Index: gears/database2/statement.h
===================================================================
--- gears/database2/statement.h	(revision 1639)
+++ gears/database2/statement.h	(working copy)
@@ -33,42 +33,73 @@
 // forward declarations
 class Database2;
 class Database2Transaction;
+class Database2Values;
 
-// represents Database2Statement
+// represents statement, for both synchronous and asynchronous operations
 class Database2Statement {
  public:
-  Database2Statement() {}
-
   bool HasCallback() const {
-    assert(callback_.get());
-    return !JsTokenIsNullOrUndefined(callback_->token());
+    return callback_.get() != NULL;
   }
 
   bool HasErrorCallback() const {
-    assert(error_callback_.get());
-    return !JsTokenIsNullOrUndefined(error_callback_->token());
+    return error_callback_.get() != NULL;
   }
 
   void InvokeCallback(Database2Transaction *tx);
   void InvokeErrorCallback(Database2Transaction *tx, JsObject *error);
 
+  // create a statement instance
+  // must passs NULL for arguments or callbacks if they are not specified
   static bool Create(const std::string16 &sql_statement,
-                     const JsArray &sql_arguments,
+                     JsArray *sql_arguments,
                      JsRootedCallback *callback,
                      JsRootedCallback *error_callback,
                      Database2Statement **instance);
 
   std::string16 sql() const { return sql_statement_; }
-  JsParamToSend *arguments() const { return sql_arguments_; }
-  int num_arguments() const { return num_arguments_; }
+  Database2Values *arguments() const { return arguments_.get(); }
  private:
+  Database2Statement() {}
+  // if true, the statement has invalid arguments
+  bool bogus_;
   std::string16 sql_statement_;
-  int num_arguments_;
-  JsParamToSend *sql_arguments_;
+  scoped_ptr<Database2Values> arguments_;
   scoped_ptr<JsRootedCallback> callback_;
   scoped_ptr<JsRootedCallback> error_callback_;
 
   DISALLOW_EVIL_CONSTRUCTORS(Database2Statement);
 };
 
+// Used for marshaling statement arguments to the database thread and
+// results to the main thread.
+// JsParamToSend is used to store the value-type pairs, and as a result the 
+// values are heap-allocated, which is unfortunate in the case of int/double.
+// TODO(dimitri.glazkov): Reimplement using unions, possibly reusing or
+// integrating with MarshaledJsToken
+class Database2Values {
+ public:
+  ~Database2Values();
+
+  static bool CreateFromJsArray(const JsArray *sql_arguments,
+                                Database2Values **instance);
+
+  int length() const { return length_; }
+  JsParamType GetType(int index) const;
+  int GetAsInt(int index) const;
+  double GetAsDouble(int index) const;
+  std::string16 &GetAsString(int index) const;
+ private:
+  Database2Values() {}
+
+  static bool SetJsParamToSend(const JsArray *js_array,
+                               int index,
+                               JsParamToSend *param);
+
+  scoped_array<JsParamToSend> arguments_;
+  int length_;
+
+  DISALLOW_EVIL_CONSTRUCTORS(Database2Values);
+};
+
 #endif // GEARS_DATABASE2_STATEMENT_H__