com.espertech.esper.view.std

Class GroupByViewFactory

java.lang.Object

com.espertech.esper.view.std.GroupByViewFactory

All Implemented Interfaces:

GroupByViewFactoryMarker, ViewFactory

public class GroupByViewFactory
extends Object
implements ViewFactory, GroupByViewFactoryMarker

Factory for GroupByView instances.

Field Summary

Fields

Modifier and Type	Field and Description
protected ExprEvaluator[]	criteriaExpressionEvals
protected ExprNode[]	criteriaExpressions List of criteria expressions.
protected boolean	isReclaimAged
protected double	reclaimFrequency
protected double	reclaimMaxAge
protected List<ExprNode>	viewParameters View parameters.

Constructor Summary

Constructors

Constructor and Description
GroupByViewFactory()

Method Summary

Modifier and Type	Method and Description
void	attach(EventType parentEventType, StatementContext statementContext, ViewFactory optionalParentFactory, List<ViewFactory> parentViewFactories) Attaches the factory to a parent event type such that the factory can validate attach requirements and determine an event type for resulting views.
boolean	canReuse(View view, AgentInstanceContext agentInstanceContext) Determines if the given view could be used instead of creating a new view, requires the view factory to compare view type, parameters and other capabilities provided.
ExprEvaluator[]	getCriteriaExpressionEvals()
ExprNode[]	getCriteriaExpressions() Returns the names of fields to group by
EventType	getEventType() Returns the event type that the view that is created by the view factory would create for events posted by the view.
double	getReclaimFrequency()
double	getReclaimMaxAge()
String	getViewName() Returns the name of the view, not namespace+name but readable name.
boolean	isReclaimAged()
View	makeView(AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext) Create a new view.
void	setViewParameters(ViewFactoryContext viewFactoryContext, List<ExprNode> expressionParameters) Indicates user EPL query view parameters to the view factory.

Methods inherited from class java.lang.Object

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

Field Detail

viewParameters

protected List<ExprNode> viewParameters

View parameters.

criteriaExpressions

protected ExprNode[] criteriaExpressions

List of criteria expressions.

criteriaExpressionEvals

protected ExprEvaluator[] criteriaExpressionEvals

isReclaimAged

protected boolean isReclaimAged

reclaimMaxAge

protected double reclaimMaxAge

reclaimFrequency

protected double reclaimFrequency

Constructor Detail

GroupByViewFactory

public GroupByViewFactory()

Method Detail

setViewParameters

public void setViewParameters(ViewFactoryContext viewFactoryContext,
                              List<ExprNode> expressionParameters)
                       throws ViewParameterException

Description copied from interface: ViewFactory

Indicates user EPL query view parameters to the view factory.

Specified by:

setViewParameters in interface ViewFactory

Parameters:

viewFactoryContext - supplied context information for the view factory

expressionParameters - is the objects representing the view parameters

Throws:

ViewParameterException - if the parameters don't match view parameter needs

attach

public void attach(EventType parentEventType,
                   StatementContext statementContext,
                   ViewFactory optionalParentFactory,
                   List<ViewFactory> parentViewFactories)
            throws ViewParameterException

Description copied from interface: ViewFactory

Attaches the factory to a parent event type such that the factory can validate attach requirements and determine an event type for resulting views.

Specified by:

attach in interface ViewFactory

Parameters:

parentEventType - is the parent event stream's or view factory's event type

statementContext - contains the services needed for creating a new event type

optionalParentFactory - is null when there is no parent view factory, or contains the parent view factory

parentViewFactories - is a list of all the parent view factories or empty list if there are none

Throws:

ViewParameterException - is thrown to indicate that this view factories's view would not play with the parent view factories view

getCriteriaExpressions

public ExprNode[] getCriteriaExpressions()

Returns the names of fields to group by

Specified by:

getCriteriaExpressions in interface GroupByViewFactoryMarker

Returns:

field names

makeView

public View makeView(AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext)

Description copied from interface: ViewFactory

Create a new view.

Specified by:

makeView in interface ViewFactory

Parameters:

agentInstanceViewFactoryContext - context

Returns:

view

getEventType

public EventType getEventType()

Description copied from interface: ViewFactory

Returns the event type that the view that is created by the view factory would create for events posted by the view.

Specified by:

getEventType in interface ViewFactory

Returns:

event type of view's created by the view factory

canReuse

public boolean canReuse(View view,
                        AgentInstanceContext agentInstanceContext)

Description copied from interface: ViewFactory

Determines if the given view could be used instead of creating a new view, requires the view factory to compare view type, parameters and other capabilities provided.

Specified by:

canReuse in interface ViewFactory

Parameters:

view - is the candidate view to compare to

agentInstanceContext - agent instance context

Returns:

true if the given view can be reused instead of creating a new view, or false to indicate the view is not right for reuse

isReclaimAged

public boolean isReclaimAged()

Specified by:

isReclaimAged in interface GroupByViewFactoryMarker

getReclaimMaxAge

public double getReclaimMaxAge()

getReclaimFrequency

public double getReclaimFrequency()

getViewName

public String getViewName()

Description copied from interface: ViewFactory

Returns the name of the view, not namespace+name but readable name.

Specified by:

getViewName in interface ViewFactory

Returns:

readable name

getCriteriaExpressionEvals

public ExprEvaluator[] getCriteriaExpressionEvals()