v4.5.2

Test full `make build` on Travis

.babelrc

@@ -1,5 +1,6 @@
 {
   "experimental": true,
   "playground": true,
-  "loose": true
+  "loose": true,
+  "blacklist": ["es6.tailCall"]
 }

.editorconfig

@@ -5,6 +5,7 @@ insert_final_newline = true
 charset = utf-8
 trim_trailing_whitespace = true
 insert_final_newline = true
+end_of_line = lf
 
 [*.{js,json}]
 indent_style = space

.gitignore

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

.gitmodules

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

.jscsrc

@@ -1,58 +0,0 @@
-{
-  "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 +0,0 @@
-lib/6to5/transformation/templates

.jshintrc

@@ -1,27 +0,0 @@
-{
-  "esnext": true,
-  "indent": 2,
-  "freeze": true,
-  "validthis": true,
-  "camelcase": true,
-  "unused": true,
-  "eqnull": true,
-  "newcap": true,
-  "supernew": true,
-  "noyield": true,
-  "evil": true,
-  "node": true,
-  "boss": true,
-  "expr": true,
-  "undef": true,
-  "maxparams": 5,
-  "maxdepth": 4,
-
-  "globals": {
-    "window": true,
-    "suite": true,
-    "set": true,
-    "before": true,
-    "bench": true
-  }
-}

.npmignore

@@ -1,7 +1,7 @@
 node_modules
 *.log
 *.cache
-lib/6to5/transformation/templates
+lib/babel/transformation/templates
 test
 benchmark
 Makefile
@@ -13,3 +13,4 @@ CHANGELOG.md
 coverage
 vendor
 packages
+src

.travis.yml

@@ -2,8 +2,8 @@ sudo: false
 language: node_js
 node_js:
   - "0.10"
-  - "0.11"
   - "0.12"
+  - "iojs"
 
 branches:
   except:

CONTRIBUTING.md

@@ -2,7 +2,7 @@
 
 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).
+[code of conduct](https://github.com/babel/babel/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
@@ -10,16 +10,58 @@ pollutes the git tree.
 
 ## Developing
 
+#### Setup
+
+```sh
+$ git clone https://github.com/babel/babel
+$ cd babel
+$ make bootstrap
+```
+
+Then you need to run:
+
+```sh
+$ make watch-core
+```
+
+This will compile babel and then sit in the background and on file modification
+recompile the necessary files.
+
+#### Running tests
+
+You can run tests via:
+
+```sh
+$ make test
+```
+
+This will usually take around two minutes as it's compiling the entire
+[test262](https://github.com/tc39/test262) test suite and validating it's AST.
+This is mostly overkill and you can limit the tests to a select few by directly
+running them with `mocha`:
+
+```sh
+$ mocha test/transformation.js
+```
+
+#### Linting
+
+Please follow the correct code style, this ensures that the code is consistent
+and increases maintainability.
+
+```sh
+$ make lint
+```
+
 #### Workflow
 
 * Fork the repository
-* Clone your fork and change directory to it (`git clone git@github.com:yourUserName/6to5.git && cd 6to5`)
+* Clone your fork and change directory to it (`git clone git@github.com:yourUserName/babel.git && cd babel`)
 * Install the project dependencies (`make bootstrap`)
 * Link your forked clone (`npm link`)
 * Develop your changes ensuring you're fetching updates from upstream often
 * Ensure the test are passing (`make test`)
-* Create new pull request explaining your proposed change or reference an issue
-  in your commit message
+* Create new pull request explaining your proposed change or reference an issue in your commit message
 
 #### Code Standards
 
@@ -43,11 +85,3 @@ pollutes the git tree.
  * **Declaration**
    * No unused variables
    * No pollution of global variables and prototypes
-
-## Testing
-
-    $ make test
-
-## Linting
-
-    $ make lint

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2014-2015 Sebastian McKenzie
+Copyright (c) 2014-2015 Sebastian McKenzie <sebmck@gmail.com>
 
 MIT License
 

Makefile

@@ -4,65 +4,60 @@ 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
+BABEL_CMD = node_modules/babel/bin/babel
 
 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 publish-runtime build-core watch-core
+.PHONY: clean test test-cov test-clean 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
+	node $(BABEL_CMD) src --out-dir lib --copy-files
 
 watch-core:
-	#node $(6TO5_CMD) src --out-dir lib --watch
+	node $(BABEL_CMD) src --out-dir lib --watch --copy-files
 
 build:
 	mkdir -p dist
+	make build-core
 
 	node tools/cache-templates
 
-	node $(BROWSERIFY_CMD) -e lib/6to5/polyfill.js >dist/polyfill.js
+	node $(BROWSERIFY_CMD) -e lib/babel/polyfill.js >dist/polyfill.js
 	node $(UGLIFY_CMD) dist/polyfill.js >dist/polyfill.min.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 $(BROWSERIFY_CMD) lib/babel/api/browser.js -s babel >dist/babel.js
+	node $(UGLIFY_CMD) dist/babel.js >dist/babel.min.js
 
-	node bin/6to5-runtime >dist/runtime.js
-	node $(UGLIFY_CMD) dist/runtime.js >dist/runtime.min.js
+	node bin/babel-external-helpers >dist/external-helpers.js
+	node $(UGLIFY_CMD) dist/external-helpers.js >dist/external-helpers.min.js
 
 	rm -rf templates.json
 
 clean:
 	rm -rf coverage templates.json test/tmp dist
 
-lint:
-	$(JSHINT_CMD) --reporter node_modules/jshint-stylish/stylish.js lib bin
-	$(JSCS_CMD) lib bin
-
 test-clean:
 	rm -rf test/tmp
 
-test: lint
+test:
 	$(MOCHA_CMD)
 	make test-clean
 
 test-simple:
 	# excludes test262
-	export SIMPLE_6TO5_TESTS=1; \
+	export SIMPLE_BABEL_TESTS=1; \
 	make test
 
 test-all:
-	# includes traceur, esnext, regenerator
-	export ALL_6TO5_TESTS=1; \
+	export ALL_BABEL_TESTS=1; \
 	make test
 
 test-cov:
 	rm -rf coverage
-	export SIMPLE_6TO5_TESTS=1; \
+	export SIMPLE_BABEL_TESTS=1; \
 	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
 
-test-travis: build-core bootstrap
+test-travis: bootstrap build
 	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
 	if test -n "$$CODECLIMATE_REPO_TOKEN"; then codeclimate < coverage/lcov.info; fi
 
@@ -71,7 +66,7 @@ test-browser:
 
 	node tools/cache-templates
 	node tools/cache-tests
-	node $(BROWSERIFY_CMD) -e test/_browser.js >dist/6to5-test.js
+	node $(BROWSERIFY_CMD) -e test/_browser.js >dist/babel-test.js
 	rm -rf templates.json tests.json
 
 	test -n "`which open`" && open test/browser.html
@@ -85,9 +80,9 @@ publish:
 	npm version $$version --message "v%s"
 
 	make build
-	cp dist/6to5.min.js browser.js
+	cp dist/babel.min.js browser.js
 	cp dist/polyfill.min.js browser-polyfill.js
-	cp dist/runtime.min.js runtime.js
+	cp dist/external-helpers.min.js external-helpers.js
 
 	node tools/cache-templates
 	test -f templates.json
@@ -99,12 +94,12 @@ publish:
 	make publish-core
 	make publish-runtime
 
-	rm -rf templates.json browser.js browser-polyfill.js runtime.js
+	rm -rf templates.json browser.js browser-polyfill.js external-helpers.js
 
 publish-runtime:
 	cd packages; \
 	node build-runtime.js; \
-	cd 6to5-runtime; \
+	cd babel-runtime; \
 	npm publish
 
 publish-core:
@@ -120,5 +115,5 @@ publish-core:
 bootstrap:
 	npm install
 	git submodule update --init
-	cd vendor/regenerator; npm install
-	cd vendor/compat-table; npm install object-assign
+	cd vendor/regenerator && npm install
+	cd vendor/compat-table && npm install object-assign

NOTES.md

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

README.md

@@ -1,12 +1,17 @@
 <p align="center">
-  <img alt="6to5" src="https://raw.githubusercontent.com/6to5/logo/master/logo.png" width="546">
+  <a href="https://babeljs.io/">
+    <img alt="babel" src="https://raw.githubusercontent.com/babel/logo/master/logo.png" width="546">
+  </a>
 </p>
 
 <p align="center">
-  <strong>6to5</strong> turns ES6+ code into vanilla ES5, so you can use next generation features <strong>today.</strong>
+  <strong>Babel</strong> is a transpiler for writing next generation JavaScript.
 </p>
 
 <p align="center">
-  For more information view the <a href="https://6to5.github.io">documentation</a>. For
-  support visit the <a href="https://gitter.im/6to5/6to5">gitter room</a>.
+  For questions and support please visit the <a href="https://gitter.im/babel/babel">gitter room</a> before creating an issue.
+</p>
+
+<p align="center">
+  For documentation and website issues please visit the <a href="https://github.com/babel/babel.github.io">babel.github.io</a> repo.
 </p>

bin/6to5-minify

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

bin/6to5-runtime

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

bin/_babel-node

@@ -1,15 +1,16 @@
 #!/usr/bin/env node
 
-var commander = require("commander");
-var Module    = require("module");
-var path      = require("path");
-var repl      = require("repl");
-var to5       = require("../lib/6to5/api/node");
-var util      = require("../lib/6to5/util");
-var vm        = require("vm");
-var _         = require("lodash");
+var pathIsAbsolute = require("path-is-absolute");
+var commander      = require("commander");
+var Module         = require("module");
+var babel          = require("../lib/babel/api/node");
+var path           = require("path");
+var repl           = require("repl");
+var util           = require("../lib/babel/util");
+var vm             = require("vm");
+var _              = require("lodash");
 
-var program = new commander.Command("6to5-node");
+var program = new commander.Command("babel-node");
 
 program.option("-e, --eval [script]", "Evaluate script");
 program.option("-p, --print [code]", "Evaluate script and print result");
@@ -28,7 +29,7 @@ program.parse(process.argv);
 
 //
 
-to5.register({
+babel.register({
   experimental: program.experimental,
   extensions:   program.extensions,
   playground:   program.playground,
@@ -41,7 +42,7 @@ to5.register({
 //
 
 var _eval = function (code, filename) {
-  code = to5.transform(code, {
+  code = babel.transform(code, {
     filename: filename,
     blacklist: ["useStrict"].concat(program.blacklist || []),
     whitelist: program.whitelist,
@@ -49,7 +50,10 @@ var _eval = function (code, filename) {
     experimental: program.experimental,
     playground: program.playground
   }).code;
-  return vm.runInThisContext(code, filename);
+
+  return vm.runInThisContext(code, {
+    filename: filename
+  });
 };
 
 if (program.eval || program.print) {
@@ -60,7 +64,7 @@ if (program.eval || program.print) {
   if (program.print) console.log(result);
 } else {
   if (program.args.length) {
-    // slice all arguments up to the first filename since they're 6to5 args that we handle
+    // slice all arguments up to the first filename since they're babel args that we handle
     var args = process.argv.slice(2);
 
     var i = 0;
@@ -85,7 +89,7 @@ if (program.eval || program.print) {
 
     // make the filename absolute
     var filename = args[0]
-    if (!util.isAbsolute(filename)) args[0] = path.join(process.cwd(), filename);
+    if (!pathIsAbsolute(filename)) args[0] = path.join(process.cwd(), filename);
 
     // add back on node and concat the sliced args
     process.argv = ["node"].concat(args);

bin/babel-external-helpers

@@ -0,0 +1,4 @@
+#!/usr/bin/env node
+
+var runtime = require("../lib/babel/build-external-helpers");
+console.log(runtime());

bin/babel-node

@@ -2,10 +2,10 @@
 
 /**
  * This tiny wrapper file checks for known node flags and appends them
- * when found, before invoking the "real" _6to5-node(1) executable.
+ * when found, before invoking the "real" _babel-node(1) executable.
  */
 
-var args  = [__dirname + "/_6to5-node"];
+var args  = [__dirname + "/_babel-node"];
 
 process.argv.slice(2).forEach(function(arg){
   var flag = arg.split("=")[0];

bin/babel/dir.js

@@ -16,7 +16,9 @@ module.exports = function (commander, filenames, opts) {
 
     var dest = path.join(commander.outDir, relative);
 
-    var data = util.compile(src, { sourceMapName: dest });
+    var data = util.compile(src, {
+      sourceFileName: path.relative(dest + "/..", src)
+    });
 
     if (commander.sourceMaps) {
       var mapLoc = dest + ".map";
@@ -41,7 +43,7 @@ module.exports = function (commander, filenames, opts) {
         var src = path.join(dirname, filename);
         if (util.canCompile(filename)) {
           write(src, filename);
-        } else {
+        } else if (commander.copyFiles) {
           outputFileSync(path.join(commander.outDir, filename), fs.readFileSync(src));
         }
       });
@@ -62,7 +64,7 @@ module.exports = function (commander, filenames, opts) {
       _.each(["add", "change"], function (type) {
         watcher.on(type, function (filename) {
           var relative = path.relative(dirname, filename) || filename;
-          write(filename, relative);
+          if (util.canCompile(filename)) write(filename, relative);
         });
       });
     });

bin/babel/file.js

@@ -1,10 +1,10 @@
-var sourceMap = require("source-map");
-var chokidar  = require("chokidar");
-var util2     = require("../../lib/6to5/util");
-var path      = require("path");
-var util      = require("./util");
-var fs        = require("fs");
-var _         = require("lodash");
+var sourceMapToComment = require("source-map-to-comment");
+var sourceMap          = require("source-map");
+var chokidar           = require("chokidar");
+var path               = require("path");
+var util               = require("./util");
+var fs                 = require("fs");
+var _                  = require("lodash");
 
 module.exports = function (commander, filenames) {
   var results = [];
@@ -42,7 +42,7 @@ module.exports = function (commander, filenames) {
     });
 
     if (commander.sourceMapsInline || (!commander.outFile && commander.sourceMaps)) {
-      code += "\n" + util2.sourceMapToComment(map);
+      code += "\n" + sourceMapToComment(map);
     }
 
     return {

bin/babel/index.js

@@ -1,8 +1,8 @@
 #!/usr/bin/env node
 
 var commander = require("commander");
-var transform = require("../../lib/6to5/transformation");
-var util      = require("../../lib/6to5/util");
+var transform = require("../../lib/babel/transformation");
+var util      = require("../../lib/babel/util");
 var fs        = require("fs");
 var each      = require("lodash/collection/each");
 var keys      = require("lodash/object/keys");
@@ -11,10 +11,11 @@ commander.option("-t, --source-maps-inline", "Append sourceMappingURL comment to
 commander.option("-s, --source-maps", "Save source map alongside the compiled code");
 commander.option("-f, --filename [filename]", "Filename to use when reading from stdin - this will be used in source-maps, errors etc [stdin]", "stdin");
 commander.option("-w, --watch", "Recompile files on changes");
-commander.option("-r, --runtime", "Replace 6to5 declarations with references to a runtime");
+commander.option("-r, --external-helpers", "Replace helpers with references to a `babelHelpers` global");
 commander.option("-e, --experimental", "Enable experimental support for proposed ES7 features");
 commander.option("-p, --playground", "Enable playground support");
 
+commander.option("-c, --compact [mode]", "When set to \"auto\" compact is `true` when the input size exceeds 100KB. (auto|true|false)", "auto");
 commander.option("-m, --modules [modules]", "Module formatter type to use [common]", "common");
 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);
@@ -26,6 +27,8 @@ commander.option("-c, --remove-comments", "Remove comments from the compiled cod
 commander.option("-M, --module-ids", "Insert module id in modules", false);
 commander.option("-R, --react-compat", "Makes the react transformer produce pre-v0.12 code");
 commander.option("--keep-module-id-extensions", "Keep extensions when generating module ids", false);
+commander.option("-a, --auxiliary-comment [comment]", "Comment text to prepend to all auxiliary code");
+commander.option("-D, --copy-files", "When compiling a directory copy over non-compilable files");
 
 commander.on("--help", function () {
   var outKeys = function (title, obj) {
@@ -99,6 +102,8 @@ if (errors.length) {
 
 exports.opts = {
   keepModuleIdExtensions: commander.keepModuleIdExtensions,
+  auxiliaryComment:       commander.auxiliaryComment,
+  externalHelpers:        commander.externalHelpers,
   sourceMapName:          commander.outFile,
   experimental:           commander.experimental,
   reactCompat:            commander.reactCompat,
@@ -109,22 +114,17 @@ exports.opts = {
   sourceMap:              commander.sourceMaps || commander.sourceMapsInline,
   optional:               commander.optional,
   comments:               !commander.removeComments,
-  runtime:                commander.runtime,
   modules:                commander.modules,
+  compact:                commander.compact,
   loose:                  commander.loose
 };
 
-setTimeout(function () {
-  // this is just a hack to give `6to5-minify` and other files including this
-  // time to modify `exports.opts`
+var fn;
 
-  var fn;
+if (commander.outDir) {
+  fn = require("./dir");
+} else {
+  fn = require("./file");
+}
 
-  if (commander.outDir) {
-    fn = require("./dir");
-  } else {
-    fn = require("./file");
-  }
-
-  fn(commander, filenames, exports.opts);
-}, 0);
+fn(commander, filenames, exports.opts);

bin/babel/util.js

@@ -1,10 +1,11 @@
-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/api/node");
-var fs      = require("fs");
-var _       = require("lodash");
+var resolveRc = require("../../lib/babel/api/register/resolve-rc");
+var readdir   = require("fs-readdir-recursive");
+var index     = require("./index");
+var babel     = require("../../lib/babel/api/node");
+var util      = require("../../lib/babel/util");
+var path      = require("path");
+var fs        = require("fs");
+var _         = require("lodash");
 
 exports.readdirFilter = function (filename) {
   return readdir(filename).filter(function (filename) {
@@ -21,12 +22,13 @@ exports.addSourceMappingUrl = function (code, loc) {
 };
 
 exports.transform = function (filename, code, opts) {
-  opts = _.extend(opts || {}, index.opts);
+  opts = _.defaults(opts || {}, index.opts);
   opts.filename = filename;
+  resolveRc(filename, opts);
 
   var result;
   try {
-    result = to5.transform(code, opts);
+    result = babel.transform(code, opts);
   } catch (e) {
     if (e instanceof SyntaxError) {
       console.error("SyntaxError:", e.message);

bin/deprecated/6to5

@@ -0,0 +1,3 @@
+#!/usr/bin/env node
+console.error("`6to5` has been renamed to `babel`");
+require("../babel");

bin/deprecated/6to5-node

@@ -0,0 +1,3 @@
+#!/usr/bin/env node
+console.error("`6to5-node` has been renamed to `babel-node`");
+require("../_babel-node");

bin/deprecated/6to5-runtime

@@ -0,0 +1,3 @@
+#!/usr/bin/env node
+console.error("`6to5-runtime` has been renamed to `babel-external-helpers`");
+require("../babel-external-helpers");

doc/index.md

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

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

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

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

@@ -1,84 +0,0 @@
-"use strict";
-
-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: {
-    Property: function (node, parent) {
-      if (parent.properties[0] === node) {
-        return 1;
-      }
-    },
-
-    SpreadProperty: function (node, parent) {
-      return exports.before.nodes.Property(node, parent);
-    },
-
-    SwitchCase: function (node, parent) {
-      if (parent.cases[0] === node) {
-        return 1;
-      }
-    },
-
-    CallExpression: function (node) {
-      if (t.isFunction(node.callee)) {
-        return 1;
-      }
-    }
-  }
-};
-
-exports.after = {
-  nodes: {
-    LogicalExpression: function (node) {
-      return t.isFunction(node.left) || t.isFunction(node.right);
-    },
-
-    AssignmentExpression: function (node) {
-      if (t.isFunction(node.right)) {
-        return 1;
-      }
-    }
-  },
-
-  list: {
-    VariableDeclaration: function (node) {
-      return map(node.declarations, "init");
-    },
-
-    ArrayExpression: function (node) {
-      return node.elements;
-    },
-
-    ObjectExpression: function (node) {
-      return node.properties;
-    }
-  }
-};
-
-each({
-  Function: 1,
-  Class: 1,
-  For: 1,
-  ArrayExpression: { after: 1 },
-  ObjectExpression: { after: 1 },
-  SwitchStatement: 1,
-  IfStatement: { before: 1 },
-  CallExpression: { after: 1 },
-  Literal: { after: 1 }
-}, function (amounts, type) {
-  if (isNumber(amounts)) {
-    amounts = { after: amounts, before: amounts };
-  }
-
-  each([type].concat(t.FLIPPED_ALIAS_KEYS[type] || []), function (type) {
-    each(amounts, function (amount, key) {
-      exports[key].nodes[type] = function () {
-        return amount;
-      };
-    });
-  });
-});

lib/6to5/helpers/clone.js

@@ -1,12 +0,0 @@
-"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

@@ -1,79 +0,0 @@
-// 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

@@ -1,38 +0,0 @@
-// 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/polyfill.js

@@ -1,9 +0,0 @@
-"use strict";
-
-if (global._6to5Polyfill) {
-  throw new Error("only one instance of 6to5/polyfill is allowed");
-}
-global._6to5Polyfill = true;
-
-require("core-js/shim");
-require("regenerator-6to5/runtime");

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

@@ -1,53 +0,0 @@
-"use strict";
-
-var util = require("../../util");
-var t    = require("../../types");
-
-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;
-
-    // check if this node is the one referenced
-    if (!t.isReferenced(node, parent)) return;
-
-    // check that we don't have a local variable declared as that removes the need
-    // for the wrapper
-    var localDeclar = scope.getBindingIdentifier(state.id);
-    if (localDeclar !== state.outerDeclar) return;
-
-    state.selfReference = true;
-    this.stop();
-  }
-};
-
-exports.property = function (node, file, scope) {
-  var key = t.toComputedKey(node, node.key);
-  if (!t.isLiteral(key)) return node; // we can't set a function id with this
-
-  var id = t.toIdentifier(key.value);
-  key = t.identifier(id);
-
-  var state = {
-    id: id,
-    selfReference: false,
-    outerDeclar: scope.getBindingIdentifier(id),
-  };
-
-  scope.traverse(node, visitor, state);
-
-  var method = node.value;
-
-  if (state.selfReference) {
-    var templateName = "property-method-assignment-wrapper";
-    if (method.generator) templateName += "-generator";
-    node.value = util.template(templateName, {
-      FUNCTION: method,
-      FUNCTION_ID: key,
-      FUNCTION_KEY: scope.generateUidIdentifier(id),
-      WRAPPER_KEY: scope.generateUidIdentifier(id + "Wrapper")
-    });
-  } else {
-    method.id = key;
-  }
-};

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

@@ -1,13 +0,0 @@
-"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/index.js

@@ -1,11 +0,0 @@
-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/templates/.6to5rc

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

lib/6to5/transformation/templates/tail-call-body.js

@@ -1,3 +0,0 @@
-{
-  FUNCTION_ID:while (true) BLOCK
-}

lib/6to5/transformation/templates/tail-call.js

@@ -1,23 +0,0 @@
-(function () {
-  function Tail(func, args, context) {
-    this.func = func;
-    this.args = args;
-    this.context = context;
-  }
-
-  Tail.prototype._isTailDescriptor = true;
-
-  var isRunning = false;
-
-  return function (func, args, context) {
-    var result = new Tail(func, args, context);
-    if (!isRunning) {
-      isRunning = true;
-      do {
-        result = result.func.apply(result.context, result.args);
-      } while (result instanceof Tail || (result && result._isTailDescriptor));
-      isRunning = false;
-    }
-    return result;
-  };
-})()

lib/6to5/transformation/transformers/deprecated.json

@@ -1,41 +0,0 @@
-{
-  "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.objectRestSpread",
-  "es7.objectSpread": "es7.objectRestSpread",
-  "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.letScoping",
-  "blockScopingTDZ": "es6.blockScopingTDZ",
-  "generators": "regenerator",
-  "protoToAssign": "spec.protoToAssign",
-  "typeofSymbol": "spec.typeofSymbol",
-  "coreAliasing": "selfContained",
-  "undefinedToVoid": "spec.undefinedToVoid",
-  "undeclaredVariableCheck": "validation.undeclaredVariableCheck",
-  "specPropertyLiterals": "es3.propertyLiterals",
-  "specMemberExpressionLiterals": "es3.memberExpressionLiterals",
-  "minification.propertyLiterals": "es3.propertyLiterals",
-  "minification.memberExpressionLiterals": "es3.memberExpressionLiterals"
-}

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

@@ -1,540 +0,0 @@
-"use strict";
-
-var traverse = require("../../../traversal");
-var object   = require("../../../helpers/object");
-var util     = require("../../../util");
-var t        = require("../../../types");
-var values   = require("lodash/object/values");
-var extend   = require("lodash/object/extend");
-
-exports.check = function (node) {
-  return t.isVariableDeclaration(node) && (node.kind === "let" || node.kind === "const");
-};
-
-var isLet = function (node, parent) {
-  if (!t.isVariableDeclaration(node)) return false;
-  if (node._let) return true;
-  if (node.kind !== "let") return false;
-
-  // https://github.com/6to5/6to5/issues/255
-  if (isLetInitable(node, parent)) {
-    for (var i = 0; i < node.declarations.length; i++) {
-      var declar = node.declarations[i];
-      declar.init = declar.init || t.identifier("undefined");
-    }
-  }
-
-  node._let = true;
-  node.kind = "var";
-  return true;
-};
-
-var isLetInitable = function (node, parent) {
-  return !t.isFor(parent) || t.isFor(parent) && parent.left !== node;
-};
-
-var isVar = function (node, parent) {
-  return t.isVariableDeclaration(node, { kind: "var" }) && !isLet(node, parent);
-};
-
-var standardizeLets = function (declars) {
-  for (var i = 0; i < declars.length; i++) {
-    delete declars[i]._let;
-  }
-};
-
-exports.VariableDeclaration = function (node, parent, scope, file) {
-  if (!isLet(node, parent)) return;
-
-  if (isLetInitable(node) && file.transformers["es6.blockScopingTDZ"].canRun()) {
-    var nodes = [node];
-
-    for (var i = 0; i < node.declarations.length; i++) {
-      var decl = node.declarations[i];
-      if (decl.init) {
-        var assign = t.assignmentExpression("=", decl.id, decl.init);
-        assign._ignoreBlockScopingTDZ = true;
-        nodes.push(t.expressionStatement(assign));
-      }
-      decl.init = file.addHelper("temporal-undefined");
-    }
-
-    node._blockHoist = 2;
-
-    return nodes;
-  }
-};
-
-exports.Loop = function (node, parent, scope, file) {
-  var init = node.left || node.init;
-  if (isLet(init, node)) {
-    t.ensureBlock(node);
-    node.body._letDeclarators = [init];
-  }
-  var blockScoping = new BlockScoping(node, node.body, parent, scope, file);
-  blockScoping.run();
-};
-
-exports.Program =
-exports.BlockStatement = function (block, parent, scope, file) {
-  if (!t.isLoop(parent)) {
-    var blockScoping = new BlockScoping(false, block, parent, scope, file);
-    blockScoping.run();
-  }
-};
-
-/**
- * Description
- *
- * @param {Boolean|Node} loopParent
- * @param {Node} block
- * @param {Node} parent
- * @param {Scope} scope
- * @param {File} file
- */
-
-function BlockScoping(loopParent, block, parent, scope, file) {
-  this.loopParent = loopParent;
-  this.parent     = parent;
-  this.scope      = scope;
-  this.block      = block;
-  this.file       = file;
-
-  this.outsideLetReferences = object();
-  this.hasLetReferences     = false;
-  this.letReferences        = block._letReferences = object();
-  this.body                 = [];
-}
-
-/**
- * Start the ball rolling.
- */
-
-BlockScoping.prototype.run = function () {
-  var block = this.block;
-  if (block._letDone) return;
-  block._letDone = true;
-
-  var needsClosure = this.getLetReferences();
-
-  // this is a block within a `Function/Program` so we can safely leave it be
-  if (t.isFunction(this.parent) || t.isProgram(this.block)) return;
-
-  // we can skip everything
-  if (!this.hasLetReferences) return;
-
-  if (needsClosure) {
-    this.needsClosure();
-  } else {
-    this.remap();
-  }
-};
-
-function replace(node, parent, scope, remaps) {
-  if (!t.isReferencedIdentifier(node, parent)) return;
-
-  var remap = remaps[node.name];
-  if (!remap) return;
-
-  var ownBinding = scope.getBindingIdentifier(node.name);
-  if (ownBinding === remap.binding) {
-    node.name = remap.uid;
-  } else {
-    // scope already has it's own binding that doesn't
-    // match the one we have a stored replacement for
-    if (this) this.skip();
-  }
-}
-
-var replaceVisitor = {
-  enter: replace
-};
-
-function traverseReplace(node, parent, scope, remaps) {
-  replace(node, parent, scope, remaps);
-  scope.traverse(node, replaceVisitor, remaps);
-}
-
-/**
- * Description
- */
-
-BlockScoping.prototype.remap = function () {
-  var hasRemaps = false;
-  var letRefs   = this.letReferences;
-  var scope     = this.scope;
-
-  // alright, so since we aren't wrapping this block in a closure
-  // we have to check if any of our let variables collide with
-  // those in upper scopes and then if they do, generate a uid
-  // for them and replace all references with it
-  var remaps = object();
-
-  for (var key in letRefs) {
-    // just an Identifier node we collected in `getLetReferences`
-    // this is the defining identifier of a declaration
-    var ref = letRefs[key];
-
-    if (scope.parentHasBinding(key) || scope.hasGlobal(key)) {
-      var uid = scope.generateUidIdentifier(ref.name).name;
-      ref.name = uid;
-
-      hasRemaps = true;
-      remaps[key] = remaps[uid] = {
-        binding: ref,
-        uid: uid
-      };
-    }
-  }
-
-  if (!hasRemaps) return;
-
-  //
-
-  var loopParent = this.loopParent;
-  if (loopParent) {
-    traverseReplace(loopParent.right, loopParent, scope, remaps);
-    traverseReplace(loopParent.test, loopParent, scope, remaps);
-    traverseReplace(loopParent.update, loopParent, scope, remaps);
-  }
-
-  scope.traverse(this.block, replaceVisitor, remaps);
-};
-
-/**
- * Description
- */
-
-BlockScoping.prototype.needsClosure = function () {
-  var block = this.block;
-
-  // if we're inside of a for loop then we search to see if there are any
-  // `break`s, `continue`s, `return`s etc
-  this.has = this.checkLoop();
-
-  // hoist var references to retain scope
-  this.hoistVarDeclarations();
-
-  // turn outsideLetReferences into an array
-  var params = values(this.outsideLetReferences);
-
-  // build the closure that we're going to wrap the block with
-  var fn = t.functionExpression(null, params, t.blockStatement(block.body));
-  fn._aliasFunction = true;
-
-  // replace the current block body with the one we're going to build
-  block.body = this.body;
-
-  // build a call and a unique id that we can assign the return value to
-  var call = t.callExpression(fn, params);
-  var ret  = this.scope.generateUidIdentifier("ret");
-
-  // handle generators
-  var hasYield = traverse.hasType(fn.body, this.scope, "YieldExpression", t.FUNCTION_TYPES);
-  if (hasYield) {
-    fn.generator = true;
-    call = t.yieldExpression(call, true);
-  }
-
-  // handlers async functions
-  var hasAsync = traverse.hasType(fn.body, this.scope, "AwaitExpression", t.FUNCTION_TYPES);
-  if (hasAsync) {
-    fn.async = true;
-    call = t.awaitExpression(call, true);
-  }
-
-  this.build(ret, call);
-};
-
-var letReferenceFunctionVisitor = {
-  enter: function (node, parent, scope, state) {
-    // not a direct reference
-    if (!t.isReferencedIdentifier(node, parent)) return;
-
-    // this scope has a variable with the same name so it couldn't belong
-    // to our let scope
-    if (scope.hasOwnBinding(node.name)) return;
-
-    // not a part of our scope
-    if (!state.letReferences[node.name]) return;
-
-    state.closurify = true;
-  }
-};
-
-var letReferenceBlockVisitor = {
-  enter: function (node, parent, scope, state) {
-    if (t.isFunction(node)) {
-      scope.traverse(node, letReferenceFunctionVisitor, state);
-      return this.skip();
-    }
-  }
-};
-
-/**
- * Description
- */
-
-BlockScoping.prototype.getLetReferences = function () {
-  var block = this.block;
-
-  var declarators = block._letDeclarators || [];
-  var declar;
-
-  //
-  for (var i = 0; i < declarators.length; i++) {
-    declar = declarators[i];
-    extend(this.outsideLetReferences, t.getBindingIdentifiers(declar));
-  }
-
-  //
-  if (block.body) {
-    for (i = 0; i < block.body.length; i++) {
-      declar = block.body[i];
-      if (isLet(declar, block)) {
-        declarators = declarators.concat(declar.declarations);
-      }
-    }
-  }
-
-  //
-  for (i = 0; i < declarators.length; i++) {
-    declar = declarators[i];
-    var keys = t.getBindingIdentifiers(declar);
-    extend(this.letReferences, keys);
-    this.hasLetReferences = true;
-  }
-
-  // no let references so we can just quit
-  if (!this.hasLetReferences) return;
-
-  // set let references to plain var references
-  standardizeLets(declarators);
-
-  var state = {
-    letReferences: this.letReferences,
-    closurify:     false
-  };
-
-  // traverse through this block, stopping on functions and checking if they
-  // contain any local let references
-  this.scope.traverse(this.block, letReferenceBlockVisitor, state);
-
-  return state.closurify;
-};
-
-var loopNodeTo = function (node) {
-  if (t.isBreakStatement(node)) {
-    return "break";
-  } else if (t.isContinueStatement(node)) {
-    return "continue";
-  }
-};
-
-var loopVisitor = {
-  enter: function (node, parent, scope, state) {
-    var replace;
-
-    if (t.isLoop(node)) {
-      state.ignoreLabeless = true;
-      scope.traverse(node, loopVisitor, state);
-      state.ignoreLabeless = false;
-    }
-
-    if (t.isFunction(node) || t.isLoop(node)) {
-      return this.skip();
-    }
-
-    var loopText = loopNodeTo(node);
-
-    if (loopText) {
-      if (node.label) {
-        // we shouldn't be transforming this because it exists somewhere inside
-        if (state.innerLabels.indexOf(node.label.name) >= 0) {
-          return;
-        }
-
-        loopText = loopText + "|" + node.label.name;
-      } else {
-        // we shouldn't be transforming these statements because
-        // they don't refer to the actual loop we're scopifying
-        if (state.ignoreLabeless) return;
-
-        // break statements mean something different in this context
-        if (t.isBreakStatement(node) && t.isSwitchCase(parent)) return;
-      }
-
-      state.hasBreakContinue = true;
-      state.map[loopText] = node;
-      replace = t.literal(loopText);
-    }
-
-    if (t.isReturnStatement(node)) {
-      state.hasReturn = true;
-      replace = t.objectExpression([
-        t.property("init", t.identifier("v"), node.argument || t.identifier("undefined"))
-      ]);
-    }
-
-    if (replace) {
-      replace = t.returnStatement(replace);
-      return t.inherits(replace, node);
-    }
-  }
-};
-
-var loopLabelVisitor = {
-  enter: function (node, parent, scope, state) {
-    if (t.isLabeledStatement(node)) {
-      state.innerLabels.push(node.label.name);
-    }
-  }
-};
-
-/**
- * If we're inside of a loop then traverse it and check if it has one of
- * the following node types `ReturnStatement`, `BreakStatement`,
- * `ContinueStatement` and replace it with a return value that we can track
- * later on.
- *
- * @returns {Object}
- */
-
-BlockScoping.prototype.checkLoop = function () {
-  var state = {
-    hasBreakContinue: false,
-    ignoreLabeless:   false,
-    innerLabels:      [],
-    hasReturn:        false,
-    isLoop:           !!this.loopParent,
-    map:              {}
-  };
-
-  this.scope.traverse(this.block, loopLabelVisitor, state);
-  this.scope.traverse(this.block, loopVisitor, state);
-
-  return state;
-};
-
-var hoistVarDeclarationsVisitor = {
-  enter: function (node, parent, scope, self) {
-    if (t.isForStatement(node)) {
-      if (isVar(node.init, node)) {
-        node.init = t.sequenceExpression(self.pushDeclar(node.init));
-      }
-    } else if (t.isFor(node)) {
-      if (isVar(node.left, node)) {
-        node.left = node.left.declarations[0].id;
-      }
-    } else if (isVar(node, parent)) {
-      return self.pushDeclar(node).map(t.expressionStatement);
-    } else if (t.isFunction(node)) {
-      return this.skip();
-    }
-  }
-};
-
-/**
- * Hoist all var declarations in this block to before it so they retain scope
- * once we wrap everything in a closure.
- */
-
-BlockScoping.prototype.hoistVarDeclarations = function () {
-  traverse(this.block, hoistVarDeclarationsVisitor, this.scope, this);
-};
-
-/**
- * Turn a `VariableDeclaration` into an array of `AssignmentExpressions` with
- * their declarations hoisted to before the closure wrapper.
- *
- * @param {Node} node VariableDeclaration
- * @returns {Array}
- */
-
-BlockScoping.prototype.pushDeclar = function (node) {
-  this.body.push(t.variableDeclaration(node.kind, node.declarations.map(function (declar) {
-    return t.variableDeclarator(declar.id);
-  })));
-
-  var replace = [];
-
-  for (var i = 0; i < node.declarations.length; i++) {
-    var declar = node.declarations[i];
-    if (!declar.init) continue;
-
-    var expr = t.assignmentExpression("=", declar.id, declar.init);
-    replace.push(t.inherits(expr, declar));
-  }
-
-  return replace;
-};
-
-/**
- * Push the closure to the body.
- *
- * @param {Node} ret Identifier
- * @param {Node} call CallExpression
- */
-
-BlockScoping.prototype.build = function (ret, call) {
-  var has = this.has;
-  if (has.hasReturn || has.hasBreakContinue) {
-    this.buildHas(ret, call);
-  } else {
-    this.body.push(t.expressionStatement(call));
-  }
-};
-
-/**
- * Description
- *
- * @param {Node} ret Identifier
- * @param {Node} call CallExpression
- */
-
-BlockScoping.prototype.buildHas = function (ret, call) {
-  var body = this.body;
-
-  body.push(t.variableDeclaration("var", [
-    t.variableDeclarator(ret, call)
-  ]));
-
-  var loopParent = this.loopParent;
-  var retCheck;
-  var has = this.has;
-  var cases = [];
-
-  if (has.hasReturn) {
-    // typeof ret === "object"
-    retCheck = util.template("let-scoping-return", {
-      RETURN: ret
-    });
-  }
-
-  if (has.hasBreakContinue) {
-    if (!loopParent) {
-      throw new Error("Has no loop parent but we're trying to reassign breaks " +
-                      "and continues, something is going wrong here.");
-    }
-
-    for (var key in has.map) {
-      cases.push(t.switchCase(t.literal(key), [has.map[key]]));
-    }
-
-    if (has.hasReturn) {
-      cases.push(t.switchCase(null, [retCheck]));
-    }
-
-    if (cases.length === 1) {
-      var single = cases[0];
-      body.push(t.ifStatement(
-        t.binaryExpression("===", ret, single.test),
-        single.consequent[0]
-      ));
-    } else {
-      body.push(t.switchStatement(ret, cases));
-    }
-  } else {
-    if (has.hasReturn) body.push(retCheck);
-  }
-};

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

@@ -1,296 +0,0 @@
-"use strict";
-
-var ReplaceSupers = require("../../helpers/replace-supers");
-var nameMethod    = require("../../helpers/name-method");
-var defineMap     = require("../../helpers/define-map");
-var messages      = require("../../../messages");
-var util          = require("../../../util");
-var t             = require("../../../types");
-
-exports.check = t.isClass;
-
-exports.ClassDeclaration = function (node, parent, scope, file) {
-  return new ClassTransformer(node, file, scope, true).run();
-};
-
-exports.ClassExpression = function (node, parent, scope, file) {
-  if (!node.id) {
-    if (t.isProperty(parent) && parent.value === node && !parent.computed && t.isIdentifier(parent.key)) {
-      // var o = { foo: class {} };
-      node.id = parent.key;
-    }
-
-    if (t.isVariableDeclarator(parent) && t.isIdentifier(parent.id)) {
-      // var foo = class {};
-      node.id = parent.id;
-    }
-  }
-
-  return new ClassTransformer(node, file, scope, false).run();
-};
-
-/**
- * Description
- *
- * @param {Node} node
- * @param {File} file
- * @param {Scope} scope
- * @param {Boolean} isStatement
- */
-
-function ClassTransformer(node, file, scope, isStatement) {
-  this.isStatement = isStatement;
-  this.scope       = scope;
-  this.node        = node;
-  this.file        = file;
-
-  this.hasInstanceMutators = false;
-  this.hasStaticMutators   = false;
-
-  this.instanceMutatorMap = {};
-  this.staticMutatorMap   = {};
-  this.hasConstructor     = false;
-  this.className          = node.id || scope.generateUidIdentifier("class");
-  this.superName          = node.superClass || t.identifier("Function");
-  this.hasSuper           = !!node.superClass;
-  this.isLoose            = file.isLoose("es6.classes");
-}
-
-/**
- * Description
- *
- * @returns {Array}
- */
-
-ClassTransformer.prototype.run = function () {
-  var superName = this.superName;
-  var className = this.className;
-  var file      = this.file;
-
-  //
-
-  var body = this.body = [];
-
-  var constructorBody = t.blockStatement([
-    t.expressionStatement(t.callExpression(file.addHelper("class-call-check"), [
-      t.thisExpression(),
-      className
-    ]))
-  ]);
-  var constructor;
-
-  if (this.node.id) {
-    constructor = t.functionDeclaration(className, [], constructorBody);
-    body.push(constructor);
-  } else {
-    constructor = t.functionExpression(null, [], constructorBody);
-    body.push(t.variableDeclaration("var", [
-      t.variableDeclarator(className, constructor)
-    ]));
-  }
-  this.constructor = constructor;
-
-  var closureParams = [];
-  var closureArgs = [];
-
-  //
-
-  if (this.hasSuper) {
-    closureArgs.push(superName);
-
-    if (!t.isIdentifier(superName)) {
-      superName = this.scope.generateUidBasedOnNode(superName, this.file);
-    }
-
-    closureParams.push(superName);
-
-    this.superName = superName;
-    body.push(t.expressionStatement(t.callExpression(file.addHelper("inherits"), [className, superName])));
-  }
-
-  this.buildBody();
-
-  t.inheritsComments(body[0], this.node);
-
-  var init;
-
-  if (body.length === 1) {
-    // only a constructor so no need for a closure container
-    init = t.toExpression(constructor);
-  } else {
-    body.push(t.returnStatement(className));
-    init = t.callExpression(
-      t.functionExpression(null, closureParams, t.blockStatement(body)),
-      closureArgs
-    );
-  }
-
-  if (this.isStatement) {
-    return t.variableDeclaration("let", [
-      t.variableDeclarator(className, init)
-    ]);
-  } else {
-    return init;
-  }
-};
-
-/**
- * Description
- */
-
-ClassTransformer.prototype.buildBody = function () {
-  var constructor = this.constructor;
-  var className   = this.className;
-  var superName   = this.superName;
-  var classBody   = this.node.body.body;
-  var body        = this.body;
-
-  for (var i = 0; i < classBody.length; i++) {
-    var node = classBody[i];
-    if (t.isMethodDefinition(node)) {
-      var replaceSupers = new ReplaceSupers({
-        methodNode: node,
-        className:  this.className,
-        superName:  this.superName,
-        isStatic:   node.static,
-        isLoose:    this.isLoose,
-        scope:      this.scope,
-        file:       this.file
-      }, true);
-      replaceSupers.replace();
-
-      if (node.key.name === "constructor") {
-        this.pushConstructor(node);
-      } else {
-        this.pushMethod(node);
-      }
-    } else if (t.isPrivateDeclaration(node)) {
-      this.closure = true;
-      body.unshift(node);
-    } else if (t.isClassProperty(node)) {
-      this.pushProperty(node);
-    }
-  }
-
-  // we have no constructor, we have a super, and the super doesn't appear to be falsy
-  if (!this.hasConstructor && this.hasSuper && !t.isFalsyExpression(superName)) {
-    var helperName = "class-super-constructor-call";
-    if (this.isLoose) helperName += "-loose";
-    constructor.body.body.push(util.template(helperName, {
-      CLASS_NAME: className,
-      SUPER_NAME: this.superName
-    }, true));
-  }
-
-  var instanceProps;
-  var staticProps;
-
-  if (this.hasInstanceMutators) {
-    instanceProps = defineMap.build(this.instanceMutatorMap);
-  }
-
-  if (this.hasStaticMutators) {
-    staticProps = defineMap.build(this.staticMutatorMap);
-  }
-
-  if (instanceProps || staticProps) {
-    staticProps = staticProps || t.literal(null);
-
-    var args = [className, staticProps];
-    if (instanceProps) args.push(instanceProps);
-
-    body.push(t.expressionStatement(
-      t.callExpression(this.file.addHelper("prototype-properties"), args)
-    ));
-  }
-};
-
-/**
- * Push a method to its respective mutatorMap.
- *
- * @param {Node} node MethodDefinition
- */
-
-ClassTransformer.prototype.pushMethod = function (node) {
-  var methodName = node.key;
-
-  var kind = node.kind;
-
-  if (kind === "") {
-    nameMethod.property(node, this.file, this.scope);
-
-    if (this.isLoose) {
-      // use assignments instead of define properties for loose classes
-
-      var className = this.className;
-      if (!node.static) className = t.memberExpression(className, t.identifier("prototype"));
-      methodName = t.memberExpression(className, methodName, node.computed);
-
-      var expr = t.expressionStatement(t.assignmentExpression("=", methodName, node.value));
-      t.inheritsComments(expr, node);
-      this.body.push(expr);
-      return;
-    }
-
-    kind = "value";
-  }
-
-  var mutatorMap = this.instanceMutatorMap;
-  if (node.static) {
-    this.hasStaticMutators = true;
-    mutatorMap = this.staticMutatorMap;
-  } else {
-    this.hasInstanceMutators = true;
-  }
-
-  defineMap.push(mutatorMap, methodName, kind, node.computed, node);
-  defineMap.push(mutatorMap, methodName, "enumerable", node.computed, false);
-};
-
-/**
- * Description
- *
- * @param {Node} node
- */
-
-ClassTransformer.prototype.pushProperty = function (node) {
-  if (!node.value) return;
-
-  var key;
-
-  if (node.static) {
-    key = t.memberExpression(this.className, node.key);
-    this.body.push(
-      t.expressionStatement(t.assignmentExpression("=", key, node.value))
-    );
-  } else {
-    key = t.memberExpression(t.thisExpression(), node.key);
-    this.constructor.body.body.unshift(
-      t.expressionStatement(t.assignmentExpression("=", key, node.value))
-    );
-  }
-};
-
-/**
- * Replace the constructor body of our class.
- *
- * @param {Node} method MethodDefinition
- */
-
-ClassTransformer.prototype.pushConstructor = function (method) {
-  if (method.kind) {
-    throw this.file.errorWithNode(method, messages.get("classesIllegalConstructorKind"));
-  }
-
-  var construct = this.constructor;
-  var fn        = method.value;
-
-  this.hasConstructor = true;
-
-  t.inherits(construct, fn);
-  t.inheritsComments(construct, method);
-
-  construct._ignoreUserWhitespace = true;
-  construct.params                = fn.params;
-  construct.body.body             = construct.body.body.concat(fn.body.body);
-};

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

@@ -1,403 +0,0 @@
-"use strict";
-
-var messages = require("../../../messages");
-var t        = require("../../../types");
-
-exports.check = t.isPattern;
-
-function DestructuringTransformer(opts) {
-  this.blockHoist = opts.blockHoist;
-  this.operator   = opts.operator;
-  this.nodes      = opts.nodes;
-  this.scope      = opts.scope;
-  this.file       = opts.file;
-  this.kind       = opts.kind;
-}
-
-DestructuringTransformer.prototype.buildVariableAssignment = function (id, init) {
-  var op = this.operator;
-  if (t.isMemberExpression(id)) op = "=";
-
-  var node;
-
-  if (op) {
-    node = t.expressionStatement(t.assignmentExpression(op, id, init));
-  } else {
-    node = t.variableDeclaration(this.kind, [
-      t.variableDeclarator(id, init)
-    ]);
-  }
-
-  node._blockHoist = this.blockHoist;
-
-  return node;
-};
-
-DestructuringTransformer.prototype.buildVariableDeclaration = function (id, init) {
-  var declar = t.variableDeclaration("var", [
-    t.variableDeclarator(id, init)
-  ]);
-  declar._blockHoist = this.blockHoist;
-  return declar;
-};
-
-DestructuringTransformer.prototype.push = function (elem, parentId) {
-  if (t.isObjectPattern(elem)) {
-    this.pushObjectPattern(elem, parentId);
-  } else if (t.isArrayPattern(elem)) {
-    this.pushArrayPattern(elem, parentId);
-  } else if (t.isAssignmentPattern(elem)) {
-    this.pushAssignmentPattern(elem, parentId);
-  } else {
-    this.nodes.push(this.buildVariableAssignment(elem, parentId));
-  }
-};
-
-DestructuringTransformer.prototype.pushAssignmentPattern = function (pattern, parentId) {
-  var tempParentId = this.scope.generateUidBasedOnNode(parentId);
-
-  var declar = t.variableDeclaration("var", [
-    t.variableDeclarator(tempParentId, parentId)
-  ]);
-  declar._blockHoist = this.blockHoist;
-  this.nodes.push(declar);
-
-  this.nodes.push(this.buildVariableAssignment(
-    pattern.left,
-    t.conditionalExpression(
-      t.binaryExpression("===", tempParentId, t.identifier("undefined")),
-      pattern.right,
-      tempParentId
-    )
-  ));
-};
-
-DestructuringTransformer.prototype.pushObjectSpread = function (pattern, parentId, prop, i) {
-  // get all the keys that appear in this object before the current spread
-  var keys = [];
-  for (var i2 = 0; i2 < pattern.properties.length; i2++) {
-    var prop2 = pattern.properties[i2];
-
-    if (i2 >= i) break;
-    if (t.isSpreadProperty(prop2)) continue;
-
-    var key = prop2.key;
-    if (t.isIdentifier(key)) {
-      key = t.literal(prop2.key.name);
-    }
-    keys.push(key);
-  }
-  keys = t.arrayExpression(keys);
-
-  var value = t.callExpression(this.file.addHelper("object-without-properties"), [parentId, keys]);
-  this.nodes.push(this.buildVariableAssignment(prop.argument, value));
-};
-
-DestructuringTransformer.prototype.pushObjectProperty = function (prop, parentId) {
-  if (t.isLiteral(prop.key)) prop.computed = true;
-
-  var pattern2   = prop.value;
-  var patternId2 = t.memberExpression(parentId, prop.key, prop.computed);
-
-  if (t.isPattern(pattern2)) {
-    this.push(pattern2, patternId2);
-  } else {
-    this.nodes.push(this.buildVariableAssignment(pattern2, patternId2));
-  }
-};
-
-DestructuringTransformer.prototype.pushObjectPattern = function (pattern, parentId) {
-  if (!pattern.properties.length) {
-    this.nodes.push(t.expressionStatement(
-      t.callExpression(this.file.addHelper("object-destructuring-empty"), [parentId])
-    ));
-  }
-
-  if (pattern.properties.length > 1 && t.isMemberExpression(parentId)) {
-    var temp = this.scope.generateUidBasedOnNode(parentId, this.file);
-    this.nodes.push(this.buildVariableDeclaration(temp, parentId));
-    parentId = temp;
-  }
-
-  for (var i = 0; i < pattern.properties.length; i++) {
-    var prop = pattern.properties[i];
-    if (t.isSpreadProperty(prop)) {
-      this.pushObjectSpread(pattern, parentId, prop, i);
-    } else {
-      this.pushObjectProperty(prop, parentId);
-    }
-  }
-};
-
-var hasRest = function (pattern) {
-  for (var i = 0; i < pattern.elements.length; i++) {
-    if (t.isRestElement(pattern.elements[i])) {
-      return true;
-    }
-  }
-  return false;
-};
-
-DestructuringTransformer.prototype.pushArrayPattern = function (pattern, parentId) {
-  if (!pattern.elements) return;
-
-  // if we have a rest then we need all the elements
-  var count = !hasRest(pattern) && pattern.elements.length;
-
-  var toArray = this.scope.toArray(parentId, count);
-
-  var _parentId = this.scope.generateUidBasedOnNode(parentId);
-  this.nodes.push(this.buildVariableDeclaration(_parentId, toArray));
-  parentId = _parentId;
-
-  this.scope.assignTypeGeneric(parentId.name, "Array");
-
-  for (var i = 0; i < pattern.elements.length; i++) {
-    var elem = pattern.elements[i];
-
-    // hole
-    if (!elem) continue;
-
-    var newPatternId;
-
-    if (t.isRestElement(elem)) {
-      newPatternId = this.scope.toArray(parentId);
-
-      if (i > 0) {
-        newPatternId = t.callExpression(t.memberExpression(newPatternId, t.identifier("slice")), [t.literal(i)]);
-      }
-
-      elem = elem.argument;
-    } else {
-      newPatternId = t.memberExpression(parentId, t.literal(i), true);
-    }
-
-    this.push(elem, newPatternId);
-  }
-};
-
-DestructuringTransformer.prototype.init = function (pattern, parentId) {
-  if (!t.isArrayExpression(parentId) && !t.isMemberExpression(parentId) && !t.isIdentifier(parentId)) {
-    var key = this.scope.generateUidBasedOnNode(parentId);
-    this.nodes.push(this.buildVariableDeclaration(key, parentId));
-    parentId = key;
-  }
-
-  this.push(pattern, parentId);
-};
-
-exports.ForInStatement =
-exports.ForOfStatement = function (node, parent, scope, file) {
-  var left = node.left;
-
-  if (t.isPattern(left)) {
-    // for ({ length: k } in { abc: 3 });
-
-    var temp = scope.generateUidIdentifier("ref");
-
-    node.left = t.variableDeclaration("var", [
-      t.variableDeclarator(temp)
-    ]);
-
-    t.ensureBlock(node);
-
-    node.body.body.unshift(t.variableDeclaration("var", [
-      t.variableDeclarator(left, temp)
-    ]));
-
-    return;
-  }
-
-  if (!t.isVariableDeclaration(left)) return;
-
-  var pattern = left.declarations[0].id;
-  if (!t.isPattern(pattern)) return;
-
-  var key = scope.generateUidIdentifier("ref");
-  node.left = t.variableDeclaration(left.kind, [
-    t.variableDeclarator(key, null)
-  ]);
-
-  var nodes = [];
-
-  var destructuring = new DestructuringTransformer({
-    kind: left.kind,
-    file: file,
-    scope: scope,
-    nodes: nodes
-  });
-
-  destructuring.init(pattern, key);
-
-  t.ensureBlock(node);
-
-  var block = node.body;
-  block.body = nodes.concat(block.body);
-};
-
-exports.Function = function (node, parent, scope, file) {
-  var nodes = [];
-
-  var hasDestructuringTransformer = false;
-
-  node.params = node.params.map(function (pattern, i) {
-    if (!t.isPattern(pattern)) return pattern;
-
-    hasDestructuringTransformer = true;
-    var parentId = scope.generateUidIdentifier("ref");
-
-    var destructuring = new DestructuringTransformer({
-      blockHoist: node.params.length - i,
-      nodes:      nodes,
-      scope:      scope,
-      file:       file,
-      kind:       "var",
-    });
-    destructuring.init(pattern, parentId);
-
-    return parentId;
-  });
-
-  if (!hasDestructuringTransformer) return;
-
-  t.ensureBlock(node);
-
-  var block = node.body;
-  block.body = nodes.concat(block.body);
-};
-
-exports.CatchClause = function (node, parent, scope, file) {
-  var pattern = node.param;
-  if (!t.isPattern(pattern)) return;
-
-  var ref = scope.generateUidIdentifier("ref");
-  node.param = ref;
-
-  var nodes = [];
-
-  var destructuring = new DestructuringTransformer({
-    kind: "let",
-    file: file,
-    scope: scope,
-    nodes: nodes
-  });
-  destructuring.init(pattern, ref);
-
-  node.body.body = nodes.concat(node.body.body);
-
-  return node;
-};
-
-exports.ExpressionStatement = function (node, parent, scope, file) {
-  var expr = node.expression;
-  if (expr.type !== "AssignmentExpression") return;
-  if (!t.isPattern(expr.left)) return;
-  if (file.isConsequenceExpressionStatement(node)) return;
-
-  var nodes = [];
-
-  var ref = scope.generateUidIdentifier("ref");
-  nodes.push(t.variableDeclaration("var", [
-    t.variableDeclarator(ref, expr.right)
-  ]));
-
-  var destructuring = new DestructuringTransformer({
-    operator: expr.operator,
-    file: file,
-    scope: scope,
-    nodes: nodes
-  });
-  destructuring.init(expr.left, ref);
-
-  return nodes;
-};
-
-exports.AssignmentExpression = function (node, parent, scope, file) {
-  if (!t.isPattern(node.left)) return;
-
-  var ref = scope.generateUidIdentifier("temp");
-  scope.push({
-    key: ref.name,
-    id: ref
-  });
-
-  var nodes = [];
-  nodes.push(t.assignmentExpression("=", ref, node.right));
-
-  var destructuring = new DestructuringTransformer({
-    operator: node.operator,
-    file: file,
-    scope: scope,
-    nodes: nodes
-  });
-  destructuring.init(node.left, ref);
-
-  nodes.push(ref);
-
-  return t.toSequenceExpression(nodes, scope);
-};
-
-var variableDeclarationhasPattern = function (node) {
-  for (var i = 0; i < node.declarations.length; i++) {
-    if (t.isPattern(node.declarations[i].id)) {
-      return true;
-    }
-  }
-  return false;
-};
-
-exports.VariableDeclaration = function (node, parent, scope, file) {
-  if (t.isForInStatement(parent) || t.isForOfStatement(parent)) return;
-  if (!variableDeclarationhasPattern(node)) return;
-
-  var nodes = [];
-  var declar;
-
-  for (var i = 0; i < node.declarations.length; i++) {
-    declar = node.declarations[i];
-
-    var patternId = declar.init;
-    var pattern   = declar.id;
-
-    var destructuring = new DestructuringTransformer({
-      nodes: nodes,
-      scope: scope,
-      kind:  node.kind,
-      file:  file
-    });
-
-    if (t.isPattern(pattern) && patternId) {
-      destructuring.init(pattern, patternId);
-
-      if (+i !== node.declarations.length - 1) {
-        // we aren't the last declarator so let's just make the
-        // last transformed node inherit from us
-        t.inherits(nodes[nodes.length - 1], declar);
-      }
-    } else {
-      nodes.push(t.inherits(destructuring.buildVariableAssignment(declar.id, declar.init), declar));
-    }
-  }
-
-  if (!t.isProgram(parent) && !t.isBlockStatement(parent)) {
-    // https://github.com/6to5/6to5/issues/113
-    // for (let [x] = [0]; false;) {}
-
-    declar = null;
-
-    for (i = 0; i < nodes.length; i++) {
-      node = nodes[i];
-      declar = declar || t.variableDeclaration(node.kind, []);
-
-      if (!t.isVariableDeclaration(node) && declar.kind !== node.kind) {
-        throw file.errorWithNode(node, messages.get("invalidParentForThisNode"));
-      }
-
-      declar.declarations = declar.declarations.concat(node.declarations);
-    }
-
-    return declar;
-  }
-
-  return nodes;
-};

lib/6to5/transformation/transformers/es6/tail-call.js

@@ -1,359 +0,0 @@
-"use strict";
-
-var reduceRight = require("lodash/collection/reduceRight");
-var messages    = require("../../../messages");
-var flatten     = require("lodash/array/flatten");
-var util        = require("../../../util");
-var map         = require("lodash/collection/map");
-var t           = require("../../../types");
-
-function returnBlock(expr) {
-  return t.blockStatement([t.returnStatement(expr)]);
-}
-
-function TailCallTransformer(node, scope, file) {
-  this.hasTailRecursion = false;
-  this.needsArguments   = false;
-  this.setsArguments    = false;
-  this.needsThis        = false;
-  this.ownerId          = node.id;
-  this.vars             = [];
-
-  this.scope = scope;
-  this.file  = file;
-  this.node  = node;
-}
-
-TailCallTransformer.prototype.getArgumentsId = function () {
-  return this.argumentsId = this.argumentsId || this.scope.generateUidIdentifier("arguments");
-};
-
-TailCallTransformer.prototype.getThisId = function () {
-  return this.thisId = this.thisId || this.scope.generateUidIdentifier("this");
-};
-
-TailCallTransformer.prototype.getLeftId = function () {
-  return this.leftId = this.leftId || this.scope.generateUidIdentifier("left");
-};
-
-TailCallTransformer.prototype.getFunctionId = function () {
-  return this.functionId = this.functionId || this.scope.generateUidIdentifier("function");
-};
-
-TailCallTransformer.prototype.getParams = function () {
-  var params = this.params;
-
-  if (!params) {
-    params = this.node.params;
-    this.paramDecls = [];
-
-    for (var i = 0; i < params.length; i++) {
-      var param = params[i];
-      if (!param._isDefaultPlaceholder) {
-        this.paramDecls.push(t.variableDeclarator(
-          param,
-          params[i] = this.scope.generateUidIdentifier("x")
-        ));
-      }
-    }
-  }
-
-  return this.params = params;
-};
-
-TailCallTransformer.prototype.hasDeopt = function () {
-  // check if the ownerId has been reassigned, if it has then it's not safe to
-  // perform optimisations
-  var ownerIdInfo = this.scope.getBindingInfo(this.ownerId.name);
-  return ownerIdInfo && ownerIdInfo.reassigned;
-};
-
-TailCallTransformer.prototype.run = function () {
-  var scope = this.scope;
-  var node  = this.node;
-
-  // only tail recursion can be optimized as for now, so we can skip anonymous
-  // functions entirely
-  var ownerId = this.ownerId;
-  if (!ownerId) return;
-
-  // traverse the function and look for tail recursion
-  scope.traverse(node, firstPass, this);
-
-  if (!this.hasTailRecursion) return;
-
-  if (this.hasDeopt()) {
-    this.file.logDeopt(node, messages.get("tailCallReassignmentDeopt"));
-    return;
-  }
-
-  //
-
-  scope.traverse(node, secondPass, this);
-
-  if (!this.needsThis || !this.needsArguments) {
-    scope.traverse(node, thirdPass, this);
-  }
-
-  var body = t.ensureBlock(node).body;
-
-  if (this.vars.length > 0) {
-    var declarations = flatten(map(this.vars, function (decl) {
-      return decl.declarations;
-    }, this));
-    var statement = reduceRight(declarations, function (expr, decl) {
-      return t.assignmentExpression("=", decl.id, expr);
-    }, t.identifier("undefined"));
-    body.unshift(t.expressionStatement(statement));
-  }
-
-  var paramDecls = this.paramDecls;
-  if (paramDecls.length > 0) {
-    body.unshift(t.variableDeclaration("var", paramDecls));
-  }
-
-  node.body = util.template("tail-call-body", {
-    THIS_ID:       this.thisId,
-    ARGUMENTS_ID:  this.argumentsId,
-    FUNCTION_ID:   this.getFunctionId(),
-    BLOCK:         node.body
-  });
-
-  var topVars = [];
-
-  if (this.needsThis) {
-    topVars.push(t.variableDeclarator(this.getThisId(), t.thisExpression()));
-  }
-
-  if (this.needsArguments || this.setsArguments) {
-    var decl = t.variableDeclarator(this.getArgumentsId());
-    if (this.needsArguments) {
-      decl.init = t.identifier("arguments");
-    }
-    topVars.push(decl);
-  }
-
-  var leftId = this.leftId;
-  if (leftId) {
-    topVars.push(t.variableDeclarator(leftId));
-  }
-
-  if (topVars.length > 0) {
-    node.body.body.unshift(t.variableDeclaration("var", topVars));
-  }
-};
-
-TailCallTransformer.prototype.subTransform = function (node) {
-  if (!node) return;
-
-  var handler = this["subTransform" + node.type];
-  if (handler) return handler.call(this, node);
-};
-
-TailCallTransformer.prototype.subTransformConditionalExpression = function (node) {
-  var callConsequent = this.subTransform(node.consequent);
-  var callAlternate = this.subTransform(node.alternate);
-  if (!callConsequent && !callAlternate) {
-    return;
-  }
-
-  // if ternary operator had tail recursion in value, convert to optimized if-statement
-  node.type = "IfStatement";
-  node.consequent = callConsequent ? t.toBlock(callConsequent) : returnBlock(node.consequent);
-
-  if (callAlternate) {
-    node.alternate = t.isIfStatement(callAlternate) ? callAlternate : t.toBlock(callAlternate);
-  } else {
-    node.alternate = returnBlock(node.alternate);
-  }
-
-  return [node];
-};
-
-TailCallTransformer.prototype.subTransformLogicalExpression = function (node) {
-  // only call in right-value of can be optimized
-  var callRight = this.subTransform(node.right);
-  if (!callRight) return;
-
-  // cache left value as it might have side-effects
-  var leftId = this.getLeftId();
-  var testExpr = t.assignmentExpression(
-    "=",
-    leftId,
-    node.left
-  );
-
-  if (node.operator === "&&") {
-    testExpr = t.unaryExpression("!", testExpr);
-  }
-
-  return [t.ifStatement(testExpr, returnBlock(leftId))].concat(callRight);
-};
-
-TailCallTransformer.prototype.subTransformSequenceExpression = function (node) {
-  var seq = node.expressions;
-
-  // only last element can be optimized
-  var lastCall = this.subTransform(seq[seq.length - 1]);
-  if (!lastCall) {
-    return;
-  }
-
-  // remove converted expression from sequence
-  // and convert to regular expression if needed
-  if (--seq.length === 1) {
-    node = seq[0];
-  }
-
-  return [t.expressionStatement(node)].concat(lastCall);
-};
-
-TailCallTransformer.prototype.subTransformCallExpression = function (node) {
-  var callee = node.callee, thisBinding, args;
-
-  if (t.isMemberExpression(callee, { computed: false }) && t.isIdentifier(callee.property)) {
-    switch (callee.property.name) {
-      case "call":
-        args = t.arrayExpression(node.arguments.slice(1));
-        break;
-
-      case "apply":
-        args = node.arguments[1] || t.identifier("undefined");
-        break;
-
-      default:
-        return;
-    }
-
-    thisBinding = node.arguments[0];
-    callee = callee.object;
-  }
-
-  // only tail recursion can be optimized as for now
-  if (!t.isIdentifier(callee) || !this.scope.bindingIdentifierEquals(callee.name, this.ownerId)) {
-    return;
-  }
-
-  this.hasTailRecursion = true;
-
-  if (this.hasDeopt()) return;
-
-  var body = [];
-
-  if (!t.isThisExpression(thisBinding)) {
-    body.push(t.expressionStatement(t.assignmentExpression(
-      "=",
-      this.getThisId(),
-      thisBinding || t.identifier("undefined")
-    )));
-  }
-
-  if (!args) {
-    args = t.arrayExpression(node.arguments);
-  }
-
-  var argumentsId = this.getArgumentsId();
-  var params = this.getParams();
-
-  body.push(t.expressionStatement(t.assignmentExpression(
-    "=",
-    argumentsId,
-    args
-  )));
-
-  var i, param;
-
-  if (t.isArrayExpression(args)) {
-    var elems = args.elements;
-    for (i = 0; i < elems.length && i < params.length; i++) {
-      param = params[i];
-      var elem = elems[i] || (elems[i] = t.identifier("undefined"));
-      if (!param._isDefaultPlaceholder) {
-        elems[i] = t.assignmentExpression("=", param, elem);
-      }
-    }
-  } else {
-    this.setsArguments = true;
-    for (i = 0; i < params.length; i++) {
-      param = params[i];
-      if (!param._isDefaultPlaceholder) {
-        body.push(t.expressionStatement(t.assignmentExpression(
-          "=",
-          param,
-          t.memberExpression(argumentsId, t.literal(i), true)
-        )));
-      }
-    }
-  }
-
-  body.push(t.continueStatement(this.getFunctionId()));
-
-  return body;
-};
-
-// looks for and replaces tail recursion calls
-var firstPass = {
-  enter: function (node, parent, scope, state) {
-    if (t.isReturnStatement(node)) {
-      this.skip();
-      return state.subTransform(node.argument);
-    } else if (t.isTryStatement(parent)) {
-      if (node === parent.block) {
-        this.skip();
-      } else if (parent.finalizer && node !== parent.finalizer) {
-        this.skip();
-      }
-    } else if (t.isFunction(node)) {
-      this.skip();
-    } else if (t.isVariableDeclaration(node)) {
-      this.skip();
-      state.vars.push(node);
-    }
-  }
-};
-
-// hoists up function declarations, replaces `this` and `arguments` and marks
-// them as needed
-var secondPass = {
-  enter: function (node, parent, scope, state) {
-    if (t.isThisExpression(node)) {
-      state.needsThis = true;
-      return state.getThisId();
-    } else if (t.isReferencedIdentifier(node, parent, { name: "arguments" })) {
-      state.needsArguments = true;
-      return state.getArgumentsId();
-    } else if (t.isFunction(node)) {
-      this.skip();
-      if (t.isFunctionDeclaration(node)) {
-        node = t.variableDeclaration("var", [
-          t.variableDeclarator(node.id, t.toExpression(node))
-        ]);
-        node._blockHoist = 2;
-        return node;
-      }
-    }
-  }
-};
-
-// optimizes recursion by removing `this` and `arguments` if they aren't used
-var thirdPass = {
-  enter: function (node, parent, scope, state) {
-    if (!t.isExpressionStatement(node)) return;
-
-    var expr = node.expression;
-    if (!t.isAssignmentExpression(expr)) return;
-
-    if (!state.needsThis && expr.left === state.getThisId()) {
-      this.remove();
-    } else if (!state.needsArguments && expr.left === state.getArgumentsId() && t.isArrayExpression(expr.right)) {
-      return map(expr.right.elements, function (elem) {
-        return t.expressionStatement(elem);
-      });
-    }
-  }
-};
-
-exports.Function = function (node, parent, scope, file) {
-  var tailCall = new TailCallTransformer(node, scope, file);
-  tailCall.run();
-};

lib/6to5/transformation/transformers/internal/block-hoist.js

@@ -1,36 +0,0 @@
-"use strict";
-
-var useStrict = require("../../helpers/use-strict");
-var groupBy   = require("lodash/collection/groupBy");
-var flatten   = require("lodash/array/flatten");
-var values    = require("lodash/object/values");
-
-// Priority:
-//
-//  - 0 We want this to be at the **very** bottom
-//  - 1 Default node position
-//  - 2 Priority over normal nodes
-//  - 3 We want this to be at the **very** top
-
-exports.BlockStatement =
-exports.Program = {
-  exit: function (node) {
-    var hasChange = false;
-    for (var i = 0; i < node.body.length; i++) {
-      var bodyNode = node.body[i];
-      if (bodyNode && bodyNode._blockHoist != null) hasChange = true;
-    }
-    if (!hasChange) return;
-
-    useStrict.wrap(node, function () {
-      var nodePriorities = groupBy(node.body, function (bodyNode) {
-        var priority = bodyNode._blockHoist;
-        if (priority == null) priority = 1;
-        if (priority === true) priority = 2;
-        return priority;
-      });
-
-      node.body = flatten(values(nodePriorities).reverse());
-    });
-  }
-};

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

@@ -1,20 +0,0 @@
-"use strict";
-
-var react = require("../../helpers/react");
-var t     = require("../../../types");
-
-require("../../helpers/build-react-transformer")(exports, {
-  pre: function (state) {
-    var tagName = state.tagName;
-    var args    = state.args;
-    if (react.isCompatTag(tagName)) {
-      args.push(t.literal(tagName));
-    } else {
-      args.push(state.tagExpr);
-    }
-  },
-
-  post: function (state) {
-    state.callee = t.memberExpression(t.identifier("React"), t.identifier("createElement"));
-  }
-});

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

@@ -1,20 +0,0 @@
-"use strict";
-
-var useStrict = require("../../helpers/use-strict");
-var t         = require("../../../types");
-
-exports.post = function (file) {
-  var program = file.ast.program;
-  if (!useStrict.has(program)) {
-    program.body.unshift(t.expressionStatement(t.literal("use strict")));
-  }
-};
-
-exports.FunctionDeclaration =
-exports.FunctionExpression = function () {
-  this.skip();
-};
-
-exports.ThisExpression = function () {
-  return t.identifier("undefined");
-};

package.json

@@ -1,20 +1,22 @@
 {
-  "name": "6to5",
+  "name": "babel",
   "description": "Turn ES6 code into readable vanilla ES5 with source maps",
-  "version": "3.6.2",
+  "version": "4.5.2",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
-  "homepage": "https://6to5.org/",
-  "repository": "6to5/6to5",
+  "homepage": "https://babeljs.io/",
+  "repository": "babel/babel",
   "preferGlobal": true,
-  "main": "lib/6to5/api/node.js",
+  "main": "lib/babel/api/node.js",
   "browser": {
-    "./lib/6to5/api/register/node.js": "./lib/6to5/api/register/browser.js"
+    "./lib/babel/api/register/node.js": "./lib/babel/api/register/browser.js"
   },
   "bin": {
-    "6to5": "./bin/6to5/index.js",
-    "6to5-minify": "./bin/6to5-minify",
-    "6to5-node": "./bin/6to5-node",
-    "6to5-runtime": "./bin/6to5-runtime"
+    "6to5": "./bin/deprecated/6to5",
+    "6to5-node": "./bin/deprecated/6to5-node",
+    "6to5-runtime": "./bin/deprecated/6to5-runtime",
+    "babel": "./bin/babel/index.js",
+    "babel-node": "./bin/babel-node",
+    "babel-external-helpers": "./bin/babel-external-helpers"
   },
   "keywords": [
     "harmony",
@@ -26,49 +28,53 @@
     "es6",
     "transpile",
     "transpiler",
-    "6to5"
+    "6to5",
+    "babel"
   ],
   "scripts": {
     "bench": "make bench",
     "test": "make test"
   },
   "dependencies": {
-    "acorn-6to5": "0.11.1-30",
+    "acorn-babel": "0.11.1-35",
     "ast-types": "~0.6.1",
-    "chalk": "^0.5.1",
-    "chokidar": "0.12.6",
-    "commander": "2.6.0",
-    "core-js": "^0.5.2",
+    "chalk": "^1.0.0",
+    "chokidar": "^0.12.6",
+    "commander": "^2.6.0",
+    "core-js": "^0.6.1",
     "debug": "^2.1.1",
-    "detect-indent": "3.0.0",
-    "estraverse": "1.9.1",
-    "esutils": "1.1.6",
-    "fs-readdir-recursive": "0.1.0",
-    "globals": "^5.1.0",
-    "js-tokenizer": "1.3.3",
-    "lodash": "3.0.0",
-    "output-file-sync": "1.1.0",
-    "private": "0.1.6",
-    "regenerator-6to5": "0.8.10-1",
-    "regexpu": "1.1.0",
-    "roadrunner": "1.0.4",
-    "source-map": "0.1.43",
-    "source-map-support": "0.2.9",
-    "supports-color": "1.2.0",
-    "useragent": "^2.1.5"
+    "detect-indent": "^3.0.0",
+    "estraverse": "^1.9.1",
+    "esutils": "^1.1.6",
+    "fs-readdir-recursive": "^0.1.0",
+    "globals": "^6.2.0",
+    "is-integer": "^1.0.4",
+    "js-tokens": "0.4.1",
+    "leven": "^1.0.1",
+    "line-numbers": "0.2.0",
+    "lodash": "^3.2.0",
+    "output-file-sync": "^1.1.0",
+    "path-is-absolute": "^1.0.0",
+    "private": "^0.1.6",
+    "regenerator-babel": "0.8.13-1",
+    "regexpu": "^1.1.1",
+    "repeating": "^1.1.2",
+    "shebang-regex": "^1.0.0",
+    "slash": "^1.0.0",
+    "source-map": "^0.1.43",
+    "source-map-support": "^0.2.9",
+    "source-map-to-comment": "^1.0.0",
+    "trim-right": "^1.0.0"
   },
   "devDependencies": {
-    "6to5": "3.6.0",
-    "browserify": "8.1.1",
-    "chai": "1.10.0",
-    "esvalid": "1.1.0",
-    "istanbul": "0.3.5",
-    "jscs": "1.10.0",
-    "jshint": "2.6.0",
-    "jshint-stylish": "1.0.0",
-    "matcha": "0.6.0",
-    "mocha": "2.1.0",
-    "rimraf": "2.2.8",
-    "uglify-js": "2.4.16"
+    "babel": "4.5.1",
+    "browserify": "^8.1.3",
+    "chai": "^2.0.0",
+    "esvalid": "^1.1.0",
+    "istanbul": "^0.3.5",
+    "matcha": "^0.6.0",
+    "mocha": "^2.1.0",
+    "rimraf": "^2.2.8",
+    "uglify-js": "^2.4.16"
   }
 }

packages/6to5-runtime/README.md

@@ -1,5 +0,0 @@
-# 6to5-runtime
-
-6to5 self-contained runtime
-
-For more information please look at [6to5](https://github.com/6to5/6to5).

packages/6to5-runtime/package.json

@@ -1,7 +0,0 @@
-{
-  "name": "6to5-runtime",
-  "description": "6to5 selfContained runtime",
-  "version": "3.6.1",
-  "repository": "6to5/6to5",
-  "author": "Sebastian McKenzie <sebmck@gmail.com>"
-}

packages/README.md

@@ -1,6 +1,6 @@
 # What is this?
 
 This is a folder containing additional packages that are built whenever
-a new version of 6to5 is released.
+a new version of babel is released.
 
-**TODO:** Move `6to5-core` into here.
+**TODO:** Move `babel-core` into here.

packages/babel-runtime/README.md

@@ -0,0 +1,5 @@
+# babel-runtime
+
+Babel self-contained runtime
+
+For more information please look at [babel](https://github.com/babel/babel).

packages/babel-runtime/package.json

@@ -0,0 +1,7 @@
+{
+  "name": "babel-runtime",
+  "description": "babel selfContained runtime",
+  "version": "4.5.1",
+  "repository": "babel/babel",
+  "author": "Sebastian McKenzie <sebmck@gmail.com>"
+}

packages/build-runtime.js

@@ -1,13 +1,14 @@
 "use strict";
 
-var buildHelpers = require("../lib/6to5/build-helpers");
-var transform    = require("../lib/6to5/transformation");
+var buildHelpers = require("../lib/babel/build-helpers");
+var transform    = require("../lib/babel/transformation");
+var util         = require("../lib/babel/util");
 var fs           = require("fs");
-var t            = require("../lib/6to5/types");
+var t            = require("../lib/babel/types");
 var _            = require("lodash");
 
 var relative = function (filename) {
-  return __dirname + "/6to5-runtime/" + filename;
+  return __dirname + "/babel-runtime/" + filename;
 };
 
 var writeFile = function (filename, content) {
@@ -16,8 +17,14 @@ var writeFile = function (filename, content) {
   fs.writeFileSync(filename, content);
 };
 
-var readFile = function (filename) {
-  return fs.readFileSync(require.resolve(filename), "utf8");
+var readFile = function (filename, defaultify) {
+  var file = fs.readFileSync(require.resolve(filename), "utf8");
+
+  if (defaultify) {
+    file += '\nmodule.exports = { "default": module.exports, __esModule: true };\n';
+  }
+
+  return file;
 };
 
 var updatePackage = function () {
@@ -37,10 +44,10 @@ var selfContainify = function (code) {
 };
 
 var buildHelpers2 = function () {
-  var body = [];
+  var body = util.template("self-contained-helpers-head");
   var tree = t.program(body);
 
-  buildHelpers(body, t.identifier("exports"));
+  buildHelpers(body, t.identifier("helpers"));
 
   return transform.fromAst(tree, null, {
     optional: ["selfContained"]
@@ -48,7 +55,7 @@ var buildHelpers2 = function () {
 };
 
 writeFile("helpers.js", buildHelpers2());
-writeFile("core-js.js", readFile("core-js/library"));
-writeFile("regenerator/index.js", readFile("regenerator-6to5/runtime-module"));
-writeFile("regenerator/runtime.js", selfContainify(readFile("regenerator-6to5/runtime")));
+writeFile("core-js.js", readFile("core-js/library", true));
+writeFile("regenerator/index.js", readFile("regenerator-babel/runtime-module", true));
+writeFile("regenerator/runtime.js", selfContainify(readFile("regenerator-babel/runtime")));
 updatePackage();

polyfill.js

@@ -1 +1 @@
-module.exports = require("./lib/6to5/polyfill");
+module.exports = require("./lib/babel/polyfill");

register.js

@@ -1 +1 @@
-module.exports = require("./lib/6to5/api/register/node");
+module.exports = require("./lib/babel/api/register/node");

src/babel/api/browser.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var transform = module.exports = require("../transformation");
 
 transform.version = require("../../../package").version;
@@ -7,14 +5,14 @@ transform.version = require("../../../package").version;
 transform.transform = transform;
 
 transform.run = function (code, opts) {
-  opts = opts || {};
+  opts ||= {};
   opts.sourceMap = "inline";
   return new Function(transform(code, opts).code)();
 };
 
 transform.load = function (url, callback, opts, hold) {
-  opts = opts || {};
-  opts.filename = opts.filename || url;
+  opts ||= {};
+  opts.filename ||= url;
 
   var xhr = global.ActiveXObject ? new global.ActiveXObject("Microsoft.XMLHTTP") : new global.XMLHttpRequest();
   xhr.open("GET", url, true);
@@ -38,7 +36,7 @@ transform.load = function (url, callback, opts, hold) {
 
 var runScripts = function () {
   var scripts = [];
-  var types   = ["text/ecmascript-6", "text/6to5", "module"];
+  var types   = ["text/ecmascript-6", "text/6to5", "text/babel", "module"];
   var index   = 0;
 
   var exec = function () {

src/babel/api/node.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var isFunction = require("lodash/lang/isFunction");
 var transform  = require("../transformation");
 var util       = require("../util");
@@ -7,7 +5,7 @@ var fs         = require("fs");
 
 exports.version = require("../../../package").version;
 
-exports.runtime = require("../build-runtime");
+exports.buildExternalHelpers = require("../build-external-helpers");
 
 exports.types = require("../types");
 
@@ -23,7 +21,7 @@ exports.polyfill = function () {
 
 exports.canCompile = util.canCompile;
 
-// do not use this - this is for use by official maintained 6to5 plugins
+// do not use this - this is for use by official maintained babel plugins
 exports._util = util;
 
 exports.transform = transform;
@@ -52,7 +50,7 @@ exports.transformFile = function (filename, opts, callback) {
 };
 
 exports.transformFileSync = function (filename, opts) {
-  opts = opts || {};
+  opts ||= {};
   opts.filename = filename;
   return transform(fs.readFileSync(filename), opts);
 };

src/babel/api/register/browser.js

@@ -0,0 +1,5 @@
+// required to safely use babel/register within a browserify codebase
+
+module.exports = function () {};
+
+require("../../polyfill");

src/babel/api/register/cache.js

@@ -1,10 +1,8 @@
-"use strict";
-
 var path = require("path");
 var os   = require("os");
 var fs   = require("fs");
 
-var FILENAME = path.join(os.tmpdir(), "6to5.json");
+var FILENAME = process.env.BABEL_CACHE_PATH || path.join(os.tmpdir(), "babel.json");
 var data = {};
 
 exports.save = function () {
@@ -12,6 +10,8 @@ exports.save = function () {
 };
 
 exports.load = function () {
+  if (process.env.BABEL_DISABLE_CACHE) return;
+
   process.on("exit", exports.save);
 
   var sigint = function () {

src/babel/api/register/node.js

@@ -1,17 +1,16 @@
-"use strict";
-
 require("../../polyfill");
 
 var sourceMapSupport = require("source-map-support");
 var registerCache    = require("./cache");
+var resolveRc        = require("./resolve-rc");
 var extend           = require("lodash/object/extend");
+var babel            = require("../node");
 var each             = require("lodash/collection/each");
 var util             = require("../../util");
-var to5              = require("../node");
 var fs               = require("fs");
 
 sourceMapSupport.install({
-  retrieveSourceMap: function (source) {
+  retrieveSourceMap(source) {
     var map = maps && maps[source];
     if (map) {
       return {
@@ -44,7 +43,10 @@ var mtime = function (filename) {
 var compile = function (filename) {
   var result;
 
-  var cacheKey = filename + ":" + JSON.stringify(transformOpts);
+  var opts = extend({}, transformOpts);
+  resolveRc(filename, opts);
+
+  var cacheKey = filename + ":" + JSON.stringify(opts);
 
   if (cache) {
     var cached = cache[cacheKey];
@@ -54,10 +56,10 @@ var compile = function (filename) {
   }
 
   if (!result) {
-    result = to5.transformFileSync(filename, extend({
+    result = babel.transformFileSync(filename, extend(opts, {
       sourceMap: true,
       ast:       false
-    }, transformOpts));
+    }));
   }
 
   if (cache) {
@@ -134,7 +136,7 @@ hookExtensions(util.canCompile.EXTENSIONS);
 
 module.exports = function (opts) {
   // normalize options
-  opts = opts || {};
+  opts ||= {};
 
   if (opts.only != null) onlyRegex = util.regexify(opts.only);
   if (opts.ignore != null) ignoreRegex = util.regexify(opts.ignore);

src/babel/api/register/resolve-rc.js

@@ -0,0 +1,48 @@
+var merge = require("lodash/object/merge");
+var path  = require("path");
+var fs    = require("fs");
+
+var cache = {};
+
+function exists(filename) {
+  var cached = cache[filename];
+  if (cached != null) return cached;
+  return cache[filename] = fs.existsSync(filename);
+}
+
+module.exports = function (loc, opts) {
+  var rel = ".babelrc";
+  opts ||= {};
+
+  function find(start, rel) {
+    var file = path.join(start, rel);
+
+    if (exists(file)) {
+      var content = fs.readFileSync(file, "utf8");
+      var json;
+
+      try {
+        json = JSON.parse(content);
+      } catch (err) {
+        err.message = file + ": " + err.message;
+        throw err;
+      }
+
+      if (json.breakConfig) return;
+      merge(opts, json, function(a, b) {
+        if (Array.isArray(a)) {
+          return a.concat(b);
+        }
+      });
+    }
+
+    var up = path.dirname(start);
+    if (up !== start) { // root
+      find(up, rel);
+    }
+  }
+
+  find(loc, rel);
+
+  return opts;
+};

src/babel/build-external-helpers.js

@@ -1,12 +1,10 @@
-"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");
+module.exports = function (whitelist) {
+  var namespace = t.identifier("babelHelpers");
 
   var body      = [];
   var container = t.functionExpression(null, [t.identifier("global")], t.blockStatement(body));
@@ -19,7 +17,7 @@ module.exports = function () {
     )
   ]));
 
-  buildHelpers(body, namespace);
+  buildHelpers(body, namespace, whitelist);
 
   return generator(tree).code;
 };

src/babel/build-helpers.js

@@ -3,9 +3,11 @@ var util = require("./util");
 var each = require("lodash/collection/each");
 var t    = require("./types");
 
-module.exports = function (body, namespace) {
+module.exports = function (body, namespace, whitelist = []) {
   each(File.helpers, function (name) {
     var key = t.identifier(t.toIdentifier(name));
+    if (whitelist.length && whitelist.indexOf(key) >= 0) return;
+
     body.push(t.expressionStatement(
       t.assignmentExpression("=", t.memberExpression(namespace, key), util.template(name))
     ));

src/babel/detection/index.js

@@ -15,7 +15,7 @@ function detect(ast) {
   };
 
   traverse(ast, {
-    enter: function (node, parent) {
+    enter(node, parent) {
       if (SYNTAX_KEYS[node.type]) {
         detectedSyntax(SYNTAX_KEYS[node.type]);
       }

src/babel/generation/buffer.js

@@ -1,11 +1,10 @@
-"use strict";
-
 module.exports = Buffer;
 
+var repeating = require("repeating");
+var trimRight = require("trim-right");
 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;
@@ -15,14 +14,14 @@ function Buffer(position, format) {
 }
 
 Buffer.prototype.get = function () {
-  return util.trimRight(this.buf);
+  return trimRight(this.buf);
 };
 
 Buffer.prototype.getIndent = function () {
   if (this.format.compact || this.format.concise) {
     return "";
   } else {
-    return util.repeat(this._indent, this.format.indent.style);
+    return repeating(this.format.indent.style, this._indent);
   }
 };
 
@@ -58,13 +57,13 @@ Buffer.prototype.keyword = function (name) {
 
 Buffer.prototype.space = function () {
   if (this.format.compact) return;
-
-  if (this.buf && !this.isLast([" ", "\n"])) {
+  if (this.buf && !this.isLast(" ") && !this.isLast("\n")) {
     this.push(" ");
   }
 };
 
 Buffer.prototype.removeLast = function (cha) {
+  if (this.format.compact) return;
   if (!this.isLast(cha)) return;
 
   this.buf = this.buf.substr(0, this.buf.length - 1);
@@ -72,19 +71,24 @@ Buffer.prototype.removeLast = function (cha) {
 };
 
 Buffer.prototype.newline = function (i, removeLast) {
-  if (this.format.compact || this.format.concise) {
+  if (this.format.compact) return;
+
+  if (this.format.concise) {
     this.space();
     return;
   }
 
-  removeLast = removeLast || false;
+  removeLast ||= false;
 
   if (isNumber(i)) {
-    if (this.endsWith("{\n")) i--;
-    if (this.endsWith(util.repeat(i, "\n"))) return;
+    i = Math.min(2, i);
 
-    while (i--) {
+    if (this.endsWith("{\n") || this.endsWith(":\n")) i--;
+    if (i <= 0) return;
+
+    while (i > 0) {
       this._newline(removeLast);
+      i--;
     }
     return;
   }
@@ -97,11 +101,13 @@ Buffer.prototype.newline = function (i, removeLast) {
 };
 
 Buffer.prototype._newline = function (removeLast) {
+  // never allow more than two lines
+  if (this.endsWith("\n\n")) return;
+
+  // remove the last newline
   if (removeLast && this.isLast("\n")) this.removeLast("\n");
 
   this.removeLast(" ");
-
-  // remove whitespace if last character was a newline
   this._removeSpacesAfterLastNewline();
   this._push("\n");
 };
@@ -109,6 +115,7 @@ 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");
   if (lastNewlineIndex === -1)
@@ -129,7 +136,7 @@ Buffer.prototype._removeSpacesAfterLastNewline = function () {
 };
 
 Buffer.prototype.push = function (str, noIndent) {
-  if (this._indent && !noIndent && str !== "\n") {
+  if (!this.format.compact && this._indent && !noIndent && str !== "\n") {
     // we have an indent level and we aren't pushing a newline
     var indent = this.getIndent();
 
@@ -137,7 +144,7 @@ Buffer.prototype.push = function (str, noIndent) {
     str = str.replace(/\n/g, "\n" + indent);
 
     // we've got a newline before us so prepend on the indentation
-    if (this.isLast("\n")) str = indent + str;
+    if (this.isLast("\n")) this._push(indent);
   }
 
   this._push(str);
@@ -149,13 +156,13 @@ Buffer.prototype._push = function (str) {
 };
 
 Buffer.prototype.endsWith = function (str) {
-  var d = this.buf.length - str.length;
-  return d >= 0 && this.buf.lastIndexOf(str) === d;
+  return this.buf.slice(-str.length) === str;
 };
 
-Buffer.prototype.isLast = function (cha, trimRight) {
+Buffer.prototype.isLast = function (cha) {
+  if (this.format.compact) return false;
+
   var buf = this.buf;
-  if (trimRight) buf = util.trimRight(buf);
   var last = buf[buf.length - 1];
 
   if (Array.isArray(cha)) {

src/babel/generation/generators/base.js

@@ -1,5 +1,3 @@
-"use strict";
-
 exports.File = function (node, print) {
   print(node.program);
 };

src/babel/generation/generators/classes.js

@@ -1,5 +1,3 @@
-"use strict";
-
 exports.ClassExpression =
 exports.ClassDeclaration = function (node, print) {
   this.push("class");

src/babel/generation/generators/comprehensions.js

@@ -1,5 +1,3 @@
-"use strict";
-
 exports.ComprehensionBlock = function (node, print) {
   this.keyword("for");
   this.push("(");

src/babel/generation/generators/expressions.js

@@ -1,8 +1,6 @@
-"use strict";
-
-var util     = require("../../util");
-var t        = require("../../types");
-var isNumber = require("lodash/lang/isNumber");
+var isInteger = require("is-integer");
+var isNumber  = require("lodash/lang/isNumber");
+var t         = require("../../types");
 
 exports.UnaryExpression = function (node, print) {
   var hasSpace = /[a-z]$/.test(node.operator);
@@ -46,11 +44,9 @@ exports.ConditionalExpression = function (node, print) {
 exports.NewExpression = function (node, print) {
   this.push("new ");
   print(node.callee);
-  if (node.arguments.length || this.format.parentheses) {
-    this.push("(");
-    print.list(node.arguments);
-    this.push(")");
-  }
+  this.push("(");
+  print.list(node.arguments);
+  this.push(")");
 };
 
 exports.SequenceExpression = function (node, print) {
@@ -146,7 +142,7 @@ exports.MemberExpression = function (node, print) {
     this.push("]");
   } else {
     // 5..toFixed(2);
-    if (t.isLiteral(obj) && util.isInteger(obj.value) && !SCIENTIFIC_NOTATION.test(obj.value.toString())) {
+    if (t.isLiteral(obj) && isInteger(obj.value) && !SCIENTIFIC_NOTATION.test(obj.value.toString())) {
       this.push(".");
     }
 

src/babel/generation/generators/flow.js

@@ -1,5 +1,3 @@
-"use strict";
-
 exports.AnyTypeAnnotation =
 exports.ArrayTypeAnnotation =
 exports.BooleanTypeAnnotation =
@@ -30,6 +28,7 @@ exports.ObjectTypeIndexer =
 exports.ObjectTypeProperty =
 exports.QualifiedTypeIdentifier =
 exports.UnionTypeAnnotation =
+exports.TypeCastExpression =
 exports.VoidTypeAnnotation = function () {
   // todo: implement these once we have a `--keep-types` option
 };

src/babel/generation/generators/jsx.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var t    = require("../../types");
 var each = require("lodash/collection/each");
 
@@ -40,16 +38,14 @@ exports.JSXExpressionContainer = function (node, print) {
 };
 
 exports.JSXElement = function (node, print) {
-  var self = this;
-
   var open = node.openingElement;
   print(open);
   if (open.selfClosing) return;
 
   this.indent();
-  each(node.children, function (child) {
+  each(node.children, (child) => {
     if (t.isLiteral(child)) {
-      self.push(child.value);
+      this.push(child.value);
     } else {
       print(child);
     }

src/babel/generation/generators/methods.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var t = require("../../types");
 
 exports._params = function (node, print) {

src/babel/generation/generators/modules.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var t    = require("../../types");
 var each = require("lodash/collection/each");
 
@@ -58,24 +56,26 @@ exports.ExportDeclaration = function (node, print) {
 };
 
 exports.ImportDeclaration = function (node, print) {
-  var self = this;
-
   this.push("import ");
 
+  if (node.isType) {
+    this.push("type ");
+  }
+
   var specfiers = node.specifiers;
   if (specfiers && specfiers.length) {
     var foundImportSpecifier = false;
 
-    each(node.specifiers, function (spec, i) {
+    each(node.specifiers, (spec, i) => {
       if (+i > 0) {
-        self.push(", ");
+        this.push(", ");
       }
 
       var isDefault = t.isSpecifierDefault(spec);
 
       if (!isDefault && spec.type !== "ImportBatchSpecifier" && !foundImportSpecifier) {
         foundImportSpecifier = true;
-        self.push("{ ");
+        this.push("{ ");
       }
 
       print(spec);

src/babel/generation/generators/playground.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var each = require("lodash/collection/each");
 
 each(["BindMemberExpression", "BindFunctionExpression"], function (type) {

src/babel/generation/generators/statements.js

@@ -1,7 +1,5 @@
-"use strict";
-
-var util = require("../../util");
-var t    = require("../../types");
+var repeating = require("repeating");
+var t         = require("../../types");
 
 exports.WithStatement = function (node, print) {
   this.keyword("with");
@@ -22,12 +20,7 @@ exports.IfStatement = function (node, print) {
 
   if (node.alternate) {
     if (this.isLast("}")) this.space();
-    this.keyword("else");
-
-    if (this.format.format && !t.isBlockStatement(node.alternate)) {
-      this.push(" ");
-    }
-
+    this.push("else ");
     print.indentOnComments(node.alternate);
   }
 };
@@ -153,7 +146,14 @@ exports.SwitchStatement = function (node, print) {
   this.push(")");
   this.space();
   this.push("{");
-  print.sequence(node.cases, { indent: true });
+
+  print.sequence(node.cases, {
+    indent: true,
+    addNewlines(leading, cas) {
+      if (!leading && node.cases[node.cases.length - 1] === cas) return -1;
+    }
+  });
+
   this.push("}");
 };
 
@@ -166,8 +166,10 @@ exports.SwitchCase = function (node, print) {
     this.push("default:");
   }
 
-  this.newline();
-  print.sequence(node.consequent, { indent: true });
+  if (node.consequent.length) {
+    this.newline();
+    print.sequence(node.consequent, { indent: true });
+  }
 };
 
 exports.DebuggerStatement = function () {
@@ -189,8 +191,8 @@ exports.VariableDeclaration = function (node, print, parent) {
   }
 
   var sep = ",";
-  if (hasInits) {
-    sep += "\n" + util.repeat(node.kind.length + 1);
+  if (!this.format.compact && hasInits) {
+    sep += "\n" + repeating(" ", node.kind.length + 1);
   } else {
     sep += " ";
   }

src/babel/generation/generators/template-literals.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var each = require("lodash/collection/each");
 
 exports.TaggedTemplateExpression = function (node, print) {
@@ -15,16 +13,15 @@ exports.TemplateLiteral = function (node, print) {
   this.push("`");
 
   var quasis = node.quasis;
-  var self   = this;
   var len    = quasis.length;
 
-  each(quasis, function (quasi, i) {
+  each(quasis, (quasi, i) => {
     print(quasi);
 
     if (i + 1 < len) {
-      self.push("${ ");
+      this.push("${ ");
       print(node.expressions[i]);
-      self.push(" }");
+      this.push(" }");
     }
   });
 

src/babel/generation/generators/types.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var each = require("lodash/collection/each");
 
 exports.Identifier = function (node) {
@@ -58,23 +56,22 @@ exports.Property = function (node, print) {
 exports.ArrayExpression =
 exports.ArrayPattern = function (node, print) {
   var elems = node.elements;
-  var self  = this;
   var len   = elems.length;
 
   this.push("[");
 
-  each(elems, function (elem, i) {
+  each(elems, (elem, i) => {
     if (!elem) {
       // If the array expression ends with a hole, that hole
       // will be ignored by the interpreter, but if it ends with
       // two (or more) holes, we need to write out two (or more)
       // commas so that the resulting code is interpreted with
       // both (all) of the holes.
-      self.push(",");
+      this.push(",");
     } else {
-      if (i > 0 && !self.format.compact) self.push(" ");
+      if (i > 0) this.push(" ");
       print(elem);
-      if (i < len - 1) self.push(",");
+      if (i < len - 1) this.push(",");
     }
   });
 

src/babel/generation/index.js

@@ -1,5 +1,3 @@
-"use strict";
-
 module.exports = function (ast, opts, code) {
   var gen = new CodeGenerator(ast, opts, code);
   return gen.generate();
@@ -9,18 +7,18 @@ module.exports.CodeGenerator = CodeGenerator;
 
 var detectIndent = require("detect-indent");
 var Whitespace   = require("./whitespace");
+var repeating    = require("repeating");
 var SourceMap    = require("./source-map");
 var Position     = require("./position");
+var messages     = require("../messages");
 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 || {};
+  opts ||= {};
 
   this.comments = ast.comments || [];
   this.tokens   = ast.tokens || [];
@@ -28,7 +26,7 @@ function CodeGenerator(ast, opts, code) {
   this.opts     = opts;
   this.ast      = ast;
 
-  this.whitespace = new Whitespace(this.tokens, this.comments);
+  this.whitespace = new Whitespace(this.tokens, this.comments, this.format);
   this.position   = new Position;
   this.map        = new SourceMap(this.position, opts, code);
   this.buffer     = new Buffer(this.position, this.format);
@@ -47,17 +45,25 @@ CodeGenerator.normalizeOptions = function (code, opts) {
     if (indent && indent !== " ") style = indent;
   }
 
-  return merge({
-    parentheses: true,
+  var format = {
     comments: opts.comments == null || opts.comments,
-    compact: false,
-    concise: false,
+    compact: opts.compact,
     indent: {
       adjustMultilineComment: true,
       style: style,
       base: 0
     }
-  }, opts.format || {});
+  };
+
+  if (format.compact === "auto") {
+    format.compact = code.length > 100000; // 100KB
+
+    if (format.compact) {
+      console.error(messages.get("codeGeneratorDeopt", opts.filename, "100KB"));
+    }
+  }
+
+  return format;
 };
 
 CodeGenerator.generators = {
@@ -97,38 +103,32 @@ CodeGenerator.prototype.generate = function () {
 };
 
 CodeGenerator.prototype.buildPrint = function (parent) {
-  var self = this;
-
-  var print = function (node, opts) {
-    return self.print(node, parent, opts);
+  var print = (node, opts) => {
+    return this.print(node, parent, opts);
   };
 
-  print.sequence = function (nodes, opts) {
-    opts = opts || {};
+  print.sequence = (nodes, opts) => {
+    opts ||= {};
     opts.statement = true;
-    return self.printJoin(print, nodes, opts);
+    return this.printJoin(print, nodes, opts);
   };
 
-  print.join = function (nodes, opts) {
-    return self.printJoin(print, nodes, opts);
+  print.join = (nodes, opts) => {
+    return this.printJoin(print, nodes, opts);
   };
 
   print.list = function (items, opts) {
-    opts = opts || {};
-
-    var sep = opts.separator || ", ";
-    if (self.format.compact) sep = ",";
-    opts.separator = sep;
-
+    opts ||= {};
+    opts.separator ||= ", ";
     print.join(items, opts);
   };
 
-  print.block = function (node) {
-    return self.printBlock(print, node);
+  print.block = (node) => {
+    return this.printBlock(print, node);
   };
 
-  print.indentOnComments = function (node) {
-    return self.printAndIndentOnComments(print, node);
+  print.indentOnComments = (node) => {
+    return this.printAndIndentOnComments(print, node);
   };
 
   return print;
@@ -146,11 +146,9 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
     this.format.concise = true;
   }
 
-  var self = this;
+  opts ||= {};
 
-  opts = opts || {};
-
-  var newline = function (leading) {
+  var newline = (leading) => {
     if (!opts.statement && !n.isUserWhitespacable(node, parent)) {
       return;
     }
@@ -160,23 +158,24 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
     if (node.start != null && !node._ignoreUserWhitespace) {
       // user node
       if (leading) {
-        lines = self.whitespace.getNewlinesBefore(node);
+        lines = this.whitespace.getNewlinesBefore(node);
       } else {
-        lines = self.whitespace.getNewlinesAfter(node);
+        lines = this.whitespace.getNewlinesAfter(node);
       }
     } else {
       // generated node
       if (!leading) lines++; // always include at least a single line after
+      if (opts.addNewlines) lines += opts.addNewlines(leading, node) || 0;
 
       var needs = n.needsWhitespaceAfter;
       if (leading) needs = n.needsWhitespaceBefore;
-      lines += needs(node, parent);
+      if (needs(node, parent)) lines++;
 
       // generated nodes can't add starting file whitespace
-      if (!self.buffer.get()) lines = 0;
+      if (!this.buffer.buf) lines = 0;
     }
 
-    self.newline(lines);
+    this.newline(lines);
   };
 
   if (this[node.type]) {
@@ -217,29 +216,29 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
 CodeGenerator.prototype.printJoin = function (print, nodes, opts) {
   if (!nodes || !nodes.length) return;
 
-  opts = opts || {};
+  opts ||= {};
 
-  var self = this;
-  var len  = nodes.length;
+  var len = nodes.length;
 
-  if (opts.indent) self.indent();
+  if (opts.indent) this.indent();
 
-  each(nodes, function (node, i) {
+  each(nodes, (node, i) => {
     print(node, {
       statement: opts.statement,
-      after: function () {
+      addNewlines: opts.addNewlines,
+      after: () => {
         if (opts.iterator) {
           opts.iterator(node, i);
         }
 
         if (opts.separator && i < len - 1) {
-          self.push(opts.separator);
+          this.push(opts.separator);
         }
       }
     });
   });
 
-  if (opts.indent) self.dedent();
+  if (opts.indent) this.dedent();
 };
 
 CodeGenerator.prototype.printAndIndentOnComments = function (print, node) {
@@ -283,14 +282,13 @@ CodeGenerator.prototype.getComments = function (key, node, parent) {
 
   var comments = [];
   var nodes    = [node];
-  var self     = this;
 
   if (t.isExpressionStatement(node)) {
     nodes.push(node.argument);
   }
 
-  each(nodes, function (node) {
-    comments = comments.concat(self._getComments(key, node));
+  each(nodes, (node) => {
+    comments = comments.concat(this._getComments(key, node));
   });
 
   return comments;
@@ -302,16 +300,15 @@ CodeGenerator.prototype._getComments = function (key, node) {
 
 CodeGenerator.prototype._printComments = function (comments) {
   if (this.format.compact) return;
+
   if (!this.format.comments) return;
   if (!comments || !comments.length) return;
 
-  var self = this;
-
-  each(comments, function (comment) {
+  each(comments, (comment) => {
     var skip = false;
 
     // find the original comment in the ast and set it as displayed
-    each(self.ast.comments, function (origComment) {
+    each(this.ast.comments, function (origComment) {
       if (origComment.start === comment.start) {
         // comment has already been output
         if (origComment._displayed) skip = true;
@@ -324,38 +321,38 @@ CodeGenerator.prototype._printComments = function (comments) {
     if (skip) return;
 
     // whitespace before
-    self.newline(self.whitespace.getNewlinesBefore(comment));
+    this.newline(this.whitespace.getNewlinesBefore(comment));
 
-    var column = self.position.column;
-    var val    = self.generateComment(comment);
+    var column = this.position.column;
+    var val    = this.generateComment(comment);
 
-    if (column && !self.isLast(["\n", " ", "[", "{"])) {
-      self._push(" ");
+    if (column && !this.isLast(["\n", " ", "[", "{"])) {
+      this._push(" ");
       column++;
     }
 
     //
 
-    if (comment.type === "Block" && self.format.indent.adjustMultilineComment) {
+    if (comment.type === "Block" && this.format.indent.adjustMultilineComment) {
       var offset = comment.loc.start.column;
       if (offset) {
         var newlineRegex = new RegExp("\\n\\s{1," + offset + "}", "g");
         val = val.replace(newlineRegex, "\n");
       }
 
-      var indent = Math.max(self.indentSize(), column);
-      val = val.replace(/\n/g, "\n" + util.repeat(indent));
+      var indent = Math.max(this.indentSize(), column);
+      val = val.replace(/\n/g, "\n" + repeating(" ", indent));
     }
 
     if (column === 0) {
-      val = self.getIndent() + val;
+      val = this.getIndent() + val;
     }
 
     //
 
-    self._push(val);
+    this._push(val);
 
     // whitespace after
-    self.newline(self.whitespace.getNewlinesAfter(comment));
+    this.newline(this.whitespace.getNewlinesAfter(comment));
   });
 };

src/babel/generation/node/index.js

@@ -1,12 +1,10 @@
-"use strict";
-
 module.exports = Node;
 
 var whitespace = require("./whitespace");
 var parens     = require("./parentheses");
-var t          = require("../../types");
 var each       = require("lodash/collection/each");
 var some       = require("lodash/collection/some");
+var t          = require("../../types");
 
 var find = function (obj, node, parent) {
   if (!obj) return;
@@ -42,14 +40,19 @@ Node.needsWhitespace = function (node, parent, type) {
     node = node.expression;
   }
 
-  var lines = find(whitespace[type].nodes, node, parent);
-  if (lines) return lines;
+  var linesInfo = find(whitespace.nodes, node, parent);
 
-  each(find(whitespace[type].list, node, parent), function (expr) {
-    lines = Node.needsWhitespace(expr, node, type);
-    if (lines) return false;
-  });
-  return lines || 0;
+  if (!linesInfo) {
+    var items = find(whitespace.list, node, parent);
+    if (items) {
+      for (var i = 0; i < items.length; i++) {
+        linesInfo = Node.needsWhitespace(items[i], node, type);
+        if (linesInfo) break;
+      }
+    }
+  }
+
+  return (linesInfo && linesInfo[type]) || 0;
 };
 
 Node.needsWhitespaceBefore = function (node, parent) {

src/babel/generation/node/parentheses.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var t    = require("../../types");
 var each = require("lodash/collection/each");
 

src/babel/generation/node/whitespace.js

@@ -0,0 +1,157 @@
+var isBoolean = require("lodash/lang/isBoolean");
+var each      = require("lodash/collection/each");
+var map       = require("lodash/collection/map");
+var t         = require("../../types");
+
+var crawl = function (node, state) {
+  state ||= {};
+
+  if (t.isMemberExpression(node)) {
+    crawl(node.object, state);
+    if (node.computed) crawl(node.property, state);
+  } else if (t.isBinary(node) || t.isAssignmentExpression(node)) {
+    crawl(node.left, state);
+    crawl(node.right, state);
+  } else if (t.isCallExpression(node)) {
+    state.hasCall = true;
+    crawl(node.callee, state);
+  } else if (t.isFunction(node)) {
+    state.hasFunction = true;
+  } else if (t.isIdentifier(node)) {
+    state.hasHelper ||= isHelper(node.callee);
+  }
+
+  return state;
+};
+
+var isHelper = function (node) {
+  if (t.isMemberExpression(node)) {
+    return isHelper(node.object) || isHelper(node.property);
+  } else if (t.isIdentifier(node)) {
+    return node.name === "require" || node.name[0] === "_";
+  } else if (t.isCallExpression(node)) {
+    return isHelper(node.callee);
+  } else if (t.isBinary(node) || t.isAssignmentExpression(node)) {
+    return (t.isIdentifier(node.left) && isHelper(node.left)) || isHelper(node.right);
+  } else {
+    return false;
+  }
+};
+
+var isType = function (node) {
+  return t.isLiteral(node) || t.isObjectExpression(node) || t.isArrayExpression(node) ||
+         t.isIdentifier(node) || t.isMemberExpression(node);
+};
+
+exports.nodes = {
+  AssignmentExpression(node) {
+    var state = crawl(node.right);
+    if ((state.hasCall && state.hasHelper) || state.hasFunction) {
+      return {
+        before: state.hasFunction,
+        after: true
+      };
+    }
+  },
+
+  SwitchCase(node, parent) {
+    return {
+      before: node.consequent.length || parent.cases[0] === node
+    };
+  },
+
+  LogicalExpression(node) {
+    if (t.isFunction(node.left) || t.isFunction(node.right)) {
+      return {
+        after: true
+      };
+    }
+  },
+
+  Literal(node) {
+    if (node.value === "use strict") {
+      return {
+        after: true
+      };
+    }
+  },
+
+  CallExpression(node) {
+    if (t.isFunction(node.callee) || isHelper(node)) {
+      return {
+        before: true,
+        after: true
+      };
+    }
+  },
+
+  VariableDeclaration(node) {
+    for (var i = 0; i < node.declarations.length; i++) {
+      var declar = node.declarations[i];
+
+      var enabled = isHelper(declar.id) && !isType(declar.init);
+      if (!enabled) {
+        var state = crawl(declar.init);
+        enabled = (isHelper(declar.init) && state.hasCall) || state.hasFunction;
+      }
+
+      if (enabled) {
+        return {
+          before: true,
+          after: true
+        };
+      }
+    }
+  },
+
+  IfStatement(node) {
+    if (t.isBlockStatement(node.consequent)) {
+      return {
+        before: true,
+        after: true
+      };
+    }
+  }
+};
+
+exports.nodes.Property =
+exports.nodes.SpreadProperty = function (node, parent) {
+  if (parent.properties[0] === node) {
+    return {
+      before: true
+    };
+  }
+};
+
+exports.list = {
+  VariableDeclaration(node) {
+    return map(node.declarations, "init");
+  },
+
+  ArrayExpression(node) {
+    return node.elements;
+  },
+
+  ObjectExpression(node) {
+    return node.properties;
+  }
+};
+
+each({
+  Function: true,
+  Class: true,
+  Loop: true,
+  LabeledStatement: true,
+  SwitchStatement: true,
+  TryStatement: true
+}, function (amounts, type) {
+  if (isBoolean(amounts)) {
+    amounts = { after: amounts, before: amounts };
+  }
+
+  each([type].concat(t.FLIPPED_ALIAS_KEYS[type] || []), function (type) {
+    exports.nodes[type] = function () {
+      return amounts;
+    };
+  });
+});

src/babel/generation/position.js

@@ -1,5 +1,3 @@
-"use strict";
-
 module.exports = Position;
 
 function Position() {

src/babel/generation/source-map.js

@@ -1,5 +1,3 @@
-"use strict";
-
 module.exports = SourceMap;
 
 var sourceMap = require("source-map");

src/babel/generation/whitespace.js

@@ -1,5 +1,3 @@
-"use strict";
-
 module.exports = Whitespace;
 
 var sortBy = require("lodash/collection/sortBy");
@@ -13,11 +11,13 @@ var sortBy = require("lodash/collection/sortBy");
  * @param {Number} max Array length
  * @returns {Number} shiftedIndex
  */
+
 function getLookupIndex(i, base, max) {
   i += base;
 
-  if (i >= max)
+  if (i >= max) {
     i -= max;
+  }
 
   return i;
 }
@@ -82,7 +82,7 @@ Whitespace.prototype.getNewlinesAfter = function (node) {
     }
   }
 
-  if (endToken.type.type === "eof") {
+  if (endToken && endToken.type.type === "eof") {
     return 1;
   } else {
     var lines = this.getNewlinesBetween(startToken, endToken);
@@ -96,6 +96,8 @@ Whitespace.prototype.getNewlinesAfter = function (node) {
 };
 
 Whitespace.prototype.getNewlinesBetween = function (startToken, endToken) {
+  if (!endToken || !endToken.loc) return 0;
+
   var start = startToken ? startToken.loc.end.line : 1;
   var end   = endToken.loc.start.line;
   var lines = 0;

src/babel/helpers/code-frame.js

@@ -0,0 +1,91 @@
+var lineNumbers = require("line-numbers");
+var repeating   = require("repeating");
+var jsTokens    = require("js-tokens");
+var esutils     = require("esutils");
+var chalk       = require("chalk");
+var ary         = require("lodash/function/ary");
+
+var defs = {
+  string:      chalk.red,
+  punctuation: chalk.white.bold,
+  operator:    chalk.white.bold,
+  curly:       chalk.green,
+  parens:      chalk.blue.bold,
+  square:      chalk.yellow,
+  name:        chalk.white,
+  keyword:     chalk.cyan,
+  number:      chalk.magenta,
+  regex:       chalk.magenta,
+  comment:     chalk.grey,
+  invalid:     chalk.inverse
+};
+
+var newline = /\r\n|[\n\r\u2028\u2029]/;
+
+var highlight = function (text) {
+  var tokenType = function (match) {
+    var token = jsTokens.matchToToken(match);
+    if (token.type === "name" && esutils.keyword.isKeywordES6(token.value)) {
+      return "keyword";
+    }
+
+    if (token.type === "punctuation") {
+      switch (token.value) {
+        case "{":
+        case "}":
+          return "curly";
+        case "(":
+        case ")":
+          return "parens";
+        case "[":
+        case "]":
+          return "square";
+      }
+    }
+
+    return token.type;
+  };
+
+  return text.replace(jsTokens, function (match) {
+    var type = tokenType(arguments);
+    if (type in defs) {
+      var colorize = ary(defs[type], 1);
+      return match.split(newline).map(colorize).join("\n");
+    }
+    return match;
+  });
+};
+
+module.exports = function (lines, lineNumber, colNumber) {
+  colNumber = Math.max(colNumber, 0);
+
+  if (chalk.supportsColor) {
+    lines = highlight(lines);
+  }
+
+  lines = lines.split(newline);
+
+  var start = Math.max(lineNumber - 3, 0);
+  var end   = Math.min(lines.length, lineNumber + 3);
+
+  if (!lineNumber && !colNumber) {
+    start = 0;
+    end = lines.length;
+  }
+
+  return "\n" + lineNumbers(lines.slice(start, end), {
+    start: start + 1,
+    before: "  ",
+    after: " | ",
+    transform(params) {
+      if (params.number !== lineNumber) {
+        return;
+      }
+      if (colNumber) {
+        params.line += "\n" + params.before + repeating(" ", params.width) +
+                       params.after + repeating(" ", colNumber - 1) + "^";
+      }
+      params.before = params.before.replace(/^./, ">");
+    }
+  }).join("\n");
+};

src/babel/helpers/object.js

@@ -1,5 +1,3 @@
-"use strict";
-
 module.exports = function () {
   return Object.create(null);
 };

src/babel/helpers/parse.js

@@ -1,7 +1,7 @@
 var normalizeAst = require("./normalize-ast");
 var estraverse   = require("estraverse");
 var codeFrame    = require("./code-frame");
-var acorn        = require("acorn-6to5");
+var acorn        = require("acorn-babel");
 
 module.exports = function (opts, code, callback) {
   try {
@@ -30,8 +30,8 @@ module.exports = function (opts, code, callback) {
       return ast;
     }
   } catch (err) {
-    if (!err._6to5) {
-      err._6to5 = true;
+    if (!err._babel) {
+      err._babel = true;
       var message = opts.filename + ": " + err.message;
 
       var loc = err.loc;

src/babel/helpers/to-fast-properties.js

@@ -1,5 +1,3 @@
-"use strict";
-
 /**
  * A trick from Bluebird to force V8 to use fast properties for an object.
  * Read more: http://stackoverflow.com/questions/24987896/

src/babel/messages.js

@@ -9,13 +9,16 @@ exports.messages = {
   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",
+  settersInvalidParamLength: "Setters must have exactly 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"
+  unknownForHead: "Unknown node type $1 in ForStatement",
+  didYouMean: "Did you mean $1?",
+  evalInStrictMode: "eval is not allowed in strict mode",
+  codeGeneratorDeopt: "Note: The code generator has deoptimised the styling of $1 as it exceeds the max of $2."
 };
 
 exports.get = function (key) {

src/babel/patch.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var extend = require("lodash/object/extend");
 var t      = require("./types");
 
@@ -8,7 +6,7 @@ var t      = require("./types");
 var estraverse = require("estraverse");
 extend(estraverse.VisitorKeys, t.VISITOR_KEYS);
 
-// regenerator-6to5/ast-types
+// regenerator-babel/ast-types
 
 var types = require("ast-types");
 var def   = types.Type.def;

src/babel/polyfill.js

@@ -0,0 +1,7 @@
+if (global._babelPolyfill) {
+  throw new Error("only one instance of babel/polyfill is allowed");
+}
+global._babelPolyfill = true;
+
+require("core-js/shim");
+require("regenerator-babel/runtime");

src/babel/transformation/file.js

@@ -1,33 +1,34 @@
-"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");
+var sourceMapToComment = require("source-map-to-comment");
+var shebangRegex       = require("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 assign             = require("lodash/object/assign");
+var parse              = require("../helpers/parse");
+var Scope              = require("../traversal/scope");
+var slash              = require("slash");
+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.dynamicImportedNoDefault = [];
+  this.dynamicImportIds         = {};
+  this.dynamicImported          = [];
+  this.dynamicImports           = [];
 
-  this.dynamicData      = {};
-  this.data             = {};
+  this.usedHelpers = {};
+  this.dynamicData = {};
+  this.data        = {};
 
-  this.lastStatements   = [];
-  this.opts             = this.normalizeOptions(opts);
-  this.ast              = {};
+  this.lastStatements = [];
+  this.opts           = this.normalizeOptions(opts);
+  this.ast            = {};
 
   this.buildTransformers();
 }
@@ -58,7 +59,7 @@ File.helpers = [
   "object-destructuring-empty",
   "temporal-undefined",
   "temporal-assert-defined",
-  "tail-call"
+  "self-global"
 ];
 
 File.validOptions = [
@@ -80,11 +81,18 @@ File.validOptions = [
   "keepModuleIdExtensions",
   "code",
   "ast",
-  "format",
   "playground",
   "experimental",
+  "externalHelpers",
+  "auxiliaryComment",
+  "compact",
+  "returnUsedHelpers",
+
   "resolveModuleSource",
-  "runtime",
+  "moduleId",
+
+  // legacy
+  "format",
 
   // these are used by plugins
   "ignore",
@@ -94,7 +102,7 @@ File.validOptions = [
 ];
 
 File.prototype.normalizeOptions = function (opts) {
-  opts = clone(opts);
+  opts = assign({}, opts);
 
   for (var key in opts) {
     if (key[0] !== "_" && File.validOptions.indexOf(key) < 0) {
@@ -105,10 +113,12 @@ File.prototype.normalizeOptions = function (opts) {
   defaults(opts, {
     keepModuleIdExtensions: false,
     resolveModuleSource:    null,
+    returnUsedHelpers:      false,
+    externalHelpers:        false,
+    auxilaryComment:        "",
     experimental:           false,
     reactCompat:            false,
     playground:             false,
-    whitespace:             true,
     moduleIds:              false,
     blacklist:              [],
     whitelist:              [],
@@ -117,16 +127,20 @@ File.prototype.normalizeOptions = function (opts) {
     comments:               true,
     filename:               "unknown",
     modules:                "common",
-    runtime:                false,
+    compact:                "auto",
     loose:                  [],
     code:                   true,
     ast:                    true
   });
 
   // normalize windows path separators to unix
-  opts.filename = util.normalisePathSeparator(opts.filename);
+  opts.filename = slash(opts.filename);
   if (opts.sourceRoot) {
-    opts.sourceRoot = util.normalisePathSeparator(opts.sourceRoot);
+    opts.sourceRoot = slash(opts.sourceRoot);
+  }
+
+  if (opts.moduleId) {
+    opts.moduleIds = true;
   }
 
   opts.basename = path.basename(opts.filename, path.extname(opts.filename));
@@ -134,6 +148,7 @@ File.prototype.normalizeOptions = function (opts) {
   opts.blacklist = util.arrayify(opts.blacklist);
   opts.whitelist = util.arrayify(opts.whitelist);
   opts.optional  = util.arrayify(opts.optional);
+  opts.compact   = util.booleanify(opts.compact);
   opts.loose     = util.arrayify(opts.loose);
 
   if (includes(opts.loose, "all") || includes(opts.loose, true)) {
@@ -161,8 +176,8 @@ File.prototype.normalizeOptions = function (opts) {
     opts.experimental = true;
   }
 
-  if (opts.runtime) {
-    this.set("runtimeIdentifier", t.identifier("to5Runtime"));
+  if (opts.externalHelpers) {
+    this.set("helpersNamespace", t.identifier("babelHelpers"));
   }
 
   opts.blacklist = transform._ensureTransformerNames("blacklist", opts.blacklist);
@@ -172,8 +187,7 @@ File.prototype.normalizeOptions = function (opts) {
 
   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");
+    console.error("The reactCompat option has been moved into the optional transformer `reactCompat`");
   }
 
   var ensureEnabled = function (key) {
@@ -242,12 +256,13 @@ File.prototype.getModuleFormatter = function (type) {
 };
 
 File.prototype.parseShebang = function (code) {
-  var shebangMatch = code.match(SHEBANG_REGEX);
+  var shebangMatch = shebangRegex.exec(code);
+
   if (shebangMatch) {
     this.shebang = shebangMatch[0];
 
     // remove shebang
-    code = code.replace(SHEBANG_REGEX, "");
+    code = code.replace(shebangRegex, "");
   }
 
   return code;
@@ -273,8 +288,8 @@ File.prototype.get = function (key) {
   }
 };
 
-File.prototype.addImport = function (source, name) {
-  name = name || source;
+File.prototype.addImport = function (source, name, noDefault) {
+  name ||= source;
   var id = this.dynamicImportIds[name];
 
   if (!id) {
@@ -283,7 +298,9 @@ File.prototype.addImport = function (source, name) {
     var specifiers = [t.importSpecifier(t.identifier("default"), id)];
     var declar = t.importDeclaration(specifiers, t.literal(source));
     declar._blockHoist = 3;
+
     this.dynamicImported.push(declar);
+    if (noDefault) this.dynamicImportedNoDefault.push(declar);
 
     this.moduleFormatter.importSpecifier(specifiers[0], declar, this.dynamicImports);
   }
@@ -295,6 +312,18 @@ File.prototype.isConsequenceExpressionStatement = function (node) {
   return t.isExpressionStatement(node) && this.lastStatements.indexOf(node) >= 0;
 };
 
+File.prototype.attachAuxiliaryComment = function (node) {
+  var comment = this.opts.auxiliaryComment;
+  if (comment) {
+    node.leadingComments ||= [];
+    node.leadingComments.push({
+      type: "Line",
+      value: " " + comment
+    });
+  }
+  return node;
+};
+
 File.prototype.addHelper = function (name) {
   if (!includes(File.helpers, name)) {
     throw new ReferenceError("Unknown helper " + name);
@@ -305,7 +334,9 @@ File.prototype.addHelper = function (name) {
   var declar = program._declarations && program._declarations[name];
   if (declar) return declar.id;
 
-  var runtime = this.get("runtimeIdentifier");
+  this.usedHelpers[name] = true;
+
+  var runtime = this.get("helpersNamespace");
   if (runtime) {
     name = t.identifier(t.toIdentifier(name));
     return t.memberExpression(runtime, name);
@@ -327,7 +358,7 @@ File.prototype.logDeopt = function () {
 };
 
 File.prototype.errorWithNode = function (node, msg, Error) {
-  Error = Error || SyntaxError;
+  Error ||= SyntaxError;
 
   var loc = node.loc.start;
   var err = new Error("Line " + loc.line + ": " + msg);
@@ -342,18 +373,16 @@ File.prototype.addCode = function (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();
+  opts.strictMode = this.transformers.useStrict.canRun();
 
-  return parse(opts, code, function (tree) {
-    self.transform(tree);
-    return self.generate();
+  return parse(opts, code, (tree) => {
+    this.transform(tree);
+    return this.generate();
   });
 };
 
@@ -391,7 +420,7 @@ File.prototype.call = function (key) {
 };
 
 var checkTransformerVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     checkNode(state.stack, node, scope);
   }
 };
@@ -405,7 +434,7 @@ var checkNode = function (stack, node, scope) {
 
 File.prototype.checkNode = function (node, scope) {
   var stack = this.transformerStack;
-  scope = scope || this.scope;
+  scope ||= this.scope;
 
   checkNode(stack, node, scope);
 
@@ -424,6 +453,10 @@ File.prototype.generate = function () {
     ast: null
   };
 
+  if (this.opts.returnUsedHelpers) {
+    result.usedHelpers = Object.keys(this.usedHelpers);
+  }
+
   if (opts.ast) result.ast = ast;
   if (!opts.code) return result;
 
@@ -437,7 +470,7 @@ File.prototype.generate = function () {
   }
 
   if (opts.sourceMap === "inline") {
-    result.code += "\n" + util.sourceMapToComment(result.map);
+    result.code += "\n" + sourceMapToComment(result.map);
     result.map = null;
   }
 

src/babel/transformation/helpers/build-binary-assignment-operator-transformer.js

@@ -1,5 +1,3 @@
-"use strict";
-
 var explode = require("./explode-assignable-expression");
 var t       = require("../../types");