private static (IParseTree tree, string parseErrorMessage) TryParseExpression(string expression)
{
ICharStream stream = CharStreams.fromstring(expression);
PolynomialLexer lexer = new PolynomialLexer(stream);
ITokenStream tokens = new CommonTokenStream(lexer);
PolynomialParser parser = new PolynomialParser(tokens)
{
BuildParseTree = true
};
parser.RemoveErrorListeners();
parser.AddErrorListener(new PolynomialErrorListener());
try
{
var tree = parser.parse();
return(tree, string.Empty);
}
catch (ParseCanceledException pce)
{
return(null, pce.Message);
}
}
