private static bool CheckIfStackIsEmpty <U, V>(PDA <U, V> pda, Transition <U, V> epsilonTransition, VirtualConfiguration <U, V> currentConfig) where U : IEquatable <U> where V : IEquatable <V>
{
if (currentConfig.stack.Count() == 0)
{
pda.RemoveTransition(epsilonTransition);
pda.AddTransition().From(epsilonTransition.Origin.Id).To(currentConfig.state.Id).Read().Pop(epsilonTransition.StackSymbolIn).Push();
return(true);
}
return(false);
}
internal bool IsStartOfNotDecreasingCircle(VirtualConfiguration <U, V> circleEndConfig)
{
return(circleEndConfig.state.Id == state.Id && stack.Count() <= circleEndConfig.stack.Count());
}
private static bool CheckIfConfigIsStable <U, V>(PDA <U, V> pda, Transition <U, V> epsilonTransition, VirtualConfiguration <U, V> currentConfig) where U : IEquatable <U> where V : IEquatable <V>
{
var enterableTransitions = currentConfig.GetEnterableTransitions();
var enterableEpsilonTransitions = enterableTransitions.Where(t => t.SymbolIn.IsEmpty()).ToList();
Assertion.Assert(enterableEpsilonTransitions.Count <= 1, "a DPDA can only have one enterable epsilon transition in each configuration");
if (enterableEpsilonTransitions.Count == 0)
{
pda.RemoveTransition(epsilonTransition);
foreach (var transition in enterableTransitions)
{
Assertion.Assert(!transition.SymbolIn.IsEmpty(), "there should be no epsilon transitions at this point");
var newStack = transition.StackSymbolsWritten.Concat(currentConfig.stack.Skip(1).ToList()).ToList();
pda.AddTransition().From(epsilonTransition.Origin.Id).To(transition.Target.Id).Read(transition.SymbolIn).Pop(epsilonTransition.StackSymbolIn).Push(newStack);
}
return(true);
}
return(false);
}
