[compiler] Add a traversing AST visitor

src/ast/ast.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_AST_AST_H_
 #define V8_AST_AST_H_
 
 #include "src/assembler.h"
 #include "src/ast/ast-value-factory.h"
 #include "src/ast/modules.h"
@@ skipping 3029 matching lines @@
 // `at` and `Set`.
 #define AST_REWRITE_LIST_ELEMENT(Type, list, index)                        \
   do {                                                                     \
     auto _list = (list);                                                   \
     auto _index = (index);                                                 \
     AST_REWRITE(Type, _list->at(_index), _list->Set(_index, replacement)); \
   } while (false)
 
 
 // ----------------------------------------------------------------------------
+// Traversing visitor
+// - fully traverses the entire AST.
+
+class AstTraversalVisitor : public AstVisitor {
+ public:
+  explicit AstTraversalVisitor(Isolate* isolate);
+  virtual ~AstTraversalVisitor() {}
+
+  // Iteration left-to-right.
+  void VisitDeclarations(ZoneList<Declaration*>* declarations) override;
+  void VisitStatements(ZoneList<Statement*>* statements) override;
+  void VisitExpressions(ZoneList<Expression*>* expressions) override;
+
+// Individual nodes
+#define DECLARE_VISIT(type) void Visit##type(type* node) override;
+  AST_NODE_LIST(DECLARE_VISIT)
+#undef DECLARE_VISIT
+
+ private:
+  DEFINE_AST_VISITOR_SUBCLASS_MEMBERS();
+  DISALLOW_COPY_AND_ASSIGN(AstTraversalVisitor);
+};
+
+// ----------------------------------------------------------------------------
 // AstNode factory
 
 class AstNodeFactory final BASE_EMBEDDED {
  public:
   explicit AstNodeFactory(AstValueFactory* ast_value_factory)
       : local_zone_(ast_value_factory->zone()),
         parser_zone_(ast_value_factory->zone()),
         ast_value_factory_(ast_value_factory) {}
 
   AstValueFactory* ast_value_factory() const { return ast_value_factory_; }
@@ skipping 484 matching lines @@
                                     : NULL;                                   \
   }
 AST_NODE_LIST(DECLARE_NODE_FUNCTIONS)
 #undef DECLARE_NODE_FUNCTIONS
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_AST_H_