[parser] Refactor AstTraversalVisitor

src/debug/liveedit.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_DEBUG_LIVEEDIT_H_
 #define V8_DEBUG_LIVEEDIT_H_
 
 
 // Live Edit feature implementation.
 // User should be able to change script on already running VM. This feature
@@ skipping 20 matching lines @@
 namespace v8 {
 namespace internal {
 
 // This class collects some specific information on structure of functions
 // in a particular script.
 //
 // The primary interest of the Tracker is to record function scope structures
 // in order to analyze whether function code may be safely patched (with new
 // code successfully reading existing data from function scopes). The Tracker
 // also collects compiled function codes.
-class LiveEditFunctionTracker : public AstTraversalVisitor {
+class LiveEditFunctionTracker
+    : public AstTraversalVisitor<LiveEditFunctionTracker> {
  public:
   // Traverses the entire AST, and records information about all
   // FunctionLiterals for further use by LiveEdit code patching. The collected
   // information is returned as a serialized array.
   static Handle<JSArray> Collect(FunctionLiteral* node, Handle<Script> script,
                                  Zone* zone, Isolate* isolate);
 
-  virtual ~LiveEditFunctionTracker() {}
-  void VisitFunctionLiteral(FunctionLiteral* node) override;
+ protected:
+  friend AstTraversalVisitor<LiveEditFunctionTracker>;
+  void VisitFunctionLiteral(FunctionLiteral* node);
 
  private:
   LiveEditFunctionTracker(Handle<Script> script, Zone* zone, Isolate* isolate);
 
   void FunctionStarted(FunctionLiteral* fun);
   void FunctionDone(Handle<SharedFunctionInfo> shared, Scope* scope);
   Handle<Object> SerializeFunctionScope(Scope* scope);
 
   Handle<Script> script_;
   Zone* zone_;
@@ skipping 309 matching lines @@
   static const int kSharedInfoOffset_ = 3;
   static const int kSize_ = 4;
 
   friend class JSArrayBasedStruct<SharedInfoWrapper>;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif /* V8_DEBUG_LIVEEDIT_H_ */