void create_parse_tree(String s)
{
int idctr = 1;
Stack <node> st = new Stack <node>();
foreach (char c in s)
{
if (Char.IsLetterOrDigit(c) || c == '#')
{
node tmp = new node(c);
tmp.ID = idctr;
tmp.lastpos.Add(idctr);
tmp.firstpos.Add(idctr++);
//tmp.left = null; tmp.right = null;
st.Push(tmp);
}
else
{
if (c == '*')
{
node d = st.Pop();
node now = new node(c);
now.firstpos = d.firstpos;
now.lastpos = d.lastpos;
now.left = d;
now.nullable = true;
//richTextBox1.Text += "\n*:"+now.lastpos.Count.ToString() + "_" + now.firstpos.Count.ToString();
st.Push(now);
}
if (c == '|' || c == '+')
{
node n1 = st.Pop();
node n2 = st.Pop();
node now = new node(c);
now.left = n2;
now.right = n1;
now.firstpos.UnionWith(n1.firstpos);
now.firstpos.UnionWith(n2.firstpos);
now.lastpos.UnionWith(n1.lastpos);
now.lastpos.UnionWith(n2.lastpos);
now.nullable = n1.nullable || n2.nullable;
//richTextBox1.Text += "\n|:" + now.lastpos.Count.ToString() + "_" + now.firstpos.Count.ToString();
st.Push(now);
}
if (c == '.')
{
node n1 = st.Pop();
node n2 = st.Pop();
node now = new node(c);
now.left = n2;
now.right = n1;
now.nullable = n1.nullable && n2.nullable;
if (n2.nullable)
{
now.firstpos.UnionWith(n1.firstpos);
now.firstpos.UnionWith(n2.firstpos);
}
else
{
now.firstpos.UnionWith(n2.firstpos);
}
if (n1.nullable)
{
now.lastpos.UnionWith(n1.lastpos);
now.lastpos.UnionWith(n2.lastpos);
}
else
{
now.lastpos.UnionWith(n1.lastpos);
}
//richTextBox1.Text += "\n.:" + now.lastpos.Count.ToString() + "_" + now.firstpos.Count.ToString();
st.Push(now);
}
}
}
tree tr = new tree(st.Pop());
tr.inorder(tr.root);
tr.followpos = new HashSet <int> [idctr - 1];
for (int p = 0; p < idctr - 1; p++)
{
tr.followpos[p] = new HashSet <int>();
}
tr.follow_pos(tr.root);
// MessageBox.Show((idctr - 1).ToString());
Console.WriteLine();
richTextBox1.Text += "\nfirstpos of root: ";
foreach (int x in tr.root.firstpos)
{
richTextBox1.Text += x.ToString() + "_";
}
richTextBox1.Text += "\nendpos of root: ";
foreach (int x in tr.root.lastpos)
{
richTextBox1.Text += x.ToString() + "_";
}
String fol = "";
for (int h = 0; h < tr.followpos.Length; h++)
{
fol += "\nfollowpos(" + (h + 1) + ")=";
foreach (var set in tr.followpos[h])
{
fol += set + ",";
}
}
richTextBox1.Text += fol + "\n";
gen_dfa(tr);
}
public tree(node n)
{
root = n;
}