Optimizing nested, constant object literals (like JSON objects) by building o...

src/parser.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 140 matching lines @@
   Expression* ParseMemberExpression(bool* ok);
   Expression* ParseMemberWithNewPrefixesExpression(List<int>* new_prefixes,
                                                    bool* ok);
   Expression* ParsePrimaryExpression(bool* ok);
   Expression* ParseArrayLiteral(bool* ok);
   Expression* ParseObjectLiteral(bool* ok);
   Expression* ParseRegExpLiteral(bool seen_equal, bool* ok);
 
   // Decide if a property should be the object boilerplate.
   bool IsBoilerplateProperty(ObjectLiteral::Property* property);
-  // If the property is CONSTANT type, it returns the literal value,
-  // otherwise, it return undefined literal as the placeholder
+  // If the property is CONSTANT type, return the literal value;
+  // if the property is OBJECT_LITERAL and the object literal is
+  // simple return a fixed array containing the keys and values of the
+  // object literal.
+  // Otherwise, it return undefined literal as the placeholder

[Mads Ager (chromium), 2009/03/06 09:30:54]

it return -> return.

   // in the object literal boilerplate.
-  Literal* GetBoilerplateValue(ObjectLiteral::Property* property);
+  Handle<Object> GetBoilerplateValue(ObjectLiteral::Property* property);
 
   enum FunctionLiteralType {
     EXPRESSION,
     DECLARATION,
     NESTED
   };
 
   ZoneList<Expression*>* ParseArguments(bool* ok);
   FunctionLiteral* ParseFunctionLiteral(Handle<String> var_name,
                                         int function_token_position,
@@ skipping 2901 matching lines @@
   return NEW(ArrayLiteral(literals, values.elements()));
 }
 
 
 bool Parser::IsBoilerplateProperty(ObjectLiteral::Property* property) {
   return property != NULL &&
          property->kind() != ObjectLiteral::Property::PROTOTYPE;
 }
 
 
-Literal* Parser::GetBoilerplateValue(ObjectLiteral::Property* property) {
+Handle<Object> Parser::GetBoilerplateValue(ObjectLiteral::Property* property) {
   if (property->kind() == ObjectLiteral::Property::CONSTANT)
-    return property->value()->AsLiteral();
-  return GetLiteralUndefined();
+    return property->value()->AsLiteral()->handle();
+  if (property->kind() == ObjectLiteral::Property::OBJECT_LITERAL) {
+    ObjectLiteral* object_literal = property->value()->AsObjectLiteral();
+    if (object_literal->is_simple()) {
+      return object_literal->constant_properties();
+    }
+  }
+  return Factory::undefined_value();
 }
 
 
 Expression* Parser::ParseObjectLiteral(bool* ok) {
   // ObjectLiteral ::
   //   '{' (
   //       ((Identifier | String | Number) ':' AssignmentExpression)
   //     | (('get' | 'set') FunctionLiteral)
   //    )*[','] '}'
 
@@ skipping 74 matching lines @@
     if (peek() != Token::RBRACE) Expect(Token::COMMA, CHECK_OK);
   }
   Expect(Token::RBRACE, CHECK_OK);
   // Computation of literal_index must happen before pre parse bailout.
   int literal_index = temp_scope_->NextMaterializedLiteralIndex();
   if (is_pre_parsing_) return NULL;
 
   Handle<FixedArray> constant_properties =
       Factory::NewFixedArray(number_of_boilerplate_properties * 2, TENURED);
   int position = 0;
+  bool is_simple = true;
   for (int i = 0; i < properties.length(); i++) {
     ObjectLiteral::Property* property = properties.at(i);
-    if (!IsBoilerplateProperty(property)) continue;
+    if (!IsBoilerplateProperty(property)) {
+      is_simple = false;
+      continue;
+    }
 
     // Add CONSTANT and COMPUTED properties to boilerplate. Use undefined
     // value for COMPUTED properties, the real value is filled in at
     // runtime. The enumeration order is maintained.
     Handle<Object> key = property->key()->handle();
-    Literal* literal = GetBoilerplateValue(property);
+    Handle<Object> value = GetBoilerplateValue(property);
+    is_simple = is_simple && !value->IsUndefined();
 
     // Add name, value pair to the fixed array.
     constant_properties->set(position++, *key);
-    constant_properties->set(position++, *literal->handle());
+    constant_properties->set(position++, *value);
   }
 
   return new ObjectLiteral(constant_properties,
                            properties.elements(),
-                           literal_index);
+                           literal_index,
+                           is_simple);
 }
 
 
 Expression* Parser::ParseRegExpLiteral(bool seen_equal, bool* ok) {
   if (!scanner_.ScanRegExpPattern(seen_equal)) {
     Next();
     ReportMessage("unterminated_regexp", Vector<const char*>::empty());
     *ok = false;
     return NULL;
   }
@@ skipping 1301 matching lines @@
                        start_position,
                        is_expression);
   return result;
 }
 
 
 #undef NEW
 
 
 } }  // namespace v8::internal