slogo.instruction

Class Back

java.lang.Object

slogo.GrammarElement

slogo.instruction.Instruction

slogo.instruction.Back

public class Back
extends Instruction

Field Summary

Fields

Modifier and Type	Field and Description
private GrammarElement	expression

Fields inherited from class slogo.GrammarElement

gelementsToValue

Constructor Summary

Constructors

Constructor and Description
Back(GrammarElement e) Constructs a BACK instruction that can be executed.

Method Summary

Modifier and Type	Method and Description
java.lang.Object	evaluate(Context c) Evaluate this instruction in a Context.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

expression

private GrammarElement expression

Constructor Detail

Back

public Back(GrammarElement e)

Constructs a BACK instruction that can be executed.

Parameters:

e - number of steps to take

Method Detail

evaluate

public java.lang.Object evaluate(Context c)

Evaluate this instruction in a Context.

Specified by:

evaluate in class Instruction

Parameters:

c - the Context for the evaluation

Returns:

the number of steps moved

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

Returns:

a String representing this instruction as BK, followed by the expression about how steps were taken