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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id: Set.scala 16893 2009-01-13 13:09:22Z cunei $
package scalax.collection.generic
/** <p>
* A set is a collection that includes at most one of any object.
* </p>
* <p>
* This trait provides a limited interface, only allowing reading of elements.
* There are two extensions of this trait, in packages
* <code><a href="mutable$content.html" target="contentFrame">
* scala.collection.mutable</a></code>
* and <code><a href="immutable$content.html" target="contentFrame">
* scala.collection.immutable</a></code>, which provide functionality for
* adding and removing objects from the set. The trait in the first package is
* for sets that are modified destructively, whereas the trait in
* the second package is for immutable sets which create a new set
* when something is added or removed to them.
*
* @author Matthias Zenger
* @author Martin Odersky
* @version 2.8
*/
trait SetTemplate[+CC[B] <: SetTemplate[CC, B] with Set[B], A] extends (A => Boolean) with SizedIterable[A] with OrderedIterableTemplate[CC, A] {
/** Returns the number of elements in this set.
*
* @return number of set elements.
*/
def size: Int
/** Creates a new set of this kind with given elements */
def newBuilder[B]: Builder[CC, B]
/** Checks if this set contains element <code>elem</code>.
*
* @param elem the element to check for membership.
* @return <code>true</code> iff <code>elem</code> is contained in
* this set.
*/
def contains(elem: A): Boolean
/** Create a new set with an additional element.
*/
def +(elem: A): CC[A]
/** Remove a single element from a set.
* @param elem the element to be removed
* @return a new set with the element removed.
*/
def -(elem: A): CC[A]
/** Checks if this set is empty.
*
* @return <code>true</code> iff there is no element in the set.
*/
override def isEmpty: Boolean = size == 0
/** This method allows sets to be interpreted as predicates.
* It returns <code>true</code>, iff this set contains element
* <code>elem</code>.
*
* @param elem the element to check for membership.
* @return <code>true</code> iff <code>elem</code> is contained in
* this set.
*/
def apply(elem: A): Boolean = contains(elem)
/** Add two or more elements to this set.
* @param elem1 the first element.
* @param elem2 the second element.
* @param elems the remaining elements.
* @return a new set with the elements added.
*/
def + (elem1: A, elem2: A, elems: A*): CC[A] = {
thisCC + elem1 + elem2 ++ elems.asInstanceOf[Iterable[A]]
}
/** Remove two or more elements from this set.
*
* @param elem1 the first element.
* @param elem2 the second element.
* @param elems the remaining elements.
* @return a new set with the elements removed.
*/
def - (elem1: A, elem2: A, elems: A*): CC[A] =
this - elem1 - elem2 -- elems.asInstanceOf[Iterable[A]]
/** Remove all the elements provided by an iterator
* of the iterable object <code>elems</code> from the set.
*
* @param elems An iterable object containing the elements to remove from the set.
* @return a new set with the elements removed.
*/
def -- (elems: Iterable[A]): CC[A] = this -- elems.elements
/** Remove all the elements provided by an iterator
* <code>elems</code> from the set.
*
* @param elems An iterator containing the elements to remove from the set.
* @return a new set with the elements removed.
*/
def -- (elems: Iterator[A]): CC[A] =
(thisCC /: elems) (_ - _)
/** This method computes an intersection with set <code>that</code>.
* It removes all the elements that are not present in <code>that</code>.
*
* @param that the set to intersect with.
*/
def intersect(that: Set[A]): CC[A] = filter(that.contains)
/** This method is an alias for <code>intersect</code>.
* It computes an intersection with set <code>that</code>.
* It removes all the elements that are not present in <code>that</code>.
*
* @param that the set to intersect with
*/
def ** (that: collection.Set[A]): CC[A] = intersect(that)
/** Checks if this set is a subset of set <code>that</code>.
*
* @param that another set.
* @return <code>true</code> iff the other set is a superset of
* this set.
* todo: rename to isSubsetOf
*/
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
* @note not necessarily run-time type safe.
* @return <code>true</code> iff this set and the other set
* contain the same elements.
* @deprecated equals is not stable for mutable sets.
* If you wish object identity, use eq or cast this set of AnyRef and then use
* equals. If you wish element comparisons, use `sameElements` instead.
*/
@deprecated override def equals(that: Any): Boolean = that match {
case other: Set[_] =>
this.size == other.size && subsetOf(other.asInstanceOf[Set[A]])
case _ =>
false
}
/* @deprecated hashCode is not stable for mutable sets.
* if you intend to have object identity hashCode and wish the deprecated warning
* to go away, cast this set to AnyRef before calling hashCode.
*/
@deprecated override def hashCode() =
(0 /: this)((hash, e) => hash + e.hashCode())
/** Defines the prefix of this object's <code>toString</code> representation.
*/
override def stringPrefix: String = "Set"
/** Need to override string, so that it's not the Function1's string that gets mixed in.
*/
override def toString = super[OrderedIterableTemplate].toString
}
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