private int GetInsertPositionLinear(IList <KeyValuePair <TKey, TObject> > list, KeyValuePair <TKey, TObject> item)
{
for (var i = 0; i < list.Count; i++)
{
if (_comparer.Compare(item, list[i]) < 0)
{
return(i);
}
}
return(_list.Count);
}
/// <summary>
/// Dynamic calculation of moved items which produce a result which can be enumerated through in order
/// </summary>
/// <returns></returns>
public IChangeSet <TObject, TKey> Calculate(IChangeSet <TObject, TKey> changes)
{
var reducedChanges = ReduceChanges(changes).ToList();
var changesByReason = reducedChanges.GroupBy(c => c.Reason).ToDictionary(x => x.Key, x => x.AsEnumerable());
var result = new List <Change <TObject, TKey> >(reducedChanges.Count);
var refreshes = changesByReason.GetOrEmpty(ChangeReason.Refresh);
var removals = changesByReason.GetOrEmpty(ChangeReason.Remove);
var updateChanges = changesByReason.GetOrEmpty(ChangeReason.Update).Concat(refreshes).OrderBy(r => new KeyValuePair <TKey, TObject>(r.Key, r.Current), _comparer);
var keysToBeRemoved = updateChanges.Concat(removals).ToDictionary(x => x.Key, x => x);
var updatePreviousValues = new Dictionary <KeyValuePair <TKey, TObject>, IndexAndNode <KeyValuePair <TKey, TObject> > >();
if (keysToBeRemoved.Any())
{
var index = 0;
var node = _list.First;
while (node != null)
{
if (keysToBeRemoved.ContainsKey(node.Value.Key))
{
var toBeRemoved = keysToBeRemoved[node.Value.Key];
var nodeCopy = node;
if (toBeRemoved.Reason == ChangeReason.Remove)
{
result.Add(new Change <TObject, TKey>(ChangeReason.Remove, toBeRemoved.Key, toBeRemoved.Current, index));
}
else
{
var kvp = new KeyValuePair <TKey, TObject>(node.Value.Key, toBeRemoved.Current);
updatePreviousValues[kvp] = IndexAndNode.Create(index, node);
index++;
}
node = node.Next;
_list.Remove(nodeCopy);
keysToBeRemoved.Remove(nodeCopy.Value.Key);
if (!keysToBeRemoved.Any())
{
break;
}
}
else
{
node = node.Next;
index++;
}
}
}
var updates = new Queue <Change <TObject, TKey> >(updateChanges);
if (updates.Any())
{
var index = -1;
var node = _list.First;
var alreadyAddedNodes = new SortedSet <KeyValuePair <TKey, TObject> >(_comparer);
var nodeToBeUpdated = updates.Peek();
var kvp = new KeyValuePair <TKey, TObject>(nodeToBeUpdated.Key, nodeToBeUpdated.Current);
while (node != null)
{
index++;
var shouldInsertElement = _comparer.Compare(node.Value, kvp) >= 0;
if (shouldInsertElement)
{
var previous = updatePreviousValues[kvp];
// Previous node index is shifter by count of already added nodes
// which are less than the one we are about to insert
var indexOffset = alreadyAddedNodes.TakeWhile(kv => _comparer.Compare(kvp, node.Value) < 0).Count();
var previousIndex = previous.Index + indexOffset;
var previousValue = previous.Node.Value;
var nodeToAdd = new LinkedListNode <KeyValuePair <TKey, TObject> >(kvp);
_list.AddBefore(node, nodeToAdd);
if (previousIndex == index)
{
result.Add(new Change <TObject, TKey>(nodeToBeUpdated.Reason, kvp.Key, kvp.Value, previousValue.Value, index, previousIndex));
}
else
{
alreadyAddedNodes.Add(kvp);
result.Add(new Change <TObject, TKey>(kvp.Key, kvp.Value, index, previousIndex));
result.Add(new Change <TObject, TKey>(nodeToBeUpdated.Reason, kvp.Key, kvp.Value, previousValue.Value, index, index));
}
node = nodeToAdd;
updates.Dequeue();
if (!updates.Any())
{
break;
}
nodeToBeUpdated = updates.Peek();
kvp = new KeyValuePair <TKey, TObject>(nodeToBeUpdated.Key, nodeToBeUpdated.Current);
}
node = node.Next;
}
if (updates.Any())
{
var previous = updatePreviousValues[kvp];
var previousIndex = previous.Index;
var previousValue = previous.Node.Value;
if (index == -1)
{
result.Add(new Change <TObject, TKey>(nodeToBeUpdated.Reason, kvp.Key, kvp.Value, previousValue.Value, 0, 0));
}
else
{
result.Add(new Change <TObject, TKey>(kvp.Key, kvp.Value, index, previousIndex));
result.Add(new Change <TObject, TKey>(nodeToBeUpdated.Reason, kvp.Key, kvp.Value, previousValue.Value, index, index));
}
_list.AddLast(kvp);
}
}
var adds = new Queue <Change <TObject, TKey> >(changesByReason.GetOrEmpty(ChangeReason.Add).OrderBy(r => r.CurrentIndex));
if (adds.Any())
{
var index = -1;
var node = _list.First;
var nodeToBeAdded = adds.Peek();
var kvp = new KeyValuePair <TKey, TObject>(nodeToBeAdded.Key, nodeToBeAdded.Current);
while (node != null)
{
index++;
var shouldInsert = _comparer.Compare(node.Value, kvp) > 0;
if (shouldInsert)
{
var nodeToAdd = new LinkedListNode <KeyValuePair <TKey, TObject> >(kvp);
_list.AddBefore(node, nodeToAdd);
result.Add(new Change <TObject, TKey>(ChangeReason.Add, nodeToBeAdded.Key, nodeToBeAdded.Current, index));
node = nodeToAdd;
adds.Dequeue();
if (!adds.Any())
{
break;
}
nodeToBeAdded = adds.Peek();
kvp = new KeyValuePair <TKey, TObject>(nodeToBeAdded.Key, nodeToBeAdded.Current);
}
node = node.Next;
}
if (adds.Any())
{
_list.AddLast(kvp);
result.Add(new Change <TObject, TKey>(ChangeReason.Add, nodeToBeAdded.Key, nodeToBeAdded.Current, index));
}
}
return(new ChangeSet <TObject, TKey>(result));
}