Scala example source code file (SortedMapLike.scala)

This example Scala source code file (SortedMapLike.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

a, a, b, b, b1, b1, defaultkeysortedset, maplike, option, sortedmap, sortedmaplike, sortedset, sortedset, this

The Scala SortedMapLike.scala source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2006-2011, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */



package scala.collection

import generic._

/** A template for maps whose keys are sorted.
 *  To create a concrete sorted map, you need to implement the rangeImpl method,
 *  in addition to those of `MapLike`.
 *
 *  @author Sean McDirmid
 *  @author Martin Odersky
 *  @version 2.8
 *  @since   2.8
 */
trait SortedMapLike[A, +B, +This <: SortedMapLike[A, B, This] with SortedMap[A, B]] extends Sorted[A, This] with MapLike[A, B, This] { 
self =>

  def firstKey : A = head._1
  def lastKey : A = last._1

  implicit def ordering: Ordering[A]

  // XXX: implement default version
  def rangeImpl(from : Option[A], until : Option[A]) : This

  override def keySet : SortedSet[A] = new DefaultKeySortedSet

  protected class DefaultKeySortedSet extends super.DefaultKeySet with SortedSet[A] {
    implicit def ordering = self.ordering
    override def + (elem: A): SortedSet[A] = (SortedSet[A]() ++ this + elem)
    override def - (elem: A): SortedSet[A] = (SortedSet[A]() ++ this - elem)
    override def rangeImpl(from : Option[A], until : Option[A]) : SortedSet[A] = {
      val map = self.rangeImpl(from, until)
      new map.DefaultKeySortedSet
    }
  }

  /** Add a key/value pair to this map. 
   *  @param    key the key
   *  @param    value the value
   *  @return   A new map with the new binding added to this map
   */
  override def updated[B1 >: B](key: A, value: B1): SortedMap[A, B1] = this+((key, value))

  /** Add a key/value pair to this map. 
   *  @param    kv the key/value pair
   *  @return   A new map with the new binding added to this map
   */
  def + [B1 >: B] (kv: (A, B1)): SortedMap[A, B1]

  // todo: Add generic +,-, and so on.

  /** Adds two or more elements to this collection and returns
   *  either the collection itself (if it is mutable), or a new collection
   *  with the added elements.
   *
   *  @param elem1 the first element to add.
   *  @param elem2 the second element to add.
   *  @param elems the remaining elements to add.
   */
  override def + [B1 >: B] (elem1: (A, B1), elem2: (A, B1), elems: (A, B1) *): SortedMap[A, B1] = {
    var m = this + elem1 + elem2;
    for (e <- elems) m = m + e
    m
  }
}