switch scope tracking to a path based system

src/babel/transformation/file.js

@@ -1,6 +1,7 @@
 import convertSourceMap from "convert-source-map";
 import shebangRegex from "shebang-regex";
 import isFunction from "lodash/lang/isFunction";
+import TraversalPath from "../traversal/path";
 import sourceMap from "source-map";
 import transform from "./index";
 import generate from "../generation";
@@ -375,7 +376,7 @@ export default class File {
     this.usedHelpers[name] = true;
 
     var generator = this.get("helperGenerator");
-    var runtime = this.get("helpersNamespace");
+    var runtime   = this.get("helpersNamespace");
     if (generator) {
       return generator(name);
     } else if (runtime) {
@@ -425,9 +426,11 @@ export default class File {
   transform(ast) {
     this.log.debug();
 
-    this.ast = ast;
+    this.path  = TraversalPath.get(null, null, ast, ast, "program", this);
+    this.scope = this.path.scope;
+    this.ast   = ast;
+
     this.lastStatements = t.getLastStatements(ast.program);
-    this.scope = new Scope(ast.program, ast, null, this);
 
     var modFormatter = this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
     if (modFormatter.init && this.transformers["es6.modules"].canRun()) {
@@ -481,14 +484,14 @@ export default class File {
     if (inputMap) {
       map.sources[0] = inputMap.file;
 
-      var inputMapConsumer = new sourceMap.SourceMapConsumer(inputMap);
-      var outputMapConsumer = new sourceMap.SourceMapConsumer(map);
+      var inputMapConsumer   = new sourceMap.SourceMapConsumer(inputMap);
+      var outputMapConsumer  = new sourceMap.SourceMapConsumer(map);
       var outputMapGenerator = sourceMap.SourceMapGenerator.fromSourceMap(outputMapConsumer);
       outputMapGenerator.applySourceMap(inputMapConsumer);
 
       var mergedMap = outputMapGenerator.toJSON();
       mergedMap.sources = inputMap.sources
-      mergedMap.file = inputMap.file;
+      mergedMap.file    = inputMap.file;
       return mergedMap;
     }
 

src/babel/transformation/transformers/es6/for-of.js

@@ -29,9 +29,6 @@ export function ForOfStatement(node, parent, scope, file) {
 
   t.inherits(loop, node);
 
-  // todo: find out why this is necessary? #538
-  loop._scopeInfo = node._scopeInfo;
-
   if (build.replaceParent) {
     this.parentPath.node = build.node;
   } else {

src/babel/traversal/path.js

@@ -10,7 +10,7 @@ export default class TraversalPath {
     this.data      = {};
   }
 
-  static get(parentPath, context, parent, container, key) {
+  static get(parentPath: TraversalPath, context?: TraversalContext, parent, container, key, file?: File) {
     var targetNode = container[key];
     var paths = container._paths ||= [];
     var path;
@@ -28,17 +28,17 @@ export default class TraversalPath {
       paths.push(path);
     }
 
-    path.setContext(parentPath, context, key);
+    path.setContext(parentPath, context, key, file);
 
     return path;
   }
 
-  static getScope(node, parent, scope) {
+  static getScope(path: TraversalPath, scope: Scope, file?: File) {
     var ourScope = scope;
 
     // we're entering a new scope so let's construct it!
-    if (t.isScope(node, parent)) {
-      ourScope = new Scope(node, parent, scope);
+    if (path.isScope()) {
+      ourScope = new Scope(path, scope, file);
     }
 
     return ourScope;
@@ -60,21 +60,24 @@ export default class TraversalPath {
     return this.data[key];
   }
 
-  setScope() {
-    this.scope = TraversalPath.getScope(this.node, this.parent, this.context.scope);
+  setScope(file?) {
+    this.scope = TraversalPath.getScope(this, this.context && this.context.scope, file);
   }
 
-  setContext(parentPath, context, key) {
+  setContext(parentPath, context, key, file?) {
     this.shouldSkip = false;
     this.shouldStop = false;
 
     this.parentPath = parentPath || this.parentPath;
-    this.context    = context;
-    this.state      = context.state;
-    this.opts       = context.opts;
     this.key        = key;
 
-    this.setScope();
+    if (context) {
+      this.context = context;
+      this.state   = context.state;
+      this.opts    = context.opts;
+    }
+
+    this.setScope(file);
   }
 
   remove() {
@@ -200,6 +203,10 @@ export default class TraversalPath {
     return TraversalPath.get(this, this.context, this.node, this.node, key);
   }
 
+  isScope() {
+    return t.isScope(this.node, this.parent);
+  }
+
   isReferencedIdentifier(opts) {
     return t.isReferencedIdentifier(this.node, this.parent, opts);
   }

src/babel/traversal/scope.js

@@ -65,12 +65,20 @@ export default class Scope {
    * within.
    */
 
-  constructor(block: Object, parentBlock: Object, parent?: Scope, file?: File) {
+  constructor(path: TraversalPath, parent?: Scope, file?: File) {
+    var cached = path.getData("scope");
+    if (cached) {
+      return cached;
+    } else {
+      path.setData("scope", this);
+    }
+
     this.parent = parent;
     this.file   = parent ? parent.file : file;
 
-    this.parentBlock = parentBlock;
-    this.block       = block;
+    this.parentBlock = path.parent;
+    this.block       = path.node;
+    this.path        = path;
 
     this.crawl();
   }
@@ -472,7 +480,7 @@ export default class Scope {
    */
 
   recrawl() {
-    this.block._scopeInfo = null;
+    this.path.setData("scopeInfo", null);
     this.crawl();
   }
 
@@ -481,21 +489,21 @@ export default class Scope {
    */
 
   crawl() {
-    var block  = this.block;
+    var block = this.block;
     var i;
 
     //
 
-    var info = block._scopeInfo;
+    var info = this.path.getData("scopeInfo");
     if (info) {
       extend(this, info);
       return;
     }
 
-    info = block._scopeInfo = {
+    info = this.path.setData("scopeInfo", {
       bindings: object(),
       globals:  object()
-    };
+    });
 
     extend(this, info);