v3.6.2

Conflicts:
	lib/6to5/transformation/transformers/minification/dead-code-elimination.js

.6to5rc

@@ -0,0 +1,5 @@
+{
+  "experimental": true,
+  "playground": true,
+  "loose": true
+}

.editorconfig

@@ -6,6 +6,6 @@ charset = utf-8
 trim_trailing_whitespace = true
 insert_final_newline = true
 
-[*.js]
+[*.{js,json}]
 indent_style = space
 indent_size = 2

.gitignore

@@ -11,3 +11,5 @@ test/tmp
 coverage
 dist
 .package.json
+packages/6to5-runtime/*.js
+packages/6to5-runtime/regenerator/*.js

.gitmodules

@@ -3,7 +3,10 @@
 	url = https://github.com/google/traceur-compiler
 [submodule "vendor/regenerator"]
 	path = vendor/regenerator
-	url = https://github.com/facebook/regenerator
+	url = https://github.com/6to5/regenerator-6to5
 [submodule "vendor/test262"]
 	path = vendor/test262
 	url = https://github.com/tc39/test262
+[submodule "vendor/compat-table"]
+	path = vendor/compat-table
+	url = https://github.com/kangax/compat-table

.istanbul.yml

@@ -0,0 +1,2 @@
+instrumentation:
+  root: lib

.jscsrc

@@ -0,0 +1,58 @@
+{
+  "excludeFiles": ["lib/6to5/transformation/templates"],
+  "disallowSpacesInNamedFunctionExpression": {
+    "beforeOpeningRoundBrace": true
+  },
+  "requireSpacesInAnonymousFunctionExpression": {
+    "beforeOpeningRoundBrace": true
+  },
+  "requireSpacesInAnonymousFunctionExpression": {
+    "beforeOpeningRoundBrace": true
+  },
+  "disallowSpacesInFunctionDeclaration": {
+    "beforeOpeningRoundBrace": true
+  },
+  "disallowSpacesInsideArrayBrackets": true,
+  "disallowSpacesInsideParentheses": 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,
+  "requireLineFeedAtFileEnd": true,
+  "requireCapitalizedConstructors": true,
+  "requireSpacesInForStatement": true,
+  "requireCurlyBraces": [
+    "do"
+  ],
+  "requireSpaceAfterKeywords": [
+    "if",
+    "else",
+    "for",
+    "while",
+    "do",
+    "switch",
+    "case",
+    "return",
+    "try",
+    "catch",
+    "typeof",
+    "function"
+  ],
+  "validateLineBreaks": "LF",
+  "validateQuoteMarks": "\"",
+  "validateIndentation": 2
+}

.jshintignore

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

.jshintrc

@@ -2,6 +2,7 @@
   "esnext": true,
   "indent": 2,
   "freeze": true,
+  "validthis": true,
   "camelcase": true,
   "unused": true,
   "eqnull": true,

.npmignore

@@ -11,3 +11,5 @@ tests.json
 CHANGELOG.md
 .package.json
 coverage
+vendor
+packages

.travis.yml

@@ -3,6 +3,7 @@ language: node_js
 node_js:
   - "0.10"
   - "0.11"
+  - "0.12"
 
 branches:
   except:

CHANGELOG.md

@@ -11,6 +11,389 @@
 
 _Note: Gaps between patch versions are faulty/broken releases._
 
+## 3.6.1
+
+ * **Bug Fix**
+  * Multiline JSX string literals are now supported.
+  * Fix scope tracking import specifiers incorrectly.
+  * Fix templates incorrectly recursing into their replacements.
+ * **Internal**
+  * Type inferrence now extends to function return types.
+  * Upgrade `acorn-6to5`.
+
+## 3.6.0
+
+ * **New Feature**
+  * Add playground class property initializers.
+ * **Polish**
+  * Completely reimplemented scope tracking, can now track types and optimise certain helpers based on it.
+  * Extremely fast tail recursion optimisation implementation. Thanks [@RReverser](https://github.com/RReverser)!
+ * **Internal**
+  * `kexec` has been removed as an optional dependency and must be user installed.
+  * Upgrade `regenerator-6to5`.
+  * Upgrade `acorn-6to5`.
+  * Upgrade `core-js`.
+
+## 3.5.3
+
+ * Enable `es6.tailCall` transformer with the first implementation that only works with self referencing calls until we can implement nested tail calls elegantly.
+
+## 3.5.2
+
+ * Disable `es6.tailCall` temporairly after reports of it breaking.
+
+## 3.5.1
+
+ * **Polish**
+  * Allow tail calls to work across files without the runtime.
+ * **Internal**
+  * Upgrade `acorn-6to5`.
+
+## 3.5.0
+
+ * **Bug Fix**
+  * Destructuring patterns as the left operator in `ForInStatement`/`ForOfStatement`.
+ * **Polish**
+  * Make default parameter IIFE invocation smarter.
+  * Make `__esModule` flag non-enumerable. Thanks [@daliwali](https://github.com/daliwali)!
+ * **Internal**
+  * More performance improvements.
+  * Parsing is now ~30% faster thanks to [marijnh/acorn@7264bc0178e7e6af7cfe02e9e0c6b26ee0e6007f](https://github.com/marijnh/acorn/commit/7264bc0178e7e6af7cfe02e9e0c6b26ee0e6007f).
+ * **New Feature**
+  * Optional `es6.blockScopingTDZ` is now completely functional and handles all edgecases.
+  * `super` in object literals.
+  * Tail call optimisation. Thanks [@RReverser](https://github.com/RReverser)!
+
+## 3.4.1
+
+ * **Bug Fix**
+  * Fix conflicting `--module-ids` shorthand arg in `$ 6to5`.
+  * Add require hook options to cache key.
+  * Fix strict module formatter.
+
+## 3.4.0
+
+ * **New Feature**
+  * Add `commonStandard` module formatter.
+ * **Bug Fix**
+  * Fix conflicting `--module-ids` shorthand arg in `$ 6to5`.
+ * **Internal**
+  * Lots of internal refactoring with scope tracking and traversal.
+ * **Polish**
+  * Don't return `map` in the API result if `sourceMap` was set to `"inline"`.
+
+## 3.3.12
+
+ * **Bug Fix**
+  * Don't override `MemberExpression`s with `core-js` in `selfContained` if a local binding exists.
+
+## 3.3.11
+
+ * **Bug Fix**
+  * Fix the require cache.
+
+## 3.3.10
+
+ * **Internal**
+  * Restructure transformers so they're only ran if the AST contains nodes that they need to worry about. Improves transpilation speed significantly.
+ * **Bug Fix**
+  * Fix source maps not tracking end of node locations.
+ * **Spec Compliancy**
+  * Use static super references as the home object is actually done at definition time.
+ * **Polish**
+  * Force the `es6.destructuring` transformer to be whitelisted when the `es7.objectSpread` transformer is.
+  * Join sibling string literals when creating JSX.
+
+## 3.3.9
+
+ * **Bug Fix**
+  * Fix super inside of functions.
+  * Fix super constructor inheritance.
+
+## 3.3.7
+
+ * **Bug Fix**
+  * Add `--use-strict` to valid node flags in `6to5-node`.
+  * Fix booleans not being properly stripped from the arguments in `6to5-node`.
+  * Force `.js` extension when writing files to directories with `6to5`.
+
+## 3.3.5
+
+ * **Bug Fix**
+  * Fix block scoping inside of while loops.
+  * Make module name regex more conservative. Thanks [@johlrich](https://github.com/johlrich)!
+  * Fix block scoping of constants.
+  * Fix istanbul interop.
+  * Make JSX transforming more inline with the official transformer with spaces after non-empty last lines.
+ * **Polish**
+  * Make it illegal to export a property called `__esModule`.
+
+## 3.3.4
+
+ * **Polish**
+  * Add istanbul `require` interop.
+ * **Bug Fix**
+  * Fix incorrect source map column tracking in specific scenarios.
+
+## 3.3.3
+
+ * **Polish**
+  * Remap top level `this` to `undefined` instead of throwing an error.
+ * **Bug Fix**
+  * Run `selfContained` transformer over the regenerator runtime when building `6to5-runtime`.
+  * Fix `t.isReferenced` not properly allowing `value` nodes.
+
+## 3.3.1
+
+ * **Bug Fix**
+  * Block hoist assignment pattern destructuring.
+
+## 3.3.0
+
+ * **Bug Fix**
+  * Do all transforms before the regenerator transform is ran.
+ * **New Feature**
+  * Added back the 2.x optional runtime.
+
+## 3.2.1
+
+ * **Bug Fix**
+  * Fix block scoping transformer rewriting breaks and continues to inner labels.
+
+## 3.2.0
+
+ * **Bug Fix**
+  * Fixed scope tracking for default parameters IIFE.
+  * Fixed block scoped functions.
+  * Improved `bin/6to5` path resolution.
+ * **New Feature**
+  * You can now trigger super setters in classes. Thanks [@kruppel](https://github.com/kruppel)!
+  * Add `resolveSourceMap` option.
+  * Better support and output for block scoping loops with labels.
+
+## 3.1.1
+
+ * **Polish**
+  * Drop `enumerable: false` clause from class method definitions as `enumerable` already defaults to `false`.
+ * **Bug Fix**
+  * Properly transform `XJSIdentifier` nodes referencing `this` into a `ThisExpression`.
+
+## 3.1.0
+
+ * **Breaking Change**
+  * [Make class methods unenumerable](https://esdiscuss.org/topic/classes-and-enumerability#content-61).
+
+## 3.0.16
+
+ * **Bug Fix**
+  * Don't ignore dynamic import specifiers.
+ * **Internal**
+  * Upgrade `regenerator-6to5`.
+ * **Polish**
+  * Use `Object.assign` in place of extends helper if it exists.
+  * Require individual `lodash` methods. Thanks [@stefanpenner](https://github.com/stefanpenner)!
+
+## 3.0.15
+
+ * **Bug Fix**
+  * Use `debug/node` instead of `debug` to avoid browserify using the browser version that references `window`.
+
+## 3.0.14
+
+ * **New Feature**
+  * Add `--optional` argument to `6to5-node`.
+ * **Bug Fix**
+  * Fix bug in `asyncToGenerator` helper where it was incorrectly calling generator iterator functions.
+
+## 3.0.13
+
+ * **Bug Fix**
+  * Fix modules loose mode using `modules` instead of `es6.modules`.
+
+## 3.0.12
+
+ * **Internal**
+  * Add internal debug messages.
+ * **Bug Fix**
+  * Add `noScope` option to `traverse.clearProperties`.
+
+## 3.0.11
+
+ * **Bug Fix**
+  * Fix `ast-types` `RestElement` definition.
+  * Make `es6.forOf` loose mode more versatile and support destructuring.
+
+## 3.0.10
+
+ * **Bug Fix**
+  * In `types.getIds` make sure the `declaration` inside of `ExportDeclaration` is actually a `Declaration`.
+
+## 3.0.9
+
+ * **Bug Fix**
+  * Make `t.isReferenced` more powerful, actually take into consideration all contexts were identifier nodes aren't actually references.
+  * Don't camelcase underscores when converting a string to a valid identifier.
+
+## 3.0.8
+
+ * **Bug Fix**
+  * Split up default function declaration exports due to regenerator destroying the parent export declaration.
+
+## 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**
@@ -67,8 +450,8 @@ _Note: Gaps between patch versions are faulty/broken releases._
  * **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).
+  * `for...in` loops have been changed to optimized `for` loops - better performance and no enumeration of protoype keys.
+  * Parts of the code generator have now been optimized thanks to [gaearon](https://github.com/gaearon).
 
 ## 2.12.3
 
@@ -91,7 +474,7 @@ _Note: Gaps between patch versions are faulty/broken releases._
  * **Bug Fix**
   * Support non-string JSX literals.
  * **New Feature**
-  * Loose mode for some transformers that enables non-spec behaviour.
+  * Loose mode for some transformers that enables non-spec behavior.
  * **Internal**
   * Uglify `--mangle sort` has been added to the build script, cutting minified scripts in half.
 
@@ -529,7 +912,7 @@ _Note: Gaps between patch versions are faulty/broken releases._
 
 ## 1.13.2
 
- * Optimise `Array.from` usage by adding a helper method.
+ * Optimize `Array.from` usage by adding a helper method.
  * Upgrade `acorn-6to5`.
 
 ## 1.13.1

CONTRIBUTING.md

@@ -1,6 +1,12 @@
 # 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).
+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).
+
+**NOTE:** Please do not send pull requests that fix linting issues. It's highly
+likely that they've already been fixed by the time it's submitted and it just
+pollutes the git tree.
 
 ## Developing
 
@@ -12,7 +18,8 @@ Contributions are always welcome, no matter how large or small. Before contribut
 * 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
+* Create new pull request explaining your proposed change or reference an issue
+  in your commit message
 
 #### Code Standards
 

Makefile

@@ -4,20 +4,28 @@ 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
+6TO5_CMD = node_modules/6to5/bin/6to5
 
 export NODE_ENV = test
 
-.PHONY: clean test test-cov test-clean lint test-travis test-simple test-all test-browser publish build bootstrap publish-core
+.PHONY: clean test test-cov test-clean lint test-travis test-simple test-all test-browser publish build bootstrap publish-core publish-runtime build-core watch-core
+
+build-core:
+	#node $(6TO5_CMD) src --out-dir lib
+
+watch-core:
+	#node $(6TO5_CMD) src --out-dir lib --watch
 
 build:
 	mkdir -p dist
 
-	node bin/cache-templates
+	node tools/cache-templates
 
 	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 $(BROWSERIFY_CMD) lib/6to5/api/browser.js -s to5 >dist/6to5.js
 	node $(UGLIFY_CMD) dist/6to5.js >dist/6to5.min.js
 
 	node bin/6to5-runtime >dist/runtime.js
@@ -30,6 +38,7 @@ clean:
 
 lint:
 	$(JSHINT_CMD) --reporter node_modules/jshint-stylish/stylish.js lib bin
+	$(JSCS_CMD) lib bin
 
 test-clean:
 	rm -rf test/tmp
@@ -40,28 +49,28 @@ test: lint
 
 test-simple:
 	# excludes test262
-	export SIMPLE_6TO5_TESTS=1
+	export SIMPLE_6TO5_TESTS=1; \
 	make test
 
 test-all:
 	# includes traceur, esnext, regenerator
-	export ALL_6TO5_TESTS=1
+	export ALL_6TO5_TESTS=1; \
 	make test
 
 test-cov:
-	export SIMPLE_6TO5_TESTS=1
 	rm -rf coverage
+	export SIMPLE_6TO5_TESTS=1; \
 	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
 
-test-travis: bootstrap
+test-travis: build-core bootstrap
 	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
 	if test -n "$$CODECLIMATE_REPO_TOKEN"; then codeclimate < coverage/lcov.info; fi
 
 test-browser:
 	mkdir -p dist
 
-	node bin/cache-templates
-	node bin/cache-tests
+	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
 
@@ -80,27 +89,36 @@ publish:
 	cp dist/polyfill.min.js browser-polyfill.js
 	cp dist/runtime.min.js runtime.js
 
-	node bin/cache-templates
+	node tools/cache-templates
 	test -f templates.json
 
 	npm publish
 
 	git push --follow-tags
 
-	# generate
-	bin/generate-core-package-json >package2.json
+	make publish-core
+	make publish-runtime
+
+	rm -rf templates.json browser.js browser-polyfill.js runtime.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
 
-	# restore
 	rm -rf package.json
 	mv .package.json package.json
 
-	rm -rf templates.json browser.js runtime.js browser-polyfill.js
-
 bootstrap:
 	npm install
 	git submodule update --init
 	cd vendor/regenerator; npm install
+	cd vendor/compat-table; npm install object-assign

NOTES.md

@@ -1,14 +1,3 @@
 # Notes
 
- * Wildcard exports/imports wont normalise if `export default` is a non-object. See [#224](https://github.com/6to5/6to5/issues/224).
-
-## 3.0.0 breaking changes
-
- * Remove `allowImportExportEverywhere` option from acorn.
- * Remove this shorthand from playground.
- * Remove `super()` inside non-constructors - add descriptive error message.
- * Split up ES5 getter/setter transforming and ES6 property methods into separate transformers.
- * Add autoindentation.
- * Move `super` transformation from classes into a separate transformer that also supports object expressions.
- * Remove fast transformer backwards compatibility.
- * Rename let scoping transformer to block scoping.
+ * Wildcard exports/imports wont normalize if `export default` is a non-object. See [#224](https://github.com/6to5/6to5/issues/224).

README.md

@@ -2,28 +2,6 @@
   <img alt="6to5" src="https://raw.githubusercontent.com/6to5/logo/master/logo.png" width="546">
 </p>
 
-<p align="center">
-  <a href="https://gratipay.com/sebmck">
-    <img alt="Gratipay" src="https://img.shields.io/gratipay/sebmck.svg?style=flat">
-  </a>
-
-  <a href="https://travis-ci.org/6to5/6to5">
-    <img alt="Travis Status" src="http://img.shields.io/travis/6to5/6to5/master.svg?style=flat&amp;label=travis">
-  </a>
-
-  <a href="https://codeclimate.com/github/6to5/6to5">
-    <img alt="Code Climate Score" src="http://img.shields.io/codeclimate/github/6to5/6to5.svg?style=flat">
-  </a>
-
-  <a href="https://codeclimate.com/github/6to5/6to5">
-    <img alt="Coverage" src="http://img.shields.io/codeclimate/coverage/github/6to5/6to5.svg?style=flat">
-  </a>
-
-  <a href="https://david-dm.org/6to5/6to5">
-    <img alt="Dependency Status" src="http://img.shields.io/david/6to5/6to5.svg?style=flat">
-  </a>
-</p>
-
 <p align="center">
   <strong>6to5</strong> turns ES6+ code into vanilla ES5, so you can use next generation features <strong>today.</strong>
 </p>

appveyor.yml

@@ -1,17 +0,0 @@
-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}"

bin/6to5-minify

@@ -0,0 +1,7 @@
+#!/usr/bin/env node
+
+var opts = require("./6to5").opts;
+opts.optional = (opts.optional || []).concat("minification");
+opts.format = {
+  compact: true
+};

bin/6to5-node

@@ -5,7 +5,7 @@
  * when found, before invoking the "real" _6to5-node(1) executable.
  */
 
-var args  = ["--harmony", __dirname + "/_6to5-node"];
+var args  = [__dirname + "/_6to5-node"];
 
 process.argv.slice(2).forEach(function(arg){
   var flag = arg.split("=")[0];
@@ -35,6 +35,7 @@ process.argv.slice(2).forEach(function(arg){
     case "--prof":
     case "--throw-deprecation":
     case "--trace-deprecation":
+    case "--use-strict":
       args.unshift(arg);
       break;
 

bin/6to5-runtime

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

bin/6to5/dir.js

@@ -11,6 +11,9 @@ module.exports = function (commander, filenames, opts) {
   }
 
   var write = function (src, relative) {
+    // remove extension and then append back on .js
+    relative = relative.replace(/\.(\w*?)$/, "") + ".js";
+
     var dest = path.join(commander.outDir, relative);
 
     var data = util.compile(src, { sourceMapName: dest });
@@ -34,8 +37,13 @@ module.exports = function (commander, filenames, opts) {
     if (stat.isDirectory(filename)) {
       var dirname = filename;
 
-      _.each(util.readdirFilter(dirname), function (filename) {
-        write(path.join(dirname, filename), filename);
+      _.each(util.readdir(dirname), function (filename) {
+        var src = path.join(dirname, filename);
+        if (util.canCompile(filename)) {
+          write(src, filename);
+        } else {
+          outputFileSync(path.join(commander.outDir, filename), fs.readFileSync(src));
+        }
       });
     } else {
       write(filename, filename);
@@ -51,12 +59,9 @@ 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);
-
-          console.log(type, filename);
+          var relative = path.relative(dirname, filename) || filename;
           write(filename, relative);
         });
       });

bin/6to5/file.js

@@ -77,7 +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();
     });
@@ -117,7 +117,7 @@ module.exports = function (commander, filenames) {
         persistent: true,
         ignoreInitial: true
       }).on("all", function (type, filename) {
-        if (type === "add" || type === "change" || type === "unlink" ) {
+        if (type === "add" || type === "change") {
           console.log(type, filename);
           walk();
         }

bin/6to5/index.js

@@ -1,10 +1,11 @@
 #!/usr/bin/env node
 
 var commander = require("commander");
-var transform = require("../../lib/6to5/transformation/transform");
+var transform = require("../../lib/6to5/transformation");
 var util      = require("../../lib/6to5/util");
 var fs        = require("fs");
-var _         = require("lodash");
+var each      = require("lodash/collection/each");
+var keys      = require("lodash/object/keys");
 
 commander.option("-t, --source-maps-inline", "Append sourceMappingURL comment to bottom of code");
 commander.option("-s, --source-maps", "Save source map alongside the compiled code");
@@ -18,23 +19,20 @@ commander.option("-m, --modules [modules]", "Module formatter type to use [commo
 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("--loose [list]", "List of transformers to enable their loose mode", 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("-I, --indent [width]", "Indent width [2]", 2);
-commander.option("-a, --amd-module-ids", "Insert module id in AMD modules", false); // todo: remove in 3.0.0
-commander.option("-m, --module-ids", "Insert module id in modules", 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("-E, --include-regenerator", "Include the regenerator runtime if necessary", false);
 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) {
+    each(keys(obj).sort(), function (key) {
       if (key[0] === "_") return;
 
       if (obj[key].optional) {
@@ -62,7 +60,7 @@ var errors = [];
 
 var filenames = commander.args;
 
-_.each(filenames, function (filename) {
+each(filenames, function (filename) {
   if (!fs.existsSync(filename)) {
     errors.push(filename + " doesn't exist");
   }
@@ -101,12 +99,11 @@ if (errors.length) {
 
 exports.opts = {
   keepModuleIdExtensions: commander.keepModuleIdExtensions,
-  includeRegenerator:     commander.includeRegenerator,
   sourceMapName:          commander.outFile,
   experimental:           commander.experimental,
   reactCompat:            commander.reactCompat,
   playground:             commander.playground,
-  moduleIds:              commander.amdModuleIds || commander.moduleIds,
+  moduleIds:              commander.moduleIds,
   blacklist:              commander.blacklist,
   whitelist:              commander.whitelist,
   sourceMap:              commander.sourceMaps || commander.sourceMapsInline,
@@ -114,20 +111,20 @@ exports.opts = {
   comments:               !commander.removeComments,
   runtime:                commander.runtime,
   modules:                commander.modules,
-  loose:                  commander.loose,
-  format: {
-    indent: {
-      style:     util.repeat(parseInt(commander.indent))
-    }
-  }
+  loose:                  commander.loose
 };
 
-var fn;
+setTimeout(function () {
+  // this is just a hack to give `6to5-minify` and other files including this
+  // time to modify `exports.opts`
 
-if (commander.outDir) {
-  fn = require("./dir");
-} else {
-  fn = require("./file");
-}
+  var fn;
 
-fn(commander, filenames, exports.opts);
+  if (commander.outDir) {
+    fn = require("./dir");
+  } else {
+    fn = require("./file");
+  }
+
+  fn(commander, filenames, exports.opts);
+}, 0);

bin/6to5/util.js

@@ -2,7 +2,7 @@ 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 to5     = require("../../lib/6to5/api/node");
 var fs      = require("fs");
 var _       = require("lodash");
 
@@ -12,6 +12,10 @@ exports.readdirFilter = function (filename) {
   });
 };
 
+exports.readdir = readdir;
+
+exports.canCompile = util.canCompile;
+
 exports.addSourceMappingUrl = function (code, loc) {
   return code + "\n//# sourceMappingURL=" + path.basename(loc);
 };

bin/_6to5-node

@@ -1,40 +1,41 @@
 #!/usr/bin/env node
 
-var roadrunner = require("roadrunner");
-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 commander = require("commander");
+var Module    = require("module");
+var path      = require("path");
+var repl      = require("repl");
+var to5       = require("../lib/6to5/api/node");
+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", "Evaluate script and print result");
+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]");
+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("-c, --cache", "Cache compiled files and require paths");
+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);
+program.option("-o, --optional [optional]", "List of optional transformers to enable", util.list);
 
 var pkg = require("../package.json");
 program.version(pkg.version);
 program.usage("[options] [ -e script | script.js ] [arguments]");
 program.parse(process.argv);
 
-if (program.cache) roadrunner.load();
-
 //
 
 to5.register({
   experimental: program.experimental,
   extensions:   program.extensions,
   playground:   program.playground,
-  ignore:       program.ignore,
-  cache:        program.cache && roadrunner.get("6to5")
+  blacklist:    program.blacklist,
+  whitelist:    program.whitelist,
+  optional:     program.optional,
+  ignore:       program.ignore
 });
 
 //
@@ -42,15 +43,20 @@ to5.register({
 var _eval = function (code, filename) {
   code = to5.transform(code, {
     filename: filename,
-    blacklist: ["useStrict"],
+    blacklist: ["useStrict"].concat(program.blacklist || []),
+    whitelist: program.whitelist,
+    optional: program.optional,
     experimental: program.experimental,
     playground: program.playground
   }).code;
   return vm.runInThisContext(code, filename);
 };
 
-if (program.eval) {
-  var result = _eval(program.eval, "eval");
+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) {
@@ -58,8 +64,19 @@ if (program.eval) {
     var args = process.argv.slice(2);
 
     var i = 0;
+    var ignoreNext = false;
     _.each(args, function (arg, i2) {
-      if (arg[0] !== "-") {
+      if (ignoreNext) {
+        ignoreNext = false;
+        return;
+      }
+
+      if (arg[0] === "-") {
+        var parsedArg = program[arg.slice(2)];
+        if (parsedArg && parsedArg !== true) {
+          ignoreNext = true;
+        }
+      } else {
         i = i2;
         return false;
       }
@@ -79,8 +96,6 @@ if (program.eval) {
   }
 }
 
-if (program.cache) roadrunner.save();
-
 function replStart() {
   repl.start({
     prompt: "> ",

lib/6to5/api/browser.js

@@ -1,8 +1,8 @@
 "use strict";
 
-var transform = module.exports = require("./transformation/transform");
+var transform = module.exports = require("../transformation");
 
-transform.version = require("../../package").version;
+transform.version = require("../../../package").version;
 
 transform.transform = transform;
 

lib/6to5/api/node.js

@@ -1,24 +1,24 @@
 "use strict";
 
-var transform = require("./transformation/transform");
-var util      = require("./util");
-var fs        = require("fs");
-var _         = require("lodash");
+var isFunction = require("lodash/lang/isFunction");
+var transform  = require("../transformation");
+var util       = require("../util");
+var fs         = require("fs");
 
-exports.version = require("../../package").version;
+exports.version = require("../../../package").version;
 
-exports.types = require("./types");
+exports.runtime = require("../build-runtime");
 
-exports.runtime = require("./runtime-generator");
+exports.types = require("../types");
 
 exports.register = function (opts) {
-  var register = require("./register");
+  var register = require("./register/node");
   if (opts != null) register(opts);
   return register;
 };
 
 exports.polyfill = function () {
-  require("./polyfill");
+  require("../polyfill");
 };
 
 exports.canCompile = util.canCompile;
@@ -29,7 +29,7 @@ exports._util = util;
 exports.transform = transform;
 
 exports.transformFile = function (filename, opts, callback) {
-  if (_.isFunction(opts)) {
+  if (isFunction(opts)) {
     callback = opts;
     opts = {};
   }

lib/6to5/api/register/browser.js

@@ -4,4 +4,4 @@
 
 module.exports = function () {};
 
-require("./polyfill");
+require("../../polyfill");

lib/6to5/api/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 () {
+  process.on("exit", exports.save);
+
+  var sigint = function () {
+    process.removeListener("SIGINT", sigint);
+    exports.save();
+    process.kill(process.pid, "SIGINT");
+  };
+
+  process.on("SIGINT", sigint);
+
+  if (!fs.existsSync(FILENAME)) return;
+
+  try {
+    data = JSON.parse(fs.readFileSync(FILENAME));
+  } catch (err) {
+    return;
+  }
+};
+
+exports.get = function () {
+  return data;
+};

lib/6to5/api/register/node.js

@@ -0,0 +1,152 @@
+"use strict";
+
+require("../../polyfill");
+
+var sourceMapSupport = require("source-map-support");
+var registerCache    = require("./cache");
+var extend           = require("lodash/object/extend");
+var each             = require("lodash/collection/each");
+var util             = require("../../util");
+var to5              = require("../node");
+var fs               = require("fs");
+
+sourceMapSupport.install({
+  retrieveSourceMap: function (source) {
+    var map = maps && maps[source];
+    if (map) {
+      return {
+        url: null,
+        map: map
+      };
+    } else {
+      return null;
+    }
+  }
+});
+
+//
+
+registerCache.load();
+var cache = registerCache.get();
+
+//
+
+var transformOpts = {};
+var ignoreRegex   = /node_modules/;
+var onlyRegex;
+var exts          = {};
+var maps          = {};
+
+var mtime = function (filename) {
+  return +fs.statSync(filename).mtime;
+};
+
+var compile = function (filename) {
+  var result;
+
+  var cacheKey = filename + ":" + JSON.stringify(transformOpts);
+
+  if (cache) {
+    var cached = cache[cacheKey];
+    if (cached && cached.mtime === mtime(filename)) {
+      result = cached;
+    }
+  }
+
+  if (!result) {
+    result = to5.transformFileSync(filename, extend({
+      sourceMap: true,
+      ast:       false
+    }, transformOpts));
+  }
+
+  if (cache) {
+    result.mtime = mtime(filename);
+    cache[cacheKey] = result;
+  }
+
+  maps[filename] = result.map;
+
+  return result.code;
+};
+
+var shouldIgnore = function (filename) {
+  return (ignoreRegex && ignoreRegex.test(filename)) || (onlyRegex && !onlyRegex.test(filename));
+};
+
+var istanbulMonkey = {};
+
+if (process.env.running_under_istanbul) { // jshint ignore:line
+  // we need to monkey patch fs.readFileSync so we can hook into
+  // what istanbul gets, it's extremely dirty but it's the only way
+  var _readFileSync = fs.readFileSync;
+
+  fs.readFileSync = function (filename) {
+    if (istanbulMonkey[filename]) {
+      delete istanbulMonkey[filename];
+      var code = compile(filename);
+      istanbulMonkey[filename] = true;
+      return code;
+    } else {
+      return _readFileSync.apply(this, arguments);
+    }
+  };
+}
+
+var istanbulLoader = function (m, filename, old) {
+  istanbulMonkey[filename] = true;
+  old(m, filename);
+};
+
+var normalLoader = function (m, filename) {
+  m._compile(compile(filename), filename);
+};
+
+var registerExtension = function (ext) {
+  var old = require.extensions[ext];
+
+  var loader = normalLoader;
+  if (process.env.running_under_istanbul) loader = istanbulLoader; // jshint ignore:line
+
+  require.extensions[ext] = function (m, filename) {
+    if (shouldIgnore(filename)) {
+      old(m, filename);
+    } else {
+      loader(m, filename, old);
+    }
+  };
+};
+
+var hookExtensions = function (_exts) {
+  each(exts, function (old, ext) {
+    require.extensions[ext] = old;
+  });
+
+  exts = {};
+
+  each(_exts, function (ext) {
+    exts[ext] = require.extensions[ext];
+    registerExtension(ext);
+  });
+};
+
+hookExtensions(util.canCompile.EXTENSIONS);
+
+module.exports = function (opts) {
+  // normalize options
+  opts = opts || {};
+
+  if (opts.only != null) onlyRegex = util.regexify(opts.only);
+  if (opts.ignore != null) ignoreRegex = util.regexify(opts.ignore);
+
+  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/build-helpers.js

@@ -0,0 +1,13 @@
+var File = require("./transformation/file");
+var util = require("./util");
+var each = require("lodash/collection/each");
+var t    = require("./types");
+
+module.exports = function (body, namespace) {
+  each(File.helpers, function (name) {
+    var key = t.identifier(t.toIdentifier(name));
+    body.push(t.expressionStatement(
+      t.assignmentExpression("=", t.memberExpression(namespace, key), util.template(name))
+    ));
+  });
+};

lib/6to5/build-runtime.js

@@ -0,0 +1,25 @@
+"use strict";
+
+var buildHelpers = require("./build-helpers");
+var generator    = require("./generation");
+var util         = require("./util");
+var t            = require("./types");
+
+module.exports = function () {
+  var namespace = t.identifier("to5Runtime");
+
+  var body      = [];
+  var container = t.functionExpression(null, [t.identifier("global")], t.blockStatement(body));
+  var tree      = t.program([t.expressionStatement(t.callExpression(container, [util.template("self-global")]))]);
+
+  body.push(t.variableDeclaration("var", [
+    t.variableDeclarator(
+      namespace,
+      t.assignmentExpression("=", t.memberExpression(t.identifier("global"), namespace), t.objectExpression([]))
+    )
+  ]));
+
+  buildHelpers(body, namespace);
+
+  return generator(tree).code;
+};

lib/6to5/detection/index.js

@@ -0,0 +1,29 @@
+module.exports = detect;
+
+var SYNTAX_KEYS = require("./syntax-keys");
+var traverse    = require("../traversal");
+var visitors    = traverse.explode(require("./visitors"));
+
+function detect(ast) {
+  var stats = {
+    syntax: {},
+    builtins: {}
+  };
+
+  var detectedSyntax = function (name) {
+    stats.syntax[name] = true;
+  };
+
+  traverse(ast, {
+    enter: function (node, parent) {
+      if (SYNTAX_KEYS[node.type]) {
+        detectedSyntax(SYNTAX_KEYS[node.type]);
+      }
+
+      var visitor = visitors[node.type];
+      if (visitor) visitor(node, parent, detectedSyntax);
+    }
+  });
+
+  return stats;
+}

lib/6to5/detection/syntax-keys.json

@@ -0,0 +1,84 @@
+{
+  "ArrowFunctionExpression":   "es6.arrowFunctions",
+
+  "AwaitExpression":           "es7.asyncFunctions",
+
+  "ClassBody":                 "es6.classes",
+  "ClassDeclaration":          "es6.classes",
+  "ClassExpression":           "es6.classes",
+  "MethodDefinition":          "es6.classes",
+
+  "ComprehensionBlock":        "es7.comprehensions",
+  "ComprehensionExpression":   "es7.comprehensions",
+
+  "ForOfStatement":            "es6.forOf",
+
+  "ExportBatchSpecifier":      "es6.modules",
+  "ExportDeclaration":         "es6.modules",
+  "ExportSpecifier":           "es6.modules",
+  "ImportBatchSpecifier":      "es6.modules",
+  "ImportDeclaration":         "es6.modules",
+  "ImportSpecifier":           "es6.modules",
+
+  "ArrayPattern":              "es6.destructuring",
+  "AssignmentPattern":         "es6.destructuring",
+  "ObjectPattern":             "es6.destructuring",
+
+  "RestElement":               "es6.parameters.rest",
+
+  "SpreadElement":             "es6.spread",
+
+  "SpreadProperty":            "es7.objectSpread",
+
+  "TaggedTemplateExpression":  "es6.templateLiterals",
+  "TemplateElement":           "es6.templateLiterals",
+  "TemplateLiteral":           "es6.templateLiterals",
+
+  "VirtualPropertyExpression": "es7.abstractReferences",
+  "PrivateDeclaration":        "es7.abstractReferences",
+
+  "YieldExpression":           "es6.generators",
+
+  "AnyTypeAnnotation":           "flow",
+  "ArrayTypeAnnotation":         "flow",
+  "BooleanTypeAnnotation":       "flow",
+  "ClassProperty":               "flow",
+  "DeclareClass":                "flow",
+  "DeclareFunction":             "flow",
+  "DeclareModule":               "flow",
+  "DeclareVariable":             "flow",
+  "FunctionTypeAnnotation":      "flow",
+  "FunctionTypeParam":           "flow",
+  "GenericTypeAnnotation":       "flow",
+  "InterfaceExtends":            "flow",
+  "InterfaceDeclaration":        "flow",
+  "IntersectionTypeAnnotation":  "flow",
+  "NullableTypeAnnotation":      "flow",
+  "NumberTypeAnnotation":        "flow",
+  "StringLiteralTypeAnnotation": "flow",
+  "StringTypeAnnotation":        "flow",
+  "TupleTypeAnnotation":         "flow",
+  "TypeofTypeAnnotation":        "flow",
+  "TypeAlias":                   "flow",
+  "TypeAnnotation":              "flow",
+  "TypeParameterDeclaration":    "flow",
+  "TypeParameterInstantiation":  "flow",
+  "ObjectTypeAnnotation":        "flow",
+  "ObjectTypeCallProperty":      "flow",
+  "ObjectTypeIndexer":           "flow",
+  "ObjectTypeProperty":          "flow",
+  "QualifiedTypeIdentifier":     "flow",
+  "UnionTypeAnnotation":         "flow",
+  "VoidTypeAnnotation":          "flow",
+
+  "JSXAttribute":              "jsx",
+  "JSXClosingElement":         "jsx",
+  "JSXElement":                "jsx",
+  "JSXEmptyExpression":        "jsx",
+  "JSXExpressionContainer":    "jsx",
+  "JSXIdentifier":             "jsx",
+  "JSXMemberExpression":       "jsx",
+  "JSXNamespacedName":         "jsx",
+  "JSXOpeningElement":         "jsx",
+  "JSXSpreadAttribute":        "jsx"
+}

lib/6to5/detection/visitors.js

@@ -0,0 +1,54 @@
+var t = require("../types");
+var includes = require("lodash/collection/includes");
+
+exports.AssignmentExpression = function (node, parent, detected) {
+  if (node.operator === "**=") {
+    detected("es6.exponentation");
+  }
+};
+
+exports.BinaryExpression = function (node, parent, detected) {
+  if (node.operator === "**") {
+    detected("es6.exponentation");
+  }
+};
+
+exports.VariableDeclaration = function (node, parent, detected) {
+  if (node.kind === "let" || node.kind === "const") {
+    detected("es6.blockScoping");
+  }
+
+  if (node.kind === "const") {
+    detected("es6.constants");
+  }
+};
+
+exports.Property = function (node, parent, detected) {
+  if (node.shorthand || node.method) {
+    detected("es6.properties.shorthand");
+  }
+
+  if (node.kind === "set" || node.kind === "get") {
+    detected("es5.properties.mutators");
+  }
+
+  if (node.computed) {
+    detected("es6.properties.computed");
+  }
+};
+
+exports.AssignmentPattern = function (node, parent, detected) {
+  if (t.isFunction(parent) && includes(parent.params, node)) {
+    detected("es6.parameters.default");
+  }
+};
+
+exports.Function = function (node, parent, detected) {
+  if (node.generator) {
+    detected("es6.generators");
+  }
+
+  if (node.async) {
+    detected("es7.asyncFunctions");
+  }
+};

lib/6to5/file.js

@@ -1,348 +0,0 @@
-"use strict";
-
-module.exports = File;
-
-var SHEBANG_REGEX = /^\#\!.*/;
-
-var transform = require("./transformation/transform");
-var generate  = require("./generation/generator");
-var Scope     = require("./traverse/scope");
-var util      = require("./util");
-var t         = require("./types");
-var _         = require("lodash");
-
-function File(opts) {
-  this.dynamicImports   = [];
-  this.dynamicImportIds = {};
-  this.opts             = File.normaliseOptions(opts);
-  this.transformers     = this.getTransformers();
-  this.uids             = {};
-  this.ast              = {};
-}
-
-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.excludeHelpersFromRuntime = [
-  "async-to-generator",
-  "typeof",
-  "tagged-template-literal-loose"
-];
-
-File.normaliseOptions = function (opts) {
-  opts = _.cloneDeep(opts || {});
-
-  _.defaults(opts, {
-    keepModuleIdExtensions: false,
-    includeRegenerator:     false,
-    experimental:           false,
-    reactCompat:            false,
-    playground:             false,
-    whitespace:             true,
-    moduleIds:              opts.amdModuleIds || false,
-    blacklist:              [],
-    whitelist:              [],
-    sourceMap:              false,
-    optional:               [],
-    comments:               true,
-    filename:               "unknown",
-    modules:                "common",
-    runtime:                false,
-    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);
-  }
-
-  // todo: remove in 3.0.0
-  _.each({
-    fastForOf: "forOf",
-    classesFastSuper: "classes"
-  }, function (newTransformer, oldTransformer) {
-    if (_.contains(opts.optional, oldTransformer)) {
-      _.pull(opts.optional, oldTransformer);
-      opts.loose.push(newTransformer);
-    }
-  });
-
-  _.defaults(opts, {
-    moduleRoot: opts.sourceRoot
-  });
-
-  _.defaults(opts, {
-    sourceRoot: opts.moduleRoot
-  });
-
-  _.defaults(opts, {
-    filenameRelative: opts.filename
-  });
-
-  _.defaults(opts, {
-    sourceFileName: opts.filenameRelative,
-    sourceMapName:  opts.filenameRelative
-  });
-
-  if (opts.runtime === true) {
-    opts.runtime = "to5Runtime";
-  }
-
-  if (opts.playground) {
-    opts.experimental = true;
-  }
-
-  transform._ensureTransformerNames("blacklist", opts.blacklist);
-  transform._ensureTransformerNames("whitelist", opts.whitelist);
-  transform._ensureTransformerNames("optional", opts.optional);
-  transform._ensureTransformerNames("loose", opts.loose);
-
-  return opts;
-};
-
-File.prototype.isLoose = function (key) {
-  return _.contains(this.opts.loose, key);
-};
-
-File.prototype.getTransformers = function () {
-  var file = this;
-  var transformers = [];
-  var secondPassTransformers = [];
-
-  _.each(transform.transformers, function (transformer) {
-    if (transformer.canRun(file)) {
-      transformers.push(transformer);
-
-      if (transformer.secondPass) {
-        secondPassTransformers.push(transformer);
-      }
-
-      if (transformer.manipulateOptions) {
-        transformer.manipulateOptions(file.opts, file);
-      }
-    }
-  });
-
-  return transformers.concat(secondPassTransformers);
-};
-
-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 ModuleFormatter = _.isFunction(type) ? type : transform.moduleFormatters[type];
-
-  if (!ModuleFormatter) {
-    var loc = util.resolve(type);
-    if (loc) ModuleFormatter = require(loc);
-  }
-
-  if (!ModuleFormatter) {
-    throw new ReferenceError("Unknown module formatter type " + JSON.stringify(type));
-  }
-
-  return new ModuleFormatter(this);
-};
-
-File.prototype.parseShebang = function (code) {
-  var shebangMatch = code.match(SHEBANG_REGEX);
-  if (shebangMatch) {
-    this.shebang = shebangMatch[0];
-
-    // remove shebang
-    code = code.replace(SHEBANG_REGEX, "");
-  }
-
-  return code;
-};
-
-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.dynamicImports.push(declar);
-  }
-
-  return id;
-};
-
-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 ref;
-  var runtimeNamespace = this.opts.runtime;
-  if (runtimeNamespace && !_.contains(File.excludeHelpersFromRuntime, name)) {
-    name = t.identifier(t.toIdentifier(name));
-    return t.memberExpression(t.identifier(runtimeNamespace), name);
-  } else {
-    ref = util.template(name);
-  }
-
-  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.addCode(code);
-
-  return util.parse(this.opts, code, function (tree) {
-    self.transform(tree);
-    return self.generate();
-  });
-};
-
-File.prototype.transform = function (ast) {
-  var self = this;
-
-  this.ast = ast;
-  this.scope = new Scope(ast.program);
-  this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
-
-  var astRun = function (key) {
-    _.each(self.transformers, function (transformer) {
-      transformer.astRun(self, key);
-    });
-  };
-
-  astRun("enter");
-
-  _.each(this.transformers, function (transformer) {
-    transformer.transform(self);
-  });
-
-  astRun("exit");
-};
-
-File.prototype.generate = function () {
-  var opts = this.opts;
-  var ast  = this.ast;
-
-  var result = {
-    code: "",
-    map: null,
-    ast: null
-  };
-
-  if (opts.ast) result.ast = ast;
-  if (!opts.code) return result;
-
-  var _result = generate(ast, opts, this.code);
-  result.code = _result.code;
-  result.map  = _result.map;
-
-  if (this.shebang) {
-    // add back shebang
-    result.code = this.shebang + "\n" + result.code;
-  }
-
-  if (opts.sourceMap === "inline") {
-    result.code += "\n" + util.sourceMapToComment(result.map);
-  }
-
-  return result;
-};
-
-File.prototype.generateUid = function (name, scope) {
-  name = t.toIdentifier(name).replace(/^_+/, "");
-
-  scope = scope || this.scope;
-
-  var uid;
-  do {
-    uid = this._generateUid(name);
-  } while (scope.has(uid));
-  return uid;
-};
-
-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) {
-  var uids = this.uids;
-  var i = uids[name] || 1;
-
-  var id = name;
-  if (i > 1) id += i;
-  uids[name] = i + 1;
-  return "_" + id;
-};

lib/6to5/generation/buffer.js

@@ -2,8 +2,10 @@
 
 module.exports = Buffer;
 
-var util = require("../util");
-var _    = require("lodash");
+var isBoolean = require("lodash/lang/isBoolean");
+var includes  = require("lodash/collection/includes");
+var isNumber  = require("lodash/lang/isNumber");
+var util      = require("../util");
 
 function Buffer(position, format) {
   this.position = position;
@@ -17,7 +19,7 @@ Buffer.prototype.get = function () {
 };
 
 Buffer.prototype.getIndent = function () {
-  if (this.format.compact) {
+  if (this.format.compact || this.format.concise) {
     return "";
   } else {
     return util.repeat(this._indent, this.format.indent.style);
@@ -51,10 +53,12 @@ Buffer.prototype.rightBrace = function () {
 
 Buffer.prototype.keyword = function (name) {
   this.push(name);
-  this.push(" ");
+  this.space();
 };
 
 Buffer.prototype.space = function () {
+  if (this.format.compact) return;
+
   if (this.buf && !this.isLast([" ", "\n"])) {
     this.push(" ");
   }
@@ -68,10 +72,14 @@ Buffer.prototype.removeLast = function (cha) {
 };
 
 Buffer.prototype.newline = function (i, removeLast) {
-  if (this.format.compact) return;
+  if (this.format.compact || this.format.concise) {
+    this.space();
+    return;
+  }
+
   removeLast = removeLast || false;
 
-  if (_.isNumber(i)) {
+  if (isNumber(i)) {
     if (this.endsWith("{\n")) i--;
     if (this.endsWith(util.repeat(i, "\n"))) return;
 
@@ -81,7 +89,7 @@ Buffer.prototype.newline = function (i, removeLast) {
     return;
   }
 
-  if (_.isBoolean(i)) {
+  if (isBoolean(i)) {
     removeLast = i;
   }
 
@@ -102,13 +110,13 @@ Buffer.prototype._newline = function (removeLast) {
  * If buffer ends with a newline and some spaces after it, trim those spaces.
  */
 Buffer.prototype._removeSpacesAfterLastNewline = function () {
-  var lastNewlineIndex = this.buf.lastIndexOf('\n');
+  var lastNewlineIndex = this.buf.lastIndexOf("\n");
   if (lastNewlineIndex === -1)
     return;
 
   var index = this.buf.length - 1;
   while (index > lastNewlineIndex) {
-    if (this.buf[index] !== ' ') {
+    if (this.buf[index] !== " ") {
       break;
     }
 
@@ -151,7 +159,7 @@ Buffer.prototype.isLast = function (cha, trimRight) {
   var last = buf[buf.length - 1];
 
   if (Array.isArray(cha)) {
-    return _.contains(cha, last);
+    return includes(cha, last);
   } else {
     return cha === last;
   }

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

@@ -1,8 +1,8 @@
 "use strict";
 
-var util = require("../../util");
-var t    = require("../../types");
-var _    = require("lodash");
+var util     = require("../../util");
+var t        = require("../../types");
+var isNumber = require("lodash/lang/isNumber");
 
 exports.UnaryExpression = function (node, print) {
   var hasSpace = /[a-z]$/.test(node.operator);
@@ -17,7 +17,7 @@ exports.UnaryExpression = function (node, print) {
   }
 
   this.push(node.operator);
-  if (hasSpace) this.space();
+  if (hasSpace) this.push(" ");
   print(node.argument);
 };
 
@@ -33,9 +33,13 @@ exports.UpdateExpression = function (node, print) {
 
 exports.ConditionalExpression = function (node, print) {
   print(node.test);
-  this.push(" ? ");
+  this.space();
+  this.push("?");
+  this.space();
   print(node.consequent);
-  this.push(" : ");
+  this.space();
+  this.push(":");
+  this.space();
   print(node.alternate);
 };
 
@@ -44,13 +48,13 @@ exports.NewExpression = function (node, print) {
   print(node.callee);
   if (node.arguments.length || this.format.parentheses) {
     this.push("(");
-    print.join(node.arguments, { separator: ", " });
+    print.list(node.arguments);
     this.push(")");
   }
 };
 
 exports.SequenceExpression = function (node, print) {
-  print.join(node.expressions, { separator: ", " });
+  print.list(node.expressions);
 };
 
 exports.ThisExpression = function () {
@@ -72,9 +76,7 @@ exports.CallExpression = function (node, print) {
     separator += " ";
   }
 
-  print.join(node.arguments, {
-    separator: separator
-  });
+  print.list(node.arguments, { separator: separator });
 
   if (node._prettyCall) {
     this.newline();
@@ -87,7 +89,11 @@ exports.CallExpression = function (node, print) {
 var buildYieldAwait = function (keyword) {
   return function (node, print) {
     this.push(keyword);
-    if (node.delegate) this.push("*");
+
+    if (node.delegate || node.all) {
+      this.push("*");
+    }
+
     if (node.argument) {
       this.space();
       print(node.argument);
@@ -111,8 +117,11 @@ exports.BinaryExpression =
 exports.LogicalExpression =
 exports.AssignmentPattern =
 exports.AssignmentExpression = function (node, print) {
+  // todo: add cases where the spaces can be dropped when in compact mode
   print(node.left);
-  this.push(" " + node.operator + " ");
+  this.push(" ");
+  this.push(node.operator);
+  this.push(" ");
   print(node.right);
 };
 
@@ -127,7 +136,7 @@ exports.MemberExpression = function (node, print) {
   }
 
   var computed = node.computed;
-  if (t.isLiteral(node.property) && _.isNumber(node.property.value)) {
+  if (t.isLiteral(node.property) && isNumber(node.property.value)) {
     computed = true;
   }
 

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

@@ -1,9 +1,9 @@
 "use strict";
 
-var t = require("../../types");
-var _ = require("lodash");
+var t    = require("../../types");
+var each = require("lodash/collection/each");
 
-exports.XJSAttribute = function (node, print) {
+exports.JSXAttribute = function (node, print) {
   print(node.name);
   if (node.value) {
     this.push("=");
@@ -11,35 +11,35 @@ exports.XJSAttribute = function (node, print) {
   }
 };
 
-exports.XJSIdentifier = function (node) {
+exports.JSXIdentifier = function (node) {
   this.push(node.name);
 };
 
-exports.XJSNamespacedName = function (node, print) {
+exports.JSXNamespacedName = function (node, print) {
   print(node.namespace);
   this.push(":");
   print(node.name);
 };
 
-exports.XJSMemberExpression = function (node, print) {
+exports.JSXMemberExpression = function (node, print) {
   print(node.object);
   this.push(".");
   print(node.property);
 };
 
-exports.XJSSpreadAttribute = function (node, print) {
+exports.JSXSpreadAttribute = function (node, print) {
   this.push("{...");
   print(node.argument);
   this.push("}");
 };
 
-exports.XJSExpressionContainer = function (node, print) {
+exports.JSXExpressionContainer = function (node, print) {
   this.push("{");
   print(node.expression);
   this.push("}");
 };
 
-exports.XJSElement = function (node, print) {
+exports.JSXElement = function (node, print) {
   var self = this;
 
   var open = node.openingElement;
@@ -47,7 +47,7 @@ exports.XJSElement = function (node, print) {
   if (open.selfClosing) return;
 
   this.indent();
-  _.each(node.children, function (child) {
+  each(node.children, function (child) {
     if (t.isLiteral(child)) {
       self.push(child.value);
     } else {
@@ -59,22 +59,20 @@ exports.XJSElement = function (node, print) {
   print(node.closingElement);
 };
 
-exports.XJSOpeningElement = function (node, print) {
+exports.JSXOpeningElement = function (node, print) {
   this.push("<");
   print(node.name);
   if (node.attributes.length > 0) {
-    this.space();
+    this.push(" ");
     print.join(node.attributes, { separator: " " });
   }
   this.push(node.selfClosing ? " />" : ">");
 };
 
-exports.XJSClosingElement = function (node, print) {
+exports.JSXClosingElement = function (node, print) {
   this.push("</");
   print(node.name);
   this.push(">");
 };
 
-exports.XJSEmptyExpression = function () {
-
-};
+exports.JSXEmptyExpression = function () {};

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

@@ -3,30 +3,8 @@
 var t = require("../../types");
 
 exports._params = function (node, print) {
-  var self = this;
-
   this.push("(");
-
-  print.join(node.params, {
-    separator: ", ",
-    iterator: function (param, i) {
-      var def = node.defaults && node.defaults[i];
-      if (def) {
-        self.push(" = ");
-        print(def);
-      }
-    }
-  });
-
-  if (node.rest) {
-    if (node.params.length) {
-      this.push(", ");
-    }
-
-    this.push("...");
-    print(node.rest);
-  }
-
+  print.list(node.params);
   this.push(")");
 };
 
@@ -54,7 +32,7 @@ exports._method = function (node, print) {
   }
 
   this._params(value, print);
-  this.space();
+  this.push(" ");
   print(value.body);
 };
 
@@ -63,8 +41,14 @@ exports.FunctionExpression = function (node, print) {
   if (node.async) this.push("async ");
   this.push("function");
   if (node.generator) this.push("*");
-  this.space();
-  if (node.id) print(node.id);
+
+  if (node.id) {
+    this.push(" ");
+    print(node.id);
+  } else {
+    this.space();
+  }
+
   this._params(node, print);
   this.space();
   print(node.body);
@@ -73,7 +57,7 @@ exports.FunctionExpression = function (node, print) {
 exports.ArrowFunctionExpression = function (node, print) {
   if (node.async) this.push("async ");
 
-  if (node.params.length === 1 && !node.defaults.length && !node.rest && t.isIdentifier(node.params[0])) {
+  if (node.params.length === 1 && t.isIdentifier(node.params[0])) {
     print(node.params[0]);
   } else {
     this._params(node, print);

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

@@ -1,11 +1,11 @@
 "use strict";
 
-var t = require("../../types");
-var _ = require("lodash");
+var t    = require("../../types");
+var each = require("lodash/collection/each");
 
 exports.ImportSpecifier = function (node, print) {
-  if (node.id && node.id.name === "default") {
-    print(node.name);
+  if (t.isSpecifierDefault(node)) {
+    print(t.getSpecifierName(node));
   } else {
     return exports.ExportSpecifier.apply(this, arguments);
   }
@@ -66,12 +66,12 @@ exports.ImportDeclaration = function (node, print) {
   if (specfiers && specfiers.length) {
     var foundImportSpecifier = false;
 
-    _.each(node.specifiers, function (spec, i) {
+    each(node.specifiers, function (spec, i) {
       if (+i > 0) {
         self.push(", ");
       }
 
-      var isDefault = spec.id && spec.id.name === "default";
+      var isDefault = t.isSpecifierDefault(spec);
 
       if (!isDefault && spec.type !== "ImportBatchSpecifier" && !foundImportSpecifier) {
         foundImportSpecifier = true;

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

@@ -1,8 +1,8 @@
 "use strict";
 
-var _ = require("lodash");
+var each = require("lodash/collection/each");
 
-_.each(["BindMemberExpression", "BindFunctionExpression"], function (type) {
+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

@@ -15,13 +15,19 @@ exports.IfStatement = function (node, print) {
   this.keyword("if");
   this.push("(");
   print(node.test);
-  this.push(") ");
+  this.push(")");
+  this.space();
 
   print.indentOnComments(node.consequent);
 
   if (node.alternate) {
     if (this.isLast("}")) this.space();
     this.keyword("else");
+
+    if (this.format.format && !t.isBlockStatement(node.alternate)) {
+      this.push(" ");
+    }
+
     print.indentOnComments(node.alternate);
   }
 };
@@ -34,13 +40,13 @@ exports.ForStatement = function (node, print) {
   this.push(";");
 
   if (node.test) {
-    this.space();
+    this.push(" ");
     print(node.test);
   }
   this.push(";");
 
   if (node.update) {
-    this.space();
+    this.push(" ");
     print(node.update);
   }
 
@@ -87,7 +93,7 @@ var buildLabelStatement = function (prefix, key) {
 
     var label = node[key || "label"];
     if (label) {
-      this.space();
+      this.push(" ");
       print(label);
     }
 
@@ -144,7 +150,9 @@ exports.SwitchStatement = function (node, print) {
   this.keyword("switch");
   this.push("(");
   print(node.discriminant);
-  this.push(") {");
+  this.push(")");
+  this.space();
+  this.push("{");
   print.sequence(node.cases, { indent: true });
   this.push("}");
 };
@@ -169,26 +177,25 @@ exports.DebuggerStatement = function () {
 exports.VariableDeclaration = function (node, print, parent) {
   this.push(node.kind + " ");
 
-  var inits = 0;
-  var noInits = 0;
+  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) {
-        inits++;
-      } else {
-        noInits++;
+        // has an init so let's split it up over multiple lines
+        hasInits = true;
       }
     }
   }
 
   var sep = ",";
-  if (inits > noInits) { // more inits than no inits so let's add a newline
+  if (hasInits) {
     sep += "\n" + util.repeat(node.kind.length + 1);
   } else {
     sep += " ";
   }
 
-  print.join(node.declarations, { separator: sep });
+  print.list(node.declarations, { separator: sep });
 
   if (!t.isFor(parent)) {
     this.semicolon();
@@ -204,7 +211,9 @@ exports.PrivateDeclaration = function (node, print) {
 exports.VariableDeclarator = function (node, print) {
   if (node.init) {
     print(node.id);
-    this.push(" = ");
+    this.space();
+    this.push("=");
+    this.space();
     print(node.init);
   } else {
     print(node.id);

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

@@ -1,6 +1,6 @@
 "use strict";
 
-var _ = require("lodash");
+var each = require("lodash/collection/each");
 
 exports.TaggedTemplateExpression = function (node, print) {
   print(node.tag);
@@ -18,7 +18,7 @@ exports.TemplateLiteral = function (node, print) {
   var self   = this;
   var len    = quasis.length;
 
-  _.each(quasis, function (quasi, i) {
+  each(quasis, function (quasi, i) {
     print(quasi);
 
     if (i + 1 < len) {

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

@@ -1,11 +1,12 @@
 "use strict";
 
-var _ = require("lodash");
+var each = require("lodash/collection/each");
 
 exports.Identifier = function (node) {
   this.push(node.name);
 };
 
+exports.RestElement =
 exports.SpreadElement =
 exports.SpreadProperty = function (node, print) {
   this.push("...");
@@ -26,7 +27,7 @@ exports.ObjectPattern = function (node, print) {
     this.push("{");
     this.space();
 
-    print.join(props, { separator: ", ", indent: true });
+    print.list(props, { indent: true });
 
     this.space();
     this.push("}");
@@ -48,7 +49,8 @@ exports.Property = function (node, print) {
       if (node.shorthand) return;
     }
 
-    this.push(": ");
+    this.push(":");
+    this.space();
     print(node.value);
   }
 };
@@ -61,7 +63,7 @@ exports.ArrayPattern = function (node, print) {
 
   this.push("[");
 
-  _.each(elems, function (elem, i) {
+  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
@@ -70,7 +72,7 @@ exports.ArrayPattern = function (node, print) {
       // both (all) of the holes.
       self.push(",");
     } else {
-      if (i > 0) self.push(" ");
+      if (i > 0 && !self.format.compact) self.push(" ");
       print(elem);
       if (i < len - 1) self.push(",");
     }
@@ -92,8 +94,10 @@ exports.Literal = function (node) {
     });
 
     this.push(val);
-  } else if (type === "boolean" || type === "number") {
-    this.push(JSON.stringify(val));
+  } else if (type === "number") {
+    this.push(val + "");
+  } else if (type === "boolean") {
+    this.push(val ? "true" : "false");
   } else if (node.regex) {
     this.push("/" + node.regex.pattern + "/" + node.regex.flags);
   } else if (val === null) {

lib/6to5/generation/index.js

@@ -7,21 +7,25 @@ module.exports = function (ast, opts, code) {
 
 module.exports.CodeGenerator = CodeGenerator;
 
-var Whitespace = require("./whitespace");
-var SourceMap  = require("./source-map");
-var Position   = require("./position");
-var Buffer     = require("./buffer");
-var util       = require("../util");
-var n          = require("./node");
-var t          = require("../types");
-var _          = require("lodash");
+var detectIndent = require("detect-indent");
+var Whitespace   = require("./whitespace");
+var SourceMap    = require("./source-map");
+var Position     = require("./position");
+var Buffer       = require("./buffer");
+var extend       = require("lodash/object/extend");
+var merge        = require("lodash/object/merge");
+var each         = require("lodash/collection/each");
+var util         = require("../util");
+var n            = require("./node");
+var t            = require("../types");
 
 function CodeGenerator(ast, opts, code) {
   opts = opts || {};
 
   this.comments = ast.comments || [];
   this.tokens   = ast.tokens || [];
-  this.format   = CodeGenerator.normaliseOptions(opts);
+  this.format   = CodeGenerator.normalizeOptions(code, opts);
+  this.opts     = opts;
   this.ast      = ast;
 
   this.whitespace = new Whitespace(this.tokens, this.comments);
@@ -30,20 +34,27 @@ function CodeGenerator(ast, opts, code) {
   this.buffer     = new Buffer(this.position, this.format);
 }
 
-_.each(Buffer.prototype, function (fn, key) {
+each(Buffer.prototype, function (fn, key) {
   CodeGenerator.prototype[key] = function () {
     return fn.apply(this.buffer, arguments);
   };
 });
 
-CodeGenerator.normaliseOptions = function (opts) {
-  return _.merge({
+CodeGenerator.normalizeOptions = function (code, opts) {
+  var style = "  ";
+  if (code) {
+    var indent = detectIndent(code).indent;
+    if (indent && indent !== " ") style = indent;
+  }
+
+  return merge({
     parentheses: true,
     comments: opts.comments == null || opts.comments,
     compact: false,
+    concise: false,
     indent: {
       adjustMultilineComment: true,
-      style: "  ",
+      style: style,
       base: 0
     }
   }, opts.format || {});
@@ -64,8 +75,8 @@ CodeGenerator.generators = {
   jsx:              require("./generators/jsx")
 };
 
-_.each(CodeGenerator.generators, function (generator) {
-  _.extend(CodeGenerator.prototype, generator);
+each(CodeGenerator.generators, function (generator) {
+  extend(CodeGenerator.prototype, generator);
 });
 
 CodeGenerator.prototype.generate = function () {
@@ -74,7 +85,7 @@ CodeGenerator.prototype.generate = function () {
   this.print(ast);
 
   var comments = [];
-  _.each(ast.comments, function (comment) {
+  each(ast.comments, function (comment) {
     if (!comment._displayed) comments.push(comment);
   });
   this._printComments(comments);
@@ -102,6 +113,16 @@ CodeGenerator.prototype.buildPrint = function (parent) {
     return self.printJoin(print, nodes, opts);
   };
 
+  print.list = function (items, opts) {
+    opts = opts || {};
+
+    var sep = opts.separator || ", ";
+    if (self.format.compact) sep = ",";
+    opts.separator = sep;
+
+    print.join(items, opts);
+  };
+
   print.block = function (node) {
     return self.printBlock(print, node);
   };
@@ -116,6 +137,15 @@ CodeGenerator.prototype.buildPrint = function (parent) {
 CodeGenerator.prototype.print = function (node, parent, opts) {
   if (!node) return "";
 
+  if (parent && parent._compact) {
+    node._compact = true;
+  }
+
+  var oldConcise = this.format.concise;
+  if (node._compact) {
+    this.format.concise = true;
+  }
+
   var self = this;
 
   opts = opts || {};
@@ -180,6 +210,8 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
   } else {
     throw new ReferenceError("unknown node of type " + JSON.stringify(node.type) + " with constructor " + JSON.stringify(node && node.constructor.name));
   }
+
+  this.format.concise = oldConcise;
 };
 
 CodeGenerator.prototype.printJoin = function (print, nodes, opts) {
@@ -192,7 +224,7 @@ CodeGenerator.prototype.printJoin = function (print, nodes, opts) {
 
   if (opts.indent) self.indent();
 
-  _.each(nodes, function (node, i) {
+  each(nodes, function (node, i) {
     print(node, {
       statement: opts.statement,
       after: function () {
@@ -257,7 +289,7 @@ CodeGenerator.prototype.getComments = function (key, node, parent) {
     nodes.push(node.argument);
   }
 
-  _.each(nodes, function (node) {
+  each(nodes, function (node) {
     comments = comments.concat(self._getComments(key, node));
   });
 
@@ -275,11 +307,11 @@ CodeGenerator.prototype._printComments = function (comments) {
 
   var self = this;
 
-  _.each(comments, function (comment) {
+  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) {
+    each(self.ast.comments, function (origComment) {
       if (origComment.start === comment.start) {
         // comment has already been output
         if (origComment._displayed) skip = true;

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

@@ -5,7 +5,8 @@ module.exports = Node;
 var whitespace = require("./whitespace");
 var parens     = require("./parentheses");
 var t          = require("../../types");
-var _          = require("lodash");
+var each       = require("lodash/collection/each");
+var some       = require("lodash/collection/some");
 
 var find = function (obj, node, parent) {
   if (!obj) return;
@@ -44,7 +45,7 @@ Node.needsWhitespace = function (node, parent, type) {
   var lines = find(whitespace[type].nodes, node, parent);
   if (lines) return lines;
 
-  _.each(find(whitespace[type].list, node, parent), function (expr) {
+  each(find(whitespace[type].list, node, parent), function (expr) {
     lines = Node.needsWhitespace(expr, node, type);
     if (lines) return false;
   });
@@ -65,7 +66,7 @@ Node.needsParens = function (node, parent) {
   if (t.isNewExpression(parent) && parent.callee === node) {
     if (t.isCallExpression(node)) return true;
 
-    var hasCall = _.some(node, function (val) {
+    var hasCall = some(node, function (val) {
       return t.isCallExpression(val);
     });
     if (hasCall) return true;
@@ -94,7 +95,7 @@ Node.needsParensNoLineTerminator = function (node, parent) {
   return false;
 };
 
-_.each(Node, function (fn, key) {
+each(Node, function (fn, key) {
   Node.prototype[key] = function () {
     // Avoid leaking arguments to prevent deoptimization
     var args = new Array(arguments.length + 2);

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

@@ -1,11 +1,11 @@
 "use strict";
 
-var t = require("../../types");
-var _ = require("lodash");
+var t    = require("../../types");
+var each = require("lodash/collection/each");
 
 var PRECEDENCE = {};
 
-_.each([
+each([
   ["||"],
   ["&&"],
   ["|"],
@@ -18,7 +18,7 @@ _.each([
   ["*", "/", "%"],
   ["**"]
 ], function (tier, i) {
-  _.each(tier, function (op) {
+  each(tier, function (op) {
     PRECEDENCE[op] = i;
   });
 });
@@ -151,8 +151,10 @@ exports.ConditionalExpression = function (node, parent) {
     return true;
   }
 
-  if (t.isCallExpression(parent) && parent.callee === node) {
-    return true;
+  if (t.isCallExpression(parent) || t.isNewExpression(parent)) {
+    if (parent.callee === node) {
+      return true;
+    }
   }
 
   if (t.isConditionalExpression(parent) && parent.test === node) {

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

@@ -1,7 +1,9 @@
 "use strict";
 
-var _ = require("lodash");
-var t = require("../../types");
+var t        = require("../../types");
+var each     = require("lodash/collection/each");
+var map      = require("lodash/collection/map");
+var isNumber = require("lodash/lang/isNumber");
 
 exports.before = {
   nodes: {
@@ -31,6 +33,10 @@ exports.before = {
 
 exports.after = {
   nodes: {
+    LogicalExpression: function (node) {
+      return t.isFunction(node.left) || t.isFunction(node.right);
+    },
+
     AssignmentExpression: function (node) {
       if (t.isFunction(node.right)) {
         return 1;
@@ -40,7 +46,7 @@ exports.after = {
 
   list: {
     VariableDeclaration: function (node) {
-      return _.map(node.declarations, "init");
+      return map(node.declarations, "init");
     },
 
     ArrayExpression: function (node) {
@@ -53,7 +59,7 @@ exports.after = {
   }
 };
 
-_.each({
+each({
   Function: 1,
   Class: 1,
   For: 1,
@@ -64,12 +70,12 @@ _.each({
   CallExpression: { after: 1 },
   Literal: { after: 1 }
 }, function (amounts, type) {
-  if (_.isNumber(amounts)) {
+  if (isNumber(amounts)) {
     amounts = { after: amounts, before: amounts };
   }
 
-  _.each([type].concat(t.FLIPPED_ALIAS_KEYS[type] || []), function (type) {
-    _.each(amounts, function (amount, key) {
+  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/source-map.js

@@ -48,8 +48,6 @@ SourceMap.prototype.mark = function (node, type) {
 
   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,

lib/6to5/generation/whitespace.js

@@ -2,7 +2,7 @@
 
 module.exports = Whitespace;
 
-var _    = require("lodash");
+var sortBy = require("lodash/collection/sortBy");
 
 /**
  * Returns `i`th number from `base`, continuing from 0 when `max` is reached.
@@ -23,7 +23,7 @@ function getLookupIndex(i, base, max) {
 }
 
 function Whitespace(tokens, comments) {
-  this.tokens = _.sortBy(tokens.concat(comments), "start");
+  this.tokens = sortBy(tokens.concat(comments), "start");
   this.used   = {};
 
   // Profiling this code shows that while generator passes over it, indexes
@@ -101,7 +101,7 @@ Whitespace.prototype.getNewlinesBetween = function (startToken, endToken) {
   var lines = 0;
 
   for (var line = start; line < end; line++) {
-    if (typeof this.used[line] === 'undefined') {
+    if (typeof this.used[line] === "undefined") {
       this.used[line] = true;
       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(/\r\n|[\n\r\u2028\u2029]/);
+
+  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/levenshtein.js

@@ -0,0 +1,38 @@
+// taken from stackoverflow, it's crap i know.
+
+module.exports = function (a, b) {
+  if (a.length === 0) return b.length;
+  if (b.length === 0) return a.length;
+
+  var matrix = [];
+
+  // increment along the first column of each row
+  var i;
+  for (i = 0; i <= b.length; i++) {
+    matrix[i] = [i];
+  }
+
+  // increment each column in the first row
+  var j;
+  for (j = 0; j <= a.length; j++) {
+    matrix[0][j] = j;
+  }
+
+  // Fill in the rest of the matrix
+  for (i = 1; i <= b.length; i++) {
+    for (j = 1; j <= a.length; j++) {
+      if (b.charAt(i - 1) == a.charAt(j - 1)) {
+        matrix[i][j] = matrix[i - 1][j - 1];
+      } else {
+        matrix[i][j] = Math.min(
+          matrix[i - 1][j - 1] + 1, // substitution
+          Math.min(
+            matrix[i][j - 1] + 1, // insertion
+            matrix[i - 1][j] + 1) // deletion
+          );
+      }
+    }
+  }
+
+  return matrix[b.length][a.length];
+};

lib/6to5/helpers/normalize-ast.js

@@ -0,0 +1,9 @@
+var t = require("../types");
+
+module.exports = function (ast, comments, tokens) {
+  if (ast && ast.type === "Program") {
+    return t.file(ast, comments || [], tokens || []);
+  } else {
+    throw new Error("Not a valid ast?");
+  }
+};

lib/6to5/helpers/object.js

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

lib/6to5/helpers/parse.js

@@ -0,0 +1,49 @@
+var normalizeAst = require("./normalize-ast");
+var estraverse   = require("estraverse");
+var codeFrame    = require("./code-frame");
+var acorn        = require("acorn-6to5");
+
+module.exports = function (opts, code, callback) {
+  try {
+    var comments = [];
+    var tokens   = [];
+
+    var ast = acorn.parse(code, {
+      allowImportExportEverywhere: opts.allowImportExportEverywhere,
+      allowReturnOutsideFunction:  !opts._anal,
+      ecmaVersion:                 opts.experimental ? 7 : 6,
+      playground:                  opts.playground,
+      strictMode:                  opts.strictMode,
+      onComment:                   comments,
+      locations:                   true,
+      onToken:                     tokens,
+      ranges:                      true
+    });
+
+    estraverse.attachComments(ast, comments, tokens);
+
+    ast = normalizeAst(ast, comments, tokens);
+
+    if (callback) {
+      return callback(ast);
+    } else {
+      return ast;
+    }
+  } catch (err) {
+    if (!err._6to5) {
+      err._6to5 = true;
+      var message = opts.filename + ": " + err.message;
+
+      var loc = err.loc;
+      if (loc) {
+        var frame = codeFrame(code, loc.line, loc.column + 1);
+        message += frame;
+      }
+
+      if (err.stack) err.stack = err.stack.replace(err.message, message);
+      err.message = message;
+    }
+
+    throw err;
+  }
+};

lib/6to5/messages.js

@@ -0,0 +1,48 @@
+var util = require("util");
+
+exports.messages = {
+  tailCallReassignmentDeopt: "Function reference has been reassigned so it's probably be dereferenced so we can't optimise this with confidence",
+  JSXNamespacedTags: "Namespace tags are not supported. ReactJSX is not XML.",
+  classesIllegalBareSuper: "Illegal use of bare super",
+  classesIllegalSuperCall: "Direct super call is illegal in non-constructor, use super.$1() instead",
+  classesIllegalConstructorKind: "Illegal kind for constructor method",
+  scopeDuplicateDeclaration: "Duplicate declaration $1",
+  undeclaredVariable: "Reference to undeclared variable $1",
+  undeclaredVariableSuggestion: "Reference to undeclared variable $1 - did you mean $2?",
+  settersInvalidParamLength: "Setters must have only one parameter",
+  noAssignmentsInForHead: "No assignments allowed in for-in/of head",
+  expectedMemberExpressionOrIdentifier: "Expected type MemeberExpression or Identifier",
+  invalidParentForThisNode: "We don't know how to handle this node within the current parent - please open an issue",
+  readOnly: "$1 is read-only",
+  modulesIllegalExportName: "Illegal export $1",
+  unknownForHead: "Unknown node type $1 in ForStatement"
+};
+
+exports.get = function (key) {
+  var msg = exports.messages[key];
+  if (!msg) throw new ReferenceError("Unknown message `" + key + "`");
+
+  var args = [];
+  for (var i = 1; i < arguments.length; i++) {
+    args.push(arguments[i]);
+  }
+  args = exports.parseArgs(args);
+
+  return msg.replace(/\$(\d+)/g, function (str, i) {
+    return args[--i];
+  });
+};
+
+exports.parseArgs = function (args) {
+  return args.map(function (val) {
+    if (val != null && val.inspect) {
+      return val.inspect();
+    } else {
+      try {
+        return JSON.stringify(val) || val + "";
+      } catch (e) {
+        return util.inspect(val);
+      }
+    }
+  });
+};

lib/6to5/patch.js

@@ -1,24 +1,29 @@
 "use strict";
 
-var t = require("./types");
-var _ = require("lodash");
+var extend = require("lodash/object/extend");
+var t      = require("./types");
 
 // estraverse
 
 var estraverse = require("estraverse");
-_.extend(estraverse.VisitorKeys, t.VISITOR_KEYS);
+extend(estraverse.VisitorKeys, t.VISITOR_KEYS);
 
-// regenerator/recast/ast-types
+// 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"));
+  .bases("Pattern")
+  .build("left", "right")
+  .field("left", def("Pattern"))
+  .field("right", def("Expression"));
 
 // Acorn - Same as ImportNamespaceSpecifier but `id` is `name`
 def("ImportBatchSpecifier")
@@ -26,6 +31,11 @@ def("ImportBatchSpecifier")
   .build("name")
   .field("name", def("Identifier"));
 
+def("RestElement")
+  .bases("Pattern")
+  .build("argument")
+  .field("argument", def("expression"));
+
 // Abstract references
 def("VirtualPropertyExpression")
   .bases("Expression")

lib/6to5/polyfill.js

@@ -1,4 +1,9 @@
 "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/runtime");
+require("regenerator-6to5/runtime");

lib/6to5/register.js

@@ -1,104 +0,0 @@
-"use strict";
-
-require("./polyfill");
-
-var sourceMapSupport = require("source-map-support");
-var roadrunner       = require("roadrunner");
-var util             = require("./util");
-var to5              = require("./index");
-var fs               = require("fs");
-var _                = require("lodash");
-
-sourceMapSupport.install({
-  retrieveSourceMap: function (source) {
-    var map = maps && maps[source];
-    if (map) {
-      return {
-        url: null,
-        map: map
-      };
-    } else {
-      return null;
-    }
-  }
-});
-
-var transformOpts = {};
-var ignoreRegex   = /node_modules/;
-var onlyRegex;
-var whitelist     = [];
-var cache;
-var exts          = {};
-var maps          = {};
-var old           = require.extensions[".js"];
-
-var mtime = function (filename) {
-  return +fs.statSync(filename).mtime;
-};
-
-var loader = function (m, filename) {
-  if ((ignoreRegex && ignoreRegex.test(filename)) || (onlyRegex && !onlyRegex.test(filename))) {
-    return old.apply(this, arguments);
-  }
-
-  var result;
-
-  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;
-
-  m._compile(result.code, filename);
-};
-
-var hookExtensions = function (_exts) {
-  _.each(exts, function (old, ext) {
-    require.extensions[ext] = old;
-  });
-
-  exts = {};
-
-  _.each(_exts, function (ext) {
-    exts[ext] = require.extensions[ext];
-    require.extensions[ext] = loader;
-  });
-};
-
-hookExtensions(util.canCompile.EXTENSIONS);
-
-module.exports = function (opts) {
-  // normalise options
-  opts = opts || {};
-  if (_.isRegExp(opts)) opts = { ignore: opts };
-  if (opts.ignoreRegex != null) opts.ignore = opts.ignoreRegex;
-
-  if (opts.only != null) onlyRegex = util.regexify(opts.only);
-  if (opts.ignore != null) ignoreRegex = util.regexify(opts.ignore);
-
-  if (opts.extensions) hookExtensions(util.arrayify(opts.extensions));
-
-  if (opts.cache) cache = opts.cache;
-  if (opts.cache === false) cache = null;
-  if (opts.cache === true) {
-    roadrunner.load();
-    roadrunner.setup();
-    cache = roadrunner.get("6to5");
-  }
-
-  _.extend(transformOpts, opts);
-};

lib/6to5/runtime-generator.js

@@ -1,35 +0,0 @@
-"use strict";
-
-var generator = require("./generation/generator");
-var util      = require("./util");
-var File      = require("./file");
-var t         = require("./types");
-var _         = require("lodash");
-
-module.exports = function (namespace) {
-  namespace = t.identifier(t.toIdentifier(namespace || "to5Runtime"));
-
-  var body      = [];
-  var container = t.functionExpression(null, [t.identifier("global")], t.blockStatement(body));
-  var tree      = t.program([t.expressionStatement(t.callExpression(container, [util.template("self-global")]))]);
-
-  body.push(t.variableDeclaration("var", [
-    t.variableDeclarator(
-      namespace,
-      t.assignmentExpression("=", t.memberExpression(t.identifier("global"), namespace), t.objectExpression([]))
-    )
-  ]));
-
-  _.each(File.helpers, function (name) {
-    if (_.contains(File.excludeHelpersFromRuntime, name)) {
-      return;
-    }
-
-    var key = t.identifier(t.toIdentifier(name));
-    body.push(t.expressionStatement(
-      t.assignmentExpression("=", t.memberExpression(namespace, key), util.template(name))
-    ));
-  });
-
-  return generator(tree).code;
-};

lib/6to5/transformation/file.js

@@ -0,0 +1,445 @@
+"use strict";
+
+module.exports = File;
+
+var SHEBANG_REGEX = /^\#\!.*/;
+
+var isFunction = require("lodash/lang/isFunction");
+var transform  = require("./index");
+var generate   = require("../generation");
+var defaults   = require("lodash/object/defaults");
+var includes   = require("lodash/collection/includes");
+var clone      = require("../helpers/clone");
+var parse      = require("../helpers/parse");
+var Scope      = require("../traversal/scope");
+var util       = require("../util");
+var path       = require("path");
+var each       = require("lodash/collection/each");
+var t          = require("../types");
+
+function File(opts) {
+  this.dynamicImportIds = {};
+  this.dynamicImported  = [];
+  this.dynamicImports   = [];
+
+  this.dynamicData      = {};
+  this.data             = {};
+
+  this.lastStatements   = [];
+  this.opts             = this.normalizeOptions(opts);
+  this.ast              = {};
+
+  this.buildTransformers();
+}
+
+File.helpers = [
+  "inherits",
+  "defaults",
+  "prototype-properties",
+  "apply-constructor",
+  "tagged-template-literal",
+  "tagged-template-literal-loose",
+  "interop-require",
+  "to-array",
+  "to-consumable-array",
+  "sliced-to-array",
+  "object-without-properties",
+  "has-own",
+  "slice",
+  "bind",
+  "define-property",
+  "async-to-generator",
+  "interop-require-wildcard",
+  "typeof",
+  "extends",
+  "get",
+  "set",
+  "class-call-check",
+  "object-destructuring-empty",
+  "temporal-undefined",
+  "temporal-assert-defined",
+  "tail-call"
+];
+
+File.validOptions = [
+  "filename",
+  "filenameRelative",
+  "blacklist",
+  "whitelist",
+  "loose",
+  "optional",
+  "modules",
+  "sourceMap",
+  "sourceMapName",
+  "sourceFileName",
+  "sourceRoot",
+  "moduleRoot",
+  "moduleIds",
+  "comments",
+  "reactCompat",
+  "keepModuleIdExtensions",
+  "code",
+  "ast",
+  "format",
+  "playground",
+  "experimental",
+  "resolveModuleSource",
+  "runtime",
+
+  // these are used by plugins
+  "ignore",
+  "only",
+  "extensions",
+  "accept"
+];
+
+File.prototype.normalizeOptions = function (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, {
+    keepModuleIdExtensions: false,
+    resolveModuleSource:    null,
+    experimental:           false,
+    reactCompat:            false,
+    playground:             false,
+    whitespace:             true,
+    moduleIds:              false,
+    blacklist:              [],
+    whitelist:              [],
+    sourceMap:              false,
+    optional:               [],
+    comments:               true,
+    filename:               "unknown",
+    modules:                "common",
+    runtime:                false,
+    loose:                  [],
+    code:                   true,
+    ast:                    true
+  });
+
+  // normalize windows path separators to unix
+  opts.filename = util.normalisePathSeparator(opts.filename);
+  if (opts.sourceRoot) {
+    opts.sourceRoot = util.normalisePathSeparator(opts.sourceRoot);
+  }
+
+  opts.basename = path.basename(opts.filename, path.extname(opts.filename));
+
+  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 (includes(opts.loose, "all") || includes(opts.loose, true)) {
+    opts.loose = Object.keys(transform.transformers);
+  }
+
+  defaults(opts, {
+    moduleRoot: opts.sourceRoot
+  });
+
+  defaults(opts, {
+    sourceRoot: opts.moduleRoot
+  });
+
+  defaults(opts, {
+    filenameRelative: opts.filename
+  });
+
+  defaults(opts, {
+    sourceFileName: opts.filenameRelative,
+    sourceMapName:  opts.filenameRelative
+  });
+
+  if (opts.playground) {
+    opts.experimental = true;
+  }
+
+  if (opts.runtime) {
+    this.set("runtimeIdentifier", t.identifier("to5Runtime"));
+  }
+
+  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);
+
+  if (opts.reactCompat) {
+    opts.optional.push("reactCompat");
+    console.error("The reactCompat option has been moved into the optional transformer " +
+                  "`reactCompat` - backwards compatibility will be removed in v4.0.0");
+  }
+
+  var ensureEnabled = function (key) {
+    var namespace = transform.transformerNamespaces[key];
+    if (namespace === "es7") opts.experimental = true;
+    if (namespace === "playground") opts.playground = true;
+  };
+
+  each(opts.whitelist, ensureEnabled);
+  each(opts.optional, ensureEnabled);
+
+  return opts;
+};
+
+File.prototype.isLoose = function (key) {
+  return includes(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.debug = function (msg) {
+  var parts = this.opts.filename;
+  if (msg) parts += ": " + msg;
+  util.debug(parts);
+};
+
+File.prototype.getModuleFormatter = function (type) {
+  var ModuleFormatter = isFunction(type) ? type : transform.moduleFormatters[type];
+
+  if (!ModuleFormatter) {
+    var loc = util.resolve(type);
+    if (loc) ModuleFormatter = require(loc);
+  }
+
+  if (!ModuleFormatter) {
+    throw new ReferenceError("Unknown module formatter type " + JSON.stringify(type));
+  }
+
+  return new ModuleFormatter(this);
+};
+
+File.prototype.parseShebang = function (code) {
+  var shebangMatch = code.match(SHEBANG_REGEX);
+  if (shebangMatch) {
+    this.shebang = shebangMatch[0];
+
+    // remove shebang
+    code = code.replace(SHEBANG_REGEX, "");
+  }
+
+  return code;
+};
+
+File.prototype.set = function (key, val) {
+  return this.data[key] = val;
+};
+
+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.scope.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 (!includes(File.helpers, name)) {
+    throw new ReferenceError("Unknown helper " + 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.scope.generateUidIdentifier(name);
+    this.scope.push({
+      key: name,
+      id: uid,
+      init: ref
+    });
+    return uid;
+  }
+};
+
+File.prototype.logDeopt = function () {
+  // todo, (node, msg)
+};
+
+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.addCode(code);
+
+  var opts = this.opts;
+
+  opts.allowImportExportEverywhere = this.isLoose("es6.modules");
+  //opts.strictMode = this.transformers.useStrict.canRun();
+
+  return parse(opts, code, function (tree) {
+    self.transform(tree);
+    return self.generate();
+  });
+};
+
+File.prototype.transform = function (ast) {
+  this.debug();
+
+  this.ast = ast;
+  this.lastStatements = t.getLastStatements(ast.program);
+  this.scope = new Scope(ast.program, ast, null, this);
+
+  var modFormatter = this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
+  if (modFormatter.init && this.transformers["es6.modules"].canRun()) {
+    modFormatter.init();
+  }
+
+  this.checkNode(ast);
+
+  this.call("pre");
+
+  each(this.transformerStack, function (pass) {
+    pass.transform();
+  });
+
+  this.call("post");
+};
+
+File.prototype.call = function (key) {
+  var stack = this.transformerStack;
+  for (var i = 0; i < stack.length; i++) {
+    var transformer = stack[i].transformer;
+    if (transformer[key]) {
+      transformer[key](this);
+    }
+  }
+};
+
+var checkTransformerVisitor = {
+  enter: function (node, parent, scope, state) {
+    checkNode(state.stack, node, scope);
+  }
+};
+
+var checkNode = function (stack, node, scope) {
+  each(stack, function (pass) {
+    if (pass.shouldRun) return;
+    pass.checkNode(node, scope);
+  });
+};
+
+File.prototype.checkNode = function (node, scope) {
+  var stack = this.transformerStack;
+  scope = scope || this.scope;
+
+  checkNode(stack, node, scope);
+
+  scope.traverse(node, checkTransformerVisitor, {
+    stack: stack
+  });
+};
+
+File.prototype.generate = function () {
+  var opts = this.opts;
+  var ast  = this.ast;
+
+  var result = {
+    code: "",
+    map: null,
+    ast: null
+  };
+
+  if (opts.ast) result.ast = ast;
+  if (!opts.code) return result;
+
+  var _result = generate(ast, opts, this.code);
+  result.code = _result.code;
+  result.map  = _result.map;
+
+  if (this.shebang) {
+    // add back shebang
+    result.code = this.shebang + "\n" + result.code;
+  }
+
+  if (opts.sourceMap === "inline") {
+    result.code += "\n" + util.sourceMapToComment(result.map);
+    result.map = null;
+  }
+
+  return result;
+};

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

@@ -12,7 +12,10 @@ module.exports = function (exports, opts) {
     return t.assignmentExpression("=", left, right);
   };
 
-  exports.ExpressionStatement = function (node, parent, scope, context, file) {
+  exports.ExpressionStatement = function (node, parent, scope, file) {
+    // hit the `AssignmentExpression` one below
+    if (file.isConsequenceExpressionStatement(node)) return;
+
     var expr = node.expression;
     if (!isAssignment(expr)) return;
 
@@ -26,14 +29,12 @@ module.exports = function (exports, opts) {
     return nodes;
   };
 
-  exports.AssignmentExpression = function (node, parent, scope, context, file) {
-    if (t.isExpressionStatement(parent)) return;
+  exports.AssignmentExpression = function (node, parent, scope, file) {
     if (!isAssignment(node)) return;
 
     var nodes    = [];
     var exploded = explode(node.left, nodes, file, scope);
-    nodes.push(opts.build(exploded.uid, node.right));
-    nodes.push(exploded.ref);
+    nodes.push(buildAssignment(exploded.ref, opts.build(exploded.uid, node.right)));
 
     return t.toSequenceExpression(nodes, scope);
   };

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

@@ -8,7 +8,10 @@ module.exports = function (exports, opts) {
     return t.assignmentExpression("=", left, right);
   };
 
-  exports.ExpressionStatement = function (node, parent, scope, context, file) {
+  exports.ExpressionStatement = function (node, parent, scope, file) {
+    // hit the `AssignmentExpression` one below
+    if (file.isConsequenceExpressionStatement(node)) return;
+
     var expr = node.expression;
     if (!opts.is(expr, file)) return;
 
@@ -24,8 +27,7 @@ module.exports = function (exports, opts) {
     return nodes;
   };
 
-  exports.AssignmentExpression = function (node, parent, scope, context, file) {
-    if (t.isExpressionStatement(parent)) return;
+  exports.AssignmentExpression = function (node, parent, scope, file) {
     if (!opts.is(node, file)) return;
 
     var nodes    = [];

lib/6to5/transformation/helpers/build-react-transformer.js

@@ -0,0 +1,284 @@
+"use strict";
+
+// Based upon the excellent jsx-transpiler by Ingvar Stepanyan (RReverser)
+// https://github.com/RReverser/jsx-transpiler
+
+// jsx
+
+var isString = require("lodash/lang/isString");
+var messages = require("../../messages");
+var esutils  = require("esutils");
+var react    = require("./react");
+var t        = require("../../types");
+
+module.exports = function (exports, opts) {
+  exports.check = function (node) {
+    if (t.isJSX(node)) return true;
+    if (react.isCreateClass(node)) return true;
+    return false;
+  };
+
+  exports.JSXIdentifier = function (node, parent) {
+    if (node.name === "this" && t.isReferenced(node, parent)) {
+      return t.thisExpression();
+    } else if (esutils.keyword.isIdentifierName(node.name)) {
+      node.type = "Identifier";
+    } else {
+      return t.literal(node.name);
+    }
+  };
+
+  exports.JSXNamespacedName = function (node, parent, scope, file) {
+    throw file.errorWithNode(node, messages.get("JSXNamespacedTags"));
+  };
+
+  exports.JSXMemberExpression = {
+    exit: function (node) {
+      node.computed = t.isLiteral(node.property);
+      node.type = "MemberExpression";
+    }
+  };
+
+  exports.JSXExpressionContainer = function (node) {
+    return node.expression;
+  };
+
+  exports.JSXAttribute = {
+    exit: function (node) {
+      var value = node.value || t.literal(true);
+
+      if (t.isLiteral(value) && isString(value.value)) {
+        value.value = value.value.replace(/\n\s+/g, " ");
+      }
+
+      return t.inherits(t.property("init", node.name, value), node);
+    }
+  };
+  exports.JSXOpeningElement = {
+    exit: function (node, parent, scope, file) {
+      var tagExpr = node.name;
+      var args = [];
+
+      var tagName;
+      if (t.isIdentifier(tagExpr)) {
+        tagName = tagExpr.name;
+      } else if (t.isLiteral(tagExpr)) {
+        tagName = tagExpr.value;
+      }
+
+      var state = {
+        tagExpr: tagExpr,
+        tagName: tagName,
+        args:    args
+      };
+
+      if (opts.pre) {
+        opts.pre(state);
+      }
+
+      var attribs = node.attributes;
+      if (attribs.length) {
+        attribs = buildJSXOpeningElementAttributes(attribs, file);
+      } else {
+        attribs = t.literal(null);
+      }
+
+      args.push(attribs);
+
+      if (opts.post) {
+        opts.post(state);
+      }
+
+      return state.call || t.callExpression(state.callee, args);
+    }
+  };
+
+  /**
+   * The logic for this is quite terse. It's because we need to
+   * support spread elements. We loop over all attributes,
+   * breaking on spreads, we then push a new object containg
+   * all prior attributes to an array for later processing.
+   */
+
+  var buildJSXOpeningElementAttributes = function (attribs, file) {
+    var _props = [];
+    var objs = [];
+
+    var pushProps = function () {
+      if (!_props.length) return;
+
+      objs.push(t.objectExpression(_props));
+      _props = [];
+    };
+
+    while (attribs.length) {
+      var prop = attribs.shift();
+      if (t.isJSXSpreadAttribute(prop)) {
+        pushProps();
+        objs.push(prop.argument);
+      } else {
+        _props.push(prop);
+      }
+    }
+
+    pushProps();
+
+    if (objs.length === 1) {
+      // only one object
+      attribs = objs[0];
+    } else {
+      // looks like we have multiple objects
+      if (!t.isObjectExpression(objs[0])) {
+        objs.unshift(t.objectExpression([]));
+      }
+
+      // spread it
+      attribs = t.callExpression(
+        file.addHelper("extends"),
+        objs
+      );
+    }
+
+    return attribs;
+  };
+
+  exports.JSXElement = {
+    exit: function (node) {
+      var callExpr = node.openingElement;
+
+      for (var i = 0; i < node.children.length; i++) {
+        var child = node.children[i];
+
+        if (t.isLiteral(child) && typeof child.value === "string") {
+          cleanJSXElementLiteralChild(child, callExpr.arguments);
+          continue;
+        } else if (t.isJSXEmptyExpression(child)) {
+          continue;
+        }
+
+        callExpr.arguments.push(child);
+      }
+
+      callExpr.arguments = flatten(callExpr.arguments);
+
+      if (callExpr.arguments.length >= 3) {
+        callExpr._prettyCall = true;
+      }
+
+      return t.inherits(callExpr, node);
+    }
+  };
+
+  var isStringLiteral = function (node) {
+    return t.isLiteral(node) && isString(node.value);
+  };
+
+  var flatten = function (args) {
+    var flattened = [];
+    var last;
+
+    for (var i = 0; i < args.length; i++) {
+      var arg = args[i];
+      if (isStringLiteral(arg) && isStringLiteral(last)) {
+        last.value += arg.value;
+      } else {
+        last = arg;
+        flattened.push(arg);
+      }
+    }
+
+    return flattened;
+  };
+
+  var cleanJSXElementLiteralChild = function (child, args) {
+    var lines = child.value.split(/\r\n|\n|\r/);
+
+    var lastNonEmptyLine = 0;
+    var i;
+
+    for (i = 0; i < lines.length; i++) {
+      if (lines[i].match(/[^ \t]/)) {
+        lastNonEmptyLine = i;
+      }
+    }
+
+    for (i = 0; i < lines.length; i++) {
+      var line = lines[i];
+
+      var isFirstLine = i === 0;
+      var isLastLine = i === lines.length - 1;
+      var isLastNonEmptyLine = i === lastNonEmptyLine;
+
+      // replace rendered whitespace tabs with spaces
+      var trimmedLine = line.replace(/\t/g, " ");
+
+      // trim whitespace touching a newline
+      if (!isFirstLine) {
+        trimmedLine = trimmedLine.replace(/^[ ]+/, "");
+      }
+
+      // trim whitespace touching an endline
+      if (!isLastLine) {
+        trimmedLine = trimmedLine.replace(/[ ]+$/, "");
+      }
+
+      if (trimmedLine) {
+        if (!isLastNonEmptyLine) {
+          trimmedLine += " ";
+        }
+
+        args.push(t.literal(trimmedLine));
+      }
+    }
+  };
+
+  // display names
+
+  var addDisplayName = function (id, call) {
+    var props = call.arguments[0].properties;
+    var safe = true;
+
+    for (var i = 0; i < props.length; i++) {
+      var prop = props[i];
+      if (t.isIdentifier(prop.key, { name: "displayName" })) {
+        safe = false;
+        break;
+      }
+    }
+
+    if (safe) {
+      props.unshift(t.property("init", t.identifier("displayName"), t.literal(id)));
+    }
+  };
+
+  exports.ExportDeclaration = function (node, parent, scope, file) {
+    if (node.default && react.isCreateClass(node.declaration)) {
+      addDisplayName(file.opts.basename, node.declaration);
+    }
+  };
+
+  exports.AssignmentExpression =
+  exports.Property =
+  exports.VariableDeclarator = function (node) {
+    var left, right;
+
+    if (t.isAssignmentExpression(node)) {
+      left = node.left;
+      right = node.right;
+    } else if (t.isProperty(node)) {
+      left = node.key;
+      right = node.value;
+    } else if (t.isVariableDeclarator(node)) {
+      left = node.id;
+      right = node.init;
+    }
+
+    if (t.isMemberExpression(left)) {
+      left = left.property;
+    }
+
+    if (t.isIdentifier(left) && react.isCreateClass(right)) {
+      addDisplayName(left.name, right);
+    }
+  };
+};

lib/6to5/transformation/helpers/define-map.js

@@ -0,0 +1,73 @@
+var cloneDeep = require("lodash/lang/cloneDeep");
+var traverse  = require("../../traversal");
+var clone     = require("lodash/lang/clone");
+var each      = require("lodash/collection/each");
+var has       = require("lodash/object/has");
+var t         = require("../../types");
+
+exports.push = function (mutatorMap, key, kind, computed, value) {
+  var alias;
+
+  if (t.isIdentifier(key)) {
+    alias = key.name;
+    if (computed) alias = "computed:" + alias;
+  } else if (t.isLiteral(key)) {
+    alias = String(key.value);
+  } else {
+    alias = JSON.stringify(traverse.removeProperties(cloneDeep(key)));
+  }
+
+  var map;
+  if (has(mutatorMap, alias)) {
+    map = mutatorMap[alias];
+  } else {
+    map = {};
+  }
+  mutatorMap[alias] = map;
+
+  map._key = key;
+  if (computed) {
+    map._computed = true;
+  }
+
+  map[kind] = value;
+};
+
+exports.build = function (mutatorMap) {
+  var objExpr = t.objectExpression([]);
+
+  each(mutatorMap, function (map) {
+    var mapNode = t.objectExpression([]);
+
+    var propNode = t.property("init", map._key, mapNode, map._computed);
+
+    if (!map.get && !map.set) {
+      map.writable = t.literal(true);
+    }
+
+    if (map.enumerable === false) {
+      delete map.enumerable;
+    } else {
+      map.enumerable = t.literal(true);
+    }
+
+    map.configurable = t.literal(true);
+
+    each(map, function (node, key) {
+      if (key[0] === "_") return;
+
+      node = clone(node);
+      var inheritNode = node;
+      if (t.isMethodDefinition(node)) node = node.value;
+
+      var prop = t.property("init", t.identifier(key), node);
+      t.inheritsComments(prop, inheritNode);
+      t.removeComments(inheritNode);
+      mapNode.properties.push(prop);
+    });
+
+    objExpr.properties.push(propNode);
+  });
+
+  return objExpr;
+};

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

@@ -5,14 +5,30 @@ var t = require("../../types");
 var getObjRef = function (node, nodes, file, scope) {
   var ref;
   if (t.isIdentifier(node)) {
-    ref = node;
+    if (scope.hasBinding(node.name)) {
+      // 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.hasGlobal(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, file);
+  var temp = scope.generateUidBasedOnNode(ref);
   nodes.push(t.variableDeclaration("var", [
     t.variableDeclarator(temp, ref)
   ]));
@@ -24,7 +40,7 @@ var getPropRef = function (node, nodes, file, scope) {
   var key = t.toComputedKey(node, prop);
   if (t.isLiteral(key)) return key;
 
-  var temp = scope.generateUidBasedOnNode(prop, file);
+  var temp = scope.generateUidBasedOnNode(prop);
   nodes.push(t.variableDeclaration("var", [
     t.variableDeclarator(temp, prop)
   ]));

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

@@ -1,11 +1,10 @@
 "use strict";
 
-var traverse = require("../../traverse");
-var util     = require("../../util");
-var t        = require("../../types");
+var util = require("../../util");
+var t    = require("../../types");
 
-var traverser = {
-  enter: function (node, parent, scope, context, state) {
+var visitor = {
+  enter: function (node, parent, scope, state) {
     // check if this node is an identifier that matches the same as our function id
     if (!t.isIdentifier(node, { name: state.id })) return;
 
@@ -14,11 +13,11 @@ var traverser = {
 
     // 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);
+    var localDeclar = scope.getBindingIdentifier(state.id);
     if (localDeclar !== state.outerDeclar) return;
 
     state.selfReference = true;
-    context.stop();
+    this.stop();
   }
 };
 
@@ -32,19 +31,23 @@ exports.property = function (node, file, scope) {
   var state = {
     id: id,
     selfReference: false,
-    outerDeclar: scope.get(id, true),
+    outerDeclar: scope.getBindingIdentifier(id),
   };
 
-  traverse(node, traverser, scope, state);
+  scope.traverse(node, visitor, state);
+
+  var method = node.value;
 
   if (state.selfReference) {
-    node.value = util.template("property-method-assignment-wrapper", {
-      FUNCTION: node.value,
+    var templateName = "property-method-assignment-wrapper";
+    if (method.generator) templateName += "-generator";
+    node.value = util.template(templateName, {
+      FUNCTION: method,
       FUNCTION_ID: key,
-      FUNCTION_KEY: file.generateUidIdentifier(id, scope),
-      WRAPPER_KEY: file.generateUidIdentifier(id + "Wrapper", scope)
+      FUNCTION_KEY: scope.generateUidIdentifier(id),
+      WRAPPER_KEY: scope.generateUidIdentifier(id + "Wrapper")
     });
   } else {
-    node.value.id = key;
+    method.id = key;
   }
 };

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

@@ -0,0 +1,26 @@
+var t = require("../../types");
+
+var isCreateClassCallExpression = t.buildMatchMemberExpression("React.createClass");
+
+exports.isCreateClass = function (node) {
+  if (!node || !t.isCallExpression(node)) return false;
+
+  // not React.createClass call member object
+  if (!isCreateClassCallExpression(node.callee)) return false;
+
+  // no call arguments
+  var args = node.arguments;
+  if (args.length !== 1) return false;
+
+  // first node arg is not an object
+  var first = args[0];
+  if (!t.isObjectExpression(first)) return false;
+
+  return true;
+};
+
+exports.isReactComponent = t.buildMatchMemberExpression("React.Component");
+
+exports.isCompatTag = function (tagName) {
+  return tagName && /^[a-z]|\-/.test(tagName);
+};

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

@@ -1,27 +1,36 @@
 "use strict";
 
-var traverse = require("../../traverse");
-var t        = require("../../types");
+var t = require("../../types");
 
-module.exports = function (node, callId) {
+var visitor = {
+  enter: function (node) {
+    if (t.isFunction(node)) this.skip();
+
+    if (t.isAwaitExpression(node)) {
+      node.type = "YieldExpression";
+
+      if (node.all) {
+        // await* foo; -> yield Promise.all(foo);
+        node.all = false;
+        node.argument = t.callExpression(t.memberExpression(t.identifier("Promise"), t.identifier("all")), [node.argument]);
+      }
+    }
+  }
+};
+
+module.exports = function (node, callId, scope) {
   node.async = false;
   node.generator = true;
 
-  traverse(node, {
-    enter: function (node, parent, scope, context) {
-      if (t.isFunction(node)) context.skip();
-
-      if (t.isAwaitExpression(node)) {
-        node.type = "YieldExpression";
-      }
-    }
-  });
+  scope.traverse(node, visitor);
 
   var call = t.callExpression(callId, [node]);
+  var id = node.id;
+  delete node.id;
 
   if (t.isFunctionDeclaration(node)) {
-    var declar = t.variableDeclaration("var", [
-      t.variableDeclarator(node.id, call)
+    var declar = t.variableDeclaration("let", [
+      t.variableDeclarator(id, call)
     ]);
     declar._blockHoist = true;
     return declar;

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

@@ -2,28 +2,61 @@
 
 module.exports = ReplaceSupers;
 
-var traverse = require("../../traverse");
+var messages = require("../../messages");
 var t        = require("../../types");
 
 /**
  * Description
  *
- * @param {Object} methodNode
- * @param {Object} className
- * @param {Object} superName
- * @param {Boolean} isLoose
- * @param {File} file
+ * @param {Object} opts
+ * @param {Boolean} [inClass]
  */
 
-function ReplaceSupers(methodNode, className, superName, isLoose, file) {
-  this.topLevelThisReference = null;
-  this.methodNode            = methodNode;
-  this.className             = className;
-  this.superName             = superName;
-  this.isLoose               = isLoose;
-  this.file                  = file;
+function ReplaceSupers(opts, inClass) {
+  this.topLevelThisReference = opts.topLevelThisReference;
+  this.methodNode            = opts.methodNode;
+  this.className             = opts.className;
+  this.superName             = opts.superName;
+  this.isStatic              = opts.isStatic;
+  this.hasSuper              = false;
+  this.inClass               = inClass;
+  this.isLoose               = opts.isLoose;
+  this.scope                 = opts.scope;
+  this.file                  = opts.file;
 }
 
+/**
+ * Sets a super class value of the named property.
+ *
+ * @example
+ *
+ *   _set(Object.getPrototypeOf(CLASS.prototype), "METHOD", "VALUE", this)
+ *
+ * @param {Node} property
+ * @param {Node} value
+ * @param {Boolean} isComputed
+ * @param {Node} thisExpression
+ *
+ * @returns {Node}
+ */
+
+ReplaceSupers.prototype.setSuperProperty = function (property, value, isComputed, thisExpression) {
+  return t.callExpression(
+    this.file.addHelper("set"),
+    [
+      t.callExpression(
+        t.memberExpression(t.identifier("Object"), t.identifier("getPrototypeOf")),
+        [
+          this.isStatic ? this.className : t.memberExpression(this.className, t.identifier("prototype"))
+        ]
+      ),
+      isComputed ? property : t.literal(property.name),
+      value,
+      thisExpression
+    ]
+  );
+};
+
 /**
  * Gets a node representing the super class value of the named property.
  *
@@ -32,20 +65,20 @@ function ReplaceSupers(methodNode, className, superName, isLoose, file) {
  *   _get(Object.getPrototypeOf(CLASS.prototype), "METHOD", this)
  *
  * @param {Node} property
- * @param {boolean} isStatic
- * @param {boolean} isComputed
+ * @param {Boolean} isComputed
+ * @param {Node} thisExpression
  *
  * @returns {Node}
  */
 
-ReplaceSupers.prototype.superProperty = function (property, isStatic, isComputed, thisExpression) {
+ReplaceSupers.prototype.getSuperProperty = function (property, 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"))
+          this.isStatic ? this.className : t.memberExpression(this.className, t.identifier("prototype"))
         ]
       ),
       isComputed ? property : t.literal(property.name),
@@ -54,6 +87,70 @@ ReplaceSupers.prototype.superProperty = function (property, isStatic, isComputed
   );
 };
 
+/**
+ * Description
+ */
+
+ReplaceSupers.prototype.replace = function () {
+  this.traverseLevel(this.methodNode.value, true);
+};
+
+var visitor = {
+  enter: function (node, parent, scope, 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 this.skip();
+    }
+
+    if (t.isProperty(node, { method: true }) || t.isMethodDefinition(node)) {
+      // break on object methods
+      return this.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.bind(self);
+
+    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 };
+  this.scope.traverse(node, visitor, state);
+};
+
+/**
+ * Description
+ */
+
+ReplaceSupers.prototype.getThisReference = function () {
+  if (this.topLevelThisReference) {
+    return this.topLevelThisReference;
+  } else {
+    var ref = this.topLevelThisReference = this.scope.generateUidIdentifier("this");
+    this.methodNode.value.body.body.unshift(t.variableDeclaration("var", [
+      t.variableDeclarator(this.topLevelThisReference, t.thisExpression())
+    ]));
+    return ref;
+  }
+};
+
 /**
  * Description
  *
@@ -63,7 +160,8 @@ ReplaceSupers.prototype.superProperty = function (property, isStatic, isComputed
  * @returns {Object}
  */
 
-ReplaceSupers.prototype.looseSuperProperty = function (methodNode, id, parent) {
+ReplaceSupers.prototype.getLooseSuperProperty = function (id, parent) {
+  var methodNode = this.methodNode;
   var methodName = methodNode.key;
   var superName  = this.superName || t.identifier("Function");
 
@@ -95,70 +193,6 @@ ReplaceSupers.prototype.looseSuperProperty = function (methodNode, id, parent) {
   }
 };
 
-/**
- * Description
- */
-
-ReplaceSupers.prototype.replace = function () {
-  this.traverseLevel(this.methodNode.value, true);
-};
-
-/**
- * Description
- *
- * @param {Object} node
- * @param {Boolean} topLevel
- */
-
-ReplaceSupers.prototype.traverseLevel = function (node, topLevel) {
-  var self = this;
-
-  traverse(node, {
-    enter: function (node, parent, scope, context) {
-      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 = function () {
-        if (topLevel) {
-          // top level so `this` is the instance
-          return t.thisExpression();
-        } else {
-          // not in the top level so we need to create a reference
-          return self.getThisReference();
-        }
-      };
-
-      var callback = self.specHandle;
-      if (self.isLoose) callback = self.looseHandle;
-      return callback.call(self, getThisReference, node, parent);
-    }
-  });
-};
-
-/**
- * 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
  *
@@ -169,13 +203,15 @@ ReplaceSupers.prototype.getThisReference = function () {
 
 ReplaceSupers.prototype.looseHandle = function (getThisReference, node, parent) {
   if (t.isIdentifier(node, { name: "super" })) {
-    return this.looseSuperProperty(this.methodNode, node, parent);
+    this.hasSuper = true;
+    return this.getLooseSuperProperty(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);
+    this.hasSuper = true;
     t.appendToMemberExpression(callee, t.identifier("call"));
     node.arguments.unshift(getThisReference());
   }
@@ -194,39 +230,49 @@ ReplaceSupers.prototype.specHandle = function (getThisReference, node, parent) {
   var property;
   var computed;
   var args;
+  var thisReference;
 
-  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)) {
+  if (isIllegalBareSuper(node, parent)) {
+    throw this.file.errorWithNode(node, messages.get("classesIllegalBareSuper"));
+  }
+
+  if (t.isCallExpression(node)) {
     var callee = node.callee;
-    if (t.isIdentifier(callee, { name: "super" })) {
+    if (isSuper(callee, node)) {
       // super(); -> _get(Object.getPrototypeOf(ClassName), "MethodName", this).call(this);
       property = methodNode.key;
       computed = methodNode.computed;
       args = node.arguments;
-    } else {
-      if (!t.isMemberExpression(callee)) return;
-      if (callee.object.name !== "super") return;
 
+      // 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" || !this.inClass) {
+        var methodName = methodNode.key.name || "METHOD_NAME";
+        throw this.file.errorWithNode(node, messages.get("classesIllegalSuperCall", methodName));
+      }
+    } else if (t.isMemberExpression(callee) && isSuper(callee.object, callee)) {
       // 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;
-
+  } else if (t.isMemberExpression(node) && isSuper(node.object, node)) {
     // super.name; -> _get(Object.getPrototypeOf(ClassName.prototype), "name", this);
     property = node.property;
     computed = node.computed;
+  } else if (t.isAssignmentExpression(node) && isSuper(node.left.object, node.left) && methodNode.kind === "set") {
+    // super.name = "val"; -> _set(Object.getPrototypeOf(ClassName.prototype), "name", this);
+    this.hasSuper = true;
+    return this.setSuperProperty(node.left.property, node.right, node.left.computed, getThisReference());
   }
 
   if (!property) return;
 
-  var thisReference = getThisReference();
-  var superProperty = this.superProperty(property, methodNode.static, computed, thisReference);
+  this.hasSuper = true;
+
+  thisReference = getThisReference();
+  var superProperty = this.getSuperProperty(property, computed, thisReference);
   if (args) {
     if (args.length === 1 && t.isSpreadElement(args[0])) {
       // super(...arguments);
@@ -244,3 +290,14 @@ ReplaceSupers.prototype.specHandle = function (getThisReference, node, parent) {
     return superProperty;
   }
 };
+
+var isIllegalBareSuper = function (node, parent) {
+  if (!isSuper(node, parent)) return false;
+  if (t.isMemberExpression(parent, { computed: false })) return false;
+  if (t.isCallExpression(parent, { callee: node })) return false;
+  return true;
+};
+
+var isSuper = function (node, parent) {
+  return t.isIdentifier(node, { name: "super" }) && t.isReferenced(node, parent);
+};

lib/6to5/transformation/index.js

@@ -0,0 +1,76 @@
+"use strict";
+
+module.exports = transform;
+
+var normalizeAst = require("../helpers/normalize-ast");
+var Transformer  = require("./transformer");
+var object       = require("../helpers/object");
+var File         = require("./file");
+var each         = require("lodash/collection/each");
+
+function transform(code, opts) {
+  var file = new File(opts);
+  return file.parse(code);
+}
+
+transform.fromAst = function (ast, code, opts) {
+  ast = normalizeAst(ast);
+
+  var file = new File(opts);
+  file.addCode(code);
+  file.transform(ast);
+  return file.generate();
+};
+
+transform._ensureTransformerNames = function (type, rawKeys) {
+  var keys = [];
+
+  for (var i = 0; i < rawKeys.length; i++) {
+    var key = rawKeys[i];
+
+    var deprecatedKey = transform.deprecatedTransformerMap[key];
+    if (deprecatedKey) {
+      // deprecated key, remap it to the new one
+      console.error(
+        "The transformer " + key + " has been renamed to " + deprecatedKey +
+        " in v3.0.0 - backwards compatibilty will be removed 4.0.0"
+      );
+      rawKeys.push(deprecatedKey);
+    } else if (transform.transformers[key]) {
+      // valid key
+      keys.push(key);
+    } else if (transform.namespaces[key]) {
+      // namespace, append all transformers within this namespace
+      keys = keys.concat(transform.namespaces[key]);
+    } else {
+      // invalid key
+      throw new ReferenceError(
+        "Unknown transformer " + key + " specified in " + type + " - " +
+        "transformer key names have been changed in 3.0.0 see " +
+        "the changelog for more info " +
+        "https://github.com/6to5/6to5/blob/master/CHANGELOG.md#300"
+      );
+    }
+  }
+
+  return keys;
+};
+
+transform.transformerNamespaces = object();
+transform.transformers          = object();
+transform.namespaces            = object();
+
+transform.deprecatedTransformerMap = require("./transformers/deprecated");
+transform.moduleFormatters = require("./modules");
+
+var rawTransformers = require("./transformers");
+
+each(rawTransformers, function (transformer, key) {
+  var namespace = key.split(".")[0];
+
+  transform.namespaces[namespace] = transform.namespaces[namespace] || [];
+  transform.namespaces[namespace].push(key);
+  transform.transformerNamespaces[key] = namespace;
+
+  transform.transformers[key] = new Transformer(key, transformer);
+});

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

@@ -2,84 +2,128 @@
 
 module.exports = DefaultFormatter;
 
-var traverse = require("../../traverse");
+var messages = require("../../messages");
+var extend   = require("lodash/object/extend");
+var object   = require("../../helpers/object");
 var util     = require("../../util");
 var t        = require("../../types");
-var _        = require("lodash");
 
 function DefaultFormatter(file) {
-  this.file = file;
+  this.scope = file.scope;
+  this.file  = file;
+  this.ids   = object();
 
-  this.localExports = this.getLocalExports();
-  this.localImports = this.getLocalImports();
+  this.hasNonDefaultExports = false;
+
+  this.hasLocalExports = false;
+  this.hasLocalImports = false;
+
+  this.localImportOccurences = object();
+  this.localExports = object();
+  this.localImports = object();
+
+  this.getLocalExports();
+  this.getLocalImports();
 
   this.remapAssignments();
-
-  //this.checkCollisions();
 }
 
-var exportsTraverser = {
-  enter: function (node, parent, scope, context, localExports) {
+DefaultFormatter.prototype.doDefaultExportInterop = function (node) {
+  return node.default && !this.noInteropRequireExport && !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, formatter) {
     var declar = node && node.declaration;
-    if (t.isExportDeclaration(node) && declar && t.isStatement(declar)) {
-      _.extend(localExports, t.getIds(declar, true));
+    if (t.isExportDeclaration(node)) {
+      formatter.hasLocalImports = true;
+
+      if (declar && t.isStatement(declar)) {
+        extend(formatter.localExports, t.getBindingIdentifiers(declar));
+      }
+
+      if (!node.default) {
+        formatter.hasNonDefaultExports = true;
+      }
+
+      if (node.source) {
+        formatter.bumpImportOccurences(node);
+      }
     }
   }
 };
 
 DefaultFormatter.prototype.getLocalExports = function () {
-  var localExports = {};
-  traverse(this.file.ast, exportsTraverser, null, localExports);
-  return localExports;
+  this.file.scope.traverse(this.file.ast, exportsVisitor, this);
 };
 
-var importsTraverser = {
-  enter: function (node, parent, scope, context, localImports) {
+var importsVisitor = {
+  enter: function (node, parent, scope, formatter) {
     if (t.isImportDeclaration(node)) {
-      _.extend(localImports, t.getIds(node, true));
+      formatter.hasLocalImports = true;
+      extend(formatter.localImports, t.getBindingIdentifiers(node));
+      formatter.bumpImportOccurences(node);
     }
   }
 };
 
 DefaultFormatter.prototype.getLocalImports = function () {
-  var localImports = {};
-  traverse(this.file.ast, importsTraverser, null, localImports);
-  return localImports;
+  this.file.scope.traverse(this.file.ast, importsVisitor, this);
 };
 
-var collissionsTraverser = {
-  enter: function (node, parent, scope, context, check) {
-    if (t.isAssignmentExpression(node)) {
+var remapVisitor = {
+  enter: function (node, parent, scope, formatter) {
+    if (t.isUpdateExpression(node) && formatter.isLocalReference(node.argument, scope)) {
+      this.skip();
 
-      var left = node.left;
-      if (t.isMemberExpression(left)) {
-        while (left.object) left = left.object;
+      // 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;
       }
 
-      check(left);
-    } else if (t.isDeclaration(node)) {
-      _.each(t.getIds(node, true), check);
+      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)) {
+      this.skip();
+      return formatter.remapExportAssignment(node);
     }
   }
 };
 
-DefaultFormatter.prototype.checkCollisions = function () {
-  // todo: all check export collissions
+DefaultFormatter.prototype.remapAssignments = function () {
+  if (this.hasLocalImports) {
+    this.file.scope.traverse(this.file.ast, remapVisitor, this);
+  }
+};
 
+DefaultFormatter.prototype.isLocalReference = function (node) {
   var localImports = this.localImports;
-  var file = this.file;
-
-  var isLocalReference = function (node) {
-    return t.isIdentifier(node) && _.has(localImports, node.name) && localImports[node.name] !== node;
-  };
-
-  var check = function (node) {
-    if (isLocalReference(node)) {
-      throw file.errorWithNode(node, "Illegal assignment of module import");
-    }
-  };
-
-  traverse(file.ast, collissionsTraverser, null, check);
+  return t.isIdentifier(node) && localImports[node.name] && localImports[node.name] !== node;
 };
 
 DefaultFormatter.prototype.remapExportAssignment = function (node) {
@@ -94,51 +138,10 @@ DefaultFormatter.prototype.remapExportAssignment = function (node) {
   );
 };
 
-DefaultFormatter.prototype.remapAssignments = function () {
+DefaultFormatter.prototype.isLocalReference = function (node, scope) {
   var localExports = this.localExports;
-  var self = this;
-
-  var isLocalReference = function (node, scope) {
-    var name = node.name;
-    return t.isIdentifier(node) && localExports[name] && localExports[name] === scope.get(name, true);
-  };
-
-  traverse(this.file.ast, {
-    enter: function (node, parent, scope, context, isLocalReference) {
-      if (t.isUpdateExpression(node) && 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 = self.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) && isLocalReference(node.left, scope)) {
-        context.skip();
-        return self.remapExportAssignment(node);
-      }
-    }
-  }, null, isLocalReference);
+  var name = node.name;
+  return t.isIdentifier(node) && localExports[name] && localExports[name] === scope.getBindingIdentifier(name);
 };
 
 DefaultFormatter.prototype.getModuleName = function () {
@@ -162,12 +165,12 @@ DefaultFormatter.prototype.getModuleName = function () {
 
   if (!opts.keepModuleIdExtensions) {
     // remove extension
-    filenameRelative = filenameRelative.replace(/\.(.*?)$/, "");
+    filenameRelative = filenameRelative.replace(/\.(\w*?)$/, "");
   }
 
   moduleName += filenameRelative;
 
-  // normalise path separators
+  // normalize path separators
   moduleName = moduleName.replace(/\\/g, "/");
 
   return moduleName;
@@ -192,25 +195,40 @@ DefaultFormatter.prototype._hoistExport = function (declar, assign, priority) {
   return assign;
 };
 
-DefaultFormatter.prototype._exportSpecifier = function (getRef, specifier, node, nodes) {
-  var inherits = false;
-  if (node.specifiers.length === 1) inherits = node;
+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.checkExportIdentifier = function (node) {
+  if (t.isIdentifier(node, { name: "__esModule" })) {
+    throw this.file.errorWithNode(node, messages.get("modulesIllegalExportName", node.name));
+  }
+};
+
+DefaultFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
   if (node.source) {
+    var ref = this.getExternalReference(node, nodes);
+
     if (t.isExportBatchSpecifier(specifier)) {
       // export * from "foo";
-      nodes.push(this._exportsWildcard(getRef(), node));
+      nodes.push(this.buildExportsWildcard(ref, node));
     } else {
-      var ref;
-      if (t.isSpecifierDefault(specifier) && !this.noInteropRequire) {
-        // importing a default so we need to normalise it
-        ref = t.callExpression(this.file.addHelper("interop-require"), [getRef()]);
+      if (t.isSpecifierDefault(specifier) && !this.noInteropRequireExport) {
+        // importing a default so we need to normalize it
+        ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
       } else {
-        ref = t.memberExpression(getRef(), specifier.id);
+        ref = t.memberExpression(ref, t.getSpecifierId(specifier));
       }
 
       // export { foo } from "test";
-      nodes.push(this._exportsAssign(
+      nodes.push(this.buildExportsAssignment(
         t.getSpecifierName(specifier),
         ref,
         node
@@ -218,18 +236,19 @@ DefaultFormatter.prototype._exportSpecifier = function (getRef, specifier, node,
     }
   } else {
     // export { foo };
-    nodes.push(this._exportsAssign(t.getSpecifierName(specifier), specifier.id, node));
+    nodes.push(this.buildExportsAssignment(t.getSpecifierName(specifier), specifier.id, node));
   }
 };
 
-DefaultFormatter.prototype._exportsWildcard = function (objectIdentifier) {
+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._exportsAssign = function (id, init) {
+DefaultFormatter.prototype.buildExportsAssignment = function (id, init) {
+  this.checkExportIdentifier(id);
   return util.template("exports-assign", {
     VALUE: init,
     KEY:   id
@@ -251,7 +270,7 @@ DefaultFormatter.prototype.exportDeclaration = function (node, nodes) {
     for (var i = 0; i < declar.declarations.length; i++) {
       var decl = declar.declarations[i];
 
-      decl.init = this._exportsAssign(decl.id, decl.init, node).expression;
+      decl.init = this.buildExportsAssignment(decl.id, decl.init, node).expression;
 
       var newDeclar = t.variableDeclaration(declar.kind, [decl]);
       if (i === 0) t.inherits(newDeclar, declar);
@@ -265,7 +284,7 @@ DefaultFormatter.prototype.exportDeclaration = function (node, nodes) {
       nodes.push(declar);
     }
 
-    assign = this._exportsAssign(id, ref, node);
+    assign = this.buildExportsAssignment(id, ref, node);
 
     nodes.push(assign);
 

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

@@ -4,7 +4,7 @@ var util = require("../../util");
 
 module.exports = function (Parent) {
   var Constructor = function () {
-    this.noInteropExport = true;
+    this.noInteropRequireExport = true;
     Parent.apply(this, arguments);
   };
 

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

@@ -6,15 +6,17 @@ var DefaultFormatter = require("./_default");
 var CommonFormatter  = require("./common");
 var util             = require("../../util");
 var t                = require("../../types");
-var _                = require("lodash");
+var includes         = require("lodash/collection/includes");
+var values           = require("lodash/object/values");
 
 function AMDFormatter() {
   CommonFormatter.apply(this, arguments);
-  this.ids = {};
 }
 
 util.inherits(AMDFormatter, DefaultFormatter);
 
+AMDFormatter.prototype.init = CommonFormatter.prototype.init;
+
 AMDFormatter.prototype.buildDependencyLiterals = function () {
   var names = [];
   for (var name in this.ids) {
@@ -27,9 +29,8 @@ AMDFormatter.prototype.buildDependencyLiterals = function () {
  * Wrap the entire body in a `define` wrapper.
  */
 
-AMDFormatter.prototype.transform = function (ast) {
-  var program = ast.program;
-  var body    = program.body;
+AMDFormatter.prototype.transform = function (program) {
+  var body = program.body;
 
   // build an array of module names
 
@@ -40,7 +41,7 @@ AMDFormatter.prototype.transform = function (ast) {
 
   // build up define container
 
-  var params = _.values(this.ids);
+  var params = values(this.ids);
   if (this.passModuleArg) params.unshift(t.identifier("module"));
   params.unshift(t.identifier("exports"));
 
@@ -68,33 +69,29 @@ AMDFormatter.prototype.getModuleName = function () {
   }
 };
 
-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] = this.file.generateUidIdentifier(id);
-  }
+AMDFormatter.prototype._getExternalReference = function (node) {
+  return this.scope.generateUidIdentifier(node.source.value);
 };
 
 AMDFormatter.prototype.importDeclaration = function (node) {
-  this._push(node);
+  this.getExternalReference(node);
 };
 
 AMDFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
   var key = t.getSpecifierName(specifier);
-  var ref = this._push(node);
+  var ref = this.getExternalReference(node);
 
-  if (t.isImportBatchSpecifier(specifier)) {
+  if (includes(this.file.dynamicImported, node)) {
+    // Prevent unnecessary renaming of dynamic imports.
+    this.ids[node.source.value] = ref;
+  } else if (t.isImportBatchSpecifier(specifier)) {
     // import * as bar from "foo";
-  } else if (t.isSpecifierDefault(specifier) && !this.noInteropRequire) {
+  } else if (t.isSpecifierDefault(specifier) && !this.noInteropRequireImport) {
     // import foo from "foo";
     ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
   } else {
     // import {foo} from "foo";
-    ref = t.memberExpression(ref, specifier.id, false);
+    ref = t.memberExpression(ref, t.getSpecifierId(specifier), false);
   }
 
   nodes.push(t.variableDeclaration("var", [
@@ -103,16 +100,9 @@ AMDFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
 };
 
 AMDFormatter.prototype.exportDeclaration = function (node) {
-  if (node.default && !this.noInteropExport) {
+  if (this.doDefaultExportInterop(node)) {
     this.passModuleArg = true;
   }
 
   CommonFormatter.prototype.exportDeclaration.apply(this, arguments);
 };
-
-AMDFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
-  var self = this;
-  return this._exportSpecifier(function () {
-    return self._push(node);
-  }, specifier, node, nodes);
-};

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

@@ -0,0 +1,13 @@
+"use strict";
+
+module.exports = CommonStandardFormatter;
+
+var CommonStrictFormatter = require("./common-strict");
+var util = require("../../util");
+
+function CommonStandardFormatter() {
+  this.noInteropRequireImport = true;
+  CommonStrictFormatter.apply(this, arguments);
+}
+
+util.inherits(CommonStandardFormatter, CommonStrictFormatter);

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

@@ -3,54 +3,61 @@
 module.exports = CommonJSFormatter;
 
 var DefaultFormatter = require("./_default");
-var traverse         = require("../../traverse");
+var includes         = require("lodash/collection/includes");
 var util             = require("../../util");
 var t                = require("../../types");
 
-function CommonJSFormatter(file) {
+function CommonJSFormatter() {
   DefaultFormatter.apply(this, arguments);
-
-  var hasNonDefaultExports = false;
-  traverse(file.ast, {
-    enter: function (node) {
-      if (t.isExportDeclaration(node) && !node.default) hasNonDefaultExports = true;
-    }
-  });
-  this.hasNonDefaultExports = hasNonDefaultExports;
 }
 
 util.inherits(CommonJSFormatter, DefaultFormatter);
 
+CommonJSFormatter.prototype.init = function () {
+  var file  = this.file;
+  var scope = file.scope;
+
+  scope.rename("module");
+
+  if (!this.noInteropRequireImport && this.hasNonDefaultExports) {
+    file.ast.program.body.push(util.template("exports-module-declaration", true));
+  }
+};
+
 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)) {
-    nodes.push(t.variableDeclaration("var", [
-      t.variableDeclarator(variableName,
-        t.callExpression(this.file.addHelper("interop-require"), [util.template("require", {
-          MODULE_NAME: node.source
-        })])
-      )
-    ]));
+    if (!includes(this.file.dynamicImported, node)) {
+      if (this.noInteropRequireImport) {
+        ref = t.memberExpression(ref, t.identifier("default"));
+      } else {
+        ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
+      }
+    }
+    nodes.push(t.variableDeclaration("var", [t.variableDeclarator(variableName, ref)]));
   } else {
     if (specifier.type === "ImportBatchSpecifier") {
+
+      if (!this.noInteropRequireImport) {
+        ref = t.callExpression(this.file.addHelper("interop-require-wildcard"), [ref]);
+      }
+
       // import * as bar from "foo";
+      nodes.push(t.variableDeclaration("var", [
+        t.variableDeclarator(variableName, ref)
+      ]));
+    } else {
+      // import { foo } from "foo";
       nodes.push(t.variableDeclaration("var", [
         t.variableDeclarator(
           variableName,
-          t.callExpression(this.file.addHelper("interop-require-wildcard"), [
-            t.callExpression(t.identifier("require"), [node.source])
-          ])
+          t.memberExpression(ref, t.getSpecifierId(specifier))
         )
       ]));
-    } else {
-      // import foo from "foo";
-      nodes.push(util.template("require-assign-key", {
-        VARIABLE_NAME: variableName,
-        MODULE_NAME:   node.source,
-        KEY:           specifier.id
-      }));
     }
   }
 };
@@ -63,45 +70,35 @@ CommonJSFormatter.prototype.importDeclaration = function (node, nodes) {
 };
 
 CommonJSFormatter.prototype.exportDeclaration = function (node, nodes) {
-  if (node.default && !this.noInteropRequire && !this.noInteropExport) {
+  if (this.doDefaultExportInterop(node)) {
     var declar = node.declaration;
-    var assign;
+    var assign = util.template("exports-default-assign", {
+      VALUE: this._pushStatement(declar, nodes)
+    }, true);
 
-    // module.exports = VALUE;
-    var templateName = "exports-default-module";
-
-    // exports = module.exports = VALUE;
-    if (this.hasNonDefaultExports) templateName = "exports-default-module-override";
-
-    if (t.isFunctionDeclaration(declar) || !this.hasNonDefaultExports) {
-      assign = util.template(templateName, {
-        VALUE: this._pushStatement(declar, nodes)
-      }, true);
-
-      // hoist to the top if this default is a function
-      nodes.push(this._hoistExport(declar, assign, 3));
-      return;
-    } else {
-      // this export isn't a function so we can't hoist it to the top so we need to set it
-      // at the very end of the file with something like:
-      //
-      //   module.exports = _extends(exports["default"], exports)
-      //
-
-      assign = util.template("common-export-default-assign", {
-        EXTENDS_HELPER: this.file.addHelper("extends")
-      }, true);
-      assign._blockHoist = 0;
-
-      nodes.push(assign);
+    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.exportSpecifier = function (specifier, node, nodes) {
-  this._exportSpecifier(function () {
-    return t.callExpression(t.identifier("require"), [node.source]);
-  }, specifier, node, nodes);
+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.scope.generateUidIdentifier(source);
+    nodes.push(t.variableDeclaration("var", [
+      t.variableDeclarator(uid, call)
+    ]));
+    return uid;
+  } else {
+    return call;
+  }
 };

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

@@ -0,0 +1,11 @@
+module.exports = {
+  commonStandard: require("./common-standard"),
+  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

@@ -2,29 +2,34 @@
 
 module.exports = SystemFormatter;
 
-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");
+var DefaultFormatter = require("./_default");
+var AMDFormatter     = require("./amd");
+var useStrict        = require("../helpers/use-strict");
+var util             = require("../../util");
+var t                = require("../../types");
+var last             = require("lodash/array/last");
+var each             = require("lodash/collection/each");
+var map              = require("lodash/collection/map");
 
 function SystemFormatter(file) {
-  this.exportIdentifier  = file.generateUidIdentifier("export");
-  this.noInteropRequire = true;
+  this.exportIdentifier = file.scope.generateUidIdentifier("export");
+  this.noInteropRequireExport = true;
+  this.noInteropRequireImport = true;
 
-  AMDFormatter.apply(this, arguments);
+  DefaultFormatter.apply(this, arguments);
 }
 
 util.inherits(SystemFormatter, AMDFormatter);
 
+SystemFormatter.prototype.init = function () {};
+
 SystemFormatter.prototype._addImportSource = function (node, exportNode) {
   node._importSource = exportNode.source && exportNode.source.value;
   return node;
 };
 
-SystemFormatter.prototype._exportsWildcard = function (objectIdentifier, node) {
-  var leftIdentifier = this.file.generateUidIdentifier("key");
+SystemFormatter.prototype.buildExportsWildcard = function (objectIdentifier, node) {
+  var leftIdentifier = this.scope.generateUidIdentifier("key");
   var valIdentifier  = t.memberExpression(objectIdentifier, leftIdentifier, true);
 
   var left = t.variableDeclaration("var", [
@@ -40,7 +45,7 @@ SystemFormatter.prototype._exportsWildcard = function (objectIdentifier, node) {
   return this._addImportSource(t.forInStatement(left, right, block), node);
 };
 
-SystemFormatter.prototype._exportsAssign = function (id, init, node) {
+SystemFormatter.prototype.buildExportsAssignment = function (id, init, node) {
   var call = this.buildExportCall(t.literal(id.name), init, true);
   return this._addImportSource(call, node);
 };
@@ -60,42 +65,101 @@ SystemFormatter.prototype.buildExportCall = function (id, init, isStatement) {
 
 SystemFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
   AMDFormatter.prototype.importSpecifier.apply(this, arguments);
-  this._addImportSource(_.last(nodes), node);
+  this._addImportSource(last(nodes), node);
+};
+
+var runnerSettersVisitor = {
+  enter: function (node, parent, scope, 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);
+      }
+
+      this.remove();
+    }
+  }
 };
 
 SystemFormatter.prototype.buildRunnerSetters = function (block, hoistDeclarators) {
-  return t.arrayExpression(_.map(this.ids, function (uid, source) {
+  var scope = this.file.scope;
+
+  return t.arrayExpression(map(this.ids, function (uid, source) {
     var state = {
-      nodes: [],
+      source:           source,
+      nodes:            [],
       hoistDeclarators: hoistDeclarators
     };
 
-    traverse(block, {
-      enter: function (node, parent, scope, context, state) {
-        if (node._importSource === 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();
-        }
-      }
-    }, null, state);
+    scope.traverse(block, runnerSettersVisitor, state);
 
     return t.functionExpression(null, [uid], t.blockStatement(state.nodes));
   }));
 };
 
-SystemFormatter.prototype.transform = function (ast) {
-  var program = ast.program;
+var hoistVariablesVisitor = {
+  enter: function (node, parent, scope, hoistDeclarators) {
+    if (t.isFunction(node)) {
+      // nothing inside is accessible
+      return this.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, handlerBody) {
+    if (t.isFunction(node)) this.skip();
+
+    if (t.isFunctionDeclaration(node) || node._blockHoist) {
+      handlerBody.push(node);
+      this.remove();
+    }
+  }
+};
+
+SystemFormatter.prototype.transform = function (program) {
   var hoistDeclarators = [];
   var moduleName = this.getModuleName();
   var moduleNameLiteral = t.literal(moduleName);
@@ -116,46 +180,7 @@ SystemFormatter.prototype.transform = function (ast) {
   var returnStatement = handlerBody.pop();
 
   // hoist up all variable declarations
-  traverse(block, {
-    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;
-        }
-
-        var nodes = [];
-
-        _.each(node.declarations, function (declar) {
-          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;
-      }
-    }
-  }, null, hoistDeclarators);
+  this.file.scope.traverse(block, hoistVariablesVisitor, hoistDeclarators);
 
   if (hoistDeclarators.length) {
     var hoistDeclar = t.variableDeclaration("var", hoistDeclarators);
@@ -164,16 +189,7 @@ SystemFormatter.prototype.transform = function (ast) {
   }
 
   // hoist up function declarations for circular references
-  traverse(block, {
-    enter: function (node, parent, scope, context, handlerBody) {
-      if (t.isFunction(node)) context.skip();
-
-      if (t.isFunctionDeclaration(node) || node._blockHoist) {
-        handlerBody.push(node);
-        context.remove();
-      }
-    }
-  }, null, handlerBody);
+  this.file.scope.traverse(block, hoistFunctionsVisitor, handlerBody);
 
   handlerBody.push(returnStatement);
 

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

@@ -5,7 +5,7 @@ module.exports = UMDFormatter;
 var AMDFormatter = require("./amd");
 var util         = require("../../util");
 var t            = require("../../types");
-var _            = require("lodash");
+var values       = require("lodash/object/values");
 
 function UMDFormatter() {
   AMDFormatter.apply(this, arguments);
@@ -13,9 +13,8 @@ function UMDFormatter() {
 
 util.inherits(UMDFormatter, AMDFormatter);
 
-UMDFormatter.prototype.transform = function (ast) {
-  var program = ast.program;
-  var body    = program.body;
+UMDFormatter.prototype.transform = function (program) {
+  var body = program.body;
 
   // build an array of module names
 
@@ -26,7 +25,7 @@ UMDFormatter.prototype.transform = function (ast) {
 
   // factory
 
-  var ids  = _.values(this.ids);
+  var ids  = values(this.ids);
   var args = [t.identifier("exports")];
   if (this.passModuleArg) args.push(t.identifier("module"));
   args = args.concat(ids);

lib/6to5/transformation/templates/.6to5rc

@@ -0,0 +1,3 @@
+{
+  "blacklist": ["useStrict"]
+}

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

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

lib/6to5/transformation/templates/async-to-generator.js

@@ -3,35 +3,26 @@
     var gen = fn.apply(this, arguments);
 
     return new Promise(function (resolve, reject) {
-      function step(getNext) {
-        var next;
+      var callNext = step.bind(null, "next");
+      var callThrow = step.bind(null, "throw");
 
+      function step(key, arg) {
         try {
-          next = getNext();
-        } catch(e) {
-          reject(e);
+          var info = gen[key](arg);
+          var value = info.value;
+        } catch (error) {
+          reject(error);
           return;
         }
 
-        if (next.done) {
-          resolve(next.value);
-          return;
+        if (info.done) {
+          resolve(value);
+        } else {
+          Promise.resolve(value).then(callNext, callThrow);
         }
-
-        Promise.resolve(next.value).then(function (v) {
-          step(function () {
-            return gen.next(v);
-          });
-        }, function (e) {
-          step(function () {
-            return gen["throw"](e);
-          });
-        });
       }
 
-      step(function () {
-        return gen.next();
-      });
+      callNext();
     });
-  }
+  };
 })

lib/6to5/transformation/templates/class-call-check.js

@@ -0,0 +1,5 @@
+(function (instance, Constructor) {
+  if (!(instance instanceof Constructor)) {
+    throw new TypeError("Cannot call a class as a function");
+  }
+});

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

@@ -1,3 +1,3 @@
-if (Object.getPrototypeOf(CLASS_NAME) !== null) {
-  Object.getPrototypeOf(CLASS_NAME).apply(this, arguments);
+if (SUPER_NAME != null) {
+  SUPER_NAME.apply(this, arguments);
 }

lib/6to5/transformation/templates/common-export-default-assign.js

@@ -1 +0,0 @@
-module.exports = EXTENDS_HELPER(exports["default"], exports);

lib/6to5/transformation/templates/corejs-is-iterator.js

@@ -0,0 +1 @@
+CORE_ID.$for.isIterable(VALUE);

lib/6to5/transformation/templates/default-parameter.js

@@ -1 +1 @@
-var VARIABLE_NAME = ARGUMENTS[ARGUMENT_KEY] === undefined ? DEFAULT_VALUE : ARGUMENTS[ARGUMENT_KEY];
+let VARIABLE_NAME = ARGUMENTS[ARGUMENT_KEY] === undefined ? DEFAULT_VALUE : ARGUMENTS[ARGUMENT_KEY];

lib/6to5/transformation/templates/defaults.js

@@ -1,7 +1,10 @@
 (function (obj, defaults) {
-  for (var key in defaults) {
-    if (obj[key] === undefined) {
-      obj[key] = defaults[key];
+  var keys = Object.getOwnPropertyNames(defaults);
+  for (var i = 0; i < keys.length; i++) {
+    var key = keys[i];
+    var value = Object.getOwnPropertyDescriptor(defaults, key);
+    if (value && value.configurable && obj[key] === undefined) {
+      Object.defineProperty(obj, key, value);
     }
   }
   return obj;

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

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

lib/6to5/transformation/templates/exports-module-declaration.js

@@ -0,0 +1,3 @@
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});

lib/6to5/transformation/templates/extends.js

@@ -1,8 +1,10 @@
-(function (target) {
+Object.assign || (function (target) {
   for (var i = 1; i < arguments.length; i++) {
     var source = arguments[i];
     for (var key in source) {
-      target[key] = source[key];
+      if (Object.prototype.hasOwnProperty.call(source, key)) {
+        target[key] = source[key];
+      }
     }
   }
   return target;

lib/6to5/transformation/templates/for-of-loose.js

@@ -2,6 +2,7 @@ for (var LOOP_OBJECT = OBJECT,
          IS_ARRAY = Array.isArray(LOOP_OBJECT),
          INDEX = 0,
          LOOP_OBJECT = IS_ARRAY ? LOOP_OBJECT : LOOP_OBJECT[Symbol.iterator]();;) {
+  var ID;
   if (IS_ARRAY) {
     if (INDEX >= LOOP_OBJECT.length) break;
     ID = LOOP_OBJECT[INDEX++];

lib/6to5/transformation/templates/interop-require-wildcard.js

@@ -1,3 +1,3 @@
 (function (obj) {
-  return obj && obj.constructor === Object ? obj : { default: obj };
+  return obj && obj.__esModule ? obj : { default: obj };
 })

lib/6to5/transformation/templates/interop-require.js

@@ -1,3 +1,3 @@
 (function (obj) {
-  return obj && (obj["default"] || obj);
+  return obj && obj.__esModule ? obj.default : obj;
 })

lib/6to5/transformation/templates/object-destructuring-empty.js

@@ -0,0 +1,3 @@
+(function (obj) {
+  if (obj == null) throw new TypeError("Cannot destructure undefined");
+});

lib/6to5/transformation/templates/property-method-assignment-wrapper-generator.js

@@ -0,0 +1,11 @@
+(function (FUNCTION_KEY) {
+  var WRAPPER_KEY = function* FUNCTION_ID() {
+    return yield* FUNCTION_KEY.apply(this, arguments);
+  };
+
+  WRAPPER_KEY.toString = function () {
+    return FUNCTION_KEY.toString();
+  };
+
+  return WRAPPER_KEY;
+})(FUNCTION)