internal ActiveLabel(GrammarSequence sequence, int index = 0)
{
_sequence = sequence;
_index = index;
var sequenceTerms = sequence.Terms;
CurrentTerm = sequenceTerms.Skip(index).First();
WillComplete = sequenceTerms.Count() == index + 1;
var currentTerminal = CurrentTerm as Terminal;
if (currentTerminal != null)
{
TerminalLabel = new TerminalLabel(currentTerminal, sequence);
}
if (WillComplete)
{
CompleteLabel = new CompleteLabel(_sequence);
}
else
{
NextInChain = new ActiveLabel(sequence, index + 1);
}
}
internal ActiveEdge(ActiveEdge extendedEdge, CompleteEdge extendingEdge)
: base(extendedEdge.StartContext, extendingEdge.EndContext)
{
ExtendingEdge = extendingEdge;
ExtendedEdge = extendedEdge;
Label = ExtendedEdge.Label.NextInChain;
}
private IEnumerable <ActiveLabel> getTrasintions(ActiveLabel label)
{
var transitions = new HashSet <ActiveLabel>();
fillTransitions(label, transitions);
return(transitions);
}
/// <summary>
/// Creates parser, from given grammar
/// (Accepts all CFG forms)
/// </summary>
/// <param name="grammar">Grammar specifing parsing rules</param>
public Parser(GrammarBase grammar)
{
_grammar = grammar;
grammar.Build();
var nonTerminals = grammar.CollectNonTerminals(grammar.Root);
//prepare edges
foreach (var nonTerm in nonTerminals)
{
foreach (var sequence in nonTerm.Rule.Sequences)
{
var activeLabel = new ActiveLabel(sequence);
_activeChains.Add(sequence, activeLabel);
}
}
buildEdgeTransitions();
//set root transitions
_rootTransitions = getRootTransitions().ToArray();
}
private void fillTransitions(ActiveLabel label, HashSet <ActiveLabel> transitions)
{
var transitionNonTerm = label.CurrentTerm as NonTerminal;
if (transitionNonTerm == null)
{
//transitions are processed only on non terminals
return;
}
foreach (var sequence in transitionNonTerm.Rule.Sequences)
{
var transition = _activeChains[sequence];
if (transitions.Add(transition))
{
//recursive add transitions of added edge
fillTransitions(transition, transitions);
}
}
}
/// <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;
}
internal ActiveEdge(ActiveLabel label, SourceContext startContext, SourceContext endContext)
: base(startContext, endContext)
{
Label = label;
}
