public static void ExtractWords <TStackSymbol, TTransition>(
PdaExtractingContext <GssNode <TStackSymbol, PdaExtractingGssData>, TTransition> root,
Func <PdaExtractingContext <GssNode <TStackSymbol, PdaExtractingGssData>, TTransition>, bool> isFinal,
int maxCyclesExpansion,
Func <IEnumerable <TTransition>, bool> onExtracted,
Action <IEnumerable <TTransition> > peek)
{
ExtractWordsInternal(
root,
isFinal,
ImmutableDictionary <PdaExtractingContext <GssNode <TStackSymbol, PdaExtractingGssData>, TTransition>, int> .Empty,
ImmutableStack <TStackSymbol> .Empty,
ImmutableQueue <TTransition> .Empty,
onExtracted,
maxCyclesExpansion,
peek);
}
private static bool ExtractWordsInternal <TStackSymbol, TTransition>(
PdaExtractingContext <GssNode <TStackSymbol, PdaExtractingGssData>, TTransition> root,
Func <PdaExtractingContext <GssNode <TStackSymbol, PdaExtractingGssData>, TTransition>, bool> isFinal,
ImmutableDictionary <PdaExtractingContext <GssNode <TStackSymbol, PdaExtractingGssData>, TTransition>, int> visited,
ImmutableStack <TStackSymbol> stack,
ImmutableQueue <TTransition> accumulator,
Func <IEnumerable <TTransition>, bool> onExtracted,
int maxCyclesExpansion,
Action <IEnumerable <TTransition> > peek)
{
if (visited.ContainsKey(root) && visited[root] >= maxCyclesExpansion + 1)
{
return(true);
}
if (isFinal(root))
{
if (stack.IsEmpty && !root.StackTop.Pop().Any() ||
root.StackTop.Symbol.Equals(stack.Peek()))
{
var shouldContinue = onExtracted(accumulator);
if (!shouldContinue)
{
return(false);
}
}
}
if (visited.ContainsKey(root))
{
var count = visited[root] + 1;
visited = visited.SetItem(root, count);
}
else
{
visited = visited.SetItem(root, 1);
}
peek(accumulator);
foreach (var transition in root.Transitions)
{
var shouldContinue = true;
switch (transition.Action)
{
case PdaAction.Push:
shouldContinue =
ExtractWordsInternal(
transition.Target,
isFinal,
visited,
stack.Push(transition.Target.StackTop.Symbol),
accumulator.Enqueue(transition.Token),
onExtracted,
maxCyclesExpansion,
peek);
break;
case PdaAction.Skip:
shouldContinue =
ExtractWordsInternal(
transition.Target,
isFinal,
visited,
stack,
accumulator.Enqueue(transition.Token),
onExtracted,
maxCyclesExpansion,
peek);
break;
case PdaAction.Pop:
if (stack.IsEmpty)
{
break;
}
var gss = transition.Target.StackTop;
var popped = stack.Pop();
if (popped.IsEmpty)
{
if (gss.Pop().Any())
{
break;
}
}
else
{
if (!popped.Peek().Equals(gss.Symbol))
{
break;
}
}
shouldContinue =
ExtractWordsInternal(
transition.Target,
isFinal,
visited,
popped,
accumulator.Enqueue(transition.Token),
onExtracted,
maxCyclesExpansion,
peek);
break;
}
if (!shouldContinue)
{
return(false);
}
}
return(true);
}
