exprs.push(t.assignmentExpression("=", declar.id, declar.init));
+      });
+    }
+  });
+
+  return t.sequenceExpression(exprs);
+};
+
+//
+
 t.shallowEqual = function (actual, expected) {
   var same = true;
 
@@ -87,6 +115,18 @@ t.shallowEqual = function (actual, expected) {
 
 //
 
+t.isDynamic = function (node) {
+  if (t.isParenthesizedExpression(node) || t.isExpressionStatement(node)) {
+    return t.isDynamic(node.expression);
+  } else if (t.isIdentifier(node) || t.isLiteral(node) || t.isThisExpression(node)) {
+    return false;
+  } else if (t.isMemberExpression(node)) {
+    return t.isDynamic(node.object) || t.isDynamic(node.property);
+  } else {
+    return true;
+  }
+};
+
 t.isReferenced = function (node, parent) {
   // we're a property key so we aren't referenced
   if (t.isProperty(parent) && parent.key === node) return false;
@@ -125,8 +165,13 @@ t.toIdentifier = function (name) {
   return name;
 };
 
-t.ensureBlock = function (node) {
-  node.body = t.toBlock(node.body, node);
+t.isValidIdentifier = function (name) {
+  return _.isString(name) && esutils.keyword.isIdentifierName(name) && !esutils.keyword.isKeywordES6(name, true);
+};
+
+t.ensureBlock = function (node, key) {
+  key = key || "body";
+  node[key] = t.toBlock(node[key], node);
 };
 
 t.toStatement = function (node, ignore) {
@@ -250,6 +295,11 @@ t.inheritsComments = function (child, parent) {
   return child;
 };
 
+t.removeComments = function (node) {
+  delete node.leadingComments;
+  delete node.trailingComments;
+};
+
 t.inherits = function (child, parent) {
   child.loc   = parent.loc;
   child.end   = parent.end;

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

@@ -1,76 +1,80 @@
 {
-  "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"],
-  "ComprehensionBlock":       ["left", "right", "body"],
-  "ComprehensionExpression":  ["filter", "blocks", "body"],
-  "ConditionalExpression":    ["test", "consequent", "alternate"],
-  "ContinueStatement":        ["label"],
-  "DebuggerStatement":        [],
-  "DoWhileStatement":         ["body", "test"],
-  "EmptyStatement":           [],
-  "ExportBatchSpecifier":     [],
-  "ExportDeclaration":        ["declaration", "specifiers", "source"],
-  "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"],
-  "ImportBatchSpecifier":     ["id"],
-  "ImportDeclaration":        ["specifiers", "source"],
-  "ImportSpecifier":          ["id", "name"],
-  "LabeledStatement":         ["label", "body"],
-  "Literal":                  [],
-  "LogicalExpression":        ["left", "right"],
-  "MemberExpression":         ["object", "property"],
-  "MethodDefinition":         ["key", "value"],
-  "NewExpression":            ["callee", "arguments"],
-  "ObjectExpression":         ["properties"],
-  "ObjectPattern":            ["properties"],
-  "ParenthesizedExpression":  ["expression"],
-  "Program":                  ["body"],
-  "Property":                 ["key", "value"],
-  "ReturnStatement":          ["argument"],
-  "SequenceExpression":       ["expressions"],
-  "SpreadElement":            ["argument"],
-  "SwitchCase":               ["test", "consequent"],
-  "SwitchStatement":          ["discriminant", "cases"],
-  "TaggedTemplateExpression": ["tag", "quasi"],
-  "TemplateElement":          [],
-  "TemplateLiteral":          ["quasis", "expressions"],
-  "ThisExpression":           [],
-  "ThrowStatement":           ["argument"],
-  "TryStatement":             ["block", "handlers", "handler", "guardedHandlers", "finalizer"],
-  "UnaryExpression":          ["argument"],
-  "UpdateExpression":         ["argument"],
-  "VariableDeclaration":      ["declarations"],
-  "VariableDeclarator":       ["id", "init"],
-  "WhileStatement":           ["test", "body"],
-  "WithStatement":            ["object", "body"],
-  "XJSAttribute":             ["name", "value"],
-  "XJSClosingElement":        ["name"],
-  "XJSElement":               ["openingElement", "closingElement", "children"],
-  "XJSEmptyExpression":       [],
-  "XJSExpressionContainer":   ["expression"],
-  "XJSIdentifier":            [],
-  "XJSMemberExpression":      ["object", "property"],
-  "XJSNamespacedName":        ["namespace", "name"],
-  "XJSOpeningElement":        ["name", "attributes"],
-  "XJSSpreadAttribute":       ["argument"],
-  "YieldExpression":          ["argument"]
+  "ArrayExpression":           ["elements"],
+  "ArrayPattern":              ["elements"],
+  "ArrowFunctionExpression":   ["params", "defaults", "rest", "body"],
+  "AssignmentExpression":      ["left", "right"],
+  "AwaitExpression":           ["argument"],
+  "BinaryExpression":          ["left", "right"],
+  "BindMemberExpression":      ["object", "property", "arguments"],
+  "BlockStatement":            ["body"],
+  "BreakStatement":            ["label"],
+  "CallExpression":            ["callee", "arguments"],
+  "CatchClause":               ["param", "body"],
+  "ClassBody":                 ["body"],
+  "ClassDeclaration":          ["id", "body", "superClass"],
+  "ClassExpression":           ["id", "body", "superClass"],
+  "ComprehensionBlock":        ["left", "right", "body"],
+  "ComprehensionExpression":   ["filter", "blocks", "body"],
+  "ConditionalExpression":     ["test", "consequent", "alternate"],
+  "ContinueStatement":         ["label"],
+  "DebuggerStatement":         [],
+  "DoWhileStatement":          ["body", "test"],
+  "EmptyStatement":            [],
+  "ExportBatchSpecifier":      [],
+  "ExportDeclaration":         ["declaration", "specifiers", "source"],
+  "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"],
+  "ImportBatchSpecifier":      ["id"],
+  "ImportDeclaration":         ["specifiers", "source"],
+  "ImportSpecifier":           ["id", "name"],
+  "LabeledStatement":          ["label", "body"],
+  "Literal":                   [],
+  "LogicalExpression":         ["left", "right"],
+  "MemberExpression":          ["object", "property"],
+  "MethodDefinition":          ["key", "value"],
+  "NewExpression":             ["callee", "arguments"],
+  "ObjectExpression":          ["properties"],
+  "ObjectPattern":             ["properties"],
+  "ParenthesizedExpression":   ["expression"],
+  "BindFunctionExpression":    ["callee", "arguments"],
+  "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"],
+  "UnaryExpression":           ["argument"],
+  "UpdateExpression":          ["argument"],
+  "VariableDeclaration":       ["declarations"],
+  "VariableDeclarator":        ["id", "init"],
+  "VirtualPropertyExpression": ["object", "property"],
+  "WhileStatement":            ["test", "body"],
+  "WithStatement":             ["object", "body"],
+  "XJSAttribute":              ["name", "value"],
+  "XJSClosingElement":         ["name"],
+  "XJSElement":                ["openingElement", "closingElement", "children"],
+  "XJSEmptyExpression":        [],
+  "XJSExpressionContainer":    ["expression"],
+  "XJSIdentifier":             [],
+  "XJSMemberExpression":       ["object", "property"],
+  "XJSNamespacedName":         ["namespace", "name"],
+  "XJSOpeningElement":         ["name", "attributes"],
+  "XJSSpreadAttribute":        ["argument"],
+  "YieldExpression":           ["argument"]
 }

lib/6to5/util.js

@@ -38,9 +38,9 @@ exports.list = function (val) {
 };
 
 exports.regexify = function (val) {
-  if (!val) return new RegExp;
+  if (!val) return new RegExp(/.^/);
   if (_.isArray(val)) val = val.join("|");
-  if (_.isString(val)) return new RegExp(val || "");
+  if (_.isString(val)) return new RegExp(val);
   if (_.isRegExp(val)) return val;
   throw new TypeError("illegal type for regexify");
 };
@@ -65,7 +65,7 @@ exports.getUid = function (parent, file) {
 
   if (t.isIdentifier(node)) id = node.name;
 
-  return t.identifier(file.generateUid(id));
+  return file.generateUidIdentifier(id);
 };
 
 exports.isAbsolute = function (loc) {
@@ -218,7 +218,8 @@ exports.parse = function (opts, code, callback) {
     var ast = acorn.parse(code, {
       allowReturnOutsideFunction: true,
       preserveParens:             true,
-      ecmaVersion:                Infinity,
+      ecmaVersion:                opts.experimental ? 7 : 6,
+      playground:                 opts.playground,
       strictMode:                 true,
       onComment:                  comments,
       locations:                  true,

package.json

@@ -1,7 +1,7 @@
 {
   "name": "6to5",
   "description": "Turn ES6 code into readable vanilla ES5 with source maps",
-  "version": "1.12.21",
+  "version": "1.14.7",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://github.com/6to5/6to5",
   "repository": {
@@ -35,26 +35,27 @@
     "test": "make test"
   },
   "dependencies": {
-    "ast-types": "~0.6.0",
+    "acorn-6to5": "0.9.1-11",
+    "ast-types": "0.6.5",
+    "chokidar": "0.11.1",
     "commander": "2.5.0",
-    "fs-readdir-recursive": "0.0.2",
+    "es6-shim": "0.21.0",
+    "es6-symbol": "0.1.1",
+    "estraverse": "1.8.0",
+    "esutils": "1.1.6",
+    "fs-readdir-recursive": "0.1.0",
     "lodash": "2.4.1",
     "mkdirp": "0.5.0",
-    "es6-shim": "0.20.2",
-    "es6-symbol": "0.1.1",
+    "private": "0.1.6",
     "regexpu": "0.3.0",
+    "roadrunner": "^1.0.4",
     "source-map": "0.1.40",
-    "chokidar": "0.10.5",
-    "source-map-support": "0.2.8",
-    "esutils": "1.1.4",
-    "acorn-6to5": "0.9.1-2",
-    "estraverse": "^1.7.0",
-    "private": "^0.1.6"
+    "source-map-support": "0.2.8"
   },
   "devDependencies": {
     "istanbul": "0.3.2",
     "matcha": "0.6.0",
-    "mocha": "2.0.1",
+    "mocha": "1.21.4",
     "uglify-js": "2.4.15",
     "browserify": "6.3.2",
     "rimraf": "2.2.8",

test/fixtures/generation/types/SequenceExpression/expected.js

@@ -1,4 +1,3 @@
 foo, bar;
 
-foo,
-bar;
+foo, bar;