From 860432cdfdf3cb5b8373b1bc0837ca34b40f9ca2 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Thu, 1 Jan 2015 22:31:59 +1100
Subject: [PATCH] hoist export default to very top

---
 lib/6to5/transformation/modules/_default.js   | 15 +++++++-------
 lib/6to5/transformation/modules/common.js     |  2 +-
 .../transformers/_block-hoist.js              | 20 ++++++++++---------
 3 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/lib/6to5/transformation/modules/_default.js b/lib/6to5/transformation/modules/_default.js
index 1f1747f44d..2c5ffaebe1 100644
--- a/lib/6to5/transformation/modules/_default.js
+++ b/lib/6to5/transformation/modules/_default.js
@@ -124,9 +124,9 @@ DefaultFormatter.prototype._pushStatement = function (ref, nodes) {
   return ref;
 };
 
-DefaultFormatter.prototype._hoistExport = function (declar, assign) {
+DefaultFormatter.prototype._hoistExport = function (declar, assign, priority) {
   if (t.isFunctionDeclaration(declar)) {
-    assign._blockHoist = true;
+    assign._blockHoist = priority || 1;
   }
 
   return assign;
@@ -139,17 +139,18 @@ DefaultFormatter.prototype._exportSpecifier = function (getRef, specifier, node,
   if (node.source) {
     if (t.isExportBatchSpecifier(specifier)) {
       // export * from "foo";
-      nodes.push(this._exportsWildcard(getRef()));
+      nodes.push(this._exportsWildcard(getRef(), node));
     } else {
       // export { foo } from "test";
       nodes.push(this._exportsAssign(
         t.getSpecifierName(specifier),
-        t.memberExpression(getRef(), specifier.id)
+        t.memberExpression(getRef(), specifier.id),
+        node
       ));
     }
   } else {
     // export { foo };
-    nodes.push(this._exportsAssign(t.getSpecifierName(specifier), specifier.id));
+    nodes.push(this._exportsAssign(t.getSpecifierName(specifier), specifier.id, node));
   }
 };
 
@@ -181,7 +182,7 @@ DefaultFormatter.prototype.exportDeclaration = function (node, nodes) {
     for (var i in declar.declarations) {
       var decl = declar.declarations[i];
 
-      decl.init = this._exportsAssign(decl.id, decl.init).expression;
+      decl.init = this._exportsAssign(decl.id, decl.init, node).expression;
 
       var newDeclar = t.variableDeclaration(declar.kind, [decl]);
       if (i === "0") t.inherits(newDeclar, declar);
@@ -195,7 +196,7 @@ DefaultFormatter.prototype.exportDeclaration = function (node, nodes) {
       nodes.push(declar);
     }
 
-    assign = this._exportsAssign(id, ref);
+    assign = this._exportsAssign(id, ref, node);
 
     nodes.push(assign);
 
diff --git a/lib/6to5/transformation/modules/common.js b/lib/6to5/transformation/modules/common.js
index 341846f4a0..6f5025f5ab 100644
--- a/lib/6to5/transformation/modules/common.js
+++ b/lib/6to5/transformation/modules/common.js
@@ -69,7 +69,7 @@ CommonJSFormatter.prototype.exportDeclaration = function (node, nodes) {
     }, true);
 
     // hoist to the top if this default is a function
-    nodes.push(this._hoistExport(declar, assign));
+    nodes.push(this._hoistExport(declar, assign, 2));
   } else {
     DefaultFormatter.prototype.exportDeclaration.apply(this, arguments);
   }
diff --git a/lib/6to5/transformation/transformers/_block-hoist.js b/lib/6to5/transformation/transformers/_block-hoist.js
index 8efe4108fd..6d7eb6a469 100644
--- a/lib/6to5/transformation/transformers/_block-hoist.js
+++ b/lib/6to5/transformation/transformers/_block-hoist.js
@@ -1,17 +1,19 @@
+var _ = require("lodash");
+
 exports.BlockStatement =
 exports.Program = {
   exit: function (node) {
-    var unshift = [];
+    var hasChange = false;
+    for (var i in node.body) {
+      var bodyNode = node.body[i];
+      if (bodyNode && bodyNode._blockHoist) hasChange = true;
+    }
+    if (!hasChange) return;
 
-    node.body = node.body.filter(function (bodyNode) {
-      if (bodyNode._blockHoist) {
-        unshift.push(bodyNode);
-        return false;
-      } else {
-        return true;
-      }
+    var nodePriorities = _.groupBy(node.body, function (bodyNode) {
+      return bodyNode._blockHoist || 0;
     });
 
-    node.body = unshift.concat(node.body);
+    node.body = _.flatten(_.values(nodePriorities).reverse());
   }
 };