static void CollectChains(SentenceConstruct sen, SqliteCommand cmd)
{
while (sen.Continue)
{
string chain = sen.LatestChain();
// Seems like Add is slightly faster than AddWithValue, although the difference is so small it only
// makes sense to use it in this loop, where it can get called 10's of thousands of times.
cmd.Parameters.Add("@Chain", DbType.String).Value = chain;
var followUp = (string)cmd.ExecuteScalar();
// If the chain couldn't be found (followUp is null) or if the chain is an ending chain (followUp is
// empty) stop collecting chains.
if (!string.IsNullOrEmpty(followUp))
{
sen.ModeAdd(followUp);
}
else
{
return;
}
}
}
IEnumerable <Sentence> Builder(BuilderVectors v)
{
// Copies out the volatile field, so we have a consistent MaxWords while building.
var words = new SentenceConstruct(Order, MaxWords);
using (var reader = v.StartingChains.ExecuteReader())
{
while (reader.Read())
{
string backward = reader.GetString(0);
string chain = reader.GetString(1);
string forward = reader.GetString(2);
words.Set(chain);
if (backward != string.Empty)
{
// Backward search.
words.PrependMode();
words.ModeAdd(backward);
CollectChains(words, v.BackwardSearch);
}
if (forward != string.Empty && words.Continue)
{
// Forward search.
words.AppendMode();
words.ModeAdd(forward);
CollectChains(words, v.ForwardSearch);
}
var segment = words.CurrentSegment();
long[] wordCounts = WordCount(segment, v.WordCount);
yield return(new Sentence(segment, wordCounts));
}
}
}
