void CreateRootBuilder (Stream inputStream, string filename)
{
if (rootBuilder != null)
return;
Type rootBuilderType = GetRootBuilderType (inputStream, filename);
rootBuilder = Activator.CreateInstance (rootBuilderType) as RootBuilder;
if (rootBuilder == null)
throw new HttpException ("Cannot create an instance of file-level control builder.");
rootBuilder.Init (tparser, null, null, null, null, null);
if (componentFoundry != null)
rootBuilder.Foundry = componentFoundry;
stack.Push (rootBuilder, null);
tparser.RootBuilder = rootBuilder;
}