org.nfunk.jep.function
Class If

java.lang.Object
  org.nfunk.jep.function.PostfixMathCommand
      org.nfunk.jep.function.If

All Implemented Interfaces:

PostfixMathCommandI, SpecialEvaluationI

public class If

extends PostfixMathCommand

implements SpecialEvaluationI

The if(condExpr,posExpr,negExpr) function. The value of trueExpr will be returned if condExpr is >0 (true) and value of negExpr will be returned if condExpr is <= 0 (false).

This function performs lazy evaluation so that only posExpr or negExpr will be evaluated. For Complex numbers only the real part is used.

An alternate form if(condExpr,posExpr,negExpr,zeroExpr) is also availiable. Note most computations are carried out over floating point doubles so testing for zero can be dangerous.

This function implements the SpecialEvaluationI interface so that it handles setting the value of a variable.

Author:

Rich Morris Created on 18-Nov-2003

Field Summary

Fields inherited from class org.nfunk.jep.function.PostfixMathCommand

curNumberOfParameters, numberOfParameters

Constructor Summary

If()

Method Summary

java.lang.Object

evaluate(Node node, java.lang.Object data, ParserVisitor pv, java.util.Stack inStack) For assignment

Methods inherited from class org.nfunk.jep.function.PostfixMathCommand

checkStack, getNumberOfParameters, run, setCurNumberOfParameters

Methods inherited from class java.lang.Object

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

Constructor Detail

If

public If()

Method Detail

evaluate

public java.lang.Object evaluate(Node node,
                                 java.lang.Object data,
                                 ParserVisitor pv,
                                 java.util.Stack inStack)
                          throws ParseException

For assignment

Specified by:

evaluate in interface SpecialEvaluationI

Parameters:

node - The current node

data - The data passed to visitor, typically not used

pv - The visitor, can be used evaluate the children

inStack - The stack of the evaluator

Returns:

the value after evaluation

Throws:

ParseException