elan.expression
Class Expression

java.lang.Object
  |
  +--elan.GrammarElement
        |
        +--elan.expression.Expression

Direct Known Subclasses:

Back, Background, BinaryExpression, Bye, Clean, ClearScreen, Forward, Heading, HideTurtle, Home, Left, Load, Number, PenColor, PenDown, PenDownP, PenSize, PenUp, Right, Save, SetBackground, SetHeading, SetPenColor, SetPenSize, SetX, SetY, ShowTurtle, UnaryExpression, Variable, XCor, YCor

public abstract class Expression

extends GrammarElement

Field Summary

Fields inherited from class elan.GrammarElement

ourMap

Constructor Summary

Expression()

Method Summary

java.lang.Object	evaluate(Context c)
java.lang.String	getMessage()
abstract double	value(Context c)

Methods inherited from class java.lang.Object

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

Constructor Detail

Expression

public Expression()

Method Detail

evaluate

public java.lang.Object evaluate(Context c)

Specified by:

evaluate in class GrammarElement

value

public abstract double value(Context c)

getMessage

public java.lang.String getMessage()