WindowFunctionInfo(FunctionInfo fInfo)
{
assert fInfo.isGenericUDAF();
this.fInfo = fInfo;
Class<? extends GenericUDAFResolver> wfnCls = fInfo.getGenericUDAFResolver().getClass();
WindowFunctionDescription def = wfnCls.getAnnotation(WindowFunctionDescription.class);
if ( def != null)
{
supportsWindow = def.supportsWindow();
pivotResult = def.pivotResult();
}
}