/// <summary>
/// Merge two nodes. Both of them become equiualent.
///
/// In complex situation, 'secondary' node becomes reference to 'main' node, if it is possible
/// </summary>
public static void MergeInplace(TicNode main, TicNode secondary)
{
if (main == secondary)
{
return;
}
if (main.State is StateRefTo)
{
var nonreferenceMain = main.GetNonReference();
var nonreferenceSecondary = secondary.GetNonReference();
MergeInplace(nonreferenceMain, nonreferenceSecondary);
return;
}
if (secondary.GetNonReference() == main)
{
return;
}
var res = GetMergedStateOrNull(main.State, secondary.State);
if (res == null)
{
throw TicErrors.CannotMerge(main, secondary);
}
main.State = res;
if (res is ITypeState t && t.IsSolved)
{
secondary.State = res;
return;
}
main.AddAncestors(secondary.Ancestors.Where(a => a != main));
secondary.ClearAncestors();
secondary.State = new StateRefTo(main);
}
private TicNode GetNonReferenceNodeOrNull(TicNode node)
{
if (node.VisitMark == _nodeInListMark)
{
return(node);
}
if (!(node.State is StateRefTo refTo))
{
return(node);
}
if (node.VisitMark == RefVisitingMark)
{
return(null);
}
node.VisitMark = RefVisitingMark;
var res = GetNonReferenceNodeOrNull(refTo.Node);
if (res == null)
{
_refRoute.Push(node);
}
else
{
node.VisitMark = -1;
//merge
if (node.Ancestors.Any())
{
res.AddAncestors(node.Ancestors);
node.ClearAncestors();
}
}
return(res);
}