public IEnumerable<int> Parse(string message)
{
var lexer = new StringCalculatorLexer(message);
var delimiters = new HashSet<string>();
string numbersString = null;
foreach (var token in lexer.Read())
{
if (token is DelimiterToken)
{
delimiters.Add(token.Content);
}
if (token is NumbersToken)
{
numbersString = token.Content;
}
}
if (string.IsNullOrEmpty(numbersString))
{
return Enumerable.Empty<int>();
}
var numberSplitter = delimiters.Any() ?
delimiters.GenerateSplitter() :
_defaultSplitter;
return numberSplitter
.Split(numbersString)
.Select(int.Parse);
}