add iterators

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

@@ -0,0 +1,3 @@
+for (var ITERATOR_KEY = OBJECT[Symbol.iterator](), STEP_KEY; !(STEP_KEY = ITERATOR_KEY.next()).done; ) {
+  var KEY = STEP_KEY.value;
+}

lib/6to5/transform.js

@@ -30,6 +30,8 @@ var transform = module.exports = function (code, opts) {
     }
   });
 
+  var generateUid = util.buildUidGenerator();
+
   _.each(transform.transformers, function (transformer, name) {
     var blacklist = opts.blacklist;
     if (blacklist.length && _.contains(blacklist, name)) return;
@@ -37,7 +39,7 @@ var transform = module.exports = function (code, opts) {
     var whitelist = opts.whitelist;
     if (whitelist.length && !_.contains(whitelist, name)) return;
 
-    transform._runTransformer(transformer, tree, opts);
+    transform._runTransformer(transformer, tree, opts, generateUid);
   });
 
   var genOpts = {
@@ -64,14 +66,14 @@ var transform = module.exports = function (code, opts) {
   }
 };
 
-transform._runTransformer = function (transformer, tree, opts) {
+transform._runTransformer = function (transformer, tree, opts, generateUid) {
   if (transformer.Program) transformer.Program(tree, opts);
 
   traverse.replace(tree, function (node, parent) {
     var fn = transformer[node.type] || transformer.all;
     if (!fn) return;
 
-    return fn(node, parent, opts);
+    return fn(node, parent, opts, generateUid);
   });
 };
 
@@ -109,5 +111,6 @@ transform.transformers = {
   generators:               require("./transformers/generators"),
   blockBinding:             require("./transformers/block-binding"),
   modules:                  require("./transformers/modules"),
-  restParameters:           require("./transformers/rest-parameters")
+  restParameters:           require("./transformers/rest-parameters"),
+  iterators:                require("./transformers/iterators")
 };

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

@@ -3,6 +3,8 @@ var util     = require("../util");
 
 exports.ArrowFunctionExpression = function (node) {
   var body = node.body;
+
+  // expression body
   if (body.type !== "BlockStatement") {
     body = {
       type: "BlockStatement",

lib/6to5/transformers/block-binding.js

@@ -35,6 +35,7 @@ exports.BlockStatement = function (node, parent) {
   node.body = buildNode(node.body);
 };
 
+exports.ForOfStatement =
 exports.ForInStatement = function (node) {
   if (isLet(node.left)) return buildNode(node);
 };

lib/6to5/transformers/constants.js

@@ -5,6 +5,7 @@ var _        = require("lodash");
 exports.Program =
 exports.BlockStatement =
 exports.ForInStatement =
+exports.ForOfStatement =
 exports.ForStatement = function (node) {
   var constants = [];
 

lib/6to5/transformers/iterators.js

@@ -0,0 +1,20 @@
+var util = require("../util");
+
+exports.ForOfStatement = function (node, parent, opts, generateUid) {
+  var node2 = util.template("for-of", {
+    ITERATOR_KEY: generateUid("iterator"),
+    STEP_KEY: generateUid("step"),
+
+    KEY: node.left.declarations[0].id,
+    OBJECT: node.right
+  });
+
+  var block = node2.body;
+
+  var declar = block.body[0];
+  declar.kind = node.left.kind;
+
+  block.body = block.body.concat(node.body.body);
+
+  return node2;
+};

lib/6to5/util.js

@@ -47,6 +47,19 @@ exports.canCompile = function (filename) {
   return path.extname(filename) === ".js";
 };
 
+exports.buildUidGenerator = function () {
+  var ids = {};
+
+  return function (name) {
+    var i = ids[name] || 0;
+
+    var id = "_" + name;
+    if (i > 0) id += i;
+    ids[name] = i + 1;
+    return id;
+  };
+};
+
 exports.sourceMapToComment = function (map) {
   var json = JSON.stringify(map);
   var base64 = new Buffer(json).toString("base64");