slogo.expression
Class Expression

java.lang.Object
  slogo.language.GrammarElement
      slogo.expression.Expression

Direct Known Subclasses:

Number, Variable

public abstract class Expression
extends GrammarElement

The base class of all arithmetic expressions, the evaluate method uses the hook/template method value to return a Double value, the template method returns a double.

Author:

Owen Astrachan

Field Summary

Fields inherited from class slogo.language.GrammarElement

gelementsToValue

Constructor Summary

Expression()

Method Summary

java.lang.Double	evaluate(Context c) Evaluate this language construct in some context.
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.Double evaluate(Context c)

Description copied from class: GrammarElement

Evaluate this language construct in some context. The evaluation may have side-effects, e.g., moving a turtle.

Specified by:

evaluate in class GrammarElement

Parameters:

c - context in which the evaluation takes place

Returns:

the result of evaluating the construct

value

public abstract double value(Context c)