net.esper.eql.expression
Class ExprEqualsNode

java.lang.Object
  extended by net.esper.eql.expression.ExprNode
      extended by net.esper.eql.expression.ExprEqualsNode
All Implemented Interfaces:
ExprEvaluator, ExprValidator, MetaDefItem

public class ExprEqualsNode
extends ExprNode

Represents an equals (=) comparator in a filter expressiun tree.


Nested Class Summary
 
Nested classes/interfaces inherited from class net.esper.eql.expression.ExprNode
ExprNode.MappedPropertyParseResult
 
Constructor Summary
ExprEqualsNode(boolean isNotEquals)
          Ctor.
 
Method Summary
 boolean equalsNode(ExprNode node)
          Return true if a expression node semantically equals the current node, or false if not.
 Object evaluate(EventBean[] eventsPerStream, boolean isNewData)
          Evaluate event tuple and return result.
 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.
 boolean isNotEquals()
          Returns true if this is a NOT EQUALS node, false if this is a EQUALS node.
 String toExpressionString()
          Returns the expression node rendered as a string.
 void validate(StreamTypeService streamTypeService, MethodResolutionService methodResolutionService, ViewResourceDelegate viewResourceDelegate)
          Validate node.
 
Methods inherited from class net.esper.eql.expression.ExprNode
accept, addChildNode, deepEquals, dumpDebug, getChildNodes, getValidatedSubtree, parseMappedProperty
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ExprEqualsNode

public ExprEqualsNode(boolean isNotEquals)
Ctor.

Parameters:
isNotEquals - - true if this is a (!=) not equals rather then equals, false if its a '=' equals
Method Detail

isNotEquals

public boolean isNotEquals()
Returns true if this is a NOT EQUALS node, false if this is a EQUALS node.

Returns:
true for !=, false for =

validate

public void validate(StreamTypeService streamTypeService,
                     MethodResolutionService methodResolutionService,
                     ViewResourceDelegate viewResourceDelegate)
              throws ExprValidationException
Description copied from interface: ExprValidator
Validate node.

Parameters:
streamTypeService - serves stream event type info
methodResolutionService - - for resolving class names in library method invocations
viewResourceDelegate - - delegates for view resources to expression nodes
Throws:
ExprValidationException - thrown when validation failed

isConstantResult

public boolean isConstantResult()
Description copied from class: 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 class ExprNode
Returns:
true for constant evaluation value, false for non-constant evaluation value

getType

public Class getType()
Description copied from interface: ExprValidator
Returns the type that the node's evaluate method returns an instance of.

Returns:
type returned when evaluated

evaluate

public Object evaluate(EventBean[] eventsPerStream,
                       boolean isNewData)
Description copied from interface: ExprEvaluator
Evaluate event tuple and return result.

Parameters:
eventsPerStream - - event tuple
isNewData - - indicates whether we are dealing with new data (istream) or old data (rstream)
Returns:
evaluation result, a boolean value for OR/AND-type evalution nodes.

toExpressionString

public String toExpressionString()
Description copied from class: ExprNode
Returns the expression node rendered as a string.

Specified by:
toExpressionString in class ExprNode
Returns:
string rendering of expression

equalsNode

public boolean equalsNode(ExprNode node)
Description copied from class: 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 class ExprNode
Parameters:
node - to compare to
Returns:
true if semantically equal, or false if not equals