///<summary>
/// Candidates are lowercase letters.
/// Utility may be positional or explicit.
/// Positional utility groups candidates into space-separated buckets, assigning utility 100 to the first bucket and utility 0 to omitted candidates. Buckets in between are evenly pro-rated.
/// Buckets prefixed by an integer and a colon assign that integer utility to the bucket, overriding any positional utility.
///</summary>
public static Voter Parse(int candidateCount, string voter)
{
var buckets = voter.Split(' ', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
var utilities = new int[candidateCount];
for (var i = 0; i < buckets.Length; i++)
{
var match = Regex.Match(buckets[i], @"^(-?\d*):?([a-z]+)$");
if (!match.Success)
{
throw new InvalidOperationException($"Unexpected bucket format '{buckets[i]}'.");
}
var utility = int.TryParse(match.Groups[1].Value, out var parsed)
? parsed
: BucketDefaultUtility(i, buckets.Length);
foreach (var c in match.Groups[2].Value)
{
utilities[ParsingUtility.DecodeCandidateIndex(c)] = utility;
}
}
return(new Voter(utilities));
}
///<summary>
/// Comparers are separated by newlines or semicolons.
/// Candidates are lowercase letters.
/// Comparers may be duplicated by suffixing the line with "* nn", where "nn" is a positive integer.
///</summary>
public static CandidateComparerCollection <T> Parse(string source, int?candidateCount = null)
{
candidateCount ??= ParsingUtility.CandidateCount(source);
if (candidateCount < 2)
{
throw new InvalidOperationException("Unexpected number of candidates.");
}
return(new CandidateComparerCollection <T>(
candidateCount.Value,
source
.Split(new char[] { '\n', ';' }, StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
.Select(line =>
{
var starSplit = line.Split('*', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
if (starSplit.Length > 2)
{
throw new InvalidOperationException($"Unexpected number of *s on line '{line}'.");
}
return (
Comparer: ParseComparer(candidateCount.Value, starSplit[0]),
Count: starSplit.Length == 2
? int.Parse(starSplit[1])
: 1);
})
.ToCountedList()));
}
public override string ToString()
{
var numberOfBuckets = Ranking.Count - (Utilities.Any(u => u == 0) ? 1 : 0);
return(Ranking
.Where(candidates => Utilities[candidates[0]] != 0)
.Select((candidates, bucketNumber) =>
BucketDefaultUtility(bucketNumber, numberOfBuckets) == Utilities[candidates[0]]
? ParsingUtility.EncodeCandidates(candidates)
: Utilities[candidates[0]].ToString() + ParsingUtility.EncodeCandidates(candidates))
.Join(" "));
}
