public static IEnumerable <DependencyCycle <T> > VisitCycles <T>(this IEnumerable <DependencyCycle <T> > cycles,
VisitCycleHandler <T> visit)
{
var mc = new Dictionary <DependencyCycle <T>, DependencyCycle <T> >();
var setComparer = HashSetEqualityComparer <DependencyCycle <T> > .Default;
return(VisitCyclesCore(cycles, () => { }, mc, visit, setComparer));
}
private static IEnumerable <DependencyCycle <T> > VisitCyclesCore <T>(IEnumerable <DependencyCycle <T> > cycles,
Action cancelled,
IDictionary <DependencyCycle <T>, DependencyCycle <T> > cache,
VisitCycleHandler <T> visit,
IEqualityComparer <HashSet <DependencyCycle <T> > > setComparer)
{
foreach (var cycle in cycles)
{
if (cache.TryGetValue(cycle, out var newCycle))
{
yield return(cycle);
continue;
}
var dependenciesChanged = false;
var dependencies = cycle.Dependencies as HashSet <DependencyCycle <T> > ?? cycle.Dependencies.ToHashSet();
if (dependencies.Count > 0)
{
var wasCancelled = false;
var dependenciesSet = VisitCyclesCore(dependencies, () => wasCancelled = true, cache, visit, setComparer)
.ToHashSet();
if (wasCancelled)
{
cancelled();
yield break;
}
if (!setComparer.Equals(dependenciesSet, dependencies))
{
dependenciesChanged = true;
dependencies = dependenciesSet;
}
}
newCycle = visit(cycle, dependenciesChanged, dependencies);
if (newCycle == null)
{
cancelled();
yield break;
}
if (newCycle == cycle && dependenciesChanged)
{
newCycle = new DependencyCycle <T>(cycle.Contents, dependencies);
}
cache.Add(cycle, newCycle);
yield return(newCycle);
}
}