//TODO: test for this
public StackSymbolSequence <S> GetLongestPossibleCommonTail(StackSymbolSequence <S> other)
{
var reverseZipped = StackSequence.Reverse().Zip(other.StackSequence.Reverse(), (first, second) => new { first, second });
var tail = reverseZipped.TakeWhile(el => el.first.Equals(el.second)).Select(el => el.first).Reverse().ToList();
return(new StackSymbolSequence <S>(tail));
}
private static void AddSingleTransitionToPDA(PDA <A, StackSymbolSequence <S> > targetPDA, IEnumerable <Transition <A, S> > originTransitions, Transition <A, S> outerOrigTransition)
{
var stackSymbolQueue = new Queue <StackSymbolSequence <S> >();
var readStackSymbol = new StackSymbolSequence <S>(outerOrigTransition.StackSymbolIn);
AddToCollectionsIfNotAlreadyExisting(stackSymbolQueue, targetPDA, readStackSymbol);
while (stackSymbolQueue.Count > 0)
{
AddTransitionsForNewStackSymbol(targetPDA, originTransitions, stackSymbolQueue);
}
}
private static void AddTransitionsForNewStackSymbol(PDA <A, StackSymbolSequence <S> > targetPDA, IEnumerable <Transition <A, S> > originTransitions, Queue <StackSymbolSequence <S> > stackSymbolQueue)
{
var next = stackSymbolQueue.Dequeue();
foreach (var innerOriginTransition in originTransitions.Where(t => next.StackSequence.First().Equals(t.StackSymbolIn)))
{
var upperWrittenSymbol = new StackSymbolSequence <S>(innerOriginTransition.StackSymbolsWritten);
var lowerWrittenSymbl = new StackSymbolSequence <S>(next.StackSequence.Skip(1).ToArray());
var newStackSymbolsWritten = GetNotEmptyStackSymbols(ArrayOf(upperWrittenSymbol, lowerWrittenSymbl));
foreach (var s in newStackSymbolsWritten)
{
AddToCollectionsIfNotAlreadyExisting(stackSymbolQueue, targetPDA, s);
}
targetPDA.AddTransition().From(innerOriginTransition.Origin.Id).To(innerOriginTransition.Target.Id).Read(innerOriginTransition.SymbolIn).Pop(next).Push(newStackSymbolsWritten);
}
}
private static void AddToCollectionsIfNotAlreadyExisting(Queue <StackSymbolSequence <S> > stackSymbolQueue, PDA <A, StackSymbolSequence <S> > pda, StackSymbolSequence <S> stackSymbol)
{
if (!pda.AllStackSymbols.Any(s => s.Equals(stackSymbol)))
{
pda.AddStackSymbol(stackSymbol);
stackSymbolQueue.Enqueue(stackSymbol);
}
}
public StackSymbolSequence <S> GetHeadWithRespectToTail(StackSymbolSequence <S> tail)
{
Assertion.Assert(EndsWith(tail), "the given tail has to be a tail of this stack sequence");
return(new StackSymbolSequence <S>(StackSequence.Take(StackSequence.Count() - tail.StackSequence.Count()).ToList()));
}
public bool EndsWith(StackSymbolSequence <S> tail)
{
return(StackSequence.Count() >= tail.StackSequence.Count() &&
new StackSymbolSequence <S>(StackSequence.Skip(StackSequence.Count() - tail.StackSequence.Count()).ToList()).Equals(tail));
}
public bool Equals(StackSymbolSequence <S> other)
{
return(StackSequence.SequenceEqual(other.StackSequence));
}