package sets.multysets;

import java.util.Iterator;

public interface MultySet<E> {
	/**
	 * Returns true of multyset is empty
	 */
	public boolean isEmpty() ;

	/**
	 * Returns the number of all instances of all elements of the multyset
	 */
	public int size() ;
	
	/**
	 * Removes all elements of multyset
	 */
	public void clear() ;
	
	/**
	 * Returns an Iterator object to iterate over multyset
	 */
	public Iterator<E> iterator();
	
	/**
	 * Returns a copy of the multyset
	 */
	public MultySet<E> clone() ;
	
	/**
	 * Adds an element with a given number of instances to the multyset
	 */
	public void add(E e, int card);
	
	/**
	 * Removes all instances of an element of the multyset
	 * Returns number of instances of removed element, null if element not in multyset
	 */
	public Integer removeElement(E e) ;
	
	/**
	 * Removes an instance of an element of the multyset
	 * Returns true if multyset is changed
	 */
	public boolean removeInstance(E e);
	
	/**
	 * Returns number of instances of an element of the multyset, zero if not present
	 */
	public int contains(E e);

	/**
	 * Overrides method equals of class Object
	 */
	public boolean equals(Object other) ;
	
	/**
	 * Overrides method toString of class Object
	 */
	public String toString() ;
	
	/**
	 * Returns true if this multyset is a subset of other multyset
	 */
	public boolean SubSetOf(MultySet<E> other);
	
	/**
	 * Returns the union of this multyset and the other multyset
	 */
	public MultySet<E> union(MultySet<E> other) ;

	/**
	 * Returns the intersection of this multyset and the other multyset
	 */
	public MultySet<E> intersection(MultySet<E> other) ;
	
	
	/**
	 * Returns the difference of this multyset and the other multyset
	 */
	public MultySet<E> difference(MultySet<E> other);
	
	public E[] toArray();

}