internal static void Exit(bool revertAll = false)
{
var trail = current;
if (revertAll)
{
while (trail.Depth > 0)
{
trail.Backtrack();
}
}
else if (trail.parent is Trail parent)
{
foreach (var frame in trail.frames.Reverse())
{
parent.frames.Push(frame);
}
}
current = trail.parent;
}
public static IEnumerable AsEnumerable(this Query query, bool revertAll = false)
{
try
{
Trail.Enter();
Query nextQuery = query;
while (nextQuery != null)
{
var currentQuery = nextQuery;
var result = currentQuery.Run();
switch (result)
{
case QueryResult.ChoicePoint:
nextQuery = currentQuery.Continuation;
Trail.Current.ChoicePoint(currentQuery.Alternate);
break;
case QueryResult.Success:
yield return(null);
nextQuery = Trail.Current.Backtrack();
break;
default:
nextQuery = Trail.Current.Backtrack();
break;
}
}
}
finally
{
Trail.Exit(revertAll);
}
}
public Trail(Trail parent)
{
this.parent = parent;
this.frames = new Stack <ChoiceFrame>();
}
internal static void Enter()
{
current = new Trail(Current);
current.ChoicePoint(null);
}
public Trail(Trail parent)
{
this.parent = parent;
}
