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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection.mutable
//import Predef.NoSuchElementException
/** This class is used internally to represent mutable lists. It is the
* basis for the implementation of the classes <code>Buffer</code>,
* <code>Stack</code>, and <code>Queue</code>.
*
* @author Matthias Zenger
* @version 1.0, 08/07/2003
*/
trait MutableList[A] extends Seq[A] with PartialFunction[Int, A] {
protected var first0: LinkedList[A] = null
protected var last0: LinkedList[A] = null
protected var len: Int = 0
/** Returns the length of this list.
*/
def length: Int = len
/** Returns the <code>n</code>th element of this list. This method
* yields an error if the element does not exist.
*/
def apply(n: Int): A = get(n) match {
case None => throw new NoSuchElementException("element not found")
case Some(value) => value
}
/** Returns the <code>n</code>th element of this list or <code>None</code>
* if this element does not exist.
*/
def get(n: Int): Option[A] = first0.get(n)
protected def prependElem(elem: A): Unit = {
first0 = new LinkedList[A](elem, first0)
if (len == 0)
last0 = first0
len = len + 1
}
protected def appendElem(elem: A): Unit =
if (len == 0)
prependElem(elem)
else {
last0.next = new LinkedList[A](elem, null)
last0 = last0.next
len = len + 1
}
protected def reset() {
first0 = null
last0 = null
len = 0
}
/** Returns an iterator over all elements of this list.
*/
override def elements: Iterator[A] =
if (first0 eq null) Nil.elements else first0.elements
override def last = last0.elem
/** Returns an instance of <code>scala.List</code> containing the same
* sequence of elements.
*/
override def toList: List[A] = if (first0 eq null) Nil else first0.toList
override protected def stringPrefix: String = "MutableList"
}
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