internal bool Connect(ActiveEdge edge)
{
if (!_activeEdges.Add(edge))
{
return(false);
}
var currentTerm = edge.Label.CurrentTerm;
var terminal = edge.Label.TerminalLabel;
if (terminal != null)
{
//label is waiting for terminal
_waitingTerminals.Add(terminal);
}
HashSet <ActiveEdge> extensible;
if (!_extensibleEdges.TryGetValue(currentTerm, out extensible))
{
extensible = new HashSet <ActiveEdge>();
_extensibleEdges[currentTerm] = extensible;
}
extensible.Add(edge);
return(true);
}
internal ActiveEdge(ActiveEdge extendedEdge, CompleteEdge extendingEdge)
: base(extendedEdge.StartContext, extendingEdge.EndContext)
{
ExtendingEdge = extendingEdge;
ExtendedEdge = extendedEdge;
Label = ExtendedEdge.Label.NextInChain;
}
internal CompleteEdge(ActiveEdge extendedEdge, CompleteEdge extendingEdge)
: base(extendedEdge.StartContext, extendingEdge.EndContext)
{
CompleteLabel = extendedEdge.Label.CompleteLabel;
Parent = CompleteLabel.Parent;
ExtendedEdge = extendedEdge;
ExtendingEdge = extendingEdge;
}
private static void predict(CompleteEdge constituent, ActiveEdge edge)
{
//TODO check if new possible interpretation of input is added
var newEdge = edge.ExtendBy(constituent);
var endContext = newEdge.EndContext;
if (endContext.Connect(newEdge))
{
foreach (var transition in newEdge.Label.Transitions)
{
var transitionEdge = new ActiveEdge(transition, newEdge);
endContext.Connect(transitionEdge);
}
}
}
private void complete(CompleteEdge constituent, ActiveEdge edge)
{
//new constituent will be created
var newConstituent = edge.CompleteBy(constituent);
var endContext = newConstituent.EndContext;
if (endContext.Connect(newConstituent))
{
//constituent doesn't exists in the graph yet
_agenda.Enqueue(newConstituent);
}
if (newConstituent.IsFinal && newConstituent.EndContext.EOF && newConstituent.StartContext.BOF)
{
_result = newConstituent;
//prevent further processing
_agenda.Clear();
}
}
/// <summary>
/// Creates self edge
/// </summary>
/// <param name="label"></param>
/// <param name="extendedEdge"></param>
internal ActiveEdge(ActiveLabel label, ActiveEdge extendedEdge)
: base(extendedEdge.EndContext, extendedEdge.EndContext)
{
Label = label;
// ExtendedEdge = extendedEdge;
}
