org.lsmp.djep.xjep

Class XEvaluatorVisitor

java.lang.Object

org.nfunk.jep.EvaluatorVisitor

org.lsmp.djep.xjep.XEvaluatorVisitor

All Implemented Interfaces:

EvaluatorI, ParserVisitor

public class XEvaluatorVisitor
extends EvaluatorVisitor

This class is used for the evaluation of an expression. It uses the Visitor design pattern to traverse the function tree and evaluate the expression using a stack.

Function nodes are evaluated by first evaluating all the children nodes, then applying the function class associated with the node. Variable and constant nodes are evaluated by pushing their value onto the stack.

Some changes implemented by rjm. Nov 03. Added hook to SpecialEvaluationI. Clears stack before evaluation. Simplifies error handling by making visit methods throw ParseException. Changed visit(ASTVarNode node) so messages not calculated every time.

Field Summary

Fields inherited from class org.nfunk.jep.EvaluatorVisitor

debug, stack, symTab, trapNullValues

Constructor Summary

Constructors

Constructor and Description
XEvaluatorVisitor()

Method Summary

Modifier and Type	Method and Description
Object	visit(ASTVarNode node, Object data) Visit a variable node.

Methods inherited from class org.nfunk.jep.EvaluatorVisitor

eval, eval, getValue, isTrapNullValues, setTrapNullValues, visit, visit, visit, visit

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

XEvaluatorVisitor

public XEvaluatorVisitor()

Method Detail

visit

public Object visit(ASTVarNode node,
                    Object data)
             throws ParseException

Visit a variable node. The value of the variable is obtained from the symbol table (symTab) and pushed onto the stack.

Specified by:

visit in interface ParserVisitor

Overrides:

visit in class EvaluatorVisitor

Throws:

ParseException