public class DelegateEqualityComparer<T> : IEqualityComparer<T>
{
    private readonly Func<T, T, bool> _equals;
    private readonly Func<T, int> _hashCode;
    public DelegateEqualityComparer(Func<T, T, bool> equals, Func<T, int> hashCode)
    {
        _equals = equals;
        _hashCode = hashCode;
    }

    public bool Equals(T x, T y)
    {
        return _equals(x, y);
    }

    public int GetHashCode(T obj)
    {
        if (_hashCode != null)
            return _hashCode(obj);
        return obj.GetHashCode();
    }
}