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package scalaz.stream

import scala.annotation.tailrec
import java.util.concurrent.atomic.AtomicInteger

private[stream] object Util {

  implicit class AppendSyntax[A](val self: Vector[A]) extends AnyVal {

    /**
     * Helper to fix performance issue on Vector append Seq
     * hopefully this can be removed in scala 2.11
     */
    def fast_++[B >: A](other: Seq[B]): Vector[B] = {
      @tailrec
      def append(acc:Vector[B], rem:Seq[B]) : Vector[B] = {
      //  debug(s"AP: self: ${self.size} other: ${other.size}")
        if (rem.nonEmpty) append(acc :+ rem.head, rem.tail)
        else acc
      }

      @tailrec
      def prepend(acc:Vector[B], rem:Seq[B]) : Vector[B] = {
        if (rem.nonEmpty) prepend(rem.last +: acc, rem.init)
        else acc
      }

      if (self.size < other.size) prepend(other.toVector,self)
      else append(self.toVector, other)
    }
  }


  /**
   * Helper to wrap evaluation of `p` that may cause side-effects by throwing exception.
   */
  private[stream] def Try[F[_], A](p: => Process[F, A]): Process[F, A] =
    try p
    catch {case e: Throwable => Process.fail(e)}



}