huynhjl

import scala.util.continuations._

class Generator[A] extends Iterator[A] with (A => Unit @ suspendable) {
  private var a: Option[A] = None
  private var k: Option[Unit => Unit] = None

  def next = {
    val a0 = a.get
    val k0 = k.get
    a = None

huynhjl

/**
 * An iterator that allows retrieving elements ahead without advancing the iterator.
 */
class LookAheadIterator[T](underlying:Iterator[T]) extends BufferedIterator[T] {
  
  private val queue = collection.mutable.Queue[T]()
  
  /**
   * Returns a new iterator to read ahead element. 
   * Elements from underlying are queued so that they can be returned by the

huynhjl

// Borrowed from 
// http://stackoverflow.com/questions/3102872/what-is-the-fastest-way-to-sum-a-collection-in-scala/3103800#3103800

def time[F](f: => F) = {
  val t0 = System.nanoTime
  val ans = f
  printf("Elapsed: %.3f\n",1e-9*(System.nanoTime-t0))
  ans
}

huynhjl

import scala.annotation._

val l = 0 until 30 toList

def div(i:Int) = i / 2

def cluster[T,U](xs:Seq[T], f:T => U): Seq[(U, Seq[T])] = {
  @tailrec 
  def tr_cluster(acc: Seq[(U, Seq[T])], xs:Seq[T]): Seq[(U, Seq[T])] = {
    if (xs.isEmpty) {

huynhjl

// The continuation code is from an answer by Rich posted at StackOverflow
// http://stackoverflow.com/questions/2201882/implementing-yield-yield-return-using-scala-continuations/2215182#2215182 

import scala.continuations._
import scala.continuations.ControlContext.{shift,reset}


sealed trait Iteration[+R]
case class Yield[+R](result: R, next: () => Iteration[R]) extends Iteration[R]
case object Done extends Iteration[Nothing]

huynhjl

// The continuation code is from an answer by Rich posted at StackOverflow
// http://stackoverflow.com/questions/2201882/implementing-yield-yield-return-using-scala-continuations/2215182#2215182 
// The printClass example is from this question http://stackoverflow.com/questions/2137619/scala-equivalent-to-python-generators

import scala.continuations._
import scala.continuations.ControlContext.{shift,reset}


sealed trait Iteration[+R]
case class Yield[+R](result: R, next: () => Iteration[R]) extends Iteration[R]

huynhjl

def yieldClass2(clazz:Class[_]): Iterator[Class[_]] = {
  import scala.collection.{Iterator => I}
  clazz match {
    case null => I.empty
    case _ =>
      val interfaces = clazz.getInterfaces map { yieldClass2 } reduceLeft (_ ++ _)
      I.single(clazz) ++ yieldClass2(clazz.getSuperclass) ++ interfaces
  }
}

huynhjl

import scala.xml.pull._
import scala.xml.UnprefixedAttribute
import scala.collection.mutable.ListBuffer
import scala.collection.mutable.Stack
import scala.io.Source

class Joint(name:String) {
  val joints = ListBuffer[Joint]()
  def addJoint(joint:Joint) {
    joints += joint