primitiveselectornode.java

是有关解释器的.用JAVA编写.可以解释一般的JAVA程序.

class PrimitiveSelectorNode extends EvaluatableNode
{
	static String[] vPrimitiveSelectors={"turnOff","move","turnLeft","pickBeeper","putBeeper",
			"frontIsClear","nextToABeeper","anyBeepersInBeeperBag","facingNorth","facingSouth",
			"facingEast","facingWest"};	
	String vPrimitiveSelector;
	
	static PrimitiveSelectorNode parserPrimitiveSelector(Environment env, Scanner s) throws ParserException, ScannerException
	{
		return new PrimitiveSelectorNode(matchIdentifier(s));
	}
	PrimitiveSelectorNode(String aString)
	{
		vPrimitiveSelector= aString;
	}
	static boolean mIsPrimitiveSelector(Scanner s) throws ScannerException
	{
		int i=0;
		
		while(i<vPrimitiveSelectors.length)
		{			
			if(isIdentifierToken(s,vPrimitiveSelectors[i]))return true;
			i++;
		}
		return false;
	}
	static boolean mIsPrimitiveSelector(String str)
	{
		int i=0;
		while(i<vPrimitiveSelectors.length)
		{
			if(vPrimitiveSelectors[i].equals(str))return true;
			i++;
		}
		return false;
	}
	String format(int indent)
	{		
		return vPrimitiveSelector;
	}
	Value evaluate(Environment env) throws InterpreterException
	{	
		boolean result= true;
		
		if(ProgramNode.vMessageReciever!=null)
		{
			QueryRobot r= ((RobotValue)env.at(ProgramNode.vMessageReciever)).robotRef();
			if(r!=null)
			{
				if(vPrimitiveSelector.equals("turnOff"))r.turnOff();else
				if(vPrimitiveSelector.equals("move"))r.move();else
				if(vPrimitiveSelector.equals("turnLeft"))r.turnLeft();else
				if(vPrimitiveSelector.equals("pickBeeper"))r.pickBeeper();else
				if(vPrimitiveSelector.equals("putBeeper"))r.putBeeper();else
				if(vPrimitiveSelector.equals("frontIsClear"))result=r.frontIsClear();else
				if(vPrimitiveSelector.equals("nextToABeeper"))result=r.nextToABeeper();else
				if(vPrimitiveSelector.equals("anyBeepersInBeeperBag"))result=r.anyBeepersInBeeperBag();else
				if(vPrimitiveSelector.equals("facingNorth"))result=r.facingNorth();else
				if(vPrimitiveSelector.equals("facingSouth"))result=r.facingSouth();else
				if(vPrimitiveSelector.equals("facingEast"))result=r.facingEast();else
				if(vPrimitiveSelector.equals("facingWest"))result=r.facingWest();
				env.updateValue(ProgramNode.vMessageReciever,new RobotValue(r));
			}
			else throw new InterpreterException("UninitializedVariable  " + ProgramNode.vMessageReciever);
		}
		return new BooleanValue(result);		
	}
}