public Node Factor()
{
Node result = null;
if (CurrentToken().type == TokenType.LEFT_PAREN)
{
MatchAndEat(TokenType.LEFT_PAREN);
result = Expression();
MatchAndEat(TokenType.RIGHT_PAREN);
}
else if (IsNumber())
{
Token token = MatchAndEat(TokenType.NUMBER);
result = new NumberNode(Int32.Parse(token.text));
}
else if (IsString())
{
Token token = MatchAndEat(TokenType.STRING);
result = new StringNode((token.text).ToString());
}
else if (IsKeyWord())
{
result = Variable();
}
return(result);
}
public static void main(string[] args)
{
NumberNode firstNumber = new NumberNode(100);
NumberNode secondNumber = new NumberNode(200);
Node sumNode = new BinOpNode(TokenType.ADD, firstNumber, secondNumber);
Console.WriteLine("100 + 200 = " + sumNode.Eval());
Node compareNode = new BinOpNode(TokenType.LESS, firstNumber, secondNumber);
Console.WriteLine("100 < 200 = " + compareNode.Eval());
}
