net.esper.pattern
Class EvalStateNode

java.lang.Object
  extended by net.esper.pattern.EvalStateNode
Direct Known Subclasses:
EvalAndStateNode, EvalEveryStateNode, EvalFilterStateNode, EvalFollowedByStateNode, EvalGuardStateNode, EvalNotStateNode, EvalObserverStateNode, EvalOrStateNode, EvalRootStateNode

public abstract class EvalStateNode
extends Object

Superclass of all state nodes in an evaluation node tree representing an event expressions. Follows the Composite pattern. Subclasses are expected to keep their own collection containing child nodes as needed.


Method Summary
protected abstract  Object accept(EvalStateNodeVisitor visitor, Object data)
          Accept a visitor.
abstract  Object childrenAccept(EvalStateNodeVisitor visitor, Object data)
          Pass the visitor to all child nodes.
protected abstract  void quit()
          Stops the event expression or an instance of it.
protected abstract  void start()
          Starts the event expression or an instance of it.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

start

protected abstract void start()
Starts the event expression or an instance of it. Child classes are expected to initialize and start any event listeners or schedule any time-based callbacks as needed.


quit

protected abstract void quit()
Stops the event expression or an instance of it. Child classes are expected to free resources and stop any event listeners or remove any time-based callbacks.


accept

protected abstract Object accept(EvalStateNodeVisitor visitor,
                                 Object data)
Accept a visitor. Child classes are expected to invoke the visit method on the visitor instance passed in.

Parameters:
visitor - on which the visit method is invoked by each node
data - any additional data the visitor may need is passed in this parameter
Returns:
any additional data the visitor may need or null

childrenAccept

public abstract Object childrenAccept(EvalStateNodeVisitor visitor,
                                      Object data)
Pass the visitor to all child nodes.

Parameters:
visitor - is the instance to be passed to all child nodes
data - any additional data the visitor may need is passed in this parameter
Returns:
any additional data the visitor may need or null