path: root/sources/scala/collection/mutable/DefaultMapModel.scala

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2004, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |                                         **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
** $Id$
\*                                                                      */

package scala.collection.mutable;


/** This trait is used internally. It implements the mutable <code>Map</code>
 *  trait in terms of three functions: <code>findEntry</code>, <code>addEntry</code>,
 *  and <code>entries</code>.
 *
 *  @author  Matthias Zenger
 *  @version 1.0, 08/07/2003
 */
trait DefaultMapModel[A, B] extends scala.collection.mutable.Map[A, B] {

    protected def findEntry(key: A): Option[Entry];

    protected def addEntry(e: Entry): Unit;

    protected def entries: Iterator[Entry];

    def get(key: A) = findEntry(key) match {
        case None => None
        case Some(e) => Some(e.value);
    }

    def update(key: A, value: B) = findEntry(key) match {
        case None => addEntry(new Entry(key, value));
        case Some(e) => e.value = value;
    }

    def elements = new Iterator[Pair[A, B]] {
        val iter = entries;
        def hasNext = iter.hasNext;
        def next = iter.next.toPair;
    }

    protected class Entry(k: A, v: B) with java.io.Serializable {
        def key = k;
        var value = v;
        def toPair = Pair(k, value);
        override def toString() = k.toString() + " -> " + value;
    }

}