public IEnumerable <Transition <Symbol, ProductionItem <TTokenKind> > > GetTransitions()
{
foreach (KeyValuePair <SourceTransitionPair <ProductionItem <TTokenKind>, Symbol>, HashSet <ProductionItem <TTokenKind> > > kvp in _delta)
{
ProductionItem <TTokenKind> sourceState = kvp.Key.SourceState;
Symbol label = kvp.Key.Label;
foreach (ProductionItem <TTokenKind> targetState in kvp.Value)
{
yield return(Transition.Move(sourceState, label, targetState));
}
}
}
public bool Equals(ProductionItem <TTokenKind> other, ProductionItemComparison comparison)
{
switch (comparison)
{
case ProductionItemComparison.MarkedProductionOnly:
return(MarkedProduction.Equals(other.MarkedProduction)); // CORE is the same
case ProductionItemComparison.LookaheadsOnly:
return(Lookaheads.SetEquals(other.Lookaheads));
case ProductionItemComparison.MarkedProductionAndLookaheads:
default:
return(MarkedProduction.Equals(other.MarkedProduction) && Lookaheads.SetEquals(other.Lookaheads));
}
}
public LrItemNfa(
IEnumerable <Transition <Symbol, ProductionItem <TTokenKind> > > transitions,
ProductionItem <TTokenKind> startState,
IEnumerable <ProductionItem <TTokenKind> > acceptStates)
{
StartState = startState;
_acceptStates = new HashSet <ProductionItem <TTokenKind> >(acceptStates);
_states = new HashSet <ProductionItem <TTokenKind> >(acceptStates)
{
startState
};
_delta = new Dictionary <SourceTransitionPair <ProductionItem <TTokenKind>, Symbol>, HashSet <ProductionItem <TTokenKind> > >();
_alphabet = new Set <Symbol>();
foreach (var triple in transitions)
{
_states.Add(triple.SourceState);
_states.Add(triple.TargetState);
var pair = Transition.FromPair(triple.SourceState, triple.Label);
if (_delta.ContainsKey(pair))
{
_delta[pair].Add(triple.TargetState);
}
else
{
_delta[pair] = new HashSet <ProductionItem <TTokenKind> > {
triple.TargetState
}
};
if (triple.Label.Equals(Symbol.Epsilon))
{
IsEpsilonNfa = true;
}
else
{
_alphabet.Add(triple.Label); // alphabet does not contain epsilon
}
}
}
ProductionItemSet <TTokenKind> EpsilonClose(IEnumerable <ProductionItem <TTokenKind> > kernelItems)
{
var markedVisitedStates = new Queue <ProductionItem <TTokenKind> >(kernelItems);
// base step
var closure = new Set <ProductionItem <TTokenKind> >(kernelItems);
// induction step: recurse until no more states in a round
while (markedVisitedStates.Count != 0)
{
ProductionItem <TTokenKind> sourceState = markedVisitedStates.Dequeue();
// if any epsilon-moves add them all to the closure (union)
foreach (var targetState in Delta(Transition.FromPair(sourceState, Symbol.Epsilon)))
{
if (!closure.Contains(targetState))
{
closure.Add(targetState);
markedVisitedStates.Enqueue(targetState);
}
}
}
return(new ProductionItemSet <TTokenKind>(closure));
}
public bool Equals(ProductionItem <TTokenKind> other)
{
return(Equals(other, ProductionItemComparison.MarkedProductionAndLookaheads));
}
public bool IsAcceptState(ProductionItem <TTokenKind> state)
{
return(_acceptStates.Contains(state));
}
public bool Contains(ProductionItem <TTokenKind> item)
{
return(_kernelItems.Contains(item) || _closureItems.Contains(item));
}