use scope for uid registry instead of a global registry

lib/6to5/file.js

@@ -17,7 +17,6 @@ function File(opts) {
   this.data             = {};
   this.opts             = File.normaliseOptions(opts);
   this.transformers     = this.getTransformers();
-  this.uids             = {};
   this.ast              = {};
 }
 
@@ -315,8 +314,10 @@ File.prototype.generateUid = function (name, scope) {
   scope = scope || this.scope;
 
   var uid;
+  var i = 0;
   do {
-    uid = this._generateUid(name);
+    uid = this._generateUid(name, i);
+    i++;
   } while (scope.has(uid));
   return uid;
 };
@@ -328,12 +329,8 @@ File.prototype.generateUidIdentifier = function (name, scope) {
   return id;
 };
 
-File.prototype._generateUid = function (name) {
-  var uids = this.uids;
-  var i = uids[name] || 1;
-
+File.prototype._generateUid = function (name, i) {
   var id = name;
   if (i > 1) id += i;
-  uids[name] = i + 1;
   return "_" + id;
 };

lib/6to5/traverse/scope.js

@@ -36,9 +36,20 @@ Scope.defaultDeclarations = _.flatten([
   vars.reservedVars
 ].map(_.keys));
 
-Scope.add = function (node, references, throwOnDuplicate) {
+Scope.prototype._add = function (node, references, throwOnDuplicate) {
   if (!node) return;
-  _.defaults(references, t.getIds(node, true));
+
+  var ids = t.getIds(node, true);
+
+  for (var key in ids) {
+    var id = ids[key];
+
+    if (throwOnDuplicate && references[key]) {
+      throw this.file.errorWithNode(id, "Duplicate declaration");
+    }
+
+    references[key] = id;
+  }
 };
 
 /**
@@ -156,18 +167,31 @@ var functionVariableTraverser = {
   }
 };
 
+var blockVariableTraverser = {
+  enter: function (node, parent, scope, context, add) {
+    if (t.isScope(node)) {
+      return context.skip();
+    }
+
+    if (t.isBlockScoped(node)) {
+      add(node, false, true);
+    }
+  }
+};
+
 Scope.prototype.getInfo = function () {
   var parent = this.parent;
-  var block = this.block;
+  var block  = this.block;
+  var self   = this;
   if (block._scopeInfo) return block._scopeInfo;
 
   var info = block._scopeInfo = {};
   var references = info.references = {};
   var declarations = info.declarations = {};
 
-  var add = function (node, reference) {
-    Scope.add(node, references);
-    if (!reference) Scope.add(node, declarations);
+  var add = function (node, reference, throwOnDuplicate) {
+    self._add(node, references);
+    if (!reference) self._add(node, declarations, throwOnDuplicate);
   };
 
   if (parent && t.isBlockStatement(block) && t.isFor(parent.block)) {
@@ -179,7 +203,7 @@ Scope.prototype.getInfo = function () {
   if (t.isFor(block)) {
     _.each(FOR_KEYS, function (key) {
       var node = block[key];
-      if (t.isBlockScoped(node)) add(node);
+      if (t.isBlockScoped(node)) add(node, false, true);
     });
 
     if (t.isBlockStatement(block.body)) {
@@ -190,10 +214,7 @@ Scope.prototype.getInfo = function () {
   // Program, BlockStatement - let variables
 
   if (t.isBlockStatement(block) || t.isProgram(block)) {
-    _.each(block.body, function (node) {
-      // check for non-var `VariableDeclaration`s
-      if (t.isBlockScoped(node)) add(node);
-    });
+    traverse(block, blockVariableTraverser, this, add);
   }
 
   // CatchClause - param
@@ -211,12 +232,10 @@ Scope.prototype.getInfo = function () {
   // Program, Function - var variables
 
   if (t.isProgram(block) || t.isFunction(block)) {
-    var state = {
+    traverse(block, functionVariableTraverser, this, {
       blockId: block.id,
       add:     add
-    };
-
-    traverse(block, functionVariableTraverser, this, state);
+    });
   }
 
   // Function - params, rest
@@ -264,7 +283,7 @@ Scope.prototype.push = function (opts) {
  */
 
 Scope.prototype.add = function (node) {
-  Scope.add(node, this.references);
+  this._add(node, this.references);
 };
 
 /**

test/fixtures/transformation/es6-arrow-functions/arguments/expected.js

@@ -10,15 +10,15 @@ function one() {
 one(1, 2);
 
 function two() {
-  var _arguments2 = arguments;
+  var _arguments = arguments;
   var inner = function () {
-    return _arguments2;
+    return _arguments;
   };
 
   var another = function () {
-    var _arguments3 = arguments;
+    var _arguments2 = arguments;
     var inner2 = function () {
-      return _arguments3;
+      return _arguments2;
     };
   };
 
@@ -27,18 +27,18 @@ function two() {
 two(1, 2);
 
 function three() {
-  var _arguments4 = arguments;
+  var _arguments = arguments;
   var fn = function () {
-    return _arguments4[0] + "bar";
+    return _arguments[0] + "bar";
   };
   return fn();
 }
 three("foo");
 
 function four() {
-  var _arguments5 = arguments;
+  var _arguments = arguments;
   var fn = function () {
-    return _arguments5[0].foo + "bar";
+    return _arguments[0].foo + "bar";
   };
   return fn();
 }

test/fixtures/transformation/es6-destructuring/parameters/expected.js

@@ -23,25 +23,25 @@ function somethingAdvanced(_ref) {
   var y2 = _ref.bottomRight.y;
 }
 
-function unpackObject(_ref2) {
-  var title = _ref2.title;
-  var author = _ref2.author;
+function unpackObject(_ref) {
+  var title = _ref.title;
+  var author = _ref.author;
   return title + " " + author;
 }
 
 console.log(unpackObject({ title: "title", author: "author" }));
 
-var unpackArray = function (_ref3, _ref4) {
+var unpackArray = function (_ref, _ref3) {
+  var _ref2 = _slicedToArray(_ref, 3);
+
+  var a = _ref2[0];
+  var b = _ref2[1];
+  var c = _ref2[2];
   var _ref32 = _slicedToArray(_ref3, 3);
 
-  var a = _ref32[0];
-  var b = _ref32[1];
-  var c = _ref32[2];
-  var _ref42 = _slicedToArray(_ref4, 3);
-
-  var x = _ref42[0];
-  var y = _ref42[1];
-  var z = _ref42[2];
+  var x = _ref32[0];
+  var y = _ref32[1];
+  var z = _ref32[2];
   return a + b + c;
 };
 

test/fixtures/transformation/es6-parameters.rest/multiple/expected.js

@@ -7,7 +7,7 @@ var t = function (f) {
 };
 
 function t(f) {
-  for (var _len2 = arguments.length, items = Array(_len2 > 1 ? _len2 - 1 : 0), _key2 = 1; _key2 < _len2; _key2++) {
-    items[_key2 - 1] = arguments[_key2];
+  for (var _len = arguments.length, items = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
+    items[_key - 1] = arguments[_key];
   }
 }

test/fixtures/transformation/es6-parameters.rest/single/expected.js

@@ -7,7 +7,7 @@ var t = function () {
 };
 
 function t() {
-  for (var _len2 = arguments.length, items = Array(_len2), _key2 = 0; _key2 < _len2; _key2++) {
-    items[_key2] = arguments[_key2];
+  for (var _len = arguments.length, items = Array(_len), _key = 0; _key < _len; _key++) {
+    items[_key] = arguments[_key];
   }
 }