/// <summary>
/// NFA building functions, build a NFA to find all words within given levenshtein distance from given word.
/// </summary>
/// <param name="str">The input word</param>
/// <param name="maxDist">The max levenshtein distance from input word</param>
/// <returns></returns>
public static LenvstnNFA BuildNFA(String str, int maxDist)
{
int width = str.Length + 1;
int height = maxDist + 1;
int size = width * height;
Set <state> final = new Set <state>();
for (int i = 1; i <= height; ++i)
{
final.Add(i * width - 1);
}
LenvstnNFA nfa = new LenvstnNFA(size, 0, final);
//Every state except those in right most coulmn in the matrix
for (int e = 0; e < height; ++e)
{
for (int i = 0; i < width - 1; ++i)
{
//trans to right
nfa.AddTrans(e * width + i, e * width + i + 1, str[i]);
if (e < (height - 1))
{
//trans to upper
nfa.AddTrans(e * width + i, (e + 1) * width + i, (char)Constants.Any);
//trans to diagonal upper
nfa.AddTrans(e * width + i, (e + 1) * width + i + 1, (char)Constants.EpsilonAny);
}
}
}
//right most column
for (int k = 1; k < height; ++k)
{
//trans to upper
nfa.AddTrans(k * width - 1, (k + 1) * width - 1, (char)Constants.Any);
}
return(nfa);
}
