v3.3.11

Concatenate adjacent string literals in JSX

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "vendor/test262"]
 	path = vendor/test262
 	url = https://github.com/tc39/test262
+[submodule "vendor/compat-table"]
+	path = vendor/compat-table
+	url = https://github.com/kangax/compat-table

.istanbul.yml

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

.jscsrc

@@ -14,7 +14,6 @@
   },
   "disallowSpacesInsideArrayBrackets": true,
   "disallowSpacesInsideParentheses": true,
-  "disallowQuotedKeysInObjects": true,
   "disallowSpaceAfterObjectKeys": true,
   "disallowSpaceAfterPrefixUnaryOperators": true,
   "disallowSpaceBeforePostfixUnaryOperators": true,
@@ -33,10 +32,8 @@
   "requireCommaBeforeLineBreak": true,
   "requireSpaceBeforeBinaryOperators": true,
   "requireSpaceAfterBinaryOperators": true,
-  "requireCamelCaseOrUpperCaseIdentifiers": true,
   "requireLineFeedAtFileEnd": true,
   "requireCapitalizedConstructors": true,
-  "requireDotNotation": true,
   "requireSpacesInForStatement": true,
   "requireCurlyBraces": [
     "do"
@@ -52,7 +49,8 @@
     "return",
     "try",
     "catch",
-    "typeof"
+    "typeof",
+    "function"
   ],
   "validateLineBreaks": "LF",
   "validateQuoteMarks": "\"",

CHANGELOG.md

@@ -11,6 +11,166 @@
 
 _Note: Gaps between patch versions are faulty/broken releases._
 
+## 3.3.10
+
+ * **Internal**
+  * Restructure transformers so they're only ran if the AST contains nodes that they need to worry about. Improves transpilation speed significantly.
+ * **Bug Fix**
+  * Fix source maps not tracking end of node locations.
+ * **Spec Compliancy**
+  * Use static super references as the home object is actually done at definition time.
+ * **Polish**
+  * Force the `es6.destructuring` transformer to be whitelisted when the `es7.objectSpread` transformer is.
+  * Join sibling string literals when creating JSX.
+
+## 3.3.9
+
+ * **Bug Fix**
+  * Fix super inside of functions.
+  * Fix super constructor inheritance.
+
+## 3.3.7
+
+ * **Bug Fix**
+  * Add `--use-strict` to valid node flags in `6to5-node`.
+  * Fix booleans not being properly stripped from the arguments in `6to5-node`.
+  * Force `.js` extension when writing files to directories with `6to5`.
+
+## 3.3.5
+
+ * **Bug Fix**
+  * Fix block scoping inside of while loops.
+  * Make module name regex more conservative. Thanks [@johlrich](https://github.com/johlrich)!
+  * Fix block scoping of constants.
+  * Fix istanbul interop.
+  * Make JSX transforming more inline with the official transformer with spaces after non-empty last lines.
+ * **Polish**
+  * Make it illegal to export a property called `__esModule`.
+
+## 3.3.4
+
+ * **Polish**
+  * Add istanbul `require` interop.
+ * **Bug Fix**
+  * Fix incorrect source map column tracking in specific scenarios.
+
+## 3.3.3
+
+ * **Polish**
+  * Remap top level `this` to `undefined` instead of throwing an error.
+ * **Bug Fix**
+  * Run `selfContained` transformer over the regenerator runtime when building `6to5-runtime`.
+  * Fix `t.isReferenced` not properly allowing `value` nodes.
+
+## 3.3.1
+
+ * **Bug Fix**
+  * Block hoist assignment pattern destructuring.
+
+## 3.3.0
+
+ * **Bug Fix**
+  * Do all transforms before the regenerator transform is ran.
+ * **New Feature**
+  * Added back the 2.x optional runtime.
+
+## 3.2.1
+
+ * **Bug Fix**
+  * Fix block scoping transformer rewriting breaks and continues to inner labels.
+
+## 3.2.0
+
+ * **Bug Fix**
+  * Fixed scope tracking for default parameters IIFE.
+  * Fixed block scoped functions.
+  * Improved `bin/6to5` path resolution.
+ * **New Feature**
+  * You can now trigger super setters in classes. Thanks [@kruppel](https://github.com/kruppel)!
+  * Add `resolveSourceMap` option.
+  * Better support and output for block scoping loops with labels.
+
+## 3.1.1
+
+ * **Polish**
+  * Drop `enumerable: false` clause from class method definitions as `enumerable` already defaults to `false`.
+ * **Bug Fix**
+  * Properly transform `XJSIdentifier` nodes referencing `this` into a `ThisExpression`.
+
+## 3.1.0
+
+ * **Breaking Change**
+  * [Make class methods unenumerable](https://esdiscuss.org/topic/classes-and-enumerability#content-61).
+
+## 3.0.16
+
+ * **Bug Fix**
+  * Don't ignore dynamic import specifiers.
+ * **Internal**
+  * Upgrade `regenerator-6to5`.
+ * **Polish**
+  * Use `Object.assign` in place of extends helper if it exists.
+  * Require individual `lodash` methods. Thanks [@stefanpenner](https://github.com/stefanpenner)!
+
+## 3.0.15
+
+ * **Bug Fix**
+  * Use `debug/node` instead of `debug` to avoid browserify using the browser version that references `window`.
+
+## 3.0.14
+
+ * **New Feature**
+  * Add `--optional` argument to `6to5-node`.
+ * **Bug Fix**
+  * Fix bug in `asyncToGenerator` helper where it was incorrectly calling generator iterator functions.
+
+## 3.0.13
+
+ * **Bug Fix**
+  * Fix modules loose mode using `modules` instead of `es6.modules`.
+
+## 3.0.12
+
+ * **Internal**
+  * Add internal debug messages.
+ * **Bug Fix**
+  * Add `noScope` option to `traverse.clearProperties`.
+
+## 3.0.11
+
+ * **Bug Fix**
+  * Fix `ast-types` `RestElement` definition.
+  * Make `es6.forOf` loose mode more versatile and support destructuring.
+
+## 3.0.10
+
+ * **Bug Fix**
+  * In `types.getIds` make sure the `declaration` inside of `ExportDeclaration` is actually a `Declaration`.
+
+## 3.0.9
+
+ * **Bug Fix**
+  * Make `t.isReferenced` more powerful, actually take into consideration all contexts were identifier nodes aren't actually references.
+  * Don't camelcase underscores when converting a string to a valid identifier.
+
+## 3.0.8
+
+ * **Bug Fix**
+  * Split up default function declaration exports due to regenerator destroying the parent export declaration.
+
+## 3.0.7
+
+ * **Internal**
+  * Upgrade `core-js` to `0.4.9`.
+ * **Bug Fix**
+  * Add id to function express scope tracking.
+
+## 3.0.6
+
+ * **Bug Fix**
+  * Fix block scope variable tracking stopping whenever it hits a new scope.
+  * Fix block scope variable tracking breaking on all block statement scopes that have a for loop parent.
+
 ## 3.0.5
 
  * **Internal**
@@ -70,13 +230,13 @@ _Note: Gaps between patch versions are faulty/broken releases._
   * This shorthand has been removed from the playground.
   * `6to5/polyfill` can now only be required **once**.
   * **CLI**
-   * `--indent` option has been removed.
-   * `--include-regenerator` option has been removed.
-   * `--amd-modules-id` option has been removed, use `--module-ids` instead.
+    * `--indent` option has been removed.
+    * `--include-regenerator` option has been removed.
+    * `--amd-modules-id` option has been removed, use `--module-ids` instead.
   * **Options**
-   * `amdModuleIds` option has been removed, use `moduleIds` instead.
-   * `includeRegenerator` has been removed.
-   * `ignoreRegex` fallback has now been dropped from the require hook. `register(/foo/);`, `register({ ignoreRegex: /foo/ })` -> `register({ ignore: /foo/ })`.
+    * `amdModuleIds` option has been removed, use `moduleIds` instead.
+    * `includeRegenerator` has been removed.
+    * `ignoreRegex` fallback has now been dropped from the require hook. `register(/foo/);`, `register({ ignoreRegex: /foo/ })` -> `register({ ignore: /foo/ })`.
   * **Modules**
     * Module interop now only collapses to `module.exports` when there's a **single** export that's default.
     * Imports and exports are now illegal anywhere except the root level by default. Set `modules` to [loose mode](http://6to5.org/docs/usage/loose) to allow them everywhere.
@@ -209,8 +369,8 @@ _Note: Gaps between patch versions are faulty/broken releases._
  * **Polish**
   * Rest parameters now allocate the array before populating.
  * **Internal**
-  * `for...in` loops have been changed to optimised `for` loops - better performance and no enumeration of protoype keys.
-  * Parts of the code generator have now been optimised thanks to [gaearon](https://github.com/gaearon).
+  * `for...in` loops have been changed to optimized `for` loops - better performance and no enumeration of protoype keys.
+  * Parts of the code generator have now been optimized thanks to [gaearon](https://github.com/gaearon).
 
 ## 2.12.3
 
@@ -233,7 +393,7 @@ _Note: Gaps between patch versions are faulty/broken releases._
  * **Bug Fix**
   * Support non-string JSX literals.
  * **New Feature**
-  * Loose mode for some transformers that enables non-spec behaviour.
+  * Loose mode for some transformers that enables non-spec behavior.
  * **Internal**
   * Uglify `--mangle sort` has been added to the build script, cutting minified scripts in half.
 
@@ -671,7 +831,7 @@ _Note: Gaps between patch versions are faulty/broken releases._
 
 ## 1.13.2
 
- * Optimise `Array.from` usage by adding a helper method.
+ * Optimize `Array.from` usage by adding a helper method.
  * Upgrade `acorn-6to5`.
 
 ## 1.13.1

Makefile

@@ -21,6 +21,9 @@ build:
 	node $(BROWSERIFY_CMD) lib/6to5/browser.js -s to5 >dist/6to5.js
 	node $(UGLIFY_CMD) dist/6to5.js >dist/6to5.min.js
 
+	node bin/6to5-runtime >dist/runtime.js
+	node $(UGLIFY_CMD) dist/runtime.js >dist/runtime.min.js
+
 	rm -rf templates.json
 
 clean:
@@ -77,6 +80,7 @@ publish:
 	make build
 	cp dist/6to5.min.js browser.js
 	cp dist/polyfill.min.js browser-polyfill.js
+	cp dist/runtime.min.js runtime.js
 
 	node tools/cache-templates
 	test -f templates.json
@@ -110,3 +114,4 @@ bootstrap:
 	npm install
 	git submodule update --init
 	cd vendor/regenerator; npm install
+	cd vendor/compat-table; npm install object-assign

NOTES.md

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

bin/6to5-minify

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

bin/6to5-node

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

bin/6to5-runtime

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

bin/6to5/dir.js

@@ -11,6 +11,9 @@ module.exports = function (commander, filenames, opts) {
   }
 
   var write = function (src, relative) {
+    // remove extension and then append back on .js
+    relative = relative.replace(/\.(\w*?)$/, "") + ".js";
+
     var dest = path.join(commander.outDir, relative);
 
     var data = util.compile(src, { sourceMapName: dest });
@@ -53,10 +56,7 @@ module.exports = function (commander, filenames, opts) {
 
       _.each(["add", "change"], function (type) {
         watcher.on(type, function (filename) {
-          // chop off the dirname plus the path separator
-          var relative = filename.slice(dirname.length + 1);
-
-          console.log(type, filename);
+          var relative = path.relative(dirname, filename) || filename;
           write(filename, relative);
         });
       });

bin/6to5/index.js

@@ -1,15 +1,17 @@
 #!/usr/bin/env node
 
 var commander = require("commander");
-var transform = require("../../lib/6to5/transformation/transform");
+var transform = require("../../lib/6to5/transformation");
 var util      = require("../../lib/6to5/util");
 var fs        = require("fs");
-var _         = require("lodash");
+var each      = require("lodash/collection/each");
+var keys      = require("lodash/object/keys");
 
 commander.option("-t, --source-maps-inline", "Append sourceMappingURL comment to bottom of code");
 commander.option("-s, --source-maps", "Save source map alongside the compiled code");
 commander.option("-f, --filename [filename]", "Filename to use when reading from stdin - this will be used in source-maps, errors etc [stdin]", "stdin");
 commander.option("-w, --watch", "Recompile files on changes");
+commander.option("-r, --runtime", "Replace 6to5 declarations with references to a runtime");
 commander.option("-e, --experimental", "Enable experimental support for proposed ES7 features");
 commander.option("-p, --playground", "Enable playground support");
 
@@ -30,7 +32,7 @@ commander.on("--help", function () {
     console.log("  " + title + ":");
     console.log();
 
-    _.each(_.keys(obj).sort(), function (key) {
+    each(keys(obj).sort(), function (key) {
       if (key[0] === "_") return;
 
       if (obj[key].optional) {
@@ -58,7 +60,7 @@ var errors = [];
 
 var filenames = commander.args;
 
-_.each(filenames, function (filename) {
+each(filenames, function (filename) {
   if (!fs.existsSync(filename)) {
     errors.push(filename + " doesn't exist");
   }
@@ -107,16 +109,22 @@ exports.opts = {
   sourceMap:              commander.sourceMaps || commander.sourceMapsInline,
   optional:               commander.optional,
   comments:               !commander.removeComments,
+  runtime:                commander.runtime,
   modules:                commander.modules,
   loose:                  commander.loose
 };
 
-var fn;
+setTimeout(function () {
+  // this is just a hack to give `6to5-minify` and other files including this
+  // time to modify `exports.opts`
 
-if (commander.outDir) {
-  fn = require("./dir");
-} else {
-  fn = require("./file");
-}
+  var fn;
 
-fn(commander, filenames, exports.opts);
+  if (commander.outDir) {
+    fn = require("./dir");
+  } else {
+    fn = require("./file");
+  }
+
+  fn(commander, filenames, exports.opts);
+}, 0);

bin/_6to5-node

@@ -19,6 +19,7 @@ program.option("-r, --experimental", "Enable experimental support for proposed E
 program.option("-g, --playground", "Enable playground support");
 program.option("-w, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util.list);
 program.option("-b, --blacklist [blacklist]", "Blacklist of transformers to NOT use", util.list);
+program.option("-o, --optional [optional]", "List of optional transformers to enable", util.list);
 
 var pkg = require("../package.json");
 program.version(pkg.version);
@@ -33,6 +34,7 @@ to5.register({
   playground:   program.playground,
   blacklist:    program.blacklist,
   whitelist:    program.whitelist,
+  optional:     program.optional,
   ignore:       program.ignore
 });
 
@@ -43,6 +45,7 @@ var _eval = function (code, filename) {
     filename: filename,
     blacklist: ["useStrict"].concat(program.blacklist || []),
     whitelist: program.whitelist,
+    optional: program.optional,
     experimental: program.experimental,
     playground: program.playground
   }).code;
@@ -61,8 +64,19 @@ if (program.eval || program.print) {
     var args = process.argv.slice(2);
 
     var i = 0;
+    var ignoreNext = false;
     _.each(args, function (arg, i2) {
-      if (arg[0] !== "-") {
+      if (ignoreNext) {
+        ignoreNext = false;
+        return;
+      }
+
+      if (arg[0] === "-") {
+        var parsedArg = program[arg.slice(2)];
+        if (parsedArg && parsedArg !== true) {
+          ignoreNext = true;
+        }
+      } else {
         i = i2;
         return false;
       }

lib/6to5/browser.js

@@ -1,6 +1,6 @@
 "use strict";
 
-var transform = module.exports = require("./transformation/transform");
+var transform = module.exports = require("./transformation");
 
 transform.version = require("../../package").version;
 

lib/6to5/build-helpers.js

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

lib/6to5/build-runtime.js

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

lib/6to5/detection/index.js

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

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

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

lib/6to5/detection/visitors.js

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

lib/6to5/file.js

@@ -4,13 +4,17 @@ module.exports = File;
 
 var SHEBANG_REGEX = /^\#\!.*/;
 
-var transform = require("./transformation/transform");
-var generate  = require("./generation/generator");
-var clone     = require("./helpers/clone");
-var Scope     = require("./traverse/scope");
-var util      = require("./util");
-var t         = require("./types");
-var _         = require("lodash");
+var isFunction = require("lodash/lang/isFunction");
+var transform  = require("./transformation");
+var generate   = require("./generation");
+var defaults   = require("lodash/object/defaults");
+var contains   = require("lodash/collection/contains");
+var clone      = require("./helpers/clone");
+var Scope      = require("./traverse/scope");
+var util       = require("./util");
+var path       = require("path");
+var each       = require("lodash/collection/each");
+var t          = require("./types");
 
 function File(opts) {
   this.dynamicImportIds = {};
@@ -21,7 +25,7 @@ function File(opts) {
   this.data             = {};
 
   this.lastStatements   = [];
-  this.opts             = File.normaliseOptions(opts);
+  this.opts             = this.normalizeOptions(opts);
   this.ast              = {};
 
   this.buildTransformers();
@@ -46,7 +50,10 @@ File.helpers = [
   "interop-require-wildcard",
   "typeof",
   "extends",
-  "get"
+  "get",
+  "set",
+  "class-call-check",
+  "object-destructuring-empty"
 ];
 
 File.validOptions = [
@@ -71,14 +78,17 @@ File.validOptions = [
   "format",
   "playground",
   "experimental",
+  "resolveModuleSource",
+  "runtime",
 
   // these are used by plugins
   "ignore",
   "only",
-  "extensions"
+  "extensions",
+  "accept"
 ];
 
-File.normaliseOptions = function (opts) {
+File.prototype.normalizeOptions = function (opts) {
   opts = clone(opts);
 
   for (var key in opts) {
@@ -87,8 +97,9 @@ File.normaliseOptions = function (opts) {
     }
   }
 
-  _.defaults(opts, {
+  defaults(opts, {
     keepModuleIdExtensions: false,
+    resolveModuleSource:    null,
     experimental:           false,
     reactCompat:            false,
     playground:             false,
@@ -101,36 +112,39 @@ File.normaliseOptions = function (opts) {
     comments:               true,
     filename:               "unknown",
     modules:                "common",
+    runtime:                false,
     loose:                  [],
     code:                   true,
     ast:                    true
   });
 
-  // normalise windows path separators to unix
+  // normalize windows path separators to unix
   opts.filename = opts.filename.replace(/\\/g, "/");
 
+  opts.basename = path.basename(opts.filename, path.extname(opts.filename));
+
   opts.blacklist = util.arrayify(opts.blacklist);
   opts.whitelist = util.arrayify(opts.whitelist);
   opts.optional  = util.arrayify(opts.optional);
   opts.loose     = util.arrayify(opts.loose);
 
-  if (_.contains(opts.loose, "all")) {
+  if (contains(opts.loose, "all")) {
     opts.loose = Object.keys(transform.transformers);
   }
 
-  _.defaults(opts, {
+  defaults(opts, {
     moduleRoot: opts.sourceRoot
   });
 
-  _.defaults(opts, {
+  defaults(opts, {
     sourceRoot: opts.moduleRoot
   });
 
-  _.defaults(opts, {
+  defaults(opts, {
     filenameRelative: opts.filename
   });
 
-  _.defaults(opts, {
+  defaults(opts, {
     sourceFileName: opts.filenameRelative,
     sourceMapName:  opts.filenameRelative
   });
@@ -139,6 +153,10 @@ File.normaliseOptions = function (opts) {
     opts.experimental = true;
   }
 
+  if (opts.runtime) {
+    this.set("runtimeIdentifier", t.identifier("to5Runtime"));
+  }
+
   opts.blacklist = transform._ensureTransformerNames("blacklist", opts.blacklist);
   opts.whitelist = transform._ensureTransformerNames("whitelist", opts.whitelist);
   opts.optional = transform._ensureTransformerNames("optional", opts.optional);
@@ -148,7 +166,7 @@ File.normaliseOptions = function (opts) {
 };
 
 File.prototype.isLoose = function (key) {
-  return _.contains(this.opts.loose, key);
+  return contains(this.opts.loose, key);
 };
 
 File.prototype.buildTransformers = function () {
@@ -159,11 +177,12 @@ File.prototype.buildTransformers = function () {
   var secondaryStack = [];
   var stack = [];
 
-  _.each(transform.transformers, function (transformer, key) {
+  each(transform.transformers, function (transformer, key) {
     var pass = transformers[key] = transformer.buildPass(file);
 
     if (pass.canRun(file)) {
       stack.push(pass);
+
       if (transformer.secondPass) {
         secondaryStack.push(pass);
       }
@@ -195,7 +214,7 @@ File.prototype.toArray = function (node, i) {
 };
 
 File.prototype.getModuleFormatter = function (type) {
-  var ModuleFormatter = _.isFunction(type) ? type : transform.moduleFormatters[type];
+  var ModuleFormatter = isFunction(type) ? type : transform.moduleFormatters[type];
 
   if (!ModuleFormatter) {
     var loc = util.resolve(type);
@@ -264,7 +283,7 @@ File.prototype.isConsequenceExpressionStatement = function (node) {
 };
 
 File.prototype.addHelper = function (name) {
-  if (!_.contains(File.helpers, name)) {
+  if (!contains(File.helpers, name)) {
     throw new ReferenceError("unknown declaration " + name);
   }
 
@@ -312,7 +331,8 @@ File.prototype.parse = function (code) {
 
   var opts = this.opts;
 
-  opts.allowImportExportEverywhere = this.isLoose("modules");
+  opts.allowImportExportEverywhere = this.isLoose("es6.modules");
+  //opts.strictMode = this.transformers.useStrict.canRun();
 
   return util.parse(opts, code, function (tree) {
     self.transform(tree);
@@ -323,26 +343,58 @@ File.prototype.parse = function (code) {
 File.prototype.transform = function (ast) {
   var self = this;
 
+  util.debug(this.opts.filename);
+
   this.ast = ast;
   this.lastStatements = t.getLastStatements(ast.program);
-  this.scope = new Scope(ast.program, null, this);
-  this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
+  this.scope = new Scope(ast.program, ast, null, this);
+
+  var modFormatter = this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
+  if (modFormatter.init && this.transformers["es6.modules"].canRun()) {
+    modFormatter.init();
+  }
+
+  this.checkNode(ast);
 
   var astRun = function (key) {
-    _.each(self.transformerStack, function (pass) {
+    each(self.transformerStack, function (pass) {
       pass.astRun(key);
     });
   };
 
   astRun("enter");
 
-  _.each(this.transformerStack, function (pass) {
+  each(this.transformerStack, function (pass) {
     pass.transform();
   });
 
   astRun("exit");
 };
 
+var checkTransformerVisitor = {
+  enter: function (node, parent, scope, context, state) {
+    state.check(node, scope);
+  }
+};
+
+File.prototype.checkNode = function (node, scope) {
+  var self = this;
+  scope = scope || this.scope;
+
+  var check = function (node, scope) {
+    each(self.transformerStack, function (pass) {
+      if (pass.shouldRun) return;
+      pass.checkNode(node, scope);
+    });
+  };
+
+  check(node, scope);
+
+  scope.traverse(node, checkTransformerVisitor, {
+    check: check
+  });
+};
+
 File.prototype.generate = function () {
   var opts = this.opts;
   var ast  = this.ast;
@@ -382,14 +434,14 @@ File.prototype.generateUid = function (name, scope) {
   do {
     uid = this._generateUid(name, i);
     i++;
-  } while (scope.has(uid));
+  } while (scope.hasReference(uid));
   return uid;
 };
 
 File.prototype.generateUidIdentifier = function (name, scope) {
   scope = scope || this.scope;
   var id = t.identifier(this.generateUid(name, scope));
-  scope.add(id);
+  scope.addDeclarationToFunctionScope("var", id);
   return id;
 };
 

lib/6to5/generation/buffer.js

@@ -2,8 +2,10 @@
 
 module.exports = Buffer;
 
-var util = require("../util");
-var _    = require("lodash");
+var util      = require("../util");
+var isNumber  = require("lodash/lang/isNumber");
+var isBoolean = require("lodash/lang/isBoolean");
+var contains  = require("lodash/collection/contains");
 
 function Buffer(position, format) {
   this.position = position;
@@ -17,7 +19,7 @@ Buffer.prototype.get = function () {
 };
 
 Buffer.prototype.getIndent = function () {
-  if (this.format.compact) {
+  if (this.format.compact || this.format.concise) {
     return "";
   } else {
     return util.repeat(this._indent, this.format.indent.style);
@@ -51,10 +53,12 @@ Buffer.prototype.rightBrace = function () {
 
 Buffer.prototype.keyword = function (name) {
   this.push(name);
-  this.push(" ");
+  this.space();
 };
 
 Buffer.prototype.space = function () {
+  if (this.format.compact) return;
+
   if (this.buf && !this.isLast([" ", "\n"])) {
     this.push(" ");
   }
@@ -68,14 +72,14 @@ Buffer.prototype.removeLast = function (cha) {
 };
 
 Buffer.prototype.newline = function (i, removeLast) {
-  if (this.format.compact) {
+  if (this.format.compact || this.format.concise) {
     this.space();
     return;
   }
 
   removeLast = removeLast || false;
 
-  if (_.isNumber(i)) {
+  if (isNumber(i)) {
     if (this.endsWith("{\n")) i--;
     if (this.endsWith(util.repeat(i, "\n"))) return;
 
@@ -85,7 +89,7 @@ Buffer.prototype.newline = function (i, removeLast) {
     return;
   }
 
-  if (_.isBoolean(i)) {
+  if (isBoolean(i)) {
     removeLast = i;
   }
 
@@ -155,7 +159,7 @@ Buffer.prototype.isLast = function (cha, trimRight) {
   var last = buf[buf.length - 1];
 
   if (Array.isArray(cha)) {
-    return _.contains(cha, last);
+    return contains(cha, last);
   } else {
     return cha === last;
   }

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

@@ -1,8 +1,8 @@
 "use strict";
 
-var util = require("../../util");
-var t    = require("../../types");
-var _    = require("lodash");
+var util     = require("../../util");
+var t        = require("../../types");
+var isNumber = require("lodash/lang/isNumber");
 
 exports.UnaryExpression = function (node, print) {
   var hasSpace = /[a-z]$/.test(node.operator);
@@ -17,7 +17,7 @@ exports.UnaryExpression = function (node, print) {
   }
 
   this.push(node.operator);
-  if (hasSpace) this.space();
+  if (hasSpace) this.push(" ");
   print(node.argument);
 };
 
@@ -33,9 +33,13 @@ exports.UpdateExpression = function (node, print) {
 
 exports.ConditionalExpression = function (node, print) {
   print(node.test);
-  this.push(" ? ");
+  this.space();
+  this.push("?");
+  this.space();
   print(node.consequent);
-  this.push(" : ");
+  this.space();
+  this.push(":");
+  this.space();
   print(node.alternate);
 };
 
@@ -44,13 +48,13 @@ exports.NewExpression = function (node, print) {
   print(node.callee);
   if (node.arguments.length || this.format.parentheses) {
     this.push("(");
-    print.join(node.arguments, { separator: ", " });
+    print.list(node.arguments);
     this.push(")");
   }
 };
 
 exports.SequenceExpression = function (node, print) {
-  print.join(node.expressions, { separator: ", " });
+  print.list(node.expressions);
 };
 
 exports.ThisExpression = function () {
@@ -72,9 +76,7 @@ exports.CallExpression = function (node, print) {
     separator += " ";
   }
 
-  print.join(node.arguments, {
-    separator: separator
-  });
+  print.list(node.arguments, { separator: separator });
 
   if (node._prettyCall) {
     this.newline();
@@ -87,7 +89,11 @@ exports.CallExpression = function (node, print) {
 var buildYieldAwait = function (keyword) {
   return function (node, print) {
     this.push(keyword);
-    if (node.delegate) this.push("*");
+
+    if (node.delegate || node.all) {
+      this.push("*");
+    }
+
     if (node.argument) {
       this.space();
       print(node.argument);
@@ -111,10 +117,11 @@ exports.BinaryExpression =
 exports.LogicalExpression =
 exports.AssignmentPattern =
 exports.AssignmentExpression = function (node, print) {
+  // todo: add cases where the spaces can be dropped when in compact mode
   print(node.left);
-  this.space();
+  this.push(" ");
   this.push(node.operator);
-  this.space();
+  this.push(" ");
   print(node.right);
 };
 
@@ -129,7 +136,7 @@ exports.MemberExpression = function (node, print) {
   }
 
   var computed = node.computed;
-  if (t.isLiteral(node.property) && _.isNumber(node.property.value)) {
+  if (t.isLiteral(node.property) && isNumber(node.property.value)) {
     computed = true;
   }
 

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

@@ -1,7 +1,7 @@
 "use strict";
 
-var t = require("../../types");
-var _ = require("lodash");
+var t    = require("../../types");
+var each = require("lodash/collection/each");
 
 exports.JSXAttribute = function (node, print) {
   print(node.name);
@@ -47,7 +47,7 @@ exports.JSXElement = function (node, print) {
   if (open.selfClosing) return;
 
   this.indent();
-  _.each(node.children, function (child) {
+  each(node.children, function (child) {
     if (t.isLiteral(child)) {
       self.push(child.value);
     } else {
@@ -75,6 +75,4 @@ exports.JSXClosingElement = function (node, print) {
   this.push(">");
 };
 
-exports.JSXEmptyExpression = function () {
-
-};
+exports.JSXEmptyExpression = function () {};

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

@@ -4,11 +4,7 @@ var t = require("../../types");
 
 exports._params = function (node, print) {
   this.push("(");
-
-  print.join(node.params, {
-    separator: ", "
-  });
-
+  print.list(node.params);
   this.push(")");
 };
 
@@ -45,11 +41,14 @@ exports.FunctionExpression = function (node, print) {
   if (node.async) this.push("async ");
   this.push("function");
   if (node.generator) this.push("*");
-  this.push(" ");
+
   if (node.id) {
-    this.space();
+    this.push(" ");
     print(node.id);
+  } else {
+    this.space();
   }
+
   this._params(node, print);
   this.space();
   print(node.body);

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

@@ -1,7 +1,7 @@
 "use strict";
 
-var t = require("../../types");
-var _ = require("lodash");
+var t    = require("../../types");
+var each = require("lodash/collection/each");
 
 exports.ImportSpecifier = function (node, print) {
   if (t.isSpecifierDefault(node)) {
@@ -66,7 +66,7 @@ exports.ImportDeclaration = function (node, print) {
   if (specfiers && specfiers.length) {
     var foundImportSpecifier = false;
 
-    _.each(node.specifiers, function (spec, i) {
+    each(node.specifiers, function (spec, i) {
       if (+i > 0) {
         self.push(", ");
       }

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

@@ -1,8 +1,8 @@
 "use strict";
 
-var _ = require("lodash");
+var each = require("lodash/collection/each");
 
-_.each(["BindMemberExpression", "BindFunctionExpression"], function (type) {
+each(["BindMemberExpression", "BindFunctionExpression"], function (type) {
   exports[type] = function () {
     throw new ReferenceError("Trying to render non-standard playground node " + JSON.stringify(type));
   };

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

@@ -23,6 +23,11 @@ exports.IfStatement = function (node, print) {
   if (node.alternate) {
     if (this.isLast("}")) this.push(" ");
     this.keyword("else");
+
+    if (this.format.format && !t.isBlockStatement(node.alternate)) {
+      this.push(" ");
+    }
+
     print.indentOnComments(node.alternate);
   }
 };
@@ -190,7 +195,7 @@ exports.VariableDeclaration = function (node, print, parent) {
     sep += " ";
   }
 
-  print.join(node.declarations, { separator: sep });
+  print.list(node.declarations, { separator: sep });
 
   if (!t.isFor(parent)) {
     this.semicolon();

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

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

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

@@ -1,6 +1,6 @@
 "use strict";
 
-var _ = require("lodash");
+var each = require("lodash/collection/each");
 
 exports.Identifier = function (node) {
   this.push(node.name);
@@ -27,7 +27,7 @@ exports.ObjectPattern = function (node, print) {
     this.push("{");
     this.space();
 
-    print.join(props, { separator: ", ", indent: true });
+    print.list(props, { indent: true });
 
     this.space();
     this.push("}");
@@ -49,7 +49,8 @@ exports.Property = function (node, print) {
       if (node.shorthand) return;
     }
 
-    this.push(": ");
+    this.push(":");
+    this.space();
     print(node.value);
   }
 };
@@ -62,7 +63,7 @@ exports.ArrayPattern = function (node, print) {
 
   this.push("[");
 
-  _.each(elems, function (elem, i) {
+  each(elems, function (elem, i) {
     if (!elem) {
       // If the array expression ends with a hole, that hole
       // will be ignored by the interpreter, but if it ends with
@@ -71,7 +72,7 @@ exports.ArrayPattern = function (node, print) {
       // both (all) of the holes.
       self.push(",");
     } else {
-      if (i > 0) self.push(" ");
+      if (i > 0 && !self.format.compact) self.push(" ");
       print(elem);
       if (i < len - 1) self.push(",");
     }
@@ -93,8 +94,10 @@ exports.Literal = function (node) {
     });
 
     this.push(val);
-  } else if (type === "boolean" || type === "number") {
-    this.push(JSON.stringify(val));
+  } else if (type === "number") {
+    this.push(val + "");
+  } else if (type === "boolean") {
+    this.push(val ? "true" : "false");
   } else if (node.regex) {
     this.push("/" + node.regex.pattern + "/" + node.regex.flags);
   } else if (val === null) {

lib/6to5/generation/index.js

@@ -15,14 +15,16 @@ var Buffer       = require("./buffer");
 var util         = require("../util");
 var n            = require("./node");
 var t            = require("../types");
-var _            = require("lodash");
+var each         = require("lodash/collection/each");
+var extend       = require("lodash/object/extend");
+var merge        = require("lodash/object/merge");
 
 function CodeGenerator(ast, opts, code) {
   opts = opts || {};
 
   this.comments = ast.comments || [];
   this.tokens   = ast.tokens || [];
-  this.format   = CodeGenerator.normaliseOptions(code, opts);
+  this.format   = CodeGenerator.normalizeOptions(code, opts);
   this.ast      = ast;
 
   this.whitespace = new Whitespace(this.tokens, this.comments);
@@ -31,21 +33,24 @@ function CodeGenerator(ast, opts, code) {
   this.buffer     = new Buffer(this.position, this.format);
 }
 
-_.each(Buffer.prototype, function (fn, key) {
+each(Buffer.prototype, function (fn, key) {
   CodeGenerator.prototype[key] = function () {
     return fn.apply(this.buffer, arguments);
   };
 });
 
-CodeGenerator.normaliseOptions = function (code, opts) {
-  var indent = detectIndent(code);
-  var style  = indent.indent;
-  if (!style || style === " ") style = "  ";
+CodeGenerator.normalizeOptions = function (code, opts) {
+  var style = "  ";
+  if (code) {
+    var indent = detectIndent(code).indent;
+    if (indent && indent !== " ") style = indent;
+  }
 
-  return _.merge({
+  return merge({
     parentheses: true,
     comments: opts.comments == null || opts.comments,
     compact: false,
+    concise: false,
     indent: {
       adjustMultilineComment: true,
       style: style,
@@ -69,8 +74,8 @@ CodeGenerator.generators = {
   jsx:              require("./generators/jsx")
 };
 
-_.each(CodeGenerator.generators, function (generator) {
-  _.extend(CodeGenerator.prototype, generator);
+each(CodeGenerator.generators, function (generator) {
+  extend(CodeGenerator.prototype, generator);
 });
 
 CodeGenerator.prototype.generate = function () {
@@ -79,7 +84,7 @@ CodeGenerator.prototype.generate = function () {
   this.print(ast);
 
   var comments = [];
-  _.each(ast.comments, function (comment) {
+  each(ast.comments, function (comment) {
     if (!comment._displayed) comments.push(comment);
   });
   this._printComments(comments);
@@ -107,6 +112,16 @@ CodeGenerator.prototype.buildPrint = function (parent) {
     return self.printJoin(print, nodes, opts);
   };
 
+  print.list = function (items, opts) {
+    opts = opts || {};
+
+    var sep = opts.separator || ", ";
+    if (self.format.compact) sep = ",";
+    opts.separator = sep;
+
+    print.join(items, opts);
+  };
+
   print.block = function (node) {
     return self.printBlock(print, node);
   };
@@ -125,9 +140,9 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
     node._compact = true;
   }
 
-  var oldCompact = this.format.compact;
+  var oldConcise = this.format.concise;
   if (node._compact) {
-    this.format.compact = true;
+    this.format.concise = true;
   }
 
   var self = this;
@@ -195,7 +210,7 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
     throw new ReferenceError("unknown node of type " + JSON.stringify(node.type) + " with constructor " + JSON.stringify(node && node.constructor.name));
   }
 
-  this.format.compact = oldCompact;
+  this.format.concise = oldConcise;
 };
 
 CodeGenerator.prototype.printJoin = function (print, nodes, opts) {
@@ -208,7 +223,7 @@ CodeGenerator.prototype.printJoin = function (print, nodes, opts) {
 
   if (opts.indent) self.indent();
 
-  _.each(nodes, function (node, i) {
+  each(nodes, function (node, i) {
     print(node, {
       statement: opts.statement,
       after: function () {
@@ -273,7 +288,7 @@ CodeGenerator.prototype.getComments = function (key, node, parent) {
     nodes.push(node.argument);
   }
 
-  _.each(nodes, function (node) {
+  each(nodes, function (node) {
     comments = comments.concat(self._getComments(key, node));
   });
 
@@ -291,11 +306,11 @@ CodeGenerator.prototype._printComments = function (comments) {
 
   var self = this;
 
-  _.each(comments, function (comment) {
+  each(comments, function (comment) {
     var skip = false;
 
     // find the original comment in the ast and set it as displayed
-    _.each(self.ast.comments, function (origComment) {
+    each(self.ast.comments, function (origComment) {
       if (origComment.start === comment.start) {
         // comment has already been output
         if (origComment._displayed) skip = true;

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

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

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

@@ -1,11 +1,11 @@
 "use strict";
 
-var t = require("../../types");
-var _ = require("lodash");
+var t    = require("../../types");
+var each = require("lodash/collection/each");
 
 var PRECEDENCE = {};
 
-_.each([
+each([
   ["||"],
   ["&&"],
   ["|"],
@@ -18,7 +18,7 @@ _.each([
   ["*", "/", "%"],
   ["**"]
 ], function (tier, i) {
-  _.each(tier, function (op) {
+  each(tier, function (op) {
     PRECEDENCE[op] = i;
   });
 });

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

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

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

@@ -48,8 +48,6 @@ SourceMap.prototype.mark = function (node, type) {
 
   var original = loc[type];
 
-  if (generated.line === original.line && generated.column === original.column) return; // nothing to map
-
   map.addMapping({
     source: this.opts.sourceFileName,
     generated: generated,

lib/6to5/generation/whitespace.js

@@ -2,7 +2,7 @@
 
 module.exports = Whitespace;
 
-var _    = require("lodash");
+var sortBy = require("lodash/collection/sortBy");
 
 /**
  * Returns `i`th number from `base`, continuing from 0 when `max` is reached.
@@ -23,7 +23,7 @@ function getLookupIndex(i, base, max) {
 }
 
 function Whitespace(tokens, comments) {
-  this.tokens = _.sortBy(tokens.concat(comments), "start");
+  this.tokens = sortBy(tokens.concat(comments), "start");
   this.used   = {};
 
   // Profiling this code shows that while generator passes over it, indexes

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

@@ -47,7 +47,7 @@ module.exports = function (lines, lineNumber, colNumber) {
     lines = highlight(lines);
   }
 
-  lines = lines.split("\n");
+  lines = lines.split(/\r\n|[\n\r\u2028\u2029]/);
 
   var start = Math.max(lineNumber - 3, 0);
   var end   = Math.min(lines.length, lineNumber + 3);

lib/6to5/helpers/levenshtein.js

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

lib/6to5/index.js

@@ -1,12 +1,14 @@
 "use strict";
 
-var transform = require("./transformation/transform");
-var util      = require("./util");
-var fs        = require("fs");
-var _         = require("lodash");
+var transform  = require("./transformation");
+var util       = require("./util");
+var fs         = require("fs");
+var isFunction = require("lodash/lang/isFunction");
 
 exports.version = require("../../package").version;
 
+exports.runtime = require("./build-runtime");
+
 exports.types = require("./types");
 
 exports.register = function (opts) {
@@ -27,7 +29,7 @@ exports._util = util;
 exports.transform = transform;
 
 exports.transformFile = function (filename, opts, callback) {
-  if (_.isFunction(opts)) {
+  if (isFunction(opts)) {
     callback = opts;
     opts = {};
   }

lib/6to5/patch.js

@@ -1,14 +1,14 @@
 "use strict";
 
-var t = require("./types");
-var _ = require("lodash");
+var t      = require("./types");
+var extend = require("lodash/object/extend");
 
 require("./types/node");
 
 // estraverse
 
 var estraverse = require("estraverse");
-_.extend(estraverse.VisitorKeys, t.VISITOR_KEYS);
+extend(estraverse.VisitorKeys, t.VISITOR_KEYS);
 
 // regenerator-6to5/ast-types
 
@@ -34,9 +34,9 @@ def("ImportBatchSpecifier")
   .field("name", def("Identifier"));
 
 def("RestElement")
-  .bases("Node")
+  .bases("Pattern")
   .build("argument")
-  .field("argument", def("Pattern"));
+  .field("argument", def("expression"));
 
 // Abstract references
 def("VirtualPropertyExpression")

lib/6to5/register-cache.js

@@ -12,14 +12,6 @@ exports.save = function () {
 };
 
 exports.load = function () {
-  if (!fs.existsSync(FILENAME)) return;
-
-  try {
-    data = JSON.parse(fs.readFileSync(FILENAME));
-  } catch (err) {
-    return;
-  }
-
   process.on("exit", exports.save);
 
   var sigint = function () {
@@ -29,6 +21,14 @@ exports.load = function () {
   };
 
   process.on("SIGINT", sigint);
+
+  if (!fs.existsSync(FILENAME)) return;
+
+  try {
+    data = JSON.parse(fs.readFileSync(FILENAME));
+  } catch (err) {
+    return;
+  }
 };
 
 exports.get = function () {

lib/6to5/register.js

@@ -7,7 +7,8 @@ var registerCache    = require("./register-cache");
 var util             = require("./util");
 var to5              = require("./index");
 var fs               = require("fs");
-var _                = require("lodash");
+var extend           = require("lodash/object/extend");
+var each             = require("lodash/collection/each");
 
 sourceMapSupport.install({
   retrieveSourceMap: function (source) {
@@ -33,20 +34,14 @@ var cache = registerCache.get();
 var transformOpts = {};
 var ignoreRegex   = /node_modules/;
 var onlyRegex;
-var whitelist     = [];
 var exts          = {};
 var maps          = {};
-var old           = require.extensions[".js"];
 
 var mtime = function (filename) {
   return +fs.statSync(filename).mtime;
 };
 
-var loader = function (m, filename) {
-  if ((ignoreRegex && ignoreRegex.test(filename)) || (onlyRegex && !onlyRegex.test(filename))) {
-    return old.apply(this, arguments);
-  }
-
+var compile = function (filename) {
   var result;
 
   if (cache) {
@@ -56,11 +51,12 @@ var loader = function (m, filename) {
     }
   }
 
-  result = result || to5.transformFileSync(filename, _.extend({
-    whitelist: whitelist,
-    sourceMap: true,
-    ast:       false
-  }, transformOpts));
+  if (!result) {
+    result = to5.transformFileSync(filename, extend({
+      sourceMap: true,
+      ast:       false
+    }, transformOpts));
+  }
 
   if (cache) {
     result.mtime = mtime(filename);
@@ -69,26 +65,73 @@ var loader = function (m, filename) {
 
   maps[filename] = result.map;
 
-  m._compile(result.code, filename);
+  return result.code;
+};
+
+var shouldIgnore = function (filename) {
+  return (ignoreRegex && ignoreRegex.test(filename)) || (onlyRegex && !onlyRegex.test(filename));
+};
+
+var istanbulMonkey = {};
+
+if (process.env.running_under_istanbul) { // jshint ignore:line
+  // we need to monkey patch fs.readFileSync so we can hook into
+  // what istanbul gets, it's extremely dirty but it's the only way
+  var _readFileSync = fs.readFileSync;
+
+  fs.readFileSync = function (filename) {
+    if (istanbulMonkey[filename]) {
+      delete istanbulMonkey[filename];
+      var code = compile(filename);
+      istanbulMonkey[filename] = true;
+      return code;
+    } else {
+      return _readFileSync.apply(this, arguments);
+    }
+  };
+}
+
+var istanbulLoader = function (m, filename, old) {
+  istanbulMonkey[filename] = true;
+  old(m, filename);
+};
+
+var normalLoader = function (m, filename) {
+  m._compile(compile(filename), filename);
+};
+
+var registerExtension = function (ext) {
+  var old = require.extensions[ext];
+
+  var loader = normalLoader;
+  if (process.env.running_under_istanbul) loader = istanbulLoader; // jshint ignore:line
+
+  require.extensions[ext] = function (m, filename) {
+    if (shouldIgnore(filename)) {
+      old(m, filename);
+    } else {
+      loader(m, filename, old);
+    }
+  };
 };
 
 var hookExtensions = function (_exts) {
-  _.each(exts, function (old, ext) {
+  each(exts, function (old, ext) {
     require.extensions[ext] = old;
   });
 
   exts = {};
 
-  _.each(_exts, function (ext) {
+  each(_exts, function (ext) {
     exts[ext] = require.extensions[ext];
-    require.extensions[ext] = loader;
+    registerExtension(ext);
   });
 };
 
 hookExtensions(util.canCompile.EXTENSIONS);
 
 module.exports = function (opts) {
-  // normalise options
+  // normalize options
   opts = opts || {};
 
   if (opts.only != null) onlyRegex = util.regexify(opts.only);
@@ -103,5 +146,5 @@ module.exports = function (opts) {
   delete opts.cache;
   delete opts.only;
 
-  _.extend(transformOpts, opts);
+  extend(transformOpts, opts);
 };

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

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

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

@@ -5,7 +5,7 @@ var t = require("../../types");
 var getObjRef = function (node, nodes, file, scope) {
   var ref;
   if (t.isIdentifier(node)) {
-    if (scope.has(node.name, true)) {
+    if (scope.hasBinding(node.name)) {
       // this variable is declared in scope so we can be 100% sure
       // that evaluating it multiple times wont trigger a getter
       // or something else
@@ -18,7 +18,7 @@ var getObjRef = function (node, nodes, file, scope) {
   } else if (t.isMemberExpression(node)) {
     ref = node.object;
 
-    if (t.isIdentifier(ref) && scope.has(ref.name)) {
+    if (t.isIdentifier(ref) && scope.hasReference(ref.name)) {
       // the object reference that we need to save is locally declared
       // so as per the previous comment we can be 100% sure evaluating
       // it multiple times will be safe

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

@@ -1,8 +1,7 @@
 "use strict";
 
-var traverse = require("../../traverse");
-var util     = require("../../util");
-var t        = require("../../types");
+var util = require("../../util");
+var t    = require("../../types");
 
 var visitor = {
   enter: function (node, parent, scope, context, state) {
@@ -14,7 +13,7 @@ var visitor = {
 
     // check that we don't have a local variable declared as that removes the need
     // for the wrapper
-    var localDeclar = scope.get(state.id, true);
+    var localDeclar = scope.getBinding(state.id);
     if (localDeclar !== state.outerDeclar) return;
 
     state.selfReference = true;
@@ -32,10 +31,10 @@ exports.property = function (node, file, scope) {
   var state = {
     id: id,
     selfReference: false,
-    outerDeclar: scope.get(id, true),
+    outerDeclar: scope.getBinding(id),
   };
 
-  traverse(node, visitor, scope, state);
+  scope.traverse(node, visitor, state);
 
   if (state.selfReference) {
     // todo: support generators

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

@@ -0,0 +1,22 @@
+var t = require("../../types");
+
+var isCreateClassCallExpression = t.buildMatchMemberExpression("React.createClass");
+
+exports.isCreateClass = function (node) {
+  if (!node || !t.isCallExpression(node)) return false;
+
+  // not React.createClass call member object
+  if (!isCreateClassCallExpression(node.callee)) return false;
+
+  // no call arguments
+  var args = node.arguments;
+  if (args.length !== 1) return false;
+
+  // first node arg is not an object
+  var first = args[0];
+  if (!t.isObjectExpression(first)) return false;
+
+  return true;
+};
+
+exports.isReactComponent = t.buildMatchMemberExpression("React.Component");

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

@@ -1,7 +1,6 @@
 "use strict";
 
-var traverse = require("../../traverse");
-var t        = require("../../types");
+var t = require("../../types");
 
 var visitor = {
   enter: function (node, parent, scope, context) {
@@ -9,6 +8,12 @@ var visitor = {
 
     if (t.isAwaitExpression(node)) {
       node.type = "YieldExpression";
+
+      if (node.all) {
+        // await* foo; -> yield Promise.all(foo);
+        node.all = false;
+        node.argument = t.callExpression(t.memberExpression(t.identifier("Promise"), t.identifier("all")), [node.argument]);
+      }
     }
   }
 };
@@ -17,7 +22,7 @@ module.exports = function (node, callId, scope) {
   node.async = false;
   node.generator = true;
 
-  traverse(node, visitor, scope);
+  scope.traverse(node, visitor);
 
   var call = t.callExpression(callId, [node]);
   var id = node.id;

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

@@ -2,8 +2,7 @@
 
 module.exports = ReplaceSupers;
 
-var traverse = require("../../traverse");
-var t        = require("../../types");
+var t = require("../../types");
 
 /**
  * Description
@@ -21,6 +20,31 @@ function ReplaceSupers(opts) {
   this.file                  = opts.file;
 }
 
+/**
+ * Sets a super class value of the named property.
+ *
+ * @example
+ *
+ *   _set(Object.getPrototypeOf(CLASS.prototype), "METHOD", "VALUE", this)
+ *
+ * @param {Node} property
+ * @param {boolean} isStatic
+ * @param {boolean} isComputed
+ *
+ * @returns {Node}
+ */
+ReplaceSupers.prototype.setSuperProperty = function (property, value, isStatic, isComputed, thisExpression) {
+  return t.callExpression(
+    this.file.addHelper("set"),
+    [
+      isStatic ? this.superName : t.memberExpression(this.superName, t.identifier("prototype")),
+      isComputed ? property : t.literal(property.name),
+      value,
+      thisExpression
+    ]
+  );
+};
+
 /**
  * Gets a node representing the super class value of the named property.
  *
@@ -35,22 +59,81 @@ function ReplaceSupers(opts) {
  * @returns {Node}
  */
 
-ReplaceSupers.prototype.superProperty = function (property, isStatic, isComputed, thisExpression) {
+ReplaceSupers.prototype.getSuperProperty = function (property, isStatic, isComputed, thisExpression) {
   return t.callExpression(
     this.file.addHelper("get"),
     [
-      t.callExpression(
-        t.memberExpression(t.identifier("Object"), t.identifier("getPrototypeOf")),
-        [
-          isStatic ? this.className : t.memberExpression(this.className, t.identifier("prototype"))
-        ]
-      ),
+      isStatic ? this.superName : t.memberExpression(this.superName, t.identifier("prototype")),
       isComputed ? property : t.literal(property.name),
       thisExpression
     ]
   );
 };
 
+/**
+ * Description
+ */
+
+ReplaceSupers.prototype.replace = function () {
+  this.traverseLevel(this.methodNode.value, true);
+};
+
+var visitor = {
+  enter: function (node, parent, scope, context, state) {
+    var topLevel = state.topLevel;
+    var self = state.self;
+
+    if (t.isFunction(node) && !t.isArrowFunctionExpression(node)) {
+      // we need to call traverseLevel again so we're context aware
+      self.traverseLevel(node, false);
+      return context.skip();
+    }
+
+    if (t.isProperty(node, { method: true }) || t.isMethodDefinition(node)) {
+      // break on object methods
+      return context.skip();
+    }
+
+    var getThisReference = topLevel ?
+      // top level so `this` is the instance
+      t.thisExpression :
+      // not in the top level so we need to create a reference
+      self.getThisReference.bind(self);
+
+    var callback = self.specHandle;
+    if (self.isLoose) callback = self.looseHandle;
+    return callback.call(self, getThisReference, node, parent);
+  }
+};
+
+/**
+ * Description
+ *
+ * @param {Object} node
+ * @param {Boolean} topLevel
+ */
+
+ReplaceSupers.prototype.traverseLevel = function (node, topLevel) {
+  var state = { self: this, topLevel: topLevel };
+  this.scope.traverse(node, visitor, state);
+};
+
+/**
+ * Description
+ */
+
+ReplaceSupers.prototype.getThisReference = function () {
+  if (this.topLevelThisReference) {
+    return this.topLevelThisReference;
+  } else {
+    var ref = this.topLevelThisReference = this.file.generateUidIdentifier("this");
+    this.methodNode.value.body.body.unshift(t.variableDeclaration("var", [
+      t.variableDeclarator(this.topLevelThisReference, t.thisExpression())
+    ]));
+    return ref;
+  }
+};
+
 /**
  * Description
  *
@@ -60,7 +143,7 @@ ReplaceSupers.prototype.superProperty = function (property, isStatic, isComputed
  * @returns {Object}
  */
 
-ReplaceSupers.prototype.looseSuperProperty = function (methodNode, id, parent) {
+ReplaceSupers.prototype.getLooseSuperProperty = function (methodNode, id, parent) {
   var methodName = methodNode.key;
   var superName  = this.superName || t.identifier("Function");
 
@@ -92,70 +175,6 @@ ReplaceSupers.prototype.looseSuperProperty = function (methodNode, id, parent) {
   }
 };
 
-/**
- * Description
- */
-
-ReplaceSupers.prototype.replace = function () {
-  this.traverseLevel(this.methodNode.value, true);
-};
-
-var visitor = {
-  enter: function (node, parent, scope, context, state) {
-    var topLevel = state.topLevel;
-    var self = state.self;
-
-    if (t.isFunction(node) && !t.isArrowFunctionExpression(node)) {
-      // we need to call traverseLevel again so we're context aware
-      self.traverseLevel(node, false);
-      return context.skip();
-    }
-
-    if (t.isProperty(node, { method: true }) || t.isMethodDefinition(node)) {
-      // break on object methods
-      return context.skip();
-    }
-
-    var getThisReference = topLevel ?
-      // top level so `this` is the instance
-      t.thisExpression :
-      // not in the top level so we need to create a reference
-      self.getThisReference;
-
-    var callback = self.specHandle;
-    if (self.isLoose) callback = self.looseHandle;
-    return callback.call(self, getThisReference, node, parent);
-  }
-};
-
-/**
- * Description
- *
- * @param {Object} node
- * @param {Boolean} topLevel
- */
-
-ReplaceSupers.prototype.traverseLevel = function (node, topLevel) {
-  var state = { self: this, topLevel: topLevel };
-  traverse(node, visitor, this.scope, state);
-};
-
-/**
- * Description
- */
-
-ReplaceSupers.prototype.getThisReference = function () {
-  if (this.topLevelThisReference) {
-    return this.topLevelThisReference;
-  } else {
-    var ref = this.topLevelThisReference = this.file.generateUidIdentifier("this");
-    this.methodNode.value.body.body.unshift(t.variableDeclaration("var", [
-      t.variableDeclarator(this.topLevelThisReference, t.thisExpression())
-    ]));
-    return ref;
-  }
-};
-
 /**
  * Description
  *
@@ -166,7 +185,7 @@ ReplaceSupers.prototype.getThisReference = function () {
 
 ReplaceSupers.prototype.looseHandle = function (getThisReference, node, parent) {
   if (t.isIdentifier(node, { name: "super" })) {
-    return this.looseSuperProperty(this.methodNode, node, parent);
+    return this.getLooseSuperProperty(this.methodNode, node, parent);
   } else if (t.isCallExpression(node)) {
     var callee = node.callee;
     if (!t.isMemberExpression(callee)) return;
@@ -191,6 +210,7 @@ ReplaceSupers.prototype.specHandle = function (getThisReference, node, parent) {
   var property;
   var computed;
   var args;
+  var thisReference;
 
   if (t.isIdentifier(node, { name: "super" })) {
     if (!(t.isMemberExpression(parent) && !parent.computed && parent.property === node)) {
@@ -226,12 +246,19 @@ ReplaceSupers.prototype.specHandle = function (getThisReference, node, parent) {
     // super.name; -> _get(Object.getPrototypeOf(ClassName.prototype), "name", this);
     property = node.property;
     computed = node.computed;
+  } else if (t.isAssignmentExpression(node)) {
+    if (!t.isIdentifier(node.left.object, { name: "super" })) return;
+    if (methodNode.kind !== "set") return;
+
+    thisReference = getThisReference();
+    // super.name = "val"; -> _set(Object.getPrototypeOf(ClassName.prototype), "name", this);
+    return this.setSuperProperty(node.left.property, node.right, methodNode.static, node.left.computed, thisReference);
   }
 
   if (!property) return;
 
-  var thisReference = getThisReference();
-  var superProperty = this.superProperty(property, methodNode.static, computed, thisReference);
+  thisReference = getThisReference();
+  var superProperty = this.getSuperProperty(property, methodNode.static, computed, thisReference);
   if (args) {
     if (args.length === 1 && t.isSpreadElement(args[0])) {
       // super(...arguments);

lib/6to5/transformation/index.js

@@ -6,7 +6,7 @@ var Transformer = require("./transformer");
 var object      = require("../helpers/object");
 var File        = require("../file");
 var util        = require("../util");
-var _           = require("lodash");
+var each        = require("lodash/collection/each");
 
 function transform(code, opts) {
   var file = new File(opts);
@@ -14,7 +14,7 @@ function transform(code, opts) {
 }
 
 transform.fromAst = function (ast, code, opts) {
-  ast = util.normaliseAst(ast);
+  ast = util.normalizeAst(ast);
 
   var file = new File(opts);
   file.addCode(code);
@@ -64,7 +64,7 @@ transform.moduleFormatters = require("./modules");
 
 var rawTransformers = require("./transformers");
 
-_.each(rawTransformers, function (transformer, key) {
+each(rawTransformers, function (transformer, key) {
   var namespace = key.split(".")[0];
   transform.namespaces[namespace] = transform.namespaces[namespace] || [];
   transform.namespaces[namespace].push(key);

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

@@ -2,11 +2,10 @@
 
 module.exports = DefaultFormatter;
 
-var traverse = require("../../traverse");
 var object   = require("../../helpers/object");
 var util     = require("../../util");
 var t        = require("../../types");
-var _        = require("lodash");
+var extend   = require("lodash/object/extend");
 
 function DefaultFormatter(file) {
   this.file = file;
@@ -45,7 +44,7 @@ var exportsVisitor = {
       formatter.hasLocalImports = true;
 
       if (declar && t.isStatement(declar)) {
-        _.extend(formatter.localExports, t.getIds(declar, true));
+        extend(formatter.localExports, t.getBindingIdentifiers(declar));
       }
 
       if (!node.default) {
@@ -60,21 +59,21 @@ var exportsVisitor = {
 };
 
 DefaultFormatter.prototype.getLocalExports = function () {
-  traverse(this.file.ast, exportsVisitor, this.file.scope, this);
+  this.file.scope.traverse(this.file.ast, exportsVisitor, this);
 };
 
 var importsVisitor = {
   enter: function (node, parent, scope, context, formatter) {
     if (t.isImportDeclaration(node)) {
       formatter.hasLocalImports = true;
-      _.extend(formatter.localImports, t.getIds(node, true));
+      extend(formatter.localImports, t.getBindingIdentifiers(node));
       formatter.bumpImportOccurences(node);
     }
   }
 };
 
 DefaultFormatter.prototype.getLocalImports = function () {
-  traverse(this.file.ast, importsVisitor, this.file.scope, this);
+  this.file.scope.traverse(this.file.ast, importsVisitor, this);
 };
 
 var remapVisitor = {
@@ -116,7 +115,7 @@ var remapVisitor = {
 
 DefaultFormatter.prototype.remapAssignments = function () {
   if (this.hasLocalImports) {
-    traverse(this.file.ast, remapVisitor, this.file.scope, this);
+    this.file.scope.traverse(this.file.ast, remapVisitor, this);
   }
 };
 
@@ -147,7 +146,7 @@ DefaultFormatter.prototype.remapExportAssignment = function (node) {
 DefaultFormatter.prototype.isLocalReference = function (node, scope) {
   var localExports = this.localExports;
   var name = node.name;
-  return t.isIdentifier(node) && localExports[name] && localExports[name] === scope.get(name, true);
+  return t.isIdentifier(node) && localExports[name] && localExports[name] === scope.getBinding(name);
 };
 
 DefaultFormatter.prototype.getModuleName = function () {
@@ -171,12 +170,12 @@ DefaultFormatter.prototype.getModuleName = function () {
 
   if (!opts.keepModuleIdExtensions) {
     // remove extension
-    filenameRelative = filenameRelative.replace(/\.(.*?)$/, "");
+    filenameRelative = filenameRelative.replace(/\.(\w*?)$/, "");
   }
 
   moduleName += filenameRelative;
 
-  // normalise path separators
+  // normalize path separators
   moduleName = moduleName.replace(/\\/g, "/");
 
   return moduleName;
@@ -212,6 +211,12 @@ DefaultFormatter.prototype.getExternalReference = function (node, nodes) {
   }
 };
 
+DefaultFormatter.prototype.checkExportIdentifier = function (node) {
+  if (t.isIdentifier(node, { name: "__esModule" })) {
+    throw this.file.errorWithNode(node, "Illegal export __esModule - this is used internally for CommonJS interop");
+  }
+};
+
 DefaultFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
   var inherits = false;
   if (node.specifiers.length === 1) inherits = node;
@@ -224,7 +229,7 @@ DefaultFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
       nodes.push(this.buildExportsWildcard(ref, node));
     } else {
       if (t.isSpecifierDefault(specifier) && !this.noInteropRequire) {
-        // importing a default so we need to normalise it
+        // importing a default so we need to normalize it
         ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
       } else {
         ref = t.memberExpression(ref, t.getSpecifierId(specifier));
@@ -251,6 +256,7 @@ DefaultFormatter.prototype.buildExportsWildcard = function (objectIdentifier) {
 };
 
 DefaultFormatter.prototype.buildExportsAssignment = function (id, init) {
+  this.checkExportIdentifier(id);
   return util.template("exports-assign", {
     VALUE: init,
     KEY:   id

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

@@ -6,7 +6,8 @@ var DefaultFormatter = require("./_default");
 var CommonFormatter  = require("./common");
 var util             = require("../../util");
 var t                = require("../../types");
-var _                = require("lodash");
+var contains         = require("lodash/collection/contains");
+var values           = require("lodash/object/values");
 
 function AMDFormatter() {
   CommonFormatter.apply(this, arguments);
@@ -14,6 +15,8 @@ function AMDFormatter() {
 
 util.inherits(AMDFormatter, DefaultFormatter);
 
+AMDFormatter.prototype.init = CommonFormatter.prototype.init;
+
 AMDFormatter.prototype.buildDependencyLiterals = function () {
   var names = [];
   for (var name in this.ids) {
@@ -39,7 +42,7 @@ AMDFormatter.prototype.transform = function (ast) {
 
   // build up define container
 
-  var params = _.values(this.ids);
+  var params = values(this.ids);
   if (this.passModuleArg) params.unshift(t.identifier("module"));
   params.unshift(t.identifier("exports"));
 
@@ -79,10 +82,9 @@ AMDFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
   var key = t.getSpecifierName(specifier);
   var ref = this.getExternalReference(node);
 
-  if (_.contains(this.file.dynamicImported, node)) {
+  if (contains(this.file.dynamicImported, node)) {
     // Prevent unnecessary renaming of dynamic imports.
-    this.ids[node.source.value] = key;
-    return;
+    this.ids[node.source.value] = ref;
   } else if (t.isImportBatchSpecifier(specifier)) {
     // import * as bar from "foo";
   } else if (t.isSpecifierDefault(specifier) && !this.noInteropRequire) {

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

@@ -3,20 +3,22 @@
 module.exports = CommonJSFormatter;
 
 var DefaultFormatter = require("./_default");
+var contains         = require("lodash/collection/contains");
 var util             = require("../../util");
 var t                = require("../../types");
-var _                = require("lodash");
 
-function CommonJSFormatter(file) {
+function CommonJSFormatter() {
   DefaultFormatter.apply(this, arguments);
-
-  if (this.hasNonDefaultExports) {
-    file.ast.program.body.push(util.template("exports-module-declaration", true));
-  }
 }
 
 util.inherits(CommonJSFormatter, DefaultFormatter);
 
+CommonJSFormatter.prototype.init = function () {
+  if (this.hasNonDefaultExports) {
+    this.file.ast.program.body.push(util.template("exports-module-declaration", true));
+  }
+};
+
 CommonJSFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
   var variableName = t.getSpecifierName(specifier);
 
@@ -24,7 +26,7 @@ CommonJSFormatter.prototype.importSpecifier = function (specifier, node, nodes)
 
   // import foo from "foo";
   if (t.isSpecifierDefault(specifier)) {
-    if (!_.contains(this.file.dynamicImported, node)) {
+    if (!contains(this.file.dynamicImported, node)) {
       ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
     }
     nodes.push(t.variableDeclaration("var", [t.variableDeclarator(variableName, ref)]));

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

@@ -5,10 +5,11 @@ module.exports = SystemFormatter;
 var DefaultFormatter = require("./_default");
 var AMDFormatter     = require("./amd");
 var useStrict        = require("../helpers/use-strict");
-var traverse         = require("../../traverse");
 var util             = require("../../util");
 var t                = require("../../types");
-var _                = require("lodash");
+var last             = require("lodash/array/last");
+var each             = require("lodash/collection/each");
+var map              = require("lodash/collection/map");
 
 function SystemFormatter(file) {
   this.exportIdentifier = file.generateUidIdentifier("export");
@@ -19,6 +20,8 @@ function SystemFormatter(file) {
 
 util.inherits(SystemFormatter, AMDFormatter);
 
+SystemFormatter.prototype.init = function () {};
+
 SystemFormatter.prototype._addImportSource = function (node, exportNode) {
   node._importSource = exportNode.source && exportNode.source.value;
   return node;
@@ -61,14 +64,14 @@ SystemFormatter.prototype.buildExportCall = function (id, init, isStatement) {
 
 SystemFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
   AMDFormatter.prototype.importSpecifier.apply(this, arguments);
-  this._addImportSource(_.last(nodes), node);
+  this._addImportSource(last(nodes), node);
 };
 
 var runnerSettersVisitor = {
   enter: function (node, parent, scope, context, state) {
     if (node._importSource === state.source) {
       if (t.isVariableDeclaration(node)) {
-        _.each(node.declarations, function (declar) {
+        each(node.declarations, function (declar) {
           state.hoistDeclarators.push(t.variableDeclarator(declar.id));
           state.nodes.push(t.expressionStatement(
             t.assignmentExpression("=", declar.id, declar.init)
@@ -86,14 +89,14 @@ var runnerSettersVisitor = {
 SystemFormatter.prototype.buildRunnerSetters = function (block, hoistDeclarators) {
   var scope = this.file.scope;
 
-  return t.arrayExpression(_.map(this.ids, function (uid, source) {
+  return t.arrayExpression(map(this.ids, function (uid, source) {
     var state = {
       source:           source,
       nodes:            [],
       hoistDeclarators: hoistDeclarators
     };
 
-    traverse(block, runnerSettersVisitor, scope, state);
+    scope.traverse(block, runnerSettersVisitor, state);
 
     return t.functionExpression(null, [uid], t.blockStatement(state.nodes));
   }));
@@ -178,7 +181,7 @@ SystemFormatter.prototype.transform = function (ast) {
   var returnStatement = handlerBody.pop();
 
   // hoist up all variable declarations
-  traverse(block, hoistVariablesVisitor, this.file.scope, hoistDeclarators);
+  this.file.scope.traverse(block, hoistVariablesVisitor, hoistDeclarators);
 
   if (hoistDeclarators.length) {
     var hoistDeclar = t.variableDeclaration("var", hoistDeclarators);
@@ -187,7 +190,7 @@ SystemFormatter.prototype.transform = function (ast) {
   }
 
   // hoist up function declarations for circular references
-  traverse(block, hoistFunctionsVisitor, this.file.scope, handlerBody);
+  this.file.scope.traverse(block, hoistFunctionsVisitor, handlerBody);
 
   handlerBody.push(returnStatement);
 

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

@@ -5,7 +5,7 @@ module.exports = UMDFormatter;
 var AMDFormatter = require("./amd");
 var util         = require("../../util");
 var t            = require("../../types");
-var _            = require("lodash");
+var values       = require("lodash/object/values");
 
 function UMDFormatter() {
   AMDFormatter.apply(this, arguments);
@@ -26,7 +26,7 @@ UMDFormatter.prototype.transform = function (ast) {
 
   // factory
 
-  var ids  = _.values(this.ids);
+  var ids  = values(this.ids);
   var args = [t.identifier("exports")];
   if (this.passModuleArg) args.push(t.identifier("module"));
   args = args.concat(ids);

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

@@ -3,12 +3,12 @@
     var gen = fn.apply(this, arguments);
 
     return new Promise(function (resolve, reject) {
-      var callNext = step.bind(gen.next);
-      var callThrow = step.bind(gen.throw);
+      var callNext = step.bind(null, "next");
+      var callThrow = step.bind(null, "throw");
 
-      function step(arg) {
+      function step(key, arg) {
         try {
-          var info = this(arg);
+          var info = gen[key](arg);
           var value = info.value;
         } catch (error) {
           reject(error);

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

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

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

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

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

@@ -1,4 +1,4 @@
-(function (target) {
+Object.assign || (function (target) {
   for (var i = 1; i < arguments.length; i++) {
     var source = arguments[i];
     for (var key in source) {

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

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

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

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

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

@@ -0,0 +1,24 @@
+(function set(object, property, value, receiver) {
+  var desc = Object.getOwnPropertyDescriptor(object, property);
+
+  if (desc === undefined) {
+    var parent = Object.getPrototypeOf(object);
+
+    if (parent === null) {
+      return;
+    } else {
+      return set(parent, property, value, receiver);
+    }
+  } else if ("value" in desc && desc.writable) {
+    desc.value = value;
+    return;
+  } else {
+    var setter = desc.set;
+
+    if (setter === undefined) {
+      return;
+    }
+
+    return setter.call(receiver, value);
+  }
+});

lib/6to5/transformation/transformer-pass.js

@@ -1,7 +1,7 @@
 module.exports = TransformerPass;
 
-var traverse = require("../traverse");
-var _        = require("lodash");
+var util     = require("../util");
+var contains = require("lodash/collection/contains");
 
 /**
  * This class is responsible for traversing over the provided `File`s
@@ -10,11 +10,14 @@ var _        = require("lodash");
 
 function TransformerPass(file, transformer) {
   this.transformer = transformer;
+  this.shouldRun   = !transformer.check;
   this.handlers    = transformer.handlers;
   this.file        = file;
 }
 
 TransformerPass.prototype.astRun = function (key) {
+  if (!this.shouldRun) return;
+
   var handlers = this.handlers;
   var file = this.file;
 
@@ -28,21 +31,39 @@ TransformerPass.prototype.canRun = function () {
 
   var opts = this.file.opts;
   var key  = transformer.key;
+
+  // internal
   if (key[0] === "_") return true;
 
+  // blacklist
   var blacklist = opts.blacklist;
-  if (blacklist.length && _.contains(blacklist, key)) return false;
+  if (blacklist.length && contains(blacklist, key)) return false;
 
+  // whitelist
   var whitelist = opts.whitelist;
-  if (whitelist.length && !_.contains(whitelist, key)) return false;
+  if (whitelist.length && !contains(whitelist, key)) return false;
 
-  if (transformer.optional && !_.contains(opts.optional, key)) return false;
+  // optional
+  if (transformer.optional && !contains(opts.optional, key)) return false;
 
+  // experimental
   if (transformer.experimental && !opts.experimental) return false;
 
+  // playground
+  if (transformer.playground && !opts.playground) return false;
+
   return true;
 };
 
+TransformerPass.prototype.checkNode = function (node) {
+  var check = this.transformer.check;
+  if (check) {
+    return this.shouldRun = check(node);
+  } else {
+    return true;
+  }
+};
+
 var transformVisitor = {
   enter: function (node, parent, scope, context, state) {
     var fns = state.handlers[node.type];
@@ -58,12 +79,16 @@ var transformVisitor = {
 };
 
 TransformerPass.prototype.transform = function () {
+  if (!this.shouldRun) return;
+
   var file = this.file;
 
+  util.debug(file.opts.filename + ": Running transformer " + this.transformer.key);
+
   this.astRun("before");
 
   var state = { file: file, handlers: this.handlers, pass: this };
-  traverse(file.ast, transformVisitor, file.scope, state);
+  file.scope.traverse(file.ast, transformVisitor, state);
 
   this.astRun("after");
 };

lib/6to5/transformation/transformer.js

@@ -3,8 +3,10 @@
 module.exports = Transformer;
 
 var TransformerPass = require("./transformer-pass");
-var t               = require("../types");
-var _               = require("lodash");
+var isFunction      = require("lodash/lang/isFunction");
+var traverse        = require("../traverse");
+var isObject        = require("lodash/lang/isObject");
+var each            = require("lodash/collection/each");
 
 /**
  * This is the class responsible for normalising a transformers handlers
@@ -14,43 +16,42 @@ var _               = require("lodash");
 
 function Transformer(key, transformer, opts) {
   this.manipulateOptions = transformer.manipulateOptions;
-  this.experimental      = !!transformer.experimental;
-  this.secondPass        = !!transformer.secondPass;
-  this.optional          = !!transformer.optional;
-  this.handlers          = this.normalise(transformer);
-  this.opts              = opts || {};
-  this.key               = key;
+  this.check             = transformer.check;
+
+  this.experimental = !!transformer.experimental;
+  this.playground   = !!transformer.playground;
+  this.secondPass   = !!transformer.secondPass;
+  this.optional     = !!transformer.optional;
+
+  this.handlers = this.normalize(transformer);
+  this.opts     = opts || {};
+  this.key      = key;
 }
 
-Transformer.prototype.normalise = function (transformer) {
+Transformer.prototype.normalize = function (transformer) {
   var self = this;
 
-  if (_.isFunction(transformer)) {
+  if (isFunction(transformer)) {
     transformer = { ast: transformer };
   }
 
-  _.each(transformer, function (fns, type) {
+  traverse.explode(transformer);
+
+  each(transformer, function (fns, type) {
     // hidden property
     if (type[0] === "_") {
       self[type] = fns;
       return;
     }
 
-    if (_.isFunction(fns)) fns = { enter: fns };
+    if (isFunction(fns)) fns = { enter: fns };
 
-    if (!_.isObject(fns)) return;
+    if (!isObject(fns)) return;
 
-    if (!fns.enter) fns.enter = _.noop;
-    if (!fns.exit) fns.exit = _.noop;
+    if (!fns.enter) fns.enter = function () { };
+    if (!fns.exit) fns.exit = function () { };
 
     transformer[type] = fns;
-
-    var aliases = t.FLIPPED_ALIAS_KEYS[type];
-    if (aliases) {
-      _.each(aliases, function (alias) {
-        transformer[alias] = fns;
-      });
-    }
   });
 
   return transformer;

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

@@ -12,7 +12,8 @@
   "generatorComprehension": "es7.comprehensions",
   "arrowFunctions": "es6.arrowFunctions",
   "classes": "es6.classes",
-  "objectSpread": "es7.objectSpread",
+  "objectSpread": "es7.objectRestSpread",
+  "es7.objectSpread": "es7.objectRestSpread",
   "exponentiationOperator": "es7.exponentiationOperator",
   "spread": "es6.spread",
   "templateLiterals": "es6.templateLiterals",

lib/6to5/transformation/transformers/es5/properties.mutators.js

@@ -1,7 +1,11 @@
 "use strict";
 
-var util = require("../../../util");
-var t    = require("../../../types");
+var defineMap = require("../../helpers/define-map");
+var t         = require("../../../types");
+
+exports.check = function (node) {
+  return t.isProperty(node) && (node.kind === "get" || node.kind === "set");
+};
 
 exports.ObjectExpression = function (node) {
   var mutatorMap = {};
@@ -10,7 +14,7 @@ exports.ObjectExpression = function (node) {
   node.properties = node.properties.filter(function (prop) {
     if (prop.kind === "get" || prop.kind === "set") {
       hasAny = true;
-      util.pushMutatorMap(mutatorMap, prop.key, prop.kind, prop.computed, prop.value);
+      defineMap.push(mutatorMap, prop.key, prop.kind, prop.computed, prop.value);
       return false;
     } else {
       return true;
@@ -21,6 +25,6 @@ exports.ObjectExpression = function (node) {
 
   return t.callExpression(
     t.memberExpression(t.identifier("Object"), t.identifier("defineProperties")),
-    [node, util.buildDefineProperties(mutatorMap)]
+    [node, defineMap.build(mutatorMap)]
   );
 };

lib/6to5/transformation/transformers/es6/arrow-functions.js

@@ -2,6 +2,8 @@
 
 var t = require("../../../types");
 
+exports.check = t.isArrowFunctionExpression;
+
 exports.ArrowFunctionExpression = function (node) {
   t.ensureBlock(node);
 

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

@@ -1,7 +1,6 @@
 "use strict";
 
-var traverse = require("../../../traverse");
-var t        = require("../../../types");
+var t = require("../../../types");
 
 var visitor = {
   enter: function (node, parent, scope, context, state) {
@@ -11,7 +10,7 @@ var visitor = {
     if (!declared) return;
 
     // declared node is different in this scope
-    if (scope.get(node.name, true) !== declared) return;
+    if (scope.getBinding(node.name) !== declared) return;
 
     var declaredLoc  = declared.loc;
     var referenceLoc = node.loc;
@@ -46,5 +45,5 @@ exports.BlockStatement = function (node, parent, scope, context, file) {
     file:    file
   };
 
-  traverse(node, visitor, scope, state);
+  scope.traverse(node, visitor, state);
 };

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

@@ -4,7 +4,12 @@ var traverse = require("../../../traverse");
 var object   = require("../../../helpers/object");
 var util     = require("../../../util");
 var t        = require("../../../types");
-var _        = require("lodash");
+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;
@@ -28,7 +33,7 @@ var isVar = function (node, parent) {
   return t.isVariableDeclaration(node, { kind: "var" }) && !isLet(node, parent);
 };
 
-var standardiseLets = function (declars) {
+var standardizeLets = function (declars) {
   for (var i = 0; i < declars.length; i++) {
     delete declars[i]._let;
   }
@@ -44,26 +49,15 @@ exports.Loop = function (node, parent, scope, context, file) {
     t.ensureBlock(node);
     node.body._letDeclarators = [init];
   }
-
-  if (t.isLabeledStatement(parent)) {
-    // set label so `run` has access to it
-    node.label = parent.label;
-  }
-
-  var letScoping = new LetScoping(node, node.body, parent, scope, file);
-  letScoping.run();
-
-  if (node.label && !t.isLabeledStatement(parent)) {
-    // we've been given a label so let's wrap ourselves
-    return t.labeledStatement(node.label, node);
-  }
+  var blockScoping = new BlockScoping(node, node.body, parent, scope, file);
+  blockScoping.run();
 };
 
 exports.Program =
 exports.BlockStatement = function (block, parent, scope, context, file) {
   if (!t.isLoop(parent)) {
-    var letScoping = new LetScoping(false, block, parent, scope, file);
-    letScoping.run();
+    var blockScoping = new BlockScoping(false, block, parent, scope, file);
+    blockScoping.run();
   }
 };
 
@@ -77,7 +71,7 @@ exports.BlockStatement = function (block, parent, scope, context, file) {
  * @param {File} file
  */
 
-function LetScoping(loopParent, block, parent, scope, file) {
+function BlockScoping(loopParent, block, parent, scope, file) {
   this.loopParent = loopParent;
   this.parent     = parent;
   this.scope      = scope;
@@ -94,7 +88,7 @@ function LetScoping(loopParent, block, parent, scope, file) {
  * Start the ball rolling.
  */
 
-LetScoping.prototype.run = function () {
+BlockScoping.prototype.run = function () {
   var block = this.block;
   if (block._letDone) return;
   block._letDone = true;
@@ -120,11 +114,11 @@ function replace(node, parent, scope, context, remaps) {
   var remap = remaps[node.name];
   if (!remap) return;
 
-  var own = scope.get(node.name, true);
-  if (own === remap.node) {
+  var ownBinding = scope.getBinding(node.name);
+  if (ownBinding === remap.binding) {
     node.name = remap.uid;
   } else {
-    // scope already has it's own declaration that doesn't
+    // scope already has it's own binding that doesn't
     // match the one we have a stored replacement for
     if (context) context.skip();
   }
@@ -136,14 +130,14 @@ var replaceVisitor = {
 
 function traverseReplace(node, parent, scope, remaps) {
   replace(node, parent, scope, null, remaps);
-  traverse(node, replaceVisitor, scope, remaps);
+  scope.traverse(node, replaceVisitor, remaps);
 }
 
 /**
  * Description
  */
 
-LetScoping.prototype.remap = function () {
+BlockScoping.prototype.remap = function () {
   var hasRemaps = false;
   var letRefs   = this.letReferences;
   var scope     = this.scope;
@@ -159,13 +153,13 @@ LetScoping.prototype.remap = function () {
     // this is the defining identifier of a declaration
     var ref = letRefs[key];
 
-    if (scope.parentHas(key)) {
+    if (scope.parentHasReference(key)) {
       var uid = scope.generateUidIdentifier(ref.name).name;
       ref.name = uid;
 
       hasRemaps = true;
       remaps[key] = remaps[uid] = {
-        node: ref,
+        binding: ref,
         uid: uid
       };
     }
@@ -182,14 +176,14 @@ LetScoping.prototype.remap = function () {
     traverseReplace(loopParent.update, loopParent, scope, remaps);
   }
 
-  traverse(this.block, replaceVisitor, scope, remaps);
+  scope.traverse(this.block, replaceVisitor, remaps);
 };
 
 /**
  * Description
  */
 
-LetScoping.prototype.needsClosure = function () {
+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
@@ -200,7 +194,7 @@ LetScoping.prototype.needsClosure = function () {
   this.hoistVarDeclarations();
 
   // turn outsideLetReferences into an array
-  var params = _.values(this.outsideLetReferences);
+  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));
@@ -237,7 +231,7 @@ var letReferenceFunctionVisitor = {
 
     // this scope has a variable with the same name so it couldn't belong
     // to our let scope
-    if (scope.hasOwn(node.name, true)) return;
+    if (scope.hasOwnBinding(node.name)) return;
 
     // not a part of our scope
     if (!state.letReferences[node.name]) return;
@@ -249,7 +243,7 @@ var letReferenceFunctionVisitor = {
 var letReferenceBlockVisitor = {
   enter: function (node, parent, scope, context, state) {
     if (t.isFunction(node)) {
-      traverse(node, letReferenceFunctionVisitor, scope, state);
+      scope.traverse(node, letReferenceFunctionVisitor, state);
       return context.skip();
     }
   }
@@ -259,7 +253,7 @@ var letReferenceBlockVisitor = {
  * Description
  */
 
-LetScoping.prototype.getLetReferences = function () {
+BlockScoping.prototype.getLetReferences = function () {
   var block = this.block;
 
   var declarators = block._letDeclarators || [];
@@ -268,7 +262,7 @@ LetScoping.prototype.getLetReferences = function () {
   //
   for (var i = 0; i < declarators.length; i++) {
     declar = declarators[i];
-    _.extend(this.outsideLetReferences, t.getIds(declar, true));
+    extend(this.outsideLetReferences, t.getBindingIdentifiers(declar));
   }
 
   //
@@ -284,8 +278,8 @@ LetScoping.prototype.getLetReferences = function () {
   //
   for (i = 0; i < declarators.length; i++) {
     declar = declarators[i];
-    var keys = t.getIds(declar, true);
-    _.extend(this.letReferences, keys);
+    var keys = t.getBindingIdentifiers(declar);
+    extend(this.letReferences, keys);
     this.hasLetReferences = true;
   }
 
@@ -293,7 +287,7 @@ LetScoping.prototype.getLetReferences = function () {
   if (!this.hasLetReferences) return;
 
   // set let references to plain var references
-  standardiseLets(declarators);
+  standardizeLets(declarators);
 
   var state = {
     letReferences: this.letReferences,
@@ -302,39 +296,76 @@ LetScoping.prototype.getLetReferences = function () {
 
   // traverse through this block, stopping on functions and checking if they
   // contain any local let references
-  traverse(this.block, letReferenceBlockVisitor, this.scope, state);
+  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, context, 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 context.skip();
     }
 
-    if (node && !node.label && state.isLoop) {
-      if (t.isBreakStatement(node)) {
-        if (t.isSwitchCase(parent)) return;
+    var loopText = loopNodeTo(node);
 
-        state.hasBreak = true;
-        replace = t.returnStatement(t.literal("break"));
-      } else if (t.isContinueStatement(node)) {
-        state.hasContinue = true;
-        replace = t.returnStatement(t.literal("continue"));
+    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.returnStatement(t.objectExpression([
+      replace = t.objectExpression([
         t.property("init", t.identifier("v"), node.argument || t.identifier("undefined"))
-      ]));
+      ]);
     }
 
-    if (replace) return t.inherits(replace, node);
+    if (replace) {
+      replace = t.returnStatement(replace);
+      return t.inherits(replace, node);
+    }
+  }
+};
+
+var loopLabelVisitor = {
+  enter: function (node, parent, scope, context, state) {
+    if (t.isLabeledStatement(node)) {
+      state.innerLabels.push(node.label.name);
+    }
   }
 };
 
@@ -347,15 +378,19 @@ var loopVisitor = {
  * @returns {Object}
  */
 
-LetScoping.prototype.checkLoop = function () {
+BlockScoping.prototype.checkLoop = function () {
   var state = {
-    hasContinue: false,
-    hasReturn:   false,
-    hasBreak:    false,
-    isLoop:      !!this.loopParent
+    hasBreakContinue: false,
+    ignoreLabeless:   false,
+    innerLabels:      [],
+    hasReturn:        false,
+    isLoop:           !!this.loopParent,
+    map:              {}
   };
 
-  traverse(this.block, loopVisitor, this.scope, state);
+  this.scope.traverse(this.block, loopLabelVisitor, state);
+  this.scope.traverse(this.block, loopVisitor, state);
+
   return state;
 };
 
@@ -382,7 +417,7 @@ var hoistVarDeclarationsVisitor = {
  * once we wrap everything in a closure.
  */
 
-LetScoping.prototype.hoistVarDeclarations = function () {
+BlockScoping.prototype.hoistVarDeclarations = function () {
   traverse(this.block, hoistVarDeclarationsVisitor, this.scope, this);
 };
 
@@ -394,7 +429,7 @@ LetScoping.prototype.hoistVarDeclarations = function () {
  * @returns {Array}
  */
 
-LetScoping.prototype.pushDeclar = function (node) {
+BlockScoping.prototype.pushDeclar = function (node) {
   this.body.push(t.variableDeclaration(node.kind, node.declarations.map(function (declar) {
     return t.variableDeclarator(declar.id);
   })));
@@ -419,9 +454,9 @@ LetScoping.prototype.pushDeclar = function (node) {
  * @param {Node} call CallExpression
  */
 
-LetScoping.prototype.build = function (ret, call) {
+BlockScoping.prototype.build = function (ret, call) {
   var has = this.has;
-  if (has.hasReturn || has.hasBreak || has.hasContinue) {
+  if (has.hasReturn || has.hasBreakContinue) {
     this.buildHas(ret, call);
   } else {
     this.body.push(t.expressionStatement(call));
@@ -435,7 +470,7 @@ LetScoping.prototype.build = function (ret, call) {
  * @param {Node} call CallExpression
  */
 
-LetScoping.prototype.buildHas = function (ret, call) {
+BlockScoping.prototype.buildHas = function (ret, call) {
   var body = this.body;
 
   body.push(t.variableDeclaration("var", [
@@ -454,22 +489,14 @@ LetScoping.prototype.buildHas = function (ret, call) {
     });
   }
 
-  if (has.hasBreak || has.hasContinue) {
+  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.");
     }
 
-    // ensure that the parent has a label as we're building a switch and we
-    // need to be able to access it
-    var label = loopParent.label = loopParent.label || this.scope.generateUidIdentifier("loop");
-
-    if (has.hasBreak) {
-      cases.push(t.switchCase(t.literal("break"), [t.breakStatement(label)]));
-    }
-
-    if (has.hasContinue) {
-      cases.push(t.switchCase(t.literal("continue"), [t.continueStatement(label)]));
+    for (var key in has.map) {
+      cases.push(t.switchCase(t.literal(key), [has.map[key]]));
     }
 
     if (has.hasReturn) {

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

@@ -2,9 +2,12 @@
 
 var ReplaceSupers = require("../../helpers/replace-supers");
 var nameMethod    = require("../../helpers/name-method");
+var defineMap     = require("../../helpers/define-map");
 var util          = require("../../../util");
 var t             = require("../../../types");
 
+exports.check = t.isClass;
+
 exports.ClassDeclaration = function (node, parent, scope, context, file) {
   return new Class(node, file, scope, true).run();
 };
@@ -47,7 +50,8 @@ function Class(node, file, scope, isStatement) {
   this.staticMutatorMap   = {};
   this.hasConstructor     = false;
   this.className          = node.id || scope.generateUidIdentifier("class");
-  this.superName          = node.superClass;
+  this.superName          = node.superClass || t.identifier("Function");
+  this.hasSuper           = !!node.superClass;
   this.isLoose            = file.isLoose("es6.classes");
 }
 
@@ -66,12 +70,19 @@ Class.prototype.run = function () {
 
   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, [], t.blockStatement([]));
+    constructor = t.functionDeclaration(className, [], constructorBody);
     body.push(constructor);
   } else {
-    constructor = t.functionExpression(null, [], t.blockStatement([]));
+    constructor = t.functionExpression(null, [], constructorBody);
     body.push(t.variableDeclaration("var", [
       t.variableDeclarator(className, constructor)
     ]));
@@ -83,7 +94,7 @@ Class.prototype.run = function () {
 
   //
 
-  if (superName) {
+  if (this.hasSuper) {
     closureArgs.push(superName);
 
     if (!t.isIdentifier(superName)) {
@@ -159,11 +170,10 @@ Class.prototype.buildBody = function () {
   }
 
   // we have no constructor, we have a super, and the super doesn't appear to be falsy
-  if (!this.hasConstructor && superName && !t.isFalsyExpression(superName)) {
-    var defaultConstructorTemplate = "class-super-constructor-call";
-    if (this.isLoose) defaultConstructorTemplate += "-loose";
-
-    constructor.body.body.push(util.template(defaultConstructorTemplate, {
+  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));
@@ -173,11 +183,11 @@ Class.prototype.buildBody = function () {
   var staticProps;
 
   if (this.hasInstanceMutators) {
-    instanceProps = util.buildDefineProperties(this.instanceMutatorMap);
+    instanceProps = defineMap.build(this.instanceMutatorMap);
   }
 
   if (this.hasStaticMutators) {
-    staticProps = util.buildDefineProperties(this.staticMutatorMap);
+    staticProps = defineMap.build(this.staticMutatorMap);
   }
 
   if (instanceProps || staticProps) {
@@ -230,7 +240,8 @@ Class.prototype.pushMethod = function (node) {
     this.hasInstanceMutators = true;
   }
 
-  util.pushMutatorMap(mutatorMap, methodName, kind, node.computed, node);
+  defineMap.push(mutatorMap, methodName, kind, node.computed, node);
+  defineMap.push(mutatorMap, methodName, "enumerable", node.computed, false);
 };
 
 /**
@@ -254,5 +265,5 @@ Class.prototype.pushConstructor = function (method) {
 
   construct._ignoreUserWhitespace = true;
   construct.params                = fn.params;
-  construct.body                  = fn.body;
+  construct.body.body             = construct.body.body.concat(fn.body.body);
 };

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

@@ -1,12 +1,15 @@
 "use strict";
 
-var traverse = require("../../../traverse");
-var t        = require("../../../types");
+var t = require("../../../types");
+
+exports.check = function (node) {
+  return t.isVariableDeclaration(node, { kind: "const" });
+};
 
 var visitor = {
   enter: function (node, parent, scope, context, state) {
-    if (t.isDeclaration(node) || t.isAssignmentExpression(node)) {
-      var ids = t.getIds(node, true);
+    if (t.isAssignmentExpression(node) || t.isUpdateExpression(node)) {
+      var ids = t.getBindingIdentifiers(node);
 
       for (var key in ids) {
         var id = ids[key];
@@ -21,6 +24,9 @@ var visitor = {
         // constant so we can just ignore it
         if (id === constant) continue;
 
+        var localBinding = scope.getBinding(key);
+        if (localBinding !== constant) continue;
+
         throw state.file.errorWithNode(id, key + " is read-only");
       }
     } else if (t.isScope(node)) {
@@ -30,8 +36,8 @@ var visitor = {
 };
 
 exports.Scope = function (node, parent, scope, context, file) {
-  traverse(node, visitor, scope, {
-    constants: scope.getAllOfKind("const"),
+  scope.traverse(node, visitor, {
+    constants: scope.getAllDeclarationsOfKind("const"),
     file:      file
   });
 };

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

@@ -1,11 +1,20 @@
 "use strict";
 
-// TODO: Clean up
-
 var t = require("../../../types");
 
-var buildVariableAssign = function (opts, id, init) {
-  var op = opts.operator;
+exports.check = t.isPattern;
+
+function Destructuring(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;
+}
+
+Destructuring.prototype.buildVariableAssignment = function (id, init) {
+  var op = this.operator;
   if (t.isMemberExpression(id)) op = "=";
 
   var node;
@@ -13,45 +22,46 @@ var buildVariableAssign = function (opts, id, init) {
   if (op) {
     node = t.expressionStatement(t.assignmentExpression(op, id, init));
   } else {
-    node = t.variableDeclaration(opts.kind, [
+    node = t.variableDeclaration(this.kind, [
       t.variableDeclarator(id, init)
     ]);
   }
 
-  node._blockHoist = opts.blockHoist;
+  node._blockHoist = this.blockHoist;
 
   return node;
 };
 
-var buildVariableDeclar = function (opts, id, init) {
+Destructuring.prototype.buildVariableDeclaration = function (id, init) {
   var declar = t.variableDeclaration("var", [
     t.variableDeclarator(id, init)
   ]);
-  declar._blockHoist = opts.blockHoist;
+  declar._blockHoist = this.blockHoist;
   return declar;
 };
 
-var push = function (opts, nodes, elem, parentId) {
+Destructuring.prototype.push = function (elem, parentId) {
   if (t.isObjectPattern(elem)) {
-    pushObjectPattern(opts, nodes, elem, parentId);
+    this.pushObjectPattern(elem, parentId);
   } else if (t.isArrayPattern(elem)) {
-    pushArrayPattern(opts, nodes, elem, parentId);
+    this.pushArrayPattern(elem, parentId);
   } else if (t.isAssignmentPattern(elem)) {
-    pushAssignmentPattern(opts, nodes, elem, parentId);
+    this.pushAssignmentPattern(elem, parentId);
   } else {
-    nodes.push(buildVariableAssign(opts, elem, parentId));
+    this.nodes.push(this.buildVariableAssignment(elem, parentId));
   }
 };
 
-var pushAssignmentPattern = function (opts, nodes, pattern, parentId) {
-  var tempParentId = opts.scope.generateUidBasedOnNode(parentId, opts.file);
+Destructuring.prototype.pushAssignmentPattern = function (pattern, parentId) {
+  var tempParentId = this.scope.generateUidBasedOnNode(parentId);
 
-  nodes.push(t.variableDeclaration("var", [
+  var declar = t.variableDeclaration("var", [
     t.variableDeclarator(tempParentId, parentId)
-  ]));
+  ]);
+  declar._blockHoist = this.blockHoist;
+  this.nodes.push(declar);
 
-  nodes.push(buildVariableAssign(
-    opts,
+  this.nodes.push(this.buildVariableAssignment(
     pattern.left,
     t.conditionalExpression(
       t.binaryExpression("===", tempParentId, t.identifier("undefined")),
@@ -61,72 +71,88 @@ var pushAssignmentPattern = function (opts, nodes, pattern, parentId) {
   ));
 };
 
-var pushObjectPattern = function (opts, nodes, pattern, parentId) {
+Destructuring.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));
+};
+
+Destructuring.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));
+  }
+};
+
+Destructuring.prototype.pushObjectPattern = function (pattern, parentId) {
+  if (!pattern.properties.length) {
+    this.nodes.push(t.expressionStatement(
+      t.callExpression(this.file.addHelper("object-destructuring-empty"), [parentId])
+    ));
+  }
+
   for (var i = 0; i < pattern.properties.length; i++) {
     var prop = pattern.properties[i];
     if (t.isSpreadProperty(prop)) {
-      // 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(opts.file.addHelper("object-without-properties"), [parentId, keys]);
-      nodes.push(buildVariableAssign(opts, prop.argument, value));
+      this.pushObjectSpread(pattern, parentId, prop, i);
     } else {
-      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)) {
-        push(opts, nodes, pattern2, patternId2);
-      } else {
-        nodes.push(buildVariableAssign(opts, pattern2, patternId2));
-      }
+      this.pushObjectProperty(prop, parentId);
     }
   }
 };
 
-var pushArrayPattern = function (opts, nodes, pattern, parentId) {
-  if (!pattern.elements) return;
-
-  var i;
-
-  var hasRest = false;
-  for (i = 0; i < pattern.elements.length; i++) {
+var hasRest = function (pattern) {
+  for (var i = 0; i < pattern.elements.length; i++) {
     if (t.isRestElement(pattern.elements[i])) {
-      hasRest = true;
-      break;
+      return true;
     }
   }
+  return false;
+};
 
-  var toArray = opts.file.toArray(parentId, !hasRest && pattern.elements.length);
+Destructuring.prototype.pushArrayPattern = function (pattern, parentId) {
+  if (!pattern.elements) return;
 
-  var _parentId = opts.scope.generateUidBasedOnNode(parentId, opts.file);
-  nodes.push(buildVariableDeclar(opts, _parentId, toArray));
+  // if we have a rest then we need all the elements
+  var count = !hasRest(pattern) && pattern.elements.length;
+
+  var toArray = this.file.toArray(parentId, count);
+
+  var _parentId = this.scope.generateUidBasedOnNode(parentId, this.file);
+  this.nodes.push(this.buildVariableDeclaration(_parentId, toArray));
   parentId = _parentId;
 
-  for (i = 0; i < pattern.elements.length; i++) {
+  for (var i = 0; i < pattern.elements.length; i++) {
     var elem = pattern.elements[i];
-    if (!elem) continue;
 
-    i = +i;
+    // hole
+    if (!elem) continue;
 
     var newPatternId;
 
     if (t.isRestElement(elem)) {
-      newPatternId = opts.file.toArray(parentId);
+      newPatternId = this.file.toArray(parentId);
 
       if (i > 0) {
         newPatternId = t.callExpression(t.memberExpression(newPatternId, t.identifier("slice")), [t.literal(i)]);
@@ -137,23 +163,18 @@ var pushArrayPattern = function (opts, nodes, pattern, parentId) {
       newPatternId = t.memberExpression(parentId, t.literal(i), true);
     }
 
-    push(opts, nodes, elem, newPatternId);
+    this.push(elem, newPatternId);
   }
 };
 
-var pushPattern = function (opts) {
-  var nodes = opts.nodes;
-  var pattern = opts.pattern;
-  var parentId = opts.id;
-  var scope = opts.scope;
-
+Destructuring.prototype.init = function (pattern, parentId) {
   if (!t.isArrayExpression(parentId) && !t.isMemberExpression(parentId) && !t.isIdentifier(parentId)) {
-    var key = scope.generateUidBasedOnNode(parentId);
-    nodes.push(buildVariableDeclar(opts, key, parentId));
+    var key = this.scope.generateUidBasedOnNode(parentId);
+    this.nodes.push(this.buildVariableDeclaration(key, parentId));
     parentId = key;
   }
 
-  push(opts, nodes, pattern, parentId);
+  this.push(pattern, parentId);
 };
 
 exports.ForInStatement =
@@ -171,11 +192,14 @@ exports.ForOfStatement = function (node, parent, scope, context, file) {
 
   var nodes = [];
 
-  push({
+  var destructuring = new Destructuring({
     kind: declar.kind,
     file: file,
-    scope: scope
-  }, nodes, pattern, key);
+    scope: scope,
+    nodes: nodes
+  });
+
+  destructuring.init(pattern, key);
 
   t.ensureBlock(node);
 
@@ -194,15 +218,14 @@ exports.Function = function (node, parent, scope, context, file) {
     hasDestructuring = true;
     var parentId = scope.generateUidIdentifier("ref");
 
-    pushPattern({
+    var destructuring = new Destructuring({
       blockHoist: node.params.length - i,
-      pattern:    pattern,
       nodes:      nodes,
       scope:      scope,
       file:       file,
       kind:       "var",
-      id:         parentId
     });
+    destructuring.init(pattern, parentId);
 
     return parentId;
   });
@@ -224,11 +247,13 @@ exports.CatchClause = function (node, parent, scope, context, file) {
 
   var nodes = [];
 
-  push({
+  var destructuring = new Destructuring({
     kind: "var",
     file: file,
-    scope: scope
-  }, nodes, pattern, ref);
+    scope: scope,
+    nodes: nodes
+  });
+  destructuring.init(pattern, ref);
 
   node.body.body = nodes.concat(node.body.body);
 };
@@ -246,11 +271,13 @@ exports.ExpressionStatement = function (node, parent, scope, context, file) {
     t.variableDeclarator(ref, expr.right)
   ]));
 
-  push({
+  var destructuring = new Destructuring({
     operator: expr.operator,
     file: file,
-    scope: scope
-  }, nodes, expr.left, ref);
+    scope: scope,
+    nodes: nodes
+  });
+  destructuring.init(expr.left, ref);
 
   return nodes;
 };
@@ -267,50 +294,50 @@ exports.AssignmentExpression = function (node, parent, scope, context, file) {
   var nodes = [];
   nodes.push(t.assignmentExpression("=", ref, node.right));
 
-  push({
+  var destructuring = new Destructuring({
     operator: node.operator,
     file: file,
-    scope: scope
-  }, nodes, node.left, ref);
+    scope: scope,
+    nodes: nodes
+  });
+  destructuring.init(node.left, ref);
 
   nodes.push(ref);
 
   return t.toSequenceExpression(nodes, scope);
 };
 
-exports.VariableDeclaration = function (node, parent, scope, context, file) {
-  if (t.isForInStatement(parent) || t.isForOfStatement(parent)) return;
-
-  var nodes = [];
-  var i;
-  var declar;
-
-  var hasPattern = false;
-  for (i = 0; i < node.declarations.length; i++) {
-    declar = node.declarations[i];
-    if (t.isPattern(declar.id)) {
-      hasPattern = true;
-      break;
+var variableDeclarationhasPattern = function (node) {
+  for (var i = 0; i < node.declarations.length; i++) {
+    if (t.isPattern(node.declarations[i].id)) {
+      return true;
     }
   }
-  if (!hasPattern) return;
+  return false;
+};
 
-  for (i = 0; i < node.declarations.length; i++) {
+exports.VariableDeclaration = function (node, parent, scope, context, 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 opts = {
-      pattern: pattern,
-      nodes:   nodes,
-      scope:   scope,
-      kind:    node.kind,
-      file:    file,
-      id:      patternId,
-    };
+
+    var destructuring = new Destructuring({
+      nodes: nodes,
+      scope: scope,
+      kind:  node.kind,
+      file:  file
+    });
 
     if (t.isPattern(pattern) && patternId) {
-      pushPattern(opts);
+      destructuring.init(pattern, patternId);
 
       if (+i !== node.declarations.length - 1) {
         // we aren't the last declarator so let's just make the
@@ -318,11 +345,14 @@ exports.VariableDeclaration = function (node, parent, scope, context, file) {
         t.inherits(nodes[nodes.length - 1], declar);
       }
     } else {
-      nodes.push(t.inherits(buildVariableAssign(opts, declar.id, declar.init), declar));
+      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++) {

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

@@ -3,6 +3,8 @@
 var util = require("../../../util");
 var t    = require("../../../types");
 
+exports.check = t.isForOfStatement;
+
 exports.ForOfStatement = function (node, parent, scope, context, file) {
   var callback = spec;
   if (file.isLoose("es6.forOf")) callback = loose;
@@ -20,11 +22,7 @@ exports.ForOfStatement = function (node, parent, scope, context, file) {
 
   // add the value declaration to the new loop body
   if (declar) {
-    if (build.shouldUnshift) {
-      block.body.unshift(declar);
-    } else {
-      block.body.push(declar);
-    }
+    block.body.push(declar);
   }
 
   // push the rest of the original loop body onto our new body
@@ -45,9 +43,9 @@ var loose = function (node, parent, scope, context, file) {
     id = left;
   } else if (t.isVariableDeclaration(left)) {
     // for (var i of test)
-    id = left.declarations[0].id;
+    id = scope.generateUidIdentifier("ref");
     declar = t.variableDeclaration(left.kind, [
-      t.variableDeclarator(id)
+      t.variableDeclarator(left.declarations[0].id, id)
     ]);
   } else {
     throw file.errorWithNode(left, "Unknown node type " + left.type + " in ForOfStatement");
@@ -61,10 +59,15 @@ var loose = function (node, parent, scope, context, file) {
     ID:           id
   });
 
+  if (!declar) {
+    // no declaration so we need to remove the variable declaration at the top of
+    // the for-of-loose template
+    loop.body.body.shift();
+  }
+
   return {
-    shouldUnshift: true,
-    declar:        declar,
-    loop:          loop
+    declar: declar,
+    loop:   loop
   };
 };
 

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

@@ -2,6 +2,8 @@
 
 var t = require("../../../types");
 
+exports.check = require("../internal/modules").check;
+
 exports.ImportDeclaration = function (node, parent, scope, context, file) {
   var nodes = [];
 
@@ -26,7 +28,7 @@ exports.ExportDeclaration = function (node, parent, scope, context, file) {
   var i;
 
   if (node.declaration) {
-    // make sure variable exports have an initialiser
+    // make sure variable exports have an initializer
     // this is done here to avoid duplicating it in the module formatters
     if (t.isVariableDeclaration(node.declaration)) {
       var declar = node.declaration.declarations[0];

lib/6to5/transformation/transformers/es6/parameters.default.js

@@ -1,8 +1,11 @@
 "use strict";
 
-var traverse = require("../../../traverse");
-var util     = require("../../../util");
-var t        = require("../../../types");
+var util = require("../../../util");
+var t    = require("../../../types");
+
+exports.check = function (node) {
+  return t.isFunction(node) && hasDefaults(node);
+};
 
 var hasDefaults = function (node) {
   for (var i = 0; i < node.params.length; i++) {
@@ -13,7 +16,7 @@ var hasDefaults = function (node) {
 
 var iifeVisitor = {
   enter: function (node, parent, scope, context, state) {
-    if (t.isReferencedIdentifier(node, parent) && scope.hasOwn(node.name)) {
+    if (t.isReferencedIdentifier(node, parent) && state.scope.hasOwnReference(node.name)) {
       state.iife = true;
       context.stop();
     }
@@ -48,10 +51,10 @@ exports.Function = function (node, parent, scope) {
     node.params[i] = scope.generateUidIdentifier("x");
 
     if (!state.iife) {
-      if (t.isIdentifier(right) && scope.hasOwn(right.name)) {
+      if (t.isIdentifier(right) && scope.hasOwnReference(right.name)) {
         state.iife = true;
       } else {
-        traverse(right, iifeVisitor, scope, state);
+        scope.traverse(right, iifeVisitor, state);
       }
     }
 

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

@@ -3,6 +3,8 @@
 var util = require("../../../util");
 var t    = require("../../../types");
 
+exports.check = t.isRestElement;
+
 var hasRest = function (node) {
   return t.isRestElement(node.params[node.params.length - 1]);
 };
@@ -12,8 +14,6 @@ exports.Function = function (node, parent, scope) {
 
   var rest = node.params.pop().argument;
 
-  t.ensureBlock(node);
-
   var argsId = t.identifier("arguments");
 
   // otherwise `arguments` will be remapped in arrow functions
@@ -60,15 +60,15 @@ exports.Function = function (node, parent, scope) {
     node.body.body.unshift(restDeclar);
   }
 
-  node.body.body.unshift(
-    util.template("rest", {
-      ARGUMENTS: argsId,
-      ARRAY_KEY: arrKey,
-      ARRAY_LEN: arrLen,
-      START: start,
-      ARRAY: rest,
-      KEY: key,
-      LEN: len,
-    })
-  );
+  var loop = util.template("rest", {
+    ARGUMENTS: argsId,
+    ARRAY_KEY: arrKey,
+    ARRAY_LEN: arrLen,
+    START: start,
+    ARRAY: rest,
+    KEY: key,
+    LEN: len,
+  });
+  loop._blockHoist = node.params.length + 1;
+  node.body.body.unshift(loop);
 };

lib/6to5/transformation/transformers/es6/properties.computed.js

@@ -2,6 +2,10 @@
 
 var t = require("../../../types");
 
+exports.check = function (node) {
+  return t.isProperty(node) && node.computed;
+};
+
 exports.ObjectExpression = function (node, parent, scope, context, file) {
   var hasComputed = false;
 
@@ -58,7 +62,7 @@ var spec = function (node, body, objId, initProps, file) {
   var props = node.properties;
   var prop, key;
 
-  // normalise key
+  // normalize key
 
   for (var i = 0; i < props.length; i++) {
     prop = props[i];

lib/6to5/transformation/transformers/es6/properties.shorthand.js

@@ -2,7 +2,11 @@
 
 var nameMethod = require("../../helpers/name-method");
 var t          = require("../../../types");
-var _          = require("lodash");
+var clone      = require("lodash/lang/clone");
+
+exports.check = function (node) {
+  return t.isProperty(node) && (node.method || node.shorthand);
+};
 
 exports.Property = function (node, parent, scope, context, file) {
   if (node.method) {
@@ -12,6 +16,6 @@ exports.Property = function (node, parent, scope, context, file) {
 
   if (node.shorthand) {
     node.shorthand = false;
-    node.key = t.removeComments(_.clone(node.key));
+    node.key = t.removeComments(clone(node.key));
   }
 };

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

@@ -1,7 +1,9 @@
 "use strict";
 
-var t = require("../../../types");
-var _ = require("lodash");
+var contains = require("lodash/collection/contains");
+var t        = require("../../../types");
+
+exports.check = t.isSpreadElement;
 
 var getSpreadLiteral = function (spread, file) {
   return file.toArray(spread.argument);
@@ -101,7 +103,7 @@ exports.NewExpression = function (node, parent, scope, context, file) {
   var args = node.arguments;
   if (!hasSpread(args)) return;
 
-  var nativeType = t.isIdentifier(node.callee) && _.contains(t.NATIVE_TYPE_NAMES, node.callee.name);
+  var nativeType = t.isIdentifier(node.callee) && contains(t.NATIVE_TYPE_NAMES, node.callee.name);
 
   var nodes = build(args, file);
 

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

@@ -6,6 +6,10 @@ var buildBinaryExpression = function (left, right) {
   return t.binaryExpression("+", left, right);
 };
 
+exports.check = function (node) {
+  return t.isTemplateLiteral(node) || t.isTaggedTemplateExpression(node);
+};
+
 exports.TaggedTemplateExpression = function (node, parent, scope, context, file) {
   var args = [];
   var quasi = node.quasi;

lib/6to5/transformation/transformers/es6/unicode-regex.js

@@ -1,7 +1,12 @@
 "use strict";
 
 var rewritePattern = require("regexpu/rewrite-pattern");
-var _              = require("lodash");
+var pull           = require("lodash/array/pull");
+var t              = require("../../../types");
+
+exports.check = function (node) {
+  return t.isLiteral(node) && node.regex && node.regex.flags.indexOf("u") >= 0;
+};
 
 exports.Literal = function (node) {
   var regex = node.regex;
@@ -9,7 +14,7 @@ exports.Literal = function (node) {
 
   var flags = regex.flags.split("");
   if (regex.flags.indexOf("u") < 0) return;
-  _.pull(flags, "u");
+  pull(flags, "u");
 
   regex.pattern = rewritePattern(regex.pattern, regex.flags);
   regex.flags   = flags.join("");

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

@@ -6,18 +6,21 @@ var t = require("../../../types");
 
 exports.experimental = true;
 
-exports.ObjectExpression = function (node, parent, scope, context, file) {
-  var hasSpread = false;
-  var i;
-  var prop;
-  for (i = 0; i < node.properties.length; i++) {
-    prop = node.properties[i];
-    if (t.isSpreadProperty(prop)) {
-      hasSpread = true;
-      break;
+exports.manipulateOptions = function (opts) {
+  if (opts.whitelist.length) opts.whitelist.push("es6.destructuring");
+};
+
+var hasSpread = function (node) {
+  for (var i = 0; i < node.properties.length; i++) {
+    if (t.isSpreadProperty(node.properties[i])) {
+      return true;
     }
   }
-  if (!hasSpread) return;
+  return false;
+};
+
+exports.ObjectExpression = function (node, parent, scope, context, file) {
+  if (!hasSpread(node)) return;
 
   var args = [];
   var props = [];
@@ -28,8 +31,8 @@ exports.ObjectExpression = function (node, parent, scope, context, file) {
     props = [];
   };
 
-  for (i = 0; i < node.properties.length; i++) {
-    prop = node.properties[i];
+  for (var i = 0; i < node.properties.length; i++) {
+    var prop = node.properties[i];
     if (t.isSpreadProperty(prop)) {
       push();
       args.push(prop.argument);

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

@@ -13,7 +13,7 @@ module.exports = {
 
   react:                                   require("./other/react"),
 
-  _modulesSplit:                           require("./internal/modules-split"),
+  _modules:                                require("./internal/modules"),
 
   // needs to be before `regenerator` due to generator comprehensions
   // needs to be before `_aliasFunction`
@@ -27,7 +27,7 @@ module.exports = {
   asyncToGenerator:                        require("./other/async-to-generator"),
   bluebirdCoroutines:                      require("./other/bluebird-coroutines"),
 
-  "es7.objectSpread":                      require("./es7/object-spread"),
+  "es7.objectRestSpread":                  require("./es7/object-rest-spread"),
   "es7.exponentiationOperator":            require("./es7/exponentiation-operator"),
   "es6.spread":                            require("./es6/spread"),
   "es6.templateLiterals":                  require("./es6/template-literals"),
@@ -52,14 +52,13 @@ module.exports = {
   // needs to be after `es6.blockScoping` due to needing `letReferences` set on blocks
   "es6.blockScopingTDZ":                   require("./es6/block-scoping-tdz"),
 
-  // needs to be after block scoping since regenerator doesn't support it
-  regenerator:                             require("./other/regenerator"),
-
   "es6.parameters.default":                require("./es6/parameters.default"),
   "es6.parameters.rest":                   require("./es6/parameters.rest"),
 
   "es6.destructuring":                     require("./es6/destructuring"),
 
+  regenerator:                             require("./other/regenerator"),
+
   // needs to be after `regenerator` due to needing `regeneratorRuntime` references
   // needs to be after `es6.forOf` due to needing `Symbol.iterator` references
   // needs to be before `es6.modules` due to dynamic imports
@@ -81,5 +80,10 @@ module.exports = {
   "spec.undefinedToVoid":                  require("./spec/undefined-to-void"),
 
   "minification.propertyLiterals":         require("./minification/property-literals"),
-  "minification.memberExpressionLiterals": require("./minification/member-expression-literals")
+  "minification.memberExpressionLiterals": require("./minification/member-expression-literals"),
+
+  "minification.removeDebugger":           require("./minification/remove-debugger"),
+  "minification.removeConsoleCalls":       require("./minification/remove-console-calls"),
+  "minification.deadCodeElimination":      require("./minification/dead-code-elimination"),
+  "minification.renameLocalVariables":     require("./minification/rename-local-variables")
 };

lib/6to5/transformation/transformers/internal/alias-functions.js

@@ -1,7 +1,6 @@
 "use strict";
 
-var traverse = require("../../../traverse");
-var t        = require("../../../types");
+var t = require("../../../types");
 
 var functionChildrenVisitor = {
   enter: function (node, parent, scope, context, state) {
@@ -37,7 +36,7 @@ var functionVisitor = {
     }
 
     // traverse all child nodes of this function and find `arguments` and `this`
-    traverse(node, functionChildrenVisitor, scope, state);
+    scope.traverse(node, functionChildrenVisitor, state);
 
     return context.skip();
   }
@@ -58,7 +57,7 @@ var go = function (getBody, node, scope) {
 
   // traverse the function and find all alias functions so we can alias
   // `arguments` and `this` if necessary
-  traverse(node, functionVisitor, scope, state);
+  scope.traverse(node, functionVisitor, state);
 
   var body;
 

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

@@ -1,7 +1,9 @@
 "use strict";
 
 var useStrict = require("../../helpers/use-strict");
-var _         = require("lodash");
+var groupBy   = require("lodash/collection/groupBy");
+var flatten   = require("lodash/array/flatten");
+var values    = require("lodash/object/values");
 
 // Priority:
 //
@@ -21,14 +23,14 @@ exports.Program = {
     if (!hasChange) return;
 
     useStrict.wrap(node, function () {
-      var nodePriorities = _.groupBy(node.body, function (bodyNode) {
+      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());
+      node.body = flatten(values(nodePriorities).reverse());
     });
   }
 };

lib/6to5/transformation/transformers/internal/modules-split.js

@@ -1,28 +0,0 @@
-"use strict";
-
-var t = require("../../../types");
-
-exports.ExportDeclaration = function (node, parent, scope) {
-  var declar = node.declaration;
-
-  if (node.default) {
-    if (t.isClassDeclaration(declar)) {
-      node.declaration = declar.id;
-      return [declar, node];
-    } else if (t.isClassExpression(declar)) {
-      var temp = scope.generateUidIdentifier("default");
-      declar = t.variableDeclaration("var", [
-        t.variableDeclarator(temp, declar)
-      ]);
-      node.declaration = temp;
-      return [declar, node];
-    }
-  } else {
-    if (t.isFunctionDeclaration(declar)) {
-      node.specifiers  = [t.importSpecifier(declar.id, declar.id)];
-      node.declaration = null;
-      node._blockHoist = 2;
-      return [declar, node];
-    }
-  }
-};

lib/6to5/transformation/transformers/internal/modules.js

@@ -0,0 +1,53 @@
+"use strict";
+
+// in this transformer we have to split up classes and function declarations
+// from their exports. why? because sometimes we need to replace classes with
+// nodes that aren't allowed in the same contexts. also, if you're exporting
+// a generator function as a default then regenerator will destroy the export
+// declaration and leave a variable declaration in it's place... yeah, handy.
+
+var t = require("../../../types");
+
+var resolveModuleSource = function (node, parent, scope, context, file) {
+  var resolveModuleSource = file.opts.resolveModuleSource;
+  if (node.source && resolveModuleSource) {
+    node.source.value = resolveModuleSource(node.source.value);
+  }
+};
+
+exports.check = function (node) {
+  return t.isImportDeclaration(node) || t.isExportDeclaration(node);
+};
+
+exports.ImportDeclaration = resolveModuleSource;
+
+exports.ExportDeclaration = function (node, parent, scope) {
+  resolveModuleSource.apply(null, arguments);
+
+  var declar = node.declaration;
+
+  if (node.default) {
+    if (t.isClassDeclaration(declar)) {
+      node.declaration = declar.id;
+      return [declar, node];
+    } else if (t.isClassExpression(declar)) {
+      var temp = scope.generateUidIdentifier("default");
+      declar = t.variableDeclaration("var", [
+        t.variableDeclarator(temp, declar)
+      ]);
+      node.declaration = temp;
+      return [declar, node];
+    } else if (t.isFunctionDeclaration(declar)) {
+      node._blockHoist = 2;
+      node.declaration = declar.id;
+      return [declar, node];
+    }
+  } else {
+    if (t.isFunctionDeclaration(declar)) {
+      node.specifiers  = [t.importSpecifier(declar.id, declar.id)];
+      node.declaration = null;
+      node._blockHoist = 2;
+      return [declar, node];
+    }
+  }
+};

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

@@ -0,0 +1,77 @@
+var t = require("../../../types");
+
+exports.optional = true;
+
+exports.ExpressionStatement = function (node, parent, scope, context) {
+  // remove consequenceless expressions such as local variables and literals
+  //
+  //   var foo = true; foo; -> var foo = true;
+  //   "foo"; ->
+  //
+
+  var expr = node.expression;
+  if (t.isLiteral(expr) || (t.isIdentifier(node) && t.hasBinding(node.name))) {
+    context.remove();
+  }
+};
+
+exports.IfStatement = {
+  exit: function (node, parent, scope, context) {
+    // todo: in scenarios where we can just return the consequent or
+    // alternate we should drop the block statement if it contains no
+    // block scoped variables
+
+    var consequent = node.consequent;
+    var alternate  = node.alternate;
+    var test       = node.test;
+
+    // we can check if a test will be truthy 100% and if so we can inline
+    // the consequent and completely ignore the alternate
+    //
+    //   if (true) { foo; } -> { foo; }
+    //   if ("foo") { foo; } -> { foo; }
+    //
+
+    if (t.isLiteral(test) && test.value) {
+      return alternate;
+    }
+
+    // we can check if a test will be falsy 100% and if so we can inline
+    // the alternate if there is one and completely remove the consequent
+    //
+    //   if ("") { bar; } else { foo; } -> { foo; }
+    //   if ("") { bar; } ->
+    //
+
+    if (t.isFalsyExpression(test)) {
+      if (alternate) {
+        return alternate;
+      } else {
+        return context.remove();
+      }
+    }
+
+    // remove alternate blocks that are empty
+    //
+    //   if (foo) { foo; } else {} -> if (foo) { foo; }
+    //
+
+    if (t.isBlockStatement(alternate) && !alternate.body.length) {
+      alternate = node.alternate = null;
+    }
+
+    // turn alternate blocks into a consequent and flip the test if the
+    // consequent block is empty
+    //
+    //   if (foo) {} else { bar; }
+    //   if (!foo) { bar; }
+    //
+
+    if (t.blockStatement(consequent) && !consequent.body.length &&
+        t.isBlockStatement(alternate) && alternate.body.length) {
+      node.consequent = node.alternate;
+      node.alternate  = null;
+      node.test       = t.unaryExpression("!", test, true);
+    }
+  }
+};

lib/6to5/transformation/transformers/minification/remove-console-calls.js

@@ -0,0 +1,13 @@
+"use strict";
+
+var t = require("../../../types");
+
+var isConsole = t.buildMatchMemberExpression("console", true);
+
+exports.optional = true;
+
+exports.CallExpression = function (node, parent, scope, context) {
+  if (isConsole(node.callee)) {
+    context.remove();
+  }
+};

lib/6to5/transformation/transformers/minification/remove-debugger.js

@@ -0,0 +1,9 @@
+var t = require("../../../types");
+
+exports.optional = true;
+
+exports.ExpressionStatement = function (node, parent, scope, context) {
+  if (t.isIdentifier(node.expression, { name: "debugger" })) {
+    context.remove();
+  }
+};

lib/6to5/transformation/transformers/minification/rename-local-variables.js

@@ -0,0 +1,10 @@
+//var t = require("../../../types");
+
+exports.optional = true;
+
+exports.Scope = function () {
+  // todo: get all binding identifiers, generate compact names
+  // that wont collide and then call the remap identifier helper
+  // this transformer **has** to be ran last as it will absolutley
+  // destroy the scope tree
+};

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

@@ -5,11 +5,21 @@
 
 // jsx
 
-var esutils = require("esutils");
-var t       = require("../../../types");
+var isString = require("lodash/lang/isString");
+var esutils  = require("esutils");
+var react    = require("../../helpers/react");
+var t        = require("../../../types");
 
-exports.JSXIdentifier = function (node) {
-  if (esutils.keyword.isIdentifierName(node.name)) {
+exports.check = function (node) {
+  if (t.isJSX(node)) return true;
+  if (react.isCreateClass(node)) return true;
+  return false;
+};
+
+exports.JSXIdentifier = function (node, parent) {
+  if (node.name === "this" && t.isReferenced(node, parent)) {
+    return t.thisExpression();
+  } else if (esutils.keyword.isIdentifierName(node.name)) {
     node.type = "Identifier";
   } else {
     return t.literal(node.name);
@@ -157,6 +167,8 @@ exports.JSXElement = {
       callExpr.arguments.push(child);
     }
 
+    callExpr.arguments = flatten(callExpr.arguments);
+
     if (callExpr.arguments.length >= 3) {
       callExpr._prettyCall = true;
     }
@@ -165,14 +177,45 @@ exports.JSXElement = {
   }
 };
 
+var isStringLiteral = function (node) {
+  return t.isLiteral(node) && isString(node.value);
+};
+
+var flatten = function (args) {
+  var flattened = [];
+  var last;
+
+  for (var i = 0; i < args.length; i++) {
+    var arg = args[i];
+    if (isStringLiteral(arg) && isStringLiteral(last)) {
+      last.value += arg.value;
+    } else {
+      last = arg;
+      flattened.push(arg);
+    }
+  }
+
+  return flattened;
+};
+
 var cleanJSXElementLiteralChild = function (child, args) {
   var lines = child.value.split(/\r\n|\n|\r/);
 
-  for (var i = 0; i < lines.length; i++) {
+  var lastNonEmptyLine = 0;
+  var i;
+
+  for (i = 0; i < lines.length; i++) {
+    if (lines[i].match(/[^ \t]/)) {
+      lastNonEmptyLine = i;
+    }
+  }
+
+  for (i = 0; i < lines.length; i++) {
     var line = lines[i];
 
     var isFirstLine = i === 0;
     var isLastLine = i === lines.length - 1;
+    var isLastNonEmptyLine = i === lastNonEmptyLine;
 
     // replace rendered whitespace tabs with spaces
     var trimmedLine = line.replace(/\t/g, " ");
@@ -188,6 +231,10 @@ var cleanJSXElementLiteralChild = function (child, args) {
     }
 
     if (trimmedLine) {
+      if (!isLastNonEmptyLine) {
+        trimmedLine += " ";
+      }
+
       args.push(t.literal(trimmedLine));
     }
   }
@@ -195,34 +242,7 @@ var cleanJSXElementLiteralChild = function (child, args) {
 
 // display names
 
-var isCreateClass = function (call) {
-  if (!call || !t.isCallExpression(call)) return false;
-
-  var callee = call.callee;
-  if (!t.isMemberExpression(callee)) return false;
-
-  // not React call member object
-  var obj = callee.object;
-  if (!t.isIdentifier(obj, { name: "React" })) return false;
-
-  // not createClass call member property
-  var prop = callee.property;
-  if (!t.isIdentifier(prop, { name: "createClass" })) return false;
-
-  // no call arguments
-  var args = call.arguments;
-  if (args.length !== 1) return false;
-
-  // first call arg is not an object
-  var first = args[0];
-  if (!t.isObjectExpression(first)) return;
-
-  return true;
-};
-
 var addDisplayName = function (id, call) {
-  if (!isCreateClass(call)) return;
-
   var props = call.arguments[0].properties;
   var safe = true;
 
@@ -239,6 +259,12 @@ var addDisplayName = function (id, call) {
   }
 };
 
+exports.ExportDeclaration = function (node, parent, scope, context, file) {
+  if (node.default && react.isCreateClass(node.declaration)) {
+    addDisplayName(file.opts.basename, node.declaration);
+  }
+};
+
 exports.AssignmentExpression =
 exports.Property =
 exports.VariableDeclarator = function (node) {
@@ -259,7 +285,7 @@ exports.VariableDeclarator = function (node) {
     left = left.property;
   }
 
-  if (t.isIdentifier(left)) {
+  if (t.isIdentifier(left) && react.isCreateClass(right)) {
     addDisplayName(left.name, right);
   }
 };

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

@@ -1,6 +1,11 @@
 "use strict";
 
 var regenerator = require("regenerator-6to5");
+var t           = require("../../../types");
+
+exports.check = function (node) {
+  return t.isFunction(node) && (node.async || node.generator);
+};
 
 exports.ast = {
   before: function (ast, file) {

lib/6to5/transformation/transformers/other/self-contained.js

@@ -1,13 +1,13 @@
 "use strict";
 
-var traverse = require("../../../traverse");
 var util     = require("../../../util");
 var core     = require("core-js/library");
 var t        = require("../../../types");
-var _        = require("lodash");
+var has      = require("lodash/object/has");
+var contains = require("lodash/collection/contains");
 
 var coreHas = function (node) {
-  return node.name !== "_" && _.has(core, node.name);
+  return node.name !== "_" && has(core, node.name);
 };
 
 var ALIASABLE_CONSTRUCTORS = [
@@ -30,11 +30,11 @@ var astVisitor = {
 
       if (!t.isReferenced(obj, node)) return;
 
-      if (!node.computed && coreHas(obj) && _.has(core[obj.name], prop.name)) {
+      if (!node.computed && coreHas(obj) && has(core[obj.name], prop.name)) {
         context.skip();
         return t.prependToMemberExpression(node, file.get("coreIdentifier"));
       }
-    } else if (t.isReferencedIdentifier(node, parent) && !t.isMemberExpression(parent) && _.contains(ALIASABLE_CONSTRUCTORS, node.name) && !scope.get(node.name, true)) {
+    } else if (t.isReferencedIdentifier(node, parent) && !t.isMemberExpression(parent) && contains(ALIASABLE_CONSTRUCTORS, node.name) && !scope.getBinding(node.name)) {
       // Symbol() -> _core.Symbol(); new Promise -> new _core.Promise
       return t.memberExpression(file.get("coreIdentifier"), node);
     } else if (t.isCallExpression(node)) {
@@ -60,6 +60,10 @@ var astVisitor = {
 
 exports.optional = true;
 
+exports.manipulateOptions = function (opts) {
+  if (opts.whitelist.length) opts.whitelist.push("es6.modules");
+};
+
 exports.ast = {
   enter: function (ast, file) {
     file.setDynamic("runtimeIdentifier", function () {
@@ -76,7 +80,7 @@ exports.ast = {
   },
 
   after: function (ast, file) {
-    traverse(ast, astVisitor, null, file);
+    file.scope.traverse(ast, astVisitor, file);
   }
 };
 

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

@@ -16,6 +16,6 @@ exports.FunctionExpression = function (node, parent, scope, context) {
   context.skip();
 };
 
-exports.ThisExpression = function (node, parent, scope, context, file) {
-  throw file.errorWithNode(node, "Top level `this` is not allowed", ReferenceError);
+exports.ThisExpression = function () {
+  return t.identifier("undefined");
 };

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

@@ -1,7 +1,9 @@
 "use strict";
 
 var build = require("../../helpers/build-conditional-assignment-operator-transformer");
-var t      = require("../../../types");
+var t     = require("../../../types");
+
+exports.playground = true;
 
 build(exports, {
   is: function (node, file) {

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

@@ -3,6 +3,8 @@
 var build = require("../../helpers/build-conditional-assignment-operator-transformer");
 var t     = require("../../../types");
 
+exports.playground = true;
+
 build(exports, {
   is: function (node) {
     var is = t.isAssignmentExpression(node) && node.operator === "?=";

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

@@ -2,6 +2,8 @@
 
 var t = require("../../../types");
 
+exports.playground = true;
+
 exports.BindMemberExpression = function (node, parent, scope) {
   var object = node.object;
   var prop   = node.property;

lib/6to5/transformation/transformers/playground/object-getter-memoization.js

@@ -1,7 +1,8 @@
 "use strict";
 
-var traverse = require("../../../traverse");
-var t        = require("../../../types");
+var t = require("../../../types");
+
+exports.playground = true;
 
 var visitor = {
   enter: function (node, parent, scope, context, state) {
@@ -21,6 +22,7 @@ exports.Property =
 exports.MethodDefinition = function (node, parent, scope, context, file) {
   if (node.kind !== "memo") return;
   node.kind = "get";
+  file.checkNode(node, scope);
 
   var value = node.value;
   t.ensureBlock(value);
@@ -36,5 +38,5 @@ exports.MethodDefinition = function (node, parent, scope, context, file) {
     file: file
   };
 
-  traverse(value, visitor, scope, state);
+  scope.traverse(value, visitor, state);
 };

lib/6to5/transformation/transformers/spec/block-scoped-functions.js

@@ -3,13 +3,13 @@
 var t = require("../../../types");
 
 exports.BlockStatement = function (node, parent) {
-  if (t.isFunction(parent) || t.isExportDeclaration(parent)) {
+  if ((t.isFunction(parent) && parent.body === node) || t.isExportDeclaration(parent)) {
     return;
   }
 
   for (var i = 0; i < node.body.length; i++) {
     var func = node.body[i];
-    if (!t.isFunctionDeclaration(i)) continue;
+    if (!t.isFunctionDeclaration(func)) continue;
 
     var declar = t.variableDeclaration("let", [
       t.variableDeclarator(func.id, t.toExpression(func))
@@ -21,6 +21,6 @@ exports.BlockStatement = function (node, parent) {
     // todo: name this
     func.id = null;
 
-    func.body[i] = declar;
+    node.body[i] = declar;
   }
 };

lib/6to5/transformation/transformers/spec/proto-to-assign.js

@@ -1,7 +1,7 @@
 "use strict";
 
-var t = require("../../../types");
-var _ = require("lodash");
+var t    = require("../../../types");
+var pull = require("lodash/array/pull");
 
 var isProtoKey = function (node) {
   return t.isLiteral(t.toComputedKey(node, node.key), { value: "__proto__" });
@@ -50,7 +50,7 @@ exports.ObjectExpression = function (node, parent, scope, context, file) {
 
     if (isProtoKey(prop)) {
       proto = prop.value;
-      _.pull(node.properties, prop);
+      pull(node.properties, prop);
     }
   }
 

lib/6to5/transformation/transformers/validation/undeclared-variable-check.js

@@ -1,9 +1,38 @@
 "use strict";
 
+var levenshtein = require("../../../helpers/levenshtein");
+var t           = require("../../../types");
+
 exports.optional = true;
 
 exports.Identifier = function (node, parent, scope, context, file) {
-  if (!scope.has(node.name, true)) {
-    throw file.errorWithNode(node, "Reference to undeclared variable", ReferenceError);
+  if (!t.isReferenced(node, parent)) return;
+  if (scope.hasBinding(node.name)) return;
+
+  var msg = "Reference to undeclared variable";
+
+  // get the closest declaration to offer as a suggestion
+  // the variable name may have just been mistyped
+
+  var bindings = scope.getAllBindings();
+
+  var closest;
+  var shortest = -1;
+
+  for (var name in bindings) {
+    var distance = levenshtein(node.name, name);
+    if (distance <= 0 || distance > 3) continue;
+    if (distance <= shortest) continue;
+
+    closest = name;
+    shortest = distance;
   }
+
+  if (closest) {
+    msg += " - Did you mean " + closest + "?";
+  }
+
+  //
+
+  throw file.errorWithNode(node, msg, ReferenceError);
 };

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

@@ -1,64 +0,0 @@
-[
-  "Set",
-  "Map",
-  "WeakMap",
-  "WeakSet",
-  "Proxy",
-  "Promise",
-  "Reflect",
-  "Symbol",
-  "System",
-  "__filename",
-  "__dirname",
-  "GLOBAL",
-  "global",
-  "module",
-  "require",
-  "Buffer",
-  "console",
-  "exports",
-  "process",
-  "setTimeout",
-  "clearTimeout",
-  "setInterval",
-  "clearInterval",
-  "setImmediate",
-  "clearImmediate",
-  "Array",
-  "Boolean",
-  "Date",
-  "decodeURI",
-  "decodeURIComponent",
-  "encodeURI",
-  "encodeURIComponent",
-  "Error",
-  "eval",
-  "EvalError",
-  "Function",
-  "hasOwnProperty",
-  "isFinite",
-  "isNaN",
-  "JSON",
-  "Map",
-  "Math",
-  "Number",
-  "Object",
-  "Proxy",
-  "Promise",
-  "parseInt",
-  "parseFloat",
-  "RangeError",
-  "ReferenceError",
-  "RegExp",
-  "Set",
-  "String",
-  "SyntaxError",
-  "TypeError",
-  "URIError",
-  "WeakMap",
-  "WeakSet",
-  "arguments",
-  "NaN",
-  "window",
-  "self"
-]