private static NotifyBatchCollectionChangedEventArgs Combine(NotifyBatchCollectionChangedEventArgs x, NotifyBatchCollectionChangedEventArgs y)
{
if (x == null)
{
return(y);
}
if (y == null)
{
return(x);
}
var replacements = default(BiMap);
var result = default(NotifyBatchCollectionChangedEventArgs);
if (x.Action == y.Action)
{
switch (x.Action)
{
case NotifyCollectionChangedAction.Replace:
{
replacements = NotifyBatchCollectionChangedEventArgs.Merge(
NotifyBatchCollectionChangedEventArgs.Map(x.OldItems, x.NewItems),
NotifyBatchCollectionChangedEventArgs.Map(y.OldItems, y.NewItems));
if (replacements == null)
{
return(null);
}
result = new NotifyBatchCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
}
break;
case NotifyCollectionChangedAction.Add:
case NotifyCollectionChangedAction.Remove:
case NotifyCollectionChangedAction.Move:
result = new NotifyBatchCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
break;
case NotifyCollectionChangedAction.Reset:
result = new NotifyBatchCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
replacements = NotifyBatchCollectionChangedEventArgs.Merge(x.m_fromTo, y.m_fromTo);
break;
default:
throw new NotSupportedException();
}
}
else
{
if (x.Action == NotifyCollectionChangedAction.Replace)
{
replacements = NotifyBatchCollectionChangedEventArgs.Merge(NotifyBatchCollectionChangedEventArgs.Map(x.OldItems, x.NewItems), null);
}
else if ((x.Action == NotifyCollectionChangedAction.Reset) && (x.m_fromTo != null))
{
replacements = new BiMap(x.m_fromTo, x.m_toFrom);
}
switch (y.Action)
{
case NotifyCollectionChangedAction.Add:
{
if (replacements != null)
{
var fromTo = replacements.FromTo;
var toFrom = replacements.ToFrom;
foreach (var item in y.NewItems)
{
object to;
if (fromTo.TryGetValue(item, out to))
{
fromTo.Remove(item);
toFrom.Remove(to);
}
}
}
}
break;
case NotifyCollectionChangedAction.Remove:
{
if (replacements != null)
{
var fromTo = replacements.FromTo;
var toFrom = replacements.ToFrom;
foreach (var item in y.OldItems)
{
object from;
if (toFrom.TryGetValue(item, out from))
{
fromTo.Remove(from);
toFrom.Remove(item);
}
}
}
}
break;
case NotifyCollectionChangedAction.Replace:
{
var mapping = NotifyBatchCollectionChangedEventArgs.Map(y.OldItems, y.NewItems);
if (replacements != null)
{
replacements = NotifyBatchCollectionChangedEventArgs.Merge(replacements.FromTo, mapping);
}
else
{
replacements = NotifyBatchCollectionChangedEventArgs.Merge(mapping, null);
}
}
break;
case NotifyCollectionChangedAction.Move:
break;
case NotifyCollectionChangedAction.Reset:
{
if (replacements != null)
{
replacements = NotifyBatchCollectionChangedEventArgs.Merge(replacements.FromTo, y.m_fromTo);
}
else
{
replacements = NotifyBatchCollectionChangedEventArgs.Merge(y.m_fromTo, null);
}
}
break;
default:
throw new NotSupportedException();
}
result = new NotifyBatchCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
}
if ((result != null) && (replacements != null))
{
result.m_fromTo = replacements.FromTo;
result.m_toFrom = replacements.ToFrom;
}
return(result);
}
internal static NotifyBatchCollectionChangedEventArgs Combine(NotifyCollectionChangedEventArgs x, NotifyCollectionChangedEventArgs y)
{
return(NotifyBatchCollectionChangedEventArgs.Combine(
NotifyBatchCollectionChangedEventArgs.Create(x),
NotifyBatchCollectionChangedEventArgs.Create(y)));
}