com.espertech.esper.epl.core
Class OrderByProcessorFactoryImpl

java.lang.Object
  com.espertech.esper.epl.core.OrderByProcessorFactoryImpl

All Implemented Interfaces:

OrderByProcessorFactory

public class OrderByProcessorFactoryImpl
extends java.lang.Object
implements OrderByProcessorFactory

An order-by processor that sorts events according to the expressions in the order_by clause.

Constructor Summary

OrderByProcessorFactoryImpl(java.util.List<OrderByItem> orderByList, ExprNode[] groupByNodes, boolean needsGroupByKeys, boolean isSortUsingCollator)
Ctor.

Method Summary

java.util.Comparator<java.lang.Object>	getComparator()
protected static java.util.Comparator<java.lang.Object>	getComparator(OrderByElement[] orderBy, boolean isSortUsingCollator) Returns a comparator for order items that may sort string values using Collator.
ExprEvaluator[]	getGroupByNodes()
OrderByElement[]	getOrderBy()
OrderByProcessor	instantiate(AggregationService aggregationService, AgentInstanceContext agentInstanceContext)
boolean	isNeedsGroupByKeys()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

OrderByProcessorFactoryImpl

public OrderByProcessorFactoryImpl(java.util.List<OrderByItem> orderByList,
                                   ExprNode[] groupByNodes,
                                   boolean needsGroupByKeys,
                                   boolean isSortUsingCollator)
                            throws ExprValidationException

Ctor.

Parameters:

orderByList - - the nodes that generate the keys to sort events on

groupByNodes - - generate the keys for determining aggregation groups

needsGroupByKeys - - indicates whether this processor needs to have individual group by keys to evaluate the sort condition successfully

isSortUsingCollator - for string value sorting using compare or Collator

Throws:

ExprValidationException - when order-by items don't divulge a type

Method Detail

instantiate

public OrderByProcessor instantiate(AggregationService aggregationService,
                                    AgentInstanceContext agentInstanceContext)

Specified by:

instantiate in interface OrderByProcessorFactory

getOrderBy

public OrderByElement[] getOrderBy()

getGroupByNodes

public ExprEvaluator[] getGroupByNodes()

isNeedsGroupByKeys

public boolean isNeedsGroupByKeys()

getComparator

public java.util.Comparator<java.lang.Object> getComparator()

getComparator

protected static java.util.Comparator<java.lang.Object> getComparator(OrderByElement[] orderBy,
                                                                      boolean isSortUsingCollator)
                                                               throws ExprValidationException

Returns a comparator for order items that may sort string values using Collator.

Parameters:

orderBy - order-by items

isSortUsingCollator - true for Collator string sorting

Returns:

comparator

Throws:

ExprValidationException - if the return type of order items cannot be determined