protected AExpression ExtractValue(ref string formula)
{
AExpression result;
string f = formula.TrimStart();
// handle -sign
bool wrapInNeg = f[0] == '-';
if (wrapInNeg)
{
f = f.Substring(1).TrimStart();
}
if (f[0] == '(')
{
int closingPos = SearchClosingBracket(f);
result = new Expression(f.Substring(1, closingPos - 1));
f = f.Substring(closingPos + 1);
}
else if ((f[0] >= '0' && f[0] <= '9') || f[0] == '.')
{
var m = numberReg.Match(f);
if (!m.Success)
{
throw new ArgumentException("Invalid number format");
}
float val = float.Parse(m.Value.Replace(",", "."), CultureInfo.InvariantCulture.NumberFormat);
f = f.Substring(m.Length);
result = new FixedValue {
Value = val
};
}
else
{
throw new NotSupportedException("Unknown value format");
}
if (wrapInNeg)
{
result = new NegWrapper()
{
Expr = result
};
}
formula = f.TrimStart();
return(result);
}