v5.6.14

This is necessary in order to retain correct function arity and to have
completely correct semantics. Sometimes features are tied together so much
that they would require so much desugaring to retain the correct semantics
that they'd be equivalent to... the normal transpiled output.

.babelrc

@@ -2,5 +2,6 @@
   "stage": 0,
   "loose": ["all"],
   "blacklist": ["es6.tailCall"],
-  "optional": ["optimisation.flow.forOf"]
+  "optional": ["optimisation.flow.forOf"],
+  "plugins": ["./tools/build-plugins/protect"]
 }

.eslintrc

@@ -17,7 +17,9 @@
     "no-fallthrough": 0,
     "new-cap": 0,
     "no-loop-func": 0,
-    "no-unreachable": 0
+    "no-unreachable": 0,
+    "no-labels": 0,
+    "no-process-exit": 0
   },
   "env": {
     "node": true

.travis.yml

@@ -1,14 +1,26 @@
-#sudo: false
 language: node_js
 cache:
   directories:
-    - node_modules
+  - node_modules
 node_js:
-  - "0.12"
-  - "iojs"
-
-before_script: "npm install -g codeclimate-test-reporter"
-script: "make test-travis"
-
+- '0.12'
+- iojs
+before_script: npm install -g codeclimate-test-reporter
+script: make test-travis
 notifications:
   slack: babeljs:5Wy4QX13KVkGy9CnU0rmvgeK
+before_deploy:
+- make prepublish
+after_deploy:
+- make publish-cli
+- make publish-runtime
+deploy:
+  provider: npm
+  email: sebmck@gmail.com
+  skip_cleanup: true
+  api_key:
+    secure: Q/pZStwherdYPCqCa0aUuiEktLcx6ccBxieyH8j9IXdDgty0ydmnajZfUnlZuCjN13XI9esM44nSJFTWZvntTryDQAQm37c63VXhAEnw/qrAINI06yt0gLBTT69/fKvIAkH8l48nmW32ZS2dse3rHRPZF1CwyQLC/pdMip8I4sM=
+  on:
+    branch: master
+    tags: true
+    repo: babel/babel

CHANGELOG.md

@@ -9,10 +9,115 @@
 > - [Internal]
 > - [Polish]
 
-_Note: Gaps between patch versions are faulty/broken releases._
+_Note: Gaps between patch versions are faulty, broken or test releases._
 
 See [CHANGELOG - 6to5](CHANGELOG-6to5.md) for the pre-4.0.0 version changelog.
 
+## 5.6.12
+
+ * **Bug Fix**
+  * Fix finding parent for top-level shadowed functions.
+
+## 5.6.11
+
+ ** **Internal**
+  * Merge `es6.parameters.rest` and `es6.parameters.default` transformers. See commit [c0fd4c1f9e0b18231f585c4fa793e4cb0e01aed1](https://github.com/babel/babel/commit/c0fd4c1f9e0b18231f585c4fa793e4cb0e01aed1) for more info.
+
+## 5.6.10
+
+ * **Bug Fix**
+  * Fix faulty internal require check.
+ * **Polish**
+  * Add support for trailing commas in arrow function parameter lists.
+
+## 5.6.8
+
+ * **Bug Fix**
+  * Fix binary expressions colliding with unary expression operators in compact mode.
+  * Fix node properties being set to `null` when using computed properties.
+
+## 5.6.7
+
+ * **Bug Fix**
+  * Fix hoisting of `ForXStatement` `left` `var`s when inserting a block scoping IIFE.
+ * **Polish**
+  * Combine all leading computed property initialisers into the root object in loose mode.
+ * **Internal**
+  * Deprecate returning of replacement strings from visitor methods.
+
+## 5.6.6
+
+ * **Bug Fix**
+  * Fix weird parser bug where `void` type annotations were being parsed as keywords causing the tokeniser to lose track of context.
+
+## 5.6.5
+
+ * **Bug Fix**
+  * Fix nested functions causing rest parameter optimisation to not properly detect when it should deopt on a reference.
+ * **Internal**
+  * Update Regenerator `0.8.31`.
+
+## 5.6.4
+
+ * **Internal**
+  * Add `ParenthesizedExpression` node type.
+
+## 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**

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
 
@@ -112,8 +113,6 @@ your [`$PATH`](http://unix.stackexchange.com/questions/26047/how-to-correctly-ad
 
 + [js-tokens](http://ghub.io/js-tokens) This is used to get tokens for syntax error highlighting.
 
-+ [leven](http://ghub.io/leven) A levenstein algorithm to determine how close a word is to another. This is used to offer suggestions when using the utility.undeclaredVariableCheck transformer.
-
 + [line-numbers](http://ghub.io/line-numbers) Used to produce the code frames in syntax errors.
 
 + [lodash](http://ghub.io/lodash) Used for various utilities.
@@ -173,3 +172,6 @@ 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

@@ -9,13 +9,13 @@ BROWSERIFY_IGNORE = -i esprima-fb
 
 export NODE_ENV = test
 
-.PHONY: clean test test-cov test-clean test-travis test-simple test-all test-browser test-parser publish build bootstrap publish-core publish-runtime build-core watch-core build-core-test clean-core
+.PHONY: clean test test-cov test-clean test-travis test-simple test-all test-browser test-parser publish build bootstrap publish-core publish-runtime build-core watch-core build-core-test clean-core prepublish
 
 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
@@ -24,7 +24,7 @@ clean-core:
 	rm -rf lib
 
 lint:
-	eslint src/babel
+	eslint src/babel packages/babel-cli/bin
 
 build:
 	mkdir -p dist
@@ -81,34 +81,20 @@ test-browser:
 
 publish: lint
 	git pull --rebase
-
 	make test
-
 	read -p "Version: " version; \
 	npm version $$version --message "v%s"
-
-	make build
-
-	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
-
-	cp dist/external-helpers.js external-helpers.js
-	cp dist/external-helpers.min.js external-helpers.min.js
-
-	node tools/cache-templates
-	test -f templates.json
-
-	npm publish
-
 	git push --follow-tags
 
-	make publish-cli
-	make publish-runtime
-
-	rm -rf templates.json browser.js browser.min.js browser-polyfill.js browser-polyfill.min.js external-helpers.js external-helpers.min.js
+prepublish: build
+	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
+	cp dist/external-helpers.js external-helpers.js
+	cp dist/external-helpers.min.js external-helpers.min.js
+	node tools/cache-templates
+	test -f templates.json
 
 publish-runtime:
 	cd packages; \

README.md

@@ -5,17 +5,23 @@
 </p>
 
 <p align="center">
-  <strong>Babel</strong> is a compiler for writing next generation JavaScript.
+  The compiler for writing next generation JavaScript.
 </p>
 
+<p align="center">
+  <a href="https://travis-ci.org/babel/babel"><img alt="Build Status" src="https://img.shields.io/travis/babel/babel.svg?style=flat"></a>
+  <a href="http://issuestats.com/github/babel/babel"><img alt="Issue Stats" src="http://issuestats.com/github/babel/babel/badge/pr?style=flat"></a>
+  <a href="http://issuestats.com/github/babel/babel"><img alt="Issue Stats" src="http://issuestats.com/github/babel/babel/badge/issue?style=flat"></a>
+  <a href="http://badge.fury.io/js/babel-core"><img alt="npm version" src="https://badge.fury.io/js/babel-core.svg"></a>
+  <a href="https://npmjs.org/package/babel-core"><img alt="Downloads" src="http://img.shields.io/npm/dm/babel-core.svg"></a>
+</p>
+
+----
+
 <p align="center">
   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">
-  Issues without instructions to reproduce <strong>will be immediately closed<strong>.
-</p>
-
 <p align="center">
   For documentation and website issues please visit the <a href="https://github.com/babel/babel.github.io">babel.github.io</a> repo.
 </p>

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.

index.js

@@ -0,0 +1 @@
+module.exports = require("./lib/babel/api/node.js");

package.json

@@ -1,27 +1,26 @@
 {
   "name": "babel-core",
   "description": "A compiler for writing next generation JavaScript",
-  "version": "5.5.6",
+  "version": "5.6.14",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
   "license": "MIT",
   "repository": "babel/babel",
-  "main": "lib/babel/api/node.js",
   "browser": {
     "./lib/babel/api/register/node.js": "./lib/babel/api/register/browser.js"
   },
   "keywords": [
-    "harmony",
+    "6to5",
+    "babel",
     "classes",
-    "modules",
-    "let",
     "const",
-    "var",
     "es6",
+    "harmony",
+    "let",
+    "modules",
     "transpile",
     "transpiler",
-    "6to5",
-    "babel"
+    "var"
   ],
   "scripts": {
     "bench": "make bench",
@@ -30,28 +29,42 @@
   "dependencies": {
     "acorn-jsx": "^1.0.0",
     "ast-types": "~0.7.0",
-    "bluebird": "^2.9.25",
+    "babel-eslint": "^3.1.19",
+    "babel-plugin-constant-folding": "^1.0.1",
+    "babel-plugin-dead-code-elimination": "^1.0.2",
+    "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",
-    "leven": "^1.0.1",
+    "js-tokens": "1.0.1",
     "line-numbers": "0.2.0",
     "lodash": "^3.6.0",
     "minimatch": "^2.0.3",
     "output-file-sync": "^1.1.0",
+    "path-exists": "^1.0.0",
     "path-is-absolute": "^1.0.0",
     "private": "^0.1.6",
-    "regenerator": "0.8.28",
+    "regenerator": "0.8.31",
     "regexpu": "^1.1.2",
     "repeating": "^1.1.2",
     "resolve": "^1.1.6",
@@ -64,11 +77,11 @@
     "trim-right": "^1.0.0"
   },
   "devDependencies": {
-    "babel": "5.3.1",
+    "babel": "5.6.10",
+    "babel-eslint": "^3.1.9",
     "browserify": "^9.0.8",
     "chai": "^2.2.0",
     "eslint": "^0.21.2",
-    "babel-eslint": "^3.1.9",
     "esvalid": "^1.1.0",
     "istanbul": "^0.3.5",
     "matcha": "^0.6.0",

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

@@ -0,0 +1,141 @@
+#!/usr/bin/env node
+
+var pathExists = require("path-exists");
+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(path.join(__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 (!pathExists.sync("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/dir.js

@@ -1,4 +1,5 @@
 var outputFileSync = require("output-file-sync");
+var pathExists     = require("path-exists");
 var chokidar       = require("chokidar");
 var slash          = require("slash");
 var path           = require("path");
@@ -6,7 +7,7 @@ var util           = require("./util");
 var fs             = require("fs");
 var _              = require("lodash");
 
-module.exports = function (commander, filenames, opts) {
+module.exports = function (commander, filenames) {
   var write = function (src, relative) {
     // remove extension and then append back on .js
     relative = relative.replace(/\.(\w*?)$/, "") + ".js";
@@ -41,7 +42,7 @@ module.exports = function (commander, filenames, opts) {
   };
 
   var handle = function (filename) {
-    if (!fs.existsSync(filename)) return;
+    if (!pathExists.sync(filename)) return;
 
     var stat = fs.statSync(filename);
 

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

@@ -1,4 +1,5 @@
 var convertSourceMap = require("convert-source-map");
+var pathExists       = require("path-exists");
 var sourceMap        = require("source-map");
 var chokidar         = require("chokidar");
 var slash            = require("slash");
@@ -100,7 +101,7 @@ module.exports = function (commander, filenames, opts) {
     results = [];
 
     _.each(filenames, function (filename) {
-      if (!fs.existsSync(filename)) return;
+      if (!pathExists.sync(filename)) return;
 
       var stat = fs.statSync(filename);
       if (stat.isDirectory()) {

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

@@ -1,14 +1,17 @@
 #!/usr/bin/env node
 
+require("babel-core");
+
 var moduleFormatters = require("babel-core/lib/babel/transformation/modules");
+var pathExists       = require("path-exists");
 var commander        = require("commander");
 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");
 var glob             = require("glob");
 
 each(options, function (option, key) {
@@ -35,7 +38,7 @@ 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 +54,7 @@ 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);
     });
@@ -84,8 +87,10 @@ var filenames = commander.args.reduce(function (globbed, input) {
   return globbed.concat(files);
 }, []);
 
+filenames = uniq(filenames);
+
 each(filenames, function (filename) {
-  if (!fs.existsSync(filename)) {
+  if (!pathExists.sync(filename)) {
     errors.push(filename + " doesn't exist");
   }
 });
@@ -118,11 +123,16 @@ 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 +1,13 @@
 {
   "name": "babel",
   "description": "Turn ES6 code into readable vanilla ES5 with source maps",
-  "version": "5.5.5",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
   "license": "MIT",
   "repository": "babel/babel",
   "preferGlobal": true,
   "dependencies": {
-    "babel-core": "^5.5.5",
+    "babel-core": "^5.6.12",
     "chokidar": "^1.0.0",
     "commander": "^2.6.0",
     "convert-source-map": "^1.1.0",
@@ -16,6 +15,7 @@
     "glob": "^5.0.5",
     "lodash": "^3.2.0",
     "output-file-sync": "^1.1.0",
+    "path-exists": "^1.0.0",
     "path-is-absolute": "^1.0.0",
     "source-map": "^0.4.0",
     "slash": "^1.0.0"
@@ -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

@@ -1,11 +1,10 @@
 {
   "name": "babel-runtime",
   "description": "babel selfContained runtime",
-  "version": "5.5.5",
   "license": "MIT",
   "repository": "babel/babel",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "dependencies": {
     "core-js": "^0.9.0"
   }
-}
+}

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/plugins/flow.js

@@ -1,3 +1,4 @@
+Error.stackTraceLimit = Infinity;
 var acorn = require("../src/index")
 
 var pp = acorn.Parser.prototype
@@ -41,8 +42,11 @@ pp.flow_parseDeclareFunction = function (node) {
   typeNode.rest = tmp.rest
   this.expect(tt.parenR)
 
+  var oldInType = this.inType
+  this.inType = true
   this.expect(tt.colon)
   typeNode.returnType = this.flow_parseType()
+  this.inType = oldInType
 
   typeContainer.typeAnnotation = this.finishNode(typeNode, "FunctionTypeAnnotation")
   id.typeAnnotation = this.finishNode(typeContainer, "TypeAnnotation")
@@ -352,12 +356,6 @@ pp.flow_parseGenericType = function (start, id) {
   return this.finishNode(node, "GenericTypeAnnotation")
 }
 
-pp.flow_parseVoidType = function () {
-  var node = this.startNode()
-  this.expect(tt._void)
-  return this.finishNode(node, "VoidTypeAnnotation")
-}
-
 pp.flow_parseTypeofType = function () {
   var node = this.startNode()
   this.expect(tt._typeof)
@@ -411,6 +409,9 @@ pp.flow_identToTypeAnnotation = function (start, node, id) {
     case "any":
       return this.finishNode(node, "AnyTypeAnnotation")
 
+    case "void":
+      return this.finishNode(node, "VoidTypeAnnotation")
+
     case "bool":
     case "boolean":
       return this.finishNode(node, "BooleanTypeAnnotation")
@@ -524,14 +525,8 @@ pp.flow_parsePrimaryType = function () {
       return this.finishNode(node, "StringLiteralTypeAnnotation")
 
     default:
-      if (this.type.keyword) {
-        switch (this.type.keyword) {
-          case "void":
-            return this.flow_parseVoidType()
-
-          case "typeof":
-            return this.flow_parseTypeofType()
-        }
+      if (this.type.keyword === "typeof") {
+        return this.flow_parseTypeofType()
       }
   }
 
@@ -694,6 +689,18 @@ acorn.plugins.flow = function (instance) {
     }
   })
 
+  // don't consider `void` to be a keyword as then it'll use the void token type
+  // and set startExpr
+  instance.extend("isKeyword", function (inner) {
+    return function(name) {
+      if (this.inType && name === "void") {
+        return false
+      } else {
+        return inner.call(this, name)
+      }
+    }
+  })
+
   instance.extend("readToken", function (inner) {
     return function(code) {
       if (this.inType && (code === 62 || code === 60)) {

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()
@@ -421,9 +432,18 @@ pp.parseParenAndDistinguishExpression = function(start, isAsync, canBeArrow) {
     }
 
     let innerStart = this.markPosition(), exprList = [], first = true
-    let refShorthandDefaultPos = {start: 0}, spreadStart, innerParenStart
+    let refShorthandDefaultPos = {start: 0}, spreadStart, innerParenStart, optionalCommaStart
     while (this.type !== tt.parenR) {
-      first ? first = false : this.expect(tt.comma)
+      if (first) {
+        first = false;
+      } else {
+        this.expect(tt.comma)
+        if (this.type === tt.parenR && this.options.features["es7.trailingFunctionCommas"]) {
+          optionalCommaStart = this.start
+          break
+        }
+      }
+
       if (this.type === tt.ellipsis) {
         let spreadNodeStart = this.markPosition()
         spreadStart = this.start
@@ -451,6 +471,7 @@ pp.parseParenAndDistinguishExpression = function(start, isAsync, canBeArrow) {
         this.unexpected(this.lastTokStart)
       }
     }
+    if (optionalCommaStart) this.unexpected(optionalCommaStart)
     if (spreadStart) this.unexpected(spreadStart)
     if (refShorthandDefaultPos.start) this.unexpected(refShorthandDefaultPos.start)
 
@@ -609,6 +630,14 @@ 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 +663,12 @@ 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

@@ -19,7 +19,11 @@ var STATE_KEYS = [
   "exprAllowed",
   "potentialArrowAt",
   "currLine",
-  "input"
+  "input",
+  "inType",
+  "inFunction",
+  "inGenerator",
+  "labels"
 ];
 
 pp.getState = function () {
@@ -29,6 +33,7 @@ pp.getState = function () {
     state[key] = this[key]
   }
   state.context = this.context.slice()
+  state.labels = this.labels.slice()
   return state
 };
 

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

@@ -1,13 +1,14 @@
 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
-  this.loadPlugins(this.options.plugins)
   this.sourceFile = this.options.sourceFile || null
   this.isKeyword = keywords[this.options.ecmaVersion >= 6 ? 6 : 5]
   this.isReservedWord = reservedWords[this.options.ecmaVersion]
   this.input = input
+  this.loadPlugins(this.options.plugins)
 
   // Set up token state
 

src/acorn/src/statement.js

@@ -347,7 +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
@@ -466,6 +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 = []
@@ -480,16 +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))
@@ -500,23 +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/acorn/src/tokentype.js

@@ -112,7 +112,7 @@ kw("case", beforeExpr)
 kw("catch")
 kw("continue")
 kw("debugger")
-kw("default")
+kw("default", beforeExpr)
 kw("do", {isLoop: true})
 kw("else", beforeExpr)
 kw("finally")

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/cache.js

@@ -1,6 +1,7 @@
 import path from "path";
 import fs from "fs";
 import homeOrTmp from "home-or-tmp";
+import pathExists from "path-exists";
 
 const FILENAME = process.env.BABEL_CACHE_PATH || path.join(homeOrTmp, ".babel.json");
 var data = {};
@@ -15,7 +16,7 @@ export function load() {
   process.on("exit", save);
   process.nextTick(save);
 
-  if (!fs.existsSync(FILENAME)) return;
+  if (!pathExists.sync(FILENAME)) return;
 
   try {
     data = JSON.parse(fs.readFileSync(FILENAME));

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, {
-        auxiliaryComment: "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/buffer.js

@@ -54,9 +54,10 @@ export default class Buffer {
     this.space();
   }
 
-  space() {
-    if (this.format.compact) return;
-    if (this.buf && !this.isLast(" ") && !this.isLast("\n")) {
+  space(force?) {
+    if (!force && this.format.compact) return;
+
+    if (force || this.buf && !this.isLast(" ") && !this.isLast("\n")) {
       this.push(" ");
     }
   }
@@ -155,8 +156,12 @@ export default class Buffer {
     this.buf += str;
   }
 
-  endsWith(str) {
-    return this.buf.slice(-str.length) === str;
+  endsWith(str, buf = this.buf) {
+    if (str.length === 1) {
+      return buf[buf.length - 1] === str;
+    } else {
+      return buf.slice(-str.length) === str;
+    }
   }
 
   isLast(cha) {

src/babel/generation/generators/classes.js

@@ -1,5 +1,5 @@
 export function ClassDeclaration(node, print) {
-  print.list(node.decorators);
+  print.list(node.decorators, { separator: "" });
   this.push("class");
 
   if (node.id) {
@@ -43,7 +43,7 @@ export function ClassBody(node, print) {
 
 
 export function ClassProperty(node, print) {
-  print.list(node.decorators);
+  print.list(node.decorators, { separator: "" });
 
   if (node.static) this.push("static ");
   print.plain(node.key);
@@ -58,7 +58,7 @@ export function ClassProperty(node, print) {
 }
 
 export function MethodDefinition(node, print) {
-  print.list(node.decorators);
+  print.list(node.decorators, { separator: "" });
 
   if (node.static) {
     this.push("static ");

src/babel/generation/generators/expressions.js

@@ -1,21 +1,20 @@
-import isInteger from "is-integer";
 import isNumber from "lodash/lang/isNumber";
 import * as t from "../../types";
 
 export function UnaryExpression(node, print) {
-  var hasSpace = /[a-z]$/.test(node.operator);
+  var needsSpace = /[a-z]$/.test(node.operator);
   var arg = node.argument;
 
   if (t.isUpdateExpression(arg) || t.isUnaryExpression(arg)) {
-    hasSpace = true;
+    needsSpace = true;
   }
 
   if (t.isUnaryExpression(arg) && arg.operator === "!") {
-    hasSpace = false;
+    needsSpace = false;
   }
 
   this.push(node.operator);
-  if (hasSpace) this.push(" ");
+  if (needsSpace) this.push(" ");
   print.plain(node.argument);
 }
 
@@ -25,6 +24,12 @@ export function DoExpression(node, print) {
   print.plain(node.body);
 }
 
+export function ParenthesizedExpression(node, print) {
+  this.push("(");
+  print.plain(node.expression);
+  this.push(")");
+}
+
 export function UpdateExpression(node, print) {
   if (node.prefix) {
     this.push(node.operator);
@@ -70,6 +75,7 @@ export function Super() {
 export function Decorator(node, print) {
   this.push("@");
   print.plain(node.expression);
+  this.newline();
 }
 
 export function CallExpression(node, print) {
@@ -77,19 +83,16 @@ export function CallExpression(node, print) {
 
   this.push("(");
 
-  var separator = ",";
-
-  var isPrettyCall = node._prettyCall && !this.format.retainLines;
+  var isPrettyCall = node._prettyCall && !this.format.retainLines && !this.format.compact;
 
+  var separator;
   if (isPrettyCall) {
-    separator += "\n";
+    separator = ",\n";
     this.newline();
     this.indent();
-  } else {
-    separator += " ";
   }
 
-  print.list(node.arguments, { separator: separator });
+  print.list(node.arguments, { separator });
 
   if (isPrettyCall) {
     this.newline();
@@ -126,12 +129,32 @@ 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);
-  this.push(" ");
+
+  var spaces = node.operator === "in" || node.operator === "instanceof";
+  spaces = true; // todo: https://github.com/babel/babel/issues/1835
+  this.space(spaces);
+
   this.push(node.operator);
-  this.push(" ");
+
+  if (!spaces) {
+    // space is mandatory to avoid outputting <!--
+    // http://javascript.spec.whatwg.org/#comment-syntax
+    spaces = node.operator === "<" &&
+             t.isUnaryExpression(node.right, { prefix: true, operator: "!" }) &&
+             t.isUnaryExpression(node.right.argument, { prefix: true, operator: "--" });
+  }
+
+  this.space(spaces);
+
   print.plain(node.right);
 }
 
@@ -143,12 +166,9 @@ 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 +187,6 @@ 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/methods.js

@@ -42,7 +42,7 @@ export function _method(node, print) {
   }
 
   this._params(value, print);
-  this.push(" ");
+  this.space();
   print.plain(value.body);
 }
 

src/babel/generation/generators/statements.js

@@ -33,13 +33,13 @@ export function ForStatement(node, print) {
   this.push(";");
 
   if (node.test) {
-    this.push(" ");
+    this.space();
     print.plain(node.test);
   }
   this.push(";");
 
   if (node.update) {
-    this.push(" ");
+    this.space();
     print.plain(node.update);
   }
 
@@ -190,16 +190,29 @@ export function VariableDeclaration(node, print, parent) {
     }
   }
 
-  var sep = ",";
+  //
+  // use a pretty separator when we aren't in compact mode, have initializers and don't have retainLines on
+  // this will format declarations like:
+  //
+  //   var foo = "bar", bar = "foo";
+  //
+  // into
+  //
+  //   var foo = "bar",
+  //       bar = "foo";
+  //
+
+  var sep;
   if (!this.format.compact && !this.format.concise && hasInits && !this.format.retainLines) {
-    sep += `\n${repeating(" ", node.kind.length + 1)}`;
-  } else {
-    sep += " ";
+    sep = `,\n${repeating(" ", node.kind.length + 1)}`;
   }
 
+  //
+
   print.list(node.declarations, { separator: sep });
 
   if (t.isFor(parent)) {
+    // don't give semicolons to these nodes since they'll be inserted in the parent generator
     if (parent.left === node || parent.init === node) return;
   }
 

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) {
@@ -32,6 +33,8 @@ export function ObjectExpression(node, print) {
 export { ObjectExpression as ObjectPattern };
 
 export function Property(node, print) {
+  print.list(node.decorators, { separator: "" });
+
   if (node.method || node.kind === "get" || node.kind === "set") {
     this._method(node, print);
   } else {
@@ -79,7 +82,7 @@ export function ArrayExpression(node, print) {
       // both (all) of the holes.
       this.push(",");
     } else {
-      if (i > 0) this.push(" ");
+      if (i > 0) this.space();
       print.plain(elem);
       if (i < len - 1) this.push(",");
     }
@@ -90,14 +93,29 @@ 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 +134,16 @@ 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

@@ -128,8 +128,7 @@ class CodeGenerator {
     // catch up to this nodes newline if we're behind
     if (node.loc && this.format.retainLines && this.buffer.buf) {
       var needsParens = false;
-      if (!leftParenPrinted && parent &&
-          this.position.line < node.loc.start.line && t.isTerminatorless(parent)) {
+      if (!leftParenPrinted && parent && this.position.line < node.loc.start.line && t.isTerminatorless(parent)) {
         needsParens = true;
         this._push("(");
       }

src/babel/generation/node/printer.js

@@ -18,7 +18,11 @@ export default class NodePrinter {
   }
 
   list(items, opts = {}) {
-    if (opts.separator == null) opts.separator = ", ";
+    if (opts.separator == null) {
+      opts.separator = ",";
+      if (!this.generator.format.compact) opts.separator += " ";
+    }
+
     return this.join(items, opts);
   }
 

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

@@ -5,15 +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",
-  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.",
@@ -22,6 +19,9 @@ 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?",
@@ -34,10 +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/tools/protect.js

@@ -0,0 +1,9 @@
+import path from "path";
+
+var root = path.resolve(__dirname, "../../../");
+
+export default function (module) {
+  if (module.parent && module.parent.filename.indexOf(root) !== 0) {
+    throw new Error("Don't hotlink internal Babel files.");
+  }
+}

src/babel/transformation/file/index.js

@@ -1,26 +1,26 @@
+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";
 import defaults from "lodash/object/defaults";
 import includes from "lodash/collection/includes";
 import traverse from "../../traversal";
-import Hub from "../../traversal/hub";
 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";
@@ -52,7 +52,7 @@ export default class File {
     this.log      = new Logger(this, opts.filename || "unknown");
     this.ast      = {};
 
-    this.normalizeOptions(opts);
+    this.normaliseOptions(opts);
 
     this.buildTransformers();
 
@@ -98,10 +98,10 @@ export default class File {
 
   static soloHelpers = [];
 
-  static options = require("./options");
+  static options = optionsConfig;
 
-  normalizeOptions(opts: Object) {
-    opts = this.opts = assign({}, opts);
+  normaliseOptions(opts: Object) {
+    opts = this.opts = normaliseOptions(assign({}, opts));
 
     // resolve babelrc
     if (opts.filename) {
@@ -120,26 +120,28 @@ export default class File {
 
     // 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) {
         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 {
@@ -164,7 +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
@@ -241,7 +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;
       }
     }
@@ -258,7 +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) {
@@ -268,7 +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);
         }
@@ -276,11 +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;
@@ -330,7 +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);
@@ -341,14 +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;
   }
 
@@ -400,11 +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;
@@ -570,7 +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/logger.js

@@ -4,6 +4,8 @@ import buildDebug from "debug/node";
 var verboseDebug = buildDebug("babel:verbose");
 var generalDebug = buildDebug("babel");
 
+var seenDeprecatedMessages = [];
+
 export default class Logger {
   constructor(file: File, filename: string) {
     this.filename = filename;
@@ -25,9 +27,17 @@ export default class Logger {
   }
 
   deprecate(msg) {
-    if (!this.file.opts.suppressDeprecationMessages) {
-      console.error(this._buildMessage(msg));
-    }
+    if (this.file.opts.suppressDeprecationMessages) return;
+
+    msg = this._buildMessage(msg);
+
+    // already seen this message
+    if (seenDeprecatedMessages.indexOf(msg) >= 0) return;
+
+    // make sure we don't see it again
+    seenDeprecatedMessages.push(msg);
+
+    console.error(msg);
   }
 
   verbose(msg: string) {

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

@@ -78,7 +78,8 @@
   "blacklist": {
     "type": "transformerList",
     "description": "blacklist of transformers to NOT use",
-    "shorthand": "b"
+    "shorthand": "b",
+    "default": []
   },
 
   "whitelist": {
@@ -90,7 +91,8 @@
 
   "optional": {
     "type": "transformerList",
-    "description": "list of optional transformers to enable"
+    "description": "list of optional transformers to enable",
+    "default": []
   },
 
   "modules": {
@@ -122,12 +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": {
@@ -173,12 +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

@@ -1,17 +1,17 @@
 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";
+import pathExists from "path-exists";
 
 var cache = {};
 var jsons = {};
 
 function exists(filename) {
-  if (!fs.existsSync) return false;
-
   var cached = cache[filename];
   if (cached != null) return cached;
-  return cache[filename] = fs.existsSync(filename);
+  return cache[filename] = pathExists.sync(filename);
 }
 
 export default function (loc, opts = {}) {
@@ -34,6 +34,7 @@ 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 +43,7 @@ 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/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/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

@@ -1,122 +1,64 @@
 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;
+  ImportDeclaration: {
+    exit(node, parent, scope, formatter) {
+      formatter.hasLocalImports = true;
 
-    var specifiers = [];
-    var imported = [];
-    formatter.metadata.imports.push({
-      source: node.source.value,
-      imported,
-      specifiers
-    });
+      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);
+      for (var specifier of (this.get("specifiers"): Array)) {
+        var ids = specifier.getBindingIdentifiers();
+        extend(formatter.localImports, ids);
 
-      var local = specifier.node.local.name;
+        var local = specifier.node.local.name;
 
-      if (specifier.isImportDefaultSpecifier()) {
-        imported.push("default");
-        specifiers.push({
-          kind: "named",
-          imported: "default",
-          local
-        });
-      }
+        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.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
-        });
+        if (specifier.isImportNamespaceSpecifier()) {
+          imported.push("*");
+          specifiers.push({
+            kind: "namespace",
+            local
+          });
+        }
       }
     }
   },
@@ -214,18 +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;
 
@@ -239,6 +190,18 @@ export default class DefaultFormatter {
     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;
@@ -260,12 +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/helper-define-property.js

@@ -1,8 +1,18 @@
 (function (obj, key, value) {
-  return Object.defineProperty(obj, key, {
-    value: value,
-    enumerable: true,
-    configurable: true,
-    writable: true
-  });
+  // Shortcircuit the slow defineProperty path when possible.
+  // We are trying to avoid issues where setters defined on the
+  // prototype cause side effects under the fast path of simple
+  // assignment. By checking for existence of the property with
+  // the in operator, we can optimize most of this overhead away.
+  if (key in obj) {
+    Object.defineProperty(obj, key, {
+      value: value,
+      enumerable: true,
+      configurable: true,
+      writable: true
+    });
+  } else {
+    obj[key] = value;
+  }
+  return obj;
 });

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/templates/helper-sliced-to-array.js

@@ -1,7 +1,7 @@
-(function (arr, i) {
-  if (Array.isArray(arr)) {
-    return arr;
-  } else if (Symbol.iterator in Object(arr)) {
+(function () {
+  // Broken out into a separate function to avoid deoptimizations due to the try/catch for the
+  // array iterator case.
+  function sliceIterator(arr, i) {
     // this is an expanded form of `for...of` that properly supports abrupt completions of
     // iterators etc. variable names have been minimised to reduce the size of this massive
     // helper. sometimes spec compliancy is annoying :(
@@ -32,7 +32,15 @@
       }
     }
     return _arr;
-  } else {
-    throw new TypeError("Invalid attempt to destructure non-iterable instance");
   }
-});
+
+  return function (arr, i) {
+    if (Array.isArray(arr)) {
+      return arr;
+    } else if (Symbol.iterator in Object(arr)) {
+      return sliceIterator(arr, i);
+    } else {
+      throw new TypeError("Invalid attempt to destructure non-iterable instance");
+    }
+  };
+})();

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/deprecated.json

@@ -8,5 +8,8 @@
   "utility.inlineExpressions": "minification.constantFolding",
   "utility.deadCodeElimination": "minification.deadCodeElimination",
   "utility.removeConsoleCalls": "minification.removeConsole",
-  "utility.removeDebugger": "minification.removeDebugger"
+  "utility.removeDebugger": "minification.removeDebugger",
+
+  "es6.parameters.rest": "es6.parameters",
+  "es6.parameters.default": "es6.parameters"
 }

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];
@@ -162,6 +162,7 @@ var hoistVarDeclarationsVisitor = {
     } else if (this.isFor()) {
       if (isVar(node.left, node)) {
         node.left = node.left.declarations[0].id;
+        self.pushDeclar(node.left);
       }
     } else if (isVar(node, parent)) {
       return self.pushDeclar(node).map(t.expressionStatement);
@@ -337,6 +338,7 @@ 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: {
@@ -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

@@ -1,18 +1,20 @@
 import * as messages from "../../../messages";
 
-export function Scope(node, parent, scope) {
-  for (var name in scope.bindings) {
-    var binding = scope.bindings[name];
+export var visitor = {
+  Scope(node, parent, scope) {
+    for (var name in scope.bindings) {
+      var binding = scope.bindings[name];
 
-    // not a constant
-    if (binding.kind !== "const" && binding.kind !== "module") continue;
+      // not a constant
+      if (binding.kind !== "const" && binding.kind !== "module") continue;
 
-    for (var violation of (binding.constantViolations: Array)) {
-      throw violation.errorWithNode(messages.get("readOnly", name));
+      for (var violation of (binding.constantViolations: Array)) {
+        throw violation.errorWithNode(messages.get("readOnly", name));
+      }
     }
-  }
-}
+  },
 
-export function VariableDeclaration(node) {
-  if (node.kind === "const") node.kind = "let";
-}
+  VariableDeclaration(node) {
+    if (node.kind === "const") node.kind = "let";
+  }
+};

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

@@ -5,145 +5,209 @@ 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 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 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, ref);
-  }
+    destructuring.init(pattern, key);
 
-  t.ensureBlock(node);
+    this.ensureBlock();
 
-  var block = node.body;
-  block.body = nodes.concat(block.body);
-}
+    var block = node.body;
+    block.body = nodes.concat(block.body);
+  },
 
-export function 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);
-
-  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;
+  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 = scope.generateUidIdentifier("ref");
+      if (t.isAssignmentPattern(pattern)) {
+        var _pattern = pattern;
+        pattern = pattern.left;
+        _pattern.left = ref;
+      } else {
+        node.params[i] = 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);
+
+    node.body.body = nodes.concat(node.body.body);
+  },
+
+  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;
+      }
+    }
+
+    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++) {
@@ -154,62 +218,6 @@ 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])) {

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 = [];

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

@@ -1,118 +0,0 @@
-import callDelegate from "../../helpers/call-delegate";
-import getFunctionArity from "../../helpers/get-function-arity";
-import * as util from  "../../../util";
-import * as t from "../../../types";
-
-var hasDefaults = function (node) {
-  for (var i = 0; i < node.params.length; i++) {
-    if (!t.isIdentifier(node.params[i])) return true;
-  }
-  return false;
-};
-
-var iifeVisitor = {
-  ReferencedIdentifier(node, parent, scope, state) {
-    if (node.name !== "eval") {
-      if (!state.scope.hasOwnBinding(node.name)) return;
-      if (state.scope.bindingIdentifierEquals(node.name, node)) return;
-    }
-
-    state.iife = true;
-    this.stop();
-  }
-};
-
-export function Func/*tion*/(node, parent, scope, file) {
-  if (!hasDefaults(node)) return;
-
-  // ensure it's a block, useful for arrow functions
-  t.ensureBlock(node);
-
-  var state = {
-    iife: false,
-    scope: scope
-  };
-
-  var body = [];
-
-  //
-  var argsIdentifier = t.identifier("arguments");
-  argsIdentifier._shadowedFunctionLiteral = 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 {
-      defNode = util.template("default-parameter-assign", {
-        VARIABLE_NAME: left,
-        DEFAULT_VALUE: right
-      }, true);
-    }
-    defNode._blockHoist = node.params.length - i;
-    body.push(defNode);
-  }
-
-  // check if an index exceeds the functions arity
-  function exceedsLastNonDefault(i) {
-    return i + 1 > lastNonDefaultParam;
-  }
-
-  //
-  var lastNonDefaultParam = getFunctionArity(node);
-
-  //
-  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

@@ -1,148 +0,0 @@
-import * as util from  "../../../util";
-import * as t from "../../../types";
-
-var memberExpressionOptimisationVisitor = {
-  Scope(node, parent, scope, state) {
-    // check if this scope has a local binding that will shadow the rest parameter
-    if (!scope.bindingIdentifierEquals(state.name, state.outerBinding)) {
-      this.skip();
-    }
-  },
-
-  enter(node, parent, scope, state) {
-    var stop = () => {
-      state.canOptimise = false;
-      this.stop();
-    };
-
-    if (this.isArrowFunctionExpression()) return stop();
-
-    // 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();
-    }
-
-    // is this a referenced identifier and is it referencing the rest parameter?
-    if (!this.isReferencedIdentifier({ 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 = this.parentPath.get("property");
-      if (prop.isGenericType("Number")) {
-        state.candidates.push(this);
-        return;
-      }
-    }
-
-    stop();
-  }
-};
-
-function optimizeMemberExpression(parent, offset) {
-  if (offset === 0) return;
-
-  var newExpr;
-  var prop = parent.property;
-
-  if (t.isLiteral(prop)) {
-    prop.value += offset;
-    prop.raw = String(prop.value);
-  } else { // // UnaryExpression, BinaryExpression
-    newExpr = t.binaryExpression("+", prop, t.literal(offset));
-    parent.property = newExpr;
-  }
-}
-
-var hasRest = function (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);
-}

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

@@ -0,0 +1,120 @@
+import callDelegate from "../../../helpers/call-delegate";
+import getFunctionArity from "../../../helpers/get-function-arity";
+import * as util from  "../../../../util";
+import * as t from "../../../../types";
+
+var hasDefaults = function (node) {
+  for (var i = 0; i < node.params.length; i++) {
+    if (!t.isIdentifier(node.params[i])) return true;
+  }
+  return false;
+};
+
+var iifeVisitor = {
+  ReferencedIdentifier(node, parent, scope, state) {
+    if (node.name !== "eval") {
+      if (!state.scope.hasOwnBinding(node.name)) return;
+      if (state.scope.bindingIdentifierEquals(node.name, node)) return;
+    }
+
+    state.iife = true;
+    this.stop();
+  }
+};
+
+export var visitor = {
+  Function(node, parent, scope, file) {
+    if (!hasDefaults(node)) return;
+
+    // ensure it's a block, useful for arrow functions
+    this.ensureBlock();
+
+    var state = {
+      iife: false,
+      scope: scope
+    };
+
+    var body = [];
+
+    //
+    var argsIdentifier = t.identifier("arguments");
+    argsIdentifier._shadowedFunctionLiteral = this;
+
+    // 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 {
+        defNode = util.template("default-parameter-assign", {
+          VARIABLE_NAME: left,
+          DEFAULT_VALUE: right
+        }, true);
+      }
+      defNode._blockHoist = node.params.length - i;
+      body.push(defNode);
+    }
+
+    // check if an index exceeds the functions arity
+    function exceedsLastNonDefault(i) {
+      return i + 1 > lastNonDefaultParam;
+    }
+
+    //
+    var lastNonDefaultParam = getFunctionArity(node);
+
+    //
+    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/index.js

@@ -0,0 +1,10 @@
+import * as visitors from "../../../../traversal/visitors";
+
+import * as def from "./default";
+import * as rest from "./rest";
+
+export var metadata = {
+  group: "builtin-advanced"
+};
+
+export var visitor = visitors.merge([rest.visitor, def.visitor]);

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

@@ -0,0 +1,186 @@
+import * as util from  "../../../../util";
+import * as t from "../../../../types";
+
+var memberExpressionOptimisationVisitor = {
+  Scope(node, parent, scope, state) {
+    // check if this scope has a local binding that will shadow the rest parameter
+    if (!scope.bindingIdentifierEquals(state.name, state.outerBinding)) {
+      this.skip();
+    }
+  },
+
+  Function(node, parent, scope, state) {
+    // skip over functions as whatever `arguments` we reference inside will refer
+    // to the wrong function
+    var oldNoOptimise = state.noOptimise;
+    state.noOptimise = true;
+    this.traverse(memberExpressionOptimisationVisitor, state);
+    state.noOptimise = oldNoOptimise;
+    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 (node.name !== state.name) return;
+
+    if (state.noOptimise) {
+      state.deopted = true;
+    } else {
+      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;
+        }
+      }
+
+      state.references.push(this);
+    }
+  }
+};
+
+function optimiseMemberExpression(parent, offset) {
+  if (offset === 0) return;
+
+  var newExpr;
+  var prop = parent.property;
+
+  if (t.isLiteral(prop)) {
+    prop.value += offset;
+    prop.raw = String(prop.value);
+  } else { // // UnaryExpression, BinaryExpression
+    newExpr = t.binaryExpression("+", prop, t.literal(offset));
+    parent.property = newExpr;
+  }
+}
+
+function hasRest(node) {
+  return t.isRestElement(node.params[node.params.length - 1]);
+}
+
+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 = this;
+
+    // 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

@@ -1,9 +1,7 @@
 import * as t from "../../../types";
 
 function loose(node, body, objId) {
-  for (var i = 0; i < node.properties.length; i++) {
-    var prop = node.properties[i];
-
+  for (var prop of (node.properties: Array)) {
     body.push(t.expressionStatement(
       t.assignmentExpression(
         "=",
@@ -15,31 +13,15 @@ function loose(node, body, objId) {
 }
 
 function spec(node, body, objId, initProps, file) {
-  var props = node.properties;
-
-  // add all non-computed properties and `__proto__` properties to the initializer
-
-  var broken = false;
-
-  for (let i = 0; i < props.length; i++) {
-    let prop = props[i];
-
-    if (prop.computed) {
-      broken = true;
-    }
-
-    if (prop.kind !== "init" || !broken || t.isLiteral(t.toComputedKey(prop, prop.key), { value: "__proto__" })) {
-      initProps.push(prop);
-      props[i] = null;
-    }
-  }
-
   // add a simple assignment for all Symbol member expressions due to symbol polyfill limitations
   // otherwise use Object.defineProperty
 
-  for (let i = 0; i < props.length; i++) {
-    let prop = props[i];
-    if (!prop) continue;
+  for (let prop of (node.properties: Array)) {
+    // this wont work with Object.defineProperty
+    if (t.isLiteral(t.toComputedKey(prop), { value: "__proto__" })) {
+      initProps.push(prop);
+      continue;
+    }
 
     let key = prop.key;
     if (t.isIdentifier(key) && !prop.computed) {
@@ -63,40 +45,62 @@ 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 (let prop of (node.properties: Array)) {
+        hasComputed = t.isProperty(prop, { computed: true, kind: "init" });
+        if (hasComputed) break;
+      }
+
+      if (!hasComputed) return;
+
+      // put all getters/setters into the first object expression as well as all initialisers up
+      // to the first computed property
+
+      var initProps = [];
+      var stopInits = false;
+
+      node.properties = node.properties.filter(function (prop) {
+        if (prop.computed) {
+          stopInits = true;
+        }
+
+        if (prop.kind !== "init" || !stopInits) {
+          initProps.push(prop);
+          return false;
+        } else {
+          return true;
+        }
+      });
+
+      //
+
+      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.hub.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 +43,82 @@ function build(props, scope) {
   return nodes;
 }
 
-export function ArrayExpression(node, parent, scope) {
-  var elements = node.elements;
-  if (!hasSpread(elements)) return;
+export var metadata = {
+  group: "builtin-advanced"
+};
 
-  var nodes = build(elements, scope);
-  var first = nodes.shift();
+export var visitor = {
+  ArrayExpression(node, parent, scope) {
+    var elements = node.elements;
+    if (!hasSpread(elements)) return;
 
-  if (!t.isArrayExpression(first)) {
-    nodes.unshift(first);
-    first = t.arrayExpression([]);
-  }
+    var nodes = build(elements, scope);
+    var first = nodes.shift();
 
-  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];
@@ -209,7 +211,7 @@ class TailCallTransformer {
       var decl = t.variableDeclarator(this.argumentsId);
       if (this.argumentsId) {
         decl.init = t.identifier("arguments");
-        decl.init._shadowedFunctionLiteral = true;
+        decl.init._shadowedFunctionLiteral = this.path;
       }
       topVars.push(decl);
     }

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.isGenericType("String") && !path.isGenericType("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];
+    }
   }
-}
+};