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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2010, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection
package mutable
import generic._
import immutable.{List, Nil}
// !!! todo: convert to LinkedListBuffer?
/**
* This class is used internally to represent mutable lists. It is the
* basis for the implementation of the classes
* `Stack`, and `Queue`.
*
* @author Matthias Zenger
* @author Martin Odersky
* @version 2.8
* @since 1
*/
@serializable @SerialVersionUID(5938451523372603072L)
class MutableList[A] extends LinearSeq[A]
with LinearSeqOptimized[A, MutableList[A]]
with Builder[A, MutableList[A]] {
override protected[this] def newBuilder = new MutableList[A]
protected var first0: LinkedList[A] = new LinkedList[A]
protected var last0: LinkedList[A] = _ // undefined if first0.isEmpty
protected var len: Int = 0
/** Is the list empty?
*/
override def isEmpty = len == 0
/** Returns the first element in this list
*/
override def head: A = first0.head
/** Returns the rest of this list
*/
override def tail: MutableList[A] = {
require(nonEmpty, "tail of empty list")
val tl = new MutableList[A]
tl.first0 = first0.tail
tl.last0 = last0
tl.len = len - 1
tl
}
/** Returns the length of this list.
*/
override def length: Int = len
/** Returns the <code>n</code>th element of this list.
* @throws IndexOutofBoundsException if index does not exist.
*/
override def apply(n: Int): A = first0.apply(n)
/** Updates the <code>n</code>th element of this list to a new value.
* @throws IndexOutofBoundsException if index does not exist.
*/
def update(n: Int, x: A): Unit = first0.update(n, x)
/** Returns the <code>n</code>th element of this list or <code>None</code>
* if index does not exist.
*/
def get(n: Int): Option[A] = first0.get(n)
protected def prependElem(elem: A) {
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]
last0 = last0.next
last0.elem = elem
last0.next = new LinkedList[A] // for performance, use sentinel `object' instead?
len = len + 1
}
@deprecated("use clear instead")
def reset() { clear() }
/** Returns an iterator over all elements of this list.
*/
override def iterator: Iterator[A] = first0.iterator
override def last = {
if (isEmpty) throw new NoSuchElementException("MutableList.empty.last")
last0.elem
}
/** Returns an instance of <code>scala.List</code> containing the same
* sequence of elements.
*/
override def toList: List[A] = first0.toList
/** Returns the current list of elements as a linked List
* sequence of elements.
*/
private[mutable] def toLinkedList: LinkedList[A] = first0
/** Appends a single element to this buffer. This takes constant time.
*
* @param elem the element to append.
*/
def +=(elem: A): this.type = { appendElem(elem); this }
def clear() {
first0 = new LinkedList[A]
last0 = first0
len = 0
}
def result = this
}
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