public static int Search(string pattern, string source, int startIndex)
{
char[] x = pattern.ToCharArray(), y = source.ToCharArray(startIndex, source.Length - startIndex);
int j, init, ell, state, m = x.Length, n = y.Length;
Graph aut;
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
/* Preprocessing */
aut = Automata.NewSuffixAutomaton(2 * (m + 2), 2 * (m + 2) * 65536);
BuildSuffixAutomaton(x, ref aut);
init = Automata.GetInitial(aut);
stopwatch.Stop();
preProcessTime = stopwatch.Elapsed.TotalMilliseconds;
stopwatch.Restart();
/* Searching */
ell = 0;
state = init;
for (j = 0; j < n; ++j)
{
if (Automata.GetTarget(aut, state, y[j]) != -1)
{
++ell;
state = Automata.GetTarget(aut, state, y[j]);
}
else
{
while (state != init &&
Automata.GetTarget(aut, state, y[j]) == -1)
{
state = Automata.GetSuffixLink(aut, state);
}
if (Automata.GetTarget(aut, state, y[j]) != -1)
{
ell = Automata.GetLength(aut, state) + 1;
state = Automata.GetTarget(aut, state, y[j]);
}
else
{
ell = 0;
state = init;
}
}
if (ell == m)
{
stopwatch.Stop();
searchTime = stopwatch.Elapsed.TotalMilliseconds;
return(j - m + 1 + startIndex);
}
}
stopwatch.Stop();
searchTime = stopwatch.Elapsed.TotalMilliseconds;
return(-1);
}
private static void BuildSuffixAutomaton(char[] x, ref Graph aut)
{
int i, art, init, last, p, q, r, m = (x.Length - 1);
char c;
init = Automata.GetInitial(aut);
art = Automata.NewVertex(aut);
Automata.SetSuffixLink(aut, init, art);
last = init;
for (i = 0; i < m; ++i)
{
c = x[i];
p = last;
q = Automata.NewVertex(aut);
Automata.SetLength(aut, q, Automata.GetLength(aut, p) + 1);
Automata.SetPosition(aut, q, Automata.GetPosition(aut, p) + 1);
while (p != init &&
Automata.GetTarget(aut, p, c) == -1)
{
Automata.SetTarget(aut, p, c, q);
Automata.SetShift(aut, p, c, Automata.GetPosition(aut, q)
- Automata.GetPosition(aut, p) - 1);
p = Automata.GetSuffixLink(aut, p);
}
if (Automata.GetTarget(aut, p, c) == -1)
{
Automata.SetTarget(aut, init, c, q);
Automata.SetShift(aut, init, c, Automata.GetPosition(aut, q)
- Automata.GetPosition(aut, init) - 1);
Automata.SetSuffixLink(aut, q, init);
}
else if (Automata.GetLength(aut, p) + 1 == Automata.GetLength(
aut, Automata.GetTarget(aut, p, c)))
{
Automata.SetSuffixLink(aut, q, Automata.GetTarget(aut, p, c));
}
else
{
r = Automata.NewVertex(aut);
Automata.CopyVertex(aut, r, Automata.GetTarget(aut, p, c));
Automata.SetLength(aut, r, Automata.GetLength(aut, p) + 1);
Automata.SetSuffixLink(aut, Automata.GetTarget(aut, p, c), r);
Automata.SetSuffixLink(aut, q, r);
while (p != art &&
Automata.GetLength(aut, Automata
.GetTarget(aut, p, c)) >= Automata.GetLength(
aut, r))
{
Automata.SetShift(aut, p, c, Automata.GetPosition(aut,
Automata.GetTarget(aut, p, c))
- Automata.GetPosition(aut, p) - 1);
Automata.SetTarget(aut, p, c, r);
p = Automata.GetSuffixLink(aut, p);
}
}
last = q;
}
Automata.SetTerminal(aut, last);
while (last != init)
{
last = Automata.GetSuffixLink(aut, last);
Automata.SetTerminal(aut, last);
}
}