public static CollectionComparisonResult <T> CompareTo <T>([CanBeNull] this IEnumerable <T> source,
[CanBeNull] IEnumerable <T> destination,
[NotNull] Func <T, T, bool> comparer)
{
comparer.RequiredNotNull("comparer");
var result = new CollectionComparisonResult <T>();
if (source == null && destination == null)
{
return(result);
}
if (source != null && destination == null)
{
result.OnlyInSource.AddRange(source);
return(result);
}
if (source == null)
{
result.OnlyInDestination.AddRange(destination);
return(result);
}
var source_list = source.ConvertToList();
Debug.Assert(source_list != null, "source_list != null");
var destination_list = destination.ConvertToList();
Debug.Assert(destination_list != null, "destination_list != null");
foreach (var s in source_list)
{
if (destination_list.Any(d => comparer(s, d)))
{
result.SourceInBoth.Add(s);
}
else
{
result.OnlyInSource.Add(s);
}
}
foreach (var d in destination_list)
{
if (source_list.Any(s => comparer(s, d)))
{
result.DestinationInBoth.Add(d);
}
else
{
result.OnlyInDestination.Add(d);
}
}
return(result);
}
public static CollectionComparisonResult <TItem> CompareTo <TItem, TKey>([CanBeNull] this IEnumerable <TItem> source,
[CanBeNull] IEnumerable <TItem> destination,
[NotNull] Func <TItem, TKey> key)
{
key.RequiredNotNull("key");
var result = new CollectionComparisonResult <TItem>();
if (source == null && destination == null)
{
return(result);
}
if (source != null && destination == null)
{
result.OnlyInSource.AddRange(source);
return(result);
}
if (source == null)
{
result.OnlyInDestination.AddRange(destination);
return(result);
}
var source_list = source.ConvertToList();
Debug.Assert(source_list != null, "source_list != null");
var destination_list = destination.ConvertToList();
Debug.Assert(destination_list != null, "destination_list != null");
var source_keys = new HashSet <TKey>(source_list.Select(key));
var destination_keys = new HashSet <TKey>(destination_list.Select(key));
foreach (var s in source_list)
{
if (destination_keys.Contains(key(s)))
{
result.SourceInBoth.Add(s);
}
else
{
result.OnlyInSource.Add(s);
}
}
foreach (var d in destination_list)
{
if (source_keys.Contains(key(d)))
{
result.DestinationInBoth.Add(d);
}
else
{
result.OnlyInDestination.Add(d);
}
}
return(result);
}