private SortedSet <IDottedRule> GetPredictedStates(DottedRuleSet frame)
{
var pool = SharedPools.Default <Queue <IDottedRule> >();
var queue = pool.AllocateAndClear();
var closure = new SortedSet <IDottedRule>();
for (int i = 0; i < frame.Data.Count; i++)
{
var state = frame.Data[i];
if (!IsComplete(state))
{
queue.Enqueue(state);
}
}
while (queue.Count > 0)
{
var state = queue.Dequeue();
if (IsComplete(state))
{
continue;
}
var postDotSymbol = GetPostDotSymbol(state);
if (postDotSymbol.SymbolType != SymbolType.NonTerminal)
{
continue;
}
var nonTerminalPostDotSymbol = postDotSymbol as INonTerminal;
if (Grammar.IsTransativeNullable(nonTerminalPostDotSymbol))
{
var preComputedState = GetPreComputedState(state.Production, state.Position + 1);
if (!frame.Contains(preComputedState))
{
if (closure.Add(preComputedState))
{
if (!IsComplete(preComputedState))
{
queue.Enqueue(preComputedState);
}
}
}
}
var predictions = Grammar.RulesFor(nonTerminalPostDotSymbol);
for (var p = 0; p < predictions.Count; p++)
{
var prediction = predictions[p];
var preComputedState = GetPreComputedState(prediction, 0);
if (frame.Contains(preComputedState))
{
continue;
}
if (!closure.Add(preComputedState))
{
continue;
}
if (!IsComplete(preComputedState))
{
queue.Enqueue(preComputedState);
}
}
}
pool.ClearAndFree(queue);
return(closure);
}