net.esper.eql.expression
Class ExprCaseNode

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

public class ExprCaseNode
extends ExprNode

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


Nested Class Summary
 
Nested classes/interfaces inherited from class net.esper.eql.expression.ExprNode
ExprNode.MappedPropertyParseResult
 
Constructor Summary
ExprCaseNode(boolean isCase2)
          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.
 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

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

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.

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

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