com.espertech.esper.epl.expression.ops
Class ExprMathNode

java.lang.Object
  com.espertech.esper.epl.expression.core.ExprNodeBase
      com.espertech.esper.epl.expression.ops.ExprMathNode

All Implemented Interfaces:

ExprEvaluator, ExprNode, ExprValidator, MetaDefItem, java.io.Serializable

public class ExprMathNode
extends ExprNodeBase
implements ExprEvaluator

Represents a simple Math (+/-/divide/*) in a filter expression tree.

See Also:

Serialized Form

Constructor Summary

ExprMathNode(MathArithTypeEnum mathArithTypeEnum, boolean isIntegerDivision, boolean isDivisionByZeroReturnsNull)
Ctor.

Method Summary

boolean	equalsNode(ExprNode node) Return true if a expression node semantically equals the current node, or false if not.
java.lang.Object	evaluate(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext) Evaluate event tuple and return result.
ExprEvaluator	getExprEvaluator()
MathArithTypeEnum	getMathArithTypeEnum() Returns the type of math.
ExprPrecedenceEnum	getPrecedence() Returns precedence.
java.lang.Class	getType() Returns the type that the node's evaluate method returns an instance of.
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	toPrecedenceFreeEPL(java.io.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

ExprMathNode

public ExprMathNode(MathArithTypeEnum mathArithTypeEnum,
                    boolean isIntegerDivision,
                    boolean isDivisionByZeroReturnsNull)

Ctor.

Parameters:

mathArithTypeEnum - - type of math

isIntegerDivision - - false for division returns double, true for using Java-standard integer division

isDivisionByZeroReturnsNull - - false for division-by-zero returns infinity, true for null

Method Detail

getExprEvaluator

public ExprEvaluator getExprEvaluator()

Specified by:

getExprEvaluator in interface ExprNode

validate

public ExprNode validate(ExprValidationContext validationContext)
                  throws ExprValidationException

Specified by:

validate in interface ExprValidator

Throws:

ExprValidationException

getType

public java.lang.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

evaluate

public java.lang.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(java.io.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)

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

Returns:

true if semantically equal, or false if not equals

getMathArithTypeEnum

public MathArithTypeEnum getMathArithTypeEnum()

Returns the type of math.

Returns:

math type