public DiGraph reverse()
{
DiGraph R = new DiGraph(V);
for (int v = 0; v < V; v++)
foreach (int w in Adj(v))
R.addEdge(w, v);
return R;
}
private int M; // number of states
public NFA(string regexp)
{ // Create the NFA for the given regular expression.
Stack <int> ops = new Stack <int>();
re = regexp.ToCharArray();
M = re.Length;
G = new DiGraph(M + 1);
for (int i = 0; i < M; i++)
{
int lp = i;
if (re[i] == '(' || re[i] == '|')
{
ops.Push(i);
}
else if (re[i] == ')')
{
int or = ops.Pop();
if (re[or] == '|')
{
lp = ops.Pop();
G.addEdge(lp, or + 1);
G.addEdge(or, i);
}
else
{
lp = or;
}
}
if (i < M - 1 && re[i + 1] == '*') // lookahead
{
G.addEdge(lp, i + 1);
G.addEdge(i + 1, lp);
}
if (re[i] == '(' || re[i] == '*' || re[i] == ')')
{
G.addEdge(i, i + 1);
}
}
}
public DiGraph reverse()
{
DiGraph R = new DiGraph(V);
for (int v = 0; v < V; v++)
{
foreach (int w in Adj(v))
{
R.addEdge(w, v);
}
}
return(R);
}
private char[] re; // match transitions
#endregion Fields
#region Constructors
public NFA(string regexp)
{
// Create the NFA for the given regular expression.
Stack<int> ops = new Stack<int>();
re = regexp.ToCharArray();
M = re.Length;
G = new DiGraph(M + 1);
for (int i = 0; i < M; i++)
{
int lp = i;
if (re[i] == '(' || re[i] == '|')
ops.Push(i);
else if (re[i] == ')')
{
int or = ops.Pop();
if (re[or] == '|')
{
lp = ops.Pop();
G.addEdge(lp, or + 1);
G.addEdge(or, i);
}
else lp = or;
}
if (i < M - 1 && re[i + 1] == '*') // lookahead
{
G.addEdge(lp, i + 1);
G.addEdge(i + 1, lp);
}
if (re[i] == '(' || re[i] == '*' || re[i] == ')')
G.addEdge(i, i + 1);
}
}
