Scala example source code file (Reactions.scala)

This example Scala source code file (Reactions.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

buffer, event, event, impl, listbuffer, proxy, reaction, reaction, reactions, reactions, stronglyreferenced, stronglyreferenced, unit, wrapper

The Scala Reactions.scala source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2007-2011, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */



package scala.swing

import event.Event
import scala.collection.mutable.{Buffer, ListBuffer}

object Reactions {
  import scala.ref._
  
  class Impl extends Reactions {
    private val parts: Buffer[Reaction] = new ListBuffer[Reaction]
    def isDefinedAt(e: Event) = parts.exists(_ isDefinedAt e)
    def += (r: Reaction): this.type = { parts += r; this }
    def -= (r: Reaction): this.type = { parts -= r; this }
    def apply(e: Event) {
      for (p <- parts) if (p isDefinedAt e) p(e)
    }
  }
  
  type Reaction = PartialFunction[Event, Unit]
  
  /**
   * A Reaction implementing this trait is strongly referenced in the reaction list
   */
  trait StronglyReferenced
  
  class Wrapper(listener: Any)(r: Reaction) extends Reaction with StronglyReferenced with Proxy {
    def self = listener
    def isDefinedAt(e: Event) = r.isDefinedAt(e)
    def apply(e: Event) { r(e) }
  }
}

/**
 * Used by reactors to let clients register custom event reactions.
 */
abstract class Reactions extends Reactions.Reaction {
  /**
   * Add a reaction.
   */
  def += (r: Reactions.Reaction): this.type

  /**
   * Remove the given reaction.
   */
  def -= (r: Reactions.Reaction): this.type
}