com.espertech.esper.epl.expression.prev

Class ExprPreviousNode

java.lang.Object

com.espertech.esper.epl.expression.core.ExprNodeBase

com.espertech.esper.epl.expression.prev.ExprPreviousNode

All Implemented Interfaces:

ExprEvaluator, ExprEvaluatorEnumeration, ExprNode, ExprValidator, MetaDefItem, Serializable

public class ExprPreviousNode
extends ExprNodeBase
implements ExprEvaluator, ExprEvaluatorEnumeration

Represents the 'prev' previous event function in an expression node tree.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ExprPreviousNode(ExprPreviousNodePreviousType previousType)

Method Summary

Modifier and Type	Method and Description
boolean	equalsNode(ExprNode node, boolean ignoreStreamPrefix) Return true if a expression node semantically equals the current node, or false if not.
Object	evaluate(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext) Evaluate event tuple and return result.
EventBean	evaluateGetEventBean(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext context)
Collection<EventBean>	evaluateGetROCollectionEvents(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext context)
Collection	evaluateGetROCollectionScalar(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext context)
Class	getComponentTypeCollection()
Integer	getConstantIndexNumber()
EventType	getEventTypeCollection(EventAdapterService eventAdapterService, int statementId)
EventType	getEventTypeSingle(EventAdapterService eventAdapterService, int statementId)
ExprEvaluator	getExprEvaluator()
ExprPrecedenceEnum	getPrecedence() Returns precedence.
ExprPreviousNodePreviousType	getPreviousType()
Class	getResultType()
int	getStreamNumber()
Class	getType() Returns the type that the node's evaluate method returns an instance of.
int	hashCode()
boolean	isConstantIndex()
boolean	isConstantResult() Returns true if the expression node's evaluation value doesn't depend on any events data, as must be determined at validation time, which is bottom-up and therefore reliably allows each node to determine constant value.
void	setEvaluator(ExprPreviousEvalStrategy evaluator)
void	toPrecedenceFreeEPL(StringWriter writer)
ExprNode	validate(ExprValidationContext validationContext)

Methods inherited from class com.espertech.esper.epl.expression.core.ExprNodeBase

accept, accept, acceptChildnodes, addChildNode, addChildNodes, addChildNodeToFront, getChildNodes, replaceUnlistedChildNode, setChildNode, setChildNodes, toEPL

Methods inherited from class java.lang.Object

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

Constructor Detail

ExprPreviousNode

public ExprPreviousNode(ExprPreviousNodePreviousType previousType)

Method Detail

getExprEvaluator

public ExprEvaluator getExprEvaluator()

Specified by:

getExprEvaluator in interface ExprNode

setEvaluator

public void setEvaluator(ExprPreviousEvalStrategy evaluator)

getStreamNumber

public int getStreamNumber()

getConstantIndexNumber

public Integer getConstantIndexNumber()

isConstantIndex

public boolean isConstantIndex()

getResultType

public Class getResultType()

validate

public ExprNode validate(ExprValidationContext validationContext)
                  throws ExprValidationException

Specified by:

validate in interface ExprValidator

Throws:

ExprValidationException

getPreviousType

public ExprPreviousNodePreviousType getPreviousType()

getType

public Class getType()

Description copied from interface: ExprEvaluator

Returns the type that the node's evaluate method returns an instance of.

Specified by:

getType in interface ExprEvaluator

Returns:

type returned when evaluated

isConstantResult

public boolean isConstantResult()

Description copied from interface: ExprNode

Returns true if the expression node's evaluation value doesn't depend on any events data, as must be determined at validation time, which is bottom-up and therefore reliably allows each node to determine constant value.

Specified by:

isConstantResult in interface ExprNode

Returns:

true for constant evaluation value, false for non-constant evaluation value

evaluateGetROCollectionEvents

public Collection<EventBean> evaluateGetROCollectionEvents(EventBean[] eventsPerStream,
                                                           boolean isNewData,
                                                           ExprEvaluatorContext context)

Specified by:

evaluateGetROCollectionEvents in interface ExprEvaluatorEnumeration

evaluateGetEventBean

public EventBean evaluateGetEventBean(EventBean[] eventsPerStream,
                                      boolean isNewData,
                                      ExprEvaluatorContext context)

Specified by:

evaluateGetEventBean in interface ExprEvaluatorEnumeration

evaluateGetROCollectionScalar

public Collection evaluateGetROCollectionScalar(EventBean[] eventsPerStream,
                                                boolean isNewData,
                                                ExprEvaluatorContext context)

Specified by:

evaluateGetROCollectionScalar in interface ExprEvaluatorEnumeration

getEventTypeCollection

public EventType getEventTypeCollection(EventAdapterService eventAdapterService,
                                        int statementId)
                                 throws ExprValidationException

Specified by:

getEventTypeCollection in interface ExprEvaluatorEnumeration

Throws:

ExprValidationException

getEventTypeSingle

public EventType getEventTypeSingle(EventAdapterService eventAdapterService,
                                    int statementId)
                             throws ExprValidationException

Specified by:

getEventTypeSingle in interface ExprEvaluatorEnumeration

Throws:

ExprValidationException

getComponentTypeCollection

public Class getComponentTypeCollection()
                                 throws ExprValidationException

Specified by:

getComponentTypeCollection in interface ExprEvaluatorEnumeration

Throws:

ExprValidationException

evaluate

public Object evaluate(EventBean[] eventsPerStream,
                       boolean isNewData,
                       ExprEvaluatorContext exprEvaluatorContext)

Description copied from interface: ExprEvaluator

Evaluate event tuple and return result.

Specified by:

evaluate in interface ExprEvaluator

Parameters:

eventsPerStream - - event tuple

isNewData - - indicates whether we are dealing with new data (istream) or old data (rstream)

exprEvaluatorContext - context for expression evaluation

Returns:

evaluation result, a boolean value for OR/AND-type evalution nodes.

toPrecedenceFreeEPL

public void toPrecedenceFreeEPL(StringWriter writer)

Specified by:

toPrecedenceFreeEPL in class ExprNodeBase

getPrecedence

public ExprPrecedenceEnum getPrecedence()

Description copied from interface: ExprNode

Returns precedence.

Specified by:

getPrecedence in interface ExprNode

Returns:

precedence

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equalsNode

public boolean equalsNode(ExprNode node,
                          boolean ignoreStreamPrefix)

Description copied from interface: ExprNode

Return true if a expression node semantically equals the current node, or false if not.

Concrete implementations should compare the type and any additional information that impact the evaluation of a node.

Specified by:

equalsNode in interface ExprNode

Parameters:

node - to compare to

ignoreStreamPrefix - when the equals-comparison can ignore prefix of event properties

Returns:

true if semantically equal, or false if not equals