// seqSets is a sequence (ordered) of sets (unordered)
// muliconcat computes cartesian product in order of given sequence, with limit of the given width
// (a1,a2) x (b1,b2) will give (a1,b2) but not (b1,a2)
// not that nice as recursive version, but faster (around 25% increase in speed after using this version)
public static SymbolChunkSet <SYMBOL_ENUM> MultiConcat <SYMBOL_ENUM>(SymbolChunkSet <SYMBOL_ENUM>[] seq_sets,
int lookaheadWidth)
where SYMBOL_ENUM : struct
{
if (seq_sets.Length == 0)
{
return(new SymbolChunkSet <SYMBOL_ENUM>());
}
else
{
var finished = new List <SymbolChunk <SYMBOL_ENUM> >();
var incomplete = new List <SymbolChunk <SYMBOL_ENUM> >();
foreach (SymbolChunk <SYMBOL_ENUM> chunk in seq_sets[0].Chunks)
{
var copy = chunk.GetFirst(lookaheadWidth);
if (copy.Count == lookaheadWidth)
{
finished.Add(copy);
}
else
{
incomplete.Add(copy);
}
}
for (int i = 1; incomplete.Any() && i < seq_sets.Length; ++i)
{
var seeds = incomplete;
incomplete = new List <SymbolChunk <SYMBOL_ENUM> >();
foreach (SymbolChunk <SYMBOL_ENUM> seed in seeds)
{
foreach (SymbolChunk <SYMBOL_ENUM> chunk in seq_sets[i].Chunks)
{
var copy = seed.Concat(chunk, lookaheadWidth);
if (copy.Count == lookaheadWidth)
{
finished.Add(copy);
}
else
{
incomplete.Add(copy);
}
}
}
}
finished.AddRange(incomplete);
return(SymbolChunkSet.Create(finished));
}
}
// creates all combinations of symbols up to length given by lookaheadWidth
// example: A, B, C, up to 2
// will give: (empty), A, B, C, AA, AB, AC, BA, BB, BC, CA, CB, CC
public static SymbolChunkSet <SYMBOL_ENUM> MultiplyUpTo <SYMBOL_ENUM>(IEnumerable <SYMBOL_ENUM> symbols,
int lookaheadWidth)
where SYMBOL_ENUM : struct
{
var seed = SymbolChunkSet.Create(symbols.Select(it => SymbolChunk.Create(it)));
var working = new SymbolChunkSet <SYMBOL_ENUM>();
var result = new SymbolChunkSet <SYMBOL_ENUM>();
result.Add(SymbolChunk.Create <SYMBOL_ENUM>()); // empty entry
foreach (var _ in Enumerable.Repeat(0, lookaheadWidth))
{
working = MultiConcat(new[] { working, seed }, lookaheadWidth);
result.Add(working);
}
return(result);
}