v5.6.3

matchPattern fixes and "this" handling

.eslintrc

@@ -17,7 +17,8 @@
     "no-fallthrough": 0,
     "new-cap": 0,
     "no-loop-func": 0,
-    "no-unreachable": 0
+    "no-unreachable": 0,
+    "no-labels": 0
   },
   "env": {
     "node": true

.travis.yml

@@ -11,9 +11,4 @@ before_script: "npm install -g codeclimate-test-reporter"
 script: "make test-travis"
 
 notifications:
-  webhooks:
-    urls:
-      - https://webhooks.gitter.im/e/acf1870e9d223c65e8d5
-    on_success: always
-    on_failure: always
-    on_start: false
+  slack: babeljs:5Wy4QX13KVkGy9CnU0rmvgeK

CHANGELOG.md

@@ -13,6 +13,79 @@ _Note: Gaps between patch versions are faulty/broken releases._
 
 See [CHANGELOG - 6to5](CHANGELOG-6to5.md) for the pre-4.0.0 version changelog.
 
+## 5.6.3
+
+ * **Bug Fix**
+  * Fix rest parameter array allocation loop being incorrectly aliased.
+
+## 5.6.2
+
+ * **Bug Fix**
+  * Fix method key literals not turning into computed member expression in loose mode.
+  * Elect rest parameters in spread element position as candidates instead of replacing them in place.
+
+## 5.6.0
+
+ * **Bug Fix**
+  * Fix istanbul interop for register hook when registering for non-existence extension.
+  * Fix super class constructor call differing for no constructor in derived classes.
+  * Disable module import receiver when in loose mode.
+  * Fix duplicate filenames when using `babel` CLI when passing multiple matching patterns.
+  * Register labels as bindings to fix undeclared variable checks.
+ * **Polish**
+  * Remove unnecessary string binary expressions when transforming template literals.
+  * Support module live bindings in arbitary positions not in Program statement position.
+  * Throw error when attemping to replace a `Program` root node with another node not of type `Program`.
+  * Optimise rest parameters in spread element position and allocate rest array at the earliest common ancestor of all references.
+  * Generate original number representation when value was not changed.
+  * Check for invalid binding identifiers when generating inferred method names.
+  * Don't terminate CLI when watching files fail compilation on init.
+ * **New Feature**
+  * Add new plugin API.
+ * **Internal**
+  * Split react displayName addition into a plugin.
+  * Add check for `JSXMemberExpression` to `t.isReferenced`.
+  * Move `validation.undeclaredVariableCheck` transformer up.
+  * Start great core-to-plugin exodus.
+  * Add `BindingIdentifier` virtual type.
+  * Hidden class optimisations.
+  * Array allocation optimisations.
+  * Update `regenerator`.
+  * Update `js-tokens`.
+  * Sync with upstream Acorn.
+
+## 5.5.8
+
+ * **Internal**
+  * Remove extremely unprofessional and harsh error message for those hotlinking to `resolve-rc`.
+
+## 5.5.7
+
+ * **Bug Fix**
+  * Push newline after decorators when doing code gen.
+  * Rewriting error handling to normalise options before merging them.
+  * Remove duplicate keys in `alias-keys.json` causing errors in strict mode.
+  * Fix `$ babel --help` not showing optional transformers as such.
+ * **New Feature**
+  * Add `auxiliaryCommentBefore` and `auxiliaryCommentAfter` options.
+
+## 5.5.6
+
+ * **Bug Fix**
+  * Fix `let` binding collision in loop head not properly replacing `AssignmentExpression`s.
+
+## 5.5.5
+
+ * **Bug Fix**
+  * Fix `file.opts` not being set before `file.log.deprecate` was called causing a `ReferenceError` as it was checking for a property on it.
+
+## 5.5.4
+
+ * **Bug Fix**
+  * Add back missing `shouldIgnore` check.
+  * Log message on deprecated options rather than throw an error.
+  * Fix name of `auxiliaryComment` option when attempting Istanbul interop in `babel/register`.
+
 ## 5.5.3
 
  * **Bug Fix**

CONTRIBUTING.md

@@ -12,6 +12,8 @@
    <strong><a href="#dependencies">Dependencies</a></strong>
    |
    <strong><a href="#code-standards">Code Standards</a></strong>
+   |
+   <strong><a href="#internals">Internals</a></strong>
 </p>
 
 ----
@@ -22,11 +24,10 @@ Contributions are always welcome, no matter how large or small. Before
 contributing, please read the
 [code of conduct](https://github.com/babel/babel/blob/master/CODE_OF_CONDUCT.md).
 
-
 ## Developing
 
->Note: Babel moves fast. Only the latest release is guaranteed to build correctly.
->Older releases are not officially supported. If you attempt to build them, do that at your own risk.
+> Note: Babel moves fast. Only the latest release is guaranteed to build correctly.
+> Older releases are not officially supported. If you attempt to build them, do that at your own risk.
 
 #### Setup
 
@@ -173,3 +174,6 @@ your [`$PATH`](http://unix.stackexchange.com/questions/26047/how-to-correctly-ad
  * **Declaration**
    * No unused variables
    * No pollution of global variables and prototypes
+
+#### Internals
+Please see [`/doc`](/doc) for internals documentation relevant to developing babel.

Makefile

@@ -5,6 +5,7 @@ UGLIFY_CMD = node_modules/uglify-js/bin/uglifyjs
 #UGLIFY_CMD = node_modules/uglify-js/bin/uglifyjs --mangle sort
 MOCHA_CMD = node_modules/mocha/bin/_mocha
 BABEL_CMD = node_modules/babel/bin/babel
+BROWSERIFY_IGNORE = -i esprima-fb
 
 export NODE_ENV = test
 
@@ -14,7 +15,7 @@ build-core: clean-core
 	node $(BABEL_CMD) src --out-dir lib --copy-files
 
 build-core-test: clean-core
-	node $(BABEL_CMD) src --out-dir lib --copy-files --auxiliary-comment "istanbul ignore next"
+	node $(BABEL_CMD) src --out-dir lib --copy-files --auxiliary-comment-before "istanbul ignore next"
 
 watch-core: clean-core
 	node $(BABEL_CMD) src --out-dir lib --watch --copy-files
@@ -34,8 +35,10 @@ build:
 	node $(BROWSERIFY_CMD) -e lib/babel/polyfill.js >dist/polyfill.js
 	node $(UGLIFY_CMD) dist/polyfill.js >dist/polyfill.min.js
 
-	node $(BROWSERIFY_CMD) lib/babel/api/browser.js -s babel >dist/babel.js
-	node $(UGLIFY_CMD) dist/babel.js >dist/babel.min.js
+	node $(BROWSERIFY_CMD) lib/babel/api/browser.js -s babel $(BROWSERIFY_IGNORE) >dist/browser.js
+	node $(UGLIFY_CMD) dist/browser.js >dist/browser.min.js
+
+	node $(BROWSERIFY_CMD) lib/babel/api/node.js --node $(BROWSERIFY_IGNORE) >dist/node.js
 
 	node packages/babel-cli/bin/babel-external-helpers >dist/external-helpers.js
 	node $(UGLIFY_CMD) dist/external-helpers.js >dist/external-helpers.min.js
@@ -86,8 +89,8 @@ publish: lint
 
 	make build
 
-	cp dist/babel.js browser.js
-	cp dist/babel.min.js browser.min.js
+	cp dist/browser.js browser.js
+	cp dist/browser.min.js browser.min.js
 
 	cp dist/polyfill.js browser-polyfill.js
 	cp dist/polyfill.min.js browser-polyfill.min.js

README.md

@@ -9,7 +9,7 @@
 </p>
 
 <p align="center">
-  For questions and support please visit the <a href="https://gitter.im/babel/babel">gitter room</a> or <a href="http://stackoverflow.com/questions/tagged/babeljs">StackOverflow</a>. The Babel issue tracker is <strong>exclusively</strong> for bug reports and feature requests.
+  For questions and support please visit the <a href="https://babel-slack.herokuapp.com">slack channel</a> or <a href="http://stackoverflow.com/questions/tagged/babeljs">StackOverflow</a>. The Babel issue tracker is <strong>exclusively</strong> for bug reports and feature requests.
 </p>
 
 <p align="center">

doc/index.md

@@ -0,0 +1,4 @@
+This is a collection of documentation about babel internals, for use in development of babel.
+
+# [Properties of nodes](/doc/node-props.md)
+These are properties babel stores in AST node objects for internal use, as opposed to properties that are part of the AST spec (ESTree at the time of this writing).

doc/node-props.md

@@ -0,0 +1,11 @@
+# Properties of nodes
+These are properties babel stores in AST node objects for internal use, as opposed to properties that are part of the AST spec (ESTree at the time of this writing).
+
+## `_blockHoist`
+`node._blockHoist != null` triggers the [block-hoist transformer](/src/babel/transformation/transformers/internal/block-hoist.js). Value should be `true` or an integer in the range `0..3`. `true` is equivalent to `2`. The value indicates whether the node should be hoisted and to what degree. See the source code for more detailed information.
+
+## `_paths`
+Stores a representation of a node's position in the tree and relationship to other nodes.
+
+## `shadow`
+A truthy value on a function node triggers the [shadow-functions transformer](/src/babel/transformation/transformers/internal/shadow-functions.js), which transforms the node so that it references (or inherits) `arguments` and `this` from the parent scope. It is invoked for arrow functions, for example.

package.json

@@ -1,7 +1,7 @@
 {
   "name": "babel-core",
   "description": "A compiler for writing next generation JavaScript",
-  "version": "5.5.3",
+  "version": "5.6.3",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
   "license": "MIT",
@@ -30,20 +30,33 @@
   "dependencies": {
     "acorn-jsx": "^1.0.0",
     "ast-types": "~0.7.0",
-    "bluebird": "^2.9.25",
+    "babel-plugin-constant-folding": "^1.0.1",
+    "babel-plugin-dead-code-elimination": "^1.0.1",
+    "babel-plugin-eval": "^1.0.1",
+    "babel-plugin-inline-environment-variables": "^1.0.1",
+    "babel-plugin-jscript": "^1.0.1",
+    "babel-plugin-member-expression-literals": "^1.0.1",
+    "babel-plugin-property-literals": "^1.0.1",
+    "babel-plugin-proto-to-assign": "^1.0.3",
+    "babel-plugin-react-constant-elements": "^1.0.3",
+    "babel-plugin-react-display-name": "^1.0.3",
+    "babel-plugin-remove-console": "^1.0.1",
+    "babel-plugin-remove-debugger": "^1.0.1",
+    "babel-plugin-runtime": "^1.0.7",
+    "babel-plugin-undeclared-variables-check": "^1.0.2",
+    "babel-plugin-undefined-to-void": "^1.1.6",
     "chalk": "^1.0.0",
     "convert-source-map": "^1.1.0",
     "core-js": "^0.9.0",
     "debug": "^2.1.1",
     "detect-indent": "^3.0.0",
-    "esquery": "^0.4.0",
     "estraverse": "^4.0.0",
     "esutils": "^2.0.0",
     "fs-readdir-recursive": "^0.1.0",
     "globals": "^6.4.0",
     "home-or-tmp": "^1.0.0",
     "is-integer": "^1.0.4",
-    "js-tokens": "1.0.0",
+    "js-tokens": "1.0.1",
     "leven": "^1.0.1",
     "line-numbers": "0.2.0",
     "lodash": "^3.6.0",
@@ -51,7 +64,7 @@
     "output-file-sync": "^1.1.0",
     "path-is-absolute": "^1.0.0",
     "private": "^0.1.6",
-    "regenerator": "^0.8.28",
+    "regenerator": "0.8.30",
     "regexpu": "^1.1.2",
     "repeating": "^1.1.2",
     "resolve": "^1.1.6",
@@ -64,7 +77,7 @@
     "trim-right": "^1.0.0"
   },
   "devDependencies": {
-    "babel": "5.3.1",
+    "babel": "5.5.7",
     "browserify": "^9.0.8",
     "chai": "^2.2.0",
     "eslint": "^0.21.2",

packages/babel-cli/bin/babel-plugin/index.js

@@ -0,0 +1,140 @@
+#!/usr/bin/env node
+
+var readline = require("readline");
+var child    = require("child_process");
+var path     = require("path");
+var fs       = require("fs");
+
+function spawn(cmd, args, callback) {
+  console.log(">", cmd, args);
+
+  var spawn = child.spawn(cmd, args, { stdio: "inherit" });
+
+  spawn.on("exit", function (code) {
+    if (code === 0) {
+      if (callback) callback();
+    } else {
+      console.log("Killing...");
+      process.exit(1);
+    }
+  });
+}
+
+function spawnMultiple(cmds) {
+  function next() {
+    var cmd = cmds.shift();
+    if (cmd) {
+      spawn(cmd.command, cmd.args, next);
+    } else {
+      process.exit();
+    }
+  }
+
+  next();
+}
+
+function template(name, data) {
+  var source = fs.readFileSync(__dirname + "/templates/" + name, "utf8");
+  source = source.replace(/[A-Z_]+/g, function (key) {
+    return data[key] === undefined ? key : data[key];
+  });
+  return source;
+}
+
+function write(filename, content) {
+  console.log(filename);
+  fs.writeFileSync(filename, content);
+}
+
+var rl = readline.createInterface({
+  input: process.stdin,
+  output: process.stdout
+});
+
+var BABEL_PLUGIN_PREFIX = "babel-plugin-";
+
+var cmds = {
+  init: function () {
+    var name = path.basename(process.cwd());
+
+    if (name.indexOf(BABEL_PLUGIN_PREFIX) === 0) {
+      name = name.slice(BABEL_PLUGIN_PREFIX.length);
+    }
+
+    rl.question("Description (optional): ", function (description) {
+      rl.question("GitHub Repository (eg. sebmck/babel-plugin-foobar) (optional): ", function (repo) {
+        rl.close();
+
+        var templateData = {
+          DESCRIPTION: description,
+          FULL_NAME: BABEL_PLUGIN_PREFIX + name,
+          NAME: name
+        };
+
+        write("package.json", JSON.stringify({
+          name: templateData.FULL_NAME,
+          version: "1.0.0",
+          description: templateData.DESCRIPTION,
+          repository: repo || undefined,
+          license: "MIT",
+          main: "lib/index.js",
+
+          devDependencies: {
+            babel: "^5.6.0"
+          },
+
+          scripts: {
+            build: "babel-plugin build",
+            push:  "babel-plugin publish",
+            test:  "babel-plugin test"
+          },
+
+          keywords: ["babel-plugin"]
+        }, null, "  ") + "\n");
+
+        write(".npmignore", "node_modules\n*.log\nsrc\n");
+
+        write(".gitignore", "node_modules\n*.log\nlib\n");
+
+        write("README.md", template("README.md", templateData));
+
+        if (!fs.existsSync("src")) {
+          fs.mkdirSync("src");
+          write("src/index.js", template("index.js", templateData));
+        }
+      });
+    });
+  },
+
+  build: function () {
+    spawn("babel", ["src", "--out-dir", "lib", "--copy-files"]);
+  },
+
+  publish: function () {
+    var pkg = require(process.cwd() + "/package.json");
+    console.log("Current verison:", pkg.version);
+
+    rl.question("New version (enter nothing for patch): ", function (newVersion) {
+      rl.close();
+
+      newVersion = newVersion || "patch";
+
+      spawnMultiple([
+        { command: "git", args: ["pull"] },
+        { command: "git", args: ["push"] },
+        { command: "babel-plugin", args: ["build"] },
+        { command: "npm", args: ["version", newVersion] },
+        { command: "npm", args: ["publish"] },
+        { command: "git", args: ["push", "--follow-tags"] }
+      ]);
+    });
+  }
+};
+
+var cmd = cmds[process.argv[2]];
+if (cmd) {
+  cmd();
+} else {
+  console.error("Unknown command:", cmd);
+  process.exit(1);
+}

packages/babel-cli/bin/babel-plugin/templates/README.md

@@ -0,0 +1,35 @@
+# FULL_NAME
+
+DESCRIPTION
+
+## Installation
+
+```sh
+$ npm install FULL_NAME
+```
+
+## Usage
+
+### Via `.babelrc` (Recommended)
+
+**.babelrc**
+
+```json
+{
+  "plugins": ["NAME"]
+}
+```
+
+### Via CLI
+
+```sh
+$ babel --plugins NAME script.js
+```
+
+### Via Node API
+
+```javascript
+require("babel-core").transform("code", {
+  plugins: ["NAME"]
+});
+```

packages/babel-cli/bin/babel-plugin/templates/index.js

@@ -0,0 +1,7 @@
+export default function ({ Plugin, types: t }) {
+  return new Plugin("NAME", {
+    visitor: {
+      // your visitor methods go here
+    }
+  });
+}

packages/babel-cli/bin/babel/index.js

@@ -6,6 +6,7 @@ var transform        = require("babel-core").transform;
 var kebabCase        = require("lodash/string/kebabCase");
 var options          = require("babel-core").options;
 var util             = require("babel-core").util;
+var uniq             = require("lodash/array/uniq");
 var each             = require("lodash/collection/each");
 var keys             = require("lodash/object/keys");
 var fs               = require("fs");
@@ -35,7 +36,7 @@ each(options, function (option, key) {
   if (option.description) desc.push(option.description);
 
   commander.option(arg, desc.join(" "));
-})
+});
 
 commander.option("-x, --extensions [extensions]", "List of extensions to compile when a directory has been input [.es6,.js,.es,.jsx]");
 commander.option("-w, --watch", "Recompile files on changes");
@@ -51,7 +52,7 @@ commander.on("--help", function () {
     each(keys(obj).sort(), function (key) {
       if (key[0] === "_") return;
 
-      if (obj[key].optional) key = "[" + key + "]";
+      if (obj[key].metadata && obj[key].metadata.optional) key = "[" + key + "]";
 
       console.log("    - " + key);
     });
@@ -84,6 +85,8 @@ var filenames = commander.args.reduce(function (globbed, input) {
   return globbed.concat(files);
 }, []);
 
+filenames = uniq(filenames);
+
 each(filenames, function (filename) {
   if (!fs.existsSync(filename)) {
     errors.push(filename + " doesn't exist");
@@ -118,11 +121,16 @@ if (errors.length) {
 var opts = exports.opts = {};
 
 each(options, function (opt, key) {
-  opts[key] = commander[key];
+  if (commander[key] !== undefined) {
+    opts[key] = commander[key];
+  }
 });
 
 opts.ignore = util.arrayify(opts.ignore, util.regexify);
-opts.only   = util.arrayify(opts.only, util.regexify);
+
+if (opts.only) {
+  opts.only = util.arrayify(opts.only, util.regexify);
+}
 
 var fn;
 

packages/babel-cli/bin/babel/util.js

@@ -1,10 +1,11 @@
-var readdir = require("fs-readdir-recursive");
-var index   = require("./index");
-var babel   = require("babel-core");
-var util    = require("babel-core").util;
-var path    = require("path");
-var fs      = require("fs");
-var _       = require("lodash");
+var commander = require("commander");
+var readdir   = require("fs-readdir-recursive");
+var index     = require("./index");
+var babel     = require("babel-core");
+var util      = require("babel-core").util;
+var path      = require("path");
+var fs        = require("fs");
+var _         = require("lodash");
 
 exports.readdirFilter = function (filename) {
   return readdir(filename).filter(function (filename) {
@@ -37,6 +38,15 @@ exports.transform = function (filename, code, opts) {
 };
 
 exports.compile = function (filename, opts) {
-  var code = fs.readFileSync(filename, "utf8");
-  return exports.transform(filename, code, opts);
+  try {
+    var code = fs.readFileSync(filename, "utf8");
+    return exports.transform(filename, code, opts);
+  } catch (err) {
+    if (commander.watch) {
+      console.error(err.stack);
+      return { ignored: true };
+    } else {
+      throw err;
+    }
+  }
 };

packages/babel-cli/package.json

@@ -1,14 +1,14 @@
 {
   "name": "babel",
   "description": "Turn ES6 code into readable vanilla ES5 with source maps",
-  "version": "5.5.2",
+  "version": "5.6.2",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
   "license": "MIT",
   "repository": "babel/babel",
   "preferGlobal": true,
   "dependencies": {
-    "babel-core": "^5.5.2",
+    "babel-core": "^5.6.2",
     "chokidar": "^1.0.0",
     "commander": "^2.6.0",
     "convert-source-map": "^1.1.0",
@@ -23,6 +23,7 @@
   "bin": {
     "babel": "./bin/babel/index.js",
     "babel-node": "./bin/babel-node",
-    "babel-external-helpers": "./bin/babel-external-helpers"
+    "babel-external-helpers": "./bin/babel-external-helpers",
+    "babel-plugin": "./bin/babel-plugin/index.js"
   }
 }

packages/babel-runtime/package.json

@@ -1,7 +1,7 @@
 {
   "name": "babel-runtime",
   "description": "babel selfContained runtime",
-  "version": "5.5.2",
+  "version": "5.6.2",
   "license": "MIT",
   "repository": "babel/babel",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",

packages/build-runtime.js

@@ -75,7 +75,7 @@ writeFile("regenerator/runtime.js", selfContainify(readFile("regenerator/runtime
 
 //
 
-var coreDefinitions = require("../lib/babel/transformation/transformers/other/runtime/definitions");
+var coreDefinitions = require("babel-plugin-runtime/lib/definitions");
 
 var paths = ["is-iterable", "get-iterator"];
 

src/acorn/src/expression.js

@@ -29,14 +29,23 @@ const pp = Parser.prototype
 // strict mode, init properties are also not allowed to be repeated.
 
 pp.checkPropClash = function(prop, propHash) {
-  if (this.options.ecmaVersion >= 6) return
+  if (this.options.ecmaVersion >= 6 && (prop.computed || prop.method || prop.shorthand))
+    return
   let key = prop.key, name
   switch (key.type) {
   case "Identifier": name = key.name; break
   case "Literal": name = String(key.value); break
   default: return
   }
-  let kind = prop.kind || "init", other
+  let kind = prop.kind
+  if (this.options.ecmaVersion >= 6) {
+    if (name === "__proto__" && kind === "init") {
+      if (propHash.proto) this.raise(key.start, "Redefinition of __proto__ property");
+      propHash.proto = true
+    }
+    return
+  }
+  let other
   if (has(propHash, name)) {
     other = propHash[name]
     let isGetSet = kind !== "init"
@@ -260,8 +269,10 @@ pp.parseNoCallExpr = function() {
 pp.parseExprAtom = function(refShorthandDefaultPos) {
   let node, canBeArrow = this.potentialArrowAt == this.start
   switch (this.type) {
-  case tt._this:
   case tt._super:
+    if (!this.inFunction)
+      this.raise(this.start, "'super' outside of function or class")
+  case tt._this:
     let type = this.type === tt._this ? "ThisExpression" : "Super"
     node = this.startNode()
     this.next()
@@ -292,7 +303,7 @@ pp.parseExprAtom = function(refShorthandDefaultPos) {
     //
     if (this.options.features["es7.asyncFunctions"]) {
       // async functions!
-      if (id.name === "async") {
+      if (id.name === "async" && !this.canInsertSemicolon()) {
         // arrow functions
         if (this.type === tt.parenL) {
           let expr = this.parseParenAndDistinguishExpression(start, true, true)
@@ -609,6 +620,14 @@ pp.parseObjPropValue = function (prop, start, isGenerator, isAsync, isPattern, r
     prop.kind = prop.key.name
     this.parsePropertyName(prop)
     prop.value = this.parseMethod(false)
+    let paramCount = prop.kind === "get" ? 0 : 1
+    if (prop.value.params.length !== paramCount) {
+      let start = prop.value.start
+      if (prop.kind === "get")
+        this.raise(start, "getter should have no params");
+      else
+        this.raise(start, "setter should have exactly one param")
+    }
   } else if (this.options.ecmaVersion >= 6 && !prop.computed && prop.key.type === "Identifier") {
     prop.kind = "init"
     if (isPattern) {
@@ -634,12 +653,12 @@ pp.parsePropertyName = function(prop) {
       prop.computed = true
       prop.key = this.parseMaybeAssign()
       this.expect(tt.bracketR)
-      return
+      return prop.key
     } else {
       prop.computed = false
     }
   }
-  prop.key = (this.type === tt.num || this.type === tt.string) ? this.parseExprAtom() : this.parseIdent(true)
+  return prop.key = (this.type === tt.num || this.type === tt.string) ? this.parseExprAtom() : this.parseIdent(true)
 }
 
 // Initialize empty function node.

src/acorn/src/lookahead.js

@@ -9,6 +9,7 @@ var STATE_KEYS = [
   "lastTokEnd",
   "lineStart",
   "startLoc",
+  "curLine",
   "endLoc",
   "start",
   "pos",

src/acorn/src/lval.js

@@ -35,6 +35,7 @@ pp.toAssignable = function(node, isBinding) {
     case "AssignmentExpression":
       if (node.operator === "=") {
         node.type = "AssignmentPattern"
+        delete node.operator
       } else {
         this.raise(node.left.end, "Only '=' operator can be used for specifying default value.")
       }
@@ -171,7 +172,7 @@ pp.checkLVal = function(expr, isBinding, checkClashes) {
     break
 
   case "ObjectPattern":
-    for (let i = 0; i < expr.properties.length; i++) {
+       for (let i = 0; i < expr.properties.length; i++) {
       var prop = expr.properties[i];
       if (prop.type === "Property") prop = prop.value;
       this.checkLVal(prop, isBinding, checkClashes)
@@ -194,6 +195,10 @@ pp.checkLVal = function(expr, isBinding, checkClashes) {
     this.checkLVal(expr.argument, isBinding, checkClashes)
     break
 
+  case "ParenthesizedExpression":
+    this.checkLVal(expr.expression, isBinding, checkClashes)
+    break
+
   default:
     this.raise(expr.start, (isBinding ? "Binding" : "Assigning to") + " rvalue")
   }

src/acorn/src/state.js

@@ -1,5 +1,6 @@
 import {reservedWords, keywords} from "./identifier"
-import {types as tt, lineBreak} from "./tokentype"
+import {types as tt} from "./tokentype"
+import {lineBreak} from "./whitespace"
 
 export function Parser(options, input, startPos) {
   this.options = options

src/acorn/src/statement.js

@@ -83,10 +83,13 @@ pp.parseStatement = function(declaration, topLevel) {
     return starttype === tt._import ? this.parseImport(node) : this.parseExport(node)
 
   case tt.name:
-    if (this.options.features["es7.asyncFunctions"] && this.value === "async" && this.lookahead().type === tt._function) {
-      this.next();
-      this.expect(tt._function);
-      return this.parseFunction(node, true, false, true);
+    if (this.options.features["es7.asyncFunctions"] && this.value === "async") {
+      var lookahead = this.lookahead();
+      if (lookahead.type === tt._function && !this.canInsertSemicolon.call(lookahead)) {
+        this.next();
+        this.expect(tt._function);
+        return this.parseFunction(node, true, false, true);
+      }
     }
 
     // If the statement does not start with a statement keyword or a
@@ -344,7 +347,14 @@ pp.parseLabeledStatement = function(node, maybeName, expr) {
   for (let i = 0; i < this.labels.length; ++i)
     if (this.labels[i].name === maybeName) this.raise(expr.start, "Label '" + maybeName + "' is already declared")
   let kind = this.type.isLoop ? "loop" : this.type === tt._switch ? "switch" : null
-  this.labels.push({name: maybeName, kind: kind})
+  for (let i = this.labels.length - 1; i >= 0; i--) {
+    let label = this.labels[i]
+    if (label.statementStart == node.start) {
+      label.statementStart = this.start;
+      label.kind = kind;
+    } else break;
+  }
+  this.labels.push({name: maybeName, kind: kind, statementStart: this.start})
   node.body = this.parseStatement(true)
   this.labels.pop()
   node.label = expr
@@ -463,6 +473,7 @@ pp.parseClass = function(node, isStatement) {
   this.parseClassId(node, isStatement)
   this.parseClassSuper(node)
   var classBody = this.startNode()
+  let hadConstructor = false
   classBody.body = []
   this.expect(tt.braceL)
   let decorators = []
@@ -477,16 +488,14 @@ pp.parseClass = function(node, isStatement) {
       method.decorators = decorators
       decorators = []
     }
+    let isMaybeStatic = this.type === tt.name && this.value === "static"
     var isGenerator = this.eat(tt.star), isAsync = false
     this.parsePropertyName(method)
-    if (this.type !== tt.parenL && !method.computed && method.key.type === "Identifier" &&
-        method.key.name === "static") {
+    method.static = isMaybeStatic && this.type !== tt.parenL
+    if (method.static) {
       if (isGenerator) this.unexpected()
-      method['static'] = true
       isGenerator = this.eat(tt.star)
       this.parsePropertyName(method)
-    } else {
-      method['static'] = false
     }
     if (!isGenerator && method.key.type === "Identifier" && !method.computed && this.isClassProperty()) {
       classBody.body.push(this.parseClassProperty(method))
@@ -497,23 +506,39 @@ pp.parseClass = function(node, isStatement) {
       isAsync = true
       this.parsePropertyName(method)
     }
+    let isGetSet = false
     method.kind = "method"
-    if (!method.computed && !isGenerator && !isAsync) {
-      if (method.key.type === "Identifier") {
-        if (this.type !== tt.parenL && (method.key.name === "get" || method.key.name === "set")) {
-          method.kind = method.key.name
-          this.parsePropertyName(method)
-        } else if (!method['static'] && method.key.name === "constructor") {
-          method.kind = "constructor"
-        }
-      } else if (!method['static'] && method.key.type === "Literal" && method.key.value === "constructor") {
+    if (!method.computed) {
+      let {key} = method
+      if (!isAsync && !isGenerator && key.type === "Identifier" && this.type !== tt.parenL && (key.name === "get" || key.name === "set")) {
+        isGetSet = true
+        method.kind = key.name
+        key = this.parsePropertyName(method)
+      }
+      if (!method.static && (key.type === "Identifier" && key.name === "constructor" ||
+          key.type === "Literal" && key.value === "constructor")) {
+        if (hadConstructor) this.raise(key.start, "Duplicate constructor in the same class")
+        if (isGetSet) this.raise(key.start, "Constructor can't have get/set modifier")
+        if (isGenerator) this.raise(key.start, "Constructor can't be a generator")
+        if (isAsync) this.raise(key.start, "Constructor can't be an async function")
         method.kind = "constructor"
+        hadConstructor = true
       }
     }
     if (method.kind === "constructor" && method.decorators) {
       this.raise(method.start, "You can't attach decorators to a class constructor")
     }
     this.parseClassMethod(classBody, method, isGenerator, isAsync)
+    if (isGetSet) {
+      let paramCount = method.kind === "get" ? 0 : 1
+      if (method.value.params.length !== paramCount) {
+        let start = method.value.start
+        if (method.kind === "get")
+          this.raise(start, "getter should have no params");
+        else
+          this.raise(start, "setter should have exactly one param")
+      }
+    }
   }
   if (decorators.length) {
     this.raise(this.start, "You have trailing decorators with no method");

src/acorn/src/tokenize.js

@@ -25,6 +25,9 @@ export class Token {
 
 const pp = Parser.prototype
 
+// Are we running under Rhino?
+const isRhino = typeof Packages == "object" && Object.prototype.toString.call(Packages) == "[object JavaPackage]"
+
 // Move to the next token
 
 pp.next = function() {
@@ -430,23 +433,30 @@ pp.readRegexp = function() {
       // negatives in unlikely scenarios. For example, `[\u{61}-b]` is a
       // perfectly valid pattern that is equivalent to `[a-b]`, but it would
       // be replaced by `[x-b]` which throws an error.
-      tmp = tmp.replace(/\\u([a-fA-F0-9]{4})|\\u\{([0-9a-fA-F]+)\}|[\uD800-\uDBFF][\uDC00-\uDFFF]/g, "x")
+      tmp = tmp.replace(/\\u\{([0-9a-fA-F]+)\}/g, (match, code, offset) => {
+        code = Number("0x" + code)
+        if (code > 0x10FFFF) this.raise(start + offset + 3, "Code point out of bounds")
+        return "x"
+      });
+      tmp = tmp.replace(/\\u([a-fA-F0-9]{4})|[\uD800-\uDBFF][\uDC00-\uDFFF]/g, "x")
     }
   }
   // Detect invalid regular expressions.
-  try {
-    new RegExp(tmp)
-  } catch (e) {
-    if (e instanceof SyntaxError) this.raise(start, "Error parsing regular expression: " + e.message)
-    this.raise(e)
-  }
-  // Get a regular expression object for this pattern-flag pair, or `null` in
-  // case the current environment doesn't support the flags it uses.
-  let value
-  try {
-    value = new RegExp(content, mods)
-  } catch (err) {
-    value = null
+  let value = null
+  // Rhino's regular expression parser is flaky and throws uncatchable exceptions,
+  // so don't do detection if we are running under Rhino
+  if (!isRhino) {
+    try {
+      new RegExp(tmp)
+    } catch (e) {
+      if (e instanceof SyntaxError) this.raise(start, "Error parsing regular expression: " + e.message)
+      this.raise(e)
+    }
+    // Get a regular expression object for this pattern-flag pair, or `null` in
+    // case the current environment doesn't support the flags it uses.
+    try {
+      value = new RegExp(content, mods)
+    } catch (err) {}
   }
   return this.finishToken(tt.regexp, {pattern: content, flags: mods, value: value})
 }
@@ -514,10 +524,10 @@ pp.readCodePoint = function() {
 
   if (ch === 123) {
     if (this.options.ecmaVersion < 6) this.unexpected()
-    ++this.pos
+    let codePos = ++this.pos
     code = this.readHexChar(this.input.indexOf('}', this.pos) - this.pos)
     ++this.pos
-    if (code > 0x10FFFF) this.unexpected()
+    if (code > 0x10FFFF) this.raise(codePos, "Code point out of bounds")
   } else {
     code = this.readHexChar(4)
   }
@@ -539,7 +549,7 @@ pp.readString = function(quote) {
     if (ch === quote) break
     if (ch === 92) { // '\'
       out += this.input.slice(chunkStart, this.pos)
-      out += this.readEscapedChar()
+      out += this.readEscapedChar(false)
       chunkStart = this.pos
     } else {
       if (isNewLine(ch)) this.raise(this.start, "Unterminated string constant")
@@ -572,7 +582,7 @@ pp.readTmplToken = function() {
     }
     if (ch === 92) { // '\'
       out += this.input.slice(chunkStart, this.pos)
-      out += this.readEscapedChar()
+      out += this.readEscapedChar(true)
       chunkStart = this.pos
     } else if (isNewLine(ch)) {
       out += this.input.slice(chunkStart, this.pos)
@@ -600,42 +610,46 @@ pp.readTmplToken = function() {
 
 // Used to read escaped characters
 
-pp.readEscapedChar = function() {
+pp.readEscapedChar = function(inTemplate) {
   let ch = this.input.charCodeAt(++this.pos)
-  let octal = /^[0-7]+/.exec(this.input.slice(this.pos, this.pos + 3))
-  if (octal) octal = octal[0]
-  while (octal && parseInt(octal, 8) > 255) octal = octal.slice(0, -1)
-  if (octal === "0") octal = null
   ++this.pos
-  if (octal) {
-    if (this.strict) this.raise(this.pos - 2, "Octal literal in strict mode")
-    this.pos += octal.length - 1
-    return String.fromCharCode(parseInt(octal, 8))
-  } else {
-    switch (ch) {
-    case 110: return "\n"; // 'n' -> '\n'
-    case 114: return "\r"; // 'r' -> '\r'
-    case 120: return String.fromCharCode(this.readHexChar(2)); // 'x'
-    case 117: return codePointToString(this.readCodePoint()); // 'u'
-    case 116: return "\t"; // 't' -> '\t'
-    case 98: return "\b"; // 'b' -> '\b'
-    case 118: return "\u000b"; // 'v' -> '\u000b'
-    case 102: return "\f"; // 'f' -> '\f'
-    case 48: return "\0"; // 0 -> '\0'
-    case 13: if (this.input.charCodeAt(this.pos) === 10) ++this.pos; // '\r\n'
-    case 10: // ' \n'
-      if (this.options.locations) { this.lineStart = this.pos; ++this.curLine }
-      return ""
-    default: return String.fromCharCode(ch)
+  switch (ch) {
+  case 110: return "\n"; // 'n' -> '\n'
+  case 114: return "\r"; // 'r' -> '\r'
+  case 120: return String.fromCharCode(this.readHexChar(2)); // 'x'
+  case 117: return codePointToString(this.readCodePoint()); // 'u'
+  case 116: return "\t"; // 't' -> '\t'
+  case 98: return "\b"; // 'b' -> '\b'
+  case 118: return "\u000b"; // 'v' -> '\u000b'
+  case 102: return "\f"; // 'f' -> '\f'
+  case 13: if (this.input.charCodeAt(this.pos) === 10) ++this.pos; // '\r\n'
+  case 10: // ' \n'
+    if (this.options.locations) { this.lineStart = this.pos; ++this.curLine }
+    return ""
+  default:
+    if (ch >= 48 && ch <= 55) {
+      let octalStr = this.input.substr(this.pos - 1, 3).match(/^[0-7]+/)[0]
+      let octal = parseInt(octalStr, 8)
+      if (octal > 255) {
+        octalStr = octalStr.slice(0, -1)
+        octal = parseInt(octalStr, 8)
+      }
+      if (octal > 0 && (this.strict || inTemplate)) {
+        this.raise(this.pos - 2, "Octal literal in strict mode")
+      }
+      this.pos += octalStr.length - 1
+      return String.fromCharCode(octal)
     }
+    return String.fromCharCode(ch)
   }
 }
 
 // Used to read character escape sequences ('\x', '\u', '\U').
 
 pp.readHexChar = function(len) {
+  let codePos = this.pos
   let n = this.readInt(16, len)
-  if (n === null) this.raise(this.start, "Bad character escape sequence")
+  if (n === null) this.raise(codePos, "Bad character escape sequence")
   return n
 }
 

src/babel/api/node.js

@@ -8,9 +8,10 @@ export { util, acorn, transform };
 export { pipeline } from "../transformation";
 export { canCompile } from "../util";
 
-export { default as options } from "../transformation/file/options";
+export { default as options } from "../transformation/file/options/config";
+export { default as Plugin } from "../transformation/plugin";
 export { default as Transformer } from "../transformation/transformer";
-export { default as TransformerPipeline } from "../transformation/transformer-pipeline";
+export { default as Pipeline } from "../transformation/pipeline";
 export { default as traverse } from "../traversal";
 export { default as buildExternalHelpers } from "../tools/build-external-helpers";
 export { version } from "../../../package";

src/babel/api/register/node.js

@@ -1,6 +1,6 @@
 import sourceMapSupport from "source-map-support";
 import * as registerCache from "./cache";
-import resolveRc from "../../tools/resolve-rc";
+import resolveRc from "../../transformation/file/options/resolve-rc";
 import extend from "lodash/object/extend";
 import * as babel from "../node";
 import each from "lodash/collection/each";
@@ -90,7 +90,7 @@ var shouldIgnore = function (filename) {
   if (!ignore && !only) {
     return getRelativePath(filename).split(path.sep).indexOf("node_modules") >= 0;
   } else {
-    return util.shouldIgnore(filename, ignore || [], only || []);
+    return util.shouldIgnore(filename, ignore || [], only);
   }
 };
 
@@ -105,7 +105,7 @@ if (process.env.running_under_istanbul) {
     if (istanbulMonkey[filename]) {
       delete istanbulMonkey[filename];
       var code = compile(filename, {
-        attachAuxiliaryComment: "istanbul ignore next"
+        auxiliaryCommentBefore: "istanbul ignore next"
       });
       istanbulMonkey[filename] = true;
       return code;
@@ -125,7 +125,7 @@ var normalLoader = function (m, filename) {
 };
 
 var registerExtension = function (ext) {
-  var old = oldHandlers[ext] || oldHandlers[".js"];
+  var old = oldHandlers[ext] || oldHandlers[".js"] || require.extensions[".js"];
 
   var loader = normalLoader;
   if (process.env.running_under_istanbul) loader = istanbulLoader;

src/babel/generation/generators/base.js

@@ -17,3 +17,7 @@ export function BlockStatement(node, print) {
     this.rightBrace();
   }
 }
+
+export function Noop() {
+
+}

src/babel/generation/generators/expressions.js

@@ -1,4 +1,3 @@
-import isInteger from "is-integer";
 import isNumber from "lodash/lang/isNumber";
 import * as t from "../../types";
 
@@ -70,6 +69,7 @@ export function Super() {
 export function Decorator(node, print) {
   this.push("@");
   print.plain(node.expression);
+  this.newline();
 }
 
 export function CallExpression(node, print) {
@@ -126,6 +126,12 @@ export function ExpressionStatement(node, print) {
   this.semicolon();
 }
 
+export function AssignmentPattern(node, print) {
+  print.plain(node.left);
+  this.push(" = ");
+  print.plain(node.right);
+}
+
 export function AssignmentExpression(node, print) {
   // todo: add cases where the spaces can be dropped when in compact mode
   print.plain(node.left);
@@ -143,12 +149,9 @@ export function BindExpression(node, print) {
 
 export {
   AssignmentExpression as BinaryExpression,
-  AssignmentExpression as LogicalExpression,
-  AssignmentExpression as AssignmentPattern
+  AssignmentExpression as LogicalExpression
 };
 
-var SCIENTIFIC_NOTATION = /e/i;
-
 export function MemberExpression(node, print) {
   var obj = node.object;
   print.plain(obj);
@@ -167,11 +170,6 @@ export function MemberExpression(node, print) {
     print.plain(node.property);
     this.push("]");
   } else {
-    // 5..toFixed(2);
-    if (t.isLiteral(obj) && isInteger(obj.value) && !SCIENTIFIC_NOTATION.test(obj.value.toString())) {
-      this.push(".");
-    }
-
     this.push(".");
     print.plain(node.property);
   }

src/babel/generation/generators/types.js

@@ -1,5 +1,6 @@
 /* eslint quotes: 0 */
 
+import isInteger from "is-integer";
 import * as t from "../../types";
 
 export function Identifier(node) {
@@ -90,14 +91,29 @@ export function ArrayExpression(node, print) {
 
 export { ArrayExpression as ArrayPattern };
 
-export function Literal(node) {
+const SCIENTIFIC_NOTATION = /e/i;
+
+export function Literal(node, print, parent) {
   var val  = node.value;
   var type = typeof val;
 
   if (type === "string") {
     this._stringLiteral(val);
   } else if (type === "number") {
-    this.push(val + "");
+    // check to see if this is the same number as the raw one in the original source as asm.js uses
+    // numbers in the form 5.0 for type hinting
+    var raw = node.raw;
+    if (val === +raw && raw[raw.length - 1] !== "." && !/^0[bo]/i.test(raw)) {
+      val = raw;
+    }
+
+    val = val + "";
+
+    if (isInteger(+val) && t.isMemberExpression(parent, { object: node }) && !SCIENTIFIC_NOTATION.test(val)) {
+      val += ".";
+    }
+
+    this.push(val);
   } else if (type === "boolean") {
     this.push(val ? "true" : "false");
   } else if (node.regex) {
@@ -116,9 +132,16 @@ export function _stringLiteral(val) {
   });
 
   if (this.format.quotes === "single") {
+    // remove double quotes
     val = val.slice(1, -1);
+
+    // unescape double quotes
     val = val.replace(/\\"/g, '"');
+
+    // escape single quotes
     val = val.replace(/'/g, "\\'");
+
+    // add single quotes
     val = `'${val}'`;
   }
 

src/babel/generation/index.js

@@ -344,7 +344,7 @@ class CodeGenerator {
 
       //
       if (comment.type === "CommentBlock" && this.format.indent.adjustMultilineComment) {
-        var offset = comment.loc.start.column;
+        var offset = comment.loc && comment.loc.start.column;
         if (offset) {
           var newlineRegex = new RegExp("\\n\\s{1," + offset + "}", "g");
           val = val.replace(newlineRegex, "\n");

src/babel/helpers/code-frame.js

@@ -79,9 +79,11 @@ export default function (lines: number, lineNumber: number, colNumber: number, o
       if (params.number !== lineNumber) {
         return;
       }
+
       if (colNumber) {
         params.line += `\n${params.before}${repeating(" ", params.width)}${params.after}${repeating(" ", colNumber - 1)}^`;
       }
+
       params.before = params.before.replace(/^./, ">");
     }
   }).join("\n");

src/babel/messages.js

@@ -5,17 +5,12 @@ export const MESSAGES = {
   JSXNamespacedTags: "Namespace tags are not supported. ReactJSX is not XML.",
   classesIllegalBareSuper: "Illegal use of bare super",
   classesIllegalSuperCall: "Direct super call is illegal in non-constructor, use super.$1() instead",
-  classesIllegalConstructorKind: "Illegal kind for constructor method",
   scopeDuplicateDeclaration: "Duplicate declaration $1",
-  undeclaredVariable: "Reference to undeclared variable $1",
-  undeclaredVariableSuggestion: "Reference to undeclared variable $1 - did you mean $2?",
-  settersInvalidParamLength: "Setters must have exactly one parameter",
   settersNoRest: "Setters aren't allowed to have a rest",
   noAssignmentsInForHead: "No assignments allowed in for-in/of head",
-  expectedMemberExpressionOrIdentifier: "Expected type MemeberExpression or Identifier",
+  expectedMemberExpressionOrIdentifier: "Expected type MemberExpression or Identifier",
   invalidParentForThisNode: "We don't know how to handle this node within the current parent - please open an issue",
   readOnly: "$1 is read-only",
-  modulesIllegalExportName: "Illegal export $1",
   unknownForHead: "Unknown node type $1 in ForStatement",
   didYouMean: "Did you mean $1?",
   codeGeneratorDeopt: "Note: The code generator has deoptimised the styling of $1 as it exceeds the max of $2.",
@@ -24,6 +19,13 @@ export const MESSAGES = {
   illegalMethodName: "Illegal method name $1",
   lostTrackNodePath: "We lost track of this nodes position, likely because the AST was directly manipulated",
 
+  modulesIllegalExportName: "Illegal export $1",
+  modulesDuplicateDeclarations: "Duplicate module declarations with the same source but in different scopes",
+
+  undeclaredVariable: "Reference to undeclared variable $1",
+  undeclaredVariableType: "Referencing a type alias outside of a type annotation",
+  undeclaredVariableSuggestion: "Reference to undeclared variable $1 - did you mean $2?",
+
   traverseNeedsParent: "Must pass a scope and parentPath unless traversing a Program/File got a $1 node",
   traverseVerifyRootFunction: "You passed `traverse()` a function when it expected a visitor object, are you sure you didn't mean `{ enter: Function }`?",
   traverseVerifyVisitorProperty: "You passed `traverse()` a visitor object with the property $1 that has the invalid property $2",
@@ -32,10 +34,10 @@ export const MESSAGES = {
   pluginIllegalKind: "Illegal kind $1 for plugin $2",
   pluginIllegalPosition: "Illegal position $1 for plugin $2",
   pluginKeyCollision: "The plugin $1 collides with another of the same name",
-  pluginNotTransformer: "The plugin $1 didn't export a Transformer instance",
+  pluginNotTransformer: "The plugin $1 didn't export a Plugin instance",
   pluginUnknown: "Unknown plugin $1",
 
-  transformerNotFile: "Transformer $1 is resolving to a different Babel version to what is doing the actual transformation..."
+  pluginNotFile: "Plugin $1 is resolving to a different Babel version to what is doing the actual transformation..."
 };
 
 export function get(key: String, ...args) {

src/babel/patch.js

@@ -17,6 +17,8 @@ var or  = types.Type.or;
 //  .build("program")
 //  .field("program", def("Program"));
 
+def("Noop");
+
 def("AssignmentPattern")
   .bases("Pattern")
   .build("left", "right")

src/babel/transformation/file/index.js

@@ -1,13 +1,12 @@
+import { validateOption, normaliseOptions, config as optionsConfig } from "./options";
 import convertSourceMap from "convert-source-map";
-import * as optionParsers from "./option-parsers";
 import moduleFormatters from "../modules";
 import PluginManager from "./plugin-manager";
 import shebangRegex from "shebang-regex";
 import NodePath from "../../traversal/path";
-import Transformer from "../transformer";
 import isFunction from "lodash/lang/isFunction";
 import isAbsolute from "path-is-absolute";
-import resolveRc from "../../tools/resolve-rc";
+import resolveRc from "./options/resolve-rc";
 import sourceMap from "source-map";
 import generate from "../../generation";
 import codeFrame from "../../helpers/code-frame";
@@ -16,10 +15,12 @@ import includes from "lodash/collection/includes";
 import traverse from "../../traversal";
 import assign from "lodash/object/assign";
 import Logger from "./logger";
+import Plugin from "../plugin";
 import parse from "../../helpers/parse";
 import merge from "../../helpers/merge";
 import slash from "slash";
 import clone from "lodash/lang/clone";
+import Hub from "../../traversal/hub";
 import * as util from  "../../util";
 import path from "path";
 import * as t from "../../types";
@@ -35,15 +36,27 @@ export default class File {
     this.declarations = {};
     this.usedHelpers  = {};
     this.dynamicData  = {};
-    this.metadata     = {};
     this.data         = {};
 
+    this.metadata = {
+      modules: {
+        imports: [],
+        exports: {
+          exported: [],
+          specifiers: []
+        }
+      }
+    };
+
     this.pipeline = pipeline;
     this.log      = new Logger(this, opts.filename || "unknown");
-    this.opts     = this.normalizeOptions(opts);
     this.ast      = {};
 
+    this.normaliseOptions(opts);
+
     this.buildTransformers();
+
+    this.hub = new Hub(this);
   }
 
   static helpers = [
@@ -85,19 +98,19 @@ export default class File {
 
   static soloHelpers = [];
 
-  static options = require("./options");
+  static options = optionsConfig;
 
-  normalizeOptions(opts: Object) {
-    opts = assign({}, opts);
+  normaliseOptions(opts: Object) {
+    opts = this.opts = normaliseOptions(assign({}, opts));
 
+    // resolve babelrc
     if (opts.filename) {
       var rcFilename = opts.filename;
       if (!isAbsolute(rcFilename)) rcFilename = path.join(process.cwd(), rcFilename);
       opts = resolveRc(rcFilename, opts);
     }
 
-    //
-
+    // check for unknown options
     for (let key in opts) {
       if (key[0] === "_") continue;
 
@@ -105,26 +118,30 @@ export default class File {
       if (!option) this.log.error(`Unknown option: ${key}`, ReferenceError);
     }
 
+    // merge in environment options
     var envKey = process.env.BABEL_ENV || process.env.NODE_ENV || "development";
-    if (opts.env) merge(opts, opts.env[envKey]);
+    if (opts.env) merge(opts, normaliseOptions(opts.env[envKey]));
 
+    // normalise options
     for (let key in File.options) {
       let option = File.options[key];
+      var val    = opts[key];
 
-      var val = opts[key];
+      // optional
       if (!val && option.optional) continue;
 
+      // deprecated
       if (val && option.deprecated) {
-        throw new Error("Deprecated option " + key + ": " + option.deprecated);
+        this.log.deprecate("Deprecated option " + key + ": " + option.deprecated);
       }
 
-      if (val == null) {
-        val = clone(option.default);
-      }
+      // default
+      if (val == null) val = clone(option.default);
 
-      var optionParser = optionParsers[option.type];
-      if (optionParser) val = optionParser(key, val, this.pipeline);
+      // validate
+      if (val) val = validateOption(key, val, this.pipeline);
 
+      // aaliases
       if (option.alias) {
         opts[option.alias] = opts[option.alias] || val;
       } else {
@@ -149,7 +166,10 @@ export default class File {
     opts.basename = path.basename(opts.filename, path.extname(opts.filename));
 
     opts.ignore = util.arrayify(opts.ignore, util.regexify);
-    opts.only   = util.arrayify(opts.only, util.regexify);
+
+    if (opts.only) {
+      opts.only = util.arrayify(opts.only, util.regexify);
+    }
 
     defaults(opts, {
       moduleRoot: opts.sourceRoot
@@ -226,7 +246,7 @@ export default class File {
 
     // build dependency graph
     for (let pass of (stack: Array)) {
-      for (var dep of (pass.transformer.dependencies: Array)) {
+      for (var dep of (pass.plugin.dependencies: Array)) {
         this.transformerDependencies[dep] = pass.key;
       }
     }
@@ -243,7 +263,7 @@ export default class File {
       // been merged
       if (ignore.indexOf(pass) >= 0) continue;
 
-      var group = pass.transformer.metadata.group;
+      var group = pass.plugin.metadata.group;
 
       // can't merge
       if (!pass.canTransform() || !group) {
@@ -253,7 +273,7 @@ export default class File {
 
       var mergeStack = [];
       for (let pass of (_stack: Array)) {
-        if (pass.transformer.metadata.group === group) {
+        if (pass.plugin.metadata.group === group) {
           mergeStack.push(pass);
           ignore.push(pass);
         }
@@ -261,11 +281,11 @@ export default class File {
 
       var visitors = [];
       for (let pass of (mergeStack: Array)) {
-        visitors.push(pass.handlers);
+        visitors.push(pass.plugin.visitor);
       }
       var visitor = traverse.visitors.merge(visitors);
-      var mergeTransformer = new Transformer(group, visitor);
-      stack.push(mergeTransformer.buildPass(this));
+      var mergePlugin = new Plugin(group, { visitor });
+      stack.push(mergePlugin.buildPass(this));
     }
 
     return stack;
@@ -315,7 +335,7 @@ export default class File {
       }
 
       if (this.transformers["es6.modules"].canTransform()) {
-        this.moduleFormatter.importSpecifier(specifiers[0], declar, this.dynamicImports);
+        this.moduleFormatter.importSpecifier(specifiers[0], declar, this.dynamicImports, this.scope);
         this.moduleFormatter.hasLocalImports = true;
       } else {
         this.dynamicImports.push(declar);
@@ -326,14 +346,24 @@ export default class File {
   }
 
   attachAuxiliaryComment(node: Object): Object {
-    var comment = this.opts.auxiliaryComment;
-    if (comment) {
+    var beforeComment = this.opts.auxiliaryCommentBefore;
+    if (beforeComment) {
       node.leadingComments = node.leadingComments || [];
       node.leadingComments.push({
         type: "CommentLine",
-        value: " " + comment
+        value: " " + beforeComment
       });
     }
+
+    var afterComment = this.opts.auxiliaryCommentAfter;
+    if (afterComment) {
+      node.trailingComments = node.trailingComments || [];
+      node.trailingComments.push({
+        type: "CommentLine",
+        value: " " + afterComment
+      });
+    }
+
     return node;
   }
 
@@ -385,11 +415,12 @@ export default class File {
 
   errorWithNode(node, msg, Error = SyntaxError) {
     var err;
-    if (node.loc) {
+    if (node && node.loc) {
       var loc = node.loc.start;
       err = new Error(`Line ${loc.line}: ${msg}`);
       err.loc = loc;
     } else {
+      // todo: find errors with nodes inside to at least point to something
       err = new Error("There's been an error on a dynamic node. This is almost certainly an internal error. Please report it.");
     }
     return err;
@@ -466,12 +497,13 @@ export default class File {
   }
 
   _addAst(ast) {
-    this.path  = NodePath.get({
+    this.path = NodePath.get({
+      hub: this.hub,
       parentPath: null,
       parent: ast,
       container: ast,
       key: "program"
-    }).setContext(null, this);
+    }).setContext();
     this.scope = this.path.scope;
     this.ast   = ast;
   }
@@ -486,15 +518,9 @@ export default class File {
     if (modFormatter.init && this.transformers["es6.modules"].canTransform()) {
       modFormatter.init();
     }
-    this.populateModuleMetadata();
     this.log.debug("End module formatter init");
   }
 
-  populateModuleMetadata() {
-    var modules = {};
-    this.metadata.modules = modules;
-  }
-
   transform() {
     this.call("pre");
     for (var pass of (this.transformerStack: Array)) {
@@ -509,7 +535,11 @@ export default class File {
     code = code + "";
 
     try {
-      return callback();
+      if (this.shouldIgnore()) {
+        return this.makeResult({ code, ignored: true });
+      } else {
+        return callback();
+      }
     } catch (err) {
       if (err._babel) {
         throw err;
@@ -556,7 +586,7 @@ export default class File {
 
   call(key: string) {
     for (var pass of (this.uncollapsedTransformerStack: Array)) {
-      var fn = pass.transformer[key];
+      var fn = pass.plugin[key];
       if (fn) fn(this);
     }
   }

src/babel/transformation/file/option-parsers.js

@@ -1,27 +0,0 @@
-import * as util from  "../../util";
-
-export function transformerList(key, val, pipeline) {
-  val = util.arrayify(val);
-
-  if (val.indexOf("all") >= 0 || val.indexOf(true) >= 0) {
-    val = Object.keys(pipeline.transformers);
-  }
-
-  return pipeline._ensureTransformerNames(key, val);
-}
-
-export function number(key, val) {
-  return +val;
-}
-
-export function boolean(key, val) {
-  return !!val;
-}
-
-export function booleanString(key, val) {
-  return util.booleanify(val);
-}
-
-export function list(key, val) {
-  return util.list(val);
-}

src/babel/transformation/file/options/config.json

@@ -47,6 +47,7 @@
   },
 
   "experimental": {
+    "type": "boolean",
     "description": "allow use of experimental transformers",
     "default": false
   },
@@ -77,7 +78,8 @@
   "blacklist": {
     "type": "transformerList",
     "description": "blacklist of transformers to NOT use",
-    "shorthand": "b"
+    "shorthand": "b",
+    "default": []
   },
 
   "whitelist": {
@@ -89,7 +91,8 @@
 
   "optional": {
     "type": "transformerList",
-    "description": "list of optional transformers to enable"
+    "description": "list of optional transformers to enable",
+    "default": []
   },
 
   "modules": {
@@ -121,12 +124,14 @@
 
   "plugins": {
     "type": "list",
-    "description": ""
+    "description": "",
+    "default": []
   },
 
   "ignore": {
     "type": "list",
-    "description": "list of glob paths to **not** compile"
+    "description": "list of glob paths to **not** compile",
+    "default": []
   },
 
   "only": {
@@ -172,12 +177,23 @@
   },
 
   "auxiliaryComment": {
+    "deprecated": "renamed to auxiliaryCommentBefore",
+    "shorthand": "a",
+    "alias": "auxiliaryCommentBefore"
+  },
+
+  "auxiliaryCommentBefore": {
     "type": "string",
     "default": "",
-    "shorthand": "a",
     "description": "attach a comment before all helper declarations and auxiliary code"
   },
 
+  "auxiliaryCommentAfter": {
+    "type": "string",
+    "default": "",
+    "description": "attach a comment after all helper declarations and auxiliary code"
+  },
+
   "externalHelpers": {
     "type": "boolean",
     "default": false,

src/babel/transformation/file/options/index.js

@@ -0,0 +1,31 @@
+import * as parsers from "./parsers";
+import config from "./config";
+
+export { config };
+
+export function validateOption(key, val, pipeline) {
+  var opt = config[key];
+  var parser = opt && parsers[opt.type];
+  if (parser && parser.validate) {
+    return parser.validate(key, val, pipeline);
+  } else {
+    return val;
+  }
+}
+
+export function normaliseOptions(options = {}) {
+  for (var key in options) {
+    var val = options[key];
+    if (val == null) continue;
+
+    var opt = config[key];
+    if (!opt) continue;
+
+    var parser = parsers[opt.type];
+    if (parser) val = parser(val);
+
+    options[key] = val;
+  }
+
+  return options;
+}

src/babel/transformation/file/options/parsers.js

@@ -0,0 +1,29 @@
+import * as util from "../../../util";
+
+export function transformerList(val) {
+  return util.arrayify(val);
+}
+
+transformerList.validate = function (key, val, pipeline) {
+  if (val.indexOf("all") >= 0 || val.indexOf(true) >= 0) {
+    val = Object.keys(pipeline.transformers);
+  }
+
+  return pipeline._ensureTransformerNames(key, val);
+};
+
+export function number(val) {
+  return +val;
+}
+
+export function boolean(val) {
+  return !!val;
+}
+
+export function booleanString(val) {
+  return util.booleanify(val);
+}
+
+export function list(val) {
+  return util.list(val);
+}

src/babel/transformation/file/options/resolve-rc.js

@@ -1,5 +1,6 @@
 import stripJsonComments from "strip-json-comments";
-import merge from "../helpers/merge";
+import { normaliseOptions } from "./index";
+import merge from "../../../helpers/merge";
 import path from "path";
 import fs from "fs";
 
@@ -34,6 +35,7 @@ export default function (loc, opts = {}) {
 
       try {
         json = jsons[content] = jsons[content] || JSON.parse(stripJsonComments(content));
+        normaliseOptions(json);
       } catch (err) {
         err.message = `${file}: ${err.message}`;
         throw err;
@@ -42,6 +44,7 @@ export default function (loc, opts = {}) {
       opts.babelrc.push(file);
 
       if (json.breakConfig) return;
+
       merge(opts, json);
     }
 

src/babel/transformation/file/plugin-manager.js

@@ -1,5 +1,19 @@
-import * as node from  "../../api/node";
+import Transformer from "../transformer";
+import Plugin from "../plugin";
+import * as types from "../../types";
 import * as messages from "../../messages";
+import traverse from "../../types";
+import parse from "../../helpers/parse";
+
+var context = {
+  messages,
+  Transformer,
+  Plugin,
+  types,
+  parse,
+  traverse
+};
+
 import * as util from  "../../util";
 
 export default class PluginManager {
@@ -11,7 +25,7 @@ export default class PluginManager {
       if (plugin.container === fn) return plugin.transformer;
     }
 
-    var transformer = fn(node);
+    var transformer = fn(context);
     PluginManager.memoisedPlugins.push({
       container: fn,
       transformer: transformer
@@ -55,7 +69,7 @@ export default class PluginManager {
     }
 
     // validate Transformer instance
-    if (!plugin.buildPass || plugin.constructor.name !== "Transformer") {
+    if (!plugin.buildPass || plugin.constructor.name !== "Plugin") {
       throw new TypeError(messages.get("pluginNotTransformer", name));
     }
 

src/babel/transformation/helpers/build-react-transformer.js

@@ -9,8 +9,10 @@ import esutils from "esutils";
 import * as react from "./react";
 import * as t from "../../types";
 
-export default function (exports, opts) {
-  exports.JSXIdentifier = function (node) {
+export default function (opts) {
+  var visitor = {};
+
+  visitor.JSXIdentifier = function (node) {
     if (node.name === "this" && this.isReferenced()) {
       return t.thisExpression();
     } else if (esutils.keyword.isIdentifierNameES6(node.name)) {
@@ -20,22 +22,22 @@ export default function (exports, opts) {
     }
   };
 
-  exports.JSXNamespacedName = function () {
+  visitor.JSXNamespacedName = function () {
     throw this.errorWithNode(messages.get("JSXNamespacedTags"));
   };
 
-  exports.JSXMemberExpression = {
+  visitor.JSXMemberExpression = {
     exit(node) {
       node.computed = t.isLiteral(node.property);
       node.type = "MemberExpression";
     }
   };
 
-  exports.JSXExpressionContainer = function (node) {
+  visitor.JSXExpressionContainer = function (node) {
     return node.expression;
   };
 
-  exports.JSXAttribute = {
+  visitor.JSXAttribute = {
     enter(node) {
       var value = node.value;
       if (t.isLiteral(value) && isString(value.value)) {
@@ -49,7 +51,7 @@ export default function (exports, opts) {
     }
   };
 
-  exports.JSXOpeningElement = {
+  visitor.JSXOpeningElement = {
     exit(node, parent, scope, file) {
       parent.children = react.buildChildren(parent);
 
@@ -139,7 +141,7 @@ export default function (exports, opts) {
     return attribs;
   };
 
-  exports.JSXElement = {
+  visitor.JSXElement = {
     exit(node) {
       var callExpr = node.openingElement;
 
@@ -153,54 +155,5 @@ export default function (exports, opts) {
     }
   };
 
-  // display names
-
-  var addDisplayName = function (id, call) {
-    var props = call.arguments[0].properties;
-    var safe = true;
-
-    for (var i = 0; i < props.length; i++) {
-      var prop = props[i];
-      var key = t.toComputedKey(prop);
-      if (t.isLiteral(key, { value: "displayName" })) {
-        safe = false;
-        break;
-      }
-    }
-
-    if (safe) {
-      props.unshift(t.property("init", t.identifier("displayName"), t.literal(id)));
-    }
-  };
-
-  exports.ExportDefaultDeclaration = function (node, parent, scope, file) {
-    if (react.isCreateClass(node.declaration)) {
-      addDisplayName(file.opts.basename, node.declaration);
-    }
-  };
-
-  exports.AssignmentExpression =
-  exports.Property =
-  exports.VariableDeclarator = function (node) {
-    var left, right;
-
-    if (t.isAssignmentExpression(node)) {
-      left = node.left;
-      right = node.right;
-    } else if (t.isProperty(node)) {
-      left = node.key;
-      right = node.value;
-    } else if (t.isVariableDeclarator(node)) {
-      left = node.id;
-      right = node.init;
-    }
-
-    if (t.isMemberExpression(left)) {
-      left = left.property;
-    }
-
-    if (t.isIdentifier(left) && react.isCreateClass(right)) {
-      addDisplayName(left.name, right);
-    }
-  };
+  return visitor;
 }

src/babel/transformation/helpers/get-function-arity.js

@@ -3,7 +3,10 @@ import * as t from "../../types";
 export default function (node) {
   var lastNonDefault = 0;
   for (var i = 0; i < node.params.length; i++) {
-    if (!t.isAssignmentPattern(node.params[i])) lastNonDefault = i + 1;
+    var param = node.params[i];
+    if (!t.isAssignmentPattern(param) && !t.isRestElement(param)) {
+      lastNonDefault = i + 1;
+    }
   }
   return lastNonDefault;
 }

src/babel/transformation/helpers/name-method.js

@@ -20,11 +20,8 @@ var visitor = {
     visitIdentifier(this, node, scope, state);
   },
 
-  AssignmentExpression(node, parent, scope, state) {
-    var ids = this.getBindingIdentifiers();
-    for (var name in ids) {
-      visitIdentifier(this, ids[name], scope, state);
-    }
+  BindingIdentifier(node, parent, scope, state) {
+    visitIdentifier(this, node, scope, state);
   }
 };
 
@@ -71,10 +68,10 @@ var visit = function (node, name, scope) {
   // check to see if we have a local binding of the id we're setting inside of
   // the function, this is important as there are caveats associated
 
-  var bindingInfo = scope.getOwnBindingInfo(name);
+  var binding = scope.getOwnBinding(name);
 
-  if (bindingInfo) {
-    if (bindingInfo.kind === "param") {
+  if (binding) {
+    if (binding.kind === "param") {
       // safari will blow up in strict mode with code like:
       //
       //   var t = function t(t) {};
@@ -114,8 +111,7 @@ export function property(node, file, scope) {
   var key = t.toComputedKey(node, node.key);
   if (!t.isLiteral(key)) return; // we can't set a function id with this
 
-  var name = t.toIdentifier(key.value);
-  if (name === "eval" || name === "arguments") name = "_" + name;
+  var name = t.toBindingIdentifierName(key.value);
   var id = t.identifier(name);
 
   var method = node.value;
@@ -136,8 +132,8 @@ export function bare(node, parent, scope) {
     id = parent.id;
 
     if (t.isIdentifier(id)) {
-      var bindingInfo = scope.parent.getBinding(id.name);
-      if (bindingInfo && bindingInfo.constant && scope.getBinding(id.name) === bindingInfo) {
+      var binding = scope.parent.getBinding(id.name);
+      if (binding && binding.constant && scope.getBinding(id.name) === binding) {
         // always going to reference this method
         node.id = id;
         return;
@@ -156,7 +152,7 @@ export function bare(node, parent, scope) {
     return;
   }
 
-  name = t.toIdentifier(name);
+  name = t.toBindingIdentifierName(name);
   id = t.identifier(name);
 
   var state = visit(node, name, scope);

src/babel/transformation/helpers/react.js

@@ -1,24 +1,5 @@
 import * as t from "../../types";
 
-var isCreateClassCallExpression = t.buildMatchMemberExpression("React.createClass");
-
-export function isCreateClass(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;
-}
-
 export var isReactComponent = t.buildMatchMemberExpression("React.Component");
 
 export function isCompatTag(tagName) {

src/babel/transformation/helpers/remap-async-to-generator.js

@@ -25,11 +25,13 @@ var referenceVisitor = {
   }
 };
 
-export default function (node, callId, scope) {
+export default function (path, callId) {
+  var node = path.node;
+
   node.async = false;
   node.generator = true;
 
-  scope.traverse(node, awaitVisitor, state);
+  path.traverse(awaitVisitor, state);
 
   var call = t.callExpression(callId, [node]);
 
@@ -44,11 +46,11 @@ export default function (node, callId, scope) {
     return declar;
   } else {
     if (id) {
-      var state = { id: id };
-      scope.traverse(node, referenceVisitor, state);
+      var state = { id };
+      path.traverse(referenceVisitor, state);
 
       if (state.ref) {
-        scope.parent.push({ id: state.ref });
+        path.scope.parent.push({ id: state.ref });
         return t.assignmentExpression("=", state.ref, call);
       }
     }

src/babel/transformation/helpers/replace-supers.js

@@ -169,7 +169,13 @@ export default class ReplaceSupers {
 
       if (methodName.name === "constructor") {
         // constructor() { super(); }
-        return t.memberExpression(superRef, t.identifier("call"));
+        if (parent.arguments.length === 2 && t.isSpreadElement(parent.arguments[1]) && t.isIdentifier(parent.arguments[1].argument, { name: "arguments" })) {
+          // special case single arguments spread
+          parent.arguments[1] = parent.arguments[1].argument;
+          return t.memberExpression(superRef, t.identifier("apply"));
+        } else {
+          return t.memberExpression(superRef, t.identifier("call"));
+        }
       } else {
         id = superRef;
 

src/babel/transformation/index.js

@@ -1,4 +1,4 @@
-import Pipeline from "./transformer-pipeline";
+import Pipeline from "./pipeline";
 
 var pipeline = new Pipeline;
 
@@ -8,8 +8,11 @@ import transformers from "./transformers";
 
 for (var key in transformers) {
   var transformer = transformers[key];
-  var metadata = transformer.metadata = transformer.metadata || {};
-  metadata.group = metadata.group || "builtin-basic";
+
+  if (typeof transformer === "object") {
+    var metadata = transformer.metadata = transformer.metadata || {};
+    metadata.group = metadata.group || "builtin-basic";
+  }
 }
 
 pipeline.addTransformers(transformers);

src/babel/transformation/modules/_default.js

@@ -1,108 +1,154 @@
 import * as messages from "../../messages";
+import Remaps from "./lib/remaps";
 import extend from "lodash/object/extend";
 import object from "../../helpers/object";
 import * as util from  "../../util";
 import * as t from "../../types";
 
-var remapVisitor = {
-  enter(node) {
-    if (node._skipModulesRemap) {
-      return this.skip();
-    }
-  },
-
-  ReferencedIdentifier(node, parent, scope, formatter) {
-    var remap = formatter.internalRemap[node.name];
-
-    if (remap && node !== remap) {
-      if (!scope.hasBinding(node.name) || scope.bindingIdentifierEquals(node.name, formatter.localImports[node.name])) {
-        if (this.key === "callee" && this.parentPath.isCallExpression()) {
-          return t.sequenceExpression([t.literal(0), remap]);
-        } else {
-          return remap;
-        }
-      }
-    }
-  },
-
-  AssignmentExpression: {
-    exit(node, parent, scope, formatter) {
-      if (!node._ignoreModulesRemap) {
-        var exported = formatter.getExport(node.left, scope);
-        if (exported) {
-          return formatter.remapExportAssignment(node, exported);
-        }
-      }
-    }
-  },
-
-  UpdateExpression(node, parent, scope, formatter) {
-    var exported = formatter.getExport(node.argument, scope);
-    if (!exported) return;
-
-    this.skip();
-
-    // expand to long file assignment expression
-    var assign = t.assignmentExpression(node.operator[0] + "=", node.argument, t.literal(1));
-
-    // remap this assignment expression
-    var remapped = formatter.remapExportAssignment(assign, exported);
-
-    // we don't need to change the result
-    if (t.isExpressionStatement(parent) || node.prefix) {
-      return remapped;
-    }
-
-    var nodes = [];
-    nodes.push(remapped);
-
-    var operator;
-    if (node.operator === "--") {
-      operator = "+";
-    } else { // "++"
-      operator = "-";
-    }
-    nodes.push(t.binaryExpression(operator, node.argument, t.literal(1)));
-
-    return t.sequenceExpression(nodes);
-  }
-};
-
 var metadataVisitor = {
-  ModuleDeclaration(node, parent, scope, formatter) {
-    if (node.source) {
-      node.source.value = formatter.file.resolveModuleSource(node.source.value);
+  ModuleDeclaration: {
+    enter(node, parent, scope, formatter) {
+      if (node.source) {
+        node.source.value = formatter.file.resolveModuleSource(node.source.value);
+        formatter.addScope(this);
+      }
     }
   },
 
-  ImportDeclaration(node, parent, scope, formatter) {
-    formatter.hasLocalImports = true;
-    extend(formatter.localImports, this.getBindingIdentifiers());
+  ImportDeclaration: {
+    exit(node, parent, scope, formatter) {
+      formatter.hasLocalImports = true;
+
+      var specifiers = [];
+      var imported = [];
+      formatter.metadata.imports.push({
+        source: node.source.value,
+        imported,
+        specifiers
+      });
+
+      for (var specifier of (this.get("specifiers"): Array)) {
+        var ids = specifier.getBindingIdentifiers();
+        extend(formatter.localImports, ids);
+
+        var local = specifier.node.local.name;
+
+        if (specifier.isImportDefaultSpecifier()) {
+          imported.push("default");
+          specifiers.push({
+            kind: "named",
+            imported: "default",
+            local
+          });
+        }
+
+        if (specifier.isImportSpecifier()) {
+          var importedName = specifier.node.imported.name;
+          imported.push(importedName);
+          specifiers.push({
+            kind: "named",
+            imported: importedName,
+            local
+          });
+        }
+
+        if (specifier.isImportNamespaceSpecifier()) {
+          imported.push("*");
+          specifiers.push({
+            kind: "namespace",
+            local
+          });
+        }
+      }
+    }
   },
 
   ExportDeclaration(node, parent, scope, formatter) {
     formatter.hasLocalExports = true;
 
+    var source = node.source ? node.source.value : null;
+    var exports = formatter.metadata.exports;
+
+    // export function foo() {}
+    // export var foo = "bar";
     var declar = this.get("declaration");
     if (declar.isStatement()) {
       var bindings = declar.getBindingIdentifiers();
+
       for (var name in bindings) {
         var binding = bindings[name];
         formatter._addExport(name, binding);
+
+        exports.exported.push(name);
+        exports.specifiers.push({
+          kind: "local",
+          local: name,
+          exported: this.isExportDefaultDeclaration() ? "default" : name
+        });
       }
     }
 
     if (this.isExportNamedDeclaration() && node.specifiers) {
-      for (var i = 0; i < node.specifiers.length; i++) {
-        var specifier = node.specifiers[i];
+      for (var specifier of (node.specifiers: Array)) {
+        var exported = specifier.exported.name;
+        exports.exported.push(exported);
+
+        // export foo from "bar";
+        if (t.isExportDefaultSpecifier(specifier)) {
+          exports.specifiers.push({
+            kind: "external",
+            local: exported,
+            exported,
+            source
+          });
+        }
+
+        // export * as foo from "bar";
+        if (t.isExportNamespaceSpecifier(specifier)) {
+          exports.specifiers.push({
+            kind: "external-namespace",
+            exported,
+            source
+          });
+        }
+
         var local = specifier.local;
         if (!local) continue;
 
         formatter._addExport(local.name, specifier.exported);
+
+        // export { foo } from "bar";
+        // export { foo as bar } from "bar";
+        if (source) {
+          exports.specifiers.push({
+            kind: "external",
+            local: local.name,
+            exported,
+            source
+          });
+        }
+
+        // export { foo };
+        // export { foo as bar };
+        if (!source) {
+          exports.specifiers.push({
+            kind: "local",
+            local: local.name,
+            exported
+          });
+        }
       }
     }
 
-    if (!t.isExportDefaultDeclaration(node)) {
+    // export * from "bar";
+    if (this.isExportAllDeclaration()) {
+      exports.specifiers.push({
+        kind: "external-all",
+        source
+      });
+    }
+
+    if (!t.isExportDefaultDeclaration(node) && !declar.isTypeAlias()) {
       var onlyDefault = node.specifiers && node.specifiers.length === 1 && t.isSpecifierDefault(node.specifiers[0]);
       if (!onlyDefault) {
         formatter.hasNonDefaultExports = true;
@@ -110,18 +156,27 @@ var metadataVisitor = {
     }
   },
 
-  Scope() {
-    this.skip();
+  Scope(node, parent, scope, formatter) {
+    if (!formatter.isLoose()) {
+      this.skip();
+    }
   }
 };
 
 export default class DefaultFormatter {
   constructor(file) {
-    this.internalRemap = object();
-    this.defaultIds    = object();
-    this.scope         = file.scope;
-    this.file          = file;
-    this.ids           = object();
+    // object containg all module sources with the scope that they're contained in
+    this.sourceScopes = object();
+
+    // ids for use in module ids
+    this.defaultIds = object();
+    this.ids        = object();
+
+    // contains reference aliases for live bindings
+    this.remaps = new Remaps(file, this);
+
+    this.scope = file.scope;
+    this.file  = file;
 
     this.hasNonDefaultExports = false;
 
@@ -131,9 +186,22 @@ export default class DefaultFormatter {
     this.localExports = object();
     this.localImports = object();
 
+    this.metadata = file.metadata.modules;
     this.getMetadata();
   }
 
+  addScope(path) {
+    var source = path.node.source && path.node.source.value;
+    if (!source) return;
+
+    var existingScope = this.sourceScopes[source];
+    if (existingScope && existingScope !== path.scope) {
+      throw path.errorWithNode(messages.get("modulesDuplicateDeclarations"));
+    }
+
+    this.sourceScopes[source] = path.scope;
+  }
+
   isModuleType(node, type) {
     var modules = this.file.dynamicImportTypes[type];
     return modules && modules.indexOf(node) >= 0;
@@ -155,12 +223,14 @@ export default class DefaultFormatter {
         break;
       }
     }
-    if (has) this.file.path.traverse(metadataVisitor, this);
+    if (has || this.isLoose()) {
+      this.file.path.traverse(metadataVisitor, this);
+    }
   }
 
   remapAssignments() {
     if (this.hasLocalExports || this.hasLocalImports) {
-      this.file.path.traverse(remapVisitor, this);
+      this.remaps.run();
     }
   }
 

src/babel/transformation/modules/amd.js

@@ -72,7 +72,7 @@ export default class AMDFormatter extends DefaultFormatter {
     this.getExternalReference(node);
   }
 
-  importSpecifier(specifier, node, nodes) {
+  importSpecifier(specifier, node, nodes, scope) {
     var key = node.source.value;
     var ref = this.getExternalReference(node);
 
@@ -90,7 +90,7 @@ export default class AMDFormatter extends DefaultFormatter {
       // import * as bar from "foo";
     } else if (!includes(this.file.dynamicImported, node) && t.isSpecifierDefault(specifier) && !this.noInteropRequireImport) {
       // import foo from "foo";
-      var uid = this.scope.generateUidIdentifier(specifier.local.name);
+      var uid = scope.generateUidIdentifier(specifier.local.name);
       nodes.push(t.variableDeclaration("var", [
         t.variableDeclarator(uid, t.callExpression(this.file.addHelper("interop-require-default"), [ref]))
       ]));
@@ -102,7 +102,7 @@ export default class AMDFormatter extends DefaultFormatter {
       ref = t.memberExpression(ref, imported);
     }
 
-    this.internalRemap[specifier.local.name] = ref;
+    this.remaps.add(scope, specifier.local.name, ref);
   }
 
   exportSpecifier(specifier, node, nodes) {

src/babel/transformation/modules/common.js

@@ -37,7 +37,7 @@ export default class CommonJSFormatter extends DefaultFormatter {
     }
   }
 
-  importSpecifier(specifier, node, nodes) {
+  importSpecifier(specifier, node, nodes, scope) {
     var variableName = specifier.local;
 
     var ref = this.getExternalReference(node, nodes);
@@ -47,9 +47,9 @@ export default class CommonJSFormatter extends DefaultFormatter {
       if (this.isModuleType(node, "absolute")) {
         // absolute module reference
       } else if (this.isModuleType(node, "absoluteDefault")) {
-        this.internalRemap[variableName.name] = ref;
+        this.remaps.add(scope, variableName.name, ref);
       } else if (this.noInteropRequireImport) {
-        this.internalRemap[variableName.name] = t.memberExpression(ref, t.identifier("default"));
+        this.remaps.add(scope, variableName.name, t.memberExpression(ref, t.identifier("default")));
       } else {
         var uid = this.scope.generateUidIdentifierBasedOnNode(node, "import");
 
@@ -57,7 +57,7 @@ export default class CommonJSFormatter extends DefaultFormatter {
           t.variableDeclarator(uid, t.callExpression(this.file.addHelper("interop-require-default"), [ref]))
         ]));
 
-        this.internalRemap[variableName.name] = t.memberExpression(uid, t.identifier("default"));
+        this.remaps.add(scope, variableName.name, t.memberExpression(uid, t.identifier("default")));
       }
     } else {
       if (t.isImportNamespaceSpecifier(specifier)) {
@@ -71,7 +71,7 @@ export default class CommonJSFormatter extends DefaultFormatter {
         ]));
       } else {
         // import { foo } from "foo";
-        this.internalRemap[variableName.name] = t.memberExpression(ref, specifier.imported);
+        this.remaps.add(scope, variableName.name, t.memberExpression(ref, specifier.imported));
       }
     }
   }

src/babel/transformation/modules/ignore.js

@@ -1,6 +1,7 @@
+import DefaultFormatter from "./_default";
 import * as t from "../../types";
 
-export default class IgnoreFormatter {
+export default class IgnoreFormatter extends DefaultFormatter {
   exportDeclaration(node, nodes) {
     var declar = t.toStatement(node.declaration, true);
     if (declar) nodes.push(t.inherits(declar, node));
@@ -10,4 +11,5 @@ export default class IgnoreFormatter {
   importDeclaration() {}
   importSpecifier() {}
   exportSpecifier() {}
+  transform() {}
 }

src/babel/transformation/modules/lib/remaps.js

@@ -0,0 +1,121 @@
+import * as t from "../../../types";
+
+var remapVisitor = {
+  enter(node) {
+    if (node._skipModulesRemap) {
+      return this.skip();
+    }
+  },
+
+  ReferencedIdentifier(node, parent, scope, remaps) {
+    var { formatter } = remaps;
+
+    var remap = remaps.get(scope, node.name);
+    if (!remap || node === remap) return;
+
+    if (!scope.hasBinding(node.name) ||
+        scope.bindingIdentifierEquals(node.name, formatter.localImports[node.name])) {
+      if (!formatter.isLoose() && this.key === "callee" && this.parentPath.isCallExpression()) {
+        return t.sequenceExpression([t.literal(0), remap]);
+      } else {
+        return remap;
+      }
+    }
+  },
+
+  AssignmentExpression: {
+    exit(node, parent, scope, { formatter }) {
+      if (!node._ignoreModulesRemap) {
+        var exported = formatter.getExport(node.left, scope);
+        if (exported) {
+          return formatter.remapExportAssignment(node, exported);
+        }
+      }
+    }
+  },
+
+  UpdateExpression(node, parent, scope, { formatter }) {
+    var exported = formatter.getExport(node.argument, scope);
+    if (!exported) return;
+
+    this.skip();
+
+    // expand to long file assignment expression
+    var assign = t.assignmentExpression(node.operator[0] + "=", node.argument, t.literal(1));
+
+    // remap this assignment expression
+    var remapped = formatter.remapExportAssignment(assign, exported);
+
+    // we don't need to change the result
+    if (t.isExpressionStatement(parent) || node.prefix) {
+      return remapped;
+    }
+
+    var nodes = [];
+    nodes.push(remapped);
+
+    var operator;
+    if (node.operator === "--") {
+      operator = "+";
+    } else { // "++"
+      operator = "-";
+    }
+    nodes.push(t.binaryExpression(operator, node.argument, t.literal(1)));
+
+    return t.sequenceExpression(nodes);
+  }
+};
+export default class Remaps {
+  constructor(file, formatter) {
+    this.formatter = formatter;
+    this.file      = file;
+  }
+
+  run() {
+    this.file.path.traverse(remapVisitor, this);
+  }
+
+  _getKey(name) {
+    return `${name}:moduleRemap`;
+  }
+
+  get(scope, name) {
+    return scope.getData(this._getKey(name));
+  }
+
+  add(scope, name, val) {
+    if (this.all) {
+      this.all.push({
+        name,
+        scope,
+        node: val
+      });
+    }
+
+    return scope.setData(this._getKey(name), val);
+  }
+
+  remove(scope, name) {
+    return scope.removeData(this._getKey(name));
+  }
+
+  /**
+   * These methods are used by the system module formatter who needs access to all the remaps
+   * so it can process them into it's specific setter method. We don't do this by default since
+   * no other module formatters need access to this.
+   */
+
+  getAll() {
+    return this.all;
+  }
+
+  clearAll() {
+    if (this.all) {
+      for (var remap of (this.all: Array)) {
+        remap.scope.removeData(this._getKey(remap.name));
+      }
+    }
+
+    this.all = [];
+  }
+}

src/babel/transformation/modules/system.js

@@ -1,6 +1,5 @@
 import DefaultFormatter from "./_default";
 import AMDFormatter from "./amd";
-import object from  "../../helpers/object";
 import * as util from  "../../util";
 import last from "lodash/array/last";
 import map from "lodash/collection/map";
@@ -82,6 +81,8 @@ export default class SystemFormatter extends AMDFormatter {
     this.exportIdentifier = file.scope.generateUidIdentifier("export");
     this.noInteropRequireExport = true;
     this.noInteropRequireImport = true;
+
+    this.remaps.clearAll();
   }
 
   _addImportSource(node, exportNode) {
@@ -137,13 +138,13 @@ export default class SystemFormatter extends AMDFormatter {
   importSpecifier(specifier, node, nodes) {
     AMDFormatter.prototype.importSpecifier.apply(this, arguments);
 
-    for (var name in this.internalRemap) {
+    for (var remap of (this.remaps.getAll(): Array)) {
       nodes.push(t.variableDeclaration("var", [
-        t.variableDeclarator(t.identifier(name), this.internalRemap[name])
+        t.variableDeclarator(t.identifier(remap.name), remap.node)
       ]));
     }
 
-    this.internalRemap = object();
+    this.remaps.clearAll();
 
     this._addImportSource(last(nodes), node);
   }

src/babel/transformation/pipeline.js

@@ -1,10 +1,11 @@
-import Transformer from "./transformer";
+import PluginManager from "./file/plugin-manager";
 import normalizeAst from "../helpers/normalize-ast";
+import Plugin from "./plugin";
 import assign from "lodash/object/assign";
 import object from "../helpers/object";
 import File from "./file";
 
-export default class TransformerPipeline {
+export default class Pipeline {
   constructor() {
     this.transformers = object();
     this.namespaces   = object();
@@ -20,7 +21,7 @@ export default class TransformerPipeline {
     return this;
   }
 
-  addTransformer(key, transformer) {
+  addTransformer(key, plugin) {
     if (this.transformers[key]) throw new Error(); // todo: error
 
     var namespace = key.split(".")[0];
@@ -28,7 +29,19 @@ export default class TransformerPipeline {
     this.namespaces[namespace].push(key);
     this.namespaces[key] = namespace;
 
-    this.transformers[key] = new Transformer(key, transformer);
+    if (typeof plugin === "function") {
+      plugin = PluginManager.memoisePluginContainer(plugin);
+      plugin.key = key;
+      plugin.metadata.optional = true;
+
+      if (key === "react.displayName") {
+        plugin.metadata.optional = false;
+      }
+    } else {
+      plugin = new Plugin(key, plugin);
+    }
+
+    this.transformers[key] = plugin;
   }
 
   addAliases(names) {
@@ -46,17 +59,24 @@ export default class TransformerPipeline {
     return this;
   }
 
-  canTransform(transformer, fileOpts) {
-    if (transformer.metadata.plugin) return true;
+  canTransform(plugin, fileOpts) {
+    if (plugin.metadata.plugin) {
+      return true;
+    }
 
     for (var filter of (this.filters: Array)) {
-      var result = filter(transformer, fileOpts);
+      var result = filter(plugin, fileOpts);
       if (result != null) return result;
     }
 
     return true;
   }
 
+  analyze(code: string, opts?: Object = {}) {
+    opts.code = false;
+    return this.transform(code, opts);
+  }
+
   pretransform(code: string, opts?: Object) {
     var file = new File(opts, this);
     return file.wrap(code, function () {

src/babel/transformation/plugin-pass.js

@@ -7,14 +7,13 @@ import type File from "./file";
  * AST and running it's parent transformers handlers over it.
  */
 
-export default class TransformerPass {
-  constructor(file: File, transformer: Transformer) {
-    this.transformer = transformer;
-    this.handlers    = transformer.handlers;
-    this.file        = file;
-    this.key         = transformer.key;
+export default class PluginPass {
+  constructor(file: File, plugin: Transformer) {
+    this.plugin = plugin;
+    this.file   = file;
+    this.key    = plugin.key;
 
-    if (this.canTransform() && transformer.metadata.experimental && !file.opts.experimental) {
+    if (this.canTransform() && plugin.metadata.experimental && !file.opts.experimental) {
       file.log.warn(`THE TRANSFORMER ${this.key} HAS BEEN MARKED AS EXPERIMENTAL AND IS WIP. USE AT YOUR OWN RISK. ` +
                     "THIS WILL HIGHLY LIKELY BREAK YOUR CODE SO USE WITH **EXTREME** CAUTION. ENABLE THE " +
                     "`experimental` OPTION TO IGNORE THIS WARNING.");
@@ -23,13 +22,13 @@ export default class TransformerPass {
 
   canTransform(): boolean {
     return this.file.transformerDependencies[this.key] ||
-           this.file.pipeline.canTransform(this.transformer, this.file.opts);
+           this.file.pipeline.canTransform(this.plugin, this.file.opts);
   }
 
   transform() {
     var file = this.file;
     file.log.debug(`Start transformer ${this.key}`);
-    traverse(file.ast, this.handlers, file.scope, file);
+    traverse(file.ast, this.plugin.visitor, file.scope, file);
     file.log.debug(`Finish transformer ${this.key}`);
   }
 }

src/babel/transformation/plugin.js

@@ -0,0 +1,55 @@
+import PluginPass from "./plugin-pass";
+import * as messages from "../messages";
+import isFunction from "lodash/lang/isFunction";
+import traverse from "../traversal";
+import assign from "lodash/object/assign";
+import clone from "lodash/lang/clone";
+import File from "./file";
+
+export default class Plugin {
+  constructor(key: string, plugin: Object) {
+    plugin = assign({}, plugin);
+
+    var take = function (key) {
+      var val = plugin[key];
+      delete plugin[key];
+      return val;
+    };
+
+    this.manipulateOptions = take("manipulateOptions");
+    this.metadata          = take("metadata") || {};
+    this.dependencies      = this.metadata.dependencies || [];
+    this.post              = take("post");
+    this.pre               = take("pre");
+
+    //
+
+    if (this.metadata.stage != null) {
+      this.metadata.optional = true;
+    }
+
+    //
+
+    this.visitor = this.normalize(clone(take("visitor")) || {});
+    this.key     = key;
+  }
+
+  normalize(visitor: Object): Object {
+    if (isFunction(visitor)) {
+      visitor = { ast: visitor };
+    }
+
+    traverse.explode(visitor);
+
+    return visitor;
+  }
+
+  buildPass(file: File): PluginPass {
+    // validate Transformer instance
+    if (!(file instanceof File)) {
+      throw new TypeError(messages.get("pluginNotFile", this.key));
+    }
+
+    return new PluginPass(file, this);
+  }
+}

src/babel/transformation/templates/class-derived-default-constructor.js

@@ -0,0 +1,3 @@
+(function () {
+  super(...arguments);
+})

src/babel/transformation/templates/class-super-constructor-call-loose.js

@@ -1,3 +0,0 @@
-if (SUPER_NAME != null) {
-  SUPER_NAME.apply(this, arguments);
-}

src/babel/transformation/templates/class-super-constructor-call.js

@@ -1,3 +0,0 @@
-if (SUPER_NAME != null) {
-  SUPER_NAME.apply(this, arguments);
-}

src/babel/transformation/templates/class-super-native-constructor-call.js

@@ -1,5 +0,0 @@
-if (SUPER_NAME != null) {
-  var NATIVE_REF = new SUPER_NAME(...arguments);
-  NATIVE_REF.__proto__ = CLASS_NAME.prototype;
-  return NATIVE_REF;
-}

src/babel/transformation/templates/default-parameter-assign.js

@@ -0,0 +1 @@
+if (VARIABLE_NAME === undefined) VARIABLE_NAME = DEFAULT_VALUE;

src/babel/transformation/templates/helper-get.js

@@ -1,4 +1,6 @@
 (function get(object, property, receiver) {
+  if (object === null) object = Function.prototype;
+
   var desc = Object.getOwnPropertyDescriptor(object, property);
 
   if (desc === undefined) {

src/babel/transformation/transformer.js

@@ -1,82 +1,14 @@
-import TransformerPass from "./transformer-pass";
-import * as messages from "../messages";
-import isFunction from "lodash/lang/isFunction";
-import traverse from "../traversal";
-import isObject from "lodash/lang/isObject";
-import assign from "lodash/object/assign";
-import File from "./file";
-import each from "lodash/collection/each";
-
-/**
- * This is the class responsible for normalising a transformers handlers
- * as well as constructing a `TransformerPass` that is responsible for
- * actually running the transformer over the provided `File`.
- */
+import Plugin from "./plugin";
 
 export default class Transformer {
-  constructor(transformerKey: string, transformer: Object) {
-    transformer = assign({}, transformer);
+  constructor(key, obj) {
+    var plugin = {};
 
-    var take = function (key) {
-      var val = transformer[key];
-      delete transformer[key];
-      return val;
-    };
+    plugin.metadata = obj.metadata;
+    delete obj.metadata;
 
-    this.manipulateOptions = take("manipulateOptions");
-    this.metadata          = take("metadata") || {};
-    this.dependencies      = this.metadata.dependencies || [];
-    this.parser            = take("parser");
-    this.post              = take("post");
-    this.pre               = take("pre");
+    plugin.visitor = obj;
 
-    //
-
-    if (this.metadata.stage != null) {
-      this.metadata.optional = true;
-    }
-
-    //
-
-    this.handlers = this.normalize(transformer);
-    this.key      = transformerKey;
-  }
-
-  normalize(transformer: Object): Object {
-    if (isFunction(transformer)) {
-      transformer = { ast: transformer };
-    }
-
-    traverse.explode(transformer);
-
-    each(transformer, (fns, type) => {
-      // hidden property
-      if (type[0] === "_") {
-        this[type] = fns;
-        return;
-      }
-
-      if (type === "enter" || type === "exit") return;
-
-      if (isFunction(fns)) fns = { enter: fns };
-
-      if (!isObject(fns)) return;
-
-      if (!fns.enter) fns.enter = function () { };
-      if (!fns.exit) fns.exit = function () { };
-
-      transformer[type] = fns;
-    });
-
-    return transformer;
-  }
-
-  buildPass(file: File): TransformerPass {
-    // validate Transformer instance
-    if (!(file instanceof File)) {
-      throw new TypeError(messages.get("transformerNotFile", this.key));
-    }
-
-    return new TransformerPass(file, this);
+    return new Plugin(key, plugin);
   }
 }

src/babel/transformation/transformers/es3/member-expression-literals.js

@@ -4,13 +4,15 @@ export var metadata = {
   group: "builtin-trailing"
 };
 
-export var MemberExpression = {
-  exit(node) {
-    var prop = node.property;
-    if (!node.computed && t.isIdentifier(prop) && !t.isValidIdentifier(prop.name)) {
-      // foo.default -> foo["default"]
-      node.property = t.literal(prop.name);
-      node.computed = true;
+export var visitor = {
+  MemberExpression: {
+    exit(node) {
+      var prop = node.property;
+      if (!node.computed && t.isIdentifier(prop) && !t.isValidIdentifier(prop.name)) {
+        // foo.default -> foo["default"]
+        node.property = t.literal(prop.name);
+        node.computed = true;
+      }
     }
   }
 };

src/babel/transformation/transformers/es3/property-literals.js

@@ -4,12 +4,14 @@ export var metadata = {
   group: "builtin-trailing"
 };
 
-export var Property = {
-  exit(node) {
-    var key = node.key;
-    if (!node.computed && t.isIdentifier(key) && !t.isValidIdentifier(key.name)) {
-      // default: "bar" -> "default": "bar"
-      node.key = t.literal(key.name);
+export var visitor = {
+  Property: {
+    exit(node) {
+      var key = node.key;
+      if (!node.computed && t.isIdentifier(key) && !t.isValidIdentifier(key.name)) {
+        // default: "bar" -> "default": "bar"
+        node.key = t.literal(key.name);
+      }
     }
   }
 };

src/babel/transformation/transformers/es5/properties.mutators.js

@@ -1,29 +1,31 @@
 import * as defineMap from "../../helpers/define-map";
 import * as t from "../../../types";
 
-export function ObjectExpression(node, parent, scope, file) {
-  var hasAny = false;
-  for (var prop of (node.properties: Array)) {
-    if (prop.kind === "get" || prop.kind === "set") {
-      hasAny = true;
-      break;
+export var visitor = {
+  ObjectExpression(node, parent, scope, file) {
+    var hasAny = false;
+    for (var prop of (node.properties: Array)) {
+      if (prop.kind === "get" || prop.kind === "set") {
+        hasAny = true;
+        break;
+      }
     }
+    if (!hasAny) return;
+
+    var mutatorMap = {};
+
+    node.properties = node.properties.filter(function (prop) {
+      if (prop.kind === "get" || prop.kind === "set") {
+        defineMap.push(mutatorMap, prop, prop.kind, file);
+        return false;
+      } else {
+        return true;
+      }
+    });
+
+    return t.callExpression(
+      t.memberExpression(t.identifier("Object"), t.identifier("defineProperties")),
+      [node, defineMap.toDefineObject(mutatorMap)]
+    );
   }
-  if (!hasAny) return;
-
-  var mutatorMap = {};
-
-  node.properties = node.properties.filter(function (prop) {
-    if (prop.kind === "get" || prop.kind === "set") {
-      defineMap.push(mutatorMap, prop, prop.kind, file);
-      return false;
-    } else {
-      return true;
-    }
-  });
-
-  return t.callExpression(
-    t.memberExpression(t.identifier("Object"), t.identifier("defineProperties")),
-    [node, defineMap.toDefineObject(mutatorMap)]
-  );
-}
+};

src/babel/transformation/transformers/es6/arrow-functions.js

@@ -1,9 +1,8 @@
-import * as t from "../../../types";
-
-export function ArrowFunctionExpression(node) {
-  t.ensureBlock(node);
-
-  node.expression = false;
-  node.type = "FunctionExpression";
-  node.shadow = true;
-}
+export var visitor = {
+  ArrowFunctionExpression(node) {
+    this.ensureBlock();
+    node.expression = false;
+    node.type = "FunctionExpression";
+    node.shadow = true;
+  }
+};

src/babel/transformation/transformers/es6/block-scoping.js

@@ -44,47 +44,47 @@ export var metadata = {
   group: "builtin-advanced"
 };
 
-export function VariableDeclaration(node, parent, scope, file) {
-  if (!isLet(node, parent)) return;
+export var visitor = {
+  VariableDeclaration(node, parent, scope, file) {
+    if (!isLet(node, parent)) return;
 
-  if (isLetInitable(node) && file.transformers["es6.spec.blockScoping"].canTransform()) {
-    var nodes = [node];
+    if (isLetInitable(node) && file.transformers["es6.spec.blockScoping"].canTransform()) {
+      var nodes = [node];
 
-    for (var i = 0; i < node.declarations.length; i++) {
-      var decl = node.declarations[i];
-      if (decl.init) {
-        var assign = t.assignmentExpression("=", decl.id, decl.init);
-        assign._ignoreBlockScopingTDZ = true;
-        nodes.push(t.expressionStatement(assign));
+      for (var i = 0; i < node.declarations.length; i++) {
+        var decl = node.declarations[i];
+        if (decl.init) {
+          var assign = t.assignmentExpression("=", decl.id, decl.init);
+          assign._ignoreBlockScopingTDZ = true;
+          nodes.push(t.expressionStatement(assign));
+        }
+        decl.init = file.addHelper("temporal-undefined");
       }
-      decl.init = file.addHelper("temporal-undefined");
+
+      node._blockHoist = 2;
+
+      return nodes;
+    }
+  },
+
+  Loop(node, parent, scope, file) {
+    var init = node.left || node.init;
+    if (isLet(init, node)) {
+      t.ensureBlock(node);
+      node.body._letDeclarators = [init];
     }
 
-    node._blockHoist = 2;
+    var blockScoping = new BlockScoping(this, this.get("body"), parent, scope, file);
+    return blockScoping.run();
+  },
 
-    return nodes;
+  "BlockStatement|Program"(block, parent, scope, file) {
+    if (!t.isLoop(parent)) {
+      var blockScoping = new BlockScoping(null, this, parent, scope, file);
+      blockScoping.run();
+    }
   }
-}
-
-export function Loop(node, parent, scope, file) {
-  var init = node.left || node.init;
-  if (isLet(init, node)) {
-    t.ensureBlock(node);
-    node.body._letDeclarators = [init];
-  }
-
-  var blockScoping = new BlockScoping(this, this.get("body"), parent, scope, file);
-  return blockScoping.run();
-}
-
-export function BlockStatement(block, parent, scope, file) {
-  if (!t.isLoop(parent)) {
-    var blockScoping = new BlockScoping(null, this, parent, scope, file);
-    blockScoping.run();
-  }
-}
-
-export { BlockStatement as Program };
+};
 
 function replace(node, parent, scope, remaps) {
   var remap = remaps[node.name];
@@ -116,6 +116,13 @@ function traverseReplace(node, parent, scope, remaps) {
     replace(node, parent, scope, remaps);
   }
 
+  if (t.isAssignmentExpression(node)) {
+    var ids = t.getBindingIdentifiers(node);
+    for (var name in ids) {
+      replace(ids[name], parent, scope, remaps);
+    }
+  }
+
   scope.traverse(node, replaceVisitor, remaps);
 }
 
@@ -330,6 +337,7 @@ class BlockScoping {
       // this is the defining identifier of a declaration
       var ref = letRefs[key];
 
+      // todo: could skip this if the colliding binding is in another function
       if (scope.parentHasBinding(key) || scope.hasGlobal(key)) {
         var uid = scope.generateUidIdentifier(ref.name).name;
         ref.name = uid;

src/babel/transformation/transformers/es6/classes.js

@@ -10,15 +10,17 @@ import * as t from "../../../types";
 
 const PROPERTY_COLLISION_METHOD_NAME = "__initializeProperties";
 
-export function ClassDeclaration(node, parent, scope, file) {
-  return t.variableDeclaration("let", [
-    t.variableDeclarator(node.id, t.toExpression(node))
-  ]);
-}
+export var visitor = {
+  ClassDeclaration(node) {
+    return t.variableDeclaration("let", [
+      t.variableDeclarator(node.id, t.toExpression(node))
+    ]);
+  },
 
-export function ClassExpression(node, parent, scope, file) {
-  return new ClassTransformer(this, file).run();
-}
+  ClassExpression(node, parent, scope, file) {
+    return new ClassTransformer(this, file).run();
+  }
+};
 
 var collectPropertyReferencesVisitor = {
   Identifier: {
@@ -200,6 +202,8 @@ class ClassTransformer {
       }
     }
 
+    body = body.concat(this.staticPropBody);
+
     if (this.className) {
       // named class with only a constructor
       if (body.length === 1) return t.toExpression(body[0]);
@@ -214,8 +218,6 @@ class ClassTransformer {
       t.inheritsComments(body[0], this.node);
     }
 
-    body = body.concat(this.staticPropBody);
-
     //
 
     body.push(t.returnStatement(classRef));
@@ -251,20 +253,43 @@ class ClassTransformer {
     }
   }
 
+  /**
+   * https://www.youtube.com/watch?v=fWNaR-rxAic
+   */
+
+  constructorMeMaybe() {
+    if (!this.hasSuper) return;
+
+    var hasConstructor = false;
+    var paths = this.path.get("body.body");
+
+    for (var path of (paths: Array)) {
+      hasConstructor = path.equals("kind", "constructor");
+      if (hasConstructor) break;
+    }
+
+    if (!hasConstructor) {
+      this.path.get("body").unshiftContainer("body", t.methodDefinition(
+        t.identifier("constructor"),
+        util.template("class-derived-default-constructor"),
+        "constructor"
+      ));
+    }
+  }
+
   /**
    * Description
    */
 
   buildBody() {
+    this.constructorMeMaybe();
+
     var constructorBody = this.constructorBody;
-    var classBody       = this.node.body.body;
+    var classBodyPaths  = this.path.get("body.body");
     var body            = this.body;
 
-    var classBodyPaths = this.path.get("body").get("body");
-
-    for (var i = 0; i < classBody.length; i++) {
-      var node = classBody[i];
-      var path = classBodyPaths[i];
+    for (var path of (classBodyPaths: Array)) {
+      var node = path.node;
 
       if (node.decorators) {
         memoiseDecorators(node.decorators, this.scope);
@@ -297,16 +322,6 @@ class ClassTransformer {
       }
     }
 
-    // we have no constructor, but we're a derived class
-    if (!this.hasConstructor && this.hasSuper) {
-      var helperName = "class-super-constructor-call";
-      if (this.isLoose) helperName += "-loose";
-      constructorBody.body.push(util.template(helperName, {
-        CLASS_NAME: this.classRef,
-        SUPER_NAME: this.superName
-      }, true));
-    }
-
     //
     this.placePropertyInitializers();
 
@@ -462,7 +477,7 @@ class ClassTransformer {
 
         var classRef = this.classRef;
         if (!node.static) classRef = t.memberExpression(classRef, t.identifier("prototype"));
-        var methodName = t.memberExpression(classRef, node.key, node.computed);
+        var methodName = t.memberExpression(classRef, node.key, node.computed || t.isLiteral(node.key));
 
         var expr = t.expressionStatement(t.assignmentExpression("=", methodName, node.value));
         t.inheritsComments(expr, node);

src/babel/transformation/transformers/es6/constants.js

@@ -1,41 +1,20 @@
 import * as messages from "../../../messages";
 
-function checkPath(path, file) {
-  var ids = path.getBindingIdentifiers();
+export var visitor = {
+  Scope(node, parent, scope) {
+    for (var name in scope.bindings) {
+      var binding = scope.bindings[name];
 
-  for (var name in ids) {
-    var id = ids[name];
+      // not a constant
+      if (binding.kind !== "const" && binding.kind !== "module") continue;
 
-    var binding = path.scope.getBinding(name);
+      for (var violation of (binding.constantViolations: Array)) {
+        throw violation.errorWithNode(messages.get("readOnly", name));
+      }
+    }
+  },
 
-    // no binding exists
-    if (!binding) continue;
-
-    // not a constant
-    if (binding.kind !== "const" && binding.kind !== "module") continue;
-
-    // check if the assignment id matches the constant declaration id
-    // if it does then it was the id used to initially declare the
-    // constant so we can just ignore it
-    if (binding.identifier === id) continue;
-
-    throw file.errorWithNode(id, messages.get("readOnly", name));
+  VariableDeclaration(node) {
+    if (node.kind === "const") node.kind = "let";
   }
-}
-
-export function AssignmentExpression(node, parent, scope, file) {
-  checkPath(this, file);
-}
-
-export { AssignmentExpression as UpdateExpression };
-
-export function VariableDeclaration(node) {
-  if (node.kind === "const") node.kind = "let";
-}
-
-export function ForXStatement(node, parent, scope, file) {
-  var left = this.get("left");
-  if (left.isIdentifier() || left.isPattern()) {
-    checkPath(left, file);
-  }
-}
+};

src/babel/transformation/transformers/es6/destructuring.js

@@ -5,141 +5,201 @@ export var metadata = {
   group: "builtin-advanced"
 };
 
-export function ForOfStatement(node, parent, scope, file) {
-  var left = node.left;
+export var visitor = {
+  ForXStatement(node, parent, scope, file) {
+    var left = node.left;
 
-  if (t.isPattern(left)) {
-    // for ({ length: k } in { abc: 3 });
+    if (t.isPattern(left)) {
+      // for ({ length: k } in { abc: 3 });
 
-    var temp = scope.generateUidIdentifier("ref");
+      var temp = scope.generateUidIdentifier("ref");
 
-    node.left = t.variableDeclaration("var", [
-      t.variableDeclarator(temp)
+      node.left = t.variableDeclaration("var", [
+        t.variableDeclarator(temp)
+      ]);
+
+      this.ensureBlock();
+
+      node.body.body.unshift(t.variableDeclaration("var", [
+        t.variableDeclarator(left, temp)
+      ]));
+
+      return;
+    }
+
+    if (!t.isVariableDeclaration(left)) return;
+
+    var pattern = left.declarations[0].id;
+    if (!t.isPattern(pattern)) return;
+
+    var key = scope.generateUidIdentifier("ref");
+    node.left = t.variableDeclaration(left.kind, [
+      t.variableDeclarator(key, null)
     ]);
 
-    t.ensureBlock(node);
-
-    node.body.body.unshift(t.variableDeclaration("var", [
-      t.variableDeclarator(left, temp)
-    ]));
-
-    return;
-  }
-
-  if (!t.isVariableDeclaration(left)) return;
-
-  var pattern = left.declarations[0].id;
-  if (!t.isPattern(pattern)) return;
-
-  var key = scope.generateUidIdentifier("ref");
-  node.left = t.variableDeclaration(left.kind, [
-    t.variableDeclarator(key, null)
-  ]);
-
-  var nodes = [];
-
-  var destructuring = new DestructuringTransformer({
-    kind: left.kind,
-    file: file,
-    scope: scope,
-    nodes: nodes
-  });
-
-  destructuring.init(pattern, key);
-
-  t.ensureBlock(node);
-
-  var block = node.body;
-  block.body = nodes.concat(block.body);
-}
-
-export { ForOfStatement as ForInStatement };
-
-export function Func/*tion*/(node, parent, scope, file) {
-  var nodes = [];
-
-  var hasDestructuring = false;
-
-  node.params = node.params.map(function (pattern, i) {
-    if (!t.isPattern(pattern)) return pattern;
-
-    hasDestructuring = true;
-    var ref = scope.generateUidIdentifier("ref");
-    t.inherits(ref, pattern);
+    var nodes = [];
 
     var destructuring = new DestructuringTransformer({
-      blockHoist: node.params.length - i,
-      nodes:      nodes,
-      scope:      scope,
-      file:       file,
-      kind:       "let"
+      kind: left.kind,
+      file: file,
+      scope: scope,
+      nodes: nodes
+    });
+
+    destructuring.init(pattern, key);
+
+    this.ensureBlock();
+
+    var block = node.body;
+    block.body = nodes.concat(block.body);
+  },
+
+  Function(node, parent, scope, file) {
+    var hasDestructuring = false;
+    for (let pattern of (node.params: Array)) {
+      if (t.isPattern(pattern)) {
+        hasDestructuring = true;
+        break;
+      }
+    }
+    if (!hasDestructuring) return;
+
+    var nodes = [];
+
+    for (var i = 0; i < node.params.length; i++) {
+      let pattern = node.params[i];
+      if (!t.isPattern(pattern)) continue;
+
+      var ref = node.params[i] = scope.generateUidIdentifier("ref");
+      t.inherits(ref, pattern);
+
+      var destructuring = new DestructuringTransformer({
+        blockHoist: node.params.length - i,
+        nodes:      nodes,
+        scope:      scope,
+        file:       file,
+        kind:       "let"
+      });
+
+      destructuring.init(pattern, ref);
+    }
+
+    this.ensureBlock();
+
+    var block = node.body;
+    block.body = nodes.concat(block.body);
+  },
+
+  CatchClause(node, parent, scope, file) {
+    var pattern = node.param;
+    if (!t.isPattern(pattern)) return;
+
+    var ref = scope.generateUidIdentifier("ref");
+    node.param = ref;
+
+    var nodes = [];
+
+    var destructuring = new DestructuringTransformer({
+      kind: "let",
+      file: file,
+      scope: scope,
+      nodes: nodes
     });
     destructuring.init(pattern, ref);
 
-    return ref;
-  });
+    node.body.body = nodes.concat(node.body.body);
+  },
 
-  if (!hasDestructuring) return;
+  AssignmentExpression(node, parent, scope, file) {
+    if (!t.isPattern(node.left)) return;
 
-  t.ensureBlock(node);
+    var nodes = [];
 
-  var block = node.body;
-  block.body = nodes.concat(block.body);
-}
+    var destructuring = new DestructuringTransformer({
+      operator: node.operator,
+      file: file,
+      scope: scope,
+      nodes: nodes
+    });
 
-export function CatchClause(node, parent, scope, file) {
-  var pattern = node.param;
-  if (!t.isPattern(pattern)) return;
+    var ref;
+    if (this.isCompletionRecord() || !this.parentPath.isExpressionStatement()) {
+      ref = scope.generateUidIdentifierBasedOnNode(node.right, "ref");
 
-  var ref = scope.generateUidIdentifier("ref");
-  node.param = ref;
+      nodes.push(t.variableDeclaration("var", [
+        t.variableDeclarator(ref, node.right)
+      ]));
 
-  var nodes = [];
-
-  var destructuring = new DestructuringTransformer({
-    kind: "let",
-    file: file,
-    scope: scope,
-    nodes: nodes
-  });
-  destructuring.init(pattern, ref);
-
-  node.body.body = nodes.concat(node.body.body);
-}
-
-export function AssignmentExpression(node, parent, scope, file) {
-  if (!t.isPattern(node.left)) return;
-
-  var nodes = [];
-
-  var destructuring = new DestructuringTransformer({
-    operator: node.operator,
-    file: file,
-    scope: scope,
-    nodes: nodes
-  });
-
-  var ref;
-  if (this.isCompletionRecord() || !this.parentPath.isExpressionStatement()) {
-    ref = scope.generateUidIdentifierBasedOnNode(node.right, "ref");
-
-    nodes.push(t.variableDeclaration("var", [
-      t.variableDeclarator(ref, node.right)
-    ]));
-
-    if (t.isArrayExpression(node.right)) {
-      destructuring.arrays[ref.name] = true;
+      if (t.isArrayExpression(node.right)) {
+        destructuring.arrays[ref.name] = true;
+      }
     }
+
+    destructuring.init(node.left, ref || node.right);
+
+    if (ref) {
+      nodes.push(t.expressionStatement(ref));
+    }
+
+    return nodes;
+  },
+
+  VariableDeclaration(node, parent, scope, file) {
+    if (t.isForXStatement(parent)) return;
+    if (!variableDeclarationHasPattern(node)) return;
+
+    var nodes = [];
+    var declar;
+
+    for (var i = 0; i < node.declarations.length; i++) {
+      declar = node.declarations[i];
+
+      var patternId = declar.init;
+      var pattern   = declar.id;
+
+      var destructuring = new DestructuringTransformer({
+        nodes: nodes,
+        scope: scope,
+        kind:  node.kind,
+        file:  file
+      });
+
+      if (t.isPattern(pattern)) {
+        destructuring.init(pattern, patternId);
+
+        if (+i !== node.declarations.length - 1) {
+          // we aren't the last declarator so let's just make the
+          // last transformed node inherit from us
+          t.inherits(nodes[nodes.length - 1], declar);
+        }
+      } else {
+        nodes.push(t.inherits(destructuring.buildVariableAssignment(declar.id, declar.init), declar));
+      }
+    }
+
+    if (!t.isProgram(parent) && !t.isBlockStatement(parent)) {
+      // https://github.com/babel/babel/issues/113
+      // for (let [x] = [0]; false;) {}
+
+      declar = null;
+
+      for (i = 0; i < nodes.length; i++) {
+        node = nodes[i];
+        declar = declar || t.variableDeclaration(node.kind, []);
+
+        if (!t.isVariableDeclaration(node) && declar.kind !== node.kind) {
+          throw file.errorWithNode(node, messages.get("invalidParentForThisNode"));
+        }
+
+        declar.declarations = declar.declarations.concat(node.declarations);
+      }
+
+      return declar;
+    }
+
+    return nodes;
   }
-
-  destructuring.init(node.left, ref || node.right);
-
-  if (ref) {
-    nodes.push(t.expressionStatement(ref));
-  }
-
-  return nodes;
-}
+};
 
 function variableDeclarationHasPattern(node) {
   for (var i = 0; i < node.declarations.length; i++) {
@@ -150,62 +210,6 @@ function variableDeclarationHasPattern(node) {
   return false;
 }
 
-export function VariableDeclaration(node, parent, scope, file) {
-  if (t.isForXStatement(parent)) return;
-  if (!variableDeclarationHasPattern(node)) return;
-
-  var nodes = [];
-  var declar;
-
-  for (var i = 0; i < node.declarations.length; i++) {
-    declar = node.declarations[i];
-
-    var patternId = declar.init;
-    var pattern   = declar.id;
-
-    var destructuring = new DestructuringTransformer({
-      nodes: nodes,
-      scope: scope,
-      kind:  node.kind,
-      file:  file
-    });
-
-    if (t.isPattern(pattern)) {
-      destructuring.init(pattern, patternId);
-
-      if (+i !== node.declarations.length - 1) {
-        // we aren't the last declarator so let's just make the
-        // last transformed node inherit from us
-        t.inherits(nodes[nodes.length - 1], declar);
-      }
-    } else {
-      nodes.push(t.inherits(destructuring.buildVariableAssignment(declar.id, declar.init), declar));
-    }
-  }
-
-  if (!t.isProgram(parent) && !t.isBlockStatement(parent)) {
-    // https://github.com/babel/babel/issues/113
-    // for (let [x] = [0]; false;) {}
-
-    declar = null;
-
-    for (i = 0; i < nodes.length; i++) {
-      node = nodes[i];
-      declar = declar || t.variableDeclaration(node.kind, []);
-
-      if (!t.isVariableDeclaration(node) && declar.kind !== node.kind) {
-        throw file.errorWithNode(node, messages.get("invalidParentForThisNode"));
-      }
-
-      declar.declarations = declar.declarations.concat(node.declarations);
-    }
-
-    return declar;
-  }
-
-  return nodes;
-}
-
 function hasRest(pattern) {
   for (var i = 0; i < pattern.elements.length; i++) {
     if (t.isRestElement(pattern.elements[i])) {
@@ -216,8 +220,8 @@ function hasRest(pattern) {
 }
 
 var arrayUnpackVisitor = {
-  enter(node, parent, scope, state) {
-    if (this.isReferencedIdentifier() && state.bindings[node.name]) {
+  ReferencedIdentifier(node, parent, scope, state) {
+    if (state.bindings[node.name]) {
       state.deopt = true;
       this.stop();
     }

src/babel/transformation/transformers/es6/for-of.js

@@ -2,40 +2,42 @@ import * as messages from "../../../messages";
 import * as util from  "../../../util";
 import * as t from "../../../types";
 
-export function ForOfStatement(node, parent, scope, file) {
-  if (this.get("right").isArrayExpression()) {
-    return _ForOfStatementArray.call(this, node, scope, file);
+export var visitor = {
+  ForOfStatement(node, parent, scope, file) {
+    if (this.get("right").isArrayExpression()) {
+      return _ForOfStatementArray.call(this, node, scope, file);
+    }
+
+    var callback = spec;
+    if (file.isLoose("es6.forOf")) callback = loose;
+
+    var build  = callback(node, parent, scope, file);
+    var declar = build.declar;
+    var loop   = build.loop;
+    var block  = loop.body;
+
+    // ensure that it's a block so we can take all its statements
+    this.ensureBlock();
+
+    // add the value declaration to the new loop body
+    if (declar) {
+      block.body.push(declar);
+    }
+
+    // push the rest of the original loop body onto our new body
+    block.body = block.body.concat(node.body.body);
+
+    t.inherits(loop, node);
+    t.inherits(loop.body, node.body);
+
+    if (build.replaceParent) {
+      this.parentPath.replaceWithMultiple(build.node);
+      this.dangerouslyRemove();
+    } else {
+      return build.node;
+    }
   }
-
-  var callback = spec;
-  if (file.isLoose("es6.forOf")) callback = loose;
-
-  var build  = callback(node, parent, scope, file);
-  var declar = build.declar;
-  var loop   = build.loop;
-  var block  = loop.body;
-
-  // ensure that it's a block so we can take all its statements
-  t.ensureBlock(node);
-
-  // add the value declaration to the new loop body
-  if (declar) {
-    block.body.push(declar);
-  }
-
-  // push the rest of the original loop body onto our new body
-  block.body = block.body.concat(node.body.body);
-
-  t.inherits(loop, node);
-  t.inherits(loop.body, node.body);
-
-  if (build.replaceParent) {
-    this.parentPath.replaceWithMultiple(build.node);
-    this.dangerouslyRemove();
-  } else {
-    return build.node;
-  }
-}
+};
 
 export function _ForOfStatementArray(node, scope, file) {
   var nodes = [];
@@ -70,6 +72,10 @@ export function _ForOfStatementArray(node, scope, file) {
     loop.body.body.unshift(t.expressionStatement(t.assignmentExpression("=", left, iterationValue)));
   }
 
+  if (this.parentPath.isLabeledStatement()) {
+    loop = t.labeledStatement(this.parentPath.node.label, loop);
+  }
+
   nodes.push(loop);
 
   return nodes;

src/babel/transformation/transformers/es6/modules.js

@@ -12,64 +12,66 @@ export var metadata = {
   group: "builtin-modules"
 };
 
-export function ImportDeclaration(node, parent, scope, file) {
-  // flow type
-  if (node.isType) return;
+export var visitor = {
+  ImportDeclaration(node, parent, scope, file) {
+    // flow type
+    if (node.isType) return;
 
-  var nodes = [];
+    var nodes = [];
 
-  if (node.specifiers.length) {
-    for (var specifier of (node.specifiers: Array)) {
-      file.moduleFormatter.importSpecifier(specifier, node, nodes, parent);
-    }
-  } else {
-    file.moduleFormatter.importDeclaration(node, nodes, parent);
-  }
-
-  if (nodes.length === 1) {
-    // inherit `_blockHoist` - this is for `_blockHoist` in File.prototype.addImport
-    nodes[0]._blockHoist = node._blockHoist;
-  }
-
-  return nodes;
-}
-
-export function ExportAllDeclaration(node, parent, scope, file) {
-  var nodes = [];
-  file.moduleFormatter.exportAllDeclaration(node, nodes, parent);
-  keepBlockHoist(node, nodes);
-  return nodes;
-}
-
-export function ExportDefaultDeclaration(node, parent, scope, file) {
-  var nodes = [];
-  file.moduleFormatter.exportDeclaration(node, nodes, parent);
-  keepBlockHoist(node, nodes);
-  return nodes;
-}
-
-export function ExportNamedDeclaration(node, parent, scope, file) {
-  // flow type
-  if (this.get("declaration").isTypeAlias()) return;
-
-  var nodes = [];
-
-  if (node.declaration) {
-    // 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];
-      declar.init = declar.init || t.identifier("undefined");
+    if (node.specifiers.length) {
+      for (var specifier of (node.specifiers: Array)) {
+        file.moduleFormatter.importSpecifier(specifier, node, nodes, scope);
+      }
+    } else {
+      file.moduleFormatter.importDeclaration(node, nodes, scope);
     }
 
-    file.moduleFormatter.exportDeclaration(node, nodes, parent);
-  } else if (node.specifiers) {
-    for (let i = 0; i < node.specifiers.length; i++) {
-      file.moduleFormatter.exportSpecifier(node.specifiers[i], node, nodes, parent);
+    if (nodes.length === 1) {
+      // inherit `_blockHoist` - this is for `_blockHoist` in File.prototype.addImport
+      nodes[0]._blockHoist = node._blockHoist;
     }
+
+    return nodes;
+  },
+
+  ExportAllDeclaration(node, parent, scope, file) {
+    var nodes = [];
+    file.moduleFormatter.exportAllDeclaration(node, nodes, scope);
+    keepBlockHoist(node, nodes);
+    return nodes;
+  },
+
+  ExportDefaultDeclaration(node, parent, scope, file) {
+    var nodes = [];
+    file.moduleFormatter.exportDeclaration(node, nodes, scope);
+    keepBlockHoist(node, nodes);
+    return nodes;
+  },
+
+  ExportNamedDeclaration(node, parent, scope, file) {
+    // flow type
+    if (this.get("declaration").isTypeAlias()) return;
+
+    var nodes = [];
+
+    if (node.declaration) {
+      // 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];
+        declar.init = declar.init || t.identifier("undefined");
+      }
+
+      file.moduleFormatter.exportDeclaration(node, nodes, scope);
+    } else if (node.specifiers) {
+      for (let i = 0; i < node.specifiers.length; i++) {
+        file.moduleFormatter.exportSpecifier(node.specifiers[i], node, nodes, scope);
+      }
+    }
+
+    keepBlockHoist(node, nodes);
+
+    return nodes;
   }
-
-  keepBlockHoist(node, nodes);
-
-  return nodes;
-}
+};

src/babel/transformation/transformers/es6/object-super.js

@@ -17,17 +17,19 @@ function Property(path, node, scope, getObjectRef, file) {
   replaceSupers.replace();
 }
 
-export function ObjectExpression(node, parent, scope, file) {
-  var objectRef;
-  var getObjectRef = () => objectRef = objectRef || scope.generateUidIdentifier("obj");
+export var visitor = {
+  ObjectExpression(node, parent, scope, file) {
+    var objectRef;
+    var getObjectRef = () => objectRef = objectRef || scope.generateUidIdentifier("obj");
 
-  var propPaths = this.get("properties");
-  for (var i = 0; i < node.properties.length; i++) {
-    Property(propPaths[i], node.properties[i], scope, getObjectRef, file);
-  }
+    var propPaths = this.get("properties");
+    for (var i = 0; i < node.properties.length; i++) {
+      Property(propPaths[i], node.properties[i], scope, getObjectRef, file);
+    }
 
-  if (objectRef) {
-    scope.push({ id: objectRef });
-    return t.assignmentExpression("=", objectRef, node);
+    if (objectRef) {
+      scope.push({ id: objectRef });
+      return t.assignmentExpression("=", objectRef, node);
+    }
   }
-}
+};

src/babel/transformation/transformers/es6/parameters.default.js

@@ -1,4 +1,5 @@
 import callDelegate from "../../helpers/call-delegate";
+import getFunctionArity from "../../helpers/get-function-arity";
 import * as util from  "../../../util";
 import * as t from "../../../types";
 
@@ -21,76 +22,99 @@ var iifeVisitor = {
   }
 };
 
-export function Func/*tion*/(node, parent, scope, file) {
-  if (!hasDefaults(node)) return;
+export var visitor = {
+  Function(node, parent, scope, file) {
+    if (!hasDefaults(node)) return;
 
-  t.ensureBlock(node);
+    // ensure it's a block, useful for arrow functions
+    this.ensureBlock();
 
-  var body = [];
+    var state = {
+      iife: false,
+      scope: scope
+    };
 
-  var argsIdentifier = t.identifier("arguments");
-  argsIdentifier._shadowedFunctionLiteral = true;
+    var body = [];
 
-  var lastNonDefaultParam = 0;
+    //
+    var argsIdentifier = t.identifier("arguments");
+    argsIdentifier._shadowedFunctionLiteral = true;
 
-  var state = { iife: false, scope: scope };
-
-  var pushDefNode = function (left, right, i) {
-    var defNode = util.template("default-parameter", {
-      VARIABLE_NAME: left,
-      DEFAULT_VALUE: right,
-      ARGUMENT_KEY:  t.literal(i),
-      ARGUMENTS:     argsIdentifier
-    }, true);
-    defNode._blockHoist = node.params.length - i;
-    body.push(defNode);
-  };
-
-  var params = this.get("params");
-  for (var i = 0; i < params.length; i++) {
-    var param = params[i];
-
-    if (!param.isAssignmentPattern()) {
-      if (!param.isRestElement()) {
-        lastNonDefaultParam = i + 1;
-      }
-
-      if (!param.isIdentifier()) {
-        param.traverse(iifeVisitor, state);
-      }
-
-      if (file.transformers["es6.spec.blockScoping"].canTransform() && param.isIdentifier()) {
-        pushDefNode(param.node, t.identifier("undefined"), i);
-      }
-
-      continue;
-    }
-
-    var left  = param.get("left");
-    var right = param.get("right");
-
-    var placeholder = scope.generateUidIdentifier("x");
-    placeholder._isDefaultPlaceholder = true;
-    node.params[i] = placeholder;
-
-    if (!state.iife) {
-      if (right.isIdentifier() && scope.hasOwnBinding(right.node.name)) {
-        state.iife = true;
+    // push a default parameter definition
+    function pushDefNode(left, right, i) {
+      var defNode;
+      if (exceedsLastNonDefault(i) || t.isPattern(left) || file.transformers["es6.spec.blockScoping"].canTransform()) {
+        defNode = util.template("default-parameter", {
+          VARIABLE_NAME: left,
+          DEFAULT_VALUE: right,
+          ARGUMENT_KEY:  t.literal(i),
+          ARGUMENTS:     argsIdentifier
+        }, true);
       } else {
-        right.traverse(iifeVisitor, state);
+        defNode = util.template("default-parameter-assign", {
+          VARIABLE_NAME: left,
+          DEFAULT_VALUE: right
+        }, true);
       }
+      defNode._blockHoist = node.params.length - i;
+      body.push(defNode);
     }
 
-    pushDefNode(left.node, right.node, i);
-  }
+    // check if an index exceeds the functions arity
+    function exceedsLastNonDefault(i) {
+      return i + 1 > lastNonDefaultParam;
+    }
 
-  // we need to cut off all trailing default parameters
-  node.params = node.params.slice(0, lastNonDefaultParam);
+    //
+    var lastNonDefaultParam = getFunctionArity(node);
 
-  if (state.iife) {
-    body.push(callDelegate(node, scope));
-    node.body = t.blockStatement(body);
-  } else {
-    node.body.body = body.concat(node.body.body);
+    //
+    var params = this.get("params");
+    for (var i = 0; i < params.length; i++) {
+      var param = params[i];
+
+      if (!param.isAssignmentPattern()) {
+        if (!param.isIdentifier()) {
+          param.traverse(iifeVisitor, state);
+        }
+
+        if (file.transformers["es6.spec.blockScoping"].canTransform() && param.isIdentifier()) {
+          pushDefNode(param.node, t.identifier("undefined"), i);
+        }
+
+        continue;
+      }
+
+      var left  = param.get("left");
+      var right = param.get("right");
+
+      if (exceedsLastNonDefault(i) || left.isPattern()) {
+        var placeholder = scope.generateUidIdentifier("x");
+        placeholder._isDefaultPlaceholder = true;
+        node.params[i] = placeholder;
+      } else {
+        node.params[i] = left.node;
+      }
+
+      if (!state.iife) {
+        if (right.isIdentifier() && scope.hasOwnBinding(right.node.name)) {
+          state.iife = true;
+        } else {
+          right.traverse(iifeVisitor, state);
+        }
+      }
+
+      pushDefNode(left.node, right.node, i);
+    }
+
+    // we need to cut off all trailing default parameters
+    node.params = node.params.slice(0, lastNonDefaultParam);
+
+    if (state.iife) {
+      body.push(callDelegate(node, scope));
+      node.body = t.blockStatement(body);
+    } else {
+      node.body.body = body.concat(node.body.body);
+    }
   }
-}
+};

src/babel/transformation/transformers/es6/parameters.rest.js

@@ -1,48 +1,64 @@
-import isNumber from "lodash/lang/isNumber";
 import * as util from  "../../../util";
 import * as t from "../../../types";
 
 var memberExpressionOptimisationVisitor = {
-  enter(node, parent, scope, state) {
+  Scope(node, parent, scope, state) {
     // check if this scope has a local binding that will shadow the rest parameter
-    if (this.isScope() && !scope.bindingIdentifierEquals(state.name, state.outerBinding)) {
-      return this.skip();
+    if (!scope.bindingIdentifierEquals(state.name, state.outerBinding)) {
+      this.skip();
     }
+  },
 
-    var stop = () => {
-      state.canOptimise = false;
-      this.stop();
-    };
-
-    if (this.isArrowFunctionExpression()) return stop();
-
+  Function(node, parent, scope, state) {
     // skip over functions as whatever `arguments` we reference inside will refer
     // to the wrong function
-    if (this.isFunctionDeclaration() || this.isFunctionExpression()) {
-      state.noOptimise = true;
-      this.traverse(memberExpressionOptimisationVisitor, state);
-      state.noOptimise = false;
-      return this.skip();
+    state.noOptimise = true;
+    this.traverse(memberExpressionOptimisationVisitor, state);
+    state.noOptimise = false;
+    this.skip();
+  },
+
+  ReferencedIdentifier(node, parent, scope, state) {
+    // we can't guarantee the purity of arguments
+    if (node.name === "arguments") {
+      state.deopted = true;
     }
 
     // is this a referenced identifier and is it referencing the rest parameter?
-    if (!this.isReferencedIdentifier({ name: state.name })) return;
+    if (node.name !== state.name) return;
 
-    if (!state.noOptimise && t.isMemberExpression(parent) && parent.computed) {
-      // if we know that this member expression is referencing a number then we can safely
-      // optimise it
-      var prop = parent.property;
-      if (isNumber(prop.value) || t.isUnaryExpression(prop) || t.isBinaryExpression(prop)) {
-        state.candidates.push(this);
-        return;
+    if (!state.noOptimise) {
+      if (this.parentPath.isMemberExpression({ computed: true, object: node })) {
+        // if we know that this member expression is referencing a number then we can safely
+        // optimise it
+        var prop = this.parentPath.get("property");
+        if (prop.isBaseType("number")) {
+          state.candidates.push(this);
+          return;
+        }
+      }
+
+      // optimise single spread args in calls
+      if (this.parentPath.isSpreadElement() && state.offset === 0) {
+        var call = this.parentPath.parentPath;
+        if (call.isCallExpression() && call.node.arguments.length === 1) {
+          state.candidates.push(this);
+          return;
+        }
       }
     }
 
-    stop();
+    if (state.noOptimise) {
+      state.deopted = true;
+    } else {
+      state.references.push(this);
+    }
   }
 };
 
-function optimizeMemberExpression(parent, offset) {
+function optimiseMemberExpression(parent, offset) {
+  if (offset === 0) return;
+
   var newExpr;
   var prop = parent.property;
 
@@ -55,91 +71,117 @@ function optimizeMemberExpression(parent, offset) {
   }
 }
 
-var hasRest = function (node) {
+function hasRest(node) {
   return t.isRestElement(node.params[node.params.length - 1]);
-};
-
-export function Func/*tion*/(node, parent, scope, file) {
-  if (!hasRest(node)) return;
-
-  var restParam = node.params.pop();
-  var rest = restParam.argument;
-
-  var argsId = t.identifier("arguments");
-
-  // otherwise `arguments` will be remapped in arrow functions
-  argsId._shadowedFunctionLiteral = true;
-
-  // support patterns
-  if (t.isPattern(rest)) {
-    var pattern = rest;
-    rest = scope.generateUidIdentifier("ref");
-
-    var declar = t.variableDeclaration("let", pattern.elements.map(function (elem, index) {
-      var accessExpr = t.memberExpression(rest, t.literal(index), true);
-      return t.variableDeclarator(elem, accessExpr);
-    }));
-    node.body.body.unshift(declar);
-  }
-
-  // check if rest is used in member expressions and optimise for those cases
-
-  var state = {
-    outerBinding: scope.getBindingIdentifier(rest.name),
-    canOptimise:  true,
-    candidates:   [],
-    method:       node,
-    name:         rest.name
-  };
-
-  this.traverse(memberExpressionOptimisationVisitor, state);
-
-  // we only have shorthands and there's no other references
-  if (state.canOptimise && state.candidates.length) {
-    for (var candidate of (state.candidates: Array)) {
-      candidate.replaceWith(argsId);
-      optimizeMemberExpression(candidate.parent, node.params.length);
-    }
-    return;
-  }
-
-  //
-
-  var start = t.literal(node.params.length);
-  var key = scope.generateUidIdentifier("key");
-  var len = scope.generateUidIdentifier("len");
-
-  var arrKey = key;
-  var arrLen = len;
-  if (node.params.length) {
-    // this method has additional params, so we need to subtract
-    // the index of the current argument position from the
-    // position in the array that we want to populate
-    arrKey = t.binaryExpression("-", key, start);
-
-    // we need to work out the size of the array that we're
-    // going to store all the rest parameters
-    //
-    // we need to add a check to avoid constructing the array
-    // with <0 if there are less arguments than params as it'll
-    // cause an error
-    arrLen = t.conditionalExpression(
-      t.binaryExpression(">", len, start),
-      t.binaryExpression("-", len, start),
-      t.literal(0)
-    );
-  }
-
-  var loop = util.template("rest", {
-    ARRAY_TYPE: restParam.typeAnnotation,
-    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);
 }
+
+export var visitor = {
+  Function(node, parent, scope) {
+    if (!hasRest(node)) return;
+
+    var restParam = node.params.pop();
+    var rest = restParam.argument;
+
+    var argsId = t.identifier("arguments");
+
+    // otherwise `arguments` will be remapped in arrow functions
+    argsId._shadowedFunctionLiteral = true;
+
+    // support patterns
+    if (t.isPattern(rest)) {
+      var pattern = rest;
+      rest = scope.generateUidIdentifier("ref");
+
+      var declar = t.variableDeclaration("let", pattern.elements.map(function (elem, index) {
+        var accessExpr = t.memberExpression(rest, t.literal(index), true);
+        return t.variableDeclarator(elem, accessExpr);
+      }));
+      node.body.body.unshift(declar);
+    }
+
+    // check and optimise for extremely common cases
+    var state = {
+      references: [],
+      offset:     node.params.length,
+
+      argumentsNode: argsId,
+      outerBinding:  scope.getBindingIdentifier(rest.name),
+
+      // candidate member expressions we could optimise if there are no other references
+      candidates: [],
+
+      // local rest binding name
+      name: rest.name,
+
+      // whether any references to the rest parameter were made in a function
+      deopted: false
+    };
+
+    this.traverse(memberExpressionOptimisationVisitor, state);
+
+    if (!state.deopted && !state.references.length) {
+      // we only have shorthands and there are no other references
+      if (state.candidates.length) {
+        for (var candidate of (state.candidates: Array)) {
+          candidate.replaceWith(argsId);
+          if (candidate.parentPath.isMemberExpression()) {
+            optimiseMemberExpression(candidate.parent, state.offset);
+          }
+        }
+      }
+      return;
+    } else {
+      state.references = state.references.concat(state.candidates);
+    }
+
+    // deopt shadowed functions as transforms like regenerator may try touch the allocation loop
+    state.deopted = state.deopted || !!node.shadow;
+
+    //
+
+    var start = t.literal(node.params.length);
+    var key = scope.generateUidIdentifier("key");
+    var len = scope.generateUidIdentifier("len");
+
+    var arrKey = key;
+    var arrLen = len;
+    if (node.params.length) {
+      // this method has additional params, so we need to subtract
+      // the index of the current argument position from the
+      // position in the array that we want to populate
+      arrKey = t.binaryExpression("-", key, start);
+
+      // we need to work out the size of the array that we're
+      // going to store all the rest parameters
+      //
+      // we need to add a check to avoid constructing the array
+      // with <0 if there are less arguments than params as it'll
+      // cause an error
+      arrLen = t.conditionalExpression(
+        t.binaryExpression(">", len, start),
+        t.binaryExpression("-", len, start),
+        t.literal(0)
+      );
+    }
+
+    var loop = util.template("rest", {
+      ARRAY_TYPE: restParam.typeAnnotation,
+      ARGUMENTS:  argsId,
+      ARRAY_KEY:  arrKey,
+      ARRAY_LEN:  arrLen,
+      START:      start,
+      ARRAY:      rest,
+      KEY:        key,
+      LEN:        len
+    });
+
+    if (state.deopted) {
+      loop._blockHoist = node.params.length + 1;
+      node.body.body.unshift(loop);
+    } else {
+      // perform allocation at the lowest common denominator of all references
+      loop._blockHoist = 1;
+      this.getEarliestCommonAncestorFrom(state.references).getStatementParent().insertBefore(loop);
+    }
+  }
+};

src/babel/transformation/transformers/es6/properties.computed.js

@@ -63,40 +63,42 @@ function spec(node, body, objId, initProps, file) {
   }
 }
 
-export var ObjectExpression = {
-  exit(node, parent, scope, file) {
-    var hasComputed = false;
+export var visitor = {
+  ObjectExpression: {
+    exit(node, parent, scope, file) {
+      var hasComputed = false;
 
-    for (var prop of (node.properties: Array)) {
-      hasComputed = t.isProperty(prop, { computed: true, kind: "init" });
-      if (hasComputed) break;
+      for (var prop of (node.properties: Array)) {
+        hasComputed = t.isProperty(prop, { computed: true, kind: "init" });
+        if (hasComputed) break;
+      }
+
+      if (!hasComputed) return;
+
+      var initProps = [];
+      var objId = scope.generateUidIdentifierBasedOnNode(parent);
+
+      //
+
+      var body = [];
+
+      //
+
+      var callback = spec;
+      if (file.isLoose("es6.properties.computed")) callback = loose;
+
+      var result = callback(node, body, objId, initProps, file);
+      if (result) return result;
+
+      //
+
+      body.unshift(t.variableDeclaration("var", [
+        t.variableDeclarator(objId, t.objectExpression(initProps))
+      ]));
+
+      body.push(t.expressionStatement(objId));
+
+      return body;
     }
-
-    if (!hasComputed) return;
-
-    var initProps = [];
-    var objId = scope.generateUidIdentifierBasedOnNode(parent);
-
-    //
-
-    var body = [];
-
-    //
-
-    var callback = spec;
-    if (file.isLoose("es6.properties.computed")) callback = loose;
-
-    var result = callback(node, body, objId, initProps, file);
-    if (result) return result;
-
-    //
-
-    body.unshift(t.variableDeclaration("var", [
-      t.variableDeclarator(objId, t.objectExpression(initProps))
-    ]));
-
-    body.push(t.expressionStatement(objId));
-
-    return body;
   }
 };

src/babel/transformation/transformers/es6/properties.shorthand.js

@@ -1,9 +1,11 @@
-export function Property(node) {
-  if (node.method) {
-    node.method = false;
-  }
+export var visitor = {
+  Property(node) {
+    if (node.method) {
+      node.method = false;
+    }
 
-  if (node.shorthand) {
-    node.shorthand = false;
+    if (node.shorthand) {
+      node.shorthand = false;
+    }
   }
-}
+};

src/babel/transformation/transformers/es6/regex.sticky.js

@@ -1,10 +1,12 @@
 import * as regex from "../../helpers/regex";
 import * as t from "../../../types";
 
-export function Literal(node) {
-  if (!regex.is(node, "y")) return;
-  return t.newExpression(t.identifier("RegExp"), [
-    t.literal(node.regex.pattern),
-    t.literal(node.regex.flags)
-  ]);
-}
+export var visitor = {
+  Literal(node) {
+    if (!regex.is(node, "y")) return;
+    return t.newExpression(t.identifier("RegExp"), [
+      t.literal(node.regex.pattern),
+      t.literal(node.regex.flags)
+    ]);
+  }
+};

src/babel/transformation/transformers/es6/regex.unicode.js

@@ -1,8 +1,10 @@
 import rewritePattern from "regexpu/rewrite-pattern";
 import * as regex from "../../helpers/regex";
 
-export function Literal(node) {
-  if (!regex.is(node, "u")) return;
-  node.regex.pattern = rewritePattern(node.regex.pattern, node.regex.flags);
-  regex.pullFlag(node, "u");
-}
+export var visitor = {
+  Literal(node) {
+    if (!regex.is(node, "u")) return;
+    node.regex.pattern = rewritePattern(node.regex.pattern, node.regex.flags);
+    regex.pullFlag(node, "u");
+  }
+};

src/babel/transformation/transformers/es6/spec.block-scoping.js

@@ -15,7 +15,7 @@ function references(node, scope, state) {
   return scope.getBindingIdentifier(node.name) === declared;
 }
 
-var visitor = {
+var refVisitor = {
   ReferencedIdentifier(node, parent, scope, state) {
     if (t.isFor(parent) && parent.left === node) return;
 
@@ -62,16 +62,16 @@ export var metadata = {
   group: "builtin-advanced"
 };
 
-export var BlockStatement = {
-  exit(node, parent, scope, file) {
-    var letRefs = node._letReferences;
-    if (!letRefs) return;
+export var visitor = {
+  "Program|Loop|BlockStatement": {
+    exit(node, parent, scope, file) {
+      var letRefs = node._letReferences;
+      if (!letRefs) return;
 
-    this.traverse(visitor, {
-      letRefs: letRefs,
-      file:    file
-    });
+      this.traverse(refVisitor, {
+        letRefs: letRefs,
+        file:    file
+      });
+    }
   }
 };
-
-export { BlockStatement as Program, BlockStatement as Loop };

src/babel/transformation/transformers/es6/spec.symbols.js

@@ -4,34 +4,34 @@ export var metadata = {
   optional: true
 };
 
-export function UnaryExpression(node, parent, scope, file) {
-  if (node._ignoreSpecSymbols) return;
+export var visitor = {
+  UnaryExpression(node, parent, scope, file) {
+    if (node._ignoreSpecSymbols) return;
 
-  if (node.operator === "typeof") {
-    var call = t.callExpression(file.addHelper("typeof"), [node.argument]);
-    if (this.get("argument").isIdentifier()) {
-      var undefLiteral = t.literal("undefined");
-      var unary = t.unaryExpression("typeof", node.argument);
-      unary._ignoreSpecSymbols = true;
-      return t.conditionalExpression(
-        t.binaryExpression("===", unary, undefLiteral),
-        undefLiteral,
-        call
-      );
-    } else {
-      return call;
+    if (node.operator === "typeof") {
+      var call = t.callExpression(file.addHelper("typeof"), [node.argument]);
+      if (this.get("argument").isIdentifier()) {
+        var undefLiteral = t.literal("undefined");
+        var unary = t.unaryExpression("typeof", node.argument);
+        unary._ignoreSpecSymbols = true;
+        return t.conditionalExpression(
+          t.binaryExpression("===", unary, undefLiteral),
+          undefLiteral,
+          call
+        );
+      } else {
+        return call;
+      }
     }
+  },
+
+  BinaryExpression(node, parent, scope, file) {
+    if (node.operator === "instanceof") {
+      return t.callExpression(file.addHelper("instanceof"), [node.left, node.right]);
+    }
+  },
+
+  "VariableDeclaration|FunctionDeclaration"(node) {
+    if (node._generated) this.skip();
   }
-}
-
-export function BinaryExpression(node, parent, scope, file) {
-  if (node.operator === "instanceof") {
-    return t.callExpression(file.addHelper("instanceof"), [node.left, node.right]);
-  }
-}
-
-export function VariableDeclaration(node) {
-  if (node._generated) this.skip();
-}
-
-export { VariableDeclaration as FunctionDeclaration };
+};

src/babel/transformation/transformers/es6/spec.template-literals.js

@@ -5,10 +5,12 @@ export var metadata = {
   group: "builtin-pre"
 };
 
-export function TemplateLiteral(node, parent, scope, file) {
-  if (t.isTaggedTemplateExpression(parent)) return;
+export var visitor = {
+  TemplateLiteral(node, parent) {
+    if (t.isTaggedTemplateExpression(parent)) return;
 
-  for (var i = 0; i < node.expressions.length; i++) {
-    node.expressions[i] = t.callExpression(t.identifier("String"), [node.expressions[i]]);
+    for (var i = 0; i < node.expressions.length; i++) {
+      node.expressions[i] = t.callExpression(t.identifier("String"), [node.expressions[i]]);
+    }
   }
-}
+};

src/babel/transformation/transformers/es6/spread.js

@@ -1,7 +1,7 @@
 import * as t from "../../../types";
 
 function getSpreadLiteral(spread, scope) {
-  if (scope.file.isLoose("es6.spread")) {
+  if (scope.hub.file.isLoose("es6.spread") && !t.isIdentifier(spread.argument, { name: "arguments" })) {
     return spread.argument;
   } else {
     return scope.toArray(spread.argument, true);
@@ -43,76 +43,78 @@ function build(props, scope) {
   return nodes;
 }
 
-export function ArrayExpression(node, parent, scope) {
-  var elements = node.elements;
-  if (!hasSpread(elements)) return;
+export var visitor = {
+  ArrayExpression(node, parent, scope) {
+    var elements = node.elements;
+    if (!hasSpread(elements)) return;
 
-  var nodes = build(elements, scope);
-  var first = nodes.shift();
+    var nodes = build(elements, scope);
+    var first = nodes.shift();
 
-  if (!t.isArrayExpression(first)) {
-    nodes.unshift(first);
-    first = t.arrayExpression([]);
-  }
-
-  return t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes);
-}
-
-export function CallExpression(node, parent, scope) {
-  var args = node.arguments;
-  if (!hasSpread(args)) return;
-
-  var contextLiteral = t.identifier("undefined");
-
-  node.arguments = [];
-
-  var nodes;
-  if (args.length === 1 && args[0].argument.name === "arguments") {
-    nodes = [args[0].argument];
-  } else {
-    nodes = build(args, scope);
-  }
-
-  var first = nodes.shift();
-  if (nodes.length) {
-    node.arguments.push(t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes));
-  } else {
-    node.arguments.push(first);
-  }
-
-  var callee = node.callee;
-
-  if (this.get("callee").isMemberExpression()) {
-    var temp = scope.maybeGenerateMemoised(callee.object);
-    if (temp) {
-      callee.object = t.assignmentExpression("=", temp, callee.object);
-      contextLiteral = temp;
-    } else {
-      contextLiteral = callee.object;
+    if (!t.isArrayExpression(first)) {
+      nodes.unshift(first);
+      first = t.arrayExpression([]);
     }
-    t.appendToMemberExpression(callee, t.identifier("apply"));
-  } else {
-    node.callee = t.memberExpression(node.callee, t.identifier("apply"));
+
+    return t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes);
+  },
+
+  CallExpression(node, parent, scope) {
+    var args = node.arguments;
+    if (!hasSpread(args)) return;
+
+    var contextLiteral = t.identifier("undefined");
+
+    node.arguments = [];
+
+    var nodes;
+    if (args.length === 1 && args[0].argument.name === "arguments") {
+      nodes = [args[0].argument];
+    } else {
+      nodes = build(args, scope);
+    }
+
+    var first = nodes.shift();
+    if (nodes.length) {
+      node.arguments.push(t.callExpression(t.memberExpression(first, t.identifier("concat")), nodes));
+    } else {
+      node.arguments.push(first);
+    }
+
+    var callee = node.callee;
+
+    if (this.get("callee").isMemberExpression()) {
+      var temp = scope.maybeGenerateMemoised(callee.object);
+      if (temp) {
+        callee.object = t.assignmentExpression("=", temp, callee.object);
+        contextLiteral = temp;
+      } else {
+        contextLiteral = callee.object;
+      }
+      t.appendToMemberExpression(callee, t.identifier("apply"));
+    } else {
+      node.callee = t.memberExpression(node.callee, t.identifier("apply"));
+    }
+
+    node.arguments.unshift(contextLiteral);
+  },
+
+  NewExpression(node, parent, scope, file) {
+    var args = node.arguments;
+    if (!hasSpread(args)) return;
+
+    var nodes = build(args, scope);
+
+    var context = t.arrayExpression([t.literal(null)]);
+
+    args = t.callExpression(t.memberExpression(context, t.identifier("concat")), nodes);
+
+    return t.newExpression(
+      t.callExpression(
+        t.memberExpression(file.addHelper("bind"), t.identifier("apply")),
+        [node.callee, args]
+      ),
+      []
+    );
   }
-
-  node.arguments.unshift(contextLiteral);
-}
-
-export function NewExpression(node, parent, scope, file) {
-  var args = node.arguments;
-  if (!hasSpread(args)) return;
-
-  var nodes = build(args, scope);
-
-  var context = t.arrayExpression([t.literal(null)]);
-
-  args = t.callExpression(t.memberExpression(context, t.identifier("concat")), nodes);
-
-  return t.newExpression(
-    t.callExpression(
-      t.memberExpression(file.addHelper("bind"), t.identifier("apply")),
-      [node.callee, args]
-    ),
-    []
-  );
-}
+};

src/babel/transformation/transformers/es6/tail-call.js

@@ -9,11 +9,13 @@ export var metadata = {
   group: "builtin-trailing"
 };
 
-export function Func/*tion*/(node, parent, scope, file) {
-  if (node.generator || node.async) return;
-  var tailCall = new TailCallTransformer(this, scope, file);
-  tailCall.run();
-}
+export var visitor = {
+  Function(node, parent, scope, file) {
+    if (node.generator || node.async) return;
+    var tailCall = new TailCallTransformer(this, scope, file);
+    tailCall.run();
+  }
+};
 
 function returnBlock(expr) {
   return t.blockStatement([t.returnStatement(expr)]);
@@ -148,7 +150,7 @@ class TailCallTransformer {
 
     //
 
-    var body = t.ensureBlock(node).body;
+    var body = this.path.ensureBlock().body;
 
     for (var i = 0; i < body.length; i++) {
       var bodyNode = body[i];

src/babel/transformation/transformers/es6/template-literals.js

@@ -6,6 +6,10 @@ export var metadata = {
   group: "builtin-pre"
 };
 
+function isString(node) {
+  return t.isLiteral(node) && typeof node.value === "string";
+}
+
 function buildBinaryExpression(left, right) {
   var node = t.binaryExpression("+", left, right);
   node._templateLiteralProduced = true;
@@ -16,59 +20,70 @@ function crawl(path) {
   if (path.is("_templateLiteralProduced")) {
     crawl(path.get("left"));
     crawl(path.get("right"));
-  } else if (!path.isTypeAnnotationGeneric("String") && !path.isTypeAnnotationGeneric("Number")) {
+  } else if (!path.isBaseType("string") && !path.isBaseType("number")) {
     path.replaceWith(t.callExpression(t.identifier("String"), [path.node]));
   }
 }
 
-export function TaggedTemplateExpression(node, parent, scope, file) {
-  var quasi = node.quasi;
-  var args  = [];
+export var visitor = {
+  TaggedTemplateExpression(node, parent, scope, file) {
+    var quasi = node.quasi;
+    var args  = [];
 
-  var strings = [];
-  var raw     = [];
+    var strings = [];
+    var raw     = [];
 
-  for (var elem of (quasi.quasis: Array)) {
-    strings.push(t.literal(elem.value.cooked));
-    raw.push(t.literal(elem.value.raw));
-  }
-
-  strings = t.arrayExpression(strings);
-  raw = t.arrayExpression(raw);
-
-  var templateName = "tagged-template-literal";
-  if (file.isLoose("es6.templateLiterals")) templateName += "-loose";
-  args.push(t.callExpression(file.addHelper(templateName), [strings, raw]));
-
-  args = args.concat(quasi.expressions);
-
-  return t.callExpression(node.tag, args);
-}
-
-export function TemplateLiteral(node, parent, scope, file) {
-  var nodes = [];
-
-  for (let elem of (node.quasis: Array)) {
-    nodes.push(t.literal(elem.value.cooked));
-
-    var expr = node.expressions.shift();
-    if (expr) nodes.push(expr);
-  }
-
-  if (nodes.length > 1) {
-    // remove redundant '' at the end of the expression
-    var last = nodes[nodes.length - 1];
-    if (t.isLiteral(last, { value: "" })) nodes.pop();
-
-    var root = buildBinaryExpression(nodes.shift(), nodes.shift());
-
-    for (let node of (nodes: Array)) {
-      root = buildBinaryExpression(root, node);
+    for (var elem of (quasi.quasis: Array)) {
+      strings.push(t.literal(elem.value.cooked));
+      raw.push(t.literal(elem.value.raw));
     }
 
-    this.replaceWith(root);
-    //crawl(this);
-  } else {
-    return nodes[0];
+    strings = t.arrayExpression(strings);
+    raw = t.arrayExpression(raw);
+
+    var templateName = "tagged-template-literal";
+    if (file.isLoose("es6.templateLiterals")) templateName += "-loose";
+    args.push(t.callExpression(file.addHelper(templateName), [strings, raw]));
+
+    args = args.concat(quasi.expressions);
+
+    return t.callExpression(node.tag, args);
+  },
+
+  TemplateLiteral(node, parent, scope, file) {
+    var nodes = [];
+
+    for (let elem of (node.quasis: Array)) {
+      nodes.push(t.literal(elem.value.cooked));
+
+      var expr = node.expressions.shift();
+      if (expr) nodes.push(expr);
+    }
+
+    if (nodes.length > 1) {
+      // filter out empty string literals
+      nodes = nodes.filter(n => !t.isLiteral(n, { value: "" }));
+
+      if (nodes.length === 1 && isString(nodes[0])) {
+        return nodes[0];
+      }
+
+      // since `+` is left-to-right associative
+      // ensure the first node is a string if first/second isn't
+      if (!isString(nodes[0]) && !isString(nodes[1])) {
+        nodes.unshift(t.literal(""));
+      }
+
+      var root = buildBinaryExpression(nodes.shift(), nodes.shift());
+
+      for (let node of (nodes: Array)) {
+        root = buildBinaryExpression(root, node);
+      }
+
+      this.replaceWith(root);
+      //crawl(this);
+    } else {
+      return nodes[0];
+    }
   }
-}
+};

src/babel/transformation/transformers/es7/comprehensions.js

@@ -7,11 +7,13 @@ export var metadata = {
   stage: 0
 };
 
-export function ComprehensionExpression(node, parent, scope, file) {
-  var callback = array;
-  if (node.generator) callback = generator;
-  return callback(node, parent, scope);
-}
+export var visitor = {
+  ComprehensionExpression(node, parent, scope) {
+    var callback = array;
+    if (node.generator) callback = generator;
+    return callback(node, parent, scope);
+  }
+};
 
 function generator(node) {
   var body = [];

src/babel/transformation/transformers/es7/decorators.js

@@ -8,35 +8,37 @@ export var metadata = {
   stage: 1
 };
 
-export function ObjectExpression(node, parent, scope, file) {
-  var hasDecorators = false;
-  for (let i = 0; i < node.properties.length; i++) {
-    let prop = node.properties[i];
-    if (prop.decorators) {
-      hasDecorators = true;
-      break;
+export var visitor = {
+  ObjectExpression(node, parent, scope, file) {
+    var hasDecorators = false;
+    for (let i = 0; i < node.properties.length; i++) {
+      let prop = node.properties[i];
+      if (prop.decorators) {
+        hasDecorators = true;
+        break;
+      }
     }
-  }
-  if (!hasDecorators) return;
+    if (!hasDecorators) return;
 
-  var mutatorMap = {};
+    var mutatorMap = {};
 
-  for (let i = 0; i < node.properties.length; i++) {
-    let prop = node.properties[i];
-    if (prop.decorators) memoiseDecorators(prop.decorators, scope);
+    for (let i = 0; i < node.properties.length; i++) {
+      let prop = node.properties[i];
+      if (prop.decorators) memoiseDecorators(prop.decorators, scope);
 
 
-    if (prop.kind === "init" && !prop.method) {
-      prop.kind = "";
-      prop.value = t.functionExpression(null, [], t.blockStatement([
-        t.returnStatement(prop.value)
-      ]));
+      if (prop.kind === "init" && !prop.method) {
+        prop.kind = "";
+        prop.value = t.functionExpression(null, [], t.blockStatement([
+          t.returnStatement(prop.value)
+        ]));
+      }
+
+      defineMap.push(mutatorMap, prop, "initializer", file);
     }
 
-    defineMap.push(mutatorMap, prop, "initializer", file);
+    var obj = defineMap.toClassObject(mutatorMap);
+    obj = defineMap.toComputedObjectFromClass(obj);
+    return t.callExpression(file.addHelper("create-decorated-object"), [obj]);
   }
-
-  var obj = defineMap.toClassObject(mutatorMap);
-  obj = defineMap.toComputedObjectFromClass(obj);
-  return t.callExpression(file.addHelper("create-decorated-object"), [obj]);
-}
+};

src/babel/transformation/transformers/es7/do-expressions.js

@@ -5,11 +5,13 @@ export var metadata = {
   stage: 0
 };
 
-export function DoExpression(node) {
-  var body = node.body.body;
-  if (body.length) {
-    return body;
-  } else {
-    return t.identifier("undefined");
+export var visitor = {
+  DoExpression(node) {
+    var body = node.body.body;
+    if (body.length) {
+      return body;
+    } else {
+      return t.identifier("undefined");
+    }
   }
-}
+};

src/babel/transformation/transformers/es7/exponentiation-operator.js

@@ -9,20 +9,10 @@ export var metadata = {
 
 var MATH_POW = t.memberExpression(t.identifier("Math"), t.identifier("pow"));
 
-var {
-  ExpressionStatement,
-  AssignmentExpression,
-  BinaryExpression
-} = build({
+export var visitor = build({
   operator: "**",
 
   build(left, right) {
     return t.callExpression(MATH_POW, [left, right]);
   }
 });
-
-export {
-  ExpressionStatement,
-  AssignmentExpression,
-  BinaryExpression
-};

src/babel/transformation/transformers/es7/export-extensions.js

@@ -26,14 +26,16 @@ function build(node, nodes, scope) {
   build(node, nodes, scope);
 }
 
-export function ExportNamedDeclaration(node, parent, scope) {
-  var nodes = [];
-  build(node, nodes, scope);
-  if (!nodes.length) return;
+export var visitor = {
+  ExportNamedDeclaration(node, parent, scope) {
+    var nodes = [];
+    build(node, nodes, scope);
+    if (!nodes.length) return;
 
-  if (node.specifiers.length >= 1) {
-    nodes.push(node);
+    if (node.specifiers.length >= 1) {
+      nodes.push(node);
+    }
+
+    return nodes;
   }
-
-  return nodes;
-}
+};

src/babel/transformation/transformers/es7/function-bind.js

@@ -36,16 +36,18 @@ function inferBindContext(bind, scope) {
   return tempId;
 }
 
-export function CallExpression(node, parent, scope, file) {
-  var bind = node.callee;
-  if (!t.isBindExpression(bind)) return;
+export var visitor = {
+  CallExpression(node, parent, scope) {
+    var bind = node.callee;
+    if (!t.isBindExpression(bind)) return;
 
-  var context = inferBindContext(bind, scope);
-  node.callee = t.memberExpression(bind.callee, t.identifier("call"));
-  node.arguments.unshift(context);
-}
+    var context = inferBindContext(bind, scope);
+    node.callee = t.memberExpression(bind.callee, t.identifier("call"));
+    node.arguments.unshift(context);
+  },
 
-export function BindExpression(node, parent, scope, file) {
-  var context = inferBindContext(node, scope);
-  return t.callExpression(t.memberExpression(node.callee, t.identifier("bind")), [context]);
-}
+  BindExpression(node, parent, scope) {
+    var context = inferBindContext(node, scope);
+    return t.callExpression(t.memberExpression(node.callee, t.identifier("bind")), [context]);
+  }
+};

src/babel/transformation/transformers/es7/object-rest-spread.js

@@ -16,33 +16,35 @@ var hasSpread = function (node) {
   return false;
 };
 
-export function ObjectExpression(node, parent, scope, file) {
-  if (!hasSpread(node)) return;
+export var visitor = {
+  ObjectExpression(node, parent, scope, file) {
+    if (!hasSpread(node)) return;
 
-  var args = [];
-  var props = [];
+    var args = [];
+    var props = [];
 
-  var push = function () {
-    if (!props.length) return;
-    args.push(t.objectExpression(props));
-    props = [];
-  };
+    var push = function () {
+      if (!props.length) return;
+      args.push(t.objectExpression(props));
+      props = [];
+    };
 
-  for (var i = 0; i < node.properties.length; i++) {
-    var prop = node.properties[i];
-    if (t.isSpreadProperty(prop)) {
-      push();
-      args.push(prop.argument);
-    } else {
-      props.push(prop);
+    for (var i = 0; i < node.properties.length; i++) {
+      var prop = node.properties[i];
+      if (t.isSpreadProperty(prop)) {
+        push();
+        args.push(prop.argument);
+      } else {
+        props.push(prop);
+      }
     }
+
+    push();
+
+    if (!t.isObjectExpression(args[0])) {
+      args.unshift(t.objectExpression([]));
+    }
+
+    return t.callExpression(file.addHelper("extends"), args);
   }
-
-  push();
-
-  if (!t.isObjectExpression(args[0])) {
-    args.unshift(t.objectExpression([]));
-  }
-
-  return t.callExpression(file.addHelper("extends"), args);
-}
+};

src/babel/transformation/transformers/index.js

@@ -1,34 +1,35 @@
 export default {
   //- builtin-prepass
-  "minification.constantFolding":          require("./minification/constant-folding"),
+  "minification.constantFolding":          require("babel-plugin-constant-folding"),
 
   //- builtin-pre
   strict:                                  require("./other/strict"),
-  eval:                                    require("./other/eval"),
+  eval:                                    require("babel-plugin-eval"),
   _explode:                                require("./internal/explode"),
   _validation:                             require("./internal/validation"),
   _hoistDirectives:                        require("./internal/hoist-directives"),
-  "minification.removeDebugger":           require("./minification/remove-debugger"),
-  "minification.removeConsole":            require("./minification/remove-console"),
-  "utility.inlineEnvironmentVariables":    require("./utility/inline-environment-variables"),
-  "minification.deadCodeElimination":      require("./minification/dead-code-elimination"),
+  "minification.removeDebugger":           require("babel-plugin-remove-debugger"),
+  "minification.removeConsole":            require("babel-plugin-remove-console"),
+  "utility.inlineEnvironmentVariables":    require("babel-plugin-inline-environment-variables"),
+  "minification.deadCodeElimination":      require("babel-plugin-dead-code-elimination"),
   _modules:                                require("./internal/modules"),
-  "spec.functionName":                     require("./spec/function-name"),
+  "react.displayName":                     require("babel-plugin-react-display-name"),
   "es6.spec.templateLiterals":             require("./es6/spec.template-literals"),
   "es6.templateLiterals":                  require("./es6/template-literals"),
+  "validation.undeclaredVariableCheck":    require("babel-plugin-undeclared-variables-check"),
 
   //- builtin-basic
   // this is where the bulk of the ES6 transformations take place, none of them require traversal state
   // so they can all be concatenated together for performance
+  "spec.functionName":                     require("./spec/function-name"),
   "es7.classProperties":                   require("./es7/class-properties"),
   "es7.trailingFunctionCommas":            require("./es7/trailing-function-commas"),
   "es7.asyncFunctions":                    require("./es7/async-functions"),
   "es7.decorators":                        require("./es7/decorators"),
-  "validation.undeclaredVariableCheck":    require("./validation/undeclared-variable-check"),
   "validation.react":                      require("./validation/react"),
   "es6.arrowFunctions":                    require("./es6/arrow-functions"),
   "spec.blockScopedFunctions":             require("./spec/block-scoped-functions"),
-  "optimisation.react.constantElements":   require("./optimisation/react.constant-elements"),
+  "optimisation.react.constantElements":   require("babel-plugin-react-constant-elements"),
   "optimisation.react.inlineElements":     require("./optimisation/react.inline-elements"),
   "es7.comprehensions":                    require("./es7/comprehensions"),
   "es6.classes":                           require("./es6/classes"),
@@ -49,11 +50,11 @@ export default {
   "es6.spread":                            require("./es6/spread"),
   "es6.parameters.default":                require("./es6/parameters.default"),
   "es7.exportExtensions":                  require("./es7/export-extensions"),
-  "spec.protoToAssign":                    require("./spec/proto-to-assign"),
+  "spec.protoToAssign":                    require("babel-plugin-proto-to-assign"),
   "es7.doExpressions":                     require("./es7/do-expressions"),
   "es6.spec.symbols":                      require("./es6/spec.symbols"),
   "es7.functionBind":                      require("./es7/function-bind"),
-  "spec.undefinedToVoid":                  require("./spec/undefined-to-void"),
+  "spec.undefinedToVoid":                  require("babel-plugin-undefined-to-void"),
 
   //- builtin-advanced
   "es6.destructuring":                     require("./es6/destructuring"),
@@ -67,7 +68,7 @@ export default {
   // hissy fit
 
   //- builtin-modules
-  runtime:                                 require("./other/runtime"),
+  runtime:                                 require("babel-plugin-runtime"),
   "es6.modules":                           require("./es6/modules"),
   _moduleFormatter:                        require("./internal/module-formatter"),
 
@@ -79,9 +80,9 @@ export default {
   _shadowFunctions:                        require("./internal/shadow-functions"),
   "es3.propertyLiterals":                  require("./es3/property-literals"),
   "es3.memberExpressionLiterals":          require("./es3/member-expression-literals"),
-  "minification.memberExpressionLiterals": require("./minification/member-expression-literals"),
-  "minification.propertyLiterals":         require("./minification/property-literals"),
+  "minification.memberExpressionLiterals": require("babel-plugin-member-expression-literals"),
+  "minification.propertyLiterals":         require("babel-plugin-property-literals"),
   _blockHoist:                             require("./internal/block-hoist"),
-  jscript:                                 require("./other/jscript"),
+  jscript:                                 require("babel-plugin-jscript"),
   flow:                                    require("./other/flow"),
 };

src/babel/transformation/transformers/internal/block-hoist.js

@@ -11,24 +11,24 @@ export var metadata = {
 //  - 2 Priority over normal nodes
 //  - 3 We want this to be at the **very** top
 
-export var BlockStatement = {
-  exit(node) {
-    var hasChange = false;
-    for (var i = 0; i < node.body.length; i++) {
-      var bodyNode = node.body[i];
-      if (bodyNode && bodyNode._blockHoist != null) hasChange = true;
+export var visitor = {
+  Block: {
+    exit(node) {
+      var hasChange = false;
+      for (var i = 0; i < node.body.length; i++) {
+        var bodyNode = node.body[i];
+        if (bodyNode && bodyNode._blockHoist != null) hasChange = true;
+      }
+      if (!hasChange) return;
+
+      node.body = sortBy(node.body, function(bodyNode){
+        var priority = bodyNode && bodyNode._blockHoist;
+        if (priority == null) priority = 1;
+        if (priority === true) priority = 2;
+
+        // Higher priorities should move toward the top.
+        return -1 * priority;
+      });
     }
-    if (!hasChange) return;
-
-    node.body = sortBy(node.body, function(bodyNode){
-      var priority = bodyNode && bodyNode._blockHoist;
-      if (priority == null) priority = 1;
-      if (priority === true) priority = 2;
-
-      // Higher priorities should move toward the top.
-      return -1 * priority;
-    });
   }
 };
-
-export { BlockStatement as Program };

src/babel/transformation/transformers/internal/explode.js

@@ -25,9 +25,10 @@ function buildListClone(listKey, bindingKey, refKey) {
   };
 }
 
-export var Property = buildClone("value", "key", function (node) {
-  return t.isAssignmentPattern(node.value) && node.value.left === node.key;
-});
-
-export var ExportDeclaration = buildListClone("specifiers", "local", "exported");
-export var ImportDeclaration = buildListClone("specifiers", "local", "imported");
+export var visitor = {
+  Property: buildClone("value", "key", function (node) {
+    return t.isAssignmentPattern(node.value) && node.value.left === node.key;
+  }),
+  ExportDeclaration: buildListClone("specifiers", "local", "exported"),
+  ImportDeclaration: buildListClone("specifiers", "local", "imported")
+};

src/babel/transformation/transformers/internal/hoist-directives.js

@@ -4,17 +4,17 @@ export var metadata = {
   group: "builtin-pre"
 };
 
-export var BlockStatement = {
-  exit(node) {
-    for (var i = 0; i < node.body.length; i++) {
-      var bodyNode = node.body[i];
-      if (t.isExpressionStatement(bodyNode) && t.isLiteral(bodyNode.expression)) {
-        bodyNode._blockHoist = Infinity;
-      } else {
-        return;
+export var visitor = {
+  Block: {
+    exit(node) {
+      for (var i = 0; i < node.body.length; i++) {
+        var bodyNode = node.body[i];
+        if (t.isExpressionStatement(bodyNode) && t.isLiteral(bodyNode.expression)) {
+          bodyNode._blockHoist = Infinity;
+        } else {
+          return;
+        }
       }
     }
   }
 };
-
-export { BlockStatement as Program };

src/babel/transformation/transformers/internal/module-formatter.js

@@ -2,19 +2,21 @@ export var metadata = {
   group: "builtin-modules"
 };
 
-export var Program = {
-  exit(program, parent, scope, file) {
-    // ensure that these are at the top, just like normal imports
-    for (var node of (file.dynamicImports: Array)) {
-      node._blockHoist = 3;
-    }
+export var visitor = {
+  Program: {
+    exit(program, parent, scope, file) {
+      // ensure that these are at the top, just like normal imports
+      for (var node of (file.dynamicImports: Array)) {
+        node._blockHoist = 3;
+      }
 
-    program.body = file.dynamicImports.concat(program.body);
+      program.body = file.dynamicImports.concat(program.body);
 
-    if (!file.transformers["es6.modules"].canTransform()) return;
+      if (!file.transformers["es6.modules"].canTransform()) return;
 
-    if (file.moduleFormatter.transform) {
-      file.moduleFormatter.transform(program);
+      if (file.moduleFormatter.transform) {
+        file.moduleFormatter.transform(program);
+      }
     }
   }
 };

src/babel/transformation/transformers/internal/modules.js

@@ -15,93 +15,95 @@ function getDeclar(node) {
   return declar;
 }
 
-export var metadata = {
-  group: "builtin-pre"
-};
-
-export function ExportDefaultDeclaration(node, parent, scope) {
-  var declar = node.declaration;
-
-  if (t.isClassDeclaration(declar)) {
-    // export default class Foo {};
-    let nodes = [getDeclar(node), node];
-    node.declaration = declar.id;
-    return nodes;
-  } else if (t.isClassExpression(declar)) {
-    // export default class {};
-    var temp = scope.generateUidIdentifier("default");
-    node.declaration = t.variableDeclaration("var", [
-      t.variableDeclarator(temp, declar)
-    ]);
-
-    let nodes = [getDeclar(node), node];
-    node.declaration = temp;
-    return nodes;
-  } else if (t.isFunctionDeclaration(declar)) {
-    // export default function Foo() {}
-    node._blockHoist = 2;
-
-    let nodes = [getDeclar(node), node];
-    node.declaration = declar.id;
-    return nodes;
-  }
-}
-
 function buildExportSpecifier(id) {
   return t.exportSpecifier(clone(id), clone(id));
 }
 
-export function ExportNamedDeclaration(node, parent, scope) {
-  var declar = node.declaration;
+export var metadata = {
+  group: "builtin-pre"
+};
 
-  if (t.isClassDeclaration(declar)) {
-    // export class Foo {}
-    node.specifiers  = [buildExportSpecifier(declar.id)];
+export var visitor = {
+  ExportDefaultDeclaration(node, parent, scope) {
+    var declar = node.declaration;
 
-    let nodes = [getDeclar(node), node];
-    node.declaration = null;
-    return nodes;
-  } else if (t.isFunctionDeclaration(declar)) {
-    // export function Foo() {}
-    node.specifiers  = [buildExportSpecifier(declar.id)];
-    node._blockHoist = 2;
+    if (t.isClassDeclaration(declar)) {
+      // export default class Foo {};
+      let nodes = [getDeclar(node), node];
+      node.declaration = declar.id;
+      return nodes;
+    } else if (t.isClassExpression(declar)) {
+      // export default class {};
+      var temp = scope.generateUidIdentifier("default");
+      node.declaration = t.variableDeclaration("var", [
+        t.variableDeclarator(temp, declar)
+      ]);
 
-    let nodes = [getDeclar(node), node];
-    node.declaration = null;
-    return nodes;
-  } else if (t.isVariableDeclaration(declar)) {
-    // export var foo = "bar";
-    var specifiers = [];
-    var bindings = this.get("declaration").getBindingIdentifiers();
-    for (var key in bindings) {
-      specifiers.push(buildExportSpecifier(bindings[key]));
+      let nodes = [getDeclar(node), node];
+      node.declaration = temp;
+      return nodes;
+    } else if (t.isFunctionDeclaration(declar)) {
+      // export default function Foo() {}
+      node._blockHoist = 2;
+
+      let nodes = [getDeclar(node), node];
+      node.declaration = declar.id;
+      return nodes;
     }
-    return [declar, t.exportNamedDeclaration(null, specifiers)];
-  }
-}
-
-export var Program = {
-  enter(node) {
-    var imports = [];
-    var rest = [];
-
-    for (var i = 0; i < node.body.length; i++) {
-      var bodyNode = node.body[i];
-      if (t.isImportDeclaration(bodyNode)) {
-        imports.push(bodyNode);
-      } else {
-        rest.push(bodyNode);
-      }
-    }
-
-    node.body = imports.concat(rest);
   },
 
-  exit(node, parent, scope, file) {
-    if (!file.transformers["es6.modules"].canTransform()) return;
+  ExportNamedDeclaration(node) {
+    var declar = node.declaration;
 
-    if (file.moduleFormatter.setup) {
-      file.moduleFormatter.setup();
+    if (t.isClassDeclaration(declar)) {
+      // export class Foo {}
+      node.specifiers  = [buildExportSpecifier(declar.id)];
+
+      let nodes = [getDeclar(node), node];
+      node.declaration = null;
+      return nodes;
+    } else if (t.isFunctionDeclaration(declar)) {
+      // export function Foo() {}
+      node.specifiers  = [buildExportSpecifier(declar.id)];
+      node._blockHoist = 2;
+
+      let nodes = [getDeclar(node), node];
+      node.declaration = null;
+      return nodes;
+    } else if (t.isVariableDeclaration(declar)) {
+      // export var foo = "bar";
+      var specifiers = [];
+      var bindings = this.get("declaration").getBindingIdentifiers();
+      for (var key in bindings) {
+        specifiers.push(buildExportSpecifier(bindings[key]));
+      }
+      return [declar, t.exportNamedDeclaration(null, specifiers)];
+    }
+  },
+
+  Program: {
+    enter(node) {
+      var imports = [];
+      var rest    = [];
+
+      for (var i = 0; i < node.body.length; i++) {
+        var bodyNode = node.body[i];
+        if (t.isImportDeclaration(bodyNode)) {
+          imports.push(bodyNode);
+        } else {
+          rest.push(bodyNode);
+        }
+      }
+
+      node.body = imports.concat(rest);
+    },
+
+    exit(node, parent, scope, file) {
+      if (!file.transformers["es6.modules"].canTransform()) return;
+
+      if (file.moduleFormatter.setup) {
+        file.moduleFormatter.setup();
+      }
     }
   }
 };

src/babel/transformation/transformers/internal/shadow-functions.js

@@ -8,7 +8,7 @@ function remap(path, key, create) {
   // ensure that we're shadowed
   if (!path.inShadow()) return;
 
-  var fnPath = path.findParent((node, path) => !node.shadow && (path.isFunction() || path.isProgram()));
+  var fnPath = path.findParent((path) => !path.is("shadow") && (path.isFunction() || path.isProgram()));
 
   var cached = fnPath.getData(key);
   if (cached) return cached;
@@ -22,12 +22,14 @@ function remap(path, key, create) {
   return id;
 }
 
-export function ThisExpression() {
-  return remap(this, "this", () => t.thisExpression());
-}
+export var visitor = {
+  ThisExpression() {
+    return remap(this, "this", () => t.thisExpression());
+  },
 
-export function ReferencedIdentifier(node) {
-  if (node.name === "arguments" && !node._shadowedFunctionLiteral) {
-    return remap(this, "arguments", () => t.identifier("arguments"));
+  ReferencedIdentifier(node) {
+    if (node.name === "arguments" && !node._shadowedFunctionLiteral) {
+      return remap(this, "arguments", () => t.identifier("arguments"));
+    }
   }
-}
+};

src/babel/transformation/transformers/internal/validation.js

@@ -5,41 +5,21 @@ export var metadata = {
   group: "builtin-pre"
 };
 
-export function ForOfStatement(node, parent, scope, file) {
-  var left = node.left;
-  if (t.isVariableDeclaration(left)) {
-    var declar = left.declarations[0];
-    if (declar.init) throw file.errorWithNode(declar, messages.get("noAssignmentsInForHead"));
-  }
-}
+export var visitor = {
+  ForXStatement(node, parent, scope, file) {
+    var left = node.left;
+    if (t.isVariableDeclaration(left)) {
+      var declar = left.declarations[0];
+      if (declar.init) throw file.errorWithNode(declar, messages.get("noAssignmentsInForHead"));
+    }
+  },
 
-export { ForOfStatement as ForInStatement };
-
-export function MethodDefinition(node) {
-  if (node.kind !== "constructor") {
-    // get constructor() {}
-    var isConstructor = !node.computed && t.isIdentifier(node.key, { name: "constructor" });
-
-    // get ["constructor"]() {}
-    isConstructor = isConstructor || t.isLiteral(node.key, { value: "constructor" });
-
-    if (isConstructor) {
-      throw this.errorWithNode(messages.get("classesIllegalConstructorKind"));
+  Property(node, parent, scope, file) {
+    if (node.kind === "set") {
+      var first = node.value.params[0];
+      if (t.isRestElement(first)) {
+        throw file.errorWithNode(first, messages.get("settersNoRest"));
+      }
     }
   }
-
-  Property.apply(this, arguments);
-}
-
-export function Property(node, parent, scope, file) {
-  if (node.kind === "set") {
-    if (node.value.params.length !== 1) {
-      throw file.errorWithNode(node.value, messages.get("settersInvalidParamLength"));
-    }
-
-    var first = node.value.params[0];
-    if (t.isRestElement(first)) {
-      throw file.errorWithNode(first, messages.get("settersNoRest"));
-    }
-  }
-}
+};