/// <summary>
/// Determines if this bag is a proper subset of another bag. Neither bag is modified.
/// This bag is a subset of <paramref name="otherBag"/> if every element in this bag
/// is also in <paramref name="otherBag"/>, at least the same number of
/// times. Additional, this bag must have strictly fewer items than <paramref name="otherBag"/>.
/// </summary>
/// <remarks>IsProperSubsetOf is computed in time O(N), where N is the number of unique items in this bag.</remarks>
/// <param name="otherBag">Bag to compare to.</param>
/// <returns>True if this is a proper subset of <paramref name="otherBag"/>.</returns>
/// <exception cref="InvalidOperationException">This bag and <paramref name="otherBag"/> don't use the same method for comparing items.</exception>
public bool IsProperSubsetOf(Bag <T> otherBag)
{
return(otherBag.IsProperSupersetOf(this));
}
/// <summary>
/// Makes a shallow clone of this bag; i.e., if items of the
/// bag are reference types, then they are not cloned. If T is a value type,
/// then each element is copied as if by simple assignment.
/// </summary>
/// <remarks>Cloning the bag takes time O(N), where N is the number of unquie items in the bag.</remarks>
/// <returns>The cloned bag.</returns>
public Bag <T> Clone()
{
Bag <T> newBag = new Bag <T>(equalityComparer, keyEqualityComparer, hash.Clone(null), count);
return(newBag);
}