v5.6.19

add some useful links

.babelrc

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

.eslintrc

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

.gitignore

@@ -15,3 +15,4 @@ test/core/tmp
 /packages/babel-runtime/helpers/*.js
 /packages/babel-runtime/regenerator/*.js
 /lib
+_babel.github.io

.npmignore

@@ -13,3 +13,4 @@
 /vendor
 /packages
 /src
+_babel.github.io

.travis.yml

@@ -1,19 +1,35 @@
-#sudo: false
 language: node_js
 cache:
   directories:
-    - node_modules
+  - node_modules
 node_js:
-  - "0.12"
-  - "iojs"
+- "0.10"
+- "0.12"
+- iojs
 
-before_script: "npm install -g codeclimate-test-reporter"
-script: "make test-travis"
+before_script: ./tools/setup-git.sh
+script: make test-travis
+after_success: ./tools/merge-development-with-master.sh
 
 notifications:
-  webhooks:
-    urls:
-      - https://webhooks.gitter.im/e/acf1870e9d223c65e8d5
-    on_success: always
-    on_failure: always
-    on_start: false
+  slack: babeljs:5Wy4QX13KVkGy9CnU0rmvgeK
+
+before_deploy:
+- make prepublish
+
+deploy:
+  provider: npm
+  email: sebmck@gmail.com
+  skip_cleanup: true
+  api_key:
+    secure: Q/pZStwherdYPCqCa0aUuiEktLcx6ccBxieyH8j9IXdDgty0ydmnajZfUnlZuCjN13XI9esM44nSJFTWZvntTryDQAQm37c63VXhAEnw/qrAINI06yt0gLBTT69/fKvIAkH8l48nmW32ZS2dse3rHRPZF1CwyQLC/pdMip8I4sM=
+  on:
+    branch: master
+    tags: true
+    repo: babel/babel
+
+after_deploy:
+- make publish-cli
+- make publish-runtime
+- make build-website
+- make comment-issues

CHANGELOG.md

@@ -9,10 +9,178 @@
 > - [Internal]
 > - [Polish]
 
-_Note: Gaps between patch versions are faulty/broken releases._
+_Note: Gaps between patch versions are faulty, broken or test releases._
 
 See [CHANGELOG - 6to5](CHANGELOG-6to5.md) for the pre-4.0.0 version changelog.
 
+## 5.6.19
+
+ * Removed do expressions.
+
+## 5.6.17
+
+ * **Bug Fix**
+  * Fix `CodeGenerator.findCommonStringDelimiter` causing a stack overflow.
+
+## 5.6.16
+
+ * **Internal**
+  * Fix `recast` version to avoid pulling in a newer version.
+ * **New Feature**
+  * Add support for functions in `util.shouldIgnore`.
+ * **Polish**
+  * Strip flow directives in flow transformer.
+  * Add a check for out of bounds default parameters, drastically improving performance and removes engine deoptimisations.
+  * Various performance optimisations by [@samccone](https://github.com/samccone) 💅✨
+  * Delay `this` assignment when referencing this inside an arrow function pre-bare super in derived class constructors.
+  * Split up class body pushing if the constructor is in the wrong order.
+ * **Bug Fix**
+  * Fix hoisting of `ForInStatement` `init` variables in `system` module formatter.
+  * `PathHoister`: Don't hoist to the same function as their original paths function parent.
+  * `PathHoister`: Push each violation paths ancestry to the breakOnScopePaths collection to avoid constant hoisting to nested paths.fix tail call recursion on functions with less arguments than parameters.
+  * Disallow `super.*` before `super()` in derived class constructors.
+  * Properly regenerate scope for replaced nodes. Thanks [@loganfsmyth](https://github.com/loganfsmyth)!
+  * Move up template literal simplification logic to avoid breaking on single elements.
+
+## 5.6.13-5.6.15
+
+ * Setting up automatic Travis releases.
+
+## 5.6.12
+
+ * **Bug Fix**
+  * Fix finding parent for top-level shadowed functions.
+
+## 5.6.11
+
+ ** **Internal**
+  * Merge `es6.parameters.rest` and `es6.parameters.default` transformers. See commit [c0fd4c1f9e0b18231f585c4fa793e4cb0e01aed1](https://github.com/babel/babel/commit/c0fd4c1f9e0b18231f585c4fa793e4cb0e01aed1) for more info.
+
+## 5.6.10
+
+ * **Bug Fix**
+  * Fix faulty internal require check.
+ * **Polish**
+  * Add support for trailing commas in arrow function parameter lists.
+
+## 5.6.8
+
+ * **Bug Fix**
+  * Fix binary expressions colliding with unary expression operators in compact mode.
+  * Fix node properties being set to `null` when using computed properties.
+
+## 5.6.7
+
+ * **Bug Fix**
+  * Fix hoisting of `ForXStatement` `left` `var`s when inserting a block scoping IIFE.
+ * **Polish**
+  * Combine all leading computed property initialisers into the root object in loose mode.
+ * **Internal**
+  * Deprecate returning of replacement strings from visitor methods.
+
+## 5.6.6
+
+ * **Bug Fix**
+  * Fix weird parser bug where `void` type annotations were being parsed as keywords causing the tokeniser to lose track of context.
+
+## 5.6.5
+
+ * **Bug Fix**
+  * Fix nested functions causing rest parameter optimisation to not properly detect when it should deopt on a reference.
+ * **Internal**
+  * Update Regenerator `0.8.31`.
+
+## 5.6.4
+
+ * **Internal**
+  * Add `ParenthesizedExpression` node type.
+
+## 5.6.3
+
+ * **Bug Fix**
+  * Fix rest parameter array allocation loop being incorrectly aliased.
+
+## 5.6.2
+
+ * **Bug Fix**
+  * Fix method key literals not turning into computed member expression in loose mode.
+  * Elect rest parameters in spread element position as candidates instead of replacing them in place.
+
+## 5.6.0
+
+ * **Bug Fix**
+  * Fix istanbul interop for register hook when registering for non-existence extension.
+  * Fix super class constructor call differing for no constructor in derived classes.
+  * Disable module import receiver when in loose mode.
+  * Fix duplicate filenames when using `babel` CLI when passing multiple matching patterns.
+  * Register labels as bindings to fix undeclared variable checks.
+ * **Polish**
+  * Remove unnecessary string binary expressions when transforming template literals.
+  * Support module live bindings in arbitary positions not in Program statement position.
+  * Throw error when attemping to replace a `Program` root node with another node not of type `Program`.
+  * Optimise rest parameters in spread element position and allocate rest array at the earliest common ancestor of all references.
+  * Generate original number representation when value was not changed.
+  * Check for invalid binding identifiers when generating inferred method names.
+  * Don't terminate CLI when watching files fail compilation on init.
+ * **New Feature**
+  * Add new plugin API.
+ * **Internal**
+  * Split react displayName addition into a plugin.
+  * Add check for `JSXMemberExpression` to `t.isReferenced`.
+  * Move `validation.undeclaredVariableCheck` transformer up.
+  * Start great core-to-plugin exodus.
+  * Add `BindingIdentifier` virtual type.
+  * Hidden class optimisations.
+  * Array allocation optimisations.
+  * Update `regenerator`.
+  * Update `js-tokens`.
+  * Sync with upstream Acorn.
+
+## 5.5.8
+
+ * **Internal**
+  * Remove extremely unprofessional and harsh error message for those hotlinking to `resolve-rc`.
+
+## 5.5.7
+
+ * **Bug Fix**
+  * Push newline after decorators when doing code gen.
+  * Rewriting error handling to normalise options before merging them.
+  * Remove duplicate keys in `alias-keys.json` causing errors in strict mode.
+  * Fix `$ babel --help` not showing optional transformers as such.
+ * **New Feature**
+  * Add `auxiliaryCommentBefore` and `auxiliaryCommentAfter` options.
+
+## 5.5.6
+
+ * **Bug Fix**
+  * Fix `let` binding collision in loop head not properly replacing `AssignmentExpression`s.
+
+## 5.5.5
+
+ * **Bug Fix**
+  * Fix `file.opts` not being set before `file.log.deprecate` was called causing a `ReferenceError` as it was checking for a property on it.
+
+## 5.5.4
+
+ * **Bug Fix**
+  * Add back missing `shouldIgnore` check.
+  * Log message on deprecated options rather than throw an error.
+  * Fix name of `auxiliaryComment` option when attempting Istanbul interop in `babel/register`.
+
+## 5.5.3
+
+ * **Bug Fix**
+  * Fix weird state bug when traversing overa  `node` `ClassProperty` instead of `path` in the `es6.classes` transformer.
+
+## 5.5.2
+
+ * **Bug Fix**
+  * Fix `NodePath#isPure` on `Property` nodes.
+  * Use cwd instead of entry file directory when working out relative directory for `babel/register`.
+ * **Internal**
+  * Add scary warning for those few who choose to use the WIP experimental transformers.
+
 ## 5.5.1
 
  * **Bug Fix**

CONTRIBUTING.md

@@ -12,6 +12,8 @@
    <strong><a href="#dependencies">Dependencies</a></strong>
    |
    <strong><a href="#code-standards">Code Standards</a></strong>
+   |
+   <strong><a href="#internals">Internals</a></strong>
 </p>
 
 ----
@@ -22,11 +24,10 @@ Contributions are always welcome, no matter how large or small. Before
 contributing, please read the
 [code of conduct](https://github.com/babel/babel/blob/master/CODE_OF_CONDUCT.md).
 
-
 ## Developing
 
->Note: Babel moves fast. Only the latest release is guaranteed to build correctly.
->Older releases are not officially supported. If you attempt to build them, do that at your own risk.
+> Note: Babel moves fast. Only the latest release is guaranteed to build correctly.
+> Older releases are not officially supported. If you attempt to build them, do that at your own risk.
 
 #### Setup
 
@@ -112,8 +113,6 @@ your [`$PATH`](http://unix.stackexchange.com/questions/26047/how-to-correctly-ad
 
 + [js-tokens](http://ghub.io/js-tokens) This is used to get tokens for syntax error highlighting.
 
-+ [leven](http://ghub.io/leven) A levenstein algorithm to determine how close a word is to another. This is used to offer suggestions when using the utility.undeclaredVariableCheck transformer.
-
 + [line-numbers](http://ghub.io/line-numbers) Used to produce the code frames in syntax errors.
 
 + [lodash](http://ghub.io/lodash) Used for various utilities.
@@ -144,8 +143,11 @@ your [`$PATH`](http://unix.stackexchange.com/questions/26047/how-to-correctly-ad
 
 + [trim-right](http://ghub.io/trim-right) Trims the rightside whitespace.
 
-+ [user-home](http://ghub.io/user-home) Gets the users home directory. This is used to resolve the babel-node/babel/register cache.
++ [path-exists](https://www.npmjs.com/package/path-exists) Checks if a path exists. (replaces the deprecated `fs.exists` methods)
 
++ [home-or-tmp](https://github.com/sindresorhus/home-or-tmp) Gets the user home directory with fallback to the system temporary directory. This is used to resolve the babel-node/babel/register cache.
+
++ [resolve](https://www.npmjs.com/package/resolve) Implements the [`require.resolve()` algorithm](http://nodejs.org/docs/v0.12.0/api/all.html#all_require_resolve) such that we can `require.resolve()` on behalf of a file asynchronously and synchronously.
 
 #### Code Standards
 
@@ -173,3 +175,6 @@ your [`$PATH`](http://unix.stackexchange.com/questions/26047/how-to-correctly-ad
  * **Declaration**
    * No unused variables
    * No pollution of global variables and prototypes
+
+#### Internals
+Please see [`/doc`](/doc) for internals documentation relevant to developing babel.

Makefile

@@ -5,16 +5,17 @@ UGLIFY_CMD = node_modules/uglify-js/bin/uglifyjs
 #UGLIFY_CMD = node_modules/uglify-js/bin/uglifyjs --mangle sort
 MOCHA_CMD = node_modules/mocha/bin/_mocha
 BABEL_CMD = node_modules/babel/bin/babel
+BROWSERIFY_IGNORE = -i esprima-fb
 
 export NODE_ENV = test
 
-.PHONY: clean test test-cov test-clean test-travis test-simple test-all test-browser test-parser publish build bootstrap publish-core publish-runtime build-core watch-core build-core-test clean-core
+.PHONY: clean test test-cov test-clean test-travis test-simple test-all test-browser test-parser publish build bootstrap publish-core publish-runtime build-website build-core watch-core build-core-test clean-core prepublish
 
 build-core: clean-core
 	node $(BABEL_CMD) src --out-dir lib --copy-files
 
 build-core-test: clean-core
-	node $(BABEL_CMD) src --out-dir lib --copy-files --auxiliary-comment "istanbul ignore next"
+	node $(BABEL_CMD) src --out-dir lib --copy-files --auxiliary-comment-before "istanbul ignore next"
 
 watch-core: clean-core
 	node $(BABEL_CMD) src --out-dir lib --watch --copy-files
@@ -23,7 +24,7 @@ clean-core:
 	rm -rf lib
 
 lint:
-	eslint src/babel
+	eslint src/babel packages/babel-cli/bin
 
 build:
 	mkdir -p dist
@@ -34,8 +35,10 @@ build:
 	node $(BROWSERIFY_CMD) -e lib/babel/polyfill.js >dist/polyfill.js
 	node $(UGLIFY_CMD) dist/polyfill.js >dist/polyfill.min.js
 
-	node $(BROWSERIFY_CMD) lib/babel/api/browser.js -s babel >dist/babel.js
-	node $(UGLIFY_CMD) dist/babel.js >dist/babel.min.js
+	node $(BROWSERIFY_CMD) lib/babel/api/browser.js -s babel $(BROWSERIFY_IGNORE) >dist/browser.js
+	node $(UGLIFY_CMD) dist/browser.js >dist/browser.min.js
+
+	node $(BROWSERIFY_CMD) lib/babel/api/node.js --node $(BROWSERIFY_IGNORE) >dist/node.js
 
 	node packages/babel-cli/bin/babel-external-helpers >dist/external-helpers.js
 	node $(UGLIFY_CMD) dist/external-helpers.js >dist/external-helpers.min.js
@@ -78,34 +81,20 @@ test-browser:
 
 publish: lint
 	git pull --rebase
-
 	make test
-
 	read -p "Version: " version; \
 	npm version $$version --message "v%s"
-
-	make build
-
-	cp dist/babel.js browser.js
-	cp dist/babel.min.js browser.min.js
-
-	cp dist/polyfill.js browser-polyfill.js
-	cp dist/polyfill.min.js browser-polyfill.min.js
-
-	cp dist/external-helpers.js external-helpers.js
-	cp dist/external-helpers.min.js external-helpers.min.js
-
-	node tools/cache-templates
-	test -f templates.json
-
-	npm publish
-
 	git push --follow-tags
 
-	make publish-cli
-	make publish-runtime
-
-	rm -rf templates.json browser.js browser.min.js browser-polyfill.js browser-polyfill.min.js external-helpers.js external-helpers.min.js
+prepublish: build
+	cp dist/browser.js browser.js
+	cp dist/browser.min.js browser.min.js
+	cp dist/polyfill.js browser-polyfill.js
+	cp dist/polyfill.min.js browser-polyfill.min.js
+	cp dist/external-helpers.js external-helpers.js
+	cp dist/external-helpers.min.js external-helpers.min.js
+	node tools/cache-templates
+	test -f templates.json
 
 publish-runtime:
 	cd packages; \
@@ -114,10 +103,13 @@ publish-runtime:
 	npm publish
 
 publish-cli:
-	cd packages; \
-	node build-cli.js; \
-	cd babel-cli; \
-	npm publish
+	@./tools/publish-cli.sh
+
+build-website:
+	@./tools/build-website.sh
+
+comment-issues:
+	@./tools/comment-issues.sh
 
 bootstrap:
 	npm list --global --depth 1 babel >/dev/null 2>&1 && npm uninstall -g babel || true

README.md

@@ -1,19 +1,28 @@
 <p align="center">
   <a href="https://babeljs.io/">
-    <img alt="babel" src="https://raw.githubusercontent.com/babel/logo/master/logo.png" width="546">
+    <img alt="babel" src="https://raw.githubusercontent.com/babel/logo/master/babel.png" width="546">
   </a>
 </p>
 
 <p align="center">
-  <strong>Babel</strong> is a compiler for writing next generation JavaScript.
+  The compiler for writing next generation JavaScript.
 </p>
 
 <p align="center">
-  For questions and support please visit the <a href="https://gitter.im/babel/babel">gitter room</a> or <a href="http://stackoverflow.com/questions/tagged/babeljs">StackOverflow</a>. The Babel issue tracker is <strong>exclusively</strong> for bug reports and feature requests.
+  <a href="https://travis-ci.org/babel/babel"><img alt="Build Status" src="https://img.shields.io/travis/babel/babel.svg?style=flat"></a>
+  <a href="http://badge.fury.io/js/babel-core"><img alt="npm version" src="https://badge.fury.io/js/babel-core.svg"></a>
+  <a href="https://npmjs.org/package/babel-core"><img alt="Downloads" src="http://img.shields.io/npm/dm/babel-core.svg"></a>
 </p>
 
 <p align="center">
-  Issues without instructions to reproduce <strong>will be immediately closed<strong>.
+  <a href="http://issuestats.com/github/babel/babel"><img alt="Issue Stats" src="http://issuestats.com/github/babel/babel/badge/pr?style=flat"></a>
+  <a href="http://issuestats.com/github/babel/babel"><img alt="Issue Stats" src="http://issuestats.com/github/babel/babel/badge/issue?style=flat"></a>
+</p>
+
+----
+
+<p align="center">
+  For questions and support please visit the <a href="https://babel-slack.herokuapp.com">Slack community</a> or <a href="http://stackoverflow.com/questions/tagged/babeljs">StackOverflow</a>. The Babel issue tracker is <strong>exclusively</strong> for bug reports and feature requests.
 </p>
 
 <p align="center">

doc/index.md

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

doc/node-props.md

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

index.js

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

package.json

@@ -1,27 +1,26 @@
 {
   "name": "babel-core",
   "description": "A compiler for writing next generation JavaScript",
-  "version": "5.5.1",
+  "version": "5.6.19",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
   "license": "MIT",
   "repository": "babel/babel",
-  "main": "lib/babel/api/node.js",
   "browser": {
     "./lib/babel/api/register/node.js": "./lib/babel/api/register/browser.js"
   },
   "keywords": [
-    "harmony",
+    "6to5",
+    "babel",
     "classes",
-    "modules",
-    "let",
     "const",
-    "var",
     "es6",
+    "harmony",
+    "let",
+    "modules",
     "transpile",
     "transpiler",
-    "6to5",
-    "babel"
+    "var"
   ],
   "scripts": {
     "bench": "make bench",
@@ -29,29 +28,41 @@
   },
   "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": "^1.0.2",
+    "babel-plugin-eval": "^1.0.1",
+    "babel-plugin-inline-environment-variables": "^1.0.1",
+    "babel-plugin-jscript": "^1.0.1",
+    "babel-plugin-member-expression-literals": "^1.0.1",
+    "babel-plugin-property-literals": "^1.0.1",
+    "babel-plugin-proto-to-assign": "^1.0.3",
+    "babel-plugin-react-constant-elements": "^1.0.3",
+    "babel-plugin-react-display-name": "^1.0.3",
+    "babel-plugin-remove-console": "^1.0.1",
+    "babel-plugin-remove-debugger": "^1.0.1",
+    "babel-plugin-runtime": "^1.0.7",
+    "babel-plugin-undeclared-variables-check": "^1.0.2",
+    "babel-plugin-undefined-to-void": "^1.1.6",
     "chalk": "^1.0.0",
     "convert-source-map": "^1.1.0",
     "core-js": "^0.9.0",
     "debug": "^2.1.1",
     "detect-indent": "^3.0.0",
-    "esquery": "^0.4.0",
     "estraverse": "^4.0.0",
     "esutils": "^2.0.0",
     "fs-readdir-recursive": "^0.1.0",
     "globals": "^6.4.0",
     "home-or-tmp": "^1.0.0",
     "is-integer": "^1.0.4",
-    "js-tokens": "1.0.0",
-    "leven": "^1.0.1",
+    "js-tokens": "1.0.1",
     "line-numbers": "0.2.0",
     "lodash": "^3.6.0",
     "minimatch": "^2.0.3",
     "output-file-sync": "^1.1.0",
+    "path-exists": "^1.0.0",
     "path-is-absolute": "^1.0.0",
     "private": "^0.1.6",
-    "regenerator": "^0.8.28",
+    "regenerator": "0.8.34",
     "regexpu": "^1.1.2",
     "repeating": "^1.1.2",
     "resolve": "^1.1.6",
@@ -64,11 +75,11 @@
     "trim-right": "^1.0.0"
   },
   "devDependencies": {
-    "babel": "5.3.1",
+    "babel": "5.6.10",
+    "babel-eslint": "^3.1.19",
     "browserify": "^9.0.8",
     "chai": "^2.2.0",
     "eslint": "^0.21.2",
-    "babel-eslint": "^3.1.9",
     "esvalid": "^1.1.0",
     "istanbul": "^0.3.5",
     "matcha": "^0.6.0",

packages/babel-cli/bin/_babel-node

@@ -18,9 +18,9 @@ program.option("-p, --print [code]", "Evaluate script and print result");
 program.option("-i, --ignore [regex]", "Ignore all files that match this regex when using the require hook");
 program.option("-x, --extensions [extensions]", "List of extensions to hook into [.es6,.js,.es,.jsx]");
 program.option("-r, --stage [stage]", "Enable support for specific ECMAScript stages");
-program.option("-w, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util.list);
-program.option("-b, --blacklist [blacklist]", "Blacklist of transformers to NOT use", util.list);
-program.option("-o, --optional [optional]", "List of optional transformers to enable", util.list);
+program.option("-w, --whitelist [whitelist]", "Whitelist of transformers separated by comma to ONLY use", util.list);
+program.option("-b, --blacklist [blacklist]", "Blacklist of transformers separated by comma to NOT use", util.list);
+program.option("-o, --optional [optional]", "List of optional transformers separated by comma to enable", util.list);
 
 var pkg = require("../package.json");
 program.version(pkg.version);
@@ -41,6 +41,7 @@ babel.register({
 //
 
 var _eval = function (code, filename) {
+  code = code.trim();
   if (!code) return undefined;
 
   code = babel.transform(code, {

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

@@ -0,0 +1,141 @@
+#!/usr/bin/env node
+
+var pathExists = require("path-exists");
+var readline   = require("readline");
+var child      = require("child_process");
+var path       = require("path");
+var fs         = require("fs");
+
+function spawn(cmd, args, callback) {
+  console.log(">", cmd, args);
+
+  var spawn = child.spawn(cmd, args, { stdio: "inherit" });
+
+  spawn.on("exit", function (code) {
+    if (code === 0) {
+      if (callback) callback();
+    } else {
+      console.log("Killing...");
+      process.exit(1);
+    }
+  });
+}
+
+function spawnMultiple(cmds) {
+  function next() {
+    var cmd = cmds.shift();
+    if (cmd) {
+      spawn(cmd.command, cmd.args, next);
+    } else {
+      process.exit();
+    }
+  }
+
+  next();
+}
+
+function template(name, data) {
+  var source = fs.readFileSync(path.join(__dirname, "templates", name), "utf8");
+  source = source.replace(/[A-Z_]+/g, function (key) {
+    return data[key] === undefined ? key : data[key];
+  });
+  return source;
+}
+
+function write(filename, content) {
+  console.log(filename);
+  fs.writeFileSync(filename, content);
+}
+
+var rl = readline.createInterface({
+  input: process.stdin,
+  output: process.stdout
+});
+
+var BABEL_PLUGIN_PREFIX = "babel-plugin-";
+
+var cmds = {
+  init: function () {
+    var name = path.basename(process.cwd());
+
+    if (name.indexOf(BABEL_PLUGIN_PREFIX) === 0) {
+      name = name.slice(BABEL_PLUGIN_PREFIX.length);
+    }
+
+    rl.question("Description (optional): ", function (description) {
+      rl.question("GitHub Repository (eg. sebmck/babel-plugin-foobar) (optional): ", function (repo) {
+        rl.close();
+
+        var templateData = {
+          DESCRIPTION: description,
+          FULL_NAME: BABEL_PLUGIN_PREFIX + name,
+          NAME: name
+        };
+
+        write("package.json", JSON.stringify({
+          name: templateData.FULL_NAME,
+          version: "1.0.0",
+          description: templateData.DESCRIPTION,
+          repository: repo || undefined,
+          license: "MIT",
+          main: "lib/index.js",
+
+          devDependencies: {
+            babel: "^5.6.0"
+          },
+
+          scripts: {
+            build: "babel-plugin build",
+            push:  "babel-plugin publish",
+            test:  "babel-plugin test"
+          },
+
+          keywords: ["babel-plugin"]
+        }, null, "  ") + "\n");
+
+        write(".npmignore", "node_modules\n*.log\nsrc\n");
+
+        write(".gitignore", "node_modules\n*.log\nlib\n");
+
+        write("README.md", template("README.md", templateData));
+
+        if (!pathExists.sync("src")) {
+          fs.mkdirSync("src");
+          write("src/index.js", template("index.js", templateData));
+        }
+      });
+    });
+  },
+
+  build: function () {
+    spawn("babel", ["src", "--out-dir", "lib", "--copy-files"]);
+  },
+
+  publish: function () {
+    var pkg = require(process.cwd() + "/package.json");
+    console.log("Current verison:", pkg.version);
+
+    rl.question("New version (enter nothing for patch): ", function (newVersion) {
+      rl.close();
+
+      newVersion = newVersion || "patch";
+
+      spawnMultiple([
+        { command: "git", args: ["pull"] },
+        { command: "git", args: ["push"] },
+        { command: "babel-plugin", args: ["build"] },
+        { command: "npm", args: ["version", newVersion] },
+        { command: "npm", args: ["publish"] },
+        { command: "git", args: ["push", "--follow-tags"] }
+      ]);
+    });
+  }
+};
+
+var cmd = cmds[process.argv[2]];
+if (cmd) {
+  cmd();
+} else {
+  console.error("Unknown command:", cmd);
+  process.exit(1);
+}

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

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

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

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

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

@@ -1,4 +1,5 @@
 var outputFileSync = require("output-file-sync");
+var pathExists     = require("path-exists");
 var chokidar       = require("chokidar");
 var slash          = require("slash");
 var path           = require("path");
@@ -6,7 +7,7 @@ var util           = require("./util");
 var fs             = require("fs");
 var _              = require("lodash");
 
-module.exports = function (commander, filenames, opts) {
+module.exports = function (commander, filenames) {
   var write = function (src, relative) {
     // remove extension and then append back on .js
     relative = relative.replace(/\.(\w*?)$/, "") + ".js";
@@ -27,7 +28,7 @@ module.exports = function (commander, filenames, opts) {
 
     outputFileSync(dest, data.code);
 
-    console.log(src + " -> " + dest);
+    util.log(src + " -> " + dest);
   };
 
   var handleFile = function (src, filename) {
@@ -41,7 +42,7 @@ module.exports = function (commander, filenames, opts) {
   };
 
   var handle = function (filename) {
-    if (!fs.existsSync(filename)) return;
+    if (!pathExists.sync(filename)) return;
 
     var stat = fs.statSync(filename);
 

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

@@ -1,4 +1,5 @@
 var convertSourceMap = require("convert-source-map");
+var pathExists       = require("path-exists");
 var sourceMap        = require("source-map");
 var chokidar         = require("chokidar");
 var slash            = require("slash");
@@ -100,7 +101,7 @@ module.exports = function (commander, filenames, opts) {
     results = [];
 
     _.each(filenames, function (filename) {
-      if (!fs.existsSync(filename)) return;
+      if (!pathExists.sync(filename)) return;
 
       var stat = fs.statSync(filename);
       if (stat.isDirectory()) {
@@ -134,7 +135,7 @@ module.exports = function (commander, filenames, opts) {
         ignoreInitial: true
       }).on("all", function (type, filename) {
         if (type === "add" || type === "change") {
-          console.log(type, filename);
+          util.log(type + " " + filename);
           try {
             walk();
           } catch (err) {

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

@@ -1,14 +1,17 @@
 #!/usr/bin/env node
 
+require("babel-core");
+
 var moduleFormatters = require("babel-core/lib/babel/transformation/modules");
+var pathExists       = require("path-exists");
 var commander        = require("commander");
 var transform        = require("babel-core").transform;
 var kebabCase        = require("lodash/string/kebabCase");
 var options          = require("babel-core").options;
 var util             = require("babel-core").util;
+var uniq             = require("lodash/array/uniq");
 var each             = require("lodash/collection/each");
 var keys             = require("lodash/object/keys");
-var fs               = require("fs");
 var glob             = require("glob");
 
 each(options, function (option, key) {
@@ -35,13 +38,14 @@ each(options, function (option, key) {
   if (option.description) desc.push(option.description);
 
   commander.option(arg, desc.join(" "));
-})
+});
 
 commander.option("-x, --extensions [extensions]", "List of extensions to compile when a directory has been input [.es6,.js,.es,.jsx]");
 commander.option("-w, --watch", "Recompile files on changes");
 commander.option("-o, --out-file [out]", "Compile all input files into a single file");
 commander.option("-d, --out-dir [out]", "Compile an input directory of modules into an output directory");
 commander.option("-D, --copy-files", "When compiling a directory copy over non-compilable files");
+commander.option("-q, --quiet", "Don't log anything");
 
 commander.on("--help", function () {
   var outKeys = function (title, obj) {
@@ -51,7 +55,7 @@ commander.on("--help", function () {
     each(keys(obj).sort(), function (key) {
       if (key[0] === "_") return;
 
-      if (obj[key].optional) key = "[" + key + "]";
+      if (obj[key].metadata && obj[key].metadata.optional) key = "[" + key + "]";
 
       console.log("    - " + key);
     });
@@ -64,7 +68,7 @@ commander.on("--help", function () {
 });
 
 var pkg = require("../../package.json");
-commander.version(pkg.version);
+commander.version(pkg.version + " (babel-core " + require("babel-core").version + ")");
 commander.usage("[options] <files ...>");
 commander.parse(process.argv);
 
@@ -84,8 +88,10 @@ var filenames = commander.args.reduce(function (globbed, input) {
   return globbed.concat(files);
 }, []);
 
+filenames = uniq(filenames);
+
 each(filenames, function (filename) {
-  if (!fs.existsSync(filename)) {
+  if (!pathExists.sync(filename)) {
     errors.push(filename + " doesn't exist");
   }
 });
@@ -118,11 +124,16 @@ if (errors.length) {
 var opts = exports.opts = {};
 
 each(options, function (opt, key) {
-  opts[key] = commander[key];
+  if (commander[key] !== undefined) {
+    opts[key] = commander[key];
+  }
 });
 
 opts.ignore = util.arrayify(opts.ignore, util.regexify);
-opts.only   = util.arrayify(opts.only, util.regexify);
+
+if (opts.only) {
+  opts.only = util.arrayify(opts.only, util.regexify);
+}
 
 var fn;
 

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

@@ -1,10 +1,11 @@
-var readdir = require("fs-readdir-recursive");
-var index   = require("./index");
-var babel   = require("babel-core");
-var util    = require("babel-core").util;
-var path    = require("path");
-var fs      = require("fs");
-var _       = require("lodash");
+var commander = require("commander");
+var readdir   = require("fs-readdir-recursive");
+var index     = require("./index");
+var babel     = require("babel-core");
+var util      = require("babel-core").util;
+var path      = require("path");
+var fs        = require("fs");
+var _         = require("lodash");
 
 exports.readdirFilter = function (filename) {
   return readdir(filename).filter(function (filename) {
@@ -24,6 +25,10 @@ exports.addSourceMappingUrl = function (code, loc) {
   return code + "\n//# sourceMappingURL=" + path.basename(loc);
 };
 
+exports.log = function (msg) {
+  if (!commander.quiet) console.log(msg);
+};
+
 exports.transform = function (filename, code, opts) {
   opts = _.defaults(opts || {}, index.opts);
   opts.filename = filename;
@@ -37,6 +42,15 @@ 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 +1,12 @@
 {
   "name": "babel",
   "description": "Turn ES6 code into readable vanilla ES5 with source maps",
-  "version": "5.5.0",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
   "license": "MIT",
   "repository": "babel/babel",
   "preferGlobal": true,
   "dependencies": {
-    "babel-core": "^5.5.0",
     "chokidar": "^1.0.0",
     "commander": "^2.6.0",
     "convert-source-map": "^1.1.0",
@@ -16,6 +14,7 @@
     "glob": "^5.0.5",
     "lodash": "^3.2.0",
     "output-file-sync": "^1.1.0",
+    "path-exists": "^1.0.0",
     "path-is-absolute": "^1.0.0",
     "source-map": "^0.4.0",
     "slash": "^1.0.0"
@@ -23,6 +22,7 @@
   "bin": {
     "babel": "./bin/babel/index.js",
     "babel-node": "./bin/babel-node",
-    "babel-external-helpers": "./bin/babel-external-helpers"
+    "babel-external-helpers": "./bin/babel-external-helpers",
+    "babel-plugin": "./bin/babel-plugin/index.js"
   }
-}
+}

packages/babel-runtime/package.json

@@ -1,11 +1,10 @@
 {
   "name": "babel-runtime",
   "description": "babel selfContained runtime",
-  "version": "5.5.0",
   "license": "MIT",
   "repository": "babel/babel",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "dependencies": {
     "core-js": "^0.9.0"
   }
-}
+}

packages/build-runtime.js

@@ -73,9 +73,8 @@ each(File.helpers, function (helperName) {
 writeFile("regenerator/index.js", readFile("regenerator/runtime-module", true));
 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"];
 
@@ -93,6 +92,5 @@ each(paths, function (path) {
   writeFile("core-js/" + path + ".js", defaultify('require("core-js/library/fn/' + path + '")'));
 });
 
-//
 
 updatePackage();

src/README.md

@@ -0,0 +1,27 @@
+## Welcome to the Babel Codebase
+
+Babel is broken down into three parts:
+
+- Parsing
+- [Transformation](babel/transformation/)
+- [Generation](babel/generation/)
+
+**Parsing** is the process of turning a piece of code into an [ESTree spec](https://github.com/estree/estree) compatible AST (Abstract
+Syntax Tree) which is a tree-like object of nodes that _describes_ the code.
+This makes it easier to transform the code over direct string manpulation.
+
+**Transformation** is the process of taking an AST and manipulating it into
+a new one. For example, Babel might take an ES2015 ArrowFunction and transform
+it into a normal Function which will work in ES5 environments.
+
+**Generation** is the process of turning an AST back into code. After Babel is
+done transforming the AST, the generation takes over to return normal code.
+
+---
+
+Babel's parsing step is done by [Acorn](https://github.com/marijnh/acorn). However, because Babel is implementing
+future standards it maintains a [fork of Acorn](acorn/) in order to do it's job. You can
+see that fork in the "acorn" folder.
+
+The transformation and generation steps are both handled inside of the Babel
+codebase itself, which is in the "babel" folder here.

src/acorn/plugins/flow.js

@@ -15,6 +15,15 @@ pp.expectRelational = function (op) {
   }
 }
 
+pp.flow_parseTypeInitialiser = function (tok) {
+  var oldInType = this.inType
+  this.inType = true
+  this.expect(tok || tt.colon)
+  var type = this.flow_parseType()
+  this.inType = oldInType
+  return type;
+}
+
 pp.flow_parseDeclareClass = function (node) {
   this.next()
   this.flow_parseInterfaceish(node, true)
@@ -40,9 +49,7 @@ pp.flow_parseDeclareFunction = function (node) {
   typeNode.params = tmp.params
   typeNode.rest = tmp.rest
   this.expect(tt.parenR)
-
-  this.expect(tt.colon)
-  typeNode.returnType = this.flow_parseType()
+  typeNode.returnType = this.flow_parseTypeInitialiser()
 
   typeContainer.typeAnnotation = this.finishNode(typeNode, "FunctionTypeAnnotation")
   id.typeAnnotation = this.finishNode(typeContainer, "TypeAnnotation")
@@ -153,15 +160,7 @@ pp.flow_parseTypeAlias = function (node) {
     node.typeParameters = null
   }
 
-  var oldInType = this.inType;
-  this.inType = true;
-
-  this.expect(tt.eq)
-
-  node.right = this.flow_parseType()
-
-  this.inType = oldInType;
-
+  node.right = this.flow_parseTypeInitialiser(tt.eq)
   this.semicolon()
 
   return this.finishNode(node, "TypeAlias")
@@ -214,11 +213,9 @@ pp.flow_parseObjectTypeIndexer = function (node, isStatic) {
 
   this.expect(tt.bracketL)
   node.id = this.flow_parseObjectPropertyKey()
-  this.expect(tt.colon)
-  node.key = this.flow_parseType()
+  node.key = this.flow_parseTypeInitialiser()
   this.expect(tt.bracketR)
-  this.expect(tt.colon)
-  node.value = this.flow_parseType()
+  node.value = this.flow_parseTypeInitialiser()
 
   this.flow_objectTypeSemicolon()
   return this.finishNode(node, "ObjectTypeIndexer")
@@ -245,8 +242,7 @@ pp.flow_parseObjectTypeMethodish = function (node) {
     node.rest = this.flow_parseFunctionTypeParam()
   }
   this.expect(tt.parenR)
-  this.expect(tt.colon)
-  node.returnType = this.flow_parseType()
+  node.returnType = this.flow_parseTypeInitialiser()
 
   return this.finishNode(node, "FunctionTypeAnnotation")
 }
@@ -265,7 +261,7 @@ pp.flow_parseObjectTypeCallProperty = function (node, isStatic) {
   var valueNode = this.startNode()
   node.static = isStatic
   node.value = this.flow_parseObjectTypeMethodish(valueNode)
-    this.flow_objectTypeSemicolon()
+  this.flow_objectTypeSemicolon()
   return this.finishNode(node, "ObjectTypeCallProperty")
 }
 
@@ -310,9 +306,8 @@ pp.flow_parseObjectType = function (allowStatic) {
         if (this.eat(tt.question)) {
           optional = true
         }
-        this.expect(tt.colon)
         node.key = propertyKey
-        node.value = this.flow_parseType()
+        node.value = this.flow_parseTypeInitialiser()
         node.optional = optional
         node.static = isStatic
         this.flow_objectTypeSemicolon()
@@ -352,12 +347,6 @@ pp.flow_parseGenericType = function (start, id) {
   return this.finishNode(node, "GenericTypeAnnotation")
 }
 
-pp.flow_parseVoidType = function () {
-  var node = this.startNode()
-  this.expect(tt._void)
-  return this.finishNode(node, "VoidTypeAnnotation")
-}
-
 pp.flow_parseTypeofType = function () {
   var node = this.startNode()
   this.expect(tt._typeof)
@@ -386,9 +375,8 @@ pp.flow_parseFunctionTypeParam = function () {
   if (this.eat(tt.question)) {
     optional = true
   }
-  this.expect(tt.colon)
   node.optional = optional
-  node.typeAnnotation = this.flow_parseType()
+  node.typeAnnotation = this.flow_parseTypeInitialiser()
   return this.finishNode(node, "FunctionTypeParam")
 }
 
@@ -411,6 +399,9 @@ pp.flow_identToTypeAnnotation = function (start, node, id) {
     case "any":
       return this.finishNode(node, "AnyTypeAnnotation")
 
+    case "void":
+      return this.finishNode(node, "VoidTypeAnnotation")
+
     case "bool":
     case "boolean":
       return this.finishNode(node, "BooleanTypeAnnotation")
@@ -524,14 +515,8 @@ pp.flow_parsePrimaryType = function () {
       return this.finishNode(node, "StringLiteralTypeAnnotation")
 
     default:
-      if (this.type.keyword) {
-        switch (this.type.keyword) {
-          case "void":
-            return this.flow_parseVoidType()
-
-          case "typeof":
-            return this.flow_parseTypeofType()
-        }
+      if (this.type.keyword === "typeof") {
+        return this.flow_parseTypeofType()
       }
   }
 
@@ -588,13 +573,7 @@ pp.flow_parseType = function () {
 
 pp.flow_parseTypeAnnotation = function () {
   var node = this.startNode()
-
-  var oldInType = this.inType
-  this.inType = true
-  this.expect(tt.colon)
-  node.typeAnnotation = this.flow_parseType()
-  this.inType = oldInType
-
+  node.typeAnnotation = this.flow_parseTypeInitialiser()
   return this.finishNode(node, "TypeAnnotation")
 }
 
@@ -694,6 +673,18 @@ acorn.plugins.flow = function (instance) {
     }
   })
 
+  // don't consider `void` to be a keyword as then it'll use the void token type
+  // and set startExpr
+  instance.extend("isKeyword", function (inner) {
+    return function(name) {
+      if (this.inType && name === "void") {
+        return false
+      } else {
+        return inner.call(this, name)
+      }
+    }
+  })
+
   instance.extend("readToken", function (inner) {
     return function(code) {
       if (this.inType && (code === 62 || code === 60)) {
@@ -800,16 +791,15 @@ acorn.plugins.flow = function (instance) {
 
   instance.extend("parseImportSpecifiers", function (inner) {
     return function (node) {
-      node.isType = false
-      if (this.isContextual("type")) {
-        var start = this.markPosition()
-        var typeId = this.parseIdent()
-        if ((this.type === tt.name && this.value !== "from") || this.type === tt.braceL || this.type === tt.star) {
-          node.isType = true
-        } else {
-          node.specifiers.push(this.parseImportSpecifierDefault(typeId, start))
-          if (this.isContextual("from")) return
-          this.eat(tt.comma)
+      node.importKind = "value"
+      var kind =
+        (this.type === tt._typeof ? "typeof" :
+        (this.isContextual("type") ? "type" : null))
+      if (kind) {
+        var lh = this.lookahead()
+        if ((lh.type === tt.name && lh.value !== "from") || lh.type === tt.braceL || lh.type === tt.star) {
+          this.next()
+          node.importKind = kind
         }
       }
       inner.call(this, node)

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()
@@ -270,20 +281,6 @@ pp.parseExprAtom = function(refShorthandDefaultPos) {
   case tt._yield:
     if (this.inGenerator) this.unexpected()
 
-  case tt._do:
-    if (this.options.features["es7.doExpressions"]) {
-      let node = this.startNode()
-      this.next()
-      var oldInFunction = this.inFunction
-      var oldLabels = this.labels
-      this.labels = []
-      this.inFunction = false
-      node.body = this.parseBlock()
-      this.inFunction = oldInFunction
-      this.labels = oldLabels
-      return this.finishNode(node, "DoExpression")
-    }
-
   case tt.name:
     let start = this.markPosition()
     node = this.startNode()
@@ -292,7 +289,7 @@ pp.parseExprAtom = function(refShorthandDefaultPos) {
     //
     if (this.options.features["es7.asyncFunctions"]) {
       // async functions!
-      if (id.name === "async") {
+      if (id.name === "async" && !this.canInsertSemicolon()) {
         // arrow functions
         if (this.type === tt.parenL) {
           let expr = this.parseParenAndDistinguishExpression(start, true, true)
@@ -421,9 +418,18 @@ pp.parseParenAndDistinguishExpression = function(start, isAsync, canBeArrow) {
     }
 
     let innerStart = this.markPosition(), exprList = [], first = true
-    let refShorthandDefaultPos = {start: 0}, spreadStart, innerParenStart
+    let refShorthandDefaultPos = {start: 0}, spreadStart, innerParenStart, optionalCommaStart
     while (this.type !== tt.parenR) {
-      first ? first = false : this.expect(tt.comma)
+      if (first) {
+        first = false;
+      } else {
+        this.expect(tt.comma)
+        if (this.type === tt.parenR && this.options.features["es7.trailingFunctionCommas"]) {
+          optionalCommaStart = this.start
+          break
+        }
+      }
+
       if (this.type === tt.ellipsis) {
         let spreadNodeStart = this.markPosition()
         spreadStart = this.start
@@ -451,6 +457,7 @@ pp.parseParenAndDistinguishExpression = function(start, isAsync, canBeArrow) {
         this.unexpected(this.lastTokStart)
       }
     }
+    if (optionalCommaStart) this.unexpected(optionalCommaStart)
     if (spreadStart) this.unexpected(spreadStart)
     if (refShorthandDefaultPos.start) this.unexpected(refShorthandDefaultPos.start)
 
@@ -609,6 +616,14 @@ 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 +649,12 @@ pp.parsePropertyName = function(prop) {
       prop.computed = true
       prop.key = this.parseMaybeAssign()
       this.expect(tt.bracketR)
-      return
+      return prop.key
     } else {
       prop.computed = false
     }
   }
-  prop.key = (this.type === tt.num || this.type === tt.string) ? this.parseExprAtom() : this.parseIdent(true)
+  return prop.key = (this.type === tt.num || this.type === tt.string) ? this.parseExprAtom() : this.parseIdent(true)
 }
 
 // Initialize empty function node.

src/acorn/src/lookahead.js

@@ -9,6 +9,7 @@ var STATE_KEYS = [
   "lastTokEnd",
   "lineStart",
   "startLoc",
+  "curLine",
   "endLoc",
   "start",
   "pos",
@@ -18,7 +19,11 @@ var STATE_KEYS = [
   "exprAllowed",
   "potentialArrowAt",
   "currLine",
-  "input"
+  "input",
+  "inType",
+  "inFunction",
+  "inGenerator",
+  "labels"
 ];
 
 pp.getState = function () {
@@ -28,6 +33,7 @@ pp.getState = function () {
     state[key] = this[key]
   }
   state.context = this.context.slice()
+  state.labels = this.labels.slice()
   return state
 };
 

src/acorn/src/lval.js

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

src/acorn/src/options.js

@@ -1,4 +1,4 @@
-import {has, isArray} from "./util"
+import {has} from "./util"
 import {SourceLocation} from "./location"
 
 // A second optional argument can be given to further configure
@@ -94,11 +94,11 @@ export function getOptions(opts) {
   for (let opt in defaultOptions)
     options[opt] = opts && has(opts, opt) ? opts[opt] : defaultOptions[opt]
 
-  if (isArray(options.onToken)) {
+  if (Array.isArray(options.onToken)) {
     let tokens = options.onToken
     options.onToken = (token) => tokens.push(token)
   }
-  if (isArray(options.onComment))
+  if (Array.isArray(options.onComment))
     options.onComment = pushComment(options, options.onComment)
 
   return options

src/acorn/src/state.js

@@ -1,13 +1,14 @@
 import {reservedWords, keywords} from "./identifier"
-import {types as tt, lineBreak} from "./tokentype"
+import {types as tt} from "./tokentype"
+import {lineBreak} from "./whitespace"
 
 export function Parser(options, input, startPos) {
   this.options = options
-  this.loadPlugins(this.options.plugins)
   this.sourceFile = this.options.sourceFile || null
   this.isKeyword = keywords[this.options.ecmaVersion >= 6 ? 6 : 5]
   this.isReservedWord = reservedWords[this.options.ecmaVersion]
   this.input = input
+  this.loadPlugins(this.options.plugins)
 
   // Set up token state
 

src/acorn/src/statement.js

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

src/acorn/src/tokenize.js

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

src/acorn/src/tokentype.js

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

src/acorn/src/util.js

@@ -1,7 +1,3 @@
-export function isArray(obj) {
-  return Object.prototype.toString.call(obj) === "[object Array]"
-}
-
 // Checks if an object has a property.
 
 export function has(obj, propName) {

src/babel/README.md

@@ -0,0 +1,4 @@
+## Diving into Babel
+
+If you look around in the various directories in here you'll find some details
+about the organization of the Babel codebase.

src/babel/api/README.md

@@ -0,0 +1,18 @@
+## API
+
+In this directory you'll find all the public interfaces to using Babel for both
+node and the browser.
+
+### Node
+
+There are two ways people use Babel within Node, they either are manipulating
+strings of code with `babel.transform` or `babel.parse`, they also might be
+running their code through Babel before execution via `register` or `polyfill`.
+
+### Browser
+
+Usage of Babel in the browser is extremely uncommon and in most cases
+considered A Bad Idea™. However it works by loading `<script>`'s with XHR,
+transforming them and then executing them. These `<script>`'s need to have a
+`type` of "text/ecmascript-6", "text/babel", or "module" ("text/6to5" exists as
+well for legacy reasons).

src/babel/api/browser.js

@@ -3,16 +3,32 @@
 require("./node");
 var transform = module.exports = require("../transformation");
 
+/**
+ * Add `options` and `version` to `babel` global.
+ */
+
 transform.options = require("../transformation/file/options");
 transform.version = require("../../../package").version;
 
+/**
+ * Add `transform` api to `babel` global.
+ */
+
 transform.transform = transform;
 
+/**
+ * Tranform and execute script, adding in inline sourcemaps.
+ */
+
 transform.run = function (code, opts = {}) {
   opts.sourceMaps = "inline";
   return new Function(transform(code, opts).code)();
 };
 
+/**
+ * Load scripts via xhr, and `transform` when complete (optional).
+ */
+
 transform.load = function (url, callback, opts = {}, hold) {
   opts.filename = opts.filename || url;
 
@@ -20,6 +36,10 @@ transform.load = function (url, callback, opts = {}, hold) {
   xhr.open("GET", url, true);
   if ("overrideMimeType" in xhr) xhr.overrideMimeType("text/plain");
 
+  /**
+   * When successfully loaded, transform (optional), and call `callback`.
+   */
+
   xhr.onreadystatechange = function () {
     if (xhr.readyState !== 4) return;
 
@@ -36,11 +56,22 @@ transform.load = function (url, callback, opts = {}, hold) {
   xhr.send(null);
 };
 
+/**
+ * Load and transform all scripts of `types`.
+ *
+ * @example
+ * <script type="module"></script>
+ */
+
 var runScripts = function () {
   var scripts = [];
   var types   = ["text/ecmascript-6", "text/6to5", "text/babel", "module"];
   var index   = 0;
 
+  /**
+   * Transform and execute script. Ensures correct load order.
+   */
+
   var exec = function () {
     var param = scripts[index];
     if (param instanceof Array) {
@@ -50,6 +81,10 @@ var runScripts = function () {
     }
   };
 
+  /**
+   * Load, transform, and execute all scripts.
+   */
+
   var run = function (script, i) {
     var opts = {};
 
@@ -64,7 +99,9 @@ var runScripts = function () {
     }
   };
 
-  var _scripts = global.document .getElementsByTagName("script");
+  // Collect scripts with Babel `types`.
+
+  var _scripts = global.document.getElementsByTagName("script");
 
   for (var i = 0; i < _scripts.length; ++i) {
     var _script = _scripts[i];
@@ -78,6 +115,10 @@ var runScripts = function () {
   exec();
 };
 
+/**
+ * Register load event to transform and execute scripts.
+ */
+
 if (global.addEventListener) {
   global.addEventListener("DOMContentLoaded", runScripts, false);
 } else if (global.attachEvent) {

src/babel/api/node.js

@@ -8,9 +8,10 @@ export { util, acorn, transform };
 export { pipeline } from "../transformation";
 export { canCompile } from "../util";
 
-export { default as options } from "../transformation/file/options";
+export { default as options } from "../transformation/file/options/config";
+export { default as Plugin } from "../transformation/plugin";
 export { default as Transformer } from "../transformation/transformer";
-export { default as TransformerPipeline } from "../transformation/transformer-pipeline";
+export { default as Pipeline } from "../transformation/pipeline";
 export { default as traverse } from "../traversal";
 export { default as buildExternalHelpers } from "../tools/build-external-helpers";
 export { version } from "../../../package";
@@ -18,16 +19,28 @@ export { version } from "../../../package";
 import * as t from "../types";
 export { t as types };
 
+/**
+ * Register Babel and polyfill globally.
+ */
+
 export function register(opts?: Object) {
   var callback = require("./register/node-polyfill");
   if (opts != null) callback(opts);
   return callback;
 }
 
+/**
+ * Register polyfill globally.
+ */
+
 export function polyfill() {
   require("../polyfill");
 }
 
+/**
+ * Asynchronously transform `filename` with optional `opts`, calls `callback` when complete.
+ */
+
 export function transformFile(filename: string, opts?: Object, callback: Function) {
   if (isFunction(opts)) {
     callback = opts;
@@ -51,11 +64,19 @@ export function transformFile(filename: string, opts?: Object, callback: Functio
   });
 }
 
+/**
+ * Synchronous form of `transformFile`.
+ */
+
 export function transformFileSync(filename: string, opts?: Object = {}) {
   opts.filename = filename;
   return transform(fs.readFileSync(filename, "utf8"), opts);
 }
 
+/**
+ * Parse script with Babel's parser.
+ */
+
 export function parse(code, opts = {}) {
   opts.allowHashBang = true;
   opts.sourceType = "module";

src/babel/api/register/cache.js

@@ -1,21 +1,30 @@
 import path from "path";
 import fs from "fs";
 import homeOrTmp from "home-or-tmp";
+import pathExists from "path-exists";
 
 const FILENAME = process.env.BABEL_CACHE_PATH || path.join(homeOrTmp, ".babel.json");
 var data = {};
 
+/**
+ * Write stringified cache to disk.
+ */
+
 export function save() {
   fs.writeFileSync(FILENAME, JSON.stringify(data, null, "  "));
 }
 
+/**
+ * Load cache from disk and parse.
+ */
+
 export function load() {
   if (process.env.BABEL_DISABLE_CACHE) return;
 
   process.on("exit", save);
   process.nextTick(save);
 
-  if (!fs.existsSync(FILENAME)) return;
+  if (!pathExists.sync(FILENAME)) return;
 
   try {
     data = JSON.parse(fs.readFileSync(FILENAME));
@@ -24,6 +33,10 @@ export function load() {
   }
 }
 
+/**
+ * Retrieve data from cache.
+ */
+
 export function get() {
   return data;
 }

src/babel/api/register/node.js

@@ -1,6 +1,6 @@
 import sourceMapSupport from "source-map-support";
 import * as registerCache from "./cache";
-import resolveRc from "../../tools/resolve-rc";
+import OptionManager from "../../transformation/file/options/option-manager";
 import extend from "lodash/object/extend";
 import * as babel from "../node";
 import each from "lodash/collection/each";
@@ -8,6 +8,10 @@ import * as util from  "../../util";
 import fs from "fs";
 import path from "path";
 
+/**
+ * Install sourcemaps into node.
+ */
+
 sourceMapSupport.install({
   handleUncaughtExceptions: false,
   retrieveSourceMap(source) {
@@ -23,12 +27,16 @@ sourceMapSupport.install({
   }
 });
 
-//
+/**
+ * Load and setup cache.
+ */
 
 registerCache.load();
 var cache = registerCache.get();
 
-//
+/**
+ * Store options.
+ */
 
 var transformOpts = {};
 
@@ -38,24 +46,34 @@ var only;
 var oldHandlers   = {};
 var maps          = {};
 
-var cwd = require.main ? require.main.filename : process.cwd();
+var cwd = process.cwd();
+
+/**
+ * Get path from `filename` relative to the current working directory.
+ */
 
 var getRelativePath = function (filename){
   return path.relative(cwd, filename);
 };
 
+/**
+ * Get last modified time for a `filename`.
+ */
+
 var mtime = function (filename) {
   return +fs.statSync(filename).mtime;
 };
 
+/**
+ * Compile a `filename` with optional `opts`.
+ */
+
 var compile = function (filename, opts = {}) {
   var result;
 
-  opts = extend(opts, transformOpts);
-
-  // this will be done when the file is transformed anyway but we need all
-  // the options so we can generate the cache key
-  resolveRc(filename, opts);
+  var optsManager = new OptionManager;
+  optsManager.mergeOptions(transformOpts);
+  opts = optsManager.init(opts);
 
   var cacheKey = `${filename}:${JSON.stringify(opts)}:${babel.version}`;
 
@@ -86,14 +104,22 @@ var compile = function (filename, opts = {}) {
   return result.code;
 };
 
+/**
+ * Test if a `filename` should be ignored by Babel.
+ */
+
 var shouldIgnore = function (filename) {
   if (!ignore && !only) {
     return getRelativePath(filename).split(path.sep).indexOf("node_modules") >= 0;
   } else {
-    return util.shouldIgnore(filename, ignore || [], only || []);
+    return util.shouldIgnore(filename, ignore || [], only);
   }
 };
 
+/**
+ * Monkey patch istanbul if it is running so that it works properly.
+ */
+
 var istanbulMonkey = {};
 
 if (process.env.running_under_istanbul) {
@@ -105,7 +131,7 @@ if (process.env.running_under_istanbul) {
     if (istanbulMonkey[filename]) {
       delete istanbulMonkey[filename];
       var code = compile(filename, {
-        attachAuxiliaryComment: "istanbul ignore next"
+        auxiliaryCommentBefore: "istanbul ignore next"
       });
       istanbulMonkey[filename] = true;
       return code;
@@ -115,17 +141,29 @@ if (process.env.running_under_istanbul) {
   };
 }
 
+/**
+ * Replacement for the loader for istanbul.
+ */
+
 var istanbulLoader = function (m, filename, old) {
   istanbulMonkey[filename] = true;
   old(m, filename);
 };
 
+/**
+ * Default loader.
+ */
+
 var normalLoader = function (m, filename) {
   m._compile(compile(filename), filename);
 };
 
+/**
+ * Register a loader for an extension.
+ */
+
 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;
@@ -139,6 +177,10 @@ var registerExtension = function (ext) {
   };
 };
 
+/**
+ * Register loader for given extensions.
+ */
+
 var hookExtensions = function (_exts) {
   each(oldHandlers, function (old, ext) {
     if (old === undefined) {
@@ -156,8 +198,16 @@ var hookExtensions = function (_exts) {
   });
 };
 
+/**
+ * Register loader for default extensions.
+ */
+
 hookExtensions(util.canCompile.EXTENSIONS);
 
+/**
+ * Update options at runtime.
+ */
+
 export default function (opts = {}) {
   if (opts.only != null) only = util.arrayify(opts.only, util.regexify);
   if (opts.ignore != null) ignore = util.arrayify(opts.ignore, util.regexify);

src/babel/generation/README.md

@@ -0,0 +1,16 @@
+## Generation
+
+Here is Babel's code generator, here you'll find all of the code to turn an AST
+back into a string of code.
+
+[TBD: To Be Documented:]
+
+- Code Generator
+- Buffer
+- Source Maps
+  - Position
+- Printer
+- Code Style
+  - Whitespace
+  - Parenthesis
+- Generators

src/babel/generation/buffer.js

@@ -4,6 +4,10 @@ import isBoolean from "lodash/lang/isBoolean";
 import includes from "lodash/collection/includes";
 import isNumber from "lodash/lang/isNumber";
 
+/**
+ * Buffer for collecting generated output.
+ */
+
 export default class Buffer {
   constructor(position, format) {
     this.position = position;
@@ -12,10 +16,18 @@ export default class Buffer {
     this.buf      = "";
   }
 
+  /**
+   * Get the current trimmed buffer.
+   */
+
   get() {
     return trimRight(this.buf);
   }
 
+  /**
+   * Get the current indent.
+   */
+
   getIndent() {
     if (this.format.compact || this.format.concise) {
       return "";
@@ -24,43 +36,80 @@ export default class Buffer {
     }
   }
 
+  /**
+   * Get the current indent size.
+   */
+
   indentSize() {
     return this.getIndent().length;
   }
 
+  /**
+   * Increment indent size.
+   */
+
   indent() {
     this._indent++;
   }
 
+  /**
+   * Decrement indent size.
+   */
+
   dedent() {
     this._indent--;
   }
 
+  /**
+   * Add a semicolon to the buffer.
+   */
+
   semicolon() {
     this.push(";");
   }
 
+  /**
+   * Ensure last character is a semicolon.
+   */
+
   ensureSemicolon() {
     if (!this.isLast(";")) this.semicolon();
   }
 
+  /**
+   * Add a right brace to the buffer.
+   */
+
   rightBrace() {
     this.newline(true);
     this.push("}");
   }
 
+  /**
+   * Add a keyword to the buffer.
+   */
+
   keyword(name) {
     this.push(name);
     this.space();
   }
 
-  space() {
-    if (this.format.compact) return;
-    if (this.buf && !this.isLast(" ") && !this.isLast("\n")) {
+  /**
+   * Add a space to the buffer unless it is compact (override with force).
+   */
+
+  space(force?) {
+    if (!force && this.format.compact) return;
+
+    if (force || this.buf && !this.isLast(" ") && !this.isLast("\n")) {
       this.push(" ");
     }
   }
 
+  /**
+   * Remove the last character.
+   */
+
   removeLast(cha) {
     if (this.format.compact) return;
     if (!this.isLast(cha)) return;
@@ -69,6 +118,11 @@ export default class Buffer {
     this.position.unshift(cha);
   }
 
+  /**
+   * Add a newline (or many newlines), maintaining formatting.
+   * Strips multiple newlines if removeLast is true.
+   */
+
   newline(i, removeLast) {
     if (this.format.compact || this.format.retainLines) return;
 
@@ -99,6 +153,10 @@ export default class Buffer {
     this._newline(removeLast);
   }
 
+  /**
+   * Adds a newline unless there is already two previous newlines.
+   */
+
   _newline(removeLast) {
     // never allow more than two lines
     if (this.endsWith("\n\n")) return;
@@ -135,6 +193,10 @@ export default class Buffer {
     }
   }
 
+  /**
+   * Push a string to the buffer, maintaining indentation and newlines.
+   */
+
   push(str, noIndent) {
     if (!this.format.compact && this._indent && !noIndent && str !== "\n") {
       // we have an indent level and we aren't pushing a newline
@@ -150,15 +212,31 @@ export default class Buffer {
     this._push(str);
   }
 
+  /**
+   * Push a string to the buffer.
+   */
+
   _push(str) {
     this.position.push(str);
     this.buf += str;
   }
 
-  endsWith(str) {
-    return this.buf.slice(-str.length) === str;
+  /**
+   * Test if the buffer ends with a string.
+   */
+
+  endsWith(str, buf = this.buf) {
+    if (str.length === 1) {
+      return buf[buf.length - 1] === str;
+    } else {
+      return buf.slice(-str.length) === str;
+    }
   }
 
+  /**
+   * Test if a character is last in the buffer.
+   */
+
   isLast(cha) {
     if (this.format.compact) return false;
 

src/babel/generation/generators/README.md

@@ -0,0 +1,10 @@
+## Generators
+
+Code generation in Babel is broken down into generators by node type, they all
+live in this directory.
+
+[TBD: To Be Documented:]
+
+- How generators work
+- How to print a node
+- How generators related to one another

src/babel/generation/generators/base.js

@@ -1,11 +1,23 @@
+/**
+ * Print File.program
+ */
+
 export function File(node, print) {
   print.plain(node.program);
 }
 
+/**
+ * Print all nodes in a Program.body.
+ */
+
 export function Program(node, print) {
   print.sequence(node.body);
 }
 
+/**
+ * Print BlockStatement, collapses empty blocks, prints body.
+ */
+
 export function BlockStatement(node, print) {
   if (node.body.length === 0) {
     this.push("{}");
@@ -17,3 +29,14 @@ export function BlockStatement(node, print) {
     this.rightBrace();
   }
 }
+
+/**
+ * What is my purpose?
+ * Why am I here?
+ * Why are any of us here?
+ * Does any of this really matter?
+ */
+
+export function Noop() {
+
+}

src/babel/generation/generators/classes.js

@@ -1,5 +1,9 @@
+/**
+ * Print ClassDeclaration, prints decorators, typeParameters, extends, implements, and body.
+ */
+
 export function ClassDeclaration(node, print) {
-  print.list(node.decorators);
+  print.list(node.decorators, { separator: "" });
   this.push("class");
 
   if (node.id) {
@@ -24,8 +28,16 @@ export function ClassDeclaration(node, print) {
   print.plain(node.body);
 }
 
+/**
+ * Alias ClassDeclaration printer as ClassExpression.
+ */
+
 export { ClassDeclaration as ClassExpression };
 
+/**
+ * Print ClassBody, collapses empty blocks, prints body.
+ */
+
 export function ClassBody(node, print) {
   if (node.body.length === 0) {
     this.push("{}");
@@ -41,9 +53,13 @@ export function ClassBody(node, print) {
   }
 }
 
+/**
+ * Print ClassProperty, prints decorators, static, key, typeAnnotation, and value.
+ * Also: semicolons, deal with it.
+ */
 
 export function ClassProperty(node, print) {
-  print.list(node.decorators);
+  print.list(node.decorators, { separator: "" });
 
   if (node.static) this.push("static ");
   print.plain(node.key);
@@ -57,8 +73,12 @@ export function ClassProperty(node, print) {
   this.semicolon();
 }
 
+/**
+ * Print MethodDefinition, prints decorations, static, and method.
+ */
+
 export function MethodDefinition(node, print) {
-  print.list(node.decorators);
+  print.list(node.decorators, { separator: "" });
 
   if (node.static) {
     this.push("static ");

src/babel/generation/generators/comprehensions.js

@@ -1,3 +1,7 @@
+/**
+ * Prints ComprehensionBlock, prints left and right.
+ */
+
 export function ComprehensionBlock(node, print) {
   this.keyword("for");
   this.push("(");
@@ -7,6 +11,10 @@ export function ComprehensionBlock(node, print) {
   this.push(")");
 }
 
+/**
+ * Prints ComprehensionExpression, prints blocks, filter, and body. Handles generators.
+ */
+
 export function ComprehensionExpression(node, print) {
   this.push(node.generator ? "(" : "[");
 

src/babel/generation/generators/expressions.js

@@ -1,30 +1,41 @@
-import isInteger from "is-integer";
 import isNumber from "lodash/lang/isNumber";
 import * as t from "../../types";
 
+/**
+ * Prints UnaryExpression, prints operator and argument.
+ */
+
 export function UnaryExpression(node, print) {
-  var hasSpace = /[a-z]$/.test(node.operator);
+  var needsSpace = /[a-z]$/.test(node.operator);
   var arg = node.argument;
 
   if (t.isUpdateExpression(arg) || t.isUnaryExpression(arg)) {
-    hasSpace = true;
+    needsSpace = true;
   }
 
   if (t.isUnaryExpression(arg) && arg.operator === "!") {
-    hasSpace = false;
+    needsSpace = false;
   }
 
   this.push(node.operator);
-  if (hasSpace) this.push(" ");
+  if (needsSpace) this.push(" ");
   print.plain(node.argument);
 }
 
-export function DoExpression(node, print) {
-  this.push("do");
-  this.space();
-  print.plain(node.body);
+/**
+ * Prints ParenthesizedExpression, prints expression.
+ */
+
+export function ParenthesizedExpression(node, print) {
+  this.push("(");
+  print.plain(node.expression);
+  this.push(")");
 }
 
+/**
+ * Prints UpdateExpression, prints operator and argument.
+ */
+
 export function UpdateExpression(node, print) {
   if (node.prefix) {
     this.push(node.operator);
@@ -35,6 +46,10 @@ export function UpdateExpression(node, print) {
   }
 }
 
+/**
+ * Prints ConditionalExpression, prints test, consequent, and alternate.
+ */
+
 export function ConditionalExpression(node, print) {
   print.plain(node.test);
   this.space();
@@ -47,6 +62,10 @@ export function ConditionalExpression(node, print) {
   print.plain(node.alternate);
 }
 
+/**
+ * Prints NewExpression, prints callee and arguments.
+ */
+
 export function NewExpression(node, print) {
   this.push("new ");
   print.plain(node.callee);
@@ -55,41 +74,59 @@ export function NewExpression(node, print) {
   this.push(")");
 }
 
+/**
+ * Prints SequenceExpression.expressions.
+ */
+
 export function SequenceExpression(node, print) {
   print.list(node.expressions);
 }
 
+/**
+ * Prints ThisExpression.
+ */
+
 export function ThisExpression() {
   this.push("this");
 }
 
+/**
+ * Prints Super.
+ */
+
 export function Super() {
   this.push("super");
 }
 
+/**
+ * Prints Decorator, prints expression.
+ */
+
 export function Decorator(node, print) {
   this.push("@");
   print.plain(node.expression);
+  this.newline();
 }
 
+/**
+ * Prints CallExpression, prints callee and arguments.
+ */
+
 export function CallExpression(node, print) {
   print.plain(node.callee);
 
   this.push("(");
 
-  var separator = ",";
-
-  var isPrettyCall = node._prettyCall && !this.format.retainLines;
+  var isPrettyCall = node._prettyCall && !this.format.retainLines && !this.format.compact;
 
+  var separator;
   if (isPrettyCall) {
-    separator += "\n";
+    separator = ",\n";
     this.newline();
     this.indent();
-  } else {
-    separator += " ";
   }
 
-  print.list(node.arguments, { separator: separator });
+  print.list(node.arguments, { separator });
 
   if (isPrettyCall) {
     this.newline();
@@ -99,6 +136,11 @@ export function CallExpression(node, print) {
   this.push(")");
 }
 
+/**
+ * Builds yield or await expression printer.
+ * Prints delegate, all, and argument.
+ */
+
 var buildYieldAwait = function (keyword) {
   return function (node, print) {
     this.push(keyword);
@@ -114,40 +156,90 @@ var buildYieldAwait = function (keyword) {
   };
 };
 
+/**
+ * Create YieldExpression and AwaitExpression printers.
+ */
+
 export var YieldExpression = buildYieldAwait("yield");
 export var AwaitExpression = buildYieldAwait("await");
 
+/**
+ * Prints EmptyStatement.
+ */
+
 export function EmptyStatement() {
   this.semicolon();
 }
 
+/**
+ * Prints ExpressionStatement, prints expression.
+ */
+
 export function ExpressionStatement(node, print) {
   print.plain(node.expression);
   this.semicolon();
 }
 
+/**
+ * Prints AssignmentPattern, prints left and right.
+ */
+
+export function AssignmentPattern(node, print) {
+  print.plain(node.left);
+  this.push(" = ");
+  print.plain(node.right);
+}
+
+/**
+ * Prints AssignmentExpression, prints left, operator, and right.
+ */
+
 export function AssignmentExpression(node, print) {
   // todo: add cases where the spaces can be dropped when in compact mode
   print.plain(node.left);
-  this.push(" ");
+
+  var spaces = node.operator === "in" || node.operator === "instanceof";
+  spaces = true; // todo: https://github.com/babel/babel/issues/1835
+  this.space(spaces);
+
   this.push(node.operator);
-  this.push(" ");
+
+  if (!spaces) {
+    // space is mandatory to avoid outputting <!--
+    // http://javascript.spec.whatwg.org/#comment-syntax
+    spaces = node.operator === "<" &&
+             t.isUnaryExpression(node.right, { prefix: true, operator: "!" }) &&
+             t.isUnaryExpression(node.right.argument, { prefix: true, operator: "--" });
+  }
+
+  this.space(spaces);
+
   print.plain(node.right);
 }
 
+/**
+ * Prints BindExpression, prints object and callee.
+ */
+
 export function BindExpression(node, print) {
   print.plain(node.object);
   this.push("::");
   print.plain(node.callee);
 }
 
+/**
+ * Alias ClassDeclaration printer as ClassExpression,
+ * and AssignmentExpression printer as LogicalExpression.
+ */
+
 export {
   AssignmentExpression as BinaryExpression,
-  AssignmentExpression as LogicalExpression,
-  AssignmentExpression as AssignmentPattern
+  AssignmentExpression as LogicalExpression
 };
 
-var SCIENTIFIC_NOTATION = /e/i;
+/**
+ * Print MemberExpression, prints object, property, and value. Handles computed.
+ */
 
 export function MemberExpression(node, print) {
   var obj = node.object;
@@ -167,16 +259,15 @@ 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);
   }
 }
 
+/**
+ * Print MetaProperty, prints meta and property.
+ */
+
 export function MetaProperty(node, print) {
   print.plain(node.meta);
   this.push(".");

src/babel/generation/generators/flow.js

@@ -1,24 +1,44 @@
 import * as t from "../../types";
 
+/**
+ * Prints AnyTypeAnnotation.
+ */
+
 export function AnyTypeAnnotation() {
   this.push("any");
 }
 
+/**
+ * Prints ArrayTypeAnnotation, prints elementType.
+ */
+
 export function ArrayTypeAnnotation(node, print) {
   print.plain(node.elementType);
   this.push("[");
   this.push("]");
 }
 
+/**
+ * Prints BooleanTypeAnnotation.
+ */
+
 export function BooleanTypeAnnotation(node) {
   this.push("bool");
 }
 
+/**
+ * Prints DeclareClass, prints node.
+ */
+
 export function DeclareClass(node, print) {
   this.push("declare class ");
   this._interfaceish(node, print);
 }
 
+/**
+ * Prints DeclareFunction, prints id and id.typeAnnotation.
+ */
+
 export function DeclareFunction(node, print) {
   this.push("declare function ");
   print.plain(node.id);
@@ -26,6 +46,10 @@ export function DeclareFunction(node, print) {
   this.semicolon();
 }
 
+/**
+ * Prints DeclareModule, prints id and body.
+ */
+
 export function DeclareModule(node, print) {
   this.push("declare module ");
   print.plain(node.id);
@@ -33,6 +57,10 @@ export function DeclareModule(node, print) {
   print.plain(node.body);
 }
 
+/**
+ * Prints DeclareVariable, prints id and id.typeAnnotation.
+ */
+
 export function DeclareVariable(node, print) {
   this.push("declare var ");
   print.plain(node.id);
@@ -40,6 +68,10 @@ export function DeclareVariable(node, print) {
   this.semicolon();
 }
 
+/**
+ * Prints FunctionTypeAnnotation, prints typeParameters, params, and rest.
+ */
+
 export function FunctionTypeAnnotation(node, print, parent) {
   print.plain(node.typeParameters);
   this.push("(");
@@ -68,6 +100,10 @@ export function FunctionTypeAnnotation(node, print, parent) {
   print.plain(node.returnType);
 }
 
+/**
+ * Prints FunctionTypeParam, prints name and typeAnnotation, handles optional.
+ */
+
 export function FunctionTypeParam(node, print) {
   print.plain(node.name);
   if (node.optional) this.push("?");
@@ -76,13 +112,26 @@ export function FunctionTypeParam(node, print) {
   print.plain(node.typeAnnotation);
 }
 
+/**
+ * Prints InterfaceExtends, prints id and typeParameters.
+ */
+
 export function InterfaceExtends(node, print) {
   print.plain(node.id);
   print.plain(node.typeParameters);
 }
 
+/**
+ * Alias InterfaceExtends printer as ClassImplements,
+ * and InterfaceExtends printer as GenericTypeAnnotation.
+ */
+
 export { InterfaceExtends as ClassImplements, InterfaceExtends as GenericTypeAnnotation };
 
+/**
+ * Prints interface-like node, prints id, typeParameters, extends, and body.
+ */
+
 export function _interfaceish(node, print) {
   print.plain(node.id);
   print.plain(node.typeParameters);
@@ -94,47 +143,87 @@ export function _interfaceish(node, print) {
   print.plain(node.body);
 }
 
+/**
+ * Prints InterfaceDeclaration, prints node.
+ */
+
 export function InterfaceDeclaration(node, print) {
   this.push("interface ");
   this._interfaceish(node, print);
 }
 
+/**
+ * Prints IntersectionTypeAnnotation, prints types.
+ */
+
 export function IntersectionTypeAnnotation(node, print) {
   print.join(node.types, { separator: " & " });
 }
 
+/**
+ * Prints MixedTypeAnnotation.
+ */
+
 export function MixedTypeAnnotation() {
   this.push("mixed");
 }
 
+/**
+ * Prints NullableTypeAnnotation, prints typeAnnotation.
+ */
+
 export function NullableTypeAnnotation(node, print) {
   this.push("?");
   print.plain(node.typeAnnotation);
 }
 
+/**
+ * Prints NumberTypeAnnotation.
+ */
+
 export function NumberTypeAnnotation() {
   this.push("number");
 }
 
+/**
+ * Prints StringLiteralTypeAnnotation, prints value.
+ */
+
 export function StringLiteralTypeAnnotation(node) {
   this._stringLiteral(node.value);
 }
 
+/**
+ * Prints StringTypeAnnotation.
+ */
+
 export function StringTypeAnnotation() {
   this.push("string");
 }
 
+/**
+ * Prints TupleTypeAnnotation, prints types.
+ */
+
 export function TupleTypeAnnotation(node, print) {
   this.push("[");
   print.join(node.types, { separator: ", " });
   this.push("]");
 }
 
+/**
+ * Prints TypeofTypeAnnotation, prints argument.
+ */
+
 export function TypeofTypeAnnotation(node, print) {
   this.push("typeof ");
   print.plain(node.argument);
 }
 
+/**
+ * Prints TypeAlias, prints id, typeParameters, and right.
+ */
+
 export function TypeAlias(node, print) {
   this.push("type ");
   print.plain(node.id);
@@ -146,6 +235,10 @@ export function TypeAlias(node, print) {
   this.semicolon();
 }
 
+/**
+ * Prints TypeAnnotation, prints typeAnnotation, handles optional.
+ */
+
 export function TypeAnnotation(node, print) {
   this.push(":");
   this.space();
@@ -153,14 +246,26 @@ export function TypeAnnotation(node, print) {
   print.plain(node.typeAnnotation);
 }
 
+/**
+ * Prints TypeParameterInstantiation, prints params.
+ */
+
 export function TypeParameterInstantiation(node, print) {
   this.push("<");
   print.join(node.params, { separator: ", " });
   this.push(">");
 }
 
+/**
+ * Alias TypeParameterInstantiation printer as TypeParameterDeclaration
+ */
+
 export { TypeParameterInstantiation as TypeParameterDeclaration };
 
+/**
+ * Prints ObjectTypeAnnotation, prints properties, callProperties, and indexers.
+ */
+
 export function ObjectTypeAnnotation(node, print) {
   this.push("{");
   var props = node.properties.concat(node.callProperties, node.indexers);
@@ -185,11 +290,19 @@ export function ObjectTypeAnnotation(node, print) {
   this.push("}");
 }
 
+/**
+ * Prints ObjectTypeCallProperty, prints value, handles static.
+ */
+
 export function ObjectTypeCallProperty(node, print) {
   if (node.static) this.push("static ");
   print.plain(node.value);
 }
 
+/**
+ * Prints ObjectTypeIndexer, prints id, key, and value, handles static.
+ */
+
 export function ObjectTypeIndexer(node, print) {
   if (node.static) this.push("static ");
   this.push("[");
@@ -203,6 +316,10 @@ export function ObjectTypeIndexer(node, print) {
   print.plain(node.value);
 }
 
+/**
+ * Prints ObjectTypeProperty, prints static, key, and value.
+ */
+
 export function ObjectTypeProperty(node, print) {
   if (node.static) this.push("static ");
   print.plain(node.key);
@@ -214,16 +331,28 @@ export function ObjectTypeProperty(node, print) {
   print.plain(node.value);
 }
 
+/**
+ * Prints QualifiedTypeIdentifier, prints qualification and id.
+ */
+
 export function QualifiedTypeIdentifier(node, print) {
   print.plain(node.qualification);
   this.push(".");
   print.plain(node.id);
 }
 
+/**
+ * Prints UnionTypeAnnotation, prints types.
+ */
+
 export function UnionTypeAnnotation(node, print) {
   print.join(node.types, { separator: " | " });
 }
 
+/**
+ * Prints TypeCastExpression, prints expression and typeAnnotation.
+ */
+
 export function TypeCastExpression(node, print) {
   this.push("(");
   print.plain(node.expression);
@@ -231,6 +360,10 @@ export function TypeCastExpression(node, print) {
   this.push(")");
 }
 
+/**
+ * Prints VoidTypeAnnotation.
+ */
+
 export function VoidTypeAnnotation(node) {
   this.push("void");
 }

src/babel/generation/generators/jsx.js

@@ -1,5 +1,9 @@
 import * as t from "../../types";
 
+/**
+ * Prints JSXAttribute, prints name and value.
+ */
+
 export function JSXAttribute(node, print) {
   print.plain(node.name);
   if (node.value) {
@@ -8,34 +12,58 @@ export function JSXAttribute(node, print) {
   }
 }
 
+/**
+ * Prints JSXIdentifier, prints name.
+ */
+
 export function JSXIdentifier(node) {
   this.push(node.name);
 }
 
+/**
+ * Prints JSXNamespacedName, prints namespace and name.
+ */
+
 export function JSXNamespacedName(node, print) {
   print.plain(node.namespace);
   this.push(":");
   print.plain(node.name);
 }
 
+/**
+ * Prints JSXMemberExpression, prints object and property.
+ */
+
 export function JSXMemberExpression(node, print) {
   print.plain(node.object);
   this.push(".");
   print.plain(node.property);
 }
 
+/**
+ * Prints JSXSpreadAttribute, prints argument.
+ */
+
 export function JSXSpreadAttribute(node, print) {
   this.push("{...");
   print.plain(node.argument);
   this.push("}");
 }
 
+/**
+ * Prints JSXExpressionContainer, prints expression.
+ */
+
 export function JSXExpressionContainer(node, print) {
   this.push("{");
   print.plain(node.expression);
   this.push("}");
 }
 
+/**
+ * Prints JSXElement, prints openingElement, children, and closingElement.
+ */
+
 export function JSXElement(node, print) {
   var open = node.openingElement;
   print.plain(open);
@@ -54,6 +82,10 @@ export function JSXElement(node, print) {
   print.plain(node.closingElement);
 }
 
+/**
+ * Prints JSXOpeningElement, prints name and attributes, handles selfClosing.
+ */
+
 export function JSXOpeningElement(node, print) {
   this.push("<");
   print.plain(node.name);
@@ -64,10 +96,18 @@ export function JSXOpeningElement(node, print) {
   this.push(node.selfClosing ? " />" : ">");
 }
 
+/**
+ * Prints JSXClosingElement, prints name.
+ */
+
 export function JSXClosingElement(node, print) {
   this.push("</");
   print.plain(node.name);
   this.push(">");
 }
 
+/**
+ * Prints JSXEmptyExpression.
+ */
+
 export function JSXEmptyExpression() {}

src/babel/generation/generators/methods.js

@@ -1,5 +1,9 @@
 import * as t from "../../types";
 
+/**
+ * Prints nodes with params, prints typeParameters, params, and returnType, handles optional params.
+ */
+
 export function _params(node, print) {
   print.plain(node.typeParameters);
   this.push("(");
@@ -16,6 +20,10 @@ export function _params(node, print) {
   }
 }
 
+/**
+ * Prints method-like nodes, prints key, value, and body, handles async, generator, computed, and get or set.
+ */
+
 export function _method(node, print) {
   var value = node.value;
   var kind  = node.kind;
@@ -42,10 +50,14 @@ export function _method(node, print) {
   }
 
   this._params(value, print);
-  this.push(" ");
+  this.space();
   print.plain(value.body);
 }
 
+/**
+ * Prints FunctionExpression, prints id and body, handles async and generator.
+ */
+
 export function FunctionExpression(node, print) {
   if (node.async) this.push("async ");
   this.push("function");
@@ -63,8 +75,17 @@ export function FunctionExpression(node, print) {
   print.plain(node.body);
 }
 
+/**
+ * Alias FunctionExpression printer as FunctionDeclaration.
+ */
+
 export { FunctionExpression as FunctionDeclaration };
 
+/**
+ * Prints ArrowFunctionExpression, prints params and body, handles async.
+ * Leaves out parentheses when single param.
+ */
+
 export function ArrowFunctionExpression(node, print) {
   if (node.async) this.push("async ");
 

src/babel/generation/generators/modules.js

@@ -1,5 +1,9 @@
 import * as t from "../../types";
 
+/**
+ * Prints ImportSpecifier, prints imported and local.
+ */
+
 export function ImportSpecifier(node, print) {
   print.plain(node.imported);
   if (node.local && node.local.name !== node.imported.name) {
@@ -8,14 +12,26 @@ export function ImportSpecifier(node, print) {
   }
 }
 
+/**
+ * Prints ImportDefaultSpecifier, prints local.
+ */
+
 export function ImportDefaultSpecifier(node, print) {
   print.plain(node.local);
 }
 
+/**
+ * Prints ExportDefaultSpecifier, prints exported.
+ */
+
 export function ExportDefaultSpecifier(node, print) {
   print.plain(node.exported);
 }
 
+/**
+ * Prints ExportSpecifier, prints local and exported.
+ */
+
 export function ExportSpecifier(node, print) {
   print.plain(node.local);
   if (node.exported && node.local.name !== node.exported.name) {
@@ -24,11 +40,19 @@ export function ExportSpecifier(node, print) {
   }
 }
 
+/**
+ * Prints ExportNamespaceSpecifier, prints exported.
+ */
+
 export function ExportNamespaceSpecifier(node, print) {
   this.push("* as ");
   print.plain(node.exported);
 }
 
+/**
+ * Prints ExportAllDeclaration, prints exported and source.
+ */
+
 export function ExportAllDeclaration(node, print) {
   this.push("export *");
   if (node.exported) {
@@ -40,16 +64,28 @@ export function ExportAllDeclaration(node, print) {
   this.semicolon();
 }
 
+/**
+ * Prints ExportNamedDeclaration, delegates to ExportDeclaration.
+ */
+
 export function ExportNamedDeclaration(node, print) {
   this.push("export ");
   ExportDeclaration.call(this, node, print);
 }
 
+/**
+ * Prints ExportDefaultDeclaration, delegates to ExportDeclaration.
+ */
+
 export function ExportDefaultDeclaration(node, print) {
   this.push("export default ");
   ExportDeclaration.call(this, node, print);
 }
 
+/**
+ * Prints ExportDeclaration, prints specifiers, declration, and source.
+ */
+
 function ExportDeclaration(node, print) {
   var specifiers = node.specifiers;
 
@@ -87,11 +123,15 @@ function ExportDeclaration(node, print) {
   this.ensureSemicolon();
 }
 
+/**
+ * Prints ImportDeclaration, prints specifiers and source, handles isType.
+ */
+
 export function ImportDeclaration(node, print) {
   this.push("import ");
 
-  if (node.isType) {
-    this.push("type ");
+  if (node.importKind === "type" || node.importKind === "typeof") {
+    this.push(node.importKind + " ");
   }
 
   var specfiers = node.specifiers;
@@ -119,6 +159,10 @@ export function ImportDeclaration(node, print) {
   this.semicolon();
 }
 
+/**
+ * Prints ImportNamespaceSpecifier, prints local.
+ */
+
 export function ImportNamespaceSpecifier(node, print) {
   this.push("* as ");
   print.plain(node.local);

src/babel/generation/generators/statements.js

@@ -1,6 +1,10 @@
 import repeating from "repeating";
 import * as t from "../../types";
 
+/**
+ * Prints WithStatement, prints object and body.
+ */
+
 export function WithStatement(node, print) {
   this.keyword("with");
   this.push("(");
@@ -9,6 +13,10 @@ export function WithStatement(node, print) {
   print.block(node.body);
 }
 
+/**
+ * Prints IfStatement, prints test, consequent, and alternate.
+ */
+
 export function IfStatement(node, print) {
   this.keyword("if");
   this.push("(");
@@ -25,6 +33,10 @@ export function IfStatement(node, print) {
   }
 }
 
+/**
+ * Prints ForStatement, prints init, test, update, and body.
+ */
+
 export function ForStatement(node, print) {
   this.keyword("for");
   this.push("(");
@@ -33,13 +45,13 @@ export function ForStatement(node, print) {
   this.push(";");
 
   if (node.test) {
-    this.push(" ");
+    this.space();
     print.plain(node.test);
   }
   this.push(";");
 
   if (node.update) {
-    this.push(" ");
+    this.space();
     print.plain(node.update);
   }
 
@@ -47,6 +59,10 @@ export function ForStatement(node, print) {
   print.block(node.body);
 }
 
+/**
+ * Prints WhileStatement, prints test and body.
+ */
+
 export function WhileStatement(node, print) {
   this.keyword("while");
   this.push("(");
@@ -55,6 +71,11 @@ export function WhileStatement(node, print) {
   print.block(node.body);
 }
 
+/**
+ * Builds ForIn or ForOf statement printers.
+ * Prints left, right, and body.
+ */
+
 var buildForXStatement = function (op) {
   return function (node, print) {
     this.keyword("for");
@@ -67,9 +88,17 @@ var buildForXStatement = function (op) {
   };
 };
 
+/**
+ * Create ForInStatement and ForOfStatement printers.
+ */
+
 export var ForInStatement = buildForXStatement("in");
 export var ForOfStatement = buildForXStatement("of");
 
+/**
+ * Prints DoWhileStatement, prints body and test.
+ */
+
 export function DoWhileStatement(node, print) {
   this.push("do ");
   print.plain(node.body);
@@ -80,6 +109,11 @@ export function DoWhileStatement(node, print) {
   this.push(");");
 }
 
+/**
+ * Builds continue, return, or break statement printers.
+ * Prints label (or key).
+ */
+
 var buildLabelStatement = function (prefix, key) {
   return function (node, print) {
     this.push(prefix);
@@ -94,16 +128,28 @@ var buildLabelStatement = function (prefix, key) {
   };
 };
 
+/**
+ * Create ContinueStatement, ReturnStatement, and BreakStatement printers.
+ */
+
 export var ContinueStatement = buildLabelStatement("continue");
 export var ReturnStatement   = buildLabelStatement("return", "argument");
 export var BreakStatement    = buildLabelStatement("break");
 
+/**
+ * Prints LabeledStatement, prints label and body.
+ */
+
 export function LabeledStatement(node, print) {
   print.plain(node.label);
   this.push(": ");
   print.plain(node.body);
 }
 
+/**
+ * Prints TryStatement, prints block, handlers, and finalizer.
+ */
+
 export function TryStatement(node, print) {
   this.keyword("try");
   print.plain(node.block);
@@ -125,6 +171,10 @@ export function TryStatement(node, print) {
   }
 }
 
+/**
+ * Prints CatchClause, prints param and body.
+ */
+
 export function CatchClause(node, print) {
   this.keyword("catch");
   this.push("(");
@@ -133,12 +183,20 @@ export function CatchClause(node, print) {
   print.plain(node.body);
 }
 
+/**
+ * Prints ThrowStatement, prints argument.
+ */
+
 export function ThrowStatement(node, print) {
   this.push("throw ");
   print.plain(node.argument);
   this.semicolon();
 }
 
+/**
+ * Prints SwitchStatement, prints discriminant and cases.
+ */
+
 export function SwitchStatement(node, print) {
   this.keyword("switch");
   this.push("(");
@@ -157,6 +215,10 @@ export function SwitchStatement(node, print) {
   this.push("}");
 }
 
+/**
+ * Prints SwitchCase, prints test and consequent.
+ */
+
 export function SwitchCase(node, print) {
   if (node.test) {
     this.push("case ");
@@ -172,10 +234,18 @@ export function SwitchCase(node, print) {
   }
 }
 
+/**
+ * Prints DebuggerStatement.
+ */
+
 export function DebuggerStatement() {
   this.push("debugger;");
 }
 
+/**
+ * Prints VariableDeclaration, prints declarations, handles kind and format.
+ */
+
 export function VariableDeclaration(node, print, parent) {
   this.push(node.kind + " ");
 
@@ -190,22 +260,39 @@ export function VariableDeclaration(node, print, parent) {
     }
   }
 
-  var sep = ",";
+  //
+  // use a pretty separator when we aren't in compact mode, have initializers and don't have retainLines on
+  // this will format declarations like:
+  //
+  //   var foo = "bar", bar = "foo";
+  //
+  // into
+  //
+  //   var foo = "bar",
+  //       bar = "foo";
+  //
+
+  var sep;
   if (!this.format.compact && !this.format.concise && hasInits && !this.format.retainLines) {
-    sep += `\n${repeating(" ", node.kind.length + 1)}`;
-  } else {
-    sep += " ";
+    sep = `,\n${repeating(" ", node.kind.length + 1)}`;
   }
 
+  //
+
   print.list(node.declarations, { separator: sep });
 
   if (t.isFor(parent)) {
+    // don't give semicolons to these nodes since they'll be inserted in the parent generator
     if (parent.left === node || parent.init === node) return;
   }
 
   this.semicolon();
 }
 
+/**
+ * Prints VariableDeclarator, handles id, id.typeAnnotation, and init.
+ */
+
 export function VariableDeclarator(node, print) {
   print.plain(node.id);
   print.plain(node.id.typeAnnotation);

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

@@ -1,12 +1,24 @@
+/**
+ * Prints TaggedTemplateExpression, prints tag and quasi.
+ */
+
 export function TaggedTemplateExpression(node, print) {
   print.plain(node.tag);
   print.plain(node.quasi);
 }
 
+/**
+ * Prints TemplateElement, prints value.
+ */
+
 export function TemplateElement(node) {
   this._push(node.value.raw);
 }
 
+/**
+ * Prints TemplateLiteral, prints quasis, and expressions.
+ */
+
 export function TemplateLiteral(node, print) {
   this.push("`");
 

src/babel/generation/generators/types.js

@@ -1,18 +1,36 @@
 /* eslint quotes: 0 */
 
+import isInteger from "is-integer";
 import * as t from "../../types";
 
+/**
+ * Prints Identifier, prints name.
+ */
+
 export function Identifier(node) {
   this.push(node.name);
 }
 
+/**
+ * Prints RestElement, prints argument.
+ */
+
 export function RestElement(node, print) {
   this.push("...");
   print.plain(node.argument);
 }
 
+/**
+ * Alias RestElement printer as SpreadElement,
+ * and RestElement printer as SpreadProperty.
+ */
+
 export { RestElement as SpreadElement, RestElement as SpreadProperty };
 
+/**
+ * Prints ObjectExpression, prints properties.
+ */
+
 export function ObjectExpression(node, print) {
   var props = node.properties;
 
@@ -29,9 +47,19 @@ export function ObjectExpression(node, print) {
   }
 }
 
+/**
+ * Alias ObjectExpression printer as ObjectPattern.
+ */
+
 export { ObjectExpression as ObjectPattern };
 
+/**
+ * Prints Property, prints decorators, key, and value, handles kind, computed, and shorthand.
+ */
+
 export function Property(node, print) {
+  print.list(node.decorators, { separator: "" });
+
   if (node.method || node.kind === "get" || node.kind === "set") {
     this._method(node, print);
   } else {
@@ -63,6 +91,10 @@ export function Property(node, print) {
   }
 }
 
+/**
+ * Prints ArrayExpression, prints elements.
+ */
+
 export function ArrayExpression(node, print) {
   var elems = node.elements;
   var len   = elems.length;
@@ -79,7 +111,7 @@ export function ArrayExpression(node, print) {
       // both (all) of the holes.
       this.push(",");
     } else {
-      if (i > 0) this.push(" ");
+      if (i > 0) this.space();
       print.plain(elem);
       if (i < len - 1) this.push(",");
     }
@@ -88,16 +120,43 @@ export function ArrayExpression(node, print) {
   this.push("]");
 }
 
+/**
+ * Alias ArrayExpression printer as ArrayPattern.
+ */
+
 export { ArrayExpression as ArrayPattern };
 
-export function Literal(node) {
+/**
+ * RegExp for testing scientific notation in literals.
+ */
+
+const SCIENTIFIC_NOTATION = /e/i;
+
+/**
+ * Prints Literal, prints value, regex, raw, handles val type.
+ */
+
+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) {
@@ -107,6 +166,10 @@ export function Literal(node) {
   }
 }
 
+/**
+ * Prints string literals, handles format.
+ */
+
 export function _stringLiteral(val) {
   val = JSON.stringify(val);
 
@@ -116,9 +179,16 @@ export function _stringLiteral(val) {
   });
 
   if (this.format.quotes === "single") {
+    // remove double quotes
     val = val.slice(1, -1);
+
+    // unescape double quotes
     val = val.replace(/\\"/g, '"');
+
+    // escape single quotes
     val = val.replace(/'/g, "\\'");
+
+    // add single quotes
     val = `'${val}'`;
   }
 

src/babel/generation/index.js

@@ -11,6 +11,11 @@ import each from "lodash/collection/each";
 import n from "./node";
 import * as t from "../types";
 
+/**
+ * Babel's code generator, turns an ast into code, maintaining sourcemaps,
+ * user preferences, and valid output.
+ */
+
 class CodeGenerator {
   constructor(ast, opts, code) {
     opts = opts || {};
@@ -27,6 +32,13 @@ class CodeGenerator {
     this.buffer     = new Buffer(this.position, this.format);
   }
 
+  /**
+   * Normalize generator options, setting defaults.
+   *
+   * - Detects code indentation.
+   * - If `opts.compact = "auto"` and the code is over 100KB, `compact` will be set to `true`.
+   */
+
   static normalizeOptions(code, opts, tokens) {
     var style = "  ";
     if (code) {
@@ -57,6 +69,9 @@ class CodeGenerator {
     return format;
   }
 
+  /**
+   * Determine if input code uses more single or double quotes.
+   */
   static findCommonStringDelimiter(code, tokens) {
     var occurences = {
       single: 0,
@@ -79,7 +94,6 @@ class CodeGenerator {
       checked++;
       if (checked >= 3) break;
     }
-
     if (occurences.single > occurences.double) {
       return "single";
     } else {
@@ -87,6 +101,10 @@ class CodeGenerator {
     }
   }
 
+  /**
+   * All node generators.
+   */
+
   static generators = {
     templateLiterals: require("./generators/template-literals"),
     comprehensions:   require("./generators/comprehensions"),
@@ -101,6 +119,12 @@ class CodeGenerator {
     jsx:              require("./generators/jsx")
   };
 
+  /**
+   * Generate code and sourcemap from ast.
+   *
+   * Appends comments that weren't attached to any node to the end of the generated output.
+   */
+
   generate() {
     var ast = this.ast;
 
@@ -120,16 +144,23 @@ class CodeGenerator {
     };
   }
 
+  /**
+   * Build NodePrinter.
+   */
+
   buildPrint(parent) {
     return new NodePrinter(this, parent);
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   catchUp(node, parent, leftParenPrinted) {
     // catch up to this nodes newline if we're behind
     if (node.loc && this.format.retainLines && this.buffer.buf) {
       var needsParens = false;
-      if (!leftParenPrinted && parent &&
-          this.position.line < node.loc.start.line && t.isTerminatorless(parent)) {
+      if (!leftParenPrinted && parent && this.position.line < node.loc.start.line && t.isTerminatorless(parent)) {
         needsParens = true;
         this._push("(");
       }
@@ -141,6 +172,10 @@ class CodeGenerator {
     return false;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   _printNewline(leading, node, parent, opts) {
     if (!opts.statement && !n.isUserWhitespacable(node, parent)) {
       return;
@@ -171,6 +206,10 @@ class CodeGenerator {
     this.newline(lines);
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   print(node, parent, opts = {}) {
     if (!node) return;
 
@@ -220,6 +259,10 @@ class CodeGenerator {
     }
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   printJoin(print, nodes, opts = {}) {
     if (!nodes || !nodes.length) return;
 
@@ -249,6 +292,10 @@ class CodeGenerator {
     if (opts.indent) this.dedent();
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   printAndIndentOnComments(print, node) {
     var indent = !!node.leadingComments;
     if (indent) this.indent();
@@ -256,6 +303,10 @@ class CodeGenerator {
     if (indent) this.dedent();
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   printBlock(print, node) {
     if (t.isEmptyStatement(node)) {
       this.semicolon();
@@ -265,6 +316,10 @@ class CodeGenerator {
     }
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   generateComment(comment) {
     var val = comment.value;
     if (comment.type === "CommentLine") {
@@ -275,14 +330,26 @@ class CodeGenerator {
     return val;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   printTrailingComments(node, parent) {
     this._printComments(this.getComments("trailingComments", node, parent));
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   printLeadingComments(node, parent) {
     this._printComments(this.getComments("leadingComments", node, parent));
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   getComments(key, node, parent) {
     if (t.isExpressionStatement(parent)) {
       return [];
@@ -302,10 +369,18 @@ class CodeGenerator {
     return comments;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   _getComments(key, node) {
     return (node && node[key]) || [];
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   _printComments(comments) {
     if (this.format.compact) return;
     if (!this.format.comments) return;
@@ -344,7 +419,7 @@ class CodeGenerator {
 
       //
       if (comment.type === "CommentBlock" && this.format.indent.adjustMultilineComment) {
-        var offset = comment.loc.start.column;
+        var offset = comment.loc && comment.loc.start.column;
         if (offset) {
           var newlineRegex = new RegExp("\\n\\s{1," + offset + "}", "g");
           val = val.replace(newlineRegex, "\n");
@@ -373,16 +448,28 @@ class CodeGenerator {
   }
 }
 
+/**
+ * [Please add a description.]
+ */
+
 each(Buffer.prototype, function (fn, key) {
   CodeGenerator.prototype[key] = function () {
     return fn.apply(this.buffer, arguments);
   };
 });
 
+/**
+ * [Please add a description.]
+ */
+
 each(CodeGenerator.generators, function (generator) {
   extend(CodeGenerator.prototype, generator);
 });
 
+/**
+ * [Please add a description.]
+ */
+
 module.exports = function (ast, opts, code) {
   var gen = new CodeGenerator(ast, opts, code);
   return gen.generate();

src/babel/generation/node/index.js

@@ -4,6 +4,16 @@ import each from "lodash/collection/each";
 import some from "lodash/collection/some";
 import * as t from "../../types";
 
+/**
+ * Test if node matches a set of type-matcher pairs.
+ * @example
+ * find({
+ *   VariableDeclaration(node, parent) {
+ *     return true;
+ *   }
+ * }, node, parent);
+ */
+
 var find = function (obj, node, parent) {
   if (!obj) return;
   var result;
@@ -22,16 +32,28 @@ var find = function (obj, node, parent) {
   return result;
 };
 
+/**
+ * Whitespace and Parenthesis related methods for nodes.
+ */
+
 export default class Node {
   constructor(node, parent) {
     this.parent = parent;
     this.node   = node;
   }
 
+  /**
+   * Test if `node` can have whitespace set by the user.
+   */
+
   static isUserWhitespacable(node) {
     return t.isUserWhitespacable(node);
   }
 
+  /**
+   * Test if a `node` requires whitespace.
+   */
+
   static needsWhitespace(node, parent, type) {
     if (!node) return 0;
 
@@ -54,14 +76,26 @@ export default class Node {
     return (linesInfo && linesInfo[type]) || 0;
   }
 
+  /**
+   * Test if a `node` requires whitespace before it.
+   */
+
   static needsWhitespaceBefore(node, parent) {
     return Node.needsWhitespace(node, parent, "before");
   }
 
+  /**
+   * Test if a `note` requires whitespace after it.
+   */
+
   static needsWhitespaceAfter(node, parent) {
     return Node.needsWhitespace(node, parent, "after");
   }
 
+  /**
+   * Test if a `node` needs parentheses around it.
+   */
+
   static needsParens(node, parent) {
     if (!parent) return false;
 
@@ -77,6 +111,10 @@ export default class Node {
     return find(parens, node, parent);
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   static needsParensNoLineTerminator(node, parent) {
     if (!parent) return false;
 
@@ -89,6 +127,10 @@ export default class Node {
   }
 }
 
+/**
+ * Add all static methods from `Node` to `Node.prototype`.
+ */
+
 each(Node, function (fn, key) {
   Node.prototype[key] = function () {
     // Avoid leaking arguments to prevent deoptimization

src/babel/generation/node/parentheses.js

@@ -1,6 +1,12 @@
 import each from "lodash/collection/each";
 import * as t from "../../types";
 
+/**
+ * Create a mapping of operators to precendence.
+ *
+ * @example
+ * { "==": 6, "+": 9 }
+ */
 const PRECEDENCE = {};
 
 each([
@@ -21,12 +27,24 @@ each([
   });
 });
 
+/**
+ * Test if NullableTypeAnnotation needs parentheses.
+ */
+
 export function NullableTypeAnnotation(node, parent) {
   return t.isArrayTypeAnnotation(parent);
 }
 
+/**
+ * Alias NullableTypeAnnotation test as FunctionTypeAnnotation.
+ */
+
 export { NullableTypeAnnotation as FunctionTypeAnnotation };
 
+/**
+ * Test if UpdateExpression needs parentheses.
+ */
+
 export function UpdateExpression(node, parent) {
   if (t.isMemberExpression(parent) && parent.object === node) {
     // (foo++).test()
@@ -34,6 +52,10 @@ export function UpdateExpression(node, parent) {
   }
 }
 
+/**
+ * Test if ObjectExpression needs parentheses.
+ */
+
 export function ObjectExpression(node, parent) {
   if (t.isExpressionStatement(parent)) {
     // ({ foo: "bar" });
@@ -48,6 +70,10 @@ export function ObjectExpression(node, parent) {
   return false;
 }
 
+/**
+ * Test if Binary needs parentheses.
+ */
+
 export function Binary(node, parent) {
   if ((t.isCallExpression(parent) || t.isNewExpression(parent)) && parent.callee === node) {
     return true;
@@ -78,6 +104,10 @@ export function Binary(node, parent) {
   }
 }
 
+/**
+ * Test if BinaryExpression needs parentheses.
+ */
+
 export function BinaryExpression(node, parent) {
   if (node.operator === "in") {
     // var i = (1 in []);
@@ -92,6 +122,10 @@ export function BinaryExpression(node, parent) {
   }
 }
 
+/**
+ * Test if SequenceExpression needs parentheses.
+ */
+
 export function SequenceExpression(node, parent) {
   if (t.isForStatement(parent)) {
     // Although parentheses wouldn't hurt around sequence
@@ -110,6 +144,10 @@ export function SequenceExpression(node, parent) {
   return true;
 }
 
+/**
+ * Test if YieldExpression needs parentheses.
+ */
+
 export function YieldExpression(node, parent) {
   return t.isBinary(parent) ||
          t.isUnaryLike(parent) ||
@@ -120,14 +158,26 @@ export function YieldExpression(node, parent) {
          t.isYieldExpression(parent);
 }
 
+/**
+ * Test if ClassExpression needs parentheses.
+ */
+
 export function ClassExpression(node, parent) {
   return t.isExpressionStatement(parent);
 }
 
+/**
+ * Test if UnaryLike needs parentheses.
+ */
+
 export function UnaryLike(node, parent) {
   return t.isMemberExpression(parent) && parent.object === node;
 }
 
+/**
+ * Test if FunctionExpression needs parentheses.
+ */
+
 export function FunctionExpression(node, parent) {
   // function () {};
   if (t.isExpressionStatement(parent)) {
@@ -145,6 +195,10 @@ export function FunctionExpression(node, parent) {
   }
 }
 
+/**
+ * Test if ConditionalExpression needs parentheses.
+ */
+
 export function ConditionalExpression(node, parent) {
   if (t.isUnaryLike(parent)) {
     return true;
@@ -171,6 +225,10 @@ export function ConditionalExpression(node, parent) {
   return false;
 }
 
+/**
+ * Test if AssignmentExpression needs parentheses.
+ */
+
 export function AssignmentExpression(node) {
   if (t.isObjectPattern(node.left)) {
     return true;

src/babel/generation/node/printer.js

@@ -1,31 +1,63 @@
+/**
+ * Printer for nodes, needs a `generator` and a `parent`.
+ */
+
 export default class NodePrinter {
   constructor(generator, parent) {
     this.generator = generator;
     this.parent = parent;
   }
 
+  /**
+   * Print a plain node.
+   */
+
   plain(node, opts) {
     return this.generator.print(node, this.parent, opts);
   }
 
+  /**
+   * Print a sequence of nodes as statements.
+   */
+
   sequence(nodes, opts = {}) {
     opts.statement = true;
     return this.generator.printJoin(this, nodes, opts);
   }
 
+  /**
+   * Print a sequence of nodes as expressions.
+   */
+
   join(nodes, opts) {
     return this.generator.printJoin(this, nodes, opts);
   }
 
+  /**
+   * Print a list of nodes, with a customizable separator (defaults to ",").
+   */
+
   list(items, opts = {}) {
-    if (opts.separator == null) opts.separator = ", ";
+    if (opts.separator == null) {
+      opts.separator = ",";
+      if (!this.generator.format.compact) opts.separator += " ";
+    }
+
     return this.join(items, opts);
   }
 
+  /**
+   * Print a block-like node.
+   */
+
   block(node) {
     return this.generator.printBlock(this, node);
   }
 
+  /**
+   * Print node and indent comments.
+   */
+
   indentOnComments(node) {
     return this.generator.printAndIndentOnComments(this, node);
   }

src/babel/generation/node/whitespace.js

@@ -3,6 +3,14 @@ import each from "lodash/collection/each";
 import map from "lodash/collection/map";
 import * as t from "../../types";
 
+/**
+ * Crawl a node to test if it contains a CallExpression, a Function, or a Helper.
+ *
+ * @example
+ * crawl(node)
+ * // { hasCall: false, hasFunction: true, hasHelper: false }
+ */
+
 function crawl(node, state = {}) {
   if (t.isMemberExpression(node)) {
     crawl(node.object, state);
@@ -22,6 +30,10 @@ function crawl(node, state = {}) {
   return state;
 }
 
+/**
+ * Test if a node is or has a helper.
+ */
+
 function isHelper(node) {
   if (t.isMemberExpression(node)) {
     return isHelper(node.object) || isHelper(node.property);
@@ -36,12 +48,25 @@ function isHelper(node) {
   }
 }
 
+/**
+ * [Please add a description.]
+ */
+
 function isType(node) {
   return t.isLiteral(node) || t.isObjectExpression(node) || t.isArrayExpression(node) ||
          t.isIdentifier(node) || t.isMemberExpression(node);
 }
 
+/**
+ * Tests for node types that need whitespace.
+ */
+
 exports.nodes = {
+
+  /**
+   * Test if AssignmentExpression needs whitespace.
+   */
+
   AssignmentExpression(node) {
     var state = crawl(node.right);
     if ((state.hasCall && state.hasHelper) || state.hasFunction) {
@@ -52,12 +77,20 @@ exports.nodes = {
     }
   },
 
+  /**
+   * Test if SwitchCase needs whitespace.
+   */
+
   SwitchCase(node, parent) {
     return {
       before: node.consequent.length || parent.cases[0] === node
     };
   },
 
+  /**
+   * Test if LogicalExpression needs whitespace.
+   */
+
   LogicalExpression(node) {
     if (t.isFunction(node.left) || t.isFunction(node.right)) {
       return {
@@ -66,6 +99,10 @@ exports.nodes = {
     }
   },
 
+  /**
+   * Test if Literal needs whitespace.
+   */
+
   Literal(node) {
     if (node.value === "use strict") {
       return {
@@ -74,6 +111,10 @@ exports.nodes = {
     }
   },
 
+  /**
+   * Test if CallExpression needs whitespace.
+   */
+
   CallExpression(node) {
     if (t.isFunction(node.callee) || isHelper(node)) {
       return {
@@ -83,6 +124,10 @@ exports.nodes = {
     }
   },
 
+  /**
+   * Test if VariableDeclaration needs whitespace.
+   */
+
   VariableDeclaration(node) {
     for (var i = 0; i < node.declarations.length; i++) {
       var declar = node.declarations[i];
@@ -102,6 +147,10 @@ exports.nodes = {
     }
   },
 
+  /**
+   * Test if IfStatement needs whitespace.
+   */
+
   IfStatement(node) {
     if (t.isBlockStatement(node.consequent)) {
       return {
@@ -112,6 +161,10 @@ exports.nodes = {
   }
 };
 
+/**
+ * Test if Property or SpreadProperty needs whitespace.
+ */
+
 exports.nodes.Property =
 exports.nodes.SpreadProperty = function (node, parent) {
   if (parent.properties[0] === node) {
@@ -121,20 +174,41 @@ exports.nodes.SpreadProperty = function (node, parent) {
   }
 };
 
+/**
+ * Returns lists from node types that need whitespace.
+ */
+
 exports.list = {
+
+  /**
+   * Return VariableDeclaration declarations init properties.
+   */
+
   VariableDeclaration(node) {
     return map(node.declarations, "init");
   },
 
+  /**
+   * Return VariableDeclaration elements.
+   */
+
   ArrayExpression(node) {
     return node.elements;
   },
 
+  /**
+   * Return VariableDeclaration properties.
+   */
+
   ObjectExpression(node) {
     return node.properties;
   }
 };
 
+/**
+ * Add whitespace tests for nodes and their aliases.
+ */
+
 each({
   Function: true,
   Class: true,

src/babel/generation/position.js

@@ -1,9 +1,17 @@
+/**
+ * Track current position in code generation.
+ */
+
 export default class Position {
   constructor() {
     this.line = 1;
     this.column = 0;
   }
 
+  /**
+   * Push a string to the current position, mantaining the current line and column.
+   */
+
   push(str) {
     for (var i = 0; i < str.length; i++) {
       if (str[i] === "\n") {
@@ -15,6 +23,10 @@ export default class Position {
     }
   }
 
+  /**
+   * Unshift a string from the current position, mantaining the current line and column.
+   */
+
   unshift(str) {
     for (var i = 0; i < str.length; i++) {
       if (str[i] === "\n") {

src/babel/generation/source-map.js

@@ -1,6 +1,10 @@
 import sourceMap from "source-map";
 import * as t from "../types";
 
+/**
+ * Build a sourcemap.
+ */
+
 export default class SourceMap {
   constructor(position, opts, code) {
     this.position = position;
@@ -18,6 +22,10 @@ export default class SourceMap {
     }
   }
 
+  /**
+   * Get the sourcemap.
+   */
+
   get() {
     var map = this.map;
     if (map) {
@@ -27,6 +35,10 @@ export default class SourceMap {
     }
   }
 
+  /**
+   * Mark a node's generated position, and add it to the sourcemap.
+   */
+
   mark(node, type) {
     var loc = node.loc;
     if (!loc) return; // no location info

src/babel/generation/whitespace.js

@@ -18,6 +18,10 @@ function getLookupIndex(i, base, max) {
   return i;
 }
 
+/**
+ * Get whitespace around tokens.
+ */
+
 export default class Whitespace {
   constructor(tokens) {
     this.tokens = tokens;
@@ -34,6 +38,10 @@ export default class Whitespace {
     this._lastFoundIndex = 0;
   }
 
+  /**
+   * Count all the newlines before a node.
+   */
+
   getNewlinesBefore(node) {
     var startToken;
     var endToken;
@@ -57,6 +65,10 @@ export default class Whitespace {
     return this.getNewlinesBetween(startToken, endToken);
   }
 
+  /**
+   * Count all the newlines after a node.
+   */
+
   getNewlinesAfter(node) {
     var startToken;
     var endToken;
@@ -91,6 +103,10 @@ export default class Whitespace {
     }
   }
 
+  /**
+   * Count all the newlines between two tokens.
+   */
+
   getNewlinesBetween(startToken, endToken) {
     if (!endToken || !endToken.loc) return 0;
 

src/babel/helpers/README.md

@@ -0,0 +1,4 @@
+## Helpers
+
+Utilities for Babel, which is just another way to say "helpers", but I wrote it
+anyways, so– deal with it.

src/babel/helpers/code-frame.js

@@ -4,6 +4,10 @@ import jsTokens from "js-tokens";
 import esutils from "esutils";
 import chalk from "chalk";
 
+/**
+ * Chalk styles for token types.
+ */
+
 var defs = {
   string:     chalk.red,
   punctuator: chalk.bold,
@@ -17,8 +21,16 @@ var defs = {
   invalid:    chalk.inverse
 };
 
+/**
+ * RegExp to test for newlines in terminal.
+ */
+
 const NEWLINE = /\r\n|[\n\r\u2028\u2029]/;
 
+/**
+ * Get the type of token, specifying punctuator type.
+ */
+
 function getTokenType(match) {
   var token = jsTokens.matchToToken(match);
   if (token.type === "name" && esutils.keyword.isReservedWordES6(token.value)) {
@@ -42,6 +54,10 @@ function getTokenType(match) {
   return token.type;
 }
 
+/**
+ * Highlight `text`.
+ */
+
 function highlight(text) {
   return text.replace(jsTokens, function (...args) {
     var type = getTokenType(args);
@@ -54,6 +70,10 @@ function highlight(text) {
   });
 }
 
+/**
+ * Create a code frame, adding line numbers, code highlighting, and pointing to a given position.
+ */
+
 export default function (lines: number, lineNumber: number, colNumber: number, opts = {}): string {
   colNumber = Math.max(colNumber, 0);
 
@@ -79,9 +99,11 @@ 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/helpers/merge.js

@@ -1,10 +1,14 @@
 import merge from "lodash/object/merge";
 
+/**
+ * Merge options.
+ */
+
 export default function (dest, src) {
   if (!dest || !src) return;
 
-  return merge(dest, src, function(a, b) {
-    if (Array.isArray(a)) {
+  return merge(dest, src, function (a, b) {
+    if (b && Array.isArray(a)) {
       var c = a.slice(0);
       for (var v of b) {
         if (a.indexOf(v) < 0) {

src/babel/helpers/normalize-ast.js

@@ -1,5 +1,11 @@
 import * as t from "../types";
 
+/**
+ * Normalize an AST.
+ *
+ * - Wrap `Program` node with a `File` node.
+ */
+
 export default function (ast, comments, tokens) {
   if (ast && ast.type === "Program") {
     return t.file(ast, comments || [], tokens || []);

src/babel/helpers/object.js

@@ -1,3 +1,7 @@
+/**
+ * Create an object with a `null` prototype.
+ */
+
 export default function () {
   return Object.create(null);
 }

src/babel/helpers/parse.js

@@ -2,6 +2,10 @@ import normalizeAst from "./normalize-ast";
 import estraverse from "estraverse";
 import * as acorn from "../../acorn";
 
+/**
+ * Parse `code` with normalized options, collecting tokens and comments.
+ */
+
 export default function (code, opts = {}) {
   var commentsAndTokens = [];
   var comments          = [];
@@ -21,11 +25,17 @@ export default function (code, opts = {}) {
     ranges:                      true
   };
 
+  /**
+   * Collect all tokens.
+   */
   parseOpts.onToken = function (token) {
     tokens.push(token);
     commentsAndTokens.push(token);
   };
 
+  /**
+   * Collection all comments.
+   */
   parseOpts.onComment = function (block, text, start, end, startLoc, endLoc) {
     var comment = {
       type: block ? "CommentBlock" : "CommentLine",

src/babel/messages.js

@@ -1,30 +1,37 @@
 import * as util from  "util";
 
+/**
+ * Mapping of messages to be used in Babel.
+ * Messages can include $0-style placeholders.
+ */
+
 export const MESSAGES = {
-  tailCallReassignmentDeopt: "Function reference has been reassigned so it's probably be dereferenced so we can't optimise this with confidence",
+  tailCallReassignmentDeopt: "Function reference has been reassigned, so it will probably be dereferenced, therefore we can't optimise this with confidence",
   JSXNamespacedTags: "Namespace tags are not supported. ReactJSX is not XML.",
   classesIllegalBareSuper: "Illegal use of bare super",
   classesIllegalSuperCall: "Direct super call is illegal in non-constructor, use super.$1() instead",
-  classesIllegalConstructorKind: "Illegal kind for constructor method",
   scopeDuplicateDeclaration: "Duplicate declaration $1",
-  undeclaredVariable: "Reference to undeclared variable $1",
-  undeclaredVariableSuggestion: "Reference to undeclared variable $1 - did you mean $2?",
-  settersInvalidParamLength: "Setters must have exactly one parameter",
   settersNoRest: "Setters aren't allowed to have a rest",
   noAssignmentsInForHead: "No assignments allowed in for-in/of head",
-  expectedMemberExpressionOrIdentifier: "Expected type MemeberExpression or Identifier",
+  expectedMemberExpressionOrIdentifier: "Expected type MemberExpression or Identifier",
   invalidParentForThisNode: "We don't know how to handle this node within the current parent - please open an issue",
   readOnly: "$1 is read-only",
-  modulesIllegalExportName: "Illegal export $1",
   unknownForHead: "Unknown node type $1 in ForStatement",
   didYouMean: "Did you mean $1?",
   codeGeneratorDeopt: "Note: The code generator has deoptimised the styling of $1 as it exceeds the max of $2.",
   missingTemplatesDirectory: "no templates directory - this is most likely the result of a broken `npm publish`. Please report to https://github.com/babel/babel/issues",
   unsupportedOutputType: "Unsupported output type $1",
   illegalMethodName: "Illegal method name $1",
-  lostTrackNodePath: "We lost track of this nodes position, likely because the AST was directly manipulated",
+  lostTrackNodePath: "We lost track of this node's position, likely because the AST was directly manipulated",
 
-  traverseNeedsParent: "Must pass a scope and parentPath unless traversing a Program/File got a $1 node",
+  modulesIllegalExportName: "Illegal export $1",
+  modulesDuplicateDeclarations: "Duplicate module declarations with the same source but in different scopes",
+
+  undeclaredVariable: "Reference to undeclared variable $1",
+  undeclaredVariableType: "Referencing a type alias outside of a type annotation",
+  undeclaredVariableSuggestion: "Reference to undeclared variable $1 - did you mean $2?",
+
+  traverseNeedsParent: "You must pass a scope and parentPath unless traversing a Program/File got a $1 node",
   traverseVerifyRootFunction: "You passed `traverse()` a function when it expected a visitor object, are you sure you didn't mean `{ enter: Function }`?",
   traverseVerifyVisitorProperty: "You passed `traverse()` a visitor object with the property $1 that has the invalid property $2",
   traverseVerifyNodeType: "You gave us a visitor for the node type $1 but it's not a valid type",
@@ -32,24 +39,44 @@ 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 than what is performing the transformation.",
+
+  pluginInvalidProperty: "Plugin $1 provided an invalid property of $2.",
+  pluginInvalidPropertyVisitor: `Define your visitor methods inside a \`visitor\` property like so:
+
+  new Plugin("foobar", {
+    visitor: {
+      // define your visitor methods here!
+    }
+  });
+`
 };
 
-export function get(key: String, ...args) {
+/**
+ * Get a message with $0 placeholders replaced by arguments.
+ */
+
+export function get(key: string, ...args): string {
   var msg = MESSAGES[key];
   if (!msg) throw new ReferenceError(`Unknown message ${JSON.stringify(key)}`);
 
+  // stringify args
   args = parseArgs(args);
 
+  // replace $0 placeholders with args
   return msg.replace(/\$(\d+)/g, function (str, i) {
     return args[--i];
   });
 }
 
-export function parseArgs(args: Array<any>) {
+/**
+ * Stingify arguments to be used inside messages.
+ */
+
+export function parseArgs(args: Array<any>): Array<string> {
   return args.map(function (val) {
     if (val != null && val.inspect) {
       return val.inspect();

src/babel/patch.js

@@ -1,81 +1,7 @@
 import estraverse from "estraverse";
 import extend from "lodash/object/extend";
-import types from "ast-types";
 import * as t from "./types";
 
 // estraverse
 
 extend(estraverse.VisitorKeys, t.VISITOR_KEYS);
-
-// regenerator/ast-types
-
-var def = types.Type.def;
-var or  = types.Type.or;
-
-//def("File")
-//  .bases("Node")
-//  .build("program")
-//  .field("program", def("Program"));
-
-def("AssignmentPattern")
-  .bases("Pattern")
-  .build("left", "right")
-  .field("left", def("Pattern"))
-  .field("right", def("Expression"));
-
-def("RestElement")
-  .bases("Pattern")
-  .build("argument")
-  .field("argument", def("expression"));
-
-def("DoExpression")
-  .bases("Expression")
-  .build("body")
-  .field("body", [def("Statement")]);
-
-def("Super")
-  .bases("Expression");
-
-def("ExportDefaultDeclaration")
-  .bases("Declaration")
-  .build("declaration")
-  .field("declaration", or(
-    def("Declaration"),
-    def("Expression"),
-    null
-  ));
-
-def("ExportNamedDeclaration")
-  .bases("Declaration")
-  .build("declaration")
-  .field("declaration", or(
-    def("Declaration"),
-    def("Expression"),
-    null
-  ))
-  .field("specifiers", [or(
-    def("ExportSpecifier")
-  )])
-  .field("source", or(def("ModuleSpecifier"), null));
-
-def("ExportNamespaceSpecifier")
-  .bases("Specifier")
-  .field("exported", def("Identifier"));
-
-def("ExportDefaultSpecifier")
-  .bases("Specifier")
-  .field("exported", def("Identifier"));
-
-def("ExportAllDeclaration")
-  .bases("Declaration")
-  .build("exported", "source")
-  .field("exported", def("Identifier"))
-  .field("source", def("Literal"));
-
-def("BindExpression")
-  .bases("Expression")
-  .build("object", "callee")
-  .field("object", or(def("Expression"), null))
-  .field("callee", def("Expression"));
-
-types.finalize();

src/babel/tools/README.md

@@ -0,0 +1,15 @@
+## Tools
+
+> This directory is best browsed while listening to
+> https://www.youtube.com/watch?v=hglVqACd1C8.
+
+### Protect Babel
+
+The protect script seen here is to throw errors if someone ever tries to
+include internal babel files in their script. If you need something to be
+exposed, you should ask for it, not try to hack your way into getting it.
+
+### External Helpers
+
+You'll also find the script for building the external helpers file, this is
+the Babel "runtime" where all helper functions go instead of the top of a file.

src/babel/tools/build-external-helpers.js

@@ -5,6 +5,10 @@ import File from "../transformation/file";
 import each from "lodash/collection/each";
 import * as t from "../types";
 
+/**
+ * [Please add a description.]
+ */
+
 function buildGlobal(namespace, builder) {
   var body      = [];
   var container = t.functionExpression(null, [t.identifier("global")], t.blockStatement(body));
@@ -22,6 +26,10 @@ function buildGlobal(namespace, builder) {
   return tree;
 }
 
+/**
+ * [Please add a description.]
+ */
+
 function buildUmd(namespace, builder) {
   var body = [];
   body.push(t.variableDeclaration("var", [
@@ -41,6 +49,10 @@ function buildUmd(namespace, builder) {
   return t.program([container]);
 }
 
+/**
+ * [Please add a description.]
+ */
+
 function buildVar(namespace, builder) {
   var body = [];
   body.push(t.variableDeclaration("var", [
@@ -50,6 +62,10 @@ function buildVar(namespace, builder) {
   return t.program(body);
 }
 
+/**
+ * [Please add a description.]
+ */
+
 function buildHelpers(body, namespace, whitelist) {
   each(File.helpers, function (name) {
     if (whitelist && whitelist.indexOf(name) === -1) return;
@@ -61,6 +77,10 @@ function buildHelpers(body, namespace, whitelist) {
   });
 }
 
+/**
+ * [Please add a description.]
+ */
+
 export default function (whitelist, outputType = "global") {
   var namespace = t.identifier("babelHelpers");
 

src/babel/tools/protect.js

@@ -0,0 +1,14 @@
+import path from "path";
+
+var root = path.resolve(__dirname, "../../../");
+
+/**
+ * Protect Babel internals from being hotlinked by other tools.
+ * Sorry, not sorry.
+ */
+
+export default function (module) {
+  if (module.parent && module.parent.filename.indexOf(root) !== 0) {
+    throw new Error("Don't hotlink internal Babel files.");
+  }
+}

src/babel/tools/resolve-rc.js

@@ -1,59 +0,0 @@
-import stripJsonComments from "strip-json-comments";
-import merge from "../helpers/merge";
-import path from "path";
-import fs from "fs";
-
-var cache = {};
-var jsons = {};
-
-function exists(filename) {
-  if (!fs.existsSync) return false;
-
-  var cached = cache[filename];
-  if (cached != null) return cached;
-  return cache[filename] = fs.existsSync(filename);
-}
-
-export default function (loc, opts = {}) {
-  var rel = ".babelrc";
-
-  if (!opts.babelrc) {
-    opts.babelrc = [];
-  }
-
-  function find(start, rel) {
-    var file = path.join(start, rel);
-
-    if (opts.babelrc.indexOf(file) >= 0) {
-      return;
-    }
-
-    if (exists(file)) {
-      var content = fs.readFileSync(file, "utf8");
-      var json;
-
-      try {
-        json = jsons[content] = jsons[content] || JSON.parse(stripJsonComments(content));
-      } catch (err) {
-        err.message = `${file}: ${err.message}`;
-        throw err;
-      }
-
-      opts.babelrc.push(file);
-
-      if (json.breakConfig) return;
-      merge(opts, json);
-    }
-
-    var up = path.dirname(start);
-    if (up !== start) { // root
-      find(up, rel);
-    }
-  }
-
-  if (opts.babelrc.indexOf(loc) < 0 && opts.breakConfig !== true) {
-    find(loc, rel);
-  }
-
-  return opts;
-}

src/babel/transformation/README.md

@@ -0,0 +1,3 @@
+## Transformation
+
+This is the Transformation directory.

src/babel/transformation/file/README.md

@@ -0,0 +1,3 @@
+## File Transformation
+
+This is the File Transformation directory.

src/babel/transformation/file/index.js

@@ -1,29 +1,28 @@
 import convertSourceMap from "convert-source-map";
-import * as optionParsers from "./option-parsers";
 import moduleFormatters from "../modules";
+import OptionManager from "./options/option-manager";
 import PluginManager from "./plugin-manager";
 import shebangRegex from "shebang-regex";
 import NodePath from "../../traversal/path";
-import Transformer from "../transformer";
 import isFunction from "lodash/lang/isFunction";
-import isAbsolute from "path-is-absolute";
-import resolveRc from "../../tools/resolve-rc";
 import sourceMap from "source-map";
 import generate from "../../generation";
 import codeFrame from "../../helpers/code-frame";
 import defaults from "lodash/object/defaults";
 import includes from "lodash/collection/includes";
 import traverse from "../../traversal";
-import 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";
 
+/**
+ * [Please add a description.]
+ */
+
 export default class File {
   constructor(opts = {}, pipeline) {
     this.transformerDependencies = {};
@@ -35,17 +34,32 @@ export default class File {
     this.declarations = {};
     this.usedHelpers  = {};
     this.dynamicData  = {};
-    this.metadata     = {};
     this.data         = {};
 
+    this.metadata = {
+      modules: {
+        imports: [],
+        exports: {
+          exported: [],
+          specifiers: []
+        }
+      }
+    };
+
     this.pipeline = pipeline;
     this.log      = new Logger(this, opts.filename || "unknown");
-    this.opts     = this.normalizeOptions(opts);
+    this.opts     = this.initOptions(opts);
     this.ast      = {};
 
     this.buildTransformers();
+
+    this.hub = new Hub(this);
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   static helpers = [
     "inherits",
     "defaults",
@@ -80,68 +94,27 @@ export default class File {
     "instanceof",
 
     // legacy
-    "interop-require",
+    "interop-require"
   ];
 
+  /**
+   * [Please add a description.]
+   */
+
   static soloHelpers = [];
 
-  static options = require("./options");
 
-  normalizeOptions(opts: Object) {
-    opts = assign({}, opts);
+  /**
+   * [Please add a description.]
+   */
 
-    if (opts.filename) {
-      var rcFilename = opts.filename;
-      if (!isAbsolute(rcFilename)) rcFilename = path.join(process.cwd(), rcFilename);
-      opts = resolveRc(rcFilename, opts);
-    }
-
-    //
-
-    for (let key in opts) {
-      if (key[0] === "_") continue;
-
-      let option = File.options[key];
-      if (!option) this.log.error(`Unknown option: ${key}`, ReferenceError);
-    }
-
-    var envKey = process.env.BABEL_ENV || process.env.NODE_ENV || "development";
-    if (opts.env) merge(opts, opts.env[envKey]);
-
-    for (let key in File.options) {
-      let option = File.options[key];
-
-      var val = opts[key];
-      if (!val && option.optional) continue;
-
-      if (val && option.deprecated) {
-        throw new Error("Deprecated option " + key + ": " + option.deprecated);
-      }
-
-      if (val == null) {
-        val = clone(option.default);
-      }
-
-      var optionParser = optionParsers[option.type];
-      if (optionParser) val = optionParser(key, val, this.pipeline);
-
-      if (option.alias) {
-        opts[option.alias] = opts[option.alias] || val;
-      } else {
-        opts[key] = val;
-      }
-    }
+  initOptions(opts) {
+    opts = new OptionManager(this.log, this.pipeline).init(opts);
 
     if (opts.inputSourceMap) {
       opts.sourceMaps = true;
     }
 
-    // normalize windows path separators to unix
-    opts.filename = slash(opts.filename);
-    if (opts.sourceRoot) {
-      opts.sourceRoot = slash(opts.sourceRoot);
-    }
-
     if (opts.moduleId) {
       opts.moduleIds = true;
     }
@@ -149,7 +122,8 @@ export default class File {
     opts.basename = path.basename(opts.filename, path.extname(opts.filename));
 
     opts.ignore = util.arrayify(opts.ignore, util.regexify);
-    opts.only   = util.arrayify(opts.only, util.regexify);
+
+    if (opts.only) opts.only = util.arrayify(opts.only, util.regexify);
 
     defaults(opts, {
       moduleRoot: opts.sourceRoot
@@ -175,12 +149,20 @@ export default class File {
     }
 
     return opts;
-  };
+  }
+
+  /**
+   * [Please add a description.]
+   */
 
   isLoose(key: string) {
     return includes(this.opts.loose, key);
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   buildTransformers() {
     var file = this;
 
@@ -226,7 +208,7 @@ 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;
       }
     }
@@ -235,6 +217,10 @@ export default class File {
     this.transformerStack = this.collapseStack(stack);
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   collapseStack(_stack) {
     var stack  = [];
     var ignore = [];
@@ -243,7 +229,7 @@ export default class File {
       // been merged
       if (ignore.indexOf(pass) >= 0) continue;
 
-      var group = pass.transformer.metadata.group;
+      var group = pass.plugin.metadata.group;
 
       // can't merge
       if (!pass.canTransform() || !group) {
@@ -253,7 +239,7 @@ export default class File {
 
       var mergeStack = [];
       for (let pass of (_stack: Array)) {
-        if (pass.transformer.metadata.group === group) {
+        if (pass.plugin.metadata.group === group) {
           mergeStack.push(pass);
           ignore.push(pass);
         }
@@ -261,24 +247,36 @@ 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;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   set(key: string, val): any {
     return this.data[key] = val;
-  };
+  }
+
+  /**
+   * [Please add a description.]
+   */
 
   setDynamic(key: string, fn: Function) {
     this.dynamicData[key] = fn;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   get(key: string): any {
     var data = this.data[key];
     if (data) {
@@ -291,12 +289,20 @@ export default class File {
     }
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   resolveModuleSource(source: string): string {
     var resolveModuleSource = this.opts.resolveModuleSource;
     if (resolveModuleSource) source = resolveModuleSource(source, this.opts.filename);
     return source;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   addImport(source: string, name?: string, type?: string): Object {
     name = name || source;
     var id = this.dynamicImportIds[name];
@@ -315,7 +321,7 @@ 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);
@@ -325,18 +331,36 @@ export default class File {
     return id;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   attachAuxiliaryComment(node: Object): Object {
-    var comment = this.opts.auxiliaryComment;
-    if (comment) {
+    var beforeComment = this.opts.auxiliaryCommentBefore;
+    if (beforeComment) {
       node.leadingComments = node.leadingComments || [];
       node.leadingComments.push({
         type: "CommentLine",
-        value: " " + comment
+        value: " " + beforeComment
       });
     }
+
+    var afterComment = this.opts.auxiliaryCommentAfter;
+    if (afterComment) {
+      node.trailingComments = node.trailingComments || [];
+      node.trailingComments.push({
+        type: "CommentLine",
+        value: " " + afterComment
+      });
+    }
+
     return node;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   addHelper(name: string): Object {
     var isSolo = includes(File.soloHelpers, name);
 
@@ -383,18 +407,27 @@ export default class File {
     return uid;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   errorWithNode(node, msg, Error = SyntaxError) {
     var err;
-    if (node.loc) {
+    if (node && node.loc) {
       var loc = node.loc.start;
       err = new Error(`Line ${loc.line}: ${msg}`);
       err.loc = loc;
     } else {
+      // todo: find errors with nodes inside to at least point to something
       err = new Error("There's been an error on a dynamic node. This is almost certainly an internal error. Please report it.");
     }
     return err;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   mergeSourceMap(map: Object) {
     var opts = this.opts;
 
@@ -417,6 +450,9 @@ export default class File {
     return map;
   }
 
+  /**
+   * [Please add a description.]
+   */
 
   getModuleFormatter(type: string) {
     if (isFunction(type) || !moduleFormatters[type]) {
@@ -437,6 +473,10 @@ export default class File {
     return new ModuleFormatter(this);
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   parse(code: string) {
     var opts = this.opts;
 
@@ -465,17 +505,26 @@ export default class File {
     return tree;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   _addAst(ast) {
-    this.path  = NodePath.get({
+    this.path = NodePath.get({
+      hub: this.hub,
       parentPath: null,
       parent: ast,
       container: ast,
       key: "program"
-    }).setContext(null, this);
+    }).setContext();
     this.scope = this.path.scope;
     this.ast   = ast;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   addAst(ast) {
     this.log.debug("Start set AST");
     this._addAst(ast);
@@ -486,14 +535,12 @@ export default class File {
     if (modFormatter.init && this.transformers["es6.modules"].canTransform()) {
       modFormatter.init();
     }
-    this.populateModuleMetadata();
     this.log.debug("End module formatter init");
   }
 
-  populateModuleMetadata() {
-    var modules = {};
-    this.metadata.modules = modules;
-  }
+  /**
+   * [Please add a description.]
+   */
 
   transform() {
     this.call("pre");
@@ -505,11 +552,19 @@ export default class File {
     return this.generate();
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   wrap(code, callback) {
     code = code + "";
 
     try {
-      return callback();
+      if (this.shouldIgnore()) {
+        return this.makeResult({ code, ignored: true });
+      } else {
+        return callback();
+      }
     } catch (err) {
       if (err._babel) {
         throw err;
@@ -538,29 +593,49 @@ export default class File {
     }
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   addCode(code: string) {
     code = (code || "") + "";
     code = this.parseInputSourceMap(code);
     this.code = code;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   parseCode() {
     this.parseShebang();
     this.addAst(this.parse(this.code));
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   shouldIgnore() {
     var opts = this.opts;
     return util.shouldIgnore(opts.filename, opts.ignore, opts.only);
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   call(key: string) {
     for (var pass of (this.uncollapsedTransformerStack: Array)) {
-      var fn = pass.transformer[key];
+      var fn = pass.plugin[key];
       if (fn) fn(this);
     }
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   parseInputSourceMap(code: string) {
     var opts = this.opts;
 
@@ -575,6 +650,10 @@ export default class File {
     return code;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   parseShebang() {
     var shebangMatch = shebangRegex.exec(this.code);
     if (shebangMatch) {
@@ -583,6 +662,10 @@ export default class File {
     }
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   makeResult({ code, map = null, ast, ignored }) {
     var result = {
       metadata: null,
@@ -608,6 +691,10 @@ export default class File {
     return result;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   generate() {
     var opts = this.opts;
     var ast  = this.ast;

src/babel/transformation/file/logger.js

@@ -4,36 +4,82 @@ import buildDebug from "debug/node";
 var verboseDebug = buildDebug("babel:verbose");
 var generalDebug = buildDebug("babel");
 
+var seenDeprecatedMessages = [];
+
+/**
+ * [Please add a description.]
+ */
+
 export default class Logger {
   constructor(file: File, filename: string) {
     this.filename = filename;
     this.file     = file;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   _buildMessage(msg: string): string {
     var parts = `[BABEL] ${this.filename}`;
     if (msg) parts += `: ${msg}`;
     return parts;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
+  warn(msg) {
+    console.warn(this._buildMessage(msg));
+  }
+
+  /**
+   * [Please add a description.]
+   */
+
   error(msg: string, Constructor = Error) {
     throw new Constructor(this._buildMessage(msg));
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   deprecate(msg) {
-    if (!this.file.opts.suppressDeprecationMessages) {
-      console.error(this._buildMessage(msg));
-    }
+    if (this.file.opts.suppressDeprecationMessages) return;
+
+    msg = this._buildMessage(msg);
+
+    // already seen this message
+    if (seenDeprecatedMessages.indexOf(msg) >= 0) return;
+
+    // make sure we don't see it again
+    seenDeprecatedMessages.push(msg);
+
+    console.error(msg);
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   verbose(msg: string) {
     if (verboseDebug.enabled) verboseDebug(this._buildMessage(msg));
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   debug(msg: string) {
     if (generalDebug.enabled) generalDebug(this._buildMessage(msg));
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   deopt(node: Object, msg: string) {
     this.debug(msg);
   }

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

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

src/babel/transformation/file/options/README.md

@@ -0,0 +1,3 @@
+## File Options
+
+This is the File Options directory.

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

@@ -1,6 +1,6 @@
 {
   "filename": {
-    "type": "string",
+    "type": "filename",
     "description": "filename to use when reading from stdin - this will be used in source-maps, errors etc",
     "default": "unknown",
     "shorthand": "f"
@@ -47,7 +47,9 @@
   },
 
   "experimental": {
-    "deprecated": "use `--stage 0`/`{ stage: 0 }` instead"
+    "type": "boolean",
+    "description": "allow use of experimental transformers",
+    "default": false
   },
 
   "highlightCode": {
@@ -76,7 +78,8 @@
   "blacklist": {
     "type": "transformerList",
     "description": "blacklist of transformers to NOT use",
-    "shorthand": "b"
+    "shorthand": "b",
+    "default": []
   },
 
   "whitelist": {
@@ -88,7 +91,8 @@
 
   "optional": {
     "type": "transformerList",
-    "description": "list of optional transformers to enable"
+    "description": "list of optional transformers to enable",
+    "default": []
   },
 
   "modules": {
@@ -120,12 +124,14 @@
 
   "plugins": {
     "type": "list",
-    "description": ""
+    "description": "",
+    "default": []
   },
 
   "ignore": {
     "type": "list",
-    "description": "list of glob paths to **not** compile"
+    "description": "list of glob paths to **not** compile",
+    "default": []
   },
 
   "only": {
@@ -171,12 +177,23 @@
   },
 
   "auxiliaryComment": {
+    "deprecated": "renamed to auxiliaryCommentBefore",
+    "shorthand": "a",
+    "alias": "auxiliaryCommentBefore"
+  },
+
+  "auxiliaryCommentBefore": {
     "type": "string",
     "default": "",
-    "shorthand": "a",
     "description": "attach a comment before all helper declarations and auxiliary code"
   },
 
+  "auxiliaryCommentAfter": {
+    "type": "string",
+    "default": "",
+    "description": "attach a comment after all helper declarations and auxiliary code"
+  },
+
   "externalHelpers": {
     "type": "boolean",
     "default": false,
@@ -219,12 +236,12 @@
   },
 
   "sourceRoot": {
-    "type": "string",
+    "type": "filename",
     "description": "the root from which all sources are relative"
   },
 
   "moduleRoot": {
-    "type": "string",
+    "type": "filename",
     "description": "optional prefix for the AMD module formatter that will be prepend to the filename on module definitions"
   },
 
@@ -236,7 +253,7 @@
   },
 
   "babelrc": {
-    "hidden": true,
-    "description": "do not load the same .babelrc file twice"
+    "description": "Specify a custom list of babelrc files to use",
+    "type": "list"
   }
 }

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

@@ -0,0 +1,39 @@
+import * as parsers from "./parsers";
+import config from "./config";
+
+export { config };
+
+/**
+ * Validate an option.
+ */
+
+export function validateOption(key, val, pipeline) {
+  var opt = config[key];
+  var parser = opt && parsers[opt.type];
+  if (parser && parser.validate) {
+    return parser.validate(key, val, pipeline);
+  } else {
+    return val;
+  }
+}
+
+/**
+ * Normalize all options.
+ */
+
+export function normaliseOptions(options = {}) {
+  for (var key in options) {
+    var val = options[key];
+    if (val == null) continue;
+
+    var opt = config[key];
+    if (!opt) continue;
+
+    var parser = parsers[opt.type];
+    if (parser) val = parser(val);
+
+    options[key] = val;
+  }
+
+  return options;
+}

src/babel/transformation/file/options/option-manager.js

@@ -0,0 +1,170 @@
+import { validateOption, normaliseOptions } from "./index";
+import stripJsonComments from "strip-json-comments";
+import isAbsolute from "path-is-absolute";
+import pathExists from "path-exists";
+import clone from "lodash/lang/clone";
+import merge from "../../../helpers/merge";
+import config from "./config";
+import path from "path";
+import fs from "fs";
+
+var existsCache = {};
+var jsonCache   = {};
+
+const CONFIG_FILENAME = ".babelrc";
+
+function exists(filename) {
+  var cached = existsCache[filename];
+  if (cached != null) {
+    return cached;
+  } else {
+    return existsCache[filename] = pathExists.sync(filename);
+  }
+}
+
+export default class OptionManager {
+  constructor(log, pipeline) {
+    this.resolvedConfigs = [];
+    this.options         = OptionManager.createBareOptions();
+    this.pipeline        = pipeline;
+    this.log             = log;
+  }
+
+  /**
+   * [Please add a description.]
+   */
+
+  static createBareOptions() {
+    var opts = {};
+
+    for (var key in config) {
+      var opt = config[key];
+      opts[key] = clone(opt.default);
+    }
+
+    return opts;
+  }
+
+  /**
+   * [Please add a description.]
+   */
+
+  addConfig(loc) {
+    if (this.resolvedConfigs.indexOf(loc) >= 0) return;
+
+    var content = fs.readFileSync(loc, "utf8");
+    var opts;
+
+    try {
+      opts = jsonCache[content] = jsonCache[content] || JSON.parse(stripJsonComments(content));
+    } catch (err) {
+      err.message = `${loc}: ${err.message}`;
+      throw err;
+    }
+
+    this.mergeOptions(opts, loc);
+    this.resolvedConfigs.push(loc);
+  }
+
+  /**
+   * [Please add a description.]
+   */
+
+  mergeOptions(opts, alias = "foreign") {
+    if (!opts) return;
+
+    for (let key in opts) {
+      if (key[0] === "_") continue;
+
+      let option = config[key];
+
+      // check for an unknown option
+      if (!option) this.log.error(`Unknown option: ${alias}.${key}`, ReferenceError);
+    }
+
+    // normalise options
+    normaliseOptions(opts);
+
+    // merge them into this current files options
+    merge(this.options, opts);
+  }
+
+  /**
+   * [Please add a description.]
+   */
+
+  findConfigs(loc) {
+    if (!loc) return;
+
+    if (!isAbsolute(loc)) {
+      loc = path.join(process.cwd(), loc);
+    }
+
+    while (loc !== (loc = path.dirname(loc))) {
+      if (this.options.breakConfig) return;
+
+      var configLoc = path.join(loc, CONFIG_FILENAME);
+      if (exists(configLoc)) this.addConfig(configLoc);
+    }
+  }
+
+  /**
+   * [Please add a description.]
+   */
+
+  normaliseOptions() {
+    var opts = this.options;
+
+    for (let key in config) {
+      var option = config[key];
+      var val    = opts[key];
+
+      // optional
+      if (!val && option.optional) continue;
+
+      // deprecated
+      if (this.log && val && option.deprecated) {
+        this.log.deprecate(`Deprecated option ${key}: ${option.deprecated}`);
+      }
+
+      // validate
+      if (this.pipeline && val) {
+        val = validateOption(key, val, this.pipeline);
+      }
+
+      // aaliases
+      if (option.alias) {
+        opts[option.alias] = opts[option.alias] || val;
+      } else {
+        opts[key] = val;
+      }
+    }
+  }
+
+  /**
+   * [Please add a description.]
+   */
+
+  init(opts) {
+    this.mergeOptions(opts, "direct");
+
+    // babelrc option
+    if (opts.babelrc) {
+      for (var loc of (opts.babelrc: Array)) this.addConfig(loc);
+    }
+
+    // resolve all .babelrc files
+    this.findConfigs(opts.filename);
+
+    // merge in env
+    var envKey = process.env.BABEL_ENV || process.env.NODE_ENV || "development";
+    if (this.options.env) {
+      this.mergeOptions(this.options.env[envKey], `direct.env.${envKey}`);
+    }
+
+    // normalise
+    this.normaliseOptions(opts);
+
+    return this.options;
+  }
+}

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

@@ -0,0 +1,60 @@
+import slash from "slash";
+import * as util from "../../../util";
+
+/**
+ * Get a transformer list from a value.
+ */
+
+export function transformerList(val) {
+  return util.arrayify(val);
+}
+
+/**
+ * Validate transformer list. Maps "all" to all transformer names.
+ */
+
+transformerList.validate = function (key, val, pipeline) {
+  if (val.indexOf("all") >= 0 || val.indexOf(true) >= 0) {
+    val = Object.keys(pipeline.transformers);
+  }
+
+  return pipeline._ensureTransformerNames(key, val);
+};
+
+/**
+ * Cast a value to a number.
+ */
+
+export function number(val) {
+  return +val;
+}
+
+/**
+ * Cast a value to a boolean.
+ */
+
+export var filename = slash;
+
+/**
+ * [Please add a description.]
+ */
+
+export function boolean(val) {
+  return !!val;
+}
+
+/**
+ * Cast a boolean-like string to a boolean.
+ */
+
+export function booleanString(val) {
+  return util.booleanify(val);
+}
+
+/**
+ * Cast a value to an array, splitting strings by ",".
+ */
+
+export function list(val) {
+  return util.list(val);
+}

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

@@ -1,17 +1,48 @@
-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 "../../traversal";
+import parse from "../../helpers/parse";
+
+/**
+ * [Please add a description.]
+ */
+
+var context = {
+  messages,
+  Transformer,
+  Plugin,
+  types,
+  parse,
+  traverse
+};
+
 import * as util from  "../../util";
 
+/**
+ * [Please add a description.]
+ */
+
 export default class PluginManager {
+
+  /**
+   * [Please add a description.]
+   */
+
   static memoisedPlugins = [];
 
+  /**
+   * [Please add a description.]
+   */
+
   static memoisePluginContainer(fn) {
     for (var i = 0; i < PluginManager.memoisedPlugins.length; i++) {
       var plugin = PluginManager.memoisedPlugins[i];
       if (plugin.container === fn) return plugin.transformer;
     }
 
-    var transformer = fn(node);
+    var transformer = fn(context);
     PluginManager.memoisedPlugins.push({
       container: fn,
       transformer: transformer
@@ -19,8 +50,16 @@ export default class PluginManager {
     return transformer;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   static positions = ["before", "after"];
 
+  /**
+   * [Please add a description.]
+   */
+
   constructor({ file, transformers, before, after } = { transformers: {}, before: [], after: [] }) {
     this.transformers = transformers;
     this.file         = file;
@@ -28,6 +67,10 @@ export default class PluginManager {
     this.after        = after;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   subnormaliseString(name, position) {
     // this is a plugin in the form of "foobar" or "foobar:after"
     // where the optional colon is the delimiter for plugin position in the transformer stack
@@ -47,6 +90,10 @@ export default class PluginManager {
     }
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   validate(name, plugin) {
     // validate transformer key
     var key = plugin.key;
@@ -55,7 +102,7 @@ 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));
     }
 
@@ -63,6 +110,10 @@ export default class PluginManager {
     plugin.metadata.plugin = true;
   }
 
+  /**
+   * [Please add a description.]
+   */
+
   add(name) {
     var position;
     var plugin;

src/babel/transformation/helpers/README.md

@@ -0,0 +1,3 @@
+## Transformation Helpers
+
+This is the Transformation Helpers directory.

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

@@ -1,17 +1,33 @@
 import explode from "./explode-assignable-expression";
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 export default function (opts) {
   var exports = {};
 
+  /**
+   * [Please add a description.]
+   */
+
   var isAssignment = function (node) {
     return node.operator === opts.operator + "=";
   };
 
+  /**
+   * [Please add a description.]
+   */
+
   var buildAssignment = function (left, right) {
     return t.assignmentExpression("=", left, right);
   };
 
+  /**
+   * [Please add a description.]
+   */
+
   exports.ExpressionStatement = function (node, parent, scope, file) {
     // hit the `AssignmentExpression` one below
     if (this.isCompletionRecord()) return;
@@ -29,6 +45,10 @@ export default function (opts) {
     return nodes;
   };
 
+  /**
+   * [Please add a description.]
+   */
+
   exports.AssignmentExpression = function (node, parent, scope, file) {
     if (!isAssignment(node)) return;
 
@@ -38,6 +58,10 @@ export default function (opts) {
     return nodes;
   };
 
+  /**
+   * [Please add a description.]
+   */
+
   exports.BinaryExpression = function (node) {
     if (node.operator !== opts.operator) return;
     return opts.build(node.left, node.right);

src/babel/transformation/helpers/build-comprehension.js

@@ -1,5 +1,9 @@
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 export default function build(node, buildBody) {
   var self = node.blocks.shift();
   if (!self) return;

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

@@ -1,11 +1,24 @@
 import explode from "./explode-assignable-expression";
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 export default function (exports, opts) {
+
+  /**
+   * [Please add a description.]
+   */
+
   var buildAssignment = function (left, right) {
     return t.assignmentExpression("=", left, right);
   };
 
+  /**
+   * [Please add a description.]
+   */
+
   exports.ExpressionStatement = function (node, parent, scope, file) {
     // hit the `AssignmentExpression` one below
     if (this.isCompletionRecord()) return;
@@ -25,6 +38,10 @@ export default function (exports, opts) {
     return nodes;
   };
 
+  /**
+   * [Please add a description.]
+   */
+
   exports.AssignmentExpression = function (node, parent, scope, file) {
     if (!opts.is(node, file)) return;
 

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

@@ -9,8 +9,18 @@ import esutils from "esutils";
 import * as react from "./react";
 import * as t from "../../types";
 
-export default function (exports, opts) {
-  exports.JSXIdentifier = function (node) {
+/**
+ * [Please add a description.]
+ */
+
+export default function (opts) {
+  var visitor = {};
+
+  /**
+   * [Please add a description.]
+   */
+
+  visitor.JSXIdentifier = function (node) {
     if (node.name === "this" && this.isReferenced()) {
       return t.thisExpression();
     } else if (esutils.keyword.isIdentifierNameES6(node.name)) {
@@ -20,22 +30,38 @@ export default function (exports, opts) {
     }
   };
 
-  exports.JSXNamespacedName = function () {
+  /**
+   * [Please add a description.]
+   */
+
+  visitor.JSXNamespacedName = function () {
     throw this.errorWithNode(messages.get("JSXNamespacedTags"));
   };
 
-  exports.JSXMemberExpression = {
+  /**
+   * [Please add a description.]
+   */
+
+  visitor.JSXMemberExpression = {
     exit(node) {
       node.computed = t.isLiteral(node.property);
       node.type = "MemberExpression";
     }
   };
 
-  exports.JSXExpressionContainer = function (node) {
+  /**
+   * [Please add a description.]
+   */
+
+  visitor.JSXExpressionContainer = function (node) {
     return node.expression;
   };
 
-  exports.JSXAttribute = {
+  /**
+   * [Please add a description.]
+   */
+
+  visitor.JSXAttribute = {
     enter(node) {
       var value = node.value;
       if (t.isLiteral(value) && isString(value.value)) {
@@ -49,7 +75,11 @@ export default function (exports, opts) {
     }
   };
 
-  exports.JSXOpeningElement = {
+  /**
+   * [Please add a description.]
+   */
+
+  visitor.JSXOpeningElement = {
     exit(node, parent, scope, file) {
       parent.children = react.buildChildren(parent);
 
@@ -139,7 +169,11 @@ export default function (exports, opts) {
     return attribs;
   };
 
-  exports.JSXElement = {
+  /**
+   * [Please add a description.]
+   */
+
+  visitor.JSXElement = {
     exit(node) {
       var callExpr = node.openingElement;
 
@@ -153,54 +187,5 @@ 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/call-delegate.js

@@ -1,6 +1,15 @@
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 var visitor = {
+
+  /**
+   * [Please add a description.]
+   */
+
   enter(node, parent, scope, state) {
     if (this.isThisExpression() || this.isReferencedIdentifier({ name: "arguments" })) {
       state.found = true;
@@ -8,11 +17,19 @@ var visitor = {
     }
   },
 
+  /**
+   * [Please add a description.]
+   */
+
   Function() {
     this.skip();
   }
 };
 
+/**
+ * [Please add a description.]
+ */
+
 export default function (node, scope) {
   var container = t.functionExpression(null, [], node.body, node.generator, node.async);
 

src/babel/transformation/helpers/define-map.js

@@ -2,6 +2,10 @@ import each from "lodash/collection/each";
 import has from "lodash/object/has";
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 export function push(mutatorMap, node, kind, file) {
   var alias = t.toKeyAlias(node);
 
@@ -43,6 +47,10 @@ export function push(mutatorMap, node, kind, file) {
   return map;
 }
 
+/**
+ * [Please add a description.]
+ */
+
 export function hasComputed(mutatorMap) {
   for (var key in mutatorMap) {
     if (mutatorMap[key]._computed) {
@@ -52,6 +60,10 @@ export function hasComputed(mutatorMap) {
   return false;
 }
 
+/**
+ * [Please add a description.]
+ */
+
 export function toComputedObjectFromClass(obj) {
   var objExpr = t.arrayExpression([]);
 
@@ -65,6 +77,10 @@ export function toComputedObjectFromClass(obj) {
   return objExpr;
 }
 
+/**
+ * [Please add a description.]
+ */
+
 export function toClassObject(mutatorMap) {
   var objExpr = t.objectExpression([]);
 
@@ -92,6 +108,10 @@ export function toClassObject(mutatorMap) {
   return objExpr;
 }
 
+/**
+ * [Please add a description.]
+ */
+
 export function toDefineObject(mutatorMap) {
   each(mutatorMap, function (map) {
     if (map.value) map.writable = t.literal(true);

src/babel/transformation/helpers/explode-assignable-expression.js

@@ -1,5 +1,9 @@
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 var getObjRef = function (node, nodes, file, scope) {
   var ref;
   if (t.isIdentifier(node)) {
@@ -33,6 +37,10 @@ var getObjRef = function (node, nodes, file, scope) {
   return temp;
 };
 
+/**
+ * [Please add a description.]
+ */
+
 var getPropRef = function (node, nodes, file, scope) {
   var prop = node.property;
   var key = t.toComputedKey(node, prop);
@@ -45,6 +53,10 @@ var getPropRef = function (node, nodes, file, scope) {
   return temp;
 };
 
+/**
+ * [Please add a description.]
+ */
+
 export default function (node, nodes, file, scope, allowedSingleIdent) {
   var obj;
   if (t.isIdentifier(node) && allowedSingleIdent) {

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

@@ -1,9 +1,16 @@
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 export default function (node) {
   var lastNonDefault = 0;
   for (var i = 0; i < node.params.length; i++) {
-    if (!t.isAssignmentPattern(node.params[i])) lastNonDefault = i + 1;
+    var param = node.params[i];
+    if (!t.isAssignmentPattern(param) && !t.isRestElement(param)) {
+      lastNonDefault = i + 1;
+    }
   }
   return lastNonDefault;
 }

src/babel/transformation/helpers/memoise-decorators.js

@@ -1,5 +1,9 @@
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 export default function (decorators, scope) {
   for (var i = 0; i < decorators.length; i++) {
     var decorator = decorators[i];

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

@@ -2,6 +2,10 @@ import getFunctionArity from "./get-function-arity";
 import * as util from  "../../util";
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 function visitIdentifier(context, node, scope, state) {
   // check if this node matches our function id
   if (node.name !== state.name) return;
@@ -15,19 +19,33 @@ function visitIdentifier(context, node, scope, state) {
   context.stop();
 }
 
+/**
+ * [Please add a description.]
+ */
+
 var visitor = {
+
+  /**
+   * [Please add a description.]
+   */
+
   ReferencedIdentifier(node, parent, scope, state) {
     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);
-    }
+  /**
+   * [Please add a description.]
+   */
+
+  BindingIdentifier(node, parent, scope, state) {
+    visitIdentifier(this, node, scope, state);
   }
 };
 
+/**
+ * [Please add a description.]
+ */
+
 var wrap = function (state, method, id, scope) {
   if (state.selfReference) {
     if (scope.hasBinding(id.name) && !scope.hasGlobal(id.name)) {
@@ -59,6 +77,10 @@ var wrap = function (state, method, id, scope) {
   scope.getProgramParent().references[id.name] = true;
 };
 
+/**
+ * [Please add a description.]
+ */
+
 var visit = function (node, name, scope) {
   var state = {
     selfAssignment: false,
@@ -71,10 +93,10 @@ 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) {};
@@ -105,17 +127,24 @@ var visit = function (node, name, scope) {
   return state;
 };
 
+/**
+ * [Please add a description.]
+ */
+
 export function custom(node, id, scope) {
   var state = visit(node, id.name, scope);
   return wrap(state, node, id, scope);
 }
 
+/**
+ * [Please add a description.]
+ */
+
 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;
@@ -123,6 +152,10 @@ export function property(node, file, scope) {
   node.value = wrap(state, method, id, scope) || method;
 }
 
+/**
+ * [Please add a description.]
+ */
+
 export function bare(node, parent, scope) {
   // has an `id` so we don't need to infer one
   if (node.id) return;
@@ -136,8 +169,8 @@ 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 +189,7 @@ 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

@@ -1,30 +1,19 @@
 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");
 
+/**
+ * [Please add a description.]
+ */
+
 export function isCompatTag(tagName) {
   return tagName && /^[a-z]|\-/.test(tagName);
 }
 
+/**
+ * [Please add a description.]
+ */
+
 function cleanJSXElementLiteralChild(child, args) {
   var lines = child.value.split(/\r\n|\n|\r/);
 
@@ -70,6 +59,10 @@ function cleanJSXElementLiteralChild(child, args) {
   if (str) args.push(t.literal(str));
 }
 
+/**
+ * [Please add a description.]
+ */
+
 export function buildChildren(node) {
   var elems = [];
 

src/babel/transformation/helpers/regex.js

@@ -1,10 +1,18 @@
 import pull from "lodash/array/pull";
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 export function is(node, flag) {
   return t.isLiteral(node) && node.regex && node.regex.flags.indexOf(flag) >= 0;
 }
 
+/**
+ * [Please add a description.]
+ */
+
 export function pullFlag(node, flag) {
   var flags = node.regex.flags.split("");
   if (node.regex.flags.indexOf(flag) < 0) return;

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

@@ -1,10 +1,23 @@
 import * as t from "../../types";
 
+/**
+ * [Please add a description.]
+ */
+
 var awaitVisitor = {
+
+  /**
+   * [Please add a description.]
+   */
+
   Function() {
     this.skip();
   },
 
+  /**
+   * [Please add a description.]
+   */
+
   AwaitExpression(node) {
     node.type = "YieldExpression";
 
@@ -16,7 +29,16 @@ var awaitVisitor = {
   }
 };
 
+/**
+ * [Please add a description.]
+ */
+
 var referenceVisitor = {
+
+  /**
+   * [Please add a description.]
+   */
+
   ReferencedIdentifier(node, parent, scope, state) {
     var name = state.id.name;
     if (node.name === name && scope.bindingIdentifierEquals(name, state.id)) {
@@ -25,11 +47,17 @@ var referenceVisitor = {
   }
 };
 
-export default function (node, callId, scope) {
+/**
+ * [Please add a description.]
+ */
+
+export default function (path, callId) {
+  var node = path.node;
+
   node.async = false;
   node.generator = true;
 
-  scope.traverse(node, awaitVisitor, state);
+  path.traverse(awaitVisitor, state);
 
   var call = t.callExpression(callId, [node]);
 
@@ -44,11 +72,11 @@ export default function (node, callId, scope) {
     return declar;
   } else {
     if (id) {
-      var state = { id: id };
-      scope.traverse(node, referenceVisitor, state);
+      var state = { id };
+      path.traverse(referenceVisitor, state);
 
       if (state.ref) {
-        scope.parent.push({ id: state.ref });
+        path.scope.parent.push({ id: state.ref });
         return t.assignmentExpression("=", state.ref, call);
       }
     }