v5.6.2

matchPattern fixes and "this" handling

.eslintrc

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

CHANGELOG.md

@@ -13,6 +13,51 @@ _Note: Gaps between patch versions are faulty/broken releases._
 
 See [CHANGELOG - 6to5](CHANGELOG-6to5.md) for the pre-4.0.0 version changelog.
 
+## 5.6.0
+
+ * **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

@@ -24,11 +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
 

Makefile

@@ -15,7 +15,7 @@ build-core: clean-core
 	node $(BABEL_CMD) src --out-dir lib --copy-files
 
 build-core-test: clean-core
-	node $(BABEL_CMD) src --out-dir lib --copy-files --auxiliary-comment "istanbul ignore next"
+	node $(BABEL_CMD) src --out-dir lib --copy-files --auxiliary-comment-before "istanbul ignore next"
 
 watch-core: clean-core
 	node $(BABEL_CMD) src --out-dir lib --watch --copy-files

package.json

@@ -1,7 +1,7 @@
 {
   "name": "babel-core",
   "description": "A compiler for writing next generation JavaScript",
-  "version": "5.5.7",
+  "version": "5.6.2",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
   "license": "MIT",
@@ -30,20 +30,33 @@
   "dependencies": {
     "acorn-jsx": "^1.0.0",
     "ast-types": "~0.7.0",
-    "bluebird": "^2.9.25",
+    "babel-plugin-constant-folding": "^1.0.1",
+    "babel-plugin-dead-code-elimination": "^1.0.1",
+    "babel-plugin-eval": "^1.0.1",
+    "babel-plugin-inline-environment-variables": "^1.0.1",
+    "babel-plugin-jscript": "^1.0.1",
+    "babel-plugin-member-expression-literals": "^1.0.1",
+    "babel-plugin-property-literals": "^1.0.1",
+    "babel-plugin-proto-to-assign": "^1.0.3",
+    "babel-plugin-react-constant-elements": "^1.0.3",
+    "babel-plugin-react-display-name": "^1.0.3",
+    "babel-plugin-remove-console": "^1.0.1",
+    "babel-plugin-remove-debugger": "^1.0.1",
+    "babel-plugin-runtime": "^1.0.7",
+    "babel-plugin-undeclared-variables-check": "^1.0.2",
+    "babel-plugin-undefined-to-void": "^1.1.6",
     "chalk": "^1.0.0",
     "convert-source-map": "^1.1.0",
     "core-js": "^0.9.0",
     "debug": "^2.1.1",
     "detect-indent": "^3.0.0",
-    "esquery": "^0.4.0",
     "estraverse": "^4.0.0",
     "esutils": "^2.0.0",
     "fs-readdir-recursive": "^0.1.0",
     "globals": "^6.4.0",
     "home-or-tmp": "^1.0.0",
     "is-integer": "^1.0.4",
-    "js-tokens": "1.0.0",
+    "js-tokens": "1.0.1",
     "leven": "^1.0.1",
     "line-numbers": "0.2.0",
     "lodash": "^3.6.0",
@@ -51,7 +64,7 @@
     "output-file-sync": "^1.1.0",
     "path-is-absolute": "^1.0.0",
     "private": "^0.1.6",
-    "regenerator": "0.8.28",
+    "regenerator": "0.8.30",
     "regexpu": "^1.1.2",
     "repeating": "^1.1.2",
     "resolve": "^1.1.6",
@@ -64,7 +77,7 @@
     "trim-right": "^1.0.0"
   },
   "devDependencies": {
-    "babel": "5.3.1",
+    "babel": "5.5.7",
     "browserify": "^9.0.8",
     "chai": "^2.2.0",
     "eslint": "^0.21.2",

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

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

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

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

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

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

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

@@ -6,6 +6,7 @@ var transform        = require("babel-core").transform;
 var kebabCase        = require("lodash/string/kebabCase");
 var options          = require("babel-core").options;
 var util             = require("babel-core").util;
+var uniq             = require("lodash/array/uniq");
 var each             = require("lodash/collection/each");
 var keys             = require("lodash/object/keys");
 var fs               = require("fs");
@@ -84,6 +85,8 @@ var filenames = commander.args.reduce(function (globbed, input) {
   return globbed.concat(files);
 }, []);
 
+filenames = uniq(filenames);
+
 each(filenames, function (filename) {
   if (!fs.existsSync(filename)) {
     errors.push(filename + " doesn't exist");

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

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

packages/babel-cli/package.json

@@ -1,14 +1,14 @@
 {
   "name": "babel",
   "description": "Turn ES6 code into readable vanilla ES5 with source maps",
-  "version": "5.5.6",
+  "version": "5.6.1",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
   "license": "MIT",
   "repository": "babel/babel",
   "preferGlobal": true,
   "dependencies": {
-    "babel-core": "^5.5.6",
+    "babel-core": "^5.6.1",
     "chokidar": "^1.0.0",
     "commander": "^2.6.0",
     "convert-source-map": "^1.1.0",
@@ -23,6 +23,7 @@
   "bin": {
     "babel": "./bin/babel/index.js",
     "babel-node": "./bin/babel-node",
-    "babel-external-helpers": "./bin/babel-external-helpers"
+    "babel-external-helpers": "./bin/babel-external-helpers",
+    "babel-plugin": "./bin/babel-plugin/index.js"
   }
 }

packages/babel-runtime/package.json

@@ -1,7 +1,7 @@
 {
   "name": "babel-runtime",
   "description": "babel selfContained runtime",
-  "version": "5.5.6",
+  "version": "5.6.1",
   "license": "MIT",
   "repository": "babel/babel",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",

packages/build-runtime.js

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

src/acorn/src/expression.js

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

src/acorn/src/lval.js

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

src/acorn/src/state.js

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

src/acorn/src/statement.js

@@ -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/babel/api/node.js

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

src/babel/api/register/node.js

@@ -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/generators/expressions.js

@@ -1,4 +1,3 @@
-import isInteger from "is-integer";
 import isNumber from "lodash/lang/isNumber";
 import * as t from "../../types";
 
@@ -127,6 +126,12 @@ export function ExpressionStatement(node, print) {
   this.semicolon();
 }
 
+export function AssignmentPattern(node, print) {
+  print.plain(node.left);
+  this.push(" = ");
+  print.plain(node.right);
+}
+
 export function AssignmentExpression(node, print) {
   // todo: add cases where the spaces can be dropped when in compact mode
   print.plain(node.left);
@@ -144,12 +149,9 @@ export function BindExpression(node, print) {
 
 export {
   AssignmentExpression as BinaryExpression,
-  AssignmentExpression as LogicalExpression,
-  AssignmentExpression as AssignmentPattern
+  AssignmentExpression as LogicalExpression
 };
 
-var SCIENTIFIC_NOTATION = /e/i;
-
 export function MemberExpression(node, print) {
   var obj = node.object;
   print.plain(obj);
@@ -168,11 +170,6 @@ export function MemberExpression(node, print) {
     print.plain(node.property);
     this.push("]");
   } else {
-    // 5..toFixed(2);
-    if (t.isLiteral(obj) && isInteger(obj.value) && !SCIENTIFIC_NOTATION.test(obj.value.toString())) {
-      this.push(".");
-    }
-
     this.push(".");
     print.plain(node.property);
   }

src/babel/generation/generators/types.js

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

src/babel/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/resolve-rc.js

@@ -1,5 +0,0 @@
-console.trace("I know someone out there is hotlinking straight to this file. This is a " +
-              "PRIVATE API. I hate you, but I wont break your code just because you're a " +
-              "programmer who practices bad habits.");
-
-export { default } from "../transformation/file/options/resolve-rc";

src/babel/transformation/file/index.js

@@ -4,7 +4,6 @@ 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 "./options/resolve-rc";
@@ -14,13 +13,14 @@ 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";
@@ -246,7 +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;
       }
     }
@@ -263,7 +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) {
@@ -273,7 +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);
         }
@@ -281,11 +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;
@@ -335,7 +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);
@@ -586,7 +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/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

@@ -1,78 +1,16 @@
 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: {
     enter(node, parent, scope, formatter) {
       if (node.source) {
         node.source.value = formatter.file.resolveModuleSource(node.source.value);
+        formatter.addScope(this);
       }
     }
   },
@@ -218,18 +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;
 
@@ -243,6 +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;
@@ -264,12 +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-get.js

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

src/babel/transformation/transformer.js

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

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

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

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

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

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

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

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

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

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

@@ -44,47 +44,47 @@ export var metadata = {
   group: "builtin-advanced"
 };
 
-export function VariableDeclaration(node, parent, scope, file) {
-  if (!isLet(node, parent)) return;
+export var visitor = {
+  VariableDeclaration(node, parent, scope, file) {
+    if (!isLet(node, parent)) return;
 
-  if (isLetInitable(node) && file.transformers["es6.spec.blockScoping"].canTransform()) {
-    var nodes = [node];
+    if (isLetInitable(node) && file.transformers["es6.spec.blockScoping"].canTransform()) {
+      var nodes = [node];
 
-    for (var i = 0; i < node.declarations.length; i++) {
-      var decl = node.declarations[i];
-      if (decl.init) {
-        var assign = t.assignmentExpression("=", decl.id, decl.init);
-        assign._ignoreBlockScopingTDZ = true;
-        nodes.push(t.expressionStatement(assign));
+      for (var i = 0; i < node.declarations.length; i++) {
+        var decl = node.declarations[i];
+        if (decl.init) {
+          var assign = t.assignmentExpression("=", decl.id, decl.init);
+          assign._ignoreBlockScopingTDZ = true;
+          nodes.push(t.expressionStatement(assign));
+        }
+        decl.init = file.addHelper("temporal-undefined");
       }
-      decl.init = file.addHelper("temporal-undefined");
+
+      node._blockHoist = 2;
+
+      return nodes;
+    }
+  },
+
+  Loop(node, parent, scope, file) {
+    var init = node.left || node.init;
+    if (isLet(init, node)) {
+      t.ensureBlock(node);
+      node.body._letDeclarators = [init];
     }
 
-    node._blockHoist = 2;
+    var blockScoping = new BlockScoping(this, this.get("body"), parent, scope, file);
+    return blockScoping.run();
+  },
 
-    return nodes;
+  "BlockStatement|Program"(block, parent, scope, file) {
+    if (!t.isLoop(parent)) {
+      var blockScoping = new BlockScoping(null, this, parent, scope, file);
+      blockScoping.run();
+    }
   }
-}
-
-export function Loop(node, parent, scope, file) {
-  var init = node.left || node.init;
-  if (isLet(init, node)) {
-    t.ensureBlock(node);
-    node.body._letDeclarators = [init];
-  }
-
-  var blockScoping = new BlockScoping(this, this.get("body"), parent, scope, file);
-  return blockScoping.run();
-}
-
-export function BlockStatement(block, parent, scope, file) {
-  if (!t.isLoop(parent)) {
-    var blockScoping = new BlockScoping(null, this, parent, scope, file);
-    blockScoping.run();
-  }
-}
-
-export { BlockStatement as Program };
+};
 
 function replace(node, parent, scope, remaps) {
   var remap = remaps[node.name];

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 +5,201 @@ export var metadata = {
   group: "builtin-advanced"
 };
 
-export function ForOfStatement(node, parent, scope, file) {
-  var left = node.left;
+export var visitor = {
+  ForXStatement(node, parent, scope, file) {
+    var left = node.left;
 
-  if (t.isPattern(left)) {
-    // for ({ length: k } in { abc: 3 });
+    if (t.isPattern(left)) {
+      // for ({ length: k } in { abc: 3 });
 
-    var temp = scope.generateUidIdentifier("ref");
+      var temp = scope.generateUidIdentifier("ref");
 
-    node.left = t.variableDeclaration("var", [
-      t.variableDeclarator(temp)
+      node.left = t.variableDeclaration("var", [
+        t.variableDeclarator(temp)
+      ]);
+
+      this.ensureBlock();
+
+      node.body.body.unshift(t.variableDeclaration("var", [
+        t.variableDeclarator(left, temp)
+      ]));
+
+      return;
+    }
+
+    if (!t.isVariableDeclaration(left)) return;
+
+    var pattern = left.declarations[0].id;
+    if (!t.isPattern(pattern)) return;
+
+    var key = scope.generateUidIdentifier("ref");
+    node.left = t.variableDeclaration(left.kind, [
+      t.variableDeclarator(key, null)
     ]);
 
-    t.ensureBlock(node);
-
-    node.body.body.unshift(t.variableDeclaration("var", [
-      t.variableDeclarator(left, temp)
-    ]));
-
-    return;
-  }
-
-  if (!t.isVariableDeclaration(left)) return;
-
-  var pattern = left.declarations[0].id;
-  if (!t.isPattern(pattern)) return;
-
-  var key = scope.generateUidIdentifier("ref");
-  node.left = t.variableDeclaration(left.kind, [
-    t.variableDeclarator(key, null)
-  ]);
-
-  var nodes = [];
-
-  var destructuring = new DestructuringTransformer({
-    kind: left.kind,
-    file: file,
-    scope: scope,
-    nodes: nodes
-  });
-
-  destructuring.init(pattern, key);
-
-  t.ensureBlock(node);
-
-  var block = node.body;
-  block.body = nodes.concat(block.body);
-}
-
-export { ForOfStatement as ForInStatement };
-
-export function Func/*tion*/(node, parent, scope, file) {
-  var 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 = node.params[i] = scope.generateUidIdentifier("ref");
+      t.inherits(ref, pattern);
+
+      var destructuring = new DestructuringTransformer({
+        blockHoist: node.params.length - i,
+        nodes:      nodes,
+        scope:      scope,
+        file:       file,
+        kind:       "let"
+      });
+
+      destructuring.init(pattern, ref);
+    }
+
+    this.ensureBlock();
+
+    var block = node.body;
+    block.body = nodes.concat(block.body);
+  },
+
+  CatchClause(node, parent, scope, file) {
+    var pattern = node.param;
+    if (!t.isPattern(pattern)) return;
+
+    var ref = scope.generateUidIdentifier("ref");
+    node.param = ref;
+
+    var nodes = [];
+
+    var destructuring = new DestructuringTransformer({
+      kind: "let",
+      file: file,
+      scope: scope,
+      nodes: nodes
+    });
+    destructuring.init(pattern, ref);
+
+    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 +210,6 @@ function variableDeclarationHasPattern(node) {
   return false;
 }
 
-export function VariableDeclaration(node, parent, scope, file) {
-  if (t.isForXStatement(parent)) return;
-  if (!variableDeclarationHasPattern(node)) return;
-
-  var nodes = [];
-  var declar;
-
-  for (var i = 0; i < node.declarations.length; i++) {
-    declar = node.declarations[i];
-
-    var patternId = declar.init;
-    var pattern   = declar.id;
-
-    var destructuring = new DestructuringTransformer({
-      nodes: nodes,
-      scope: scope,
-      kind:  node.kind,
-      file:  file
-    });
-
-    if (t.isPattern(pattern)) {
-      destructuring.init(pattern, patternId);
-
-      if (+i !== node.declarations.length - 1) {
-        // we aren't the last declarator so let's just make the
-        // last transformed node inherit from us
-        t.inherits(nodes[nodes.length - 1], declar);
-      }
-    } else {
-      nodes.push(t.inherits(destructuring.buildVariableAssignment(declar.id, declar.init), declar));
-    }
-  }
-
-  if (!t.isProgram(parent) && !t.isBlockStatement(parent)) {
-    // https://github.com/babel/babel/issues/113
-    // for (let [x] = [0]; false;) {}
-
-    declar = null;
-
-    for (i = 0; i < nodes.length; i++) {
-      node = nodes[i];
-      declar = declar || t.variableDeclaration(node.kind, []);
-
-      if (!t.isVariableDeclaration(node) && declar.kind !== node.kind) {
-        throw file.errorWithNode(node, messages.get("invalidParentForThisNode"));
-      }
-
-      declar.declarations = declar.declarations.concat(node.declarations);
-    }
-
-    return declar;
-  }
-
-  return nodes;
-}
-
 function hasRest(pattern) {
   for (var i = 0; i < pattern.elements.length; i++) {
     if (t.isRestElement(pattern.elements[i])) {

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

@@ -22,97 +22,99 @@ var iifeVisitor = {
   }
 };
 
-export function Func/*tion*/(node, parent, scope, file) {
-  if (!hasDefaults(node)) return;
+export var visitor = {
+  Function(node, parent, scope, file) {
+    if (!hasDefaults(node)) return;
 
-  // ensure it's a block, useful for arrow functions
-  t.ensureBlock(node);
+    // ensure it's a block, useful for arrow functions
+    this.ensureBlock();
 
-  var state = {
-    iife: false,
-    scope: scope
-  };
+    var state = {
+      iife: false,
+      scope: scope
+    };
 
-  var body = [];
+    var body = [];
 
-  //
-  var argsIdentifier = t.identifier("arguments");
-  argsIdentifier._shadowedFunctionLiteral = true;
+    //
+    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;
+    // push a default parameter definition
+    function pushDefNode(left, right, i) {
+      var defNode;
+      if (exceedsLastNonDefault(i) || t.isPattern(left) || file.transformers["es6.spec.blockScoping"].canTransform()) {
+        defNode = util.template("default-parameter", {
+          VARIABLE_NAME: left,
+          DEFAULT_VALUE: right,
+          ARGUMENT_KEY:  t.literal(i),
+          ARGUMENTS:     argsIdentifier
+        }, true);
       } else {
-        right.traverse(iifeVisitor, state);
+        defNode = util.template("default-parameter-assign", {
+          VARIABLE_NAME: left,
+          DEFAULT_VALUE: right
+        }, true);
       }
+      defNode._blockHoist = node.params.length - i;
+      body.push(defNode);
     }
 
-    pushDefNode(left.node, right.node, i);
-  }
+    // check if an index exceeds the functions arity
+    function exceedsLastNonDefault(i) {
+      return i + 1 > lastNonDefaultParam;
+    }
 
-  // we need to cut off all trailing default parameters
-  node.params = node.params.slice(0, lastNonDefaultParam);
+    //
+    var lastNonDefaultParam = getFunctionArity(node);
 
-  if (state.iife) {
-    body.push(callDelegate(node, scope));
-    node.body = t.blockStatement(body);
-  } else {
-    node.body.body = body.concat(node.body.body);
+    //
+    var params = this.get("params");
+    for (var i = 0; i < params.length; i++) {
+      var param = params[i];
+
+      if (!param.isAssignmentPattern()) {
+        if (!param.isIdentifier()) {
+          param.traverse(iifeVisitor, state);
+        }
+
+        if (file.transformers["es6.spec.blockScoping"].canTransform() && param.isIdentifier()) {
+          pushDefNode(param.node, t.identifier("undefined"), i);
+        }
+
+        continue;
+      }
+
+      var left  = param.get("left");
+      var right = param.get("right");
+
+      if (exceedsLastNonDefault(i) || left.isPattern()) {
+        var placeholder = scope.generateUidIdentifier("x");
+        placeholder._isDefaultPlaceholder = true;
+        node.params[i] = placeholder;
+      } else {
+        node.params[i] = left.node;
+      }
+
+      if (!state.iife) {
+        if (right.isIdentifier() && scope.hasOwnBinding(right.node.name)) {
+          state.iife = true;
+        } else {
+          right.traverse(iifeVisitor, state);
+        }
+      }
+
+      pushDefNode(left.node, right.node, i);
+    }
+
+    // we need to cut off all trailing default parameters
+    node.params = node.params.slice(0, lastNonDefaultParam);
+
+    if (state.iife) {
+      body.push(callDelegate(node, scope));
+      node.body = t.blockStatement(body);
+    } else {
+      node.body.body = body.concat(node.body.body);
+    }
   }
-}
+};

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

@@ -9,41 +9,54 @@ var memberExpressionOptimisationVisitor = {
     }
   },
 
-  enter(node, parent, scope, state) {
-    var stop = () => {
-      state.canOptimise = false;
-      this.stop();
-    };
-
-    if (this.isArrowFunctionExpression()) return stop();
-
+  Function(node, parent, scope, state) {
     // skip over functions as whatever `arguments` we reference inside will refer
     // to the wrong function
-    if (this.isFunctionDeclaration() || this.isFunctionExpression()) {
-      state.noOptimise = true;
-      this.traverse(memberExpressionOptimisationVisitor, state);
-      state.noOptimise = false;
-      return this.skip();
+    state.noOptimise = true;
+    this.traverse(memberExpressionOptimisationVisitor, state);
+    state.noOptimise = false;
+    this.skip();
+  },
+
+  ReferencedIdentifier(node, parent, scope, state) {
+    // we can't guarantee the purity of arguments
+    if (node.name === "arguments") {
+      state.deopted = true;
     }
 
     // is this a referenced identifier and is it referencing the rest parameter?
-    if (!this.isReferencedIdentifier({ name: state.name })) return;
+    if (node.name !== state.name) return;
 
-    if (!state.noOptimise && t.isMemberExpression(parent) && parent.computed) {
-      // if we know that this member expression is referencing a number then we can safely
-      // optimise it
-      var prop = this.parentPath.get("property");
-      if (prop.isBaseType("number")) {
-        state.candidates.push(this);
-        return;
+    if (!state.noOptimise) {
+      if (this.parentPath.isMemberExpression({ computed: true, object: node })) {
+        // if we know that this member expression is referencing a number then we can safely
+        // optimise it
+        var prop = this.parentPath.get("property");
+        if (prop.isBaseType("number")) {
+          state.candidates.push(this);
+          return;
+        }
+      }
+
+      // optimise single spread args in calls
+      if (this.parentPath.isSpreadElement() && state.offset === 0) {
+        var call = this.parentPath.parentPath;
+        if (call.isCallExpression() && call.node.arguments.length === 1) {
+          state.candidates.push(this);
+          return;
+        }
       }
     }
 
-    stop();
+    if (state.noOptimise) {
+      state.deopted = true;
+    } else {
+      state.references.push(this);
+    }
   }
 };
 
-function optimizeMemberExpression(parent, offset) {
+function optimiseMemberExpression(parent, offset) {
   if (offset === 0) return;
 
   var newExpr;
@@ -58,91 +71,115 @@ function optimizeMemberExpression(parent, offset) {
   }
 }
 
-var hasRest = function (node) {
+function hasRest(node) {
   return t.isRestElement(node.params[node.params.length - 1]);
-};
-
-export function Func/*tion*/(node, parent, scope, file) {
-  if (!hasRest(node)) return;
-
-  var restParam = node.params.pop();
-  var rest = restParam.argument;
-
-  var argsId = t.identifier("arguments");
-
-  // otherwise `arguments` will be remapped in arrow functions
-  argsId._shadowedFunctionLiteral = true;
-
-  // support patterns
-  if (t.isPattern(rest)) {
-    var pattern = rest;
-    rest = scope.generateUidIdentifier("ref");
-
-    var declar = t.variableDeclaration("let", pattern.elements.map(function (elem, index) {
-      var accessExpr = t.memberExpression(rest, t.literal(index), true);
-      return t.variableDeclarator(elem, accessExpr);
-    }));
-    node.body.body.unshift(declar);
-  }
-
-  // check if rest is used in member expressions and optimise for those cases
-
-  var state = {
-    outerBinding: scope.getBindingIdentifier(rest.name),
-    canOptimise:  true,
-    candidates:   [],
-    method:       node,
-    name:         rest.name
-  };
-
-  this.traverse(memberExpressionOptimisationVisitor, state);
-
-  // we only have shorthands and there's no other references
-  if (state.canOptimise && state.candidates.length) {
-    for (var candidate of (state.candidates: Array)) {
-      candidate.replaceWith(argsId);
-      optimizeMemberExpression(candidate.parent, node.params.length);
-    }
-    return;
-  }
-
-  //
-
-  var start = t.literal(node.params.length);
-  var key = scope.generateUidIdentifier("key");
-  var len = scope.generateUidIdentifier("len");
-
-  var arrKey = key;
-  var arrLen = len;
-  if (node.params.length) {
-    // this method has additional params, so we need to subtract
-    // the index of the current argument position from the
-    // position in the array that we want to populate
-    arrKey = t.binaryExpression("-", key, start);
-
-    // we need to work out the size of the array that we're
-    // going to store all the rest parameters
-    //
-    // we need to add a check to avoid constructing the array
-    // with <0 if there are less arguments than params as it'll
-    // cause an error
-    arrLen = t.conditionalExpression(
-      t.binaryExpression(">", len, start),
-      t.binaryExpression("-", len, start),
-      t.literal(0)
-    );
-  }
-
-  var loop = util.template("rest", {
-    ARRAY_TYPE: restParam.typeAnnotation,
-    ARGUMENTS:  argsId,
-    ARRAY_KEY:  arrKey,
-    ARRAY_LEN:  arrLen,
-    START:      start,
-    ARRAY:      rest,
-    KEY:        key,
-    LEN:        len
-  });
-  loop._blockHoist = node.params.length + 1;
-  node.body.body.unshift(loop);
 }
+
+export var visitor = {
+  Function(node, parent, scope) {
+    if (!hasRest(node)) return;
+
+    var restParam = node.params.pop();
+    var rest = restParam.argument;
+
+    var argsId = t.identifier("arguments");
+
+    // otherwise `arguments` will be remapped in arrow functions
+    argsId._shadowedFunctionLiteral = true;
+
+    // support patterns
+    if (t.isPattern(rest)) {
+      var pattern = rest;
+      rest = scope.generateUidIdentifier("ref");
+
+      var declar = t.variableDeclaration("let", pattern.elements.map(function (elem, index) {
+        var accessExpr = t.memberExpression(rest, t.literal(index), true);
+        return t.variableDeclarator(elem, accessExpr);
+      }));
+      node.body.body.unshift(declar);
+    }
+
+    // check and optimise for extremely common cases
+
+    var state = {
+      references: [],
+      offset:     node.params.length,
+
+      argumentsNode: argsId,
+      outerBinding:  scope.getBindingIdentifier(rest.name),
+
+      // candidate member expressions we could optimise if there are no other references
+      candidates: [],
+
+      // local rest binding name
+      name: rest.name,
+
+      // whether any references to the rest parameter were made in a function
+      deopted: false
+    };
+
+    this.traverse(memberExpressionOptimisationVisitor, state);
+
+    if (!state.deopted && !state.references.length) {
+      // we only have shorthands and there are no other references
+      if (state.candidates.length) {
+        for (var candidate of (state.candidates: Array)) {
+          candidate.replaceWith(argsId);
+          if (candidate.parentPath.isMemberExpression()) {
+            optimiseMemberExpression(candidate.parent, state.offset);
+          }
+        }
+      }
+      return;
+    } else {
+      state.references = state.references.concat(state.candidates);
+    }
+
+    //
+
+    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) {
+      // perform allocation at the lowest common denominator of all references
+      this.getEarliestCommonAncestorFrom(state.references).getStatementParent().insertBefore(loop);
+      return;
+    }
+
+    loop._blockHoist = node.params.length + 1;
+    node.body.body.unshift(loop);
+  }
+};

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

@@ -6,6 +6,10 @@ export var metadata = {
   group: "builtin-pre"
 };
 
+function isString(node) {
+  return t.isLiteral(node) && typeof node.value === "string";
+}
+
 function buildBinaryExpression(left, right) {
   var node = t.binaryExpression("+", left, right);
   node._templateLiteralProduced = true;
@@ -21,54 +25,65 @@ function crawl(path) {
   }
 }
 
-export function TaggedTemplateExpression(node, parent, scope, file) {
-  var quasi = node.quasi;
-  var args  = [];
+export var visitor = {
+  TaggedTemplateExpression(node, parent, scope, file) {
+    var quasi = node.quasi;
+    var args  = [];
 
-  var strings = [];
-  var raw     = [];
+    var strings = [];
+    var raw     = [];
 
-  for (var elem of (quasi.quasis: Array)) {
-    strings.push(t.literal(elem.value.cooked));
-    raw.push(t.literal(elem.value.raw));
-  }
-
-  strings = t.arrayExpression(strings);
-  raw = t.arrayExpression(raw);
-
-  var templateName = "tagged-template-literal";
-  if (file.isLoose("es6.templateLiterals")) templateName += "-loose";
-  args.push(t.callExpression(file.addHelper(templateName), [strings, raw]));
-
-  args = args.concat(quasi.expressions);
-
-  return t.callExpression(node.tag, args);
-}
-
-export function TemplateLiteral(node, parent, scope, file) {
-  var nodes = [];
-
-  for (let elem of (node.quasis: Array)) {
-    nodes.push(t.literal(elem.value.cooked));
-
-    var expr = node.expressions.shift();
-    if (expr) nodes.push(expr);
-  }
-
-  if (nodes.length > 1) {
-    // remove redundant '' at the end of the expression
-    var last = nodes[nodes.length - 1];
-    if (t.isLiteral(last, { value: "" })) nodes.pop();
-
-    var root = buildBinaryExpression(nodes.shift(), nodes.shift());
-
-    for (let node of (nodes: Array)) {
-      root = buildBinaryExpression(root, node);
+    for (var elem of (quasi.quasis: Array)) {
+      strings.push(t.literal(elem.value.cooked));
+      raw.push(t.literal(elem.value.raw));
     }
 
-    this.replaceWith(root);
-    //crawl(this);
-  } else {
-    return nodes[0];
+    strings = t.arrayExpression(strings);
+    raw = t.arrayExpression(raw);
+
+    var templateName = "tagged-template-literal";
+    if (file.isLoose("es6.templateLiterals")) templateName += "-loose";
+    args.push(t.callExpression(file.addHelper(templateName), [strings, raw]));
+
+    args = args.concat(quasi.expressions);
+
+    return t.callExpression(node.tag, args);
+  },
+
+  TemplateLiteral(node, parent, scope, file) {
+    var nodes = [];
+
+    for (let elem of (node.quasis: Array)) {
+      nodes.push(t.literal(elem.value.cooked));
+
+      var expr = node.expressions.shift();
+      if (expr) nodes.push(expr);
+    }
+
+    if (nodes.length > 1) {
+      // filter out empty string literals
+      nodes = nodes.filter(n => !t.isLiteral(n, { value: "" }));
+
+      if (nodes.length === 1 && isString(nodes[0])) {
+        return nodes[0];
+      }
+
+      // since `+` is left-to-right associative
+      // ensure the first node is a string if first/second isn't
+      if (!isString(nodes[0]) && !isString(nodes[1])) {
+        nodes.unshift(t.literal(""));
+      }
+
+      var root = buildBinaryExpression(nodes.shift(), nodes.shift());
+
+      for (let node of (nodes: Array)) {
+        root = buildBinaryExpression(root, node);
+      }
+
+      this.replaceWith(root);
+      //crawl(this);
+    } else {
+      return nodes[0];
+    }
   }
-}
+};

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

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

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

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

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

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

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

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

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

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

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

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

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

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

src/babel/transformation/transformers/index.js

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

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

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

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

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

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

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

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

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

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

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

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

@@ -22,12 +22,14 @@ function remap(path, key, create) {
   return id;
 }
 
-export function ThisExpression() {
-  return remap(this, "this", () => t.thisExpression());
-}
+export var visitor = {
+  ThisExpression() {
+    return remap(this, "this", () => t.thisExpression());
+  },
 
-export function ReferencedIdentifier(node) {
-  if (node.name === "arguments" && !node._shadowedFunctionLiteral) {
-    return remap(this, "arguments", () => t.identifier("arguments"));
+  ReferencedIdentifier(node) {
+    if (node.name === "arguments" && !node._shadowedFunctionLiteral) {
+      return remap(this, "arguments", () => t.identifier("arguments"));
+    }
   }
-}
+};

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

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

src/babel/transformation/transformers/minification/constant-folding.js

@@ -1,71 +0,0 @@
-import * as t from "../../../types";
-
-export var metadata = {
-  optional: true,
-  group: "builtin-prepass",
-  experimental: true
-};
-
-export function AssignmentExpression() {
-  var left = this.get("left");
-  if (!left.isIdentifier()) return;
-
-  var binding = this.scope.getBinding(left.node.name);
-  if (!binding || binding.hasDeoptValue) return;
-
-  var evaluated = this.get("right").evaluate();
-  if (evaluated.confident) {
-    binding.setValue(evaluated.value);
-  } else {
-    binding.deoptValue();
-  }
-}
-
-export function IfStatement() {
-  var evaluated = this.get("test").evaluate();
-  if (!evaluated.confident) {
-    // todo: deopt binding values for constant violations inside
-    return this.skip();
-  }
-
-  if (evaluated.value) {
-    this.skipKey("alternate");
-  } else {
-    this.skipKey("consequent");
-  }
-}
-
-export var Scopable = {
-  enter() {
-    var funcScope = this.scope.getFunctionParent();
-
-    for (var name in this.scope.bindings) {
-      var binding = this.scope.bindings[name];
-      var deopt = false;
-
-      for (var path of (binding.constantViolations: Array)) {
-        var funcViolationScope = path.scope.getFunctionParent();
-        if (funcViolationScope !== funcScope) {
-          deopt = true;
-          break;
-        }
-      }
-
-      if (deopt) binding.deoptValue();
-    }
-  },
-
-  exit() {
-    for (var name in this.scope.bindings) {
-      var binding = this.scope.bindings[name];
-      binding.clearValue();
-    }
-  }
-};
-
-export var Expression = {
-  exit() {
-    var res = this.evaluate();
-    if (res.confident) return t.valueToNode(res.value);
-  }
-};

src/babel/transformation/transformers/minification/dead-code-elimination.js

@@ -1,154 +0,0 @@
-import * as t from "../../../types";
-
-function toStatements(node) {
-  if (t.isBlockStatement(node)) {
-    var hasBlockScoped = false;
-
-    for (var i = 0; i < node.body.length; i++) {
-      var bodyNode = node.body[i];
-      if (t.isBlockScoped(bodyNode)) hasBlockScoped = true;
-    }
-
-    if (!hasBlockScoped) {
-      return node.body;
-    }
-  }
-
-  return node;
-}
-
-export var metadata = {
-  optional: true,
-  group: "builtin-pre",
-  experimental: true
-};
-
-export function ReferencedIdentifier(node, parent, scope) {
-  var binding = scope.getBinding(node.name);
-  if (!binding || binding.references > 1 || !binding.constant) return;
-  if (binding.kind === "param" || binding.kind === "module") return;
-
-  var replacement = binding.path.node;
-  if (t.isVariableDeclarator(replacement)) {
-    replacement = replacement.init;
-  }
-  if (!replacement) return;
-
-  // ensure it's a "pure" type
-  if (!scope.isPure(replacement, true)) return;
-
-  if (t.isClass(replacement) || t.isFunction(replacement)) {
-    // don't change this if it's in a different scope, this can be bad
-    // for performance since it may be inside a loop or deeply nested in
-    // hot code
-    if (binding.path.scope.parent !== scope) return;
-  }
-
-  if (this.findParent((path) => path.node === replacement)) {
-    return;
-  }
-
-  t.toExpression(replacement);
-  scope.removeBinding(node.name);
-  binding.path.dangerouslyRemove();
-  return replacement;
-}
-
-export function FunctionDeclaration(node, parent, scope) {
-  var bindingInfo = scope.getBinding(node.id.name);
-  if (bindingInfo && !bindingInfo.referenced) {
-    this.dangerouslyRemove();
-  }
-}
-
-export { FunctionDeclaration as ClassDeclaration };
-
-export function VariableDeclarator(node, parent, scope) {
-  if (!t.isIdentifier(node.id) || !scope.isPure(node.init, true)) return;
-  FunctionDeclaration.apply(this, arguments);
-}
-
-export function ConditionalExpression(node, parent, scope) {
-  var evaluateTest = this.get("test").evaluateTruthy();
-  if (evaluateTest === true) {
-    return node.consequent;
-  } else if (evaluateTest === false) {
-    return node.alternate;
-  }
-}
-
-export function BlockStatement(node) {
-  var paths = this.get("body");
-
-  var purge = false;
-
-  for (var i = 0; i < paths.length; i++) {
-    let path = paths[i];
-
-    if (!purge && path.isCompletionStatement()) {
-      purge = true;
-      continue;
-    }
-
-    if (purge && !path.isFunctionDeclaration()) {
-      path.dangerouslyRemove();
-    }
-  }
-}
-
-export var IfStatement = {
-  exit(node) {
-    var consequent = node.consequent;
-    var alternate  = node.alternate;
-    var test = node.test;
-
-    var evaluateTest = this.get("test").evaluateTruthy();
-
-    // we can check if a test will be truthy 100% and if so then we can inline
-    // the consequent and completely ignore the alternate
-    //
-    //   if (true) { foo; } -> { foo; }
-    //   if ("foo") { foo; } -> { foo; }
-    //
-
-    if (evaluateTest === true) {
-      return toStatements(consequent);
-    }
-
-    // we can check if a test will be falsy 100% and if so we can inline the
-    // alternate if there is one and completely remove the consequent
-    //
-    //   if ("") { bar; } else { foo; } -> { foo; }
-    //   if ("") { bar; } ->
-    //
-
-    if (evaluateTest === false) {
-      if (alternate) {
-        return toStatements(alternate);
-      } else {
-        return this.dangerouslyRemove();
-      }
-    }
-
-    // remove alternate blocks that are empty
-    //
-    //   if (foo) { foo; } else {} -> if (foo) { foo; }
-    //
-
-    if (t.isBlockStatement(alternate) && !alternate.body.length) {
-      alternate = node.alternate = null;
-    }
-
-    // if the consequent block is empty turn alternate blocks into a consequent
-    // and flip the test
-    //
-    //   if (foo) {} else { bar; } -> if (!foo) { bar; }
-    //
-
-    if (t.isBlockStatement(consequent) && !consequent.body.length && t.isBlockStatement(alternate) && alternate.body.length) {
-      node.consequent = node.alternate;
-      node.alternate  = null;
-      node.test       = t.unaryExpression("!", test, true);
-    }
-  }
-};

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

@@ -1,17 +0,0 @@
-import * as t from "../../../types";
-
-export var metadata = {
-  optional: true,
-  group: "builtin-trailing"
-};
-
-export var MemberExpression = {
-  exit(node) {
-    var prop = node.property;
-    if (node.computed && t.isLiteral(prop) && t.isValidIdentifier(prop.value)) {
-      // foo["bar"] => foo.bar
-      node.property = t.identifier(prop.value);
-      node.computed = false;
-    }
-  }
-};

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

@@ -1,17 +0,0 @@
-import * as t from "../../../types";
-
-export var metadata = {
-  optional: true,
-  group: "builtin-trailing"
-};
-
-export var Property = {
-  exit(node) {
-    var key = node.key;
-    if (t.isLiteral(key) && t.isValidIdentifier(key.value)) {
-      // "foo": "bar" -> foo: "bar"
-      node.key = t.identifier(key.value);
-      node.computed = false;
-    }
-  }
-};

src/babel/transformation/transformers/minification/remove-console.js

@@ -1,10 +0,0 @@
-export var metadata = {
-  optional: true,
-  group: "builtin-pre"
-};
-
-export function CallExpression(node, parent) {
-  if (this.get("callee").matchesPattern("console", true)) {
-    this.dangerouslyRemove();
-  }
-}

src/babel/transformation/transformers/minification/remove-debugger.js

@@ -1,8 +0,0 @@
-export var metadata = {
-  optional: true,
-  group: "builtin-pre"
-};
-
-export function DebuggerStatement(node) {
-  this.dangerouslyRemove();
-}

src/babel/transformation/transformers/optimisation/flow.for-of.js

@@ -4,8 +4,10 @@ export var metadata = {
   optional: true
 };
 
-export function ForOfStatement(node, parent, scope, file) {
-  if (this.get("right").isGenericType("Array")) {
-    return _ForOfStatementArray.call(this, node, scope, file);
+export var visitor = {
+  ForOfStatement(node, parent, scope, file) {
+    if (this.get("right").isGenericType("Array")) {
+      return _ForOfStatementArray.call(this, node, scope, file);
+    }
   }
-}
+};

src/babel/transformation/transformers/optimisation/react.constant-elements.js

@@ -1,40 +0,0 @@
-export var metadata = {
-  optional: true
-};
-
-var immutabilityVisitor = {
-  enter(node, parent, scope, state) {
-    var stop = () => {
-      state.isImmutable = false;
-      this.stop();
-    };
-
-    if (this.isJSXClosingElement()) {
-      this.skip();
-      return;
-    }
-
-    if (this.isJSXIdentifier({ name: "ref" }) && this.parentPath.isJSXAttribute({ name: node })) {
-      return stop();
-    }
-
-    if (this.isJSXIdentifier() || this.isIdentifier() || this.isJSXMemberExpression()) {
-      return;
-    }
-
-    if (!this.isImmutable()) stop();
-  }
-};
-
-export function JSXElement(node, parent, scope, file) {
-  if (node._hoisted) return;
-
-  var state = { isImmutable: true };
-  this.traverse(immutabilityVisitor, state);
-
-  if (state.isImmutable) {
-    this.hoist();
-  } else {
-    node._hoisted = true;
-  }
-}

src/babel/transformation/transformers/optimisation/react.inline-elements.js

@@ -18,57 +18,59 @@ function isJSXAttributeOfName(attr, name) {
   return t.isJSXAttribute(attr) && t.isJSXIdentifier(attr.name, { name: name });
 }
 
-export function JSXElement(node, parent, scope, file) {
-  // filter
-  var open = node.openingElement;
-  if (hasRefOrSpread(open.attributes)) return;
+export var visitor = {
+  JSXElement(node, parent, scope, file) {
+    // filter
+    var open = node.openingElement;
+    if (hasRefOrSpread(open.attributes)) return;
 
-  // init
-  var isComponent = true;
-  var props       = t.objectExpression([]);
-  var obj         = t.objectExpression([]);
-  var key         = t.literal(null);
-  var type        = open.name;
+    // init
+    var isComponent = true;
+    var props       = t.objectExpression([]);
+    var obj         = t.objectExpression([]);
+    var key         = t.literal(null);
+    var type        = open.name;
 
-  if (t.isJSXIdentifier(type) && react.isCompatTag(type.name)) {
-    type = t.literal(type.name);
-    isComponent = false;
-  }
-
-  function pushElemProp(key, value) {
-    pushProp(obj.properties, t.identifier(key), value);
-  }
-
-  function pushProp(objProps, key, value) {
-    objProps.push(t.property("init", key, value));
-  }
-
-  // metadata
-  pushElemProp("type", type);
-  pushElemProp("ref", t.literal(null));
-
-  if (node.children.length) {
-    pushProp(props.properties, t.identifier("children"), t.arrayExpression(react.buildChildren(node)));
-  }
-
-  // props
-  for (var i = 0; i < open.attributes.length; i++) {
-    var attr = open.attributes[i];
-    if (isJSXAttributeOfName(attr, "key")) {
-      key = attr.value;
-    } else {
-      pushProp(props.properties, attr.name, attr.value || t.identifier("true"));
+    if (t.isJSXIdentifier(type) && react.isCompatTag(type.name)) {
+      type = t.literal(type.name);
+      isComponent = false;
     }
+
+    function pushElemProp(key, value) {
+      pushProp(obj.properties, t.identifier(key), value);
+    }
+
+    function pushProp(objProps, key, value) {
+      objProps.push(t.property("init", key, value));
+    }
+
+    // metadata
+    pushElemProp("type", type);
+    pushElemProp("ref", t.literal(null));
+
+    if (node.children.length) {
+      pushProp(props.properties, t.identifier("children"), t.arrayExpression(react.buildChildren(node)));
+    }
+
+    // props
+    for (var i = 0; i < open.attributes.length; i++) {
+      var attr = open.attributes[i];
+      if (isJSXAttributeOfName(attr, "key")) {
+        key = attr.value;
+      } else {
+        pushProp(props.properties, attr.name, attr.value || t.identifier("true"));
+      }
+    }
+
+    if (isComponent) {
+      props = t.callExpression(file.addHelper("default-props"), [t.memberExpression(type, t.identifier("defaultProps")), props]);
+    }
+
+    pushElemProp("props", props);
+
+    // key
+    pushElemProp("key", key);
+
+    return obj;
   }
-
-  if (isComponent) {
-    props = t.callExpression(file.addHelper("default-props"), [t.memberExpression(type, t.identifier("defaultProps")), props]);
-  }
-
-  pushElemProp("props", props);
-
-  // key
-  pushElemProp("key", key);
-
-  return obj;
-}
+};

src/babel/transformation/transformers/other/async-to-generator.js

@@ -7,8 +7,10 @@ export var metadata = {
   dependencies: ["es7.asyncFunctions", "es6.classes"]
 };
 
-export function Func/*tion*/(node, parent, scope, file) {
-  if (!node.async || node.generator) return;
+export var visitor = {
+  Function(node, parent, scope, file) {
+    if (!node.async || node.generator) return;
 
-  return remapAsyncToGenerator(this, file.addHelper("async-to-generator"));
-}
+    return remapAsyncToGenerator(this, file.addHelper("async-to-generator"));
+  }
+};

src/babel/transformation/transformers/other/bluebird-coroutines.js

@@ -10,11 +10,13 @@ export var metadata = {
   dependencies: ["es7.asyncFunctions", "es6.classes"]
 };
 
-export function Func/*tion*/(node, parent, scope, file) {
-  if (!node.async || node.generator) return;
+export var visitor = {
+  Function(node, parent, scope, file) {
+    if (!node.async || node.generator) return;
 
-  return remapAsyncToGenerator(
-    this,
-    t.memberExpression(file.addImport("bluebird", null, "absolute"), t.identifier("coroutine"))
-  );
-}
+    return remapAsyncToGenerator(
+      this,
+      t.memberExpression(file.addImport("bluebird", null, "absolute"), t.identifier("coroutine"))
+    );
+  }
+};

src/babel/transformation/transformers/other/eval.js

@@ -1,21 +0,0 @@
-import traverse from "../../../traversal";
-import parse from "../../../helpers/parse";
-
-export var metadata = {
-  group: "builtin-pre",
-  optional: true
-};
-
-export function CallExpression(node) {
-  if (this.get("callee").isIdentifier({ name: "eval" }) && node.arguments.length === 1) {
-    var evaluate = this.get("arguments")[0].evaluate();
-    if (!evaluate.confident) return;
-
-    var code = evaluate.value;
-    if (typeof code !== "string") return;
-
-    var ast = parse(code);
-    traverse.removeProperties(ast);
-    return ast.program;
-  }
-}

src/babel/transformation/transformers/other/flow.js

@@ -4,37 +4,39 @@ export var metadata = {
   group: "builtin-trailing"
 };
 
-export function Flow(node) {
-  this.dangerouslyRemove();
-}
+export var visitor = {
+  Flow() {
+    this.dangerouslyRemove();
+  },
 
-export function ClassProperty(node) {
-  node.typeAnnotation = null;
-  if (!node.value) this.dangerouslyRemove();
-}
+  ClassProperty(node) {
+    node.typeAnnotation = null;
+    if (!node.value) this.dangerouslyRemove();
+  },
 
-export function Class(node) {
-  node.implements = null;
-}
+  Class(node) {
+    node.implements = null;
+  },
 
-export function Func/*tion*/(node) {
-  for (var i = 0; i < node.params.length; i++) {
-    var param = node.params[i];
-    param.optional = false;
+  Function(node) {
+    for (var i = 0; i < node.params.length; i++) {
+      var param = node.params[i];
+      param.optional = false;
+    }
+  },
+
+  TypeCastExpression(node) {
+    do {
+      node = node.expression;
+    } while(t.isTypeCastExpression(node));
+    return node;
+  },
+
+  ImportDeclaration(node) {
+    if (node.isType) this.dangerouslyRemove();
+  },
+
+  ExportDeclaration() {
+    if (this.get("declaration").isTypeAlias()) this.dangerouslyRemove();
   }
-}
-
-export function TypeCastExpression(node) {
-  do {
-    node = node.expression;
-  } while(t.isTypeCastExpression(node));
-  return node;
-}
-
-export function ImportDeclaration(node) {
-  if (node.isType) this.dangerouslyRemove();
-}
-
-export function ExportDeclaration(node) {
-  if (this.get("declaration").isTypeAlias()) this.dangerouslyRemove();
-}
+};

src/babel/transformation/transformers/other/jscript.js

@@ -1,21 +0,0 @@
-import * as t from "../../../types";
-
-export var metadata = {
-  group: "builtin-trailing",
-  optional: true
-};
-
-export var FunctionExpression = {
-  exit(node) {
-    if (!node.id) return;
-    node._ignoreUserWhitespace = true;
-
-    return t.callExpression(
-      t.functionExpression(null, [], t.blockStatement([
-        t.toStatement(node),
-        t.returnStatement(node.id)
-      ])),
-      []
-    );
-  }
-};

src/babel/transformation/transformers/other/react-compat.js

@@ -10,7 +10,7 @@ export var metadata = {
   group: "builtin-advanced"
 };
 
-require("../../helpers/build-react-transformer")(exports, {
+export var visitor = require("../../helpers/build-react-transformer")({
   pre(state) {
     state.callee = state.tagExpr;
   },