protected virtual void PopulateNextCache()
{
for (int i = 0; i < TargetGrammar.Count; i++)
{
var r = initialListing[TargetGrammar[i]];
for (int j = 0; j < r.Count; j++)
{
AdvanceableProduction prod = r[j];
while (prod.HasNext)
{
var tmp = prod.FunctionalNext();
advancementDict[prod] = tmp;
prod = tmp;
}
advancementDict[prod] = prod;
terminates[prod] = new AdvanceableRule(r.Name);
terminates[prod].Add(prod);
}
}
}
private string ToString0(AdvanceableProduction production)
{
StringBuilder sb = new StringBuilder();
sb.AppendFormat("[{0} => ",Name);
for(int i = 0;i < production.Min; i++)
sb.AppendFormat("{0} ", production[i]);
sb.Append("!");
for(int i = production.Min;i < production.Position; i++)
sb.AppendFormat("{0} ", production[i]);
sb.Append("@");
for(int i = production.Position; i < production.Max; i++)
sb.AppendFormat("{0} ", production[i]);
sb.AppendFormat(", {0}]", LookaheadSymbol);
return sb.ToString();
}
public override IEnumerable <LookaheadRule> Closure(
IEnumerable <LookaheadRule> rules,
string terminateSymbol)
{
//Closure is more refined.
//If [A → α • B β, a] belongs to the set of items,
//and B → γ is a production of the grammar,
//then we add the item [B → • γ, b] for all b in FIRST(β a).
HashSet <LookaheadRule> rr = new HashSet <LookaheadRule>(rules);
int size = currentRules.Count;
do
{
size = rr.Count;
//get rid of the
foreach (var rule in rr)
{
var a = rule.LookaheadSymbol;
var container = singles[rule.Name][rule.LookaheadSymbol];
for (int j = 0; j < rule.Count; j++)
{
var p = rule[j];
string symbol = p.Current;
if (!p.HasNext)
{
nullTerminators.Add(terminates[p]);
}
else
{
if (TargetGrammar.Exists(symbol))
{
AdvanceableProduction betaProd = advancementDict[p]; //create beta
var target = initialListing[TargetGrammar[symbol]]; //grab the B-Production
var actualTarget = memo[target];
if (!betaProd.HasNext && a.Equals(terminateSymbol))
{
currentRules.Add(actualTarget[terminateSymbol]);
}
else
{
if (betaProd.HasNext)
{
var next = container[p];
var ff = First(next, betaProd.Position);
foreach (var v in ff)
{
currentRules.Add(actualTarget[v]);
}
}
currentRules.Add(actualTarget[a]);
}
}
}
}
}
rr.UnionWith(currentRules);
currentRules.Clear();
}while(rr.Count != size);
for (int n = 0; n < nullTerminators.Count; n++)
{
var v = nullTerminators[n];
string name = v.Name;
foreach (var s in rr)
{
if (s.Name.Equals(name))
{
foreach (var qq in v)
{
if (!s.Contains(qq))
{
s.Add(qq);
}
}
}
}
}
if (nullTerminators.Count > 0)
{
nullTerminators.Clear();
}
if (currentRules.Count > 0)
{
currentRules.Clear();
}
return(rr);
}