add inherits option to util.template

lib/6to5/transformation/modules/common.js

@@ -10,6 +10,7 @@ function CommonJSFormatter(file) {
 CommonJSFormatter.prototype.import = function (node, nodes) {
   // import "foo";
   nodes.push(util.template("require", {
+    inherits: node,
     MODULE_NAME: node.source.raw
   }, true));
 };
@@ -28,6 +29,8 @@ CommonJSFormatter.prototype.importSpecifier = function (specifier, node, nodes)
   if (specifier.type !== "ImportBatchSpecifier") templateName += "-key";
 
   nodes.push(util.template(templateName, {
+    inherits: node.specifiers.length === 1 && node,
+
     VARIABLE_NAME: variableName,
     MODULE_NAME:   node.source.raw,
     KEY:           specifier.id
@@ -42,12 +45,14 @@ CommonJSFormatter.prototype.export = function (node, nodes) {
 
     if (t.isClass(ref) || t.isFunction(ref)) {
       if (ref.id) {
-        nodes.push(ref);
+        nodes.push(t.toStatement(ref));
         ref = ref.id;
       }
     }
 
     nodes.push(util.template("exports-default", {
+      inherits: node,
+
       VALUE: ref
     }, true));
   } else {
@@ -58,6 +63,8 @@ CommonJSFormatter.prototype.export = function (node, nodes) {
 
       if (decl.init) {
         decl.init = util.template("exports-assign", {
+          inherits: node,
+
           VALUE: decl.init,
           KEY:   decl.id
         });
@@ -66,6 +73,8 @@ CommonJSFormatter.prototype.export = function (node, nodes) {
       nodes.push(declar);
     } else {
       assign = util.template("exports-assign", {
+        inherits: node,
+
         VALUE: declar.id,
         KEY:   declar.id
       }, true);
@@ -83,15 +92,22 @@ CommonJSFormatter.prototype.export = function (node, nodes) {
 CommonJSFormatter.prototype._exportSpecifier = function (getRef, specifier, node, nodes) {
   var variableName = t.getSpecifierName(specifier);
 
+  var inherits = false;
+  if (node.specifiers.length === 1) inherits = node;
+
   if (node.source) {
     if (t.isExportBatchSpecifier(specifier)) {
       // export * from "foo";
       nodes.push(util.template("exports-wildcard", {
+        inherits: inherits,
+
         OBJECT: getRef()
       }, true));
     } else {
       // export { foo } from "test";
       nodes.push(util.template("exports-assign-key", {
+        inherits: inherits,
+
         VARIABLE_NAME: variableName.name,
         OBJECT:        getRef(),
         KEY:           specifier.id
@@ -100,6 +116,8 @@ CommonJSFormatter.prototype._exportSpecifier = function (getRef, specifier, node
   } else {
     // export { foo };
     nodes.push(util.template("exports-assign", {
+      inherits: inherits,
+
       VALUE: specifier.id,
       KEY:   variableName
     }, true));

lib/6to5/util.js

@@ -113,26 +113,36 @@ exports.template = function (name, nodes, keepExpression) {
 
   template = _.cloneDeep(template);
 
-  if (!_.isEmpty(nodes)) {
-    traverse(template, function (node) {
-      if (t.isIdentifier(node) && _.has(nodes, node.name)) {
-        var newNode = nodes[node.name];
-        if (_.isString(newNode)) {
-          node.name = newNode;
-        } else {
-          return newNode;
+  var inherits = false;
+  if (nodes) {
+    inherits = nodes.inherits;
+    delete nodes.inherits;
+
+    if (!_.isEmpty(nodes)) {
+      traverse(template, function (node) {
+        if (t.isIdentifier(node) && _.has(nodes, node.name)) {
+          var newNode = nodes[node.name];
+          if (_.isString(newNode)) {
+            node.name = newNode;
+          } else {
+            return newNode;
+          }
         }
-      }
-    });
+      });
+    }
   }
 
   var node = template.body[0];
 
   if (!keepExpression && t.isExpressionStatement(node)) {
-    return node.expression;
-  } else {
-    return node;
+    node = node.expression;
   }
+
+  if (inherits) {
+    node = t.inherits(node, inherits);
+  }
+
+  return node;
 };
 
 exports.codeFrame = function (lines, lineNumber, colNumber) {
@@ -227,27 +237,37 @@ exports.parseNoProperties = function (loc, code) {
   return traverse.removeProperties(ast);
 };
 
-try {
-  exports.templates = require("../../templates.json");
-} catch (err) {
-  if (err.code !== "MODULE_NOT_FOUND") throw err;
+var loadTemplates = function () {
+  try {
+    return require("../../templates.json");
+  } catch (err) {
+    if (err.code !== "MODULE_NOT_FOUND") throw err;
 
-  exports.templates = {};
+    var templates = {};
 
-  var templatesLoc = __dirname + "/templates";
-  if (!fs.existsSync(templatesLoc)) {
-    throw new Error("no templates directory - this is most likely the result" +
-                    " of a broken `npm publish`. Please report to " +
-                    "https://githut.com/sebmck/6to5/issues");
+    var templatesLoc = __dirname + "/templates";
+    if (!fs.existsSync(templatesLoc)) {
+      throw new Error("no templates directory - this is most likely the " +
+                      "result of a broken `npm publish`. Please report to " +
+                      "https://githut.com/sebmck/6to5/issues");
+    }
+
+    _.each(fs.readdirSync(templatesLoc), function (name) {
+      if (name[0] === ".") return;
+
+      var key  = path.basename(name, path.extname(name));
+      var loc  = templatesLoc + "/" + name;
+      var code = fs.readFileSync(loc, "utf8");
+
+      templates[key] = exports.parseNoProperties(loc, code);
+    });
+
+    return templates;
   }
+};
 
-  _.each(fs.readdirSync(templatesLoc), function (name) {
-    if (name[0] === ".") return;
-
-    var key  = path.basename(name, path.extname(name));
-    var loc  = templatesLoc + "/" + name;
-    var code = fs.readFileSync(loc, "utf8");
-
-    exports.templates[key] = exports.parseNoProperties(loc, code);
-  });
-}
+Object.defineProperty(exports, "templates", {
+  get: function () {
+    return exports.templates = loadTemplates();
+  }
+});