private digit Parse_digit()
{
if (_index >= _tokens.Count())
{
return(null);
} // must be first line on any atom
/* digit:
* "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" */
var _data = _tokens[_index];
var _result = new digit(_data);
if (_result.is_digit)
{
_index++;
return(_result);
}
else
{
return(null);
}
}
public digit_sequence(digit _digit, digit_sequence _digit_sequence)
{
digit = _digit;
self_digit_sequence = _digit_sequence;
expression = self_digit_sequence?.expression + digit.expression;
}
public digit_sequence(digit _digit)
{
digit = _digit;
expression = digit.expression;
}
