observablebuffer.scala

来自「JAVA 语言的函数式编程扩展」· SCALA 代码 · 共 83 行

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2006, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |                                         **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

// $Id: ObservableBuffer.scala 11911 2007-06-05 15:57:59Z odersky $


package scala.collection.mutable


//import Predef.UnsupportedOperationException

/** This class is typically used as a mixin. It adds a subscription
 *  mechanism to the <code>Buffer</code> class into which this abstract
 *  class is mixed in. Class <code>ObservableBuffer</code> publishes
 *  events of the type <code>Message</code>.
 *
 *  @author  Matthias Zenger
 *  @version 1.0, 08/07/2003
 */
trait ObservableBuffer[A, This <: ObservableBuffer[A, This]] 
      extends Buffer[A]
      with Publisher[Message[(Location, A)]
      with Undoable, This]
{ self: This =>

  abstract override def +(element: A): Buffer[A] = {
    super.+(element)
    publish(new Include((End, element)) with Undoable {
      def undo() { trimEnd(1) }
    })
    this
  }

  abstract override def +:(element: A): Buffer[A] = {
    super.+:(element);
    publish(new Include((Start, element)) with Undoable {
      def undo() { trimStart(1) }
    })
    this
  }

  abstract override def insertAll(n: Int, iter: Iterable[A]): Unit = {
    super.insertAll(n, iter)
    var i = n
    val it = iter.elements
    while (it.hasNext) {
      publish(new Include((Index(i), it.next)) with Undoable {
        def undo { remove(i) }
      })
      i = i + 1
    }
  }

  abstract override def update(n: Int, newelement: A): Unit = {
    val oldelement = apply(n)
    super.update(n, newelement)
    publish(new Update((Index(n), newelement)) with Undoable {
      def undo { update(n, oldelement) }
    })
  }

  abstract override def remove(n: Int): A = {
    val oldelement = apply(n)
    super.remove(n)
    publish(new Remove((Index(n), oldelement)) with Undoable {
      def undo { insert(n, oldelement) }
    })
    oldelement
  }

  abstract override def clear(): Unit = {
    super.clear
    publish(new Reset with Undoable { 
      def undo { throw new UnsupportedOperationException("cannot undo") }
    })
  }
}