From 55054e45da08aa53dcaf67e8537e3a38a22caaf4 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Thu, 15 Jan 2015 19:34:33 +1100
Subject: [PATCH] Revert "Improve performance of rest parameter."

This reverts commit e5463cc2a97cafbf9d35656038f19b45dd75ffce.
---
 lib/6to5/transformation/templates/rest.js     |  2 +-
 .../transformers/es6-rest-parameters.js       | 20 ++++++-------------
 .../arrow-functions/expected.js               |  6 +++---
 .../es6-rest-parameters/multiple/expected.js  | 12 +++++------
 .../es6-rest-parameters/single/expected.js    | 12 +++++------
 5 files changed, 22 insertions(+), 30 deletions(-)

diff --git a/lib/6to5/transformation/templates/rest.js b/lib/6to5/transformation/templates/rest.js
index c15ce8815d..f396f01117 100644
--- a/lib/6to5/transformation/templates/rest.js
+++ b/lib/6to5/transformation/templates/rest.js
@@ -1,3 +1,3 @@
-for (var LEN = ARGUMENTS.length, ARRAY = Array(ARRAY_LEN), KEY = START; KEY < LEN; KEY++) {
+for (var KEY = START; KEY < ARGUMENTS.length; KEY++) {
   ARRAY[ARRAY_KEY] = ARGUMENTS[KEY];
 }
diff --git a/lib/6to5/transformation/transformers/es6-rest-parameters.js b/lib/6to5/transformation/transformers/es6-rest-parameters.js
index d1de130e31..266b6f62f7 100644
--- a/lib/6to5/transformation/transformers/es6-rest-parameters.js
+++ b/lib/6to5/transformation/transformers/es6-rest-parameters.js
@@ -14,31 +14,23 @@ exports.Function = function (node, parent, file) {
 
   var start = t.literal(node.params.length);
   var key = file.generateUidIdentifier("key");
-  var len = file.generateUidIdentifier("len");
 
   var arrKey = key;
   if (node.params.length) {
-    arrKey = t.binaryExpression("-", key, start);
-  }
-
-  var arrLen = len;
-  if (node.params.length) {
-    arrLen = t.conditionalExpression(
-      t.binaryExpression(">", len, start),
-      t.binaryExpression("-", len, start),
-      t.literal(0)
-    );
+    arrKey = t.binaryExpression("-", arrKey, start);
   }
 
   node.body.body.unshift(
+    t.variableDeclaration("var", [
+      t.variableDeclarator(rest, t.arrayExpression([]))
+    ]),
+
     util.template("rest", {
       ARGUMENTS: argsId,
       ARRAY_KEY: arrKey,
-      ARRAY_LEN: arrLen,
       START: start,
       ARRAY: rest,
-      KEY: key,
-      LEN: len,
+      KEY: key
     })
   );
 };
diff --git a/test/fixtures/transformation/es6-rest-parameters/arrow-functions/expected.js b/test/fixtures/transformation/es6-rest-parameters/arrow-functions/expected.js
index fa875fd363..cb971ebc77 100644
--- a/test/fixtures/transformation/es6-rest-parameters/arrow-functions/expected.js
+++ b/test/fixtures/transformation/es6-rest-parameters/arrow-functions/expected.js
@@ -1,9 +1,9 @@
 "use strict";
 
 var concat = function () {
-  for (var _len = arguments.length,
-      arrs = Array(_len),
-      _key = 0; _key < _len; _key++) {
+  var arrs = [];
+
+  for (var _key = 0; _key < arguments.length; _key++) {
     arrs[_key] = arguments[_key];
   }
 };
diff --git a/test/fixtures/transformation/es6-rest-parameters/multiple/expected.js b/test/fixtures/transformation/es6-rest-parameters/multiple/expected.js
index dc6e082ce6..56ff1c407f 100644
--- a/test/fixtures/transformation/es6-rest-parameters/multiple/expected.js
+++ b/test/fixtures/transformation/es6-rest-parameters/multiple/expected.js
@@ -1,17 +1,17 @@
 "use strict";
 
 var t = function (f) {
-  for (var _len = arguments.length,
-      items = Array(_len > 1 ? _len - 1 : 0),
-      _key = 1; _key < _len; _key++) {
+  var items = [];
+
+  for (var _key = 1; _key < arguments.length; _key++) {
     items[_key - 1] = arguments[_key];
   }
 };
 
 function t(f) {
-  for (var _len2 = arguments.length,
-      items = Array(_len2 > 1 ? _len2 - 1 : 0),
-      _key2 = 1; _key2 < _len2; _key2++) {
+  var items = [];
+
+  for (var _key2 = 1; _key2 < arguments.length; _key2++) {
     items[_key2 - 1] = arguments[_key2];
   }
 }
diff --git a/test/fixtures/transformation/es6-rest-parameters/single/expected.js b/test/fixtures/transformation/es6-rest-parameters/single/expected.js
index d6f9e1a5fe..316b3ec9a4 100644
--- a/test/fixtures/transformation/es6-rest-parameters/single/expected.js
+++ b/test/fixtures/transformation/es6-rest-parameters/single/expected.js
@@ -1,17 +1,17 @@
 "use strict";
 
 var t = function () {
-  for (var _len = arguments.length,
-      items = Array(_len),
-      _key = 0; _key < _len; _key++) {
+  var items = [];
+
+  for (var _key = 0; _key < arguments.length; _key++) {
     items[_key] = arguments[_key];
   }
 };
 
 function t() {
-  for (var _len2 = arguments.length,
-      items = Array(_len2),
-      _key2 = 0; _key2 < _len2; _key2++) {
+  var items = [];
+
+  for (var _key2 = 0; _key2 < arguments.length; _key2++) {
     items[_key2] = arguments[_key2];
   }
 }