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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2006, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection;
/** This class defines the interface of collections that do not contain
* duplicate elements. Class <code>Set</code> may only be used for
* accessing elements from set implementations. Two different extensions
* of class <code>Set</code> in the package <code>scala.collections.mutable</code>
* and <code>scala.collections.immutable</code> provide functionality for
* adding new elements to a set. The class in the first package is implemented
* by sets the are modified destructively, whereas the class in the second
* package is used by functional set implementations that rely on immutable
* data structures.
*
* @author Matthias Zenger
* @version 1.0, 08/07/2003
*/
mixin class Set[A] extends AnyRef with Function1[A, Boolean] with Iterable[A] {
/** Returns the number of elements in this set.
*
* @return number of set elements.
*/
def size: Int;
/** Checks if this set contains element <code>elem</code>.
*
* @param elem the element to check for membership.
* @return true, iff <code>elem</code> is contained in this set.
*/
def contains(elem: A): Boolean;
/** This method allows sets to be interpreted as predicates.
* It returns true, iff this set contains element <code>elem</code>.
*
* @param elem the element to check for membership.
* @return true, iff <code>elem</code> is contained in this set.
*/
def apply(elem: A): Boolean = contains(elem);
/** Checks if this set is empty.
*
* @return true, iff there is no element in the set.
*/
def isEmpty: Boolean = (size == 0);
/** Checks if this set is a subset of set <code>that</code>.
*
* @param that another set.
* @return true, iff the other set is a superset of this set.
*/
def subsetOf(that: Set[A]): Boolean = forall(that.contains);
/** Compares this set with another object and returns true, iff the
* other object is also a set which contains the same elements as
* this set.
*
* @param that the other object
* @return true, iff this set and the other set contain the same
* elements.
*/
override def equals(that: Any): Boolean = that match {
case other: Set[A] =>
this.size == other.size && this.elements.forall(other.contains)
case _ =>
false
}
/** Returns the elements of this set as a list.
*
* @return a list containing all set elements.
*/
def toList: List[A] = elements.toList;
/** Returns a string representation of this set.
*
* @return a string showing all elements of this set.
*/
override def toString(): String =
if (isEmpty) "{}" else toList.mkString("{", ", ", "}");
}
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