private int EvaluateInput(string input)
{
CalculatorLexer lexer = new CalculatorLexer(new AntlrInputStream(input));
lexer.RemoveErrorListeners();
lexer.AddErrorListener(new ThrowingErrorListener <int>());
CalculatorParser parser = new CalculatorParser(new CommonTokenStream(lexer));
parser.RemoveErrorListeners();
parser.AddErrorListener(new ThrowingErrorListener <IToken>());
return(new CalculatorVisitor().Visit(parser.expression()));
}
public static double Evaluate(string expression)
{
var lexer = new CalculatorLexer(new AntlrInputStream(expression));
lexer.RemoveErrorListeners();
lexer.AddErrorListener(new ThrowExceptionErrorListener());
var tokens = new CommonTokenStream(lexer);
var parser = new CalculatorParser(tokens);
var tree = parser.compileUnit();
var visitor = new ExcelVisitor();
return(visitor.Visit(tree));
}
/// <summary>
/// This will attempt to recalculate if an error was encountered. Will try to skip whitespaces
/// and comments so to prevent number literals and function qualifiers not being identified.
/// </summary>
/// <param name="formula"></param>
/// <param name="secondRun"></param>
/// <returns></returns>
private static CalculationResult CalculateResult(string formula, bool secondRun)
{
if (string.IsNullOrWhiteSpace(formula))
{
return(new CalculationResult
{
IsValid = true,
Result = 0
});
}
var inputStream = new AntlrInputStream(formula);
var lexer = new CalculatorLexer(inputStream);
var tokenStream = new CommonTokenStream(lexer);
var parser = new CalculatorParser(tokenStream);
// Removing default error listeners due to noise in debug
lexer.RemoveErrorListeners();
parser.RemoveErrorListeners();
// But adding the custom one
var customErrorListener = new CalculatorErrorListener();
parser.AddErrorListener(customErrorListener);
var visitor = new CalculatorVisitor();
var calculatorExpression = parser.calculator().expression();
var result = visitor.Visit(calculatorExpression);
var isValid = customErrorListener.IsValid;
var errorLocation = customErrorListener.ErrorLocation;
var errorMessage = customErrorListener.ErrorMessage;
if (double.IsInfinity(result))
{
isValid = false;
}
if (!isValid && !secondRun)
{
var cleanedFormula = string.Empty;
var tokenList = tokenStream.GetTokens().ToList();
for (var i = 0; i < tokenList.Count - 1; i++)
{
cleanedFormula += tokenList[i].Text;
}
var originalErrorLocation = errorLocation;
var retriedResult = CalculateResult(cleanedFormula, true);
if (!retriedResult.IsValid)
{
retriedResult.ErrorPosition = originalErrorLocation;
retriedResult.ErrorMessage = errorMessage;
}
return(retriedResult);
}
return(new CalculationResult
{
IsValid = isValid,
Result = isValid || double.IsInfinity(result)
? result
: double.NaN,
ErrorPosition = errorLocation,
ErrorMessage = isValid ? null : errorMessage
});
}
