andclausenode.java

是有关解释器的.用JAVA编写.可以解释一般的JAVA程序.

class AndClauseNode extends EvaluatableNode 
{
	EqualityExpressionNode vEqualityExpressionNode;
	AndClauseNode vAndClauseNode;
	Value vEqualityExpressionValue;
	Value vAndClauseValue;

	static AndClauseNode parserAndClause(Environment env, Scanner s)
		throws ParserException,
		ScannerException {
		EqualityExpressionNode tmpEqualityExpressionNode;
		AndClauseNode tmpAndClauseNode = null;
		Token t;

		tmpEqualityExpressionNode = EqualityExpressionNode
			.parserEqualityExpression(env, s);
		t = s.token();
		if (t.isOperator() && ((OperatorToken) t).isAnd()) {
			matchOperator(s, ((OperatorToken) t).content());
			tmpAndClauseNode = AndClauseNode.parserAndClause(env, s);
		}

		return new AndClauseNode(tmpEqualityExpressionNode, tmpAndClauseNode);
	}
	AndClauseNode() 
	{
		vEqualityExpressionNode = null;
		vAndClauseNode = null;
	}
	AndClauseNode(EqualityExpressionNode aEqualityExpressionNode, AndClauseNode aAndClauseNode) 
	{
		vEqualityExpressionNode = aEqualityExpressionNode;
		vAndClauseNode = aAndClauseNode;
	}
	String format(int indent) 
	{
		String str= vEqualityExpressionNode.format(indent);
		if(vAndClauseNode!=null)
			str+= "&&" + vAndClauseNode.format(indent);
		return str;
	}
	Value evaluate(Environment env) throws InterpreterException 
	{
		if(vAndClauseNode!=null)			
			return vEqualityExpressionNode.evaluate(env).and(vAndClauseNode.evaluate(env));
		return vEqualityExpressionNode.evaluate(env);
	}
	boolean typeCheck(Environment env) throws InterpreterException
	{
		if(vEqualityExpressionNode.typeCheck(env))
		{
			vEqualityExpressionValue= vEqualityExpressionNode.evaluate(env);
			if(vAndClauseNode!=null)
				if(vEqualityExpressionValue.isBoolean())
				{
					if(vAndClauseNode.typeCheck(env))
					{
						vAndClauseValue= vAndClauseNode.evaluate(env);
						if(vAndClauseValue.isBoolean())return true;
							else ProgramNode.mTypeCheckError(this.format(4));
					}else ProgramNode.mTypeCheckError(this.format(4));
				}else ProgramNode.mTypeCheckError(this.format(4));					
		}else ProgramNode.mTypeCheckError(this.format(4));
		
		return true;
	}
}