/// <summary>
/// Perfomrs Chomsky analysis and reduces list elements, extracting equal parts into newly created elements.
/// The method is similar to compression.
/// </summary>
/// <param name="melodyPartNodes">All nodes including input and all produced nodes</param>
/// <param name="scales">
/// Scales for diatonic option. Within the list no scale should be similar to any other.
/// Two scales are similar if one is inversion of another one,
/// for example major and minor scale,
/// but minor haromnic, minor melodic and minor natural are not similar to each other.
/// If null, no diatonic option.
/// </param>
public static List <MelodyPartList> Reduce(IEnumerable <MelodyPartList> melodyPartNodes, List <TwelveToneSet> scales = null)
{
List <MelodyPartList> allNodes = new List <MelodyPartList>(melodyPartNodes);
int maxListCount = int.MaxValue;
List <TwelveToneSet> allScales = CalculateAllScales(scales);
Swap swap = FindLongestSwap(melodyPartNodes, allScales);
int count = 500;
while (swap.list.Count > 2)
{
swap.AssertCorrect();
// Assert the chunck size is not increasing
Debug.Assert(swap.list.Count <= maxListCount);
maxListCount = swap.list.Count;
// If there is identical list already, don't add it, use the identical one
MelodyPartList nodeExisting;
if ((nodeExisting = allNodes.Find(node => node.IsIdentical(swap.list))) != null)
{
swap.list = nodeExisting;
}
else
{
allNodes.Add(swap.list);
}
//Assert that at most one part is whole
if (swap.IsWhole1 && swap.IsWhole2 &&
swap.pnt1.part.type != MelodyPartList.Type.Voice &&
swap.pnt2.part.type != MelodyPartList.Type.Voice)
{
Debug.Fail(message: "There are two identical parts. One should have referenced another instead of being created.");
}
int offset1 = swap.pnt1.MelodyPart.GetNotes().First().note;
swap.pnt1.part.RemoveRange(swap.pnt1.firstNoteIndex, swap.list.Count);
MelodyPart mp1 = swap.IsDToC ?
new MelodyPartDtoC(offset1, swap.scales1.First(), swap.list) :
new MelodyPart(offset1, swap.list);
swap.pnt1.part.Insert(swap.pnt1.firstNoteIndex, mp1);
if (!swap.IsWhole2 || swap.IsDToC)
{
// If it's the same part, adjust the pnt2.index
if (swap.pnt1.part == swap.pnt2.part)
{
swap.pnt2.firstNoteIndex -= swap.list.Count - 1;
}
int offset2 = swap.pnt2.MelodyPart.GetNotes().First().note;
swap.pnt2.part.RemoveRange(swap.pnt2.firstNoteIndex, swap.list.Count);
MelodyPart mp2 = swap.IsDToC ?
new MelodyPartDtoC(offset2, swap.scales2.First(), swap.list) :
new MelodyPart(offset2, swap.list);
swap.pnt2.part.Insert(swap.pnt2.firstNoteIndex, mp2);
}
else
{
// This is unexpected, but may be possible.
// If it happens rethink it.
Debug.Assert(!swap.IsDToC);
}
if (--count <= 0)
{
break;
}
// Next swap
swap = FindLongestSwap(allNodes, allScales);
}
;
foreach (var list in melodyPartNodes)
{
Debug.Assert(list.RecursiveCount > 1);
}
return(allNodes);
}
