Scala example source code file (Growable.scala)

This example Scala source code file (Growable.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, annotation, clearable, growable, traversableonce, unit

The Growable.scala Scala example source code

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

package scala
package collection
package generic

import scala.annotation.tailrec

/** This trait forms part of collections that can be augmented
 *  using a `+=` operator and that can be cleared of all elements using
 *  a `clear` method.
 *
 *  @author   Martin Odersky
 *  @version 2.8
 *  @since   2.8
 *  @define coll growable collection
 *  @define Coll `Growable`
 *  @define add  add
 *  @define Add  add
 */
trait Growable[-A] extends Clearable {

  /** ${Add}s a single element to this $coll.
   *
   *  @param elem  the element to $add.
   *  @return the $coll itself
   */
  def +=(elem: A): this.type

  /** ${Add}s two or more elements to this $coll.
   *
   *  @param elem1 the first element to $add.
   *  @param elem2 the second element to $add.
   *  @param elems the remaining elements to $add.
   *  @return the $coll itself
   */
  def +=(elem1: A, elem2: A, elems: A*): this.type = this += elem1 += elem2 ++= elems

  /** ${Add}s all elements produced by a TraversableOnce to this $coll.
   *
   *  @param xs   the TraversableOnce producing the elements to $add.
   *  @return  the $coll itself.
   */
  def ++=(xs: TraversableOnce[A]): this.type = {
    @tailrec def loop(xs: scala.collection.LinearSeq[A]) {
      if (xs.nonEmpty) {
        this += xs.head
        loop(xs.tail)
      }
    }
    xs match {
      case xs: scala.collection.LinearSeq[_] => loop(xs)
      case xs                                => xs foreach +=
    }
    this
  }

  /** Clears the $coll's contents. After this operation, the
   *  $coll is empty.
   */
  def clear(): Unit
}