v3.0.7

Conflicts:
	package.json

.gitignore

@@ -4,6 +4,12 @@ test/tmp
 *.log
 *.cache
 /templates.json
+/tests.json
 /browser.js
+/browser-polyfill.js
+/runtime.js
 coverage
 dist
+.package.json
+packages/6to5-runtime/*.js
+packages/6to5-runtime/regenerator/*.js

.gitmodules

@@ -0,0 +1,9 @@
+[submodule "vendor/traceur"]
+	path = vendor/traceur
+	url = https://github.com/google/traceur-compiler
+[submodule "vendor/regenerator"]
+	path = vendor/regenerator
+	url = https://github.com/6to5/regenerator-6to5
+[submodule "vendor/test262"]
+	path = vendor/test262
+	url = https://github.com/tc39/test262

.jscsrc

@@ -0,0 +1,60 @@
+{
+  "excludeFiles": ["lib/6to5/transformation/templates"],
+  "disallowSpacesInNamedFunctionExpression": {
+    "beforeOpeningRoundBrace": true
+  },
+  "requireSpacesInAnonymousFunctionExpression": {
+    "beforeOpeningRoundBrace": true
+  },
+  "requireSpacesInAnonymousFunctionExpression": {
+    "beforeOpeningRoundBrace": true
+  },
+  "disallowSpacesInFunctionDeclaration": {
+    "beforeOpeningRoundBrace": true
+  },
+  "disallowSpacesInsideArrayBrackets": true,
+  "disallowSpacesInsideParentheses": true,
+  "disallowQuotedKeysInObjects": true,
+  "disallowSpaceAfterObjectKeys": true,
+  "disallowSpaceAfterPrefixUnaryOperators": true,
+  "disallowSpaceBeforePostfixUnaryOperators": true,
+  "disallowSpaceBeforeBinaryOperators": [
+    ","
+  ],
+  "disallowMixedSpacesAndTabs": true,
+  "disallowTrailingWhitespace": true,
+  "disallowYodaConditions": true,
+  "disallowKeywords": [ "with" ],
+  "disallowMultipleLineBreaks": true,
+  "requireSpaceBeforeBlockStatements": true,
+  "requireParenthesesAroundIIFE": true,
+  "requireSpacesInConditionalExpression": true,
+  "requireBlocksOnNewline": 1,
+  "requireCommaBeforeLineBreak": true,
+  "requireSpaceBeforeBinaryOperators": true,
+  "requireSpaceAfterBinaryOperators": true,
+  "requireCamelCaseOrUpperCaseIdentifiers": true,
+  "requireLineFeedAtFileEnd": true,
+  "requireCapitalizedConstructors": true,
+  "requireDotNotation": true,
+  "requireSpacesInForStatement": true,
+  "requireCurlyBraces": [
+    "do"
+  ],
+  "requireSpaceAfterKeywords": [
+    "if",
+    "else",
+    "for",
+    "while",
+    "do",
+    "switch",
+    "case",
+    "return",
+    "try",
+    "catch",
+    "typeof"
+  ],
+  "validateLineBreaks": "LF",
+  "validateQuoteMarks": "\"",
+  "validateIndentation": 2
+}

.jshintignore

@@ -1,3 +1 @@
-node_modules
-test
-lib/6to5/templates
+lib/6to5/transformation/templates

.jshintrc

@@ -5,7 +5,6 @@
   "camelcase": true,
   "unused": true,
   "eqnull": true,
-  "proto": true,
   "newcap": true,
   "supernew": true,
   "noyield": true,
@@ -14,12 +13,11 @@
   "boss": true,
   "expr": true,
   "undef": true,
-  "loopfunc": true,
-  "white": true,
   "maxparams": 5,
   "maxdepth": 4,
 
   "globals": {
+    "window": true,
     "suite": true,
     "set": true,
     "before": true,

.npmignore

@@ -1,10 +1,15 @@
 node_modules
 *.log
 *.cache
-lib/6to5/templates
+lib/6to5/transformation/templates
 test
 benchmark
 Makefile
 .*
 dist
-!README.md
+tests.json
+CHANGELOG.md
+.package.json
+coverage
+vendor
+packages

.travis.yml

@@ -1,12 +1,20 @@
+sudo: false
 language: node_js
 node_js:
   - "0.10"
   - "0.11"
 
+branches:
+  except:
+   - experimental
+
 before_script: "npm install -g codeclimate-test-reporter"
 script: "make test-travis"
 
-addons:
-  code_climate:
-    repo_token:
-      secure: "PfP9sDUJzSznDb+ZEPO2cignXabSTXJxEVm5ESRPgEcFr+/4b0pt3hI8R9b+9mLtBEwtw3DLUq48MOeqEKnq29csQmpjPVcN6gT4uR2DdNa1JpVgDuwxT05NB3fBea9U2reM73iV8ylCgPHExr2uGR9/87JzR2beY/56EUL5NjY="
+notifications:
+  webhooks:
+    urls:
+      - https://webhooks.gitter.im/e/acf1870e9d223c65e8d5
+    on_success: always
+    on_failure: always
+    on_start: false

CHANGELOG.md

@@ -0,0 +1,841 @@
+# Changelog
+
+> **Tags:**
+> - [New Feature]
+> - [Bug Fix]
+> - [Spec Compliancy]
+> - [Breaking Change]
+> - [Documentation]
+> - [Internal]
+> - [Polish]
+
+_Note: Gaps between patch versions are faulty/broken releases._
+
+## 3.0.7
+
+ * **Internal**
+  * Upgrade `core-js` to `0.4.9`.
+ * **Bug Fix**
+  * Add id to function express scope tracking.
+
+## 3.0.6
+
+ * **Bug Fix**
+  * Fix block scope variable tracking stopping whenever it hits a new scope.
+  * Fix block scope variable tracking breaking on all block statement scopes that have a for loop parent.
+
+## 3.0.5
+
+ * **Internal**
+  * More reliable default parameter scope.
+
+## 3.0.4
+
+ * **Bug Fix**
+  * Remove traversal stops from block scope tracking.
+
+## 3.0.3
+
+ * **Internal**
+  * Ignore options starting with `_`.
+
+## 3.0.2
+
+ * **Internal**
+  * Add common plugin options to valid options list.
+
+## 3.0.1
+
+ * **Internal**
+  * Downgrade `kexec` as `1.1.0` throws compilation errors.
+
+## 3.0.0
+
+ * **Polish**
+  * Generated code autoindentation.
+  * Moved global uid registry to a scope registry resulting in nicer uids.
+  * `this` is now illegal in the top level scope when using the default `useStrict` transformer.
+  * New `asyncToGenerator` helper that's much more compact.
+  * Throw errors on unknown options.
+  * More reliable default parameter scope.
+  * Helpers are now compact and have no newlines.
+ * **Internal**
+  * Rewritten a lot of the internals to much simpler.
+  * Removed TDZ from default parameters as it was very wonky and unreliable.
+  * Upgrade `core-js` to `0.4.6`.
+  * Upgrade `acorn-6to5`.
+   * JSX support is now on-par with react-tools/esprima.
+   * Shorthand destructuring.
+ * **Bug Fix**
+  * Generators now work flawlessly with any parameter transformers.
+  * Optional async function transformers should not name their functions.
+  * Remove `unlink` event watching in `bin/6to5`.
+  * Fix regenerator variable declarations being incorrectly hoisted breaking scope.
+  * Transformers that attempted to simplify expressions that had no consequence now take into account whether it's one of the last statements/expressions in the script.
+ * **New Feature**
+  * New `selfContained` transformer.
+  * New `undeclaredVariableCheck` optional transformer.
+  * Added `--blacklist` and `--whitelist` options to `6to5-node`.
+ * **Breaking Change**
+  * Caching is now always enabled for the require hook. It also now no longer caches require resolutions.
+  * Bare `super();` only works inside of constructors.
+  * Removed the optional runtime in favor of the `selfContained` transformer.
+  * This shorthand has been removed from the playground.
+  * `6to5/polyfill` can now only be required **once**.
+  * **CLI**
+   * `--indent` option has been removed.
+   * `--include-regenerator` option has been removed.
+   * `--amd-modules-id` option has been removed, use `--module-ids` instead.
+  * **Options**
+   * `amdModuleIds` option has been removed, use `moduleIds` instead.
+   * `includeRegenerator` has been removed.
+   * `ignoreRegex` fallback has now been dropped from the require hook. `register(/foo/);`, `register({ ignoreRegex: /foo/ })` -> `register({ ignore: /foo/ })`.
+  * **Modules**
+    * Module interop now only collapses to `module.exports` when there's a **single** export that's default.
+    * Imports and exports are now illegal anywhere except the root level by default. Set `modules` to [loose mode](http://6to5.org/docs/usage/loose) to allow them everywhere.
+  * **Transformers**
+    * Optional fast transformer backwards compatibility support has been removed. Use [loose mode](https://6to5.org/docs/usage/loose).
+    * Removed the `coreAliasing` transformer in favor of `selfContained`.
+    * Renamed transformers:
+     * `specNoForInOfAssignment` -> `validation.noForInOfAssignment`
+     * `specSetters` -> `validation.setters`
+     * `specBlockScopedFunctions` -> `spec.blockScopedFunctions`
+     * `malletOperator` -> `playground.malletOperator`
+     * `methodBinding` -> `playground.methodBinding`
+     * `memoizationOperator` -> `playground.memoizationOperator`
+     * `objectGetterMemoization` -> `playground.objectGetterMemoization`
+     * `modules` -> `es6.modules`
+     * `propertyNameShorthand` -> `es6.properties.shorthand`
+     * `arrayComprehension` -> `es7.comprehensions`
+     * `generatorComprehension` -> `es7.comprehensions`
+     * `arrowFunctions` -> `es6.arrowFunctions`
+     * `classes` -> `es6.classes`
+     * `objectSpread` -> `es7.objectSpread`
+     * `exponentiationOperator` -> `es7.exponentiationOperator`
+     * `spread` -> `es6.spread`
+     * `templateLiterals` -> `es6.templateLiterals`
+     * `propertyMethodAssignment` -> `es6.properties.shorthand`
+     * `computedPropertyNames` -> `es6.properties.computed`
+     * `defaultParameters` -> `es6.parameters.default`
+     * `restParameters` -> `es6.parameters.rest`
+     * `destructuring` -> `es6.destructuring`
+     * `forOf` -> `es6.forOf`
+     * `unicodeRegex` -> `es6.unicodeRegex`
+     * `abstractReferences` -> `es7.abstractReferences`
+     * `constants` -> `es6.constants`
+     * `letScoping` -> `es6.blockScoping`
+     * `blockScopingTDZ` -> `es6.blockScopingTDZ`
+     * `generators` -> `regenerator`
+     * `protoToAssign` -> `spec.protoToAssign`
+     * `typeofSymbol` -> `spec.typeofSymbol`
+     * `coreAliasing` -> `selfContained`
+     * `undefinedToVoid` -> `spec.undefinedToVoid`
+     * `undeclaredVariableCheck` -> `validation.undeclaredVariableCheck`
+     * `specPropertyLiterals` -> `minification.propertyLiterals`
+     * `specMemberExpressionLiterals` -> `minification.memberExpressionLiterals`
+
+## 2.13.7
+
+ * **Bug Fix**
+  * Don't realias variables that are already declared in optional `coreAliasing` transformer.
+
+## 2.13.6
+
+ * **Bug Fix**
+  * Add `NewExpression` as a valid parent for parentheses insertion for `ConditionalExpression`.
+
+## 2.13.5
+
+ * **Bug Fix**
+  * Allow rest parameters to be destructuring patterns.
+ * **Internal**
+  * Upgrade `kexec` to `1.1.0`.
+
+## 2.13.4
+
+ * **Bug Fix**
+  * Fix ordering of destructuring and default params.
+  * Fix loop body scope.
+  * Fix `for...of` transformation not retaining it's scope.
+  * Add destructuring assignment support to scope tracking.
+ * **Polish**
+  * More reliable newlines for pretty printing variable declarations.
+
+## 2.13.3
+
+ * **Internal**
+  * Add `coverage` and `vendor` to npmignore.
+
+## 2.13.2
+
+ * **Bug Fix**
+  * Fix `super` inside of nested functions.
+ * **Internal**
+  * Move let scoping TDZ into a separate transformer until it's more solid.
+  * Use `process.stdin.write` instead of `console.log` in `bin` to avoid sprintfification.
+
+## 2.13.1
+
+ * **New Feature**
+  * Temporal dead zone for block binding.
+
+## 2.13.0
+
+ * **New Feature**
+  * Block scoped functions.
+  * Add `--loose all` option.
+  * Add playground mallet operator thanks to [@jridgewell](https://github.com/jridgewell).
+ * **Bug Fix**
+  * Rewrote large parts of the let scoping transformer. Now passes all known tests.
+ * **Internal**
+  * Even more optimisations thanks to the awesome [@gaearon](https://github.com/gaearon).
+  * Upgrade `acorn-6to5`.
+    * Fixes exponentation operator thanks to [@charliesome](https://github.com/charliesome).
+    * Fix flow optional parameters with types.
+  * Upgrade `chokidar` to `0.12.6`.
+  * Upgrade `commander` to `2.6.0`.
+  * Upgrade `core-js` to `0.4.5`.
+  * Upgrade `estraverse` to `1.9.1`.
+  * Upgrade `jshint` to `2.5.11`.
+  * Upgrade `regenerator` to `0.8.9`.
+  * Upgrade `regexpu` to `1.0.0`.
+  * Upgrade `source-map` to `0.1.43`.
+  * Upgrade `source-map-support` to `0.2.9`.
+  * Upgrade `browserify` to `8.1.1`.
+  * Upgrade `chai` to `1.10.0`.
+  * Upgrade `istanbul` to `0.3.5`.
+  * Upgrade `mocha` to `2.1.0`.
+  * Upgrade `uglify-js` to `2.4.16`.
+
+## 2.12.6
+
+ * **Bug Fix**
+  * Add missing flow type traversal keys.
+
+## 2.12.5
+
+ * **Internal**
+  * Fix incorrect `for...in` loop still causing `ember-script` issues.
+
+## 2.12.4
+
+ * **Polish**
+  * Rest parameters now allocate the array before populating.
+ * **Internal**
+  * `for...in` loops have been changed to optimised `for` loops - better performance and no enumeration of protoype keys.
+  * Parts of the code generator have now been optimised thanks to [gaearon](https://github.com/gaearon).
+
+## 2.12.3
+
+ * **Spec Compliancy**
+  * Optional `typeof` transformer checks for `undefined` before passing it to the helper.
+  * Class methods are now named.
+
+## 2.12.2
+
+ * **Internal**
+  * Exclude nodes in function parameters and catch clauses from `isReferenced` check.
+
+## 2.12.1
+
+ * **Internal**
+  * Add `.jsx` to list of allowed extensions.
+
+## 2.12.0
+
+ * **Bug Fix**
+  * Support non-string JSX literals.
+ * **New Feature**
+  * Loose mode for some transformers that enables non-spec behaviour.
+ * **Internal**
+  * Uglify `--mangle sort` has been added to the build script, cutting minified scripts in half.
+
+## 2.11.4
+
+ * **Internal**
+  * Make all dependency versions fixed.
+
+## 2.11.3
+
+ * **Bug Fix**
+  * Allow a string to be passed as the `optional` option.
+
+## 2.11.2
+
+ * **Bug Fix**
+  * Support esprima-style catch clause handlers.
+ * **Polish**
+  * Don't print a stacktrace for syntax errors in the CLI.
+
+## 2.11.1
+
+ * **Bug Fix**
+  * Remove stray `console.log` outputting debug code.
+  * Remove `Dict` from `coreAliasing`.
+
+## 2.11.0
+
+ * **Bug Fix**
+  * Fix unnecessary IIFE in default parameters on method calls.
+  * Add support for supers inside of closures.
+ * **New Feature**
+  * Add `--keep-module-id-extensions`/`keepModuleIdExtensions` option to keep extensions in module ids.
+ * **Polish**
+  * Special case single argument spread properties in `super` inside classes.
+  * Don't use a variable declaration for class declaration IFFE.
+  * Rename `inherits` helper parameters.
+  * `coreAliasing` transformer now aliases `Promise`, `Set`, `Map` and more. Thanks [@AluisioASG](https://github.com/AluisioASG).
+
+## 2.10.1
+
+ * **Internal**
+  * Upgrade `core-js` to `0.4.4`.
+ * **New Feature**
+  * Added `--include-regenerator` option to CLI and `includeRegenerator` option to API that includes the regenerator runtime if necessary.
+
+## 2.10.0
+
+ * **New Feature**
+  * Add `classesFastSuper` optional transformer that doesn't support parent getters and prototype changing.
+  * Add `forOfFast` transformer that speeds up `for...of` on arrays but produces more code.
+  * Add `--react-compat` to `bin/6to5`.
+ * **Spec Compliancy**
+  * Disallow setters without a single parameter.
+  * Add `configurable` and `writable` to defined properties.
+  * Use define instead of assignment for class methods.
+ * **Polish**
+  * Fix bin name in `6to5-node --help`.
+  * Fix shorthand `--whitelist` name in `bin/6to5`.
+ * **Internal**
+  * Hot code optimisation of traversal etc thanks to [gaearon](https://github.com/gaearon).
+
+## 2.9.4
+
+ * **Bug Fix**
+  * Support `UpdateExpression`s as `MemberExpression` objects.
+
+## 2.9.3
+
+ * **Bug Fix**
+  * Remove `exportsWildcard` helper in favor of `defaults`.
+
+## 2.9.2
+
+ * **Bug Fix**
+  * Pass `exports` to `exportWildcard` helper to allow for use inside the optional runtime.
+
+## 2.9.1
+
+ * **Bug Fix**
+  * Fix runtime generator breaking the helper inclusion loop.
+
+## 2.9.0
+
+ * **Internal**
+  * Upgrade `acorn-6to5`.
+    * Now supports destructuring shorthand properties.
+
+## 2.8.1
+
+ * **Bug Fix**
+  * Fix computed accessors on object literals.
+
+## 2.8.0
+
+ * **New Feature**
+  * Add `commonStrict`, `amdStrict` and `umdStrict` module formatters that remove `module.exports` interop assignment.
+  * Add `--indent` option to the 6to5 CLI.
+
+## 2.7.4
+
+ * **Polish**
+  * Inherit assignments from their declaration in destructuring.
+  * Properly align multi-declarator variable declarations.
+
+## 2.7.3
+
+ * **Polish**
+  * Indent and add newlines to `React.createElement` calls in `react` transformer.
+  * Remove `Object.assign` calls and replace it with an `extends` helper.
+
+## 2.7.1
+
+ * **New Feature**
+  * Expose `version` on browser and node API.
+ * **Internal**
+  * Upgrade `core-js` to 0.4.1
+
+## 2.7.0
+
+ * **Spec Compliancy**
+  * Disallow reassignments of imports.
+ * **New Feature**
+  * `reactCompat` option to enable pre-v0.12 react components.
+
+## 2.6.3
+
+ * **Bug Fix**
+  * Fix 2.6.0 regression caused by faulty export default from a source handling.
+
+## 2.6.2
+
+ * **Bug Fix**
+  * Fix rest parameter keys when on functions with params.
+
+## 2.6.1
+
+ * **Bug Fix**
+  * Fix rest parameter arguments key.
+
+## 2.6.0
+
+ * **Bug Fix**
+  * Better handling of number literal property keys.
+  * Handle `NewExpression` paren insertion edegcases better.
+ * **Internal**
+  * Fix incorrect AST node `identifier("this")`.
+  * Better `toIdentifier` method that handles reserved words.
+  * Upgrade `acorn-6to5`.
+    * Fix exponentiation operator precedence.
+    * Fix line terminators after async contextual keywords.
+    * Add semicolons as class elements inside of a class body.
+  * Upgrade to `core-js` 4.0.0.
+  * Upgrade to `regenerator` 0.8.3.
+    * Fix non-loop labeled statements.
+ * **New Feature**
+  * Basic destructuring defaults
+  * Add `.es` to list of supported extensions.
+  * Add optional `typeofSymbol` transformer.
+  * Use a `for` loop for rest parameters instead of `Array.prototype.slice`.
+ * **Polish**
+  * Move `"use strict";` to inside module bodies instead of at the top of the file.
+  * Better handling of dynamic imports.
+ * **Spec Compliancy**
+  * Class inheritance now has a `function` or `null` type check.
+  * Add `interopRequireWildcard` around wildcard imports and exports to handle non-object exports.
+
+## 2.5.0
+
+ * Remove `noDuplicateProperties` transformer.
+ * Better generated UIDs based on nodes.
+ * Default parameters now use `arguments[i]`, conditionals and variable declarations instead of using long-form if statements.
+
+## 2.4.10
+
+ * Upgrade `acorn-6to5`.
+
+## 2.4.9
+
+ * Upgrade `acorn-6to5`.
+ * Add optional `protoToAssign` transformer.
+ * Fix missing properties from computed property keys.
+ * Make ES7 comprehensions `let` variables.
+
+## 2.4.8
+
+ * Make `require("6to5/register")` work with browserify - [#370](https://github.com/6to5/6to5/pull/370). Thanks [@hughsk](https://github.com/hughsk)!
+
+## 2.4.7
+
+ * Upgrade `acorn-6to5`.
+
+## 2.4.6
+
+ * Move `coreAliasing` and `undefinedToVoid` transformers down to catch `moduleFormatter` transforms.
+
+## 2.4.5
+
+ * Avoid printing comments if they've already been output.
+
+## 2.4.4
+
+ * Add `module` type to browser build `<script>` handler.
+ * Fix some `MemberExpression` modifying incorrectly setting `property` to a `MemberExpression`.
+
+## 2.4.3
+
+ * Upgrade `acorn-6to5`.
+ * Add support for `FunctionDeclaration`s in `bluebirdCoroutines` and `asyncToGenerators` transformers.
+
+## 2.4.2
+
+ * Upgrade `acorn-6to5`.
+ * Better uids generated for various transformers based on parent node.
+ * Alias flat references in `coreAliasing` transformer.
+
+## 2.4.1
+
+ * Better whitespace handling of parenthesized expressions due to trailing comments.
+ * Fix `yield` inside of comprehensions.
+
+## 2.4.0
+
+ * Use a closure always for classes with a super.
+ * Always use native loops for array comprehensions.
+ * Allow `yield` inside of comprehensions.
+ * Add optional `bluebirdCoroutine` transformer.
+ * Add optional `asyncToGenerator` transformer.
+ * Move `useStrict` transformer to before `_moduleFormatter` causing `"use strict";` to always be placed the very top.
+
+## 2.3.2
+
+ * Add parens on expressions with trailing comments.
+
+## 2.3.1
+
+ * Add `undefinedToVoid` optional transformer.
+ * Use `Object.defineProperty` for computed properties.
+
+## 2.3.0
+
+ * Upgrade `acorn-6to5`.
+ * Support circular references and hoist variable declarations in `system` module formatter.
+ * Add optional transformers, including a new `coreAliasing` transformer that aliases native ES6 static properties to their `core-js` equivalent.
+
+## 2.2.0
+
+ * Make `system` module formatter modules anonymous by default.
+ * Fix duplicate comments being output, breaking code.
+
+## 2.1.0
+
+ * Add `cache` option to register hook.
+ * Update `core-js`.
+ * Fix starting newline not being added on case statements.
+ * Fix destructuring `VariableDeclaration`s not inside `BlockStatement`s and `Program`.
+
+## 2.0.4
+
+ * Avoid being greedy when destructuring array iterables.
+
+## 2.0.3
+
+ * Hoist function declarations in system module formatter for circular references.
+ * Hoist default function declarations in umd and amd module formatters for circular references.
+
+## 2.0.2
+
+ * Inherit comments in `for-of` transformer.
+ * Remove `interopRequire` from `system` module formatter.
+
+## 2.0.1
+
+ * Remap `UpdateExpression` module export binding.
+ * Fix automatic closure on `PrivateDeclaration` in classes.
+
+## 2.0.0
+
+ * Make string literal generation only escapes unicode that it has to.
+ * Internal code generation format options have been exposed.
+ * Change playground method binding operator from `:` to `#` removing ambiguous syntax with terns.
+ * Fix rest parameters in async and generator functions.
+ * Export/import declarations replace by the modules transformer now inherit comments.
+ * Added playground flag to `6to5-node`.
+ * `6to5-node` now behaves the same as `node`.
+ * `6to5-node` now uses `kexec` to become the forked process to correctly propagate signals on unix.
+ * Constants are now block scoped.
+ * Exposed ast transformer.
+ * Merged `commonInterop` and `common` module formatters.
+ * Fix generator comprehensions not inheriting `arguments`, `this` etc.
+ * Object and class mutator shorthand are now enumerable.
+ * Remove regenerator `Generator has already finished` error which isn't spec-compliant.
+ * Expose internal `spec` transformers that nicen up code output.
+ * Add export variable declaration default initializers.
+ * Propagate export declaration reassignments.
+ * Add initializer default to block scoped variable declarations within a loop.
+ * Flow type support.
+ * Make async/await contextual keywords.
+ * Allow `yield`ing of non-objects.
+ * Class declarations now lack an IIFE.
+ * Support falsy and `null` super classes.
+ * Add support for experimental abstract references `private` declarations.
+ * Leave out IIFE for class declarations.
+ * Switched to [core-js](https://github.com/zloirock/core-js) from [es6-symbol](https://github.com/medikoo/es6-symbol) and [es6-shim](https://github.com/paulmillr/es6-shim/) for built-in polyfill.
+ * `amd` and `umd` module formatters now behave the same as `common` with `interopRequire`.
+ * Micro-optimizations to boost performance by 200%.
+ * Rename module formatter methods `import` to `importDeclaration` and `export` to `exportDeclaration`.
+ * Support multiple declarators in export variable declarations.
+ * Freeze tagged template literal object.
+ * Remove inlined `regenerator` fork.
+ * Remove `ParenthesizedExpression`.
+ * Rename `object-spread` helper to `object-without-properties`.
+ * Rename `class-props` helper to `prototype-properties`.
+ * Rename `extends` helper to `inherits`.
+ * Completely rewritten `system` module formatter.
+
+## 1.15.0
+
+ * Don't alias `GeneratorFunction` and check the name which causes minifiers to remove the name and throw an error later on when we check if it's set.
+
+## 1.14.18
+
+ * Fix files only containg comments not being output.
+ * Fix duplicate comments on property key shorthands.
+
+## 1.14.17
+
+ * Add default initializer to let variables within loop bodies.
+ * Fix excessive `break` replacement inside of switches in let scoping.
+
+## 1.14.16
+
+ * Add object getter memos and this shorthand to playground.
+ * Fix while loops in let scoping.
+ * Upgrade `acorn-6to5`.
+
+## 1.14.14
+
+ * Fix template literals escaping.
+
+## 1.14.13
+
+ * Fix let scoping of `while` loops.
+ * Make class methods enumerable.
+
+## 1.14.12
+
+ * Fix duplicate dynamic expressions in call spread.
+
+## 1.14.10
+
+ * Fix let scoping unneccesary override.
+
+## 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.
+ * Add `commonInterop` module formatter. Thanks [@Naddiseo](https://github.com/Naddiseo).
+ * Fix `return` outside of function body bug. Thanks [@brentburg](https://github.com/brentburg).
+ * Add more flexible option types.
+
+## 1.12.20
+
+ * Append `sourceMappingURL` when using `bin/6to5` and output sourcemaps.
+
+## 1.12.19
+
+ * Add `comments` option and `--remove-comments` flag. Thanks [@webpro](htps://github.com/webpro).
+ * Embed `regenerator`.
+
+## 1.12.18
+
+ * Use `global` reference instead of `window`.
+
+## 1.12.17
+
+ * Add `moduleName`, `sourceRoot` and `filenameRelative` options. Thanks [@darvelo](https://github.com/darvelo).
+ * Traversal optimisations.
+
+## 1.12.16
+
+ * Fix comments not being retained from `MethodDefinition` in classes.
+ * Add temporal dead zone in default parameters.
+
+## 1.12.15
+
+ * Update `acorn-6to5`.
+
+## 1.12.14
+
+ * Fix duplicate let scoping in functions.
+ * Make JSX whitespace more React-compliant.
+ * Add `_memberExpressionKeywords` transformer that turns keyword identifiers to computed literals.
+ * Upgrade `regenerator-6to5`.
+
+## 1.12.13
+
+ * Support duplicate constants within different block scopes.
+ * Fix for-head duplication testing and replacement.
+ * Support `raw` property on tagged template literals.
+
+## 1.12.12
+
+ * Make scope tracker more reliable to handle all edgecases.
+
+## 1.12.11
+
+ * Block scope classes.
+ * Fix generation of integer `Literal`s in `MemberExpression`.
+
+## 1.12.10
+
+ * Fix let scoping var hoisting.
+
+## 1.12.9
+
+ * Escape unicode characters when generating string `Literal`s.
+ * Fix semicolons being output for statements in `ExportDeclaration`.
+ * Fix `WithStatement` missing parenthesis.
+
+## 1.12.8
+
+ * Temporarily forbid `AssignmentExpression` destructuring outside of `ExpressionStatement`.
+
+## 1.12.7
+
+ * Update to latest `acorn-6to5`.
+
+## 1.12.6
+
+ * Update to latest `acorn-6to5`.
+
+## 1.12.5
+
+ * Fix excessive whitespace trimming resulting in innaccurate sourcemap line.
+
+## 1.12.4
+
+ * Add `doc` folder for documentation.
+
+## 1.12.3
+
+ * Support generator comprehensions.
+ * Use `Array.from` instead of `Array.prototype.slice` in spread transformer.
+ * Support spread in `NewExpression`s.
+
+## 1.12.2
+
+ * Upgrade `matcha` to `0.6.0` and `browserify` to `6.3.2`.
+ * Add own `trimRight` helper instead of relying on the string instance method.
+ * Support JSX spreads that aren't the first.
+
+## 1.12.1
+
+ * Fix `this` and `arguments` mapping in the `_aliasFunctions` transformer.
+
+## 1.12.0
+
+ * Combine `jsx` and `react` transformers to `react`.
+ * Update `react` syntax output to React v0.12.
+
+## 1.11.15
+
+ * Fix JSX literal whitespace generation.
+
+## 1.11.14
+
+ * Avoid using a switch for let-scoping continue and break statements and use an if statement instead.
+ * Remove excess whitespace and newlines from JSX literals.
+
+## 1.11.13
+
+ * Update regenerator-6to5
+ * Add support for most escodegen formatting options

CODE_OF_CONDUCT.md

@@ -0,0 +1,13 @@
+# Contributor Code of Conduct
+
+As contributors and maintainers of this project, we pledge to respect all people who contribute through reporting issues, posting feature requests, updating documentation, submitting pull requests or patches, and other activities.
+
+We are committed to making participation in this project a harassment-free experience for everyone, regardless of level of experience, gender, gender identity and expression, sexual orientation, disability, personal appearance, body size, race, age, or religion.
+
+Examples of unacceptable behavior by participants include the use of sexual language or imagery, derogatory comments or personal attacks, trolling, public or private harassment, insults, or other unprofessional conduct.
+
+Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct. Project maintainers who do not follow the Code of Conduct may be removed from the project team.
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by opening an issue or contacting one or more of the project maintainers.
+
+This Code of Conduct is adapted from the [Contributor Covenant](http://contributor-covenant.org), version 1.0.0, available at [http://contributor-covenant.org/version/1/0/0/](http://contributor-covenant.org/version/1/0/0/)

CONTRIBUTING.md

@@ -0,0 +1,46 @@
+# Contributing
+
+Contributions are always welcome, no matter how large or small. Before contributing, please read the [code of conduct](https://github.com/6to5/6to5/blob/master/CODE_OF_CONDUCT.md).
+
+## Developing
+
+#### Workflow
+
+* Fork the repository
+* Clone your fork and change directory to it (`git clone git@github.com:yourUserName/6to5.git && cd 6to5`)
+* Install the project dependencies (`make bootstrap`)
+* Link your forked clone (`npm link`)
+* Develop your changes ensuring you're fetching updates from upstream often
+* Ensure the test are passing (`make test`)
+* Create new pull request explaining your proposed change or reference an issue in your commit message
+
+#### Code Standards
+
+ * **General**
+   * No ES6 syntax features or methods, exclusively ES5.
+   * Max of five arguments for functions
+   * Max depth of four nested blocks
+   * 2-spaced soft tabs
+ * **Naming**
+   * CamelCase all class names
+   * camelBack all variable names
+ * **Spacing**
+   * Spaces after all keywords
+   * Spaces before all left curly braces
+ * **Comments**
+   * Use JSDoc-style comments for methods
+   * Single-line comments for ambiguous code
+ * **Quotes**
+   * Always use double quotes
+   * Only use single quotes when the string contains a double quote
+ * **Declaration**
+   * No unused variables
+   * No pollution of global variables and prototypes
+
+## Testing
+
+    $ make test
+
+## Linting
+
+    $ make lint

FEATURES.md

@@ -1,162 +0,0 @@
-# Features
-
-## Array comprehension
-
-```javascript
-[for (i of [1, 2, 3]) i * i]; // [1, 4, 9]
-```
-
-## Arrow functions
-
-```javascript
-arr.map(x => x * x);
-```
-
-## Let scoping
-
-```javascript
-for (let i in arr) {
-  let v = arr[i];
-}
-```
-
-## Classes
-
-```javascript
-class Foo extends Bar {
-  constructor() { }
-
-  foo() { }
-
-  get bar() { }
-
-  set bar() { }
-}
-```
-
-## Computed property names
-
-```javascript
-var foo = "foo";
-var bar = "bar";
-var obj = {
-  ["foo" + bar]: "heh",
-  ["bar" + foo]: "noo",
-  foo: "foo",
-  bar: "bar"
-};
-```
-
-## Constants
-
-```javascript
-const MULTIPLIER = 5;
-console.log(2 * MULTIPLIER);
-
-MULTIPLIER = 6; // error
-var MULTIPLIER; // error
-```
-
-## Default parameters
-
-```javascript
-function foo(bar = "foo") {
-  return bar + "bar";
-}
-```
-
-## Destructuring
-
-```javascript
-var [a, [b], c, d] = ["hello", [", ", "junk"], ["world"]];
-console.log(a + b + c); // hello, world
-```
-
-## For-of
-
-```javascript
-for (var i of [1, 2, 3]) {
-  console.log(i * i);
-}
-```
-
-## Generators
-
-```javascript
-```
-
-## Modules
-
-```javascript
-```
-
-## Numeric literals
-
-```javascript
-0b111110111 === 503; // true
-0o767 === 503; // true
-```
-
-## Property method assignment
-
-```javascript
-var obj = {
-  foo() {
-    return "foobar";
-  },
-
-  get bar() {
-    return this._bar;
-  },
-
-  set bar(val) {
-    this._bar = val;
-  }
-};
-```
-
-## Property name shorthand
-
-```javascript
-function f(x, y) {
-  return { x, y };
-}
-```
-
-## Rest parameters
-
-```javascript
-function printList(name, ...items) {
-  console.log("list %s has the following items", name);
-  items.forEach(function (item) {
-    console.log(item);
-  });
-}
-```
-
-## Spread
-
-```javascript
-function add(x, y) {
-  return x + y;
-}
-
-var numbers = [5, 10];
-add(...numbers); // 15
-```
-
-## Template literals
-
-```javascript
-var x = 5;
-var y = 10;
-console.log(`${x} + ${y} = ${x + y}`); // "5 + 10 = 15"
-```
-
-## Unicode regex
-
-```javascript
-var string = 'foo💩bar';
-var match = string.match(/foo(.)bar/u);
-console.log(match[1]);
-```

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2014 Sebastian McKenzie
+Copyright (c) 2014-2015 Sebastian McKenzie
 
 MIT License
 

MODULES.md

@@ -1,145 +0,0 @@
-# Modules
-
-## Usage
-
-### CLI
-
-    $ 6to5 --modules common script.js
-
-### Node
-
-```javascript
-var to5 = require("6to5");
-to5.transform('import "foo";', { modules: "common" });
-```
-
-## Formats
-
-### Common (Default)
-
-**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
-require("foo");
-
-var foo = require("foo").default;
-var foo = require("foo");
-
-var bar = require("foo").bar;
-var bar = require("foo").foo;
-
-exports.test = test;
-var test = 5; exports.test = test;
-
-exports.default = test;
-```
-
-### AMD
-
-**In**
-
-```javascript
-import foo from "foo";
-
-export function bar() {
-  return foo("foobar");
-}
-```
-
-**Out**
-
-```javascript
-define(["exports", "foo"], function (exports, _foo) {
-  exports.bar = bar;
-
-  var foo = _foo.default;
-
-  function bar() {
-    return foo("foobar");
-  }
-});
-```
-
-### UMD
-
-**In**
-
-```javascript
-import foo from "foo";
-
-export function bar() {
-  return foo("foobar");
-}
-```
-
-**Out**
-
-```javascript
-(function (factory) {
-  if (typeof define === "function" && define.amd) {
-    define(["exports", "foo"], factory);
-  } else if (typeof exports !== "undefined") {
-    factory(exports, require("foo"));
-  }
-})(function (exports) {
-  exports.bar = bar;
-
-  var foo = _foo.default;
-
-  function bar() {
-    return foo("foobar");
-  }
-});
-```
-
-## Custom
-
-You can alternatively specify module names instead of one of the built-in types.
-
-```javascript
-module.exports = ModuleFormatter;
-
-function ModuleFormatter() {
-
-}
-
-ModuleFormatter.prototype.transform = function (ast) {
-  // this is ran after all transformers have had their turn at modifying the ast
-  // feel free to modify this however
-};
-
-ModuleFormatter.prototype.import = function (node, nodes) {
-  // node is an ImportDeclaration
-};
-
-ModuleFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
-  // specifier is an ImportSpecifier
-  // node is an ImportDeclaration
-};
-
-ModuleFormatter.prototype.export = function (node, nodes) {
-  // node is an ExportDeclaration
-};
-
-ModuleFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
-  // specifier is an ExportSpecifier
-  // node is an ExportDeclaration
-};
-```

Makefile

@@ -1,60 +1,112 @@
+BROWSERIFY_CMD = node_modules/browserify/bin/cmd.js
 ISTANBUL_CMD = node_modules/istanbul/lib/cli.js cover
+UGLIFY_CMD = node_modules/uglify-js/bin/uglifyjs
+#UGLIFY_CMD = node_modules/uglify-js/bin/uglifyjs --mangle sort
 JSHINT_CMD = node_modules/jshint/bin/jshint
 MOCHA_CMD = node_modules/mocha/bin/_mocha
+JSCS_CMD = node_modules/jscs/bin/jscs
 
 export NODE_ENV = test
 
-.PHONY: clean test test-cov test-travis test-browser publish bench build
-
-clean:
-	rm -rf coverage templates.json test/tmp dist
-
-bench:
-	npm install es6-transpiler traceur esnext es6now jstransform
-	node node_modules/matcha/bin/_matcha
-
-test:
-	$(JSHINT_CMD) lib bin benchmark/index.js
-	$(MOCHA_CMD)
-
-test-cov:
-	rm -rf coverage
-	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
-
-test-travis:
-	node $(ISTANBUL_CMD) $(MOCHA_CMD) -- --reporter spec
-	if test -n "$$CODECLIMATE_REPO_TOKEN"; then codeclimate < coverage/lcov.info; fi
-
-test-browser:
-	make build
-	node bin/generate-browser-test >dist/6to5-test.js
-	test -n "`which open`" && open test/browser.html
+.PHONY: clean test test-cov test-clean lint test-travis test-simple test-all test-browser publish build bootstrap publish-core publish-runtime
 
 build:
 	mkdir -p dist
 
-	node bin/cache-templates
+	node tools/cache-templates
 
-	browserify lib/6to5/browser.js -s to5 >dist/6to5.js
-	uglifyjs dist/6to5.js >dist/6to5.min.js
+	node $(BROWSERIFY_CMD) -e lib/6to5/polyfill.js >dist/polyfill.js
+	node $(UGLIFY_CMD) dist/polyfill.js >dist/polyfill.min.js
+
+	node $(BROWSERIFY_CMD) lib/6to5/browser.js -s to5 >dist/6to5.js
+	node $(UGLIFY_CMD) dist/6to5.js >dist/6to5.min.js
 
 	rm -rf templates.json
 
+clean:
+	rm -rf coverage templates.json test/tmp dist
+
+lint:
+	$(JSHINT_CMD) --reporter node_modules/jshint-stylish/stylish.js lib bin
+	$(JSCS_CMD) lib bin
+
+test-clean:
+	rm -rf test/tmp
+
+test: lint
+	$(MOCHA_CMD)
+	make test-clean
+
+test-simple:
+	# excludes test262
+	export SIMPLE_6TO5_TESTS=1; \
+	make test
+
+test-all:
+	# includes traceur, esnext, regenerator
+	export ALL_6TO5_TESTS=1; \
+	make test
+
+test-cov:
+	rm -rf coverage
+	export SIMPLE_6TO5_TESTS=1; \
+	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
+
+test-travis: bootstrap
+	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
+	if test -n "$$CODECLIMATE_REPO_TOKEN"; then codeclimate < coverage/lcov.info; fi
+
+test-browser:
+	mkdir -p dist
+
+	node tools/cache-templates
+	node tools/cache-tests
+	node $(BROWSERIFY_CMD) -e test/_browser.js >dist/6to5-test.js
+	rm -rf templates.json tests.json
+
+	test -n "`which open`" && open test/browser.html
+
 publish:
 	git pull --rebase
 
 	make test
 
-	make build
-	cp dist/6to5.js browser.js
+	read -p "Version: " version; \
+	npm version $$version --message "v%s"
 
-	node bin/cache-templates
+	make build
+	cp dist/6to5.min.js browser.js
+	cp dist/polyfill.min.js browser-polyfill.js
+
+	node tools/cache-templates
 	test -f templates.json
 
-	read -p "Version: "  version; \
-  npm version $$version --message "v%s"
 	npm publish
 
 	git push --follow-tags
 
-	rm -rf templates.json browser.js
+	make publish-core
+	make publish-runtime
+
+	rm -rf templates.json browser.js browser-polyfill.js
+
+publish-runtime:
+	cd packages; \
+	node build-runtime.js; \
+	cd 6to5-runtime; \
+	npm publish
+
+publish-core:
+	tools/generate-core-package-json >package2.json
+	mv package.json .package.json
+	mv package2.json package.json
+
+	npm publish
+
+	rm -rf package.json
+	mv .package.json package.json
+
+bootstrap:
+	npm install
+	git submodule update --init
+	cd vendor/regenerator; npm install

NOTES.md

@@ -0,0 +1,3 @@
+# Notes
+
+ * Wildcard exports/imports wont normalise if `export default` is a non-object. See [#224](https://github.com/6to5/6to5/issues/224).

README.md

@@ -1,385 +1,12 @@
 <p align="center">
-  <img alt="6to5" src="http://i.imgur.com/hVl9KRw.png">
+  <img alt="6to5" src="https://raw.githubusercontent.com/6to5/logo/master/logo.png" width="546">
 </p>
 
 <p align="center">
-  <a href="https://travis-ci.org/sebmck/6to5">
-    <img alt="Travis Status" src="http://img.shields.io/travis/sebmck/6to5.svg?style=flat&amp;label=travis">
-  </a>
-
-  <a href="https://codeclimate.com/github/sebmck/6to5">
-    <img alt="Code Climate Score" src="http://img.shields.io/codeclimate/github/sebmck/6to5.svg?style=flat">
-  </a>
-
-  <a href="https://codeclimate.com/github/sebmck/6to5">
-    <img alt="Coverage" src="http://img.shields.io/codeclimate/coverage/github/sebmck/6to5.svg?style=flat">
-  </a>
-
-  <a href="https://david-dm.org/sebmck/6to5">
-    <img alt="Dependency Status" src="http://img.shields.io/david/sebmck/6to5.svg?style=flat">
-  </a>
+  <strong>6to5</strong> turns ES6+ code into vanilla ES5, so you can use next generation features <strong>today.</strong>
 </p>
 
-**6to5** turns ES6 code into vanilla ES5, so you can use ES6 features **today.**
-
- - **Readable** - formatting is retained if possible so your generated code is as similar as possible.
- - **Extensible** - with a large range of [plugins](#plugins) 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**[\*](#generators).
-
-## Installation
-
-It's as easy as:
-
-    $ npm install -g 6to5
-
-## Table of Contents
-
-- [Features](#features)
-- [Usage](#usage)
-  - [Plugins](#plugins)
-  - [CLI](#cli)
-  - [Node](#node-1)
-  - [Browser](#browser)
-- [Modules](#modules)
-- [Caveats](#caveats)
-- [Differences](#differences)
-
-## [Features](FEATURES.md)
-
- - [Array comprehension](FEATURES.md#array-comprehension)
- - [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)
- - [For-of](FEATURES.md#for-of)
- - [Generators](FEATURES.md#generators) via [regenerator](https://github.com/facebook/regenerator)
- - [Let scoping](FEATURES.md#let-scoping)
- - [Modules](FEATURES.md#modules)
- - [Numeric literals](FEATURES.md#numeric-literals)
- - [Property method assignment](FEATURES.md#property-method-assignment)
- - [Property name shorthand](FEATURES.md#property-name-shorthand)
- - [Rest parameters](FEATURES.md#rest-parameters)
- - [Spread](FEATURES.md#spread)
- - [Template literals](FEATURES.md#template-literals)
- - [Unicode regex](FEATURES.md#unicode-regex)
-
-## Usage
-
-### Plugins
-
- - [Broccoli](https://github.com/very-geek/broccoli-6to5-transpiler)
- - [Browserify](https://github.com/sebmck/6to5-browserify)
- - [Brunch](https://github.com/es128/6to5-brunch)
- - [Connect](https://github.com/sebmck/6to5-connect)
- - [Gulp](https://github.com/sindresorhus/gulp-6to5)
- - [Grunt](https://github.com/sindresorhus/grunt-6to5)
- - [Jade](https://github.com/Apoxx/jade-6to5)
- - [webpack](https://github.com/Couto/6to5-loader)
-
-### CLI
-
-Compile the file `script.js` and output it to stdout.
-
-    $ 6to5 script.js
-
-Compile the file `script.js` and output it to `script-compiled.js`.
-
-    $ 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
-
-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
-
-Compile the entire `src` directory and output it to the `lib` directory.
-
-    $ 6to5 src --out-dir lib
-
-Pipe a file in via stdin and output it to `script-compiled.js`
-
-    $ 6to5 --out-file script-compiled.js < script.js
-
-#### Node
-
-Launch a repl.
-
-    $ 6to5-node
-
-Evaluate code.
-
-    $ 6to5-node -e "class Test { }"
-
-Compile and run `test.js`.
-
-    $ 6to5-node test
-
-### Node
-
-```javascript
-var to5 = require("6to5");
-
-var result = to5.transform("code();", options);
-result.code;
-result.map;
-result.ast;
-
-to5.transformFileSync("filename.js", options).code;
-
-to5.transformFile("filename.js", options, function (err, result) {
-
-});
-```
-
-##### Options
-
-```javascript
-{
-  // Filename for use in errors etc.
-  // Default: "unknown"
-  filename: "filename",
-
-  // List of transformers to EXCLUDE.
-  // Run `6to5 --help` to see a full list of transformers.
-  blacklist: [],
-
-  // List of transformers to ONLY use.
-  // Run `6to5 --help` to see a full list of transformers.
-  whitelist: [],
-
-  // Module formatter to use
-  // Run `6to5 --help` to see a full list of module formatters.
-  // Default: "common"
-  modules: "common",
-
-  // If truthy, adds a `map` property to returned output.
-  // If set to "inline", a comment with a sourceMappingURL directive is added to
-  // the bottom of the returned code.
-  // Default: false
-  sourceMap: true,
-
-  // Set `file` on returned source map.
-  // Default: `filename` option.
-  sourceMapName: "filename",
-
-  // Set `sources[0]` on returned source map.
-  // Default: `filename` option.
-  sourceFileName: "filename"
-}
-```
-
-#### Require hook
-
-All subsequent files required by node with the extensions `.es6` and `.js` will
-be transformed by 6to5. The polyfill specified in [Polyfill](#polyfill) is also
-required.
-
-```javascript
-require("6to5/register");
-```
-
-**NOTE:** By default all requires to `node_modules` will be ignored. You can
-override this by passing an ignore regex via:
-
-```javascript
-require("6to5/register")(/regex/);
-```
-
-You can also customise the file extensions that the require hook will use via:
-
-```javascript
-require("6to5/register")({
-  // optional ignore regex
-  ignoreRegex: /regex/,
-
-  // this will remove the currently hooked extensions of .es6 and .js so you'll
-  // have to add them back if you want them to be used again
-  extensions: [".js", ".es6"]
-});
-```
-
-### Browser
-
-You can build a browser version of the compiler by running the following in the
-6to5 directory:
-
-    $ make build
-
-This will output the files `dist/6to5.js` and `dist/6to5.min.js`.
-
-Just include one of those in the browser and access the transform method via the
-global `to5`.
-
-```javascript
-to5("class Test {}").code;
-```
-
-#### Test
-
-To test 6to5 in your browser run:
-
-    $ make test-browser
-
-And open `test/browser.html` in your browser if it doesn't open automatically.
-
-## [Modules](MODULES.md)
-
-See [Modules - Common](MODULES.md#common-default) for documentation on the
-default module formatting.
-
-Alternatively see [Modules](MODULES.md) for all other supported module formatting types.
-
-## Caveats
-
-### Polyfill
-
-6to5 does not include a runtime nor polyfill and it's up to the developer to
-include one in compiled browser code.
-
-#### Node
-
-A polyfill is included with the 6to5 module that can be included in node like
-so:
-
-```javascript
-require("6to5/polyfill");
-```
-
-This is simply a wrapper around the
-[regenerator runtime](https://github.com/facebook/regenerator/blob/master/runtime.js) and the
-[es6-shim](https://github.com/paulmillr/es6-shim) and
-[es6-symbol](https://github.com/medikoo/es6-symbol) polyfills.
-
-#### Browser
-
-If you're planning on using 6to5 output in the browser then it's up to you
-to include polyfills. [es6-symbol](https://github.com/medikoo/es6-symbol#browser)
-and [es6-shim](https://raw.githubusercontent.com/paulmillr/es6-shim/master/es6-shim.js)
-fill the vast majority of polyfill concerns.
-
-### For-of
-
-A polyfill is required for for-of functionality that implements `Symbol` and
-adds `prototype[Symbol.iterator]` behaviour to built-ins. Using the polyfills
-specified in [polyfill](#polyfill) suffices.
-
-### Classes
-
-Built-in classes such as `Date`, `Array` and `DOM` cannot be subclassed due to
-limitations in ES5 implementations.
-
-If you're inheriting from a class then static properties are inherited from it
-via [\_\_proto\_\_](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto),
-this is widely supported but you may run into problems with much older browsers.
-
-### Generators
-
-The [regenerator runtime](https://github.com/facebook/regenerator/blob/master/runtime.js)
-and an [ES6 polyfill](#polyfill) are required in order for generators to work.
-
-## Differences
-
-### Philosophy
-
-The fundamental concept behind 6to5 is that the generated code must be close as
-possible to the original, retaining all the same formatting and readability.
-
-Many other transpilers are just concerned with making the code work while 6to5
-is concerned with making sure it works **and** is readable at the same time.
-
-For example, given the following array comprehension:
-
-```javascript
-var seattlers = [for (c of customers) if (c.city == "Seattle") { name: c.name, age: c.age }];
-```
-
-is generated to the following with 6to5:
-
-```javascript
-var seattlers = customers.filter(function (c) {
-  return c.city == "Seattle";
-}).map(function (c) {
-  return {
-    name: c.name,
-    age: c.age
-  };
-});
-```
-
-The following is what Traceur generates:
-
-```javascript
-var seattlers = (function() {
-  var c;
-  var $__20 = 0,
-      $__21 = [];
-  for (var $__22 = customers[$traceurRuntime.toProperty(Symbol.iterator)](),
-      $__23; !($__23 = $__22.next()).done; ) {
-    c = $__23.value;
-    if (c.city == "Seattle")
-      $traceurRuntime.setProperty($__21, $__20++, {
-        name: c.name,
-        age: c.age
-      });
-  }
-  return $__21;
-}());
-```
-
-As you can tell, it's not very pretty, unreadable even. Instead of mapping
-directly to a runtime, like other transpilers, 6to5 maps directly to the
-equivalent ES5.
-
-I'm not saying 6to5 is for everyone or even suited for everything. Traceur is
-better suited if you'd like a full ES6 environment with polyfills and all.
-
-### Comparison to other transpilers
-
-|                              | 6to5 | Traceur | esnext | es6now | es6-transpiler | jstransform |
-| ---------------------------- | ---- | ------- | ------ | ------ | -------------- | ----------- |
-| No runtime                   | ✓    |         |        |        | ✓              | ✓           |
-| Source maps                  | ✓    | ✓       | ✓      |        | ✓              | ✓           |
-| No compiler global pollution | ✓    |         | ✓      |        | ✓              | ✓           |
-| Arrow functions              | ✓    | ✓       | ✓      | ✓      | ✓              | ✓           |
-| Classes                      | ✓    | ✓       | ✓      | ✓      | ✓              | ✓           |
-| Computed property names      | ✓    | ✓       | ✓      | ✓      | ✓              |             |
-| Constants                    | ✓    | ✓       |        |        | ✓              |             |
-| Default parameters           | ✓    | ✓       | ✓      | ✓      | ✓              |             |
-| Destructuring                | ✓    | ✓       | ✓      | ✓      | ✓              | ✓           |
-| For-of                       | ✓    | ✓       | ✓      | ✓      | ✓              |             |
-| Generators                   | ✓    | ✓       | ✓      |        |                |             |
-| Let scoping                  | ✓    | ✓       |        |        | ✓              |             |
-| Modules                      | ✓    | ✓       |        | ✓      |                |             |
-| Property method assignment   | ✓    | ✓       | ✓      | ✓      | ✓              | ✓           |
-| Property name shorthand      | ✓    | ✓       | ✓      | ✓      | ✓              | ✓           |
-| Rest parameters              | ✓    | ✓       | ✓      | ✓      | ✓              | ✓           |
-| Spread                       | ✓    | ✓       | ✓      | ✓      | ✓              |             |
-| 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.
-
-#### [es6now](https://github.com/zenparsing/es6now)
-
-es6now doesn't output sourcemaps. This is cited as a positive as line-to-line
-mapping is the goal. This however obviously doesn't retain column mapping
-resulting in the output code not being very pleasant.
-
-#### [es6-transpiler](https://github.com/termi/es6-transpiler)
-
-The es6-transpiler compiler requires shims to operate which pollutes the global
-scope resulting in possible collisions.
-
-es6-transpiler maps line-by-line, just like es6now, this results in the same
-issues such as lack of column information and unpleasant code output.
+<p align="center">
+  For more information view the <a href="https://6to5.github.io">documentation</a>. For
+  support visit the <a href="https://gitter.im/6to5/6to5">gitter room</a>.
+</p>

appveyor.yml

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

benchmark/fixtures/all.js

@@ -1,99 +0,0 @@
-var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-var obj = {};
-var foo = "foo";
-var bar = "bar";
-
-// constants
-const MULTIPLIER = 5;
-
-// classes
-class Foo {
-  constructor() {
-    this.foo = "bar";
-  }
-}
-
-class Bar extends Foo {
-  constructor() {
-    super();
-  }
-
-  // default parameters
-  go(foo = "bar", bar = "foo") {
-
-  }
-
-  // not supported by jstransform
-  //get foo() {
-  //  return this._foo;
-  //}
-  //set foo(val) {
-  //  this._foo = val + " foo!";
-  //}
-}
-
-// arrow functions
-arr.map(x => x * x);
-
-// block binding
-for (let key in arr) {
-  let val = arr[key];
-  console.log(key, val);
-}
-
-// computed property names
-obj = {
-  ["foo" + bar]: "foobar"
-};
-
-// destructuring
-var [a, [b], c, d] = ["hello", [", ", "junk"], ["world"]];
-console.log(a + b + c);
-
-// array comprehension
-// [for (i of [1, 2, 3]) i * i]; // not supported by es6now
-
-// for-of
-for (var i of [1, 2, 3]) {
-  console.log(i * i);
-}
-
-// property method assignment
-obj = {
-  foo() {
-    return "foobar";
-  },
-
-  get bar() {
-    return this._bar;
-  },
-
-  set bar(val) {
-    this._bar = val;
-  }
-};
-
-// property name shorthand
-function f(x, y) {
-  return { x, y };
-}
-
-// rest parameters
-function printList(name, ...items) {
-  console.log("list %s has the following items", name);
-  items.forEach(function (item) {
-    console.log(item);
-  });
-}
-
-// spread
-function add(x, y) {
-  return x + y;
-}
-var numbers = [5, 10];
-add(...numbers);
-
-// template literals
-var x = 5;
-var y = 10;
-console.log(`${x} + ${y} = ${x + y}`);

benchmark/index.js

@@ -1,168 +0,0 @@
-Error.stackTraceLimit = Infinity;
-
-var jsTrans = require("jstransform");
-var traceur = require("traceur");
-var es6tr   = require("es6-transpiler");
-var es6now  = require("es6now");
-var esnext  = require("esnext");
-var to5     = require("../lib/6to5");
-
-//var uglify  = require("uglify-js");
-var matcha  = require("matcha");
-var path    = require("path");
-var fs      = require("fs");
-var _       = require("lodash");
-
-var readResolve = function (filename) {
-  try {
-    filename = require.resolve(filename);
-  } catch (err) {
-    return null;
-  }
-  return fs.readFileSync(filename, "utf8");
-};
-
-var getVersion = function (name) {
-  return require(name + "/package.json").version;
-};
-
-var jsTransVisitors = [];
-
-_.each([
-  "arrow-function-visitors", "class-visitors", "destructuring-visitors",
-  "object-concise-method-visitors", "object-short-notation-visitors",
-  "rest-param-visitors", "template-visitors"
-], function (name) {
-  var mod = require("jstransform/visitors/es6-" + name);
-  jsTransVisitors = jsTransVisitors.concat(mod.visitorList);
-});
-
-
-var compilers = {
-  "6to5": {
-    version: getVersion(".."),
-    compile: function (code, filename) {
-      return to5.transform(code, { filename: filename }).code;
-    }
-  },
-
-  traceur: {
-    runtime: readResolve("traceur/bin/traceur-runtime.js"),
-    compile: function (code) {
-      return traceur.compile(code, {
-        modules: "commonjs",
-        experimental: true
-      });
-    }
-  },
-
-  esnext: {
-    runtime: readResolve("esnext/node_modules/regenerator/runtime.js") || readResolve("regenerator/runtime.js"),
-    compile: function (code) {
-      return esnext.compile(code).code;
-    }
-  },
-
-  es6now: {
-    runtime: readResolve("es6now/runtime/ES6.js"),
-    compile: function (code) {
-      return es6now.translate(code);
-    }
-  },
-
-  "es6-transpiler": {
-    compile: function (code) {
-      var result = es6tr.run({ src: code });
-      if (result.errors.length) throw new Error(result.join("; "));
-      return result.src;
-    }
-  },
-
-  jstransform: {
-    compile: function (code) {
-      return jsTrans.transform(jsTransVisitors, code).code;
-    }
-  }
-};
-
-// versions
-
-//var uglifyTitle = "uglify v" + getVersion("uglify-js");
-
-_.each(compilers, function (compiler, name) {
-  compiler.title = name + " v" + (compiler.version || getVersion(name));
-});
-
-//
-
-var sizeBenchmark = function (code, loc, name, compiler) {
-  var log = function (output, title) {
-    title = [compiler.title].concat(title || []).join(" + ");
-
-    var text;
-    var color;
-    if (output.stack) {
-      text = "error";
-      color = "red";
-    } else {
-      var kilo  = (output.length / 1024).toFixed(2);
-      text = kilo + "KB";
-      color = "cyan";
-    }
-
-    text = matcha.utils.color(matcha.utils.padBefore(text, 22), color);
-
-    console.log(text, matcha.utils.color("» " + title, "gray"));
-
-    if (output.stack) {
-      console.error(output.stack);
-    }
-  };
-
-  var go = function (getOutput, title) {
-    var code;
-    try {
-      code = getOutput();
-    } catch (err) {
-      log(err, title);
-      return;
-    }
-
-    log(code, title);
-  };
-
-  var output;
-  go(function () {
-    return output = compiler.compile(code, loc);
-  });
-  if (!output) return;
-
-  //go(function () {
-  //  return uglify.minify(output, { fromString: true }).code;
-  //}, uglifyTitle);
-};
-
-//
-
-_.each(fs.readdirSync(__dirname + "/fixtures"), function (name) {
-  var alias = path.basename(name, path.extname(name));
-
-  suite(alias, function () {
-    set("delay", 0);
-
-    var loc  = __dirname + "/fixtures/" + name;
-    var code = fs.readFileSync(loc, "utf8");
-
-    before(function () {
-      _.each(compilers, function (compiler, name) {
-        sizeBenchmark(code, loc, name, compiler);
-      });
-    });
-
-    _.each(compilers, function (compiler) {
-      bench(compiler.title, function () {
-        compiler.compile(code, loc);
-      });
-    });
-  });
-});

bin/6to5-node

@@ -1,83 +1,68 @@
 #!/usr/bin/env node
 
-var commander = require("commander");
-var util      = require("../lib/6to5/util");
-var path      = require("path");
-var repl      = require("repl");
-var to5       = require("../lib/6to5");
-var vm        = require("vm");
-var _         = require("lodash");
+/**
+ * This tiny wrapper file checks for known node flags and appends them
+ * when found, before invoking the "real" _6to5-node(1) executable.
+ */
 
-commander.option("-e, --eval [script]", "evaluate script");
-commander.option("-p, --print", "evaluate script and print result");
-commander.option("-i, --ignore [regex]", "ignore all files that match this regex when using the require hook");
-commander.option("-x, --extensions [extensions]", "list of extensions to hook into [.es6,.js]", util.list);
+var args  = ["--harmony", __dirname + "/_6to5-node"];
 
-var pkg = require("../package.json");
-commander.version(pkg.version);
-commander.usage("[options] [ -e script | script.js ] [arguments]");
-commander.parse(process.argv);
+process.argv.slice(2).forEach(function(arg){
+  var flag = arg.split("=")[0];
 
-//
+  switch (flag) {
+    case "-d":
+      args.unshift("--debug");
+      break;
 
-var registerOpts = {};
+    case "debug":
+    case "--debug":
+    case "--debug-brk":
+      args.unshift(arg);
+      break;
 
-if (commander.ignore) {
-  registerOpts.ignoreRegex = new RegExp(commander.ignore);
-}
+    case "-gc":
+    case "--expose-gc":
+      args.unshift("--expose-gc");
+      break;
 
-if (commander.extensions && commander.extensions.length) {
-  registerOpts.extensions = commander.extensions
-}
+    case "--gc-global":
+    case "--harmony":
+    case "--harmony-proxies":
+    case "--harmony-collections":
+    case "--harmony-generators":
+    case "--no-deprecation":
+    case "--prof":
+    case "--throw-deprecation":
+    case "--trace-deprecation":
+      args.unshift(arg);
+      break;
 
-to5.register(registerOpts);
-
-//
-
-var _eval = function (code, filename) {
-  code = to5.transform(code, { filename: filename }).code;
-  return vm.runInThisContext(code, filename);
-};
-
-if (commander.eval) {
-  var result = _eval(commander.eval, "eval");
-  if (commander.print) console.log(result);
-} else {
-  var filenames = commander.args;
-
-  if (filenames.length) {
-    _.each(filenames, function (filename) {
-      if (!util.isAbsolute(filename)) {
-        filename = path.join(process.cwd(), filename);
+    default:
+      if (arg.indexOf("--trace") === 0) {
+        args.unshift(arg);
+      } else {
+        args.push(arg);
       }
-
-      require(require.resolve(filename));
-    });
-  } else {
-    replStart();
+      break;
   }
-}
+});
 
-function replStart() {
-  repl.start({
-    prompt: "> ",
-    input: process.stdin,
-    output: process.stdout,
-    eval: replEval,
-    useGlobal: true
+try {
+  var kexec = require("kexec");
+  kexec(process.argv[0], args);
+} catch (err) {
+  if (err.code !== "MODULE_NOT_FOUND") throw err;
+
+  var child_process = require("child_process");
+  var proc = child_process.spawn(process.argv[0], args, { stdio: "inherit" });
+  proc.on("exit", function (code, signal) {
+    process.on("exit", function () {
+      if (signal) {
+        process.kill(process.pid, signal);
+      } else {
+        process.exit(code);
+      }
+    })
   });
 }
-
-function replEval(code, context, filename, callback) {
-  var err;
-  var result;
-
-  try {
-    code = code.slice(1, -2); // remove "(" and "\n)"
-    result = _eval(code, filename);
-  } catch (e) {
-    err = e;
-  }
-
-  callback(err, result);
-}

bin/6to5/dir.js

@@ -1,9 +1,9 @@
-var chokidar = require("chokidar");
-var mkdirp   = require("mkdirp");
-var path     = require("path");
-var util     = require("./util");
-var fs       = require("fs");
-var _        = require("lodash");
+var outputFileSync = require("output-file-sync");
+var chokidar       = require("chokidar");
+var path           = require("path");
+var util           = require("./util");
+var fs             = require("fs");
+var _              = require("lodash");
 
 module.exports = function (commander, filenames, opts) {
   if (commander.sourceMapsInline) {
@@ -15,14 +15,13 @@ module.exports = function (commander, filenames, opts) {
 
     var data = util.compile(src, { sourceMapName: dest });
 
-    var up = path.normalize(dest + "/..");
-    mkdirp.sync(up);
-
     if (commander.sourceMaps) {
-      fs.writeFileSync(dest + ".map", JSON.stringify(data.map));
+      var mapLoc = dest + ".map";
+      data.code = util.addSourceMappingUrl(data.code, mapLoc);
+      outputFileSync(mapLoc, JSON.stringify(data.map));
     }
 
-    fs.writeFileSync(dest, data.code);
+    outputFileSync(dest, data.code);
 
     console.log(src + " -> " + dest);
   };
@@ -52,7 +51,7 @@ module.exports = function (commander, filenames, opts) {
         ignoreInitial: true
       });
 
-      _.each(["add", "change", "unlink"], function (type) {
+      _.each(["add", "change"], function (type) {
         watcher.on(type, function (filename) {
           // chop off the dirname plus the path separator
           var relative = filename.slice(dirname.length + 1);

bin/6to5/file.js

@@ -28,7 +28,7 @@ module.exports = function (commander, filenames) {
         map.setSourceContent(filename, result.actual);
 
         consumer.eachMapping(function (mapping) {
-          map._mappings.push({
+          map._mappings.add({
             generatedLine: mapping.generatedLine + offset,
             generatedColumn: mapping.generatedColumn,
             originalLine: mapping.originalLine,
@@ -56,12 +56,14 @@ module.exports = function (commander, filenames) {
 
     if (commander.outFile) {
       if (commander.sourceMaps) {
-        fs.writeFileSync(commander.outFile + ".map", JSON.stringify(result.map));
+        var mapLoc = commander.outFile + ".map";
+        result.code = util.addSourceMappingUrl(result.code, mapLoc);
+        fs.writeFileSync(mapLoc, JSON.stringify(result.map));
       }
 
       fs.writeFileSync(commander.outFile, result.code);
     } else {
-      console.log(result.code);
+      process.stdout.write(result.code + "\n");
     }
   };
 
@@ -75,7 +77,7 @@ module.exports = function (commander, filenames) {
       if (chunk !== null) code += chunk;
     });
 
-    process.stdin.on("end", function() {
+    process.stdin.on("end", function () {
       results.push(util.transform(commander.filename, code));
       output();
     });
@@ -100,8 +102,8 @@ module.exports = function (commander, filenames) {
       }
     });
 
-    _.each(_filenames, function (filename, i) {
-      results.push(util.compile(filename, { _noStrict: +i !== 0 }));
+    _.each(_filenames, function (filename) {
+      results.push(util.compile(filename));
     });
 
     output();
@@ -111,16 +113,14 @@ module.exports = function (commander, filenames) {
     walk();
 
     if (commander.watch) {
-      var watcher = chokidar.watch(filenames, {
+      chokidar.watch(filenames, {
         persistent: true,
         ignoreInitial: true
-      });
-
-      _.each(["add", "change", "unlink"], function (type) {
-        watcher.on(type, function (filename) {
+      }).on("all", function (type, filename) {
+        if (type === "add" || type === "change") {
           console.log(type, filename);
           walk();
-        });
+        }
       });
     }
   };

bin/6to5/index.js

@@ -1,7 +1,7 @@
 #!/usr/bin/env node
 
 var commander = require("commander");
-var transform = require("../../lib/6to5/transform");
+var transform = require("../../lib/6to5/transformation/transform");
 var util      = require("../../lib/6to5/util");
 var fs        = require("fs");
 var _         = require("lodash");
@@ -10,20 +10,33 @@ commander.option("-t, --source-maps-inline", "Append sourceMappingURL comment to
 commander.option("-s, --source-maps", "Save source map alongside the compiled code");
 commander.option("-f, --filename [filename]", "Filename to use when reading from stdin - this will be used in source-maps, errors etc [stdin]", "stdin");
 commander.option("-w, --watch", "Recompile files on changes");
+commander.option("-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);
+commander.option("-l, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util.list);
 commander.option("-b, --blacklist [blacklist]", "Blacklist of transformers to NOT use", util.list);
+commander.option("-i, --optional [list]", "List of optional transformers to enable", util.list);
+commander.option("-L, --loose [list]", "List of transformers to enable loose mode ON", util.list);
 commander.option("-o, --out-file [out]", "Compile all input files into a single file");
 commander.option("-d, --out-dir [out]", "Compile an input directory of modules into an output directory");
+commander.option("-c, --remove-comments", "Remove comments from the compiled code", false);
+commander.option("-m, --module-ids", "Insert module id in modules", false);
+commander.option("-R, --react-compat", "Makes the react transformer produce pre-v0.12 code");
+commander.option("--keep-module-id-extensions", "Keep extensions when generating module ids", false);
 
-commander.on("--help", function(){
+commander.on("--help", function () {
   var outKeys = function (title, obj) {
     console.log("  " + title + ":");
     console.log();
 
     _.each(_.keys(obj).sort(), function (key) {
       if (key[0] === "_") return;
+
+      if (obj[key].optional) {
+        key = "[" + key + "]";
+      }
+
       console.log("    - " + key);
     });
 
@@ -83,11 +96,19 @@ if (errors.length) {
 //
 
 exports.opts = {
-  sourceMapName: commander.outFile,
-  blacklist:     commander.blacklist,
-  whitelist:     commander.whitelist,
-  sourceMap:     commander.sourceMaps || commander.sourceMapsInline,
-  modules:       commander.modules
+  keepModuleIdExtensions: commander.keepModuleIdExtensions,
+  sourceMapName:          commander.outFile,
+  experimental:           commander.experimental,
+  reactCompat:            commander.reactCompat,
+  playground:             commander.playground,
+  moduleIds:              commander.moduleIds,
+  blacklist:              commander.blacklist,
+  whitelist:              commander.whitelist,
+  sourceMap:              commander.sourceMaps || commander.sourceMapsInline,
+  optional:               commander.optional,
+  comments:               !commander.removeComments,
+  modules:                commander.modules,
+  loose:                  commander.loose
 };
 
 var fn;

bin/6to5/util.js

@@ -1,19 +1,36 @@
 var readdir = require("fs-readdir-recursive");
 var index   = require("./index");
 var util    = require("../../lib/6to5/util");
+var path    = require("path");
 var to5     = require("../../lib/6to5");
 var fs      = require("fs");
 var _       = require("lodash");
 
 exports.readdirFilter = function (filename) {
-  return readdir(filename).filter(util.canCompile);
+  return readdir(filename).filter(function (filename) {
+    return util.canCompile(filename);
+  });
+};
+
+exports.addSourceMappingUrl = function (code, loc) {
+  return code + "\n//# sourceMappingURL=" + path.basename(loc);
 };
 
 exports.transform = function (filename, code, opts) {
   opts = _.extend(opts || {}, index.opts);
   opts.filename = filename;
 
-  var result = to5.transform(code, opts);
+  var result;
+  try {
+    result = to5.transform(code, opts);
+  } catch (e) {
+    if (e instanceof SyntaxError) {
+      console.error("SyntaxError:", e.message);
+      process.exit(1);
+    } else {
+      throw e;
+    }
+  }
   result.filename = filename;
   result.actual = code;
   return result;

bin/_6to5-node

@@ -0,0 +1,110 @@
+#!/usr/bin/env node
+
+var commander = require("commander");
+var Module    = require("module");
+var path      = require("path");
+var repl      = require("repl");
+var to5       = require("../lib/6to5");
+var util      = require("../lib/6to5/util");
+var vm        = require("vm");
+var _         = require("lodash");
+
+var program = new commander.Command("6to5-node");
+
+program.option("-e, --eval [script]", "Evaluate script");
+program.option("-p, --print [code]", "Evaluate script and print result");
+program.option("-i, --ignore [regex]", "Ignore all files that match this regex when using the require hook");
+program.option("-x, --extensions [extensions]", "List of extensions to hook into [.es6,.js,.es,.jsx]");
+program.option("-r, --experimental", "Enable experimental support for proposed ES7 features");
+program.option("-g, --playground", "Enable playground support");
+program.option("-w, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util.list);
+program.option("-b, --blacklist [blacklist]", "Blacklist of transformers to NOT use", util.list);
+
+var pkg = require("../package.json");
+program.version(pkg.version);
+program.usage("[options] [ -e script | script.js ] [arguments]");
+program.parse(process.argv);
+
+//
+
+to5.register({
+  experimental: program.experimental,
+  extensions:   program.extensions,
+  playground:   program.playground,
+  blacklist:    program.blacklist,
+  whitelist:    program.whitelist,
+  ignore:       program.ignore
+});
+
+//
+
+var _eval = function (code, filename) {
+  code = to5.transform(code, {
+    filename: filename,
+    blacklist: ["useStrict"].concat(program.blacklist || []),
+    whitelist: program.whitelist,
+    experimental: program.experimental,
+    playground: program.playground
+  }).code;
+  return vm.runInThisContext(code, filename);
+};
+
+if (program.eval || program.print) {
+  var code = program.eval;
+  if (!code || code === true) code = program.print;
+
+  var result = _eval(code, "eval");
+  if (program.print) console.log(result);
+} else {
+  if (program.args.length) {
+    // slice all arguments up to the first filename since they're 6to5 args that we handle
+    var args = process.argv.slice(2);
+
+    var i = 0;
+    _.each(args, function (arg, i2) {
+      if (arg[0] !== "-") {
+        i = i2;
+        return false;
+      }
+    });
+    args = args.slice(i);
+
+    // make the filename absolute
+    var filename = args[0]
+    if (!util.isAbsolute(filename)) args[0] = path.join(process.cwd(), filename);
+
+    // add back on node and concat the sliced args
+    process.argv = ["node"].concat(args);
+
+    Module.runMain();
+  } else {
+    replStart();
+  }
+}
+
+function replStart() {
+  repl.start({
+    prompt: "> ",
+    input: process.stdin,
+    output: process.stdout,
+    eval: replEval,
+    useGlobal: true
+  });
+}
+
+function replEval(code, context, filename, callback) {
+  var err;
+  var result;
+
+  try {
+    if (code[0] === "(" && code[code.length - 1] === ")") {
+      code = code.slice(1, -1); // remove "(" and ")"
+    }
+
+    result = _eval(code, filename);
+  } catch (e) {
+    err = e;
+  }
+
+  callback(err, result);
+}

bin/generate-browser-test

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

doc/index.md

@@ -0,0 +1 @@
+See [6to5.github.io/docs](https://github.com/6to5/6to5.github.io/tree/master/docs).

lib/6to5/browser.js

@@ -1,3 +1,85 @@
-var transform = require("./transform");
+"use strict";
 
-module.exports = transform;
+var transform = module.exports = require("./transformation/transform");
+
+transform.version = require("../../package").version;
+
+transform.transform = transform;
+
+transform.run = function (code, opts) {
+  opts = opts || {};
+  opts.sourceMap = "inline";
+  return new Function(transform(code, opts).code)();
+};
+
+transform.load = function (url, callback, opts, hold) {
+  opts = opts || {};
+  opts.filename = opts.filename || url;
+
+  var xhr = global.ActiveXObject ? new global.ActiveXObject("Microsoft.XMLHTTP") : new global.XMLHttpRequest();
+  xhr.open("GET", url, true);
+  if ("overrideMimeType" in xhr) xhr.overrideMimeType("text/plain");
+
+  xhr.onreadystatechange = function () {
+    if (xhr.readyState !== 4) return;
+
+    var status = xhr.status;
+    if (status === 0 || status === 200) {
+      var param = [xhr.responseText, opts];
+      if (!hold) transform.run.apply(transform, param);
+      if (callback) callback(param);
+    } else {
+      throw new Error("Could not load " + url);
+    }
+  };
+
+  xhr.send(null);
+};
+
+var runScripts = function () {
+  var scripts = [];
+  var types   = ["text/ecmascript-6", "text/6to5", "module"];
+  var index   = 0;
+
+  var exec = function () {
+    var param = scripts[index];
+    if (param instanceof Array) {
+      transform.run.apply(transform, param);
+      index++;
+      exec();
+    }
+  };
+
+  var run = function (script, i) {
+    var opts = {};
+
+    if (script.src) {
+      transform.load(script.src, function (param) {
+        scripts[i] = param;
+        exec();
+      }, opts, true);
+    } else {
+      opts.filename = "embedded";
+      scripts[i] = [script.innerHTML, opts];
+    }
+  };
+
+  var _scripts = global.document .getElementsByTagName("script");
+
+  for (var i = 0; i < _scripts.length; ++i) {
+    var _script = _scripts[i];
+    if (types.indexOf(_script.type) >= 0) scripts.push(_script);
+  }
+
+  for (i in scripts) {
+    run(scripts[i], i);
+  }
+
+  exec();
+};
+
+if (global.addEventListener) {
+  global.addEventListener("DOMContentLoaded", runScripts, false);
+} else if (global.attachEvent) {
+  global.attachEvent("onload", runScripts);
+}

lib/6to5/file.js

@@ -1,57 +1,212 @@
+"use strict";
+
 module.exports = File;
 
 var SHEBANG_REGEX = /^\#\!.*/;
 
-var transform = require("./transform");
-var recast    = require("acorn-recast");
+var transform = require("./transformation/transform");
+var generate  = require("./generation/generator");
+var clone     = require("./helpers/clone");
+var Scope     = require("./traverse/scope");
 var util      = require("./util");
-var b         = require("acorn-ast-types").builders;
+var t         = require("./types");
 var _         = require("lodash");
 
 function File(opts) {
-  this.opts            = File.normaliseOptions(opts);
-  this.moduleFormatter = this.getModuleFormatter(opts.modules);
+  this.dynamicImportIds = {};
+  this.dynamicImported  = [];
+  this.dynamicImports   = [];
 
-  this.declarations = {};
-  this.uids         = {};
-  this.ast          = {};
+  this.dynamicData      = {};
+  this.data             = {};
+
+  this.lastStatements   = [];
+  this.opts             = File.normaliseOptions(opts);
+  this.ast              = {};
+
+  this.buildTransformers();
 }
 
+File.helpers = [
+  "inherits",
+  "defaults",
+  "prototype-properties",
+  "apply-constructor",
+  "tagged-template-literal",
+  "tagged-template-literal-loose",
+  "interop-require",
+  "to-array",
+  "sliced-to-array",
+  "object-without-properties",
+  "has-own",
+  "slice",
+  "bind",
+  "define-property",
+  "async-to-generator",
+  "interop-require-wildcard",
+  "typeof",
+  "extends",
+  "get"
+];
+
+File.validOptions = [
+  "filename",
+  "filenameRelative",
+  "blacklist",
+  "whitelist",
+  "loose",
+  "optional",
+  "modules",
+  "sourceMap",
+  "sourceMapName",
+  "sourceFileName",
+  "sourceRoot",
+  "moduleRoot",
+  "moduleIds",
+  "comments",
+  "reactCompat",
+  "keepModuleIdExtensions",
+  "code",
+  "ast",
+  "format",
+  "playground",
+  "experimental",
+
+  // these are used by plugins
+  "ignore",
+  "only",
+  "extensions"
+];
+
 File.normaliseOptions = function (opts) {
-  opts = opts || {};
+  opts = clone(opts);
+
+  for (var key in opts) {
+    if (key[0] !== "_" && File.validOptions.indexOf(key) < 0) {
+      throw new ReferenceError("Unknown option: " + key);
+    }
+  }
 
   _.defaults(opts, {
-    blacklist: [],
-    whitelist: [],
-    sourceMap: false,
-    filename:  "unknown",
-    modules:   "common"
+    keepModuleIdExtensions: false,
+    experimental:           false,
+    reactCompat:            false,
+    playground:             false,
+    whitespace:             true,
+    moduleIds:              false,
+    blacklist:              [],
+    whitelist:              [],
+    sourceMap:              false,
+    optional:               [],
+    comments:               true,
+    filename:               "unknown",
+    modules:                "common",
+    loose:                  [],
+    code:                   true,
+    ast:                    true
+  });
+
+  // normalise windows path separators to unix
+  opts.filename = opts.filename.replace(/\\/g, "/");
+
+  opts.blacklist = util.arrayify(opts.blacklist);
+  opts.whitelist = util.arrayify(opts.whitelist);
+  opts.optional  = util.arrayify(opts.optional);
+  opts.loose     = util.arrayify(opts.loose);
+
+  if (_.contains(opts.loose, "all")) {
+    opts.loose = Object.keys(transform.transformers);
+  }
+
+  _.defaults(opts, {
+    moduleRoot: opts.sourceRoot
   });
 
   _.defaults(opts, {
-    sourceFileName: opts.filename,
-    sourceMapName:  opts.filename
+    sourceRoot: opts.moduleRoot
   });
 
-  transform._ensureTransformerNames("blacklist", opts.blacklist);
-  transform._ensureTransformerNames("whitelist", opts.whitelist);
+  _.defaults(opts, {
+    filenameRelative: opts.filename
+  });
+
+  _.defaults(opts, {
+    sourceFileName: opts.filenameRelative,
+    sourceMapName:  opts.filenameRelative
+  });
+
+  if (opts.playground) {
+    opts.experimental = true;
+  }
+
+  opts.blacklist = transform._ensureTransformerNames("blacklist", opts.blacklist);
+  opts.whitelist = transform._ensureTransformerNames("whitelist", opts.whitelist);
+  opts.optional = transform._ensureTransformerNames("optional", opts.optional);
+  opts.loose = transform._ensureTransformerNames("loose", opts.loose);
 
   return opts;
 };
 
+File.prototype.isLoose = function (key) {
+  return _.contains(this.opts.loose, key);
+};
+
+File.prototype.buildTransformers = function () {
+  var file = this;
+
+  var transformers = {};
+
+  var secondaryStack = [];
+  var stack = [];
+
+  _.each(transform.transformers, function (transformer, key) {
+    var pass = transformers[key] = transformer.buildPass(file);
+
+    if (pass.canRun(file)) {
+      stack.push(pass);
+      if (transformer.secondPass) {
+        secondaryStack.push(pass);
+      }
+
+      if (transformer.manipulateOptions) {
+        transformer.manipulateOptions(file.opts, file);
+      }
+    }
+  });
+
+  this.transformerStack = stack.concat(secondaryStack);
+  this.transformers = transformers;
+};
+
+File.prototype.toArray = function (node, i) {
+  if (t.isArrayExpression(node)) {
+    return node;
+  } else if (t.isIdentifier(node) && node.name === "arguments") {
+    return t.callExpression(t.memberExpression(this.addHelper("slice"), t.identifier("call")), [node]);
+  } else {
+    var declarationName = "to-array";
+    var args = [node];
+    if (i) {
+      args.push(t.literal(i));
+      declarationName = "sliced-to-array";
+    }
+    return t.callExpression(this.addHelper(declarationName), args);
+  }
+};
+
 File.prototype.getModuleFormatter = function (type) {
-  var ModuleLoader = transform.moduleFormatters[type];
+  var ModuleFormatter = _.isFunction(type) ? type : transform.moduleFormatters[type];
 
-  if (!ModuleLoader) {
+  if (!ModuleFormatter) {
     var loc = util.resolve(type);
-    if (loc) ModuleLoader = require(loc);
+    if (loc) ModuleFormatter = require(loc);
   }
 
-  if (!ModuleLoader) {
-    throw new ReferenceError("unknown module formatter type " + type);
+  if (!ModuleFormatter) {
+    throw new ReferenceError("Unknown module formatter type " + JSON.stringify(type));
   }
 
-  return new ModuleLoader(this);
+  return new ModuleFormatter(this);
 };
 
 File.prototype.parseShebang = function (code) {
@@ -66,85 +221,180 @@ File.prototype.parseShebang = function (code) {
   return code;
 };
 
-File.prototype.addDeclaration = function (name) {
-  var declar = this.declarations[name];
-  if (declar) return declar.uid;
+File.prototype.set = function (key, val) {
+  return this.data[key] = val;
+};
 
-  var uid = b.identifier(this.generateUid(name));
-  this.declarations[name] = {
-    uid: uid,
-    node: util.template(name)
-  };
-  return uid;
+File.prototype.setDynamic = function (key, fn) {
+  this.dynamicData[key] = fn;
+};
+
+File.prototype.get = function (key) {
+  var data = this.data[key];
+  if (data) {
+    return data;
+  } else {
+    var dynamic = this.dynamicData[key];
+    if (dynamic) {
+      return this.set(key, dynamic());
+    }
+  }
+};
+
+File.prototype.addImport = function (source, name) {
+  name = name || source;
+  var id = this.dynamicImportIds[name];
+
+  if (!id) {
+    id = this.dynamicImportIds[name] = this.generateUidIdentifier(name);
+
+    var specifiers = [t.importSpecifier(t.identifier("default"), id)];
+    var declar = t.importDeclaration(specifiers, t.literal(source));
+    declar._blockHoist = 3;
+    this.dynamicImported.push(declar);
+
+    this.moduleFormatter.importSpecifier(specifiers[0], declar, this.dynamicImports);
+  }
+
+  return id;
+};
+
+File.prototype.isConsequenceExpressionStatement = function (node) {
+  return t.isExpressionStatement(node) && this.lastStatements.indexOf(node) >= 0;
+};
+
+File.prototype.addHelper = function (name) {
+  if (!_.contains(File.helpers, name)) {
+    throw new ReferenceError("unknown declaration " + name);
+  }
+
+  var program = this.ast.program;
+
+  var declar = program._declarations && program._declarations[name];
+  if (declar) return declar.id;
+
+  var runtime = this.get("runtimeIdentifier");
+  if (runtime) {
+    name = t.identifier(t.toIdentifier(name));
+    return t.memberExpression(runtime, name);
+  } else {
+    var ref = util.template(name);
+    ref._compact = true;
+    var uid = this.generateUidIdentifier(name);
+    this.scope.push({
+      key: name,
+      id: uid,
+      init: ref
+    });
+    return uid;
+  }
+};
+
+File.prototype.errorWithNode = function (node, msg, Error) {
+  Error = Error || SyntaxError;
+
+  var loc = node.loc.start;
+  var err = new Error("Line " + loc.line + ": " + msg);
+  err.loc = loc;
+  return err;
+};
+
+File.prototype.addCode = function (code) {
+  code = (code || "") + "";
+  this.code = code;
+  return this.parseShebang(code);
 };
 
 File.prototype.parse = function (code) {
   var self = this;
 
-  code = this.parseShebang(code);
+  code = this.addCode(code);
 
-  return util.parse(this.opts, code, function (tree) {
+  var opts = this.opts;
+
+  opts.allowImportExportEverywhere = this.isLoose("modules");
+
+  return util.parse(opts, code, function (tree) {
     self.transform(tree);
     return self.generate();
   });
 };
 
 File.prototype.transform = function (ast) {
-  this.ast = ast;
-
   var self = this;
 
-  _.each(transform.transformers, function (transformer) {
-    transformer.transform(self);
+  this.ast = ast;
+  this.lastStatements = t.getLastStatements(ast.program);
+  this.scope = new Scope(ast.program, ast, null, this);
+  this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
+
+  var astRun = function (key) {
+    _.each(self.transformerStack, function (pass) {
+      pass.astRun(key);
+    });
+  };
+
+  astRun("enter");
+
+  _.each(this.transformerStack, function (pass) {
+    pass.transform();
   });
+
+  astRun("exit");
 };
 
 File.prototype.generate = function () {
   var opts = this.opts;
   var ast  = this.ast;
 
-  var printOpts = { tabWidth: 2 };
+  var result = {
+    code: "",
+    map: null,
+    ast: null
+  };
 
-  if (opts.sourceMap) {
-    printOpts.sourceMapName = opts.sourceMapName;
-  }
+  if (opts.ast) result.ast = ast;
+  if (!opts.code) return result;
 
-  var result = recast.print(ast, printOpts);
-  var code   = result.code;
+  var _result = generate(ast, opts, this.code);
+  result.code = _result.code;
+  result.map  = _result.map;
 
   if (this.shebang) {
     // add back shebang
-    code = this.shebang + code;
+    result.code = this.shebang + "\n" + result.code;
   }
 
   if (opts.sourceMap === "inline") {
-    code += "\n" + util.sourceMapToComment(result.map);
+    result.code += "\n" + util.sourceMapToComment(result.map);
   }
 
-  return {
-    code: code,
-    map:  result.map || null,
-    ast:  ast
-  };
+  return result;
 };
 
-File.prototype.generateUid = function (name) {
-  // replace all non-valid identifiers with dashes
-  name = name.replace(/[^a-zA-Z0-9]/g, "-");
+File.prototype.generateUid = function (name, scope) {
+  name = t.toIdentifier(name).replace(/^_+/, "");
 
-  // remove all dashes and numbers from start of name
-  name = name.replace(/^[-0-9]+/, "");
+  scope = scope || this.scope;
 
-  // camel case
-  name = name.replace(/[-_\s]+(.)?/g, function (match, c) {
-    return c ? c.toUpperCase() : "";
-  });
+  var uid;
+  var i = 0;
+  do {
+    uid = this._generateUid(name, i);
+    i++;
+  } while (scope.has(uid));
+  return uid;
+};
 
-  var uids = this.uids;
-  var i = uids[name] || 1;
+File.prototype.generateUidIdentifier = function (name, scope) {
+  scope = scope || this.scope;
+  var id = t.identifier(this.generateUid(name, scope));
+  scope.add(id);
+  return id;
+};
 
+File.prototype._generateUid = function (name, i) {
   var id = name;
   if (i > 1) id += i;
-  uids[name] = i + 1;
   return "_" + id;
 };

lib/6to5/generation/buffer.js

@@ -0,0 +1,162 @@
+"use strict";
+
+module.exports = Buffer;
+
+var util = require("../util");
+var _    = require("lodash");
+
+function Buffer(position, format) {
+  this.position = position;
+  this._indent  = format.indent.base;
+  this.format   = format;
+  this.buf      = "";
+}
+
+Buffer.prototype.get = function () {
+  return util.trimRight(this.buf);
+};
+
+Buffer.prototype.getIndent = function () {
+  if (this.format.compact) {
+    return "";
+  } else {
+    return util.repeat(this._indent, this.format.indent.style);
+  }
+};
+
+Buffer.prototype.indentSize = function () {
+  return this.getIndent().length;
+};
+
+Buffer.prototype.indent = function () {
+  this._indent++;
+};
+
+Buffer.prototype.dedent = function () {
+  this._indent--;
+};
+
+Buffer.prototype.semicolon = function () {
+  this.push(";");
+};
+
+Buffer.prototype.ensureSemicolon = function () {
+  if (!this.isLast(";")) this.semicolon();
+};
+
+Buffer.prototype.rightBrace = function () {
+  this.newline(true);
+  this.push("}");
+};
+
+Buffer.prototype.keyword = function (name) {
+  this.push(name);
+  this.push(" ");
+};
+
+Buffer.prototype.space = function () {
+  if (this.buf && !this.isLast([" ", "\n"])) {
+    this.push(" ");
+  }
+};
+
+Buffer.prototype.removeLast = function (cha) {
+  if (!this.isLast(cha)) return;
+
+  this.buf = this.buf.substr(0, this.buf.length - 1);
+  this.position.unshift(cha);
+};
+
+Buffer.prototype.newline = function (i, removeLast) {
+  if (this.format.compact) {
+    this.space();
+    return;
+  }
+
+  removeLast = removeLast || false;
+
+  if (_.isNumber(i)) {
+    if (this.endsWith("{\n")) i--;
+    if (this.endsWith(util.repeat(i, "\n"))) return;
+
+    while (i--) {
+      this._newline(removeLast);
+    }
+    return;
+  }
+
+  if (_.isBoolean(i)) {
+    removeLast = i;
+  }
+
+  this._newline(removeLast);
+};
+
+Buffer.prototype._newline = function (removeLast) {
+  if (removeLast && this.isLast("\n")) this.removeLast("\n");
+
+  this.removeLast(" ");
+
+  // remove whitespace if last character was a newline
+  this._removeSpacesAfterLastNewline();
+  this._push("\n");
+};
+
+/**
+ * If buffer ends with a newline and some spaces after it, trim those spaces.
+ */
+Buffer.prototype._removeSpacesAfterLastNewline = function () {
+  var lastNewlineIndex = this.buf.lastIndexOf("\n");
+  if (lastNewlineIndex === -1)
+    return;
+
+  var index = this.buf.length - 1;
+  while (index > lastNewlineIndex) {
+    if (this.buf[index] !== " ") {
+      break;
+    }
+
+    index--;
+  }
+
+  if (index === lastNewlineIndex) {
+    this.buf = this.buf.substring(0, index + 1);
+  }
+};
+
+Buffer.prototype.push = function (str, noIndent) {
+  if (this._indent && !noIndent && str !== "\n") {
+    // we have an indent level and we aren't pushing a newline
+    var indent = this.getIndent();
+
+    // replace all newlines with newlines with the indentation
+    str = str.replace(/\n/g, "\n" + indent);
+
+    // we've got a newline before us so prepend on the indentation
+    if (this.isLast("\n")) str = indent + str;
+  }
+
+  this._push(str);
+};
+
+Buffer.prototype._push = function (str) {
+  this.position.push(str);
+  this.buf += str;
+};
+
+Buffer.prototype.endsWith = function (str) {
+  var d = this.buf.length - str.length;
+  return d >= 0 && this.buf.lastIndexOf(str) === d;
+};
+
+Buffer.prototype.isLast = function (cha, trimRight) {
+  var buf = this.buf;
+  if (trimRight) buf = util.trimRight(buf);
+  var last = buf[buf.length - 1];
+
+  if (Array.isArray(cha)) {
+    return _.contains(cha, last);
+  } else {
+    return cha === last;
+  }
+};

lib/6to5/generation/generator.js

@@ -0,0 +1,345 @@
+"use strict";
+
+module.exports = function (ast, opts, code) {
+  var gen = new CodeGenerator(ast, opts, code);
+  return gen.generate();
+};
+
+module.exports.CodeGenerator = CodeGenerator;
+
+var detectIndent = require("detect-indent");
+var Whitespace   = require("./whitespace");
+var SourceMap    = require("./source-map");
+var Position     = require("./position");
+var Buffer       = require("./buffer");
+var util         = require("../util");
+var n            = require("./node");
+var t            = require("../types");
+var _            = require("lodash");
+
+function CodeGenerator(ast, opts, code) {
+  opts = opts || {};
+
+  this.comments = ast.comments || [];
+  this.tokens   = ast.tokens || [];
+  this.format   = CodeGenerator.normaliseOptions(code, opts);
+  this.ast      = ast;
+
+  this.whitespace = new Whitespace(this.tokens, this.comments);
+  this.position   = new Position;
+  this.map        = new SourceMap(this.position, opts, code);
+  this.buffer     = new Buffer(this.position, this.format);
+}
+
+_.each(Buffer.prototype, function (fn, key) {
+  CodeGenerator.prototype[key] = function () {
+    return fn.apply(this.buffer, arguments);
+  };
+});
+
+CodeGenerator.normaliseOptions = function (code, opts) {
+  var indent = detectIndent(code);
+  var style  = indent.indent;
+  if (!style || style === " ") style = "  ";
+
+  return _.merge({
+    parentheses: true,
+    comments: opts.comments == null || opts.comments,
+    compact: false,
+    indent: {
+      adjustMultilineComment: true,
+      style: style,
+      base: 0
+    }
+  }, opts.format || {});
+};
+
+CodeGenerator.generators = {
+  templateLiterals: require("./generators/template-literals"),
+  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"),
+  types:            require("./generators/types"),
+  flow:             require("./generators/flow"),
+  base:             require("./generators/base"),
+  jsx:              require("./generators/jsx")
+};
+
+_.each(CodeGenerator.generators, function (generator) {
+  _.extend(CodeGenerator.prototype, generator);
+});
+
+CodeGenerator.prototype.generate = function () {
+  var ast = this.ast;
+
+  this.print(ast);
+
+  var comments = [];
+  _.each(ast.comments, function (comment) {
+    if (!comment._displayed) comments.push(comment);
+  });
+  this._printComments(comments);
+
+  return {
+    map:  this.map.get(),
+    code: this.buffer.get()
+  };
+};
+
+CodeGenerator.prototype.buildPrint = function (parent) {
+  var self = this;
+
+  var print = function (node, opts) {
+    return self.print(node, parent, opts);
+  };
+
+  print.sequence = function (nodes, opts) {
+    opts = opts || {};
+    opts.statement = true;
+    return self.printJoin(print, nodes, opts);
+  };
+
+  print.join = function (nodes, opts) {
+    return self.printJoin(print, nodes, opts);
+  };
+
+  print.block = function (node) {
+    return self.printBlock(print, node);
+  };
+
+  print.indentOnComments = function (node) {
+    return self.printAndIndentOnComments(print, node);
+  };
+
+  return print;
+};
+
+CodeGenerator.prototype.print = function (node, parent, opts) {
+  if (!node) return "";
+
+  if (parent && parent._compact) {
+    node._compact = true;
+  }
+
+  var oldCompact = this.format.compact;
+  if (node._compact) {
+    this.format.compact = true;
+  }
+
+  var self = this;
+
+  opts = opts || {};
+
+  var newline = function (leading) {
+    if (!opts.statement && !n.isUserWhitespacable(node, parent)) {
+      return;
+    }
+
+    var lines = 0;
+
+    if (node.start != null && !node._ignoreUserWhitespace) {
+      // user node
+      if (leading) {
+        lines = self.whitespace.getNewlinesBefore(node);
+      } else {
+        lines = self.whitespace.getNewlinesAfter(node);
+      }
+    } else {
+      // generated node
+      if (!leading) lines++; // always include at least a single line after
+
+      var needs = n.needsWhitespaceAfter;
+      if (leading) needs = n.needsWhitespaceBefore;
+      lines += needs(node, parent);
+
+      // generated nodes can't add starting file whitespace
+      if (!self.buffer.get()) lines = 0;
+    }
+
+    self.newline(lines);
+  };
+
+  if (this[node.type]) {
+    var needsNoLineTermParens = n.needsParensNoLineTerminator(node, parent);
+    var needsParens           = needsNoLineTermParens || n.needsParens(node, parent);
+
+    if (needsParens) this.push("(");
+    if (needsNoLineTermParens) this.indent();
+
+    this.printLeadingComments(node, parent);
+
+    newline(true);
+
+    if (opts.before) opts.before();
+    this.map.mark(node, "start");
+
+    this[node.type](node, this.buildPrint(node), parent);
+
+    if (needsNoLineTermParens) {
+      this.newline();
+      this.dedent();
+    }
+    if (needsParens) this.push(")");
+
+    this.map.mark(node, "end");
+    if (opts.after) opts.after();
+
+    newline(false);
+
+    this.printTrailingComments(node, parent);
+  } else {
+    throw new ReferenceError("unknown node of type " + JSON.stringify(node.type) + " with constructor " + JSON.stringify(node && node.constructor.name));
+  }
+
+  this.format.compact = oldCompact;
+};
+
+CodeGenerator.prototype.printJoin = function (print, nodes, opts) {
+  if (!nodes || !nodes.length) return;
+
+  opts = opts || {};
+
+  var self = this;
+  var len  = nodes.length;
+
+  if (opts.indent) self.indent();
+
+  _.each(nodes, function (node, i) {
+    print(node, {
+      statement: opts.statement,
+      after: function () {
+        if (opts.iterator) {
+          opts.iterator(node, i);
+        }
+
+        if (opts.separator && i < len - 1) {
+          self.push(opts.separator);
+        }
+      }
+    });
+  });
+
+  if (opts.indent) self.dedent();
+};
+
+CodeGenerator.prototype.printAndIndentOnComments = function (print, node) {
+  var indent = !!node.leadingComments;
+  if (indent) this.indent();
+  print(node);
+  if (indent) this.dedent();
+};
+
+CodeGenerator.prototype.printBlock = function (print, node) {
+  if (t.isEmptyStatement(node)) {
+    this.semicolon();
+  } else {
+    this.push(" ");
+    print(node);
+  }
+};
+
+CodeGenerator.prototype.generateComment = function (comment) {
+  var val = comment.value;
+  if (comment.type === "Line") {
+    val = "//" + val;
+  } else {
+    val = "/*" + val + "*/";
+  }
+  return val;
+};
+
+CodeGenerator.prototype.printTrailingComments = function (node, parent) {
+  this._printComments(this.getComments("trailingComments", node, parent));
+};
+
+CodeGenerator.prototype.printLeadingComments = function (node, parent) {
+  this._printComments(this.getComments("leadingComments", node, parent));
+};
+
+CodeGenerator.prototype.getComments = function (key, node, parent) {
+  if (t.isExpressionStatement(parent)) {
+    return [];
+  }
+
+  var comments = [];
+  var nodes    = [node];
+  var self     = this;
+
+  if (t.isExpressionStatement(node)) {
+    nodes.push(node.argument);
+  }
+
+  _.each(nodes, function (node) {
+    comments = comments.concat(self._getComments(key, node));
+  });
+
+  return comments;
+};
+
+CodeGenerator.prototype._getComments = function (key, node) {
+  return (node && node[key]) || [];
+};
+
+CodeGenerator.prototype._printComments = function (comments) {
+  if (this.format.compact) return;
+  if (!this.format.comments) return;
+  if (!comments || !comments.length) return;
+
+  var self = this;
+
+  _.each(comments, function (comment) {
+    var skip = false;
+
+    // find the original comment in the ast and set it as displayed
+    _.each(self.ast.comments, function (origComment) {
+      if (origComment.start === comment.start) {
+        // comment has already been output
+        if (origComment._displayed) skip = true;
+
+        origComment._displayed = true;
+        return false;
+      }
+    });
+
+    if (skip) return;
+
+    // whitespace before
+    self.newline(self.whitespace.getNewlinesBefore(comment));
+
+    var column = self.position.column;
+    var val    = self.generateComment(comment);
+
+    if (column && !self.isLast(["\n", " ", "[", "{"])) {
+      self._push(" ");
+      column++;
+    }
+
+    //
+
+    if (comment.type === "Block" && self.format.indent.adjustMultilineComment) {
+      var offset = comment.loc.start.column;
+      if (offset) {
+        var newlineRegex = new RegExp("\\n\\s{1," + offset + "}", "g");
+        val = val.replace(newlineRegex, "\n");
+      }
+
+      var indent = Math.max(self.indentSize(), column);
+      val = val.replace(/\n/g, "\n" + util.repeat(indent));
+    }
+
+    if (column === 0) {
+      val = self.getIndent() + val;
+    }
+
+    //
+
+    self._push(val);
+
+    // whitespace after
+    self.newline(self.whitespace.getNewlinesAfter(comment));
+  });
+};

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

@@ -0,0 +1,21 @@
+"use strict";
+
+exports.File = function (node, print) {
+  print(node.program);
+};
+
+exports.Program = function (node, print) {
+  print.sequence(node.body);
+};
+
+exports.BlockStatement = function (node, print) {
+  if (node.body.length === 0) {
+    this.push("{}");
+  } else {
+    this.push("{");
+    this.newline();
+    print.sequence(node.body, { indent: true });
+    this.removeLast("\n");
+    this.rightBrace();
+  }
+};

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

@@ -0,0 +1,42 @@
+"use strict";
+
+exports.ClassExpression =
+exports.ClassDeclaration = function (node, print) {
+  this.push("class");
+
+  if (node.id) {
+    this.space();
+    print(node.id);
+  }
+
+  if (node.superClass) {
+    this.push(" extends ");
+    print(node.superClass);
+  }
+
+  this.space();
+  print(node.body);
+};
+
+exports.ClassBody = function (node, print) {
+  if (node.body.length === 0) {
+    this.push("{}");
+  } else {
+    this.push("{");
+    this.newline();
+
+    this.indent();
+    print.sequence(node.body);
+    this.dedent();
+
+    this.rightBrace();
+  }
+};
+
+exports.MethodDefinition = function (node, print) {
+  if (node.static) {
+    this.push("static ");
+  }
+
+  this._method(node, print);
+};

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

@@ -0,0 +1,29 @@
+"use strict";
+
+exports.ComprehensionBlock = function (node, print) {
+  this.keyword("for");
+  this.push("(");
+  print(node.left);
+  this.push(" of ");
+  print(node.right);
+  this.push(")");
+};
+
+exports.ComprehensionExpression = function (node, print) {
+  this.push(node.generator ? "(" : "[");
+
+  print.join(node.blocks, { separator: " " });
+  this.space();
+
+  if (node.filter) {
+    this.keyword("if");
+    this.push("(");
+    print(node.filter);
+    this.push(")");
+    this.space();
+  }
+
+  print(node.body);
+
+  this.push(node.generator ? ")" : "]");
+};

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

@@ -0,0 +1,149 @@
+"use strict";
+
+var util = require("../../util");
+var t    = require("../../types");
+var _    = require("lodash");
+
+exports.UnaryExpression = function (node, print) {
+  var hasSpace = /[a-z]$/.test(node.operator);
+  var arg = node.argument;
+
+  if (t.isUpdateExpression(arg) || t.isUnaryExpression(arg)) {
+    hasSpace = true;
+  }
+
+  if (t.isUnaryExpression(arg) && arg.operator === "!") {
+    hasSpace = false;
+  }
+
+  this.push(node.operator);
+  if (hasSpace) this.space();
+  print(node.argument);
+};
+
+exports.UpdateExpression = function (node, print) {
+  if (node.prefix) {
+    this.push(node.operator);
+    print(node.argument);
+  } else {
+    print(node.argument);
+    this.push(node.operator);
+  }
+};
+
+exports.ConditionalExpression = function (node, print) {
+  print(node.test);
+  this.push(" ? ");
+  print(node.consequent);
+  this.push(" : ");
+  print(node.alternate);
+};
+
+exports.NewExpression = function (node, print) {
+  this.push("new ");
+  print(node.callee);
+  if (node.arguments.length || this.format.parentheses) {
+    this.push("(");
+    print.join(node.arguments, { separator: ", " });
+    this.push(")");
+  }
+};
+
+exports.SequenceExpression = function (node, print) {
+  print.join(node.expressions, { separator: ", " });
+};
+
+exports.ThisExpression = function () {
+  this.push("this");
+};
+
+exports.CallExpression = function (node, print) {
+  print(node.callee);
+
+  this.push("(");
+
+  var separator = ",";
+
+  if (node._prettyCall) {
+    separator += "\n";
+    this.newline();
+    this.indent();
+  } else {
+    separator += " ";
+  }
+
+  print.join(node.arguments, {
+    separator: separator
+  });
+
+  if (node._prettyCall) {
+    this.newline();
+    this.dedent();
+  }
+
+  this.push(")");
+};
+
+var buildYieldAwait = function (keyword) {
+  return function (node, print) {
+    this.push(keyword);
+    if (node.delegate) this.push("*");
+    if (node.argument) {
+      this.space();
+      print(node.argument);
+    }
+  };
+};
+
+exports.YieldExpression = buildYieldAwait("yield");
+exports.AwaitExpression = buildYieldAwait("await");
+
+exports.EmptyStatement = function () {
+  this.semicolon();
+};
+
+exports.ExpressionStatement = function (node, print) {
+  print(node.expression);
+  this.semicolon();
+};
+
+exports.BinaryExpression =
+exports.LogicalExpression =
+exports.AssignmentPattern =
+exports.AssignmentExpression = function (node, print) {
+  print(node.left);
+  this.space();
+  this.push(node.operator);
+  this.space();
+  print(node.right);
+};
+
+var SCIENTIFIC_NOTATION = /e/i;
+
+exports.MemberExpression = function (node, print) {
+  var obj = node.object;
+  print(obj);
+
+  if (!node.computed && t.isMemberExpression(node.property)) {
+    throw new TypeError("Got a MemberExpression for MemberExpression property");
+  }
+
+  var computed = node.computed;
+  if (t.isLiteral(node.property) && _.isNumber(node.property.value)) {
+    computed = true;
+  }
+
+  if (computed) {
+    this.push("[");
+    print(node.property);
+    this.push("]");
+  } else {
+    // 5..toFixed(2);
+    if (t.isLiteral(obj) && util.isInteger(obj.value) && !SCIENTIFIC_NOTATION.test(obj.value.toString())) {
+      this.push(".");
+    }
+
+    this.push(".");
+    print(node.property);
+  }
+};

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

@@ -0,0 +1,35 @@
+"use strict";
+
+exports.AnyTypeAnnotation =
+exports.ArrayTypeAnnotation =
+exports.BooleanTypeAnnotation =
+exports.ClassProperty =
+exports.DeclareClass =
+exports.DeclareFunction =
+exports.DeclareModule =
+exports.DeclareVariable =
+exports.FunctionTypeAnnotation =
+exports.FunctionTypeParam =
+exports.GenericTypeAnnotation =
+exports.InterfaceExtends =
+exports.InterfaceDeclaration =
+exports.IntersectionTypeAnnotation =
+exports.NullableTypeAnnotation =
+exports.NumberTypeAnnotation =
+exports.StringLiteralTypeAnnotation =
+exports.StringTypeAnnotation =
+exports.TupleTypeAnnotation =
+exports.TypeofTypeAnnotation =
+exports.TypeAlias =
+exports.TypeAnnotation =
+exports.TypeParameterDeclaration =
+exports.TypeParameterInstantiation =
+exports.ObjectTypeAnnotation =
+exports.ObjectTypeCallProperty =
+exports.ObjectTypeIndexer =
+exports.ObjectTypeProperty =
+exports.QualifiedTypeIdentifier =
+exports.UnionTypeAnnotation =
+exports.VoidTypeAnnotation = function () {
+  // todo: implement these once we have a `--keep-types` option
+};

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

@@ -0,0 +1,80 @@
+"use strict";
+
+var t = require("../../types");
+var _ = require("lodash");
+
+exports.JSXAttribute = function (node, print) {
+  print(node.name);
+  if (node.value) {
+    this.push("=");
+    print(node.value);
+  }
+};
+
+exports.JSXIdentifier = function (node) {
+  this.push(node.name);
+};
+
+exports.JSXNamespacedName = function (node, print) {
+  print(node.namespace);
+  this.push(":");
+  print(node.name);
+};
+
+exports.JSXMemberExpression = function (node, print) {
+  print(node.object);
+  this.push(".");
+  print(node.property);
+};
+
+exports.JSXSpreadAttribute = function (node, print) {
+  this.push("{...");
+  print(node.argument);
+  this.push("}");
+};
+
+exports.JSXExpressionContainer = function (node, print) {
+  this.push("{");
+  print(node.expression);
+  this.push("}");
+};
+
+exports.JSXElement = function (node, print) {
+  var self = this;
+
+  var open = node.openingElement;
+  print(open);
+  if (open.selfClosing) return;
+
+  this.indent();
+  _.each(node.children, function (child) {
+    if (t.isLiteral(child)) {
+      self.push(child.value);
+    } else {
+      print(child);
+    }
+  });
+  this.dedent();
+
+  print(node.closingElement);
+};
+
+exports.JSXOpeningElement = function (node, print) {
+  this.push("<");
+  print(node.name);
+  if (node.attributes.length > 0) {
+    this.push(" ");
+    print.join(node.attributes, { separator: " " });
+  }
+  this.push(node.selfClosing ? " />" : ">");
+};
+
+exports.JSXClosingElement = function (node, print) {
+  this.push("</");
+  print(node.name);
+  this.push(">");
+};
+
+exports.JSXEmptyExpression = function () {
+
+};

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

@@ -0,0 +1,69 @@
+"use strict";
+
+var t = require("../../types");
+
+exports._params = function (node, print) {
+  this.push("(");
+
+  print.join(node.params, {
+    separator: ", "
+  });
+
+  this.push(")");
+};
+
+exports._method = function (node, print) {
+  var value = node.value;
+  var kind  = node.kind;
+  var key   = node.key;
+
+  if (!kind || kind === "init") {
+    if (value.generator) {
+      this.push("*");
+    }
+  } else {
+    this.push(kind + " ");
+  }
+
+  if (value.async) this.push("async ");
+
+  if (node.computed) {
+    this.push("[");
+    print(key);
+    this.push("]");
+  } else {
+    print(key);
+  }
+
+  this._params(value, print);
+  this.push(" ");
+  print(value.body);
+};
+
+exports.FunctionDeclaration =
+exports.FunctionExpression = function (node, print) {
+  if (node.async) this.push("async ");
+  this.push("function");
+  if (node.generator) this.push("*");
+  this.push(" ");
+  if (node.id) {
+    this.space();
+    print(node.id);
+  }
+  this._params(node, print);
+  this.space();
+  print(node.body);
+};
+
+exports.ArrowFunctionExpression = function (node, print) {
+  if (node.async) this.push("async ");
+
+  if (node.params.length === 1 && t.isIdentifier(node.params[0])) {
+    print(node.params[0]);
+  } else {
+    this._params(node, print);
+  }
+
+  this.push(" => ");
+  print(node.body);
+};

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

@@ -0,0 +1,98 @@
+"use strict";
+
+var t = require("../../types");
+var _ = require("lodash");
+
+exports.ImportSpecifier = function (node, print) {
+  if (t.isSpecifierDefault(node)) {
+    print(t.getSpecifierName(node));
+  } else {
+    return exports.ExportSpecifier.apply(this, arguments);
+  }
+};
+
+exports.ExportSpecifier = function (node, print) {
+  print(node.id);
+  if (node.name) {
+    this.push(" as ");
+    print(node.name);
+  }
+};
+
+exports.ExportBatchSpecifier = function () {
+  this.push("*");
+};
+
+exports.ExportDeclaration = function (node, print) {
+  this.push("export ");
+
+  var specifiers = node.specifiers;
+
+  if (node.default) {
+    this.push("default ");
+  }
+
+  if (node.declaration) {
+    print(node.declaration);
+    if (t.isStatement(node.declaration)) return;
+  } else {
+    if (specifiers.length === 1 && t.isExportBatchSpecifier(specifiers[0])) {
+      print(specifiers[0]);
+    } else {
+      this.push("{");
+      if (specifiers.length) {
+        this.space();
+        print.join(specifiers, { separator: ", " });
+        this.space();
+      }
+      this.push("}");
+    }
+
+    if (node.source) {
+      this.push(" from ");
+      print(node.source);
+    }
+  }
+
+  this.ensureSemicolon();
+};
+
+exports.ImportDeclaration = function (node, print) {
+  var self = this;
+
+  this.push("import ");
+
+  var specfiers = node.specifiers;
+  if (specfiers && specfiers.length) {
+    var foundImportSpecifier = false;
+
+    _.each(node.specifiers, function (spec, i) {
+      if (+i > 0) {
+        self.push(", ");
+      }
+
+      var isDefault = t.isSpecifierDefault(spec);
+
+      if (!isDefault && spec.type !== "ImportBatchSpecifier" && !foundImportSpecifier) {
+        foundImportSpecifier = true;
+        self.push("{ ");
+      }
+
+      print(spec);
+    });
+
+    if (foundImportSpecifier) {
+      this.push(" }");
+    }
+
+    this.push(" from ");
+  }
+
+  print(node.source);
+  this.semicolon();
+};
+
+exports.ImportBatchSpecifier = function (node, print) {
+  this.push("* as ");
+  print(node.name);
+};

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

@@ -0,0 +1,9 @@
+"use strict";
+
+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/statements.js

@@ -0,0 +1,216 @@
+"use strict";
+
+var util = require("../../util");
+var t    = require("../../types");
+
+exports.WithStatement = function (node, print) {
+  this.keyword("with");
+  this.push("(");
+  print(node.object);
+  this.push(")");
+  print.block(node.body);
+};
+
+exports.IfStatement = function (node, print) {
+  this.keyword("if");
+  this.push("(");
+  print(node.test);
+  this.push(")");
+  this.space();
+
+  print.indentOnComments(node.consequent);
+
+  if (node.alternate) {
+    if (this.isLast("}")) this.push(" ");
+    this.keyword("else");
+    print.indentOnComments(node.alternate);
+  }
+};
+
+exports.ForStatement = function (node, print) {
+  this.keyword("for");
+  this.push("(");
+
+  print(node.init);
+  this.push(";");
+
+  if (node.test) {
+    this.push(" ");
+    print(node.test);
+  }
+  this.push(";");
+
+  if (node.update) {
+    this.push(" ");
+    print(node.update);
+  }
+
+  this.push(")");
+  print.block(node.body);
+};
+
+exports.WhileStatement = function (node, print) {
+  this.keyword("while");
+  this.push("(");
+  print(node.test);
+  this.push(")");
+  print.block(node.body);
+};
+
+var buildForXStatement = function (op) {
+  return function (node, print) {
+    this.keyword("for");
+    this.push("(");
+    print(node.left);
+    this.push(" " + op + " ");
+    print(node.right);
+    this.push(")");
+    print.block(node.body);
+  };
+};
+
+exports.ForInStatement = buildForXStatement("in");
+exports.ForOfStatement = buildForXStatement("of");
+
+exports.DoWhileStatement = function (node, print) {
+  this.keyword("do");
+  print(node.body);
+  this.space();
+  this.keyword("while");
+  this.push("(");
+  print(node.test);
+  this.push(");");
+};
+
+var buildLabelStatement = function (prefix, key) {
+  return function (node, print) {
+    this.push(prefix);
+
+    var label = node[key || "label"];
+    if (label) {
+      this.push(" ");
+      print(label);
+    }
+
+    this.semicolon();
+  };
+};
+
+exports.ContinueStatement = buildLabelStatement("continue");
+exports.ReturnStatement   = buildLabelStatement("return", "argument");
+exports.BreakStatement    = buildLabelStatement("break");
+
+exports.LabeledStatement = function (node, print) {
+  print(node.label);
+  this.push(": ");
+  print(node.body);
+};
+
+exports.TryStatement = function (node, print) {
+  this.keyword("try");
+  print(node.block);
+  this.space();
+
+  // Esprima bug puts the catch clause in a `handlers` array.
+  // see https://code.google.com/p/esprima/issues/detail?id=433
+  // We run into this from regenerator generated ast.
+  if (node.handlers) {
+    print(node.handlers[0]);
+  } else {
+    print(node.handler);
+  }
+
+  if (node.finalizer) {
+    this.space();
+    this.push("finally ");
+    print(node.finalizer);
+  }
+};
+
+exports.CatchClause = function (node, print) {
+  this.keyword("catch");
+  this.push("(");
+  print(node.param);
+  this.push(") ");
+  print(node.body);
+};
+
+exports.ThrowStatement = function (node, print) {
+  this.push("throw ");
+  print(node.argument);
+  this.semicolon();
+};
+
+exports.SwitchStatement = function (node, print) {
+  this.keyword("switch");
+  this.push("(");
+  print(node.discriminant);
+  this.push(")");
+  this.space();
+  this.push("{");
+  print.sequence(node.cases, { indent: true });
+  this.push("}");
+};
+
+exports.SwitchCase = function (node, print) {
+  if (node.test) {
+    this.push("case ");
+    print(node.test);
+    this.push(":");
+  } else {
+    this.push("default:");
+  }
+
+  this.newline();
+  print.sequence(node.consequent, { indent: true });
+};
+
+exports.DebuggerStatement = function () {
+  this.push("debugger;");
+};
+
+exports.VariableDeclaration = function (node, print, parent) {
+  this.push(node.kind + " ");
+
+  var hasInits = false;
+  // don't add whitespace to loop heads
+  if (!t.isFor(parent)) {
+    for (var i = 0; i < node.declarations.length; i++) {
+      if (node.declarations[i].init) {
+        // has an init so let's split it up over multiple lines
+        hasInits = true;
+      }
+    }
+  }
+
+  var sep = ",";
+  if (hasInits) {
+    sep += "\n" + util.repeat(node.kind.length + 1);
+  } else {
+    sep += " ";
+  }
+
+  print.join(node.declarations, { separator: sep });
+
+  if (!t.isFor(parent)) {
+    this.semicolon();
+  }
+};
+
+exports.PrivateDeclaration = function (node, print) {
+  this.push("private ");
+  print.join(node.declarations, { separator: ", " });
+  this.semicolon();
+};
+
+exports.VariableDeclarator = function (node, print) {
+  if (node.init) {
+    print(node.id);
+    this.space();
+    this.push("=");
+    this.space();
+    print(node.init);
+  } else {
+    print(node.id);
+  }
+};

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

@@ -0,0 +1,32 @@
+"use strict";
+
+var _ = require("lodash");
+
+exports.TaggedTemplateExpression = function (node, print) {
+  print(node.tag);
+  print(node.quasi);
+};
+
+exports.TemplateElement = function (node) {
+  this._push(node.value.raw);
+};
+
+exports.TemplateLiteral = function (node, print) {
+  this.push("`");
+
+  var quasis = node.quasis;
+  var self   = this;
+  var len    = quasis.length;
+
+  _.each(quasis, function (quasi, i) {
+    print(quasi);
+
+    if (i + 1 < len) {
+      self.push("${ ");
+      print(node.expressions[i]);
+      self.push(" }");
+    }
+  });
+
+  this._push("`");
+};

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

@@ -0,0 +1,103 @@
+"use strict";
+
+var _ = require("lodash");
+
+exports.Identifier = function (node) {
+  this.push(node.name);
+};
+
+exports.RestElement =
+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;
+
+  if (props.length) {
+    this.push("{");
+    this.space();
+
+    print.join(props, { separator: ", ", indent: true });
+
+    this.space();
+    this.push("}");
+  } else {
+    this.push("{}");
+  }
+};
+
+exports.Property = function (node, print) {
+  if (node.method || node.kind === "get" || node.kind === "set") {
+    this._method(node, print);
+  } else {
+    if (node.computed) {
+      this.push("[");
+      print(node.key);
+      this.push("]");
+    } else {
+      print(node.key);
+      if (node.shorthand) return;
+    }
+
+    this.push(": ");
+    print(node.value);
+  }
+};
+
+exports.ArrayExpression =
+exports.ArrayPattern = function (node, print) {
+  var elems = node.elements;
+  var self  = this;
+  var len   = elems.length;
+
+  this.push("[");
+
+  _.each(elems, function (elem, i) {
+    if (!elem) {
+      // If the array expression ends with a hole, that hole
+      // will be ignored by the interpreter, but if it ends with
+      // two (or more) holes, we need to write out two (or more)
+      // commas so that the resulting code is interpreted with
+      // both (all) of the holes.
+      self.push(",");
+    } else {
+      if (i > 0) self.push(" ");
+      print(elem);
+      if (i < len - 1) self.push(",");
+    }
+  });
+
+  this.push("]");
+};
+
+exports.Literal = function (node) {
+  var val  = node.value;
+  var type = typeof val;
+
+  if (type === "string") {
+    val = JSON.stringify(val);
+
+    // escape illegal js but valid json unicode characters
+    val = val.replace(/[\u000A\u000D\u2028\u2029]/g, function (c) {
+      return "\\u" + ("0000" + c.charCodeAt(0).toString(16)).slice(-4);
+    });
+
+    this.push(val);
+  } else if (type === "boolean" || type === "number") {
+    this.push(JSON.stringify(val));
+  } else if (node.regex) {
+    this.push("/" + node.regex.pattern + "/" + node.regex.flags);
+  } else if (val === null) {
+    this.push("null");
+  }
+};

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

@@ -0,0 +1,111 @@
+"use strict";
+
+module.exports = Node;
+
+var whitespace = require("./whitespace");
+var parens     = require("./parentheses");
+var t          = require("../../types");
+var _          = require("lodash");
+
+var find = function (obj, node, parent) {
+  if (!obj) return;
+  var result;
+
+  var types = Object.keys(obj);
+  for (var i = 0; i < types.length; i++) {
+    var type = types[i];
+
+    if (t.is(type, node)) {
+      var fn = obj[type];
+      result = fn(node, parent);
+      if (result != null) break;
+    }
+  }
+
+  return result;
+};
+
+function Node(node, parent) {
+  this.parent = parent;
+  this.node   = node;
+}
+
+Node.isUserWhitespacable = function (node) {
+  return t.isUserWhitespacable(node);
+};
+
+Node.needsWhitespace = function (node, parent, type) {
+  if (!node) return 0;
+
+  if (t.isExpressionStatement(node)) {
+    node = node.expression;
+  }
+
+  var lines = find(whitespace[type].nodes, node, parent);
+  if (lines) return lines;
+
+  _.each(find(whitespace[type].list, node, parent), function (expr) {
+    lines = Node.needsWhitespace(expr, node, type);
+    if (lines) return false;
+  });
+  return lines || 0;
+};
+
+Node.needsWhitespaceBefore = function (node, parent) {
+  return Node.needsWhitespace(node, parent, "before");
+};
+
+Node.needsWhitespaceAfter = function (node, parent) {
+  return Node.needsWhitespace(node, parent, "after");
+};
+
+Node.needsParens = function (node, parent) {
+  if (!parent) return false;
+
+  if (t.isNewExpression(parent) && parent.callee === node) {
+    if (t.isCallExpression(node)) return true;
+
+    var hasCall = _.some(node, function (val) {
+      return t.isCallExpression(val);
+    });
+    if (hasCall) return true;
+  }
+
+  return find(parens, node, parent);
+};
+
+Node.needsParensNoLineTerminator = function (node, parent) {
+  if (!parent) return false;
+
+  // no comments
+  if (!node.leadingComments || !node.leadingComments.length) {
+    return false;
+  }
+
+  if (t.isYieldExpression(parent) || t.isAwaitExpression(parent)) {
+    return true;
+  }
+
+  if (t.isContinueStatement(parent) || t.isBreakStatement(parent) ||
+      t.isReturnStatement(parent) || t.isThrowStatement(parent)) {
+    return true;
+  }
+
+  return false;
+};
+
+_.each(Node, function (fn, key) {
+  Node.prototype[key] = function () {
+    // Avoid leaking arguments to prevent deoptimization
+    var args = new Array(arguments.length + 2);
+
+    args[0] = this.node;
+    args[1] = this.parent;
+
+    for (var i = 0; i < args.length; i++) {
+      args[i + 2] = arguments[i];
+    }
+
+    return Node[key].apply(null, args);
+  };
+});

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

@@ -0,0 +1,169 @@
+"use strict";
+
+var t = require("../../types");
+var _ = require("lodash");
+
+var PRECEDENCE = {};
+
+_.each([
+  ["||"],
+  ["&&"],
+  ["|"],
+  ["^"],
+  ["&"],
+  ["==", "===", "!=", "!=="],
+  ["<", ">", "<=", ">=", "in", "instanceof"],
+  [">>", "<<", ">>>"],
+  ["+", "-"],
+  ["*", "/", "%"],
+  ["**"]
+], function (tier, i) {
+  _.each(tier, function (op) {
+    PRECEDENCE[op] = i;
+  });
+});
+
+exports.UpdateExpression = function (node, parent) {
+  if (t.isMemberExpression(parent) && parent.object === node) {
+    // (foo++).test()
+    return true;
+  }
+};
+
+exports.ObjectExpression = function (node, parent) {
+  if (t.isExpressionStatement(parent)) {
+    // ({ foo: "bar" });
+    return true;
+  }
+
+  if (t.isMemberExpression(parent) && parent.object === node) {
+    // ({ foo: "bar" }).foo
+    return true;
+  }
+
+  return false;
+};
+
+exports.Binary = function (node, parent) {
+  if ((t.isCallExpression(parent) || t.isNewExpression(parent)) && parent.callee === node) {
+    return true;
+  }
+
+  if (t.isUnaryLike(parent)) {
+    return true;
+  }
+
+  if (t.isMemberExpression(parent) && parent.object === node) {
+    return true;
+  }
+
+  if (t.isBinary(parent)) {
+    var parentOp  = parent.operator;
+    var parentPos = PRECEDENCE[parentOp];
+
+    var nodeOp = node.operator;
+    var nodePos = PRECEDENCE[nodeOp];
+
+    if (parentPos > nodePos) {
+      return true;
+    }
+
+    if (parentPos === nodePos && parent.right === node) {
+      return true;
+    }
+  }
+};
+
+exports.BinaryExpression = function (node, parent) {
+  if (node.operator === "in") {
+    // var i = (1 in []);
+    if (t.isVariableDeclarator(parent)) {
+      return true;
+    }
+
+    // for ((1 in []);;);
+    if (t.isFor(parent)) {
+      return true;
+    }
+  }
+};
+
+exports.SequenceExpression = function (node, parent) {
+  if (t.isForStatement(parent)) {
+    // Although parentheses wouldn't hurt around sequence
+    // expressions in the head of for loops, traditional style
+    // dictates that e.g. i++, j++ should not be wrapped with
+    // parentheses.
+    return false;
+  }
+
+  if (t.isExpressionStatement(parent) && parent.expression === node) {
+    return false;
+  }
+
+  // Otherwise err on the side of overparenthesization, adding
+  // explicit exceptions above if this proves overzealous.
+  return true;
+};
+
+exports.YieldExpression = function (node, parent) {
+  return t.isBinary(parent) ||
+         t.isUnaryLike(parent) ||
+         t.isCallExpression(parent) ||
+         t.isMemberExpression(parent) ||
+         t.isNewExpression(parent) ||
+         t.isConditionalExpression(parent) ||
+         t.isYieldExpression(parent);
+};
+
+exports.ClassExpression = function (node, parent) {
+  return t.isExpressionStatement(parent);
+};
+
+exports.UnaryLike = function (node, parent) {
+  return t.isMemberExpression(parent) && parent.object === node;
+};
+
+exports.FunctionExpression = function (node, parent) {
+  // function () {};
+  if (t.isExpressionStatement(parent)) {
+    return true;
+  }
+
+  // (function test() {}).name;
+  if (t.isMemberExpression(parent) && parent.object === node) {
+    return true;
+  }
+
+  // (function () {})();
+  if (t.isCallExpression(parent) && parent.callee === node) {
+    return true;
+  }
+};
+
+exports.AssignmentExpression =
+exports.ConditionalExpression = function (node, parent) {
+  if (t.isUnaryLike(parent)) {
+    return true;
+  }
+
+  if (t.isBinary(parent)) {
+    return true;
+  }
+
+  if (t.isCallExpression(parent) || t.isNewExpression(parent)) {
+    if (parent.callee === node) {
+      return true;
+    }
+  }
+
+  if (t.isConditionalExpression(parent) && parent.test === node) {
+    return true;
+  }
+
+  if (t.isMemberExpression(parent) && parent.object === node) {
+    return true;
+  }
+
+  return false;
+};

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

@@ -0,0 +1,78 @@
+"use strict";
+
+var _ = require("lodash");
+var t = require("../../types");
+
+exports.before = {
+  nodes: {
+    Property: function (node, parent) {
+      if (parent.properties[0] === node) {
+        return 1;
+      }
+    },
+
+    SpreadProperty: function (node, parent) {
+      return exports.before.nodes.Property(node, parent);
+    },
+
+    SwitchCase: function (node, parent) {
+      if (parent.cases[0] === node) {
+        return 1;
+      }
+    },
+
+    CallExpression: function (node) {
+      if (t.isFunction(node.callee)) {
+        return 1;
+      }
+    }
+  }
+};
+
+exports.after = {
+  nodes: {
+    AssignmentExpression: function (node) {
+      if (t.isFunction(node.right)) {
+        return 1;
+      }
+    }
+  },
+
+  list: {
+    VariableDeclaration: function (node) {
+      return _.map(node.declarations, "init");
+    },
+
+    ArrayExpression: function (node) {
+      return node.elements;
+    },
+
+    ObjectExpression: function (node) {
+      return node.properties;
+    }
+  }
+};
+
+_.each({
+  Function: 1,
+  Class: 1,
+  For: 1,
+  ArrayExpression: { after: 1 },
+  ObjectExpression: { after: 1 },
+  SwitchStatement: 1,
+  IfStatement: { before: 1 },
+  CallExpression: { after: 1 },
+  Literal: { after: 1 }
+}, function (amounts, type) {
+  if (_.isNumber(amounts)) {
+    amounts = { after: amounts, before: amounts };
+  }
+
+  _.each([type].concat(t.FLIPPED_ALIAS_KEYS[type] || []), function (type) {
+    _.each(amounts, function (amount, key) {
+      exports[key].nodes[type] = function () {
+        return amount;
+      };
+    });
+  });
+});

lib/6to5/generation/position.js

@@ -0,0 +1,29 @@
+"use strict";
+
+module.exports = Position;
+
+function Position() {
+  this.line = 1;
+  this.column = 0;
+}
+
+Position.prototype.push = function (str) {
+  for (var i = 0; i < str.length; i++) {
+    if (str[i] === "\n") {
+      this.line++;
+      this.column = 0;
+    } else {
+      this.column++;
+    }
+  }
+};
+
+Position.prototype.unshift = function (str) {
+  for (var i = 0; i < str.length; i++) {
+    if (str[i] === "\n") {
+      this.line--;
+    } else {
+      this.column--;
+    }
+  }
+};

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

@@ -0,0 +1,58 @@
+"use strict";
+
+module.exports = SourceMap;
+
+var sourceMap = require("source-map");
+var t         = require("../types");
+
+function SourceMap(position, opts, code) {
+  this.position = position;
+  this.opts     = opts;
+
+  if (opts.sourceMap) {
+    this.map = new sourceMap.SourceMapGenerator({
+      file: opts.sourceMapName,
+      sourceRoot: opts.sourceRoot
+    });
+
+    this.map.setSourceContent(opts.sourceFileName, code);
+  } else {
+    this.map = null;
+  }
+}
+
+SourceMap.prototype.get = function () {
+  var map = this.map;
+  if (map) {
+    return map.toJSON();
+  } else {
+    return map;
+  }
+};
+
+SourceMap.prototype.mark = function (node, type) {
+  var loc = node.loc;
+  if (!loc) return; // no location info
+
+  var map = this.map;
+  if (!map) return; // no source map
+
+  if (t.isProgram(node) || t.isFile(node)) return; // illegal mapping nodes
+
+  var position = this.position;
+
+  var generated = {
+    line: position.line,
+    column: position.column
+  };
+
+  var original = loc[type];
+
+  if (generated.line === original.line && generated.column === original.column) return; // nothing to map
+
+  map.addMapping({
+    source: this.opts.sourceFileName,
+    generated: generated,
+    original: original
+  });
+};

lib/6to5/generation/whitespace.js

@@ -0,0 +1,111 @@
+"use strict";
+
+module.exports = Whitespace;
+
+var _    = require("lodash");
+
+/**
+ * Returns `i`th number from `base`, continuing from 0 when `max` is reached.
+ * Useful for shifting `for` loop by a fixed number but going over all items.
+ *
+ * @param {Number} i Current index in the loop
+ * @param {Number} base Start index for which to return 0
+ * @param {Number} max Array length
+ * @returns {Number} shiftedIndex
+ */
+function getLookupIndex(i, base, max) {
+  i += base;
+
+  if (i >= max)
+    i -= max;
+
+  return i;
+}
+
+function Whitespace(tokens, comments) {
+  this.tokens = _.sortBy(tokens.concat(comments), "start");
+  this.used   = {};
+
+  // Profiling this code shows that while generator passes over it, indexes
+  // returned by `getNewlinesBefore` and `getNewlinesAfter` are always increasing.
+
+  // We use this implementation detail for an optimization: instead of always
+  // starting to look from `this.tokens[0]`, we will start `for` loops from the
+  // previous successful match. We will enumerate all tokens—but the common
+  // case will be much faster.
+
+  this._lastFoundIndex = 0;
+}
+
+Whitespace.prototype.getNewlinesBefore = function (node) {
+  var startToken;
+  var endToken;
+  var tokens = this.tokens;
+  var token;
+
+  for (var j = 0; j < tokens.length; j++) {
+    // optimize for forward traversal by shifting for loop index
+    var i = getLookupIndex(j, this._lastFoundIndex, this.tokens.length);
+    token = tokens[i];
+
+    // this is the token this node starts with
+    if (node.start === token.start) {
+      startToken = tokens[i - 1];
+      endToken = token;
+
+      this._lastFoundIndex = i;
+      break;
+    }
+  }
+
+  return this.getNewlinesBetween(startToken, endToken);
+};
+
+Whitespace.prototype.getNewlinesAfter = function (node) {
+  var startToken;
+  var endToken;
+  var tokens = this.tokens;
+  var token;
+
+  for (var j = 0; j < tokens.length; j++) {
+    // optimize for forward traversal by shifting for loop index
+    var i = getLookupIndex(j, this._lastFoundIndex, this.tokens.length);
+    token = tokens[i];
+
+    // this is the token this node ends with
+    if (node.end === token.end) {
+      startToken = token;
+      endToken = tokens[i + 1];
+
+      this._lastFoundIndex = i;
+      break;
+    }
+  }
+
+  if (endToken.type.type === "eof") {
+    return 1;
+  } else {
+    var lines = this.getNewlinesBetween(startToken, endToken);
+    if (node.type === "Line" && !lines) {
+      // line comment
+      return 1;
+    } else {
+      return lines;
+    }
+  }
+};
+
+Whitespace.prototype.getNewlinesBetween = function (startToken, endToken) {
+  var start = startToken ? startToken.loc.end.line : 1;
+  var end   = endToken.loc.start.line;
+  var lines = 0;
+
+  for (var line = start; line < end; line++) {
+    if (typeof this.used[line] === "undefined") {
+      this.used[line] = true;
+      lines++;
+    }
+  }
+
+  return lines;
+};

lib/6to5/helpers/clone.js

@@ -0,0 +1,12 @@
+"use strict";
+
+module.exports = function cloneDeep(obj) {
+  var obj2 = {};
+  if (!obj) return obj2;
+
+  for (var key in obj) {
+    obj2[key] = obj[key];
+  }
+
+  return obj2;
+};

lib/6to5/helpers/code-frame.js

@@ -0,0 +1,79 @@
+// syntax highlighting based on https://github.com/dominictarr/ansi-highlight by the fantastic Dominic Tarr
+
+var supportsColor = require("supports-color");
+var tokenize      = require("js-tokenizer");
+var chalk         = require("chalk");
+var util          = require("../util");
+
+var defs = {
+  string1:  "red",
+  string2:  "red",
+  punct:    ["white", "bold"],
+  curly:    "green",
+  parens:   ["blue", "bold"],
+  square:   ["yellow"],
+  name:     "white",
+  keyword:  ["cyan"],
+  number:   "magenta",
+  regexp:   "magenta",
+  comment1: "grey",
+  comment2: "grey"
+};
+
+var highlight = function (text) {
+  var colorize = function (str, col) {
+    if (!col) return str;
+
+    if (Array.isArray(col)) {
+      col.forEach(function (col) {
+        str = chalk[col](str);
+      });
+    } else {
+      str = chalk[col](str);
+    }
+    return str;
+  };
+
+  return tokenize(text, true).map(function (str) {
+    var type = tokenize.type(str);
+    return colorize(str, defs[type]);
+  }).join("");
+};
+
+module.exports = function (lines, lineNumber, colNumber) {
+  colNumber = Math.max(colNumber, 0);
+
+  if (supportsColor) {
+    lines = highlight(lines);
+  }
+
+  lines = lines.split("\n");
+
+  var start = Math.max(lineNumber - 3, 0);
+  var end   = Math.min(lines.length, lineNumber + 3);
+  var width = (end + "").length;
+
+  if (!lineNumber && !colNumber) {
+    start = 0;
+    end = lines.length;
+  }
+
+  return "\n" + lines.slice(start, end).map(function (line, i) {
+    var curr = i + start + 1;
+
+    var gutter = curr === lineNumber ? "> " : "  ";
+
+    var sep = curr + util.repeat(width + 1);
+    gutter += sep + "| ";
+
+    var str = gutter + line;
+
+    if (colNumber && curr === lineNumber) {
+      str += "\n";
+      str += util.repeat(gutter.length - 2);
+      str += "|" + util.repeat(colNumber) + "^";
+    }
+
+    return str;
+  }).join("\n");
+};

lib/6to5/helpers/object.js

@@ -0,0 +1,5 @@
+"use strict";
+
+module.exports = function () {
+  return Object.create(null);
+};

lib/6to5/helpers/to-fast-properties.js

@@ -0,0 +1,17 @@
+"use strict";
+
+/**
+ * A trick from Bluebird to force V8 to use fast properties for an object.
+ * Read more: http://stackoverflow.com/questions/24987896/
+ *
+ * Use %HasFastProperties(obj) and --allow-natives-syntax to check whether
+ * a particular object already has fast properties.
+ */
+
+module.exports = function toFastProperties(obj) {
+  /*jshint -W027*/
+  function f() {}
+  f.prototype = obj;
+  return f;
+  eval(obj);
+};

lib/6to5/index.js

@@ -1,8 +1,13 @@
-var transform = require("./transform");
+"use strict";
+
+var transform = require("./transformation/transform");
+var util      = require("./util");
 var fs        = require("fs");
 var _         = require("lodash");
 
-exports.util = require("./util");
+exports.version = require("../../package").version;
+
+exports.types = require("./types");
 
 exports.register = function (opts) {
   var register = require("./register");
@@ -14,6 +19,11 @@ exports.polyfill = function () {
   require("./polyfill");
 };
 
+exports.canCompile = util.canCompile;
+
+// do not use this - this is for use by official maintained 6to5 plugins
+exports._util = util;
+
 exports.transform = transform;
 
 exports.transformFile = function (filename, opts, callback) {

lib/6to5/modules/amd.js

@@ -1,82 +0,0 @@
-module.exports = AMDFormatter;
-
-var CommonJSFormatter = require("./common");
-var util              = require("../util");
-var b                 = require("acorn-ast-types").builders;
-var _                 = require("lodash");
-
-function AMDFormatter(file) {
-  this.file = file;
-  this.ids  = {};
-}
-
-util.inherits(AMDFormatter, CommonJSFormatter);
-
-AMDFormatter.prototype.transform = function (ast) {
-  var program = ast.program;
-  var body    = program.body;
-
-  // build an array of module names
-
-  var names = [b.literal("exports")];
-  _.each(this.ids, function (id, name) {
-    names.push(b.literal(name));
-  });
-  names = b.arrayExpression(names);
-
-  // build up define container
-
-  var params = _.values(this.ids);
-  params.unshift(b.identifier("exports"));
-
-  var container = b.functionExpression(null, params, b.blockStatement(body));
-  var call = b.callExpression(b.identifier("define"), [names, container]);
-
-  program.body = [b.expressionStatement(call)];
-};
-
-AMDFormatter.prototype._push = function (node) {
-  var id  = node.source.value;
-  var ids = this.ids;
-
-  if (ids[id]) {
-    return ids[id];
-  } else {
-    return this.ids[id] = b.identifier(this.file.generateUid(id));
-  }
-};
-
-AMDFormatter.prototype.import = function (node) {
-  this._push(node);
-};
-
-AMDFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
-  var key = util.getSpecifierName(specifier);
-  var id  = specifier.id;
-
-  // import foo from "foo";
-  if (specifier.default) {
-    id = b.identifier("default");
-  }
-
-  var ref;
-
-  if (specifier.type === "ImportBatchSpecifier") {
-    // import * as bar from "foo";
-    ref = this._push(node);
-  } else {
-    // import foo from "foo";
-    ref = b.memberExpression(this._push(node), id, false);
-  }
-
-  nodes.push(b.variableDeclaration("var", [
-    b.variableDeclarator(key, ref)
-  ]));
-};
-
-AMDFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
-  var self = this;
-  return this._exportSpecifier(function () {
-    return self._push(node);
-  }, specifier, node, nodes);
-};

lib/6to5/modules/common.js

@@ -1,97 +0,0 @@
-module.exports = CommonJSFormatter;
-
-var util = require("../util");
-var b    = require("acorn-ast-types").builders;
-
-function CommonJSFormatter(file) {
-  this.file = file;
-}
-
-CommonJSFormatter.prototype.import = function (node, nodes) {
-  // import "foo";
-  nodes.push(util.template("require", {
-    MODULE_NAME: node.source.raw
-  }, true));
-};
-
-CommonJSFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
-  var variableName = util.getSpecifierName(specifier);
-
-  // import foo from "foo";
-  if (specifier.default) {
-    specifier.id = b.identifier("default");
-  }
-
-  var templateName = "require-assign";
-
-  // import * as bar from "foo";
-  if (specifier.type !== "ImportBatchSpecifier") templateName += "-key";
-
-  nodes.push(util.template(templateName, {
-    VARIABLE_NAME: variableName,
-    MODULE_NAME:   node.source.raw,
-    KEY:           specifier.id
-  }));
-};
-
-CommonJSFormatter.prototype.export = function (node, nodes) {
-  var declar = node.declaration;
-
-  if (node.default) {
-    util.ensureExpressionType(declar);
-
-    nodes.push(util.template("exports-default", {
-      VALUE: declar
-    }, true));
-  } else {
-    var id = declar.id;
-    if (declar.type === "VariableDeclaration") {
-      id = declar.declarations[0].id;
-    }
-
-    var assign = util.template("exports-assign", {
-      VALUE: id,
-      KEY:   id
-    }, true);
-
-    nodes.push(declar);
-
-    if (declar.type === "FunctionDeclaration") {
-      assign._blockHoist = true;
-    }
-
-    nodes.push(assign);
-  }
-};
-
-CommonJSFormatter.prototype._exportSpecifier = function (getRef, specifier, node, nodes) {
-  var variableName = util.getSpecifierName(specifier);
-
-  if (node.source) {
-    if (specifier.type === "ExportBatchSpecifier") {
-      // export * from "foo";
-      nodes.push(util.template("exports-wildcard", {
-        OBJECT: getRef()
-      }, true));
-    } else {
-      // export { foo } from "test";
-      nodes.push(util.template("exports-assign-key", {
-        VARIABLE_NAME: variableName.name,
-        OBJECT:        getRef(),
-        KEY:           specifier.id
-      }, true));
-    }
-  } else {
-    // export { foo };
-    nodes.push(util.template("exports-assign", {
-      VALUE: specifier.id,
-      KEY:   variableName
-    }, true));
-  }
-};
-
-CommonJSFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
-  return this._exportSpecifier(function () {
-    return b.callExpression(b.identifier("require"), [node.source]);
-  }, specifier, node, nodes);
-};

lib/6to5/modules/umd.js

@@ -1,47 +0,0 @@
-module.exports = UMDFormatter;
-
-var AMDFormatter = require("./amd");
-var util         = require("../util");
-var b            = require("acorn-ast-types").builders;
-var _            = require("lodash");
-
-function UMDFormatter(file) {
-  this.file = file;
-  this.ids  = {};
-}
-
-util.inherits(UMDFormatter, AMDFormatter);
-
-UMDFormatter.prototype.transform = function (ast) {
-  var program = ast.program;
-  var body    = program.body;
-
-  // build an array of module names
-
-  var names = [];
-  _.each(this.ids, function (id, name) {
-    names.push(b.literal(name));
-  });
-
-  // factory
-
-  var ids  = _.values(this.ids);
-  var args = [b.identifier("exports")].concat(ids);
-
-  var factory = b.functionExpression(null, args, b.blockStatement(body));
-
-  // runner
-
-  var runner = util.template("umd-runner-body", {
-    AMD_ARGUMENTS: b.arrayExpression([b.literal("exports")].concat(names)),
-
-    COMMON_ARGUMENTS: names.map(function (name) {
-      return b.callExpression(b.identifier("require"), [name]);
-    })
-  });
-
-  //
-
-  var call = b.callExpression(runner, [factory]);
-  program.body = [b.expressionStatement(call)];
-};

lib/6to5/patch.js

@@ -0,0 +1,67 @@
+"use strict";
+
+var t = require("./types");
+var _ = require("lodash");
+
+require("./types/node");
+
+// estraverse
+
+var estraverse = require("estraverse");
+_.extend(estraverse.VisitorKeys, t.VISITOR_KEYS);
+
+// regenerator-6to5/ast-types
+
+var types = require("ast-types");
+var def   = types.Type.def;
+var or    = types.Type.or;
+
+def("File")
+  .bases("Node")
+  .build("program")
+  .field("program", def("Program"));
+
+def("AssignmentPattern")
+  .bases("Pattern")
+  .build("left", "right")
+  .field("left", def("Pattern"))
+  .field("right", def("Expression"));
+
+// Acorn - Same as ImportNamespaceSpecifier but `id` is `name`
+def("ImportBatchSpecifier")
+  .bases("Specifier")
+  .build("name")
+  .field("name", def("Identifier"));
+
+def("RestElement")
+  .bases("Node")
+  .build("argument")
+  .field("argument", def("Pattern"));
+
+// Abstract references
+def("VirtualPropertyExpression")
+  .bases("Expression")
+  .build("object", "property")
+  .field("object", def("Expression"))
+  .field("property", or(def("Identifier"), def("Expression")));
+
+def("PrivateDeclaration")
+  .bases("Declaration")
+  .build("declarations")
+  .field("declarations", [def("Identifier")]);
+
+// 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();

lib/6to5/polyfill.js

@@ -1,3 +1,9 @@
-require("es6-symbol/implement");
-require("es6-shim");
-require("regenerator/runtime");
+"use strict";
+
+if (global._6to5Polyfill) {
+  throw new Error("only one instance of 6to5/polyfill is allowed");
+}
+global._6to5Polyfill = true;
+
+require("core-js/shim");
+require("regenerator-6to5/runtime");

lib/6to5/register-browser.js

@@ -0,0 +1,7 @@
+"use strict";
+
+// required to safely use 6to5/register within a browserify codebase
+
+module.exports = function () {};
+
+require("./polyfill");

lib/6to5/register-cache.js

@@ -0,0 +1,36 @@
+"use strict";
+
+var path = require("path");
+var os   = require("os");
+var fs   = require("fs");
+
+var FILENAME = path.join(os.tmpdir(), "6to5.json");
+var data = {};
+
+exports.save = function () {
+  fs.writeFileSync(FILENAME, JSON.stringify(data, null, "  "));
+};
+
+exports.load = function () {
+  if (!fs.existsSync(FILENAME)) return;
+
+  try {
+    data = JSON.parse(fs.readFileSync(FILENAME));
+  } catch (err) {
+    return;
+  }
+
+  process.on("exit", exports.save);
+
+  var sigint = function () {
+    process.removeListener("SIGINT", sigint);
+    exports.save();
+    process.kill(process.pid, "SIGINT");
+  };
+
+  process.on("SIGINT", sigint);
+};
+
+exports.get = function () {
+  return data;
+};

lib/6to5/register.js

@@ -1,12 +1,17 @@
+"use strict";
+
 require("./polyfill");
 
 var sourceMapSupport = require("source-map-support");
+var registerCache    = require("./register-cache");
+var util             = require("./util");
 var to5              = require("./index");
+var fs               = require("fs");
 var _                = require("lodash");
 
 sourceMapSupport.install({
   retrieveSourceMap: function (source) {
-    var map = maps[source];
+    var map = maps && maps[source];
     if (map) {
       return {
         url: null,
@@ -20,19 +25,47 @@ sourceMapSupport.install({
 
 //
 
-var ignoreRegex = /node_modules/;
-var exts        = {};
-var maps        = {};
-var old         = require.extensions[".js"];
+registerCache.load();
+var cache = registerCache.get();
+
+//
+
+var transformOpts = {};
+var ignoreRegex   = /node_modules/;
+var onlyRegex;
+var whitelist     = [];
+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)) {
+  if ((ignoreRegex && ignoreRegex.test(filename)) || (onlyRegex && !onlyRegex.test(filename))) {
     return old.apply(this, arguments);
   }
 
-  var result = to5.transformFileSync(filename, {
-    sourceMap: true
-  });
+  var result;
+
+  if (cache) {
+    var cached = cache[filename];
+    if (cached && cached.mtime === mtime(filename)) {
+      result = cached;
+    }
+  }
+
+  result = result || to5.transformFileSync(filename, _.extend({
+    whitelist: whitelist,
+    sourceMap: true,
+    ast:       false
+  }, transformOpts));
+
+  if (cache) {
+    result.mtime = mtime(filename);
+    cache[filename] = result;
+  }
 
   maps[filename] = result.map;
 
@@ -52,15 +85,23 @@ var hookExtensions = function (_exts) {
   });
 };
 
-hookExtensions([".es6", ".js"]);
+hookExtensions(util.canCompile.EXTENSIONS);
 
 module.exports = function (opts) {
+  // normalise options
   opts = opts || {};
-  if (_.isRegExp(opts)) opts = { ignoreRegex: opts };
 
-  if (opts.ignoreRegex != null) {
-    ignoreRegex = opts.ignoreRegex;
-  }
+  if (opts.only != null) onlyRegex = util.regexify(opts.only);
+  if (opts.ignore != null) ignoreRegex = util.regexify(opts.ignore);
 
-  if (opts.extensions) hookExtensions(opts.extensions);
+  if (opts.extensions) hookExtensions(util.arrayify(opts.extensions));
+
+  if (opts.cache === false) cache = null;
+
+  delete opts.extensions;
+  delete opts.ignore;
+  delete opts.cache;
+  delete opts.only;
+
+  _.extend(transformOpts, opts);
 };

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-comprehension-filter.js

@@ -1,5 +0,0 @@
-ARRAY.filter(function (KEY) {
-  return FILTER;
-}).map(function (KEY) {
-  return STATEMENT;
-});

lib/6to5/templates/array-comprehension-for-each.js

@@ -1,3 +0,0 @@
-ARRAY.forEach(function (KEY) {
-
-});

lib/6to5/templates/array-comprehension-map.js

@@ -1,3 +0,0 @@
-ARRAY.map(function (KEY) {
-  return STATEMENT;
-});

lib/6to5/templates/class-super-constructor-call.js

@@ -1,2 +0,0 @@
-SUPER_NAME.apply(this, arguments);
-

lib/6to5/templates/class.js

@@ -1,7 +0,0 @@
-(function () {
-  var CLASS_NAME = function () {
-
-  };
-
-  return CLASS_NAME;
-})()

lib/6to5/templates/exports-assign-key.js

@@ -1 +0,0 @@
-exports.VARIABLE_NAME = OBJECT.KEY;

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

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

lib/6to5/templates/exports-wildcard.js

@@ -1,5 +0,0 @@
-(function (obj) {
-  for (var i in obj) {
-    exports[i] = obj[i];
-  }
-})(OBJECT);

lib/6to5/templates/extends.js

@@ -1,11 +0,0 @@
-(function (child, parent) {
-  child.prototype = Object.create(parent.prototype, {
-    constructor: {
-      value: child,
-      enumerable: false,
-      writable: true,
-      configurable: true
-    }
-  });
-  child.__proto__ = parent;
-})

lib/6to5/templates/function-return-obj.js

@@ -1,3 +0,0 @@
-(function (KEY) {
-  return KEY;
-})(OBJECT)

lib/6to5/templates/if-undefined-set-to.js

@@ -1 +0,0 @@
-if (VARIABLE === undefined) VARIABLE = DEFAULT;

lib/6to5/templates/object-define-properties-closure.js

@@ -1,4 +0,0 @@
-(function (KEY) {
-  CONTENT;
-  return KEY;
-})(OBJECT);

lib/6to5/templates/object-define-properties.js

@@ -1 +0,0 @@
-Object.defineProperties(OBJECT, PROPS);

lib/6to5/templates/require-assign.js

@@ -1 +0,0 @@
-var VARIABLE_NAME = require(MODULE_NAME);

lib/6to5/transform.js

@@ -1,118 +0,0 @@
-module.exports = transform;
-
-var Transformer = require("./transformer");
-var sourceMap   = require("source-map");
-var recast      = require("acorn-recast");
-var File        = require("./file");
-var util        = require("./util");
-var _           = require("lodash");
-
-function transform(code, opts) {
-  opts = opts || {};
-  code = (code || "") + "";
-
-  var file = new File(opts);
-  return file.parse(code);
-}
-
-transform.test = function (task, assert) {
-  var actual = task.actual;
-  var expect = task.expect;
-  var opts   = task.options;
-  var exec   = task.exec;
-
-  var getOpts = function (filename) {
-    return _.merge({ filename: filename }, opts);
-  };
-
-  var execCode = exec.code.trim();
-  var result;
-
-  if (execCode) {
-    result = transform(execCode, getOpts(exec.filename));
-    execCode = result.code;
-
-    require("./polyfill");
-    var fn = new Function("assert", execCode);
-    fn(assert);
-  } else {
-    var actualCode = actual.code.trim();
-    var expectCode = expect.code.trim();
-
-    var printOpts = { tabWidth: 2 };
-
-    result     = transform(actualCode, getOpts(actual.filename));
-    actualCode = recast.prettyPrint(result.ast, printOpts).code;
-
-    var expectAst    = util.parse(expect, expectCode);
-    var expectResult = recast.prettyPrint(expectAst, printOpts);
-    expectCode       = expectResult.code;
-
-    assert.equal(actualCode, expectCode);
-  }
-
-  if (task.sourceMap) {
-    assert.deepEqual(task.sourceMap, result.map);
-  }
-
-  if (task.sourceMappings) {
-    var consumer = new sourceMap.SourceMapConsumer(result.map);
-
-    _.each(task.sourceMappings, function (mapping, i) {
-      var generated = mapping.generated;
-      var original  = mapping.original;
-
-      var pos = consumer.originalPositionFor(generated);
-      var msg = "source mapping " + i + " - generated: " + generated.line + ":" + generated.column;
-      assert.equal(pos.line + ":" + pos.column, original.line + ":" + original.column, msg);
-    });
-  }
-};
-
-transform._ensureTransformerNames = function (type, keys) {
-  _.each(keys, function (key) {
-    if (!_.has(transform.transformers, key)) {
-      throw new ReferenceError("unknown transformer " + key + " specified in " + type);
-    }
-  });
-};
-
-transform.transformers = {
-  modules:                  require("./transformers/modules"),
-  computedPropertyNames:    require("./transformers/computed-property-names"),
-  propertyNameShorthand:    require("./transformers/property-name-shorthand"),
-  constants:                require("./transformers/constants"),
-  arrayComprehension:       require("./transformers/array-comprehension"),
-  arrowFunctions:           require("./transformers/arrow-functions"),
-  classes:                  require("./transformers/classes"),
-  spread:                   require("./transformers/spread"),
-  templateLiterals:         require("./transformers/template-literals"),
-  propertyMethodAssignment: require("./transformers/property-method-assignment"),
-  defaultParameters:        require("./transformers/default-parameters"),
-  letScoping:               require("./transformers/let-scoping"),
-  restParameters:           require("./transformers/rest-parameters"),
-  destructuring:            require("./transformers/destructuring"),
-  forOf:                    require("./transformers/for-of"),
-  unicodeRegex:             require("./transformers/unicode-regex"),
-  generators:               require("./transformers/generators"),
-
-  react:                    require("./transformers/react"),
-  jsx:                      require("./transformers/jsx"),
-
-  _aliasFunctions:          require("./transformers/_alias-functions"),
-  _blockHoist:              require("./transformers/_block-hoist"),
-  _declarations:            require("./transformers/_declarations"),
-  _moduleFormatter:         require("./transformers/_module-formatter"),
-
-  useStrict:                require("./transformers/use-strict")
-};
-
-transform.moduleFormatters = {
-  common: require("./modules/common"),
-  amd:    require("./modules/amd"),
-  umd:    require("./modules/umd")
-};
-
-_.each(transform.transformers, function (transformer, key) {
-  transform.transformers[key] = new Transformer(key, transformer);
-});

lib/6to5/transformation/helpers/build-binary-assignment-operator-transformer.js

@@ -0,0 +1,46 @@
+"use strict";
+
+var explode = require("./explode-assignable-expression");
+var t       = require("../../types");
+
+module.exports = function (exports, opts) {
+  var isAssignment = function (node) {
+    return node.operator === opts.operator + "=";
+  };
+
+  var buildAssignment = function (left, right) {
+    return t.assignmentExpression("=", left, right);
+  };
+
+  exports.ExpressionStatement = function (node, parent, scope, context, file) {
+    // hit the `AssignmentExpression` one below
+    if (file.isConsequenceExpressionStatement(node)) return;
+
+    var expr = node.expression;
+    if (!isAssignment(expr)) return;
+
+    var nodes    = [];
+    var exploded = explode(expr.left, nodes, file, scope, true);
+
+    nodes.push(t.expressionStatement(
+      buildAssignment(exploded.ref, opts.build(exploded.uid, expr.right))
+    ));
+
+    return nodes;
+  };
+
+  exports.AssignmentExpression = function (node, parent, scope, context, file) {
+    if (!isAssignment(node)) return;
+
+    var nodes    = [];
+    var exploded = explode(node.left, nodes, file, scope);
+    nodes.push(buildAssignment(exploded.ref, opts.build(exploded.uid, node.right)));
+
+    return t.toSequenceExpression(nodes, scope);
+  };
+
+  exports.BinaryExpression = function (node) {
+    if (node.operator !== opts.operator) return;
+    return opts.build(node.left, node.right);
+  };
+};

lib/6to5/transformation/helpers/build-comprehension.js

@@ -0,0 +1,25 @@
+"use strict";
+
+var t = require("../../types");
+
+module.exports = function build(node, buildBody) {
+  var self = node.blocks.shift();
+  if (!self) return;
+
+  var child = build(node, buildBody);
+  if (!child) {
+    // last item
+    child = buildBody();
+
+    // add a filter as this is our final stop
+    if (node.filter) {
+      child = t.ifStatement(node.filter, t.blockStatement([child]));
+    }
+  }
+
+  return t.forOfStatement(
+    t.variableDeclaration("let", [t.variableDeclarator(self.left)]),
+    self.right,
+    t.blockStatement([child])
+  );
+};

lib/6to5/transformation/helpers/build-conditional-assignment-operator-transformer.js

@@ -0,0 +1,47 @@
+"use strict";
+
+var explode = require("./explode-assignable-expression");
+var t       = require("../../types");
+
+module.exports = function (exports, opts) {
+  var buildAssignment = function (left, right) {
+    return t.assignmentExpression("=", left, right);
+  };
+
+  exports.ExpressionStatement = function (node, parent, scope, context, file) {
+    // hit the `AssignmentExpression` one below
+    if (file.isConsequenceExpressionStatement(node)) return;
+
+    var expr = node.expression;
+    if (!opts.is(expr, file)) return;
+
+    var nodes = [];
+
+    var exploded = explode(expr.left, nodes, file, scope);
+
+    nodes.push(t.ifStatement(
+      opts.build(exploded.uid, file),
+      t.expressionStatement(buildAssignment(exploded.ref, expr.right))
+    ));
+
+    return nodes;
+  };
+
+  exports.AssignmentExpression = function (node, parent, scope, context, file) {
+    if (!opts.is(node, file)) return;
+
+    var nodes    = [];
+    var exploded = explode(node.left, nodes, file, scope);
+
+    nodes.push(t.logicalExpression(
+      "&&",
+      opts.build(exploded.uid, file),
+      buildAssignment(exploded.ref, node.right)
+    ));
+
+    // todo: duplicate expression node
+    nodes.push(exploded.ref);
+
+    return t.toSequenceExpression(nodes, scope);
+  };
+};

lib/6to5/transformation/helpers/explode-assignable-expression.js

@@ -0,0 +1,73 @@
+"use strict";
+
+var t = require("../../types");
+
+var getObjRef = function (node, nodes, file, scope) {
+  var ref;
+  if (t.isIdentifier(node)) {
+    if (scope.has(node.name, true)) {
+      // this variable is declared in scope so we can be 100% sure
+      // that evaluating it multiple times wont trigger a getter
+      // or something else
+      return node;
+    } else {
+      // could possibly trigger a getter so we need to only evaluate
+      // it once
+      ref = node;
+    }
+  } else if (t.isMemberExpression(node)) {
+    ref = node.object;
+
+    if (t.isIdentifier(ref) && scope.has(ref.name)) {
+      // the object reference that we need to save is locally declared
+      // so as per the previous comment we can be 100% sure evaluating
+      // it multiple times will be safe
+      return ref;
+    }
+  } else {
+    throw new Error("We can't explode this node type " + node.type);
+  }
+
+  var temp = scope.generateUidBasedOnNode(ref);
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(temp, ref)
+  ]));
+  return temp;
+};
+
+var getPropRef = function (node, nodes, file, scope) {
+  var prop = node.property;
+  var key = t.toComputedKey(node, prop);
+  if (t.isLiteral(key)) return key;
+
+  var temp = scope.generateUidBasedOnNode(prop);
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(temp, prop)
+  ]));
+  return temp;
+};
+
+module.exports = function (node, nodes, file, scope, allowedSingleIdent) {
+  var obj;
+  if (t.isIdentifier(node) && allowedSingleIdent) {
+    obj = node;
+  } else {
+    obj = getObjRef(node, nodes, file, scope);
+  }
+
+  var ref, uid;
+
+  if (t.isIdentifier(node)) {
+    ref = node;
+    uid = obj;
+  } else {
+    var prop = getPropRef(node, nodes, file, scope);
+    var computed = node.computed || t.isLiteral(prop);
+    uid = ref = t.memberExpression(obj, prop, computed);
+  }
+
+  return {
+    uid: uid,
+    ref: ref
+  };
+};

lib/6to5/transformation/helpers/name-method.js

@@ -0,0 +1,51 @@
+"use strict";
+
+var traverse = require("../../traverse");
+var util     = require("../../util");
+var t        = require("../../types");
+
+var visitor = {
+  enter: function (node, parent, scope, context, state) {
+    // check if this node is an identifier that matches the same as our function id
+    if (!t.isIdentifier(node, { name: state.id })) return;
+
+    // check if this node is the one referenced
+    if (!t.isReferenced(node, parent)) return;
+
+    // check that we don't have a local variable declared as that removes the need
+    // for the wrapper
+    var localDeclar = scope.get(state.id, true);
+    if (localDeclar !== state.outerDeclar) return;
+
+    state.selfReference = true;
+    context.stop();
+  }
+};
+
+exports.property = function (node, file, scope) {
+  var key = t.toComputedKey(node, node.key);
+  if (!t.isLiteral(key)) return node; // we can't set a function id with this
+
+  var id = t.toIdentifier(key.value);
+  key = t.identifier(id);
+
+  var state = {
+    id: id,
+    selfReference: false,
+    outerDeclar: scope.get(id, true),
+  };
+
+  traverse(node, visitor, scope, state);
+
+  if (state.selfReference) {
+    // todo: support generators
+    node.value = util.template("property-method-assignment-wrapper", {
+      FUNCTION: node.value,
+      FUNCTION_ID: key,
+      FUNCTION_KEY: scope.generateUidIdentifier(id),
+      WRAPPER_KEY: scope.generateUidIdentifier(id + "Wrapper")
+    });
+  } else {
+    node.value.id = key;
+  }
+};

lib/6to5/transformation/helpers/remap-async-to-generator.js

@@ -0,0 +1,35 @@
+"use strict";
+
+var traverse = require("../../traverse");
+var t        = require("../../types");
+
+var visitor = {
+  enter: function (node, parent, scope, context) {
+    if (t.isFunction(node)) context.skip();
+
+    if (t.isAwaitExpression(node)) {
+      node.type = "YieldExpression";
+    }
+  }
+};
+
+module.exports = function (node, callId, scope) {
+  node.async = false;
+  node.generator = true;
+
+  traverse(node, visitor, scope);
+
+  var call = t.callExpression(callId, [node]);
+  var id = node.id;
+  delete node.id;
+
+  if (t.isFunctionDeclaration(node)) {
+    var declar = t.variableDeclaration("let", [
+      t.variableDeclarator(id, call)
+    ]);
+    declar._blockHoist = true;
+    return declar;
+  } else {
+    return call;
+  }
+};

lib/6to5/transformation/helpers/replace-supers.js

@@ -0,0 +1,251 @@
+"use strict";
+
+module.exports = ReplaceSupers;
+
+var traverse = require("../../traverse");
+var t        = require("../../types");
+
+/**
+ * Description
+ *
+ * @param {Object} opts
+ */
+
+function ReplaceSupers(opts) {
+  this.topLevelThisReference = null;
+  this.methodNode            = opts.methodNode;
+  this.className             = opts.className;
+  this.superName             = opts.superName;
+  this.isLoose               = opts.isLoose;
+  this.scope                 = opts.scope;
+  this.file                  = opts.file;
+}
+
+/**
+ * Gets a node representing the super class value of the named property.
+ *
+ * @example
+ *
+ *   _get(Object.getPrototypeOf(CLASS.prototype), "METHOD", this)
+ *
+ * @param {Node} property
+ * @param {boolean} isStatic
+ * @param {boolean} isComputed
+ *
+ * @returns {Node}
+ */
+
+ReplaceSupers.prototype.superProperty = function (property, isStatic, isComputed, thisExpression) {
+  return t.callExpression(
+    this.file.addHelper("get"),
+    [
+      t.callExpression(
+        t.memberExpression(t.identifier("Object"), t.identifier("getPrototypeOf")),
+        [
+          isStatic ? this.className : t.memberExpression(this.className, t.identifier("prototype"))
+        ]
+      ),
+      isComputed ? property : t.literal(property.name),
+      thisExpression
+    ]
+  );
+};
+
+/**
+ * Description
+ *
+ * @param {Object} node
+ * @param {Object} id
+ * @param {Object} parent
+ * @returns {Object}
+ */
+
+ReplaceSupers.prototype.looseSuperProperty = function (methodNode, id, parent) {
+  var methodName = methodNode.key;
+  var superName  = this.superName || t.identifier("Function");
+
+  if (parent.property === id) {
+    return;
+  } else if (t.isCallExpression(parent, { callee: id })) {
+    // super(); -> ClassName.prototype.MethodName.call(this);
+    parent.arguments.unshift(t.thisExpression());
+
+    if (methodName.name === "constructor") {
+      // constructor() { super(); }
+      return t.memberExpression(superName, t.identifier("call"));
+    } else {
+      id = superName;
+
+      // foo() { super(); }
+      if (!methodNode.static) {
+        id = t.memberExpression(id, t.identifier("prototype"));
+      }
+
+      id = t.memberExpression(id, methodName, methodNode.computed);
+      return t.memberExpression(id, t.identifier("call"));
+    }
+  } else if (t.isMemberExpression(parent) && !methodNode.static) {
+    // super.test -> ClassName.prototype.test
+    return t.memberExpression(superName, t.identifier("prototype"));
+  } else {
+    return superName;
+  }
+};
+
+/**
+ * Description
+ */
+
+ReplaceSupers.prototype.replace = function () {
+  this.traverseLevel(this.methodNode.value, true);
+};
+
+var visitor = {
+  enter: function (node, parent, scope, context, state) {
+    var topLevel = state.topLevel;
+    var self = state.self;
+
+    if (t.isFunction(node) && !t.isArrowFunctionExpression(node)) {
+      // we need to call traverseLevel again so we're context aware
+      self.traverseLevel(node, false);
+      return context.skip();
+    }
+
+    if (t.isProperty(node, { method: true }) || t.isMethodDefinition(node)) {
+      // break on object methods
+      return context.skip();
+    }
+
+    var getThisReference = topLevel ?
+      // top level so `this` is the instance
+      t.thisExpression :
+      // not in the top level so we need to create a reference
+      self.getThisReference;
+
+    var callback = self.specHandle;
+    if (self.isLoose) callback = self.looseHandle;
+    return callback.call(self, getThisReference, node, parent);
+  }
+};
+
+/**
+ * Description
+ *
+ * @param {Object} node
+ * @param {Boolean} topLevel
+ */
+
+ReplaceSupers.prototype.traverseLevel = function (node, topLevel) {
+  var state = { self: this, topLevel: topLevel };
+  traverse(node, visitor, this.scope, state);
+};
+
+/**
+ * Description
+ */
+
+ReplaceSupers.prototype.getThisReference = function () {
+  if (this.topLevelThisReference) {
+    return this.topLevelThisReference;
+  } else {
+    var ref = this.topLevelThisReference = this.file.generateUidIdentifier("this");
+    this.methodNode.value.body.body.unshift(t.variableDeclaration("var", [
+      t.variableDeclarator(this.topLevelThisReference, t.thisExpression())
+    ]));
+    return ref;
+  }
+};
+
+/**
+ * Description
+ *
+ * @param {Function} getThisReference
+ * @param {Object} node
+ * @param {Object} parent
+ */
+
+ReplaceSupers.prototype.looseHandle = function (getThisReference, node, parent) {
+  if (t.isIdentifier(node, { name: "super" })) {
+    return this.looseSuperProperty(this.methodNode, node, parent);
+  } else if (t.isCallExpression(node)) {
+    var callee = node.callee;
+    if (!t.isMemberExpression(callee)) return;
+    if (callee.object.name !== "super") return;
+
+    // super.test(); -> ClassName.prototype.MethodName.call(this);
+    t.appendToMemberExpression(callee, t.identifier("call"));
+    node.arguments.unshift(getThisReference());
+  }
+};
+
+/**
+ * Description
+ *
+ * @param {Function} getThisReference
+ * @param {Object} node
+ * @param {Object} parent
+ */
+
+ReplaceSupers.prototype.specHandle = function (getThisReference, node, parent) {
+  var methodNode = this.methodNode;
+  var property;
+  var computed;
+  var args;
+
+  if (t.isIdentifier(node, { name: "super" })) {
+    if (!(t.isMemberExpression(parent) && !parent.computed && parent.property === node)) {
+      throw this.file.errorWithNode(node, "illegal use of bare super");
+    }
+  } else if (t.isCallExpression(node)) {
+    var callee = node.callee;
+    if (t.isIdentifier(callee, { name: "super" })) {
+      // super(); -> _get(Object.getPrototypeOf(ClassName), "MethodName", this).call(this);
+      property = methodNode.key;
+      computed = methodNode.computed;
+      args = node.arguments;
+
+      // bare `super` call is illegal inside non-constructors
+      //  - https://esdiscuss.org/topic/super-call-in-methods
+      //  - https://twitter.com/wycats/status/544553184396836864
+      if (methodNode.key.name !== "constructor") {
+        var methodName = methodNode.key.name || "METHOD_NAME";
+        throw this.file.errorWithNode(node, "Direct super call is illegal in non-constructor, use super." + methodName + "() instead");
+      }
+    } else {
+      if (!t.isMemberExpression(callee)) return;
+      if (callee.object.name !== "super") return;
+
+      // super.test(); -> _get(Object.getPrototypeOf(ClassName.prototype), "test", this).call(this);
+      property = callee.property;
+      computed = callee.computed;
+      args = node.arguments;
+    }
+  } else if (t.isMemberExpression(node)) {
+    if (!t.isIdentifier(node.object, { name: "super" })) return;
+
+    // super.name; -> _get(Object.getPrototypeOf(ClassName.prototype), "name", this);
+    property = node.property;
+    computed = node.computed;
+  }
+
+  if (!property) return;
+
+  var thisReference = getThisReference();
+  var superProperty = this.superProperty(property, methodNode.static, computed, thisReference);
+  if (args) {
+    if (args.length === 1 && t.isSpreadElement(args[0])) {
+      // super(...arguments);
+      return t.callExpression(
+        t.memberExpression(superProperty, t.identifier("apply")),
+        [thisReference, args[0].argument]
+      );
+    } else {
+      return t.callExpression(
+        t.memberExpression(superProperty, t.identifier("call")),
+        [thisReference].concat(args)
+      );
+    }
+  } else {
+    return superProperty;
+  }
+};

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

@@ -0,0 +1,21 @@
+"use strict";
+
+var t = require("../../types");
+
+exports.has = function (node) {
+  var first = node.body[0];
+  return t.isExpressionStatement(first) && t.isLiteral(first.expression, { value: "use strict" });
+};
+
+exports.wrap = function (node, callback) {
+  var useStrictNode;
+  if (exports.has(node)) {
+    useStrictNode = node.body.shift();
+  }
+
+  callback();
+
+  if (useStrictNode) {
+    node.body.unshift(useStrictNode);
+  }
+};

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

@@ -0,0 +1,295 @@
+"use strict";
+
+module.exports = DefaultFormatter;
+
+var traverse = require("../../traverse");
+var object   = require("../../helpers/object");
+var util     = require("../../util");
+var t        = require("../../types");
+var _        = require("lodash");
+
+function DefaultFormatter(file) {
+  this.file = file;
+  this.ids  = object();
+
+  this.hasNonDefaultExports = false;
+
+  this.hasLocalExports = false;
+  this.hasLocalImports = false;
+
+  this.localImportOccurences = object();
+  this.localExports = object();
+  this.localImports = object();
+
+  this.getLocalExports();
+  this.getLocalImports();
+
+  this.remapAssignments();
+}
+
+DefaultFormatter.prototype.doDefaultExportInterop = function (node) {
+  return node.default && !this.noInteropRequire && !this.hasNonDefaultExports;
+};
+
+DefaultFormatter.prototype.bumpImportOccurences = function (node) {
+  var source = node.source.value;
+  var occurs = this.localImportOccurences;
+  occurs[source] = occurs[source] || 0;
+  occurs[source] += node.specifiers.length;
+};
+
+var exportsVisitor = {
+  enter: function (node, parent, scope, context, formatter) {
+    var declar = node && node.declaration;
+    if (t.isExportDeclaration(node)) {
+      formatter.hasLocalImports = true;
+
+      if (declar && t.isStatement(declar)) {
+        _.extend(formatter.localExports, t.getIds(declar, true));
+      }
+
+      if (!node.default) {
+        formatter.hasNonDefaultExports = true;
+      }
+
+      if (node.source) {
+        formatter.bumpImportOccurences(node);
+      }
+    }
+  }
+};
+
+DefaultFormatter.prototype.getLocalExports = function () {
+  traverse(this.file.ast, exportsVisitor, this.file.scope, this);
+};
+
+var importsVisitor = {
+  enter: function (node, parent, scope, context, formatter) {
+    if (t.isImportDeclaration(node)) {
+      formatter.hasLocalImports = true;
+      _.extend(formatter.localImports, t.getIds(node, true));
+      formatter.bumpImportOccurences(node);
+    }
+  }
+};
+
+DefaultFormatter.prototype.getLocalImports = function () {
+  traverse(this.file.ast, importsVisitor, this.file.scope, this);
+};
+
+var remapVisitor = {
+  enter: function (node, parent, scope, context, formatter) {
+    if (t.isUpdateExpression(node) && formatter.isLocalReference(node.argument, scope)) {
+      context.skip();
+
+      // expand to long file assignment expression
+      var assign = t.assignmentExpression(node.operator[0] + "=", node.argument, t.literal(1));
+
+      // remap this assignment expression
+      var remapped = formatter.remapExportAssignment(assign);
+
+      // we don't need to change the result
+      if (t.isExpressionStatement(parent) || node.prefix) {
+        return remapped;
+      }
+
+      var nodes = [];
+      nodes.push(remapped);
+
+      var operator;
+      if (node.operator === "--") {
+        operator = "+";
+      } else { // "++"
+        operator = "-";
+      }
+      nodes.push(t.binaryExpression(operator, node.argument, t.literal(1)));
+
+      return t.sequenceExpression(nodes);
+    }
+
+    if (t.isAssignmentExpression(node) && formatter.isLocalReference(node.left, scope)) {
+      context.skip();
+      return formatter.remapExportAssignment(node);
+    }
+  }
+};
+
+DefaultFormatter.prototype.remapAssignments = function () {
+  if (this.hasLocalImports) {
+    traverse(this.file.ast, remapVisitor, this.file.scope, this);
+  }
+};
+
+DefaultFormatter.prototype.isLocalReference = function (node) {
+  var localImports = this.localImports;
+  return t.isIdentifier(node) && localImports[node.name] && localImports[node.name] !== node;
+};
+
+DefaultFormatter.prototype.checkLocalReference = function (node) {
+  var file = this.file;
+  if (this.isLocalReference(node)) {
+    throw file.errorWithNode(node, "Illegal assignment of module import");
+  }
+};
+
+DefaultFormatter.prototype.remapExportAssignment = function (node) {
+  return t.assignmentExpression(
+    "=",
+    node.left,
+    t.assignmentExpression(
+      node.operator,
+      t.memberExpression(t.identifier("exports"), node.left),
+      node.right
+    )
+  );
+};
+
+DefaultFormatter.prototype.isLocalReference = function (node, scope) {
+  var localExports = this.localExports;
+  var name = node.name;
+  return t.isIdentifier(node) && localExports[name] && localExports[name] === scope.get(name, true);
+};
+
+DefaultFormatter.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, "");
+  }
+
+  if (!opts.keepModuleIdExtensions) {
+    // remove extension
+    filenameRelative = filenameRelative.replace(/\.(.*?)$/, "");
+  }
+
+  moduleName += filenameRelative;
+
+  // normalise path separators
+  moduleName = moduleName.replace(/\\/g, "/");
+
+  return moduleName;
+};
+
+DefaultFormatter.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;
+};
+
+DefaultFormatter.prototype._hoistExport = function (declar, assign, priority) {
+  if (t.isFunctionDeclaration(declar)) {
+    assign._blockHoist = priority || 2;
+  }
+
+  return assign;
+};
+
+DefaultFormatter.prototype.getExternalReference = function (node, nodes) {
+  var ids = this.ids;
+  var id = node.source.value;
+
+  if (ids[id]) {
+    return ids[id];
+  } else {
+    return this.ids[id] = this._getExternalReference(node, nodes);
+  }
+};
+
+DefaultFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
+  var inherits = false;
+  if (node.specifiers.length === 1) inherits = node;
+
+  if (node.source) {
+    var ref = this.getExternalReference(node, nodes);
+
+    if (t.isExportBatchSpecifier(specifier)) {
+      // export * from "foo";
+      nodes.push(this.buildExportsWildcard(ref, node));
+    } else {
+      if (t.isSpecifierDefault(specifier) && !this.noInteropRequire) {
+        // importing a default so we need to normalise it
+        ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
+      } else {
+        ref = t.memberExpression(ref, t.getSpecifierId(specifier));
+      }
+
+      // export { foo } from "test";
+      nodes.push(this.buildExportsAssignment(
+        t.getSpecifierName(specifier),
+        ref,
+        node
+      ));
+    }
+  } else {
+    // export { foo };
+    nodes.push(this.buildExportsAssignment(t.getSpecifierName(specifier), specifier.id, node));
+  }
+};
+
+DefaultFormatter.prototype.buildExportsWildcard = function (objectIdentifier) {
+  return t.expressionStatement(t.callExpression(this.file.addHelper("defaults"), [
+    t.identifier("exports"),
+    t.callExpression(this.file.addHelper("interop-require-wildcard"), [objectIdentifier])
+  ]));
+};
+
+DefaultFormatter.prototype.buildExportsAssignment = function (id, init) {
+  return util.template("exports-assign", {
+    VALUE: init,
+    KEY:   id
+  }, true);
+};
+
+DefaultFormatter.prototype.exportDeclaration = function (node, nodes) {
+  var declar = node.declaration;
+
+  var id = declar.id;
+
+  if (node.default) {
+    id = t.identifier("default");
+  }
+
+  var assign;
+
+  if (t.isVariableDeclaration(declar)) {
+    for (var i = 0; i < declar.declarations.length; i++) {
+      var decl = declar.declarations[i];
+
+      decl.init = this.buildExportsAssignment(decl.id, decl.init, node).expression;
+
+      var newDeclar = t.variableDeclaration(declar.kind, [decl]);
+      if (i === 0) t.inherits(newDeclar, declar);
+      nodes.push(newDeclar);
+    }
+  } else {
+    var ref = declar;
+
+    if (t.isFunctionDeclaration(declar) || t.isClassDeclaration(declar)) {
+      ref = declar.id;
+      nodes.push(declar);
+    }
+
+    assign = this.buildExportsAssignment(id, ref, node);
+
+    nodes.push(assign);
+
+    this._hoistExport(declar, assign);
+  }
+};

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

@@ -0,0 +1,14 @@
+"use strict";
+
+var util = require("../../util");
+
+module.exports = function (Parent) {
+  var Constructor = function () {
+    this.noInteropRequire = true;
+    Parent.apply(this, arguments);
+  };
+
+  util.inherits(Constructor, Parent);
+
+  return Constructor;
+};

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

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_strict")(require("./amd"));

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

@@ -0,0 +1,107 @@
+"use strict";
+
+module.exports = AMDFormatter;
+
+var DefaultFormatter = require("./_default");
+var CommonFormatter  = require("./common");
+var util             = require("../../util");
+var t                = require("../../types");
+var _                = require("lodash");
+
+function AMDFormatter() {
+  CommonFormatter.apply(this, arguments);
+}
+
+util.inherits(AMDFormatter, DefaultFormatter);
+
+AMDFormatter.prototype.buildDependencyLiterals = function () {
+  var names = [];
+  for (var name in this.ids) {
+    names.push(t.literal(name));
+  }
+  return names;
+};
+
+/**
+ * Wrap the entire body in a `define` wrapper.
+ */
+
+AMDFormatter.prototype.transform = function (ast) {
+  var program = ast.program;
+  var body    = program.body;
+
+  // build an array of module names
+
+  var names = [t.literal("exports")];
+  if (this.passModuleArg) names.push(t.literal("module"));
+  names = names.concat(this.buildDependencyLiterals());
+  names = t.arrayExpression(names);
+
+  // build up define container
+
+  var params = _.values(this.ids);
+  if (this.passModuleArg) params.unshift(t.identifier("module"));
+  params.unshift(t.identifier("exports"));
+
+  var container = t.functionExpression(null, params, t.blockStatement(body));
+
+  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)];
+};
+
+/**
+ * Get the AMD module name that we'll prepend to the wrapper
+ * to define this module
+ */
+
+AMDFormatter.prototype.getModuleName = function () {
+  if (this.file.opts.moduleIds) {
+    return DefaultFormatter.prototype.getModuleName.apply(this, arguments);
+  } else {
+    return null;
+  }
+};
+
+AMDFormatter.prototype._getExternalReference = function (node) {
+  return this.file.generateUidIdentifier(node.source.value);
+};
+
+AMDFormatter.prototype.importDeclaration = function (node) {
+  this.getExternalReference(node);
+};
+
+AMDFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
+  var key = t.getSpecifierName(specifier);
+  var ref = this.getExternalReference(node);
+
+  if (_.contains(this.file.dynamicImported, node)) {
+    // Prevent unnecessary renaming of dynamic imports.
+    this.ids[node.source.value] = key;
+    return;
+  } else if (t.isImportBatchSpecifier(specifier)) {
+    // import * as bar from "foo";
+  } else if (t.isSpecifierDefault(specifier) && !this.noInteropRequire) {
+    // import foo from "foo";
+    ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
+  } else {
+    // import {foo} from "foo";
+    ref = t.memberExpression(ref, t.getSpecifierId(specifier), false);
+  }
+
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(key, ref)
+  ]));
+};
+
+AMDFormatter.prototype.exportDeclaration = function (node) {
+  if (this.doDefaultExportInterop(node)) {
+    this.passModuleArg = true;
+  }
+
+  CommonFormatter.prototype.exportDeclaration.apply(this, arguments);
+};

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

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_strict")(require("./common"));

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

@@ -0,0 +1,93 @@
+"use strict";
+
+module.exports = CommonJSFormatter;
+
+var DefaultFormatter = require("./_default");
+var util             = require("../../util");
+var t                = require("../../types");
+var _                = require("lodash");
+
+function CommonJSFormatter(file) {
+  DefaultFormatter.apply(this, arguments);
+
+  if (this.hasNonDefaultExports) {
+    file.ast.program.body.push(util.template("exports-module-declaration", true));
+  }
+}
+
+util.inherits(CommonJSFormatter, DefaultFormatter);
+
+CommonJSFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
+  var variableName = t.getSpecifierName(specifier);
+
+  var ref = this.getExternalReference(node, nodes);
+
+  // import foo from "foo";
+  if (t.isSpecifierDefault(specifier)) {
+    if (!_.contains(this.file.dynamicImported, node)) {
+      ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
+    }
+    nodes.push(t.variableDeclaration("var", [t.variableDeclarator(variableName, ref)]));
+  } else {
+    if (specifier.type === "ImportBatchSpecifier") {
+      // import * as bar from "foo";
+      nodes.push(t.variableDeclaration("var", [
+        t.variableDeclarator(
+          variableName,
+          t.callExpression(this.file.addHelper("interop-require-wildcard"), [
+            ref
+          ])
+        )
+      ]));
+    } else {
+      // import { foo } from "foo";
+      nodes.push(t.variableDeclaration("var", [
+        t.variableDeclarator(
+          variableName,
+          t.memberExpression(ref, t.getSpecifierId(specifier))
+        )
+      ]));
+    }
+  }
+};
+
+CommonJSFormatter.prototype.importDeclaration = function (node, nodes) {
+  // import "foo";
+  nodes.push(util.template("require", {
+    MODULE_NAME: node.source
+  }, true));
+};
+
+CommonJSFormatter.prototype.exportDeclaration = function (node, nodes) {
+  if (this.doDefaultExportInterop(node)) {
+    var declar = node.declaration;
+    var assign = util.template("exports-default-assign", {
+      VALUE: this._pushStatement(declar, nodes)
+    }, true);
+
+    if (t.isFunctionDeclaration(declar)) {
+      // we can hoist this assignment to the top of the file
+      assign._blockHoist = 3;
+    }
+
+    nodes.push(assign);
+    return;
+  }
+
+  DefaultFormatter.prototype.exportDeclaration.apply(this, arguments);
+};
+
+CommonJSFormatter.prototype._getExternalReference = function (node, nodes) {
+  var source = node.source.value;
+  var call = t.callExpression(t.identifier("require"), [node.source]);
+
+  if (this.localImportOccurences[source] > 1) {
+    var uid = this.file.generateUidIdentifier(source);
+    nodes.push(t.variableDeclaration("var", [
+      t.variableDeclarator(uid, call)
+    ]));
+    return uid;
+  } else {
+    return call;
+  }
+};

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

@@ -0,0 +1,20 @@
+"use strict";
+
+module.exports = IgnoreFormatter;
+
+var t = require("../../types");
+
+function IgnoreFormatter() {
+
+}
+
+IgnoreFormatter.prototype.exportDeclaration = function (node, nodes) {
+  var declar = t.toStatement(node.declaration, true);
+  if (declar) nodes.push(t.inherits(declar, node));
+};
+
+IgnoreFormatter.prototype.importDeclaration =
+IgnoreFormatter.prototype.importSpecifier =
+IgnoreFormatter.prototype.exportSpecifier = function () {
+
+};

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

@@ -0,0 +1,10 @@
+module.exports = {
+  commonStrict: require("./common-strict"),
+  amdStrict:    require("./amd-strict"),
+  umdStrict:    require("./umd-strict"),
+  common:       require("./common"),
+  system:       require("./system"),
+  ignore:       require("./ignore"),
+  amd:          require("./amd"),
+  umd:          require("./umd")
+};

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

@@ -0,0 +1,199 @@
+"use strict";
+
+module.exports = SystemFormatter;
+
+var DefaultFormatter = require("./_default");
+var AMDFormatter     = require("./amd");
+var useStrict        = require("../helpers/use-strict");
+var traverse         = require("../../traverse");
+var util             = require("../../util");
+var t                = require("../../types");
+var _                = require("lodash");
+
+function SystemFormatter(file) {
+  this.exportIdentifier = file.generateUidIdentifier("export");
+  this.noInteropRequire = true;
+
+  DefaultFormatter.apply(this, arguments);
+}
+
+util.inherits(SystemFormatter, AMDFormatter);
+
+SystemFormatter.prototype._addImportSource = function (node, exportNode) {
+  node._importSource = exportNode.source && exportNode.source.value;
+  return node;
+};
+
+SystemFormatter.prototype.buildExportsWildcard = function (objectIdentifier, node) {
+  var leftIdentifier = this.file.generateUidIdentifier("key");
+  var valIdentifier  = t.memberExpression(objectIdentifier, leftIdentifier, true);
+
+  var left = t.variableDeclaration("var", [
+    t.variableDeclarator(leftIdentifier)
+  ]);
+
+  var right = objectIdentifier;
+
+  var block = t.blockStatement([
+    t.expressionStatement(this.buildExportCall(leftIdentifier, valIdentifier))
+  ]);
+
+  return this._addImportSource(t.forInStatement(left, right, block), node);
+};
+
+SystemFormatter.prototype.buildExportsAssignment = function (id, init, node) {
+  var call = this.buildExportCall(t.literal(id.name), init, true);
+  return this._addImportSource(call, node);
+};
+
+SystemFormatter.prototype.remapExportAssignment = function (node) {
+  return this.buildExportCall(t.literal(node.left.name), node);
+};
+
+SystemFormatter.prototype.buildExportCall = function (id, init, isStatement) {
+  var call = t.callExpression(this.exportIdentifier, [id, init]);
+  if (isStatement) {
+    return t.expressionStatement(call);
+  } else {
+    return call;
+  }
+};
+
+SystemFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
+  AMDFormatter.prototype.importSpecifier.apply(this, arguments);
+  this._addImportSource(_.last(nodes), node);
+};
+
+var runnerSettersVisitor = {
+  enter: function (node, parent, scope, context, state) {
+    if (node._importSource === state.source) {
+      if (t.isVariableDeclaration(node)) {
+        _.each(node.declarations, function (declar) {
+          state.hoistDeclarators.push(t.variableDeclarator(declar.id));
+          state.nodes.push(t.expressionStatement(
+            t.assignmentExpression("=", declar.id, declar.init)
+          ));
+        });
+      } else {
+        state.nodes.push(node);
+      }
+
+      context.remove();
+    }
+  }
+};
+
+SystemFormatter.prototype.buildRunnerSetters = function (block, hoistDeclarators) {
+  var scope = this.file.scope;
+
+  return t.arrayExpression(_.map(this.ids, function (uid, source) {
+    var state = {
+      source:           source,
+      nodes:            [],
+      hoistDeclarators: hoistDeclarators
+    };
+
+    traverse(block, runnerSettersVisitor, scope, state);
+
+    return t.functionExpression(null, [uid], t.blockStatement(state.nodes));
+  }));
+};
+
+var hoistVariablesVisitor = {
+  enter: function (node, parent, scope, context, hoistDeclarators) {
+    if (t.isFunction(node)) {
+      // nothing inside is accessible
+      return context.skip();
+    }
+
+    if (t.isVariableDeclaration(node)) {
+      if (node.kind !== "var" && !t.isProgram(parent)) { // let, const
+        // can't be accessed
+        return;
+      }
+
+      // ignore block hoisted nodes as these can be left in
+      if (node._blockHoist) return;
+
+      var nodes = [];
+
+      for (var i = 0; i < node.declarations.length; i++) {
+        var declar = node.declarations[i];
+        hoistDeclarators.push(t.variableDeclarator(declar.id));
+        if (declar.init) {
+          // no initializer so we can just hoist it as-is
+          var assign = t.expressionStatement(t.assignmentExpression("=", declar.id, declar.init));
+          nodes.push(assign);
+        }
+      }
+
+      // for (var i in test)
+      // for (var i = 0;;)
+      if (t.isFor(parent)) {
+        if (parent.left === node) {
+          return node.declarations[0].id;
+        }
+
+        if (parent.init === node) {
+          return t.toSequenceExpression(nodes, scope);
+        }
+      }
+
+      return nodes;
+    }
+  }
+};
+
+var hoistFunctionsVisitor = {
+  enter: function (node, parent, scope, context, handlerBody) {
+    if (t.isFunction(node)) context.skip();
+
+    if (t.isFunctionDeclaration(node) || node._blockHoist) {
+      handlerBody.push(node);
+      context.remove();
+    }
+  }
+};
+
+SystemFormatter.prototype.transform = function (ast) {
+  var program = ast.program;
+
+  var hoistDeclarators = [];
+  var moduleName = this.getModuleName();
+  var moduleNameLiteral = t.literal(moduleName);
+
+  var block = t.blockStatement(program.body);
+
+  var runner = util.template("system", {
+    MODULE_NAME: moduleNameLiteral,
+    MODULE_DEPENDENCIES: t.arrayExpression(this.buildDependencyLiterals()),
+    EXPORT_IDENTIFIER: this.exportIdentifier,
+    SETTERS: this.buildRunnerSetters(block, hoistDeclarators),
+    EXECUTE: t.functionExpression(null, [], block)
+  }, true);
+
+  var handlerBody = runner.expression.arguments[2].body.body;
+  if (!moduleName) runner.expression.arguments.shift();
+
+  var returnStatement = handlerBody.pop();
+
+  // hoist up all variable declarations
+  traverse(block, hoistVariablesVisitor, this.file.scope, hoistDeclarators);
+
+  if (hoistDeclarators.length) {
+    var hoistDeclar = t.variableDeclaration("var", hoistDeclarators);
+    hoistDeclar._blockHoist = true;
+    handlerBody.unshift(hoistDeclar);
+  }
+
+  // hoist up function declarations for circular references
+  traverse(block, hoistFunctionsVisitor, this.file.scope, handlerBody);
+
+  handlerBody.push(returnStatement);
+
+  if (useStrict.has(block)) {
+    handlerBody.unshift(block.body.shift());
+  }
+
+  program.body = [runner];
+};

lib/6to5/transformation/modules/umd-strict

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_strict")(require("./umd"));

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

@@ -0,0 +1,74 @@
+"use strict";
+
+module.exports = UMDFormatter;
+
+var AMDFormatter = require("./amd");
+var util         = require("../../util");
+var t            = require("../../types");
+var _            = require("lodash");
+
+function UMDFormatter() {
+  AMDFormatter.apply(this, arguments);
+}
+
+util.inherits(UMDFormatter, AMDFormatter);
+
+UMDFormatter.prototype.transform = function (ast) {
+  var program = ast.program;
+  var body    = program.body;
+
+  // build an array of module names
+
+  var names = [];
+  for (var name in this.ids) {
+    names.push(t.literal(name));
+  }
+
+  // factory
+
+  var ids  = _.values(this.ids);
+  var args = [t.identifier("exports")];
+  if (this.passModuleArg) args.push(t.identifier("module"));
+  args = args.concat(ids);
+
+  var factory = t.functionExpression(null, args, t.blockStatement(body));
+
+  // amd
+
+  var defineArgs = [t.literal("exports")];
+  if (this.passModuleArg) defineArgs.push(t.literal("module"));
+  defineArgs = defineArgs.concat(names);
+  defineArgs = [t.arrayExpression(defineArgs)];
+
+  // common
+
+  var testExports = util.template("test-exports");
+  var testModule  = util.template("test-module");
+  var commonTests = this.passModuleArg ? t.logicalExpression("&&", testExports, testModule) : testExports;
+
+  var commonArgs = [t.identifier("exports")];
+  if (this.passModuleArg) commonArgs.push(t.identifier("module"));
+  commonArgs = commonArgs.concat(names.map(function (name) {
+    return t.callExpression(t.identifier("require"), [name]);
+  }));
+
+  // globals
+
+  //var umdArgs = [];
+
+  //
+
+  var moduleName = this.getModuleName();
+  if (moduleName) defineArgs.unshift(t.literal(moduleName));
+
+  var runner = util.template("umd-runner-body", {
+    AMD_ARGUMENTS: defineArgs,
+    COMMON_TEST: commonTests,
+    COMMON_ARGUMENTS: commonArgs
+  });
+
+  //
+
+  var call = t.callExpression(runner, [factory]);
+  program.body = [t.expressionStatement(call)];
+};

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

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