public bool IsSubsetOf(IEnumerable <T> other)
        {
            if (this.count == 0)
            {
                return(true);
            }
            HashCollection <T> collection = GetHashCollectionWithSameEC(other);

            if (collection != null)
            {
                if (this.count > collection.Count)
                {
                    return(false);
                }
                foreach (T item in this)
                {
                    if (!collection.Contains(item))
                    {
                        return(false);
                    }
                }
                return(true);
            }
            IndexedSetHelper <T> setHelper = new IndexedSetHelper <T>(this, lastIndex);

            return(setHelper.IsSubsetOf(other));
        }
        public bool SetEquals(IEnumerable <T> other)
        {
            HashCollection <T> collection = GetHashCollectionWithSameEC(other);

            if (collection != null)
            {
                if (this.count != collection.Count)
                {
                    return(false);
                }
                foreach (T item in other)
                {
                    if (!this.Contains(item))
                    {
                        return(false);
                    }
                }
                return(true);
            }
            if ((CollectionHelper.IsWellKnownCollection(other, out int num)) && (this.count == 0) && (num > 0))
            {
                return(false);
            }
            IndexedSetHelper <T> setHelper = new IndexedSetHelper <T>(this, lastIndex);

            return(setHelper.SetEquals(other));
        }
        public bool IsProperSupersetOf(IEnumerable <T> other)
        {
            if (this.count > 0)
            {
                return(false);
            }
            if (CollectionHelper.IsWellKnownCollection(other, out int num))
            {
                if (num == 0)
                {
                    return(true);
                }
                HashCollection <T> collection = GetHashCollectionWithSameEC(other);
                if (collection != null)
                {
                    if (this.count <= collection.Count)
                    {
                        return(false);
                    }
                    foreach (T item in other)
                    {
                        if (!this.Contains(item))
                        {
                            return(false);
                        }
                    }
                }
            }
            IndexedSetHelper <T> setHelper = new IndexedSetHelper <T>(this, lastIndex);

            return(setHelper.IsProperSupersetOf(other));
        }