private static List <DetectionGroup> DetectGroups(List <int> data)
{
// Find groups of ascending indices
var groups = new List <DetectionGroup> ();
DetectionGroup currentGroup = null;
foreach (var val in data)
{
if (currentGroup != null)
{
if (val > currentGroup.Last)
{
currentGroup.Last = val;
currentGroup.Size += 1;
}
else
{
currentGroup = null;
}
}
if (currentGroup == null)
{
if (val >= 0)
{
currentGroup = new DetectionGroup()
{
First = val,
Last = val,
Size = 1,
};
groups.Add(currentGroup);
}
}
}
return(groups);
}
public static IEnumerable <ResolveResult> Resolve <T> (List <T> oldList, List <T> newList, Func <T, T, bool> comparer)
{
// Make an array of old indexes that correspond to the new array items
var idxMap = newList
.Select(newItem => oldList.FindIndex(oldItem => comparer(newItem, oldItem)))
.ToList();
// Find groups to keep
var groups = new Queue <DetectionGroup> (FindGroupsToKeep(DetectGroups(idxMap)));
// Determine items to delete
for (var oldIdx = 0; oldIdx < oldList.Count; oldIdx++)
{
var oldItem = oldList [oldIdx];
if (!newList.Any(newItem => comparer(newItem, oldItem)))
{
yield return(new ResolveResult()
{
OldIndex = oldIdx,
NewIndex = -1,
Action = ResolvedAction.Delete,
});
}
}
// Determine items to insert or keep:
DetectionGroup currentGroup = null;
for (var newIdx = 0; newIdx < idxMap.Count; newIdx++)
{
var oldIdx = idxMap [newIdx];
// Reached end of a group:
if (oldIdx == -1 || (currentGroup != null && currentGroup.Last < oldIdx))
{
currentGroup = null;
}
// See if we can use next group item:
if (currentGroup == null)
{
var nextGroup = groups.Count > 0 ? groups.Peek() : null;
if (nextGroup != null && nextGroup.First == oldIdx)
{
currentGroup = groups.Dequeue();
}
}
if (currentGroup == null)
{
yield return(new ResolveResult()
{
OldIndex = -1,
NewIndex = newIdx,
Action = ResolvedAction.Insert,
});
}
else
{
yield return(new ResolveResult()
{
OldIndex = oldIdx,
NewIndex = newIdx,
Action = ResolvedAction.Keep,
});
}
}
}
