private IExpression ParseOctalEscapeOrNumberedBackreference()
{
int endIndex = GetNumberEndIndex();
string numberString = regex.Substring(index, endIndex - index);
index = endIndex; // swallow number
int number = Int32.Parse(numberString);
if (number >= 1 && number <= 9)
{
return(Backreference.For(number));
}
else if (numberString[0] == '8' || numberString[0] == '9')
{
return(CharacterEscapes.Octal(numberString));
}
else if (number >= 10)
{
if (number < groupNames.Count)
{
return(Backreference.For(number));
}
else
{
return(CharacterEscapes.Octal(numberString));
}
}
// The Regex constructor to prevent backreferences to \0 and invalid octal codes
throw new InvalidOperationException();
}
private IExpression ParseNamedBackreference()
{
++index; // swallow 'k'
bool useQuotes = regex[index] == '\'';
char closingChar = useQuotes ? '\'' : '>';
++index; // swallow opening char
int endIndex = regex.IndexOf(closingChar, index);
string name = regex.Substring(index, endIndex - index);
index = endIndex + 1; // swallow closing char
return(Backreference.For(name, useQuotes));
}