com.espertech.esper.epl.expression.core

Class ExprConstantNodeImpl

java.lang.Object

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

com.espertech.esper.epl.expression.core.ExprConstantNodeImpl

All Implemented Interfaces:

ExprConstantNode, ExprEvaluator, ExprForge, ExprNode, ExprNodeRenderable, ExprValidator, MetaDefItem, Serializable

public class ExprConstantNodeImpl
extends ExprNodeBase
implements ExprConstantNode, ExprEvaluator, ExprForge

Represents a constant in an expressiun tree.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ExprConstantNodeImpl(Class clazz) Ctor - for use when the constant should return a given type and the actual value is always null.
ExprConstantNodeImpl(Object value) Ctor.
ExprConstantNodeImpl(Object value, Class valueType) 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.
CodegenExpression	evaluateCodegen(CodegenParamSetExprPremade params, CodegenContext context)
ExprForgeComplexityEnum	getComplexity()
Class	getConstantType()
Object	getConstantValue(ExprEvaluatorContext context) Returns the constant's value.
Class	getEvaluationType()
ExprEvaluator	getExprEvaluator()
ExprForge	getForge()
ExprNodeRenderable	getForgeRenderable()
ExprPrecedenceEnum	getPrecedence() Returns precedence.
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	setValue(Object value) Sets the value of the constant.
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

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

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

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

toEPL

Constructor Detail

ExprConstantNodeImpl

public ExprConstantNodeImpl(Object value)

Ctor.

Parameters:

value - is the constant's value.

ExprConstantNodeImpl

public ExprConstantNodeImpl(Object value,
                            Class valueType)

Ctor.

Parameters:

value - is the constant's value.

valueType - is the constant's value type.

ExprConstantNodeImpl

public ExprConstantNodeImpl(Class clazz)

Ctor - for use when the constant should return a given type and the actual value is always null.

Parameters:

clazz - the type of the constant null.

Method Detail

isConstantValue

public boolean isConstantValue()

Specified by:

isConstantValue in interface ExprConstantNode

getExprEvaluator

public ExprEvaluator getExprEvaluator()

Specified by:

getExprEvaluator in interface ExprForge

getEvaluationType

public Class getEvaluationType()

Specified by:

getEvaluationType in interface ExprForge

getForge

public ExprForge getForge()

Specified by:

getForge in interface ExprNode

getForgeRenderable

public ExprNodeRenderable getForgeRenderable()

Specified by:

getForgeRenderable in interface ExprForge

evaluateCodegen

public CodegenExpression evaluateCodegen(CodegenParamSetExprPremade params,
                                         CodegenContext context)

Specified by:

evaluateCodegen in interface ExprForge

getComplexity

public ExprForgeComplexityEnum getComplexity()

Specified by:

getComplexity in interface ExprForge

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

getConstantValue

public Object getConstantValue(ExprEvaluatorContext context)

Returns the constant's value.

Specified by:

getConstantValue in interface ExprConstantNode

Returns:

value of constant

setValue

public void setValue(Object value)

Sets the value of the constant.

Parameters:

value - to set

getConstantType

public Class getConstantType()

Specified by:

getConstantType in interface ExprConstantNode

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