if (null == stmt) {
msgBuilder.append("(Could not parse command)");
return new QuerySubmitResponse(msgBuilder.toString(), null);
}
stmt.accept(new AssignFieldLabelsVisitor());
stmt.accept(new CountStarVisitor()); // Must be after assign labels, before TC.
stmt.accept(new TypeChecker(mRootSymbolTable));
stmt.accept(new ReplaceWindows()); // Must be after TC.
stmt.accept(new JoinKeyVisitor()); // Must be after TC.
stmt.accept(new JoinNameVisitor());