CallbackEvaluationI

All Known Implementing Classes:: AbstractInc, Assign, Case, If, LazyLogical, NullWrappedAbstractInc, NullWrappedIf, NullWrappedLazyLogical, OpEquals, PostDec, PostInc, PreDec, PreInc, Switch, SwitchDefault, TernaryConditional, ThreadSafeAssign

public interface CallbackEvaluationI

Functions which require greater control over their evaluation should implement this interface.

Since Jep 4.0 this interface should not be used with UnaryFunction, BinaryFunction etc., the eval() of those classes will be called rather than the evaluate(Node, Evaluator).

Author:: Rich Morris Created on 18-Nov-2003

Method Summary

Modifier and Type

Method

Description

Object

evaluate(Node node, Evaluator pv)

Performs some special evaluation on the node.

Method Details
- evaluate
  
  Object evaluate(Node node, Evaluator pv) throws EvaluationException
  Performs some special evaluation on the node. This method has the responsibility for evaluating the children of the node, and it should generally call
  pv.eval(node.jjtGetChild(i))
  for each child. The SymbolTable is not passed as an argument. This is because it is better practice to get and set variable values by using node.getVar().setValue() rather that through the SymbolTable with requires a hashtable lookup.
  Parameters:
  
  node - The current node
  
  pv - The visitor, can be used evaluate the children
  
  Returns:
  
  the value after evaluation. This value will be passed to other functions higher up the node tree. The value can be any type including Double or Vector<Object>
  
  Throws:
  
  EvaluationException - if the calculation cannot be performed
  
  See Also:
  
  Evaluator