public void TestCalculator()
{
var testString = @"a=1+2*3; print a;";
CalculatorLexer lexer = new CalculatorLexer(new AntlrInputStream(testString));
CommonTokenStream tokens = new CommonTokenStream(lexer);
CalculatorParser p = new CalculatorParser(tokens);
p.BuildParseTree = true;
p.AddParseListener(new CalculatorListener());
ParserRuleContext t = p.program();
}