com.espertech.esper.epl.expression.core

Class ExprVariableNodeImpl

java.lang.Object

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

com.espertech.esper.epl.expression.core.ExprVariableNodeImpl

All Implemented Interfaces:

ExprConstantNode, ExprEvaluator, ExprNode, ExprValidator, ExprVariableNode, MetaDefItem, Serializable

public class ExprVariableNodeImpl
extends ExprNodeBase
implements ExprEvaluator, ExprVariableNode

Represents a variable in an expression tree.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ExprVariableNodeImpl(VariableMetaData variableMetaData, String optSubPropName)

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.
Class	getConstantType()
Object	getConstantValue(ExprEvaluatorContext context)
ExprEvaluator	getExprEvaluator()
ExprPrecedenceEnum	getPrecedence() Returns precedence.
Class	getType() Returns the type that the node's evaluate method returns an instance of.
String	getVariableName()
String	getVariableNameWithSubProp()
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	isConstantValue()
void	toPrecedenceFreeEPL(StringWriter writer)
String	toString()
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, wait, wait, wait

Methods inherited from interface com.espertech.esper.epl.expression.core.ExprNode

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

Constructor Detail

ExprVariableNodeImpl

public ExprVariableNodeImpl(VariableMetaData variableMetaData,
                            String optSubPropName)

Method Detail

isConstantValue

public boolean isConstantValue()

Specified by:

isConstantValue in interface ExprConstantNode

getExprEvaluator

public ExprEvaluator getExprEvaluator()

Specified by:

getExprEvaluator in interface ExprNode

getVariableName

public String getVariableName()

Specified by:

getVariableName in interface ExprVariableNode

getConstantValue

public Object getConstantValue(ExprEvaluatorContext context)

Specified by:

getConstantValue in interface ExprConstantNode

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

validate

public ExprNode validate(ExprValidationContext validationContext)
                  throws ExprValidationException

Specified by:

validate in interface ExprValidator

Throws:

ExprValidationException

getConstantType

public Class getConstantType()

Specified by:

getConstantType in interface ExprConstantNode

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

toString

public String toString()

Overrides:

toString in class Object

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

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

getVariableNameWithSubProp

public String getVariableNameWithSubProp()

Specified by:

getVariableNameWithSubProp in interface ExprVariableNode