private ulong GetFrequency(ulong linkIndex, ulong source, ulong target)
{
var frequency = (_linkFrequenciesCache.GetFrequency(source, target) ?? new LinkFrequency <ulong>(0, 0)).Frequency;
if (frequency == default && linkIndex > 0)
{
frequency = _totalSequenceSymbolFrequencyCounter.Count(linkIndex);
}
return(frequency);
}
private IList <TLink> Compress(IList <TLink> sequence)
{
if (sequence.IsNullOrEmpty())
{
return(null);
}
if (sequence.Count == 1)
{
return(sequence);
}
if (sequence.Count == 2)
{
return(new[] { _links.GetOrCreate(sequence[0], sequence[1]) });
}
// TODO: arraypool with min size (to improve cache locality) or stackallow with Sigil
var copy = new HalfDoublet[sequence.Count];
Doublet <TLink> doublet = default;
for (var i = 1; i < sequence.Count; i++)
{
doublet = new Doublet <TLink>(sequence[i - 1], sequence[i]);
LinkFrequency <TLink> data;
if (_doInitialFrequenciesIncrement)
{
data = _doubletFrequenciesCache.IncrementFrequency(ref doublet);
}
else
{
data = _doubletFrequenciesCache.GetFrequency(ref doublet);
if (data == null)
{
throw new NotSupportedException("If you ask not to increment frequencies, it is expected that all frequencies for the sequence are prepared.");
}
}
copy[i - 1].Element = sequence[i - 1];
copy[i - 1].DoubletData = data;
UpdateMaxDoublet(ref doublet, data);
}
copy[sequence.Count - 1].Element = sequence[sequence.Count - 1];
copy[sequence.Count - 1].DoubletData = new LinkFrequency <TLink>();
if (_comparer.Compare(_maxDoubletData.Frequency, default) > 0)
{
var newLength = ReplaceDoublets(copy);
sequence = new TLink[newLength];
for (int i = 0; i < newLength; i++)
{
sequence[i] = copy[i].Element;
}
}
return(sequence);
}
