private TResult handleMutate <TResult>(
MultiDictionary <CompositionHost, object> exportsList,
Func <List <object>, TResult> mutate,
CompositionHost addUnder)
{
IEqualityComparer <object> referenceEqualityComparer
= EquatableHelper.ReferenceEqualityComparer <object>();
MultiDictionary <CompositionHost, object> currentCopy = exports.CopyCollection(exportsList);
List <object> currentValuesCopy = exportsList.GetAllValues();
List <object> currentValues = exportsList.GetAllValues();
TResult result = mutate(currentValues);
// Removed?
foreach (object currentValueCopy in currentValuesCopy)
{
if (currentValues.Contains(currentValueCopy, referenceEqualityComparer))
{
continue;
}
KeyValuePair <CompositionHost, object> entry
= currentCopy.FirstOrDefault(kv => object.ReferenceEquals(currentValueCopy, kv.Value));
exportsList.Remove(entry);
if (!exportsList.ContainsKey(entry.Key) &&
!object.ReferenceEquals(MefSingletonComposer.unmanagedCompositionHost, entry.Key))
{
entry.Key.Dispose();
}
}
// Added?
foreach (object currentValue in currentValues)
{
if (currentValuesCopy.Contains(currentValue, referenceEqualityComparer))
{
continue;
}
exportsList.AddValue(addUnder, currentValue);
}
return(result);
}