/// <summary>
/// Determines if contents of both lists are equal ignoring their order.
/// <locDE><para />Ermittelt ob die beiden Listen den gleichen Inhalt haben (ohne Rücksicht auf die Reihenfolge).</locDE>
/// </summary>
/// <typeparam name="T">The element type of the lists.<locDE><para />Elementtyp der Listen.</locDE></typeparam>
/// <param name="list1">The first list.<locDE><para />Erste Liste.</locDE></param>
/// <param name="list2">The second list.<locDE><para />Zweite Liste.</locDE></param>
/// <param name="diff">The found difference between the collections (if any).<locDE><para />Gefundene Unterschiede (falls nicht gleich).</locDE></param>
/// <returns>True if equal.<locDE><para />True falls identisch.</locDE></returns>
public static bool EqualContentsIgnoreOrder <T>(this System.Collections.Generic.IEnumerable <T> list1, System.Collections.Generic.IEnumerable <T> list2,
out System.Collections.Generic.ICollection <T> diff)
{
var listType = typeof(System.Collections.Generic.List <>);
var constructedListType = listType.MakeGenericType(typeof(T));
diff = Activator.CreateInstance(constructedListType) as System.Collections.Generic.ICollection <T>;
#region Handle list(s) being null
if (null == list1 && null == list2)
{
return(true);
}
if (null == list1 && null != list2)
{
foreach (T s in list2)
{
diff.Add(s);
}
return(false);
}
if (null != list1 && null == list2)
{
foreach (T s in list1)
{
diff.Add(s);
}
return(false);
}
#endregion Handle list(s) being null
// https://stackoverflow.com/questions/3669970/compare-two-listt-objects-for-equality-ignoring-order
var cnt = new System.Collections.Generic.Dictionary <T, int>();
foreach (T s in list1)
{
if (cnt.ContainsKey(s))
{
cnt[s]++;
}
else
{
cnt.Add(s, 1);
}
}
foreach (T s in list2)
{
if (cnt.ContainsKey(s))
{
cnt[s]--;
}
else
{
diff.Add(s);
}
}
//diff.Union(cnt.Where(x => x.Value != 0).Select(x => x.Key));
System.Collections.Generic.IEnumerable <T> cntsNotZero = cnt.Where(x => x.Value != 0).Select(x => x.Key);
if (null != cntsNotZero)
{
foreach (T cntNoZero in cntsNotZero)
{
diff.AddIfNotContains(cntNoZero);
}
}
return(0 == diff.Count());
}