src/compiler/scala/tools/nsc/backend/WorklistAlgorithm.scala


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/* NSC -- new scala compiler
 * Copyright 2005 LAMP/EPFL
 * @author  Martin Odersky
 */

// $Id$

package scala.tools.nsc.backend;

import scala.tools.nsc.ast._;
import scala.collection.mutable.MutableList;

/**
 * Simple implementation of a worklist algorithm. A processing
 * function is applied repeatedly to the first element in the
 * worklist, as long as the stack is not empty.
 *
 * The client class should mix-in this trait and initialize the
 * worklist field and define the processElement method. Then call
 * the 'run' method providing a function that initializes the
 * worklist.
 *
 * @see scala.tools.nsc.backend.icode.Linearizers
 */
trait WorklistAlgorithm {
  type Elem;
  type WList <: MutableList[Elem];

  val worklist: WList;

  /**
   * Run the iterative algorithm until the worklist
   * remains empty. The initializer is run once before
   * the loop starts and should initialize the worklist.
   */
  def run(initWorklist: => Unit) = {
    initWorklist;

    while (!(worklist.length == 0))
      processElement(dequeue);
  }

  /**
   * Process the current element from the worklist.
   */
  def processElement(e: Elem): Unit;

  /** Remove and return the first element to be processed from the worklist. */
  def dequeue: Elem;
}