implement new and improved let scoping - fixes #91, fixes #102, fixes #124

lib/6to5/scope.js

@@ -6,24 +6,23 @@ var _        = require("lodash");
 
 function Scope(parent, block) {
   this.parent = parent;
+  this.block  = block;
   this.ids    = block._scopeIds = block._scopeIds || Scope.getIds(block);
 }
 
 Scope.getIds = function (block) {
-  var ids = [];
+  var ids = {};
 
   if (t.isBlockStatement(block)) {
     _.each(block.body, function (node) {
       if (t.isVariableDeclaration(node) && node.kind !== "var") {
-        ids = ids.concat(t.getIds(node));
+        ids = t.getIds(node, true);
       }
     });
-  }
-
-  if (t.isProgram(block) || t.isFunction(block)) {
+  } else if (t.isProgram(block) || t.isFunction(block)) {
     traverse(block, function (node) {
       if (t.isVariableDeclaration(node) && node.kind === "var") {
-        ids = ids.concat(t.getIds(node));
+        ids = t.getIds(node, true);
       } else if (t.isFunction(node)) {
         return false;
       }
@@ -32,16 +31,33 @@ Scope.getIds = function (block) {
 
   if (t.isFunction(block)) {
     _.each(block.params, function (param) {
-      ids = ids.concat(t.getIds(param));
+      _.merge(ids, t.getIds(param, true));
     });
   }
 
   return ids;
 };
 
-Scope.prototype.has = function (id, noParent) {
-  if (!id) return false;
-  if (_.contains(this.ids, id)) return true;
-  if (noParent !== false && this.parent) return this.parent.has(id);
-  return false;
+Scope.prototype.get = function (id) {
+  return id && (this.getOwn(id) || this.parentGet(id));
+};
+
+Scope.prototype.getOwn = function (id) {
+  return _.has(this.ids, id) && this.ids[id];
+};
+
+Scope.prototype.parentGet = function (id) {
+  return this.parent && this.parent.get(id);
+};
+
+Scope.prototype.has = function (id) {
+  return id && (this.hasOwn(id) || this.parentHas(id));
+};
+
+Scope.prototype.hasOwn = function (id) {
+  return !!this.getOwn(id);
+};
+
+Scope.prototype.parentHas = function (id) {
+  return this.parent && this.parent.has(id);
 };