add a "spec" transformer namespace for transformers that nicen up code and make it well, more spec compliant

lib/6to5/transformation/transform.js

@@ -20,16 +20,21 @@ transform._ensureTransformerNames = function (type, keys) {
 transform.transformers = {};
 
 transform.moduleFormatters = {
-  common:        require("./modules/common"),
-  commonInterop: require("./modules/common-interop"),
-  system:        require("./modules/system"),
-  ignore:        require("./modules/ignore"),
-  amd:           require("./modules/amd"),
-  umd:           require("./modules/umd")
+  commonStrict: require("./modules/common-strict"),
+  common:       require("./modules/common"),
+  system:       require("./modules/system"),
+  ignore:       require("./modules/ignore"),
+  amd:          require("./modules/amd"),
+  umd:          require("./modules/umd")
 };
 
 _.each({
-  // plyground
+  // spec
+  _blockHoistFunctions:      require("./transformers/spec-block-hoist-functions"),
+  _noForInOfAssignment:      require("./transformers/spec-no-for-in-of-assignment"),
+  _noDuplicateProperties:    require("./transformers/spec-no-duplicate-properties"),
+
+  // playground
   methodBinding:             require("./transformers/playground-method-binding"),
   memoizationOperator:       require("./transformers/playground-memoization-operator"),
   objectGetterMemoization:   require("./transformers/playground-object-getter-memoization"),
@@ -59,16 +64,18 @@ _.each({
   constants:                 require("./transformers/es6-constants"),
   letScoping:                require("./transformers/es6-let-scoping"),
 
-  generators:                require("./transformers/es6-generators"),
-
   _blockHoist:               require("./transformers/_block-hoist"),
   _declarations:             require("./transformers/_declarations"),
+
+  generators:                require("./transformers/es6-generators"),
+
+  // spec
+  _propertyLiterals:         require("./transformers/spec-property-literals"),
+  _memberExpressioLiterals:  require("./transformers/spec-member-expression-literals"),
+
+  // wrap up
   _aliasFunctions:           require("./transformers/_alias-functions"),
-
   useStrict:                 require("./transformers/use-strict"),
-
-  _propertyLiterals:         require("./transformers/_property-literals"),
-  _memberExpressioLiterals:  require("./transformers/_member-expression-literals"),
   _moduleFormatter:          require("./transformers/_module-formatter")
 }, function (transformer, key) {
   transform.transformers[key] = new Transformer(key, transformer);

lib/6to5/transformation/transformers/spec-block-hoist-functions.js

@@ -0,0 +1,19 @@
+var t = require("../../types");
+var _ = require("lodash");
+
+exports.BlockStatement = function (node, parent) {
+  if (t.isFunction(parent)) return;
+
+  node.body = node.body.map(function (node) {
+    if (t.isFunction(node)) {
+      node.type = "FunctionExpression";
+      var declar = t.variableDeclaration("let", [
+        t.variableDeclarator(node.id, node)
+      ]);
+      declar._blockHoist = true;
+      return declar;
+    } else {
+      return node;
+    }
+  });
+};

lib/6to5/transformation/transformers/spec-no-duplicate-properties.js

@@ -0,0 +1,25 @@
+var t = require("../../types");
+var _ = require("lodash");
+
+exports.ObjectExpression = function (node, parent, file) {
+  var keys = [];
+
+  _.each(node.properties, function (prop) {
+    if (prop.computed || prop.kind !== "init") return;
+
+    var key = prop.key;
+    if (t.isIdentifier(key)) {
+      key = key.name;
+    } else if (t.isLiteral(key)) {
+      key = key.value;
+    } else {
+      return;
+    }
+
+    if (_.contains(keys, key)) {
+      throw file.errorWithNode(prop.key, "Duplicate property key");
+    } else {
+      keys.push(key);
+    }
+  });
+};

lib/6to5/transformation/transformers/spec-no-for-in-of-assignment.js

@@ -0,0 +1,10 @@
+var t = require("../../types");
+
+exports.ForInStatement =
+exports.ForOfStatement = function (node, parent, file) {
+  var left = node.left;
+  if (t.isVariableDeclaration(left)) {
+    var declar = left.declarations[0];
+    if (declar.init) throw file.errorWithNode(declar, "No assignments allowed in for-in/of head");
+  }
+};