slogo.language
Class GrammarElement

java.lang.Object
  slogo.language.GrammarElement

Direct Known Subclasses:

Expression, Instruction

public abstract class GrammarElement
extends java.lang.Object

All elements of the elan language (e.g., that make up an abstract syntax tree) should extend GrammarElement. Evaluating a language construct with a context returns the value of the evaluation and may have side-effects.

Field Summary

protected static java.util.Map<GrammarElement,java.lang.Object>

gelementsToValue

Constructor Summary

GrammarElement()

Method Summary

abstract java.lang.Object

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

Methods inherited from class java.lang.Object

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

Field Detail

gelementsToValue

protected static java.util.Map<GrammarElement,java.lang.Object> gelementsToValue

Constructor Detail

GrammarElement

public GrammarElement()

Method Detail

evaluate

public abstract java.lang.Object evaluate(Context c)

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

Parameters:

c - context in which the evaluation takes place

Returns:

the result of evaluating the construct