public RegExpTreeItem Load(String s)
{
if (s.Length == 0) return null;
Char last = s[s.Length - 1];
if (last == ']')
{
int i = s.Length - 2;
while (s[i] != '[' && i > 0) i--;
if (s[i] != '[') throw new Exception("No corresponding bracket!");
RegExpTreeItem res = new RegExpTreeItem();
String right = s.Substring(i + 1, s.Length - i - 2);
RegExpTreeItem rightitem = Roots.ContainsKey(right)
? Roots[right].Clone().Children[0]
: new RegExpTreeItem() { Op = Operation.NONE, Value = right[0] };
if (i == 0)
return rightitem;
String left = String.Empty;
if (s[i - 1] == '|')
{
res.Op = Operation.OR;
left = s.Substring(0, i - 1);
}
else
{
left = s.Substring(0, i);
res.Op = Operation.AND;
}
res.Children.Add(Load(left));
res.Children.Add(rightitem);
return res;
}
if (last == ')')
{
int i = s.Length - 2;
int count = 1;
while (i > 0 && count != 0)
{
if (s[i] == ')') count++;
if (s[i] == '(') count--;
if (count == 0) break;
i--;
}
if (i == 0 && s[i] == '(') count--;
if (s[i] != '(' || count != 0)
throw new Exception("No corresponding bracket!");
RegExpTreeItem res = new RegExpTreeItem();
String right = s.Substring(i + 1, s.Length - i - 2);
if (right == String.Empty) return new RegExpTreeItem() { Op = Operation.LAMBDA };
if (i == 0) return Load(right);
String left = String.Empty;
if (s[i - 1] == '|')
{
res.Op = Operation.OR;
left = s.Substring(0, i - 1);
}
else
{
left = s.Substring(0, i);
res.Op = Operation.AND;
}
res.Children.Add(Load(left));
res.Children.Add(Load(right));
return res;
}
if (last == '*' && s.Length > 1)
{
String expr = s.Substring(0, s.Length - 1);
RegExpTreeItem res = new RegExpTreeItem() { Op = Operation.MULT };
res.Children.Add(Load(expr));
return res;
}
if (Special.Contains(last))
throw new Exception("Single special item " + last + "!");
if (s.Length == 1)
return new RegExpTreeItem() { Op = Operation.NONE, Value = last };
if (s[s.Length - 2] == '|')
{
String expr = s.Substring(0, s.Length - 2);
if (expr.Length == 0) throw new Exception("Nothing to the left of |!");
RegExpTreeItem res = new RegExpTreeItem() { Op = Operation.OR };
res.Children.Add(Load(expr));
res.Children.Add(new RegExpTreeItem() { Op = Operation.NONE, Value = last });
return res;
}
RegExpTreeItem rs = new RegExpTreeItem() { Op = Operation.AND };
rs.Children.Add(Load(s.Substring(0, s.Length - 1)));
rs.Children.Add(new RegExpTreeItem() { Op = Operation.NONE, Value = last });
return rs;
}
public RegExpTreeItem Clone()
{
RegExpTreeItem res = new RegExpTreeItem();
res.Op = Op;
res.Value = Value;
foreach (var child in Children)
res.Children.Add(child.Clone());
return res;
}
private void Copy(RegExpTreeItem from, RegExpTreeItem to)
{
to.Value = from.Value;
to.Op = from.Op;
foreach (var child in from.Children)
{
var tochild = new RegExpTreeItem();
to.Children.Add(tochild);
Copy(child, tochild);
}
}
