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Diffstat (limited to 'src/library/scala/collection/GenSetLike.scala')
| -rw-r--r-- | src/library/scala/collection/GenSetLike.scala | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/src/library/scala/collection/GenSetLike.scala b/src/library/scala/collection/GenSetLike.scala new file mode 100644 index 0000000000..d45810d2e7 --- /dev/null +++ b/src/library/scala/collection/GenSetLike.scala @@ -0,0 +1,131 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2003-2011, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +\* */ + +package scala.collection + +/** A template trait for sets which may possibly + * have their operations implemented in parallel. + * + * @define Coll GenSet + * @define coll general set + * @author Martin Odersky + * @author Aleksandar Prokopec + * @since 2.9 + * @define setNote + * + * A set is a collection that contains no duplicate elements. + */ +private[collection] trait GenSetLike[A, +Repr] + extends GenIterableLike[A, Repr] + with (A => Boolean) + with Equals + with Parallelizable[A, parallel.ParSet[A]] { + + def iterator: Iterator[A] + def contains(elem: A): Boolean + def +(elem: A): Repr + def -(elem: A): Repr + + def seq: Set[A] + + /** Tests if some element is contained in this set. + * + * This method is equivalent to `contains`. It allows sets to be interpreted as predicates. + * @param elem the element to test for membership. + * @return `true` if `elem` is contained in this set, `false` otherwise. + */ + def apply(elem: A): Boolean = this contains elem + + /** Computes the intersection between this set and another set. + * + * @param that the set to intersect with. + * @return a new set consisting of all elements that are both in this + * set and in the given set `that`. + */ + def intersect(that: GenSet[A]): Repr = this filter that + + /** Computes the intersection between this set and another set. + * + * '''Note:''' Same as `intersect`. + * @param that the set to intersect with. + * @return a new set consisting of all elements that are both in this + * set and in the given set `that`. + */ + def &(that: GenSet[A]): Repr = this intersect that + + /** Computes the union between of set and another set. + * + * @param that the set to form the union with. + * @return a new set consisting of all elements that are in this + * set or in the given set `that`. + */ + def union(that: GenSet[A]): Repr + + /** Computes the union between this set and another set. + * + * '''Note:''' Same as `union`. + * @param that the set to form the union with. + * @return a new set consisting of all elements that are in this + * set or in the given set `that`. + */ + def | (that: GenSet[A]): Repr = this union that + + /** Computes the difference of this set and another set. + * + * @param that the set of elements to exclude. + * @return a set containing those elements of this + * set that are not also contained in the given set `that`. + */ + def diff(that: GenSet[A]): Repr + + /** The difference of this set and another set. + * + * '''Note:''' Same as `diff`. + * @param that the set of elements to exclude. + * @return a set containing those elements of this + * set that are not also contained in the given set `that`. + */ + def &~(that: GenSet[A]): Repr = this diff that + + /** Tests whether this set is a subset of another set. + * + * @param that the set to test. + * @return `true` if this set is a subset of `that`, i.e. if + * every element of this set is also an element of `that`. + */ + def subsetOf(that: GenSet[A]): Boolean = this forall that + + /** Compares this set with another object for equality. + * + * '''Note:''' This operation contains an unchecked cast: if `that` + * is a set, it will assume with an unchecked cast + * that it has the same element type as this set. + * Any subsequent ClassCastException is treated as a `false` result. + * @param that the other object + * @return `true` if `that` is a set which contains the same elements + * as this set. + */ + override def equals(that: Any): Boolean = that match { + case that: GenSet[_] => + (this eq that) || + (that canEqual this) && + (this.size == that.size) && + (try this subsetOf that.asInstanceOf[GenSet[A]] + catch { case ex: ClassCastException => false }) + case _ => + false + } + + // Careful! Don't write a Set's hashCode like: + // override def hashCode() = this map (_.hashCode) sum + // Calling map on a set drops duplicates: any hashcode collisions would + // then be dropped before they can be added. + // Hash should be symmetric in set entries, but without trivial collisions. + override def hashCode() = util.MurmurHash.symmetricHash(seq, Set.hashSeed) + +} |