hoist FunctionDeclaration exports to top, possible fix for #30

lib/6to5/transform.js

@@ -34,7 +34,7 @@ var transform = module.exports = function (code, opts) {
 };
 
 transform._run = function (code, tree, opts) {
-  traverse.replace(tree, function (node) {
+  traverse(tree, function (node) {
     if (node.type === "EmptyStatement") {
       return traverse.Delete;
     }
@@ -70,13 +70,22 @@ transform._run = function (code, tree, opts) {
 };
 
 transform._runTransformer = function (transformer, tree, opts, generateUid) {
-  if (transformer.Program) transformer.Program(tree, opts);
+  var build = function (exit) {
+    return function (node, parent) {
+      var fns = transformer[node.type] || transformer.all;
+      if (!fns) return;
 
-  traverse.replace(tree, function (node, parent) {
-    var fn = transformer[node.type] || transformer.all;
-    if (!fn) return;
+      var fn = fns.enter || fns;
+      if (exit) fn = fns.exit;
+      if (!fn || !_.isFunction(fn)) return;
 
-    return fn(node, parent, opts, generateUid);
+      return fn(node, parent, opts, generateUid);
+    };
+  };
+
+  traverse(tree, {
+    enter: build(),
+    exit:  build(true)
   });
 };
 

lib/6to5/transformers/modules.js

@@ -61,7 +61,7 @@ var pushExportSpecifiers = function (node, nodes) {
   });
 };
 
-var pushExportDeclaration = function (node, nodes) {
+var pushExportDeclaration = function (node, parent, nodes) {
   var declar = node.declaration;
 
   if (node.default) {
@@ -80,19 +80,43 @@ var pushExportDeclaration = function (node, nodes) {
       id = declar.declarations[0].id;
     }
 
-    nodes.push(declar);
-    nodes.push(util.template("exports-assign", {
+    var assign = util.template("exports-assign", {
       VALUE: id,
       KEY:   id
-    }, true));
+    }, true);
+
+    nodes.push(declar);
+
+    if (declar.type === "FunctionDeclaration") {
+      assign._modulesHoist = true;
+    }
+
+    nodes.push(assign);
   }
 };
 
-exports.ExportDeclaration = function (node) {
+exports.Program = {
+  exit: function (node) {
+    var unshift = [];
+
+    node.body = node.body.filter(function (bodyNode) {
+      if (bodyNode._modulesHoist) {
+        unshift.push(bodyNode);
+        return false;
+      } else {
+        return true;
+      }
+    });
+
+    node.body = unshift.concat(node.body);
+  }
+};
+
+exports.ExportDeclaration = function (node, parent) {
   var nodes = [];
 
   if (node.declaration) {
-    pushExportDeclaration(node, nodes);
+    pushExportDeclaration(node, parent, nodes);
   } else {
     pushExportSpecifiers(node, nodes);
   }

test/fixtures/modules/exports-variable/expected.js

@@ -3,6 +3,8 @@ var foo2;
 var foo3;
 var foo8;
 (function () {
+  exports.foo7 = foo7;
+
   foo = 1;
   exports.foo = foo;
 
@@ -21,7 +23,6 @@ var foo8;
   exports.foo6 = foo6;
 
   function foo7 () {}
-  exports.foo7 = foo7;
 
   foo8 = function () {
     function foo8() {

test/fixtures/modules/hoist-function-exports/actual.js

@@ -0,0 +1,11 @@
+import { isEven } from "./evens";
+
+export function nextOdd(n) {
+  return isEven(n) ? n + 1 : n + 2;
+}
+
+export var isOdd = (function(isEven) {
+  return function(n) {
+    return !isEven(n);
+  };
+})(isEven);

test/fixtures/modules/hoist-function-exports/expected.js

@@ -0,0 +1,13 @@
+exports.nextOdd = nextOdd;
+
+var isEven = require("./evens").isEven;
+function nextOdd(n) {
+  return isEven(n) ? n + 1 : n + 2;
+}
+
+var isOdd = (function(isEven) {
+  return function(n) {
+    return !isEven(n);
+  };
+})(isEven);
+exports.isOdd = isOdd;