Scala example source code file (Subtractable.scala)

This example Scala source code file (Subtractable.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

a, gentraversableonce, repr, subtractable

The Subtractable.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */


package scala
package collection
package generic


/** This trait represents collection-like objects that can be reduced
 *  using a '+' operator. It defines variants of `-` and `--`
 *  as convenience methods in terms of single-element removal `-`.
 *  @tparam   A    the type of the elements of the $coll.
 *  @tparam   Repr the type of the $coll itself
 *  @author   Martin Odersky
 *  @version  2.8
 *  @since    2.8
 *  @define   coll collection
 *  @define   Coll Subtractable
 */
trait Subtractable[A, +Repr <: Subtractable[A, Repr]] { self =>

  /** The representation object of type `Repr` which contains the collection's elements
   */
  protected def repr: Repr

  /** Creates a new $coll from this $coll with an element removed.
   *  @param elem the element to remove
   *  @return a new collection that contains all elements of the current $coll
   *  except one less occurrence of `elem`.
   */
  def -(elem: A): Repr

  /** Creates a new $coll from this $coll with some elements removed.
   *
   *  This method takes two or more elements to be removed. Another overloaded
   *  variant of this method handles the case where a single element is
   *  removed.
   *  @param elem1 the first element to remove.
   *  @param elem2 the second element to remove.
   *  @param elems the remaining elements to remove.
   *  @return a new $coll that contains all elements of the current $coll
   *  except one less occurrence of each of the given elements.
   */
  def -(elem1: A, elem2: A, elems: A*): Repr =
    this - elem1 - elem2 -- elems

  /** Creates a new $coll from this $coll by removing all elements of another
   *  collection.
   *
   *  @param xs     the collection containing the removed elements.
   *  @return a new $coll that contains all elements of the current $coll
   *  except one less occurrence of each of the elements of `elems`.
   */
  def --(xs: GenTraversableOnce[A]): Repr = (repr /: xs.seq) (_ - _)
}