public static Summand Parse(string summandString)
{
if (summandString.IsNullOrWhiteSpace())
{
throw new ArgumentNullException(nameof(summandString));
}
if (!SummandRegex.IsMatch(summandString))
{
throw new FormatException($"Could not parse summand string: {summandString}. Format string not matched by summand patters - '|(+,-)(number)|<variables=(name)^(power)>'.");
}
var regexGroupResult = SummandRegex.Match(summandString).Groups;
var multiplierString = String.Empty;
if (regexGroupResult[MultiplierRegexGroupName].Captures.Count == 1)
{
multiplierString = regexGroupResult[MultiplierRegexGroupName].Captures[0].Value;
}
if (multiplierString.Equals(String.Empty) || multiplierString.Equals(Symbols.Minus.ToString()) ||
multiplierString.Equals(Symbols.Plus.ToString()))
{
multiplierString += "1";
}
var multiplier = float.Parse(multiplierString.Replace(',', '.'), NumberStyles.Any, CultureInfo.InvariantCulture.NumberFormat);
if (Math.Abs(multiplier) < float.Epsilon)
{
return(new Summand(0));
}
var variables = new List <Variable>();
foreach (Capture capture in regexGroupResult[VariblesRegexGroupName].Captures)
{
variables.Add(VariableParser.Parse(capture.Value));
}
return(new Summand(variables, multiplier));
}
/// <summary>
/// Parse a summand string e.g. 2x^2y^2
/// </summary>
public static Summand Parse(string input)
{
var coefficientString = CoefficientRegex.Match(input).Value;
var coefficient = String.IsNullOrEmpty(coefficientString) || coefficientString.Equals("+")
? 1
: coefficientString.Equals("-")
? -1
: float.Parse(coefficientString);
var variables = VariablesRegex
.Matches(input)
.Select(i => VariableParser.Parse(i.Value))
.GroupBy(i => i.Name)
.Select(i => new Variable(i.Key, i.Sum(j => j.Exponent)))
.OrderBy(i => i.Name)
.ToList();
var result = new Summand(coefficient, variables);
return(result);
}