public string Parse(string polynom)
{
polynom = OpenBraces(polynom);
var equalityPos = polynom.IndexOf("=");
string result = String.Empty;
var parsedSummands = ParseSummands(polynom);
foreach (var summand in parsedSummands)
if (summand.Index > equalityPos)
summand.Negative = !summand.Negative;
var similarSummands = parsedSummands.GroupBy(s => s.GetPoweredVariableString());
List<Summand> resultingSummands = new List<Summand>();
foreach (var summandGroup in similarSummands)
{
var multiplierSum = summandGroup.Sum(g => g.GetSignedMultiplier());
if (multiplierSum != 0)
{
var summand = summandGroup.First();
var resultingSummand = new Summand { Negative = multiplierSum < 0, Multiplier = multiplierSum < 0 ? multiplierSum * -1 : multiplierSum, Variable = summand.Variable, Power = summand.Power };
resultingSummands.Add(resultingSummand);
}
}
result = String.Join("+", resultingSummands.OrderByDescending(s => s.SortOrder()).Select(s => s.GetFullString()).ToArray()).Replace("+-", "-") + "=0";
return result;
}
public List<Summand> ParseSummands(string polynom)
{
string polynomPattern = @"(\-?\d*(?:\.\d+)?[a-zA-Z]*(?:\^?\d+)?)";
string summandPattern = @"(?'negation'\-+)*\s*(?'multiplier'\d+\.*\d*)*\s*(?'variable'[a-zA-Z]+)*\s*(?'power'\^{1}\d+)*";
Regex mainReg = new Regex(polynomPattern);
Regex summandReg = new Regex(summandPattern);
var summands = mainReg.Matches(polynom);
List<Summand> parsedSummands = new List<Summand>();
foreach (Match summand in summands)
{
if (summand.Value.Length == 0)
continue;
var summandParts = summandReg.Match(summand.ToString()).Groups;
var negation = summandParts["negation"].Value.Length > 0;
decimal? multiplier = summandParts["multiplier"].Value.Length > 0 ? (decimal?)Convert.ToDecimal(summandParts["multiplier"].Value.Replace(',', '.'), CultureInfo.InvariantCulture) : null;
var variable = summandParts["variable"].Value;
int? power = summandParts["power"].Length > 0 ? (int?)Int32.Parse(summandParts["power"].Value.Substring(1)) : null;
if (variable.Length > 0 && multiplier.GetValueOrDefault(0) == 0)
multiplier = 1;
var parsedSummand = new Summand { Negative = negation, Multiplier = multiplier, Variable = variable, Power = power, Index = summand.Index };
parsedSummands.Add(parsedSummand);
}
return parsedSummands;
}