// Return true if any locations contain objects moving any of these ways
// if found add this location to every trail (usually just the root)
internal bool OpFindOM(HashSet <int> objectids, Direction direction, MatchOperator oper)
{
var matches = _levelstate.FindMatches(objectids, direction, oper).ToList();
if (matches.Count == 0)
{
_vm_trail = new Trail(); // Hmmm. Maybe clear all is better?
}
//_trail.Clear();
else
{
// combinatorially add match to all trails
foreach (var trail in _vm_trail.GetLeaves())
{
foreach (var match in matches)
{
_vm_trail.Add(trail, match);
}
}
}
return(_vm_trail.IsEmpty);
}