public static bool TryResolveConflicts <TItem>(this GraphNode <TItem> root)
{
// now we walk the tree as often as it takes to determine
// which paths are accepted or rejected, based on conflicts occuring
// between cousin packages
var patience = 1000;
var incomplete = true;
while (incomplete && --patience != 0)
{
// Create a picture of what has not been rejected yet
var tracker = new Tracker <TItem>();
root.ForEach(true, (node, state) =>
{
if (!state || node.Disposition == Disposition.Rejected)
{
// Mark all nodes as rejected if they aren't already marked
node.Disposition = Disposition.Rejected;
return(false);
}
tracker.Track(node.Item);
return(true);
});
// Inform tracker of ambiguity beneath nodes that are not resolved yet
// between:
// a1->b1->d1->x1
// a1->c1->d2->z1
// first attempt
// d1/d2 are considered disputed
// x1 and z1 are considered ambiguous
// d1 is rejected
// second attempt
// d1 is rejected, d2 is accepted
// x1 is no longer seen, and z1 is not ambiguous
// z1 is accepted
root.ForEach("Walking", (node, state) =>
{
if (node.Disposition == Disposition.Rejected)
{
return("Rejected");
}
if (state == "Walking" && tracker.IsDisputed(node.Item))
{
return("Ambiguous");
}
if (state == "Ambiguous")
{
tracker.MarkAmbiguous(node.Item);
}
return(state);
});
// Now mark unambiguous nodes as accepted or rejected
root.ForEach(true, (node, state) =>
{
if (!state || node.Disposition == Disposition.Rejected)
{
return(false);
}
if (tracker.IsAmbiguous(node.Item))
{
return(false);
}
if (node.Disposition == Disposition.Acceptable)
{
node.Disposition = tracker.IsBestVersion(node.Item) ? Disposition.Accepted : Disposition.Rejected;
}
return(node.Disposition == Disposition.Accepted);
});
incomplete = false;
root.ForEach(node => incomplete |= node.Disposition == Disposition.Acceptable);
}
return(!incomplete);
}