public static NFA CreateAutomaton(string a)
{
var result = new NFA();
var start = 0;
var next = 1;
result.AddState(start, false);
for (int i = 0; i < a.Length; ++i)
{
if (a[i] == '*')
{
result.AddTransition(next - 1, next - 1, NFA.Any);
}
else
{
result.AddState(next, false);
result.AddTransition(next - 1, next, (a[i] != '?' ? CharRange.SingleChar(a[i]) : NFA.Any));
++next;
}
}
result.AddState(next, true);
result.AddTransition(next - 1, next, NFA.Epsilon);
return(result);
}
public static NFA CreateAutomaton(string a, int k)
{
if (a.Contains('*'))
{
throw new ArgumentException("Star is a reserved character");
}
var result = new NFA();
var m = a.Length + 1;
/* Create |a|*k states */
for (int i = 0; i < m; ++i)
{
for (int j = 0; j <= k; ++j)
{
result.AddState(i + m * j, i == a.Length);
}
}
/* Create transitions */
for (int i = 0; i < m; ++i)
{
for (int j = 0; j <= k; ++j)
{
if (i < m - 1)
{
result.AddTransition(i + m * j, i + 1 + m * j, CharRange.SingleChar(a[i]));
}
if (j < k)
{
if (i < m - 1)
{
result.AddTransition(i + m * j, i + 1 + m * (j + 1), NFA.Any);
result.AddTransition(i + m * j, i + 1 + m * (j + 1), NFA.Epsilon);
}
result.AddTransition(i + m * j, i + m * (j + 1), NFA.Any);
}
}
}
return(result);
}
public void AddTransition(int from, int to, CharRange c)
{
transitions[from].Add(new ValueTuple <CharRange, int>(c, to));
}
public static IEnumerable <CharRange> Disjoin(this IEnumerable <CharRange> ranges)
{
var pqueue = new SortedSet <CharRange>(ranges, Comparer <CharRange> .Create((x, y) =>
{
if (x.start == y.start)
{
return(y.end - x.end);
}
return(y.start - x.start);
}));
while (pqueue.Count > 1)
{
var current = pqueue.Max;
pqueue.Remove(current);
var next = pqueue.Max;
if (current.end == next.start)
{
pqueue.Remove(next);
if (current.start <= current.end - 1)
{
pqueue.Add(new CharRange(current.start, current.end - 1));
}
pqueue.Add(new CharRange(next.start, next.start));
if (next.start + 1 <= next.end)
{
pqueue.Add(new CharRange(next.start + 1, next.end));
}
}
else if (current.end > next.start)
{
pqueue.Remove(next);
if (current.start < next.start)
{
var first = new CharRange(current.start, next.start - 1);
pqueue.Add(first);
}
var firstEnd = Math.Min(current.end, next.end);
var lastEnd = Math.Max(current.end, next.end);
if (next.start <= firstEnd)
{
var second = new CharRange(next.start, firstEnd);
pqueue.Add(second);
}
if (firstEnd + 1 < lastEnd)
{
var third = new CharRange(firstEnd + 1, lastEnd);
pqueue.Add(third);
}
}
else
{
yield return(current);
}
}
if (pqueue.Count > 0)
{
yield return(pqueue.Max);
}
}