// static Type isortedtype = typeof(ISorted<T>);
/// <summary>
/// Examine if collection1 and collection2 are equal as unsequenced collections
/// using the specified item equalityComparer (assumed compatible with the two collections).
/// </summary>
/// <param name="collection1">The first collection</param>
/// <param name="collection2">The second collection</param>
/// <param name="itemequalityComparer">The item equalityComparer to use for comparison</param>
/// <returns>True if equal</returns>
public static bool StaticEquals(ICollection <T> collection1, ICollection <T> collection2, System.Collections.Generic.IEqualityComparer <T> itemequalityComparer)
{
if (object.ReferenceEquals(collection1, collection2))
{
return(true);
}
// bug20070227:
if (collection1 == null || collection2 == null)
{
return(false);
}
if (collection1.Count != collection2.Count)
{
return(false);
}
//This way we might run through both enumerations twice, but
//probably not (if the hash codes are good)
//TODO: check equal equalityComparers, at least here!
if (collection1.GetUnsequencedHashCode() != collection2.GetUnsequencedHashCode())
{
return(false);
}
//TODO: move this to the sorted implementation classes?
//Really depends on speed of InstanceOfType: we could save a cast
{
if (collection1 is ISorted <T> stit && collection2 is ISorted <T> stat && stit.Comparer == stat.Comparer)
{
using System.Collections.Generic.IEnumerator <T> dat = collection2.GetEnumerator(), dit = collection1.GetEnumerator();
while (dit.MoveNext())
{
dat.MoveNext();
if (!itemequalityComparer.Equals(dit.Current, dat.Current))
{
return(false);
}
}
return(true);
}
}
if (!collection1.AllowsDuplicates && (collection2.AllowsDuplicates || collection2.ContainsSpeed >= collection1.ContainsSpeed))
{
foreach (T x in collection1)
{
if (!collection2.Contains(x))
{
return(false);
}
}
}
else if (!collection2.AllowsDuplicates)
{
foreach (T x in collection2)
{
if (!collection1.Contains(x))
{
return(false);
}
}
}
// Now tit.AllowsDuplicates && tat.AllowsDuplicates
else if (collection1.DuplicatesByCounting && collection2.DuplicatesByCounting)
{
foreach (T item in collection2)
{
if (collection1.ContainsCount(item) != collection2.ContainsCount(item))
{
return(false);
}
}
}
else
{
// To avoid an O(n^2) algorithm, we make an aux hashtable to hold the count of items
// bug20101103: HashDictionary<T, int> dict = new HashDictionary<T, int>();
HashDictionary <T, int> dict = new HashDictionary <T, int>(itemequalityComparer);
foreach (T item in collection2)
{
int count = 1;
if (dict.FindOrAdd(item, ref count))
{
dict[item] = count + 1;
}
}
foreach (T item in collection1)
{
var i = item;
if (dict.Find(ref i, out int count) && count > 0)
{
dict[item] = count - 1;
}