generator: add support for modules

lib/6to5/generators/modules.js

@@ -1,3 +1,5 @@
+var _ = require("lodash");
+
 exports.ImportSpecifier =
 exports.ExportSpecifier = function (node, print) {
   print(node.id);
@@ -11,14 +13,75 @@ exports.ExportBatchSpecifier = function () {
   this.push("*");
 };
 
-exports.ExportDeclaration = function () {
-  throw new Error("ExportDeclaration");
+exports.ExportDeclaration = function (node, print) {
+  this.push("export");
+
+  var specifiers = node.specifiers;
+
+  if (node.default) {
+    this.push(" default");
+  } else if (specifiers && specifiers.length > 0) {
+    if (specifiers.length === 1 && specifiers[0].type === "ExportBatchSpecifier") {
+      this.push(" *");
+    } else {
+      this.push(" { ");
+      this.printJoin(print, specifiers, ", ");
+      this.push(" }");
+    }
+
+    if (node.source) {
+      this.push(" from ");
+      print(node.source);
+    }
+
+    this.semicolon();
+
+    return;
+  }
+
+  if (node.declaration) {
+    this.push(" ");
+    print(node.declaration);
+  } else {
+    this.push(" { }");
+    this.semicolon();
+  }
 };
 
-exports.ImportDeclaration = function () {
-  throw new Error("ImportDeclaration");
+exports.ImportDeclaration = function (node, print) {
+  var self = this;
+
+  this.push("import ");
+
+  var specfiers = node.specifiers;
+  if (specfiers && specfiers.length) {
+    var foundImportSpecifier = false;
+
+    _.each(node.specifiers, function (spec, i) {
+      if (+i > 0) {
+        self.push(", ");
+      }
+
+      if (!spec.default && spec.type !== "ImportBatchSpecifier" && !foundImportSpecifier) {
+        foundImportSpecifier = true;
+        self.push("{");
+      }
+
+      print(spec);
+    });
+
+    if (foundImportSpecifier) {
+      this.push("}");
+    }
+
+    this.push(" from ");
+  }
+
+  print(node.source);
+  this.semicolon();
 };
 
 exports.ImportBatchSpecifier = function (node, print) {
-  throw new Error("ImportBatchSpecifier");
+  this.push("* as ");
+  print(node.name);
 };