From 83487f22a7f5d421120315a9a322aee6453f4ba9 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Thu, 9 Oct 2014 22:41:12 +1100
Subject: [PATCH] support destructuring in For*Statements

---
 lib/6to5/transform.js                         |  2 +-
 lib/6to5/transformers/destructuring.js        | 21 ++++++++++++++++
 lib/6to5/transformers/for-of.js               | 25 ++++++-------------
 .../fixtures/destructuring/for-in/expected.js |  5 ++--
 .../fixtures/destructuring/for-of/expected.js |  7 +++---
 5 files changed, 37 insertions(+), 23 deletions(-)

diff --git a/lib/6to5/transform.js b/lib/6to5/transform.js
index e23dd7f718..79bbe6b70e 100644
--- a/lib/6to5/transform.js
+++ b/lib/6to5/transform.js
@@ -117,7 +117,7 @@ transform.transformers = {
   generators:               require("./transformers/generators"),
   blockBinding:             require("./transformers/block-binding"),
   restParameters:           require("./transformers/rest-parameters"),
-  forOf:                    require("./transformers/for-of"),
   destructuring:            require("./transformers/destructuring"),
+  forOf:                    require("./transformers/for-of"),
   unicodeRegex:             require("./transformers/unicode-regex")
 };
diff --git a/lib/6to5/transformers/destructuring.js b/lib/6to5/transformers/destructuring.js
index bbc7de07f0..0f865fcbe6 100644
--- a/lib/6to5/transformers/destructuring.js
+++ b/lib/6to5/transformers/destructuring.js
@@ -62,6 +62,27 @@ var pushPattern = function (kind, nodes, pattern, parentId, generateUid) {
   push(kind, nodes, pattern, parentId);
 };
 
+exports.ForInStatement =
+exports.ForOfStatement = function (node, parent, opts, generateUid) {
+  var declar = node.left;
+  if (declar.type !== "VariableDeclaration") return;
+
+  var pattern = declar.declarations[0].id;
+  if (!util.isPattern(pattern)) return;
+
+  var key = b.identifier(generateUid("ref"));
+  node.left = b.variableDeclaration(declar.kind, [
+    b.variableDeclarator(key, null)
+  ]);
+
+  var nodes = [];
+
+  push(declar.kind, nodes, pattern, key);
+
+  var block = node.body;
+  block.body = nodes.concat(block.body);
+};
+
 exports.FunctionDeclaration =
 exports.FunctionExpression = function (node, parent, opts, generateUid) {
   var block = node.body;
diff --git a/lib/6to5/transformers/for-of.js b/lib/6to5/transformers/for-of.js
index 26a3937ce1..f17a619727 100644
--- a/lib/6to5/transformers/for-of.js
+++ b/lib/6to5/transformers/for-of.js
@@ -2,17 +2,15 @@ var util = require("../util");
 var b    = require("ast-types").builders;
 
 exports.ForOfStatement = function (node, parent, opts, generateUid) {
-  var declar;
-  var isPattern = false;
-
+  var left = node.left;
   var key;
-  if (node.left.type === "VariableDeclaration") {
-    declar = node.left;
-    key = declar.declarations[0].id;
+
+  if (left.type === "Identifier") {
+    key = left;
+  } else if (left.type === "VariableDeclaration") {
+    key = left.declarations[0].id;
   } else {
-    isPattern = true;
-    declar = node.left[0];
-    key = b.identifier(generateUid("ref"));
+    return;
   }
 
   var node2 = util.template("for-of", {
@@ -22,14 +20,7 @@ exports.ForOfStatement = function (node, parent, opts, generateUid) {
     KEY:          key
   });
 
-  var block  = node2.body;
-
-  if (isPattern) {
-    block.body.push(b.variableDeclaration(declar.kind, [
-      b.variableDeclarator(declar.declarations[0].id, key)
-    ]));
-  }
-
+  var block = node2.body;
   block.body = block.body.concat(node.body.body || []);
 
   var declar  = block.body[0];
diff --git a/test/fixtures/destructuring/for-in/expected.js b/test/fixtures/destructuring/for-in/expected.js
index b4d357111f..f07723cb59 100644
--- a/test/fixtures/destructuring/for-in/expected.js
+++ b/test/fixtures/destructuring/for-in/expected.js
@@ -1,4 +1,5 @@
-for (var name in obj) {
-  var value = obj[name];
+for (var _ref in obj) {
+  var name = _ref[0];
+  var value = _ref[1];
   print("Name: " + name + ", Value: " + value);
 }
diff --git a/test/fixtures/destructuring/for-of/expected.js b/test/fixtures/destructuring/for-of/expected.js
index 5f0004fccd..3ba44b3480 100644
--- a/test/fixtures/destructuring/for-of/expected.js
+++ b/test/fixtures/destructuring/for-of/expected.js
@@ -1,5 +1,6 @@
 for (var _iterator = this.test.expectation.registers[Symbol.iterator](), _step; !(_step = _iterator.next()).done;) {
-  var name = _step.value[0];
-  var before = _step.value[1];
-  var after = _step.value[2];
+  var _ref = _step.value;
+  var name = _ref[0];
+  var before = _ref[1];
+  var after = _ref[2];
 }