public FirstSetBuilder(cfg cfg)
{
FirstSets = new FirstSet();
this.cfg = cfg;
Empty = System.Configuration.ConfigurationManager.AppSettings["Empty"][0];
foreach (char c in cfg.Vn)
{
FirstSets.Add(c, new HashSet <char>());
}
Build();
}
public static void Closure(this ItemSet itemset, cfg cfg, FirstSet first)
{
HashSet <Production> productions = cfg.Productions;
bool changed;
do
{
changed = false;
char end = System.Configuration.ConfigurationManager.AppSettings["End"][0];
for (int i = 0; i < itemset.Count; ++i)
{
Item item = itemset.ElementAt(i);
int index = item.Index;
string right = item.Production.Right;
if (index >= right.Length || !cfg.isVn(right[index]))
{
continue;
}
foreach (Production production in productions)
{
if (production.Left != right[index])
{
continue;
}
int length = right.Length;
if (index + 1 == right.Length)
{
Item newItem = new Item(production, 0, item.Symbol);
changed |= itemset.AddItem(newItem);
continue;
}
if (index + 1 < right.Length)
{
char empty = System.Configuration.ConfigurationManager.AppSettings["Empty"][0];
HashSet <char> symbols = first.GetFirst(right[index + 1]);
foreach (char c in symbols)
{
if (c == empty)
{
Item newItem = new Item(production, 0, item.Symbol);
changed |= itemset.Add(newItem);
}
else
{
Item newItem = new Item(production, 0, c);
changed |= itemset.Add(newItem);
}
}
}
}
}
} while (changed);
}
public TableBuilder(cfg cfg, FirstSet first)
{
this.CFG = cfg;
this.First = first;
Build();
}
