com.espertech.esper.epl.expression.funcs

Class ExprCaseNode

java.lang.Object

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

com.espertech.esper.epl.expression.funcs.ExprCaseNode

All Implemented Interfaces:

ExprEvaluator, ExprEvaluatorTypableReturn, ExprNode, ExprValidator, MetaDefItem, Serializable

public class ExprCaseNode
extends ExprNodeBase
implements ExprEvaluator, ExprEvaluatorTypableReturn

Represents the case-when-then-else control flow function is an expression tree.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ExprCaseNode.CaseAnalysis

Constructor Summary

Constructors

Constructor and Description
ExprCaseNode(boolean isCase2) Ctor.

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.
Object[][]	evaluateTypableMulti(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext context)
Object[]	evaluateTypableSingle(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext context)
ExprEvaluator	getExprEvaluator()
ExprPrecedenceEnum	getPrecedence() Returns precedence.
LinkedHashMap<String,Object>	getRowProperties() Return null to indicate no row-type result available, or a map of property names and types to indicate a row-type result is available.
Class	getType() Returns the type that the node's evaluate method returns an instance of.
boolean	isCase2() Returns true if this is a switch-type case.
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.
Boolean	isMultirow() Return true for multi-row return, return false for return of single row only
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, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExprCaseNode

public ExprCaseNode(boolean isCase2)

Ctor.

Parameters:

isCase2 - is an indicator of which Case statement we are working on.

True indicates a 'Case2' statement with syntax "case a when a1 then b1 else b2".

False indicates a 'Case1' statement with syntax "case when a=a1 then b1 else b2".

Method Detail

getExprEvaluator

public ExprEvaluator getExprEvaluator()

Specified by:

getExprEvaluator in interface ExprNode

isCase2

public boolean isCase2()

Returns true if this is a switch-type case.

Returns:

true for switch-type case, or false for when-then type

validate

public ExprNode validate(ExprValidationContext validationContext)
                  throws ExprValidationException

Specified by:

validate in interface ExprValidator

Throws:

ExprValidationException

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

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

getRowProperties

public LinkedHashMap<String,Object> getRowProperties()
                                              throws ExprValidationException

Description copied from interface: ExprEvaluatorTypableReturn

Return null to indicate no row-type result available, or a map of property names and types to indicate a row-type result is available.

Specified by:

getRowProperties in interface ExprEvaluatorTypableReturn

Returns:

map of property names and types or null

Throws:

ExprValidationException - if the expression is invalid

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.

isMultirow

public Boolean isMultirow()

Description copied from interface: ExprEvaluatorTypableReturn

Return true for multi-row return, return false for return of single row only

Specified by:

isMultirow in interface ExprEvaluatorTypableReturn

Returns:

multi-row flag

evaluateTypableSingle

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

Specified by:

evaluateTypableSingle in interface ExprEvaluatorTypableReturn

evaluateTypableMulti

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

Specified by:

evaluateTypableMulti in interface ExprEvaluatorTypableReturn

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

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