public T this[int index]
{
get
{
var item = items[index];
if (!item.HasValue)
{
items[index] = item = item.WithValue(GetValue(item.Node));
}
return(item.Value);
}
set
{
var item = items[index];
cursor.MoveTo(item.Node);
SetValue(cursor, item.Value, ref value);
if (advisor.OnReplacing(item.Value, value))
{
// Commit the replacement
items[index] = item.WithValue(value);
advisor.OnReplaced(item.Value, value, index);
}
else
{
// Rollback the replacement
var oldValue = item.Value;
SetValue(cursor, value, ref oldValue);
items[index] = item.WithValue(oldValue);
}
}
}
private void SetValueAt(int index, T value)
{
var item = items[index];
cursor.MoveTo(item.Node);
SetValue(cursor, item.Value, ref value);
if (ShouldReplace(item.Value, value))
{
items[index] = item.WithValue(value);
DetachPropertyChanged(item.Value);
AttachPropertyChanged(value);
NotifyListChanged(ListChangedType.ItemChanged, index);
}
else
{
var oldValue = item.Value;
SetValue(cursor, value, ref oldValue);
items[index] = item.WithValue(oldValue);
}
}