presto-main/src/main/java/io/prestosql/operator/TopNRowNumberOperator.java/TopNRowNumberOperatorFactory/createOperator
class TopNRowNumberOperatorFactory:        @Override
        public Operator createOperator(DriverContext driverContext)
        {
            checkState(!closed, "Factory is already closed");
            OperatorContext operatorContext = driverContext.addOperatorContext(operatorId, planNodeId, TopNRowNumberOperator.class.getSimpleName());
            return new TopNRowNumberOperator(
                    operatorContext,
                    sourceTypes,
                    outputChannels,
                    partitionChannels,
                    partitionTypes,
                    sortChannels,
                    sortOrder,
                    maxRowCountPerPartition,
                    generateRowNumber,
                    hashChannel,
                    expectedPositions,
                    joinCompiler);
        }